Kupffer cells in non-alcoholic fatty liver disease: the emerging view

LEADS - a comprehensive human liver-on-a-chip for non-alcoholic steatohepatitis (NASH) drug testing

Metabolic dysfunction associated steatohepatitis (MASH), also known as non-alcoholic steatohepatitis (NASH), is a progressive form of steatotic liver disease (SLD). It is an emerging healthcare threat due its high prevalence, accelerated and non-linear progression, and final culmination as decompensated liver failure and/or hepatocellular carcinoma (HCC). The pathogenesis of NASH is complex with strong ethnic influences and genetic predispositions, underscoring the need for preclinical models that utilize patient-derived cells to enhance our understanding of the disease. Current models face three major limitations: (i) reliance on primary cells with limited reproducibility, high cost, short culture duration and ethical considerations, (ii) failure to recapitulate all key features of NASH, and (iii) inadequate drug testing data and/or data did not correlate with clinical responses. Therefore, there is a pressing need for robust and relevant preclinical models that faithfully recapitulate human NASH, allow generation of patient-specific models and provide quantitative responses for mechanistic studies and drug testing. We have developed a functional liver tissue-on-a-chip by co-culturing human adult liver stem cell (haLSC)-derived hepatobiliary organoids, induced pluripotent stem cell (iPSC)-derived Kupffer cells (iKCs) and iPSC-derived hepatic stellate cells (iHSCs). We simulated the metabolic microenvironment of hyper nutrition and leaky gut by treating the cells with a concoction of free fatty acids (FFAs), fructose, gut-derived lipopolysaccharides (LPS) and a gut-derived metabolite, phenyl acetic acid (PAA). Through optimization of co-culture media and induction regimens, we were able to stably induce steatosis, hepatocellular ballooning, inflammation, and activation of iHSC and fibrosis-all key hallmarks of NASH. Our LEADS (liver-on-a-chip for NASH drug testing) model also recapitulated the pathological types of steatosis and allowed for quantification of the key features via microscopic evaluation and secretome profiling to score for disease severity. Notably, treatment with saroglitazar, pioglitazone, cenicriviroc (CVC), obeticholic acid (OCA) and resmetirom produced responses similar to those observed in clinical trials. Taken together, our LEADS model is the first model developed using patient-derived hepatic stem cells which recapitulated all key features used for comprehensive drug testing, with results matching to clinical responses.

IL-6 Affects Liver Metabolic Abnormalities Caused by Silicon Exposure by Regulating the PKC/YY1 Signaling Pathway

BACKGROUND

This study aims to investigate the impact of coal dust (silicon dioxide) exposure on dyslipidemia and its underlying mechanisms, with a focus on the association between coal dust exposure and hepatic metabolic disorders.

METHODS

Clinical data were collected from 5433 coal mine workers to compare the incidence of dyslipidemia between the dust-exposed group and the non-exposed group. A mouse model of silicon dioxide exposure was established to observe hepatic fat accumulation and pathological changes. Liver tissue sequencing was performed to screen for key differential genes. In vitro cell experiments were utilized to identify the molecular mechanisms underlying hepatocyte metabolic abnormalities induced by silicon dioxide exposure.

RESULTS

Clinical data revealed that 69.2% of miners in the dust-exposed group developed dyslipidemia, which was higher than the 30.7% in the non-exposed group. Animal data showed that silicon dioxide exposure led to hepatic fat deposition and pathological damage, with the degree of injury positively correlated with exposure time. Liver sequencing identified a significant upregulation of the FMO3 (flavin monooxygenase 3) gene in mouse liver tissue following silicon dioxide exposure, accompanied by enhanced inflammatory responses. Mechanistic studies demonstrated that silicon dioxide activates Kupffer cells to secrete IL-6 (interleukin-6), which induces high expression of FMO3 in hepatocytes through the PKC/YY1 signaling pathway, thereby disrupting lipid metabolism.

CONCLUSIONS

Silicon dioxide exposure can promote the upregulation of FMO3 expression in hepatocytes by activating Kupffer cells to release IL-6 via the PKC/YY1 pathway, ultimately leading to lipid metabolic disorders and dyslipidemia.

Visceral Fat, Metabolic Health, and Lifestyle Factors in Obstructive Bronchial Diseases: Insights from Bioelectrical Impedance Analysis

Background/Objectives: This study examines the relationship between visceral fat (VF), metabolic health, and dietary patterns in patients with obstructive bronchial diseases (OBDs) using bioelectrical impedance analysis (BIA). Methods: A total of 75 patients diagnosed with OBD, including chronic obstructive pulmonary disease (COPD) and/or asthma, were assessed for VF levels via BIA. Dietary habits were evaluated using a structured questionnaire to explore their correlation with VF accumulation. Results: The study cohort comprised predominantly male participants (66.7%), with the majority aged between 61 and 70 years (46.7%). Significant gender differences in VF distribution were observed, with 60% of females maintaining normal VF levels (1-9) compared to only 28% of males, while 38% of males exhibited very high VF levels (15-30; p = 0.003). Body mass index (BMI) showed a strong correlation with VF (p < 0.0001), as overweight and obese individuals predominantly displayed elevated VF levels (≥10). Moreover, metabolic syndrome (MS) was present in 66.7% of participants, with these individuals exhibiting significantly higher VF levels compared to those without MS (p = 0.001). Dietary analysis revealed that frequent consumption of fast food (r = 0.717, p < 0.001), carbonated drinks (r = 0.366, p = 0.001), and refined carbohydrates (r = 0.438, p < 0.001) was significantly associated with increased VF accumulation. Conversely, higher intake of water (r = -0.551, p < 0.001), fruits (r = -0.581, p < 0.001), and vegetables (r = -0.482, p < 0.001) correlated with lower VF levels. Lack of physical activity was also strongly linked to VF accumulation (r = 0.481, p < 0.001), further reinforcing the role of lifestyle factors in metabolic health. Conclusions: The findings underscore the significant impact of dietary habits and physical activity on VF accumulation in OBD patients. BMI and MS emerged as critical predictors of VF, while unhealthy dietary patterns and sedentary lifestyles further exacerbated VF deposition. Elevated VF levels were linked to adverse lipid profiles, reinforcing the need for dietary and lifestyle modifications in managing metabolic health among OBD patients. Although no direct association was identified between VF and forced expiratory volume in one second (FEV1), the results highlight the necessity of integrated nutritional and metabolic interventions in the management of chronic respiratory diseases.

Protective effects of Kaempferol on hepatic apoptosis via miR-26a-5p enhancement and regulation of TLR4/NF-κB and PKCδ in a rat model of nonalcoholic fatty liver

This study aimed to evaluate kaempferol's, a dietary flavonoid widely present in plants, potential impact on nonalcoholic fatty liver disease (NAFLD) and its underlying mechanisms. In this study, 60 adult male rats were used and divided into a control group receiving a standard pellet diet, a kaempferol-treated group receiving kaempferol (250 mg/kg), a high-fat diet (HFD) group receiving HFD, and a kaempferol-treated HFD group. At the end of the experiment, the total lipid profile and liver enzymes were assayed in the serum. Additionally, oxidative stress (malondialdehyde and superoxide dismutase), inflammatory (tumor necrosis factor-alpha), apoptotic (caspase 3) markers, and nuclear factor-κB (NF-κB) and Toll-like receptor 4 (TLR4) concentrations were assayed in the liver tissues. Furthermore, miR-26a and PKCδ gene expression and beclin 1 immunohistochemical expression were determined in liver tissues. Our findings revealed that kaempferol significantly protects against the development of NAFLD in rats as well as inflammatory, oxidative, and apoptotic changes in their liver tissues by inhibiting PKCδ and the TLR-4/NF-κB signaling pathway while enhancing autophagy (Beclin 1 expression) via upregulating miR-26a expression. Accordingly, kaempferol holds promise as a complementary medication for the prevention of NAFLD. Nonetheless, more research is needed to fully understand its additional effects on liver tissue and to develop novel medications that activate miR-26a. A link between lipid metabolic abnormalities and miRNAs was demonstrated as upregulating miR-26a-5p by kaempferol mitigates the inflammation, apoptosis, and disrupted autophagy via regulating TLR4/NF-κB pathway and PKC in NAFLD.

Nicotinamide Adenine Dinucleotide Phosphate Oxidases and Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by lipid accumulation in the liver due to an excess in their supplies or an impairment in their management. While some patients remain stable for years, a proportion of them progress up to steatohepatitis (MASH). MASLD links with systemic pathways being associated with metabolic and non-metabolic diseases. Although liver lipid accumulation represents the first hit for MASLD, the pathophysiology of its development and progression to MASH remains not completely understood. Oxidative stress has received particular attention in recent years, as most of the oxidative process occurs in the liver, which is also the target of oxidative stress-induced damage. Growing evidence linked the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX) to the increased liver production of reactive oxygen species up to liver damage and fibrosis. NOX acts both in hepatocytes and in non-parenchymal hepatic cells, contributing to hepatocyte lipotoxicity, impaired hepatic microcirculation, hepatic stellate, and mesenchymal stem cells activation and proliferation. This review aims to summarize the current knowledge on the involvement of oxidative stress in the MASLD-MASH transition, focusing on the role of NOX isoforms, and to suggest targeting NOX as a therapeutic approach in MASLD.

Mechanisms and therapeutic targets of mitochondria in the progression of metabolic dysfunction-associated steatotic liver disease

Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) includes liver disease processes from simple fatty liver to nonalcoholic steatohepatitis, which may progress to liver fibrosis, cirrhosis, and even hepatocellular carcinoma (HCC). As the incidence of HCC derived from viral hepatitis decreases, MASLD has emerged as a significant health threat, driven by lifestyle changes and rising obesity rates among patients. The pathogenesis of MASLD is complex, involving factors such as insulin resistance, gut microbiota imbalance, and genetic and epigenetic factors. In recent years, the role of mitochondrial dysfunction in MASLD has gained significant attention, involving β-oxidation imbalance, oxidative stress increase, mitophagy defects, and mitochondrial DNA (mtDNA) mutations. This article reviews the pathophysiological mechanisms of mitochondrial dysfunction in MASLD, diagnostic methods, and potential therapeutic strategies. By synthesizing current research findings, the review aims to highlight the critical role of mitochondrial dysfunction as a target for future diagnostic and therapeutic interventions. This focus could pave the way for innovative clinical strategies, ultimately improving treatment options and patient prognosis in MASLD.

Gut Microbiota and Metabolic Dysfunction-Associated Steatotic Liver Disease

Background: The gut microbiota constitutes a complex microorganism community that harbors bacteria, viruses, fungi, protozoa, and archaea. The human gut bacterial microbiota has been extensively proven to participate in human metabolism, immunity, and nutrient absorption. Its imbalance, namely "dysbiosis", has been linked to disordered metabolism. Metabolic dysfunction-associated steatotic liver disease (MASLD) is one of the features of deranged human metabolism and is the leading cause of liver cirrhosis and hepatocellular carcinoma. Thus, there is a pathophysiological link between gut dysbiosis and MASLD. Aims and Methods: We aimed to review the literature data on the composition of the human bacterial gut microbiota and its dysbiosis in MASLD and describe the concept of the "gut-liver axis". Moreover, we reviewed the approaches for gut microbiota modulation in MASLD treatment. Results: There is consolidated evidence of particular gut dysbiosis associated with MASLD and its stages. The model explaining the relationship between gut microbiota and the liver has a bidirectional organization, explaining the physiopathology of MASLD. Oxidative stress is one of the keystones in the pathophysiology of MASLD and fibrosis generation. There is promising and consolidated evidence for the efficacy of pre- and probiotics in reversing gut dysbiosis in MASLD patients, with therapeutic effects. Few yet encouraging data on fecal microbiota transplantation (FMT) in MASLD are available in the literature. Conclusions: The gut dysbiosis characteristic of MASLD is a key target in its reversal and treatment via diet, pre/probiotics, and FMT treatment. Oxidative stress modulation remains a promising target for MASLD treatment, prevention, and reversal.

The Foxo1-YAP-Notch1 axis reprograms STING-mediated innate immunity in NASH progression

Innate immune activation is critical for initiating hepatic inflammation during nonalcoholic steatohepatitis (NASH) progression. However, the mechanisms by which immunoregulatory molecules recognize lipogenic, fibrotic, and inflammatory signals remain unclear. Here, we show that high-fat diet (HFD)-induced oxidative stress activates Foxo1, YAP, and Notch1 signaling in hepatic macrophages. Macrophage Foxo1 deficiency (Foxo1M-KO) ameliorated hepatic inflammation, steatosis, and fibrosis, with reduced STING, TBK1, and NF-κB activation in HFD-challenged livers. However, Foxo1 and YAP double knockout (Foxo1/YAPM-DKO) or Foxo1 and Notch1 double knockout (Foxo1/Notch1M-DKO) promoted STING function and exacerbated HFD-induced liver injury. Interestingly, Foxo1M-KO strongly reduced TGF-β1 release from palmitic acid (PA)- and oleic acid (OA)-stimulated Kupffer cells and decreased Col1α1, CCL2, and Timp1 expression but increased MMP1 expression in primary hepatic stellate cells (HSCs) after coculture with Kupffer cells. Notably, PA and OA challenge in Kupffer cells augmented LIMD1 and LATS1 colocalization and interaction, which induced YAP nuclear translocation. Foxo1M-KO activated PGC-1α and increased nuclear YAP activity, modulating mitochondrial biogenesis. Using chromatin immunoprecipitation (ChIP) coupled with massively parallel sequencing (ChIP-Seq) and in situ RNA hybridization, we found that NICD colocalizes with YAP and targets Mb21d1 (cGAS), while YAP functions as a novel coactivator of the NICD, which is crucial for reprogramming STING function in NASH progression. These findings highlight the importance of the macrophage Foxo1-YAP-Notch1 axis as a key molecular regulator that controls lipid metabolism, inflammation, and innate immunity in NASH.

Gpbar-1/cAMP/PKA signaling mitigates macrophage-mediated acute cholestatic liver injury via antagonizing NLRP3-ASC inflammasome

Acute cholestatic liver injury (ACLI) is a disease associated with bile duct obstruction that causes liver inflammation and apoptosis. Although G protein-coupled bile acid receptor1 (Gpbar-1) has diverse metabolic roles, its involvement in ACLI-associated immune activation remains unclear. Liver tissues and blood samples from 20 patients with ACLI and 20 healthy individuals were analyzed using biochemical tests, H&E staining, western blotting, and immunohistochemistry to verify liver damage and expression of Gpbar-1. The expression of Gpbar-1, cAMP/PKA signaling, and the NLRP3 inflammasome was tested in wild-type (WT) and Gpbar-1 knockdown (si-Gpbar-1) mice with ACLI induced by bile duct ligation (BDL) and in primary Kupffer cells (KCs) with or without Gpbar-1-siRNA. The results showed that total bile acids and Gpbar-1 expressions were elevated in patients with ACLI. Gpbar-1 knockdown significantly worsened BDL-induced acute hepatic damage, inflammation, and liver apoptosis in vivo. Knockdown of Gpbar-1 heightened KC sensitivity to lipopolysaccharide (LPS) stimulation. Gpbar-1 activation inhibited LPS-induced pro-inflammatory responses in normal KCs but not in Gpbar-1-knockdown KCs. Notably, NLRP3-ASC inflammasome expression was effectively enhanced by Gpbar-1 deficiency. Additionally, Gpbar-1 directly increased intracellular cAMP levels and PKA phosphorylation, thus disrupting the NLRP3-ASC inflammasome. The pro-inflammatory characteristic of Gpbar-1 deficiency was almost neutralized by the NLRP3 inhibitor CY-09. In vitro, M1 polarization was accelerated in LPS-stimulated Gpbar-1-knockdown KCs. Therapeutically, Gpbar-1 deficiency exacerbated BDL-induced ACLI, which could be rescued by inhibition of the NLRP3-ASC inflammasome. Our study reveal that Gpbar-1 may act as a novel immune-mediated regulator of ACLI by inhibiting the NLRP3-ASC inflammasome.

Restoring SRSF3 in Kupffer cells attenuates obesity-related insulin resistance

BACKGROUND AND AIMS

In obesity, depletion of KCs expressing CRIg (complement receptor of the Ig superfamily) leads to microbial DNA accumulation, which subsequently triggers tissue inflammation and insulin resistance. However, the mechanism underlying obesity-mediated changes in KC complement immune functions is largely unknown.

APPROACH AND RESULTS

Using KC-specific deactivated Cas9 transgenic mice treated with guide RNA, we assessed the effects of restoring CRIg or the serine/arginine-rich splicing factor 3 (SRSF3) abundance on KC functions and metabolic phenotypes in obese mice. The impacts of weight loss on KC responses were evaluated in a diet switch mouse model. The role of SRSF3 in regulating KC functions was also evaluated using KC-specific SRSF3 knockout mice. Here, we report that overexpression of CRIg in KCs of obese mice protects against bacterial DNA accumulation in metabolic tissues. Mechanistically, SRSF3 regulates CRIg expression, which is essential for maintaining the CRIg+ KC population. During obesity, SRSF3 expression decreases, but it is restored with weight loss through a diet switch, normalizing CRIg+ KCs. KC SRSF3 is also repressed in obese human livers. Lack of SRSF3 in KCs in lean and obese mice decreases their CRIg+ population, impairing metabolic parameters. During the diet switch, the benefits of weight loss are compromised due to SRSF3 deficiency. Conversely, SRSF3 overexpression in obese mice preserves CRIg+ KCs and improves metabolic responses.

CONCLUSIONS

Restoring SRSF3 abundance in KCs offers a strategy against obesity-associated tissue inflammation and insulin resistance by preventing bacterial DNA accumulation.

Sexually Dimorphic Response to Hepatic Injury in Newborn Suffering from Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR), when a fetus does not grow as expected, is associated with a reduction in hepatic functionality and a higher risk for chronic liver disease in adulthood. Utilizing early developmental plasticity to reverse the outcome of poor fetal programming remains an unexplored area. Focusing on the biochemical profiles of neonates and previous transcriptome findings, piglets from the same fetus are selected as models for studying IUGR. The cellular landscape of the liver is created by scRNA-seq to reveal sex-dependent patterns in IUGR-induced hepatic injury. One week after birth, IUGR piglets experience hypoxic stress. IUGR females exhibit fibroblast-driven T cell conversion into an immune-adapted phenotype, which effectively alleviates inflammation and fosters hepatic regeneration. In contrast, males experience even more severe hepatic injury. Prolonged inflammation due to disrupted lipid metabolism hinders intercellular communication among non-immune cells, which ultimately impairs liver regeneration even into adulthood. Additionally, Apolipoprotein A4 (APOA4) is explored as a novel biomarker by reducing hepatic triglyceride deposition as a protective response against hypoxia in IUGR males. PPARα activation can mitigate hepatic damage and meanwhile restore over-expressed APOA4 to normal in IUGR males. The pioneering study offers valuable insights into the sexually dimorphic responses to hepatic injury during IUGR.

Mechanism of PANoptosis in metabolic dysfunction-associated steatotic liver disease

In recent years, the incidence of metabolic dysfunction-associated steatotic liver disease (MASLD) has been steadily rising, emerging as a major chronic liver disease of global concern. The course of MASLD is varied, spanning from MASLD to metabolic dysfunction associated steatohepatitis (MASH). MASH is an important contributor to cirrhosis, which may subsequently lead to hepatocellular carcinoma. It has been found that PANoptosis, an emerging inflammatory programmed cell death (PCD), is involved in the pathogenesis of MASLD and facilitates the development of NASH, eventually resulting in inflammatory fibrosis and hepatocyte death. This paper reviews the latest research progress on PANoptosis and MASLD to understand the mechanism of MASLD and provide new directions for future treatment and drug development.

Outcomes and risk factors for mortality in clostridioides difficile infection in patients with NAFLD and NASH

INTRODUCTION AND OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide and can progress to non-alcoholic steatohepatitis (NASH) and, ultimately, cirrhosis. Clostridioides difficile is the most common nosocomial cause of diarrhea and is associated with worse clinical outcomes in other liver diseases, including cirrhosis, but has not been extensively evaluated in concomitant NAFLD/NASH.

MATERIALS AND METHODS

We conducted a retrospective cohort study using the National Inpatient Sample database from 2015 to 2017. Patients with a diagnosis of CDI, NAFLD, and NASH were identified using International Classification of Diseases (Tenth Revision) codes. The outcomes of our study include length of stay, hospitalization cost, mortality, and predictors of mortality.

RESULTS

The CDI and NASH cohort had a higher degree of comorbidity burden and prevalence of peptic ulcer disease, congestive heart failure, diabetes mellitus, and cirrhosis. Patients with NASH and CDI had a significantly higher mortality rate compared to the CDI only cohort (mortality, 7.11 % vs. 6.36 %; P = 0.042). Patients with CDI and NASH were at increased risk for liver-related complications, acute kidney injury, and septic shock (P < 0.001) compared to patients with CDI only. Older age, intestinal complications, pneumonia, sepsis and septic shock, and liver failure conferred an increased risk of mortality among the CDI and NASH cohort.

CONCLUSIONS

Patients with NASH had a higher rate of liver-related complications, progression to septic shock, and mortality rate following CDI infection compared to the CDI only cohort.

Gut-Liver-Pancreas Axis Crosstalk in Health and Disease: From the Role of Microbial Metabolites to Innovative Microbiota Manipulating Strategies

The functions of the gut are closely related to those of many other organs in the human body. Indeed, the gut microbiota (GM) metabolize several nutrients and compounds that, once released in the bloodstream, can reach distant organs, thus influencing the metabolic and inflammatory tone of the host. The main microbiota-derived metabolites responsible for the modulation of endocrine responses are short-chain fatty acids (SCFAs), bile acids and glucagon-like peptide 1 (GLP-1). These molecules can (i) regulate the pancreatic hormones (insulin and glucagon), (ii) increase glycogen synthesis in the liver, and (iii) boost energy expenditure, especially in skeletal muscles and brown adipose tissue. In other words, they are critical in maintaining glucose and lipid homeostasis. In GM dysbiosis, the imbalance of microbiota-related products can affect the proper endocrine and metabolic functions, including those related to the gut-liver-pancreas axis (GLPA). In addition, the dysbiosis can contribute to the onset of some diseases such as non-alcoholic steatohepatitis (NASH)/non-alcoholic fatty liver disease (NAFLD), hepatocellular carcinoma (HCC), and type 2 diabetes (T2D). In this review, we explored the roles of the gut microbiota-derived metabolites and their involvement in onset and progression of these diseases. In addition, we detailed the main microbiota-modulating strategies that could improve the diseases' development by restoring the healthy balance of the GLPA.

Necroptosis contributes to non-alcoholic fatty liver disease pathoetiology with promising diagnostic and therapeutic functions

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent type of chronic liver disease. However, the disease is underappreciated as a remarkable chronic disorder as there are rare managing strategies. Several studies have focused on determining NAFLD-caused hepatocyte death to elucidate the disease pathoetiology and suggest functional therapeutic and diagnostic options. Pyroptosis, ferroptosis, and necroptosis are the main subtypes of non-apoptotic regulated cell deaths (RCDs), each of which represents particular characteristics. Considering the complexity of the findings, the present study aimed to review these types of RCDs and their contribution to NAFLD progression, and subsequently discuss in detail the role of necroptosis in the pathoetiology, diagnosis, and treatment of the disease. The study revealed that necroptosis is involved in the occurrence of NAFLD and its progression towards steatohepatitis and cancer, hence it has potential in diagnostic and therapeutic approaches. Nevertheless, further studies are necessary.

Indoleamine 2,3-dioxygenase 1-mediated iron metabolism in macrophages contributes to lipid deposition in nonalcoholic steatohepatitis

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is a rapidly progressing chronic liver disease of global significance. However, the underlying mechanisms responsible for NASH remain unknown. Indoleamine 2,3-dioxygenase 1 (IDO1) has been recognized as essential factor in immune response and metabolic regulation. Here we aimed to investigate the functions and mechanisms of the IDO1 in macrophages on hepatic lipid deposition and iron metabolism in NASH.

METHODS

The effect of IDO1 in NASH was evaluated by WT and IDO1-/- mice model fed with methionine/choline-deficient (MCD) diet in vivo. Macrophages scavenger clodronate liposomes (CL) and overexpressing of IDO1 in macrophages by virus were employed as well. Lipid deposition was assessed through pathological examination and lipid droplet staining, while iron levels were measured using an iron assay kit and western blotting. Primary hepatocytes and bone marrow-derived macrophages were treated with oleic acid/palmitic acid (OA/PA) to assess IDO1 expression via Oil Red O staining and immunofluorescence staining in vitro.

RESULTS

Pathological images demonstrated that the increase of IDO1 exacerbated lipid accumulation in the livers of mice with MCD diet, while reduction of iron accumulation was observed in the liver and the serum of MCD-fed mice. Scavenging of macrophages effectively mitigated both lipid and iron accumulation. In addition, the deficiency of IDO1 in macrophages significantly mitigated lipid accumulation and iron overload in hepatic parenchymal cells. Finally, lentivirus-mediated overexpression of IDO1 in liver macrophages exacerbated hepatic steatosis and iron deposition in NASH.

CONCLUSIONS

Our results demonstrated that effective inhibition of IDO1 expression in macrophages in NASH alleviated hepatic parenchymal cell lipid accumulation and iron deposition, which provided new insights for the future treatment of NASH.

Fatty Liver, Statin Therapy, and the Risk of Hypertriglyceridemic Acute Pancreatitis: A Retrospective Study

OBJECTIVES

Identifying patients with severe hypertriglyceridemia (HTG) who are prone to developing hypertriglyceridemic pancreatitis (HTGP) is essential for facilitating preventative interventions. This research aims to explore which part of the HTG patients is easy to develop into HTGP.

MATERIALS AND METHODS

An observational cohort study was conducted in patients with serum triglycerides (TGs) ≥ 5.65 mmol/L. Propensity score matching (PSM) and logistic regression were used to adjust for potential confounding factors. Receiver operating characteristic (ROC) curves were applied to evaluate the predictive potential for HTGP.

RESULTS

A total of 283 patients were included finally with a PSM cohort consisting of 55 HTGP matched with 77 non-HTGP. In multivariate logistic regression analysis, fatty liver (FL) (odds ratio, 2.535; P = 0.019) showed statistically significant association with HTGP, whereas statin use was correlated with a lower rate of HTGP (odds ratio, 0.203; P = 0.009). Finally, the ROC analysis showed that the TGs threshold thought to be causal of HTGP in patients with FL was significantly lower (9.31 vs 14.67 mmol/L) than that in patients without FL.

CONCLUSIONS

Although with lower TGs levels, patients with FL are much more prone to generate HTGP, and our findings suggest a potential role of statin as protective agents against HTGP.

HIF1α/miR-146α/TRAF6/NF-κB axis modulates hepatic iron overload-induced inflammation

Transfusional therapy is used to cure anemia but raises the risk of hepatic iron overload (IO), which triggers oxidative stress damage, inflammation, and failure even fibrosis. microRNAs play a vital role in developing hepatic diseases. This study presented the mechanism by which IO induce hepatic inflammation through microRNAs. In this study, microRNA expression profiling in the liver was observed after IO for 2 weeks, in which the target microRNA will be found. IO activating the miR-146α/TRAF6/NF-κB pathway was validated, and the molecular mechanism of the IO-induced decrease of miR-146α in the liver was studied in vivo and in vitro. The expression of TRAF6/NF-κB (p65)-dependent inflammatory factors increased, whereas the expression of miR-146α decreased during the IO-induced inflammatory response in the liver. The reduced expression of HNF4α caused by HIF1α and miR-34α may decrease the expression of miR-146α. Overexpression of miR-146α alleviated the hepatic inflammatory response caused by IO. Our findings indicate that miR-146α is a key factor in inducing hepatic IO inflammation, which will be another potential target to prevent IO-induced hepatic damage.

Activation of GPR3-β-arrestin2-PKM2 pathway in Kupffer cells stimulates glycolysis and inhibits obesity and liver pathogenesis

Kupffer cells are liver resident macrophages and play critical role in fatty liver disease, yet the underlying mechanisms remain unclear. Here, we show that activation of G-protein coupled receptor 3 (GPR3) in Kupffer cells stimulates glycolysis and protects mice from obesity and fatty liver disease. GPR3 activation induces a rapid increase in glycolysis via formation of complexes between β-arrestin2 and key glycolytic enzymes as well as sustained increase in glycolysis through transcription of glycolytic genes. In mice, GPR3 activation in Kupffer cells results in enhanced glycolysis, reduced inflammation and inhibition of high-fat diet induced obesity and liver pathogenesis. In human fatty liver biopsies, GPR3 activation increases expression of glycolytic genes and reduces expression of inflammatory genes in a population of disease-associated macrophages. These findings identify GPR3 activation as a pivotal mechanism for metabolic reprogramming of Kupffer cells and as a potential approach for treating fatty liver disease.

Association of metabolic dysfunction-associated fatty liver disease with gastrointestinal infections: insights from National Inpatient Sample Database

OBJECTIVES

The study aimed to compare the risk of gastrointestinal infections among patients with and without metabolic dysfunction-associated fatty liver disease (MAFLD).

METHODS

This was a population-based, retrospective, observational study using data from the National Inpatient Sample (NIS), the largest all-payer US inpatient care database.

SETTING

Hospitalisation of adults aged ≥18 years old admitted in 2020 was identified using the NIS. Patients were stratified by the presence and absence of MAFLD.

PARTICIPANTS

26.4 million adults aged ≥18 years old were included in the study. Patients younger than 18 and those with missing demographic or mortality data were excluded.

PRIMARY AND SECONDARY OUTCOMES

Primary outcome was to assess the overall risk of gastrointestinal infections in patients with and without MAFLD. Secondary outcomes were demographics and comorbidities stratified by the presence or absence of gastrointestinal infection, and the risk of specific gastrointestinal pathogens.

RESULTS

Of 26.4 million patients admitted in 2020, 755 910 (2.85%) had the presence of MAFLD. There was a higher prevalence of bacterial gastrointestinal infections in patients with MAFLD than those without (1.6% vs 0.9%, p<0.001). The incidence of Clostridioides difficile (1.3% vs 0.8%, p<0.001), Escherichia coli (0.3% vs 0.01%, p<0.001), and Salmonella (0.07% vs 0.03%, p<0.001) was higher in patients with MAFLD. The presence of MAFLD was associated with higher odds of developing gastrointestinal infections (adjusted OR (aOR) -1.75, 95% CI -1.68 to 1.83, p<0.001). After adjusting for confounders, results remained statistically significant (aOR -1.36, 95% CI - 1.30-1.42, p<0.001).

CONCLUSION

Even after adjusting for confounding factors, our study demonstrates an increased risk of gastrointestinal infections in patients with MAFLD, specifically of C. difficile, E. coli, and Salmonella. The immune and microbiota changes seen within MAFLD potentially contribute to the increased risk of gastrointestinal infections.

Gut microbes in metabolic disturbances. Promising role for therapeutic manipulations?

The prevalence of overweight, obesity, type 2 diabetes, metabolic syndrome and steatotic liver disease is rapidly increasing worldwide with a huge economic burden in terms of morbidity and mortality. Several genetic and environmental factors are involved in the onset and development of metabolic disorders and related complications. A critical role also exists for the gut microbiota, a complex polymicrobial ecology at the interface of the internal and external environment. The gut microbiota contributes to food digestion and transformation, caloric intake, and immune response of the host, keeping the homeostatic control in health. Mechanisms of disease include enhanced energy extraction from the non-digestible dietary carbohydrates, increased gut permeability and translocation of bacterial metabolites which activate a chronic low-grade systemic inflammation and insulin resistance, as precursors of tangible metabolic disorders involving glucose and lipid homeostasis. The ultimate causative role of gut microbiota in this respect remains to be elucidated, as well as the therapeutic value of manipulating the gut microbiota by diet, pre- and pro- synbiotics, or fecal microbial transplantation.

Risk of Severe Infection in Patients With Biopsy-proven Nonalcoholic Fatty Liver Disease - A Population-based Cohort Study

BACKGROUND & AIMS

It has been suggested that patients with nonalcoholic fatty liver disease (NAFLD) might be at increased risk of severe infections, but large-scale data from cohorts with biopsy-proven NAFLD are lacking.

METHODS

Population-based cohort study including all Swedish adults with histologically confirmed NAFLD (n = 12,133) from 1969 to 2017. NAFLD was defined as simple steatosis (n = 8232), nonfibrotic steatohepatitis (n = 1378), noncirrhotic fibrosis (n = 1845), and cirrhosis (n = 678). Patients were matched to ≤5 population comparators (n = 57,516) by age, sex, calendar year, and county. Swedish national registers were used to ascertain incident severe infections requiring hospital admission. Multivariable adjusted Cox regression was used to estimate hazard ratios in NAFLD and histopathological subgroups.

RESULTS

Over a median of 14.1 years, 4517 (37.2%) patients with NAFLD vs 15,075 (26.2%) comparators were hospitalized for severe infections. Patients with NAFLD had higher incidence of severe infections than comparators (32.3 vs. 17.0/1000 person-years; adjusted hazard ratio [aHR], 1.71; 95% confidence interval, 1.63-1.79). The most frequent infections were respiratory (13.8/1000 person-years) and urinary tract infections (11.4/1000 person-years). The absolute risk difference at 20 years after NAFLD diagnosis was 17.3%, equal to one extra severe infection in every 6 patients with NAFLD. Risk of infection increased with worsening histological severity of NAFLD (simple steatosis [aHR, 1.64], nonfibrotic steatohepatitis [aHR, 1.84], noncirrhotic fibrosis [aHR, 1.77], and cirrhosis [aHR, 2.32]. Also compared with their full siblings, patients with NAFLD were at increased risk of severe infections (aHR, 1.54; 95% confidence interval, 1.40-1.70).

CONCLUSIONS

Patients with biopsy-proven NAFLD were at significantly higher risk of incident severe infection requiring hospitalization both compared with the general population and compared with siblings. Excess risk was evident across all stages of NAFLD and increased with worsening disease severity.

Insights into the role of vitamin D in targeting the culprits of non-alcoholic fatty liver disease

Vitamin D (VD) is a secosteroid hormone that is renowned for its crucial role in phospho-calcium homeostasis upon binding to the nuclear vitamin D receptor (VDR). Over and above, the pleiotropic immunomodulatory, anti-inflammatory, and metabolic roles VD plays in different disease settings started to surface in the past few decades. On the other hand, a growing body of evidence suggests a correlation between non-alcoholic fatty liver disease (NAFLD) and its progressive inflammatory form non-alcoholic steatohepatitis (NASH) with vitamin D deficiency (VDD) owing to the former's ingrained link with obesity and metabolic syndrome. Accordingly, a better understanding of the contribution of disrupted VDR signalling to NAFLD incidence and progression would provide further insights into its diagnosis, treatment modalities, and prognosis. This is especially significant as, hitherto, no drug for NAFLD has been approved. This review, therefore, sought to set forth the likely contribution of VDR signalling in NAFLD and how it might influence its multiple drivers.

The Impact and Burden of Dietary Sugars on the Liver

NAFLD, or metabolic dysfunction-associated steatotic liver disease, has increased in prevalence hand in hand with the rise in obesity and increased free sugars in the food supply. The causes of NAFLD are genetic in origin combined with environmental drivers of the disease phenotype. Dietary intake of added sugars has been shown to have a major role in the phenotypic onset and progression of the disease. Simple sugars are key drivers of steatosis, likely through fueling de novo lipogenesis, the conversion of excess carbohydrates into fatty acids, but also appear to upregulate lipogenic metabolism and trigger hyperinsulinemia, another driver. NAFLD carries a clinical burden as it is associated with obesity, type 2 diabetes, metabolic syndrome, and cardiovascular disease. Patient quality of life is also impacted, and there is an enormous economic burden due to healthcare use, which is likely to increase in the coming years. This review aims to discuss the role of dietary sugar in NAFLD pathogenesis, the health and economic burden, and the promising potential of sugar reduction to improve health outcomes for patients with this chronic liver disease.

15-keto-PGE2 alleviates nonalcoholic steatohepatitis through its covalent modification of NF-κB factors

15-keto-PGE2 is one of the eicosanoids with anti-inflammatory properties. In this study, we demonstrated that 15-keto-PGE2 post-translationally modified the nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) subunits p105/p50 and p65 at Cys59 and Cys120 sites, respectively, hence inhibiting the activation of NF-κB signaling in macrophages. In mice fed a high-fat and high-sucrose diet (HFHSD), 15-keto-PGE2 treatment reduced pro-inflammatory cytokines and fasting glucose levels. In mice with non-alcoholic steatohepatitis (NASH) induced by a prolonged HFHSD, 15-keto-PGE2 treatment significantly decreased liver inflammation, lowered serum levels of alanine transaminase (ALT) and aspartate transferase (AST), and inhibited macrophage infiltration. It also reduced lipid droplet size and downregulated key regulators of lipogenesis. These findings highlight the potential of 15-keto-PGE2, through NF-κB modification, in preventing the development and progression of steatohepatitis, emphasizing the significance of endogenous lipid mediators in the inflammatory response.

Risk of infections in non-alcoholic fatty liver disease: A nationwide population-based cohort study

BACKGROUND AND AIMS

Previous literature suggests an association between non-alcoholic fatty liver disease (NAFLD) and infections. We aimed to determine the rate and risk of severe infections in NAFLD compared to the general population.

METHODS

In this population-based cohort study, we used national registers to identify all patients with a hospital-based diagnosis of NAFLD in Sweden 1987-2020 (n = 14 869). The patients were matched with ≤10 comparators from the general population for age, sex, municipality, and calendar year (n = 137 145). Cox regression was used to estimate hazard ratios (HR) for infections in patients with NAFLD compared to comparators. Cumulative incidences were calculated while accounting for competing risks (non-infection death and liver transplantation).

RESULTS

Severe infections leading to death or hospitalization occurred in 1990 (13.4%) patients with NAFLD and 9899 (7.2%) comparators during a median of 4.5 and 6.1 years of follow-up, respectively. The rate of severe infections per 1000 person-years was higher in patients with NAFLD (21.0) than comparators (9.1) independently of components related to the metabolic syndrome (adjusted HR 1.9, 95% CI = 1.8-2.0). Infection-related mortality was also higher in NAFLD compared to comparators (adjusted HR 1.8, 95% CI = 1.6-2.2). The 10-year cumulative incidence of severe infections was 16.6% (95% CI = 15.8-17.4) in NAFLD and 8.0% (95% CI = 7.8-8.2) in comparators.

CONCLUSION

NAFLD was associated with severe infections and infection-related mortality, independently of components associated with the metabolic syndrome. Increased clinical vigilance of severe infections in NAFLD may diminish the risk of premature death.

Coagulation Dysfunctions in Non-Alcoholic Fatty Liver Disease-Oxidative Stress and Inflammation Relevance

Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases. Its incidence is progressively rising and it is possibly becoming a worldwide epidemic. NAFLD encompasses a spectrum of diseases accounting for the chronic accumulation of fat within the hepatocytes due to various causes, excluding excessive alcohol consumption. In this study, we aimed to focus on finding evidence regarding the implications of oxidative stress and inflammatory processes that form the multifaceted pathophysiological tableau in relation to thrombotic events that co-occur in NAFLD and associated chronic liver diseases. Recent evidence on the pathophysiology of NAFLD suggests that a complex pattern of multidirectional components, such as prooxidative, proinflammatory, and prothrombotic components, better explains the multiple factors that promote the mechanisms underlying the fatty acid excess and subsequent processes. As there is extensive evidence on the multi-component nature of NAFLD pathophysiology, further studies could address the complex interactions that underlie the development and progression of the disease. Therefore, this study aimed to describe possible pathophysiological mechanisms connecting the molecular impairments with the various clinical manifestations, focusing especially on the interactions among oxidative stress, inflammation, and coagulation dysfunctions. Thus, we described the possible bidirectional modulation among coagulation homeostasis, oxidative stress, and inflammation that occurs in the various stages of NAFLD.

Inhibition of DHCR24 activates LXRα to ameliorate hepatic steatosis and inflammation

Liver X receptor (LXR) agonism has theoretical potential for treating NAFLD/NASH, but synthetic agonists induce hyperlipidemia in preclinical models. Desmosterol, which is converted by Δ24-dehydrocholesterol reductase (DHCR24) into cholesterol, is a potent endogenous LXR agonist with anti-inflammatory properties. We aimed to investigate the effects of DHCR24 inhibition on NAFLD/NASH development. Here, by using APOE*3-Leiden. CETP mice, a well-established translational model that develops diet-induced human-like NAFLD/NASH characteristics, we report that SH42, a published DHCR24 inhibitor, markedly increases desmosterol levels in liver and plasma, reduces hepatic lipid content and the steatosis score, and decreases plasma fatty acid and cholesteryl ester concentrations. Flow cytometry showed that SH42 decreases liver inflammation by preventing Kupffer cell activation and monocyte infiltration. LXRα deficiency completely abolishes these beneficial effects of SH42. Together, the inhibition of DHCR24 by SH42 prevents diet-induced hepatic steatosis and inflammation in a strictly LXRα-dependent manner without causing hyperlipidemia. Finally, we also showed that SH42 treatment decreased liver collagen content and plasma alanine transaminase levels in an established NAFLD model. In conclusion, we anticipate that pharmacological DHCR24 inhibition may represent a novel therapeutic strategy for treatment of NAFLD/NASH.

Research Progress of Takeda G Protein-Coupled Receptor 5 in Metabolic Syndrome

Bile acids are acknowledged as signaling molecules involved in metabolic syndrome. The Takeda G protein-coupled receptor 5 (TGR5) functions as a significant bile acid receptor. The accumulated evidence suggests that TGR5 involves lipid homeostasis, glucose metabolism, and inflammation regulation. In line with this, recent preclinical studies also demonstrate that TGR5 plays a significant role in the generation and progression of metabolic syndrome, encompassing type 2 diabetes mellitus, obesity, atherosclerosis, and non-alcoholic fatty liver disease (NAFLD). In this review, we discuss the role of TGR5 in metabolic syndrome, illustrating the underlying mechanisms and therapeutic targets.

Hepatic Fat and Macrophages Are Increased in Livers of Diabetic Patients without Non-Alcoholic Fatty Liver Disease

INTRODUCTION

Diabetes mellitus (DM), especially type 2, is strongly associated with non-alcoholic fatty liver disease (NAFLD). Recent studies indicate that particularly in DM patients, "simple" liver steatosis can progress into more severe disease. However, little is known about putative hepatic histopathological changes in DM patients without NAFLD. In this study, we therefore analysed fat content and inflammatory cell infiltration in the livers of deceased DM and non-DM patients without NAFLD, and analysed age/sex effects hereon.

METHODS

Hepatic fat and inflammatory cells were studied through (immuno)histochemical analysis in liver tissue from 24 DM patients and 66 non-diabetic controls, without histopathological characteristics of NAFLD.

RESULTS

We observed a 2-fold increase in fat percentage/mm2 and a near 5-fold increase in the number of fat-containing cells/mm2 in DM patients compared to non-diabetic controls. Fat content was significantly higher in patients with type 2 DM, but not type 1 DM, compared to non-diabetic controls, while the number of CD68+ cells/mm2 was significantly elevated in both DM groups.

CONCLUSION

Hepatic fat and number of macrophages are increased in patients with DM without NAFLD, which may reflect a higher risk on development of steatosis and steatohepatitis.

Anti-Angiogenic Effects of Natural Compounds in Diet-Associated Hepatic Inflammation

Alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD) are the most common causes of chronic liver disease and are increasingly emerging as a global health problem. Such disorders can lead to liver damage, resulting in the release of pro-inflammatory cytokines and the activation of infiltrating immune cells. These are some of the common features of ALD progression in ASH (alcoholic steatohepatitis) and NAFLD to NASH (non-alcoholic steatohepatitis). Hepatic steatosis, followed by fibrosis, lead to a continuous progression accompanied by angiogenesis. This process creates hypoxia, which activates vascular factors, initiating pathological angiogenesis and further fibrosis. This forms a vicious cycle of ongoing damage and progression. This condition further exacerbates liver injury and may contribute to the development of comorbidities, such as metabolic syndrome as well as hepatocellular carcinoma. Increasing evidence suggests that anti-angiogenic therapy may have beneficial effects on these hepatic disorders and their exacerbation. Therefore, there is a great interest to deepen the knowledge of the molecular mechanisms of natural anti-angiogenic products that could both prevent and control liver diseases. In this review, we focus on the role of major natural anti-angiogenic compounds against steatohepatitis and determine their potential therapeutic benefits in the treatment of liver inflammation caused by an imbalanced diet.

Arjunolic acid modulate pancreatic dysfunction by ameliorating pattern recognition receptor and canonical Wnt pathway activation in type 2 diabetic rats

BACKGROUND

Arjunolic acid (AA) is a potent phytochemical with multiple therapeutics effects. In this study, AA is evaluated on type 2 diabetic (T2DM) rats to understand the mechanism of β-cell linkage with Toll-like receptor 4 (TLR-4) and canonical Wnt signaling. However, its role in modulating TLR-4 and canonical Wnt/β-catenin crosstalk on insulin signaling remains unclear during T2DM. Aim The current study is aimed to examine the potential role of AA on insulin signaling and TLR-4-Wnt crosstalk in the pancreas of type 2 diabetic rats.

METHOD

Multiple methods were used to determine molecular cognizance of AA in T2DM rats, when treated with different dosage levels. Histopathological and histomorphometry analysis was conducted using masson trichrome and H&E stains. While, protein and mRNA expressions of TLR-4/Wnt and insulin signaling were assessed using automated Western blotting (jess), immunohistochemistry, and RT-PCR.

RESULTS

Histopathological findings revealed that AA had reversed back the T2DM-induced apoptosis and necrosis caused to rats pancreas. Molecular findings exhibited prominent effects of AA in downregulating the elevated level of TLR-4, MyD88, NF-κB, p-JNK, and Wnt/β-catenin by blocking TLR-4/MyD88 and canonical Wnt signaling in diabetic pancreas, while IRS-1, PI3K, and pAkt were all upregulated by altering the NF-κB and β-catenin crosstalk during T2DM.

CONCLUSION

Overall results, indicate that AA has potential to develop as an effective therapeutic in the treatment of T2DM associated meta-inflammation. However, future preclinical research at multiple dose level in a long-term chronic T2DM disease model is warranted to understand its clinical relevance in cardiometabolic disease.

Uric acid and sCD163 as biomarkers for metabolic dysfunction and MAFLD in children and adolescents with overweight and obesity

OBJECTIVES

The prevalence of childhood obesity increases globally, and noninvasive methods are needed to identify metabolic dysfunction and obesity-related complications such as pediatric metabolic associated fatty liver disease (MAFLD). We investigated whether uric acid (UA) and the macrophage marker soluble form of cysteine scavenger receptor CD163 (sCD163) can be used as biomarkers for deteriorated metabolism or pediatric MAFLD in children with overweight or obesity.

METHODS

Cross-sectional clinical and biochemical data from 94 children with overweight or obesity was included. Surrogate liver markers were calculated, and correlations were investigated using Pearson's or Spearman's correlation test.

RESULTS

UA and sCD163 correlated with BMI standard deviation score (r=0.23, p<0.05; r=0.33, p<0.01) and body fat (r=0.24, p<0.05; r=0.27, p=0.01). UA correlated with triglycerides (ρ=0.21, p<0.05), fat free mass (r=0.33, p<0.01), and gamma-glutamyl transferase (r=0.39, p<0.01). sCD163 correlated with the pediatric NAFLD fibrosis score (r=0.28, p<0.01) and alanine aminotransferase (r=0.28, p<0.01). No correlation was found between UA and pediatric MAFLD.

CONCLUSIONS

UA and sCD163 was identified as markers of a deranged metabolic profile, thus acting as easily accessible biomarkers for obesity and an obesity-related deranged metabolism. Furthermore, increasing levels of sCD163 could be a useful biomarker of pediatric MAFLD. Future prospective studies are warranted.

Butyrate limits inflammatory macrophage niche in NASH

Immune cell infiltrations with lobular inflammation in the background of steatosis and deregulated gut-liver axis are the cardinal features of non-alcoholic steatohepatitis (NASH). An array of gut microbiota-derived metabolites including short-chain fatty acids (SCFA) multifariously modulates NASH pathogenesis. However, the molecular basis for the favorable impact of sodium butyrate (NaBu), a gut microbiota-derived SCFA, on the immunometabolic homeostasis in NASH remains elusive. We show that NaBu imparts a robust anti-inflammatory effect in lipopolysaccharide (LPS) stimulated or classically activated M1 polarized macrophages and in the diet-induced murine NASH model. Moreover, it impedes monocyte-derived inflammatory macrophage recruitment in liver parenchyma and induces apoptosis of proinflammatory liver macrophages (LM) in NASH livers. Mechanistically, by histone deactylase (HDAC) inhibition NaBu enhanced acetylation of canonical NF-κB subunit p65 along with its differential recruitment to the proinflammatory gene promoters independent of its nuclear translocation. NaBu-treated macrophages thus exhibit transcriptomic signatures that corroborate with a M2-like prohealing phenotype. NaBu quelled LPS-mediated catabolism and phagocytosis of macrophages, exhibited a differential secretome which consequently resulted in skewing toward prohealing phenotype and induced death of proinflammatory macrophages to abrogate metaflammation in vitro and in vivo. Thus NaBu could be a potential therapeutic as well as preventive agent in mitigating NASH.

Pharmacological inhibition of DNMT1 restores macrophage autophagy and M2 polarization in western diet-induced Nonalcoholic fatty liver disease

Non-Alcoholic Fatty Liver Disease (NAFLD) is associated with an increased ratio of classically activated M1 macrophages/Kupffer cells to alternatively activated M2 macrophages, which plays an imperative role in the development & progression of NAFLD. However, little is known about the precise mechanism behind macrophage polarization shift. Here, we provide evidence regarding the relationship between the polarization shift in Kupffer cells and autophagy resulting from lipid exposure. High-fat and High-fructose diet supplementation for 10 weeks significantly increased the abundance of Kupffer cells with an M1-predominant phenotype in mice. Interestingly, at the molecular level, we also observed a concomitant increase in expression of DNA methyltransferases DNMT1 and reduced autophagy in the NAFLD mice. We also observed hypermethylation at the promotor regions of autophagy genes (LC3B, ATG-5, and ATG-7). Furthermore, the pharmacological inhibition of DNMT1 by using DNA hypomethylating agents (Azacitidine and Zebularine) restored Kupffer cell autophagy, M1/M2 polarization and therefore prevented the progression of NAFLD. We report the presence of a link between epigenetic regulation of autophagy gene and macrophage polarization switch. We provide the evidence that epigenetic modulators restore the lipid-induced imbalance in macrophage polarization, therefore, preventing the development & progression of NAFLD.

PPAR-γ signaling in nonalcoholic fatty liver disease: Pathogenesis and therapeutic targets

Non-alcoholic fatty liver disease (NAFLD), currently the leading cause of global chronic liver disease, has emerged as a major public health problem, more efficient therapeutics of which are thus urgently needed. Peroxisome proliferator-activated receptor γ (PPAR-γ), ligand-activated transcription factors of the nuclear hormone receptor superfamily, is considered a crucial metabolic regulator of hepatic lipid metabolism and inflammation. The role of PPAR-γ in the pathogenesis of NAFLD is gradually being recognized. Here, we outline the involvement of PPAR-γ in the pathogenesis of NAFLD through adipogenesis, insulin resistance, inflammation, oxidative stress, endoplasmic reticulum stress, and fibrosis. In addition, the evidence for PPAR-γ- targeted therapy for NAFLD are summarized. Altogether, PPAR-γ is a promising therapeutic target for NAFLD, and the development of drugs that can balance the beneficial and undesirable effects of PPAR-γ will bring new light to NAFLD patients.

High-fat diet increases mortality and intensifies immunometabolic changes in septic mice

Immunometabolic changes in the liver and white adipose tissue (WAT) caused by high-fat (HF) diet intake may worse metabolic adaptation and protection against pathogens in sepsis. We investigate the effect of chronic HF diet (15 weeks) on mortality and immunometabolic responses in female mice after sepsis induced by cecum ligation and perforation (CLP). At week 14, animals were divided into four groups: sham C diet (C-Sh), sepsis C diet (C-Sp), sham HF diet (HF-Sh) and sepsis HF diet (HF-Sp). The surviving animals were euthanised on the 7th day. The HF diet decreased survival rate (58.3% vs 76.2% C-Sp group), increased serum cytokine storm (IL-6 (1.41 ×; vs HF-Sh), IL-1β (1.37 ×; vs C-Sp), TNF (1.34 ×; vs C-Sp and 1.72 ×; vs HF-Sh), IL-17 (1.44 ×; vs HF-Sh), IL-10 (1.55 ×; vs C-Sp and 1.41 ×; HF-Sh), WAT inflammation (IL-6 (8.7 ×; vs C-Sp and 2.4 ×; vs HF-Sh), TNF (5 ×; vs C-Sp and 1.7 ×;vs HF-Sh), IL-17 (1.7 ×; vs C-Sp), IL-10 (7.4 ×; vs C-Sp and 1.3 ×; vs HF-Sh), and modulated lipid metabolism in septic mice. In the HF-Sp group liver's, we observed hepatomegaly, hydropic degeneration, necrosis, an increase in oxidative stress (reduction of CAT activity (-81.7%; vs HF-Sh); increase MDA levels (82.8%; vs HF-Sh), and hepatic IL-6 (1.9 ×; vs HF-Sh), and TNF (1.3 × %;vs HF-Sh) production. Furthermore, we found a decrease in the total number of inflammatory, mononuclear cells, and in the regenerative processes, and binucleated hepatocytes in a HF-Sp group liver's. Our results suggested that the organism under metabolic stress of a HF diet during sepsis may worsen the inflammatory landscape and hepatocellular injury and may harm the liver regenerative process.

Hypoglycemic Potential of Carica papaya in Liver Is Mediated through IRS-2/PI3K/SREBP-1c/GLUT2 Signaling in High-Fat-Diet-Induced Type-2 Diabetic Male Rats

Regardless of socioeconomic or demographic background, the prevalence of type 2 diabetes mellitus, which affects more than half a billion people worldwide, has been steadily increasing over time. The health, emotional, sociological, and economic well-being of people would suffer if this number is not successfully handled. The liver is one of the key organs accountable for sustaining metabolic balance. Elevated levels of reactive oxygen species inhibit the recruitment and activation of IRS-1, IRS-2, and PI3K-Akt downstream signaling cascade. These signaling mechanisms reduce hepatic glucose absorption and glycogenesis while increasing hepatic glucose output and glycogenolysis. In our work, an analysis of the molecular mechanism of Carica papaya in mitigating hepatic insulin resistance in vivo and in silico was carried out. The gluconeogenic enzymes, glycolytic enzymes, hepatic glycogen tissue concentration, oxidative stress markers, enzymatic antioxidants, protein expression of IRS-2, PI3K, SREBP-1C, and GLUT-2 were evaluated in the liver tissues of high-fat-diet streptozotocin-induced type 2 diabetic rats using q-RT-PCR as well as immunohistochemistry and histopathology. Upon treatment, C. papaya restored the protein and gene expression in the liver. In the docking analysis, quercetin, kaempferol, caffeic acid, and p-coumaric acid present in the extract were found to have high binding affinities against IRS-2, PI3K, SREBP-1c, and GLUT-2, which may have contributed much to the antidiabetic property of C. papaya. Thus, C. papaya was capable of restoring the altered levels in the hepatic tissues of T2DM rats, reversing hepatic insulin resistance.

Non-Parenchymal Cells and the Extracellular Matrix in Hepatocellular Carcinoma in Non-Alcoholic Fatty Liver Disease

Hepatocellular carcinoma (HCC) in the setting of non-alcoholic fatty liver disease (NAFLD)-related cirrhosis and even in the pre-cirrhotic state is increasing in incidence. NAFLD-related HCC has a poor clinical outcome as it is often advanced at diagnosis due to late diagnosis and systemic treatment response is poor due to reduced immune surveillance. Much of the focus of molecular research has been on the pathological changes in hepatocytes; however, immune cells, hepatic stellate cells, liver sinusoidal endothelial cells and the extracellular matrix may play important roles in the pathogenesis of NAFLD-related HCC as well. Here, we review the role of non-parenchymal cells in the liver in the pathogenesis of HCC in the context of NAFLD-NASH, with a particular focus on the innate and the adaptive immune system, fibrogenesis and angiogenesis. We review the key roles of macrophages, hepatic stellate cells (HSCs), T cells, natural killer (NK) cells, NKT cells and liver sinusoidal endothelial cells (LSECs) and the role of the extracellular matrix in hepatocarcinogenesis within the steatotic milieu.

Gut Microbiome and Its Impact on Obesity and Obesity-Related Disorders

PURPOSE OF REVIEW

The prevalence of overweight and obesity has been increasing worldwide at an alarming rate. Gut microbiota intimately influence host energy metabolism, and immune response. Studies indicate a prominent role of gut dysbiosis in propagating inflammation that is associated with the development of obesity and obesity-related disorders such as type 2 diabetes mellitus, metabolic syndrome, and non-alcoholic fatty liver disease. This article will review the current literature on gut microbiome and its impact on obesity and obesity-related disorders.

RECENT FINDINGS

An altered gut microbial composition in obesity and obesity-related disorders is associated with enhanced energy extraction from the non-digestible dietary carbohydrates, increased gut permeability, increased production of proinflammatory metabolites, such as lipopolysaccharides, resulting in systemic inflammation and insulin resistance. Gut microbiota modulation can be achieved either by dietary manipulation or by administration of probiotics, prebiotics, synbiotics, and/or fecal microbiota transplantation aiming at the improvement of the gut dysbiosis in obesity and metabolic disorders. Further clinical trials are required to better elucidate the dose, and frequency of these interventions and also their long-term impact on host metabolism.

Immune and metabolic cross-links in the pathogenesis of comorbid non-alcoholic fatty liver disease

In recent years, there has been a steady growth of interest in non-alcoholic fatty liver disease (NAFLD), which is associated with negative epidemiological data on the prevalence of the disease and its clinical significance. NAFLD is closely related to the metabolic syndrome and these relationships are the subject of active research. A growing body of evidence shows cross-linkages between metabolic abnormalities and the innate immune system in the development and progression of NAFLD. These links are bidirectional and largely still unclear, but a better understanding of them will improve the quality of diagnosis and management of patients. In addition, lipid metabolic disorders and the innate immune system link NAFLD with other diseases, such as atherosclerosis, which is of great clinical importance.

Targeting macrophagic 17β-HSD7 by fenretinide for the treatment of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide and macrophage polarization plays an important role in its pathogenesis. However, which molecule regulates macrophage polarization in NAFLD remains unclear. Herein, we showed NAFLD mice exhibited increased 17β-hydroxysteroid dehydrogenase type 7 (17β-HSD7) expression in hepatic macrophages concomitantly with elevated M1 polarization. Single-cell RNA sequencing on hepatic non-parenchymal cells isolated from wild-type littermates and macrophage-17β-HSD7 knockout mice fed with high fat diet (HFD) for 6 weeks revealed that lipid metabolism pathways were notably changed. Furthermore, 17β-HSD7 deficiency in macrophages attenuated HFD-induced hepatic steatosis, insulin resistance and liver injury. Mechanistically, 17β-HSD7 triggered NLRP3 inflammasome activation by increasing free cholesterol content, thereby promoting M1 polarization of macrophages and the secretion of pro-inflammatory cytokines. In addition, to help demonstrate that 17β-HSD7 is a potential drug target for NAFLD, fenretinide was screened out from an FDA-approved drug library based on its 17β-HSD7 dehydrogenase inhibitory activity. Fenretinide dose-dependently abrogated macrophage polarization and pro-inflammatory cytokines production, and subsequently inhibited fat deposition in hepatocytes co-cultured with macrophages. In conclusion, our findings suggest that blockade of 17β-HSD7 signaling by fenretinide would be a drug repurposing strategy for NAFLD treatment.

Deficiency of Adipose Triglyceride Lipase Induces Metabolic Syndrome and Cardiomyopathy in Zebrafish

Lipid metabolism dysfunction is related to clinical disorders including obesity, cancer, liver steatosis, and cardiomyopathy. Impaired lipolytic enzymes result in altered release of free fatty acids. The dramatic change in dyslipidemia is important in lipotoxic cardiomyopathy. Adipose triglyceride lipase (ATGL) catalyzes the lipolysis of triacylglycerol to reduce intramyocardial triglyceride levels in the heart and improve myocardial function. We examined the role of ATGL in metabolic cardiomyopathy by developing an Atgl knockout (ALKO) zebrafish model of metabolic cardiomyopathy disease by continuously expressing CRISPR/Cas9 protein and atgl gene guide RNAs (gRNAs). The expressed Cas9 protein bound to four gRNAs targeting the atgl gene locus, facilitating systemic gene KO. Ablation of Atgl interfered with lipid metabolism, which induced hyperlipidemia and hyperglycemia. ALKO adults and embryos displayed hypertrophic hearts. ALKO presented a typical dilated cardiomyopathy profile with a remarkable reduction in four sarcomere genes (myosin heavy chain 7-like, actin alpha cardiac muscle 1b, myosin binding protein C3, and troponin T type 2a) and two Ca²⁺ handling regulator genes (tropomyosin 4b and ATPase sarcoplasmic/endoplasmic reticulum Ca²⁺ transporting 2b). Immune cell infiltration in cardiac tissue of ALKO provided direct evidence of advanced metabolic cardiomyopathy. The presently described model could become a powerful tool to clarify the underlying mechanism between metabolic disorders and cardiomyopathies.

Gut Microbiota in Non-Alcoholic Fatty Liver Disease Patients with Inflammatory Bowel Diseases: A Complex Interplay

The intestinal microbiota represents the microbial community that colonizes the gastrointestinal tract and constitutes the most complex ecosystem present in nature. The main intestinal microbial phyla are Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, Fusobacteria, and Verrucromicrobia, with a clear predominance of the two phyla Firmicutes and Bacteroidetes which account for about 90% of the intestinal phyla. Intestinal microbiota alteration, or dysbiosis, has been proven to be involved in the development of various syndromes, such as non-alcoholic fatty liver disease, Crohn's disease, and ulcerative colitis. The present review underlines the most recurrent changes in the intestinal microbiota of patients with NAFLD, Crohn's disease, and ulcerative colitis.

Ellagic acid protects against non-alcoholic fatty liver disease in streptozotocin-diabetic rats by activating AMPK

CONTEXT

Ellagic acid (EA) is used in traditional medicine to treated hyperlipidaemia.

OBJECTIVE

This study examined if AMPK mediates the anti-steatotic effect of ellagic acid (EA) in streptozotocin (STZ)-induced type 1 diabetes mellitus in rats.

MATERIALS AND METHODS

Adult male Wistar rats (130 ± 10 g) were divided into 6 groups (n = 8 rats/group) as control, control + EA, control + EA + CC an AMPK inhibitor), T1DM, T1DM + EA, and T1DM + EA + CC. The treatments with EA (50 mg/kg/orally) and CC (200 ng/rat/i.p.) were given the desired groups for 12 weeks, daily.

RESULTS

In T1DM-rats, EA reduced fasting glucose levels (44.8%), increased fasting insulin levels (92.8%), prevented hepatic lipid accumulation, and decreased hepatic and serum levels of total triglycerides (54% & 61%), cholesterol (57% & 48%), and free fatty acids (40% & 37%). It also reduced hepatic levels of ROS (62%), MDA (52%), TNF-α (62%), and IL-6 (57.2%) and the nuclear activity of NF-κB p65 (54%) but increased the nuclear activity of Nrf-2 (4-fold) and levels of GSH (107%) and SOD (87%). Besides, EA reduced downregulated SREBP1 (35%), SREBP2 (34%), ACC-1 (36%), FAS (38%), and HMG-CoAR (49%) but stimulated mRNA levels of PPARα (1.7-fold) and CPT1a (1.8-fold), CPT1b (2.9-fold), and p-AMPK (4-fold). All these events were prevented by the co-administration of CC.

DISCUSSION AND CONCLUSIONS

These findings encourage the use of EA to treat hepatic disorders, and non-alcoholic fatty liver disease (NAFLD). Further in vivo and in vitro studies are needed to validate its potential in clinical medicine.

Mechanotransduction in the pathogenesis of non-alcoholic fatty liver disease

Mechanobiology is a domain of interdisciplinary research that aims to explore the impact of physical force, applied externally or internally, on cell and tissue function, including development, growth, and differentiation. Mechanotransduction is a term that describes how cells sense physical forces (such as compression, stretch, and shear stress), convert them into biochemical signals, and mount adaptive responses integrated by the nucleus. There is accumulating evidence that mechanical forces extensively inform the biological behaviour of liver cells in health and disease. Recent research has elucidated many cellular and molecular mechanisms involved in this process including the pleiotropic control and diverse effects of the paralogous transcription co-activators YAP/TAZ, which play a prominent role in mechanotransduction. The liver sinusoids represent a unique microenvironment in which cells are exposed to mechanical cues originating in the cytoskeleton and at interfaces with adjacent cells, the extracellular matrix, and vascular or interstitial fluids. In non-alcoholic fatty liver disease (NAFLD), hepatocellular lipid accumulation and ballooning, activation of inflammatory responses, dysfunction of liver sinusoidal endothelial cells, and transdifferentiation of hepatic stellate cells into a pro-contractile and pro-fibrotic phenotype have been associated with aberrant cycles of mechanosensing and mechanoresponses. The downstream consequences of disrupted mechanical homeostasis likely contribute to the progression of NAFLD and promote the development of portal hypertension, cirrhosis, and hepatocellular carcinoma. Identification of molecular targets involved in pathogenic mechanotransduction will allow for the development of novel strategies to prevent the progression of liver disease in NAFLD.

Mechanosensing in macrophages and dendritic cells in steady-state and disease

Macrophages and dendritic cells are myeloid cells that play critical roles in immune responses. Macrophages help to maintain homeostasis through tissue regeneration and the clearance of dead cells, but also mediate inflammatory processes against invading pathogens. As the most potent antigen-presenting cells, dendritic cells are important in connecting innate to adaptive immune responses via activation of T cells, and inducing tolerance under physiological conditions. While it is known that macrophages and dendritic cells respond to biochemical cues in the microenvironment, the role of extracellular mechanical stimuli is becoming increasingly apparent. Immune cell mechanotransduction is an emerging field, where accumulating evidence suggests a role for extracellular physical cues coming from tissue stiffness in promoting immune cell recruitment, activation, metabolism and inflammatory function. Additionally, many diseases such as pulmonary fibrosis, cardiovascular disease, cancer, and cirrhosis are associated with changes to the tissue biophysical environment. This review will discuss current knowledge about the effects of biophysical cues including matrix stiffness, topography, and mechanical forces on macrophage and dendritic cell behavior under steady-state and pathophysiological conditions. In addition, we will also provide insight on molecular mediators and signaling pathways important in macrophage and dendritic cell mechanotransduction.

Gondoic acid alleviates LPS‑induced Kupffer cells inflammation by inhibiting ROS production and PKCθ/ERK/STAT3 signaling pathway

Kupffer cells (KCs) is the main macrophage in liver, and its inflammation is related to liver diseases. It has been shown that inflammatory macrophages are accompanied by changes in monounsaturated fatty acid (MUFA) content. However, the effect of gondoic acid (GA) on inflammation and its underlying mechanism have not been described. In the current study, we demonstrated that GA significantly inhibited the expression of pro-inflammatory factors in LPS-exposed KCs. Further research found that GA reduced lipopolysaccharide (LPS)-stimulated reactive oxygen species (ROS) levels and enhanced the expression of antioxidant genes. Meanwhile, GA obviously blocked the LPS-stimulated PKCθ/ERK/STAT3 signaling pathways to alleviate the inflammatory responses. These results demonstrated for the first time that GA improves KCs inflammation through the inhibition of ROS production and PKCθ/ERK/STAT3 signaling pathway, the results assist in the potential development of functional foods or prodrugs based on the GA rich plant oils.