How Inflammation Impinges on NAFLD: A Role for Kupffer Cells

Engineered Hydrogels for Organoid Models of Human Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by increased lipid accumulation and excessive deposition of extracellular matrix (ECM) that results in tissue stiffening. The potential interplay between matrix stiffness and hepatocyte lipid accumulation during NAFLD has not been established. Here, an in vitro NAFLD model is developed using chemically defined, engineered hydrogels and human induced pluripotent stem cell-derived hepatic organoids (HOs). Specifically, dynamic covalent chemistry crosslinking, along with transient small molecule competitors, are used to create dynamic stiffening hydrogels that enable the reproducible culture of HOs. Within matrices that mimic the stiffness of healthy to diseased tissue (≈1-6 kPa), lipid droplet accumulation in HOs is triggered by exposure to an NAFLD-associated free fatty acid. These NAFLD model suggests that higher stiffness microenvironments result in increased hepatic lipid droplet accumulation, increased expression of fibrosis markers, and increased metabolic dysregulation. By targeting the ROCK mechanosignaling pathway, the synergy between matrix stiffness and lipid droplet accumulation is disrupted. The in vitro model of NAFLD has the potential to understand the role of mechanosignaling in disease progression and identify new pathways for therapeutic intervention.

Fu brick tea supplementation ameliorates non-alcoholic fatty liver disease and associated endotoxemia via maintaining intestinal homeostasis and remodeling hepatic immune microenvironment

Non-alcoholic fatty liver disease (NAFLD) is a prevalent disorder of excessive fat accumulation and inflammation in the liver that currently lacks effective therapeutic interventions. Fu brick tea (FBT) has been shown to ameliorate liver damage and modulate gut microbiota dysbiosis in NAFLD, but the potential mechanisms have not been comprehensively elucidated, especailly whether its hepatoprotective effects are determined to depend on the homeostasis of gut microbiota, intestinal barrier function and hepatic immune microenvironment. In this study, our results further demonstrated that FBT not only alleviated NAFLD symptoms and related endotoxemia in high-fat diet (HFD)-fed rats, but also attenuated intestinal barrier dysfunction and associated inflammation, also confirmed in Caco-2 cell experiment. Meanwhile, FBT intervention significantly relieved HFD-induced gut microbiota dysbiosis, characterized by increased diversity and composition, particularly facilitating beneficial microbes, including short chain fatty acids (SCFAs) and bile acids producers, such as Blautia and Fusicatenibacter, and inhibiting Gram-negative bacteria, such as Prevotella_9 and Phascolarctobacterium. Also, the gut microbiota-dependent hepatoprotective effects of FBT were verified by fecal microbiota transplantation (FMT) experiment. Thus, the beneficial moulation of gut microbiota altered by FBT in levels of SCFAs, bile acids and lipopolysaccharides, intestinal barrier function and TLR4/NF-κB pathway contributed to alleviate liver steatosis and inflammation. Additionally, the hepatoprotective effects of FBT was further demonstrated by suppressing Kupffer cell activation and regulating lipid metabolism using an ex vivo model of liver organoid. Therefore, FBT supplementation can maintain intenstinal homeostasis and remodel hepatic immune microenvironment to prevent NAFLD and associated endotoxemia.

The possible protective effect of luteolin on cardiovascular and hepatic changes in metabolic syndrome rat model

The metabolic syndrome, or MetS, is currently a global health concern. The anti-inflammatory, anti-proliferative, and antioxidant properties of luteolin are some of its advantageous pharmacological characteristics. This research was designed to establish a MetS rat model and investigate the possible protective effect of luteolin on cardiovascular, hepatic, and metabolic changes in diet-induced metabolic syndrome in rats. Forty adult male albino rats were split into four groups: a negative control group, a group treated with luteolin, a group induced MetS (fed 20% fructose), and a group treated with luteolin (fed 20% fructose and given luteolin). Following the experiment after 8 weeks, biochemical, histological (light and electron), and immunohistochemistry analyses were performed on liver and heart tissues. Serum levels of cTnI, CK-MB, and LDH were significantly elevated in response to the cardiovascular effect of MetS. Furthermore, compared to the negative control group, the MetS group showed a marked increase in lipid peroxidation in the cardiac and hepatic tissues, as evidenced by elevated levels of MDA and a decline in the antioxidant defense system, as demonstrated by lower activities of GSH and SOD. The fatty liver-induced group exhibited histological alterations, including disrupted hepatic architecture, dilated and congested central veins, blood sinusoids, and portal veins. In addition to nuclear structural alterations, most hepatocytes displayed varying degrees of cytoplasmic vacuolation, mitochondrial alterations, and endoplasmic reticulum dilatation. These alterations were linked to inflammatory cellular infiltrations, collagen fiber deposition, active hepatic stellate cells, and scattered hypertrophied Kupffer cells, as demonstrated by electron microscopy and validated by immunohistochemical analysis. It is interesting to note that eosinophils were seen between the liver cells and in dilated blood sinusoids. Moreover, the biochemical (hepatic and cardiac) and histological (liver) changes were significantly less severe in luteolin-treated rat on a high-fructose diet. These results suggested that luteolin protects against a type of metabolic syndrome that is produced experimentally.

Fermented Gold Kiwifruit Protects Mice Against Non-Alcoholic Fatty Liver Disease in a High-Fat Diet Model

Gold kiwifruit is known for its high vitamin C content and various benefits. This study investigated the effects and molecular mechanisms of fermented gold kiwifruit (FGK) in a mouse model of high-fat diet (HFD)-induced obesity and hepatic steatosis. FGK powder was prepared using five strains of lactic acid bacteria: L. paracasei, Lc. lactis, L. acidophilus, L. casei, and L. helveticus. ICR mice were fed an HFD for 8 weeks to induce obesity and hepatic steatosis, and FGK supplementation was evaluated for its therapeutic potential. FGK administration significantly reduced serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol, triglyceride, and glucose compared to the HFD-only group. Histopathological analysis showed that FGK reduced lipid accumulation and hepatic lesions, as confirmed by hematoxylin and eosin (H&E) staining. Furthermore, administration of FGK activated the sirtuin 1(SIRT1)/adenosine monophosphate-activated protein kinase (AMPK) pathway and inhibited expression of the pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α in liver tissue. These findings suggest that FGK could reduce the severity of non-alcoholic fatty liver disease (NAFLD) by inhibiting fat synthesis, promoting fat breakdown, and suppressing inflammation in HFD-induced obese mice.

Immunological dynamics in MASH: from landscape analysis to therapeutic intervention

Metabolic dysfunction-associated steatohepatitis (MASH), previously known as nonalcoholic steatohepatitis (NASH), is a multifaceted liver disease characterized by inflammation and fibrosis that develops from simple steatosis. Immune and inflammatory pathways have a central role in the pathogenesis of MASH, yet, how to target immune pathways to treat MASH remains perplexed. This review emphasizes the intricate role that immune cells play in the etiology and pathophysiology of MASH and highlights their significance as targets for therapeutic approaches. It discusses both current strategies and novel therapies aimed at modulating the immune response in MASH. It also highlights challenges in liver-specific drug delivery, potential off-target effects, and difficulties in targeting diverse immune cell populations within the liver. This review is a comprehensive resource that integrates current knowledge with future perspectives in the evolving field of MASH, with the goal of driving forward progress in medical therapies designed to treat this complex liver disease.

Tenovin-1, a Selective SIRT1/2 Inhibitor, Attenuates High-fat Diet-induced Hepatic Fibrosis via Inhibition of HSC Activation in ZDF Rats

Type 2 diabetes mellitus (T2DM) increases the risk of non-alcoholic fatty liver disease (NAFLD) progression to advanced stages, especially upon high-fat diet (HFD). HFD-induced hepatic fibrosis can be marked by oxidative stress, inflammation, and activation of hepatic stellate cells. Sirtuin 1/2 (SIRT1/2), NAD-dependent class III histone deacetylases, are involved in attenuation of fibrosis. In our conducted research, TGF-β1-activated LX-2 cells, free fatty acid (FFA)-treated simultaneous co-culture (SCC) cells, and HFD-induced hepatic fibrosis in Zucker diabetic fatty (ZDF) rats, a widely used animal model in the study of metabolic syndromes, were used to evaluate the protective effect of Tenovin-1, a SIRT1/2 inhibitor. ZDF rats were divided into chow diet, HFD, and HFD + Tenovin-1 groups. Tenovin-1 reduced hepatic damage, inhibited inflammatory cell infiltration, micro/ macro-vesicular steatosis and prevented collagen deposition HFD-fed rats. Tenovin-1 reduced serum biochemical parameters, triglyceride (TG) and malondialdehyde (MDA) levels but increased glutathione, catalase, and superoxide dismutase levels. Tenovin-1 mitigated proinflammatory cytokines IL-6, IL-1β, TNFα and fibrosis biomarkers in HFD rats, TGF-β1-activated LX-2 and FFA treated SCC cells. Additionally, Tenovin-1 suppressed SIRT1/2 expression and inhibited JNK-1 and STAT3 phosphorylation in HFD rats and FFA-treated SCC cells. In conclusion, Tenovin-1 attenuates hepatic fibrosis by stimulating antioxidants and inhibiting inflammatory cytokines under HFD conditions in diabetic rats.

Assessing Causal Relationships Between Periodontitis and Non-alcoholic Fatty Liver Disease: A Two-Sample Bidirectional Mendelian Randomisation Study

PURPOSE

To investigate the causality between periodontitis and non-alcoholic fatty liver disease (NAFLD) using a two-sample bidirectional Mendelian randomisation (MR) analysis.

MATERIALS AND METHODS

Genetic variations in periodontitis and NAFLD were acquired from genome-wide association studies (GWAS) using the Gene-Lifestyle Interaction in Dental Endpoints, a large-scale meta-analysis, and FinnGen consortia. Data from the first two databases were used to explore the causal relationship between periodontitis and NAFLD ("discovery stage"), and the data from FinnGen was used to validate our results ("validation stage"). We initially performed MR analysis using 5 single nucleotide polymorphisms (SNPs) in the discovery samples and 18 in the replicate samples as genetic instruments for periodontitis to investigate the causative impact of periodontitis on NAFLD. We then conducted a reverse MR analysis using 6 SNPs in the discovery samples and 4 in the replicate samples as genetic instruments for NAFLD to assess the causative impact of NAFLD on periodontitis. We further implemented heterogeneity and sensitivity analyses to assess the reliability of the MR results.

RESULTS

Periodontitis was not causally related to NAFLD (odds ratio [OR] = 1.036, 95% CI: 0.914-1.175, p = 0.578 in the discovery stage; OR = 1.070, 95% CI: 0.935-1.224, p = 0.327 in the validation stage), and NAFLD was not causally linked with periodontitis (OR = 1.059, 95% CI: 0.916-1.225, p = 0.439 in the discovery stage; OR = 0.993, 95% CI: 0.896-1.102, p = 0.901 in the validation stage). No heterogeneity was observed among the selected SNPs. Sensitivity analyses demonstrated the absence of pleiotropy and the reliability of our MR results.

CONCLUSION

The present MR analysis showed no genetic evidence for a cause-and-effect relationship between periodontitis and NAFLD. Periodontitis may not directly influence the development of NAFLD and vice versa.

Proteomic Profiling of Plasma- and Gut-Derived Extracellular Vesicles in Obesity

Obesity entails metabolic alterations across multiple organs, highlighting the role of inter-organ communication in its pathogenesis. Extracellular vesicles (EVs) are communication agents in physiological and pathological conditions, and although they have been associated with obesity comorbidities, their protein cargo in this context remains largely unknown. To decipher the messages encapsulated in EVs, we isolated plasma-derived EVs from a diet-induced obese murine model. Obese plasma EVs exhibited a decline in protein diversity while control EVs revealed significant enrichment in protein-folding functions, highlighting the importance of proper folding in maintaining metabolic homeostasis. Previously, we revealed that gut-derived EVs' proteome holds particular significance in obesity. Here, we compared plasma and gut EVs and identified four proteins exclusively present in the control state of both EVs, revealing the potential for a non-invasive assessment of gut health by analyzing blood-derived EVs. Given the relevance of post-translational modifications (PTMs), we observed a shift in chromatin-related proteins from glycation to acetylation in obese gut EVs, suggesting a regulatory mechanism targeting DNA transcription during obesity. This study provides valuable insights into novel roles of EVs and protein PTMs in the intricate mechanisms underlying obesity, shedding light on potential biomarkers and pathways for future research.

Immunomodulation in non-alcoholic fatty liver disease: exploring mechanisms and applications

Non-alcoholic fatty liver disease (NAFLD) exhibits increased lipid enrichment in hepatocytes. The spectrum of this disease includes stages such as nonalcoholic simple fatty liver (NAFL), nonalcoholic steatohepatitis (NASH), and liver fibrosis. Changes in lifestyle behaviors have been a major factor contributing to the increased cases of NAFLD patients globally. Therefore, it is imperative to explore the pathogenesis of NAFLD, identify therapeutic targets, and develop new strategies to improve the clinical management of the disease. Immunoregulation is a strategy through which the organism recognizes and eliminates antigenic foreign bodies to maintain physiological homeostasis. In this process, multiple factors, including immune cells, signaling molecules, and cytokines, play a role in governing the evolution of NAFLD. This review seeks to encapsulate the advancements in research regarding immune regulation in NAFLD, spanning from underlying mechanisms to practical applications.

Dietary inflammatory potential is associated with higher odds of hepatic steatosis in US adults: a cross-sectional study

OBJECTIVE

Inflammation plays a critical role in the progression of chronic liver diseases, and diet can modulate inflammation. Whether an inflammatory dietary pattern is associated with higher risk of hepatic steatosis or fibrosis remains unclear. We aimed to investigate the associations between inflammatory dietary pattern and the odds of hepatic steatosis and fibrosis.

DESIGN

In this nationwide cross-sectional study, diet was measured using two 24-h dietary recalls. Empirical dietary inflammatory pattern (EDIP) score was derived to assess the inflammatory potential of usual diet, which has been validated to highly predict inflammation markers in the study population. Controlled attenuation parameter (CAP) and liver stiffness measurement (LSM) were derived from FibroScan to define steatosis and fibrosis, respectively.

SETTING

US National Health and Nutrition Examination Survey.

PARTICIPANTS

4171 participants aged ≥18 years.

RESULTS

A total of 1436 participants were diagnosed with S1 steatosis (CAP ≥ 274 dB/m), 255 with advanced fibrosis (LSM ≥ 9·7 kPa). Compared with those in the lowest tertile of EDIP-adherence scores, participants in the highest tertile had 74 % higher odds of steatosis (OR: 1·74, 95 % CI (1·26, 2·41)). Such positive association persisted among never drinkers, or participants who were free of hepatitis B and/or C. Similarly, EDIP was positively associated with CAP in multivariate linear model (P < 0·001). We found a non-significant association of EDIP score with advanced fibrosis or LSM (P = 0·837).

CONCLUSIONS

Our findings suggest that a diet score that is associated with inflammatory markers is associated with hepatic steatosis. Reducing or avoiding pro-inflammatory diets intake might be an attractive strategy for fatty liver disease prevention.

Hepatic Macrophages as Targets for the MSC-Based Cell Therapy in Non-Alcoholic Steatohepatitis

Non-alcoholic steatohepatitis (NASH) is a serious public health issue associated with the obesity pandemic. Obesity is the main risk factor for the non-alcoholic fatty liver disease (NAFLD), which progresses to NASH and then to end-stage liver disease. Currently, there are no specific pharmacotherapies of NAFLD/NASH approved by the FDA or other national regulatory bodies and the treatment includes lifestyle adjustment and medicines for improving lipid metabolism, enhancing sensitivity to insulin, balancing oxidation, and counteracting fibrosis. Accordingly, further basic research and development of new therapeutic approaches are greatly needed. Mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles prevent induced hepatocyte death in vitro and attenuate NASH symptoms in animal models of the disease. They interact with hepatocytes directly, but also target other liver cells, including Kupffer cells and macrophages recruited from the blood flow. This review provides an update on the pathogenesis of NAFLD/NASH and the key role of macrophages in the development of the disease. We examine in detail the mechanisms of the cross-talk between the MSCs and the macrophages, which are likely to be among the key targets of MSCs and their derivatives in the course of NAFLD/NASH cell therapy.

A novel combination of metformin and resveratrol alleviates hepatic steatosis by activating autophagy through the cAMP/AMPK/SIRT1 signaling pathway

Nonalcoholic fatty liver disease (NAFLD) is a prevalent liver disorder that is associated with the accumulation of triglycerides (TG) in hepatocytes. Resveratrol (RSV), as a natural product, and metformin have been reported to have potential lipid-lowering effects for the treatment of NAFLD via autophagy, but the combined effects of both have not yet been studied. The current study aimed to investigate the role of autophagy in the lipid-lowering effects of RSV, alone and in combination with metformin, on the hepatic steatosis model of HepG2 cells and elucidate the mechanism of action. Triglyceride measurement and real-time PCR showed that RSV-metformin reduced lipid accumulation and the expression of lipogenic genes in palmitic acid (PA)-induced HepG2 cells. Additionally, the LDH release assay indicated that this combination protected HepG2 cells against PA-induced cell death through autophagy. The western blotting analysis revealed that RSV-metformin induced autophagy by reducing the expression of p62 and increasing LC3-I and LC3-II proteins. This combination also enhanced cAMP, phosphorylated AMP-activated protein kinase (p-AMPK), and Beclin-1 levels in HepG2 cells. Furthermore, SIRT1 inhibitor treatment inhibited autophagy induced by RSV-metformin, which indicated the autophagy induction is SIRT1-dependent. This study demonstrated for the first time that RSV-metformin reduced hepatic steatosis by triggering autophagy via the cAMP/AMPK/SIRT1 signaling pathway.

Advances in the pharmacological effects and molecular mechanisms of emodin in the treatment of metabolic diseases

Rhubarb palmatum L., Polygonum multijiorum Thunb., and Polygonum cuspidatum Sieb. Et Zucc. are traditional Chinese medicines that have been used for thousands of years. They are formulated into various preparations and are widely used. Emodin is a traditional Chinese medicine monomer and the main active ingredient in Rhubarb palmatum L., Polygonum multijiorum Thunb., and Polygonum cuspidatum Sieb. Et Zucc. Modern research shows that it has a variety of pharmacological effects, including promoting lipid and glucose metabolism, osteogenesis, and anti-inflammatory and anti-autophagy effects. Research on the toxicity and pharmacokinetics of emodin can promote its clinical application. This review aims to provide a basis for further development and clinical research of emodin in the treatment of metabolic diseases. We performed a comprehensive summary of the pharmacology and molecular mechanisms of emodin in treating metabolic diseases by searching databases such as Web of Science, PubMed, ScienceDirect, and CNKI up to 2023. In addition, this review also analyzes the toxicity and pharmacokinetics of emodin. The results show that emodin mainly regulates AMPK, PPAR, and inflammation-related signaling pathways, and has a good therapeutic effect on obesity, hyperlipidemia, non-alcoholic fatty liver disease, diabetes and its complications, and osteoporosis. In addition, controlling toxic factors and improving bioavailability are of great significance for its clinical application.

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.

Extracellular vesicle-mediated protein delivery to the liver

Extracellular vesicles (EVs) are nanoscale particles that facilitate intercellular communication. They are regarded as a promising natural drug delivery system for transporting and delivering bioactive macromolecules to target cells. Recently, researchers have engineered EVs with FKBP12/FRB heterodimerization domains that interact with rapamycin to load and deliver exogenous proteins for both in vitro and in vivo applications. In this study, we examined the tissue distribution of EVs using near-infrared fluorescent imaging. We evaluated the effectiveness of EV-mediated delivery of Cre recombinase specifically to hepatocytes in the livers of Ai9 Cre-loxP reporter mice. Intravenous injection resulted in more efficient Cre protein delivery to the liver than intraperitoneal injections. Depleting liver-resident macrophages with clodronate-encapsulated liposome pre-treatment did not enhance EV-mediated Cre delivery to hepatocytes. Moreover, we demonstrated that multiple intravenous injections of Cre-EVs facilitated functional Cre delivery to hepatocytes. To the best of our knowledge, this is the first study to simultaneously investigate the tissue distribution of FKBP12/FRB-engineered EVs and their subsequent intracellular protein delivery in Ai9 Cre-loxP reporter mice. These insights can inform preclinical research and contribute to developing next-generation EV-based platforms for delivering therapeutic proteins or genome editing technologies targeting the liver.

Cellular heterogeneity and plasticity during NAFLD progression

Nonalcoholic fatty liver disease (NAFLD) is a progressive liver disease that can progress to nonalcoholic steatohepatitis (NASH), NASH-related cirrhosis, and hepatocellular carcinoma (HCC). NAFLD ranges from simple steatosis (or nonalcoholic fatty liver [NAFL]) to NASH as a progressive form of NAFL, which is characterized by steatosis, lobular inflammation, and hepatocellular ballooning with or without fibrosis. Because of the complex pathophysiological mechanism and the heterogeneity of NAFLD, including its wide spectrum of clinical and histological characteristics, no specific therapeutic drugs have been approved for NAFLD. The heterogeneity of NAFLD is closely associated with cellular plasticity, which describes the ability of cells to acquire new identities or change their phenotypes in response to environmental stimuli. The liver consists of parenchymal cells including hepatocytes and cholangiocytes and nonparenchymal cells including Kupffer cells, hepatic stellate cells, and endothelial cells, all of which have specialized functions. This heterogeneous cell population has cellular plasticity to adapt to environmental changes. During NAFLD progression, these cells can exert diverse and complex responses at multiple levels following exposure to a variety of stimuli, including fatty acids, inflammation, and oxidative stress. Therefore, this review provides insights into NAFLD heterogeneity by addressing the cellular plasticity and metabolic adaptation of hepatocytes, cholangiocytes, hepatic stellate cells, and Kupffer cells during NAFLD progression.

Water-soluble protein from walleye pollock (Gadus chalcogrammus) suppresses lipopolysaccharide-induced inflammation by attenuating TLR4-MyD88 expression in macrophages

Water-soluble protein (WSP) from fish meat is abundant in the waste effluent generated via the surimi manufacturing process. This study investigated the anti-inflammatory effects and mechanisms of fish WSP using primary macrophages (MΦ) and animal ingestion. MΦ were treated with digested-WSP (d-WSP, 500 µg/mL) with or without lipopolysaccharide (LPS) stimulation. For the ingestion study, male ICR mice (5 weeks old) were fed 4% WSP for 14 days following LPS administration (4 mg/kg body weight). d-WSP decreased the expression of Tlr4, an LPS receptor. Additionally, d-WSP significantly suppressed the secretion of inflammatory cytokines, phagocytic ability, and Myd88 and Il1b expressions of LPS-stimulated macrophages. Furthermore, the ingestion of 4% WSP attenuated not only LPS-induced IL-1β secretion in the blood but also Myd88 and Il1b expressions in the liver. Thus, fish WSP decreases the expressions of the genes involved in the TLR4-MyD88 pathway in MΦ and the liver, thereby suppressing inflammation.

The Prophylactic Effect of Vitamin C and Vitamin B12 against Ultraviolet-C-Induced Hepatotoxicity in Male Rats

Ultraviolet C (UVC) devices are an effective means of disinfecting surfaces and protecting medical tools against various microbes, including coronavirus. Overexposure to UVC can induce oxidative stress, damage the genetic material, and harm biological systems. This study investigated the prophylactic efficacy of vitamin C and B12 against hepatotoxicity in UVC-intoxicated rats. Rats were irradiated with UVC (725.76, 967.68, and 1048.36 J/cm²) for 2 weeks. The rats were pretreated with the aforementioned antioxidants for two months before UVC irradiation. The prophylactic effect of vitamins against UVC hepatotoxicity was evaluated by monitoring the alteration of liver enzyme activities, antioxidant status, apoptotic and inflammatory markers, DNA fragmentation, and histological and ultrastructural alterations. Rats exposed to UVC showed a significant increase in liver enzymes, oxidant-antioxidant balance disruption, and increased hepatic inflammatory markers (TNF-α, IL-1β, iNOS, and IDO-1). Additionally, obvious over-expression of activated caspase-3 protein and DNA fragmentation were detected. Histological and ultrastructural examinations verified the biochemical findings. Co-treatment with vitamins ameliorated the deviated parameters to variable degrees. In conclusion, vitamin C could alleviate UVC-induced hepatotoxicity more than vitamin B12 by diminishing oxidative stress, inflammation, and DNA damage. This study could provide a reference for the clinical practice of vitamin C and B12 as radioprotective for workers in UVC disinfectant areas.

Innate Immune System in the Pathogenesis of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a prevalent condition characterized by lipid accumulation in hepatocytes with low alcohol consumption. The development of sterile inflammation, which occurs in response to a range of cellular stressors or injuries, has been identified as a major contributor to the pathogenesis of NAFLD. Recent studies of the pathogenesis of NAFLD reported the newly developed roles of damage-associated molecular patterns (DAMPs). These molecules activate pattern recognition receptors (PRRs), which are placed in the infiltrated neutrophils, dendritic cells, monocytes, or Kupffer cells. DAMPs cause the activation of PRRs, which triggers a number of immunological responses, including the generation of cytokines that promote inflammation and the localization of immune cells to the site of the damage. This review provides a comprehensive overview of the impact of DAMPs and PRRs on the development 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.

Clonal population expansion of Staphylococcus aureus occurs due to escape from a finite number of intraphagocyte niches

Staphylococcus aureus is a human commensal and also an opportunist pathogen causing life threatening infections. During S. aureus disease, the abscesses that characterise infection can be clonal, whereby a large bacterial population is founded by a single or few organisms. Our previous work has shown that macrophages are responsible for restricting bacterial growth such that a population bottleneck occurs and clonality can emerge. A subset of phagocytes fail to control S. aureus resulting in bacterial division, escape and founding of microabscesses that can seed other host niches. Here we investigate the basis for clonal microabscess formation, using in vitro and in silico models of S. aureus macrophage infection. Macrophages that fail to control S. aureus are characterised by formation of intracellular bacterial masses, followed by cell lysis. High-resolution microscopy reveals that most macrophages had internalised only a single S. aureus, providing a conceptual framework for clonal microabscess generation, which was supported by a stochastic individual-based, mathematical model. Once a threshold of masses was reached, increasing the number of infecting bacteria did not result in greater mass numbers, despite enhanced phagocytosis. This suggests a finite number of permissive, phagocyte niches determined by macrophage associated factors. Increased understanding of the parameters of infection dynamics provides avenues for development of rational control measures.

Association between Sarcopenic Obesity Status and Nonalcoholic Fatty Liver Disease and Fibrosis

Background/Aims

There are no data regarding the association between sarcopenic obesity status and nonalcoholic fatty liver disease (NAFLD) and NAFLD-associated liver fibrosis. Therefore, we aimed to investigate the relationship between sarcopenic obesity status (sarcopenia only, obesity only, and sarcopenic obesity) and NAFLD and liver fibrosis in Korean adults.

Methods

In total, 2,191 subjects completed a health checkup program, including abdominal ultrasonography and FibroScan. Subjects were classified into the following four categories: optimal body composition (nonobese and nonsarcopenic), sarcopenia only (nonobese), obesity only (nonsarcopenic), and sarcopenic obesity. Sarcopenic obesity was stratified by the skeletal muscle mass index and body fat using bioelectrical impedance analysis. NAFLD was diagnosed by ultrasonography, and liver fibrosis was assessed using transient elastography in subjects with NAFLD.

Results

The prevalence of NAFLD and liver fibrosis significantly increased according to the sarcopenic obesity status. In the logistic regression analysis, after adjusting for multiple risk factors, the odds ratio (OR) for the risk of NAFLD was largest in the sarcopenic obesity group (OR, 3.68; 95% confidence interval [CI], 2.94 to 4.60), followed by the obesity only (OR, 2.25; 95% CI, 1.67 to 3.03) and sarcopenia only (OR, 1.92; 95% CI, 1.30 to 2.84) groups, when compared with the optimal group. Additionally, liver fibrosis was independently associated with sarcopenic obesity status (OR 4.69, 95% CI 1.95 to 11.29; OR 4.17, 95% CI 1.56 to 11.17; OR 3.80, 95% CI 0.86 to 16.75, respectively).

Conclusions

These results demonstrated that sarcopenic obesity was independently associated with NAFLD and liver fibrosis and increased the risk of NAFLD and liver fibrosis more than obesity or sarcopenia alone.

Increased Hepatic ATG7 mRNA and ATG7 Protein Expression in Nonalcoholic Steatohepatitis Associated with Obesity

The autophagy gene ATG7 has been shown to be essential for the induction of autophagy, a process that used to be suppressed in nonalcoholic fatty liver disease (NAFLD). However, the specific role of ATG7 in NAFLD remains unclear. The aim of this study was to analyze hepatic ATG7 mRNA and ATG7 protein expression regarding obesity-associated NAFLD. Patients included women classified into normal weight (NW, n = 6) and morbid obesity (MO, n = 72). The second group was subclassified into normal liver (NL, n = 11), simple steatosis (SS, n= 29), and nonalcoholic steatohepatitis (NASH, n = 32). mRNA expression was analyzed by RT-qPCR and protein expression was evaluated by Western blotting. Our results showed that NASH patients presented higher ATG7 mRNA and ATG7 protein levels. ATG7 mRNA expression was increased in NASH compared with SS, while ATG7 protein abundance was enhanced in NASH compared with NL. ATG7 mRNA correlated negatively with the expression of some hepatic lipid metabolism-related genes and positively with endocannabinoid receptors, adiponectin hepatic expression, and omentin levels. These results suggest that ATG7-mediated autophagy may play an important role in the pathogenesis of NAFLD, especially in NASH, perhaps playing a possible protective role. However, this is a preliminary study that needs to be further studied.

Hepatic Steatosis Alleviated by a Novel Metformin and Quercetin Combination Activating Autophagy Through the cAMP/AMPK/SIRT1 Pathway

Non-alcoholic fatty liver disease (NAFLD) incidence and prevalence are rapidly increasing globally. The combined effects of metformin and quercetin (Que) have yet to be investigated. However, both have demonstrated the potential to reduce triglyceride (TG) levels and treat NAFLD by promoting autophagy. The objective of the present study was to elucidate the mechanism of action and assess the role of autophagy in the lipid-lowering effects of Que, both individually and in combination with metformin, in a HepG2 cell model of hepatic steatosis. Triglyceride levels and lipogenic gene expression were reduced in HepG2 cells exposed to palmitic acid (PA) when treated with Que-metformin, as evidenced by triglyceride measurements and real-time PCR. The LDH release assay also showed that this combination induced autophagy to protect HepG2 cells from PA-induced cell death. According to the Western blot analysis outcomes, Que-metformin increased LC3-I and LC3-II protein levels while decreasing p62 expression to induce autophagy. In HepG2 cells, the co-administration of Que-metformin elevated cAMP, phosphorylated AMP-activated protein kinase (p-AMPK), and Beclin-1 levels. Additionally, the inhibition of SIRT1 reversed the autophagy induced by Que-metformin. The findings of this study demonstrated for the first time that Que-metformin reduced hepatosteatosis by stimulating autophagy through the cAMP/AMPK/SIRT1 signaling pathway and diminishing inflammatory cytokines.

Effect of lifelong sucrose consumption at human-relevant levels on food intake and body composition of C57BL/6N mice

Introduction

Controversies surround the issue if chronic consumption of a high-sugar diet is detrimental to health or not. This study investigates whether lifelong consumption of a higher sucrose diet will induce overeating, and obesity, and cause metabolic dysfunctions such as hyperglycemia and dyslipidaemia in C57BL/6N mice, compared to a lower sucrose diet.

Methods

Male C57BL/6N mice at 3 weeks of age were randomized into consuming a diet with 25 or 10% kcal from sucrose for the rest of their lives. Body weight, food and water intake, fasting blood glucose, insulin, and lipid levels were measured at regular intervals. At the end of the study, organs and tissues were collected and gene expression was measured.

Results

There was no discernible difference in the impact on food intake, body composition, glucose and lipid homeostasis, liver triglyceride content, life expectancy, as well as gene expression related to intermediary metabolism between mice fed a diet with 10 vs. 25% kcal as sucrose over their lifespan. We also showed that switching from a 25% kcal diet to a 10% kcal diet at different life stages, or vice versa, did not appear to affect these outcomes of interest.

Discussion

The results from our study suggest that lifelong consumption of a higher sugar diet generally did not induce overeating and obesity, disrupt carbohydrate metabolism and lipid homeostasis, and reduce life expectancy compared with a lower sugar diet. Our unorthodox findings disagreed with the popular belief that higher sugar consumption is detrimental to health, which should be confirmed in future studies.

Significant positive impact of duodenum-preserving pancreatic head resection on the prevention of postoperative nonalcoholic fatty liver disease and acute cholangitis

Aim

This study aimed to compare the incidence of postoperative nonalcoholic fatty liver disease (NAFLD), postoperative cholangitis, and fibrosis-4 (FIB)-4 index in patients who underwent duodenum-preserving pancreatic head resection (DPPHR) and pancreaticoduodenectomy (PD) for low-grade malignant tumors and verify the usefulness of DPPHR in preventing the occurrence of these disorders.

Methods

This retrospective study included 70 patients who underwent PD (n = 39) and DPPHR (n = 31) between 2006 and 2018 for benign or low-grade malignant tumors. The present study compared the preoperative background, cumulative incidence of postoperative NAFLD and cholangitis, and other biochemical markers, including the FIB-4 index. Subanalysis by propensity score matching (PSM) analysis was conducted to minimize treatment selection bias.

Results

In terms of the cumulative incidence of NAFLD, the 5-y incidence was significantly lower in the DPPHR group than in the PD group both before (10% vs 38%, P = .002) and after (13% vs 38%, P = .008) matching. Multivariate analyses identified DPPHR as the only independent preventive factor for postoperative NAFLD (hazard ratio: 0.160, 95% confidence intervals: 0.034-0.76, P = .021). The 5-y cumulative incidence of postoperative cholangitis was significantly higher in the PD group than in the DPPHR group before (51% vs 3%, P < .001) and after (49% vs 4%, P < .001) matching. The FIB-4 index at 12 mo postoperatively was significantly better in the DPPHR group than in the PD group (1.45 vs 2.35, P = .006) before matching.

Conclusion

Preservation of the duodenum and bile duct may contribute to preventing long-term postoperative NAFLD and cholangitis, and liver fibrosis for benign or low-grade malignant pancreatic head tumors.

Protective effects and mechanisms of Lizhong decoction against non-alcoholic fatty liver disease in a rat model

OBJECTIVE

To investigate the protective effects and molecular mechanisms of Lizhong decoction (, LZD) against non-alcoholic fatty liver disease (NAFLD).

METHODS

Male Wistar rats were fed a high-fat diet for four weeks to induce NAFLD, and were administered LZD by gavage for four weeks. Potential therapeutic targets for NAFLD were analyzed using network pharmacology. Liver pathology was evaluated using Oil Red O and hematoxylin-eosin staining. Furthermore, mitochondrial function, lipid metabolism, oxidative stress, and inflammatory response were examined.

RESULTS

Rats with NAFLD exhibited high levels of hepatic damage and cholesterol deposition. Moreover, apoptosis was increased, superoxide dismutase and glutathione content were reduced, malondialdehyde content was increased, and the protein expression of inflammatory cytokines and p-c-Jun N-terminal kinase was increased. The LZD treatment ameliorated mitochondrial dysfunction, reduced liver damage, inhibited oxidative stress and inflammatory response, upregulated peroxisome proliferator-activated receptor (PPAR)-γ expression, and suppressed dipeptidyl peptidase 4 (DPP4) expression in the liver.

CONCLUSION

It was found that LZD alleviates NAFLD by activating PPAR-γ and inhibiting DPP4.

Autophagy Dysregulation in Metabolic Associated Fatty Liver Disease: A New Therapeutic Target

Metabolic associated fatty liver disease (MAFLD) is one of the most common causes of chronic liver disease worldwide. To date, there is no FDA-approved treatment, so there is an urgent need to determine its pathophysiology and underlying molecular mechanisms. Autophagy is a lysosomal degradation pathway that removes damaged organelles and misfolded proteins after cell injury through endoplasmic reticulum stress or starvation, which inhibits apoptosis and promotes cell survival. Recent studies have shown that autophagy plays an important role in removing lipid droplets from hepatocytes. Autophagy has also been reported to inhibit the production of pro-inflammatory cytokines and provide energy for the hepatic stellate cells activation during liver fibrosis. Thyroid hormone, irisin, melatonin, hydrogen sulfide, sulforaphane, DA-1241, vacuole membrane protein 1, nuclear factor erythroid 2-related factor 2, sodium-glucose co-transporter type-2 inhibitors, immunity-related GTPase M, and autophagy-related gene 7 have been reported to ameliorate MAFLD via autophagic induction. Lipid receptor CD36, SARS-CoV-2 Spike protein and leucine aminopeptidase 3 play a negative role in the autophagic function. This review summarizes recent advances in the role of autophagy in MAFLD. Autophagy modulates major pathological changes, including hepatic lipid metabolism, inflammation, and fibrosis, suggesting the potential of modulating autophagy for the treatment of MAFLD.

Paying the Iron Price: Liver Iron Homeostasis and Metabolic Disease

Iron is an essential metal element whose bioavailability is tightly regulated. Under normal conditions, systemic and cellular iron homeostases are synchronized for optimal function, based on the needs of each system. During metabolic dysfunction, this synchrony is lost, and markers of systemic iron homeostasis are no longer coupled to the iron status of key metabolic organs such as the liver and adipose tissue. The effects of dysmetabolic iron overload syndrome in the liver have been tied to hepatic insulin resistance, nonalcoholic fatty liver disease, and nonalcoholic steatohepatitis. While the existence of a relationship between iron dysregulation and metabolic dysfunction has long been acknowledged, identifying correlative relationships is complicated by the prognostic reliance on systemic measures of iron homeostasis. What is lacking and perhaps more informative is an understanding of how cellular iron homeostasis changes with metabolic dysfunction. This article explores bidirectional relationships between different proteins involved in iron homeostasis and metabolic dysfunction in the liver. © 2022 American Physiological Society. Compr Physiol 12:3641-3663, 2022.

Extracellular Vesicles in Pathogenesis and Treatment of Metabolic Associated Fatty Liver Disease

Metabolic associated fatty liver disease (MAFLD) is the most common chronic liver disease worldwide due to the sedentary and overeating lifestyle. Yet, the pathophysiology of MAFLD is still unclear and no drug has been approved for MAFLD treatment. Extracellular vesicles (EVs) are heterogenous membrane-bound particles released from almost all types of cells. These nano-sized particles mediate intercellular communication through their bioactive cargos including nucleic acids, proteins, and lipids. The EVs modulate metabolic homeostasis via communication between adipose tissue and liver. The dysregulation of lipid metabolism leads to inflammation in liver and the number and compounds of EVs are changed during MAFLD. The injured hepatocytes secrete EVs to induce the migration of bone marrow-derived monocytes and the activation of macrophages in liver. The EVs secreted by different cells regulate the alteration of hepatic stellate cell (HSC) phenotypes and HSC activation gives rise to liver fibrosis. Based on the participation of EVs in MAFLD progression, we discuss the prospects of EVs as a therapeutic target and their application in drug delivery.

Efficacy of omega-3-rich Camelina sativa on the metabolic and clinical markers in nonalcoholic fatty liver disease: a randomized, controlled trial

OBJECTIVE

Recently, omega-3 fatty acids and antioxidants co-supplementation was considered as alternative treatment in the management of nonalcoholic fatty liver disease (NAFLD). This trial evaluated effects of Camelina sativa oil (CSO) as a rich source of omega-3 fatty acids and antioxidants on anthropometric indices, lipid profile, liver enzymes, and adiponectin in NAFLD patients.

PARTICIPANTS AND METHODS

This triple-blind, placebo-controlled, randomized clinical trial was conducted on 46 NAFLD patients who were randomly assigned to either a CSO supplement or placebo for 12 weeks. Both groups received a loss weight diet. Levels of liver enzymes, adiponectin, lipid profile, atherogenic index, and anthropometric indices were assessed for all patients at baseline and post-intervention.

RESULTS

CSO caused significant differences in weight, BMI, waist circumference, waist-to-hip ratio, triglyceride, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), TC/HDL-c, LDL-c/HDL-c, atherogenic index, alanine aminotransferase, and adiponectin concentrations in the CSO group compared with the placebo group (P < 0.046 for all). No significant differences were found in hip circumference, neck circumference, HDL-c, and other liver enzymes in the CSO group compared with the placebo group (P = 0.790, P = 0.091, P = 0.149, P < 0.159 for liver enzymes, respectively).

DISCUSSION AND CONCLUSION

This study showed that CSO supplementation for 12 weeks causes significant changes in all of anthropometric indices (except hip circumference and neck circumference), ALT, lipid profile (except HDL-c), atherogenic index, and adiponectin in NAFLD patients.

Mesenchymal Stromal/Stem Cells and Their Extracellular Vesicles Application in Acute and Chronic Inflammatory Liver Diseases: Emphasizing on the Anti-Fibrotic and Immunomodulatory Mechanisms

Various factors, including viral and bacterial infections, autoimmune responses, diabetes, drugs, alcohol abuse, and fat deposition, can damage liver tissue and impair its function. These factors affect the liver tissue and lead to acute and chronic liver damage, and if left untreated, can eventually lead to cirrhosis, fibrosis, and liver carcinoma. The main treatment for these disorders is liver transplantation. Still, given the few tissue donors, problems with tissue rejection, immunosuppression caused by medications taken while receiving tissue, and the high cost of transplantation, liver transplantation have been limited. Therefore, finding alternative treatments that do not have the mentioned problems is significant. Cell therapy is one of the treatments that has received a lot of attention today. Hepatocytes and mesenchymal stromal/stem cells (MSCs) are used in many patients to treat liver-related diseases. In the meantime, the use of mesenchymal stem cells has been studied more than other cells due to their favourable characteristics and has reduced the need for liver transplantation. These cells increase the regeneration and repair of liver tissue through various mechanisms, including migration to the site of liver injury, differentiation into liver cells, production of extracellular vesicles (EVs), secretion of various growth factors, and regulation of the immune system. Notably, cell therapy is not entirely excellent and has problems such as cell rejection, undesirable differentiation, accumulation in unwanted locations, and potential tumorigenesis. Therefore, the application of MSCs derived EVs, including exosomes, can help treat liver disease and prevent its progression. Exosomes can prevent apoptosis and induce proliferation by transferring different cargos to the target cell. In addition, these vesicles have been shown to transport hepatocyte growth factor (HGF) and can promote the hepatocytes'(one of the most important cells in the liver parenchyma) growths.

Oxidative Stress and Redox Signaling in the Pathophysiology of Liver Diseases

The increased production of derivatives of molecular oxygen and nitrogen in the form of reactive oxygen species (ROS) and reactive nitrogen species (RNS) lead to molecular damage called oxidative stress. Under normal physiological conditions, the ROS generation is tightly regulated in different cells and cellular compartments. Any disturbance in the balance between the cellular generation of ROS and antioxidant balance leads to oxidative stress. In this article, we discuss the sources of ROS (endogenous and exogenous) and antioxidant mechanisms. We also focus on the pathophysiological significance of oxidative stress in various cell types of the liver. Oxidative stress is implicated in the development and progression of various liver diseases. We narrate the master regulators of ROS-mediated signaling and their contribution to liver diseases. Nonalcoholic fatty liver diseases (NAFLD) are influenced by a "multiple parallel-hit model" in which oxidative stress plays a central role. We highlight the recent findings on the role of oxidative stress in the spectrum of NAFLD, including fibrosis and liver cancer. Finally, we provide a brief overview of oxidative stress biomarkers and their therapeutic applications in various liver-related disorders. Overall, the article sheds light on the significance of oxidative stress in the pathophysiology of the liver. © 2022 American Physiological Society. Compr Physiol 12:3167-3192, 2022.

Pathogenicity and virulence of Hepatitis B virus

Hepatitis B virus (HBV) is a hepatotropic virus and an important human pathogen. There are an estimated 296 million people in the world that are chronically infected by this virus, and many of them will develop severe liver diseases including hepatitis, cirrhosis and hepatocellular carcinoma (HCC). HBV is a small DNA virus that replicates via the reverse transcription pathway. In this review, we summarize the molecular pathways that govern the replication of HBV and its interactions with host cells. We also discuss viral and non-viral factors that are associated with HBV-induced carcinogenesis and pathogenesis, as well as the role of host immune responses in HBV persistence and liver pathogenesis.

Potential Natural Compounds for the Prevention and Treatment of Nonalcoholic Fatty Liver Disease: A Review on Molecular Mechanisms

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a kind of metabolic stress-induced liver injury closely related to insulin resistance and genetic susceptibility, and there is no specific drug for its clinical treatment currently. In recent years, a large amount of literature has reported that many natural compounds extracted from traditional Chinese medicine (TCM) can improve NAFLD through various mechanisms. According to the latest reports, some emerging natural compounds have shown great potential to improve NAFLD but are seldom used clinically due to the lacking special research.

PURPOSE

This paper aims to summarize the molecular mechanisms of the potential natural compounds on improving NAFLD, thus providing a direction and basis for further research on the pathogenesis of NAFLD and the development of effective drugs for the prevention and treatment of NAFLD.

METHODS

By searching various online databases, such as Web of Science, SciFinder, PubMed, and CNKI, NAFLD and these natural compounds were used as the keywords for detailed literature retrieval.

RESULTS

The pathogenesis of NAFLD and the molecular mechanisms of the potential natural compounds on improving NAFLD have been reviewed.

CONCLUSION

Many natural compounds from traditional Chinese medicine have a good prospect in the treatment of NAFLD, which can serve as a direction for the development of anti-NAFLD drugs in the future.

The Myristic Acid:Docosahexaenoic Acid Ratio Versus the n-6 Polyunsaturated Fatty Acid:n-3 Polyunsaturated Fatty Acid Ratio as Nonalcoholic Fatty Liver Disease Biomarkers

It is well established that diets containing an increased omega-6 polyunsaturated fatty acid (n-6 PUFA) to omega-3 polyunsaturated fatty acid (n-3 PUFA) ratios are linked to inflammation and chronic diseases such as nonalcoholic fatty liver disease (NAFLD). However, the influence of an elevated n-6 PUFA:n-3 PUFA ratio in the tissues requires clarification. Herein, we identified primary experimental and clinical studies where it is possible to compare the performance of the myristic acid (Myr):docosahexaenoic acid (DHA) and n-6 PUFA:n-3 PUFA ratios in the liver and/or serum as potential NAFLD biomarkers. Articles were included if quantitative values of n-6 PUFA, n-3 PUFA, Myr, DHA, and information about liver inflammation or liver disease progression parameters were provided. Overall, most experimental (91.6%) and clinical studies (87.5%) reported higher Myr:DHA ratios associated with inflammation and/or NAFLD progression than the n-6 PUFA:n-3 PUFA ratio. We conclude that the Myr:DHA ratio represents a better biomarker of NAFLD than the n-6 PUFA:n-3 PUFA ratio. Future studies are necessary for verifying this observation.

Design of Hepatic Targeted Drug Delivery Systems for Natural Products: Insights into Nomenclature Revision of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic-dysfunction-associated fatty liver disease (MAFLD), affects a quarter of the worldwide population. Natural products have been extensively utilized in treating NAFLD because of their distinctive advantages over chemotherapeutic drugs, despite the fact that there are no approved drugs for therapy. Notably, the limitations of many natural products, such as poor water solubility, low bioavailability in vivo, low hepatic distribution, and lack of targeted effects, have severely restricted their clinical application. These issues could be resolved via hepatic targeted drug delivery systems (HTDDS) that boost clinical efficacy in treating NAFLD and decrease the adverse effects on other organs. Herein an overview of natural products comprising formulas, single medicinal plants, and their crude extracts has been presented to treat NAFLD. Also, the clinical efficacy and molecular mechanism of active monomer compounds against NAFLD are systematically discussed. The targeted delivery of natural products via HTDDS has been explored to provide a different nanotechnology-based NAFLD treatment strategy and to make suggestions for natural-product-based targeted nanocarrier design. Finally, the challenges and opportunities put forth by the nomenclature update of NAFLD are outlined along with insights into how to improve the NAFLD therapy and how to design more rigorous nanocarriers for the HTDDS. In brief, we summarize the up-to-date developments of the NAFLD-HTDDS based on natural products and provide viewpoints for the establishment of more stringent anti-NAFLD natural-product-targeted nanoformulations.

Does iron overload in metabolic syndrome affect macrophage profile? A case control study

AIMS

Dysmetabolic iron overload syndrome (DIOS) is common but the clinical relevance of iron overload is not understood. Macrophages are central cells in iron homeostasis and inflammation. We hypothesized that iron overload in DIOS could affect the phenotype of monocytes and impair macrophage gene expression.

METHODS

This study compared 20 subjects with DIOS to 20 subjects with metabolic syndrome (MetS) without iron overload, and 20 healthy controls. Monocytes were phenotyped by Fluorescence-Activated Cell Sorting (FACS) and differentiated into anti-inflammatory M2 macrophages in the presence of IL-4. The expression of 38 genes related to inflammation, iron metabolism and M2 phenotype was assessed by real-time PCR.

RESULTS

FACS showed no difference between monocytes across the three groups. The macrophagic response to IL-4-driven differentiation was altered in four of the five genes of M2 phenotype (MRC1, F13A1, ABCA1, TGM2 but not FABP4), in DIOS vs Mets and controls demonstrating an impaired M2 polarization. The expression profile of inflammatory genes was not different in DIOS vs MetS. Several genes of iron metabolism presented a higher expression in DIOS vs MetS: SCL11A2 (a free iron transporter, +76 %, p = 0.04), SOD1 (an antioxidant enzyme, +27 %, p = 0.02), and TFRC (the receptor 1 of transferrin, +59 %, p = 0.003).

CONCLUSIONS

In DIOS, macrophage polarization toward the M2 alternative phenotype is impaired but not associated with a pro-inflammatory profile. The up regulation of transferrin receptor 1 (TFRC) in DIOS macrophages suggests an adaptive role that may limit iron toxicity in DIOS.

Rho-Kinase as a Therapeutic Target for Nonalcoholic Fatty Liver Diseases

Nonalcoholic fatty liver disease (NAFLD) is a major public health problem and the most common form of chronic liver disease, affecting 25% of the global population. Although NAFLD is closely linked with obesity, insulin resistance, and type 2 diabetes mellitus, knowledge on its pathogenesis remains incomplete. Emerging data have underscored the importance of Rho-kinase (Rho-associated coiled-coil-containing kinase [ROCK]) action in the maintenance of normal hepatic lipid homeostasis. In particular, pharmacological blockade of ROCK in hepatocytes or hepatic stellate cells prevents the progression of liver diseases such as NAFLD and fibrosis. Moreover, mice lacking hepatic ROCK1 are protected against obesity-induced fatty liver diseases by suppressing hepatic de novo lipogenesis. Here we review the roles of ROCK as an indispensable regulator of obesity-induced fatty liver disease and highlight the key cellular pathway governing hepatic lipid accumulation, with focus on de novo lipogenesis and its impact on therapeutic potential. Consequently, a comprehensive understanding of the metabolic milieu linking to liver dysfunction triggered by ROCK activation may help identify new targets for treating fatty liver diseases such as NAFLD.

Silybin Restored CYP3A Expression through the Sirtuin 2/Nuclear Factor κ-B Pathway in Mouse Nonalcoholic Fatty Liver Disease

Silybin is widely used as a hepatoprotective agent in various liver disease therapies and has been previously identified as a CYP3A inhibitor. However, little is known about the effect of silybin on CYP3A and the regulatory mechanism during high-fat-diet (HFD)-induced liver inflammation. In our study, we found that silybin restored CYP3A expression and activity that were decreased by HFD and conditioned medium (CM) from palmitate-treated Kupffer cells. Moreover, silybin suppressed liver inflammation in HFD-fed mice and inhibited nuclear factor κ-B translocation into the nucleus through elevation of SIRT2 expression and promotion of p65 deacetylation. This effect was confirmed by overexpression of SIRT2, which suppressed p65 nuclear translocation and restored CYP3A transcription affected by CM. The hepatic NAD+ concentration markedly decreased in HFD-fed mice and CM-treated hepatocytes/HepG2 cells but increased after silybin treatment. Supplementing nicotinamide mononucleotide as an NAD+ donor inhibited p65 acetylation, decreased p65 nuclear translocation, and restored cyp3a transcription in both HepG2 cells and mouse hepatocytes. These results suggest that silybin regulates metabolic enzymes during liver inflammation by a mechanism related to the increase in NAD+ and SIRT2 levels. In addition, silybin enhanced the intracellular NAD+ concentration by decreasing poly-ADP ribosyl polymerase-1 expression. In summary, silybin increased NAD+ concentration, promoted SIRT2 expression, and lowered p65 acetylation both in vivo and in vitro, which supported the recovery of CYP3A expression. These findings indicate that the NAD+/SIRT2 pathway plays an important role in CYP3A regulation during nonalcoholic fatty liver disease. SIGNIFICANCE STATEMENT: This research revealed the differential regulation of CYP3A by silybin under physiological and fatty liver pathological conditions. In the treatment of nonalcoholic fatty liver disease, silybin restored, not inhibited, CYP3A expression and activity through the NAD+/ sirtuin 2 pathway in accordance with its anti-inflammatory effect.

Simplified 89Zr-Labeling Protocol of Oxine (8-Hydroxyquinoline) Enabling Prolonged Tracking of Liposome-Based Nanomedicines and Cells

In this work, a method for the preparation of the highly lipophilic labeling synthon [89Zr]Zr(oxinate)4 was optimized for the radiolabeling of liposomes and human induced pluripotent stem cells (hiPSCs). The aim was to establish a robust and reliable labeling protocol for enabling up to one week positron emission tomography (PET) tracing of lipid-based nanomedicines and transplanted or injected cells, respectively. [89Zr]Zr(oxinate)4 was prepared from oxine (8-hydroxyquinoline) and [89Zr]Zr(OH)2(C2O4). Earlier introduced liquid-liquid extraction methods were simplified by the optimization of buffering, pH, temperature and reaction times. For quality control, thin-layer chromatography (TLC), size-exclusion chromatography (SEC) and centrifugation were employed. Subsequently, the 89Zr-complex was incorporated into liposome formulations. PET/CT imaging of 89Zr-labeled liposomes was performed in healthy mice. Cell labeling was accomplished in PBS using suspensions of 3 × 106 hiPSCs, each. [89Zr]Zr(oxinate)4 was synthesized in very high radiochemical yields of 98.7% (96.8% ± 2.8%). Similarly, high internalization rates (≥90%) of [89Zr]Zr(oxinate)4 into liposomes were obtained over an 18 h incubation period. MicroPET and biodistribution studies confirmed the labeled nanocarriers' in vivo stability. Human iPSCs incorporated the labeling agent within 30 min with ~50% efficiency. Prolonged PET imaging is an ideal tool in the development of lipid-based nanocarriers for drug delivery and cell therapies. To this end, a reliable and reproducible 89Zr radiolabeling method was developed and tested successfully in a model liposome system and in hiPSCs alike.

Insights into Macrophage/Monocyte-Endothelial Cell Crosstalk in the Liver: A Role for Trem-2

Liver disease accounts for millions of deaths worldwide annually being a major cause of global morbidity. Hepatotoxic insults elicit a multilayered response involving tissue damage, inflammation, scar formation, and tissue regeneration. Liver cell populations act coordinately to maintain tissue homeostasis and providing a barrier to external aggressors. However, upon hepatic damage, this tight regulation is disrupted, leading to liver pathology which spans from simple steatosis to cirrhosis. Inflammation is a hallmark of liver pathology, where macrophages and endothelial cells are pivotal players in promoting and sustaining disease progression. Understanding the drivers and mediators of these interactions will provide valuable information on what may contribute to liver resilience against disease. Here, we summarize the current knowledge on the role of macrophages and liver sinusoidal endothelial cells (LSEC) in homeostasis and liver pathology. Moreover, we discuss the expanding body of evidence on cell-to-cell communication between these two cell compartments and present triggering receptor expressed on myeloid cells-2 (Trem-2) as a plausible mediator of this cellular interlink. This review consolidates relevant knowledge that might be useful to guide the pursue of successful therapeutic targets and pharmacological strategies for controlling liver pathogenesis.

DSS-induced colitis is associated with adipose tissue dysfunction and disrupted hepatic lipid metabolism leading to hepatosteatosis and dyslipidemia in mice

Considering high prevalence of non-alcoholic fatty liver diseases (NAFLD) in patients with inflammatory bowel disease (IBD), this study aimed to elucidate molecular mechanisms for how intestinal inflammatory conditions are causally linked to hepatic steatosis and dyslipidemia. Both younger and older mice treated with acute or chronic dextran sodium sulfate (DSS) developed colitis, which was evidenced by weight loss, colon length shortening, and elevated disease activity index and inflammation score. They also showed decreased expression of intestinal barrier function-related proteins and elevated plasma lipopolysaccharide level, indicating DSS-induced barrier dysfunction and thereby increased permeability. Interestingly, they displayed phenotypes of hepatic fat accumulation and abnormal blood lipid profiles. This DSS-induced colitis-associated lipid metabolic dysfunction was due to overall disruption of metabolic processes including fatty acid oxidation, lipogenesis, lipolysis, reverse cholesterol transport, bile acid synthesis, and white adipose tissue browning and brown adipose tissue thermogenesis, most of which are mediated by key regulators of energy homeostasis such as FGF21, adiponectin, and irisin, via SIRT1/PGC-1α- and LXRα-dependent pathways. Our study suggests a potential molecular mechanism underlying the comorbidity of NAFLD and IBD, which could provide a key to understanding how the two diseases are pathogenically linked and discovering critical therapeutic targets for their treatment.

Trem-2 Promotes Emergence of Restorative Macrophages and Endothelial Cells During Recovery From Hepatic Tissue Damage

Macrophages are pivotal in mounting liver inflammatory and tissue repair responses upon hepatic injury, showing remarkable functional plasticity. The molecular mechanisms determining macrophage transition from inflammatory to restorative phenotypes in the damaged liver remain unclear. Using mouse models of acute (APAP) and chronic (CCl4) drug-induced hepatotoxic injury we show that the immune receptor Trem-2 controls phenotypic shifts of liver macrophages and impacts endothelial cell differentiation during tissue recovery. Trem-2 gene ablation led to a delayed re-population of Kupffer cells correlating with deterred resolution of hepatic damage following acute and chronic injury. During tissue recovery, we found that macrophages transitioning to Kupffer cells expressed high levels of Trem-2. Acquisition of the transition phenotype was associated with a unique transcriptomic profile denoting strong responsiveness to oxidative stress and downmodulation of the pro-inflammatory phenotype, which was not observed in absence of Trem-2. During tissue recovery, lack of Trem-2 favored accumulation of a liver-damage associated endothelial cell population (LDECs), whose transcriptional program was compatible with endothelial de-differentiation. Accordingly, LDECs precursor potential is supported by the downregulation of surface endothelial cell markers and by striking in vitro morphological changes towards typical endothelial cells. In conclusion, we found that the dynamics of liver macrophages in response to liver injury are critically controlled by Trem-2 and this regulation is interlinked with the de-differentiation of endothelial cells and heightened liver pathology. We propose that Trem-2 promotes the transition from pro-inflammatory to tissue repair phase by driving the acquisition of restorative properties in phagocytic macrophages.

Inhibitory Effect of Black Radish (Raphanus sativus L. var. niger) Extracts on Lipopolysaccharide-Induced Inflammatory Response in the Mouse Monocyte/Macrophage-Like Cell Line RAW 264.7

Black radish (Raphanus sativus L. var. niger), which is cultivated worldwide, is used in traditional medicine as it aids liver function, gastric secretion, gallbladder function, and gallstone mitigation. In this study, we examined the anti-inflammatory effects of black radish extract (BRE) on the lipopolysaccharide (LPS)- and interleukin (IL)-6-mediated inflammatory responses in the RAW 264.7 cell lines. Our findings show that BRE significantly ameliorated LPS-induced nitric oxide (NO) release and production of pro-inflammatory cytokines, such as IL-1β, IL-6, tumor necrosis factor (TNF)-α, and prostaglandin E2. The levels of cyclooxygenase (COX)-2 and inducible NO synthase (iNOS) in LPS-stimulated RAW 264.7 cells were found to be suppressed by BRE. Further, BRE significantly suppressed the LPS-induced expression of mRNAs encoding COX-2, iNOS, IL-1β, IL-6, and TNF-α in a concentration-dependent manner. BRE treatment significantly inhibited Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) phosphorylation in IL-6- and LPS-treated RAW 264.7 cells. In addition, BRE decreased the levels of phosphorylated extracellular signal-regulated protein kinases and c-Jun N-terminal kinase under the same conditions. Moreover, BRE induced high nuclear factor erythroid 2-related factor 2 (NRF2) levels and its target gene heme oxygenase 1 (HO-1) in the absence of LPS. These data demonstrate that BRE may be beneficial for treating inflammation through selective immunomodulatory effects, which may be mediated by inhibition of the STAT3/JAK2 and activation of the NRF2/HO-1 signal transduction pathways.

The antihypertensive agent hydralazine reduced extracellular matrix synthesis and liver fibrosis in nonalcoholic steatohepatitis exacerbated by hypertension

Hypertension is an important risk factor for nonalcoholic steatohepatitis. We have previously demonstrated that hypertensive rats fed a high fat and cholesterol (HFC) diet incurred a more severe hepatic inflammatory response and fibrosis. Here we investigated the role of hypertension in NASH by comparing HFC-induced hepatic fibrogenesis between spontaneously hypertensive rats (SHRs) and their normotensive Wistar Kyoto counterpart. Compared to the counterpart, the HFC diet led to stronger aggregation of CD68-positive macrophages in SHRs. HFC feeding also resulted in significantly higher upregulation of the fibrosis-related gene alpha-smooth muscle actin in SHR. The HFC diet induced higher overexpression of serum tissue inhibitor of metalloproteinase-1 (TIMP1) and greater suppression of matrix metalloproteinase-2 (MMP2):TIMP1, MMP8:TIMP1, and MMP9:TIMP1 ratios, as a proxy of the activities of these MMPs in SHR. Administration of the antihypertensive agent hydralazine to SHRs significantly ameliorated HFC-induced liver fibrosis; it suppressed the aggregation of CD68-positive macrophages and the upregulation of platelet-derived growth factor receptor beta, and collagen, type 1, alpha-1 chain. In conclusion, a hypertensive environment exacerbated the hepatic fibrogenetic effects of the HFC diet; while the effects were partially reversed by the antihypertensive agent hydralazine. Our data suggest that antihypertensive drugs hold promise for treating NASH exacerbated by hypertension.

Kupffer Cells Sense Free Fatty Acids and Regulate Hepatic Lipid Metabolism in High-Fat Diet and Inflammation

A high fat Western-style diet leads to hepatic steatosis that can progress to steatohepatitis and ultimately cirrhosis or liver cancer. The mechanism that leads to the development of steatosis upon nutritional overload is complex and only partially understood. Using click chemistry-based metabolic tracing and microscopy, we study the interaction between Kupffer cells and hepatocytes ex vivo. In the early phase of steatosis, hepatocytes alone do not display significant deviations in fatty acid metabolism. However, in co-cultures or supernatant transfer experiments, we show that tumor necrosis factor (TNF) secretion by Kupffer cells is necessary and sufficient to induce steatosis in hepatocytes, independent of the challenge of hepatocytes with elevated fatty acid levels. We further show that free fatty acid (FFA) or lipopolysaccharide are both able to trigger release of TNF from Kupffer cells. We conclude that Kupffer cells act as the primary sensor for both FFA overload and bacterial lipopolysaccharide, integrate these signals and transmit the information to the hepatocyte via TNF secretion. Hepatocytes react by alteration in lipid metabolism prominently leading to the accumulation of triacylglycerols (TAGs) in lipid droplets, a hallmark of steatosis.

Low-dose trans-resveratrol induce poly(ADP)-ribosylation-dependent increase of the PPAR-γ protein expression level in the in vitro model of non-alcoholic fatty liver disease

An effect of low-dose resveratrol treatment on lipid metabolism and pro-inflammatory processes has been studied, using an in vitro model of Non-Alcoholic-Fatty Liver Disease. The model system consisted of lipid-loaded monolayer cultures of hepatocytes (Hepa1-6) and macrophages (RAW264.7), as both cell types are present in the liver. Also a tridimensional model of hepatic spheroids has been created to mimic spatial adhesive contacts between cells. Treatment with resveratrol (5 μM, 10 μM) for 3 h caused a decrease in lipid load in all three model systems. This decrease wasn't accompanied by any changes in surface expression of lipid transporter-CD36. The response to resveratrol (RSV) was cell type- and cell environment-dependent. In both cell types an increase of the peroxisome proliferator-activated receptor-γ (PPAR-γ) protein level has been revealed. The increase of the PPAR-γ protein level appeared to be poly (ADP)-ribosylation-dependent. It has been revealed, that in the resveratrol-induced signaling pathway, leading to the decrease of intracellular lipid load, an activation of poly (ADP)-ribose polymerase should happen upstream of PPAR-γ protein expression.The decrease of lipid load isn't accompanied by changes in the surface expression of lipid transporter CD36.

Key Players of Hepatic Fibrosis

Hepatic fibrosis is a complex mechanism defined by the net deposition of the extracellular matrix (ECM) owing to liver injury caused by multiple etiologies such as viral hepatitis and nonalcoholic fatty liver disease. Many cell types are implicated in liver fibrosis development and progression. In general, liver fibrosis starts with the recruitment of inflammatory immune cells to generate cytokines, growth factors, and other activator molecules. Such chemical mediators drive the hepatic stellate cells (HSCs) to activate the production of the ECM component. The activation of HSC is thus a crucial event in the fibrosis initiation, and a significant contributor to collagen deposition (specifically type I). This review explores the causes and mechanisms of hepatic fibrosis and focuses on the roles of key molecules involved in liver fibro genesis, some of which are potential targets for therapeutics to hamper liver fibro genesis.