Comparative Effects of Lacticaseibacillus rhamnosus and Lactobacillus delbrueckii on the Proliferative, Anti-apoptotic, and Tolerogenic Properties of Adipose-Derived Mesenchymal Stem Cells.

Mesenchymal stem cells (MSCs) are promising therapeutic candidates for multiple sclerosis (MS). Probiotics also exhibit anti-inflammatory effects, and tolerogenic stains may help modulate immune responses in autoimmune diseases. This study evaluated the effects of Lacticaseibacillus rhamnosus (formerly Lactobacillus rhamnosus) and Lactobacillus delbrucekii on the immunomodulatory properties and cytokine-expression profile of adipose-derived MSCs (AD-MSCs) isolated from patients with MS. AD-MSCs were isolated and characterized, then treated separately or in combination with different concentrations of L. rhamnosus and L. delbrucekii. Cell proliferation and apoptosis were assessed by MTT assay and flow cytometery, respectively. Following 24 h of co-culture of AD-MSCs with peripheral blood mononuclear cells (PBMCs) from healthy donors in the presence of probiotic candidate strains, the frequency of regulatory T cells (Tregs) and expression of IL1, IL6, IL17, FOXP3, TGFβ, and IL4 were evaluated by flow cytometery and real-time PCR, respectively. Both probiotic candidate strains, particularly at 107, significantly enhanced AD-MSC proliferation and reduced apoptosis, the mRNA expression of pro-inflammatory cytokines IL6 and IL17 were downregulated in all treatment groups except the low-dose L. rhamnosus group. In contrast, the mRNA expression of anti-inflammatory mediators TGFβ, IL4, and FOXP3 were upregulated following treatment with the probiotic candidate strains. In addition, Treg frequency increased significantly in all groups (P = 0.0001). These findings suggest that treatment with L. rhamnosus and L. delbrucekii is associated with gene-expression profiles consistent with enhanced immunomodulatory capacity of AD-MSCs, including Treg induction, increased anti-inflammatory responses, and suppression of pro-inflammatory pathways. Therefore, exposure to these probiotic candidate strains may promote proliferative and tolerogenic properties of AD-MSCs in co-culture conditions. However, because these conclusions are based on mRNA expression data without protein-level validation, they should be interpreted cautiously and regarded as indicative of transcriptional changes rather than confirmed cytokine or functional immune responses.