Comparative effects of proliferative, anti-apoptotic and tolerogenic activities of Lactobacillus rhamnosus and Lactobacillus delbrueckii on adipose tissue derived mesenchymal stem cells

Abstract Mesenchymal stem cells (MSCs) are emerging as promising therapeutic candidates for multiple sclerosis (MS). In parallel, probiotics have demonstrated anti-inflammatory properties, and tolerogenic strains may modulate immune responses in autoimmune diseases. This study evaluated the effects of Lactobacillus rhamnosus and Lactobacillus delbrueckii on the immunomodulatory properties and cytokine expression of adipose-derived MSCs (AD-MSCs) from MS patients. AD-MSCs were isolated, characterized, and their proliferation assessed by MTT assay, while apoptosis was measured by flow cytometry. Cells were treated with L. rhamnosus and L. delbrueckii (10⁵ and 10⁷ Bac/ml), separately and in combination, and co-cultured with healthy PBMCs for 24 h. Flow cytometry was used to determine Treg frequency, and gene expression of IL-1, IL-6, IL-17, FoxP3, TGF-β, and IL-4 was analyzed by real-time PCR. Both probiotics, particularly at 10⁷ concentrations, significantly increased AD-MSC proliferation and reduced apoptosis. Pro-inflammatory cytokines IL-6 and IL-17 were downregulated in all groups except low-dose L. rhamnosus, while anti-inflammatory mediators TGF-β, IL-4, and FoxP3 were upregulated across probiotic treatments. Additionally, Treg numbers increased significantly in all groups (P = 0.0001). These findings suggest that probiotic treatment enhances the immunomodulatory functions of AD-MSCs by promoting Treg induction, upregulating anti-inflammatory responses, and suppressing pro-inflammatory pathways. Probiotics may serve as complementary agents in MSC-based therapies for MS.