No abstract

Epithelial to mesenchymal transition (EMT), whereby fully differentiated epithelial cells transition to a mesenchymal phenotype has been implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF). CXCR3 and its ligands are recognized to play a protective role in pulmonary fibrosis. In this study, we investigated the presence and extent of EMT and CXCR3 expression in human IPF surgical lung biopsies and assessed whether CXCR3 and its ligand CXCL9 modulate EMT in alveolar epithelial cells. Coexpression of the epithelial maker thyroid transcription factor-1, and mesenchymal marker α-smooth muscle actin and CXCR3 expression was examined by immunohistochemical staining of IPF surgical lung biopsies. Epithelial and mesenchymal marker expression was examined by quantitative real-time PCR, Western blotting, and immunofluorescence in human alveolar epithelial (A549) cells treated with TGF-β1 and CXCL9, whilst Smad2, Smad3, and Smad7 expression and cellular localization examined by Western blotting. We found that significantly more cells were undergoing EMT in fibrotic versus normal areas of lung in IPF surgical lung biopsy samples. CXCR3 was expressed by type II pneumocytes and fibroblasts in fibrotic areas in close proximity to cells undergoing EMT. In vitro, CXCL9 abrogated TGF-β1 induced EMT. A decrease in TGF-β1 induced phosphorylation of Smad2 and Smad3 occurred with CXCL9 treatment. This was associated with increased shuttling of Smad7 from the nucleus to the cytoplasm where it inhibits Smad phosphorylation. This suggests a role for EMT in the pathogenesis of IPF and provides a novel mechanism for the inhibitory effects of CXCL9 on TGF-β1 induced EMT.

Highlights• Systemic sclerosis is an idiopathic autoimmune disease, therapies are limited • Dysregulated T and B cell cytokines promote myofibroblast activation and fibrosis • Communication between fibroblasts and immune cells alters immune cell phenotype • Fibroblasts drive polarization, survival, and differentiation of T cells• Targeting both immune and stromal cells may be of therapeutic benefit in SSc

This is a repository copy of c-Rel orchestrates energy-dependent epithelial and macrophage reprogramming in fibrosis.

Pulmonary fibrosis is a progressive and fatal disease that involves the remodeling of the distal airspace and the lung parenchyma, which results in compromised gas exchange. The median survival time once diagnosed is less than three years. Interleukin (IL)-13 has been shown to play a role in a number of inflammatory and fibrotic diseases. IL-13 modulates its effector functions via a complex receptor system that includes the IL-4 receptor (R) α, IL-13Rα1, and the IL-13Rα2. IL-13Rα1 binds IL-13 with low affinity, yet, when it forms a complex with IL-4α, it binds with much higher affinity, inducing the effector functions of IL-13. IL-13Rα2 binds IL-13 with high affinity but has a short cytoplasmic tail and has been shown to act as a nonsignaling decoy receptor. Transfection of fibroblasts and epithelial cells with IL-13Rα2 inhibited the IL-13 induction of soluble collagen, TGF-β, and CCL17. Adenoviral overexpression of IL-13Rα2 in the lung reduced bleomycin-induced fibrosis. Our work shows that overexpression of IL-13Rα2 inhibits the IL-13 induction of fibrotic markers in vitro and inhibits bleomycin-induced pulmonary fibrosis. In summary our study highlights the antifibrotic nature of IL-13Ra2.

No abstract

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial pneumonia that is characterized by excessive fibroproliferation. Key effector cells in IPF are myofibroblasts that are recruited from three potential sources: resident fibroblasts, fibrocytes and epithelial cells. We hypothesized that IPF myofibroblasts from different sources of origin displayed unique genetic profiles and distinct functional characteristics. Primary human pulmonary fibroblasts (normal and IPF), fibrocytes and epithelial cells were activated into myofibroblasts using the pro fibrotic factors TGF β and TNF α. The resulting myofibroblasts were characterized using cell proliferation, soluble collagen, ELISA and contractility assays, and human fibrosis PCR arrays. Genes of significance were validated in whole human lung and validated by immunohistochemistry on human lung sections. Fibroblast-derived myofibroblasts exhibited the highest expression increase in pro fibrotic genes, and genes involved in extracellular matrix remodelling and signal transduction. Functional studies demonstrated that myofibroblasts derived from fibrocytes expressed most soluble collagen and CCL18 but were least proliferative of all myofibroblast progeny. Activated IPF fibroblasts displayed highest contraction and highest levels of CCL2 production. This study has identified novel differences in both gene expression and functional characteristics in different myofibroblast populations. Further investigation into the myofibroblast phenotype may lead to potential therapeutic targets in the future field of IPF research.

Cross-species transmission of avian influenza A viruses (IAVs) into humans could represent the first step of a future pandemic1. Multiple factors limiting the spillover and adaptation of avian IAVs in humans have been identified, but they are not sufficient to explain which virus lineages are more likely to cross the species barrier1,2. Here, we identified human BTN3A33 (butyrophilin subfamily 3 member A3) as a potent inhibitor of avian but not human IAVs. We determined that BTN3A3 is constitutively expressed in human airways and its antiviral activity evolved in primates. We show that BTN3A3 restriction acts at the early stages of virus replication by inhibiting avian IAV vRNA transcription. We identified residue 313 in the viral nucleoprotein (NP) as the genetic determinant of BTN3A3 sensitivity (313F, or rarely 313L in avian viruses) or evasion (313Y or 313V in human viruses). However, several serotypes of avian IAVs that spilled over into humans in recent decades evade BTN3A3 restriction. In these cases, BTN3A3 evasion is due to substitutions (N, H or Q) in NP residue 52 that is adjacent to residue 313 in the NP structure4. Importantly, we identified more than 150 avian IAV lineages with a BTN3A3-resistant genotype. In conclusion, sensitivity or resistance to BTN3A3 is another factor to consider in the risk assessment of the zoonotic potential of avian influenza viruses.