Fine-tuning of regulatory T cells is indispensable for the metabolic steatosis-related hepatocellular carcinoma: A review

Τ cell-mediated adaptive immunity in the transition from metabolic dysfunction-associated steatohepatitis to hepatocellular carcinoma

Metabolic dysfunction-associated steatohepatitis (MASH) is the progressed version of metabolic dysfunction-associated steatotic liver disease (MASLD) characterized by inflammation and fibrosis, but also a pathophysiological "hub" that favors the emergence of liver malignancies. Current research efforts aim to identify risk factors, discover disease biomarkers, and aid patient stratification in the context of MASH-induced hepatocellular carcinoma (HCC), the most prevalent cancer among MASLD patients. To investigate the tumorigenic transition in MASH-induced HCC, researchers predominantly exploit preclinical animal-based MASH models and studies based on archived human biopsies and clinical trials. Recapitulating the immune response during tumor development and progression is vital to obtain mechanistic insights into MASH-induced HCC. Notably, the advanced complexity behind MASLD and MASH pathogenesis shifted the research focus towards innate immunity, a fundamental element of the hepatic immune niche that is usually altered robustly in the course of liver disease. During the last few years, however, there has been an increasing interest for deciphering the role of adaptive immunity in MASH-induced HCC, particularly regarding the functions of the various T cell populations. To effectively understand the specific role of T cells in MASH-induced HCC development, scientists should urgently fill the current knowledge gaps in this field. Pinpointing the metabolic signature, sketching the immune landscape, and characterizing the cellular interactions and dynamics of the specific T cells within the MASH-HCC liver are essential to unravel the mechanisms that adaptive immunity exploits to enable the emergence and progression of this cancer. To this end, our review aims to summarize the current state of research regarding the T cell functions linked to MASH-induced HCC.

Regulatory T cell: a double-edged sword from metabolic-dysfunction-associated steatohepatitis to hepatocellular carcinoma

Metabolic-dysfunction-associated steatotic liver disease (MASLD) is becoming a leading cause of end-stage liver disease globally. Metabolic-dysfunction-associated steatohepatitis (MASH) represents a progressive inflammatory manifestation of MASLD. MASH underlies a versatile and dynamic inflammatory microenvironment, accompanied by aberrant metabolism and ongoing liver regeneration, establishing itself as a significant risk factor for hepatocellular carcinoma (HCC). The mechanisms underlying the escape and survival of malignant cells within the extensive inflammatory microenvironment of MASH remain elusive. Regulatory T cells (Tregs) play a crucial role in maintaining homeostasis and preventing excessive immune responses in the liver. Paradoxically, Tregs have been implicated in inhibiting tumour-promoting inflammation and facilitating the evasion of cancer cells. Recent studies have unveiled distinct behaviours of Tregs at different stages of MASLD, suggesting a dual role in the pathogenesis. In this review, we explore the fate of Tregs from MASLD to HCC, offering recent insights into potential targets for clinical intervention.

Forces at play: exploring factors affecting the cancer metastasis

Metastatic disease, a leading and lethal indication of deaths associated with tumors, results from the dissemination of metastatic tumor cells from the site of primary origin to a distant organ. Dispersion of metastatic cells during the development of tumors at distant organs leads to failure to comply with conventional treatments, ultimately instigating abrupt tissue homeostasis and organ failure. Increasing evidence indicates that the tumor microenvironment (TME) is a crucial factor in cancer progression and the process of metastatic tumor development at secondary sites. TME comprises several factors contributing to the initiation and progression of the metastatic cascade. Among these, various cell types in TME, such as mesenchymal stem cells (MSCs), lymphatic endothelial cells (LECs), cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), T cells, and tumor-associated macrophages (TAMs), are significant players participating in cancer metastasis. Besides, various other factors, such as extracellular matrix (ECM), gut microbiota, circadian rhythm, and hypoxia, also shape the TME and impact the metastatic cascade. A thorough understanding of the functions of TME components in tumor progression and metastasis is necessary to discover new therapeutic strategies targeting the metastatic tumor cells and TME. Therefore, we reviewed these pivotal TME components and highlighted the background knowledge on how these cell types and disrupted components of TME influence the metastatic cascade and establish the premetastatic niche. This review will help researchers identify these altered components' molecular patterns and design an optimized, targeted therapy to treat solid tumors and restrict metastatic cascade.

Pharmacological therapy of metabolic dysfunction-associated steatotic liver disease-driven hepatocellular carcinoma

In light of a global rise in the number of patients with type 2 diabetes mellitus (T2DM) and obesity, non-alcoholic fatty liver disease (NAFLD), now known as metabolic dysfunction-associated fatty liver disease (MAFLD) or metabolic dysfunction-associated steatotic liver disease (MASLD), has become the leading cause of hepatocellular carcinoma (HCC), with the annual occurrence of MASLD-driven HCC expected to increase by 45%-130% by 2030. Although MASLD has become a serious major public health threat globally, the exact molecular mechanisms mediating MASLD-driven HCC remain an open problem, necessitating future investigation. Meanwhile, emerging studies are focusing on the utility of bioactive compounds to halt the progression of MASLD to MASLD-driven HCC. In this review, we first briefly review the recent progress of the possible mechanisms of pathogenesis and progression for MASLD-driven HCC. We then discuss the application of bioactive compounds to mitigate MASLD-driven HCC through different modulatory mechanisms encompassing anti-inflammatory, lipid metabolic, and gut microbial pathways, providing valuable information for future treatment and prevention of MASLD-driven HCC. Nonetheless, clinical research exploring the effectiveness of herbal medicines in the treatment of MASLD-driven HCC is still warranted.

Gut microbe and hepatic macrophage polarization in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a common chronic hepatic disorder with the potential to progress to hepatic fibrosis, hepatic cirrhosis, and even hepatocellular carcinoma. Activation of hepatic macrophages, important innate immune cells predominantly composed of Kupffer cells, plays a pivotal role in NAFLD initiation and progression. Recent findings have underscored the regulatory role of microbes in both local and distal immune responses, including in the liver, emphasizing their contribution to NAFLD initiation and progression. Key studies have further revealed that gut microbes can penetrate the intestinal mucosa and translocate to the liver, thereby directly influencing hepatic macrophage polarization and NAFLD progression. In this review, we discuss recent evidence regarding the translocation of intestinal microbes into the liver, as well as their impact on hepatic macrophage polarization and associated cellular and molecular signaling pathways. Additionally, we summarize the potential mechanisms by which translocated microbes may activate hepatic macrophages and accelerate NAFLD progression.

Diagnostic role and immune correlates of programmed cell death-related genes in hepatocellular carcinoma

Programmed cell death (PCD) is thought to have multiple roles in tumors. Here, the roles of PCD-related genes were comprehensively analyzed to evaluate their values in hepatocellular carcinoma (HCC) diagnosis and prognosis. Gene expression and single-cell data of HCC patients, and PCD-related genes were collected from public databases. The diagnostic and prognostic roles of differentially expressed PCD-related genes in HCC were explored by univariate and multivariate Cox regression analyses. Single-cell data were further analyzed for the immune cells and expression of feature genes. Finally, we evaluated the expression of genes by quantitative real-time polymerase chain reaction and Western blot, and the proportion of immune cells was detected by flow cytometry in HCC samples. We obtained 52 differentially expressed PCD-related genes in HCC, based on which the consensus clustering analysis cluster 2 was found to have a worse prognosis than cluster 1. Then 10 feature genes were identified using LASSO analysis, and programmed cell death index (PCDI) was calculated to divided HCC patients into high-PCDI and low-PCDI groups. Worse prognosis was observed in high-PCDI group. Cox regression analysis showed that PCDI is an independent prognostic risk factor for HCC patients. Additionally, SERPINE1 and G6PD of feature genes significantly affect patient survival. Macrophages and Tregs were significantly positively correlated with PCDI. G6PD mainly expressed in macrophages, SERPINE1 mainly expressed in fibroblast. The experimental results confirmed the high expression of SERPINE1 and G6PD in HCC compared with the control, and the infiltration level of macrophages and Treg in HCC was also obviously elevated. PCDI may be a new predictor for the diagnosis of patients with HCC. The association of SERPINE1 and G6PD with the immune environment will provide new clues for HCC therapy.

Targeting post-translational modifications of Foxp3: a new paradigm for regulatory T cell-specific therapy

A healthy immune system is pivotal for the hosts to resist external pathogens and maintain homeostasis; however, the immunosuppressive tumor microenvironment (TME) damages the anti-tumor immunity and promotes tumor progression, invasion, and metastasis. Recently, many studies have found that Foxp3+ regulatory T (Treg) cells are the major immunosuppressive cells that facilitate the formation of TME by promoting the development of various tumor-associated cells and suppressing the activity of effector immune cells. Considering the role of Tregs in tumor progression, it is pivotal to identify new therapeutic drugs to target and deplete Tregs in tumors. Although several studies have developed strategies for targeted deletion of Treg to reduce the TME and support the accumulation of effector T cells in tumors, Treg-targeted therapy systematically affects the Treg population and may lead to the progression of autoimmune diseases. It has been understood that, nevertheless, in disease conditions, Foxp3 undergoes several definite post-translational modifications (PTMs), including acetylation, glycosylation, phosphorylation, ubiquitylation, and methylation. These PTMs not only elevate or mitigate the transcriptional activity of Foxp3 but also affect the stability and immunosuppressive function of Tregs. Various studies have shown that pharmacological targeting of enzymes involved in PTMs can significantly influence the PTMs of Foxp3; thus, it may influence the progression of cancers and/or autoimmune diseases. Overall, this review will help researchers to understand the advances in the immune-suppressive mechanisms of Tregs, the post-translational regulations of Foxp3, and the potential therapeutic targets and strategies to target the Tregs in TME to improve anti-tumor immunity.

Modulation of T cells by tryptophan metabolites in the kynurenine pathway

Lymphocytes maturing in the thymus (T cells) are key factors in adaptive immunity and the regulation of inflammation. The kynurenine pathway of tryptophan metabolism includes several enzymes and compounds that can modulate T cell function, but manipulating these pharmacologically has not achieved the expected therapeutic activity for the treatment of autoimmune disorders and cancer. With increasing knowledge of other pathways interacting with kynurenines, the expansion of screening methods, and the application of virtual techniques to understanding enzyme structures and mechanisms, details of interactions between kynurenines and other pathways are being revealed. This review surveys some of these alternative approaches to influence T cell function indirectly via the kynurenine pathway and summarizes the most recent work on the development of compounds acting directly on the kynurenine pathway.

Identification and Evaluation of Hub Long Noncoding RNAs and mRNAs in High Fat Diet Induced Liver Steatosis

Nonalcoholic fatty liver disease (NAFLD) is considered the most prevalent chronic liver disease, but the understanding of the mechanism of NAFLD is still limited. The aim of our study was to explore hub lncRNAs and mRNAs and pathological processes in high-fat diet (HFD)-induced and lycopene-intervened liver steatosis. We analyzed the gene profiles in the GSE146627 dataset from the Gene Expression Omnibus (GEO) database to identify differentially expressed lncRNAs and mRNAs, and we constructed coexpression networks based on weighted gene coexpression network analysis (WGCNA). The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were utilized for functional enrichment analysis. We found that the turquoise, blue, brown, yellow, green, and black modules were significantly correlated with NAFLD. Functional enrichment analysis revealed that some hub lncRNAs (Smarca2, Tacc1, Flywch1, and Mef2c) might be involved in the regulation of the inflammatory and metabolic pathways (such as TNF signaling, metabolic, mTOR signaling, MAPK signaling, and p53 signaling pathways) in NAFLD. The establishment of an NAFLD mouse model confirmed that lycopene supply attenuated hepatic steatosis in HFD-induced NAFLD. Our analysis revealed that the inflammatory and metabolic pathways may be crucially involved in the pathogenesis of NAFLD, and hub lncRNAs provide novel biomarkers, therapeutic ideas, and targets for NAFLD. Moreover, lycopene has the potential to be a phytochemical for the prevention of HFD-induced liver steatosis.

Metabolic Associated Fatty Liver Disease as a Risk Factor for the Development of Central Nervous System Disorders

MAFLD/NAFLD is the most ordinary liver disease categorized by hepatic steatosis with the increase of surplus fat in the liver and metabolic liver dysfunction, which is associated with bigger mortality and a high medical burden. An association between MAFLD/NAFLD and central nervous system disorders including psychological disorders has been demonstrated. Additionally, MAFLD/NAFLD has been correlated with various types of neurodegenerative disorders such as amyotrophic lateral sclerosis or Parkinson’s disease. Contrasted to healthy controls, patients with MAFLD/NAFLD have a greater prevalence risk of extrahepatic complications within multiple organs. Dietary interventions have emerged as effective strategies for MAFLD/NAFLD. The PI3K/AKT/mTOR signaling pathway involved in the regulation of Th17/Treg balance might promote the pathogenesis of several diseases including MAFLD/NAFLD. As extrahepatic complications may happen across various organs including CNS, cooperative care with individual experts is also necessary for managing patients with MAFLD/NAFLD.

Alcohol use disorder and liver injury related to the COVID-19 pandemic

Alcohol use disorder is a complex and heterogeneous phenomenon that can be studied from several points of view by focusing on its different components. Alcohol is a hepatotoxin whose metabolism creates profound alterations within the hepatocyte. The liver is the central organ in the metabolism of alcohol, a process that also involves other organs and tissues such as the brain, heart and muscles, but the most relevant organ is the liver. The anatomopathological alterations in the liver associated with the prolonged use of alcohol range from the simple accumulation of neutral fats in the hepatocytes, to cirrhosis and hepatocellular carcinoma. Alcohol abuse frequently leads to liver disease such as steatosis, steatohepatitis, fibrosis, cirrhosis, and tumors. Following the spread of coronavirus disease 2019 (COVID-19), there was an increase in alcohol consumption, probably linked to the months of lockdown and smart working. It is known that social isolation leads to a considerable increase in stress, and it is also recognized that high levels of stress can result in an increase in alcohol intake. Cirrhotic patients or subjects with liver cancer are immunocompromised, so they may be more exposed to COVID-19 infection with a worse prognosis. This review focuses on the fact that the COVID-19 pandemic has made the emergence of alcohol-induced liver damage a major medical and social problem.

Salvianolic acid B from Salvia miltiorrhiza bunge: A potential antitumor agent

Salvia miltiorrhiza Bunge (Lamiaceae) is a perennial herb widely found in China since ancient times with a high economic and medicinal value. Salvianolic acid B (Sal-B) is an important natural product derived from Salvia miltiorrhiza and this review summarizes the anticancer activity of Sal-B. Sal-B inhibits tumor growth and metastasis by targeting multiple cell signaling pathways. This review aims to review experimental studies to describe the possible anticancer mechanisms of Sal-B and confirm its potential as a therapeutic drug.