Interferon-gamma and tumor necrosis factor-alpha differentially affect cytokine expression and migration properties of mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are multipotent progenitor cells with the capacity to differentiate into different tissue cell types such as chondrocytes, osteocytes, and adipocytes. In addition, they can home to damaged, in-flamed, and malignant tissues and display immunomodulatory properties. Since tissue-derived factors might modulate these properties, we decided to explore the impact of prototypic tissue-derived inflammatory cytokines such as TNF-alpha and IFN-gamma on immunomodulatory MSCs functions. To this end, we used primary bone marrow and cord blood-derived MSCs as well as an immortalized MSC line (V54/2) as model systems. We demonstrate that under unstimulated conditions, V54/2 cells constitutively express low levels of indoleamine 2,3-dioxygenase (IDO), exert an immunosuppressive effect on activated T-lymphocyte proliferation, secrete a distinct set of cytokines, and express a wide range of chemokine receptors. Upon stimulation, the proinflammatory cytokines IFN-gamma and TNF-alpha did not inhibit suppression of T-cell proliferation, although IDO expression was up-regulated by IFN-gamma. In contrast, TNF-alpha but not IFN-gamma amplified the cytokine production of V54/2 and primary MSCs. Interestingly, IFN-gamma was superior to TNF-alpha in up-regulating expression of chemokine receptors and migration of the V54/2 cell line, while TNF-alpha was the predominant regulator of migration in primary MSCs. Altogether, our data show that properties of MSCs depend on local environmental factors. In particular, we have shown that IFN-gamma and TNF-alpha differentially regulate cytokine expression and migration of MSCs.