Bile Acids Activate NLRP3 Inflammasome, Promoting Murine Liver Inflammation or Fibrosis in a Cell Type-Specific Manner

Bile acids induce liver fibrosis through the NLRP3 inflammasome pathway and the mechanism of FXR inhibition of NLRP3 activation

BACKGROUND

Altered patterns of bile acids (BAs) are frequently present in liver fibrosis, and BAs function as signaling molecules to initiate inflammatory responses. Therefore, this study was conducted to uncover the notably altered components of BAs and to explore the pathway of altered BA induced inflammation in the development of liver fibrosis.

METHODS

Bile acids were quantified by ultraperformance liquid chromatography coupled to mass spectrometry (UPLC‒MS/MS). Cell Counting Kit-8 assays were used to determine the proliferative capacity of HSCs. Transwell assays and wound healing assays were used to determine the migratory capacity of LX2 cells. Protein expression was evaluated by western blotting.

RESULTS

Plasma bile acid analysis showed higher levels of GCDCA, TCDCA, GCA and TCA in patients with liver fibrosis than in normal controls. The AUC of GCDCA was the highest. Western blotting showed that GCDCA treatment increased the expression of NLRP3-related proteins and collagen1 in vitro and significantly increased LX2 cells proliferation and migration. Furthermore, knockdown of NLRP3 or overexpression of FXR in LX2 cells decreased the expression of the above proteins, and FXR inhibited NLRP3 (ser 295) phosphorylation in vitro and vivo. In vivo, HE, Masson's trichrome, and Sirius Red staining showed that GCDCA increased collagen fibers in the mouse liver, and the expression of NLRP3-related proteins, collagen 1, and α-SMA in the liver increased significantly. However, the knockout of NLRP3 reversed these patterns.

CONCLUSION

(1) Primary conjugated bile acids increased in patients with liver fibrosis; (2) GCDCA induce hepatic fibrosis via the NLRP3 inflammasome pathway; (3) FXR inhibits NLRP3 activity by restraining its phosphorylation; (4) knockdown or knockout of NLRP3 may relieve the onset of hepatic fibrosis.

Metabolite-derived damage-associated molecular patterns in immunological diseases

Damage-associated molecular patterns (DAMPs) are typically derived from the endogenous elements of necrosis cells and can trigger inflammatory responses by activating DAMPs-sensing receptors on immune cells. Failure to clear DAMPs may lead to persistent inflammation, thereby contributing to the pathogenesis of immunological diseases. This review focuses on a newly recognized class of DAMPs derived from lipid, glucose, nucleotide, and amino acid metabolic pathways, which are then termed as metabolite-derived DAMPs. This review summarizes the reported molecular mechanisms of these metabolite-derived DAMPs in exacerbating inflammation responses, which may attribute to the pathology of certain types of immunological diseases. Additionally, this review also highlights both direct and indirect clinical interventions that have been explored to mitigate the pathological effects of these DAMPs. By summarizing our current understanding of metabolite-derived DAMPs, this review aims to inspire future thoughts and endeavors on targeted medicinal interventions and the development of therapies for immunological diseases.

A bidirectional two-sample Mendelian randomization using the gut microbiota to reveal potential therapeutic targets for primary sclerosing cholangitis

BACKGROUND

Previous studies indicate that gut microbiota correlates to primary sclerosing cholangitis (PSC), but the causation is still unclear. We sought to reveal the causal relationship between gut microbiota and PSC with a bidirectional two-sample Mendelian randomization (MR) analysis.

METHODS

The large-scale genome-wide association study (GWAS) summary statistics and a bidirectional two-sample MR study were used to assess the causality between gut microbiota and PSC. Multiple sensitivity analyses were used to identify the robustness of our results.

RESULTS

Three microbial taxa causally correlated to PSC. Genus Ruminococcaceae UCG002 (OR: 1.855, 95% CI: 1.068-3.220, P = 0.028) increased the risk of PSC. Class Betaproteobacteria (OR: 0.360, 95% CI: 0.171-0.758, P = 0.007), and genus Ruminiclostridium6 (OR: 0.474, 95% CI: 0.219-0.820, P = 0.011) had protective effects on PSC. In addition, we found the causal relationship of PSC with higher abundance of genus Dialister (beta: 0.059, 95% CI: 0.017-0.102, P = 0.006), genus Veillonella (beta: 0.065, 95% CI: 0.016-0.113, P = 0.009), class Melainabacteria (beta: 0.073, 95% CI: 0.012-0.133, P = 0.019), and order Gastranaerophilales (beta: 0.072, 95% CI: 0.011-0.113, P = 0.133).

CONCLUSION

Our study reveals the causality between gut microbiota and PSC, providing new insights into the pathological mechanisms of PSC and facilitating the development of novel biomarkers and disease-modifying therapeutics for PSC from the perspective of gut microbiota.

Suppressive effect of Tripterygium hypoglaucum (Levl.) Hutch extract on rheumatoid arthritis in mice by modulating inflammasome and bile acid metabolism

Tripterygium hypoglaucum (Levl.) Hutch (THH) has long been used as a remedy for rheumatoid arthritis (RA) in China. However, it is unclear whether the anti-RA mechanism of THH is associated with inflammasome or gut-joint axis. In this study, we aimed to explore the critical role of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and bile acid (BA) in the anti-RA mechanism. Complete Freund's adjuvant (CFA)-injected mice were treated with THH extract (250 mg/kg/d) for 35 days, and joint swelling and disease scores were measured. After THH treatment, the joint swelling and RA disease score in CFA-treated mice significantly subsided. The increased ratios of lymphocytes, monocytes, and white blood cells were attenuated by THH treatment. Notably, THH treatment blocked the inflammation in both joints and colons by suppressing the NLRP3-mediated inflammasome, as indicated by NLRP3, interleukin 1beta (IL-1β), and Caspase-1. Meanwhile, THH significantly remodeled the bile acid (BA) profiles in RA mice. Spearman's analysis shed light on the close link between BAs, NLRP3 inflammasome, and RA indicators. However, THH treatment failed to improve inflammasome activation, snoptivis, and joint swelling in RA mice with gut microbiota depletion. In summary, we revealed the pivotal role of BA-mediated gut-joint axis and inflammasome in THH's RA amelioration. In the future, more work should be done to explain the in-depth mechanism between altered BAs and inflammasome.

Disruption of IL-18 signaling via engineered IL-18BP biologics alleviates experimental cholestatic liver disease

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by progressive inflammation and fibrosis around intrahepatic and extrahepatic bile ducts leading to severe hepatic cirrhosis and high mortality. Although there is an urgent clinical unmet need for PSC, no effective medical therapy has been developed to delay the disease progression until today. IL-18 binding protein (IL-18BP) is well-known to be a natural negative feedback regulator for IL-18, and we have developed a recombinant long-acting IL-18BP referred to as APB-R3 as a therapeutic agent to treat IL-18-related inflammatory diseases. Here, we aimed to study whether disrupted IL-18 signaling by APB-R3 treatment can inhibit PSC injuries in the experimental DDC diet-induced PSC rodent model. First, we found that the amounts of free IL-18 are augmented under PSC condition with increased expression of biliary IL-18 receptors. Administration of APB-R3 effectively attenuated key diagnostic parameters of PSC such as plasma ALP and GGT levels as well as bile acids levels. We also observed that blockade of IL-18 suppressed ductular reactive and proliferative phenotypes of cholangiocytes. Additionally, APB-R3 significantly ameliorated DDC diet-induced periductal fibrosis and transcriptional expressions of pro-fibrotic marker genes. Enhanced senescence associated secretory phenotype (SASP) markers in cholestatic liver disease were diminished by APB-R3 treatment. Our findings clearly demonstrate that the administration of IL-18BP biologics, APB-R3, effectively alleviates DDC diet-induced biliary injuries in rodent PSC model, implying APB-R3 can be a promising therapeutic reagent which warrants clinical human trials as new therapeutic options.

Chuanxiong Rhizoma extracts prevent cholestatic liver injury by targeting H3K9ac-mediated and cholangiocyte-derived secretory protein PAI-1 and FN

Chuanxiong Rhizoma (CX, the dried rhizome of Ligusticum wallichii Franch.), a well-known traditional Chinese medicine, is clinically used for treating cardiovascular, cerebrovascular and hepatobiliary diseases. Cholestatic liver damage is one of the chronic liver diseases with limited effective therapeutic strategies. Currently, little is known about the mechanism links between CX-induced anti-cholestatic action and intercellular communication between cholangiocytes and hepatic stellate cells (HSCs). The study aimed to evaluate the hepatoprotective activity of different CX extracts including the aqueous, alkaloid, phenolic acid and phthalide extracts of CX (CXAE, CXAL, CXPA and CXPHL) and investigate the intercellular communication-related mechanisms by which the most effective extracts work on cholestatic liver injury. The active compounds of different CX extracts were identified by UPLC-MS/MS. A cholestatic liver injury mouse model induced by bile duct ligation (BDL), and transforming growth factor-β (TGF-β)-treated human intrahepatic biliary epithelial cholangiocytes (HIBECs) and HSC cell line (LX-2 cells) were used for in vivo and in vitro studies. Histological and other biological techniques were also applied. The results indicated that CXAE, CXAL and CXPHL significantly reduced ductular reaction (DR) and improved liver fibrosis in the BDL mice. Meanwhile, both CXAE and CXPHL suppressed DR in injured HIBECs and reduced collagen contraction force and the expression of fibrosis biomarkers in LX-2 cells treated with TGF-β. CXPHL suppressed the transcription and transfer of plasminogen activator inhibitor-1 (PAI-1) and fibronectin (FN) from the 'DR-like' cholangiocytes to activated HSCs. Mechanistically, the inhibition of PAI-1 and FN by CXPHL was attributed to the untight combination of the acetyltransferase KAT2A and SMAD3, followdd by the suppression of histone 3 lysine 9 acetylation (H3K9ac)-mediated transcription in cholangiocytes. In conclusion, CXPHL exerts stronger anti-cholestatic activity in vivo and in vitro than other CX extracts, and its protective effect on the intracellular communication between cholangiocytes and HSCs is achieved by reducing KAT2A/H3K9ac-mediated transcription and release of PAI-1 and FN.

Are gut dysbiosis, barrier disruption, and endotoxemia related to adipose tissue dysfunction in metabolic disorders? Overview of the mechanisms involved

Recently, compelling evidence points to dysbiosis and disruption of the epithelial intestinal barrier as major players in the pathophysiology of metabolic disorders, such as obesity. Upon the intestinal barrier disruption, components from bacterial metabolism and bacteria itself can reach peripheral tissues through circulation. This has been associated with the low-grade inflammation that characterizes obesity and other metabolic diseases. While circulating bacterial DNA has been postulated as a common feature of obesity and even type 2 diabetes, almost no focus has been given to the existence and effects of bacteria in peripheral tissues, namely the adipose tissue. As a symbiont population, it is expected that gut microbiota modulate the immunometabolism of the host, thus influencing energy balance mechanisms and inflammation. Gut inflammatory signals cause direct deleterious inflammatory responses in adipose tissue and may also affect key gut neuroendocrine mechanisms governing nutrient sensing and energy balance, like incretins and ghrelin, which play a role in the gut-brain-adipose tissue axis. Thus, it is of major importance to disclose how gut microbiota and derived signals modulate neuroendocrine and inflammatory pathways, which contribute to the dysfunction of adipose tissue and to the metabolic sequelae of obesity and related disorders. This review summarizes the current knowledge regarding these topics and identifies new perspectives in this field of research, highlighting new pathways toward the reduction of the inflammatory burden of metabolic diseases.

Portrayal of NLRP3 Inflammasome in Atherosclerosis: Current Knowledge and Therapeutic Targets

We are witnessing the globalization of a specific type of arteriosclerosis with rising prevalence, incidence and an overall cardiovascular disease burden. Currently, atherosclerosis increasingly affects the younger generation as compared to previous decades. While early preventive medicine has seen improvements, research advances in laboratory and clinical investigation promise to provide us with novel diagnosis tools. Given the physio-pathological complexity and epigenetic patterns of atherosclerosis and the discovery of new molecules involved, the therapeutic field of atherosclerosis has room for substantial growth. Thus, the scientific community is currently investigating the role of nucleotide-binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, a crucial component of the innate immune system in different inflammatory disorders. NLRP3 is activated by distinct factors and numerous cellular and molecular events which trigger NLRP3 inflammasome assembly with subsequent cleavage of pro-interleukin (IL)-1β and pro-IL-18 pathways via caspase-1 activation, eliciting endothelial dysfunction, promotion of oxidative stress and the inflammation process of atherosclerosis. In this review, we introduce the basic cellular and molecular mechanisms of NLRP3 inflammasome activation and its role in atherosclerosis. We also emphasize its promising therapeutic pharmaceutical potential.

TNF-α/IL-1β-licensed hADSCs alleviate cholestatic liver injury and fibrosis in mice via COX-2/PGE2 pathway

BACKGROUND

Adipose tissue-derived stem cell (ADSC) transplantation has been shown to be effective for the management of severe liver disorders. Preactivation of ADSCs enhanced their therapeutic efficacy. However, these effects have not yet been examined in relation to cholestatic liver injury.

METHODS

In the present study, a cholestatic liver injury model was established by bile duct ligation (BDL) in male C57BL/6 mice. Human ADSCs (hADSCs) with or without tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) pretreatment were administrated into the mice via tail vein injections. The efficacy of hADSCs on BDL-induced liver injury was assessed by histological staining, real-time quantitative PCR (RT-qPCR), Western blot, and enzyme-linked immune sorbent assay (ELISA). In vitro, the effects of hADSC conditioned medium on the activation of hepatic stellate cells (HSCs) were investigated. Small interfering RNA (siRNA) was used to knock down cyclooxygenase-2 (COX-2) in hADSCs.

RESULTS

TNF-α/IL-1β preconditioning could downregulate immunogenic gene expression and enhance the engraftment efficiency of hADSCs. Compared to control hADSCs (C-hADSCs), TNF-α/IL-1β-pretreated hADSCs (P-hADSCs) significantly alleviated BDL-induced liver injury, as demonstrated by reduced hepatic cell death, attenuated infiltration of Ly6G + neutrophils, and decreased expression of pro-inflammatory cytokines TNF-α, IL-1β, C-X-C motif chemokine ligand 1 (CXCL1), and C-X-C motif chemokine ligand 2 (CXCL2). Moreover, P-hADSCs significantly delayed the development of BDL-induced liver fibrosis. In vitro, conditioned medium from P-hADSCs significantly inhibited HSC activation compared to that from C-hADSCs. Mechanistically, TNF-α/IL-1β upregulated COX-2 expression and increased prostaglandin E2 (PGE2) secretion. The blockage of COX-2 by siRNA transfection reversed the benefits of P-hADSCs for PGE2 production, HSC activation, and liver fibrosis progression.

CONCLUSION

In conclusion, our results suggest that TNF-α/IL-1β pretreatment enhances the efficacy of hADSCs in mice with cholestatic liver injury, partially through the COX-2/PGE2 pathway.

NLRP3 Inflammasome: A key contributor to the inflammation formation

Inflammation is an important part of the development of various organ diseases. The inflammasome, as an innate immune receptor, plays an important role in the formation of inflammation. Among various inflammasomes, the NLRP3 inflammasome is the most well studied. The NLRP3 inflammasome is composed of skeletal protein NLRP3, apoptosis-associated speck-like protein (ASC) and pro-caspase-1. There are three types of activation pathways: (1) "classical" activation pathway; (2) "non-canonical" activation pathway; (3) "alternative" activation pathway. The activation of NLRP3 inflammasome is involved in many inflammatory diseases. A variety of factors (such as genetic factors, environmental factors, chemical factors, viral infection, etc.) have been proved to activate NLRP3 inflammasome and promote the inflammatory response of the lung, heart, liver, kidney and other organs in the body. Especially, the mechanism of NLRP3 inflammation and its related molecules in its associated diseases remains not to be summarized, namely they may promote or delay inflammatory diseases in different cells and tissues. This article reviews the structure and function of the NLRP3 inflammasome and its role in various inflammations, including inflammations caused by chemically toxic substances.

The impact of subchronic ozone exposure on serum metabolome and the mechanisms of abnormal bile acid and arachidonic acid metabolisms in the liver

Ambient ozone (O₃) pollution can induce respiratory and cardiovascular toxicity. However, its impact on the metabolome and the underlying mechanisms remain unclear. This study first investigated the serum metabolite changes in rats exposed to 0.5 ppm O₃ for 3 months using untargeted metabolomic approach. Results showed chronic ozone exposure significantly altered the serum levels of 34 metabolites with potential increased risk of digestive, respiratory and cardiovascular disease. Moreover, bile acid synthesis and secretion, and arachidonic acid (AA) metabolism became the most prominent affected metabolic pathways after O₃ exposure. Further studies on the mechanisms found that the elevated serum toxic bile acid was not due to the increased biosynthesis in the liver, but the reduced reuptake from the portal vein to hepatocytes owing to repressed Ntcp and Oatp1a1, and the decreased bile acid efflux in hepatocytes as a results of inhibited Bsep, Ostalpha and Ostbeta. Meanwhile, decreased expressions of detoxification enzyme of SULT2A1 and the important regulators of FXR, PXR and HNF4α also contributed to the abnormal bile acids. In addition, O₃ promoted the conversion of AA into thromboxane A2 (TXA2) and 20-hydroxyarachidonic acid (20-HETE) in the liver by up-regulation of Fads2, Cyp4a and Tbxas1 which resulting in decreased AA and linoleic acid (LA), and increased thromboxane B2 (TXB2) and 20-HETE in the serum. Furthermore, apparent hepatic chronic inflammation, fibrosis and abnormal function were found in ozone-exposed rats. These results indicated chronic ozone exposure could alter serum metabolites by interfering their metabolism in the liver, and inducing liver injury to aggravate metabolic disorders.

The role of the gut microbiome and its metabolites in cerebrovascular diseases

The gut microbiome is critically involved in maintaining normal physiological function in the host. Recent studies have revealed that alterations in the gut microbiome contribute to the development and progression of cerebrovascular disease via the microbiota-gut-brain axis (MGBA). As a broad communication network in the human body, MGBA has been demonstrated to have significant interactions with various factors, such as brain structure and function, nervous system diseases, etc. It is also believed that the species and composition of gut microbiota and its metabolites are intrinsically linked to vascular inflammation and immune responses. In fact, in fecal microbiota transplantation (FMT) research, specific gut microbiota and downstream-related metabolites have been proven to not only participate in various physiological processes of human body, but also affect the occurrence and development of cerebrovascular diseases directly or indirectly through systemic inflammatory immune response. Due to the high mortality and disability rate of cerebrovascular diseases, new treatments to improve intestinal dysbacteriosis have gradually attracted widespread attention to better ameliorate the poor prognosis of cerebrovascular diseases in a non-invasive way. This review summarizes the latest advances in the gut microbiome and cerebrovascular disease research and reveals the profound impact of gut microbiota dysbiosis and its metabolites on cerebrovascular diseases. At the same time, we elucidated molecular mechanisms whereby gut microbial metabolites regulate the expression of specific interleukins in inflammatory immune responses. Moreover, we further discuss the feasibility of novel therapeutic strategies targeting the gut microbiota to improve the outcome of patients with cerebrovascular diseases. Finally, we provide new insights for standardized diagnosis and treatment of cerebrovascular diseases.

Bile Acids in Intrahepatic Cholestasis of Pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is the most common, reversible, and closely related to pregnancy condition characterized by elevated levels of bile acids (BAs) in blood serum and an increased risk of adverse perinatal outcomes. Due to the complex interactions between the mother and the fetus in metabolism and transplacental BAs transport, ICP is classified as a fetal-maternal disease. The disease is usually mild in pregnant women, but it can be fatal to the fetus, leading to numerous complications, including intrauterine death. The pathophysiology of the disease is based on inflammatory mechanisms caused by elevated BA levels. Although ICP cannot be completely prevented, its early diagnosis and prompt management significantly reduce the risk of fetal complications, the most serious of which is unexpected intrauterine death. It is worth emphasizing that all diagnostics and management of ICP during pregnancy are based on BA levels. Therefore, it is important to standardize the criteria for diagnosis, as well as recommendations for management depending on the level of BAs, which undoubtedly determines the impact on the fetus. The purpose of this review is to present the potential and importance of BAs in the detection and rules of medical procedure in ICP.

Antarctic krill peptide alleviates liver fibrosis via downregulating the secondary bile acid mediated NLRP3 signaling pathway

Liver fibrosis is a necessary process for liver disease. Recent studies have reported that the enterohepatic circulation of bile acid plays a vital role in developing liver fibrosis. The Antarctic krill peptide (AKP) has been proved to have a variety of activities such as antioxidant and anti-inflammatory, but any possible influence on liver fibrosis remains unclear. In the current study, the liver fibrosis mice were intraperitoneal injection of carbon tetrachloride (2.5%, 10 mL kg^-1) and oral administration AKP (400 mg kg^-1) for 30 days. The results showed that the AKP supplement decreased the serum ALT and AST levels, reduced the content of liver TNF-α and Collagen I, and improved liver inflammation and fibrosis, which was also confirmed by H&E and Masson staining. Bile acid is an important metabolite for the gut microbiota. We found that the AKP supplement alleviated the gut microbiota dysbiosis remarkably, as indicated by increased species richness and diversity, and decreased overgrowth of genera Bifidobacterium, Lactobacillus, Bacteroides, Clostridiales and Fusicatenibacter. Furthermore, AKP mediated gut microbiota improvement decreased the intestinal bile salt hydrolase and 7α-dehydroxylation activities, resulting in the decrease of secondary bile acid taurodeoxycholic acid (TDCA) and taurolithocholic acid (TLCA) concentrations. Mechanistically, AKP inhibited NLRP3 signal by downregulating the secondary bile acid, decreased cleaved Caspase-1 expression to suppress IL-1β-mediated hepatic stellate cell activation. This study reports for the first time that AKP improved liver fibrosis via improving the gut microbiota mediated bile acid-NLRP3 signaling, which might provide new ideas and evidence for Antarctic krill's high-value utilization.

Total glucosides of paeony inhibits liver fibrosis and inflammatory response associated with cirrhosis via the FLI1/NLRP3 axis

BACKGROUND

Total glucosides of paeony (TGP) has a myriad of hepatoprotective activities. However, its role in cirrhosis, a major risk factor for hepatocellular carcinoma, remains largely unexplored. Here, we determined the impact of TGP on liver fibrosis and inflammation in mice modeled by carbon tetrachloride with an aim to explore a possible molecular mechanism.

METHODS

Liver fibrosis and inflammation in mice were evaluated using ELISA, hematoxylin-eosin, Masson's trichrome, immunohistochemical staining and TUNEL methods. The impact of TGP on gene expression in the liver tissues of the mice was investigated using microarray analysis, showing the most significant increase in expression of friend leukemia integration 1 transcription factor (FLI1). After loss-of-functions assays of FLI1, the downstream gene of FLI1 was searched by bioinformatics analysis and verified.

RESULTS

TGP reduced liver tissue damage, inhibited apoptosis, and alleviated liver fibrosis and inflammation in cirrhotic mice. FLI1 was downregulated in the liver of cirrhotic mice and lipopolysaccharide-treated hepatocytes, and TGP promoted the expression of FLI1. FLI1 depletion inhibited the effects of TGP on alleviating liver fibrosis and inflammatory responses in mice. FLI1 repressed Nod-like receptor protein 3 (NLRP3) transcription by binding to its promoter. Further silencing of NLRP3 in the presence of shFLI1 alleviated histopathological changes, inhibited apoptosis, and attenuated liver fibrosis and inflammatory responses in the liver of cirrhotic mice.

CONCLUSIONS

TGP promotes the expression of FLI1, which in turn inhibits NLRP3 expression, thereby reducing cirrhosis-induced liver fibrosis and inflammatory response in mice.

A single local delivery of paclitaxel and nucleic acids via an immunoactive polymer eliminates tumors and induces antitumor immunity

SignificanceThe rationale of local cancer immunotherapy is that the treated tumor cells can serve as a depot of tumor antigens and activate/mobilize the patient's immune system to address systemic diseases. However, the challenge is to coordinate several events involved in the activation of antitumor immune responses, colocalize and retain multiple therapies in tumors, and support the functions of immune cells. Our carrier polyethyleneimine-lithocholic acid conjugate (2E') addresses these challenges based on the amphiphilic structure and inherent immunostimulatory activity. 2E' codelivers hydrophobic drugs and nucleic acids and leverages their effects to eliminate primary tumors and protect the hosts from distant and recurrent diseases. The versatility of 2E' will enable the use of therapeutic combinations to improve clinical outcomes of cancer immunotherapy.

The Mechanism and Regulation of the NLRP3 Inflammasome during Fibrosis

Fibrosis is often the end result of chronic inflammation. It is characterized by the excessive deposition of extracellular matrix. This leads to structural alterations in the tissue, causing permanent damage and organ dysfunction. Depending on the organ it effects, fibrosis can be a serious threat to human life. The molecular mechanism of fibrosis is still not fully understood, but the NLRP3 (NOD-, LRR- and pyrin–domain–containing protein 3) inflammasome appears to play a significant role in the pathogenesis of fibrotic disease. The NLRP3 inflammasome has been the most extensively studied inflammatory pathway to date. It is a crucial component of the innate immune system, and its activation mediates the secretion of interleukin (IL)-1β and IL-18. NLRP3 activation has been strongly linked with fibrosis and drives the differentiation of fibroblasts into myofibroblasts by the chronic upregulation of IL-1β and IL-18 and subsequent autocrine signaling that maintains an activated inflammasome. Both IL-1β and IL-18 are profibrotic, however IL-1β can have antifibrotic capabilities. NLRP3 responds to a plethora of different signals that have a common but unidentified unifying trigger. Even after 20 years of extensive investigation, regulation of the NLRP3 inflammasome is still not completely understood. However, what is known about NLRP3 is that its regulation and activation is complex and not only driven by various activators but controlled by numerous post-translational modifications. More recently, there has been an intensive attempt to discover NLRP3 inhibitors to treat chronic diseases. This review addresses the role of the NLRP3 inflammasome in fibrotic disorders across many different tissues. It discusses the relationships of various NLRP3 activators to fibrosis and covers different therapeutics that have been developed, or are currently in development, that directly target NLRP3 or its downstream products as treatments for fibrotic disorders.

Intestinal Barrier and Permeability in Health, Obesity and NAFLD

The largest surface of the human body exposed to the external environment is the gut. At this level, the intestinal barrier includes luminal microbes, the mucin layer, gastrointestinal motility and secretion, enterocytes, immune cells, gut vascular barrier, and liver barrier. A healthy intestinal barrier is characterized by the selective permeability of nutrients, metabolites, water, and bacterial products, and processes are governed by cellular, neural, immune, and hormonal factors. Disrupted gut permeability (leaky gut syndrome) can represent a predisposing or aggravating condition in obesity and the metabolically associated liver steatosis (nonalcoholic fatty liver disease, NAFLD). In what follows, we describe the morphological-functional features of the intestinal barrier, the role of major modifiers of the intestinal barrier, and discuss the recent evidence pointing to the key role of intestinal permeability in obesity/NAFLD.