Upregulation of thrombospondin-1(TSP-1) and its binding partners, CD36 and CD47, in sporadic inclusion body myositis

The TSP1/CD36/CD47-complex is involved in T cell expansion and inflammatory responses to β-amyloid, both relevant to IBM. We report on the mRNA and protein expression of TSP1/ CD36 /CD47-complex in IBM muscles and in human myoblasts after cytokine stimulation. The TSP1/CD36 /CD47 was upregulated in IBM. TSP1 immunolocalized to the connective tissue contiguous to inflammation and CD36/CD47 on the myofibers and CD8+ cells. Further, TNF-α upregulated the production of TSP1 and CD47 by myoblasts. The TSP-complex is another inflammatory mediator associated with chronic inflammation in IBM that may perpetuate the immune responses to local antigens in response to TNF-α.