Pre-clinical proof-of-concept of anti-fibrotic activity of caveolin-1 scaffolding domain peptide LTI-03 in ex vivo precision cut lung slices from patients with Idiopathic Pulmonary Fibrosis

Rationale: While rodent lung fibrosis models are routinely used to evaluate novel antifibrotics, these models have largely failed to predict clinical efficacy of novel drug candidates for Idiopathic Pulmonary Fibrosis (IPF). Moreover, single target therapeutic strategies for IPF have failed and current multi-target standard of care drugs are not curative. Caveolin-1 (CAV-1) is an integral membrane protein, which, via its caveolin scaffolding domain (CSD), interacts with caveolin binding domains (CBD). CAV-1 regulates homeostasis, and its expression is decreased in IPF lungs. LTI-03 is a seven amino acid peptide derived from the CSD and formulated for dry powder inhalation; it was well tolerated in normal volunteers ( NCT04233814 ) and a safety trial is underway in IPF patients ( NCT05954988 ). Objectives: Anti-fibrotic efficacy of LTI-03 and other CSD peptides has been observed in IPF lung monocultures, and rodent pulmonary, dermal, and heart fibrosis models. This study aimed to characterize progressive fibrotic activity in IPF PCLS explants and to evaluate the antifibrotic effects of LTI-03 and nintedanib in this model. Methods: First, CBD regions were identified in IPF signaling proteins using in silico analysis. Then, IPF PCLS (n=8) were characterized by COL1A1 immunostaining, multiplex immunoassays, and bulk RNA sequencing following treatment every 12hrs with LTI-03 at 0.5, 3.0, or 10 μM; nintedanib at 0.1 μM or 1 μM; or control peptide (CP) at 10 μM. Measurements and Main Results: CBDs were present in proteins implicated in IPF, including VEGFR, FGFR and PDGFR. Increased expression of profibrotic mediators indicated active fibrotic activity in IPF PCLS over five days. LTI-03 dose dependently decreased COL1A1 staining, and like nintedanib, decreased profibrotic proteins and transcripts. Unlike nintedanib, LTI-03 did not induce cellular necrosis signals. Conclusion: IPF PCLS explants demonstrate molecular activity indicative of fibrosis during 5 days in culture and LTI-03 broadly attenuated pro-fibrotic proteins and pathways, further supporting the potential therapeutic effectiveness of LTI-03 for IPF.

Interleukin 33 supports squamous cell carcinoma growth via a dual effect on tumour proliferation, migration and invasion, and T cell activation

Interleukin (IL)-33 is an important cytokine in the tumour microenvironment; it is known to promote the growth and metastasis of solid cancers, such as gastric, colorectal, ovarian and breast cancer. Our group demonstrated that the IL-33/ST2 pathway enhances the development of squamous cell carcinoma (SCC). Conversely, other researchers have reported that IL-33 inhibits tumour progression. In addition, the crosstalk between IL-33, cancer cells and immune cells in SCC remains unknown. The aim of this study was to investigate the effect of IL-33 on the biology of head and neck SCC lines and to evaluate the impact of IL-33 neutralisation on the T cell response in a preclinical model of SCC. First, we identified epithelial and peritumoural cells as a major local source of IL-33 in human SCC samples. Next, in vitro experiments demonstrated that the addition of IL-33 significantly increased the proliferative index, motility and invasiveness of SCC-25 cells, and downregulated MYC gene expression in SCC cell lines. Finally, IL-33 blockade significantly delayed SCC growth and led to a marked decrease in the severity of skin lesions. Importantly, anti-IL-33 monoclonal antibody therapy increase the percentage of CD4+IFNγ+ T cells and decreased CD4+ and CD8+ T cells secreting IL-4 in tumour-draining lymph nodes. Together, these data suggest that the IL-33/ST2 pathway may be involved in the crosstalk between the tumour and immune cells by modulating the phenotype of head and neck SCC and T cell activity. IL-33 neutralisation may offer a novel therapeutic strategy for SCC.

Caveolin scaffolding domain (CSD) peptide LTI-2355 modulates the phagocytic and synthetic activity of lung derived myeloid cells in Idiopathic Pulmonary Fibrosis (IPF) and Post-acute sequelae of COVID-fibrosis (PASC-F)

Rationale

The role of the innate immune system in Idiopathic Pulmonary Fibrosis (IPF) remains poorly understood. However, a functional myeloid compartment is required to remove dying cells and cellular debris, and to mediate innate immune responses against pathogens. Aberrant macrophage activity has been described in patients with Post-acute sequelae of COVID fibrosis (PASC-F). Therefore, we examined the functional and synthetic properties of myeloid cells isolated from normal donor lung and lung explant tissue from both IPF and PASC-F patients and explored the effect of LTI-2355, a Caveolin Scaffolding Domain (CSD) peptide, on these cells.

Methods & Results

CD45 + myeloid cells isolated from lung explant tissue from IPF and PASC-F patients exhibited an impaired capacity to clear autologous dead cells and cellular debris. Uptake of pathogen-coated bioparticles was impaired in myeloid cells from both fibrotic patient groups independent of type of pathogen highlighting a cell intrinsic functional impairment. LTI-2355 improved the phagocytic activity of both IPF and PASC-F myeloid cells, and this improvement was paired with decreased pro-inflammatory and pro-fibrotic synthetic activity. LTI-2355 was also shown to primarily target CD206-expressing IPF and PASC-F myeloid cells.

Conclusions

Primary myeloid cells from IPF and PASC-F patients exhibit dysfunctional phagocytic and synthetic properties that are reversed by LTI-2355. Thus, these studies highlight an additional mechanism of action of a CSD peptide in the treatment of IPF and progressive fibrotic lung disease.

Standard of care drugs do not modulate activity of senescent primary human lung fibroblasts

Cellular senescence is crucial in the progression of idiopathic pulmonary fibrosis (IPF), but it is not evident whether the standard-of-care (SOC) drugs, nintedanib and pirfenidone, have senolytic properties. To address this question, we performed colorimetric and fluorimetric assays, qRT-PCR, and western blotting to evaluate the effect of SOC drugs and D + Q on senescent normal and IPF lung fibroblasts. In this study, we found that SOC drugs did not provoke apoptosis in the absence of death ligand in normal or IPF senescent lung fibroblasts. Nintedanib increased caspase-3 activity in the presence of Fas Ligand in normal but not in IPF senescent fibroblasts. Conversely, nintedanib enhanced B cell lymphoma 2 expression in senescent IPF lung fibroblasts. Moreover, in senescent IPF cells, pirfenidone induced mixed lineage kinase domain-like pseudokinase phosphorylation, provoking necroptosis. Furthermore, pirfenidone increased transcript levels of FN1 and COL1A1 in senescent IPF fibroblasts. Lastly, D + Q augmented growth differentiation factor 15 (GDF15) transcript and protein levels in both normal and IPF senescent fibroblasts. Taken together, these results establish that SOC drugs failed to trigger apoptosis in senescent primary human lung fibroblasts, possibly due to enhanced Bcl-2 levels by nintedanib and the activation of the necroptosis pathway by pirfenidone. Together, these data revealed the inefficacy of SOC drugs to target senescent cells in IPF.

HER2 drives lung fibrosis by activating a metastatic cancer signature in invasive lung fibroblasts

Progressive tissue fibrosis, including idiopathic pulmonary fibrosis (IPF), is characterized by excessive recruitment of fibroblasts to sites of tissue injury and unremitting extracellular matrix deposition associated with severe morbidity and mortality. However, the molecular mechanisms that control progressive IPF have yet to be fully determined. Previous studies suggested that invasive fibroblasts drive disease progression in IPF. Here, we report profiling of invasive and noninvasive fibroblasts from IPF patients and healthy donors. Pathway analysis revealed that the activated signatures of the invasive fibroblasts, the top of which was ERBB2 (HER2), showed great similarities to those of metastatic lung adenocarcinoma cancer cells. Activation of HER2 in normal lung fibroblasts led to a more invasive genetic program and worsened fibroblast invasion and lung fibrosis, while antagonizing HER2 signaling blunted fibroblast invasion and ameliorated lung fibrosis. These findings suggest that HER2 signaling may be a key driver of fibroblast invasion and serve as an attractive target for therapeutic intervention in IPF.

Antibody-mediated depletion of CCR10+EphA3+ cells ameliorates fibrosis in IPF

Idiopathic pulmonary fibrosis (IPF) is characterized by aberrant repair that diminishes lung function via mechanisms that remain poorly understood. CC chemokine receptor (CCR10) and its ligand CCL28 were both elevated in IPF compared with normal donors. CCR10 was highly expressed by various cells from IPF lungs, most notably stage-specific embryonic antigen-4-positive mesenchymal progenitor cells (MPCs). In vitro, CCL28 promoted the proliferation of CCR10+ MPCs while CRISPR/Cas9-mediated targeting of CCR10 resulted in the death of MPCs. Following the intravenous injection of various cells from IPF lungs into immunodeficient (NOD/SCID-γ, NSG) mice, human CCR10+ cells initiated and maintained fibrosis in NSG mice. Eph receptor A3 (EphA3) was among the highest expressed receptor tyrosine kinases detected on IPF CCR10+ cells. Ifabotuzumab-targeted killing of EphA3+ cells significantly reduced the numbers of CCR10+ cells and ameliorated pulmonary fibrosis in humanized NSG mice. Thus, human CCR10+ cells promote pulmonary fibrosis, and EphA3 mAb-directed elimination of these cells inhibits lung fibrosis.

Differential Responses to Targeting Matrix Metalloproteinase 9 in Idiopathic Pulmonary Fibrosis

Rationale: Aberrant lung remodeling in idiopathic pulmonary fibrosis (IPF) is characterized by elevated MMP9 (matrix metalloproteinase 9) expression, but the precise role of this matrix metalloproteinase in this disease has yet to be fully elucidated.Objectives: To evaluate antifibrotic effects of MMP9 inhibition on IPF.Methods: Quantitative genomic, proteomic, and functional analyses both in vitro and in vivo were used to determine MMP9 expression in IPF cells and the effects of MMP9 inhibition on profibrotic mechanisms.Measurements and Main Results: In the present study, we demonstrate that MMP9 expression was increased in airway basal cell (ABC)-like cells from IPF lungs compared with ABC cells from normal lungs. The inhibition of MMP9 activity with an anti-MMP9 antibody, andecaliximab, blocked TGF-β1 (transforming growth factor β1)-induced Smad2 phosphorylation. However, in a subset of cells from patients with IPF, TGF-β1 activation in their ABC-like cells was unaffected or enhanced by MMP9 blockade (i.e., nonresponders). Further analysis of nonresponder ABC-like cells treated with andecaliximab revealed an association with type 1 IFN expression, and the addition of IFNα to these cells modulated both MMP9 expression and TGF-β1 activation. Finally, the inhibition of MMP9 ameliorated pulmonary fibrosis induced by responder lung cells but not a nonresponder in a humanized immunodeficient mouse model of IPF.Conclusions: Together, these data demonstrate that MMP9 regulates the activation of ABC-like cells in IPF and that targeting this MMP might be beneficial to a subset of patients with IPF who show sufficient expression of type 1 IFNs.

DNA-PKcs modulates progenitor cell proliferation and fibroblast senescence in idiopathic pulmonary fibrosis

BACKGROUND

Recent studies have highlighted the contribution of senescent mesenchymal and epithelial cells in Idiopathic Pulmonary Fibrosis (IPF), but little is known regarding the molecular mechanisms that regulate the accumulation of senescent cells in this disease. Therefore, we addressed the hypothesis that the loss of DNA repair mechanisms mediated by DNA protein kinase catalytic subunit (DNA-PKcs) in IPF, promoted the accumulation of mesenchymal progenitors and progeny, and the expression of senescent markers by these cell types.

METHODS

Surgical lung biopsy samples and lung fibroblasts were obtained from patients exhibiting slowly, rapidly or unknown progressing IPF and lung samples lacking any evidence of fibrotic disease (i.e. normal; NL). The expression of DNA-Pkcs in lung tissue was assessed by quantitative immunohistochemical analysis. Chronic inhibition of DNA-PKcs kinase activity was mimicked using a highly specific small molecule inhibitor, Nu7441. Proteins involved in DNA repair (stage-specific embryonic antigen (SSEA)-4⁺ cells) were determined by quantitative Ingenuity Pathway Analysis of transcriptomic datasets (GSE103488). Lastly, the loss of DNA-PKc was modeled in a humanized model of pulmonary fibrosis in NSG SCID mice genetically deficient in PRKDC (the transcript for DNA-PKcs) and treated with Nu7441.

RESULTS

DNA-PKcs expression was significantly reduced in IPF lung tissues. Chronic inhibition of DNA-PKcs by Nu7441 promoted the proliferation of SSEA4⁺ mesenchymal progenitor cells and a significant increase in the expression of senescence-associated markers in cultured lung fibroblasts. Importantly, mesenchymal progenitor cells and their fibroblast progeny derived from IPF patients showed a loss of transcripts encoding for DNA damage response and DNA repair components. Further, there was a significant reduction in transcripts encoding for PRKDC (the transcript for DNA-PKcs) in SSEA4⁺ mesenchymal progenitor cells from IPF patients compared with normal lung donors. In SCID mice lacking DNA-PKcs activity receiving IPF lung explant cells, treatment with Nu7441 promoted the expansion of progenitor cells, which was observed as a mass of SSEA4⁺ CgA⁺ expressing cells.

CONCLUSIONS

Together, our results show that the loss of DNA-PKcs promotes the expansion of SSEA4⁺ mesenchymal progenitors, and the senescence of their mesenchymal progeny.

PD-L1 on invasive fibroblasts drives fibrosis in a humanized model of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with unremitting extracellular matrix deposition, leading to a distortion of pulmonary architecture and impaired gas exchange. Fibroblasts from IPF patients acquire an invasive phenotype that is essential for progressive fibrosis. Here, we performed RNA sequencing analysis on invasive and noninvasive fibroblasts and found that the immune checkpoint ligand CD274 (also known as PD-L1) was upregulated on invasive lung fibroblasts and was required for the invasive phenotype of lung fibroblasts, is regulated by p53 and FAK, and drives lung fibrosis in a humanized IPF model in mice. Activating CD274 in IPF fibroblasts promoted invasion in vitro and pulmonary fibrosis in vivo. CD274 knockout in IPF fibroblasts and targeting CD274 by FAK inhibition or CD274-neutralizing antibodies blunted invasion and attenuated fibrosis, suggesting that CD274 may be a novel therapeutic target in IPF.

Expansion of commensal fungus Wallemia mellicola in the gastrointestinal mycobiota enhances the severity of allergic airway disease in mice

The gastrointestinal microbiota influences immune function throughout the body. The gut-lung axis refers to the concept that alterations of gut commensal microorganisms can have a distant effect on immune function in the lung. Overgrowth of intestinal Candida albicans has been previously observed to exacerbate allergic airways disease in mice, but whether subtler changes in intestinal fungal microbiota can affect allergic airways disease is less clear. In this study we have investigated the effects of the population expansion of commensal fungus Wallemia mellicola without overgrowth of the total fungal community. Wallemia spp. are commonly found as a minor component of the commensal gastrointestinal mycobiota in both humans and mice. Mice with an unaltered gut microbiota community resist population expansion when gavaged with W. mellicola; however, transient antibiotic depletion of gut microbiota creates a window of opportunity for expansion of W. mellicola following delivery of live spores to the gastrointestinal tract. This phenomenon is not universal as other commensal fungi (Aspergillus amstelodami, Epicoccum nigrum) do not expand when delivered to mice with antibiotic-depleted microbiota. Mice with Wallemia-expanded gut mycobiota experienced altered pulmonary immune responses to inhaled aeroallergens. Specifically, after induction of allergic airways disease with intratracheal house dust mite (HDM) antigen, mice demonstrated enhanced eosinophilic airway infiltration, airway hyperresponsiveness (AHR) to methacholine challenge, goblet cell hyperplasia, elevated bronchoalveolar lavage IL-5, and enhanced serum HDM IgG1. This phenomenon occurred with no detectable Wallemia in the lung. Targeted amplicon sequencing analysis of the gastrointestinal mycobiota revealed that expansion of W. mellicola in the gut was associated with additional alterations of bacterial and fungal commensal communities. We therefore colonized fungus-free Altered Schaedler Flora (ASF) mice with W. mellicola. ASF mice colonized with W. mellicola experienced enhanced severity of allergic airways disease compared to fungus-free control ASF mice without changes in bacterial community composition.

CCR10+ epithelial cells from idiopathic pulmonary fibrosis lungs drive remodeling

Idiopathic pulmonary fibrosis (IPF) is a devastating fibrotic lung disease of unknown etiology and limited therapeutic options. In this report, we characterize what we believe is a novel CCR10+ epithelial cell population in IPF lungs. There was a significant increase in the percentage of CCR10+ epithelial cells in IPF relative to normal lung explants and their numbers significantly correlated to lung remodeling in humanized NSG mice. Cultured CCR10-enriched IPF epithelial cells promoted IPF lung fibroblast invasion and collagen 1 secretion. Single-cell RNA sequencing analysis showed distinct CCR10+ epithelial cell populations enriched for inflammatory and profibrotic transcripts. Consistently, cultured IPF but not normal epithelial cells induced lung remodeling in humanized NSG mice, where the number of CCR10+ IPF, but not normal, epithelial cells correlated with hydroxyproline concentration in the remodeled NSG lungs. A subset of IPF CCR10hi epithelial cells coexpress EphA3 and ephrin A signaling induces the expression of CCR10 by these cells. Finally, EphA3+CCR10hi epithelial cells induce more consistent lung remodeling in NSG mice relative to EphA3-CCR10lo epithelial cells. Our results suggest that targeting epithelial cells, highly expressing CCR10, may be beneficial in IPF.

Divergent roles for Clusterin in Lung Injury and Repair

Lung fibrosis is an unabated wound healing response characterized by the loss and aberrant function of lung epithelial cells. Herein, we report that extracellular Clusterin promoted epithelial cell apoptosis whereas intracellular Clusterin maintained epithelium viability during lung repair. Unlike normal and COPD lungs, IPF lungs were characterized by significantly increased extracellular Clusterin whereas the inverse was evident for intracellular Clusterin. In vitro and in vivo studies demonstrated that extracellular Clusterin promoted epithelial cell apoptosis while intercellular Clusterin modulated the expression of the DNA repair proteins, MSH2, MSH6, OGG1 and BRCA1. The fibrotic response in Clusterin deficient (CLU-/-) mice persisted after bleomycin and it was associated with increased DNA damage, reduced DNA repair responses, and elevated cellular senescence. Remarkably, this pattern mirrored that observed in IPF lung tissues. Together, our results show that cellular localization of Clusterin leads to divergent effects on epithelial cell regeneration and lung repair during fibrosis.

Antifibrotic role of vascular endothelial growth factor in pulmonary fibrosis

The chronic progressive decline in lung function observed in idiopathic pulmonary fibrosis (IPF) appears to result from persistent nonresolving injury to the epithelium, impaired restitution of the epithelial barrier in the lung, and enhanced fibroblast activation. Thus, understanding these key mechanisms and pathways modulating both is essential to greater understanding of IPF pathogenesis. We examined the association of VEGF with the IPF disease state and preclinical models in vivo and in vitro. Tissue and circulating levels of VEGF were significantly reduced in patients with IPF, particularly in those with a rapidly progressive phenotype, compared with healthy controls. Lung-specific overexpression of VEGF significantly protected mice following intratracheal bleomycin challenge, with a decrease in fibrosis and bleomycin-induced cell death observed in the VEGF transgenic mice. In vitro, apoptotic endothelial cell–derived mediators enhanced epithelial cell injury and reduced epithelial wound closure. This process was rescued by VEGF pretreatment of the endothelial cells via a mechanism involving thrombospondin-1 (TSP1). Taken together, these data indicate beneficial roles for VEGF during lung fibrosis via modulating epithelial homeostasis through a previously unrecognized mechanism involving the endothelium.

Elevated VEGF is associated with less severe disease in IPF patients, and VEGF overexpression ameliorates bleomycin-induced lung fibrosis in a murine model.

Role of growth arrest-specific gene 6 in the development of fungal allergic airway disease in mice

Growth arrest-specific gene (Gas)6 is a secreted vitamin K-dependent protein with pleiotropic effects via activation of receptor tyrosine kinase Tyro3, Axl, and Mertk receptors, but little is known about its role in allergic airway disease. We investigated the role of Gas6 in the development of fungal allergic airway disease in mice. The immune response was evaluated in Gas6-deficient (Gas6-/-) and wild-type (WT) mice and in recombinant Gas6-treated WT mice during Aspergillus fumigatus-induced allergic airway disease. Gas6 plasma levels were significantly elevated in adult clinical asthma of all severities compared with subjects without asthma. In a murine model of fungal allergic airway disease, increased protein expression of Axl and Mertk were observed in the lung. Airway hyperresponsiveness (AHR), whole lung Th2 cytokine levels, goblet cell metaplasia, and peribronchial fibrosis were ameliorated in Gas6-/- mice compared with WT mice with fungal allergic airway disease. Intranasal Gas6 administration into WT mice had a divergent effect on airway inflammation and AHR. Specifically, a total dose of 2 μg of exogenous Gas6 (i.e., low dose) significantly increased whole lung Th2 cytokine levels and subsequent AHR, whereas a total dose of 7 μg of exogenous Gas6 (i.e., high dose) significantly suppressed Th1 and Th2 cytokines and AHR compared with appropriate control groups. Mechanistically, Gas6 promoted Th2 activation via its highest affinity receptor Axl expressed by myeloid DCs. Intranasal administration of Gas6 consistently exacerbated airway remodeling compared with control WT groups. These results demonstrate that Gas6 enhances several features of fungal allergic airway disease.

Axl receptor blockade protects from invasive pulmonary aspergillosis in mice

Aspergillus fumigatus is a sporulating fungus found ubiquitously in the environment, which is quickly contained in the immunocompetent host but can cause lethal invasive aspergillosis in the immunocompromised host. We have recently demonstrated that Axl (one member of the Tyro3, Axl, Mertk receptor family) is a key regulator of antiviral immune responses in the lung. In this study, we investigated the role of Axl in antifungal immunity in a model of invasive pulmonary aspergillosis (IPA). In this model, Aspergillus fumigatus conidia were administered into the lungs of neutrophil-depleted mice, and the mice were monitored for survival, lung inflammatory response, and fungal clearance. The lethal effect of IPA was significantly reduced in anti-Axl mAb-treated mice compared with IgG control-treated mice. Targeting Axl significantly inhibited pulmonary inflammation, including the expression of IL-1β, IL-6, TNF-α, and chitinase-like proteins in whole lung. Further, anti-Axl mAb treatment significantly increased M1 macrophages that highly expressed inducible NO synthase and decreased M2 macrophages that expressed Arginase 1 and were found in inflammatory zone protein (Fizz1). More importantly, anti-Axl mAb treatment significantly increased the number of IFN-γ-producing T cells and NK cells compared with the IgG control group during IPA. Together, our results demonstrate that the Axl mAb treatment is protective during invasive aspergillosis in neutropenic mice. Collectively, these data suggest a potential deleterious role for Axl during primary immune responses directed against A. fumigatus and novel therapeutic strategy for IPA.

Targeting interleukin-13 with tralokinumab attenuates lung fibrosis and epithelial damage in a humanized SCID idiopathic pulmonary fibrosis model

The aberrant fibrotic and repair responses in the lung are major hallmarks of idiopathic pulmonary fibrosis (IPF). Numerous antifibrotic strategies have been used in the clinic with limited success, raising the possibility that an effective therapeutic strategy in this disease must inhibit fibrosis and promote appropriate lung repair mechanisms. IL-13 represents an attractive target in IPF, but its disease association and mechanism of action remains unknown. In the present study, an overexpression of IL-13 and IL-13 pathway markers was associated with IPF, particularly a rapidly progressive form of this disease. Targeting IL-13 in a humanized experimental model of pulmonary fibrosis using tralokinumab (CAT354) was found to therapeutically block aberrant lung remodeling in this model. However, targeting IL-13 was also found to promote lung repair and to restore epithelial integrity. Thus, targeting IL-13 inhibits fibrotic processes and enhances repair processes in the lung.

A micro RNA processing defect in rapidly progressing idiopathic pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis exhibits differential progression from the time of diagnosis but the molecular basis for varying progression rates is poorly understood. The aim of the present study was to ascertain whether differential miRNA expression might provide one explanation for rapidly versus slowly progressing forms of IPF.

Methodology and Principal Findings

miRNA and mRNA were isolated from surgical lung biopsies from IPF patients with a clinically documented rapid or slow course of disease over the first year after diagnosis. A quantitative PCR miRNA array containing 88 of the most abundant miRNA in the human genome was used to profile lung biopsies from 9 patients with rapidly progressing IPF, 6 patients with slowly progressing IPF, and 10 normal lung biopsies. Using this approach, 11 miRNA were significantly increased and 36 were significantly decreased in rapid biopsies compared with normal biopsies. Slowly progressive biopsies exhibited 4 significantly increased miRNA and 36 significantly decreased miRNA compared with normal lung. Among the miRNA present in IPF with validated mRNA targets were those with regulatory effects on epithelial-mesenchymal transition (EMT). Five miRNA (miR-302c, miR-423-5p, miR-210, miR-376c, and miR-185) were significantly increased in rapid compared with slow IPF lung biopsies. Additional analyses of rapid biopsies and fibroblasts grown from the same biopsies revealed that the expression of AGO1 and AGO2 (essential components of the miRNA processing RISC complex) were lower compared with either slow or normal lung biopsies and fibroblasts.

Conclusion

These findings suggest that the development and/or clinical progression of IPF might be the consequence of aberrant miRNA processing.

TLR9 differentiates rapidly from slowly progressing forms of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis is characterized by diffuse alveolar damage and severe fibrosis, resulting in a steady worsening of lung function and gas exchange. Because idiopathic pulmonary fibrosis is a generally progressive disorder with highly heterogeneous disease progression, we classified affected patients as either rapid or slow progressors over the first year of follow-up and then identified differences between the two groups to investigate the mechanism governing rapid progression. Previous work from our laboratory has demonstrated that Toll-like receptor 9 (TLR9), a pathogen recognition receptor that recognizes unmethylated CpG motifs in bacterial and viral DNA, promotes myofibroblast differentiation in lung fibroblasts cultured from biopsies of patients with idiopathic pulmonary fibrosis. Therefore, we hypothesized that TLR9 functions as both a sensor of pathogenic molecules and a profibrotic signal in rapidly progressive idiopathic pulmonary fibrosis. Indeed, TLR9 was present at higher concentrations in surgical lung biopsies from rapidly progressive patients than in tissue from slowly progressing patients. Moreover, fibroblasts from rapid progressors were more responsive to the TLR9 agonist, CpG DNA, than were fibroblasts from slowly progressing patients. Using a humanized severe combined immunodeficient mouse, we then demonstrated increased fibrosis in murine lungs receiving human lung fibroblasts from rapid progressors compared with mice receiving fibroblasts from slowly progressing patients. This fibrosis was exacerbated by intranasal CpG challenges. Furthermore, CpG induced the differentiation of blood monocytes into fibrocytes and the epithelial-to-mesenchymal transition of A549 lung epithelial cells. These data suggest that TLR9 may drive the pathogenesis of rapidly progressive idiopathic pulmonary fibrosis and may serve as a potential indicator for this subset of the disease.

Delta-like 4 differentially regulates murine CD4 T cell expansion via BMI1

BACKGROUND

Studies have shown that Notch is essential for the maintenance of a T cell Th2 phenotype in vivo. It has also been shown that Notch ligands have diverse functions during T cell activation. We chose to investigate the role of Notch ligands during the Th2 response.

PRINCIPAL FINDINGS

We studied the relationship of two Notch ligands, delta-like 4 and jagged-1, to T cell proliferation in C57 Bl/6 mice. Our findings indicate that jagged-1 does not affect the rate of T cell proliferation in any subset examined. However, delta-like 4 causes an increase in the expansion of Th2 memory cells and a decrease in effector cell proliferation. Our in vivo studies indicate that the Notch system is dynamically regulated, and that blocking one Notch ligand increases the effective concentration of other Notch ligands, thus altering the response. Examination of genes related to the Notch pathway revealed that the Notch receptors were increased in memory T cells. Expression of BMI1, a gene involved in T cell proliferation, was also higher in memory T cells. Further experiments demonstrated that Notch directly regulates the expression of the BMI1 gene in T cells and may govern T cell proliferation through this pathway.

CONCLUSIONS

From these experiments we can make several novel conclusions about the role of Notch ligands in T cell biology. The first is that delta-like 4 suppresses effector cell proliferation and enhances Th2 memory cell proliferation. The second is that blocking one Notch ligand in vivo effectively increases the concentration of other Notch ligands, which can then alter the response.

Notch ligands jagged-1 and delta-like 4 differentially regulate effector and memory CD4+ T cell expansion during Th2 inflammation (90.21)

Notch ligand jagged-1 is constitutively expressed on dendritic cells, whereas Notch ligand delta-4 is induced by TLRs. It has been hypothesized that jagged-1 is important for directing Th2 responses, while delta-4 plays a role in suppressing Th2 cytokines. To determine the role of jagged-1 in Th2 responses, we administered anti jagged-1 antibody to mice during the formation of S. Mansoni induced lung granulomas in sensitized mice. Our results showed a higher amount of IL-4 in lymph nodes and an increase in the CD4 effector cell population (CD44hi CD62lo). To determine if this increase in effector cells arose from an increase in effector or memory cell proliferation, we transferred either memory (CD44hiCD62L+CCR7+) or effector cells into congenic S. Mansoni sensitized mice, induced granuloma formation, and administered anti jagged-1 antibody. Our results indicate that effector cell expansion is significantly reduced in the absence of jagged-1, and central memory cell expansion is increased under the same conditions. This occurred in an antigen specific manner and was true regardless of if the inflammation was Th1 or Th2 in nature. Additional experiments revealed that delta-4 had the opposite effect as jagged-1. A blockade of delta-4 during Th2 inflammation caused an increase in effector cell proliferation, thus defining opposing roles for these two molecules in directing memory and effector cell expansion.

Funding provided by NIH: N0105330-397736

Cross-sectional analysis of the implant?abutment interface

The purpose of this study was to develop a technique to evaluate the implant-abutment gap of an external hexagon implant system as a function of radius. Six implants of 3.75 mm in diameter (Conexao Sistema de Protese Ltda, Sao Paulo, Brazil) and their respective abutments were screw connected and torqued to 20 N cm(-1). The implants were mounted in epoxy assuring an implant long-axis position perpendicular to the vertical axis. Each implant was grounded through its thickness parallel to implant long-axis at six different distance interval. Implant-abutment gap distances were recorded along the implant-abutment region for each section. Individual measurements were related to their radial position through trigonometric inferences. A sixth degree polynomial line fit approach determined radial adaptation patterns for each implant. Micrographs along implant sections showed a approximately 300 mum length implant-abutment engagement region. All implants presented communication between external and internal regions through connection gaps and inaccurate implant-abutment alignment. Average gap distances were not significantly different between implants (P > 0.086). Polynomial lines showed implant-abutment gap values below 10 mum from 0 mum to approximately 250 mum of the implant-abutment engagement region. Gap distances significantly increased from approximately 250 mum to the outer radius of the implant-abutment engagement region. The technique described provided a broader scenario of the implant-abutment gap adaptation compared with previous work concerning implant-abutment gap determination, and should be considered for better understanding mechanical aspects or biological effects of implant-abutment adaptation on peri-implant tissues.

Protective role of CCL6 during severe sepsis through interferon-γ generation and interferon-producing killer dendritic cells recruitment (44.18)

Our group has previously demonstrated that CCL6 enhanced antimicrobial immunity during sepsis through an unknown mechanism. The goal of this study was to investigate the mechanism involved in the protective role of CCL6 during the severe sepsis. C57BL/6 transgenically overexpressing CCL6 (Tg) in the lung and wild type (WT) mice were submitted to cecal ligation and puncture (CLP) and sham operation, and survival was evaluated for up to 7 days post-CLP. Cells from peritoneal cavity (PC) were obtained 3 days after surgery. The CCL6 Tg group exhibited greater levels of CCL6 in the lung and PC when compared to WT group after sham and CLP surgery. While CCL6 Tg mice presented 90% of survival at day 7 only 20% of WT mice survived. High levels of interferon-γ (IFN-γ) were detected in the PC of CCL6 Tg mice at 3 days post-CLP. Also, cells obtained from PC of these mice produced significantly levels of IFN-γ. When CCL6 Tg mice received anti-IFN-γ prior CLP, only 20% were alive. At 3 days after sham and CLP operation, the number of natural killer (NK) cells and interferon-producing killer dendritic cells (IKDCs) was increased in the peritoneal cavity of CCL6 Tg mice when compared to WT mice. These data suggest that the protective role of CCL6 may be due to its ability to contain the consequences of an inappropriate type 2-cytokine response during anti-pathogen responses. CCL6 may achieve this through promotion of IFN-γ and NK cells and IKDCs recruitment.

Virulence of Sporothrix schenckii conidia and yeast cells, and their susceptibility to nitric oxide

The involvement of nitric oxide (NO) in macrophage (M phi) fungicidal activity against Sporothrix schenckii, and the relationship between NO susceptibility and the differential virulence of conidia and yeast cells, were investigated. Confirming a previously reported correlation between the length of time in culture and virulence of S. schenckii, conidia isolated from 12-day mycelial cultures (Ss-12) were less virulent to mice than conidia from 7-day cultures (Ss-7) or yeast cells. Indicative of NO production, infected animals showed a significant increase in serum levels of nitrite that was lower in mice infected with Ss-12 than in mice infected with Ss-7 or yeast. Stimulation of murine M phi with interferon-gamma (IFN-gamma) induced NO production and inhibition of fungal growth. The cytotoxic activity of M phi against Ss-12 was significantly greater than against Ss-7 or yeast cells, the highly virulent fungal forms. The addition of NO synthase inhibitors abrogated M phi cytotoxic activity against all fungal forms. The phagocytic activity of M phi against Ss-7 was significantly lower than against Ss-12 or yeast cells. Although the ingestion of fungal cells triggered the oxidative burst in M phi, the fungicidal activity was not altered in the presence of superoxide dismutase (SOD) and catalase. In addition, Ss-12 and yeast cells were more susceptible than Ss-7 to the direct fungicidal activity of the NO donors S-nitroso-N-acetyl-DL-penicillamine (SNAP), S-nitrosoglutathione (GSNO) and 3-morpholinosydnonimine (SIN-1). The results of this study indicate that NO is a key cytotoxic mediator involved in the murine M phi defence against S. schenckii, and that the virulence of Ss-7, Ss-12 and yeast cells may be related to a differential susceptibility to NO.

Effects of jarastatin, a novel snake venom disintegrin, on neutrophil migration and actin cytoskeleton dynamics

A new disintegrin, an RGD-containing peptide of 6 kDa called jarastatin, was purified from Bothrops jararaca venom. It is a potent inhibitor of platelet aggregation induced by ADP, collagen, and thrombin. The effect of jarastatin on neutrophil migration in vivo and in vitro and on the actin cytoskeleton dynamics of these cells was investigated. Incubation in vitro with jarastatin significantly inhibited, in a concentration-dependent manner, the chemotaxis of human neutrophils toward fMLP, IL-8, and jarastatin itself. Despite this inhibitory effect, jarastatin induced neutrophil chemotaxis. A significant increase of F-actin content was observed in jarastatin-treated neutrophils. Furthermore, as demonstrated by confocal microscopy after FITC-phalloidin labeling, these cells accumulated F-actin at the plasmalemma, a distribution similar to that observed in fMLP-stimulated cells. Pretreatment of mice with jarastatin inhibited neutrophil migration into peritoneal cavities induced by carrageenan injection. The results suggest that binding of jarastatin to neutrophil integrins promotes cellular activation and triggers a dynamic alteration of the actin filament system and that this is one of the first event in integrin-mediated signaling.