Pulmonary sarcoidosis has long resisted disease-modifying therapy, with corticosteroids remaining the default despite their significant side-effect burden and inability to prevent fibrosis. A new mechanistic target—the chemokine receptor CXCR6—now emerges as a potential leverage point, with implications for the broader class of granulomatous lung diseases where treatment options remain scarce.
This preclinical investigation used a combination of single-cell RNA sequencing, flow cytometry, and antibody-blockade experiments in both human sarcoidosis tissue and a Propionibacterium acnes–induced mouse model to characterize CXCR6-expressing CD4+ T cells. These cells were found to accumulate in granulomatous lesions and consistently displayed a Th17 and Th17.1 phenotype—a pro-inflammatory subtype linked to tissue remodeling. Cell-cell communication analysis revealed active signaling between CXCR6+ CD4+ T cells and CXCL16-expressing macrophages, forming a feedforward inflammatory loop. Treating mice with an anti-CXCR6 monoclonal antibody reduced transcript levels of key inflammatory mediators including Il17a, Tnf, Nos2, and Ifng, while suppressing mTORC1 signaling downstream of T-cell activation. The treatment curtailed granuloma formation and attenuated pulmonary fibrosis progression.
The CXCL16–CXCR6 axis has attracted interest across autoimmune and fibrotic conditions—including rheumatoid arthritis, inflammatory bowel disease, and liver fibrosis—making this finding part of a converging body of evidence rather than an isolated observation. The mTORC1 link is particularly noteworthy: mTOR signaling governs Th17 cell differentiation and survival, and its inhibition by rapamycin analogs has shown partial benefit in some fibrotic settings. This study provides a rationale for upstream receptor-level intervention rather than downstream cytokine blockade alone. Critical limitations apply: the data are predominantly from a mouse model, and P. acnes–induced granulomas imperfectly recapitulate human sarcoidosis immunology. Human validation beyond tissue enrichment studies is still absent, and monoclonal antibody specificity and off-target effects remain untested in humans. Overall, this is a mechanistically rigorous incremental advance that strengthens the case for CXCR6 as a druggable target in granulomatous lung disease, warranting translational follow-up.