Tolerogenic dendritic cells alleviate collagen-induced arthritis by regulating T-cell differentiation and inhibiting NLRP3-mediated apoptosis.

OBJECTIVE: Tolerogenic dendritic cells (tolDCs) have emerged as a potential treatment for rheumatoid arthritis (RA). However, the detailed mechanism requires further investigation. In this study, we aimed to explore the effects of tolDCs on T-cell differentiation and NLRP3-mediated pyroptosis in a collagen-induced arthritis (CIA) rat model. METHODS: TolDCs were induced using NF-κB ODN decoy. The efficacy of tolDCs intervention in alleviating arthritis symptoms was evaluated in CIA rats. Flow cytometry was employed to analyze CD4+ T-cell subpopulations, while scanning electron microscopy was utilized to observe pyroptosis morphology. Immunohistochemistry was used to assess the expression of pyroptosis-associated proteins. RESULTS: TolDCs intervention significantly reduced joint inflammation and damage in CIA rats. Moreover, it successfully restored the balance of Th1/Th2 cells as well as the balance of Treg/Th17 cells. Furthermore, tolDCs intervention effectively suppressed NLRP3-mediated pyroptosis in the synovium, decreasing the release of IL-1ß and IL-18. CONCLUSION: Our findings underscore the efficacy of tolDCs in attenuating CIA progression through modulation of CD4+ T-cell subpopulations and inhibition of NLRP3-mediated pyroptosis.

[Tolerogenic dendritic cells form microchimerism in vivo in collagen-induced arthritis rats].

Objective To find evidence of microchimerism formation following infusion of tolerogenic dendritic cells (tDCs) into collagen-induced arthritis (CIA) rats. Methods Bone marrow-derived DC precursor cells were induced into tDCs by granulocyte-macrophage colony- stimulating factor (GM-CSF), interleukin 4 (IL-4) and nuclear factor-κB oligonucleotide decoy (NF-κB ODN decoy) and then infused into CIA rats after labeling with 1, 1' -octadecyl-3, 3, 3', 3' -tetramethyltricarbocyanine iodide (DiR). At 4 hours, 24 hours, 5 days, 10 days and 15 days after cell infusion, the fluorescence intensity and distribution were observed by in vivo imaging system of small animals. Rats were sacrificed on the 15th days to detect the fluorescence signals of the main organs. Results tDCs had high expression of OX62 and low expression of CD80 and CD86. The fluorescence signal was mainly concentrated in the chest, abdomen and left posterior joint, with the strongest fluorescence signal in the chest and abdomen at 24 hours and the strongest fluorescence signal in the left posterior joint at 5 days. Fluorescence could still be detected on the 15th days after cell infusion, and the left posterior joint of the diseased foot always maintained a strong fluorescence signal. In isolated organs, the fluorescence signals in the lung, liver, spleen and mesenteric lymph nodes were strong, and the kidney fluorescence signals was weak, and the heart had little fluorescence. Conclusion tDCs forms microchimerism in the diseased foot joints, lungs, liver, spleen, and mesenteric lymph nodes.

Tolerogenic dendritic cells alleviate collagen-induced arthritis by forming microchimerism and affecting the expression of immune checkpoint molecules.

Tolerogenic dendritic cells (tolDCs) have the potential to treat rheumatoid arthritis (RA) by inducing immune tolerance. However, the mechanism of intervention needs further study. Here, we investigated whether tolDCs formed microchimerism and their effect on the expression of immune checkpoint molecules after infusion of tolDCs into rats with collagen-induced arthritis (CIA). TolDCs derived from male SD rats were labeled with fluorescence and infused into female CIA rats. The fluorescence signals as well as the sex-determining region of Y-chromosome (SRY) gene revealed that tolDCs formed microchimerism in the mesenteric lymph nodes and ankle joints. We further explored the effect of tolDCs on the expression of immune checkpoint molecules in mesenteric lymph nodes and ankle joints. For stimulatory immune checkpoint molecules, the expressions of CD86 and CD40 decreased in mesenteric lymph nodes, and the expressions of CD40, CD40L, CD28, CD80, and CD86 also decreased in rat ankle joints. In contrast, the inhibitory immune checkpoint molecule PDL1 increased in mesenteric lymph nodes, and PD1, PDL1, and CTLA4 increased in ankle joints. In conclusion, our results suggested that intervention of tolDCs in CIA is associated with the formation of microchimerism and the effect on immune checkpoints.

[Tolerogenic dendritic cells alleviate joint inflammation and arthropathy via reducing Th1 and Th17 cell proportion in CIA rats].

Objective To investigate the effects of tolerogenic dendritic cells (tolDCs) induced by nuclear factor κB oligodeoxynucleotide decoy (NF-κB ODN decoy) on Th1 cells, Th2 cells, Th17 cells and regulatory T cells (Tregs) and the intervention effects on collagen-induced arthritis (CIA) rats. Methods SD female rats used to establish CIA rat models were divided into four groups, including a CIA model group, a bovine type II collagen-decoy-dendritic cell (Col2-decoy DC) treatment group, a blank control group, and a Col2-decoy DC control group. On the 20th days after the first immunization, the rats were injected with tolDCs via the tail vein, and the rats were sacrificed on the 7th weeks. The proportions of Th1 cells, Th2 cells, Th17 cells, and Tregs in the rat spleen were detected by flow cytometry. The ankle joint pathomorphological change was evaluated by HE staining, and the arthritis index (AI) was scored. Results Compared with the CIA model group, the Col2-decoy DC group had lower AI and milder ankle joint pathomorphological change. The percentages of Th1 cells and Th17 cells in the spleen CD4+ T cells decreased, while the percentages of Th2 cells and Tregs increased. Conclusion The treatment of tolDCs can alleviate the inflammation and arthropathy of CIA rats by reducing the proportion of Th1 and Th17 cells in CD4+ T cells.