IL-17A-producing gammadelta T and Th17 lymphocytes mediate lung inflammation but not fibrosis in experimental silicosis

No causal association between pneumoconiosis and three inflammatory immune diseases: a Mendelian randomization study

Objectives

To investigate the causal relationships between pneumoconiosis and rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and gout.

Methods

The random-effects inverse variance weighted (IVW) approach was utilized to explore the causal effects of the instrumental variables (IVs). Sensitivity analyses using the MR-Egger and weighted median (WM) methods were did to investigate horizontal pleiotropy. A leave-one-out analysis was used to avoid the bias resulting from single-nucleotide polymorphisms (SNPs).

Results

There was no causal association between pneumoconiosis and SLE, RA or gout in the European population [OR = 1.01, 95% CI: 0.94-1.10, p = 0.74; OR = 1.00, 95% CI: 0.999-1.000, p = 0.50; OR = 1.00, 95% CI: 1.000-1.001, p = 0.55]. Causal relationships were also not found in pneumoconiosis due to asbestos and other mineral fibers and SLE, RA and gout [OR = 1.01, 95% CI: 0.96-1.07, p = 0.66; OR = 1.00, 95% CI: 1.00-1.00, p = 0.68; OR = 1.00, 95% CI: 1.00-1.00, p = 0.20].

Conclusion

Our study suggests that pneumoconiosis may have no causal relationship with the three inflammatory immune diseases.

In vitro inflammation and toxicity assessment of pre- and post-incinerated organomodified nanoclays to macrophages using high-throughput screening approaches

BACKGROUND

Organomodified nanoclays (ONC), two-dimensional montmorillonite with organic coatings, are increasingly used to improve nanocomposite properties. However, little is known about pulmonary health risks along the nanoclay life cycle even with increased evidence of airborne particulate exposures in occupational environments. Recently, oropharyngeal aspiration exposure to pre- and post-incinerated ONC in mice caused low grade, persistent lung inflammation with a pro-fibrotic signaling response with unknown mode(s) of action. We hypothesized that the organic coating presence and incineration status of nanoclays determine the inflammatory cytokine secretary profile and cytotoxic response of macrophages. To test this hypothesis differentiated human macrophages (THP-1) were acutely exposed (0-20 µg/cm2) to pristine, uncoated nanoclay (CloisNa), an ONC (Clois30B), their incinerated byproducts (I-CloisNa and I-Clois30B), and crystalline silica (CS) followed by cytotoxicity and inflammatory endpoints. Macrophages were co-exposed to lipopolysaccharide (LPS) or LPS-free medium to assess the role of priming the NF-κB pathway in macrophage response to nanoclay treatment. Data were compared to inflammatory responses in male C57Bl/6J mice following 30 and 300 µg/mouse aspiration exposure to the same particles.

RESULTS

In LPS-free media, CloisNa exposure caused mitochondrial depolarization while Clois30B exposure caused reduced macrophage viability, greater cytotoxicity, and significant damage-associated molecular patterns (IL-1α and ATP) release compared to CloisNa and unexposed controls. LPS priming with low CloisNa doses caused elevated cathepsin B/Caspage-1/IL-1β release while higher doses resulted in apoptosis. Clois30B exposure caused dose-dependent THP-1 cell pyroptosis evidenced by Cathepsin B and IL-1β release and Gasdermin D cleavage. Incineration ablated the cytotoxic and inflammatory effects of Clois30B while I-CloisNa still retained some mild inflammatory potential. Comparative analyses suggested that in vitro macrophage cell viability, inflammasome endpoints, and pro-inflammatory cytokine profiles significantly correlated to mouse bronchioalveolar lavage inflammation metrics including inflammatory cell recruitment.

CONCLUSIONS

Presence of organic coating and incineration status influenced inflammatory and cytotoxic responses following exposure to human macrophages. Clois30B, with a quaternary ammonium tallow coating, induced a robust cell membrane damage and pyroptosis effect which was eliminated after incineration. Conversely, incinerated nanoclay exposure primarily caused elevated inflammatory cytokine release from THP-1 cells. Collectively, pre-incinerated nanoclay displayed interaction with macrophage membrane components (molecular initiating event), increased pro-inflammatory mediators, and increased inflammatory cell recruitment (two key events) in the lung fibrosis adverse outcome pathway.

The role of inflammation in silicosis

Silicosis is a chronic illness marked by diffuse fibrosis in lung tissue resulting from continuous exposure to SiO2-rich dust in the workplace. The onset and progression of silicosis is a complicated and poorly understood pathological process involving numerous cells and molecules. However, silicosis poses a severe threat to public health in developing countries, where it is the most prevalent occupational disease. There is convincing evidence supporting that innate and adaptive immune cells, as well as their cytokines, play a significant role in the development of silicosis. In this review, we describe the roles of immune cells and cytokines in silicosis, and summarize current knowledge on several important inflammatory signaling pathways associated with the disease, aiming to provide novel targets and strategies for the treatment of silicosis-related inflammation.

Targeting progranulin alleviated silica particles-induced pulmonary inflammation and fibrosis via decreasing Il-6 and Tgf-β1/Smad

Long term exposure to silica particles leads to various diseases, among which silicosis is of great concern. Silicosis is an interstitial lung disease caused by inhalation of silica particles in production environments. However, the mechanisms underlying silicosis remains unclear. Our previous studies revealed that progranulin (Pgrn) promoted the expression of pro-inflammatory factors in alveolar macrophages treated with silica particles and the secretion of extracellular matrix of pulmonary fibroblasts. Nevertheless, the role of Pgrn in silica particles-induced silicosis in vivo was unknown. This study found that silica particles increased Pgrn expression in silicosis patients. Pgrn deficiency reduced lung inflammation and fibrosis in silica particles-induced silicosis mouse models. Subsequently, based on transcriptional sequencing and interleukin (Il) -6 knockout mouse models, results demonstrated that Pgrn deficiency might decrease silicosis inflammation by reducing the production of Il-6, thereby modulating pulmonary fibrosis in the early stage of silicosis mouse models. Furthermore, another mechanism through which Pgrn deficiency reduced fibrosis in silicosis mouse models was the regulation of the transforming growth factor (Tgf) -β1/Smad signaling pathway. Conclusively, Pgrn contributed to silicosis inflammation and fibrosis induced by silica particles, indicating that Pgrn could be a promising therapeutic target.

IL-22 Binding Protein Controls IL-22-Driven Bleomycin-Induced Lung Injury

The high mortality rates of acute lung injury and acute respiratory distress syndrome challenge the field to identify biomarkers and factors that can be exploited for therapeutic approaches. IL-22 is a cytokine that has antibacterial and reparative properties in the lung. However, it also can exacerbate inflammation and requires tight control by the extracellular inhibitory protein known as IL-22 binding protein (IL-22BP) (Il22ra2). This study showed the necessity of IL-22BP in controlling and preventing acute lung injury using IL-22BP knockout mice (Il22ra2-/-) in the bleomycin model of acute lung injury/acute respiratory distress syndrome. Il22ra2-/- mice had greater sensitivity (weight loss and death) and pulmonary inflammation in the acute phase (first 7 days) of the injury compared with wild-type C57Bl/6 controls. The inflammation was driven by excess IL-22 production, inducing the influx of pathogenic IL-17A+ γδ T cells to the lung. Interestingly, this inflammation was initiated in part by the noncanonical IL-22 signaling to macrophages, which express the IL-22 receptor (Il22ra1) in vivo after bleomycin challenge. This study further showed that IL-22 receptor alpha-1+ macrophages can be stimulated by IL-22 to produce a number of IL-17-inducing cytokines such as IL-1β, IL-6, and transforming growth factor-β1. Together, the results suggest that IL-22BP prevents IL-22 signaling to macrophages and reduces bleomycin-mediated lung injury.

Periodontitis aggravates COPD through the activation of γδ T cell and M2 macrophage

Chronic obstructive pulmonary disease (COPD) is a chronic systemic inflammatory disease with high morbidity and mortality. Periodontitis exacerbates COPD progression; however, the immune mechanisms by which periodontitis affects COPD remain unclear. Here, by constructing periodontitis and COPD mouse models, we demonstrated that periodontitis and COPD could mutually aggravate disease progression. For the first time, we found that the progression was associated with the activation of γδ T cells and M2 macrophages, and M2 polarization of macrophages was affected by γδ T cells activation. In the lung tissues of COPD with periodontitis, the activation of γδ T cells finally led to the increase of IL 17 and IFN γ expression and M2 macrophage polarization. Furthermore, we found that the periodontitis-associated bacteria Porphyromonas gingivalis (P. gingivalis) promoted the activation of γδ T cells and M2 macrophages ex vivo. The data from clinical bronchoalveolar lavage fluid (BALF) samples were consistent with the in vivo and ex vivo experiments. For the first time, our results identified the crucial role of γδ T-M2 immune mechanism in mediating periodontitis-promoted COPD progression. Therefore, targeting at periodontitis treatment and the γδ T-M2 immune mechanism might provide a new practical strategy for COPD prevention or control.IMPORTANCEPeriodontitis exacerbates chronic obstructive pulmonary disease (COPD) progression. For the first time, the current study identified that the impact of periodontitis on COPD progression was associated with the activation of γδ T cells and M2 macrophages and that M2 polarization of macrophages was affected by γδ T cells activation. The results indicated that targeting at periodontitis treatment and the γδ T-M2 immune mechanism might provide a new practical strategy for COPD prevention or control.

Single-cell transcriptomics reveals the pulmonary inflammation induced by inhalation of subway fine particles

People generally take the subway and inevitably inhale the fine particles (PM2.5) on subway platforms. This study revealed whether and how subway PM2.5 causes lung inflammation. Herein, the pulmonary inflammatory response to subway PM2.5 was observed in mice, manifesting as the inflammatory cells infiltration and collagen deposition in tissue, inflammatory cytokine enhancement in bronchoalveolar lavage fluid and Toll-like receptors signal pathway activation in the lungs. Furthermore, single-cell RNA sequencing unearthed subway PM2.5-induced cell-specific responses in the lungs. Twenty immune subsets were identified by the molecular and functional properties. Specific cell populations of CD4+ T and γδ T cells were regarded as the predominant sources of pneumonitis induced by subway PM2.5. Moreover, we demonstrated that the lung inflammatory injury was significantly more attenuated in Rag1-/- mice lacking functional T cells and B cells than that in wild type mice. We proved the slight inflammation of lung tissue in Rag1-/- mice may be dependent on monocytes and neutrophils by activation of the intracellular molecular network. This is the first experimental study on subway PM2.5 causing pulmonary inflammatory damage. It will set an alarm for people who usually travel by subway and efficient measures to reduce PM2.5 should be developed in subway stations.

Modifiable risk factors linked to the development of rheumatoid arthritis: evidence, immunological mechanisms and prevention

Rheumatoid Arthritis (RA) is a common autoimmune disease that targets the synovial joints leading to arthritis. Although the etiology of RA remains largely unknown, it is clear that numerous modifiable risk factors confer increased risk to developing RA. Of these risk factors, cigarette smoking, nutrition, obesity, occupational exposures and periodontal disease all incrementally increase RA risk. However, the precise immunological mechanisms by which these risk factors lead to RA are not well understood. Basic and translational studies have provided key insights into the relationship between inflammation, antibody production and the influence in other key cellular events such as T cell polarization in RA risk. Improving our general understanding of the mechanisms which lead to RA will help identify targets for prevention trials, which are underway in at-risk populations. Herein, we review the modifiable risk factors that are linked to RA development and describe immune mechanisms that may be involved. We highlight the few studies that have sought to understand if modification of these risk factors reduces RA risk. Finally, we speculate that modification of risk factors may be an appealing avenue for prevention for some at-risk individuals, specifically those who prefer lifestyle interventions due to safety and economic reasons.

Pulmonary fibrosis and type-17 immunity

Fibrosis of the lung can occur in idiopathic pulmonary fibrosis, collagen vascular diseases, and hypersensitivity pneumonitis, among other diseases. Transforming growth factor (TGF)-β, vascular epithelial growth factor, fibroblast growth factor, and platelet-derived growth factor contribute to the pathophysiology of fibrosis. TGF-β and other cytokines, including interleukin (IL)-1β, IL-6, and IL-23, activate type-17 immunity, which is involved in pulmonary fibrosis. The components of type-17 immunity include type-17 helper T cells, γδT cells, IL-17A-producing CD8-positive T cells, invariant NKT cells, and group 3 innate lymphoid cells. IL-17A, the main cytokine of type-17 immunity, is able to induce the epithelial-mesenchymal transition in epithelial cells via a production of TGF-β, directly stimulate fibroblasts and fibrocytes, and inhibit autophagy, which otherwise protects against pulmonary fibrosis. IL-23 induces type-17 immunity and plays an important role in the acute exacerbation of pulmonary fibrosis. Clinical studies have also linked type-17 immunity to the pathogenesis of pulmonary fibrosis. Consequently, targeting type-17 immunity may serve as a new therapeutic strategy to prevent the development or exacerbation of pulmonary fibrosis.

Unraveling the mechanism of tetrandrine combined with Buyang Huanwu Decoction against silicosis using network pharmacology and molecular docking analyses

Silicosis is an incurable chronic disease characterized by lung fibrosis and inflammation. The combination of tetrandrine and Buyang Huanwu Decoction (BYHWD) has a curative effect on silicosis. However, the mechanism of action and the key active constituent in BYHWD are still unclear. The present study employed network pharmacology and molecular docking to determine the mechanism of action and the key active components of BYHWD of Tetrandrine in combination with BYHWD for silicosis. The primary elements and targets of BYHWD were obtained from the Traditional Chinese Medicine Systems Pharmacology and analysis platform. The targets associated with tetrandrine and silicosis were identified and extracted from the Comparative Toxicogenomics Database and GeneCards database. The potential targets for the treatment of silicosis using a combination of Tetrandrine and BYHWD were identified by considering the overlapping targets between compound drugs and silicosis. These targets were then utilized to construct protein-protein interaction networks, compound drug-ingredient-target networks, and perform enrichment analyses. The top 5 active ingredients present in the compound drug-ingredient-target network are tetrandrine, quercetin, luteolin, kaempferol, and beta-carotene. Similarly, the top 6 hub genes in the protein-protein interaction network are FGF2, MMP-9, MMP-1, IL-10, IL-17A, and IL-6. The molecular docking suggested that the active components may easily access the active pocket of the hub gene. The in-silico investigation suggested that quercetin might be the active component in BYHWD responsible for therapeutic effectiveness against silicosis. This study identified the active compound and potential molecular mechanism underlying the therapeutic effects of BYHWD in combination with tetrandrine for treating silicosis. Notably, we found that quercetin may serve as the key compound in BYHWD for the treatment of silicosis.

IL-22 Is Deleterious along with IL-17 in Allergic Asthma but Is Not Detrimental in the Comorbidity Asthma and Acute Pneumonia

There is evidence that IL-22 and IL-17 participate in the pathogenesis of allergic asthma. To investigate the role of IL-22, we used IL-22 deficient mice (IL-22 KO) sensitized and challenged with ovalbumin (OVA) and compared with wild type (WT) animals exposed to OVA. IL-22 KO animals exposed to OVA showed a decreased number and frequency of eosinophils, IL-5 and IL-13 in the airways, reduced mucus production and pulmonary inflammation. In addition, IL-22 KO animals exhibited a decreased percentage and number of lung CD11c+CD11b+ cells and increased apoptosis of eosinophils. Th17 cell transfer generated from IL-22 KO to animals previously sensitized and challenged with OVA caused a reduction in eosinophil frequency and number in the airways compared to animals transferred with Th17 cells generated from WT mice. Therefore, IL-22 is deleterious with concomitant secretion of IL-17. Our findings show a pro-inflammatory role for IL-22, confirmed in a model of allergen-free and allergen-specific immunotherapy. Moreover, during the comorbidity asthma and pneumonia that induces neutrophil inflammation, IL-22 was not detrimental. Our results show that targeting IL-22 would negatively affect the survival of eosinophils, reduce the expansion or migration of CD11c+CD11b+ cells, and negatively regulate allergic asthma.

A comprehensive network map of IL-17A signaling pathway

Interleukin-17A (IL-17A) is one of the member of IL-17 family consisting of other five members (IL-17B to IL-17F). The Gamma delta (γδ) T cells and T helper 17 (Th17) cells are the major producers of IL-17A. Aberrant signaling by IL-17A has been implicated in the pathogenesis of several autoimmune diseases including idiopathic pulmonary fibrosis, acute lung injury, chronic airway diseases, and cancer. Activation of the IL-17A/IL-17 receptor A (IL-17RA) system regulates phosphoinositide 3-kinase/AKT serine/threonine kinase/mammalian target of rapamycin (PI3K/AKT/mTOR), mitogen-activated protein kinases (MAPKs) and activation of nuclear factor-κB (NF-κB) mediated signaling pathways. The IL-17RA activation orchestrates multiple downstream signaling cascades resulting in the release of pro-inflammatory cytokines such as interleukins (IL)-1β, IL-6, and IL-8, chemokines (C-X-C motif) and promotes neutrophil-mediated immune response. Considering the biomedical importance of IL-17A, we developed a pathway resource of signaling events mediated by IL-17A/IL-17RA in this study. The curation of literature data pertaining to the IL-17A system was performed manually by the NetPath criteria. Using data mined from the published literature, we describe an integrated pathway reaction map of IL-17A/IL-17RA consisting of 114 proteins and 68 reactions. That includes detailed information on IL-17A/IL-17RA mediated signaling events of 9 activation/inhibition events, 17 catalysis events, 3 molecular association events, 68 gene regulation events, 109 protein expression events, and 6 protein translocation events. The IL-17A signaling pathway map data is made freely accessible through the WikiPathways Database ( https://www.wikipathways.org/index.php/Pathway : WP5242).

The temporal characteristics of the disruption of gut microbiota, serum metabolome, and cytokines by silica exposure in wistar rats

Silicosis is one of the most frequent, rapidly developing, and lethal types of pneumoconiosis. However, our understanding of the underlying mechanisms of its pathogenesis and progress remains unclear. We investigated the fundamental processes of silicosis incidence and progression using a combination of lung function testing, histopathology, 16 S rRNA, untargeted metabolomics, and cytokine chips at different exposure times (4 or 8 weeks). The results show that silica exposure damages lung tissue reduces lung function, and increases with time. Cytokines with time-specific properties were found in lung lavage fluid: IFN-γ (4 weeks; P＜0.05), TNF-α, M-CSF, GM-CSF (8 weeks; P＜0.01). In addition, silica exposure for different periods interferes to varying degrees with the metabolism of lipids. The composition of the intestinal microbiota changed with increasing exposure time and there were time-specific: Allobaculum, Turicibacter、Jeotgalicoccu、Coprococcus 1 (4 weeks; P＜0.05), Ruminococcaceae NK4A214 group、Ruminiclostridium 5 (8 weeks; P＜0.05). We found strong associations between cytokines, gut microbiota changes, and metabolic disturbances at different exposure times. These results suggest that time-specific changes in crosstalk among cytokines, the gut microbiota, and metabolites may be a potential mechanism for silica-induced lung injury.

Plasma Cytokine Profiling Reveals Differences between Silicotic Patients with Simple Silicosis and Those with Progressive Massive Fibrosis Caused by Engineered Stone

Engineered stone silicosis has become an occupational epidemic disease that progresses rapidly to progressive massive fibrosis with respiratory failure and death, and there is no effective treatment. Silica deposition in the lung triggers a series of inflammatory reactions with the participation of multiple cytokines and cellular mediators whose role in the development and progression of the disease is largely unknown. We hypothesized that differences in plasma cytokine levels exist between patients diagnosed with simple silicosis (SS) and patients diagnosed with progressive massive fibrosis (PMF). Plasma samples from 91 ES silicosis patients, diagnosed and classified by chest radiography and/or high-resolution computed tomography with SS (n = 53) and PMF (n = 38), were assayed by multiplex assays for levels of 34 cytokines. Additionally, a healthy volunteer control group (n = 22) was included. Plasma levels of a high number of cytokines were significantly higher in subjects with silicosis than in healthy control subjects. Moreover, the levels of IL-1RA, IL-8, IL-10, IL-16, IL-18, TNF-α, MIP-1α, G-CSF and VEGF were significantly elevated in PMF compared to SS patients. This study shows that plasma cytokine levels differ between healthy people and silicosis patients, and some of them are also significantly elevated in patients with PMF compared with patients with SS, which could indicate their involvement in the severity of the disease, be considered as biomarkers and could be explored as future therapeutic targets for the disease.

IL-33 Deficiency Attenuates Lung Inflammation by Inducing Th17 Response and Impacting the Th17/Treg Balance in LPS-Induced ARDS Mice via Dendritic Cells

Objectives

The characteristic pathophysiological feature of acute respiratory distress syndrome (ARDS) is a dysregulated inflammatory response. T helper 17 (Th17) cells in the lung are inflammatory cells that contribute to pulmonary inflammatory cascades. In addition, Th17/regulatory T cells (Treg cells) also play an important role in the inflammatory process. Dendritic cells (DCs) can regulate the differentiation of CD4+ T cells, including Th17 and Treg cells. Recent evidence revealed that interleukin-33 (IL-33) signaling could activate and mature DCs. Therefore, the aim of this study was to investigate the effects of IL-33 on inflammation and immunoregulation by inducing the Th17 response and influencing the Th17/Treg balance in LPS-induced ARDS.

Methods

IL-33 gene knockout mice and the administration of recombinant mouse IL-33 (rmIL-33) were used to investigate the role of IL-33 and the underlying mechanisms in an LPS-induced ARDS model. Hematoxylin and eosin (H&E) staining, wet/dry (W/D) weight ratios, cell counts, and the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-17 (IL-17), and interleukin-10 (IL-10) in bronchoalveolar lavage fluid (BALF) were investigated. The levels of IL-33, orphan nuclear receptor gamma t (RORγt), and forkhead transcription factor protein 3 (FOXP3) protein in lung tissue were evaluated by Western blotting. The mRNA expression levels of IL-33 and RORγt were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Th17 and Treg cell frequencies were determined by flow cytometry. The levels of IL-6 in the supernatant in a dendritic cell culture system were examined by ELISA.

Results

Increased expression of IL-33 was observed in mice with LPS-induced ARDS. IL-33 deficiency significantly inhibited inflammation and attenuated LPS-induced ARDS, whereas pretreatment with rmIL-33 aggravated pulmonary inflammatory response. Furthermore, depletion of IL-33 inhibited Th17 cells, significantly decreased RORγt mRNA and protein expression and IL-17 levels in BALF, and led to less differentiation of T cells into Th17 cells than Treg cells. Moreover, IL-33^-/- DCs secreted less IL-6 and IL-23 than normal control DCs.

Conclusion

IL-33 deficiency alleviated lung injury in the LPS-induced ARDS model, which was closely related to suppressing Th17 responses and regulating the Th17/Treg balance. The expansion of Th17 cells and imbalance in Th17/Treg cells may be associated with IL-6 and IL-23 secreted from IL-33-activated DCs.

Blocking Caspase-1/Gsdmd and Caspase-3/-8/Gsdme pyroptotic pathways rescues silicosis in mice

Millions of patients suffer from silicosis, but it remains an uncurable disease due to its unclear pathogenic mechanisms. Though the Nlrp3 inflammasome is involved in silicosis pathogenesis, inhibition of its classic downstream factors, Caspase-1 and Gsdmd, fails to block pyroptosis and cytokine release. To clarify the molecular mechanism of silicosis pathogenesis for new therapy, we examined samples from silicosis patients and genetic mouse models. We discovered an alternative pyroptotic pathway which requires cleavage of Gsdme by Caspases-3/8 in addition to Caspase-1/Gsdmd. Consistently, Gsdmd-/-Gsdme-/- mice showed markedly attenuated silicosis pathology, and Gsdmd-/-Gsdme-/- macrophages were resistant to silica-induced pyroptosis. Furthermore, we found that in addition to Caspase 1, Caspase-8 cleaved IL-1β in silicosis, explaining why Caspase-1-/- mice also suffered from silicosis. Finally, we found that inhibitors of Caspase-1, -3, -8 or an FDA approved drug, dimethyl fumarate, could dramatically alleviate silicosis pathology through blocking cleavage of Gsdmd and Gsdme. This study highlights that Caspase-1/Gsdmd and Caspase-3/8/Gsdme-dependent pyroptosis is essential for the development of silicosis, implicating new potential targets and drug for silicosis treatment.

HIV and Schistosoma Co-Exposure Leads to Exacerbated Pulmonary Endothelial Remodeling and Dysfunction Associated with Altered Cytokine Landscape

HIV and Schistosoma infections have been individually associated with pulmonary vascular disease. Co-infection with these pathogens is very common in tropical areas, with an estimate of six million people co-infected worldwide. However, the effects of HIV and Schistosoma co-exposure on the pulmonary vasculature and its impact on the development of pulmonary vascular disease are largely unknown. Here, we have approached these questions by using a non-infectious animal model based on lung embolization of Schistosoma mansoni eggs in HIV-1 transgenic (HIV) mice. Schistosome-exposed HIV mice but not wild-type (Wt) counterparts showed augmented pulmonary arterial pressure associated with markedly suppressed endothelial-dependent vasodilation, increased endothelial remodeling and vessel obliterations, formation of plexiform-like lesions and a higher degree of perivascular fibrosis. In contrast, medial wall muscularization was similarly increased in both types of mice. Moreover, HIV mice displayed an impaired immune response to parasite eggs in the lung, as suggested by decreased pulmonary leukocyte infiltration, small-sized granulomas, and augmented residual egg burden. Notably, vascular changes in co-exposed mice were associated with increased expression of proinflammatory and profibrotic cytokines, including IFN-γ and IL-17A in CD4⁺ and γδ T cells and IL-13 in myeloid cells. Collectively, our study shows for the first time that combined pulmonary persistence of HIV proteins and Schistosoma eggs, as it may occur in co-infected people, alters the cytokine landscape and targets the vascular endothelium for aggravated pulmonary vascular pathology. Furthermore, it provides an experimental model for the understanding of pulmonary vascular disease associated with HIV and Schistosoma co-morbidity.

BI 1015550 is a PDE4B Inhibitor and a Clinical Drug Candidate for the Oral Treatment of Idiopathic Pulmonary Fibrosis

The anti-inflammatory and immunomodulatory abilities of oral selective phosphodiesterase 4 (PDE4) inhibitors enabled the approval of roflumilast and apremilast for use in chronic obstructive pulmonary disease and psoriasis/psoriatic arthritis, respectively. However, the antifibrotic potential of PDE4 inhibitors has not yet been explored clinically. BI 1015550 is a novel PDE4 inhibitor showing a preferential enzymatic inhibition of PDE4B. In vitro, BI 1015550 inhibits lipopolysaccharide (LPS)-induced tumor necrosis factor-α (TNF-α) and phytohemagglutinin-induced interleukin-2 synthesis in human peripheral blood mononuclear cells, as well as LPS-induced TNF-α synthesis in human and rat whole blood. In vivo, oral BI 1015550 shows potent anti-inflammatory activity in mice by inhibiting LPS-induced TNF-α synthesis ex vivo and in Suncus murinus by inhibiting neutrophil influx into bronchoalveolar lavage fluid stimulated by nebulized LPS. In Suncus murinus, PDE4 inhibitors induce emesis, a well-known gastrointestinal side effect limiting the use of PDE4 inhibitors in humans, and the therapeutic ratio of BI 1015550 appeared to be substantially improved compared with roflumilast. Oral BI 1015550 was also tested in two well-known mouse models of lung fibrosis (induced by either bleomycin or silica) under therapeutic conditions, and appeared to be effective by modulating various model-specific parameters. To better understand the antifibrotic potential of BI 1015550 in vivo, its direct effect on human fibroblasts from patients with idiopathic pulmonary fibrosis (IPF) was investigated in vitro. BI 1015550 inhibited transforming growth factor-β-stimulated myofibroblast transformation and the mRNA expression of various extracellular matrix proteins, as well as basic fibroblast growth factor plus interleukin-1β-induced cell proliferation. Nintedanib overall was unremarkable in these assays, but interestingly, the inhibition of proliferation was synergistic when it was combined with BI 1015550, leading to a roughly 10-fold shift of the concentration–response curve to the left. In summary, the unique preferential inhibition of PDE4B by BI 1015550 and its anticipated improved tolerability in humans, plus its anti-inflammatory and antifibrotic potential, suggest BI 1015550 to be a promising oral clinical candidate for the treatment of IPF and other fibro-proliferative diseases.

Recent Advances in Basic and Clinical Aspects of Rheumatoid Arthritis-associated Interstitial Lung Diseases

Rheumatoid arthritis (RA) is a common autoimmune disease that mainly affects the joints and systemic organs, such as the skin, eyes, heart, gastrointestinal tract, and lungs. In particular, among various pulmonary involvements, interstitial lung disease (ILD) is closely related to the selection of anti-rheumatic drugs and the long-term prognosis of patients with RA. Although the exact pathogenesis of RA-ILD is not well defined, several mechanistic pathways, similar to those of idiopathic pulmonary fibrosis, have been elucidated recently. Conversely, RA-related autoantibodies, including anti-cyclic citrullinated peptide antibody, are detectable in circulation and in the lungs, even in the absence of articular symptoms. RA-ILD can also predate years before the occurrence of joint symptoms. This evidence supports the fact that local dysregulated mucosal immunity in the lung causes systemic autoimmunity, resulting in clinically evident polyarthritis of RA. Because the early diagnosis of RA-ILD is important, imaging tests, such as computed tomography and pulmonary function tests, are being used for early diagnosis, but there is no clear guideline for the early diagnosis of RA-ILD and selection of optimal disease-modifying anti-rheumatic drugs for the treatment of patients with RA with ILD. In addition, the efficacy of nintedanib, a new anti-fibrotic agent, for RA-ILD treatment, has been investigated recently. This review collectively discusses the basic and clinical aspects, such as pathogenesis, animal models, diagnosis, and treatment, of RA-ILD.

Pirfenidone ameliorates silica-induced lung inflammation and fibrosis in mice by inhibiting the secretion of interleukin-17A

Silicosis is a global occupational disease characterized by lung dysfunction, pulmonary inflammation, and fibrosis, for which there is a lack of effective drugs. Pirfenidone has been shown to exert anti-inflammatory and anti-fibrotic properties in the lung. However, whether and how pirfenidone is effective against silicosis remains unknown. Here, we evaluated the efficacy of pirfenidone in the treatment of early and advanced silicosis in an experimental mouse model and explored its potential pharmacological mechanisms. We found that pirfenidone alleviated silica-induced lung dysfunction, secretion of inflammatory cytokines (TNF-α, IL-1β, IL-6) and deposition of fibrotic proteins (collagen I and fibronectin) in both early and advanced silicosis models. Moreover, we observed that both 100 and 200 mg/kg pirfenidone can effectively treat early-stage silicosis, while 400 mg/kg was recommended for advanced silicosis. Mechanistically, antibody array and bioinformatic analysis showed that the pathways related to IL-17 secretion, including JAK-STAT pathway, Th17 differentiation, and IL-17 pathway, might be involved in the treatment of silicosis by pirfenidone. Further in vivo experiments confirmed that pirfenidone reduced the production of IL-17A induced by silica exposure via inhibiting STAT3 phosphorylation. Neutralizing IL-17A by anti-IL-17A antibody improved lung function and reduced pulmonary inflammation and fibrosis in silicosis animals. Collectively, our study has demonstrated that pirfenidone effectively ameliorated silica-induced lung dysfunction, pulmonary inflammation and fibrosis in mouse models by inhibiting the secretion of IL-17A.

Pneumoconiosis: current status and future prospects

ABSTRACT

Pneumoconiosis refers to a spectrum of pulmonary diseases caused by inhalation of mineral dust, usually as the result of certain occupations. The main pathological features include chronic pulmonary inflammation and progressive pulmonary fibrosis, which can eventually lead to death caused by respiratory and/or heart failure. Pneumoconiosis is widespread globally, seriously threatening global public health. Its high incidence and mortality lie in improper occupational protection, and in the lack of early diagnostic methods and effective treatments. This article reviews the epidemiology, safeguard procedures, diagnosis, and treatment of pneumoconiosis, and summarizes recent research advances and future research prospects.

A Network Pharmacology Approach to Explore the Potential Mechanisms of Yifei Sanjie Formula in Treating Pulmonary Fibrosis

Objective

Yifei Sanjie Formula (YFSJF) is an effective formula on pulmonary fibrosis (PF), which has been used in clinic for more than 30 years. In order to investigate the molecular mechanism of YFSJF in treating PF, network pharmacology was used to predict the cooperative ingredients and associated pathways.

Methods

Firstly, we collected potential active ingredients of YFSJF by TCMSP databases. Secondly, we obtained PF-associated targets through OMIM and Genecards database. Finally, metascape was applied for the analysis of GO terms and KEGG pathways.

Results

We screened out 76 potential active ingredients and 98 associated proteins. A total of 5715 items were obtained by GO enrichment analysis (P < 0.05), including 4632 biological processes, 444 cellular components, and 639 molecular functions. A total of 143 related KEGG pathways were enriched (P < 0.05), including IL-17 signaling pathway, T cell receptor signaling pathway, TNF signaling pathway, calcium signaling pathway, TH17 cell differentiation, HIF-1 signaling pathway, and PI3K-Akt signaling pathway.

Conclusion

YFSJF can interfere with immune and inflammatory response through multiple targets and pathways, which has a certain role in the treatment of PF. This study lays a foundation for future experimental research.

Regulatory T Cells: An Emerging Player in Radiation-Induced Lung Injury

Regulatory T cells (Tregs), which have long been recognized as essential regulators of both inflammation and autoimmunity, also impede effective antitumor immune response due to their immunosuppressive properties. Combined radiotherapy and immunotherapeutic interventions focusing on the removal of Tregs have recently garnered interest as a promising strategy to reverse immunosuppression. Meanwhile, Tregs are emerging as a key player in the pathogenesis of radiation-induced lung injury (RILI), a frequent and potentially life-threatening complication of thoracic radiotherapy. Recognition of the critical role of Tregs in RILI raises the important question of whether radiotherapy combined with Treg-targeting immunotherapy offers any beneficial effects in the protection of normal lung tissue. This present review focuses on the contributions of Tregs to RILI, with particular emphasis on the suspected differential role of Tregs in the pneumonitic phase and fibrotic phase of RILI. We also introduce recent progress on the potential mechanisms by which Tregs modulate RILI and the crosstalk among Tregs, other infiltrating T cells, fibrocytes, and resident epithelial cells driving disease pathogenesis. Finally, we discuss whether Tregs also hold promise as a potential target for immunotherapeutic interventions for RILI.

Inhalation: A means to explore and optimize nintedanib's pharmacokinetic/pharmacodynamic relationship

Oral nintedanib is marketed for the treatment of idiopathic pulmonary fibrosis (IPF). While effective slowing fibrosis progression, as an oral medicine nintedanib is limited. To reduce side effects and maximize efficacy, nintedanib was reformulated as a solution for nebulization and inhaled administration. To predict effectiveness treating IPF, the nintedanib pharmacokinetic/pharmacodynamic relationship was dissected. Pharmacokinetic analysis indicated oral-delivered nintedanib plasma exposure and lung tissue partitioning were not dose-proportional and resulting lung levels were substantially higher than blood. Although initial-oral absorbed nintedanib efficiently partitioned into the lung, only a quickly eliminated fraction appeared available to epithelial lining fluid (ELF). Because IPF disease appears to initiate and progress near the epithelial surface, this observation suggests short duration nintedanib exposure (oral portion efficiently partitioned to ELF) is sufficient for IPF efficacy. To test this hypothesis, exposure duration required for nintedanib activity was explored. In vitro, IPF-cellular matrix (IPF-CM) increased primary normal human fibroblast (nHLF) aggregate size and reduced nHLF cell count. IPF-CM also increased nHLF ACTA2 and COL1A expression. Whether short duration (inhalation pharmacokinetic mimic) or continuous exposure (oral pharmacokinetic mimic), nintedanib (1-100 nM) reversed these effects. In vivo, intubated silica produced a strong pulmonary fibrotic response. Once-daily (QD) 0.021, 0.21 and 2.1 mg/kg intranasal (IN; short duration inhaled exposure) and twice-daily (BID) 30 mg/kg oral (PO; long duration oral exposure) showed that at equivalent-delivered lung exposure, QD short duration inhaled nintedanib (0.21 mg/kg IN vs. 30 mg/kg PO) exhibited equivalent-to-superior activity as BID oral (reduced silica-induced elastance, alpha-smooth muscle actin, interleukin-1 beta (IL-1β) and soluble collagen). Comparatively, the increased inhaled lung dose (2.1 mg/kg IN vs. 30 mg/kg PO) exhibited increased effect by further reducing silica-induced elastance, IL-1β and soluble collagen. Neither oral nor inhaled nintedanib reduced silica-induced parenchymal collagen. Both QD inhaled and BID oral nintedanib reduced silica-induced bronchoalveolar lavage fluid macrophage and neutrophil counts with oral achieving significance. In summary, pharmacokinetic elements important for nintedanib activity can be delivered using infrequent, small inhaled doses to achieve oral equivalent-to-superior pulmonary activity.

Interleukin-22 and intestinal homeostasis: Protective or destructive?

Interleukin (IL)-22 is a member of IL-10 family cytokines with various immunologic functions. As its name implies, IL-22 is known to be secreted mainly by Th22 cells, a recently discovered lineage of CD4+ T cells. Also, Th17, Th1, natural killer cells, γδT cells, and innate immune cells along with some nonlymphoid cells have been confirmed as secondary cellular sources of IL-22. Different cell types such as bronchial and intestinal epithelial cells, keratinocytes, hepatocytes, dermal fibroblasts, and tubular epithelial cells are affected by IL-22. Both pathologic and protective roles have been attributed to IL-22 in maintaining gut homeostasis and inflammation. According to the latest fast-growing investigations, IL-22 is significantly involved in various pathologies including allergic diseases, infection, autoimmunity, and cancer development. Regulating gut immune responses, barrier integrity, and inflammation is dependent on a diverse complex of cytokines and mediators which are secreted by mucosal immune cells. Several investigations have been designed to recognize the role of IL-22 in gastrointestinal immunity. This article tries to discuss the latest knowledge on this issue and clarify the potential of IL-22 to be used in the future therapeutic approaches of intestinal disorders including inflammatory bowel diseases and colon cancer.

T Cells in Fibrosis and Fibrotic Diseases

Fibrosis is the extensive deposition of fibrous connective tissue, and it is characterized by the accumulation of collagen and other extracellular matrix (ECM) components. Fibrosis is essential for wound healing and tissue repair in response to a variety of triggers, which include infection, inflammation, autoimmune disorder, degenerative disease, tumor, and injury. Fibrotic remodeling in various diseases, such as liver cirrhosis, pulmonary fibrosis, renal interstitial fibrosis, myocardial infarction, systemic sclerosis (SSc), and graft-versus-host disease (GVHD), can impair organ function, causing high morbidity and mortality. Both innate and adaptive immunity are involved in fibrogenesis. Although the roles of macrophages in fibrogenesis have been studied for many years, the underlying mechanisms concerning the manner in which T cells regulate fibrosis are not completely understood. The T cell receptor (TCR) engages the antigen and shapes the repertoire of antigen-specific T cells. Based on the divergent expression of surface molecules and cell functions, T cells are subdivided into natural killer T (NKT) cells, γδ T cells, CD8⁺ cytotoxic T lymphocytes (CTL), regulatory T (Treg) cells, T follicular regulatory (Tfr) cells, and T helper cells, including Th1, Th2, Th9, Th17, Th22, and T follicular helper (Tfh) cells. In this review, we summarize the pro-fibrotic or anti-fibrotic roles and distinct mechanisms of different T cell subsets. On reviewing the literature, we conclude that the T cell regulations are commonly disease-specific and tissue-specific. Finally, we provide perspectives on microbiota, viral infection, and metabolism, and discuss the current advancements of technologies for identifying novel targets and developing immunotherapies for intervention in fibrosis and fibrotic diseases.

Protein Kinase C Theta Inhibition Attenuates Lipopolysaccharide-Induced Acute Lung Injury through Notch Signaling Pathway via Suppressing Th17 Cell Response in Mice

Acute lung injury (ALI)/acute respiratory distress syndrome is characterized by increased pulmonary inflammation, where T helper 17 (Th17) cells play an important regulatory role. Notch signaling critically regulates Th17 differentiation and is known to be linked with proximal T cell by protein kinase C theta (PKCθ). We hypothesized that PKCθ inhibition could attenuate ALI by suppressing Th17 response via the Notch signaling pathway. Male C57BL/6 mice were treated with phosphate-buffered saline (PBS), lipopolysaccharide (LPS), LPS and N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT, a Notch signaling inhibitor), or LPS and PKCθ inhibitor (PI), and the bronchoalveolar lavage fluid (BALF), blood, and lung tissues were harvested at 48 h after the LPS challenge. CD4⁺ T cells were treated with DAPT or PI and harvested after 72 h. PKCθ inhibition markedly attenuated pathological changes and decreased the wet to dry weight ratio of the mouse lungs. The total cell and neutrophil counts, tumor necrosis factor-α (TNF- α) in BALF, myeloperoxidase activity in lung tissue, and the leukocyte count in whole blood were markedly reduced by PKCθ inhibition. The concentration of interleukin (IL)-17 and IL-22 in BALF, and the percentage of CD4⁺IL-17A⁺ T cells in the lungs were significantly downregulated by PKCθ inhibition. A similar trend was observed for the expression of retinoic acid-related orphan receptor gamma t and IL-23 receptor after PKCθ inhibition accompanied with inactivation of the Notch signaling pathway in vivo and in vitro. Collectively, these data demonstrated that PKCθ inhibition protects against LPS-induced ALI by suppressing the differentiation and pathogenicity of Th17, at least partially, through a Notch-dependent mechanism.

Immunological Features of Paranasal Sinus Mucosa in Patients with Graves' Orbitopathy

BACKGROUND

Previous studies showed that patients with Graves' orbitopathy (GO) had concomitant mucosal abnormality within the paranasal sinuses. It remains unknown whether the immunological reactions in sinus mucosa affect the orbit inflammation in GO.

METHODS

Patients with GO underwent sinus computed tomography (CT) scans for sinus mucosal disease by two independent reviewers using the Lund-MacKay systems. Ethmoid mucosal samples were collected during orbital decompression surgeries for patients with GO and correction surgeries for patients with old orbital fractures as controls. Histological analysis and immunofluorescence were performed in all sinus mucosa tissues. Flow cytometry analysis was used to examine the immunological features of sinus mucosa in both GO and control groups.

RESULTS

Immunohistochemistry showed that the paranasal sinus mucosa of patients with GO grew swelling, with goblet cell and small vessel proliferation, endothelial cell swelling, and inflammatory cell infiltration. The number of T helper (Th)1, Th17, and gamma-delta T cells in nasal sinus mucosa of patients with GO increased significantly compared with those from controls. Further, the proportion of Th1 cells was significantly correlated with clinical activity score. In addition, there was a decreased number of regulatory T cells in patients with GO. The number of Th2 cells showed no significant difference between the two groups. Finally, the proportion of interleukin-22-producing cell subsets in gamma-delta T cells of patients with GO was significantly increased compared with those from controls.

CONCLUSIONS

Our observations illustrated a potential pathogenic role of mucosal-infiltrating T cells, which may have the possibility to aggravate inflammatory responses in GO.

Neutralization of interleukin-17A alleviates burn-induced intestinal barrier disruption via reducing pro-inflammatory cytokines in a mouse model

Background

The intestinal barrier integrity can be disrupted due to burn injury, which is responsible for local and systemic inflammatory responses. Anti-inflammation strategy is one of the proposed therapeutic approaches to control inflammatory cascade at an early stage. Interleukin-17A (IL-17A) plays a critical role in inflammatory diseases. However, the role of IL-17A in the progression of burn-induced intestinal inflammation is poorly understood. In this study, we aimed to investigate the effect of IL-17A and associated pro-inflammatory cytokines that were deeply involved in the pathogenesis of burn-induced intestinal inflammatory injury, and furthermore, we sought to determine the early source of IL-17A in the intestine.

Methods

Mouse burn model was successfully established with infliction of 30% total body surface area scald burn. The histopathological manifestation, intestinal permeability, zonula occludens-1 expression, pro-inflammatory cytokines were determined with or without IL-17A-neutralization. Flow cytometry was used to detect the major source of IL-17A⁺ cells in the intestine.

Results

Burn caused intestinal barrier damage, increase of intestinal permeability, alteration of zonula occludens-1 expressions, elevation of IL-17A, IL-6, IL-1β and tumor necrosis factor-α (TNF-α), whereas IL-17A neutralization dramatically alleviated burn-induced intestinal barrier disruption, maintained zonula occludens-1 expression, and noticeably, inhibited pro-inflammatory cytokines elevation. In addition, we observed that the proportion of intestinal IL-17A⁺Vγ4⁺ T subtype cells (but not IL-17A⁺Vγ1⁺ T subtype cells) were increased in burn group, and neutralization of IL-17A suppressed this increase.

Conclusions

The main original findings of this study are intestinal mucosa barrier is disrupted after burn through affecting the expression of pro-inflammatory cytokines, and a protective role of IL-17A neutralization for intestinal mucosa barrier is determined. Furthermore, Vγ4⁺ T cells are identified as the major early producers of IL-17A that orchestrate an inflammatory response in the burn model. These data suggest that IL-17A blockage may provide a unique target for therapeutic intervention to treat intestinal insult after burn.

Tangeretin attenuates lipopolysaccharide-induced acute lung injury through Notch signaling pathway via suppressing Th17 cell response in mice

Tangeretin, a polymethoxylated flavonoid is abundant in citrus fruits, which has been reported to inhibit inflammation by inhibiting NF-κB activation and proinflammatory cytokines. Notch blockage inhibits Th17 cells response that are involved in the development of acute lung injury (ALI). This study investigated the protective effects of tangeretin on LPS-induced ALI in mice. Male C57BL/6 mice were treated with phosphate-buffered saline (PBS), lipopolysaccharide (LPS), LPS and tangeretin, or LPS and N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT, a Notch signaling inhibitor), which were harvested at 48 h after challenged by LPS. CD4⁺ T cells were treated with tangeretin or DAPT and harvested after 72 h. Tangeretin notably attenuated pathological changes and decreased the wet to dry weight ratio of the mouse lungs. The total cell and neutrophil counts, tumor necrosis factor (TNF)-α in bronchoalveolar lavage fluid (BALF), myeloperoxidase activity of lung tissue were markedly reduced by tangeretin. The percentage of CD4+IL-17 + T cells in the lungs and the concentration of interleukin (IL)-17 and IL-22 in BALF were significantly down-regulated by tangeretin. As with the positive control (DAPT), tangeretin inhibited the activity of the Notch signaling pathway accompanied with the down-regulation of acid-related orphan receptor gamma t and IL-23 receptor expression. This study demonstrated that tangeretin protects against LPS-induced ALI by suppressing Th17 response at least partially, through a Notch-dependent mechanism.

Fibrogenesis in Chronic DSS Colitis is Not Influenced by Neutralisation of Regulatory T Cells, of Major T Helper Cytokines or Absence of IL-13

Mechanisms underlying fibrogenesis in chronic colitis are largely unknown. There is an urgent need for clinical markers and identification of targets to prevent, treat and limit intestinal fibrosis. This study investigated the contribution of major T cell cytokines and T regulatory cells (Tregs) to inflammation and fibrosis induced in a model of experimental colitis by oral intake of dextran sodium sulphate (DSS) in wild type and IL-13 knock-out C57Bl/6 mice. Inflammation and fibrosis were scored by macroscopic and histological examination and fibrosis was quantified by hydroxyproline. Numbers of Tregs and IFN-γ⁺, IL-13⁺ and IL-17A⁺ CD4⁺ T helper (Th) cells in mesenteric lymph nodes increased during chronic DSS administration and mRNA for IFN-γ and IL-17 in the inflamed colon tissue was upregulated. However, antibody-mediated neutralisation of IFN-γ or IL-17A/F in a therapeutic setting had no effect on chronic intestinal inflammation and fibrosis. Antibody-mediated depletion of Tregs did not enhance fibrosis, nor did IL-13 deficiency have an effect on the fibrotic disease. These data argue against an important contribution of Tregs and of the cytokines IFN-γ, IL-13, IL-17A, IL-17F in the induction and/or control of fibrosis in this Crohn's disease like murine model.

Dihydrotanshinone I Alleviates Crystalline Silica-Induced Pulmonary Inflammation by Regulation of the Th Immune Response and Inhibition of STAT1/STAT3

Occupational exposure to crystalline silica (CS) results in a persistent pulmonary inflammatory response that eventually leads to abnormal tissue repair, disability, and death. The inflammatory-immune responses occur in the early stages of CS exposure, and both innate and adaptive immunity are involved. CD4+ T cells play a pivotal role in the pathogenesis of CS-induced pulmonary disease, which has no proven curative therapy. Dihydrotanshinone I (DHI), a natural product isolated from Salvia miltiorrhiza Bunge (Danshen), has anti-inflammatory and immunomodulatory properties. However, whether DHI has a protective effect on CS-induced lung disease, how it influences the Th immune response, and the potential underlying molecular mechanism(s) have not been fully clarified. In this study, DHI treatment of CS-exposed mice reduced the expression of proinflammatory cytokines and the infiltration of immune cells. It significantly ameliorated CS-induced pulmonary inflammation by attenuating T helper (Th)1 and Th17 responses, which were tightly related to the inhibition of STAT1 and STAT3. DHI significantly altered Th2 cytokines but not the Th2 nuclear transcription factor. Furthermore, our study found that DHI treatment also affected regulatory T cell activity in CS-injured mice. Taken together, our findings indicated that DHI could modulate Th responses and alleviate CS-induced pulmonary inflammation, suggesting a novel application of DHI in CS-induced pulmonary disease.

Combination of L-Arginine and L-Norvaline protects against pulmonary fibrosis progression induced by bleomycin in mice

Pulmonary fibrosis (PF) progression may be involved with arginine (Arg) metabolism and immune balance. The present study aimed to explore the effects of L-Arginine (L-Arg) and L-Norvaline (L-Nor) on bleomycin (BLM)-induced PF in mice, meanwhile, and observe dynamic changes of Arg metabolism, immune balance and crosstalk between them in PF progression. Followed intratracheal instillation of BLM or saline, Kunming mice were treated orally with saline, L-Arg, L-Nor and L-Arg + L-Nor three times a day. And the mice were sacrificed on Day 3, 14 and 28 after treatment. Changes of body weight, lung index, lung hydroxyproline and histopathology were analyzed to evaluate the PF degree. Peripheral blood Arg, Citrulline (Cit), Ornithine (Orn) and Proline (Pro), lung NO, NOS and arginase were analyzed to evaluate the Arg metabolism. Peripheral blood Tregs, Th17 and γδT cells were analyzed to evaluate the immune balance. Our data showed that combination of L-Arg and L-Nor dynamically reversed the weight loss, decreased lung index and hydroxyproline, and improved lung histopathological damages induced by BLM. The combination dynamically and significantly rectified Tregs, Th17, γδT and Tregs/Th17 abnormal changes. Meanwhile, these disorders of peripheral blood Arg, Cit, Orn, Pro, Orn/Cit and Pro/Orn, and lung NO, iNOS and TNOS were also improved accordingly. These results demonstrated that combination of L-Arg and L-Nor had inhibitory effects on BLM-induced PF progression, possibly due to their corrective action on immune imbalance, Arg metabolism disorder and crosstalk abnormality in the progression of PF.

Type 3 ILCs in Lung Disease

The lungs represent a complex immune setting, balancing external environmental signals with a poised immune response that must protect from infection, mediate tissue repair, and maintain lung function. Innate lymphoid cells (ILCs) play a central role in tissue repair and homeostasis, and mediate protective immunity in a variety of mucosal tissues, including the lung. All three ILC subsets are present in the airways of both mice and humans; and ILC2s shown to have pivotal roles in asthma, airway hyper-responsiveness, and parasitic worm infection. The involvement of ILC3s in respiratory diseases is less well-defined, but they are known to be critical in homeostasis, infection and inflammation at other mucosal barriers, such as the gut. Moreover, they are important players in the IL17/IL22 axis, which is key to lung health. In this review, we discuss the emerging role of ILC3s in the context of infectious and inflammatory lung diseases, with a focus on data from human subjects.

Emerging Role of Immunosuppression in Diseases Induced by Micro- and Nano-Particles: Time to Revisit the Exclusive Inflammatory Scenario

Fibrosis, cancer, and autoimmunity developing upon particle exposure have been exclusively linked with uncontrolled inflammatory processes. The critical role of inflammation is now challenged by several contradictory observations indicating that the emergence of these chronic disorders may result from non-inflammatory events. A growing number of studies reveals that micro- and nano-particles can cause exaggerated and persistent immunosuppression characterized by the release of potent anti-inflammatory cytokines (IL-10 and TGF-β), and the recruitment of major regulatory immune cells (M2 macrophages, T and B regs, and MDSC). This persistent immunosuppressive environment is initially established to limit early inflammation but contributes later to fibrosis, cancer, and infection. Immunosuppression promotes fibroblast proliferation and matrix element synthesis and subverts innate and adaptive immune surveillance against tumor cells and microorganisms. This review details the contribution of immunosuppressive cells and their derived immunoregulatory mediators and delineates the mutual role of inflammatory vs. immunosuppressive mechanisms in the pathogenesis of chronic diseases induced by particles. The consideration of these new results explains how particle-related diseases can develop independently of chronic inflammation, enriches current bioassays predicting particle toxicity and suggests new clinical strategies for treating patients affected by particle-associated diseases.

IL-17A contributes to HSV1 infection-induced acute lung injury in a mouse model of pulmonary fibrosis

BACKGROUND

Patients with idiopathic pulmonary fibrosis (IPF) often experience acute exacerbation (AE) after an episode of common cold.

AIMS

To establish a mouse model of virus infection-induced AE-IPF and investigate the mechanism underlying the AE-IPF.

METHODS

Herpes simplex virus 1 (HSV1) was inoculated intranasally to wild-type (WT) and IL-17A gene knockout (IL-17A^-/- ) mice 21 days after intratracheal administration of bleomycin (BLM).

RESULTS

HSV1 infection caused acute exacerbation in mice with BLM-induced fibrosis. Compared with the BLM+Saline mice, the mice with BLM+HSV1 showed significantly higher acute lung injury (ALI) score (P < 0.0001), lower survival rate (100% vs 21.4%, P < 0.0001), poorer lung function and higher inflammatory response representing by increased total inflammatory cells in bronchoalveolar lavage fluid (BALF) (P = 0.0323), increased proportion of Th17 cells in peripheral blood (P = 0.0004) and higher inflammatory factors in BALF. In addition, HSV1 infection increased the expression of endoplasmic reticulum stress (ERS)-related proteins in mice with BLM-induced fibrosis. The inhibition of ERS by tauroursodeoxycholic acid (TUDCA, an ERS inhibitor) significantly reduced the IL-17A levels in BALF (P = 0.0140) and TH17 cells in the peripheral blood (P = 0.0084) of mice with BLM+HSV1, suggesting that suppression of ERS may reduce TH17 response in mice with AE-IPF. Compared with WT mice with BLM+HSV1, IL-17A^-/- mice with BLM+HSV1 had lower ALI score (P = 0.0119), higher survival rate (78.6% vs 21.4%, P = 0.004), improved lung function, and milder inflammatory response.

CONCLUSIONS

HSV1 infection in addition to BLM-induced IPF can successfully establish AE-IPF in mice. IL-17A and ERS promote lung inflammation in AE-IPF development.

Innate lymphoid cells in organ fibrosis

Innate lymphoid cells (ILCs) are a recently identified family of lymphoid effector cells. ILCs are mainly clustered into 3 groups based on their unique cytokine profiles and transcription factors typically attributed to the subsets of T helper cells. ILCs have a critical role in the mucosal immune response through promptly responding to pathogens and producing large amount of effector cytokines of type 1, 2, or 3 responses. In addition to the role of early immune responses against infections, ILCs, particularly group 2 ILCs (ILC2), have recently gained attention for modulating remodeling and fibrosis especially in the mucosal tissues. Herein, we overview the current knowledge in this area, highlighting roles of ILCs on fibrosis in the mucosal tissues, especially focusing on the gut and lung. We also discuss some new directions for future research by extrapolating from knowledge derived from studies on Th cells.

Neutrophil Extracellular Traps Formation and Aggregation Orchestrate Induction and Resolution of Sterile Crystal-Mediated Inflammation

The formation of neutrophil extracellular traps (NETs) to immobilize pathogens represents a novel antimicrobial strategy of the immune system. The microcrystals related to human diseases are classified into endogenous microcrystals, including monosodium urate (MSU), calcium pyrophosphate dihydrate, calcium carbonate, calcium phosphate, calcium oxalate, cholesterol, and exogenous material like crystals from silica. Although microcrystals possess distinct compositions and shapes, they have a common characteristic: they stimulate neutrophils to release NETs. In low and high densities, neutrophils form NETs and aggregated NETs (aggNETs) that reportedly orchestrate the initiation and resolution of sterile crystal-mediated inflammation, respectively. Here, we summarize the different roles of NETs and aggNETs stimulated by the crystals mentioned above in related inflammatory reactions. The NETosis-derived products may represent a potential therapeutic target in crystal-mediated diseases.

Allicin attenuates lipopolysaccharide‑induced acute lung injury in neonatal rats via the PI3K/Akt pathway

Allicin is an oxygenated carotenoid derivative that exhibits strong antioxidant activity, which effectively removes reactive oxygen species from the body and has important roles in disease prevention and treatment. Therefore, the present study aimed to investigate whether allicin attenuates lipopolysaccharide (LPS)‑induced acute lung injury (ALI) in neonatal rats and the potential underlying mechanisms. An LPS‑induced ALI neonatal rat model was utilized to assess the therapeutic value and mechanisms of allicin. Following allicin treatment, increases in lung wet/dry ratio and the lung protein concentration were significantly suppressed in LPS‑induced ALI neonatal rats. Furthermore, ELISA results demonstrated that allicin significantly reduced the levels of malondialdehyde, tumor necrosis factor‑α and interleukin‑6, and increased superoxide dismutase activity, in the bronchoalveolar lavage fluid of LPS‑treated rats. Additionally, allicin administration increased the protein expression of Bcl‑2 and reduced the activity of caspase‑3/-9, as determined by western blotting or ELISA, respectively, and increased phosphatidylinositol 3‑kinase (PI3K) and phosphorylated‑Akt protein levels, in LPS‑treated ALI neonatal rats. The results of the present study indicate that allicin attenuate LPS‑induced ALI in neonatal rats by ameliorating oxidative stress, inflammation and apoptosis via the PI3K/Akt pathway. Allicin may be used for development of a novel drug for treatment of ALI.

Immune cells and autoantibodies in pulmonary arterial hypertension

Analyses of immunity in pulmonary arterial hypertension (PAH) support the notion that maladaptation of the immune response exists. Altered immunity is an increasingly recognized feature of PAH. Indeed, a delicate balance between immunity and tolerance exists and any disturbance may result in chronic inflammation or autoimmunity. This is suggested by infiltration of various immune cells (e.g. macrophages, T and B lymphocytes) in remodeled pulmonary vessels. In addition, several types of autoantibodies directed against antinuclear antigens, endothelial cells (ECs) and fibroblasts have been found in idiopathic and systemic sclerosis-associated PAH. These autoantibodies may play an important role in EC apoptosis and in the expression of cell adhesion molecules. This review article provides an overview of immunity pathways highlighting their potential roles in pulmonary vascular remodeling in PAH and the possibility of future targeted therapy.

Role of interleukin 17 in TGF-β signaling-mediated renal interstitial fibrosis

BACKGROUND

Several studies suggest IL-17 is involved in the pathogenesis of organ fibrosis. The exact role of IL-17 in renal interstitial fibrosis has not been fully elucidated.

METHODS

We compared the histopathology of renal fibrosis as well as profibrotic TGF-β signaling in wild-type (WT) and IL-17 knock-out (IL-17^-/-) mice using UUO as the disease model. To find out the possible mechanisms involved in the exacerbated renal fibrosis happened to IL-17^-/- mice, we analyzed the pattern of ECM synthesis by different fibroblasts cultured with IL-17 and associated signaling mediators.

RESULTS

On day3 and day7, IL-17^-/- mice developed more severe renal fibrosis compared with WT mice. IL-17 had an inhibitory factor in TGF-β-induced renal fibroblast activation and ECM synthesis, and sequentially in renal interstitial fibrosis, via down-regulation of Smad -independent pathway (p38MAPK and AKT phosphorylations).

CONCLUSION

IL-17 acts an inhibitory factor in TGF-β-induced renal fibroblast activation and ECM synthesis, and sequentially in renal interstitial fibrosis, via down-regulation of Smad-independent pathway (p38MAPK and AKT phosphorylations). Clarifying the novel regulatory mechanisms of fibrosis by the cytokine IL-17 may lead to a new therapeutic approach for progressive renal disease and fibrosis.

The Th1/Th17 balance dictates the fibrosis response in murine radiation-induced lung disease

Radiotherapy can result in lung diseases pneumonitis or fibrosis dependent on patient susceptibility. Herein we used inbred and genetically altered mice to investigate whether the tissue adaptive immune response to radiation injury influences the development of radiation-induced lung disease. Six inbred mouse strains were exposed to 18 Gy whole thorax irradiation and upon respiratory distress strains prone to pneumonitis with fibrosis presented an increased pulmonary frequency of Thelper (Th)17 cells which was not evident in strains prone solely to pneumonitis. The contribution of Th17 cells to fibrosis development was supported as the known enhanced fibrosis of toll-like receptor 2&4 deficient mice, compared to C57BL/6J mice, occurred with earlier onset neutrophilia, and with increased levels of pulmonary Th17, but not Th1, cells following irradiation. Irradiated Il17−/− mice lacked Th17 cells, and were spared both fibrosis and pneumonitis, as they survived to the end of the experiment with a significantly increased pulmonary Th1 cell frequency, only. Interferon-γ−/− mice, deficient in Th1 cells, developed a significantly enhanced fibrosis response compared to that of C57BL/6J mice. The tissue adaptive immune response influences the pulmonary disease response to radiotherapy, as an increased Th17 cell frequency enhanced and a Th1 response spared, fibrosis in mice.

IL-17 in the lung: the good, the bad, and the ugly

The IL-17 family of cytokines has emerged over the last two decades as a pleiotropic group of molecules that function in a wide variety of both beneficial and detrimental (pathological) processes, mainly in mucosal barrier tissue. The beneficial effects of IL-17 expression are especially important in the lung, where exposure to foreign agents is abundant. IL-17A plays an important role in protection from both extracellular bacteria and fungi, as well as viruses that infect cells of the mucosal tracts. IL-17 coregulated cytokines, such as IL-22, are involved in maintaining epithelial cell homeostasis and participate in epithelial cell repair/regeneration following inflammatory insults. Thus, the IL-17/IL-22 axis is important in both responding to, and recovering from, pathogens. However, aberrant expression or overexpression of IL-17 cytokines contributes to a number of pathological outcomes, including asthma, pneumonitis, and generation or exacerbation of pulmonary fibrosis. This review covers the good, bad, and ugly aspects of IL-17 in the lung.

Lung-resident γδ T cells and their roles in lung diseases

γδ T cells are greatly enriched in mucosal and epithelial sites, such as the skin, respiratory, digestive and reproductive tracts, and they are defined as tissue-resident immune cells. In these tissues, the characteristics and biological roles of γδ T cells are distinguished from each other. The lungs represent the most challenging immunological dilemma for the host, and they have their own effective immune system. The abundance of γδ T cells, an estimated 8-20% of resident pulmonary lymphocytes in the lung, maintains lung tissue homeostasis. In this review, we summarize the recent research progress regarding lung-resident γδ T cells, including their development, residency and immune characteristics, and discuss the involvement of γδ T cells in infectious diseases of the lung, including bacterial, viral and fungal infections; lung allergic disease; lung inflammation and fibrosis; and lung cancer.

Association between SNPs at IL-17A and IL-17F and susceptibility to accelerated silicosis

The association between single nucleotide polymorphisms (SNPs) in the interleukin (IL)-17 gene and silicosis has been evaluated in different populations. The aim of the present study was to analyze the association between SNPs at IL-17A (−832A/G) and IL-17F (+7488A/G) and susceptibility to accelerated silicosis in the Iranian Kurdish population. We studied 48 patients with accelerated silicosis and 62 controls. Genomic DNA was isolated using the “salting out” method. PCR-RFLP was performed for all SNPs typing. The frequencies of A/A, A/G, and G/G genotypes at IL-17A (−832A/G) were 4 (8.33%), 23 (47.92%), and 21 (43.75%) in patients and 5 (8.06%), 35 (56.45%), and 22 (35.48%) in controls, respectively. The frequencies of A and G alleles at IL-17 (−832A/G) were 31 (32.29%) and 65 (67.71%) in patients, and 45 (36.29%) and 79 (63.71%) in the controls, respectively. The frequencies of A/A, A/G, and G/G genotypes at IL-17F (+7488A/G) were 1 (2.08%), 47 (97.92%), and 0 (0%) in patients, and 11 (17.74%), 51 (82.26%), and 0 (0%) in the controls, respectively. The frequencies of A and G alleles at IL-17F (+7488A/G) were 49 (51.04%) and 47 (48.96%) in patients, and 73 (58.87%) and 51 (41.13%) in the controls, respectively. IL-17F (+7488A/G) genotype was more frequent among the cases compared with controls (97.92% vs. 82.26%). The frequency of the IL-17F (+7488A/G) genotype was significantly greater in patients with accelerated silicosis (odds ratio = 10.13 95%; confidence interval = 1.2–81.5; p = 0.008). The IL-17F (+7488A/G) genotype revealed a significantly increased risk of accelerated silicosis ( p < 0.05). The IL-17F (+7488 G) allele was associated with an increased risk of accelerated silicosis, but in the case of the IL-17A (−832A/G) polymorphism, a significant association was not observed.