Rat bone mesenchymal stem cells exert antiproliferative effects on nicotine-exposed T cells via iNOS production

Abstract

Adoptive transfer of bone marrow-derived mesenchymal stem cells (BMScs) significantly alleviates smoking-induced chronic obstructive pulmonary disease (coPd) in rats. considering the critical roles of T cells during coPd development, the present study aimed to further identify the molecular mechanisms underlying the antiproliferative effect of BMScs on splenic T cells isolated from rats following chronic exposure to nicotine. Splenic T cells were co-cultured with rat BMScs at various ratios and subsequently, T-cell proliferation was measured using the cell counting Kit-8 assay. The effects of the inducible nitric oxide synthase (inoS) inhibitor n-nitro-l-arginine methylester (l-naMe) and short hairpin (sh)rna-lentivirus-mediated knockdown of inoS in BMScs on T-cell proliferation were evaluated. The expression levels of inoS and STaT5 phosphorylation in BMScs and T cells, respectively, were assessed by reverse transcription-quantitative Pcr and western blotting. a higher ratio of BMScs to T cells resulted in increased inhibition of T-cell proliferation; therefore, the ratio of 1:20 was selected for further in vitro experiments. at a dose of 5 µM, l-naMe displayed the strongest ability to reverse the antiproliferative effects of BMScs in the co-culture system. Both l-naMe treatment and shrna-mediated knockdown of inoS expression significantly decreased the suppressive effects of BMSCs, downregulated inoS expression at the mrna and protein levels in BMScs, and enhanced STaT5 phosphorylation in T cells. BMScs inhibited the proliferation of nicotine-exposed T cells, which was associated with inoS expression in BMScs and decreased STaT5 phosphorylation in T cells. The present study indicated the potential mechanisms underlying the beneficial effects of BMSC infusion in patients with chronic smoking-induced coPd and emphysema.