Interleukin-32-expressing CD4 T cells are a potentially pathogenic subset in systemic sclerosis with interstitial lung disease.

Background: Systemic sclerosis (SSc) is an autoimmune disease characterized by vasculopathy, fibrosis, and inflammation. CD4 T cells produce cytokines that are crucial in the pathogenesis of SSc. However, the role of CD4 T cells in SSc-associated interstitial lung disease (SSc-ILD) remain unclear. Therefore, we aimed to characterize abnormal cytokine production by CD4 T cell subsets in SSc-ILD.

Methods: We re-analysed publicly available single-cell (sc) RNA-seq datasets (13 SSc and 11 healthy control (HC) lung biopsy samples), bulk RNA-seq (HC peripheral blood (PB)), and microarray datasets from the PB of patients with 18 SSc-ILD and 16 HC) using R, RaNA-seq pipeline, and GEO2R web tool. CD4 T cells were purified from the PB of HC and analysed.

Results: scRNA-seq data revealed higher IL32 gene expression in CD4 T cells from SSc lung biopsies compared to those from HC. Microarray data showed significantly higher IL32 gene expression in CD4 T cells from the PB of patients with SSc-ILD than in HC. IL32 gene expression was elevated in Th1, Th2, and Th17 cells compared with naïve CD4 T cells, and in central and effector memory CD4 T cells compared with Tn. Furthermore, scRNA-seq data showed that IL32 gene expression increased in Tn cells without stimulation and in memory CD4 T cells stimulated with anti-CD3/28 antibodies.

Conclusion: Our results suggest that IL32-expressing CD4 T cells are a key subset involved in SSc pathologies. IL-32 has both proinflammatory and anti-inflammatory effects on various cells; however, further studies are needed to explore its therapeutic potential.