TLR-2 and TLR-4 agonists favor expansion of CD4+ T cell subsets implicated in the severity of neuromyelitis optica spectrum disorders.

BACKGROUND: High frequency of circulating Th17 cell subsets expressing TLR2, TLR4 and TLR9 was observed in Neuromyelitis optica spectrum disorder (NMOSD) patients, a severe humoral autoimmune disease of the central nervous system. Our objective was to evaluate the direct effects of different TLR ligands on CD4+ T-cells form those patients. METHODS: CD4+ T-cell cultures from NMOSD and healthy individuals were stimulated with different TLR ligands and the cell proliferation and cytokine profile was analyzed by [3H] TdR up take and ELISA/ cytometry, respectively. The plasma levels of CD14 were determined by ELISA. RESULTS: Here, Pam3C (TLR2) and LPS (TLR4) induced significant cell proliferation and IL-6, IL-17 and IL-21 production by CD4+ T-cells from NMOSD. Additionally, while both TLR ligands were more potent in favoring the expansion of TFH-like cells, Pam3C reduced the frequency of IL-10-secreting FoxP3+and FoxP3- CD4+ T-cells. With regard to disease severity, the levels of IL-6, IL-17 and IL-21 produced by CD4+ T-cells, as well as the frequency of TFH-like cells, in response to TLR2 and TLR4 agonists were positively correlated with neurological disabilities and the occurrence of new acute relapses during follow up. Finally, circulating levels of CD14, an indirect marker of microbial translocation, were positively correlated with IL-6, IL-17 and IL-21 release by Pam3C- and LPS-activated CD4+ T-cells. CONCLUSIONS: In summary, our data suggest that microbial antigens may affect NMOSD outcomes by favoring an imbalance between Th17 and TFH-like cells and regulatory T cell subsets.

The expansion of circulating IL-6 and IL-17-secreting follicular helper T cells is associated with neurological disabilities in neuromyelitis optica spectrum disorders.

Due to their function in assisting B cells, TFH cells may be involved in the production of pathogenic IgG in neuromyelitis optica spectrum disorder (NMOSD). In the present study, the proportion of IL-6+ and IL-17+ TFH cell subsets was higher in NMOSD patients than healthy individuals. The frequency of both TFH cell subsets were directly associated with disease activity. By contrast, NMOSD patients with a higher proportion of IL-10+ TFH cell subsets showed a lower neurological disabilities score. In summary, all findings suggest that expansion of peripheral IL-6+ and IL-17+ TFH cells may be involved in the severity of NMOSD.

Expansion of IL-6+ Th17-like cells expressing TLRs correlates with microbial translocation and neurological disabilities in NMOSD patients.

Different microbial antigens, by signaling through toll-like receptors (TLR), may contribute to Th17-mediated autoimmune diseases, such as neuromyelitis optica spectrum disorder (NMOSD). The objective of this study was to determine the proportion of different Th17-like cell subsets that express TLR in NMOSD patients. For this study, the frequency of different Th17 cell subsets expressing TLR subsets in healthy individuals (n=20) and NMOSD patients (n=20) was evaluated by cytometry. The peripheral levels of soluble CD14 (sCD14) and cytokines were determined by ELISA. Our results demonstrated that the proportion of peripheral CD4+ T cells expressing TLR2, 4 and 9 was significantly higher in NMOSD samples than in healthy subjects. In NMOSD, these cells are CD28+PD-1-CD57- and produce elevated levels of IL-17. Among different TLRs+ Th17-like subsets, the proportion of those that co-express IL-17 and IL-6 was significantly higher in NMOSD patients, which was positively correlated with sCD14 levels and EDSS score. By contrast, the percentage of TLRs+Treg17 cells (IL-10+IL-17+) was negatively related to sCD14 and the severity of NMOSD. In conclusion, the expansion of peripheral IL-6-producing TLR+ Th17-like cells in NMOSD patients was associated with both bacterial translocation and disease severity.