IL13 and CCL2 Drive Disease in an Inflammatory Subset of Scleroderma [cGVHD]. Mus musculus

Scleroderma is a lethal and currently irreversible autoimmune disease characterized by widespread tissue fibrosis and vasculopathy. Using cross-species comparative gene expression profiling we show that murine sclerodematous graft-versus-host disease (sclGVHD) approximates an “inflammatory” subset of human scleroderma and that both diseases demonstrate activation of the IL13 cytokine pathway. We report that both host myeloid cells expressing type I and II activated macrophage markers and graft T-cells produce IL13 and that host mice deficient in either IL13 or IL4Rα, an IL13 signal transducer, are protected from disease. This signaling pathway converges on a single gene, CCL2, which is coordinately upregulated in sclGVHD, in the human inflammatory scleroderma subset and in IL13 treated human dermal fibroblasts. Accordingly, treatment with antibodies to CCL2, and its murine homolog CCL12, prevent sclGVHD. Lastly, we provide evidence that IL13 pathway activation in early scleroderma patients correlates with modified Rodnan skin scores (mRSS). These data indicate that an inflammatory subset of scleroderma is driven by IL13 and may benefit from IL13 or CCL2 blockade. Overall design: Sample vs reference. Total RNA isolated from skin of the following mice: B10->balb/c; balb/c->balb/c; B10->balb/c IL13-/-; balb/c->balb/c IL13-/-; B10->balb/c IL4Ra -/-; balb/c->balb/c IL4Ra -/-