The suppression effect of dendritic cells maturation by adipose-derived stem cells through TGF-β1 related pathway

Our previous studies demonstrated that adipose-derived stem cells (ASCs) could modulate regulatory T cells (Treg) and prolong hind-limb allotransplant survival in vitro and in vivo. Dendritic cells (DCs) play a pivotal role in innate and adaptive immunity. The aim of this study is to investigate the underlying mechanism of ASCs in modulating DC maturation.

ASCs were isolated from rodent adipose tissue, DCs were derived from the bone marrow, and CD4⁺ T cells were purified from splenocytes. DCs were co-cultured with ASCs to evaluate the suppressive effects of ASCs. CD4⁺ T-cells were co-cultured with DCs pre-treated with or without ASCs. The cell surface markers of DCs were analyzed by flow cytometry. T-cell proliferation was analyzed by the BrdU proliferation test. Tolerogenic cytokines and indoleamine 2,3-dioxygenase (IDO) expressions after different treatments were detected by quantitative real-time PCR, Western blotting, and ELISA analysis.

ASCs suppressed DC maturation as evidenced by low expressions of CD80, CD86, and MHC-II. Also, ASC-treated mature DCs showed higher levels of TGF-β1, IL-10, and IDO expressions, as compared to that in matured DCs (mDCs) alone. ASC-treated mDCs co-cultured with CD4⁺ T cells revealed a significant higher percentage of Treg than mDC without treatment. The IDO level in ASC-treated mDCs and Treg induction effects were blocked by the ASCs pre-treated with TGF-β1 siRNAs, but not IL-10 siRNAs.

ASC-modulated DC maturation correlated with TGF-β1 secretion, IDO expression, and Treg induction. ASCs could be used as a potential immunomodulatory strategy for clinical application in allotransplantation.