The transcription factor interferon regulatory factor 5 (IRF5) functions as an important mediator of the inflammatory response downstream of MyD88-dependent TLRs. Whereas dysregulation of IRF5 activity has been implicated in the development of numerous autoimmune diseases including systemic lupus erythematosus, the factors that modulate TLR-induced IRF5 post-translational modifications are poorly understood. The focus of this study was to identify novel kinases in TLR-MyD88-IRF5 signaling. We performed a kinome-wide siRNA screen in human THP-1 monocytic cells and identified serine/threonine protein kinase 25 (STK25) as a positive regulator of pro-inflammatory cytokine production via phosphorylation of IRF5 at Thr265, leading to IRF5 transcriptional activation. We further found that STK25 undergoes autophosphorylation in response to multiple TLR triggers. Findings were validated in Stk25-deficient primary immune cells revealing a significant attenuation in R848-induced IRF5 nuclear translocation and pro-inflammatory cytokine production. Finally, we detected increased levels of STK25 autophosphorylation in immune cells from systemic lupus erythematosus donors compared with healthy controls. These findings implicate STK25 as a new regulator of TLR7/8 signaling through the modulation of IRF5 activation.
© 2025 Rice et al.

The mammalian non-homologous end joining (NHEJ) is required for class switch and V(D)J recombination as well as repairing DNA double-strand breaks (DSBs). Initiated by the binding of Ku70/Ku80 (Ku) dimer to DNA ends and the recruitment of the DNA-dependent protein kinase catalytic subunit, NHEJ plays a key role in DSB repair. While the overall function of Ku70 in NHEJ is well documented, the specific role of its highly conserved C-terminal SAP (SAF-A/B, Acinus, and PIAS) domain remains elusive. In this study, we developed a novel mouse model by deleting the SAP domain but preserving Ku70 nuclear localization and its dimerization ability with Ku80. We found that Ku70 SAP deletion (ΔSAP) had little effect on class switch and V(D)J recombination or animal development but sensitized the animals and cells to radiation and chemotherapy agents. Ku70-ΔSAP cells exhibited reduced Ku70 recruitment and dampened DNA ligase IV retention to DNA damage sites after radiation exposure and displayed a spreading pattern of DSB marker γH2AX after DNA damage. Our findings suggest that the SAP domain is required for cells to optimally cope with DNA damage, making it a potential target to modulate cell sensitivity to therapeutic DSB-inducing agents without interfering with the developmental function of Ku70.
© The Author(s) 2025. Published by Oxford University Press on behalf of Nucleic Acids Research.

Due to their high developmental diversity and different regulatory and functional roles, B cell subpopulations can promote or inhibit tumor growth. An orthotopic murine HNSCC model was applied to investigate the B cell composition and function in HNSCCs. Using flow cytometry approaches, cells from the spleen, lymph nodes and tumors were analyzed. Additionally, immunoglobulin (Ig) levels post-tumor induction were tracked via enzyme-linked immunosorbent assays (ELISA). Following tumor induction, GCs, as well as increasing numbers of GL7+CD95+ GC B cells in the spleen and tumor tissues, were detected. In parallel, we observed CD39+CD73+ B cells in tumors and spleens of tumor-bearing mice. Notably, CD39+CD73+ expression was primarily detected on MZ B cells and to a lesser extent on follicular (FO) and non-follicular, newly formed (NF) B cells, supposing an immunosuppressive function of MZ B cells in the TME. Parallel to increased MZ B cell numbers in secondary lymphoid organs (SLOs) as well as in the tumor tissue, IgM antibody (Ab) levels rose continuously. In contrast, IgG1, IgG2, and IgG3 levels increased at later time points. Understanding the complex interactions between B cell subsets and the TME could lead to new strategies for enhancing the treatment and prognosis of HNSCC patients.

Our research team previously reported the immunomodulatory effects of kombucha fermentation liquid. This study investigated the protective effects of turmeric kombucha (TK) against lipopolysaccharide (LPS)-induced sepsis and its impact on the intestinal microbiota of mice. A turmeric culture medium without kombucha served as the control (TW). Non-targeted metabolomics analysis was employed to analyze the compositional differences between TK and TW. Qualitative analysis identified 590 unique metabolites that distinguished TK from TW. TK improved survival from 40 to 90%, enhanced thermoregulation, and reduced pro-inflammatory factor expression and inflammatory cell infiltration in the lung tissue, suppressing the NF-κB signaling pathway. TK also altered the microbiome, promoting Allobaculum growth. Our findings shed light on the protective effects and underlying mechanisms of TK in mitigating LPS-induced sepsis, highlighting TK as a promising anti-inflammatory agent and revealing new functions of kombucha prepared through traditional fermentation methods.
Copyright © 2024 Su, Tan, Wu, Zhou, Xu, Zhao, Lin, Deng, Xie, Lin, Ye and Yang.

Dendritic cell (DC) dysfunction is known to exacerbate intestinal pathologies, but the mechanisms compromising DC-mediated immune regulation in this context remain unclear. Here, we show that intestinal dendritic cells from a mouse model of experimental colitis exhibit significant levels of noncanonical NF-κB signaling, which activates the RelB:p52 heterodimer. Genetic inactivation of this pathway in DCs alleviates intestinal pathologies in mice suffering from colitis. Deficiency of RelB:p52 diminishes transcription of Axin1, a critical component of the β-catenin destruction complex, reinforcing β-catenin-dependent expression of Raldh2, which imparts tolerogenic DC attributes by promoting retinoic acid synthesis. DC-specific impairment of noncanonical NF-κB signaling leads to increased colonic numbers of Tregs and IgA+ B cells, which promote luminal IgA production and foster eubiosis. Experimentally introduced β-catenin haploinsufficiency in DCs with deficient noncanonical NF-κB signaling moderates Raldh2 activity, reinstating colitogenic sensitivity in mice. Finally, inflammatory bowel-disease patients also display a deleterious noncanonical NF-κB signaling signature in intestinal DCs. In sum, we establish how noncanonical NF-κB signaling in dendritic cells can subvert retinoic acid synthesis to fuel intestinal inflammation.
© 2024. The Author(s).