Altered Immune Responses in Mice After Receiving Nicotine-pulsed Mesenchymal Stem Cell-conditioned Medium

Abstract

Introduction: Previous investigations have documented that nicotine-pulsed mesenchymalstem cells (MSCs) can induce an anti-inflammatory phenotype in some immune cells in vitro.This study aimed to assess the effects of nicotine-pulsed MSCS in the function of immunecells, macrophages, and lymphocytes of mice receiving these cels.Materials and Methods: Bone marrow-derived MSCs (1.5×106) were seeded in a T75flaskand incubated with 0, .1, .5, or 1 μM nicotine until the cells reached 90% confluency.Afterwards, immunophenotyping change, vitality, concentration of TGF-β, IL-10, and IDOlevels of the MSC-conditioned medium were examined. Correspondent to in vitro results, theC57BL/6 mice intravenously received 400 μL of the conditioned medium of MSCs (CM),conditioned medium of nicotine (.5 μM)-pulsed MSCs (CMN), or medium. After 12 h, thelymphocytes, neutrophils, and peritoneal macrophages of the mice were isolated and theirfunction was evaluated ex vivo.Results: The least effective dose concentration of nicotine that led to an anti-inflammatoryenvironment by the MSC-conditioned medium was 0.5 μM. Nicotine at this concentrationprompted a higher level of TGF-β, IDO concentration in the conditioned medium. However,this concentration did not affect the MScs’ markers expressions or MScs’ vitality. T lymphocytesisolated from the mice receiving CMN showed a significant decrease in proliferation rate. Theratio of the IFN-γ gene expression to IL-4 gene expression in splenocytes was significantlyreduced in the mice receiving CMN compared to the mice receiving CM. The neutral reduptake, respiratory burst, and nitric oxide production of the peritoneal macrophage onlydecreased in the mice treated with CMN. These factors also decreased in neutrophils isolatedfrom mice receiving CM or CMN. However, these decreases were more prominent in the micetreated with CMN.Conclusion: Treatment of MSCs by nicotine may be a promising strategy to enhance theimmunomodulatory properties of these cells