Receptor tyrosine kinases (RTKs) have an important role in arthritis severity and in models of rheumatoid arthritis (RA), but their regulation is not fully understood. The dual specificity phosphatase 6 (DUSP6) has been implicated in the regulation of RTK signaling, but never in the context of arthritis and autoimmunity. We used the KRN serum-induced arthritis (KSIA) model of RA and showed that DUSP6-/- mice were protected and had a 50% lower maximum arthritis score (p = 0.006) and reduced joint damage than C57BL/6 DUSP6+/+ controls. Serum levels of interleukin (IL) 10 were significantly increased (>2-fold), and IL6 decreased in DUSP6-/- mice. DUSP6-/- mice had increased numbers of IL10+ cells including Tr1 regulatory cells (p < 0.01). Introduction of the IL10-/- into DUSP6-/- (double knockout [KO]) reversed the DUSP6-/- protection. In conclusion, this study reports a pro-arthritic role for DUSP6. This discovery has the potential to generate a previously unknown target for therapies for RA and inflammatory diseases.
© 2024 The Author(s).

Despite numerous clinically available vaccines and therapeutics, aged patients remain at increased risk for COVID-19 morbidity. Furthermore, various patient populations, including the aged can have suboptimal responses to SARS-CoV-2 vaccine antigens. Here, we characterized vaccine-induced responses to SARS-CoV-2 synthetic DNA vaccine antigens in aged mice. Aged mice exhibited altered cellular responses, including decreased IFNγ secretion and increased TNFα and IL-4 secretion suggestive of TH2-skewed responses. Aged mice exhibited decreased total binding and neutralizing antibodies in their serum but significantly increased TH2-type antigen-specific IgG1 antibody compared to their young counterparts. Strategies to enhance vaccine-induced immune responses are important, especially in aged patient populations. We observed that co-immunization with plasmid-encoded adenosine deaminase (pADA)enhanced immune responses in young animals. Ageing is associated with decreases in ADA function and expression. Here, we report that co-immunization with pADA enhanced IFNγ secretion while decreasing TNFα and IL-4 secretion. pADA expanded the breadth and affinity SARS-CoV-2 spike-specific antibodies while supporting TH1-type humoral responses in aged mice. scRNAseq analysis of aged lymph nodes revealed that pADA co-immunization supported a TH1 gene profile and decreased FoxP3 gene expression. Upon challenge, pADA co-immunization decreased viral loads in aged mice. These data support the use of mice as a model for age-associated decreased vaccine immunogenicity and infection-mediated morbidity and mortality in the context of SARS-CoV-2 vaccines and provide support for the use of adenosine deaminase as a molecular adjuvant in immune-challenged populations.
Copyright © 2023 Gary, Tursi, Warner, Cuismano, Connors, Parzych, Griffin, Bell, Ali, Frase, Hojecki, Canziani, Chaiken, Kannan, Moffat, Embury-Hyatt, Wooton, Kossenkov, Patel, Kobasa, Kutzler, Haddad and Weiner.

Blocking pyrimidine de novo synthesis by inhibiting dihydroorotate dehydrogenase is used to treat autoimmunity and prevent expansion of rapidly dividing cell populations including activated T cells. Here we show memory T cell precursors are resistant to pyrimidine starvation. Although the treatment effectively blocked effector T cells, the number, function and transcriptional profile of memory T cells and their precursors were unaffected. This effect occurred in a narrow time window in the early T cell expansion phase when developing effector, but not memory precursor, T cells are vulnerable to pyrimidine starvation. This vulnerability stems from a higher proliferative rate of early effector T cells as well as lower pyrimidine synthesis capacity when compared with memory precursors. This differential sensitivity is a drug-targetable checkpoint that efficiently diminishes effector T cells without affecting the memory compartment. This cell fate checkpoint might therefore lead to new methods to safely manipulate effector T cell responses.
© 2023. The Author(s), under exclusive licence to Springer Nature America, Inc.

The intestinal flora maintained by the immune system plays an important role in healthy colon. However, the role of ILC3s-TD IgA-colonic mucosal flora axis in ulcerative colitis (UC) and whether it could become an innovative pathway for the treatment of UC is unknown. Yujin Powder is a classic prescription for treatment of dampness-heat type intestine disease in traditional Chinese medicine and has therapeutic effects on UC. Hence, the present study aimed to investigate the regulatory mechanism of Yujin Powder alcoholic extracts (YJP-A) on UC via ILC3s-TD IgA-colonic mucosal flora axis. The UC mouse model was induced by drinking 3.5% dextran sodium sulfate (DSS), meanwhile, YJP-A was given orally for prevention. During the experiment, the clinical symptoms of mice were recorded. Then the intestinal injury and inflammatory response of mice about UC were detected after the experiment. In addition, the relevant indicators of ILC3s-TD IgA-colonic mucosal flora axis were detected. The results showed that YJP-A had good therapy effects on DSS-induced mice UC: improved the symptoms, increased body weight and the length of colon, decreased the disease activity index score, ameliorated the intestinal injury, and reduced the inflammation etc. Also, YJP-A significantly increased the ILC3s proportion and the expression level of MHC II; significantly decreased the proportion of Tfh cells and B cells and the expression levels of Bcl6, IL-4, Aicda in mesenteric lymph nodes of colon in UC mice and IgA in colon. In addition, by 16S rDNA sequencing, YJP-A could restore TD IgA targets colonic mucus flora in UC mice by decreasing the relative abundance of Mucispirillum, Lachnospiraceae and increasing the relative abundance of Allprevotella, Alistipes, and Ruminococcaceae etc. In conclusion, our results demonstrated that the ILC3s-TD IgA-colonic mucosal flora axis was disordered in UC mice. YJP-A could significantly promote the proliferation of ILC3s to inhibit Tfh responses and B cells class switching through MHC II, further to limit TD IgA responses toward colonic mucosal flora. Our findings suggested that this axis may be a novel and promising strategy to prevent UC.
Copyright © 2022 Wen, Zhang, Yang, Jiang, Zhang, Wang, Hua, Ji, Yuan, Wei and Yao.

Signaling via the OX40/OX40L axis plays a key role in CD4+ T cell development, and OX40L expression is primarily restricted to antigen-presenting cells (APCs). This study was designed to assess the role of APC-mediated OX40L expression in the context of the development of rheumatoid arthritis (RA)-associated CD4+ T cell subsets. For these analyses, clinical samples were harvested from patients with osteoarthritis and RA, with additional analyses performed using OX40-/- mice and mice harboring monocyte/macrophage-specific deletions of OX40L. Together, these analyses revealed tissue-specific roles for OX40/OX40L signaling in RA. Specifically, higher levels of synovial macrophage OX40L expression were associated with the enhanced development of T follicular helper cells in the joint microenvironment, thereby contributing to the pathogenesis of RA. This Tfh differentiation was found to be OX40/OX40L-dependent in this synovial setting. Overall, these results indicate that the expression of OX40L by synovia macrophages is necessary to support Tfh differentiation in the joint tissues, thus offering new insight regarding the etiological basis for RA progression.