Lung-delivered IL-10 therapy elicits beneficial effects via immune modulation in organic dust exposure-induced lung inflammation

Efficacious therapeutic options capable of resolving inflammatory lung disease associated with environmental and occupational exposures are lacking. This study sought to determine the preclinical therapeutic potential of lung-delivered recombinant interleukin (IL)-10 therapy following acute organic dust exposure in mice. Here, C57BL/6J mice were intratracheally instilled with swine confinement organic dust extract (ODE) (12.5%, 25%, 50% concentrations) with IL-10 (1 μg) treatment or vehicle control intratracheally-administered three times: 5 hr post-exposure and then daily for 2 days. The results showed that IL-10 treatment reduced ODE (25%)-induced weight loss by 66% and 46% at Day 1 and Day 2 post-exposure, respectively. IL-10 treatment reduced ODE (25%, 50%)-induced lung levels of TNFα (-76%, -83% [reduction], respectively), neutrophil chemoattractant CXCL1 (-51%, -60%), and lavage fluid IL-6 (-84%, -89%). IL-10 treatment reduced ODE (25%, 50%)-induced lung neutrophils (-49%, -70%) and recruited CD11cintCD11b+ monocyte-macrophages (-49%, -70%). IL-10 therapy reduced ODE-associated expression of antigen presentation (MHC Class II, CD80, CD86) and inflammatory (Ly6C) markers and increased anti-inflammatory CD206 expression on CD11cintCD11b+ cells. ODE (12.5%, 25%)-induced lung pathology was also reduced with IL-10 therapy. In conclusion, the studies here showed that short-term, lung-delivered IL-10 treatment induced a beneficial response in reducing inflammatory consequences (that were also associated with striking reduction in recruited monocyte-macrophages) following acute complex organic dust exposure.

Targeting transitioning lung monocytes/macrophages as treatment strategies in lung disease related to environmental exposures

BACKGROUND

Environmental/occupational exposures cause significant lung diseases. Agricultural organic dust extracts (ODE) and bacterial component lipopolysaccharide (LPS) induce recruited, transitioning murine lung monocytes/macrophages, yet their cellular role remains unclear.

METHODS

CCR2 RFP+ mice were intratracheally instilled with high concentration ODE (25%), LPS (10 μg), or gram-positive peptidoglycan (PGN, 100 μg) for monocyte/macrophage cell-trafficking studies. CCR2 knockout (KO) mice and administration of intravenous clodronate liposomes strategies were employed to reduce circulating monocytes available for lung recruitment following LPS exposure. Lung tissues and bronchoalveolar lavage fluid (BALF) were collected. Pro-inflammatory and/or pro-fibrotic cytokines, chemokines, and lung extracellular matrix mediators were quantitated by ELISA. Infiltrating lung cells including monocyte/macrophage subpopulations, neutrophils, and lymphocytes were characterized by flow cytometry. Lung histopathology, collagen content, vimentin, and post-translational protein citrullination and malondialdehyde acetaldehyde (MAA) modification were quantitated. Parametric statistical tests (one-way ANOVA, Tukey'smultiple comparison) and nonparametric statistical (Kruskal-Wallis, Dunn's multiple comparison) tests were used following Shapiro-Wilk testing for normality.

RESULTS

Intratracheal instillation of ODE, LPS, or PGN robustly induced the recruitment of inflammatory CCR2+ CD11cintCD11bhi monocytes/macrophages and both CCR2+ and CCR2- CD11c-CD11bhi monocytes at 48 h. There were also increases in CCR2+ CD4+ and CD8+ T cells and NK cells. Despite reductions in LPS-induced lung infiltrating CD11cintCD11bhi cells (54% reduction), CCR2 knockout (KO) mice were not protected against LPS-induced inflammatory and pro-fibrotic consequences. Instead, compensatory increases in lung neutrophils and CCL2 and CCL7 release occurred. In contrast, the depletion of circulating monocytes through the administration of intravenous clodronate (vs. vehicle) liposomes 24 h prior to LPS exposure reduced LPS-induced infiltrating CD11cintCD11bhi monocyte-macrophage subpopulation by 59% without compensatory changes in other cell populations. Clodronate liposome pre-treatment significantly reduced LPS-induced IL-6 (66% reduction), matrix metalloproteinases (MMP)-3 (36%), MMP-8 (57%), tissue inhibitor of metalloproteinases (61%), fibronectin (38%), collagen content (22%), and vimentin (40%). LPS-induced lung protein citrullination and MAA modification, post-translational modifications implicated in lung disease, were reduced (39% and 48%) with clodronate vs. vehicle liposome.

CONCLUSION

Highly concentrated environmental/occupational exposures induced the recruitment of CCR2+ and CCR2- transitioning monocyte-macrophage and monocyte subpopulations and targeting peripheral monocytes may reduce the adverse lung consequences resulting from exposures to LPS-enriched inhalants.

Expansion of distinct peripheral blood myeloid cell subpopulations in patients with rheumatoid arthritis-associated interstitial lung disease

OBJECTIVES

Interstitial lung disease (ILD) is associated with significant mortality in rheumatoid arthritis (RA) patients with key cellular players remaining largely unknown. This study aimed to characterize inflammatory and myeloid derived suppressor cell (MDSC) subpopulations in RA-ILD as compared to RA, idiopathic pulmonary fibrosis (IPF) without autoimmunity, and controls.

METHODS

Peripheral blood was collected from patients with RA, RA-ILD, IPF, and controls (N = 60, 15/cohort). Myeloid cell subpopulations were identified phenotypically by flow cytometry using the following markers:CD45,CD3,CD19,CD56,CD11b,HLA-DR,CD14,CD16,CD15,CD125,CD33. Functionality of subsets were identified with intracellular arginase-1 (Arg-1) and inducible nitric oxide synthase (iNOS) expression.

RESULTS

There was increased intermediate (CD14++CD16+) and nonclassical (CD14+/-CD16++) and decreased classical (CD14++CD16-) monocytes in RA, RA-ILD, and IPF vs. control. Intermediate monocytes were higher and classical monocytes were lower in RA-ILD vs. RA but not IPF. Monocytic (m)MDSCs were higher in RA-ILD vs. control and RA but not IPF. Granulocytic (g)MDSCs did not significantly differ. In contrast, neutrophils were increased in IPF and RA-ILD patients with elevated expression of Arg-1 sharing similar dimensional clustering pattern. Eosinophils were increased in RA-ILD vs. controls, RA and IPF. Across cohorts, iNOS was decreased in intermediate/nonclassical monocytes but increased in mMDSCs vs. classical monocytes. In RA-ILD, iNOS positive mMDSCs were increased versus classic monocytes.

CONCLUSIONS

Myeloid cell subpopulations are significantly modulated in RA-ILD patients with expansion of CD16+ monocytes, mMDSCs, and neutrophils, a phenotypic profile more aligned with IPF than other RA patients. Eosinophil expansion was unique to RA-ILD, potentially facilitating disease pathogenesis and providing a future therapeutic target.

Citrullinated and malondialdehyde-acetaldehyde modified fibrinogen activates macrophages and promotes an aggressive synovial fibroblast phenotype in patients with rheumatoid arthritis

Objective

Post-translational protein modifications with malondialdehyde-acetaldehyde (MAA) and citrulline (CIT) are implicated in the pathogenesis of rheumatoid arthritis (RA). Although precise mechanisms have not been elucidated, macrophage-fibroblast interactions have been proposed to play a central role in the development and progression of RA. The purpose of our study was to evaluate the downstream effects of macrophage released soluble mediators, following stimulation with fibrinogen (FIB) modified antigens, on human fibroblast-like synoviocytes (HFLS).

Methods

PMA-treated U-937 monocytes (Mϕ) and macrophage-differentiated peripheral blood mononuclear cells (MP) were stimulated with FIB, FIB-MAA, FIB-CIT, or FIB-MAA-CIT. HFLS-RA cells were stimulated directly with FIB antigens or with supernatants (SN) from macrophages (Mϕ-SN or MP-SN) stimulated with FIB antigens. Genes associated with an aggressive HFLS phenotype, extracellular matrix proteins, and activated signaling pathways were evaluated.

Results

HFLS-RA cells treated with Mϕ-SNFIB-CIT and Mϕ-SNFIB-MAA-CIT demonstrated significant increases in mRNA expression of genes associated with an aggressive phenotype at 24-h as compared to direct stimulation with the same antigens. Similar results were obtained using MP-SN. Cellular morphology was altered and protein expression of vimentin (p<0.0001 vs. Mϕ-SNFIB) and type II collagen (p<0.0001) were significantly increased in HFLS-RA cells treated with any of the Mϕ-SN generated following stimulation with modified antigens. Phosphorylation of JNK, Erk1/2, and Akt were increased most substantially in HFLS-RA treated with Mϕ-SNFIB-MAA-CIT (p<0.05 vs Mϕ-SNFIB). These and other data suggested the presence of PDGF-BB in Mϕ-SN. Mϕ-SNFIB-MAA-CIT contained the highest concentration of PDGF-BB (p<0.0001 vs. Mϕ-SNFIB) followed by Mϕ-SNFIB-CIT then Mϕ-SNFIB-MAA. HFLS-RA cells treated with PDGF-BB showed similar cellular morphology to the Mϕ-SN generated following stimulation with modified FIB, as well as the increased expression of vimentin, type II collagen, and the phosphorylation of JNK, Erk1/2 and Akt signaling molecules.

Conclusion

Together, these findings support the hypothesis that in response to MAA-modified and/or citrullinated fibrinogen, macrophages release soluble factors including PDGF-BB that induce fibroblast activation and promote an aggressive fibroblast phenotype. These cellular responses were most robust following macrophage activation with dually modified fibrinogen, compared to single modification alone, providing novel insights into the combined role of multiple post-translational protein modifications in the development of RA.

Agricultural dust derived bacterial extracellular vesicle mediated inflammation is attenuated by DHA

Dietary long-chain omega-3 polyunsaturated fatty acids (n-3 PUFA) and their pro-resolving metabolites are protective against atherosclerotic disease, and ameliorate systemic inflammatory conditions including lupus erythematosus, psoriasis, and bronchial asthma. Organic bioaerosol inhalation is a common and injurious hazard associated with agricultural occupations such as work in swine concentrated animal feeding operations (CAFOs) and is known to increase the risk for developing respiratory conditions such as asthma and COPD. Nearly all cells secrete membrane-bound vesicles (extracellular vesicles, EVs) that have the capacity to transmit protein, nucleic acid, and lipid signaling mediators between cells. Using a polymer-based isolation technique (ExoQuick, PEG) followed by ultracentrifugation, EVs were isolated from CAFO dust extracts, and were quantified and partially characterized. Here, we investigated the role of the n-3 PUFA docosahexaenoic acid (DHA) as a component of n-6 to n-3 PUFA mixtures used to recapitulate physiologically relevant dietary ratios in the resolution of inflammatory injury caused by exposure to EVs carried by agricultural organic dust in vitro. Primary human bronchial epithelial cells, fibroblasts and monocyte-derived macrophages were exposed to EVs isolated from swine CAFO dust. Cells were treated with mixtures of n-6 and n-3 PUFA during recovery from the EV-induced injury. CAFO dust extract (DE) was found to contain EVs that contributed significantly to the overall consequences of exposure to complete DE. DHA-rich PUFA ratios inhibited DE-derived EV-induced proinflammatory cytokine release dose-dependently. DHA-rich PUFA ratios also reversed the damaging effects of EVs on recellularization of lung matrix scaffolds, accelerated wound healing, and stimulated the release of pro-resolution mediators. These results underscore the importance of n-3 PUFA as anti-inflammatory compounds during recovery from EV-laden environmental dust exposure in the context of cellular responses in vitro, warranting future translational studies.

Post-endotoxin exposure-induced lung inflammation and resolution consequences beneficially impacted by lung-delivered IL-10 therapy

Although lung diseases typically result from long-term exposures, even a robust, one-time exposure can result in long-lasting consequences. Endotoxin is a ubiquitous environmental/occupational inflammatory agent often used to model airway inflammation. Using a murine model, the return to lung homeostasis following high dose inhalant lipopolysaccharide (LPS, 10-100 μg) exposure were delineated over 2 weeks. LPS-induced rapid weight loss, release of proinflammatory mediators, and inflammatory cell influx with prolonged persistence of activated macrophages CD11c⁺CD11b⁺ and recruited/transitioning CD11c^intCD11b⁺ monocyte-macrophages out to 2 weeks. Next, lung-delivered recombinant (r) interleukin (IL)-10 was intratracheally administered for 3 doses initiated 5 h following LPS (10 μg) exposure for 2 days. IL-10 therapy reduced LPS-induced weight loss and increased blood glucose levels. Whereas there was no difference in LPS-induced bronchoalveolar lavage airway fluid cellular influx, total lung cell infiltrates were reduced (37%) with rIL-10 treatment. Post-LPS exposure treatment with rIL-10 strikingly reduced lavage fluid and lung homogenate levels of tumor necrosis factor-α (88% and 93% reduction, respectively), IL-6 (98% and 94% reduction), CXCL1 (66% and 75% reduction), and CXCL2 (47% and 67% reduction). LPS-induced recruited monocyte-macrophages (CD11c^intCD11b⁺) were reduced (68%) with rIL-10. Correspondingly, LPS-induced lung tissue CCR2⁺ inflammatory monocyte-macrophage were reduced with rIL-10. There were also reductions in LPS-induced lung neutrophils, lymphocyte subpopulations, collagen content, and vimentin expression. These findings support the importance of studying resolution processes for the development of treatment after unintended environmental/occupational biohazard exposures. Short-term, lung-delivered rIL-10 favorably hastened inflammatory recovery processes following acute, high dose inhalant LPS exposure.

Peptidyl arginine deiminase expression and macrophage polarization following stimulation with citrullinated and malondialdehyde-acetaldehyde modified fibrinogen

OBJECTIVE

Post-translational modifications of extracellular matrix proteins such as fibrinogen may lead to tolerance loss and have been implicated in rheumatoid arthritis (RA) pathogenesis. The purpose of this study was to determine whether fibrinogen (FIB) modified with citrulline (CIT), malondialdehyde-acetaldehyde (MAA) or both leads to altered macrophage polarization, peptidyl arginine deiminase (PAD) expression, or production of citrullinated proteins.

METHODS

PMA-treated U-937 cells (M0 cells) were stimulated with MAA, CIT or MAA-CIT modified FIB. Macrophage (M1/M2) phenotypes were evaluated by flow cytometry, RT-PCR, and ELISA. PAD enzyme expression and protein citrullination was evaluated using RT-PCR and Western Blot.

RESULTS

Flow cytometry revealed that M0 macrophages stimulated with FIB-MAA-CIT resulted in mixed M1/M2 phenotypes as demonstrated by cell surface expression and mRNA levels of CD14, CD192, CD163, and CD206 (p < 0.001 vs. others), and the release of IL-18, IP-10, CCL22, and IL-13 (p < 0.001 vs. others). While FIB-MAA treated M0 cells demonstrated a mixed M1/M2 phenotype, cytokine and cell surface markers differed from FIB-MAA-CIT. Finally, M0 cells treated with FIB-CIT demonstrated markers and cytokines consistent with only the M1-like phenotype. Exposure of M0 cells to FIB-MAA-CIT (at 48 h) and FIB-MAA (at 24 h) led to increased mRNA expression and protein expression of PAD2 (p < 0.001) with increased protein citrullination.

CONCLUSION

These findings suggest that MAA-modification and citrullination of FIB, in isolation or combination, yield specific effects on macrophage polarization, PAD expression and citrullination that ultimately may induce inflammatory and fibrotic responses associated with RA.

Relationships of serum CC16 levels with smoking status and lung function in COPD

BACKGROUND

The club cell secretory protein (CC16) has anti-inflammatory and antioxidant effects, and low CC16 serum levels have been associated with both risk and progression of COPD, yet the interaction between smoking and CC16 on lung function outcomes remains unknown.

METHODS

Utilizing cross-sectional data on United States veterans, CC16 serum concentrations were measured by ELISA and log transformed for analyses. Spirometry was conducted and COPD status was defined by post-bronchodilator FEV₁/FVC ratio < 0.7. Smoking measures were self-reported on questionnaire. Multivariable logistic and linear regression were employed to examine associations between CC16 levels and COPD, and lung function with adjustment for covariates. Unadjusted Pearson correlations described relationships between CC16 level and lung function measures, pack-years smoked, and years since smoking cessation.

RESULTS

The study population (N = 351) was mostly male, white, with an average age over 60 years. An interaction between CC16 and smoking status on FEV₁/FVC ratio was demonstrated among subjects with COPD (N = 245, p = 0.01). There was a positive correlation among former smokers and negative correlation among current or never smokers with COPD. Among former smokers with COPD, CC16 levels were also positively correlated with years since smoking cessation, and inversely related with pack-years smoked. Increasing CC16 levels were associated with lower odds of COPD (OR_adj = 0.36, 95% CI 0.22-0.57, P_adj < 0.0001).

CONCLUSIONS

Smoking status is an important effect modifier of CC16 relationships with lung function. Increasing serum CC16 corresponded to increases in FEV₁/FVC ratio in former smokers with COPD versus opposite relationships in current or never smokers. Additional longitudinal studies may be warranted to assess relationship of CC16 with smoking cessation on lung function among subjects with COPD.

A high docosahexaenoic acid diet alters lung inflammation and recovery following repetitive exposure to aqueous organic dust extracts

Agricultural workers, especially those who work in swine confinement facilities, are at increased risk for developing pulmonary diseases including asthma, chronic obstructive pulmonary disease, and chronic bronchitis due to exposures to fumes, vapors, and organic dust. Repetitive exposure to agricultural dust leads to unresolved inflammation, a common underlying mechanism that worsens lung disease. Besides occupational exposure to dusts, diet also significantly contributes to inflammation and disease progression. Since DHA (docosahexaenoic acid), a polyunsaturated omega-3 fatty acid and its bioactive metabolites have key roles in inflammation resolution, we rationalized that individuals chronically exposed to organic dusts can benefit from dietary modifications. Here, we evaluated the role of DHA in modifying airway inflammation in a murine model of repetitive exposure to an aqueous extract of agricultural dust (three-week exposure to swine confinement dust extract, HDE) and after a one-week resolution/recovery period. We found that mice fed a high DHA diet had significantly increased bronchoalveolar lavage fluid (BALF) levels of DHA-derived resolvins and lower TNFα along with altered plasma levels of endocannabinoids and related lipid mediators. Following the one-week recovery we identified significantly reduced BALF cellularity and cytokine/chemokine release along with increased BALF amphiregulin and resolvins in DHA diet-fed versus control diet-fed mice challenged with HDE. We further report observations on the effects of repetitive HDE exposure on lung Ym1+ and Arg-1+ macrophages. Overall, our findings support a protective role for DHA and identify DHA-derived resolvins and endocannabinoids among the potential mediators of DHA in altering airway inflammation in chronic agricultural dust exposure.

The impact of airborne endotoxin exposure on rheumatoid arthritis-related joint damage, autoantigen expression, autoimmunity, and lung disease

Airborne biohazards are risk factors in the development and severity of rheumatoid arthritis (RA) and RA-associated lung disease, yet the mechanisms explaining this relationship remain unclear. Lipopolysaccharide (LPS, endotoxin) is a ubiquitous inflammatory agent in numerous environmental and occupational air pollutant settings recognized to induce airway inflammation. Combining repetitive LPS inhalation exposures with the collagen induced arthritis (CIA) model, DBA1/J mice were assigned to either: sham (saline injection/saline inhalation), CIA (CIA/saline), LPS (saline/LPS 100 ng inhalation), or CIA + LPS for 5 weeks. Serum anti-citrullinated (CIT) protein antibody (ACPA) and anti-malondialdehyde-acetaldehyde (MAA) antibodies were strikingly potentiated with co-exposure (CIA + LPS). CIT- and MAA-modified lung proteins were increased with co-exposure and co-localized across treatment groups. Inhaled LPS exacerbated arthritis with CIA + LPS > LPS > CIA versus sham. Periarticular bone loss was demonstrated in CIA and CIA + LPS but not in LPS alone. LPS induced airway inflammation and neutrophil infiltrates were reduced with co-exposure (CIA + LPS). Potentially signaling transition to pro-fibrotic processes, there were increased infiltrates of activated CD11c+CD11b+ macrophages and transitioning CD11c+CD11bint monocyte-macrophage populations with CIA + LPS. Moreover, several lung remodeling proteins including fibronectin and matrix metalloproteinases as well as complement C5a were potentiated with CIA + LPS compared to other treatment groups. IL-33 concentrations in lung homogenates were enhanced with CIA + LPS with IL-33 lung staining driven by LPS. IL-33 expression was also significantly increased in lung tissues from patients with RA-associated lung disease (N = 8) versus controls (N = 7). These findings suggest that patients with RA may be more susceptible to developing interstitial lung disease following airborne biohazard exposures enriched in LPS.

High-throughput analysis of lung immune cells in a combined murine model of agriculture dust-triggered airway inflammation with rheumatoid arthritis

Rheumatoid arthritis (RA)-associated lung disease is a leading cause of mortality in RA, yet the mechanisms linking lung disease and RA remain unknown. Using an established murine model of RA-associated lung disease combining collagen-induced arthritis (CIA) with organic dust extract (ODE)-induced airway inflammation, differences among lung immune cell populations were analyzed by single cell RNA-sequencing. Additionally, four lung myeloid-derived immune cell populations including macrophages, monocytes/macrophages, monocytes, and neutrophils were isolated by fluorescence cell sorting and gene expression was determined by NanoString analysis. Unsupervised clustering revealed 14 discrete clusters among Sham, CIA, ODE, and CIA+ODE treatment groups: 3 neutrophils (inflammatory, resident/transitional, autoreactive/suppressor), 5 macrophages (airspace, differentiating/recruited, recruited, resident/interstitial, and proliferative airspace), 2 T-cells (differentiating and effector), and a single cluster each of inflammatory monocytes, dendritic cells, B-cells and natural killer cells. Inflammatory monocytes, autoreactive/suppressor neutrophils, and recruited/differentiating macrophages were predominant with arthritis induction (CIA and CIA+ODE). By specific lung cell isolation, several interferon-related and autoimmune genes were disproportionately expressed among CIA and CIA+ODE (e.g. Oasl1, Oas2, Ifit3, Gbp2, Ifi44, and Zbp1), corresponding to RA and RA-associated lung disease. Monocytic myeloid-derived suppressor cells were reduced, while complement genes (e.g. C1s1 and Cfb) were uniquely increased in CIA+ODE mice across cell populations. Recruited and inflammatory macrophages/monocytes and neutrophils expressing interferon-, autoimmune-, and complement-related genes might contribute towards pro-fibrotic inflammatory lung responses following airborne biohazard exposures in setting of autoimmune arthritis and could be predictive and/or targeted to reduce disease burden.

Organic dust-induced lung injury and repair: Bi-directional regulation by TNFα and IL-10

Exposure to organic dust increases chronic airway inflammatory disorders. Effective treatment strategies are lacking. It has been reported that hog barn dust extracts (HDE) induce TNFα through protein kinase C (PKC) activation and that lung inflammation is enhanced in scavenger receptor A (SRA/CD204) knockout (KO) mice following HDE. Because interleukin (IL)-10 production can limit excessive inflammation, it was hypothesized here that HDE-induced IL-10 would require CD204 to effect inflammatory responses. C57BL/6 wild-type (WT), SRA KO, and IL-10 KO mice were intranasally challenged daily for 8 days with HDE and subsequently rested for 3 days with/without recombinant IL-10 (rIL-10) treatment. Primary peritoneal macrophages (PM) and murine alveolar macrophages (MH-S cells) were treated in vitro with HDE, SRA ligand (fucoidan), rIL-10, and/or PKC isoform inhibitors. HDE induced in vivo lung IL-10 in WT, but not SRA KO mice, and similar trends were demonstrated in isolated PM from same treated mice. Lung lymphocyte aggregates and neutrophils were elevated in in vivo HDE-treated SRA and IL-10 KO mice after a 3-d recovery, and treatment during recovery with rIL-10 abrogated these responses. In vitro rIL-10 treatment reduced HDE-stimulated TNFα release in MH-S and WT PM. In SRA KO macrophages, there was reduced IL-10 and PKC zeta (ζ) activity and increased TNFα following in vitro HDE stimulation. Similarly, blocking SRA (24 hr fucoidan pre-treatment) resulted in enhanced HDE-stimulated macrophage TNFα and decreased IL-10 and PKCζ activation. PKCζ inhibitors blocked HDE-stimulated IL-10, but not TNFα. Collectively, HDE stimulates IL-10 by an SRA- and PKCζ-dependent mechanism to regulate TNFα. Enhancing resolution of dust-mediated lung inflammation through targeting IL-10 and/or SRA may represent new approaches to therapeutic interventions.

Infliximab Treatment of Refractory Cardiac Sarcoidosis

Treatment of cardiac sarcoidosis is challenging, as the disease can be refractory to traditional treatment with steroids. Infliximab, a tumor necrosis factor-α inhibitor, has been reportedly used in cardiac sarcoidosis, but published evidence is limited. The potential cardiotoxicity of infliximab and the Food and Drug Administration black-box warning for patients with heart failure have hindered the use of this agent in cardiac sarcoidosis. Here, we report a case of refractory cardiac sarcoidosis successfully treated with infliximab and discuss the important role of fluorine-18–fluorodeoxyglucose positron emission tomography in prognostication and guidance of therapy. (Level of Difficulty: Intermediate.)

MyD88 regulates a prolonged adaptation response to environmental dust exposure-induced lung disease

BACKGROUND

Environmental organic dust exposures enriched in Toll-like receptor (TLR) agonists can reduce allergic asthma development but are associated with occupational asthma and chronic bronchitis. The TLR adaptor protein myeloid differentiation factor88 (MyD88) is fundamental in regulating acute inflammatory responses to organic dust extract (ODE), yet its role in repetitive exposures is unknown and could inform future strategies.

METHODS

Wild-type (WT) and MyD88 knockout (KO) mice were exposed intranasally to ODE or saline daily for 3 weeks (repetitive exposure). Repetitively exposed animals were also subsequently rested with no treatments for 4 weeks followed by single rechallenge with saline/ODE.

RESULTS

Repetitive ODE exposure induced neutrophil influx and release of pro-inflammatory cytokines and chemokines were profoundly reduced in MyD88 KO mice. In comparison, ODE-induced cellular aggregates, B cells, mast cell infiltrates and serum IgE levels remained elevated in KO mice and mucous cell metaplasia was increased. Expression of ODE-induced tight junction protein(s) was also MyD88-dependent. Following recovery and then rechallenge with ODE, inflammatory mediators, but not neutrophil influx, was reduced in WT mice pretreated with ODE coincident with increased expression of IL-33 and IL-10, suggesting an adaptation response. Repetitively exposed MyD88 KO mice lacked inflammatory responsiveness upon ODE rechallenge.

CONCLUSIONS

MyD88 is essential in mediating the classic airway inflammatory response to repetitive ODE, but targeting MyD88 does not reduce mucous cell metaplasia, lymphocyte influx, or IgE responsiveness. TLR-enriched dust exposures induce a prolonged adaptation response that is largely MyD88-independent. These findings demonstrate the complex role of MyD88-dependent signaling during acute vs. chronic organic dust exposures.

Amphiregulin modulates murine lung recovery and fibroblast function following exposure to agriculture organic dust

Exposure to agricultural bioaerosols can lead to chronic inflammatory lung diseases. Amphiregulin (AREG) can promote the lung repair process but can also lead to fibrotic remodeling. The objective of this study was to determine the role of AREG in altering recovery from environmental dust exposure in a murine in vivo model and in vitro using cultured human and murine lung fibroblasts. C57BL/6 mice were intranasally exposed to swine confinement facility dust extract (DE) or saline daily for 1 wk or allowed to recover for 3-7 days while being treated with an AREG-neutralizing antibody or recombinant AREG. Treatment with the anti-AREG antibody prevented resolution of DE exposure-induced airway influx of total cells, neutrophils, and macrophages and increased levels of TNF-α, IL-6, and CXCL1. Neutrophils and activated macrophages (CD11c+CD11bhi) persisted after recovery in lung tissues of anti-AREG-treated mice. In murine and human lung fibroblasts, DE induced the release of AREG and inflammatory cytokines. Fibroblast recellularization of primary human lung mesenchymal matrix scaffolds and wound closure was inhibited by DE and enhanced with recombinant AREG alone. AREG treatment rescued the DE-induced inhibitory fibroblast effects. AREG intranasal treatment for 3 days during recovery phase reduced repetitive DE-induced airway inflammatory cell influx and cytokine release. Collectively, these studies demonstrate that inhibition of AREG reduced, whereas AREG supplementation promoted, the airway inflammatory recovery response following environmental bioaerosol exposure, and AREG enhanced fibroblast function, suggesting that AREG could be targeted in agricultural workers repetitively exposed to organic dust environments to potentially prevent and/or reduce disease.

Alcohol and cannabis use alter pulmonary innate immunity

PURPOSE

Cannabis use is increasing due to recent legislative changes. In addition, cannabis is often used in conjunction with alcohol. The airway epithelium is the first line of defense against infectious microbes. Toll-like receptors (TLR) recognize airborne microbes and initiate the inflammatory cytokine response. The mechanism by which cannabis use in conjunction with alcohol affects pulmonary innate immunity mediated by TLRs is unknown.

METHODS

Samples and data from an existing cohort of individuals with alcohol use disorders (AUDs), along with samples from additional participants with cannabis use alone and with AUD were utilized. Subjects were categorized into the following groups: no alcohol use disorder (AUD) or cannabis use (control) (n = 46), AUD only (n = 29), cannabis use-only (n = 39), and AUD and cannabis use (n = 29). The participants underwent bronchoscopy with bronchoalveolar lavage (BAL) and airway epithelial brushings. We measured IL-6, IL-8, TNF⍺, and IL-10 levels in BAL fluid, and performed real-time PCR for TLR1-9 on the airway epithelial brushings.

RESULTS

We found significant increases in TLR2 with AUD alone, cannabis use alone, and cannabis use with AUD, compared to control. TLR5 was increased in cannabis users compared to control, TLR6 was increased in cannabis users and cannabis users with AUD compared to control, TLR7 was increased in cannabis users compared to control, and TLR9 was increased in cannabis users compared to control. In terms of cytokine production, IL-6 was increased in cannabis users compared to control. IL-8 and IL-10 were increased in AUD only.

CONCLUSIONS

AUD and cannabis use have complex effects on pulmonary innate immunity that promote airway inflammation.

Aging leads to dysfunctional innate immune responses to TLR2 and TLR4 agonists

BACKGROUND

Sepsis is more common in the elderly. TNF⍺ is recognized as an important mediator in sepsis and Toll-like receptors (TLRs) play an important role in initiating signaling cascades to produce TNF⍺. Little is known about how innate immunity is altered in healthy human aging that predisposes to sepsis.

AIMS AND METHODS

We tested the hypothesis that aging dysregulates the innate immune response to TLR 2 and 4 ligands. We performed whole blood assays on 554 healthy subjects aged 40-80 years. TNFα production was measured at baseline and after stimulation with the TLR2 agonists: peptidoglycan, lipoteichoic acid, Pam3CysK, Zymosan A and the TLR4 agonist lipopolysaccharide (LPS). In a subset of subjects (n = 250), we measured Toll-like receptor (TLR) 2, 4 and MyD88 expression using real-time PCR.

RESULTS AND DISCUSSION

We measured a 2.5% increase per year in basal secretion of TNFα with aging (n = 554 p = 0.02). Likewise, TNFα secretion was increased with aging after stimulation with peptidoglycan (1.3% increase/year; p = 0.0005) and zymosan A (1.1% increase/year p = 0.03). We also examined the difference between baseline and stimulated TNFα for each individual. We found that the increase was driven by the elevated baseline levels. In fact, there was a diminished stimulated response to LPS (1.9% decrease/year; p = 0.05), lipoteichoic acid (2.1% decrease/year p = 0.03), and Pam3CysK (2.6% decrease/year p = 0.0007). There were no differences in TLR or MyD88 mRNA expression with aging, however, there was an inverse relationship between TLR expression and stimulated TNFα production.

CONCLUSIONS

With aging, circulating leukocytes produce high levels of TNFα at baseline and have inadequate responses to TLR2 and TLR4 agonists. These defects likely contribute to the increased susceptibility to sepsis in older adults.

Combined Collagen-Induced Arthritis and Organic Dust-Induced Airway Inflammation to Model Inflammatory Lung Disease in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is characterized by extra-articular involvement including lung disease, yet the mechanisms linking the two conditions are poorly understood. The collagen-induced arthritis (CIA) model was combined with the organic dust extract (ODE) airway inflammatory model to assess bone/joint-lung inflammatory outcomes. DBA/1J mice were intranasally treated with saline or ODE daily for 5 weeks. CIA was induced on days 1 and 21. Treatment groups included sham (saline injection/saline inhalation), CIA (CIA/saline), ODE (saline/ODE), and CIA +  ODE (CIA/ODE). Arthritis inflammatory scores, bones, bronchoalveolar lavage fluid, lung tissues, and serum were assessed. In DBA/1J male mice, arthritis was increased in CIA +  ODE >  CIA >  ODE versus sham. Micro-computed tomography (µCT) demonstrated that loss of BMD and volume and deterioration of bone microarchitecture was greatest in CIA +  ODE. However, ODE-induced airway neutrophil influx and inflammatory cytokine/chemokine levels in lavage fluids were increased in ODE >  CIA +  ODE versus sham. Activated lung CD11c+ CD11b+ macrophages were increased in ODE >  CIA +  ODE >  CIA pattern, whereas lung hyaluronan, fibronectin, and amphiregulin levels were greatest in CIA +  ODE. Serum autoantibody and inflammatory marker concentrations varied among experimental groups. Compared with male mice, female mice showed less articular and pulmonary disease. The interaction of inhalation-induced airway inflammation and arthritis induction resulted in compartmentalized responses with the greatest degree of arthritis and bone loss in male mice with combined exposures. Data also support suppression of the lung inflammatory response, but increases in extracellular matrix protein deposition/interstitial disease in the setting of arthritis. This coexposure model could be exploited to better understand and treat RA-lung disease. © 2019 American Society for Bone and Mineral Research.

Insufficient zinc intake enhances lung inflammation in response to agricultural organic dust exposure

Organic dust exposure particularly within hog confinement facilities is a significant cause of airway inflammation and lung disease. In a cohort of Midwestern veterans with COPD and agricultural work exposure we observed reduced zinc intakes which were associated with decreased lung function. Because insufficient zinc intake is common within the U.S. and a potent modulator of innate immune function, we sought to determine whether deficits in zinc intake would impact the airway inflammatory response to hog confinement facility dust extract (HDE). Adult male C57BL/6 mice were randomized to zinc deficient or matched zinc sufficient diets for 3 weeks and subsequently treated with intranasal HDE inhalation or saline once or daily for 3 weeks while maintained on specific diets. Lavage fluid and lung tissue was collected. Conditions of zinc deficiency were also studied in macrophages exposed to HDE. Single and repetitive HDE inhalation exposure resulted in increased influx of total cells and neutrophils, increased mediator hyper-responsiveness (TNFα, IL-6, CXCL1, and amphiregulin), and enhanced tissue pathology that was more pronounced in zinc deficient mice compared to normal dietary counterparts. Airway inflammation was most pronounced in zinc deficient mice treated with repetitive HDE for 3 weeks. Similarly, macrophages maintained in a zinc deficient environment exhibited increased CXCL1 and IL-23 production as a result of increased NF-κB activation. Conclusion: Given the relatively high incidence of dietary deficiencies in agriculture workers, we anticipate that zinc intake, or a lack thereof, may play an important role in modulating the host response to organic dust exposure.

Biphasic changes in airway epithelial cell EGF receptor binding and phosphorylation induced by components of hogbarn dust

PURPOSE OF THE STUDY

Workers in enclosed hogbarns experience an increased incidence of airway inflammation and obstructive lung disease, and an aqueous hogbarn dust extract (HDE) induces multiple inflammation-related responses in cultured airway epithelial cells. Epidermal growth factor receptor (EGFR) phosphorylation and activation has been identified as one important mediator of inflammatory cytokine release from these cells. The studies here investigated both early and late phase adaptive changes in EGFR binding properties and subcellular localization induced by exposure of cells to HDE.

MATERIALS AND METHODS

Cell surface EGFRs were quantified as binding to intact cells on ice. EGFR phosphorylation, expression, and localization were assessed with anti-EGFR antibodies and either blotting or confocal microscopy.

RESULTS

In BEAS-2B and primary human bronchial epithelial cells, HDE induced decreases in cell surface EGFR binding following both 15-min and 18-h exposures. In contrast, H292 cells exhibited only the 15-min decrease, with binding near the control level at 18 hr. Confocal microscopy showed that the 15-min decrease in binding is due to EGFR endocytosis. Although total EGFR immunoreactivity decreased markedly at 18 hr in confocal microscopy with BEAS-2B cells, immunoblots showed no loss of EGFR protein. HDE stimulated EGFR phosphorylation at both 15 min and 18 hr in BEAS-2B cells and primary cells, but only at 15 min in H292 cells, indicating that the different EGFR binding changes among these cell types is likely related to their different time-dependent changes in phosphorylation.

CONCLUSIONS

These studies extend the evidence for EGFRs as important cellular targets for components of HDE and they reveal novel patterns of EGFR phosphorylation and binding changes that vary among airway epithelial cell types. The results provide both impetus and convenient assays for identifying the EGFR-activating components and pathways that likely contribute to hogbarn dust-induced lung disease in agricultural workers.

Ovalbumin-sensitized mice have altered airway inflammation to agriculture organic dust

Agriculture exposures are associated with reducing the risk of allergy and asthma in early life; yet, repeated exposures later in life are associated with chronic bronchitis and obstructive pulmonary diseases. The objective of this study was to investigate the airway inflammatory response to organic dust extract (ODE) in mice with established ovalbumin (OVA)-induced experimental asthma. C57BL/6 mice were either OVA sensitized/aerosol-exposed or saline (Sal) sensitized/aerosol-challenged. Both groups were then subsequently challenged once with intranasal saline or swine confinement ODE to obtain 4 treatment groups of Sal-Sal, Sal-ODE, OVA-Sal, and OVA-ODE. Airway hyper-responsiveness (AHR) to methacholine, bronchiolar lavage fluid, lung tissues, and serum were collected. Intranasal inhalation of ODE in OVA-treated (asthmatic) mice (OVA-ODE) increased AHR and total cellular influx marked by elevated neutrophil and eosinophil counts. Flow cytometry analysis further demonstrated that populations of CD11chi dendritic cells (DC), CD3+ T cells, CD19+ B cells, and NKp46+ group 3 innate lymphoid cells (ILC3) were increased in lavage fluid of OVA-ODE mice as compared to ODE or OVA alone. Alveolar macrophages, DC, and T cells were significantly increased with co-exposure to OVA-ODE as compared to OVA alone. Lung ILC2 and ILC3 were only increased in OVA-Sal mice. Cytokine/chemokine levels varied with exposure to OVA-ODE reflecting an additive mixture of the pro- and allergic-inflammatory profiles. Collectively, ODE increased airway inflammatory cells and chemotactic mediator release in allergic (OVA) sensitized mice to suggest that persons with allergy/asthma be identified and warned prior to the occupational exposure of potentially worsening airway disease.

Effects of Agricultural Organic Dusts on Human Lung-Resident Mesenchymal Stem (Stromal) Cell Function

Agricultural organic dust exposures trigger harmful airway inflammation, and workers experiencing repetitive dust exposures are at increased risk for lung disease. Mesenchymal stem/stromal cells (MSCs) regulate wound repair processes in the lung, and may contribute to either proresolution or -fibrotic lung responses. It is unknown how organic dust exposures alter lung-resident MSC activation and proinflammatory versus prorepair programs in the lung. To address this gap in knowledge, we isolated human lung-resident MSC from lung tissue. Cells were stimulated with aqueous extracts of organic dusts (DE) derived from swine confinement facilities and were assessed for changes in proliferative and migratory capacities, and production of proinflammatory and prorepair mediators. Through these investigations, we found that DE induces significant release of proinflammatory mediators TNF-α, IL-6, IL-8, and matrix metalloproteases, while also inducing the production of prorepair mediators amphiregulin, FGF-10, and resolvin D1. In addition, DE significantly reduced the growth and migratory capacities of lung-resident MSC. Together, these investigations indicate lung-resident MSC activation and wound repair activities are altered by organic dust exposures. These findings warrant future investigations to assess how organic dusts affect lung-resident mesenchymal stem/stromal cell function and impact airway inflammation, injury, and repair during agricultural aerosol exposures.

Sex differences impact the lung-bone inflammatory response to repetitive inhalant lipopolysaccharide exposures in mice

Skeletal health consequences associated with inflammatory diseases of the airways significantly contribute to morbidity. Sex differences have been described independently for lung and bone diseases. Repetitive inhalant exposure to lipopolysaccharide (LPS) induces bone loss and deterioration in male mice, but comparison effects in females are unknown. Using an intranasal inhalation exposure model, 8-week-old C57BL/6 male and female mice were treated daily with LPS (100 ng) or saline for 3 weeks. Bronchoalveolar lavage fluids, lung tissues, tibias, bone marrow cells, and blood were collected. LPS-induced airway neutrophil influx, interleukin (IL)-6 and neutrophil chemoattractant levels, and bronchiolar inflammation were exaggerated in male animals as compared to female mice. Trabecular bone micro-CT imaging and analysis of the proximal tibia were conducted. Inhalant LPS exposures lead to deterioration of bone quality only in male mice (not females) marked by decreased bone mineral density, bone volume/tissue volume ratio, trabecular thickness and number, and increased bone surface-to-bone volume ratio. Serum pentraxin-2 levels were modulated by sex differences and LPS exposure. In proof-of-concept studies, ovarectomized female mice demonstrated LPS-induced bone deterioration, and estradiol supplementation of ovarectomized female mice and control male mice protected against LPS-induced bone deterioration findings. Collectively, sex-specific differences exist in LPS-induced airway inflammatory consequences with significant differences found in bone quantity and quality parameters. Male mice demonstrated susceptibility to bone loss and female animals were protected, which was modulated by estrogen. Therefore, sex differences influence the biologic response in the lung-bone inflammatory axis in response to inhalant LPS exposures.

Bovine milk-derived extracellular vesicles enhance inflammation and promote M1 polarization following agricultural dust exposure in mice

Occupational agricultural dust exposure can cause severe lung injury, including COPD and asthma exacerbations. Cell-derived extracellular vesicles can mediate inflammatory responses and immune activation, but the contribution of diet-derived extracellular vesicles to these processes is poorly understood. We investigated whether bovine milk-derived extracellular vesicles modulate inflammatory responses to agricultural dust exposures in a murine model. C57BL/6 mice were fed either an extracellular vesicle-enriched modification of the AIN-93G diet with lyophilized bovine milk (EV) or a control diet wherein the milk was presonicated, disrupting the milk extracellular vesicles and thereby leading to RNA degradation (DEV). Mice were maintained on the diets for 5-7 weeks and challenged with a single (acute) intranasal instillation of a 12.5% organic dust extract (DE) or with 15 instillations over 3 weeks (repetitive exposure model). Through these investigations, we identified significant interactions between diet and DE when considering numerous inflammatory outcomes, including lavage inflammatory cytokine levels and cellular infiltration into the lung airways. DE-treated peritoneal macrophages also demonstrated altered polarization, with EV-fed mouse macrophages exhibiting an M1 shift compared to an M2 phenotype in DEV-fed mice (IL-6, TNF, IL-12/23 all significantly elevated, and IL-10 and arginase decreased in EV macrophages, ex vivo). In complementary in vitro studies, mouse macrophages treated with purified milk-derived EV were found to express similar polarization phenotypes upon DE stimulation. These results suggest a role for dietary extracellular vesicles in the modulation of lung inflammation in response to organic dust which may involve macrophage phenotype polarization.

Relationship of systemic IL-10 levels with proinflammatory cytokine responsiveness and lung function in agriculture workers

BACKGROUND

Agriculture workers are exposed to microbial component- and particulate matter-enriched organic dust aerosols. Whereas it is clear that exposure to these aerosols can lead to lung inflammation, it is not known how inflammatory responses are resolved in some individuals while others develop chronic lung disease. Interleukin (IL)-10 is an immunomodulatory cytokine that is recognized as a potent anti-inflammatory and pro-resolving factor. The objective of this study was to determine whether there is a relationship of systemic IL-10 and proinflammatory responses and/or respiratory health effects in humans with prior agriculture exposure.

METHODS

This is a cross sectional study of 625 veterans with > 2 years of farming experience. Whole blood was stimulated with or without organic dust and measured for IL-6, TNFα and IL-10. Participants underwent spirometry and respiratory symptoms were assessed by questionnaire.

RESULTS

We found that baseline IL-10 concentration from the whole blood assay was inversely associated with ΔTNF-α (r = - 0.63) and ΔIL-6 (r = - 0.37) levels. Results remained highly significant in the linear regression model after adjusting for age, sex, BMI, race, education, smoking status, and white blood cell count (ΔTNF-α, p < 0.0001; ΔIL-6, p < 0.0001). We found no association between chronic cough (p = 0.18), chronic phlegm (p = 0.31) and chronic bronchitis (p = 0.06) and baseline IL-10 levels using univariate logistic regression models. However, we did find that higher FEV1/FVC was significantly associated with increased baseline IL-10 concentration.

CONCLUSIONS

Collectively, these studies support a potential role for IL-10 in modulating an inflammatory response and lung function in agriculture-exposed persons.

Dimethylarginine dimethylaminohydrolase (DDAH) overexpression enhances wound repair in airway epithelial cells exposed to agricultural organic dust

OBJECTIVE

Workers exposed to dusts from concentrated animal feeding operations have a high prevalence of pulmonary diseases. These exposures lead to chronic inflammation and aberrant airway remodeling. Previous work shows that activating cAMP-dependent protein kinase (PKA) enhances airway epithelial wound repair while activating protein kinase C (PKC) inhibits wound repair. Hog barn dust extracts slow cell migration and wound repair via a PKC-dependent mechanism. Further, blocking nitric oxide (NO) production in bronchial epithelial cells prevents PKA activation. We hypothesized that blocking an endogenous NO inhibitor, asymmetric dimethylarginine, by overexpressing dimethylarginine dimethylaminohydrolase mitigates the effects of hog dust extract on airway epithelial would repair.

MATERIALS/METHODS

We cultured primary tracheal epithelial cells in monolayers from both wild-type (WT) and dimethylarginine dimethylaminohydrolase overexpressing C57Bl/6 (DDAH₁ transgenic) mice and measured wound repair using the electric cell impedance sensing system.

RESULTS

Wound closure in epithelial cells from WT mice occurred within 24 h in vitro. In contrast, treatment of the WT cell monolayers with 5% hog dust extract prevented significant NO-stimulated wound closure. In cells from DDAH₁ transgenic mice, control wounds were repaired up to 8 h earlier than seen in WT mice. A significant enhancement of wound repair was observed in DDAH cells compared to WT cells treated with hog dust extract for 24 h. Likewise, cells from DDAH₁ transgenic mice demonstrated increased NO and PKA activity and decreased hog dust extract-stimulated PKC.

DISCUSSION/CONCLUSION

Preserving the NO signal through endogenous inhibition of asymmetric dimethylarginine enhances wound repair even in the presence of dust exposure.

Short term dynamics of the sputum microbiome among COPD patients

Chronic obstructive pulmonary disease (COPD) is an inflammatory disorder characterized by incompletely reversible airflow obstruction. The complexity of the lung microbial community in COPD patients has been highlighted in recent years. Evidence suggests that transplantation, medications, age, and disease severity influence microbial community membership. However, the dynamics of the lung microbiome in stable COPD patients remain poorly understood. In this study, we completed a longitudinal 16S ribosomal RNA survey of the lung microbiome on replicate sputum samples collected from 4 former smokers with COPD (Stage 2) within a 2-day time period. Samples from each individual over the two-day period were similar based on α-diversity, principle component analysis and taxonomy at the phyla and genera level. Sputum samples from COPD patients were also collected between 2–9 months of follow-up. Data suggest an increased variability of the sputum microbiota when comparing samples collected ≤ 3 months compared to those collected ≥ 4 months; however, no statistically significant shifts in the abundance (>2-fold) of taxa between the two time points was observed. Bacterial composition and the number of operational taxonomic units (OTUs) remained similar over time. Results from this study suggest that the sputum microbiome is relatively stable in clinically stable COPD patients (Stage 2). This study furthers our understanding of the dynamics of the lung microbiome in COPD patients.

A role for B cells in organic dust induced lung inflammation

BACKGROUND

Agriculture organic dust exposures induce lung disease with lymphoid aggregates comprised of both T and B cells. The precise role of B cells in mediating lung inflammation is unknown, yet might be relevant given the emerging role of B cells in obstructive pulmonary disease and associated autoimmunity.

METHODS

Using an established animal model, C57BL/6 wild-type (WT) and B-cell receptor (BCR) knock-out (KO) mice were repetitively treated with intranasal inhalation of swine confinement organic dust extract (ODE) daily for 3 weeks and lavage fluid, lung tissues, and serum were collected.

RESULTS

ODE-induced neutrophil influx in lavage fluid was not reduced in BCR KO animals, but there was reduction in TNF-α, IL-6, CXCL1, and CXCL2 release. ODE-induced lymphoid aggregates failed to develop in BCR KO mice. There was a decrease in ODE-induced lung tissue CD11c⁺CD11b⁺ exudative macrophages and compensatory increase in CD8⁺ T cells in lavage fluid of BCR KO animals. Compared to saline, there was an expansion of conventional B2-, innate B1 (CD19⁺CD11b⁺CD5^+/-)-, and memory (CD19⁺CD273^+/-CD73^+/-) B cells following ODE exposure in WT mice. Autoreactive responses including serum IgG anti-citrullinated protein antibody (ACPA) and anti-malondialdehyde-acetaldehyde (MAA) autoantibodies were increased in ODE treated WT mice as compared to saline control. B cells and serum immunoglobulins were not detected in BCR KO animals.

CONCLUSIONS

Lung tissue staining for citrullinated and MAA modified proteins were increased in ODE-treated WT animals, but not BCR KO mice. These studies show that agriculture organic dust induced lung inflammation is dependent upon B cells, and dust exposure induces an autoreactive response.

Docosahexaenoic acid enhances amphiregulin-mediated bronchial epithelial cell repair processes following organic dust exposure

Injurious dust exposures in the agricultural workplace involve the release of inflammatory mediators and activation of epidermal growth factor receptor (EGFR) in the respiratory epithelium. Amphiregulin (AREG), an EGFR ligand, mediates tissue repair and wound healing in the lung epithelium. Omega-3 fatty acids such as docosahexaenoic acid (DHA) are also known modulators of repair and resolution of inflammatory injury. This study investigated how AREG, DHA, and EGFR modulate lung repair processes following dust-induced injury. Primary human bronchial epithelial (BEC) and BEAS-2B cells were treated with an aqueous extract of swine confinement facility dust (DE) in the presence of DHA and AREG or EGFR inhibitors. Mice were exposed to DE intranasally with or without EGFR inhibition and DHA. Using a decellularized lung scaffolding tissue repair model, BEC recolonization of human lung scaffolds was analyzed in the context of DE, DHA, and AREG treatments. Through these investigations, we identified an important role for AREG in mediating BEC repair processes. DE-induced AREG release from BEC, and DHA treatment following DE exposure, enhanced this release. Both DHA and AREG also enhanced BEC repair capacities and rescued DE-induced recellularization deficits. In vivo, DHA treatment enhanced AREG production following DE exposure, whereas EGFR inhibitor-treated mice exhibited reduced AREG in their lung homogenates. These data indicate a role for AREG in the process of tissue repair after inflammatory lung injury caused by environmental dust exposure and implicate a role for DHA in regulating AREG-mediated repair signaling in BEC.

Effect of low-level CO2 on innate inflammatory protein response to organic dust from swine confinement barns

BACKGROUND

Organic hog barn dust (HDE) exposure induces lung inflammation and long-term decreases in lung function in agricultural workers. While concentrations of common gasses in confined animal facilities are well characterized, few studies have been done addressing if exposure to elevated barn gasses impacts the lung immune response to organic dusts. Given the well documented effects of hypercapnia at much higher levels we hypothesized that CO₂ at 8 h exposure limit levels (5000 ppm) could alter innate immune responses to HDE.

METHODS

Using a mouse model, C57BL/6 mice were nasally instilled with defined barn dust extracts and then housed in an exposure box maintained at one of several CO₂ levels for six hours. Bronchiolar lavage (BAL) was tested for several cytokines while lung tissue was saved for mRNA purification and immunohistochemistry.

RESULTS

Exposure to elevated CO₂ significantly increased the expression of pro-inflammatory markers, IL-6 and KC, in BAL fluid as compared to dust exposure alone. Expression of other pro-inflammatory markers, such as ICAM-1 and matrix metalloproteinase-9 (MMP-9), were also tested and showed similar increased expression upon HDE + CO₂ exposure. A chemokine array analysis of BAL fluid revealed that MIP-1γ (CCL9) shows a similar increased response to HDE + CO₂. Further testing showed CCL9 was significantly elevated by barn dust and further enhanced by CO₂ co-exposure in a dose-dependent manner that was noticeable at the protein and mRNA levels. In all cases, except for ICAM-1, increases in tested markers in the presence of elevated CO₂ were only significant in the presence of HDE as well.

CONCLUSIONS

We show that even at mandated safe exposure limits, CO₂ is capable of enhancing multiple markers of inflammation in response to HDE.

Interaction of CD14 haplotypes and soluble CD14 on pulmonary function in agricultural workers

BACKGROUND

Agricultural environments are contaminated with organic dusts containing bacterial components. Chronic inhalation of organic dusts is implicated in respiratory diseases. CD14 is a critical receptor for gram-negative lipopolysaccharide; however, its association with respiratory disease among agricultural workers is unknown. The objective of this study was to determine if serum soluble CD14 (sCD14) levels are associated with lung function among agricultural workers and if this association is modified by genetic variants in CD14.

METHODS

This cross-sectional study included 584 veterans with >2 years of farming experience and that were between the ages of 40 and 80 years. Participants underwent spirometry and were genotyped for four tagging CD14 polymorphisms (CD14/-2838, rs2569193; CD14/-1720, rs2915863; CD14/-651, rs5744455; and CD14/-260, rs2569190). Serum sCD14 was assayed by ELISA.

RESULTS

Subjects were 98% white males with a mean age 64.5 years. High soluble CD14 levels (> median sCD14) were associated decreased lung function (FEV₁/FVC, p = 0.011; % predicted FEV₁, p = 0.03). When stratified by COPD (yes/no) and smoking status (ever/never), high sCD14 levels (> median sCD14) were associated with low lung function among ever smokers with COPD (% predicted FEV₁, p_adj = 0.0008; FEV₁/FVC, p_adj = 0.0002). A similar trend was observed for never smokers with COPD; however, results did not reach statistical significance due to small sample size. There was a significant sCD14 x COPD/smoking interaction with lung function (% predicted FEV₁, p_inter = 0.0498; FEV₁/FVC, p_inter = 0.011). Regression models were adjusted for age, body mass index, education, sex, race and years worked on a farm. No association was found between CD14 polymorphisms/haplotypes (CD14/-2838; CD14/-1720; CD14/-651; CD14/-260) and sCD14 levels. The final model included the variables sCD14 and haplotypes and a haplotype x sCD14 interaction term. Individuals with the GTTG haplotype (CD14/-2838 → CD14/-260) and high sCD14 levels (> median sCD14) had on average 6.94 lower % predicted FEV₁ than individuals with the GCCA haplotype and low sCD14 levels (≤ median sCD14, p_adj = 0.03).

CONCLUSION

CD14 haplotypes and sCD14 are important mediators of lung function among those with COPD in this occupationally-exposed population.

Alcohol Inhibits Organic Dust-induced ICAM-1 Expression on Bronchial Epithelial Cells

Aims: Exposure to dusts/bioaerosols in concentrated animal feeding operations (CAFOs) results in inflammatory lung diseases in workers. Hog CAFOs dust extract (HDE) increases expression of intercellular adhesion molecule-1 (ICAM-1), neutrophil adhesion, and TNFα release in bronchial epithelial cells. Alcohol consumption is increasingly recognized to impair lung immunity. We hypothesized that alcohol impairs HDE-induced TNFα, ICAM-1 expression and neutrophil adhesion by directly inhibiting TNFα converting enzyme (TACE) activity.

METHODS

Bronchial epithelial cells (BEAS-2B) and primary human bronchial epithelial cells were pretreated with ethanol (EtOH) or TACE inhibitor. ICAM-1 surface expression, TNFα release, and TACE activity were analyzed following HDE stimulation. The effect of alcohol and TACE inhibition on HDE-regulated epithelial cell/neutrophil adhesion interactions was investigated. Finally, utilizing an established animal model, C57BL/6 mice were fed ad libitum ethanol (20%) in drinking water for 8 wk followed by daily intranasal inhalation of HDE or saline during the final two weeks. Mice were sacrificed and lung sections immunostained for ICAM-1.

RESULTS

Pretreatment with alcohol or TACE inhibitor significantly decreased HDE-induced ICAM-1 expression and TNFα release. HDE augmented neutrophil adhesion to epithelial cells, which was decreased with alcohol (32% decrease) or TACE inhibitor (55% decrease) pretreatment. TACE activity increased following HDE exposure, but TACE activity was inhibited following alcohol pretreatment. Alcohol-fed mice demonstrated decreased HDE-induced airway epithelium ICAM-1 expression.

CONCLUSIONS

Alcohol diminishes HDE-induced ICAM-1 expression, TNFα release, and neutrophil adhesion via inhibition of TACE activity. These results suggest that alcohol may be an important modulator of lung innate immune responses following CAFO exposure.

A principal factor analysis to characterize agricultural exposures among Nebraska veterans

Agricultural workers are at an increased risk of developing chronic respiratory disorders. Accurate estimation of long-term agricultural exposures based on questionnaires has been used to improve the validity of epidemiologic investigations and subsequent evaluation of the association between agricultural exposures and chronic diseases. Our aim was to use principal factor analysis (PFA) to distill exposure data into essential variables characterizing long-term agricultural exposures. This is a cross-sectional study of veterans between the ages of 40 and 80 years and who worked on a farm for ≥2 years. Participant characteristics were: 98.1% were white males with a mean age 65±8 (SD) years and 39.8% had chronic obstructive pulmonary disease. The final model included four factors and explained 16.6% of the variance in the exposure data. Factor 1 was a heterogeneous factor; however, Factor 2 was exclusively composed of exposure to livestock such as hogs, dairy and poultry. Factor 3 included exposures from jobs on or off the farm such as wood dust, mineral dust, asbestos and spray paint. Crop exposure loaded exclusively in Factor 4 and included lifetime hours of exposure and maximum number of acres farmed in the participants' lifetime. The factors in the final model were interpretable and consistent with farming practices.

Systemic IL-6 Effector Response in Mediating Systemic Bone Loss Following Inhalation of Organic Dust

Airway and skeletal diseases are prominent among agriculture workers. Repetitive inhalant exposures to agriculture organic dust extract (ODE) induces bone deterioration in mice; yet the mechanisms responsible for connecting the lung-bone inflammatory axis remain unclear. We hypothesized that the interleukin (IL)-6 effector response regulates bone deterioration following inhalant ODE exposures. Using an established intranasal inhalation exposure model, wild-type (WT) and IL-6 knockout (KO) mice were treated daily with ODE or saline for 3 weeks. ODE-induced airway neutrophil influx, cytokine/chemokine release, and lung pathology were not reduced in IL-6 KO animals compared to WT mice. Utilizing micro-computed tomography, analysis of tibia showed that loss of bone mineral density, volume, and deterioration of bone micro-architecture, and mechanical strength induced by inhalant ODE exposures in WT mice were absent in IL-6 KO animals. Compared to saline treatments, bone-resorbing osteoclasts and bone marrow osteoclast precursor populations were also increased in ODE-treated WT but not IL-6 KO mice. These results show that the systemic IL-6 effector pathway mediates bone deterioration induced by repetitive inhalant ODE exposures through an effect on osteoclasts, but a positive role for IL-6 in the airway was not demonstrated. IL-6 might be an important link in explaining the lung-bone inflammatory axis.

Alcohol Decreases Organic Dust-Stimulated Airway Epithelial TNF-Alpha Through a Nitric Oxide and Protein Kinase-Mediated Inhibition of TACE

BACKGROUND

Farm workers in rural areas consume more alcohol than those who reside in urban areas. Occupational exposures such as agricultural work can pose hazards on the respiratory system. It is established that hog barn dust induces inflammation in the airway, including the release of cytokines such as tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and IL-8. We have shown that alcohol alters airway epithelial innate defense through changes in both nitric oxide (NO) and cAMP-dependent protein kinase A (PKA). Simultaneous exposure to hog barn dust and alcohol decreases inflammatory mediators, TNF-α, IL-6, and IL-8, in mice. Previously, mice exposed to both alcohol and hog barn dust showed a depleted amount of lymphocytes compared to mice exposed only to hog barn dust. Weakening of the innate immune response could lead to enhanced susceptibility to disease. In addition, mice that were co-exposed to hog barn dust and alcohol also experienced increased mortality.

METHODS

Because we recently demonstrated that PKA activation inhibits the TNF-α sheddase, TNF-α-converting enzyme (TACE), we hypothesized that an alcohol-mediated PKA pathway blocks TACE activity and prevents the normative inflammatory response to hog barn dust exposure. To delineate these effects, we used PKA pathway inhibitors (adenylyl cyclase [AC], cAMP, and PKA) to modulate the effects of alcohol on dust-stimulated TNF-α release in the bronchial epithelial cell line, BEAS-2B. Alcohol pretreatment blocked TACE activity and TNF-α release in hog barn dust-treated cells.

RESULTS

Alcohol continued to block hog barn dust-mediated TNF-α release in the presence of the particulate AC inhibitor, SQ22,536. The soluble adenylyl cyclase inhibitor, KH7, however, significantly increased the inflammatory response to hog barn dust. phosphodiesterase 4 inhibitors significantly elevated cAMP and enhanced alcohol-mediated inhibition of dust-stimulated TNF-α release. In addition, the NO synthase inhibitor, l-NMMA, also reversed the alcohol-blocking effect on dust-stimulated TNF-α.

CONCLUSIONS

These data suggest that alcohol requires a soluble cyclase-generated cAMP-PKA pathway that is dependent upon the action of NO to inhibit TACE and TNF-α release. These findings support our observations that alcohol functions through a dual NO and PKA pathway in bronchial epithelial cells.

Toll-Like Receptor 4 Signaling Pathway Mediates Inhalant Organic Dust-Induced Bone Loss

Agriculture workers have increased rates of airway and skeletal disease. Inhalant exposure to agricultural organic dust extract (ODE) induces bone deterioration in mice; yet, mechanisms underlying lung-bone crosstalk remain unclear. Because Toll-like receptor 2 (TLR2) and TLR4 are important in mediating the airway consequences of ODE, this study investigated their role in regulating bone responses. First, swine facility ODE stimulated wild-type (WT) bone marrow macrophages to form osteoclasts, and this finding was inhibited in TLR4 knock-out (KO), but not TLR2 KO cells. Next, using an established intranasal inhalation exposure model, WT, TLR2 KO and TLR4 KO mice were treated daily with ODE or saline for 3 weeks. ODE-induced airway neutrophil influx and cytokine/chemokine release were similarly reduced in TLR2 and TLR4 KO animals as compared to WT mice. Utilizing micro-computed tomography (CT), analysis of tibia showed loss of bone mineral density, volume and deterioration of bone micro-architecture and mechanical strength induced by ODE in WT mice were significantly reduced in TLR4 but not TLR2 KO animals. Bone marrow osteoclast precursor cell populations were analyzed by flow cytometry from exposed animals. In WT animals, exposure to inhalant ODE increased osteoclast precursor cell populations as compared to saline, an effect that was reduced in TLR4 but not TLR2 KO mice. These results show that TLR2 and TLR4 pathways mediate ODE-induced airway inflammation, but bone deterioration consequences following inhalant ODE treatment is strongly dependent upon TLR4. Thus, the TLR4 signaling pathway appears critical in regulating the lung-bone inflammatory axis to microbial component-enriched organic dust exposures.

β2-Adrenergic agonists attenuate organic dust-induced lung inflammation

Agricultural dust exposure results in significant lung inflammation, and individuals working in concentrated animal feeding operations (CAFOs) are at risk for chronic airway inflammatory diseases. Exposure of bronchial epithelial cells to aqueous extracts of hog CAFO dusts (HDE) leads to inflammatory cytokine production that is driven by protein kinase C (PKC) activation. cAMP-dependent protein kinase (PKA)-activating agents can inhibit PKC activation in epithelial cells, leading to reduced inflammatory cytokine production following HDE exposure. β2-Adrenergic receptor agonists (β2-agonists) activate PKA, and we hypothesized that β2-agonists would beneficially impact HDE-induced adverse airway inflammatory consequences. Bronchial epithelial cells were cultured with the short-acting β2-agonist salbutamol or the long-acting β2-agonist salmeterol prior to stimulation with HDE. β2-Agonist treatment significantly increased PKA activation and significantly decreased HDE-stimulated IL-6 and IL-8 production in a concentration- and time-dependent manner. Salbutamol treatment significantly reduced HDE-induced intracellular adhesion molecule-1 expression and neutrophil adhesion to epithelial cells. Using an established intranasal inhalation exposure model, we found that salbutamol pretreatment reduced airway neutrophil influx and IL-6, TNF-α, CXCL1, and CXCL2 release in bronchoalveolar lavage fluid following a one-time exposure to HDE. Likewise, when mice were pretreated daily with salbutamol prior to HDE exposure for 3 wk, HDE-induced neutrophil influx and inflammatory mediator production were also reduced. The severity of HDE-induced lung pathology in mice repetitively exposed to HDE for 3 wk was also decreased with daily salbutamol pretreatment. Together, these results support the need for future clinical investigations to evaluate the utility of β2-agonist therapies in the treatment of airway inflammation associated with CAFO dust exposure.

Vitamin D supplementation protects against bone loss following inhalant organic dust and lipopolysaccharide exposures in mice

Systemic bone loss is associated with airway inflammatory diseases; yet, strategies to halt disease progression from inhalant exposures are not clear. Vitamin D might be a potentially protective approach against noxious respirable environmental exposures. We sought to determine whether vitamin D supplementation represents a viable lung- and bone-protective strategy following repetitive inhalant treatments with organic dust extract (ODE) or lipopolysaccharide (LPS) in mice. C57BL/5 mice were maintained on diets with low (1 IU/D/g) or high (10 IU/D/g) vitamin D for 5 weeks and treated with ODE from swine confinement facilities, LPS, or saline daily for 3 weeks per established intranasal inhalation protocol. Lungs, hind limbs, and sera were harvested for experimental outcomes. Serum 25-hydroxyvitamin D levels were tenfold different between low and high vitamin D treatment groups with no differences between inhalant agents and saline treatments. Serum calcium levels were not affected. There was no difference in the magnitude of ODE- or LPS-induced inflammatory cell influx or lung histopathology between high and low vitamin D treatment groups. However, high vitamin D treatment reversed the loss of bone mineral density, bone volume, and bone micro-architecture deterioration induced by ODE or LPS as determined by micro-CT analysis. Bone-resorbing osteoclasts were also reduced by high vitamin D treatment. In the low vitamin D treatment groups, ODE induced the greatest degree of airway inflammatory consequences, and LPS induced the greatest degree of bone loss. Collectively, high-concentration vitamin D was protective against systemic bone loss, but not airway inflammation, resulting from ODE- or LPS-induced airway injury.

MyD88 in lung resident cells governs airway inflammatory and pulmonary function responses to organic dust treatment

Inhalation of organic dusts within agriculture environments contributes to the development and/or severity of airway diseases, including asthma and chronic bronchitis. MyD88 KO (knockout) mice are nearly completely protected against the inflammatory and bronchoconstriction effects induced by acute organic dust extract (ODE) treatments. However, the contribution of MyD88 in lung epithelial cell responses remains unclear. In the present study, we first addressed whether ODE-induced changes in epithelial cell responses were MyD88-dependent by quantitating ciliary beat frequency and cell migration following wounding by electric cell-substrate impedance sensing. We demonstrate that the normative ciliary beat slowing response to ODE is delayed in MyD88 KO tracheal epithelial cells as compared to wild type (WT) control. Similarly, the normative ODE-induced slowing of cell migration in response to wound repair was aberrant in MyD88 KO cells. Next, we created MyD88 bone marrow chimera mice to investigate the relative contribution of MyD88-dependent signaling in lung resident (predominately epithelial cells) versus hematopoietic cells. Importantly, we demonstrate that ODE-induced airway hyperresponsiveness is MyD88-dependent in lung resident cells, whereas MyD88 action in hematopoietic cells is mainly responsible for ODE-induced TNF-α release. MyD88 signaling in lung resident and hematopoietic cells are necessary for ODE-induced IL-6 and neutrophil chemoattractant (CXCL1 and CXCL2) release and neutrophil influx. Collectively, these findings underscore an important role for MyD88 in lung resident cells for regulating ciliary motility, wound repair and inflammatory responses to ODE, and moreover, show that airway hyperresponsiveness appears uncoupled from airway inflammatory consequences to organic dust challenge in terms of MyD88 involvement.

TLR2 and TLR4 Expression and Inflammatory Cytokines are Altered in the Airway Epithelium of Those with Alcohol Use Disorders

BACKGROUND

The lung has a highly regulated system of innate immunity to protect itself from inhaled microbes and toxins. The first line of defense is mucociliary clearance, but if invaders overcome this, inflammatory pathways are activated. Toll-like receptors (TLRs) are expressed on the airway epithelium. Their signaling initiates the inflammatory cascade and leads to production of inflammatory cytokines such as interleukin (IL)-6 and IL-8. We hypothesized that airway epithelial insults, including heavy alcohol intake or smoking, would alter the expression of TLRs on the airway epithelium.

METHODS

Bronchoscopy with bronchoalveolar lavage and brushings of the airway epithelium was performed in otherwise healthy subjects who had normal chest radiographs and spirometry. A history of alcohol use disorders (AUDs) was ascertained using the Alcohol Use Disorders Identification Test (AUDIT), and a history of cigarette smoking was also obtained. Age, gender, and nutritional status in all groups were similar. We used real-time polymerase chain reaction (PCR) to quantitate TLR1 to 9 and enzyme-linked immune assay to measure tumor necrosis factor-α, IL-6, and IL-8.

RESULTS

Airway brushings were obtained from 26 nonsmoking/non-AUD subjects, 28 smoking/non-AUD subjects, 36 smoking/AUD subjects, and 17 nonsmoking/AUD subjects. We found that TLR2 is up-regulated in AUD subjects, compared to nonsmoking/non-AUD subjects, and correlated with their AUDIT scores. We also measured a decrease in TLR4 expression in AUD subjects that correlated with AUDIT score. IL-6 and IL-8 were also increased in bronchial washings from AUD subjects.

CONCLUSIONS

We have previously demonstrated in normal human bronchial epithelial cells that in vitro alcohol exposure up-regulates TLR2 through a NO/cGMP/PKG-dependent pathway, resulting in up-regulation of inflammatory cytokine production after Gram-positive bacterial product stimulation. Our current translational study confirms that TLR2 is also up-regulated in humans with AUDs.

Maresin-1 reduces airway inflammation associated with acute and repetitive exposures to organic dust

Agriculture industry workers are at a higher risk for chronic bronchitis and obstructive pulmonary diseases, and current therapeutics are not entirely effective. We previously found that the specialized proresolving lipid mediator maresin-1 (MaR1) reduced proinflammatory cytokine release and intracellular adhesion molecule-1 (ICAM-1) expression in bronchial epithelial cells exposed to extracts of organic dust (DE) derived from swine confinement facilities in vitro. The objective of this study was to determine whether MaR1 is effective at limiting lung inflammation associated with acute and repetitive exposures to DE in an established murine model of inhalant dust exposures. C57Bl/6 mice were treated with MaR1 or vehicle control and intranasally instilled with DE once or daily for 3 weeks. Bronchioalveolar lavage fluid was analyzed for total and differential cell counts and proinflammatory cytokine levels, and lung tissues were assessed for histopathology and ICAM-1 expression. In both single and repetitive DE exposure studies, MaR1 significantly decreased bronchoalveolar lavage neutrophil infiltration, interleukin 6, tumor necrosis factor α, and chemokine C-X-C motif ligand 1 levels without altering repetitive DE-induced bronchioalveolar inflammation or lymphoid aggregate formation. Lung tissue ICAM-1 expression was also reduced in both single and repetitive exposure studies. These data suggest that MaR1 might contribute to an effective strategy to reduce airway inflammatory diseases induced by agricultural-related organic dust environmental exposures.

Proteases in agricultural dust induce lung inflammation through PAR-1 and PAR-2 activation

Workers exposed to aerosolized dust present in concentrated animal feeding operations (CAFOs) are susceptible to inflammatory lung diseases, such as chronic obstructive pulmonary disease. Extracts of dust collected from hog CAFOs [hog dust extract (HDE)] are potent stimulators of lung inflammatory responses in several model systems. The observation that HDE contains active proteases prompted the present study, which evaluated the role of CAFO dust proteases in lung inflammatory processes and tested whether protease-activated receptors (PARs) are involved in the signaling pathway for these events. We hypothesized that the damaging proinflammatory effect of HDE is due, in part, to the proteolytic activation of PARs, and inhibiting the proteases in HDE or disrupting PAR activation would attenuate HDE-mediated inflammatory indexes in bronchial epithelial cells (BECs), in mouse lung slices in vitro, and in a murine in vivo exposure model. Human BECs and mouse lung slice cultures stimulated with 5% HDE released significantly more of each of the cytokines measured (IL-6, IL-8, TNF-α, keratinocyte-derived chemokine/CXC chemokine ligand 1, and macrophage inflammatory protein-2/CXC chemokine ligand 2) than controls, and these effects were markedly diminished by protease inhibition. Inhibition of PARs also blunted the HDE-induced cytokine release from BECs. In addition, protease depletion inhibited HDE-induced BEC intracellular PKCα and PKCε activation. C57BL/6J mice administered 12.5% HDE intranasally, either once or daily for 3 wk, exhibited increased total cellular and neutrophil influx, bronchial alveolar fluid inflammatory cytokines, lung histopathology, and inflammatory scores compared with mice receiving protease-depleted HDE. These data suggest that proteases in dust from CAFOs are important mediators of lung inflammation, and these proteases and their receptors may provide novel targets for therapeutic intervention in CAFO dust-induced airways disease.

Effect of elevated carbon dioxide on bronchial epithelial innate immune receptor response to organic dust from swine confinement barns

Hypercapnia is known to have immunoregulatory effects within the lung. Cell culture systems demonstrate this in both macrophages and alveolar cell lines, suggesting that the alveoli are affected by changes in CO2 levels. We hypothesized that hypercapnia would also modulate human bronchial epithelial cell immune responses. Innate immune responses to Pam3CSK4 (TLR2 ligand), LPS (TLR4 ligand) and a complex innate immune stimulus, an extract from the organic dust of swine confinement barns (barn dust extract or BDE), were tested in a human bronchial epithelial cell line, BEAS-2B. Both TLR ligands showed a decrease in IL-6 and IL-8 production, and an increase in MCP-1 in response to elevated CO2 indicating an enhancement in cytokine production to hypercapnia. This change was not reflected in expression levels of TLR receptor RNA which remained unchanged in response to elevated CO2. Interestingly, barn dust showed an increase in IL-6, IL-8 and MCP-1 response at 9% CO2, suggesting that elevated CO2 exerts different effects on different stimuli. Our results show that airway epithelial cell immune responses to barn dust respond differently to hypercapnic conditions than individual TLR ligands.

Impact of body mass index on pulmonary complications in patients with non-Hodgkin lymphoma treated with hematopoietic stem cell transplant

The objective of this study was to examine the association between body mass index (BMI) and the incidence of pulmonary complications (PCs) after hematopoietic stem cell transplant (HCT). We reviewed 398 adult patients with non-Hodgkin lymphoma (NHL) who received autologous or allogeneic HCT between 1993 and 1997. BMI was classified as normal (18.5 < BMI ≤ 24.9), overweight (24.9 < BMI ≤ 30) and obese (BMI > 30). Multivariate logistic regression was used to analyze the relationship between BMI and presence of PCs within 100 days post-HCT while adjusting for patient-, disease- and transplant-related variables. The incidence of PCs within 100 days post-HCT was 32% (n = 129). Median BMI was 25.4 (range: 18.6-52.2). Median age was 48.8 years (range: 19.5-73.6 years). Multivariate analysis failed to show significant association between BMI and PCs. However, a total body irradiation (TBI)-based conditioning regimen was associated with lower rate of PCs.

Gait mechanics in patients with chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by the frequent association of disease outside the lung. The objective of this study was to determine the presence of biomechanical gait abnormalities in COPD patients compared to healthy controls while well rested and without rest.

METHODS

Patients with COPD (N = 17) and aged-matched, healthy controls (N = 21) walked at their self-selected pace down a 10-meter walkway while biomechanical gait variables were collected. A one-minute rest was given between each of the five collected trials to prevent tiredness (REST condition). Patients with COPD then walked at a self-selected pace on a treadmill until the onset of self-reported breathlessness or leg tiredness. Subjects immediately underwent gait analysis with no rest between each of the five collected trials (NO REST condition). Statistical models with and without covariates age, gender, and smoking history were used.

RESULTS

After adjusting for covariates, COPD patients demonstrated more ankle power absorption in mid-stance (P = 0.006) than controls during both conditions. Both groups during NO REST demonstrated increased gait speed (P = 0.04), stride length (P = 0.03), and peak hip flexion (P = 0.04) with decreased plantarflexion moment (P = 0.04) and increased knee power absorption (P = 0.04) as compared to REST. A significant interaction revealed that peak ankle dorsiflexion moment was maintained from REST to NO REST for COPD but increased for controls (P < 0.01). Stratifying by disease severity did not alter these findings, except that step width decreased in NO REST as compared to REST (P = 0.01). Standardized effect sizes of significant effects varied from 0.5 to 0.98.

CONCLUSIONS

Patients with COPD appear to demonstrate biomechanical gait changes at the ankle as compared to healthy controls. This was seen not only in increased peak ankle power absorption during no rest but was also demonstrated by a lack of increase in peak ankle dorsiflexion moment from the REST to the NO REST condition as compared to the healthy controls. Furthermore, a wider step width has been associated with fall risk and this could account for the increased incidence of falls in patients with COPD.

CXCR1/CXCR2 antagonist CXCL8(3-74)K11R/G31P blocks lung inflammation in swine barn dust-instilled mice

Inhalation of agricultural occupational dusts from swine confinement facilities can result in lung inflammation. The innate immune response to organic barn dusts results in production of a number of pro-inflammatory factors in the lungs of barn workers such as cytokines, chemokines, and an influx of neutrophils. Many of these inflammatory factors are influenced by the chemokine CXCL8/IL-8 (KC or MIP-2 in mice). Previously, we have demonstrated that an endotoxin-independent component of swine barn dust extract (SBE) elevates lung chemokines in a protein kinase C (PKC)-dependent manner resulting in the significant formation of lung inflammatory cell infiltrates in a mouse model of SBE injury. In this study we test the ability of a CXCR1/CXCR2 antagonist, CXCL8(3-74)K11R/G31P (G31P) to block many of the features of lung-inflammation in response to challenge with SBE in an established mouse exposure system. Injection of G31P concurrent with SBE nasal instillation over a course of 3 weeks significantly reduced neutrophil accumulation in the lungs of barn dust exposed animals compared to those given SBE alone. There was a similar reduction in pro-inflammatory cytokines and chemokines IL-6, KC, and MIP-2 in SBE plus G31P-treated mice. In addition to excreted products, the receptors ICAM-1, CXCR1, and CXCR2, which all were elevated with SBE exposure, were also decreased with G31P treatment. SBE activation of PKCα and PKCε was reduced as well with G31P treatment. Thus, G31P was found to be highly effective at reducing several features of lung inflammation in mice exposed to barn dust extracts.

Age Impacts Pulmonary Inflammation and Systemic Bone Response to Inhaled Organic Dust Exposure

Agricultural workers have high rates of airway and skeletal health disease. Studies recently demonstrated that inhaled agricultural organic dust extract (ODE)-induced airway injury is associated with bone deterioration in an animal model. However, the effect of age in governing these responses to organic dusts is unclear, but might be important in future approaches. Young (7-9 wk) and older (12-14,o) male C57BL/6 mice received intranasal (i.n.) inhalation exposure to ODE from swine confinement facilities once or daily for 3 wk. Acute ODE-induced neutrophil influx and cytokine and chemokine (tumor necrosis factor [TNF]-α, interleukin [IL]-6, keratinocyte chemoattractant [CXCL1], macrophage inflammatory protein-2 [CXCL2]) airway production were reduced in older compared to young mice. Repetitive ODE treatment, however, increased lymphocyte recruitment and alveolar compartment histopathologic inflammatory changes in older mice. Whole lung cell infiltrate analysis revealed that young, but not older, mice repetitively treated with ODE demonstrated an elevated CD4:CD8 lymphocyte response. Acute inhalant ODE exposure resulted in a 4-fold and 1.5-fold rise in blood neutrophils in young and older mice, respectively. Serum IL-6 and CXCL1 levels were elevated in young and older mice i.n. exposed once to ODE, with increased CXCL1 levels in younger compared to older mice. Although older mice displayed reduced bone measurements compared to younger mice, younger rodents demonstrated ODE-induced decrease in bone mineral density, bone volume, and bone microarchitecture quality as determined by computed tomography (CT) analysis. Collectively, age impacts the airway injury and systemic inflammatory and bone loss response to inhalant ODE, suggesting an altered and enhanced immunologic response in younger as compared to older counterparts.

The omega-3 fatty acid docosahexaenoic acid attenuates organic dust-induced airway inflammation

Workers exposed to organic dusts from concentrated animal feeding operations (CAFOs) are at risk for developing airway inflammatory diseases. Available preventative and therapeutic measures for alleviating dust-induced lung disease are inadequate. Because omega-3 fatty acids can mitigate inflammatory processes, we aimed to determine whether nutritional supplementation with the omega-3 fatty acid docosahexaenoic acid (DHA) could reduce the airway inflammatory consequences of exposures to organic dust. Aqueous extracts of organic dusts from swine CAFOs (ODE) were utilized. In DHA-pretreated human bronchial epithelial cells, lung fibroblasts, monocyte cell cultures, and precision-cut murine lung slices, we found that DHA pretreatment dose-dependently decreased ODE-induced inflammatory cytokine production. To determine the in vivo significance of DHA, C57BL/6 mice were orally administered DHA for seven days prior to treatment with intranasal ODE or saline inhalations. Animals treated with 2 mg DHA demonstrated significant reductions in ODE-induced bronchial alveolar lavage neutrophil influx and pro-inflammatory cytokine/chemokine production compared to mice exposed to ODE alone. Collectively, these data demonstrate that DHA affects several lung cells to reduce the airway inflammatory response to organic dust exposures. Dietary supplementation with DHA may be an effective therapeutic strategy to reduce the airway inflammatory consequences in individuals exposed to agriculture dust environments.

cAMP-dependent protein kinase activation decreases cytokine release in bronchial epithelial cells

Lung injury caused by inhalation of dust from swine-concentrated animal-feeding operations (CAFO) involves the release of inflammatory cytokine interleukin 8 (IL-8), which is mediated by protein kinase C-ε (PKC-ε) in airway epithelial cells. Once activated by CAFO dust, PKC-ε is responsible for slowing cilia beating and reducing cell migration for wound repair. Conversely, the cAMP-dependent protein kinase (PKA) stimulates contrasting effects, such as increased cilia beating and an acceleration of cell migration for wound repair. We hypothesized that a bidirectional mechanism involving PKA and PKC regulates epithelial airway inflammatory responses. To test this hypothesis, primary human bronchial epithelial cells and BEAS-2B cells were treated with hog dust extract (HDE) in the presence or absence of cAMP. PKC-ε activity was significantly reduced in cells that were pretreated for 1 h with 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) before exposure to HDE (P < 0.05). HDE-induced IL-6, and IL-8 release was significantly lower in cells that were pretreated with 8-Br-cAMP (P < 0.05). To exclude exchange protein activated by cAMP (EPAC) involvement, cells were pretreated with either 8-Br-cAMP or 8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate (8-CPT-2Me-cAMP) (EPAC agonist). 8-CPT-2Me-cAMP did not activate PKA and did not reduce HDE-stimulated IL-6 release. In contrast, 8-Br-cAMP decreased HDE-stimulated tumor necrosis factor (TNF)-α-converting enzyme (TACE; ADAM-17) activity and subsequent TNF-α release (P < 0.001). 8-Br-cAMP also blocked HDE-stimulated IL-6 and keratinocyte-derived chemokine release in precision-cut mouse lung slices (P < 0.05). These data show bidirectional regulation of PKC-ε via a PKA-mediated inhibition of TACE activity resulting in reduced PKC-ε-mediated release of IL-6 and IL-8.

Influence of farming exposure on the development of asthma and asthma-like symptoms

Based upon age and type of farming exposures, a wide range of studies demonstrate either protective or deleterious effects of the farming environment on asthma. In this review, we highlight key studies supporting the concept that farming exposure protects children from asthma and atopy based on studies performed largely in European pediatric cohorts. Various types of farming in certain regions appear to have a greater effect on asthma protection, as does the consumption of unpasteurized milk. In the United State, where concentrated animal feeding operations (CAFOs) are more common, asthma is increased in children exposed especially to swine CAFOs; whereas, rates of atopy and allergy are lower in these children. We also review studies evaluating the role of farming exposures both as a child and/or as an adult on asthma seen in adults. The importance of microbes in farming environments and the contribution of various components of the innate immune system including toll-like receptors to the underlying mechanisms of asthma related to farming exposures are also reviewed.