LECT2 as a hepatokine links liver steatosis to inflammation via activating tissue macrophages in NASH

Inflammatory markers as diagnostic and precision nutrition tools for metabolic dysfunction-associated steatotic liver disease: Results from the Fatty Liver in Obesity trial

BACKGROUND & AIMS

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing public health concern. The disease is silent, and its diagnosis is often delayed. Inflammatory markers constitute an interesting tool to act as subrogate, non-invasive markers. This study aimed to evaluate the changes of inflammatory markers throughout a two-year dietary intervention in subjects presenting MASLD, to determine which of the markers are suitable to predict the disease, and act as a customizing tool for MASLD's dietary treatment.

METHODS

Ninety-eight subjects with MASLD and forty-five controls from the Fatty Liver in Obesity (FLiO) Study were analyzed. MASLD was diagnosed and graded by ultrasound. The MASLD subjects were randomly assigned to two different dietary strategies, the American Heart Association (AHA diet) or a dietary strategy based on the Mediterranean pattern, which was specially designed for the study (FLiO diet), and then followed for two years. Hepatic status was additionally assessed through Magnetic Resonance Imaging (MRI), elastography, and determination of transaminases.

RESULTS & DISCUSSION

Inflammatory markers improved throughout the intervention in the MASLD subjects and managed to reach similar levels to controls, especially at 6 and 12 months. Additionally, leptin, adiponectin, M30, and LECT2 managed to significantly diagnose the disease at all time marks of the intervention, making them candidates for subrogate non-invasive markers of the disease. Moreover, baseline chemerin, leptin, LECT2, and M65 were used to build a predictive score to achieve greater weight loss, and therefore, which strategy could be more useful for MASLD 's treatment. The predictive score was significantly able assign a specific diet to 55% of the study participants, meaning that the remaining 45% could achieve the same amount of weight loss following either diet equally.

CONCLUSION

Inflammatory markers constitute a potential non-invasive tool to be used in MASLD screening and could also constitute an interesting tool for MASLD's treatment customization, being able to predict the effectiveness of a dietary strategy based on the initial inflammatory state of each subject.

TRIAL REGISTRATION

www.

CLINICALTRIALS

gov (NCT03183193).

Relationship between the changes in hepatokine levels and metabolic effects after laparoscopic sleeve gastrectomy in severely obese patients

PURPOSE

To clarify the relationships between the changes in hepatokines and weight loss, and between these changes and the metabolic effects, and the roles played by these changes, after laparoscopic sleeve gastrectomy (LSG).

METHODS

We recruited 25 Japanese patients with severe obesity, who underwent LSG. We measured two hepatokines: selenoprotein P (SeP) and leukocyte cell-derived chemotaxin 2 (LECT2), at the baseline, and then 6 months and 1 year after LSG. Finally, we compared the changes in the hepatokines with the parameters of type 2 diabetes (T2D) and non-alcoholic steatohepatitis (NASH).

RESULTS

Changes in LECT2 were correlated with the percentage of total weight loss (ρ = - 0.499, P = 0.024) and the decrease in total fat area (ρ = 0.559, P = 0.003). The changes in SeP were correlated with those in hemoglobin A1c (ρ = 0.526, P = 0.043) and the insulinogenic index (ρ = 0.638, P = 0.010) in T2D patients. In patients with NASH, the LECT2 levels were correlated with liver steatosis (ρ = 0.601).

CONCLUSIONS

SeP levels decrease in association with HbA1c reduction, whereas LECT2 levels are associated with reductions in fat mass and NASH scores after LSG. Hepatokines may be involved in the pathology of obesity and its complications.

LECT2 Deletion Exacerbates Liver Steatosis and Macrophage Infiltration in a Male Mouse Model of LPS-mediated NASH

Leukocyte cell-derived chemotaxin 2 (LECT2) is a protein initially isolated as a neutrophil chemotactic factor. We previously found that LECT2 is an obesity-associated hepatokine that senses liver fat and induces skeletal muscle insulin resistance. In addition, hepatocyte-derived LECT2 activates macrophage proinflammatory activity by reinforcing the lipopolysaccharide (LPS)-induced c-Jun N-terminal kinase signaling. Based on these findings, we examined the effect of LECT2 deletion on nonalcoholic fatty liver disease/nonalcoholic steatohepatitis (NAFLD/NASH) caused by bacterial translocation. We created the bacterial translocation-mediated NAFLD/NASH model using LECT2 knockout mice (LECT2 KO) with 28 times a low-dose LPS injection under high-fat diet feeding conditions. LECT2 deletion exacerbated steatosis and significantly reduced p38 phosphorylation in the liver. In addition, LECT2 deletion increased macrophage infiltration with decreased M1/M2 ratios. LECT2 might contribute to protecting against lipid accumulation and macrophage activation in the liver under pathological conditions, which might be accomplished via p38 phosphorylation. This study provides novel aspects of LECT2 in the bacterial translocation-mediated NAFLD/NASH model.

Diabetes Accelerates Steatohepatitis in Mice: Liver Pathology and Single-Cell Gene Expression Signatures

Glucose lowering independently reduces liver fibrosis in human nonalcoholic fatty liver disease. This study investigated the impact of diabetes on steatohepatitis and established a novel mouse model for diabetic steatohepatitis. Male C57BL/6J mice were fed a 60% high-fat diet (HFD) and injected with carbon tetrachloride (CCl4) and streptozotocin (STZ) to induce diabetes. The HFD+CCl4+STZ group showed more severe liver steatosis, hepatocyte ballooning, and regenerative nodules compared with other groups. Diabetes up-regulated inflammatory cytokine-associated genes and increased the M1/M2 macrophage ratios in the liver. Single-cell RNA sequencing analysis of nonparenchymal cells in the liver showed that diabetes reduced Kupffer cells and increased bone marrow-derived recruited inflammatory macrophages, such as Ly6Chi-RM. Diabetes globally reduced liver sinusoidal endothelial cells (LSECs). Furthermore, genes related to the receptor for advanced glycation end products (RAGE)/Toll-like receptor 4 (TLR4) were up-regulated in Ly6Chi-RM and LSECs in mice with diabetes, suggesting a possible role of RAGE/TLR4 signaling in the interaction between inflammatory macrophages and LSECs. This study established a novel diabetic steatohepatitis model using a combination of HFD, CCl4, and STZ. Diabetes exacerbated steatosis, hepatocyte ballooning, fibrosis, regenerative nodule formation, and the macrophage M1/M2 ratios triggered by HFD and CCl4. Single-cell RNA sequencing analysis indicated that diabetes activated inflammatory macrophages and impairs LSECs through the RAGE/TLR4 signaling pathway. These findings open avenues for discovering novel therapeutic targets for diabetic steatohepatitis.

Elevated serum levels of leukocyte cell-derived chemotaxin 2 are associated with the prevalence of metabolic syndrome

AIMS

Inflammation is central to the pathogenesis of metabolic syndrome (MetS). Leukocyte cell-derived chemotaxin 2 (LECT2) is constitutively secreted in response to inflammatory stimuli and oxidative stress contributing to tissue or systemic inflammation. We explored the relationship between LECT2 levels and MetS severity in humans and mice.

METHODS

Serum LECT2 levels were measured in 210 participants with MetS and 114 without MetS (non-MetS). LECT2 expression in the liver and adipose tissue was also examined in mice fed a high-fat diet (HFD) and genetically obese (ob/ob) mice.

RESULTS

Serum LECT2 levels were significantly higher in MetS participants than in non-MetS participants (7.47[3.36-17.14] vs. 3.74[2.61-5.82], P < 0.001). Particularly, serum LECT2 levels were significantly elevated in participants with hypertension, central obesity, diabetes mellitus (DM), hyperglycaemia, elevated triglyceride (TG) levels, and reduced high-density lipoprotein cholesterol (HDL-C) levels compared to those in participants without these conditions. Pearson's correlation analysis showed that serum LECT2 levels were positively associated with conventional risk factors in all patients. Moreover, LECT2 was positively associated with the number of MetS components (r = 0.355, P < 0.001), indicating that higher serum LECT2 levels reflected MetS severity. Multivariate regression analysis revealed that a one standard deviation increase in LECT2 was associated with an odds ratio of 1.52 (1.01-2.29, P = 0.044) for MetS prevalence after adjusting for age, sex, body mass index, waist circumference, smoking status, white blood cell count, fasting blood glucose, TG, total cholesterol, HDL-C, blood urea nitrogen, and alanine aminotransferase. Receiver operating characteristic curve analysis confirmed the strong predictive ability of serum LECT2 levels for MetS. The optimum serum LECT2 cut-off value was 9.05. The area under the curve was 0.73 (95% confidence interval 0.68-0.78, P < 0.001), with a sensitivity and specificity of 45.71% and 95.61%, respectively. Additionally, LECT2 expression levels were higher at baseline and dramatically enhanced in metabolic organs (e.g. the liver) and adipose tissue in HFD-induced obese mice and ob/ob mice.

CONCLUSIONS

Increased LECT2 levels were significantly and independently associated with the presence and severity of MetS, indicating that LECT2 could be used as a novel biomarker and clinical predictor of MetS.

Identification of crosstalk genes relating to ECM-receptor interaction genes in MASH and DN using bioinformatics and machine learning

This study aimed to identify genes shared by metabolic dysfunction-associated fatty liver disease (MASH) and diabetic nephropathy (DN) and the effect of extracellular matrix (ECM) receptor interaction genes on them. Datasets with MASH and DN were downloaded from the Gene Expression Omnibus (GEO) database. Pearson's coefficients assessed the correlation between ECM-receptor interaction genes and cross talk genes. The coexpression network of co-expression pairs (CP) genes was integrated with its protein-protein interaction (PPI) network, and machine learning was employed to identify essential disease-representing genes. Finally, immuno-penetration analysis was performed on the MASH and DN gene datasets using the CIBERSORT algorithm to evaluate the plausibility of these genes in diseases. We found 19 key CP genes. Fos proto-oncogene (FOS), belonging to the IL-17 signalling pathway, showed greater centrality PPI network; Hyaluronan Mediated Motility Receptor (HMMR), belonging to ECM-receptor interaction genes, showed most critical in the co-expression network map of 19 CP genes; Forkhead Box C1 (FOXC1), like FOS, showed a high ability to predict disease in XGBoost analysis. Further immune infiltration showed a clear positive correlation between FOS/FOXC1 and mast cells that secrete IL-17 during inflammation. Combining the results of previous studies, we suggest a FOS/FOXC1/HMMR regulatory axis in MASH and DN may be associated with mast cells in the acting IL-17 signalling pathway. Extracellular HMMR may regulate the IL-17 pathway represented by FOS through the Mitogen-Activated Protein Kinase 1 (ERK) or PI3K-Akt-mTOR pathway. HMMR may serve as a signalling carrier between MASH and DN and could be targeted for therapeutic development.

PFOS-elicited metabolic perturbation in liver and fatty acid metabolites in testis of adult mice

Introduction

Multiple factors can contribute to sub-fecundity, including genetics, lifestyle, and environmental contaminants. PFASs are characterized as "forever chemicals" due to their ubiquitous contamination and their persistence in the environment, wildlife, and humans. Numerous studies have demonstrated that PFAS exposure adversely affects multiple bodily functions, including liver metabolism and gonadal function. It is unclear, however, how the disruption of hepatic fatty acid metabolism affects testicular function.

Methods

In this study, male mice were administered 0.3 and 3 μg/g body weight of PFOS for 21 days.

Results

Our data showed that PFOS exposure caused hepatic steatosis, as evidenced by significant increases in triglyceride levels, expression of ATP-citrate lyase, and fatty acid synthase, as well as fasting insulin levels. PFOS perturbed the expression levels of hepatokines, of which fibroblast growth factor-21 (Fgf-21), leukocyte cell-derived chemotaxin-2 (Lect-2), and retinol-binding protein-4 (Rbp-4) were significantly reduced, whereas angiopoietin-like 4 (Angptl4) was noticeably increased. While Rbp-4 and Fgf-21 are known to contribute to spermatogenesis and testosterone synthesis. In PFOS-exposed groups, testicular ATP, and testosterone decreased significantly with a significant increase in the expression of peroxisome proliferator-activated receptor-coactivator 1α. Mass spectrophotometry imaging revealed the localization of PFOS in testes, along with significant increases in fatty acid metabolites. These included arachidonic acid, dihomo-α-linolenic acid, dihomo-γ-linolenic acid, oxidized ceramide, diacylglycerol, phosphatidylcholine, and phosphatidylethanolamine, which are associated with inflammation and post-testicular causes of infertility.

Discussion

This study revealed potential links between PFOS-elicited changes in hepatic metabolism and their impacts on testicular biology. This study provides insights into alternative targets elicited by PFOS that can be used to develop diagnostic and therapeutic strategies for improving testicular dysfunction.

Highlighting the idea of exerkines in the management of cancer patients with cachexia: novel insights and a critical review

BACKGROUND

Exerkines are all peptides, metabolites, and nucleic acids released into the bloodstream during and after physical exercise. Exerkines liberated from skeletal muscle (myokines), the heart (cardiokines), liver (hepatokines), white adipose tissue (adipokines), brown adipose tissue (batokines), and neurons (neurokines) may benefit health and wellbeing. Cancer-related cachexia is a highly prevalent disorder characterized by weight loss with specific skeletal muscle and adipose tissue loss. Many studies have sought to provide exercise strategies for managing cachexia, focusing on musculoskeletal tissue changes. Therefore, understanding the responses of musculoskeletal and other tissue exerkines to acute and chronic exercise may provide novel insight and recommendations for physical training to counteract cancer-related cachexia.

METHODS

For the purpose of conducting this study review, we made efforts to gather relevant studies and thoroughly discuss them to create a comprehensive overview. To achieve this, we conducted searches using appropriate keywords in various databases. Studies that were deemed irrelevant to the current research, not available in English, or lacking full-text access were excluded. Nevertheless, it is important to acknowledge the limited amount of research conducted in this specific field.

RESULTS

In order to obtain a comprehensive understanding of the findings, we prioritized human studies in order to obtain results that closely align with the scope of the present study. However, in instances where human studies were limited or additional analysis was required to draw more robust conclusions, we also incorporated animal studies. Finally, 295 studies, discussed in this review.

CONCLUSION

Our understanding of the underlying physiological mechanisms related to the significance of investigating exerkines in cancer cachexia is currently quite basic. Nonetheless, this demonstrated that resistance and aerobic exercise can contribute to the reduction and control of the disease in individuals with cancer cachexia, as well as in survivors, by inducing changes in exerkines.

The Role of Organokines in Obesity and Type 2 Diabetes and Their Functions as Molecular Transducers of Nutrition and Exercise

Maintaining systemic homeostasis requires the coordination of different organs and tissues in the body. Our bodies rely on complex inter-organ communications to adapt to perturbations or changes in metabolic homeostasis. Consequently, the liver, muscle, and adipose tissues produce and secrete specific organokines such as hepatokines, myokines, and adipokines in response to nutritional and environmental stimuli. Emerging evidence suggests that dysregulation of the interplay of organokines between organs is associated with the pathophysiology of obesity and type 2 diabetes (T2D). Strategies aimed at remodeling organokines may be effective therapeutic interventions. Diet modification and exercise have been established as the first-line therapeutic intervention to prevent or treat metabolic diseases. This review summarizes the current knowledge on organokines secreted by the liver, muscle, and adipose tissues in obesity and T2D. Additionally, we highlighted the effects of diet/nutrition and exercise on the remodeling of organokines in obesity and T2D. Specifically, we investigated the ameliorative effects of caloric restriction, selective nutrients including ω3 PUFAs, selenium, vitamins, and metabolites of vitamins, and acute/chronic exercise on the dysregulation of organokines in obesity and T2D. Finally, this study dissected the underlying molecular mechanisms by which nutrition and exercise regulate the expression and secretion of organokines in specific tissues.

The regulatory role of metabolic organ-secreted factors in the nonalcoholic fatty liver disease and cardiovascular disease

Nonalcoholic fatty liver disease (NAFLD) is a chronic metabolic disease characterized by an excessive accumulation of fat in the liver, which is becoming a major global health problem, affecting about a quarter of the population. In the past decade, mounting studies have found that 25%-40% of NAFLD patients have cardiovascular disease (CVD), and CVD is one of the leading causes of death in these subjects. However, it has not attracted enough awareness and emphasis from clinicians, and the underlying mechanisms of CVD in NAFLD patients remain unclear. Available research reveals that inflammation, insulin resistance, oxidative stress, and glucose and lipid metabolism disorders play indispensable roles in the pathogenesis of CVD in NAFLD. Notably, emerging evidence indicates that metabolic organ-secreted factors, including hepatokines, adipokines, cytokines, extracellular vesicles, and gut-derived factors, are also involved in the occurrence and development of metabolic disease and CVD. Nevertheless, few studies have focused on the role of metabolic organ-secreted factors in NAFLD and CVD. Therefore, in this review, we summarize the relationship between metabolic organ-secreted factors and NAFLD as well as CVD, which is beneficial for clinicians to comprehensive and detailed understanding of the association between both diseases and strengthen management to improve adverse cardiovascular prognosis and survival.

The emerging roles of leukocyte cell-derived chemotaxin-2 in immune diseases: From mechanisms to therapeutic potential

Leukocyte cell-derived chemotaxin-2 (LECT2, also named ChM-II), initially identified as a chemokine mediating neutrophil migration, is a multifunctional secreted factor involved in diverse physiological and pathological processes. The high sequence similarity of LECT2 among different vertebrates makes it possible to explore its functions by using comparative biology. LECT2 is associated with many immune processes and immune-related diseases via its binding to cell surface receptors such as CD209a, Tie1, and Met in various cell types. In addition, the misfolding LECT2 leads to the amyloidosis of several crucial tissues (kidney, liver, and lung, etc.) by inducing the formation of insoluble fibrils. However, the mechanisms of LECT2-mediated diverse immune pathogenic conditions in various tissues remain to be fully elucidated due to the functional and signaling heterogeneity. Here, we provide a comprehensive summary of the structure, the “double-edged sword” function, and the extensive signaling pathways of LECT2 in immune diseases, as well as the potential applications of LECT2 in therapeutic interventions in preclinical or clinical trials. This review provides an integrated perspective on the current understanding of how LECT2 is associated with immune diseases, with the aim of facilitating the development of drugs or probes against LECT2 for the theranostics of immune-related diseases.

Tandem mass tag-based quantitative proteomic profiling identifies candidate serum biomarkers of drug-induced liver injury in humans

Diagnosis of drug-induced liver injury (DILI) and its distinction from other liver diseases are significant challenges in drug development and clinical practice. Here, we identify, confirm, and replicate the biomarker performance characteristics of candidate proteins in patients with DILI at onset (DO; n = 133) and follow-up (n = 120), acute non-DILI at onset (NDO; n = 63) and follow-up (n = 42), and healthy volunteers (HV; n = 104). Area under the receiver operating characteristic curve (AUC) for cytoplasmic aconitate hydratase, argininosuccinate synthase, carbamoylphosphate synthase, fumarylacetoacetase, fructose-1,6-bisphosphatase 1 (FBP1) across cohorts achieved near complete separation (range: 0.94-0.99) of DO and HV. In addition, we show that FBP1, alone or in combination with glutathione S-transferase A1 and leukocyte cell-derived chemotaxin 2, could potentially assist in clinical diagnosis by distinguishing NDO from DO (AUC range: 0.65-0.78), but further technical and clinical validation of these candidate biomarkers is needed.

MAPK Signaling Pathways in Hepatic Ischemia/Reperfusion Injury

The mitogen-activated protein kinase signaling pathway can be activated by a variety of growth factors, cytokines, and hormones, and mediates numerous intracellular signals related to cellular activities, including cell proliferation, motility, and differentiation. It has been widely studied in the occurrence and development of inflammation and tumor. Hepatic ischemia-reperfusion injury (HIRI) is a common pathophysiological phenomenon that occurs in surgical procedures such as lobectomy and liver transplantation, which is characterized by severe inflammatory reaction after ischemia and reperfusion. In this review, we mainly discuss the role of p38, ERK1/2, JNK in MAPK family and TAK1 and ASK1 in MAPKKK family in HIRI, and try to find an effective treatment for HIRI.

Targeting endoplasmic reticulum stress-the responder to lipotoxicity and modulator of non-alcoholic fatty liver diseases

INTRODUCTION

Endoplasmic reticulum (ER) stress occurs with aberrant lipid accumulation and resultant adverse effects and widely exists in nonalcoholic fatty liver disease (NAFLD). It triggers the unfolded protein response (UPR) to restore ER homeostasis and actively participates in NAFLD pathological processes, including hepatic steatosis, inflammation, hepatocyte death, and fibrosis. Such acknowledges drive the discovery of novel NAFLD biomarker and therapeutic targets and the development of ER-stress targeted NAFLD drugs.

AREAS COVERED

This article discusses and updates the role of ER stress and UPR in NAFLD, the underlying action mechanism, and especially their full participation in NAFLD pathophysiology. It characterizes key molecular targets useful for the prevention and treatment of NAFLD and highlights the recent ER stress-targeted therapeutic strategies for NAFLD.

EXPERT OPINION

Targeting ER Stress is a valuable and promising strategy for NAFLD treatment, but its smooth translation into clinical application still requires better clarification of the different UPR patterns in diverse NAFLD physiological states. Further understanding of the distinct effects of these various patterns on NAFLD, the thresholds deciding their final impacts, and their actions via non-liver tissues and cells would be of great help to develop a precise and effective therapy for NAFLD. [Figure: see text].

The Potential of Exerkines in Women's COVID-19: A New Idea for a Better and More Accurate Understanding of the Mechanisms behind Physical Exercise

The benefits of physical exercise are well-known, but there are still many questions regarding COVID-19. Chow et al.'s 2022 study, titled Exerkines and Disease, showed that a special focus on exerkines can help to better understand the underlying mechanisms of physical exercise and disease. Exerkines are a group of promising molecules that may underlie the beneficial effects of physical exercise in diseases. The idea of exerkines is to understand the effects of physical exercise on diseases better. Exerkines have a high potential for the treatment of diseases and, considering that, there is still no study of the importance of exerkines on the most dangerous disease in the world in recent years, COVID-19. This raises the fundamental question of whether exerkines have the potential to manage COVID-19. Most of the studies focused on the general changes in physical exercise in patients with COVID-19, both during the illness and after discharge from the hospital, and did not investigate the basic differences. A unique look at the management of COVID-19 by exerkines, especially in obese and overweight women who experience high severity of COVID-19 and whose recovery period is long after discharge from the hospital, can help to understand the basic mechanisms. In this review, we explore the potential of exerkines in COVID-19 by practicing physical exercise to provide compelling practice recommendations with new insights.

Regulatory Networks, Management Approaches, and Emerging Treatments of Nonalcoholic Fatty Liver Disease

The pathogenesis of NAFLD is complex and diverse, involving multiple signaling pathways and cytokines from various organs. Hepatokines, stellakines, adipokines, and myokines secreted by hepatocytes, hepatic stellate cells, adipose tissue, and myocytes play an important role in the occurrence and development of nonalcoholic fatty liver disease (NAFLD). The nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) contributes to the progression of NAFLD by mediating liver inflammation, immune response, hepatocyte death, and later compensatory proliferation. In this review, we first discuss the crosstalk and interaction between hepatokines, stellakines, adipokines, and myokines and NF-κB in NAFLD. The characterization of the crosstalk of NF-κB with these factors will provide a better understanding of the molecular mechanisms involved in the progression of NAFLD. In addition, we examine new expert management opinions for NAFLD and explore the therapeutic potential of silymarin in NAFLD/NASH.

Regulatory network and interplay of hepatokines, stellakines, myokines and adipokines in nonalcoholic fatty liver diseases and nonalcoholic steatohepatitis

Fatty liver disease is a spectrum of liver pathologies ranging from simple hepatic steatosis to non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), and culminating with the development of cirrhosis or hepatocellular carcinoma (HCC). The pathogenesis of NAFLD is complex and diverse, and there is a lack of effective treatment measures. In this review, we address hepatokines identified in the pathogenesis of NAFLD and NASH, including the signaling of FXR/RXR, PPARα/RXRα, adipogenesis, hepatic stellate cell activation/liver fibrosis, AMPK/NF-κB, and type 2 diabetes. We also highlight the interaction between hepatokines, and cytokines or peptides secreted from muscle (myokines), adipose tissue (adipokines), and hepatic stellate cells (stellakines) in response to certain nutritional and physical activity. Cytokines exert autocrine, paracrine, or endocrine effects on the pathogenesis of NAFLD and NASH. Characterizing signaling pathways and crosstalk amongst muscle, adipose tissue, hepatic stellate cells and other liver cells will enhance our understanding of interorgan communication and potentially serve to accelerate the development of treatments for NAFLD and NASH.

Prognostic value of LECT2 and relevance to immune infiltration in hepatocellular carcinoma

Background: Previous studies have shown that Leukocyte cell-derived chemotaxin2 (LECT2) is associated with the development of HCC. However, there are still no studies with a comprehensive analysis of the role of LECT2 in hepatocellular carcinoma (HCC).

Methods: TCGA data sets were used to analyze the expression of LECT2 in HCC. In addition, the prognostic value of LECT2 in HCC was also investigated. DriverDBv3 was used to analyze the Mutation, CNV, and methylation profiles of LECT2. And, validated by immunohistochemistry in 72 HCC samples. The prognostic value of LECT2 and the correlation with clinicopathological features were analyzed. The GO/KEGG enrichment analysis of LECT2 co-expression and gene set enrichment analysis (GSEA) was performed using the R software package. The PPI interaction network was constructed by Search Tool for the Retrieval of Interacting Genes (STRING) database. Immune infiltration was estimated by the XCELL, TIMER, QUANTISEQ, MCPCOUNTER, EPIC, CIBERSORT abs and CIBERSORT algorithms, and Spearman was used to analyzing their correlation with LECT2. Moreover, we analyzed the correlation of LECT2 expression with immune checkpoint molecules and HLA genes. Finally, we analyzed the IC50 values of six chemotherapeutic drugs by the pRRophetic package.

Results: Reduced LECT2 expression levels found in HCC patients. Moreover, decreased levels of LECT2 were associated with poor overall survival, disease-free survival, disease-specific survival, and progression-free survival. Besides, methylation was significantly associated with LECT2 expression. The functional enrichment analysis revealed that LECT2 may affect HCC progression through various pathways such as JAK/STAT signaling pathway, cell cycle, and pathways in cancer. Additionally, the results showed that LECT2 expression was negatively correlated with immune infiltration of B cells, Neutrophil, Monocyte, Cancer-associated fibroblast, and Myeloid dendritic cell, and positively correlated with T cell CD8⁺ naive, Endothelial cell, and Hematopoietic stem cell. LECT2 expression was negatively correlated with multiple immune checkpoint molecules and HLA genes. Chemosensitivity analysis showed that chemosensitivity was lower in the LECT2 high expression group. We validated the prognostic value of LECT2 and analysis of clinicopathological features showed a lower TNM stage in the group with high expression of LECT2.

Conclusion: Low expression of LECT2 in HCC is closely associated with poor prognosis, LECT2 may have potential clinical applications due to its unique immunological effects.

Leukocyte cell-derived chemotaxin 2 regulates epithelial-mesenchymal transition and cancer stemness in hepatocellular carcinoma

Leukocyte cell-derived chemotaxin 2 (LECT2) acts as a tumor suppressor in hepatocellular carcinoma (HCC). However, the antineoplastic mechanism of LECT2, especially its influence on hepatic cancer stem cells (CSCs), remains largely unknown. In The Cancer Genome Atlas cohort, LECT2 mRNA expression was shown to be associated with stage, grade, recurrence, and overall survival in human HCC patients, and LECT2 expression was downregulated in hepatoma tissues compared with the adjacent nontumoral liver. Here, we show by immunofluorescence and immunoblot analyses that LECT2 was expressed at lower levels in tumors and in poorly differentiated HCC cell lines. Using functional assays, we also found LECT2 was capable of suppressing oncogenic behaviors such as cell proliferation, anchorage-independent growth, migration, invasiveness, and epithelial-mesenchymal transition in hepatoma cells. Moreover, we show exogenous LECT2 treatment inhibited CSC functions such as tumor sphere formation and drug efflux. Simultaneously, hepatic CSC marker expression was also downregulated, including expression of CD133 and CD44. This was supported by infection with adenovirus encoding LECT2 (Ad-LECT2) in HCC cells. Furthermore, in animal experiments, Ad-LECT2 gene therapy showed potent efficacy in treating HCC. We demonstrate LECT2 overexpression significantly promoted cell apoptosis and reduced neovascularization/CSC expansion in rat hepatoma tissues. Mechanistically, we showed using immunoblot and immunofluorescence analyses that LECT2 inhibited β-catenin signaling via the suppression of the hepatocyte growth factor/c-MET axis to diminish CSC properties in HCC cells. In summary, we reveal novel functions of LECT2 in the suppression of hepatic CSCs, suggesting a potential alternative strategy for HCC therapy.

LECT2: A pleiotropic and promising hepatokine, from bench to bedside

LECT2 (leucocyte cell-derived chemotaxin 2) is a 16-kDa protein mainly produced by hepatocytes. It was first isolated in PHA-activated human T-cell leukaemia SKW-3 cells and originally identified as a novel neutrophil chemotactic factor. However, many lines of studies suggested that LECT2 was a pleiotropic protein, it not only functioned as a cytokine to exhibit chemotactic property, but also played multifunctional roles in some physiological conditions and pathological abnormalities, involving liver regeneration, neuronal development, HSC(haematopoietic stem cells) homeostasis, liver injury, liver fibrosis, hepatocellular carcinoma, metabolic disorders, inflammatory arthritides, systemic sepsis and systemic amyloidosis. Among the above studies, it was discovered that LECT2 could be a promising molecular biomarker and therapeutic target. This review summarizes LECT2-related receptors and pathways, basic and clinical researches, primarily in mice and human, for a better comprehension and management of these diseases in the future.

LECT2 Is a Novel Antibacterial Protein in Vertebrates

In vertebrates, leukocyte-derived chemotaxin-2 (LECT2) is an important immunoregulator with conserved chemotactic and phagocytosis-stimulating activities to leukocytes during bacterial infection. However, whether LECT2 possesses direct antibacterial activity remains unknown. In this article, we show that, unlike tetrapods with a single LECT2 gene, two LECT2 genes exist in teleost fish, named LECT2-a and LECT2-b Using grass carp as a research model, we found that the expression pattern of grass carp LECT2-a (gcLECT2-a) is more similar to that of LECT2 in tetrapods, while gcLECT2-b has evolved to be highly expressed in mucosal immune organs, including the intestine and skin. Interestingly, we found that gcLECT2-b, with conserved chemotactic and phagocytosis-stimulating activities, can also kill Gram-negative and Gram-positive bacteria directly in a membrane-dependent and a non-membrane-dependent manner, respectively. Moreover, gcLECT2-b could prevent the adherence of bacteria to epithelial cells through agglutination by targeting peptidoglycan and lipoteichoic acid. Further study revealed that gcLECT2-b can protect grass carp from Aeromonas hydrophila infection in vivo, because it significantly reduces intestinal necrosis and tissue bacterial load. More importantly, we found that LECT2 from representative tetrapods, except human, also possesses direct antibacterial activities, indicating that the direct antibacterial property of LECT2 is generally conserved in vertebrates. Taken together, to our knowledge, our study discovered a novel function of LECT2 in the antibacterial immunity of vertebrates, especially teleost fish, greatly enhancing our knowledge of this important molecule.

Hepatic PTEN Signaling Regulates Systemic Metabolic Homeostasis through Hepatokines-Mediated Liver-to-Peripheral Organs Crosstalk

Liver-derived circulating factors deeply affect the metabolism of distal organs. Herein, we took advantage of the hepatocyte-specific PTEN knockout mice (LPTENKO), a model of hepatic steatosis associated with increased muscle insulin sensitivity and decreased adiposity, to identify potential secreted hepatic factors improving metabolic homeostasis. Our results indicated that protein factors, rather than specific metabolites, released by PTEN-deficient hepatocytes trigger an improved muscle insulin sensitivity and a decreased adiposity in LPTENKO. In this regard, a proteomic analysis of conditioned media from PTEN-deficient primary hepatocytes identified seven hepatokines whose expression/secretion was deregulated. Distinct expression patterns of these hepatokines were observed in hepatic tissues from human/mouse with NAFLD. The expression of specific factors was regulated by the PTEN/PI3K, PPAR or AMPK signaling pathways and/or modulated by classical antidiabetic drugs. Finally, loss-of-function studies identified FGF21 and the triad AHSG, ANGPTL4 and LECT2 as key regulators of insulin sensitivity in muscle cells and in adipocytes biogenesis, respectively. These data indicate that hepatic PTEN deficiency and steatosis alter the expression/secretion of hepatokines regulating insulin sensitivity in muscles and the lipid metabolism in adipose tissue. These hepatokines could represent potential therapeutic targets to treat obesity and insulin resistance.

Hepatoprotective effects of gemigliptin and empagliflozin in a murine model of diet-induced non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) includes a broad spectrum of liver diseases characterized by steatosis, inflammation, and fibrosis. This study aimed to investigate the potential of dipeptidyl peptidase-4 inhibitors and sodium-glucose cotransporter 2 inhibitors in alleviating the progression of NAFLD. The NAFLD model was generated by feeding male C57BL/6J mice a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) for 7 weeks. After 2 weeks of CDAHFD feeding, the NAFLD model mice were assigned to four groups, namely (ⅰ) VEHICLE, (ⅱ) gemigliptin (GEMI), (ⅲ) empagliflozin (EMPA), and (ⅳ) GEMI + EMPA. For the next 5 weeks, mice received the vehicle or the drug based upon the group to which they belonged. Thereafter, the triglyceride concentration, extent of fibrosis, and the expression of genes encoding inflammatory cytokines, chemokines, and antioxidant enzymes were analyzed in the livers of mice. The NAFLD activity score and hepatic fibrosis grade were assessed via hematoxylin and eosin and Sirius Red staining of the liver tissue samples. All mice belonging to the GEMI, EMPA, and GEMI + EMPA groups showed improvements in the accumulation of liver triglycerides and the expression of inflammatory cytokines and chemokines. Additionally, the oxidative stress was reduced due to inhibition of the c-Jun N-terminal kinase pathway and upregulation of the antioxidant enzymes. Furthermore, in these three groups, the galectin-3 and interleukin 33-induced activity of tumor necrosis factor-α was inhibited, thereby preventing the progression of liver fibrosis. These findings suggest that the GEMI, EMPA, and GEMI + EMPA treatments ameliorate hepatic steatosis, inflammation, oxidative stress, and fibrosis in CDAHFD-induced NAFLD mouse models.

Non-Alcoholic Steatohepatitis (NASH) and Organokines: What Is Now and What Will Be in the Future

Non-alcoholic steatohepatitis (NASH) is characterized by steatosis, lobular inflammation, and enlargement of the diameter of hepatocytes (ballooning hepatocytes), with or without fibrosis. It affects 20% of patients with non-alcoholic fatty liver disease (NAFLD). Due to liver dysfunction and the numerous metabolic changes that commonly accompany the condition (obesity, insulin resistance, type 2 diabetes, and metabolic syndrome), the secretion of organokines is modified, which may contribute to the pathogenesis or progression of the disease. In this sense, this study aimed to perform a review of the role of organokines in NASH. Thus, by combining descriptors such as NASH, organokines, oxidative stress, inflammation, insulin resistance, and dyslipidemia, a search was carried out in the EMBASE, MEDLINE-PubMed, and Cochrane databases of articles published in the last ten years. Insulin resistance, inflammation and mitochondrial dysfunction, fructose, and intestinal microbiota were factors identified as participating in the genesis and progression of NASH. Changes in the pattern of organokines secretion (adipokines, myokines, hepatokines, and osteokines) directly or indirectly contribute to aggravating the condition or compromise homeostasis. Thus, further studies involving skeletal muscle, adipose, bone, and liver tissue as endocrine organs are essential to better understand the modulation of organokines involved in the pathogenesis of NASH to advance in the treatment of this disease.

TGF-β1-Mediated Leukocyte Cell-Derived Chemotaxin 2 Is Associated With Liver Fibrosis in Biliary Atresia

OBJECTIVE

Biliary atresia (BA) presents as a severe infantile cholangiopathy disease, characterized by progressive liver fibrosis and the resulting poor prognosis. Leukocyte cell-derived chemotaxin 2 (LECT2) was proposed as the key gene associated with hepatic fibrosis in BA, but the molecular mechanism is unclear. This study aims to investigate the function of LECT2 in BA.

METHODS

A total of 53 patients were enrolled in this study; 36 patients with BA, and 17 control patients with cholestasis, including congenital biliary dilations, biliary hypoplasia, and inspissated bile syndrome. The role of LECT2 in BA was analyzed using histological and cytological tests. The correlation between LECT2 and infiltrating immune cells was further analyzed by bioinformatics. The analyses were conducted using correlational analyses and ROC curves.

RESULTS

LECT2 was highly expressed in infants with BA and positively related with fibrosis (0.1644 ± 0.0608 vs. 0.0779 ± 0.0053, p < 0.0001; r _s = 0.85, p < 0.0001). Serum levels of LECT2 showed high distinguishing features for patients with BA having an AUC of 0.95 (95% CI: 0.90-1.00). CD163 was highly expressed in the aggravation of fibrosis (0.158 ± 0.062 vs. 0.29 ± 0.078, p < 0.0001), and the expression of LECT2 was positively correlated with the accumulation of CD163⁺ macrophages (r = 0.48, p = 0.003). The bioinformatic analysis also showed that LECT2 was positively correlated with macrophage M2 (r = 0.34, p = 0.03). TGF-β1 and CD163 colocalized to the portal area in the livers of patients with BA. Moreover, TGF-β1 upregulated the expression of LECT2.

CONCLUSION

LECT2 is highly expressed in both BA liver tissue and serum, and serum LECT2 is a potential diagnostic biomarker of BA. Meanwhile, TGF-β1 is secreted by macrophages to regulate LECT2 associated with BA liver fibrosis.

Endoplasmic reticulum stress increases LECT2 expression via ATF4

Non-alcoholic fatty liver disease (NAFLD) is frequently associated with obesity, insulin resistance, and endoplasmic reticulum (ER) stress. Elevated circulating levels of the hepatokine leukocyte cell-derived chemotaxin-2 (LECT2) have also been noted in NAFLD; however, the mechanism underlying this association is unclear. To investigate a possible link between ER stress/unfolded protein response (UPR) signaling and LECT2 secretion, HepG2 cells were incubated with ER stress inducers with or without an ER stress-reducing chemical chaperone. Additionally, UPR pathway genes were knocked down and overexpressed, and a ChIP assay was performed. In diet-induced obese mice, hepatic expression of LECT2 and activating transcription factor 4 (ATF4) was measured. In HepG2 cells, LECT2 expression was increased by ER stressors, an effect blocked by the chemical chaperone. Among UPR pathway proteins, only knockdown of ATF4 suppressed ER stress-induced LECT2 expression, while overexpression of ATF4 enhanced LECT2 expression. The ChIP assay revealed that ATF4 binds to three putative binding sites on the LECT2 promoter and binding is promoted by an ER stress inducer. In steatotic livers of obese mice, LECT2 and ATF4 expression was concomitantly elevated. Our data indicate that activation of ER stress/UPR signaling induces LECT2 expression in steatotic liver; specifically, ATF4 appears to mediate upregulation of LECT2 transcription.

Hepatokines and Non-Alcoholic Fatty Liver Disease: Linking Liver Pathophysiology to Metabolism

The liver plays a key role in maintaining energy homeostasis by sensing and responding to changes in nutrient status under various metabolic conditions. Recently highlighted as a major endocrine organ, the contribution of the liver to systemic glucose and lipid metabolism is primarily attributed to signaling crosstalk between multiple organs via hepatic hormones, cytokines, and hepatokines. Hepatokines are hormone-like proteins secreted by hepatocytes, and a number of these have been associated with extra-hepatic metabolic regulation. Mounting evidence has revealed that the secretory profiles of hepatokines are significantly altered in non-alcoholic fatty liver disease (NAFLD), the most common hepatic manifestation, which frequently precedes other metabolic disorders, including insulin resistance and type 2 diabetes. Therefore, deciphering the mechanism of hepatokine-mediated inter-organ communication is essential for understanding the complex metabolic network between tissues, as well as for the identification of novel diagnostic and/or therapeutic targets in metabolic disease. In this review, we describe the hepatokine-driven inter-organ crosstalk in the context of liver pathophysiology, with a particular focus on NAFLD progression. Moreover, we summarize key hepatokines and their molecular mechanisms of metabolic control in non-hepatic tissues, discussing their potential as novel biomarkers and therapeutic targets in the treatment of metabolic diseases.

LECT-2 amyloidosis: what do we know?

Amyloidosis is a rare group of diseases characterized by abnormal folding of proteins and extracellular deposition of insoluble fibrils. It can be localized to one organ system or can have systemic involvement. The kidney is the most common organ to be involved in systemic amyloidosis often leading to renal failure and the nephrotic syndrome. The two most common types of renal amyloidosis are immunoglobulin light chain-derived amyloidosis (AL) and reactive amyloidosis (AA). A novel form of amyloidosis (ALECT2) derived from leukocyte chemotactic factor 2 (LECT-2) and primarily involving the kidneys was first described by Benson et al in 2008. The liver was subsequently identified as the second most common organ involved in ALECT2 amyloidosis. LECT-2 is a unique protein that can form amyloid deposits even in its unmutated form. Patients with ALECT2 present with minimal proteinuria in contrast to other forms of amyloidosis especially AL and AA. They may present with slightly elevated serum creatinine. Nephrotic syndrome and hematuria are rare. ALECT2 can be found in association with other types of amyloidosis as well as malignancies or autoimmune diseases. ALECT2 may be confused with amyloidosis associated with light and heavy chain monoclonal gammopathy if the immunofluorescence is positive with anti-light chain and anti-AA sera. The other organs involved are the duodenum, adrenal gland, spleen, prostate, gall bladder, pancreas, small bowel, parathyroid gland, heart, and pulmonary alveolar septa, but consistently uninvolved organs included brain and fibroadipose tissue. A renal biopsy along with characteristic features found on immunohistochemistry and mass spectrometry is diagnostic of ALECT2. ALECT2 should be suspected when all markers for AL and AA are negative. Proper diagnosis of ALECT2 can determine need for supportive care versus more aggressive interventions.

LECT2, A Novel and Direct Biomarker of Liver Fibrosis in Patients With CHB

Chronic hepatitis B (CHB) patients with severe liver fibrosis would be more likely to progress to a poorer prognosis. Treatment is considered once the liver fibrosis reaches significant liver fibrosis (≥S2). Leukocyte cell-derived chemotaxin-2 (LECT2) has been shown to contribute to liver fibrosis progression. No research has focused on the role of LECT2 in liver fibrosis in CHB patients. This study enrolled 227 CHB patients and divided them into the training group (n = 147) and validation group (n = 80), respectively. The expression of LECT2 in serum, protein and mRNA of the human liver tissues was detected to analyze the possible associations between LECT2 and liver fibrosis. A receiver operating characteristic curve (ROC) was used to estimate the efficacy of LECT2 for predicting liver fibrosis. The data showed that there was a positive relationship between LECT2 and the progression of liver fibrosis. In the training group, LECT2 was demonstrated to have better effectiveness than APRI and FIB-4. The AUC was 0.861, 0.698, and 0.734 for significant liver fibrosis, and 0.855, 0.769, and 0.752 for advanced liver fibrosis. Besides, the efficacy of LECT2 in different statuses of patients with CHB was examined and the effectiveness of LECT2 had also been confirmed in the validation group. All the results confirmed that LECT2 could act as a perfect predictor and thus offers a novel and direct biomarker to estimate liver fibrosis more accurately.

Novel ACE2 protein interactions relevant to COVID-19 predicted by evolutionary rate correlations

Angiotensin-converting enzyme 2 (ACE2) is the cell receptor that the coronavirus SARS-CoV-2 binds to and uses to enter and infect human cells. COVID-19, the pandemic disease caused by the coronavirus, involves diverse pathologies beyond those of a respiratory disease, including micro-thrombosis (micro-clotting), cytokine storms, and inflammatory responses affecting many organ systems. Longer-term chronic illness can persist for many months, often well after the pathogen is no longer detected. A better understanding of the proteins that ACE2 interacts with can reveal information relevant to these disease manifestations and possible avenues for treatment. We have undertaken an approach to predict candidate ACE2 interacting proteins which uses evolutionary inference to identify a set of mammalian proteins that “coevolve” with ACE2. The approach, called evolutionary rate correlation (ERC), detects proteins that show highly correlated evolutionary rates during mammalian evolution. Such proteins are candidates for biological interactions with the ACE2 receptor. The approach has uncovered a number of key ACE2 protein interactions of potential relevance to COVID-19 pathologies. Some proteins have previously been reported to be associated with severe COVID-19, but are not currently known to interact with ACE2, while additional predicted novel ACE2 interactors are of potential relevance to the disease. Using reciprocal rankings of protein ERCs, we have identified strongly interconnected ACE2 associated protein networks relevant to COVID-19 pathologies. ACE2 has clear connections to coagulation pathway proteins, such as Coagulation Factor V and fibrinogen components FGA, FGB, and FGG, the latter possibly mediated through ACE2 connections to Clusterin (which clears misfolded extracellular proteins) and GPR141 (whose functions are relatively unknown). ACE2 also connects to proteins involved in cytokine signaling and immune response (e.g. XCR1, IFNAR2 and TLR8), and to Androgen Receptor (AR). The ERC prescreening approach has elucidated possible functions for relatively uncharacterized proteins and possible new functions for well-characterized ones. Suggestions are made for the validation of ERC-predicted ACE2 protein interactions. We propose that ACE2 has novel protein interactions that are disrupted during SARS-CoV-2 infection, contributing to the spectrum of COVID-19 pathologies.

The molecular structure and role of LECT2 or CHM-II in arthritis, cancer, and other diseases

Leukocyte cell-derived chemotaxin-2 (LECT2 or LECT-2), also called chondromodulin II (ChM-II or CHM2) plays a versatile role in various tissues. It was first identified as a chemotactic factor to promote the migration of neutrophils. It was also reported as a hepatokine to regulate glucose metabolism, obesity, and nonalcoholic fatty liver disease. As a secreted factor, LECT2 binds to several cell surface receptors CD209a, Tie1, and Met to regulate inflammatory reaction, fibrogenesis, vascular invasion, and tumor metastasis in various cell types. As an intracellular molecule, it is associated with LECT2-mediated amyloidosis, in which LECT2 misfolding results in insoluble fibrils in multiple tissues such as the kidney, liver, and lung. Recently, LECT2 was found to be associated with the development of rheumatoid arthritis and osteoarthritis, involving the dysregulation of osteoclasts, mesenchymal stem cells, osteoblasts, chondrocytes, and endothelial cells in the bone microenvironment. LECT2 is implicated in the development of cancers, such as hepatocellular carcinoma via MET-mediated PTP1B/Raf1/ERK signaling pathways and is proposed as a biomarker. The mechanisms by which LECT2 regulates diverse pathogenic conditions in various tissues remain to be fully elucidated. Further research to understand the role of LECT2 in a tissue tropism-dependent manner would facilitate the development of LECT2 as a biomarker for diagnosis and therapeutic target.