Resveratrol increases CD68⁺ Kupffer cells colocalized with adipose differentiation-related protein and ameliorates high-fat-diet-induced fatty liver in mice

Detection of Tissue Macrophages in Different Organs Using Antibodies to the Microglial Marker Iba-1

Resident macrophages of different organs have structural and functional features, which can complicate their identification and analysis. A promising candidate for the role of a universal immunohistochemical marker of resident macrophages is the calcium-binding protein Iba-1, a well-known marker of brain microglia. The purpose of this work was to study the possibility of using one variant of antibodies to the Iba-1 protein for the immunohistochemical detection of resident macrophages in the liver, myocardium, lung, and choroid plexus of the rat brain. The study was performed on male Wistar rats (n = 15). It was shown that the use of rabbit monoclonal antibodies against Iba-1 allows highly effective detection of Kupffer cells in the liver, resident macrophages in the myocardium, alveolar and interstitial macrophages in the lung, and Kolmer cells in the choroid plexus of the rat brain. In all cases, the reaction is characterized by a high specificity and the absence of background staining. In contrast to the classical marker of macrophages, the CD68 molecule, the Iba-1 protein is evenly distributed in the cytoplasm of cell bodies and processes. This makes it possible to more fully identify cells using immunostaining for Iba-1, carry out their three-dimensional reconstructions, and study their structural and functional organization. Immunohistochemical reaction against Iba-1 can be successfully used as a universal alternative to other common methods for identifying resident macrophages.

Targeting lipid droplets and lipid droplet-associated proteins: a new perspective on natural compounds against metabolic diseases

BACKGROUND

Lipid droplet (LD) is a metabolically active organelle, which changes dynamically with the metabolic state and energy requirements of cells. Proteins that either insert into the LD phospholipid monolayer or are present in the cytoplasm, playing a crucial role in lipid homeostasis and signaling regulation, are known as LD-associated proteins.

METHODS

The keywords "lipid droplets" and "metabolic diseases" were used to obtain literature on LD metabolism and pathological mechanism. After searching databases including Scopus, OVID, Web of Science, and PubMed from 2013 to 2024 using terms like "lipid droplets", "lipid droplet-associated proteins", "fatty liver disease", "diabetes", "diabetic kidney disease", "obesity", "atherosclerosis", "hyperlipidemia", "natural drug monomers" and "natural compounds", the most common natural compounds were identified in about 954 articles. Eventually, a total of 91 studies of 10 natural compounds reporting in vitro or in vivo studies were refined and summarized.

RESULTS

The most frequently used natural compounds include Berberine, Mangostin, Capsaicin, Caffeine, Genistein, Epigallocatechin-3-gallate, Chlorogenic acid, Betaine, Ginsenoside, Resveratrol. These natural compounds interact with LD-associated proteins and help ameliorate abnormal LDs in various metabolic diseases.

CONCLUSION

Natural compounds involved in the regulation of LDs and LD-associated proteins hold promise for treating metabolic diseases. Further research into these interactions may lead to new therapeutic applications.

The promising roles of medicinal plants and bioactive compounds on hepatic lipid metabolism in the treatment of non-alcoholic fatty liver disease in animal models: molecular targets

Imbalance in hepatic lipid metabolism can lead to an abnormal triglycerides deposition in the hepatocytes which can cause non-alcoholic fatty liver disease (NAFLD). Four main mechanisms responsible for regulating hepatic lipid metabolism are fatty acid uptake, de novo lipogenesis, lipolysis and fatty acid oxidation. Controlling the expression of transcription factors at molecular level plays a crucial role in NAFLD management. This paper reviews various medicinal plants and their bioactive compounds emphasising mechanisms involved in hepatic lipid metabolism, other important NAFLD pathological features, and their promising roles in managing NAFLD through regulating key transcription factors. Although there are many medicinal plants popularly investigated for NAFLD treatment, there is still little information and scientific evidence available and there has been no research on clinical trials scrutinised on this matter. This review also aims to provide molecular information of medicinal plants in NALFD treatment that might have potentials for future scientifically controlled studies.

A review of edible plant-derived natural compounds for the therapy of liver fibrosis

Liver fibrosis has a high incidence worldwide and is the common pathological basis of many chronic liver diseases. Liver fibrosis is caused by the excessive deposition of extracellular matrix and concomitant collagen accumulation in livers and can lead to the development of liver cirrhosis and even liver cancer. A large number of studies have provided evidence that liver fibrosis can be blocked or even reversed by appropriate medical interventions. However, the antifibrosis drugs with ideal clinical efficacy are still insufficient. The edible plant-derived natural compounds have been reported to exert effective antifibrotic effects with few side-effects, representing a kind of promising source for the treatment of liver fibrosis. In this article, we reviewed the current progress of the natural compounds derived from dietary plants in the treatment of liver fibrosis, including phenolic compounds (capsaicin, chlorogenic acid, curcumin, ellagic acid, epigallocatechin-3-gallate, resveratrol, sinapic acid, syringic acid, vanillic acid and vitamin E), flavonoid compounds (genistein, hesperidin, hesperetin, naringenin, naringin and quercetin), sulfur-containing compounds (S-allylcysteine, ergothioneine, lipoic acid and sulforaphane) and other compounds (betaine, caffeine, cucurbitacin B, lycopene, α-mangostin, γ-mangostin, ursolic acid, vitamin C and yangonin). The pharmacological effects and related mechanisms of these compounds in in-vivo and in-vitro models of liver fibrosis are focused.

Hepatoprotective and therapeutic effects of resveratrol: A focus on anti-inflammatory and anti- oxidative activities

Being the most essential organ in the body, the liver performs critical functions. Hepatic disorders, such as alcoholic liver disease, hepatic steatosis, liver fibrosis, non-alcoholic fatty liver disease, hepatocellular carcinoma and hepatic failure, have an impact on the biochemical and physiological functions of the body. The main representative of the flavonoid subgroup of flavones, Resveratrol (RES), exhibits suitable pharmacological activities for treating various liver diseases, such as fatty hepatitis, liver steatosis, liver cancer and liver fibrosis. According to various studies, grapes and red wine are good sources of RES. RES has various health properties; it is anti-inflammatory, anti-apoptotic, anti-oxidative and hepatoprotective against several hepatic diseases and hepatoxicity. Therefore, we performed a thorough research and created a summary of the distinct targets of RES in various stages of liver diseases. We concluded that RES inhibited liver inflammation essentially by causing a significant decrease in the expression of various pro-inflammatory cytokines like TNF-α, IL-1α, IL-1β, and IL-6. It also inhibits the transcription factor nuclear NF-κB that brings about the inflammatory cascade. RES also inhibits the PI3K/Akt/mTOR pathway to induce apoptosis. Additionally, it reduces oxidative stress in hepatic tissue by markedly reducing MDA and NO contents, and significantly increasing the levels of CAT, SOD and reduced GSH, in addition to AST and ALT, against toxic chemicals like CC14, As2O3 and TTA. Due to its anti-oxidant, anti-inflammatory and anti-fibrotic properties, RES reduces liver injury markers. RES is safe natural antioxidant that provides pharmacological rectification of the hepatoxicity of toxic chemicals.

Progress in the Application of Drugs for the Treatment of Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune and chronic inflammatory demyelinating disease of the central nervous system (CNS), which gives rise to focal lesion in CNS and cause physical disorders. Although environmental factors and susceptibility genes are reported to play a role in the pathogenesis of MS, its etiology still remains unclear. At present, there is no complete cure, but there are drugs that decelerate the progression of MS. Traditional therapies are disease-modifying drugs that control disease severity. MS drugs that are currently marketed mainly aim at the immune system; however, increasing attention is being paid to the development of new treatment strategies targeting the CNS. Further, the number of neuroprotective drugs is presently undergoing clinical trials and may prove useful for the improvement of neuronal function and survival. In this review, we have summarized the recent application of drugs used in MS treatment, mainly introducing new drugs with immunomodulatory, neuroprotective, or regenerative properties and their possible treatment strategies for MS. Additionally, we have presented Food and Drug Administration-approved MS treatment drugs and their administration methods, mechanisms of action, safety, and effectiveness, thereby evaluating their treatment efficacy.

Liver Fibrosis: Mechanistic Concepts and Therapeutic Perspectives

Liver fibrosis due to viral or metabolic chronic liver diseases is a major challenge of global health. Correlating with liver disease progression, fibrosis is a key factor for liver disease outcome and risk of hepatocellular carcinoma (HCC). Despite different mechanism of primary liver injury and disease-specific cell responses, the progression of fibrotic liver disease follows shared patterns across the main liver disease etiologies. Scientific discoveries within the last decade have transformed the understanding of the mechanisms of liver fibrosis. Removal or elimination of the causative agent such as control or cure of viral infection has shown that liver fibrosis is reversible. However, reversal often occurs too slowly or too infrequent to avoid life-threatening complications particularly in advanced fibrosis. Thus, there is a huge unmet medical need for anti-fibrotic therapies to prevent liver disease progression and HCC development. However, while many anti-fibrotic candidate agents have shown robust effects in experimental animal models, their anti-fibrotic effects in clinical trials have been limited or absent. Thus, no approved therapy exists for liver fibrosis. In this review we summarize cellular drivers and molecular mechanisms of fibrogenesis in chronic liver diseases and discuss their impact for the development of urgently needed anti-fibrotic therapies.

Health Benefits and Molecular Mechanisms of Resveratrol: A Narrative Review

Resveratrol is a bioactive compound in many foods. Since its anticancer activity was reported in 1997, its health benefits have been intensively investigated. Resveratrol has antioxidant, anti-inflammatory, immunomodulatory, glucose and lipid regulatory, neuroprotective, and cardiovascular protective effects, therefore, can protect against diverse chronic diseases, such as cardiovascular diseases (CVDs), cancer, liver diseases, obesity, diabetes, Alzheimer's disease, and Parkinson's disease. This review summarizes the main findings of resveratrol-related health benefits in recent epidemiological surveys, experimental studies, and clinical trials, highlighting its related molecular mechanisms. Resveratrol, therefore, has been regarded as a potent candidate for the development of nutraceuticals and pharmaceuticals to prevent and treat certain chronic diseases.

Anti-toll-like receptor 2 antibody ameliorates hepatic injury, inflammation, fibrosis and steatosis in obesity-related metabolic disorder rats via regulating MAPK and NF-κB pathways

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide, which includes a spectrum of histological liver changes. Non-alcoholic steatohepatitis (NASH) is considered to be the progressive subtype of NAFLD, which is characterized by lobular inflammation and cellular ballooning on the basis of steatosis. There is a critical need to develop novel and effective therapeutic approaches for NAFLD/NASH. The activation of toll-like receptor 2 (TLR2) signaling pathway plays a key role in high-fat-related inflammation, triggering the occurrence and development of NASH. Herein, the anti-TLR2 monoclonal antibody (TLR2 mAb) was prepared and investigated for its ability to ameliorate the inflammatory response in vivo and in vitro. The anti-inflammatory role of TLR2 mAb in vitro was examined in NR8383 macrophage cells and THP-1 derived macrophage cells. For confirmation in vivo, three groups of SD rats were treated for 20 weeks: rats in the control were fed with a standard diet; rates in the IgG and TLR2 mAb groups were fed with a high-fat diet and with IgG or TLR2 mAb, respectively. Liver tissue and serum were collected for further analysis. Results showed that after 4-week treatment with TLR2 mAb, metabolic parameters in rats were improved markedly (body weight, fasting blood glucose level, liver steatosis, inflammatory response and fibrosis). Moreover, western blotting demonstrated that the TLR2 mAb blocked MAPKs and NF-κB activation, and inhibited the expression of inflammatory factors in rat liver tissue. These effects suggested that TLR2 mAb could improve HFD-induced hepatic injury, inflammation, fibrosis and steatosis by suppressing inflammatory response and regulating the hepatic MAPKs and NF-κB signaling pathways. This suggests that TLR2 may be a novel therapeutic target for metabolic diseases especially NASH.

The influence of dietary conditions in the effects of resveratrol on hepatic steatosis

Non-alcoholic fatty liver disease (NAFLD) is considered the major cause for the development of chronic liver alterations.

Pioglitazone improves phagocytic activity of liver recruited macrophages in elderly mice possibly by promoting glucose catabolism

Recent studies have revealed that the immunological function of leukocytes is dependent on their cellular metabolism, and some researchers have advocated the beneficial effects of pioglitazone against sepsis in young mice, although bacterial infections are more prevalent in elderly hosts. Here, we investigated pioglitazone’s preventative effect against sepsis induced by intravenous injection of a lethal dose of Escherichia coli in elderly mice (50–60 wk old) and examined its immunological and metabolic effects on liver leukocytes. Pioglitazone improved bacterial elimination in the peripheral blood, lowered serum pro-inflammatory cytokines (TNF-α, IL-12, IFN-γ), and prevented septic death. It also enhanced bacterial elimination in the liver, by increasing the phagocytic and bactericidal activities of liver F4/80+CD11b+ recruited macrophages (Mφ), their CD206 expression and reactive oxygen species production. Quantitative PCR revealed that pioglitazone treatment enhanced gene expression of rate-limiting enzymes for glycolysis in hepatic CD11b+ cells (including neutrophils and recruited Mφ), and their improved phagocytic and bactericidal activities were abolished by glycolysis inhibiting reagents. These findings present the possibility that pioglitazone strengthens the phagocytic and bactericidal activities of liver recruited Mφ and that these immunological activities are closely associated with their glucose catabolism.

Paeoniflorin attenuates incipient diabetic nephropathy in streptozotocin-induced mice by the suppression of the Toll-like receptor-2 signaling pathway

Toll-like receptors (TLRs) may be involved in diabetic nephropathy (DN). Paeoniflorin (PF) is an effective Chinese traditional medicine with anti-inflammatory and immunoregulatory effects that may inhibit the TLR2 signaling pathway. In this study, we investigated the effects of PF on the kidneys of mice with streptozotocin-induced type 1 diabetes mellitus using TLR2 knockout mice (TLR2^−/−) and wild-type littermates (C57BL/6J-WT). After 12 weeks of intraperitoneal injection of PF at doses of 25, 50, and 100 mg/kg once a day, diabetic mice had significantly reduced albuminuria and attenuated renal histopathology. These changes were associated with substantially alleviated macrophage infiltration and decreased expression of TLR2 signaling pathway biomarkers. These data support a role of TLR2 in promoting inflammation and indicate that the effect of PF is associated with the inhibition of the TLR2 pathway in the kidneys of diabetic mice. PF thus shows therapeutic potential for the prevention and treatment of DN.

Lack of Additive Effects of Resveratrol and Energy Restriction in the Treatment of Hepatic Steatosis in Rats

The aims of the present study were to analyze the effect of resveratrol on liver steatosis in obese rats, to compare the effects induced by resveratrol and energy restriction and to research potential additive effects. Rats were initially fed a high-fat high-sucrose diet for six weeks and then allocated in four experimental groups fed a standard diet: a control group, a resveratrol-treated group, an energy restricted group and a group submitted to energy restriction and treated with resveratrol. We measured liver triacylglycerols, transaminases, FAS, MTP, CPT1a, CS, COX, SDH and ATP synthase activities, FATP2/FATP5, DGAT2, PPARα, SIRT1, UCP2 protein expressions, ACC and AMPK phosphorylation and PGC1α deacetylation. Resveratrol reduced triacylglycerols compared with the controls, although this reduction was lower than that induced by energy restriction. The mechanisms of action were different. Both decreased protein expression of fatty acid transporters, thus suggesting reduced fatty acid uptake from blood stream and liver triacylglycerol delivery, but only energy restriction reduced the assembly. These results show that resveratrol is useful for liver steatosis treatment within a balanced diet, although its effectiveness is lower than that of energy restriction. However, resveratrol is unable to increase the reduction in triacylglycerol content induced by energy restriction.

The TIR/BB-loop mimetic AS-1 prevents non-alcoholic steatohepatitis and hepatic insulin resistance by inhibiting NLRP3-ASC inflammasome activation

BACKGROUND AND PURPOSE

Non-alcoholic steatohepatitis (NASH) is characterized by excessive intracellular lipid accumulation, inflammation and hepatic insulin resistance. As the incidence of NASH is increasing worldwide, there is an urgent need to find novel interventional approaches. The pro-inflammatory cytokine IL-1β, generated and released from Kupffer cells, is considered to initiate the development of NASH. AS-1, a synthetic low-molecule mimetic of myeloid differentiation primary response gene 88 (MyD88), disrupts the interaction between the IL-1 receptor and MyD88. Here, we investigated whether AS-1 could attenuate the pathogenesis of NASH with an emphasis on hepatic insulin resistance.

EXPERIMENTAL APPROACH

Eight-week-old db/db mice were fed a control diet or a methionine- and choline-deficient (MCD) diet. AS-1 (50 mg·kg^-1 ) or vehicle was administered i.p.

KEY RESULTS

AS-1 administration significantly ameliorated NASH as evidenced by alanine aminotransferase levels and CD68 levels in livers of MCD-fed mice. AS-1 inhibited the MCD diet-induced activation of caspase 1 and the NLRP3-ASC inflammasome, and also reduced the enhanced levels of ROS, malondialdehyde, 3-nitrotyrosine, NADPH oxidase complex and CYP reductase-associated cytochrome p450 2E1 (CYP2E1) expression in the liver. In addition, AS-1 decreased ROS, inflammasome activation and IL-1β production in free fatty acid-LPS-treated Kupffer cells. Finally, pretreatment with AS-1 significantly ameliorated gluconeogenesis and insulin desensitization induced by IL-1β, probably by blocking the interaction between MyD88 and the IL-1 receptor.

CONCLUSIONS AND IMPLICATIONS

Our results indicate that AS-1 can ameliorate NASH and hepatic insulin resistance and could be considered as a potential strategy for the prevention and treatment of NASH.

Activation and increase of radio-sensitive CD11b+ recruited Kupffer cells/macrophages in diet-induced steatohepatitis in FGF5 deficient mice

We have recently reported that Kupffer cells consist of two subsets, radio-resistant resident CD68+ Kupffer cells and radio-sensitive recruited CD11b+ Kupffer cells/macrophages (Mφs). Non-alcoholic steatohepatitis (NASH) is characterized not only by hepatic steatosis but also chronic inflammation and fibrosis. In the present study, we investigated the immunological mechanism of diet-induced steatohepatitis in fibroblast growth factor 5 (FGF5) deficient mice. After consumption of a high fat diet (HFD) for 8 weeks, FGF5 null mice developed severe steatohepatitis and fibrosis resembling human NASH. F4/80+ Mφs which were both CD11b and CD68 positive accumulated in the liver. The production of TNF and FasL indicated that they are the pivotal effectors in this hepatitis. The weak phagocytic activity and lack of CRIg mRNA suggested that they were recruited Mφs. Intermittent exposure to 1 Gy irradiation markedly decreased these Mφs and dramatically inhibited liver inflammation without attenuating steatosis. However, depletion of the resident subset by clodronate liposome (c-lipo) treatment increased the Mφs and tended to exacerbate disease progression. Recruited CD11b+ CD68+ Kupffer cells/Mφs may play an essential role in steatohepatitis and fibrosis in FGF5 null mice fed with a HFD. Recruitment and activation of bone marrow derived Mφs is the key factor to develop steatohepatitis from simple steatosis.

Proteomics in quality control: Whey protein-based supplements

The growing consumption of nutritional supplements might represent a problem, given the concern about the quality of these supplements. One of the most used supplements is whey protein (WP); because of its popularity, it has been a target of adulteration with substitute products, such as cheaper proteins with lower biological value. To investigate this type of adulteration, this study used shotgun proteomics analyses by MS(E) (multiplexed, low- and high-collision energy, data-independent acquisition) of WP-based supplements. Seventeen WP-based supplement samples were evaluated. Chicken, maize, rice, potato, soybean, and wheat proteins were considered as probable sources of bovine whey adulteration. Collectively, 523 proteins were identified across all 16 samples and replicates, with 94% of peptides inside a normal distribution within 10ppm of maximum error. In 10 of the 16 samples analyzed, only proteins from bovine whey could be detected, while in the other samples several other protein sources were detected in high concentrations, especially soybean, wheat, and rice. These results point out a probable adulteration and/or sample contamination during manufacturing that could only be detected using this proteomic approach.

SIGNIFICANCE

The present work shows how shotgun proteomics can be used to provide reliable answers in quality control matters, especially focusing on Whey Protein nutritional supplements which are a very popular subject in food and nutrition. In order to achieve an appropriate methodology, careful evaluation was performed applying extremely rigorous quality criteria, established for the proteomic analysis. These criteria and the methodological approach used in this work might serve as a guide for other authors seeking to use proteomics in quality control.

Resveratrol ameliorates fibrosis and inflammation in a mouse model of nonalcoholic steatohepatitis

The natural polyphenol compound resveratrol (RSV) is considered to have a broad spectrum of beneficial biological activities upon human health. However, the exact effect of RSV on steatosis (a phenotype of non-alcoholic fatty liver [NAFL]) or fibrosis and inflammation (major phenotypes of non-alcoholic steatohepatitis [NASH]) is not known. Our data showed that administration of RSV (2 or 20 mg/kg/day) did not suppress steatosis in a high-fat diet-induced model of NAFL in mice. In contrast, identical concentrations of RSV dramatically inhibited inflammation and fibrosis in a low-dose lipopolysaccharide-induced model of NASH. These data suggested that RSV administration-mediated improvement of inflammation and fibrosis was due to the inhibition of LPS reactivity controlled by CD14 expression in Kupffer cells. These findings suggest that RSV could be a candidate agent for the treatment of NASH.