Jiangning Tan

C-X-C Motif Chemokine 13 (CXCL13) Is a Prognostic Biomarker of Idiopathic Pulmonary Fibrosis

RATIONALE C-X-C motif chemokine 13 (CXCL13) mediates B-cell trafficking and is increased, proportionately to disease activity, in many antibody-mediated syndromes. Dysregulated B cells have recently been implicated in idiopathic pulmonary fibrosis (IPF) pathogenesis. OBJECTIVES To determine if CXCL13 is associated with IPF progression. METHODS CXCL13 was measured in lungs by DNA microarray and immunohistochemistry, and in plasma by ELISA. MEASUREMENTS AND MAIN RESULTS CXCL13 mRNA was threefold and eightfold greater in IPF lungs (n = 92) compared with chronic obstructive pulmonary disease (COPD) (n = 191) and normal (n = 108) specimens, respectively (P < 0.0001). IPF lungs also showed increased CXCL13 staining. Plasma CXCL13 concentrations (pg/ml) were greater in 95 patients with IPF (94 ± 8) than in 128 subjects with COPD (53 ± 9) and 57 normal subjects (35 ± 3) (P < 0.0001). Circulating CXCL13 levels were highest in patients with IPF with pulmonary artery hypertension (P = 0.01) or acute exacerbations (P = 0.002). Six-month survival of patients with IPF in the highest quartile of plasma CXCL13 was 65 ± 10% versus 93 ± 10% in the others (hazard ratio, 5.5; 95% confidence interval, 1.8-16.9; P = 0.0008). CXCL13 increases by more than 50% in IPF serial assays, irrespective of initial values, also presaged respiratory failure (hazard ratio, 7.2; 95% confidence interval, 1.3-40.0; P = 0.008). In contrast, CXCL13 clinical associations in subjects with COPD were limited to modest correlations with FEV1 (P = 0.05) and progression of radiographic emphysema (P = 0.05). CONCLUSIONS CXCL13 is increased and is a prognostic biomarker in patients with IPF, and more so than in patients with COPD. This contrast indicates CXCL13 overexpressions are intrinsic to IPF, rather than an epiphenomenon of lung injury. The present data implicate CXCL13 and B cells in IPF pathogenesis, and support considerations for trials of specific B-cell-targeted therapies in patients with this intractable disease.

Plasma B Lymphocyte Stimulator and B Cell Differentiation in Idiopathic Pulmonary Fibrosis Patients

We hypothesized B cells are involved in the pathogenesis of idiopathic pulmonary fibrosis (IPF), a progressive, restrictive lung disease that is refractory to glucocorticoids and other nonspecific therapies, and almost invariably lethal. Accordingly, we sought to identify clinically associated B cell–related abnormalities in these patients. Phenotypes of circulating B cells were characterized by flow cytometry. Intrapulmonary processes were evaluated by immunohistochemistry. Plasma B lymphocyte stimulating factor (BLyS) was assayed by ELISA. Circulating B cells of IPF subjects were more Ag differentiated, with greater plasmablast proportions (3.1 ± 0.8%) than in normal controls (1.3 ± 0.3%) (p < 0.03), and the extent of this differentiation correlated with IPF patient lung volumes (r = 0.44, p < 0.03). CD20+ B cell aggregates, diffuse parenchymal and perivascular immune complexes, and complement depositions were all prevalent in IPF lungs, but much less prominent or absent in normal lungs. Plasma concentrations of BLyS, an obligate factor for B cell survival and differentiation, were significantly greater (p < 0.0001) in 110 IPF (2.05 ± 0.05 ng/ml) than among 53 normal (1.40 ± 0.04 ng/ml) and 90 chronic obstructive pulmonary disease subjects (1.59 ± 0.05 ng/ml). BLyS levels were uniquely correlated among IPF patients with pulmonary artery pressures (r = 0.58, p < 0.0001). The 25% of IPF subjects with the greatest BLyS values also had diminished 1-y survival (46 ± 11%), compared with those with lesser BLyS concentrations (81 ± 5%) (hazard ratio = 4.0, 95% confidence interval = 1.8–8.7, p = 0.0002). Abnormalities of B cells and BLyS are common in IPF patients, and highly associated with disease manifestations and patient outcomes. These findings have implications regarding IPF pathogenesis and illuminate the potential for novel treatment regimens that specifically target B cells in patients with this lung disease.

miR-155 in the progression of lung fibrosis in systemic sclerosis

BackgroundMicroRNA (miRNA) control key elements of mRNA stability and likely contribute to the dysregulated lung gene expression observed in systemic sclerosis associated interstitial lung disease (SSc-ILD). We analyzed the miRNA gene expression of tissue and cells from patients with SSc-ILD. A chronic lung fibrotic murine model was used.MethodsRNA was isolated from lung tissue of 12 patients with SSc-ILD and 5 controls. High-resolution computed tomography (HRCT) was performed at baseline and 2–3 years after treatment. Lung fibroblasts and peripheral blood mononuclear cells (PBMC) were isolated from healthy controls and patients with SSc-ILD. miRNA and mRNA were analyzed by microarray, quantitative polymerase chain reaction, and/or Nanostring; pathway analysis was performed by DNA Intelligent Analysis (DIANA)-miRPath v2.0 software. Wild-type and miR-155 deficient (miR-155ko) mice were exposed to bleomycin.ResultsLung miRNA microarray data distinguished patients with SSc-ILD from healthy controls with 185 miRNA differentially expressed (q < 0.25). DIANA-miRPath revealed 57 Kyoto Encyclopedia of Genes and Genomes pathways related to the most dysregulated miRNA. miR-155 and miR-143 were strongly correlated with progression of the HRCT score. Lung fibroblasts only mildly expressed miR-155/miR-21 after several stimuli. miR-155 PBMC expression strongly correlated with lung function tests in SSc-ILD. miR-155ko mice developed milder lung fibrosis, survived longer, and weaker lung induction of several genes after bleomycin exposure compared to wild-type mice.ConclusionsmiRNA are dysregulated in the lungs and PBMC of patients with SSc-ILD. Based on mRNA-miRNA interaction analysis and pathway tools, miRNA may play a role in the progression of the disease. Our findings suggest that targeting miR-155 might provide a novel therapeutic strategy for SSc-ILD.

Ubiquitin carboxyl-terminal hydrolase-L5 promotes TGFβ-1 signaling by de-ubiquitinating and stabilizing Smad2/Smad3 in pulmonary fibrosis.

Transforming growth factor β-1 (TGFβ-1)-induced phosphorylation of transcription factors Smad2 and Smad3 plays a crucial role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). However, the molecular regulation of Smad2/Smad3 proteins stability remains a mystery. Here, we show that ubiquitin carboxyl-terminal hydrolase-L5 (UCHL5 or UCH37) de-ubiquitinates both Smad2 and Smad3, up-regulates their stability, and promotes TGFβ-1-induced expression of profibrotic proteins, such as fibronectin (FN) and α-smooth muscle actin (α-SMA). Inhibition or down-regulation of UCHL5 reduced Smad2/Smad3 levels and TGFβ-1-induced the expression of FN and α-SMA in human lung fibroblast. We demonstrate that Smad2 and Smad3 ubiquitination was diminished by over-expression of UCHL5, while it was enhanced by inhibition or down-regulation of UCHL5. UCHL5 is highly expressed in IPF lungs. UCHL5, Smad2, and Smad3 levels were increased in bleomycin-injured lungs. Administration of UCHL5 inhibitor, b-AP15, reduced the expression of FN, type I collagen, Smad2/Smad3, and the deposition of collagen in lung tissues in a bleomycin-induced model of pulmonary fibrosis. Our studies provide a molecular mechanism by which UCHL5 mitigates TGFβ-1 signaling by stabilizing Smad2/Smad3. These data indicate that UCHL5 may contribute to the pathogenesis of IPF and may be a potential therapeutic target.

Autoreactivity to glucose regulated protein 78 links emphysema and osteoporosis in smokers.

Rationale Emphysema and osteoporosis are epidemiologically associated diseases of cigarette smokers. The causal mechanism(s) linking these illnesses is unknown. We hypothesized autoimmune responses may be involved in both disorders. Objectives To discover an antigen-specific autoimmune response associated with both emphysema and osteoporosis among smokers. Methods Replicate nonbiased discovery assays indicated that autoimmunity to glucose regulated protein 78 (GRP78), an endoplasmic reticulum chaperone and cell surface signaling receptor, is present in many smokers. Subject assessments included spirometry, chest CT scans, dual x-ray absorptiometry, and immunoblots for anti-GRP78 IgG. Anti-GRP78 autoantibodies were isolated from patient plasma by affinity chromatography, leukocyte functions assessed by flow cytometry, and soluble metabolites and mediators measured by immunoassays. Measurements and Main Results Circulating anti-GRP78 IgG autoantibodies were detected in plasma specimens from 86 (32%) of the 265 smoking subjects. Anti-GRP78 autoantibodies were singularly prevalent among subjects with radiographic emphysema (OR 3.1, 95%CI 1.7–5.7, p = 0.003). Anti-GRP78 autoantibodies were also associated with osteoporosis (OR 4.7, 95%CI 1.7–13.3, p = 0.002), and increased circulating bone metabolites (p = 0.006). Among emphysematous subjects, GRP78 protein was an autoantigen of CD4 T-cells, stimulating lymphocyte proliferation (p = 0.0002) and IFN-gamma production (p = 0.03). Patient-derived anti-GRP78 autoantibodies had avidities for osteoclasts and macrophages, and increased macrophage NFkB phosphorylation (p = 0.005) and productions of IL-8, CCL-2, and MMP9 (p = 0.005, 0.007, 0.03, respectively). Conclusions Humoral and cellular GRP78 autoimmune responses in smokers have numerous biologically-relevant pro-inflammatory and other deleterious actions, and are associated with emphysema and osteoporosis. These findings may have relevance for the pathogenesis of smoking-associated diseases, and development of biomarker immunoassays and/or novel treatments for these disorders.

Loss of Twist1 in the Mesenchymal Compartment Promotes Increased Fibrosis in Experimental Lung Injury by Enhanced Expression of CXCL12

Idiopathic pulmonary fibrosis (IPF) is a disease characterized by the accumulation of apoptosis-resistant fibroblasts in the lung. We have previously shown that high expression of the transcription factor Twist1 may explain this prosurvival phenotype in vitro. However, this observation has never been tested in vivo. We found that loss of Twist1 in COL1A2+ cells led to increased fibrosis characterized by very significant accumulation of T cells and bone marrow–derived matrix-producing cells. We found that Twist1-null cells expressed high levels of the T cell chemoattractant CXCL12. In vitro, we found that the loss of Twist1 in IPF lung fibroblasts increased expression of CXCL12 downstream of increased expression of the noncanonical NF-κB transcription factor RelB. Finally, blockade of CXCL12 with AMD3100 attenuated the exaggerated fibrosis observed in Twist1-null mice. Transcriptomic analysis of 134 IPF patients revealed that low expression of Twist1 was characterized by enrichment of T cell pathways. In conclusion, loss of Twist1 in collagen-producing cells led to increased bleomycin-induced pulmonary fibrosis, which is mediated by increased expression of CXCL12. Twist1 expression is associated with dysregulation of T cells in IPF patients. Twist1 may shape the IPF phenotype and regulate inflammation in fibrotic lung injury.

Inhibition of Raf1 ameliorates bleomycin-induced pulmonary fibrosis through attenuation of TGFβ1 signaling

Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease associated with aberrant activation and differentiation of fibroblasts, leading to abnormal extracellular matrix production. Currently, it is still an untreatable disease (except for lung transplantation). Here, we demonstrate that the Raf1 inhibitor GW5074 ameliorates lung fibrosis in bleomycin-induced pulmonary fibrosis. Posttreatment with GW5074 reduced fibronectin (FN) expression, collagen deposition, and inflammatory cell infiltration in bleomycin-challenged mice, suggesting an antifibrotic property of GW5074. To determine the molecular mechanisms by which inhibition of Raf1 ameliorates lung fibrosis, we investigated the role of Raf1 in TGF-β1 signaling in human lung fibroblasts. GW5074 or downregulation of Raf1 by siRNAs significantly attenuated TGF-β1-induced smooth muscle actin, FN, and collagen I expression, whereas overexpression of Raf1 promoted the effects of TGF-β1 in lung fibroblasts. Furthermore, we found that Raf1-promoted TGF-β1 signaling was through the Raf1/ERK/Smad pathway and contributed to the cell proliferation and migration in human lung fibroblasts. This study provides preclinical and mechanistic evidence for development of Raf1 inhibitors as potential antifibrotic drugs for the treatment of IPF.

RXFP1 expression is regulated by miR-144-3p in Fibroblasts from Patients with Idiopathic Pulmonary Fibrosis

Relaxin has been considered as a potential therapy for patients with pulmonary fibrosis. We have previously shown, however, that a potential limitation of relaxin-based therapy for Idiopathic Pulmonary Fibrosis (IPF) is the loss of expression of the relaxin receptor Relaxin/Insulin Like Receptor 1 (RXFP1) expression in fibroblasts. The molecular mechanism for RXFP1 down-regulation in IPF patients remains unclear. To determine whether microRNAs play a role in RXFP1 gene expression, we employed a bioinformatics approach to identify microRNAs (miRs) that are predicted to target RXFP1. By in silico analysis, we identified a putative target site in the RXFP1 mRNA for the miR-144 family. We found that miR-144-3p was upregulated in IPF fibroblasts compared to donor lung fibroblast controls. Forced miR-144-3p mimic expression reduced RXFP1 mRNA and protein levels and increased expression of the myofibroblast marker alpha-smooth muscle actin (α-SMA) in donor lung fibroblasts. IPF lung fibroblasts transfected with a miR-144-3p inhibitor increased RXFP1 expression and reduced α-SMA expression. A lentiviral luciferase reporter vector carrying the WT 3’UTR of RXFP1 was repressed more in lung fibroblasts whereas vector carrying a mutated miR-144-3p binding site exhibited less sensitivity to endogenous miR-144-3p expression, suggesting that RXFP1 is a direct target of miR-144-3p. Thus, miR-144-3p is highly expressed in IPF fibroblasts and acts as a negative regulator of RXFP1 protein expression.

ID: 108: DEUBIQUITINATING ENZYME 11 STABILIZES TGFβ RECEPTOR II AND REGULATES TGFβ1 SIGNALING IN PULMONARY FIBROBLAST

Background Protein stability is regulated by ubiquitination and deubiquitination. The ubiquitin-deubiquitination system contributes to the regulation of tumor growth factor β1 (TGFβ1) signaling. TGFβ1 mediates its signaling and pro-fibrotic effects through binding to its receptors, TGFβ receptor I (TβRI) and TβRII. Here we reveal that deubiquitinating enzyme USP11 regulates TGFβ1 signaling through stabilization of TβRII. Methods and Results Bleomycin-induced pulmonary fibrosis is a wildly used murine model of pulmonary fibrosis. Analysis of murine lung tissue lysates from 3 weeks of bleomycin challenge revealed that USP11 levels were elevated in lung tissues from bleomycin-challenged mice. TGFβ1 plays a critical role in the pathogenesis of pulmonary fibrosis. TGFβ1 treatment of human lung fibroblast cells (HLF) induced tyrosine phosphorylation of USP11. To investigate the effect of USP11 in the TGFβ1 signaling, HLF cells were transfected with USP11 shRNA. USP11 shRNA reduced USP11 levels as well as TβRII expression in HLF. Overexpression of HA tagged USP11 (USP11-HA) enhanced TβRII lifespan. Co-immunostaining revealed that V5 tagged TβRII (TβRII-V5) and USP11-HA colocalized at plasma membrane and cytoplasm. TβRII ubiquitination was promoted by USP11 shRNA, while it was reduced by USP11-HA. Further, we investigated the role of USP11 in TGFβ1-mediated signaling, such as phosphorylation of SMAD2 and SMAD3. USP11-HA facilitated TGFβ1-induced phosphorylation of SMAD2 and SMAD3, which was attenuated in USP11 shRNA transfected HLF cells. Conclusion This study indicates that USP11 contributes to the pathogenesis of pulmonary fibrosis by regulating targeting TβRII for its deubiquitination and stabilization. This work was supported by the National Institutes of Health (R01HL091916 and R01HL112791 to Y.Z, R01GM115389 to J.Z.), American Heart Association 12SDG9050005 (J.Z.), American Lung Association Biomedical Research Grant RG350146 (J.Z.).