Hepatocyte TMEM16A Deletion Retards NAFLD Progression by Ameliorating Hepatic Glucose Metabolic Disorder

Hyperatins A-D, highly oxidized polycyclic polyprenylated acylphloroglucinols from Hypericum perforatum L. with hypoglycemic potential in liver cells

Hyperatins A-D (1-4), four previously undescribed polycyclic polyprenylated acylphloroglucinols, were isolated from Hypericum perforatum L. (St. John's wort). Compound 1 possessed a unique octahydroindeno[1,7a-b]oxirene ring system with a rare 2,7-dioxabicyclo[2.2.1]heptane fragment. Compounds 2-4 had an uncommon decahydrospiro[furan-3,7'-indeno[7,1-bc]furan] ring system. Their structures were established by spectroscopic analyses and X-ray crystallography. Plausible biosynthetic pathways of 1-4 were also proposed. Compounds 1 and 2 exerted promising hypoglycemic activity by inhibiting glycogen synthase kinase 3 expression in liver cells.

The role of anoctamin 1 in liver disease

Liver diseases include all types of viral hepatitis, alcoholic liver disease (ALD), nonalcoholic fatty liver disease (NAFLD), cirrhosis, liver failure (LF) and hepatocellular carcinoma (HCC). Liver disease is now one of the leading causes of disease and death worldwide, which compels us to better understand the mechanisms involved in the development of liver diseases. Anoctamin 1 (ANO1), a calcium-activated chloride channel (CaCC), plays an important role in epithelial cell secretion, proliferation and migration. ANO1 plays a key role in transcriptional regulation as well as in many signalling pathways. It is involved in the genesis, development, progression and/or metastasis of several tumours and other diseases including liver diseases. This paper reviews the role and molecular mechanisms of ANO1 in the development of various liver diseases, aiming to provide a reference for further research on the role of ANO1 in liver diseases and to contribute to the improvement of therapeutic strategies for liver diseases by regulating ANO1.

Ferroptosis in organ ischemia-reperfusion injuries: recent advancements and strategies

Ferroptosis is a newly discovered type of regulated cell death participated in multiple diseases. Different from other classical cell death programs such as necrosis and apoptosis, ferroptosis involving iron-catalyzed lipid peroxidation is characterized by Fe2+ accumulation and mitochondria alterations. The phenomenon of oxidative stress following organ ischemia-reperfusion (I/R) has recently garnered attention for its connection to the onset of ferroptosis and subsequent reperfusion injuries. This article provides a comprehensive overview underlying the mechanisms of ferroptosis, with a further focus on the latest research progress regarding interference with ferroptotic pathways in organ I/R injuries, such as intestine, lung, heart, kidney, liver, and brain. Understanding the links between ferroptosis and I/R injury may inform potential therapeutic strategies and targeted agents.

Dual action of macrophage miR-204 confines cyclosporine A-induced atherosclerosis

BACKGROUND AND PURPOSE

Atherosclerosis induced by cyclosporine A (CsA), an inhibitor of the calcineurin/nuclear factor of activated T cells (NFAT) pathway, is a major concern after organ transplantation. However, the atherosclerotic mechanisms of CsA remain obscure. We previously demonstrated that calcineurin/NFAT signalling inhibition contributes to atherogenesis via suppressing microRNA-204 (miR-204) transcription. We therefore hypothesised that miR-204 is involved in the development of CsA-induced atherosclerosis.

EXPERIMENTAL APPROACH

ApoE-/- mice with macrophage-miR-204 overexpression were generated to determine the effects of miR-204 on CsA-induced atherosclerosis. Luciferase reporter assays and chromatin immunoprecipitation sequencing were performed to explore the targets mediating miR-204 effects.

KEY RESULTS

CsA alone did not significantly affect atherosclerotic lesions or serum lipid levels. However, it exacerbated high-fat diet-induced atherosclerosis and hyperlipidemia in C57BL/6J and ApoE-/- mice, respectively. miR-204 levels decreased in circulating monocytes and plaque lesions during CsA-induced atherosclerosis. The upregulation of miR-204 in macrophages inhibited CsA-induced atherosclerotic plaque formation but did not affect serum lipid levels. miR-204 limited the CsA-induced foam cell formation by reducing the expression of the scavenger receptors SR-BII and CD36. SR-BII was post-transcriptionally regulated by mature miR-204-5p via 3'-UTR targeting. Additionally, nuclear-localised miR-204-3p prevented the CsA-induced binding of Ago2 to the CD36 promoter, suppressing CD36 transcription. SR-BII or CD36 expression restoration dampened the beneficial effects of miR-204 on CsA-induced atherosclerosis.

CONCLUSION AND IMPLICATIONS

Macrophage miR-204 ameliorates CsA-induced atherosclerosis, suggesting that miR-204 may be a potential target for the prevention and treatment of CsA-related atherosclerotic side effects.

Multi-omics analysis of a fatty liver model using human hepatocyte chimeric mice

We developed a fatty liver mouse model using human hepatocyte chimeric mice. As transplanted human hepatocytes do not respond to mouse growth hormone (GH) and tend to accumulate fat, we hypothesized that addition of human GH would alter lipid metabolism and reduce accumulation of fat in the liver even when fed a high-fat diet. Six uPA/SCID chimeric mice were fed a high-fat GAN diet to induce fatty liver while six were fed a normal CRF1 diet, and GH was administered to three mice in each group. The mice were euthanized at 8 weeks, and human hepatocytes were extracted for RNA-Seq, DIA proteomics, and metabolomics analysis. Abdominal echocardiography revealed that the degree of fatty liver increased significantly in mice fed GAN diet (p < 0.001) and decreased significantly in mice treated with GH (p = 0.026). Weighted gene correlation network analysis identified IGF1 and SEMA7A as eigengenes. Administration of GH significantly reduced triglyceride levels and was strongly associated with metabolism of amino acids. MiBiOmics analysis identified perilipin-2 as a co-inertia driver. Results from multi-omics analysis revealed distinct gene expression and protein/metabolite profiles in each treatment group when mice were fed a high-fat or normal diet with or without administration of GH.

Protein Tyrosine Phosphatase SHP2 in Macrophages Acts as an Antiatherosclerotic Regulator in Mice

BACKGROUND

Macrophages have versatile roles in atherosclerosis. SHP2 (Src homology 2 containing protein tyrosine phosphatase 2) has been demonstrated to play a critical role in regulating macrophage activation. However, the mechanism of SHP2 regulation of macrophage function in an atherosclerotic microenvironment remains unknown.

METHODS

APOE (apolipoprotein E) or LDLR (low-density lipoprotein receptor) null mice treated with SHP099 were fed a Western diet for 8 weeks, while Shp2MKO:ApoE-/- or Shp2MKO:Ldlr-/- mice and exo-AAV8-SHP2E76K/ApoE-/- mice were fed a Western diet for 12 weeks. In vitro, levels of proinflammatory factors and phagocytic function were then studied in mouse peritoneal macrophages. RNA sequencing was used to identify PPARγ (peroxisome proliferative activated receptor γ) as the key downstream molecule. A PPARγ agonist was used to rescue the phenotypes observed in SHP2-deleted mice.

RESULTS

Pharmacological inhibition and selective deletion in macrophages of SHP2 aggravated atherosclerosis in APOE and LDLR null mice with increased plaque macrophages and apoptotic cells. In vitro, SHP2 deficiency in APOE and LDLR null macrophages enhanced proinflammatory polarization and its efferocytosis was dramatically impaired. Conversely, the expression of gain-of-function mutation of SHP2 in mouse macrophages reduced atherosclerosis. The SHP2 agonist lovastatin repressesed macrophage inflammatory activation and enhanced efferocytosis. Mechanistically, RNA sequencing analysis identified PPARγ as a key downstream transcription factor. PPARγ was decreased in macrophages upon SHP2 deletion and inhibition. Importantly, PPARγ agonist decreased atherosclerosis in SHP2 knockout mice, restored efferocytotic defects, and reduced inflammatory activation in SHP2 deleted macrophages. PPARγ was decreased by the ubiquitin-mediated degradation upon SHP2 inhibition or deletion. Finally, we found that SHP2 was downregulated in atherosclerotic vessels.

CONCLUSIONS

Overall, SHP2 in macrophages was found to act as an antiatherosclerotic regulator by stabilizing PPARγ in APOE/LDLR null mice.

Transaldolase inhibits CD36 expression by modulating glutathione-p38 signaling, exerting protective effects against macrophage foam cell formation

In atherosclerosis, macrophage-derived foam cell formation is considered to be a hallmark of the pathological process; this occurs via the uptake of modified lipoproteins. In the present study, we aim to determine the role of transaldolase in foam cell formation and atherogenesis and reveal the mechanisms underlying its role. Bone marrow-derived macrophages (BMDMs) isolated from mice successfully form foam cells after treatment with oxidized low-density lipoprotein (80 μg/mL). Elevated transaldolase levels in the foam cell model are assessed by quantitative polymerase chain reaction and western blot analysis. Transaldolase overexpression and knockdown in BMDMs are achieved via plasmid transfection and small interfering RNA technology, respectively. We find that transaldolase overexpression effectively attenuates, whereas transaldolase knockdown accelerates, macrophage-derived foam cell formation through the inhibition or activation of cholesterol uptake mediated by the scavenger receptor cluster of differentiation 36 (CD36) in a p38 mitogen-activated protein kinase (MAPK) signaling-dependent manner. Transaldolase-mediated glutathione (GSH) homeostasis is identified as the upstream regulator of p38 MAPK-mediated CD36-dependent cholesterol uptake in BMDMs. Transaldolase upregulates GSH production, thereby suppressing p38 activity and reducing the CD36 level, ultimately preventing foam cell formation and atherosclerosis. Thus, our findings indicate that the transaldolase-GSH-p38-CD36 axis may represent a promising therapeutic target for atherosclerosis.

Hepatic PTP4A1 ameliorates high-fat diet-induced hepatosteatosis and hyperglycemia by the activation of the CREBH/FGF21 axis

Precise regulation of kinases and phosphatases is crucial for human metabolic homeostasis. This study aimed to investigate the roles and molecular mechanisms of protein tyrosine phosphatase type IVA1 (PTP4A1) in regulating hepatosteatosis and glucose homeostasis. Method: Ptp4a1^-/- mice, adeno-associated virus encoding Ptp4a1 under liver-specific promoter, adenovirus encoding Fgf21, and primary hepatocytes were used to evaluate PTP4A1-mediated regulation in the hepatosteatosis and glucose homeostasis. Glucose tolerance test, insulin tolerance test, 2-deoxyglucose uptake assay, and hyperinsulinemic-euglycemic clamp were performed to estimate glucose homeostasis in mice. The staining, including oil red O, hematoxylin & eosin, and BODIPY, and biochemical analysis for hepatic triglycerides were performed to assess hepatic lipids. Luciferase reporter assays, immunoprecipitation, immunoblots, quantitative real-time polymerase chain reaction, and immunohistochemistry staining were conducted to explore the underlying mechanism. Results: Here, we found that deficiency of PTP4A1 aggravated glucose homeostasis and hepatosteatosis in mice fed a high-fat (HF) diet. Increased lipid accumulation in hepatocytes of Ptp4a1^-/- mice reduced the level of glucose transporter 2 on the plasma membrane of hepatocytes leading to a diminution of glucose uptake. PTP4A1 prevented hepatosteatosis by activating the transcription factor cyclic adenosine monophosphate-responsive element-binding protein H (CREBH)/fibroblast growth factor 21 (FGF21) axis. Liver-specific PTP4A1 or systemic FGF21 overexpression in Ptp4a1^-/- mice fed an HF diet restored the disorder of hepatosteatosis and glucose homeostasis. Finally, liver-specific PTP4A1 expression ameliorated an HF diet-induced hepatosteatosis and hyperglycemia in wild-type mice. Conclusions: Hepatic PTP4A1 is critical for regulating hepatosteatosis and glucose homeostasis by activating the CREBH/FGF21 axis. Our current study provides a novel function of PTP4A1 in metabolic disorders; hence, modulating PTP4A1 may be a potential therapeutic strategy against hepatosteatosis-related diseases.

Hepatocyte-specific TMEM16A deficiency alleviates hepatic ischemia/reperfusion injury via suppressing GPX4-mediated ferroptosis

Ischemia/reperfusion (I/R)-induced liver injury with severe cell death is a major complication of liver transplantation. Transmembrane member 16A (TMEM16A), a component of hepatocyte Ca²⁺-activated chloride channel, has been implicated in a variety of liver diseases. However, its role in hepatic I/R injury remains unknown. Here, mice with hepatocyte-specific TMEM16A knockout or overexpression were generated to examine the effect of TMEM16A on hepatic I/R injury. TMEM16A expression increased in liver samples from patients and mice with I/R injury, which was correlated with liver damage progression. Hepatocyte-specific TMEM16A knockout alleviated I/R-induced liver damage in mice, ameliorating inflammation and ferroptotic cell death. However, mice with hepatic TMEM16A overexpression showed the opposite phenotype. In addition, TMEM16A ablation decreased inflammatory responses and ferroptosis in hepatocytes upon hypoxia/reoxygenation insult in vitro, whereas TMEM16A overexpression promoted the opposite effects. The ameliorating effects of TMEM16A knockout on hepatocyte inflammation and cell death were abolished by chemically induced ferroptosis, whereas chemical inhibition of ferroptosis reversed the potentiated role of TMEM16A in hepatocyte injury. Mechanistically, TMEM16A interacted with glutathione peroxidase 4 (GPX4) to induce its ubiquitination and degradation, thereby enhancing ferroptosis. Disruption of TMEM16A-GPX4 interaction abrogated the effects of TMEM16A on GPX4 ubiquitination, ferroptosis, and hepatic I/R injury. Our results demonstrate that TMEM16A exacerbates hepatic I/R injury by promoting GPX4-dependent ferroptosis. TMEM16A-GPX4 interaction and GPX4 ubiquitination are therefore indispensable for TMEM16A-regulated hepatic I/R injury, suggesting that blockades of TMEM16A-GPX4 interaction or TMEM16A inhibition in hepatocytes may represent promising therapeutic strategies for acute liver injury.

Ponatinib modulates the metabolic profile of obese mice by inhibiting adipose tissue macrophage inflammation

Obesity-induced metabolic syndrome is a rapidly growing conundrum, reaching epidemic proportions globally. Chronic inflammation in obese adipose tissue plays a key role in metabolic syndrome with a series of local and systemic effects such as inflammatory cell infiltration and inflammatory cytokine secretion. Adipose tissue macrophages (ATM), as one of the main regulators in this process, are particularly crucial for pharmacological studies on obesity-related metabolic syndrome. Ponatinib, a multi-targeted tyrosine kinase inhibitor originally used to treat leukemia, has recently been found to improve dyslipidemia and atherosclerosis, suggesting that it may have profound effect on metabolic syndrome, although the mechanisms underlying have not yet been revealed. Here we discovered that ponatinib significantly improved insulin sensitivity in leptin deficient obese mice. In addition to that, ponatinib treatment remarkably ameliorated high fat diet-induced hyperlipidemia and inhibited ectopic lipid deposition in the liver. Interestingly, although ponatinib did not reduce but increase the weight of white adipose tissue (WAT), it remarkably suppressed the inflammatory response in WAT and preserved its function. Mechanistically, we showed that ponatinib had no direct effect on hepatocyte or adipocyte but attenuated free fatty acid (FFA) induced macrophage transformation from pro-inflammatory to anti-inflammatory phenotype. Moreover, adipocytes co-cultured with FFA-treated macrophages exhibited insulin resistance, while pre-treat these macrophages with ponatinib can ameliorate this process. These results suggested that the beneficial effects of ponatinib on metabolic disorders are achieved by inhibiting the inflammatory phenotypic transformation of ATMs, thereby maintaining the physiological function of adipose tissue under excessive obesity. The data here not only revealed the novel therapeutic function of ponatinib, but also provided a theoretical basis for the application of multi-target tyrosine kinase inhibitors in metabolic diseases.

Transmembrane channel activity in human hepatocytes and cholangiocytes derived from induced pluripotent stem cells

The initial creation of human-induced pluripotent stem cells (iPSCs) set the foundation for the future of regenerative medicine. Human iPSCs can be differentiated into a variety of cell types in order to study normal and pathological molecular mechanisms. Currently, there are well-defined protocols for the differentiation, characterization, and establishment of functionality in human iPSC-derived hepatocytes (iHep) and iPSC-derived cholangiocytes (iCho). Electrophysiological study on chloride ion efflux channel activity in iHep and iCho cells has not been previously reported. We generated iHep and iCho cells and characterized them based on hepatocyte-specific and cholangiocyte-specific markers. The relevant transmembrane channels were selected: cystic fibrosis transmembrane conductance regulator, leucine rich repeat-containing 8 subunit A, and transmembrane member 16 subunit A. To measure the activity in these channels, we used whole-cell patch-clamp techniques with a standard intracellular and extracellular solution. Our iHep and iCho cells demonstrated definitive activity in the selected transmembrane channels, and this approach may become an important tool for investigating human liver biology of cholestatic diseases.

Anoctamin 1 controls bone resorption by coupling Cl- channel activation with RANKL-RANK signaling transduction

Osteoclast over-activation leads to bone loss and chloride homeostasis is fundamental importance for osteoclast function. The calcium-activated chloride channel Anoctamin 1 (also known as TMEM16A) is an important chloride channel involved in many physiological processes. However, its role in osteoclast remains unresolved. Here, we identified the existence of Anoctamin 1 in osteoclast and show that its expression positively correlates with osteoclast activity. Osteoclast-specific Anoctamin 1 knockout mice exhibit increased bone mass and decreased bone resorption. Mechanistically, Anoctamin 1 deletion increases intracellular Cl^- concentration, decreases H⁺ secretion and reduces bone resorption. Notably, Anoctamin 1 physically interacts with RANK and this interaction is dependent upon Anoctamin 1 channel activity, jointly promoting RANKL-induced downstream signaling pathways. Anoctamin 1 protein levels are substantially increased in osteoporosis patients and this closely correlates with osteoclast activity. Finally, Anoctamin 1 deletion significantly alleviates ovariectomy induced osteoporosis. These results collectively establish Anoctamin 1 as an essential regulator in osteoclast function and suggest a potential therapeutic target for osteoporosis.

PREX1 depletion ameliorates high-fat diet-induced non-alcoholic fatty liver disease in mice and mitigates palmitic acid-induced hepatocellular injury via suppressing the NF-κB signaling pathway

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver diseases worldwide. Oxidative stress has been considered a key factor in the pathogenesis of NAFLD. Phosphatidylinositol (3,4,5)-trisphosphate-dependent Rac exchanger 1 (PREX1), a guanine nucleotide exchange factor for Rac, has been associated with inflammation and oxidative stress. This study aimed to investigate the biological function of PREX1 in the progression of NAFLD. Male C57BL/6 mice were fed a high-fat diet for 12 weeks to induce NAFLD in vivo. Adeno-associated virus type 8-mediated liver-specific PREX1 depletion was employed to investigate the role of PREX1 in the progression of high-fat diet-induced NAFLD. Murine hepatocyte cell line AML-12 was stimulated with palmitic acid for 24 h to induce steatosis in vitro. PREX1 depletion was carried out by transfection with PREX1 small interfering RNA. Results showed that PREX1 depletion exerted protective effects against lipid accumulation, oxidative stress and inflammation and inhibited activation of the nuclear factor-κB (NF-κB) signaling pathway in vivo and in vitro. Subsequently, NF-κB inhibitor BAY11-7082 was applied to investigate the role of the NF-κB signaling pathway in the protective effect of PREX1 inhibition against NAFLD. We confirmed that PREX1 inhibition mitigated palmitic acid-induced hepatocellular inflammation mainly via the NF-κB signaling pathway and lipid accumulation and oxidative stress at least partly via the NF-κB signaling pathway. This study highlights the biological function of PREX1 in the pathogenesis of NAFLD.

NUSAP1 Could be a Potential Target for Preventing NAFLD Progression to Liver Cancer

Background: Non-alcoholic fatty liver disease (NAFLD) has gradually emerged as the most prevalent cause of chronic liver diseases. However, specific changes during the progression of NAFLD from non-fibrosis to advanced fibrosis and then hepatocellular carcinoma (HCC) are unresolved. Here, we firstly identify the key gene linking NAFLD fibrosis and HCC through analysis and experimental verification.

Methods: Two GEO datasets (GSE89632, GSE49541) were performed for identifying differentially expressed genes (DEGs) associated with NAFLD progression from non-fibrosis to early fibrosis and eventually to advanced fibrosis. Subsequently, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment analysis, protein-protein interaction (PPI) network were integrated to explore the potential function of the DEGs and hub genes. The expression of NUSAP1 was confirmed in vivo and in vitro NAFLD models at mRNA and protein level. Then, cell proliferation and migration under high fat conditions were verified by cell counting kit-8 (CCK-8) and wound-healing assays. The lipid content was measured with Oil Red O staining. Finally, the analysis of clinical survival curves was performed to reveal the prognostic value of the crucial genes among HCC patients via the online web-tool GEPIA2 and KM plotter.

Results: 5510 DEGs associated with non-fibrosis NAFLD, 3913 DEGs about NAFLD fibrosis, and 739 DEGs related to NAFLD progression from mild fibrosis to advanced fibrosis were identified. Then, a total of 112 common DEGs were found. The result of enrichment analyses suggested that common DEGs were strongly associated with the glucocorticoid receptor pathway, regulation of transmembrane transporter activity, peroxisome, and proteoglycan biosynthetic process. Six genes, including KIAA0101, NUSAP1, UHRF1, RAD51AP1, KIF22, and ZWINT, were identified as crucial candidate genes via the PPI network. The expression of NUSAP1 was validated highly expressed in vitro and vivo NAFLD models at mRNA and protein level. NUSAP1 silence could inhibit the ability of cell proliferation, migration and lipid accumulation in vitro. Finally, we also found that NUSAP1 was significantly up-regulated at transcriptional and protein levels, and associated with poor survival and advanced tumor stage among HCC patients.

Conclusion: NUSAP1 may be a potential therapeutic target for preventing NAFLD progression to liver cancer.

The Imbalance of Mitochondrial Homeostasis of Peripheral Blood-Derived Macrophages Mediated by MAFLD May Impair the Walking Ability of Elderly Patients with Osteopenia

Introduction

Many Asian cohort studies have shown that nonalcoholic fatty liver disease (NAFLD), now renamed as metabolic dysfunction-associated fatty liver disease (MAFLD), increases the risk of osteoporosis, yet the effect of MAFLD on elderly patients with osteopenia (OPe) has not been reported.

Objective

This study aimed to explore the influence of MAFLD on the function of macrophages in patients with OPe.

Methods

A total of 107 elderly OPe patients with or without MAFLD who visited the Huadong Hospital Affiliated to Fudan University (Shanghai, China) between January 1st, 2021, and September 30th, 2021, were evaluated for an interviewer-assisted questionnaire, as well as clinical and biological assessments.

Results

Comparing two groups of elderly patients with the same bone mass level, we found that the six-minute walking distance (P = 0.012) and short physical performance battery (SPPB) score (P = 0.0029) of the elderly OPe patients with MAFLD are worse than those in OPe patients without MAFLD. Our results confirmed that the mitochondrial reactive oxygen species (mtROS) in peripheral blood of OPe patients with MAFLD was significantly higher than those without. We also observed the mitochondrial metabolism level of peripheral blood-derived macrophages in the included patients and peripheral blood macrophages in patients with MAFLD with more unbalanced mitochondrial dynamics of macrophages, more weakened mitochondrial respiratory capacity, and greater mitochondrial microstructure damage, when compared with the elderly patients without MAFLD.

Conclusions

To conclude, our data revealed that MAFLD itself may aggravate the inflammatory state in elderly OPe people due to mitochondrial homeostasis imbalance of peripheral blood macrophages. Damaged monocyte-macrophages might trigger attenuation of the walking ability of OPe patients.

The diverse roles of TMEM16A Ca2+-activated Cl- channels in inflammation

Background

Transmembrane protein 16A (TMEM16A) Ca²⁺-activated Cl^- channels have diverse physiological functions, such as epithelial secretion of Cl^- and fluid and sensation of pain. Recent studies have demonstrated that TMEM16A contributes to the pathogenesis of infectious and non-infectious inflammatory diseases. However, the role of TMEM16A in inflammation has not been clearly elucidated.

Aim of review

In this review, we aimed to provide comprehensive information regarding the roles of TMEM16A in inflammation by summarizing the mechanisms underlying TMEM16A expression and activation under inflammatory conditions, in addition to exploring the diverse inflammatory signaling pathways activated by TMEM16A. This review attempts to develop the idea that TMEM16A plays a diverse role in inflammatory processes and contributes to inflammatory diseases in a cellular environment-dependent manner.

Key scientific concepts of review

Multiple inflammatory mediators, including cytokines (e.g., interleukin (IL)-4, IL-13, IL-6), histamine, bradykinin, and ATP/UTP, as well as bacterial and viral infections, promote TMEM16A expression and/or activity under inflammatory conditions. In addition, TMEM16A activates diverse inflammatory signaling pathways, including the IP₃R-mediated Ca²⁺ signaling pathway, the NF-κB signaling pathway, and the ERK signaling pathway, and contributes to the pathogenesis of many inflammatory diseases. These diseases include airway inflammatory diseases, lipopolysaccharide-induced intestinal epithelial barrier dysfunction, acute pancreatitis, and steatohepatitis. TMEM16A also plays multiple roles in inflammatory processes by increasing vascular permeability and leukocyte adhesion, promoting inflammatory cytokine release, and sensing inflammation-induced pain. Furthermore, TMEM16A plays its diverse pathological roles in different inflammatory diseases depending on the disease severity, proliferating status of the cells, and its interacting partners. We herein propose cellular environment-dependent mechanisms that explain the diverse roles of TMEM16A in inflammation.

Ginkgo biloba Extract 50 (GBE50) Ameliorates Insulin Resistance, Hepatic Steatosis and Liver Injury in High Fat Diet-Fed Mice

Background

Ginkgo biloba extract 50 (GBE50) has a variety of pharmacological functions such as anti-inflammatory, antioxidant and maintenance of glucose and lipid metabolism homeostasis. However, the therapeutic effects and mechanisms of GBE50 on non-alcoholic fatty liver disease (NAFLD) remain unknown. Therefore, in this study, we evaluated the therapeutic effects of GBE50 in NAFLD by using a high-fat diet (HFD) mice model.

Methods

C57BL/6J mice were fed a HFD diet for 15 weeks and were given respectively 25, 50, and 100 mg/kg GBE50 daily by gavage from 3 to 15 weeks. After the administration, blood samples and liver tissues were collected for biochemical detection, histological measurement, immunohistochemistry and Western blot, respectively.

Results

We found that GBE50 treatment could ameliorate insulin resistance (IR), glucose intolerance, lipid accumulation, hepatic steatosis and liver injury in HFD-fed mice. Further mechanism exploration discovered that the hepatoprotective effects of GBE50 on NAFLD may be related to the strengthening of IRS-1 signal activation and the weakening of NF-κB, Akt and endoplasmic reticulum stress signals activation.

Conclusion

GBE50 is a potentially powerful therapeutic agent for the treatment of NAFLD.

MicroRNA-302a promotes neointimal formation following carotid artery injury in mice by targeting PHLPP2 thus increasing Akt signaling

The excessive proliferation and migration of smooth muscle cells (SMCs) play an important role in restenosis following percutaneous coronary interventions. MicroRNAs are able to target various genes and involved in the regulation of diverse cellular processes including cell growth and proliferation. In this study we investigated whether and how MicroRNAs regulated vascular SMC proliferation and vascular remodeling following carotid artery injury in mice. We showed that carotid artery injury-induced neointimal formation was remarkably ameliorated in microRNA (miR)-302 heterozygous mice and SMC-specific miR-302 knockout mice. In contrast, delivery of miR-302a adenovirus to the injured carotid artery enhanced neointimal formation. Upregulation of miR-302a enhanced the proliferation and migration of mouse aorta SMC (MASMC) in vitro by promoting cell cycle transition, whereas miR-302a inhibition caused the opposite results. Moreover, miR-302a promoted Akt activation by corporately decreasing Akt expression and increasing Akt phosphorylation in MASMCs. Application of the Akt inhibitor GSK690693 (5 μmol/L) counteracted the functions of miR-302a in promoting MASMC proliferation and migration. We further revealed that miR-302a directly targeted at the 3' untranslated region of PH domain and leucine rich repeat protein phosphatase 2 (PHLPP2) and negatively regulated PHLPP2 expression. Restoration of PHLPP2 abrogated the effects of miR-302a on Akt activation and MASMC motility. Furthermore, knockdown of PHLPP2 largely abolished the inhibition of neointimal formation that was observed in miR-302 heterozygous mice. Our data demonstrate that miR-302a exacerbates SMC proliferation and restenosis through increasing Akt signaling by targeting PHLPP2.

Nrf2 mitigates prolonged PM2.5 exposure-triggered liver inflammation by positively regulating SIKE activity: Protection by Juglanin

Air pollution containing particulate matter (PM) less than 2.5 μm (PM2.5) plays an essential role in regulating hepatic disease. However, its molecular mechanism is not yet clear, lacking effective therapeutic strategies. In this study, we attempted to investigate the effects and mechanisms of PM2.5 exposure on hepatic injury by the in vitro and in vivo experiments. At first, we found that PM2.5 incubation led to a significant reduction of nuclear factor erythroid-derived 2-related factor 2 (Nrf2), along with markedly reduced expression of different anti-oxidants. Notably, suppressor of IKKε (SIKE), known as a negative regulator of the interferon pathway, was decreased in PM2.5-incubated cells, accompanied with increased activation of TANK-binding kinase 1 (TBK1) and nuclear factor-κB (NF-κB). The in vitro studies showed that Nrf2 positively regulated SIKE expression under the conditions with or without PM2.5. After PM2.5 treatment, Nrf2 knockdown further accelerated SIEK decrease and TBK1/NF-κB activation, and opposite results were observed in cells with Nrf2 over-expression. Subsequently, the gene loss- and gain-function analysis demonstrated that SIKE deficiency further aggravated inflammation and TBK1/NF-κB activation caused by PM2.5, which could be abrogated by SIKE over-expression. Importantly, SIKE-alleviated inflammation was mainly dependent on TBK1 activation. The in vivo studies confirmed that SIKE- and Nrf2-knockout mice showed significantly accelerated hepatic injury after long-term PM2.5 exposure through reducing inflammatory response and oxidative stress. Juglanin (Jug), mainly isolated from Polygonum aviculare, exhibits anti-inflammatory and anti-oxidant effects. We found that Jug could increase Nrf2 activation, and then up-regulated SIKE in cells and liver tissues, mitigating PM2.5-induced liver injury. Together, all these data demonstrated that Nrf2 might positively meditate SIKE to inhibit inflammatory and oxidative damage, ameliorating PM2.5-induced liver injury. Jug could be considered as an effective therapeutic strategy against this disease by improving Nrf2/SIKE signaling pathway.

ClC-2 inhibition prevents macrophage foam cell formation by suppressing Nlrp3 inflammasome activation

Macrophage foam cell formation and inflammation are a pathological hallmark of atherosclerosis. ClC-2 has been implicated in various pathological processes, including inflammation and lipid metabolic disorder. However, the functional role of ClC-2 in macrophage foam cell formation and inflammation is unclear. Here, we found that ClC-2 was dominantly expressed in macrophages of atherosclerotic plaque and increased in atherogenesis. Knockdown of ClC-2 inhibited ox-LDL -induced lipid uptake and deposition in macrophages. The increase in CD36 expression and the decrease in ABCA1 expression induced by ox-LDL were alleviated by ClC-2 downregulation. Further, ClC-2 lacking limited the ox-LDL-induced secretion of inflammatory cytokines and chemokine, and suppressed Nlrp3 inflammasome activation. Restoration of Nlrp3 expression reversed the effect of ClC-2 downregulation on macrophage lipid accumulation and inflammation. Collectively, our study demonstrates that ClC-2 knockdown ameliorates ox-LDL-induced macrophage foam cell formation and inflammation by inhibiting Nlrp3 inflammasome activation.