ATP/P2X7-NLRP3 axis of dendritic cells participates in the regulation of airway inflammation and hyper-responsiveness in asthma by mediating HMGB1 expression and secretion.

The ATP/P2X7 axis of dendritic cells (DCs) mediates the activation of NLRP3 inflammasome and promotes secretion of interleukin (IL)-1ß and IL-18 to induce T helper (Th) 2, Th17 differentiation in the pathogenesis of asthma. NLRP3 inflammasome also regulates high mobility protein 1 (HMGB1) release in DCs. Recent studies demonstrated the correlation between HMGB1 expression and airway inflammation and hyper-responsiveness (AHR) in asthma. However, the relationship between the ATP/P2X7-NLRP3 axis and HMGB1 in DCs in asthma is still unclear. ATP, apyrase, Brilliant Blue G, BzATP, glibenclamide, and Z-YVAD-FMK were administered to ovalbumin (OVA)-induced murine asthmatic model. For in vitro studies, bone marrow-derived mononuclear cells (BMDCs) were primed with LPS and stimulated with the same reagents. Activation of the ATP/P2X7 axis aggravated airway inflammation and AHR in the lung and induced Th2, Th17 polarization in asthmatic mice. Inhibition of NLRP3 inflammasome weakened cardinal features of asthma and blocked Th2, Th17 polarization. In vitro and vivo, ATP/P2X7 axis activated NLRP3 inflammasome and induced HMGB1 expression and release from DCs. Inhibition of NLRP3 inflammasome reduced HMGB1 expression and release. The ATP/P2X7-NLRP3 axis of DCs participates in mediating airway inflammation, AHR, and promoting Th2, Th17 inflammatory responses in asthmatic mice by inducing HMGB1 expression and secretion.

Hepatic IDH2 regulates glycolysis and gluconeogenesis.

BACKGROUND AND AIMS: The liver plays a central role in controlling glucose and lipid metabolism. IDH2, a mitochondrial protein, controls TCA cycle flux. However, its role in regulating metabolism in obesity is still unclear. This study intends to investigate the impact of hepatic IDH2 expression on overnutrition-regulated glucose and lipid metabolism. METHODS: Hepatic IDH2 was knocked-out in mice by the approach of CRISPR-Cas9. Mice were subjected to starvation and refeeding for hepatic glucose and lipid studies in vivo. Primary hepatocytes and mouse normal liver cell line, AML12 cells were used for experiments in vitro. RESULTS: This study found that IDH2 protein levels were elevated in the livers of obese people and mice with high-fat diet consumption or hepatic steatosis. Liver IDH2-deletion mice (IDH2LKO) were resistant to high-fat diet-induced body weight gain, with lower serum glucose and TG levels, increased insulin sensitivity, and higher FGF21 secretion, despite the higher TG content in the liver. Consistently, overexpression of IDH2 in hepatocytes promoted gluconeogenesis and enhanced glycogenesis. By performing mass spectrometry and proteomics analyses, we further demonstrated that IDH2-deficiency in hepatocytes accelerated ATP production by increasing forward TCA cycle flux, thus promoting glycolysis pathway and decreasing glycogen synthesis at refeeding state, and inhibiting hepatic gluconeogenesis, increasing ß-oxidation during starvation. Moreover, experiments in vivo demonstrated that IDH2-knockout might not exacerbate hepatic inflammatory responses in the NASH model. CONCLUSIONS: Elevated hepatic IDH2 under over-nutrition state contributes to elevated gluconeogenesis and glycogen synthesis. Inhibition of IDH2 in the liver could be a potential therapeutic target for obesity and diabetes.

Sigma­1 receptor overexpression promotes proliferation and ameliorates cell apoptosis in ß­cells.

Sigma­1 receptor (Sig­1R) is a class of orphan receptors, the potential role of which in pancreatic islet cells remains poorly understood. The present study aimed to investigate the role of Sig­1R in islet ß­cell proliferation and examine the effects of Sig­1R on islet ß­cell injury under lipotoxic conditions. Sig­1R­overexpressing MIN6 cells were generated by lentiviral vector transfection. The effect of Sig­1R overexpression on cell proliferation detected by EdU staining, cell cycle progression by propidium iodide (PI), apoptosis by Annexin V­APC/PI, mitochondrial membrane potential by Mitolite Red and cytoplasmic Ca2+ levelsby Fura­2/AM in islet ß­cells were measured by flow cytometry. Western blot analysis was used to measure protein expression levels of endoplasmic reticulum (ER) stress markers glucose­regulated protein 78 and C/EBP homologous protein, mitochondrial apoptotic proteins Bcl­2­associated X and Bcl­2 and cytochrome c. In addition, ATP levels and insulin secretion were separately measured using ATP Assay and mouse insulin ELISA. Mitochondria­associated ER membrane (MAM) structures in MIN6 cells were then detected using transmission electron microscopy. Protein disulfide isomerase expression and possible colocalization between inositol 1,4,5­trisphosphate receptor and voltage­dependent anion channel 1 were examined using immunofluorescence. Sig­1R overexpression was found to promote ß­cell proliferation by accelerating cell cycle progression. Furthermore, Sig­1R overexpression ameliorated the apoptosis rate whilst impairing insulin secretion induced by palmitic acid by relieving ER stress and mitochondrial dysfunction in MIN6 cells. Sig­1R overexpression also promoted Ca2+ transport between mitochondria and ER by increasing the quantity of ER adjacent to mitochondria in the 50­nm range. It was concluded that Sig­1R overexpression conferred protective effects on ß­cells against lipotoxicity as a result of the promotion of cell proliferation and inhibition of ER stress and oxidative stress, by regulating the structure of MAM.

Sigma receptor knockdown augments dysfunction and apoptosis of beta cells induced by palmitate.

Sigma-1 receptor (Sig-1R) is located in the endoplasmic reticulum (ER) and clustered on the mitochondria related endoplasmic membranes, which are involved in the regulation of nervous system disease. Here, we designed Sig-1R silence MIN6 cells and studied the influence of Sig-1R silence on beta cells. We showed Sig-1R inactivation in MIN6 cells could not only decrease cell proliferation but also inhibit cell cycle, and this inhibitory effect on cell cycle might be achieved by regulating the FoxM1/Plk1/Cenpa pathway. Moreover, Sig-1R deficiency increased MIN6 cells sensitivity to lipotoxicity, exaggerated palmitate (PA)-induced apoptosis, and impaired insulin secretion. On the other hand, ER chaperone GRP78 and ER proapoptotic molecules CHOP increased in Sig-1R knockdown MIN6 cells. The ATP level decreased and reactive oxygen species (ROS) increased in this kind of cells. Furthermore not only GRP78 and CHOP levels, but also ATP and ROS levels changed more in Sig-1R silence cells after cultured with PA. Therefore, Sig-1R deficiency exaggerated PA induced beta cells apoptosis by aggravating ER stress and mitochondrial dysfunction. Together, our study showed that Sig-1R might influence the proliferation, apoptosis, and function of beta cells.

Nr2e1 deficiency aggravates insulin resistance and chronic inflammation of visceral adipose tissues in a diet-induced obese mice model.

AIMS: To investigate the nuclear receptor subfamily 2 group E member 1 (Nr2e1) expression in adipose tissues of obese mice and assess the role of Nr2e1 in insulin resistance and chronic inflammation of the adipose tissues. MAIN METHODS: An obese model was established in Nr2e1 knockout (KO) mice and their wild type (WT) littermates through a long-term high-fat diet (HFD) feeding regime. The epididymal fat weight, body weight, and daily food intake were recorded. The blood lipid profile, blood inflammatory factors, and the levels of fasting blood glucose (FBG) and fasting insulin were determined. We estimated insulin resistance by the homeostasis model assessment (HOMA). The expression of inflammatory factors and F4/80 was examined by polymerase chain reaction (PCR) and western blotting to assess adipose tissues inflammation. We also determined the molecules of insulin signaling and the nuclear factor kappa B (NF-κB) pathway by western blotting. KEY FINDINGS: The Nr2e1 expression was upregulated in WT obese mice when compared with that in control mice. Despite a lower body weight and epididymal fat mass in Nr2e1-/- mice, these rats showed increased inflammatory cytokines secretion, more pronounced hyperlipidemia, and impaired insulin sensitivity after HFD treatment. Further investigation revealed that Nr2e1 deletion affected the expression of insulin signaling and NF-κB pathway-related molecules in visceral adipose tissues. SIGNIFICANCE: Nr2e1 may act as a potential target to improve insulin sensitivity and inflammation in obesity and related complications.

Different effects of acetyl-CoA carboxylase inhibitor TOFA on airway inflammation and airway resistance in a mice model of asthma.

BACKGROUND AND OBJECTIVE: Acetyl CoA carboxylase (ACC) regulates the differentiation of Th1, Th2, Th17 cells and Treg cells, which play a critical role in airway inflammation of asthma. Here we investigated the role of ACC in the pathogenesis of asthma. METHODS: Chicken Ovalbumin-sensitized and -challenged mice were divided into three groups, PBS group, DMSO (solvent of TOFA) group and ACC inhibitor 5-tetradecyloxy-2-furoic acid (TOFA) + DMSO group. Airway inflammation was assessed with histology, percentages of CD4+T cell subsets in lung and spleen was assessed with flow cytometry, and airway responsiveness was assessed with FinePointe RC system. The expression of characteristic transcription factors of CD4+T cell subsets was evaluated with real-time PCR. Cytokine levels in bronchoalveolar lavage fluid (BALF) and serum was determined with ELISA. RESULTS: In asthma mice, the expression of ACC increased, while the expression of phosphorylated ACC (pACC) decreased. TOFA had no significant effect on pACC expression. TOFA reduced serum IgE, airway inflammatory cells infiltration and goblet cell hyperplasia, but dramatically increased airway responsiveness. TOFA significantly reduced the percentages of Th1, Th2, Th17 cells in lung and spleen, the expression of GATA3 and RORγt in lung, and IFN-γ, IL-4, IL-17A levels in BALF and serum. TOFA had no significant effect on the percentage of Treg cells, IL-10 level and the expression of T-bet and Foxp3. CONCLUSION: Acetyl-CoA carboxylase inhibitor TOFA might have a distinct effect on asthmatic airway inflammation and airway hyperresponsiveness.

Clinical Characteristics and Risk Factors for Mortality of COVID-19 Patients With Diabetes in Wuhan, China: A Two-Center, Retrospective Study.

OBJECTIVE: Diabetes is common in COVID-19 patients and associated with unfavorable outcomes. We aimed to describe the characteristics and outcomes and to analyze the risk factors for in-hospital mortality of COVID-19 patients with diabetes. RESEARCH DESIGN AND METHODS: This two-center retrospective study was performed at two tertiary hospitals in Wuhan, China. Confirmed COVID-19 patients with diabetes (N = 153) who were discharged or died from 1 January 2020 to 8 March 2020 were identified. One sex- and age-matched COVID-19 patient without diabetes was randomly selected for each patient with diabetes. Demographic, clinical, and laboratory data were abstracted. Cox proportional hazards regression analyses were performed to identify the risk factors associated with the mortality in these patients. RESULTS: Of 1,561 COVID-19 patients, 153 (9.8%) had diabetes, with a median age of 64.0 (interquartile range 56.0-72.0) years. A higher proportion of intensive care unit admission (17.6% vs. 7.8%, P = 0.01) and more fatal cases (20.3% vs. 10.5%, P = 0.017) were identified in COVID-19 patients with diabetes than in the matched patients. Multivariable Cox regression analyses of these 306 patients showed that hypertension (hazard ratio [HR] 2.50, 95% CI 1.30-4.78), cardiovascular disease (HR 2.24, 95% CI 1.19-4.23), and chronic pulmonary disease (HR 2.51, 95% CI 1.07-5.90) were independently associated with in-hospital death. Diabetes (HR 1.58, 95% CI 0.84-2.99) was not statistically significantly associated with in-hospital death after adjustment. Among patients with diabetes, nonsurvivors were older (76.0 vs. 63.0 years), most were male (71.0% vs. 29.0%), and they were more likely to have underlying hypertension (83.9% vs. 50.0%) and cardiovascular disease (45.2% vs. 14.8%) (all P values <0.05). Age ≥70 years (HR 2.39, 95% CI 1.03-5.56) and hypertension (HR 3.10, 95% CI 1.14-8.44) were independent risk factors for in-hospital death of patients with diabetes. CONCLUSIONS: COVID-19 patients with diabetes had worse outcomes compared with the sex- and age-matched patients without diabetes. Older age and comorbid hypertension independently contributed to in-hospital death of patients with diabetes.

Nr2e1 ablation impairs liver glucolipid metabolism and induces inflammation, high-fat diets amplify the damage.

Nonalcoholic fatty liver disease (NAFLD) is a common and complex metabolic disorder. Despite the widespread concern, there are still few effective treatments except lifestyle interventions. Nuclear receptor subfamily 2 group E member 1 (Nr2e1) is a transcription factor which regulates many biological processes, including development, growth, and differentiation of nerve cells. However, its specific function in hepatocyte is still unknown. In the present study, we found that the expression of Nr2e1 decreased in the livers of high-fat diet-fed mice. We generated Nr2e1 knockout (KO) mice and studied whether Nr2e1 ablation was related to NAFLD. We found that typical pathological features of NAFLD, including insulin resistance, hepatic steatosis, and inflammation, were present in Nr2e1-KO mice or high-fat diet-induced mice models. In conclusion, Nr2e1 ablation promotes liver steatosis and systemic insulin resistance. Nr2e1 may play a protective role in the formation of NAFLD and may serve as a worthy therapeutic target for NAFLD.

Mitochondrial unfolded protein response gene CLPP changes mitochondrial dynamics and affects mitochondrial function.

Mitochondrial dynamics is associated with mitochondrial function, which is associated with diabetes. Although an important indicator of the mitochondrial unfolded protein response, to the best of our knowledge, CLPP and its effects on mitochondrial dynamics in islet cells have not been studied to date. We analyzed the effects of CLPP on mitochondrial dynamics and mitochondrial function in the mice islet ß-cell line Min6 under high glucose and high fat conditions. Min6 cells were assigned to: Normal, HG, HG+NC, HG+siCLPP, HF, HF+NC and HF+ siCLPP groups. High glucose and high fat can promote the mRNA and protein expression of CLPP in mitochondria. The increase of mitochondrial fission, the decrese of mitochondrial fusion, and the damage of mintocondrial ultrastructure were significant in the siCLPP cell groups as compared to no-siCLPP treated groups. Meanwhile, mitochondrial functions of MIN6 cells treated with siCLPP were impaired, such as ATP decreased, ROS increased, mitochondrial membrane potential decreased. In addition, cell insulin secretion decreased and cell apoptosis rate increased in siCLPP groups. These results revealed that mitochondrial unfolded protein response geneCLPP alleviated high glucose and high fat-induced mitochondrial dynamics imbalance and mitochondrial dysfunction.

IL-4 and serum amyloid P inversely regulate fibrocyte differentiation by targeting store-operated Ca2+ channels.

BACKGROUND: Circulating fibrocytes (CFs) have been shown to participate in subepithelial fibrosis of asthma with chronic airflow limitation by acting as an important source of fibroblasts deposited beneath airway epithelia. Serum amyloid P (SAP) is an innate inhibitor of fibrocytes differentiation. Store-operated Ca2+ entry (SOCE) is the major Ca2+ influx of non-excitable cells. In this study, the role of SOCE in the regulation of fibrocytes differentiation and the effects of Th2 cytokine IL-4 and SAP on SOCE of fibrocytes were investigated. METHODS: Peripheral blood mononuclear cells or monocytes were cultured in serum-free medium for 7days to differentiate into fibrocytes; the expression of SOC channels was determined with PCR, SOCE was measured with Ca2+ fluorescence imaging. RESULTS: IL-4 significantly promoted monocyte derived fibrocytes differentiation in vitro. It also increased both SOCE which was induced by thapsigargin or UTP and molecules STIM1 and Orai1 which were related to expression of SOC channels in fibrocytes. Fibrocytes differentiation induced by IL-4 and SOC channels activity could be inhibited by SOC channel blocker SKF-96365. As expected, SAP significantly inhibited IL-4-induced differentiation of fibrocytes, the activity of SOCE and the expression of STIM1 and Orai1 in IL-4-treated fibrocytes. CONCLUSION: IL-4 and SAP reversely regulates cultured fibrocytes differentiation in vitro by respectively promoting or inhibiting the expression and activity of SOC channels in fibrocytes.

HMGB1 regulates T helper 2 and T helper17 cell differentiation both directly and indirectly in asthmatic mice.

The Th (T helper) 2 response is characteristic of allergic asthma, and Th17 cells are involved in more severe asthma. Recent studies demonstrated that HMGB1 (High mobility group box 1 protein) regulates airway inflammation and the Th2, Th17 inflammatory response in asthma. HMGB1 can interact with Toll-like receptors (TLR) 2 and 4, and the receptor for advanced glycation end products (RAGE), activating the NF-κB (nuclear factor kappa B) signaling pathway and inducing the release of downstream inflammatory mediators. Both Th cells and dendritic cells express TLR2, TLR4, and RAGE receptors. Therefore, we speculate that HMGB1 could regulate the differentiation of Th2, Th17 cells in asthma through direct and indirect mechanisms. An ovalbumin (OVA)-induced mouse asthmatic model was established. Anti-HMGB1 antibody or rHMGB1 was administered to OVA-sensitized mice 30 min prior to each challenge. For in vitro studies, magnetically separated CD4+ naive T cells were stimulated with or without rHMGB1 and/or anti-HMGB1 antibody. BMDCs (bone marrow-derived dendritic cells)-stimulated with or without rHMGB1 and/or anti-HMGB1 antibody were cocultured with CD4+ naive T cells. Our study showed that administration of rHMGB1 aggravated airway inflammation and mucus production, and induced Th2, Th17 polarization in asthmatic mice, and that anti-HMGB1 antibody weakened characteristic features of asthma and blocked the Th2, Th17 inflammatory responses. HMGB1 could directly act on naive T cells to induce differentiation of Th2, Th17 cells in vitro through activating the TLR2, TLR4, RAGE-NF-κB signal pathway in CD4+ naive T cells. HMGB1 could also indirectly promote Th2, Th17 differentiation via activating the TLR2, TLR4, RAGE-NF-κB signal pathway in DCs to mediate their maturation and antigen-presenting ability in vitro.