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).

Antigen-specific recognition of microbiota by T cells enforces tolerance at homeostasis. Conversely, dysbiosis leads to imbalanced T-cell responses, triggering inflammatory and autoimmune diseases. Despite their significance, the identities of immunogenic microbial antigens remain largely enigmatic. Here, we leveraged a sensitive, unbiased, genome-wide screening platform to identify peptides from Akkermansia muciniphila (AKK) and Bacteroides thetaiotaomicron (BT) recognized by CD4+ T cells. The platform is based on screening peptide libraries using an NFAT-fluorescence reporter cell line transduced with a retrovirus encoding an MHC-TCR (MCR) hybrid molecule. We discovered several novel epitopes from AKK and BT. T-cell hybridomas reactive to AKK and BT bacteria demonstrated polyreactivity to microbiota-derived peptides in co-cultures with MCR reporter cells. Steady-state T cells recognized these epitopes in an MHC-restricted fashion. Intriguingly, most of the identified epitopes are broadly conserved within the given phylum and originate from membrane and intracellular proteins. Ex vivo stimulation of CD4+ T cells from mice vaccinated with the identified peptides revealed mono-specific IFN-γ and IL-17 responses. Our work showcases the potential of the MCR system for identifying immunogenic microbial epitopes, providing a valuable resource. Our study facilitates decoding antigen specificity in immune system-bacterial interactions, with applications in understanding microbiome and pathogenic bacterial immunity.
© 2025 Wiley‐VCH GmbH.

Lipid nanoparticle (LNP)-based mRNA therapeutics, highlighted by the success of SARS-CoV-2 vaccines, face challenges due to inflammation caused by ionizable lipids. These ionizable lipids can activate the immune system, particularly when co-delivered with nucleic acids, leading to undesirable inflammatory responses. We introduce a novel class of anti-inflammatory ionizable lipids functionalized with hydroxychloroquine (HCQ), which suppresses both lipid-induced and nucleic acid-induced immune activation. These HCQ-functionalized LNPs (HL LNPs) exhibit reduced proinflammatory responses while maintaining efficient mRNA delivery. Structural and physicochemical analyses revealed that HCQ-functionalization results in a distinct particle structure with significantly improved stability. The efficacy of HL LNPs was demonstrated across various therapeutic contexts, including a prophylactic vaccination model against varicella-zoster virus (VZV) and CRISPR-Cas9 gene editing targeting PCSK9. Notably, HL LNPs showed robust mRNA expression after repeated administration, addressing concerns of inflammation and ensuring sustained therapeutic effects. These findings highlight the potential of HCQ-functionalized LNPs in expanding the safe use of mRNA therapeutics, particularly for applications requiring repeated dosing and in scenarios where inflammation-induced side effects must be minimized.

Tyrosine kinase 2 (TYK2)-dependent cytokine signalling is integral to the pathogenesis of psoriasis. While BMS-986165, a highly selective TYK2 inhibitor, has recently been approved for oral treatment of psoriasis, its therapeutic potential via topical application remains unexplored.
We aim to investigate the efficacy of topically applying TYK2 inhibitor in psoriasis and to elucidate the underlying mechanisms driving the therapeutic effects of this delivery approach.
1.5% BMS-986165 ointment was applied topically to the back skin of imiquimod (IMQ)-induced psoriatic mice. To identify potential target cells influenced by the topical TYK2 inhibitor, we performed single cell RNA sequencing (scRNA-seq) and flow cytometry on mouse lesions. The role of TYK2 in vitro was assessed by silencing its expression or administering BMS-986165 in human keratinocytes (KCs). Mechanistic insights into TYK2 function in KCs were further investigated using RNA-seq, dual luciferase reporter assay and ChIP-qPCR.
External use of 1.5% BMS-986165 ointment significantly ameliorated the IMQ-induced psoriasis-like dermatitis. Importantly, topical TYK2 inhibitor attenuated proinflammatory capability of KCs. In vitro, TYK2 inhibition suppressed the transcription of nerve growth factor receptor (NGFR) by disrupting the AKT-SP1 signalling pathway. This impairment hindered the activation of activator protein 1 (AP1), thereby weakening the proinflammatory potential of KCs.
This study reveals a novel therapeutic potential for selective TYK2 inhibitor in topical manner on psoriasis therapy, which might prompt the development of topical treatment for psoriasis. Crucially, our findings provide an underexplored regulatory mechanism of TYK2 inhibitor in psoriasis.
Topical TYK2 inhibitor alleviates psoriasis-like dermatitis. Topical TYK2 inhibitor reduces psoriasis progression through restraining the inflammatory responses of keratinocytes. The inhibition of TYK2 regulates the inflammatory response of keratinocytes through AKT-SP1-NGFR-AP1 pathway.
© 2025 The Author(s). Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.

ABSTRACT Peptide-based therapeutic immunizations represent safe approaches to elicit antigen-specific T cell responses, but their broad utility remains limited due to poor immunogenicity and short in vivo stability due to rapid degradation and clearance. Here we employed synthetic bacterial spore-like particles, “SSHELs”, made entirely of biocompatible materials, to deliver a model peptide antigen in the absence of additional adjuvants. SSHELs carrying the peptide antigen were internalized by dendritic cells and SSHEL-delivered peptides were then processed and cross-presented in vitro and in vivo more efficiently than free peptides. Further, SSHEL-delivered peptides elicited effective antigen-specific T cell expansion in a manner that was dependent on particle size and peptide presentation mode (encased peptides were superior to surface-attached peptides). In a mouse melanoma model expressing the antigen ovalbumin, therapeutic immunization reduced tumor size and increased survival. We propose that SSHELs are a self-adjuvanting peptide delivery system that mimics a natural presentation to elicit a robust immune response.