Objectives: Interleukin‐6 (IL‐6) is critical for the development of non‐small‐cell lung cancer (NSCLC). Recently, we identified T‐cell immunoglobulin domain and mucin domain 4 (TIM‐4) as a new pro‐growth player in NSCLC progression. However, the role of TIM‐4 in IL‐6‐promoted NSCLC migration, invasion and epithelial‐to‐mesenchymal transition (EMT) remains unclear.Materials and Methods: Expressions of TIM‐4 and IL‐6 were both evaluated by immunohistochemical staining in NSCLC tissues. Real‐time quantitative PCR (qPCR), Western blot, flow cytometry and RT‐PCR were performed to detect TIM‐4 expression in NSCLC cells with IL‐6 stimulation. The roles of TIM‐4 in IL‐6 promoting migration and invasion of NSCLC were detected by transwell assay. EMT‐related markers were analysed by qPCR and Western blot in vitro, and metastasis was evaluated in BALB/c nude mice using lung cancer metastasis mouse model in vivo.Results: High IL‐6 expression was identified as an independent predictive factor for TIM‐4 expression in NSCLC tissues. NSCLC patients with TIM‐4 and IL‐6 double high expression showed the worst prognosis. IL‐6 promoted TIM‐4 expression in NSCLC cells depending on NF‐κB signal pathway. Both TIM‐4 and IL‐6 promoted migration, invasion and EMT of NSCLC cells. Interestingly, TIM‐4 knockdown reversed the role of IL‐6 in NSCLC and IL‐6 promoted metastasis of NSCLC by up‐regulating TIM‐4 via NF‐κB.Conclusions: TIM‐4 involves in IL‐6 promoted migration, invasion and EMT of NSCLC.

Background: Microglia, the resident macrophages of central nervous system, have been initially categorized into two opposite phenotypes: classical activation related to pro-inflammatory responses and alternative activation corresponding with anti-inflammatory reactions and tissue remodeling. The correlation between metabolic pattern and microglial activation has been identified. However, little is known about the mechanism of metabolism-mediated microglia polarization and pro-inflammatory effect.Methods: Metabolic alteration was analyzed in different phenotypes of microglia in vitro. LPS-induced neuroinflammation and sickness behavior mouse model was used to investigate the effect of lactate on classical microglial activation in vivo.Results: Glycolysis-related regulators, monocarboxylate transporter 1 (MCT1), MCT4, and pro-glycolytic enzyme 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3 (PFKFB3), were specifically increased in LPS-stimulated primary microglia and microglia cell line BV2. Knockdown of MCT1 suppressed glycolysis rate and decreased LPS-induced expression of iNOS, interleukin-1β (IL-1β), IL-6, and phosphorylation of STAT1 in BV2 cells. Importantly, MCT1 promoted PFKFB3 expression via hypoxia-inducible factor-1α (Hif-1α), and overexpression of PFKFB3 restored the classical activation of BV2 cells suppressed by MCT1 silence. All above strongly suggested that MCT1/PFKFB3 might accelerate LPS-induced classical polarization of microglia probably by promoting glycolysis. Interestingly, additional administration of moderate lactate, which may block the transport function of MCT1, decreased LPS-induced classical activation and expression of PFKFB3 in BV2 cells. Intracerebroventricular injection of lactate ameliorated LPS-induced sickness behavior and classical polarization of microglia in mice.Conclusions: Our results demonstrate the key role of MCT1 in microglial classical activation and neuroinflammation in pathological conditions. In addition, lactate administration may be a potential therapy to suppress neuroinflammation by altering microglial polarization.

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.

Fatty liver disease, characterized by excessive inflammation and lipid deposition, is becoming one of the most prevalent liver metabolic diseases worldwide owing to the increasing global incidence of obesity. However, the underlying mechanisms of fatty liver disease are poorly understood. Accumulating evidence suggests that hepatic macrophages, specifically Kupffer cells (KCs), act as key players in the progression of fatty liver disease. Thus, it is essential to examine the current evidence of the roles of hepatic macrophages (both KCs and monocyte-derived macrophages). In this review, we primarily address the heterogeneities and multiple patterns of hepatic macrophages participating in the pathogenesis of fatty liver disease, including Toll-like receptors (TLRs), NLRP3 inflammasome, lipotoxicity, glucotoxicity, metabolic reprogramming, interaction with surrounding cells in the liver, and iron poisoning. A better understanding of the diverse roles of hepatic macrophages in the development of fatty liver disease may provide a more specific and promising macrophage-targeting therapeutic strategy for inflammatory liver diseases.

Liver-resident natural killer cells, a unique lymphocyte subset in liver, develop locally and play multifaceted immunological roles. However, the mechanisms for the maintenance of liver-resident natural killer cell homeostasis remain unclear. Here we show that early-life antibiotic treatment blunt functional maturation of liver-resident natural killer cells even at adulthood, which is dependent on the durative microbiota dysbiosis. Mechanistically, early-life antibiotic treatment significantly decreases butyrate level in liver, and subsequently led to defective liver-resident natural killer cell maturation in a cell-extrinsic manner. Specifically, loss of butyrate impairs IL-18 production in Kupffer cells and hepatocytes through acting on the receptor GPR109A. Disrupted IL-18/IL-18R signaling in turn suppresses the mitochondrial activity and the functional maturation of liver-resident natural killer cells. Strikingly, dietary supplementation of experimentally or clinically used Clostridium butyricum restores the impaired liver-resident natural killer cell maturation and function induced by early-life antibiotic treatment. Our findings collectively unmask a regulatory network of gut-liver axis, highlighting the importance of the early-life microbiota in the development of tissue-resident immune cells.

T cell immunoglobulin and mucin-containing molecule 3 (Tim-3), expressed in dysfunctional and exhausted T cells, has been widely acknowledged as a promising immune checkpoint target for tumor immunotherapy. Here, using a strategy combining virtual and functional screening, we identified a compound named ML-T7 that targets the FG-CC′ cleft of Tim-3, a highly conserved binding site of phosphatidylserine (PtdSer) and carcinoembryonic antigen–related cell adhesion molecule 1 (CEACAM1). ML-T7 enhanced the survival and antitumor activity of primary CD8 ⁺ cytotoxic T lymphocytes (CTLs) and human chimeric antigen receptor (CAR) T cells and reduced their exhaustion in vitro and in vivo. In addition, ML-T7 promoted NK cells’ killing activity and DC antigen-presenting capacity, consistent with the reported activity of Tim-3. ML-T7 strengthened DCs’ functions through both Tim-3 and Tim-4, which is consistent with the fact that Tim-4 contains a similar FG-CC′ loop. Intraperitoneal dosing of ML-T7 showed comparable tumor inhibitory effects to the Tim-3 blocking antibody. ML-T7 reduced syngeneic tumor progression in both wild-type and Tim-3 humanized mice and alleviated the immunosuppressive microenvironment. Furthermore, combined ML-T7 and anti–PD-1 therapy had greater therapeutic efficacy than monotherapy in mice, supporting further development of ML-T7 for tumor immunotherapy. Our study demonstrates a potential small molecule for selectively blocking Tim-3 and warrants further study.