Benzyl isothiocyanate ameliorates high-fat/cholesterol/cholic acid diet-induced nonalcoholic steatohepatitis through inhibiting cholesterol crystal-activated NLRP3 inflammasome in Kupffer cells

Luteolin, apigenin, and chrysin inhibit lipotoxicity-induced NLRP3 inflammasome activation and autophagy damage in macrophages by suppressing endoplasmic reticulum stress

Lipotoxicity leads to numerous metabolic disorders such as nonalcoholic steatohepatitis. Luteolin, apigenin, and chrysin are three flavones with known antioxidant and anti-inflammatory properties, but whether they inhibit lipotoxicity-mediated NLRP3 inflammasome activation was unclear. To address this question, we used J774A.1 macrophages and Kupffer cells stimulated with 100 μM palmitate (PA) in the presence or absence of 20 μM of each flavone. PA increased p-PERK, p-IRE1α, p-JNK1/2, CHOP, and TXNIP as well as p62 and LC3-II expression and induced autophagic flux damage. Caspase-1 activation and IL-1β release were also noted after 24 h of exposure to PA. In the presence of the PERK inhibitor GSK2656157, PA-induced CHOP and TXNIP expression and caspase-1 activation were mitigated. Compared with PA treatment alone, Bcl-2 coupled to beclin-1 was elevated and autophagy was reversed by the JNK inhibitor SP600125. With luteolin, apigenin, and chrysin treatment, PA-induced ROS production, ER stress, TXNIP expression, autophagic flux damage, and apoptosis were ameliorated. Moreover, TXNIP binding to NLRP3 and IL-1β release in response to LPS/PA challenge were reduced. These results suggest that luteolin, apigenin, and chrysin protect hepatic macrophages against PA-induced NLRP3 inflammasome activation and autophagy damage by attenuating endoplasmic reticulum stress.

Immunomodulating Phytochemicals: An Insight Into Their Potential Use in Cytokine Storm Situations

Phytochemicals are compounds found in plants that possess a variety of bioactive properties, including antioxidant and immunomodulatory properties. Recent studies have highlighted the potential of phytochemicals in targeting specific signalling pathways involved in cytokine storm, a life-threatening clinical condition resulting from excessive immune cell activation and oversupply of proinflammatory cytokines. Several studies have documented the immunomodulatory effects of phytochemicals on immune function, including their ability to regulate essential cellular and molecular interactions of immune system cells. This makes them a promising alternative for cytokine storm management, especially when combined with existing chemotherapies. Furthermore, phytochemicals have been found to target multiple signalling pathways, including the TNF-α/NF-κB, IL-1/NF-κB, IFN-γ/JAK/STAT, and IL-6/JAK-STAT. These pathways play critical roles in the development and progression of cytokine storm, and targeting them with phytochemicals represents a promising strategy for controlling cytokine release and the subsequent inflammation. Studies have also investigated certain families of plant-related constituents and their potential immunomodulatory actions. In vivo and in vitro studies have reported the immunomodulatory effects of phytochemicals, which provide viable alternatives in the management of cytokine storm syndrome. The collective data from previous studies suggest that phytochemicals represent a potentially functional source of cytokine storm treatment and promote further exploration of these compounds as immunomodulatory agents for suppressing specific signalling cascade responses. Overall, the previous research findings support the use of phytochemicals as a complementary approach in managing cytokine storm and improving patient outcomes.

Mitochondrial cholesterol: Metabolism and impact on redox biology and disease

Cholesterol is a crucial component of membrane bilayers by regulating their structural and functional properties. Cholesterol traffics to different cellular compartments including mitochondria, whose cholesterol content is low compared to other cell membranes. Despite the limited availability of cholesterol in the inner mitochondrial membrane (IMM), the metabolism of cholesterol in the IMM plays important physiological roles, acting as the precursor for the synthesis of steroid hormones and neurosteroids in steroidogenic tissues and specific neurons, respectively, or the synthesis of bile acids through an alternative pathway in the liver. Accumulation of cholesterol in mitochondria above physiological levels has a negative impact on mitochondrial function through several mechanisms, including the limitation of crucial antioxidant defenses, such as the glutathione redox cycle, increased generation of reactive oxygen species and consequent oxidative modification of cardiolipin, and defective assembly of respiratory supercomplexes. These adverse consequences of increased mitochondrial cholesterol trafficking trigger the onset of oxidative stress and cell death, and, ultimately, contribute to the development of diverse diseases, including metabolic liver diseases (i.e. fatty liver disease and liver cancer), as well as lysosomal disorders (i.e. Niemann-Pick type C disease) and neurodegenerative diseases (i.e. Alzheimer's disease). In this review, we summarize the metabolism and regulation of mitochondrial cholesterol and its potential impact on liver and neurodegenerative diseases.

Benzyl isothiocyanate attenuates activation of the NLRP3 inflammasome in Kupffer cells and improves diet-induced steatohepatitis

The NLRP3 inflammasome plays an important role in the pathogenesis of numerous inflammation-related diseases. Benzyl isothiocyanate (BITC) is rich in cruciferous vegetables and possesses potent antioxidant, anti-inflammatory, anti-cancer, and anti-obesogenic properties. In this study, we investigated the role of the NLRP3 inflammasome in the protection by BITC against steatohepatitis and insulin resistance. A mouse model of high-fat/cholesterol/cholic acid diet (HFCCD)-induced steatohepatitis, LPS/nigericin-stimulated primary Kupffer cells, and IL-1β treated primary hepatocytes were used. BITC attenuated LPS/nigericin-induced activation of the NLRP3 inflammasome by enhancing protein kinase A-dependent NLRP3 ubiquitination, which increased the degradation of NLRP3 and reduced IL-1β secretion in Kupffer cells. In hepatocytes, BITC pretreatment reversed the IL-1β-induced decrease in the phosphorylation of IR, AKT, and GSK3β in response to insulin. After 12 weeks of HFCCD feeding, increases in blood alanine aminotransferase (ALT) and glucose levels were ameliorated by BITC. Hepatic IL-1β production, macrophage infiltration, and collagen expression induced by HFCCD were also mitigated by BITC. BITC suppresses activation of the NLRP3 inflammasome in Kupffer cells by enhancing the PKA-dependent ubiquitination of NLRP3, which leads to suppression of IL-1β production and subsequently ameliorates hepatic inflammation and insulin resistance.

Programmed cell death and lipid metabolism of macrophages in NAFLD

Non-alcoholic fatty liver disease (NAFLD) has now become the leading chronic liver disease worldwide with lifestyle changes. This may lead to NAFLD becoming the leading cause of end-stage liver disease in the future. To date, there are still no effective therapeutic drugs for NAFLD. An in-depth exploration of the pathogenesis of NAFLD can help to provide a basis for new therapeutic agents or strategies. As the most important immune cells of the liver, macrophages play an important role in the occurrence and development of liver inflammation and are expected to become effective targets for NAFLD treatment. Programmed cell death (PCD) of macrophages plays a regulatory role in phenotypic transformation, and there is also a certain connection between different types of PCD. However, how PCD regulates macrophage polarization has still not been systematically elucidated. Based on the role of lipid metabolic reprogramming in macrophage polarization, PCD may alter the phenotype by regulating lipid metabolism. We reviewed the effects of macrophages on inflammation in NAFLD and changes in their lipid metabolism, as well as the relationship between different types of PCD and lipid metabolism in macrophages. Furthermore, interactions between different types of PCD and potential therapeutic agents targeting of macrophages PCD are also explored.

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

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

Sodium Tanshinone IIA Sulfonate Inhibits Vascular Endothelial Cell Pyroptosis via the AMPK Signaling Pathway in Atherosclerosis

Introduction

Atherosclerosis (AS) is the underlying cause of cardiovascular events. Endothelial cell mitochondrial damage and pyroptosis are important factors contributing to AS. Changes in internal mitochondrial conformation and increase in reactive oxygen species (ROS) lead to the disruption of mitochondrial energy metabolism, activation of the NLRP3 inflammasome and pyroptosis, which in turn affect atherogenesis by impairing endothelial function. AMPK is a core player in the regulation of cellular metabolism, not only by regulating mitochondrial homeostasis but also by regulating cellular inflammatory responses. Sodium tanshinone IIA sulfonate (STS), a water-soluble derivative of tanshinone IIA, has significant antioxidant and anti-inflammatory effects, and roles in cardiovascular protection.

Purpose

In this study, we investigated whether STS plays a protective role in AS by regulating endothelial cell mitochondrial function and pyroptosis through an AMPK-dependent mitochondrial pathway.

Methods and Results

Male ApoE^−/− mice and HUVECs were used for the experiments. We found that STS treatment largely abrogated the upregulation of key proteins in aortic vessel wall plaques and typical pyroptosis signaling in ApoE^−/− mice fed a western diet, consequently enhancing pAMPK expression, plaque stabilization, and anti-inflammatory responses. Consistently, STS pretreatment inhibited cholesterol crystallization (CC) -induced cell pyroptosis and activated pAMPK expression. In vitro, using HUVECs, we further found that STS treatment ameliorated mitochondrial ROS caused by CC, as evidenced by the finding that STS inhibited mitochondrial damage caused by CC. The improvement of endothelial cell mitochondrial function by STS is blocked by dorsomorphin (AMPK inhibitor). Consistently, the blockade of endothelial cell pyroptosis by STS is disrupted by dorsomorphin.

Conclusion

Our results suggest that STS enhances maintenance of mitochondrial homeostasis and inhibits mitochondrial ROS overproduction via AMPK, thereby improving endothelial cell pyroptosis during AS.

Discovery of a Novel Oral Proteasome Inhibitor to Block NLRP3 Inflammasome Activation with Anti-inflammation Activity

NLRP3 inflammasome activation plays a critical role in inflammation-related disorders. More small-molecule entities are needed to study the mechanism of NLRP3 inflammasome activation and to validate the efficacy and safety of the NLRP3 pathway. Herein, we report the discovery of an orally bioavailable proteasome inhibitor NIC-0102 (27) that specifically prevents NLRP3 inflammasome activation but has no effect on NLRC4 or AIM2 inflammasomes. In vitro studies revealed that NIC-0102 induced the polyubiquitination of NLRP3, interfered with the NLRP3-ASC interaction, and blocked ASC oligomerization, thereby resulting in the inhibition of NLRP3 inflammasome activation. In addition, NIC-0102 also inhibited the production of pro-IL-1β. Importantly, NIC-0102 showed potent anti-inflammatory effects on DSS-induced ulcerative colitis model in vivo. As a result of these studies, a potential small molecule is identified to demonstrate the possible link between the proteasome and NLRP3 pathway, which supports further exploration of potentially druggable nodes to modulate NLRP3 inflammasome activation.

Lepidium meyenii Walp (red maca) Supplementation Prevents Acrylamide-Induced Oxidative Stress and Liver Toxicity in Rats: Phytochemical Composition by UHPLC-ESI-MS/MS

Lepidium meyenii Walp (red maca) is a high Andean plant cultivated since the Incas and has innumerable therapeutic properties. The study aims to identify its phytochemical composition using UHPLC-ESI-MS/MS, and evaluate its effects on acrylamide-induced oxidative stress. The lyophilized aqueous extract of red maca (LAqE-RM) was orally administered in doses of 1 and 2 g/kg body weight for 4 weeks. Malondialdehyde (MDA) levels in erythrocytes, brain, and liver, as well as hepatic levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined. Administration of acrylamide for 2 and 4 weeks significantly increased (p < 0.001) MDA levels in erythrocytes, brain, and liver. However, LAqE-RM prevented (p < 0.001) an increase in MDA levels in all tissues studied. Likewise, the groups treated with LAqE-RM presented significantly (p < 0.001) lower levels of ALT and AST compared to the control. Treatment with LAqE-RM ameliorated the acrylamide-induced oxidative stress by reducing MDA levels in erythrocytes, brain, and liver and by lowering liver levels of ALT and AST in a dose-dependent manner. Twenty-five secondary metabolites were identified and characterized from LAqE-RM based on UHPLC mass spectrophotometry. These include carbolines, alkamides, fatty acids, and macamides, which are probably involved in their antioxidant protective role.

Mitochondria and the NLRP3 Inflammasome in Alcoholic and Nonalcoholic Steatohepatitis

Alcoholic (ASH) and nonalcoholic steatohepatitis (NASH) are advanced stages of fatty liver disease and two of the most prevalent forms of chronic liver disease. ASH and NASH are associated with significant risk of further progression to cirrhosis and hepatocellular carcinoma (HCC), the most common type of liver cancer, and a major cause of cancer-related mortality. Despite extensive research and progress in the last decades to elucidate the mechanisms of the development of ASH and NASH, the pathogenesis of both diseases is still poorly understood. Mitochondrial damage and activation of inflammasome complexes have a role in inducing and sustaining liver damage. Mitochondrial dysfunction produces inflammatory factors that activate the inflammasome complexes. NLRP3 inflammasome (nucleotide-binding oligomerization domain-like receptor protein 3) is a multiprotein complex that activates caspase 1 and the release of pro-inflammatory cytokines, including interleukin-1β (IL-1β) and interleukin-18 (IL-18), and contributes to inflammatory pyroptotic cell death. The present review, which is part of the issue "Mitochondria in Liver Pathobiology", provides an overview of the role of mitochondrial dysfunction and NLRP3 activation in ASH and NASH.

Bisphenol A Coupled with a High-Fat Diet Promotes Hepatosteatosis through Reactive-Oxygen-Species-Induced CD36 Overexpression

Bisphenol A (BPA) is an endocrine-disrupting chemical that affects lipid metabolism and contributes to non-alcoholic fatty liver disease (NAFLD). The mechanism of BPA exposure in hepatic lipid accumulation and its potential effect on NAFLD remain unclear. This study investigated the effect of BPA-exposure-induced hepatic lipid deposition on the pathology of NAFLD and its underlying mechanism in vitro and in vivo. BPA increased intracellular reactive oxygen species (ROS) levels, and promoted fatty acid uptake through upregulation of a free fatty acid uptake transporter, cluster of differentiation 36 (CD36), in HUH-7 cells. Additionally, C57BL/6 mice administered a high-fat/high-cholesterol/high-cholic acid diet (HFCCD) and BPA (50 mg/kg body weight) for 8 weeks developed a steatohepatitis-like phenotype, characterized by alpha-smooth muscle actin (α-SMA, an indicator of hepatic fibrosis) and cleaved caspase 3 (an indicator of apoptosis) in hepatic tissue; moreover, they had a higher oxidative stress index of 8-hydroxydeoxyguanosine (8-OHdG) in liver tissue compared to the control group. Treatment with ROS scavenger n-acetylcysteine (NAC) ameliorated BPA-mediated HFCCD-induced lipid accumulation and steatohepatitis in the livers of treated mice. Our study indicates that BPA acts synergistically to increase hepatic lipid uptake and promote NAFLD development by stimulating ROS-induced CD36 overexpression.

The NLRP3 Inflammasome in Non-Alcoholic Fatty Liver Disease and Steatohepatitis: Therapeutic Targets and Treatment

Non-alcoholic fatty liver disease (NAFLD) is among the most prevalent primary liver diseases worldwide and can develop into various conditions, ranging from simple steatosis, through non-alcoholic steatohepatitis (NASH), to fibrosis, and eventually cirrhosis and hepatocellular carcinoma. Nevertheless, there is no effective treatment for NAFLD due to the complicated etiology. Recently, activation of the NLPR3 inflammasome has been demonstrated to be a contributing factor in the development of NAFLD, particularly as a modulator of progression from initial hepatic steatosis to NASH. NLRP3 inflammasome, as a caspase-1 activation platform, is critical for processing key pro-inflammatory cytokines and pyroptosis. Various stimuli involved in NAFLD can activate the NLRP3 inflammasome, depending on the diverse cellular stresses that they cause. NLRP3 inflammasome-related inhibitors and agents for NAFLD treatment have been tested and demonstrated positive effects in experimental models. Meanwhile, some drugs have been applied in clinical studies, supporting this therapeutic approach. In this review, we discuss the activation, biological functions, and treatment targeting the NLRP3 inflammasome in the context of NAFLD progression. Specifically, we focus on the different types of therapeutic agents that can inhibit the NLRP3 inflammasome and summarize their pharmacological effectiveness for NAFLD treatment.

Modulatory Properties of Food and Nutraceutical Components Targeting NLRP3 Inflammasome Activation

Inflammasomes are key intracellular multimeric proteins able to initiate the cellular inflammatory signaling pathway. NLRP3 inflammasome represents one of the main protein complexes involved in the development of inflammatory events, and its activity has been largely demonstrated to be connected with inflammatory or autoinflammatory disorders, including diabetes, gouty arthritis, liver fibrosis, Alzheimer’s disease, respiratory syndromes, atherosclerosis, and cancer initiation. In recent years, it has been demonstrated how dietary intake and nutritional status represent important environmental elements that can modulate metabolic inflammation, since food matrices are an important source of several bioactive compounds. In this review, an updated status of knowledge regarding food bioactive compounds as NLRP3 inflammasome modulators is discussed. Several chemical classes, namely polyphenols, organosulfurs, terpenes, fatty acids, proteins, amino acids, saponins, sterols, polysaccharides, carotenoids, vitamins, and probiotics, have been shown to possess NLRP3 inflammasome-modulating activity through in vitro and in vivo assays, mainly demonstrating an anti-NLRP3 inflammasome activity. Plant foods are particularly rich in important bioactive compounds, each of them can have different effects on the pathway of inflammatory response, confirming the importance of the nutritional pattern (food model) as a whole rather than any single nutrient or functional compound.

Benzyl Isothiocyanate Attenuates Inflammasome Activation in Pseudomonas aeruginosa LPS-Stimulated THP-1 Cells and Exerts Regulation through the MAPKs/NF-κB Pathway

Inflammasomes are a group of intracellular multiprotein platforms that play important roles in immune systems. Benzyl isothiocyanate (BITC) is a constituent of cruciferous plants and has been confirmed to exhibit various biological activities. The modulatory effects of BITC on inflammasome-mediated interleukin (IL)-1β expression and its regulatory mechanisms in Pseudomonas aeruginosa (P. aeruginosa) LPS/ATP-stimulated THP-1 cells was investigated. Monocytic THP-1 cells were treated with phorbol myristate acetate (PMA) to induce differentiation into macrophages. Enzyme-linked immunosorbent assays (ELISA) were performed to measure the levels of IL-1β produced in P. aeruginosa LPS/ATP-exposed THP-1 cells. Western blotting was performed to examine the BITC modulatory mechanisms in inflammasome-mediated signaling pathways. BITC inhibited IL-1β production in P. aeruginosa LPS/ATP-induced THP-1 cells. BITC also inhibited activation of leucine-rich repeat protein-3 (NLRP3) and caspase-1 in P. aeruginosa LPS/ATP-induced THP-1 cells. Furthermore, we show that mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) activation in P. aeruginosa LPS was attenuated by BITC. These BITC-mediated modulatory effects on IL-1β production may have therapeutic potential for inflammasome-mediated disorders such as a nasal polyp.

Roles of Intramolecular Interactions in the Regulation of TRP Channels

The transient receptor potential (TRP) channels, classified into six (-A, -V, -P, -C, -M, -ML, -N and -Y) subfamilies, are important membrane sensors and mediators of diverse stimuli including pH, light, mechano-force, temperature, pain, taste, and smell. The mammalian TRP superfamily of 28 members share similar membrane topology with six membrane-spanning helices (S1-S6) and cytosolic N-/C-terminus. Abnormal function or expression of TRP channels is associated with cancer, skeletal dysplasia, immunodeficiency, and cardiac, renal, and neuronal diseases. The majority of TRP members share common functional regulators such as phospholipid PIP2, 2-aminoethoxydiphenyl borate (2-APB), and cannabinoid, while other ligands are more specific, such as allyl isothiocyanate (TRPA1), vanilloids (TRPV1), menthol (TRPM8), ADP-ribose (TRPM2), and ML-SA1 (TRPML1). The mechanisms underlying the gating and regulation of TRP channels remain largely unclear. Recent advances in cryogenic electron microscopy provided structural insights into 19 different TRP channels which all revealed close proximity of the C-terminus with the N-terminus and intracellular S4-S5 linker. Further studies found that some highly conserved residues in these regions of TRPV, -P, -C and -M members mediate functionally critical intramolecular interactions (i.e., within one subunit) between these regions. This review provides an overview on (1) intramolecular interactions in TRP channels and their effect on channel function; (2) functional roles of interplays between PIP2 (and other ligands) and TRP intramolecular interactions; and (3) relevance of the ligand-induced modulation of intramolecular interaction to diseases.

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.

Pyroptosis: A possible link between obesity-related inflammation and inflammatory diseases

The main manifestation of obesity is persistent low-level inflammation and insulin resistance, which is an important factor inducing or promoting other obesity-related diseases. As a proinflammatory programmed cell death, pyroptosis plays an important role, especially in the activation and regulation of the NLRP3 inflammasome pathway. Pyroptosis is associated with the pathogenesis of many chronic inflammatory diseases and is characterized by the formation of micropores in the plasma membrane and the release of a large number of proinflammatory cytokines. This article mainly introduces the main pathways and key molecules of pyroptosis and focuses on the phenomenon of pyroptosis in obesity. It is suggested that the regulation of pyroptosis-related targets may become a new potential therapy for the prevention and treatment of systemic inflammatory response caused by obesity, and we summarize the potential molecular substances that may be beneficial to obesity-related inflammatory diseases through target pyroptosis.

Formation and Cellular Impact of Cholesterol Crystals in Health and Disease

Cholesterol crystals (CCs) were first discovered in atherosclerotic plaque tissue in the early 1900 and have since been observed and implicated in many diseases and conditions, including myocardial infarction, abdominal aortic aneurism, kidney disease, ocular diseases, and even central nervous system anomalies. Despite the widespread involvement of CCs in many pathologies, the mechanisms involved in their formation and their role in various diseases are still not fully understood. Current knowledge concerning the formation of CCs, as well as the molecular pathways activated upon cellular exposure to CCs, will be explored in this review. As CC formation is tightly associated with lipid metabolism, the role of cellular lipid homeostasis in the formation of CCs is highlighted, including the role of lysosomes. In addition, cellular pathways and processes known to be affected by CCs are described. In particular, CC-induced activation of the inflammasome and production of reactive oxygen species, along with the role of CCs in complement-mediated inflammation is discussed. Moreover, the clinical manifestation of embolized CCs is described with a focus on renal and skin diseases associated with CC embolism. Lastly, potential therapeutic measures that target either the formation of CCs or their impact on different cell types and tissues are highlighted.

Inhibitory effects of sulforaphane on NLRP3 inflammasome activation

SFN, a dietary phytochemical, is a significant member of isothiocyanates present in cruciferous vegetables at high levels in broccoli. It is a well-known activator of the Nrf2/ARE antioxidant pathway. Long since, the therapeutic effects of SFN have been widely studied in several different diseases. Other than the antioxidant effect, SFN also exhibits an anti-inflammatory effect through suppression of various mechanisms, including inflammasome activation. Considerably, SFN has been demonstrated to inhibit multiple inflammasomes, including NLRP3 inflammasome. NLRP3 inflammasome induces secretion of pro-inflammatory cytokines and promotes inflammatory cell death. The release of pro-inflammatory cytokines enhances the inflammatory response, in turn leading to tissue damage. These self-propelling inflammatory responses would need modulation with exogenous therapeutic agents to suppress them. SFN is a promising candidate molecule for the mitigation of NLRP3 inflammasome activation, which has been related to the pathogenesis of numerous disorders. In this review, we have provided fundamental knowledge about Sulforaphane, elaborated its characteristics, and evidentially focused on its mechanisms of action with regard to its anti-inflammatory, anti-oxidative, and neuroprotective features. Thereafter, we have summarized both in vitro and in vivo studies regarding SFN effect on NLRP3 inflammasome activation.

Capillin protects against non-alcoholic steatohepatitis through suppressing NLRP3 inflammasome activation and oxidative stress

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is an extreme form of non-alcoholic fatty liver disease. The present study concentrated on the role of Capillin, a polyacetylene compound isolated from Artemisia capillaris Thunb., in NASH development.

MATERIALS AND METHODS

Palmitic acid (PA) was treated with FL83B hepatocytes, and high-fat diet was given to mouse to construct the NASH model in vivo. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method, flow cytometry, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were carried out to measure the viability and apoptosis of FL83B hepatocytes. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to measure the mRNA expressions of infiltration markers (Cd11c, Ccr2, and Ly6c), fibrosis genes (Tgfβ1, Col1a1, and Timp1), and alpha-smooth muscle actin (α-SMA). Western blot, immunofluorescence, and Enzyme-linked immunosorbent assay (ELISA) were implemented to examine the proteins of Caspase-3, Bcl2, Nrf2, HO-1, NLRP3, ASC, and Caspase-1, the ROS level, and oxidative stress markers (MDA, GSH-ST, SOD, and GSH-Px), and the lipid peroxidation level, respectively. Moreover, HE staining was manipulated to observe the histopathological changes in liver tissue.

RESULTS

Capillin hampered PA-mediated hepatocytes apoptosis and enhanced cell viability. Furthermore, Capillin suppressed PA-mediated oxidative stress in hepatocytes, promoted Nrf2/HO-1 expression, and repressed NLRP3-ASC-Caspase1 inflammasome. The in vivo studies indicated that Capillin vigorously improves liver fat accumulation, oxidative stress, and liver injury in NASH mice. Mechanistically, Capillin repressed NLRP3-ASC-Caspase1 inflammasome and up-regulated the Nrf2-HO-1 pathway in the liver.

CONCLUSION

Capillin ameliorates hepatocyte injury by dampening oxidative stress and repressing NLRP3 inflammasome in NASH mice.

Mitochondrial Mutations and Genetic Factors Determining NAFLD Risk

NAFLD (non-alcoholic fatty liver disease) is a widespread liver disease that is often linked with other life-threatening ailments (metabolic syndrome, insulin resistance, diabetes, cardiovascular disease, atherosclerosis, obesity, and others) and canprogress to more severe forms, such as NASH (non-alcoholic steatohepatitis), cirrhosis, and HCC (hepatocellular carcinoma). In this review, we summarized and analyzed data about single nucleotide polymorphism sites, identified in genes related to NAFLD development and progression. Additionally, the causative role of mitochondrial mutations and mitophagy malfunctions in NAFLD is discussed. The role of mitochondria-related metabolites of the urea cycle as a new non-invasive NAFLD biomarker is discussed. While mitochondria DNA mutations and SNPs (single nucleotide polymorphisms) canbe used as effective diagnostic markers and target for treatments, age and ethnic specificity should be taken into account.

Functional Application of Sulfur-Containing Spice Compounds

Sulfur-containing spice compounds possess diverse biological functions and play an important role in food, chemicals, pharmaceuticals, and agriculture. The development of functional spices has become increasingly popular, especially for medicinal functions for dietary health. Thus, this review focuses on the properties and functions of sulfur-containing spice compounds, including antioxidant, anti-inflammatory, antiobesity, anticancer, antibacterial, and insecticidal functions, among others. Developments over the last five years concerning the properties of sulfur-containing spice compounds are summarized and discussed.

Inhibitory effects of phytochemicals on NLRP3 inflammasome activation: A review

BACKGROUND

The NLRP3 inflammasome formation and following cytokine secretion is a crucial step in innate immune responses. Internal and external factors may trigger inflammasome activation and result in inflammatory cytokine secretion. Inflammasome formation and activity play critical roles in several disease pathologies such as cardiovascular, metabolic, renal, digestive, and CNS diseases. Underlying pathways are not yet clear, but phytochemicals as alternative therapies have been extensively used for suppression of inflammatory responses.

PURPOSE

In this review, we aimed to summarize in vivo and in vitro effects on NLRP3 inflammasome activation of selected phytochemicals.

METHOD

Three phytochemicals; Sulforaphane, Curcumin, and Resveratrol were selected, and studies were reviewed to clarify their intracellular signaling mechanism in NLRP3 inflammasome activity. PubMed and Scopus databases are used for the search. For sulforaphane, 8 articles, for curcumin, 25 articles, and for resveratrol, 41 articles were included in the review.

CONCLUSION

In vitro and in vivo studies pointed out that the selected phytochemicals have inhibitory properties on NLRP3 inflammasome activity. However, neither the mechanism is clear, nor the study designs and doses are standardized.

Kupffer Cells in Non-alcoholic Fatty Liver Disease: Friend or Foe?

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing all around the world and it may become the primary cause of terminal liver disease in adults and children in the next few decades. However, the pathogenesis of NAFLD is complex, and the Food and Drug Administration (FDA) has not approved any drugs for its treatment. Kupffer cells are the key cells regulating immunity in the liver, and the effect of their unique polarization on NAFLD has received increasing attention. Kupffer cells mainly reside in the lumen of hepatic sinusoids and account for 80% to 90% of colonized macrophages in the human body. They are phagocytic cells with the capacity for self-renewal that rarely migrate from their niche in the liver, and play a crucial role in regulating and maintaining homeostasis. Upon liver damage, Kupffer cells will be activated, releasing a good deal of inflammatory cytokines and chemokines. This review summarizes the multiple roles of Kupffer cells in the pathogenesis of NAFLD, the role of infiltrating macrophages in the pathogenesis of NAFLD is also briefly discussed, and aims to provide a theoretical basis for designing an NAFLD treatment strategy with Kupffer cells as the therapeutic target.