Methane-Rich Saline Counteracts Cholestasis-Induced Liver Damage via Regulating the TLR4/NF-κB/NLRP3 Inflammasome Pathway

Metformin improves intestinal ischemia-reperfusion injury by reducing the formation of mitochondrial associated endoplasmic reticulum membranes (MAMs) and inhibiting ferroptosis in intestinal cells

Introduction

Intestinal ischemia-reperfusion (I/R) injury represents an inevitable and formidable postoperative challenge for all clinical surgeons. Ferroptosis has emerged as a crucial factor in the pathogenesis of intestinal I/R injury. Metformin, which is known to exhibit antiferroptotic properties, has elicited significant attention from both researchers and clinicians. This study was designed to comprehensively examine the protective effects of metformin against intestinal I/R injury and to elucidate the underlying potential mechanisms.

Methods

To achieve this goal, both in vivo and in vitro models of I/R injury were established. For the in vivo experiments, metformin was administered via intraperitoneal injection at the onset of reperfusion.

Results

The results from HE staining in the in vivo model, along with IF staining of tight junction proteins in the in vitro model, clearly demonstrated that metformin effectively mitigated the damage to the intestinal barrier following I/R injury. Additionally, metformin was shown to improve ROS levels and mitochondrial function in the context of I/R injury. Moreover, metfornin was observed to reduce the formation of mitochondria-associated membranes (MAMs), which is a process that is intricately linked to the onset of ferroptosis. Significantly, Western blot analysis of key ferroptosis-related proteins, including GPX4, FTH1 and SLC7A11, indicated that metformin inhibited ferroptosis.

Discussion

In conclusion, this study suggests that metformin exerts beneficial effects on intestinal I/R injury by suppressing MAM formation and ferroptosis, thereby highlighting its potential as a therapeutic agent for this challenging clinical condition.

Diacerein counteracts amiodarone‑induced hepatotoxicity in rats via targeting TLR4/NF-kB/NLRP3 pathways

This study investigates the protective effects of diacerein (DCN) against amiodarone (AMIO)-induced hepatotoxicity in a rat model. AMIO administration resulted in significant elevations of liver enzymes, ALT and AST, indicating hepatocellular membrane disruption and oxidative stress, as demonstrated by elevated levels of malondialdehyde (MDA) and decreased glutathione (GSH). Additionally, pro-inflammatory cytokines including TNF-α and IL-1β were expressed more when AMIO triggered the Toll-like receptor 4/nuclear factor kappa B/inflammasome 3 (TLR4/NF-κB/NLRP3) inflammatory pathway, along with elevated caspase-1 (CASP1) levels, which promoted apoptosis. In contrast, oral administration of DCN for two weeks effectively mitigated these effects by reducing liver enzyme levels and improving histopathological alterations. DCN also demonstrated anti-oxidant properties by decreasing MDA levels and increasing nuclear factor erythroid 2-related factor 2 (Nrf2) and GSH content. Furthermore, DCN downregulated the hepatic content of TLR4, NF-κB p65, NLRP3, CASP1, and pro-inflammatory cytokines, thereby inhibiting the activation of the inflammatory cascade. Moreover, DCN reduced protein expression of caspase 3. Those findings suggest that DCN exerts its hepatoprotective effects through its anti-oxidant activity, modulation of TLR4/NF-κB/NLRP3 inflammatory pathways, and reduction of apoptosis. These results provide new insights into potential therapeutic strategies for managing AMIO-induced hepatotoxicity, warranting further investigation into the underlying molecular mechanisms of DCN's protective effects.

Neutrophil extracellular traps-induced pyroptosis of liver sinusoidal endothelial cells exacerbates intrahepatic coagulation in cholestatic mice

BACKGROUND

Neutrophil extracellular traps (NETs) and NOD-like receptor protein 3 (NLRP3) inflammation are key contributors to cholestatic liver disease (CLD). However, the relationship between NETs release and inflammasome activation, as well as its contribution to intrahepatic coagulation in CLD, remains unexplored. This study explores NETs-induced liver sinusoidal endothelial cells (LSECs) pyroptosis on intrahepatic coagulation in CLD.

METHODS

Wild-type (WT) and PAD4-/- mice underwent bile duct ligation (BDL) or sham surgery for 7 or 14 days. The liver analysis assessed intrahepatic coagulation, inflammation, fibrosis, NETs release, and NLRP3 activation. Primary LSECs were exposed to NETs with or without MCC950. Pyroptosis and LSECs procoagulant activity were quantified.

RESULTS

BDL mice exhibited significantly increased inflammation, tissue factor (TF), and fibrin deposition compared with controls. NETs release in the liver was increased significantly in WT BDL mice and was responsible for intrahepatic coagulation. PAD4 deficiency reduced TF and fibrin expression, improving hepatic sinusoid function. RNA-seq revealed BDL-induced enrichment of coagulation, neutrophil activation, and pyroptosis pathways. In vivo, NETs increased intrahepatic NLRP3 and IL-1β expression in BDL mice. However, NLRP3 inhibition (MCC950) or activation (BMS-986299) did not alter NETs release. Furthermore, NETs-induced NLRP3 activation increased intrahepatic coagulation, inflammation, and fibrosis. Finally, we demonstrated that NETs triggered LSECs dysfunction and pyroptosis, upregulating TF and phosphatidylserine production and enhancing procoagulant activity.

CONCLUSIONS

NETs-induced LSECs pyroptosis exacerbates intrahepatic coagulation in cholestasis. Targeting NETs and LSECs pyroptosis holds promise for treating chronic liver injury in CLD.

Molecular insights of T-2 toxin exposure-induced neurotoxicity and the neuroprotective effect of dimethyl fumarate

T-2 toxin, a potent environmental pollutant, has been proved to stimulate neuroinflammation, while the connection between T-2 toxin and pyroptosis remain elusive. Dimethyl fumarate (DMF), recently identified as a neuroprotectant and pyroptosis inhibitor, has potential therapeutic applications that are underexplored. Based on present study in vitro and vivo, we demonstrated that T-2 toxin induced the activation of NLRP3-Caspase-1 inflammasome in hippocampal neurons. In addition to proinflammatory mediator overexpression, gasdermin D (GSDMD)-dependently pyroptosis in the mouse hippocampal neuron cell line (HT22) treated by T-2 toxin was determined in our study. Moreover, the palliative effect of knockdown sequence of high mobility group B1 protein (HMGB1) provided more details for T-2 toxin-initiated pyroptosis. Importantly, we confirmed that DMF, as a novel inhibitor of GSDMD, could alleviate pyroptosis induced by T-2 toxin in an GSDMD targeting manner. In summary, our studies exposed the evidence that T-2 toxin could induce NLRP3 inflammasome activation and hippocampal neuronal pyroptosis. More notably, DMF was turn out to be a critical executioner for attenuating GSDMD-mediated pyroptosis. Our data found a new function of DMF and suggested a novel therapy strategy against mycotoxin-triggered neuronal inflammation, which leads to varieties of neurological diseases.

The role of the SIRT1/NF-κB/NLRP3 pathway in the pyroptosis of lens epithelial cells under shortwave blue light radiation

Cataracts are the world's number one blinding eye disease. Cataracts can only be effectively treated surgically, although there is a chance of surgical complications. One of the pathogenic processes of cataracts is oxidative stress, which closely correlated with pyroptosis. SIRT1 is essential for the regulation of pyroptosis. Nevertheless, the role of SIRT1 in formation of cataracts is unclear. In this work, we developed an in vitro model of shortwave blue light (SWBL)-induced scotomization in human lens epithelial cells (HLECs) and an in vivo model of SWBL-induced cataracts in rats. The study aimed to understand how the SIRT1/NF-κB/NLRP3 pathway functions. Additionally, the evaluation included cell death and the release of lactate dehydrogenase (LDH), a cytotoxicity marker, from injured cells. First, we discovered that SWBL exposure resulted in lens clouding in Sprague- Dawley (SD) rats and that the degree of clouding was positively linked to the duration of irradiation. Second, we discovered that SIRT1 exhibited antioxidant properties and was connected to the NF-κB/NLRP3 pathway. SWBL irradiation inhibited SIRT1 expression, exacerbated oxidative stress, and promoted nuclear translocation of NF-κB and the activation of the NLRP3 inflammasome, which caused LEC pyroptosis and ultimately led to cataract formation. Transient transfection to increase the expression of SIRT1 decreased the protein expression levels of NF-κB, NLRP3, caspase-1, and GSDMD, inhibited HLEC pyroptosis, and reduced the release of LDH, providing a potential method for cataract prevention and treatment.

Progress in the Correlation Between Inflammasome NLRP3 and Liver Fibrosis

Liver fibrosis is a reversible condition that occurs in the early stages of chronic liver disease. To develop effective treatments for liver fibrosis, understanding the underlying mechanism is crucial. The NOD-like receptor protein 3 (NLRP3) inflammasome, which is a part of the innate immune system, plays a crucial role in the progression of various inflammatory diseases. NLRP3 activation is also important in the development of various liver diseases, including viral hepatitis, alcoholic or nonalcoholic liver disease, and autoimmune liver disease. This review discusses the role of NLRP3 and its associated molecules in the development of liver fibrosis. It also highlights the signal pathways involved in NLRP3 activation, their downstream effects on liver disease progression, and potential therapeutic targets in liver fibrosis. Further research is encouraged to develop effective treatments for liver fibrosis.

Methane-Rich Saline Suppresses ER-Mitochondria Contact and Activation of the NLRP3 Inflammasome by Regulating the PERK Signaling Pathway to Ameliorate Intestinal Ischemia‒Reperfusion Injury

Intestinal ischemia‒reperfusion (I/R) injury is a common pathological process in patients undergoing gastrointestinal surgery, leading to local intestinal damage and increased microvascular permeability, eventually causing extraintestinal multiple organ dysfunction or sepsis. The NLRP3-mediated inflammatory response is associated with I/R injury. Methane saline (MS) has anti-pyroptosis properties. This study aims to explore the protective effect of MS on intestinal I/R injury and its potential mechanisms. After MS pretreatment, the in vivo model was established by temporarily clipping the mouse superior mesentery artery with a noninvasive vascular clamp, and the in vitro model was established by OGD/R on Caco-2 cells. The results of HE and TUNEL staining showed intestinal barrier damage after I/R injury, which was consistent with the IHC staining results of tight junction proteins. Moreover, the expression of the NLRP3 signaling pathway was increased after I/R injury, and inhibition of NLRP3 activation reduced Caco-2 cell injury, indicating that NLRP3-mediated pyroptosis was one of the main forms of cell death after I/R injury. Subsequently, we found that MS treatment ameliorated intestinal barrier function after I/R injury by suppressing NLRP3-mediated pyroptosis. MS treatment also reduced mitochondria-associated membrane (MAM) formation, which was considered to be a platform for activation of the NLRP3 inflammasome. Importantly, MS reduced ER stress, which was related to the PERK signaling pathway. Knocking down PERK, a key protein involved in ER stress and MAM formation, reversed the protective effect of MS, indicating that MS suppressed NLRP3 by reducing ER stress and MAM formation. In conclusion, we believe that MS suppresses MAMs and activation of the NLRP3 inflammasome by regulating the PERK signaling pathway to ameliorate intestinal I/R injury.

The protective effect of forsythiaside A on 3,5-diethoxycarbonyl-1,4-dihydrocollidine-induced cholestatic liver injury in mice: Based on targeted metabolomics and molecular biology technology

Cholestasis is a disorder of bile secretion and excretion caused by a variety of etiologies. At present, there is a lack of functional foods or drugs that can be used for intervention. Forsythiaside A (FTA) is a natural phytochemical component isolated from the medicinal plant Forsythia suspensa (Thunb.) Vahl, which has a significant hepatoprotective effect. In this study, we investigated whether FTA could alleviate liver injury induced by cholestasis. In vitro, FTA reversed the decrease in viability of human intrahepatic bile duct epithelial cells, the decrease in antioxidant enzymes (SOD1, CAT and GSH-Px), and cell apoptosis induced by lithocholic acid. In vivo, FTA protected mice from 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-induced liver injury, abnormal serum biochemical indexes, abnormal bile duct hyperplasia, and inflammatory infiltration. Furthermore, FTA treatment alleviated liver fibrosis by inhibiting collagen deposition and HSC activation. The metabonomic results showed that DDC-induced bile acid disorders in the liver and serum were reversed after FTA treatment, which may benefit from the activation of the FXR/BSEP axis. In addition, FTA treatment increased the levels of antioxidant enzymes in the serum and liver. Meanwhile, FTA treatment inhibited ROS and MDA levels and cleaved caspase 3 protein expression, thereby reducing DDC-induced hepatic oxidative stress and apoptosis. Further studies showed that the antioxidant effects of FTA were dependent on the activation of the BRG1/NRF2/HO-1 axis. In a word, FTA has a significant hepatoprotective effect on cholestatic liver injury, and can be further developed as a functional food or drug to prevent and treat cholestatic liver injury.

Panaxynol ameliorates cardiac ischemia/reperfusion injury by suppressing NLRP3-induced pyroptosis and apoptosis via HMGB1/TLR4/NF-κB axis

BACKGROUND AND PURPOSE

Panaxynol (PNN) is a common natural minor component in Umbelliferae plants. Many clinical studies have shown that PNN exhibits nutritional value and anti-inflammatory and other pharmacological activities. However, whether PNN can mediate cardiac ischemia/reperfusion injury (IRI) remains unclear. Here, we aimed to determine the potential effects of PNN on myocardial IRI.

METHODS

Myocardial IRI was stimulated in a mouse IRI model, and neonatal rat ventricle myocytes (NRVMs) were exposed to hypoxia/reoxygenation to construct in an vitro model. Myocardial infarction size, myocardial tissue injury, myocardial apoptotic index, hemodynamic monitoring, pyroptosis-related proteins, cardiac enzyme activities and inflammatory responses were examined to assess myocardial injury.

RESULTS

It was found that PNN administration markedly reduced myocardial infarct size and apoptosis, suppressed myocardial damage and cell pyroptosis, attenuated pro-inflammatory cytokines and neutrophil infiltration via NLRP3 inhibitor. More importantly, PNN treatment remarkably decreased the expression of TLR4/NF-κB pathway-associated proteins and NLRP3-related pyroptosis proteins by HMGB1 inhibitor. PNN also enhanced cell viability, reduced cardiac enzyme activities, suppressed apoptosis and attenuated inflammation in the isolated NRVMs. Furthermore, vitro studies indicated that MCC950 (a NLRP3 inhibitor) increased the anti-inflammatory and anti-apoptotic effects of PNN on NRVMs via HMGB1/TLR4 pathway.

CONCLUSION

To sum up, our results demonstrate that PNN exhibits a cardioprotective effect by modulating heart IRI-induced apoptosis and pyroptosis via HMGB1/TLR4/NF-κB pathway, thereby inhibiting NLRP3 inflammasome stimulation.

Diacerein ameliorates cholestasis-induced liver fibrosis in rat via modulating HMGB1/RAGE/NF-κB/JNK pathway and endoplasmic reticulum stress

Diacerein is an interleukin (IL)-1β inhibitor approved for osteoarthritis. This study aimed to investigate the potential anti-fibrotic effect of diacerein against bile duct ligation (BDL)-induced liver fibrosis. Forty male Wistar rats were divided into: sham-operated group, BDL group, and BDL groups treated with diacerein at 10, 30, and 50 mg/kg/day starting two days before surgery and continued for 4 weeks. Diacerein decreased the hepatic injury markers and alleviated oxidative stress triggered by BDL by reducing hepatic malondialdehyde (MDA) and increasing hepatic superoxide dismutase (SOD) levels. Diacerein mitigated BDL-induced inflammation via lowering hepatic levels and mRNA expression of high mobility group box 1 (HMGB1), nuclear factor-κB (NF-κB), and IL-1β. The hepatic gene expression of Advanced Glycation End products Receptor (RAGE) gene and immunohistochemical expression of some ER stress markers, e.g., glucose-regulated protein 78 (GRP78), inositol-requiring enzyme 1 (IRE1α), protein kinase RNA-like endoplasmic reticulum kinase (PERK), CCAAT/enhancer-binding protein homologous protein (CHOP), and phosphorylated c-Jun N-terminal kinase protein contents were lowered by diacerein. Furthermore, diacerein suppressed the hepatic levels of fibrogenic mediators, e.g., Transforming growth factor β1 (TGF-β1), α- smooth muscle actin (α-SMA), collagen 1, and hydroxyproline, as well as the apoptotic caspase 3 and BAX immunostaining in BDL rats. The histopathological abnormalities induced by BDL significantly improved. Our study demonstrated that diacerein exhibited an antifibrotic effect by inhibiting HMGB1/RAGE/NF-κB/JNK pathway, and ER stress. Better protection was observed with increasing the dose.

TRIM64 promotes ox-LDL-induced foam cell formation, pyroptosis, and inflammation in THP-1-derived macrophages by activating a feedback loop with NF-κB via IκBα ubiquitination

Atherosclerosis is a chronic inflammatory disease and the main pathology behind most cardiovascular diseases and the overactivation of macrophages initiates the development of atherosclerosis. However, the specific functions of oxidized low-density lipoprotein (ox-LDL) in macrophages remain elusive. Macrophages derived from monocyte (THP-1) were treated with ox-LDL and were used to generate atherosclerosis in an in vitro model. NLRP3 inflammasome markers were examined using quantitative RT-PCR and Western blotting. Cytokines were measured using ELISA. Chromatin immunoprecipitation (ChIP) was utilized to detect nuclear factor kappa B (NF-κB) and TRIM64 interactions. A fat-rich diet was applied to ApoE-/- mice for in vivo studies. ox-LDL promoted TRIM64 expression in a time-dependent manner. According to loss- and gain-of-function analyses, TRIM64 enhanced the activation of NLRP3 inflammasomes and the expression of downstream molecules. TRIM64 directly interacted with IκBα and promoted IκBα ubiquitination at K67 to activate NF-κB signaling. We detected direct binding between NF-κB and the TRIM64 promoter, as well as enhanced TRIM64 expression. Our study revealed an interaction between TRIM64 and NF-κB in the development of atherosclerosis. TRIM64 and NF-κB formed a positive feedback to activate NF-κB pathway. ox-LDL induces foam cell formation and TRIM64 expression TRIM64 regulates ox-LDL-induced foam cell formation, pyroptosis and inflammation via the NF-κB signaling TRIM64 activates NF-κB signaling by ubiquitination of IκBα NF-κB inhibition attenuates atherosclerosis in HFD-induced ApoE (-/-) mice.

γ-Mangostin abrogates AINT-induced cholestatic liver injury: Impact on Nrf2/NF-κB/NLRP3/Caspase-1/IL-1β/GSDMD signalling

γ-Mangostin (γ-MN) is one of the abundant xanthones separated from Garcinia mangostana (Clusiaceae) pericarps that has been reported to have varied bioactivities such as neuroprotective, cytotoxic, antihyperglycemic, antioxidant, and anti-inflammation. Yet, its effect on cholestatic liver damage (CLI) has not been investigated. This study explored the protective activity of γ-MN against alpha-naphthyl isothiocyanate (ANIT)-induced CLI in mice. The results showed that γ-MN protected against ANIT-induced CLI as indicated by reduced serum levels of hepatic injury parameters (e.g., ALT, AST, γ-GT, ALP, LDH, bilirubin, and total bile acids). ANIT-induced pathological lesions were improved in γ-MN pre-treated groups. γ-MN exerted potent antioxidant effects as it lowered the parameters of lipid peroxidation (4-HNE, PC, and MDA) and intensified the content and activity of antioxidants (TAC, GSH, GSH-Px, GST, and SOD) in the hepatic tissue. Furthermore, γ-MN enhanced the signalling of Nrf2/HO-1 as it augmented the mRNA expression of Nrf2/downstream genes (HO-1/GCLc/NQO1/SOD). The binding capacity and the immuno-expression of Nrf2 were also increased. γ-MN showed anti-inflammatory capacity as it suppressed the activation of NF-κB signalling, it decreased mRNA expression and levels of NF-κB/TNF-α/IL-6 and the immuno-expression of NF-κB/TNF-α. In addition, γ-MN inhibited the activation of NLRP3 inflammasome as it lowered the mRNA expression of NLRP3/caspase-1/IL-1β along with their levels as well as the immuno-expression of caspase-1/IL-1β. γ-MN also reduced the level of the pyroptotic parameter GSDMD. Collectively, this study demonstrated the potent hepatoprotective potential of γ-MN against CLI which was linked to its ability to potentiate Nrf2/HO-1 and to offset NF-κB/NLRP3/Caspase-1/IL-1β/GSDMD. Hence, γ-MN may be suggested as a new candidate for cholestatic patients.

Pentoxifylline and thiamine ameliorate rhabdomyolysis-induced acute kidney injury in rats via suppressing TLR4/NF-κB and NLRP-3/caspase-1/gasdermin mediated-pyroptosis

Acute kidney injury (AKI) is a common complication of rhabdomyolysis (RM), a syndrome characterized by skeletal muscle damage resulting in renal tubular oxidative stress, inflammation, and activated toll like receptor-4 (TLR-4) and NOD-like receptor protein-3 (NLRP-3) inflammasome. Pyroptosis is a programmed cell death mediated by NLRP-3 leading to the activation of caspase-1 and gasdermin D (GSDMD), the hallmark of pyroptosis. This study aims to investigate the renoprotective effects of two antioxidants; pentoxifylline (PTX) and thiamine (TM) via targeting the aforementioned pathways. RM-AKI was induced in male Albino Wistar rats by intramuscular injection of glycerol (50% v/v, 10 ml/kg). PTX (100 mg/kg, oral) and TM (25 mg/kg, i.p) were administered for 12 days prior glycerol injection and continued for 3 days following induction of RM-AKI. Serum creatinine, blood urea nitrogen (BUN), creatin kinase, lipid peroxides, total antioxidant activity, inflammatory markers (tumor necrosis factor-α, interleukin-1β, and nuclear factor kappa B), TLR4, NLRP-3, caspase-1, GSDMD and c-myc (an apoptotic marker) were estimated. Compared to AKI model, co-administered drugs revealed a significant improvement in renal function and pathology as indicated by the reduction in serum creatinine, BUN and protein cast accumulation. The elevations of oxidative stress, and inflammatory markers as well as the over-expression of c-myc were alleviated. Protein levels of TLR4, NLRP3, cleaved caspase-1, and GSDMD were significantly elevated in RM-AKI model, and this elevation was attenuated by the tested drugs. In conclusion, PTX and TM could be a potential renoprotective approach for patients with RM through targeting TLR4/NF-κB and NLRP-3/caspase-1/gasdermin mediated-pyroptosis pathways.

DBP and BaP co-exposure induces kidney injury via promoting pyroptosis of renal tubular epithelial cells in rats

Dibutyl phthalate (DBP) and benzo(a)pyrene (BaP) are widespread environmental and foodborne contaminants that have detrimental effects on human health. Although people are often simultaneously exposed to DBP and BaP via the intake of polluted food and water, the combined effects on the kidney and potential mechanisms remain unclear. Hence, we treated rats with DBP and BaP for 90 days to investigate their effects on kidney histopathology and function. We also investigated the levels of paramount proteins and genes involved in pyroptosis and TLR4/NF-κB p65 signaling in the kidney. Our research showed that combined exposure to DBP and BaP triggered more severe histopathological and renal function abnormalities than in those exposed to DBP or BaP alone. Simultaneously, combined exposure to DBP and BaP enhanced the excretion of IL-1β and IL-18, along with the release of LDH in rat renal tubular epithelial cells (RTECs). Moreover, combined exposure to DBP and BaP increased the expression of pyroptosis marker molecules, including NLRP3, ASC, cleaved-Caspase-1, and GSDMD. Meanwhile, the combination of DBP and BaP activated TLR4/NF-κB signaling in the kidney. Taken together, the combined exposure to DBP and BaP causes more severe kidney injury than that caused by DBP or BaP exposure separately. In addition, pyroptosis of RTECs regulated by TLR4/NF-κB signaling may add to the kidney damage triggered by combined exposure to DBP and BaP.

Regulation of SIRT1-TLR2/TLR4 pathway in cell communication from macrophages to hepatic stellate cells contribute to alleviates hepatic fibrosis by Luteoloside

Regulating macrophage-hepatic stellate cells (HSCs) crosstalk through SIRT1-TLR2/TLR4 has contributed to the essence of new pharmacologic strategies to improve hepatic fibrosis. We investigated how Luteoloside (LUT), one of the flavonoid monomers isolated from Eclipta prostrata (L.) L., modulates macrophage-HSCs crosstalk during hepatic fibrosis. HSC-T6 or rat peritoneal macrophages were activated by TGF-β or LPS/ATP, and then treated with LUT or Sirtinol (SIRT1 inhibitor) for 6 h. Further, HSCs were cultured with the conditioned medium from the LPS/ATP activated peritoneal macrophages. In HSC-T6 or peritoneal macrophages, LUT could decrease the expressions of α-SMA, Collagen-I, the ratio of TIMP-1/MMP-13. LUT also significantly increased the expressions of SIRT1 and ERRα. And LUT significantly suppressed the releases of pro-inflammatory cytokines, including NLRP3, ASC, caspase-1, IL-1β, and regulated signaling TLR2/TLR4-MyD88 activation. The expressions of TLR2, TLR4, NLRP3, caspase-1, IL-1β, α-SMA were increased and the expression of ERRα was decreased by Sirtinol, indicated that LUT might mediate SIRT1 to regulate TLR4 expression and further alleviate inflammation and fibrosis. LUT could regulate SIRT1-mediated TLR4 and ECM in HSCs was reduced, when HSCs were cultured with conditioned medium. Hence, LUT could decrease the expressions of fibrosis markers, reduce the releases of inflammatory cytokines in activated HSCs or macrophages. In conclusion, LUT might be a promising candidate that regulating SIRT1-TLR2/TLR4 signaling in macrophages interacting with HSCs during hepatic fibrosis.

Fenofibrate Downregulates NF-κB Signaling to Inhibit Pro-inflammatory Cytokine Secretion in Human THP-1 Macrophages and During Primary Biliary Cholangitis

Chronic liver diseases, e.g., cholestasis, are negatively impacted by inflammation, which further aggravates liver injury. Pharmacotherapy targeting the peroxisome proliferator-activated receptor alpha (PPARα), e.g., fenofibrate, has recently become an off-label therapeutic option for patients with refractory cholestasis. Clinical studies show that fibrates can reduce some pro-inflammatory cytokines in primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC); however, its anti-inflammatory mechanisms have not been established. Numerous cytokines are regulated by the transcription factor nuclear receptor kappa B (NF-κB), and PPARα has been shown to interfere with NF-κB signaling. This study investigates the anti-inflammatory mechanism of fenofibrate by inhibiting NF-κB signaling in human macrophages and clinical outcomes in patients with PBC. For adult patients with PBC and an incomplete biochemical response to ursodiol (13-15 mg/kg/day), the addition of fenofibrate (145-160 mg/day) reduced serum levels of TNF-α, IL-17A, IL-1β, IL-6, IL-8, and MCP-1 and increased IL-10. In THP-1 cells, pretreatment with fenofibrate (125 μM) reduced LPS-stimulated peak concentrations of IL-1β (- 63%), TNF-α (- 88%), and IL-8 (- 54%), in a PPARα-dependent manner. Treatment with fenofibrate prior to LPS significantly decreased nuclear NF-κB p50 and p65 subunit binding by 49% and 31%, respectively. Additionally, fenofibrate decreased nuclear NF-κB p50 and p65 protein expression by 66% and 55% and increased cytoplasmic levels by 53% and 54% versus LPS alone, respectively. Lastly, fenofibrate increased IκBα levels by 2.7-fold (p < 0.001) vs. LPS. These data demonstrate that fenofibrate reduces pro-inflammatory cytokines section by inhibiting in NF-κB signaling, which likely contribute to its anti-inflammatory effects during chronic liver diseases.

NLRP3 inflammasome in digestive diseases: From mechanism to therapy

Digestive system diseases remain a formidable challenge to human health. NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is the most characteristic multimeric protein complex and is involved in a wide range of digestive diseases as intracellular innate immune sensors. It has emerged as a research hotspot in recent years. In this context, we provide a comprehensive review of NLRP3 inflammasome priming and activation in the pathogenesis of digestive diseases, including clinical and preclinical studies. Moreover, the scientific evidence of small-molecule chemical drugs, biologics, and phytochemicals, which acts on different steps of the NLRP3 inflammasome, is reviewed. Above all, deep interrogation of the NLRP3 inflammasome is a better insight of the pathomechanism of digestive diseases. We believe that the NLRP3 inflammasome will hold promise as a novel valuable target and research direction for treating digestive disorders.

Integrated bioinformatics analysis reveals potential mechanisms associated with intestinal flora intervention in nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease that imposes a huge economic burden on global public health. And the gut-liver axis theory supports the therapeutic role of intestinal flora in the development and progression of NAFLD. To this end, we designed bioinformatics study on the relationship between intestinal flora disorder and NAFLD, to explore the possible molecular mechanism of intestinal flora interfering with NAFLD.

METHODS

Differentially expressed genes for NAFLD were obtained from the GEO database. And the disease genes for NAFLD and intestinal flora disorder were obtained from the disease databases. The protein-protein interaction network was established by string 11.0 database and visualized by Cytoscape 3.7.2 software. Cytoscape plug-in MCODE and cytoHubba were used to screen the potential genes of intestinal flora disorder and NAFLD, to obtain potential targets for intestinal flora to interfere in the occurrence and process of NAFLD. Enrichment analysis of potential targets was carried out using R 4.0.2 software.

RESULTS

The results showed that 7 targets might be the key genes for intestinal flora to interfere with NAFLD. CCL2, IL6, IL1B, and FOS are mainly related to the occurrence and development mechanism of NAFLD, while PTGS2, SPINK1, and C5AR1 are mainly related to the intervention of intestinal flora in the occurrence and development of NAFLD. The gene function is mainly reflected in basic biological processes, including the regulation of metabolic process, epithelial development, and immune influence. The pathway is mainly related to signal transduction, immune regulation, and physiological metabolism. The TNF signaling pathway, AGE-RAGE signaling pathway in diabetic activity, and NF-Kappa B signaling pathways are important pathways for intestinal flora to interfere with NAFLD. According to the analysis results, there is a certain correlation between intestinal flora disorder and NAFLD.

CONCLUSION

It is speculated that the mechanism by which intestinal flora may interfere with the occurrence and development of NAFLD is mainly related to inflammatory response and insulin resistance. Nevertheless, further research is needed to explore the specific molecular mechanisms.

Traditional Chinese medicine: An important source for discovering candidate agents against hepatic fibrosis

Hepatic fibrosis (HF) refers to the pathophysiological process of connective tissue dysplasia in the liver caused by various pathogenic factors. Nowadays, HF is becoming a severe threat to the health of human being. However, the drugs available for treating HF are limited. Currently, increasing natural agents derived from traditional Chinese medicines (TCMs) have been found to be beneficial for HF. A systemic literature search was conducted from PubMed, GeenMedical, Sci-Hub, CNKI, Google Scholar and Baidu Scholar, with the keywords of "traditional Chinese medicine," "herbal medicine," "natural agents," "liver diseases," and "hepatic fibrosis." So far, more than 76 natural monomers have been isolated and identified from the TCMs with inhibitory effect on HF, including alkaloids, flavones, quinones, terpenoids, saponins, phenylpropanoids, and polysaccharides, etc. The anti-hepatic fibrosis effects of these compounds include hepatoprotection, inhibition of hepatic stellate cells (HSC) activation, regulation of extracellular matrix (ECM) synthesis & secretion, regulation of autophagy, and antioxidant & anti-inflammation, etc. Natural compounds and extracts from TCMs are promising agents for the prevention and treatment of HF, and this review would be of great significance to development of novel drugs for treating HF.

Schisandrol B protects against cholestatic liver injury by inhibiting pyroptosis through pregnane X receptor

Previously, we demonstrated that Schisandrol B (SolB) protected against lithocholic acid (LCA)-induced cholestatic liver injury (CLI) through pregnane X receptor (PXR). Additionally, growing evidence has revealed that pyroptosis is involved in CLI. Whether the hepatoprotective effect of SolB driven by PXR activation is related to pyroptosis in CLI remains unclear. First, the hepatoprotective effect of SolB was confirmed, as evidenced by the decreased mortality, morphological and histopathological changes, and biochemical parameters. The upregulated serum lactic dehydrogenase (LDH) level, increased number of TUNEL-positive cells, and formation of hepatocyte membrane pores induced by LCA were significantly alleviated after SolB pretreatment, indicating that SolB attenuated LCA-induced hepatocyte damage. Further analysis revealed that both NOD-like receptor protein 3 (NLRP3) inflammasome-induced canonical pyroptosis and apoptosis protease activating factor-1 (Apaf-1) pyroptosome-induced noncanonical pyroptosis were significantly inhibited after SolB pretreatment, as illustrated by the decreased expression levels of NLRP3, ASC, caspase-1, and GSDMD and the levels of Apaf-1, caspase-11 p20, caspase-3 p20, and GSDME. Furthermore, the activation of the NF-κB and FoxO1 signaling pathways was inhibited after SolB pretreatment. In addition, the activation of PXR via SolB was proven by luciferase reporter gene assays and the upregulation of PXR targets. The results illustrated that SolB could significantly inhibit NLRP3 inflammasome-induced canonical pyroptosis through the PXR/NF-κB/NLRP3 axis and inhibit Apaf-1 pyroptosome-induced noncanonical pyroptosis through the PXR/FoxO1/Apaf-1 axis. Collectively, this study revealed that SolB protected against CLI by inhibiting pyroptosis through PXR, providing new insights for understanding the molecular mechanism of SolB as a promising anti-cholestatic agent.

Metformin Alleviates LPS-Induced Acute Lung Injury by Regulating the SIRT1/NF-κB/NLRP3 Pathway and Inhibiting Endothelial Cell Pyroptosis

Acute respiratory distress syndrome (ARDS), a devastating complication of numerous conditions, is often associated with high mortality. It is well known that endothelial cell (EC) damage and inflammation are vital processes in the pathogenesis of ARDS. Nevertheless, the mechanisms of EC damage are largely unknown. In the present study, we investigated the role of pyroptosis in the initiation of ARDS and demonstrated that endothelial pyroptosis might play a pivotal role in the pathophysiology of ARDS. Metformin, an antidiabetic drug, exhibited a protective effect in lipopolysaccharide (LPS)-induced lung injury, and we hypothesized that metformin alleviated LPS-induced lung injury via inhibiting ECs pyroptosis. In vivo, male ICR mice were intratracheally injected with LPS, and metformin was previously administered intraperitoneally. Morphological properties of lung tissues were detected. We showed that metformin inhibited NLRP3 inflammasome activation and NLRP3-stimulated pyroptosis induction, as shown by decreased levels of cleaved caspase-1, N-terminal fragment of GSDMD, and protein contents of IL-1β in lung tissues of mice exposed to LPS. LPS-induced expression of vascular adhesion molecules was also reduced after the treatment with metformin. In vitro, exposure of pulmonary ECs to LPS resulted in increased expression of NLRP3 and pyroptosis-associated indicators. By inhibiting the expression of NLRP3 with NLRP3 inhibitor MCC950, pyroptosis-related markers and vascular adhesion molecules were ameliorated. Moreover, metformin treatment significantly inhibited the NF-κB signaling pathway and increased the expression of sirtuin 1 (SIRT1) both in LPS-stimulated lung tissues and pulmonary ECs. Administration of the selective SIRT1 inhibitor nicotinamide significantly reversed the protective effect of metformin against endothelial pyroptosis and lung injury in LPS-treated ECs and LPS-induced acute lung injury (ALI). Thus, these findings demonstrated that metformin alleviated LPS-induced ALI by inhibiting NF-κB-NLRP3–mediated ECs pyroptosis, possibly by upregulating the expression of SIRT1.

Ginsenoside Rb1 Reduces D-GalN/LPS-induced Acute Liver Injury by Regulating TLR4/NF-κB Signaling and NLRP3 Inflammasome

BACKGROUND AND AIMS

The effect of ginsenoside Rb1 on D-galactosamine (D-GalN)/lipopolysaccharide (LPS)-induced acute liver injury (ALI) is unknown. The aim of this study was to evaluate the effect of ginsenoside Rb1 on ALI and its underlying mechanisms.

METHODS

Mice were pretreated with ginsenoside Rb1 by intraperitoneal injection for 3 days before D-GalN/LPS treatment, to induce ALI. The survival rate was monitored every hour for 24 h, and serum biochemical parameters, hepatic index and histopathological analysis were evaluated to measure the degree of liver injury. ELISA was used to detect oxidative stress and inflammatory cytokines in hepatic tissue and serum. Immunohistochemistry staining, RT-PCR and western blotting were performed to evaluate the expression of toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB), and NLR family, pyrin domain-containing 3 protein (NLRP3) in liver tissue and Kupffer cells (KCs).

RESULTS

Ginsenoside Rb1 improved survival with D-GalN/LPS-induced ALI by up to 80%, significantly ameliorated the increased alanine and aspartate transaminase, restored the hepatic pathological changes and reduced the levels of oxidative stress and inflammatory cytokines altered by D-GalN/LPS. Compared to the control group, the KCs were increased in the D-GalN/LPS groups but did not increase significantly with Rb1 pretreatment. D-GalN/LPS could upregulate while Rb1 pretreatment could downregulate the expression of interleukin (IL)-1β, IL-18, NLRP3, apoptosis associated speck-like protein containing CARD (ASC) and caspase-1 in isolated KCs. Furthermore, ginsenoside Rb1 inhibited activation of the TLR4/NF-κB signaling pathway and NLRP3 inflammasome induced by D-GalN/LPS administration.

CONCLUSIONS

Ginsenoside Rb1 protects mice against D-GalN/LPS-induced ALI by attenuating oxidative stress and the inflammatory response through the TLR4/NF-κB signaling pathway and NLRP3 inflammasome activation.

Gut microbiota mediates methamphetamine-induced hepatic inflammation via the impairment of bile acid homeostasis

Methamphetamine (Meth), an addictive psychostimulant of abuse worldwide, has been a common cause of acute toxic hepatitis in adults. Gut microbiota has emerged as a modulator of host immunity via metabolic pathways. However, the microbial mechanism of Meth-induced hepatic inflammation and effective therapeutic strategies remain unknown. Here, mice were intraperitoneally (i.p.) injected with Meth to induce hepatotoxicity. Cecal microbiome and bile acids (BAs) composition were analyzed after Meth administration. Fecal microbiota transplantation (FMT) technology was utilized to investigate the role of microbiota. Additionally, the protective effects of obeticholic acid (OCA), an agonist of farnesoid X receptor (FXR), were evaluated. Results indicated that Meth administration induced hepatic cholestasis, dysfunction and aroused hepatic inflammation by stimulating the TLR4/MyD88/NF-κB pathway in mice. Meanwhile, Meth disturbed the cecal microbiome and impaired the homeostasis of BAs. Interestingly, FMT from Meth administered mice resulted in serum and hepatic BA accumulation and transferred similar phenotypic changes into the healthy recipient mice. Finally, OCA normalized Meth-induced BA accumulation in both serum and the liver, and effectively protected against Meth-induced hepatic dysfunction and inflammation by suppressing the TLR4/MyD88/NF-κB pathway. This study established the importance of microbial mechanism and its inhibition as a potential therapeutic target to treat Meth-related hepatotoxicity.

Construction of PIK3C3 Transgenic Pig and Its Pathogenesis of Liver Damage

As a member of the PIKs family, PIK3C3 participates in autophagy and plays a central role in liver function. Several studies demonstrated that the complete suppression of PIK3C3 in mammals can cause hepatomegaly and hepatosteatosis. However, the function of PIK3C3 overexpression on the liver and other organs is still unknown. In this study, we successfully generated PIK3C3 transgenic pigs through somatic cell nuclear transfer (SCNT) by designing a specific vector for the overexpression of PIK3C3. Plasmid identification was performed through enzyme digestion and transfected into the fetal fibroblasts derived from Diannan miniature pigs. After 2 weeks of culturing, six positive colonies obtained from a total of 14 cell colonies were identified through PCR. One positive cell line was selected as the donor cell line for SCNT for the construction of PIK3C3transgenic pigs. Thirty single blastocysts were collected and identified as PIK3C3 transgenic-positive blastocysts. Two surrogates became pregnant after transferring the reconstructed embryos into four surrogates. Fetal fibroblasts of PIK3C3-positive fetuses identified through PCR were used as donor cells for SCNT to generate PIK3C3 transgenic pigs. To further explore the function of PIK3C3 overexpression, genotyping and phenotyping of the fetuses and piglets obtained were performed by PCR, immunohistochemical, HE, and apoptosis staining. The results showed that inflammatory infiltration and vacuolar formation in hepatocytes and apoptotic cells, and the mRNA expression of NF-κB, TGF-β1, TLR4, TNF-α, and IL-6 significantly increased in the livers of PIK3C3 transgenic pigs when compared with wild-type (WT) pigs. Immunofluorescence staining showed that LC3B and LAMP-1-positive cells increased in the livers of PIK3C3 transgenic pigs. In the EBSS-induced autophagy of the porcine fibroblast cells (PFCs), the accumulated LC3II protein was cleared faster in PIK3C3 transgenic (PFCs) thanWT (PFCs). In conclusion, PIK3C3 overexpression promoted autophagy in the liver and associated molecular mechanisms related to the activation of ULK1, AMBR1, DRAM1, and MTOR, causing liver damage in pigs. Therefore, the construction of PIK3C3 transgenic pigs may provide a new experimental animal resource for liver diseases.

Cultured bear bile powder ameliorates acute liver injury in cholestatic mice via inhibition of hepatic inflammation and apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Natural bear bile powder (NBBP) is a traditional Chinese medicine used for treating liver dysfunction. Cultured bear bile powder (CBBP), which is produced using biotransformation of chicken bile, acts as an appropriate substitute for NBBP when treating cholestatic liver injury.

AIM OF THE STUDY

To investigate the molecular mechanisms underlying the hepatoprotective effects of CBBP in an α-naphthylisothiocyanate (ANIT)-induced cholestatic mouse model.

MATERIALS AND METHODS

Cholestatic mice were pretreated with CBBP or NBBP via oral gavage once a day for two weeks. Their blood biochemistry and liver histopathology were then evaluated using standard protocols. Western blot analyses, real-time polymerase chain reaction, and immunohistochemistry were used to evaluate changes in the protein levels and gene expression profiles of factors associated with hepatic inflammation and apoptosis in cholestatic mice.

RESULTS

CBBP significantly decreased the serum indices of liver injury, and ameliorated neutrophil infiltration and hepatocyte necrosis within liver tissue of cholestatic mice. Expression of the inflammatory factors, such as tumor necrosis factor-α, interleukin-1β (IL-1β), IL-6, monocyte chemoattractant protein-1, and intercellular adhesion molecule 1, was significantly reduced in CBBP-treated cholestatic mice. Moreover, proteins involved in the toll-like receptor 4/myeloid differentiation factor 88/nuclear factor-kappa B (TLR4/Myd88/NF-κB) signaling pathway, such as CD14, TLR4, Myd88, and NF-κB, that were increased in cholestatic mice, were downregulated by CBBP. Meanwhile, increased expression of the apoptosis-related proteins, caspase-3 and Bax, in cholestatic mice was reversed by CBBP treatment.

CONCLUSION

CBBP treatment alleviates ANIT-induced cholestasis and liver injury by reducing hepatocyte inflammation and apoptosis.

PF-PLC micelles ameliorate cholestatic liver injury via regulating TLR4/MyD88/NF-κB and PXR/CAR/UGT1A1 signaling pathways in EE-induced rats

Paeoniflorin (PF) has a certain therapeutic effect on cholestasis liver injury. To further improve the bioavailability of PF and play its pharmacological role in liver protection, PF-phospholipid complex micelles (PF-PLC micelles) were prepared based on our previous research on PF-PLC. The protective effects of PF and PF-PLC micelles on cholestasis liver injury induced by 17α-ethynylestradiol (EE) were compared, and the possible mechanisms were further explored. Herein, we showed that PF-PLC micelles effectively improved liver function, alleviated liver pathological damage, and localized infiltration of inflammatory cells. Mechanism studies indicated that PF-PLC micelles treatment could suppress the TLR4/MyD88/NF-κB pathway, and further reduce the levels of pro-inflammatory factors. Meanwhile, our experimental results demonstrated that the beneficial effect of PF-PLC micelles on EE-induced cholestasis may be achieved by the upregulation of nuclear receptors and metabolic enzymes (PXR/CAR/UGT1A1). All these results indicate that PF-PLC micelles have great potential in the treatment of cholestatic liver disease.

Resveratrol suppresses cholestasis-induced liver injury and fibrosis in rats associated with the inhibition of TGFβ1-Smad3-miR21 axis and profibrogenic and hepatic injury biomarkers

Cholestasis caused by slowing or blockage of bile flow is a serious liver disease that can lead to liver fibrosis and cirrhosis. The link between transforming growth factor beta 1 (TGFβ1), Smad family member 3 (Smad3), and microRNA 21 (miR21) in bile duct ligation (BDL)-induced liver fibrosis in the presence and absence of the anti-inflammatory and antioxidant compound, resveratrol (RSV), has not been previously studied. Therefore, we tested whether RSV can protect against BDL-induced liver fibrosis associated with the inhibition of the TGFβ1-Smad3-miR21 axis and profibrogenic and hepatic injury biomarkers. The model group of rats had their bile duct ligated (BDL) for 3 weeks before being killed, whereas, the BDL-treated rats were separated into three groups that received 10, 20, and 30 mg/kg RSV daily until the end of the experiment. Using light microscopy and ultrasound examinations, we documented in the BDL group, the development of hepatic injury and fibrosis as demonstrated by hepatocytes necrosis, bile duct hyperplasia, collagen deposition, enlarged liver with increased echogenicity, irregular nodular border and dilated common bile duct, which were more effectively inhibited by the highest used RSV dosage. In addition, RSV significantly (p ≤ 0.0027) inhibited BDL-induced hepatic TGFβ1, Smad3, miR21, the profibrogenic biomarker tissue inhibitor of metalloproteinases-1 (TIMP-1), malondialdehyde (MDA), interleukin-17a (IL-17a), and blood levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and bilirubin. These findings show that RSV at 30 mg/kg substantially protects against BDL-induced liver injuries, which is associated with the inhibition of TGFβ1-Smad3-miR21 axis, and biomarkers of profibrogenesis, oxidative stress, and inflammation.

Tectorigenin alleviates intrahepatic cholestasis by inhibiting hepatic inflammation and bile accumulation via activation of PPARγ

BACKGROUND AND PURPOSE

Increasing evidence suggests that human cholestasis is closely associated with the accumulation and activation of hepatic macrophages. Research indicates that activation of PPARγ exerts liver protective effects in cholestatic liver disease (CLD), particularly by ameliorating inflammation and fibrosis, thus limiting disease progression. However, existing PPARγ agonists, such as troglitazone and rosiglitazone, have significant side effects that prevent their clinical application in the treatment of CLD. In this study, we found that tectorigenin alleviates intrahepatic cholestasis in mice by activating PPARγ.

EXPERIMENTAL APPROACH

Wild-type mice were intragastrically administered α-naphthylisothiocyanate (ANIT) or fed a diet containing 0.1% 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) to simultaneously establish an experimental model of intrahepatic cholestasis and tectorigenin intervention, followed by determination of intrahepatic cholestasis and the mechanisms involved. In addition, PPARγ-deficient mice were administered ANIT and/or tectorigenin to determine whether tectorigenin exerts its liver protective effect by activating PPARγ.

KEY RESULTS

Treatment with tectorigenin alleviated intrahepatic cholestasis by inhibiting the recruitment and activation of hepatic macrophages and by promoting the expression of bile transporters via activation of PPARγ. Furthermore, tectorigenin increased expression of the bile salt export pump (BSEP) through enhanced PPARγ binding to the BSEP promoter. In PPARγ-deficient mice, the hepatoprotective effect of tectorigenin during cholestasis was blocked.

CONCLUSION AND IMPLICATIONS

In conclusion, tectorigenin reduced the recruitment and activation of hepatic macrophages and enhanced the export of bile acids by activating PPARγ. Taken together, our results suggest that tectorigenin is a candidate compound for cholestasis treatment.

Ibudilast Attenuates Folic Acid-Induced Acute Kidney Injury by Blocking Pyroptosis Through TLR4-Mediated NF-κB and MAPK Signaling Pathways

Folic acid (FA)-induced renal tubule damage, which is characterized by extensive inflammation, is a common model of acute kidney injury (AKI). Pyroptosis, a pro-inflammatory form of cell death due to the activation of inflammatory caspases, is involved in AKI progression. Ibudilast, a TLR4 antagonist, has been used in the clinic to exert an anti-inflammatory effect on asthma. However, researchers have not explored whether ibudilast exerts a protective effect on AKI by inhibiting inflammation. In the present study, ibudilast reversed FA-induced AKI in mice, as indicated by the reduced serum creatinine and urea nitrogen levels, and improved renal pathology, as well as the downregulation of kidney injury marker-1. In addition, ibudilast significantly increased the production of the anti-inflammatory factor IL-10 while suppressing the secretion of the pro-inflammatory cytokine TNF-α and macrophage infiltration. Moreover, in the injured kidney, ibudilast reduced the levels of both inflammasome markers (NLRP3) and pyroptosis-related proteins (caspase-1, IL1-β, IL-18, and GSDMD cleavage), and decreased the number of TUNEL-positive cells. Further mechanistic studies showed that ibudilast administration inhibited the FA-induced upregulation of TLR4, blocked NF-κB nuclear translocation, and reduced the phosphorylation of NF-κB and IκBα, p38, ERK, and JNK. Thus, this study substantiates the protective effect of ibudilast on FA-induced AKI in mice and suggests that protection might be achieved by reducing pyroptosis and inflammation, likely through the inhibition of TLR4-mediated NF-κB and MAPK signaling pathways.

Deficiency of TGR5 exacerbates immune-mediated cholestatic hepatic injury by stabilizing the β-catenin destruction complex

Intrahepatic cholestasis induced by drug toxicity may cause cholestatic hepatic injury (CHI) leading to liver fibrosis and cirrhosis. The G protein-coupled bile acid receptor 1 (TGR5) is a membrane receptor with well-known roles in the regulation of glucose metabolism and energy homeostasis. However, the role and mechanism of TGR5 in the context of inflammation during CHI remains unclear. Wild-type (WT) and TGR5 knockout (TGR5^−/−) mice with CHI induced by bile duct ligation (BDL) were involved in vivo, and WT and TGR5^−/− bone marrow-derived macrophages (BMDMs) were used in vitro. TGR5 deficiency significantly exacerbated BDL-induced liver injury, inflammatory responses and hepatic fibrosis compared with WT mice in vivo. TGR5^−/− macrophages were more susceptible to lipopolysaccharide (LPS) stimulation than WT macrophages. TGR5 activation by its ligand suppressed LPS-induced pro-inflammatory responses in WT but not TGR5^−/− BMDMs. Notably, expression of β-catenin was effectively inhibited by TGR5 deficiency. Furthermore, TGR5 directly interacted with Gsk3β to repress the interaction between Gsk3β and β-catenin, thus disrupting the β-catenin destruction complex. The pro-inflammatory nature of TGR5-knockout was almost abolished by lentivirus-mediated β-catenin overexpression in BMDMs. BMDM migration in vitro was accelerated under TGR5-deficient conditions or supernatant from LPS-stimulated TGR5^−/− BMDMs. From a therapeutic perspective, TGR5^−/− BMDM administration aggravated BDL-induced CHI, which was effectively rescued by β-catenin overexpression. Our findings reveal that TGR5 plays a crucial role as a novel regulator of immune-mediated CHI by destabilizing the β-catenin destruction complex, with therapeutic implications for the management of human CHI.

Hydrogen: An Endogenous Regulator of Liver Homeostasis

Basic and clinical studies have shown that hydrogen (H₂), the lightest gas in the air, has significant biological effects of anti-oxidation, anti-inflammation, and anti-apoptosis. The mammalian cells have no abilities to produce H₂ due to lack of the expression of hydrogenase. The endogenous H₂ in human body is mainly produced by anaerobic bacteria, such as Firmicutes and Bacteroides, in gut and other organs through the reversible oxidation reaction of 2 H⁺ + 2 e^- ⇌ H₂. Supplement of exogenous H₂ can improve many kinds of liver injuries, modulate glucose and lipids metabolism in animal models or in human beings. Moreover, hepatic glycogen has strong ability to accumulate H₂, thus, among the organs examined, liver has the highest concentration of H₂ after supplement of exogenous H₂ by various strategies in vivo. The inadequate production of endogenous H₂ play essential roles in brain, heart, and liver disorders, while enhanced endogenous H₂ production may improve hepatitis, hepatic ischemia and reperfusion injury, liver regeneration, and hepatic steatosis. Therefore, the endogenous H₂ may play essential roles in maintaining liver homeostasis.

Salidroside ameliorates Parkinson's disease by inhibiting NLRP3-dependent pyroptosis

Parkinson's disease (PD) is a common age-related neurodegenerative movement disorder, which is mainly due to the loss of dopaminergic neurons. Pyroptosis is a new programmed cell death characterized by NLR Family Pyrin Domain Containing 3 (NLRP3)-dependent, IL-1β, IL-18 and Gasdermin D. Salidroside (Sal) has been reported to have neuro-protective effect. However, the roles of pyroptosis and Sal on anti-pyroptosis in PD have not been elucidated. In this study, we tested underlying mechanisms of pyroptosis in PD and neuro-protective effects of Sal. We established 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced C57BL/6J mice and C57BL/10ScNJ (TLR4-deficient mice) in vivo, MPTP-induced PC-12 and LPS-induced BV2 in vitro. We found that Sal could ameliorate MPTP-induced PD symptoms and reduce the levels of IL-1β, IL-18 and Gasdermin D, which are main hallmarks of pyroptosis. Further study indicated that Sal alleviated PD through inhibiting NLRP3-dependent pyroptosis. In conclusion, pyroptosis plays a key role in PD and Sal protects dopaminergic neurons by inhibiting NLRP3-dependent pyroptosis through: (1) indirectly reducing the production of NLRP3, pro-IL-1β and pro-IL-18 by inhibiting TLR4/MyD88/NF-κB signaling pathways, (2) directly suppressing pyroptosis through inhibiting TXNIP/NLRP3/caspase-1 signaling pathways. These results indicated that inhibiting pyroptosis or administration of Sal could be a novel therapeutic strategy for PD.

Gut-Liver Axis and Inflammasome Activation in Cholangiocyte Pathophysiology

The Nlrp3 inflammasome is a multiprotein complex activated by a number of bacterial products or danger signals and is involved in the regulation of inflammatory processes through caspase-1 activation. The Nlrp3 is expressed in immune cells but also in hepatocytes and cholangiocytes, where it appears to be involved in regulation of biliary damage, epithelial barrier integrity and development of fibrosis. Activation of the pathways of innate immunity is crucial in the pathophysiology of hepatobiliary diseases, given the strong link between the gut and the liver. The liver secretes bile acids, which influence the bacterial composition of the gut microbiota and, in turn, are heavily modified by microbial metabolism. Alterations of this balance, as for the development of dysbiosis, may deeply influence the composition of the bacterial products that reach the liver and are able to activate a number of intracellular pathways. This alteration may be particularly important in the pathogenesis of cholangiopathies and, in particular, of primary sclerosing cholangitis, given its strong association with inflammatory bowel disease. In the present review, we summarize current knowledge on the gut–liver axis in cholangiopathies and discuss the role of Nlrp3 inflammasome activation in cholestatic conditions.