Mesenchymal stem cell therapy in proteoglycan induced arthritis

OBJECTIVES

To explore the immunosuppressive effect and mechanism of action of intraperitoneal (ip) and intra-articular (ia) mesenchymal stem cell (MSC) injection in proteoglycan induced arthritis (PGIA).

METHODS

MSC were administered ip or ia after establishment of arthritis. We used serial bioluminescence imaging (BLI) to trace luciferase-transfected MSC. Mice were sacrificed at different time points to examine immunomodulatory changes in blood and secondary lymphoid organs.

RESULTS

Both ip and local ia MSC injection resulted in a beneficial clinical and histological effect on established PGIA. BLI showed that MSC ip and ia in arthritic mice are largely retained for several weeks in the peritoneal cavity or injected joint respectively, without signs of migration. Following MSC treatment pathogenic PG-specific IgG2a antibodies in serum decreased. The Th2 cytokine IL-4 was only upregulated in PG-stimulated lymphocytes from spleens in ip treated mice and in lymphocytes from draining lymph nodes in ia treated mice. An increase in production of IL-10 was seen with equal distribution. Although IFN-γ was also elevated, the IFN-γ/IL-4 ratio in MSC treated mice was opposite to the ratio in (untreated) active PGIA.

CONCLUSIONS

MSC treatment, both ip and ia, suppresses PGIA, a non-collagen induced arthritis model. MSC are largely retained for weeks in the injection region. MSC treatment induced at the region of injection a deviation of PG-specific immune responses, suggesting a more regulatory phenotype with production of IL-4 and IL-10, but also of IFN-γ, and a systemic decrease of pathogenic PG-specific IgG2a antibodies. These findings underpin the potential of MSC treatment in resistant arthritis.

Lactic acid bacteria differ in their ability to induce functional regulatory T cells in humans

BACKGROUND

Trials with probiotic lactic acid bacteria have yielded different results, which may be due to the strains used. Lactobacilli and bifidobacteria are known to be potent modulators of the immune system. The capacity of these bacteria used as probiotics to influence both T helper type 1 (Th1)- and Th2-mediated diseases has been shown before. However, the ability of strains to induce forkhead box P3 (FOXP3(+)) expressing regulatory T cells has not yet been investigated.

OBJECTIVE

Test the inherent differences between strains in their capacity to induce functional regulatory T cells in human peripheral blood mononuclear cells (PBMC).

METHODS

Human PBMC were co-cultured in vitro with either Bifidobacterium lactis W51, Lactobacillus acidophilus W55 or Lactobacillus plantarum W62 or an Escherichia coli control strain. The percentage of FOXP3(+) cells, the origin of the induced cells and the functionality of these cells were assessed. Results Probiotic strains differ in their capacity to induce regulatory T cells. FOXP3(+) cells were induced from CD25(-) cells and were able to suppress effector T cells. Naturally occurring regulatory T cells were not affected by co-culture with lactobacilli. IL-10 concentrations found in the supernatant showed a trend towards the same differences between strains. Blockade of IL-10 did not influence the up-regulation of FOXP3. No differences between lactic acid bacteria were found in IL-17, IFN-gamma or IL-13.

CONCLUSIONS

Some probiotic strains are potent inducers of regulatory cells, while others are not. The clear differences between strains imply that an in vitro characterization of probiotic strains before application is recommended.