Anti-CD206 CAR T Cell Treatment Restores Fibrosis-Induced Loss of Dermal White Adipose Tissue

Fibrosis drives pathology in the chronic autoimmune disease systemic sclerosis (SSc), which has the highest case fatality rate of any systemic autoimmune disease with no validated biomarkers or curative treatments. Our prior work has shown that CD206 ⁺ macrophages and dermal fibroblasts engage in cooperative mechanisms of inflammatory and fibrotic activation in SSc. Here, we designed a targeted immunotherapeutic approach to eliminate CD206 ⁺ macrophages using chimeric antigen receptor (CAR) T cells. We demonstrate that systemic delivery of a single dose of anti-CD206 CAR T cells restores dermal white adipose tissue (DWAT) in vivo . Notably, loss of subcutaneous fat is a well-recognized but poorly understood aspect of SSc pathogenesis that precedes the development of fibrosis and is driven by changes in lineage commitment of adipose-derived stem cells (ADSCs). Using snRNA-seq and a newly-developed in vitro co-culture model, we report that CD206 ^high macrophages mediate ADSC shift from adipocytic to fibrotic activation in part through an IL-6-dependent mechanism. This report implicates a novel function for macrophages in the regulation of early SSc pathogenesis and is the first to establish the therapeutic efficacy of using CAR T cell immunotherapy to target macrophages in the treatment of SSc skin disease.