Chunyang Li

Multiple sclerosis (MS) is a chronic autoimmune disorder characterized by the immune-mediated demyelination and neurodegeneration of the central nervous system. Phagocyte mediated myelin debris clearance is required for remyelination. TIM-3 is highly expressed on mononuclear macrophages and promotes the phagocytosis of apoptotic cells. Here, we report that TIM-3 enhances the clearance of myelin debris in experimental autoimmune encephalomyelitis (EAE), a model of MS. Tim-3 knockout (KO) exacerbated EAE severity, neuroinflammation, and demyelination by regulating mononuclear macrophages. TIM-3 promoted the phagocytosis and degradation of myelin debris by macrophages. Mechanistically, Tim-3 deficiency impaired lysosomal biogenesis and function, leading to lysosomal membrane permeabilization and disrupted lysosomal acidification, which further exacerbated neuroinflammation and demyelination. Notably, TIM-3 blocked the interaction of mTOR–TFEB to inhibit TFEB phosphorylation and facilitate its nuclear translocation, followed by increased expression of lysosomal genes critical for myelin degradation. Importantly, the IgV domain is necessary in TIM-3-mediated lysosomal regulation and myelin degradation. These findings highlight TIM-3 as a key regulator of lysosomal homeostasis and the clearance of myelin debris, suggesting that the IgV domain has promise as a therapeutic agent for treating demyelinating diseases such as MS.

Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) constitutes a viral persistence reservoir that sustains chronic infection. Although the DNA damage response (DDR) facilitates cccDNA biogenesis, its role in regulating cccDNA stability remains unclear. By intersecting published cccDNA-associated proteomic datasets with known DDR-related host factors, we identified heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNPA2B1) as a novel restriction factor that binds cccDNA and suppresses HBV replication by promoting cccDNA degradation. Mechanistically, hnRNPA2B1 interacted with the G-quadruplex (G4) structure of cccDNA, with preference for G4-1, G4-7, and G4-10, and leads to the recruitment of the cytidine deaminase APOBEC3B by its prion-like domain (PrLD), thereby inducing C>T and G>A hypermutations and initiating cccDNA decay. Notably, HBV counteracts this defense mechanism through HBx-mediated hnRNPA2B1 polyubiquitination and proteasomal degradation, revealing a viral evasion strategy that perpetuates cccDNA persistence. These findings reveal a G4-dependent surveillance axis wherein hnRNPA2B1 directs APOBEC3B-mediated cytidine deamination to destabilize cccDNA while identifying HBx-induced hnRNPA2B1 ubiquitination as a viral countermeasure. This mechanistic duality not only elucidates a critical virus-host interaction governing cccDNA persistence but also provides a promising therapeutic target for the treatment of HBV infection.

Psychological stress is increasingly linked to liver disease, but the underlying mechanisms remain unclear. Here we show that chronic stress disrupts a brain–liver circuit that impairs hepatic CD8⁺ T cell immunity and accelerates liver cancer progression. Using both oncogene-driven and carcinogen-driven liver cancer models in male mice, we find that psychological stress disrupts catecholamine/β2-adrenergic receptor (ADRB2) signalling, which suppresses the expression of quinolinate phosphoribosyl transferase (QPRT), an enzyme of the kynurenine pathway, in hepatocytes. QPRT loss diverts kynurenine metabolism away from nicotinamide adenine dinucleotide (NAD⁺) synthesis towards kynurenic acid (KA) accumulation. This shift results in mitochondrial impairment and reduced effector function of liver CD8⁺ T cells. We confirm that ADRB2/QPRT expression correlates with hepatic NAD⁺ and KA levels and with CD8⁺ T cell frequency and function in human liver tissues. Importantly, ADRB2/QPRT overexpression in hepatocytes, or nicotinamide administration, recovers CD8⁺ T cell function in stressed mice and reduces liver cancer progression. These findings identify a stress-responsive metabolic checkpoint in the liver that links the nervous system to immune surveillance and may be therapeutically targeted in liver cancers.

Over the past decade, immunotherapy has emerged as a pivotal therapeutic strategy in cancer treatment. Immune checkpoint inhibitors (ICIs), such as CTLA-4 and PD-1 monoclonal antibodies, have demonstrated remarkable clinical efficacy in different types of cancer. However, the overall success rate of immune checkpoint therapies remains low. Investigating alternative immune checkpoint molecules is imperative. T-cell immunoglobulin and mucin-containing molecule-3 (TIM-3), which is expressed in T cells, natural killer (NK) cells, macrophages, and dendritic cells, has gained recognition as a promising candidate for tumor immunotherapy. Targeting TIM-3 represents a promising approach for cancer immunotherapy, particularly through the rational design of novel combination therapies with other ICIs. In this review, we present a comprehensive summary of the research advancements concerning the role of TIM-3 in regulating immune responses in different cell types and explore theoretical frameworks for targeting TIM-3 to achieve more effective immunotherapeutic breakthroughs.

Emerging evidence demonstrates that chronic stress alters immunological, neurochemical, and endocrinological functions, thereby promoting tumor progression. However, the underlying metabolic mechanism of chronic stress in tumor progression is still elusive. Using multiomics analysis, we found that aminopeptidase N (ANPEP) was upregulated in tumors with chronic restraint, associating with the reprogramming of amino acid metabolism. Functional assays revealed that ANPEP promoted liver cancer growth and metastasis. Knockdown of ANPEP blocked chronic stress–induced liver cancer progression. Chronic stress–induced glucocorticoids promoted nuclear receptor subfamily 3 group C member 1 nuclear translocation to activate ANPEP transcription by directly binding to its promoter. Furthermore, ANPEP promotes glutathione synthesis, subsequently inhibiting ROS-induced ferroptosis. Mechanistically, ANPEP interacted with solute carrier family 3 member 2 (SLC3A2) to block membrane associated ring-CH-type finger 8–mediated lysosome-dependent degradation of SLC3A2, promoting intracellular l-cystine transport, thereby increasing glutathione synthesis. The combination of ANPEP silencing and sorafenib treatment showed a synergistic effect in inhibiting liver cancer progression. Finally, clinical data and mouse models demonstrated that chronic stress drove liver tumor progression via ANPEP-regulated SLC3A2. These findings reveal unanticipated communication between chronic stress and metabolic reprogramming during liver cancer progression, providing potential therapeutic implications for liver cancer.

Ulcerative colitis (UC) is primarily characterized by inflammation-induced tissue damage, but impaired tissue repair also drives disease progression. This study demonstrates group 2 innate lymphoid cells (ILC2s), key players in tissue repair, are dysfunctional in UC and experimental colitis due to disrupted endoplasmic reticulum protein processing. We show that the pro-repair function of gut ILC2s depends on the IRE1α-Xbp1 branch of unfolded protein response (UPR), supported by IL-25 and suppressed by interferon-γ (IFN-γ). During colitis, loss of IL-25 and rise of IFN-γ hinder Xbp1 mRNA splicing, weakening ILC2s’ ability to mediate tissue repair. Mechanistically, spliced Xbp1 drives folate-dependent one-carbon (1C) metabolism by promoting dihydrofolate reductase expression. Translationally, the 1C metabolite adenosine 5′-monophosphate alleviated colitis in both ILC2-specific Xbp1 knockout and wild-type mice. Our findings highlight the UPR’s role in sensing gut environment to regulate ILC2 function and suggest folate-mediated 1C metabolism as a potential target for UC therapy.

T cell immunoglobulin and mucin domain–containing protein 3 (TIM-3) is an immune checkpoint that has critical roles in immune exhaustion. However, little is known about the mechanisms that regulate TIM-3 surface expression and turnover. Here, we report that human TIM-3 is palmitoylated by the palmitoyltransferase DHHC9 at residue cysteine 296 (Cys ²⁹⁶ ). Palmitoylation stabilized TIM-3 by preventing binding to E3 ubiquitin ligase HRD1, thereby suppressing its polyubiquitination and degradation. DHHC9 knockdown attenuated chimeric antigen receptor T (CAR-T) cell exhaustion, and a peptidic inhibitor of TIM-3 palmitoylation accelerated TIM-3 degradation and enhanced antitumor immunity mediated by CAR-T cells and natural killer (NK) cells. In hepatocellular carcinoma, DHHC9 expression correlated with TIM-3 expression in CD8 ⁺ T cells and NK cells, and high DHHC9 expression was associated with shorter survival in patients with high TIM-3. These findings demonstrate that palmitoylation of TIM-3 catalyzed by DHHC9 promotes its stability, resulting in immune exhaustion and impaired antitumor immunity.