Serum α-SMA is a potential noninvasive biomarker of liver fibrosis.

The severity of fibrosis is central to the therapeutic course for patients with chronic liver disease; therefore, early detection of liver fibrosis is critical for timely therapeutic interventions. Liver biopsy is the gold standard for the diagnosis of liver fibrosis; however, it is contraindicated in several pathological conditions. Activated hepatic stellate cells (HSCs) are the main cells for fibrotic tissue synthesis, such as that of alpha-smooth muscle actin (α-SMA). This study aimed to determine whether serum α-SMA levels are a suitable noninvasive, sensitive, and reliable liver fibrosis marker. Fibrosis was induced in male Wistar rats via chronic CCl4 administration. Fibrosis was determined in the liver tissues by quantifying the hydroxyproline content and visualized using Masson's trichrome staining. Rats chronically administered CCl4 exhibited a progressive increment in the hepatic collagen content, as well as both hepatic and serum α-SMA levels in a time-dependent manner. Moreover, serum levels of α-SMA significantly correlated with hepatic α-SMA levels (p ≤ 0.001), as well as with the severity of liver fibrosis (p ≤ 0.001). These findings suggest that increased levels of serum α-SMA can be considered a potential reliable and noninvasive biomarker for early liver fibrosis.

Nicotinic acid attenuates experimental non-alcoholic steatohepatitis by inhibiting the NLRP3 inflammasome/pyroptosis pathway.

Non-alcoholic steatohepatitis (NASH) is a global public health concern that may progress into fibrosis, cirrhosis, and liver cancer, with limited curative treatment options. While the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is closely linked to NASH progression, nicotinic acid (NA), a vitamin used for the treatment of dyslipidemia, is an emerging pharmaceutical treatment for hepatic steatosis and fibrosis. Here, we investigated pharmacological effects of NA on experimental NASH and whether NLRP3 inflammasome/pyroptosis inhibition is an associated mechanism of action. Rats were fed a high-fat sucrose diet supplemented with cholesterol and a low dose of CCl4. NA significantly reduced inflammation by decreasing the protein levels of tumor necrosis factor-alpha and nuclear factor kappa B. Moreover, NA inhibited the formation of NLRP3- apoptosis-associated speck-like protein containing caspase recruitment domain-Caspase-1, decreasing interleukin-1beta, interleukin-18, and gasdermin D protein. In addition, NA reduced tumor growth factor-beta, alpha-smooth muscle actin, and hepatic levels of collagen-1, consequently decreasing extracellular matrix synthesis. Our results indicate that NA can inhibit NASH progression and encourage further basic and clinical studies on the use of NA for the treatment of human NASH.

Mechanisms of non-alcoholic fatty liver disease development in normal-weight individuals.

While non-alcoholic fatty liver disease (NAFLD) without inflammation or fibrosis is considered a relatively 'benign' disease, non-alcoholic steatohepatitis (NASH), by contrast, is characterized by marked inflammation in addition to lipid accumulation, and may include fibrosis, progression to cirrhosis and hepatocellular carcinoma. Obesity and type II diabetes are frequently associated with NAFLD/NASH; however, a significant number of lean individuals may develop these diseases. Little attention has been paid to the causes and mechanisms contributing to NAFLD development in normal-weight individuals. One of the main causes of NAFLD in normal-weight individuals is the accumulation of visceral and muscular fat and its interaction with the liver. Myosteatosis (triglyceride accumulation in the muscle) induces a loss of muscle by reducing blood flow and insulin diffusion, contributing to NAFLD. Normal-weight patients with NAFLD exhibit higher serum markers of liver damage and C-reactive protein levels, as well as more pronounced insulin resistance, compared to healthy controls. Notably, increased levels of C-reactive protein and insulin resistance are strongly correlated with the risk of developing NAFLD/NASH. Gut dysbiosis has also been associated with NAFLD/NASH progression in normal-weight individuals. More investigation is required to elucidate the mechanisms leading to NAFLD in normal-weight individuals.

The antioxidant and anti-inflammatory activities of caffeine effectively attenuate nonalcoholic steatohepatitis and thioacetamide-induced hepatic injury in male rats.

The antioxidant effect of caffeine, associated with its ability to upregulate the nuclear factor-E2-related factor-2 (Nrf2)-signaling pathway, was explored as a possible mechanism for the attenuation of liver damage. Nonalcoholic steatohepatitis (NASH) was induced in rats by the administration of a high-fat, high-sucrose, high-cholesterol diet (HFSCD) for 15 weeks. Liver damage was induced in rats by intraperitoneal administration of thioacetamide (TAA) for six weeks. Caffeine was administered orally at a daily dose of 50 mg/kg body weight during the period of NASH induction to evaluate its ability to prevent disease development. Meanwhile, rats received TAA for three weeks, after which 50 mg/kg caffeine was administered daily for three weeks with TAA to evaluate its capacity to interfere with the progression of hepatic injury. HFSCD administration induced hepatic steatosis, decreased Nrf2 levels, increased oxidative stress, induced the activation of nuclear factor-κB (NF-κB), and elevated proinflammatory cytokine levels, leading to hepatic damage. TAA administration produced similar effects, excluding steatosis. Caffeine increased Nrf2 levels; attenuated oxidative stress markers, including malondialdehyde and 4-hydroxynonenal; restored normal, reduced glutathione levels; and reduced NF-κB activation, inflammatory cytokine levels, and damage. Our findings suggest that caffeine may be useful in the treatment of human liver diseases.

Activation of the NLRP3 inflammasome by CCl4 exacerbates hepatopathogenic diet-induced experimental NASH.

INTRODUCTION AND OBJECTIVES: Administration of carbon tetrachloride (CCl4), along with an hepatopathogenic diet, is widely employed as a chemical inducer to replicate human nonalcoholic steatohepatitis (NASH) in rodents; however, the role of the nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome in this model remains unclear. We aimed to determine the relevance of NLRP3 inflammasome activation in the development of NASH induced by CCl4 along with an hepatopathogenic diet in male Wistar rats. MATERIALS AND METHODS: Animals were fed either a high fat, sucrose, and cholesterol diet (HFSCD) or a HFSCD plus intraperitoneal injections of low doses of CCl4 (400 mg/kg) once a week for 15 weeks. Liver steatosis, inflammation, fibrosis, and NLRP3 inflammasome activation were evaluated using biochemical, histological, ultrastructural, and immunofluorescence analyses, western blotting, and immunohistochemistry. RESULTS: Our experimental model reproduced several aspects of the human NASH pathophysiology. NLRP3 inflammasome activation was induced by the combined effect of HFSCD plus CCl4 and significantly increased levels of both proinflammatory and profibrogenic cytokines and collagen deposition in the liver; thus, NASH severity was higher in the HFSCD+CCl4 group than that in the HFSCD group, to which CCl4 was not administered. Hepatic stellate cells, the most profibrogenic cells, were activated by HFSCD plus CCl4, as indicated by elevated levels of α-smooth muscle actin. Thus, activation of the NLRP3 inflammasome, triggered by low doses of CCl4, exacerbates the severity of NASH. CONCLUSIONS: Our results indicate that NLRP3 inflammasome activation plays a key role and may be an important therapeutic target for NASH treatment.

Caffeine Inhibits NLRP3 Inflammasome Activation by Downregulating TLR4/MAPK/NF-κB Signaling Pathway in an Experimental NASH Model.

Caffeine elicits protective effects against liver diseases, such as NASH; however, its mechanism of action involving the pyrin domain-containing-3 (NLRP3) inflammasome signaling pathway remains to be elucidated. This study aimed to evaluate the effect of caffeine on the NLRP3 inflammasome signaling pathway in a rat model of NASH. NASH was induced by feeding rats a high-fat, -sucrose, and -cholesterol diet (HFSCD) for 15 weeks along with a weekly low dose (400 mg/kg, i.p.) of CCl4. Caffeine was administered at 50 mg/kg p.o. The effects of HFSCD+CCl4 and caffeine on the liver were evaluated using biochemical, ultrastructural, histological, and molecular biological approaches. The HFSCD+CCl4-treated rats showed fat accumulation in the liver, elevated levels of inflammatory mediators, NLRP3 inflammasome activation, antioxidant dysregulation, and liver fibrosis. Caffeine reduced necrosis, cholestasis, oxidative stress, and fibrosis. Caffeine exhibited anti-inflammatory effects by attenuating NLRP3 inflammasome activation. Moreover, caffeine prevented increases in toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) protein levels and mitigated the phosphorylation of mitogen-activated protein kinase (MAPK). Importantly, caffeine prevented the activation of hepatic stellate cells. This study is the first to report that caffeine ameliorates NASH by inhibiting NLRP3 inflammasome activation through the suppression of the TLR4/MAPK/NF-κB signaling pathway.

Caffeine mitigates experimental nonalcoholic steatohepatitis and the progression of thioacetamide-induced liver fibrosis by blocking the MAPK and TGF-ß/Smad3 signaling pathways.

INTRODUCTION AND OBJECTIVES: Caffeine consumption is associated with beneficial effects on hepatic disorders. The objectives of this study were to evaluate the antifibrotic effects of caffeine on experimental nonalcoholic steatohepatitis (NASH) induced with a high-fat, high-sucrose, high-cholesterol diet (HFSCD), as well as to evaluate the ability of caffeine to prevent the progression of experimental liver fibrosis induced by the administration of thioacetamide (TAA) in rats and explore the mechanisms of action. METHODS: NASH and fibrosis were induced in rats by the administration of an HFSCD for 15 weeks, and liver fibrosis was induced by intraperitoneal administration of 200 mg/kg TAA 3 times per week, for 6 weeks. Caffeine was administered at a dose of 50 mg/kg body weight. The effects of diet, TAA, and caffeine on fibrosis were evaluated by biochemical and histological examinations. The profibrotic pathways were analyzed by western blotting and immunohistochemistry. RESULTS: Rats exhibited liver fibrosis after HFSCD feeding and the administration of TAA. Caffeine could reduce the hepatic level of collagen and the fibrotic area in the liver. Caffeine prevented the progression of liver fibrosis by decreasing transforming growth factor-beta (TGF-ß), connective tissue growth factor (CTGF), and alpha-smooth muscle actin (α-SMA) expression and by inhibiting the activation of mitogen-activated protein kinases (MAPKs) and Smad3 phosphorylation. CONCLUSIONS: Caffeine attenuates NASH and the progression of liver fibrosis due to its antifibrotic effects and modulating the MAPK and TGF-ß pathways. Therefore, caffeine could be a suitable candidate for treating liver diseases associated with fibrosis.

Herbal medicines for the liver: from bench to bedside.

The liver is one of the most complex organs of the human body and is involved in various metabolic processes. Due to its anatomical proximity to the digestive tract, its blood flow, and its contribution to the detoxification process, the liver is susceptible to a wide variety of disorders. Hepatic diseases can be caused by alcoholism, viral infections, malnutrition and xenobiotics, which result in a high frequency of patients with liver disease and subsequent increase in the number of deaths from these diseases, for which adequate treatments are not yet available. Therefore, the search for new alternatives to treat these liver conditions is mandatory. In recent decades, there has been an increase in interest in medicinal herbs due to their safety and hepatoprotective properties that arise from their anti-inflammatory, antioxidant, antifibrotic, antiviral, immunomodulatory and anticancer properties. Epidemiological and clinical studies have shown that the consumption of these compounds is associated with a decrease in the risk of developing liver diseases; thus, medicinal herbs have emerged as a viable option for the treatment of these hepatic pathologies. However, more basic and clinical studies are needed before reaching a final recommendation to treat human liver diseases. This review provides molecular and clinical information on some natural compounds and medicinal herbs that have hepatoprotective effects and could be useful for the treatment of hepatic disorders.