Dysregulation of TNF‐induced protein 3 and CCAAT/enhancer‐binding protein β in alveolar macrophages: Implications for systemic sclerosis‐associated interstitial lung disease

Abstract

AbstractObjectivesThis study investigates the role of TNF‐induced protein 3 (TNFAIP3) and CCAAT/enhancer‐binding protein β (C/EBPβ) in alveolar macrophages (AMs) of patients with systemic sclerosis‐associated interstitial lung disease (SSc‐ILD) and their influence on pulmonary fibrosis.MethodsTransfection of HEK293T cells and AMs with plasmids carrying TNFAIP3 and C/EBPβ was performed, followed by co‐culturing AMs with pulmonary fibroblasts. Immunoblotting analysis was then utilized to assess the expression of TNFAIP3, C/EBPβ, and collagen type 1 (Col1). Quantitative PCR analysis was conducted to quantify the mRNA levels of C/EBPβ, IL‐10, and TGF‐β1. STRING database analysis, and immunoprecipitation assays were employed to investigate the interactions between TNFAIP3 and C/EBPβ.ResultsTNFAIP3 expression was significantly reduced in SSc‐ILD AMs, correlating with increased Col1 production in fibroblasts. Overexpression of TNFAIP3 inhibited this pro‐fibrotic activity. Conversely, C/EBPβ expression was elevated in SSc‐ILD AMs, and its reduction through TNFAIP3 restoration decreased pro‐fibrotic cytokines IL‐10 and TGFβ1 levels. Protein–protein interaction studies confirmed the regulatory relationship between TNFAIP3 and C/EBPβ.ConclusionsThis study highlights the important role of TNFAIP3 in regulating pulmonary fibrosis in SSc‐ILD by modulating C/EBPβ expression in AMs. These findings suggest that targeting TNFAIP3 could be a potential therapeutic strategy for managing SSc‐ILD patients.