Association of Interferon‐ and Transforming Growth Factor β–Regulated Genes and Macrophage Activation With Systemic Sclerosis–Related Progressive Lung Fibrosis

Abstract

Objective Systemic sclerosis (SSc)–related interstitial lung disease (ILD) is one of the leading causes of mortality. We undertook this study to analyze the gene expression of lung tissue in a prospective cohort of patients with SSc-related ILD and to compare it with that in control lungs and with 2 prospective clinical parameters in order to understand the molecular pathways implicated in progressive lung disease. Methods Lung tissue was obtained by open lung biopsy in 28 consecutive patients with SSc-related ILD and in 4 controls. High-resolution computed tomography (HRCT) and pulmonary function testing (PFT) were performed at baseline and 2–3 years after treatment based on lung histologic classification. Microarray analysis was performed, and the results were correlated with changes in the HRCT score (FibMax) and PFT values. Quantitative polymerase chain reaction (qPCR) and immunohistochemistry were used to confirm differential levels of messenger RNA and protein. Results Lung microarray data distinguished patients with SSc-related ILD from healthy controls. In the lungs of patients with SSc-related ILD who had nonspecific interstitial pneumonia (NSIP), expressed genes included macrophage markers, chemokines, collagen, and transforming growth factor β (TGFβ)– and interferon (IFN)–regulated genes. Expression of these genes correlated with progressive lung fibrosis defined by the change in FibMax. Immunohistochemistry confirmed increased markers of collagen (COL1A1), IFN (OAS1 and IFI44), and macrophages (CCL18 and CD163), and the positive correlation with the change in FibMax was confirmed by qPCR in a larger group of SSc patients with NSIP. Several genes correlated with both the change in FibMax (r > 0.4) and the change in % predicted forced vital capacity (r < −0.1), including IFN and macrophage markers, chemokines, and heat-shock proteins. Conclusion These results highlight major pathogenic pathways relevant to progressive pulmonary fibrosis in SSc-related ILD: macrophage emigration and activation, and up-regulated expression of TGFβ- and IFN-regulated genes.

Toll-Like Receptor-4 Signaling Drives Persistent Fibroblast Activation and Prevents Fibrosis Resolution in Scleroderma

“…To explore this hypothesis, we generated an experimentallyderived ''fibroblast TLR4 (LPS)-regulated gene signature'' using normal skin fibroblasts transfected with TLR4. 23,27 Comparison of this fibroblast TLR4 gene signature with those generated from human monocytes indicated only a partial overlap of differentially expressed genes in the two cell types (hypergeometric test; p = 0.02) ( Table 1). The fibroblast TLR4 gene signature showed significant enrichment with pathways related to wound healing, matrix remodeling, and TGF-b signaling, revealing important cell type-specific differences between TLR responses in bone marrow-derived inflammatory versus stromal cells (Table 1).…”

“…The fibroblast TLR4 gene signature showed significant enrichment with pathways related to wound healing, matrix remodeling, and TGF-b signaling, revealing important cell type-specific differences between TLR responses in bone marrow-derived inflammatory versus stromal cells (Table 1). Most interestingly, we found that SSc skin biopsies displaying a strong fibroblast TLR4 gene 27 We carried out a comparative analysis of SSc skin and lung transcriptomes to identify pathways shared between these two target organs. Pathways involved in positive and negative regulation of TLR signaling were most highly shared (Bhattacharyya S and Varga J; unpublished).…”

Interstitial lung disease in systemic sclerosis: where do we stand?

“…Lower levels of thymosin β-4 in the bronchoalveolar lavage of SSc-ILD patients have been correlated with disease progression [14]. In recent years, some genetic studies have shown increased expression of the TGF-β response including fibrosis-associated genes and myofibroblast markers [15,16]. An analysis of gene expression in skin biopsies identified some transcripts that correlate with the severity of SSc-ILD.…”

Anti-Fibrotic Effects of Astragaloside IV in Systemic Sclerosis

“…Among R-Smads, Smads 2 and 3 signal for TGF-β and activin, while Smads 1, 5 and 8 transduce signals from BMP ligands [5]. Studies show that elevated expression of TGF-β and its aberrant regulated genes as well as heightened activity in its signaling pathway was present in SSc-related progressive lung fibrosis [6] and dermal fibrosis [7]. Lakos et al found that compared to fibroblasts derived from wild mice, Smad3-null fibroblasts showed reduced in vitro proliferative and profibrotic responses elicited by TGF-β [8], suggesting that drugs interfering with TGF-β-Smads may be promising in SSc treatment.…”