Pathological α-synuclein (α-syn) can spread from the gut to the central nervous system (CNS), with CD4 + T cells playing a key role in this process. Lymphocyte activation gene 3 (LAG3) is involved in intestinal inflammation, regulates CD4 + T cell proliferation and function, and can specifically bind to pathological α-syn during cell-to-cell transmission. However, it remains unclear whether LAG3 is involved in the spread of pathological α-syn from the gut to the brain.
We utilized LAG3 knockout mice, combined with injection of α-syn preformed fibril (PFF) into the longitudinal and intermediate muscle layers of the pylorus and duodenum to model Parkinson's disease (PD). We used Immunohistochemistry staining, Western Blot, Flow cytometry to detect the changes of TH, α-syn, pro-inflammatory factors, barrier-related proteins and CD4 + T cells differentiation.
Our results show that LAG3 knockout partially alleviates psychological and behavioral deficits, dopamine system damage, and the gut-to-brain transmission of α-syn, which correlates with enhanced regulatory T cell (Treg) cell proliferation. Furthermore, LAG3 knockout improved intestinal dysfunction and increased the expression of tight junction proteins in both the gut and the blood-brain barrier (BBB). In CD4 + T cells isolated from the spleen, LAG3 knockout suppressed the aggregation of α-syn PFF, thereby inhibiting the toxic T-cell response induced by α-syn PFF. LAG3 deficiency also enhanced the IL-2/STAT5 signaling pathway, which regulates Treg proportions both in vivo and in vitro.
Our findings demonstrated that LAG3 intrinsically limits Treg cell proliferation and function in the environment with pathological α-syn and promotes the gut-to-brain transmission of α-syn.
© 2025. The Author(s).

Accumulating evidence implicates the gut microbiome (GMB) in the pathogenesis and progression of Alzheimer's disease (AD). We recently showed that the GMB regulates reactive astrocytosis and Aβ plaque accumulation in a male APPPS1-21 AD mouse model. Yet, the mechanism(s) by which GMB perturbation alters reactive astrocytosis in a manner that reduces Aβ deposition remain unknown. Here, we performed metabolomics on plasma from mice treated with antibiotics (ABX) and identified a significant increase in plasma propionate, a gut-derived short-chain fatty acid, only in male mice. Administration of sodium propionate reduced reactive astrocytosis and Aβ plaques in APPPS1-21 mice, phenocopying the ABX-induced phenotype. Astrocyte-specific RNA-Seq on ABX- and propionate-treated mice showed reduced expression of proinflammatory and increased expression of neurotrophic genes. Next, we performed flow cytometry experiments, in which we found that ABX and propionate decreased peripheral RAR-related orphan receptor-γ+ (Rorγt+) CD4+ (Th17) cells and IL-17 secretion, which positively correlated with reactive astrocytosis. Last, using an IL-17 mAb to deplete IL-17, we found that propionate reduced reactive astrocytosis and Aβ plaques in an IL-17-dependent manner. Together, these results suggest that gut-derived propionate regulates reactive astrocytosis and Aβ amyloidosis by decreasing peripheral Th17 cells and IL-17 release. Thus, propionate treatment or strategies boosting propionate production may represent novel therapeutic strategies for the treatment of AD.

Immune checkpoint-based immunotherapy has shown limited efficacy in the treatment of ovarian cancer. In recent years, the emergence of immune checkpoint co-targeting therapies, led by the combination targeting of TIGIT and FAK, has shown promise in ovarian cancer treatment. Our preliminary research indicates that TIGIT is predominantly expressed in regulatory T cells during ovarian cancer. However, the therapeutic impact of TIGIT targeting based on regulatory T cells in ovarian cancer remains to be elucidated. We utilized ID8 cells to establish a mouse model of ovarian cancer. Through flow cytometry and co-culture methods, we validated the relationship between the functionality of regulatory T cells and tumor masses, and confirmed the crucial role of TIGIT in immune suppression in ovarian cancer. Furthermore, using Foxp3-diphtheria toxin receptor (DTR) mice, we substantiated that the combined TIGIT antibody treatment, based on targeting regulatory T cells, effectively slowed down the progression of ovarian cancer. Taken together, our results have demonstrated that dual targeting of regulatory T cells and TIGIT effectively retards tumor growth, laying the groundwork for the clinical application of immune checkpoint combination therapies. Future research in ovarian cancer immunotherapy is leaning towards a strategy that combines multiple targets, and specific cell-type immunotherapies.
© 2024. The Author(s).

Reprogramming tryptophan metabolism (TRP) may be able to overcome immunosuppression and restore the immune checkpoint blockade (ICB) response in patients with epithelial ovarian cancer (EOC) resistant to ICB therapy because TRP metabolism is involved in the kynurenine/indole and serotonin pathways of tryptophan metabolism. Herein, employing amitriptyline (AMI), an antagonist of TLR4 and serotonin transporter (SERT), we revealed that AMI remodels the immunological landscape of EOC. In particular, AMI lowered the expression of IDO1, IL-4I1, and PD-L1, the quantity of KYN and indoles, and the level of immunosuppressive immune cells MDSC, Tregs, and CD8+CD39+/PD-1+ T cell. AMI boosted the killing potential of anti-PD-1-directed CD8+T cells and worked in concert with PD-1 inhibitors to suppress tumor growth and to prolong the survival of EOC-bearing mice. This work highlights AMI as an effective regulator of ICB response by manipulating EOC cell TRP metabolism, indicating it could be a potential strategy for improving EOC ICB therapy.
© 2024 The Author(s).

Super enhancers (SEs) are large clusters of transcriptional enhancers driving the expression of genes crucial for defining cell identity. In cancer, tumor-specific SEs activate key oncogenes, leading to tumorigenesis. Identifying SE-driven oncogenes in tumors and understanding their functional mechanisms is of significant importance. In this study, a previously unreported SE region is identified in T-cell acute lymphoblastic leukemia (T-ALL) patient samples and cell lines. This SE activates the expression of interferon regulatory factor 2 binding protein 2 (IRF2BP2) and is regulated by T-ALL master transcription factors (TFs) such as ETS transcription factor ERG (ERG), E74 like ETS transcription factor 1 (ELF1), and ETS proto-oncogene 1, transcription factor (ETS1). Hematopoietic system-specific IRF2BP2 conditional knockout mice is generated and showed that IRF2BP2 has minimal impact on normal T cell development. However, in vitro and in vivo experiments demonstrated that IRF2BP2 is crucial for T-ALL cell growth and survival. Loss of IRF2BP2 affects the MYC and E2F pathways in T-ALL cells. Cleavage under targets and tagmentation (CUT&Tag) assays and immunoprecipitation revealed that IRF2BP2 cooperates with the master TFs of T-ALL cells, targeting the enhancer of the T-ALL susceptibility gene recombination activating 1 (RAG1) and modulating its expression. These findings provide new insights into the regulatory network within T-ALL cells, identifying potential new targets for therapeutic intervention.
© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.