The Impacts of <scp><i>Lactobacillus delbrueckii</i></scp> and <scp><i>Lactobacillus rhamnosus</i></scp> to Promote In Vitro Anti‐Inflammatory Profile of <scp>RA</scp>‐Macrophages

Rheumatoid arthritis (RA) is a prevalent and debilitating autoimmune disease. Numerous studies have demonstrated promising results regarding the use of probiotics as a therapeutic approach to alleviate RA symptoms. This study isolated monocytes from the PBMCs of RA patients and healthy donors. These monocytes were then differentiated into macrophages and divided into five groups: untreated, LPS-treated, <i>L. delbrueckii</i> (Del)-treated, <i>L. rhamnosus</i> (Ram)-treated, and a mixed treatment group. Three macrophage subpopulations-M0, M1, and M2-were identified in all treatment groups, with variations observed in the population percentages of each subpopulation and the expression levels of CD14, CD80, and HLA-DR. Flow cytometry results indicated that, compared to the untreated and LPS-treated groups, treatment with probiotic bacteria (Del, Ram, and Mix) stimulated the polarization of macrophages toward the M2 phenotype while suppressing the percentage of the M1 population. Additionally, the expression of CD14, a Pathogen-Associated Molecular Pattern (PAMP) and phagocytosis-inducing receptor, was significantly reduced in the probiotic-treated groups. Probiotic treatment also profoundly influenced antigen presentation by suppressing CD80, a ligand for the CD28 co-stimulatory marker on T cells, and HLA-DR, which presents antigens to the T cell receptors of Th4 cells. Interestingly, quantitative real-time PCR results indicated that probiotic treatment of macrophages significantly increased the expression of IL-10 and TGF-β, both anti-inflammatory cytokines, while significantly decreasing the expression of inflammatory cytokines, including IL-12, IL-1β, and TNF-α, in both healthy controls and RA patients. It seems that these probiotics may have a regulatory effect on macrophages, affecting their polarization, antigen presentation patterns, phagocytosis, and cytokine secretion profiles. This suggests that these probiotics may have therapeutic and prophylactic effects on RA.