Dan Li

Regulatory T-cell (Treg) stability is maintained by dynamic remodeling of the FOXP3 transcriptional complex, and disruption of this complex leads to Treg dysfunction and immune dysregulation. However, how specific FOXP3 mutations alter the dynamic remodeling of the FOXP3 complex and thereby contribute to pathogenic Treg reprogramming in IPEX syndrome remains unclear. Here, we demonstrate that predominant Th1 inflammation manifests in both FOXP3^V408M IPEX patients and FOXP3^V408M knock-in mice and reveal that the mutation intrinsically impairs Treg-mediated control of Th1 inflammation, revealing a distinct pathogenesis of this mutation in IPEX syndrome. Mechanistically, the V408M mutation disrupts the FOXP3–T-bet interaction, impairing the FOXP3-mediated restraint of T-bet-driven IFN-γ production and thereby contributing to increased Th1 inflammation. Using an AI-driven virtual screening approach, we identified a first-in-class small molecule, FM029, that directly binds to FOXP3 and reinforces its interaction with T-bet. FM029 strongly suppressed Treg-derived IFN-γ production and alleviated IFN-γ-driven tissue inflammation in both FOXP3^V408M mice and an acute colitis model. Collectively, these findings establish the FOXP3–T-bet interaction as a central checkpoint that governs Treg stability and IFN-γ-driven Th1 pathology, providing a proof-of-concept that pharmacologic stabilization of the FOXP3–T-bet interaction can mitigate IFN-γ-driven immune disorders.

The differentiation of Th17 and iTreg is tightly associated with fatty acid metabolism. TGFβ1-induced iTreg differentiation from Th0 relies on fatty acid oxidation (FAO), whereas IL-6 with TGFβ1 shifts metabolism to Th17-preferred fatty acid synthesis (FAS). However, how IL-6 reprograms fatty acid metabolism remains unclear. Here, we unveiled that TGFβ1-activated JNK is recruited to the Klhl25 promoter by NF-YA. JNK then phosphorylates histone H3 at Ser10 to activate Klhl25 transcription, leading to the ubiquitination-dependent degradation of ATP-citrate lyase (ACLY) and the switch from FAS to FAO, which supports iTreg generation. Whereas, upon IL-6 signaling, NF-YA is phosphorylated by ERK, losing its DNA binding ability, which shuts off TGFβ1-JNK-mediated Klhl25 transcription and ACLY ubiquitination, thereby increasing FAS and supporting Th17 differentiation. This study demonstrated that KLHL25-ACLY module functions as a switch in response to TGFβ1 and IL-6 signals, playing a decisive role in the fate determination of iTreg/Th17 differentiation.

Hepatic ischemia/reperfusion injury (IRI) commonly complicates liver transplantation (LT). However, the precise mechanisms underlying hepatic IRI remain incompletely understood. We acquired single‐cell RNA sequencing (scRNA‐seq) and transcriptome RNA sequencing data of LT patients from the GEO database. Employing scRNA‐seq, we delved into the interplay between non‐immune and immune cells in hepatic IRI, pinpointing genes exhibiting altered expression patterns. Integrating insights gleaned from scRNA‐seq and transcriptome RNA sequencing datasets, we deepened our comprehension of cellular interactions and underlying mechanisms in hepatic IRI. Additionally, we conducted preliminary validation of identified gene expression alterations using immunofluorescence techniques. Using scRNA‐seq, we detected significant changes in the populations of liver sinusoidal endothelial cells (LSECs) and monocytes after hepatic ischemia–reperfusion injury (IRI). By integrating scRNA‐seq with bulk transcriptome RNA sequencing data, we identified key genes with dysregulated expression in LSECs (ICAM1, SOCS3, NFKBIZ, JUND, TNFRSF12A and HSPA6) and monocytes (SOCS3, JUND, FPR2 and NR4A2). Our analysis of cell communication indicated that the ANXA1‐FPR2 axis might be a pivotal signature in mediating interactions between LSECs and monocytes. We then established a mouse model for IRI, and further analyses using flow cytometry and immunofluorescence showed a significant increase in monocyte proportion post‐IR (p < 0.01). Consistently, Western Blot also revealed significant upregulation of ANXA1 and FPR2 (p < 0.01). Our study elucidated the cellular interactions and signalling pathways following IRI. The interplay between LSECs and monocytes likely triggers a cascade of events, promoting monocyte infiltration and amplifying inflammatory responses, thus worsening the deleterious effects of IRI.

Background: Adjuvant-induced arthritis (AIA) serves as a classic model for rheumatoid arthritis (RA), typified by inflammatory cell infiltration and joint damage. This study explores the therapeutic efficacy of HU-308, a CB2 receptor-specific agonist, on inflammation and immune balance in AIA.Methods: AIA was induced in mice by CFA injection. AIA mice were treated with HU-308 or vehicle, and effects on paw swelling, spleen index, histopathology, and immune cell profiles were evaluated. Flow cytometry, in vitro differentiation assays, and Western blot analysis were performed to examine Th17 and Treg cells, as well as signaling pathways involved in their differentiation.Results: HU-308 reduced paw swelling, lowered spleen index, and preserved joint integrity in AIA mice, mitigating inflammatory cell infiltration and bone erosion. Flow cytometry revealed that HU-308 restored the Th17/Treg imbalance in AIA, decreasing Th17 cell frequency and enhancing Treg cell infiltration. In vitro assays confirmed HU-308s role in promoting Treg differentiation and inhibiting Th17 polarization. Western blot analysis indicated that HU-308 modulated immune balance through the JAK/STAT5 and TGF-β/SMAD signaling pathways, increasing Foxp3 and TGF-β expression.Conclusion: HU-308 demonstrates significant anti-inflammatory effects in AIA by restoring Th17/Treg balance and reducing joint damage. The findings indicate that HU-308 holds potential as an immunomodulatory agent for RA, providing valuable insights into CB2-mediated therapeutic strategies for autoimmune diseases.

Ku70, a DNA repair protein, binds to the damaged DNA ends and orchestrates the recruitment of other proteins to facilitate repair of DNA double-strand breaks. Besides its essential role in DNA repair, several studies have highlighted nonclassical functions of Ku70 in cellular processes. However, its function in immune homeostasis and antitumor immunity remains unknown. Here, we discovered a marked association between elevated Ku70 expression and unfavorable prognosis in lung adenocarcinoma, focusing specifically on increased Ku70 levels in tumor-infiltrated Tregs. Using a lung-colonizing tumor model in mice with Treg-specific Ku70 deficiency, we demonstrated that deletion of Ku70 in Tregs led to a stronger antitumor response and slower tumor growth due to impaired immune-suppressive capacity of Tregs. Furthermore, we confirmed that Ku70 played a critical role in sustaining the suppressive function of human Tregs. We found that Ku70 bound to forkhead box protein P3 (FOXP3) and occupied FOXP3-bound genomic sites to support its transcriptional activities. These findings not only unveil a nonhomologous end joining–independent (NHEJ-independent) role of Ku70 crucial for Treg-suppressive function, but also underscore the potential of targeting Ku70 as an effective strategy in cancer therapy, aiming to both restrain cancer cells and enhance pulmonary antitumor immunity.