Mastoparan M Suppressed NLRP3 Inflammasome Activation by Inhibiting MAPK/NF-κB and Oxidative Stress in Gouty Arthritis.

Background: Gouty arthritis is characterized by the accumulation of monosodium urate crystals (MSU) in the synovial joints and surrounding tissues. Mastoparan M (Mast-M) is a biologically active peptide composed of 14 amino acids, extracted from wasp venom. This study aims to assess the impact of Mast-M on in vitro and in vivo gouty arthritis induced by lipolyaccharide (LPS) plus MSU crystal stimulation. Methods: PMA-differentiated THP-1 macrophages were pre-treated with Mast-M or left untreated, followed by stimulation with LPS and MSU crystals. Cell lysates were collected to assess the expression of the NLRP3 inflammasome, inflammatory signaling pathways, and oxidative stress. Furthermore, to evaluate the in vivo anti-inflammatory effect of Mast-M, an experimental acute gouty arthritis mouse model was established through intra-articular injection of MSU crystals. Results: Mast-M treatment demonstrated significant inhibition of the phosphorylation of MAPKs/NF-κB signaling pathways and reduction in oxidative stress expression in LPS and MSU-induced THP-1 macrophages. This resulted in the suppression of downstream NLRP3 inflammasome activation and IL-1ß release. In vivo, Mast-M effectively attenuated the inflammation induced by MSU in mice with gouty arthritis. Specifically, Mast-M reduced swelling in the paws, inhibited the infiltration of neutrophils and macrophages into periarticular tissue, and decreased the activation of the NLRP3 inflammasome and IL-1ß production. Conclusion: Mast-M significantly improves gouty arthritis, and its potential mechanism may be achieved by inhibiting the MAPK/NF-κB pathway and alleviating oxidative stress, thus suppressing the activation of NLRP3 inflammasomes.

AMPD2 plays important roles in regulating hepatic glucose and lipid metabolism.

Dysregulation of hepatic glucose and lipid metabolism can instigate the onset of various metabolic disorders including obesity, dyslipidemia, insulin resistance, type 2 diabetes, and fatty liver disease. Adenosine monophosphate (AMP) deaminase (AMPD), which converts AMP to inosine monophosphate, plays a key role in maintaining adenylate energy charge. AMPD2 is the major isoform present in the liver. However, the mechanistic link between AMPD2 and hepatic glucose and lipid metabolism remains elusive. In this study, we probed into the hepatic glucose and lipid metabolism in AMPD2-deficient (A2-/-) mice. These mice exhibited reduced body weight, fat accumulation, and blood glucose levels, coupled with enhanced insulin sensitivity while maintaining consistent calorie intake and spontaneous motor activity compared with wild type mice. Furthermore, A2-/- mice showed mitigated obesity and hyper-insulinemia induced by high-fat diet (HFD) but elevated levels of the serum triglyceride and cholesterol. The hepatic mRNA levels of several fatty acid and cholesterol metabolism-related genes were altered in A2-/- mice. RNA sequencing unveiled multiple alterations in lipid metabolic pathways due to AMPD2 deficiency. These mice were also more susceptible to fasting or HFD-induced hepatic lipid accumulation. The liver exhibited elevated AMP levels but unaltered AMP/ATP ratio. In addition, AMPD2 deficiency is not associated with the adenosine production. In summary, this study established a link between purine metabolism and hepatic glucose and lipid metabolism via AMPD2, providing novel insights into these metabolic pathways.

Corrigendum: Receptor of advanced glycation end products deficiency attenuates cisplatin-induced acute nephrotoxicity by inhibiting apoptosis, inflammation and restoring fatty acid oxidation.

[This corrects the article DOI: 10.3389/fphar.2022.907133.].

Activation of p62-NRF2 Axis Protects against Doxorubicin-Induced Ferroptosis in Cardiomyocytes: A Novel Role and Molecular Mechanism of Resveratrol.

Doxorubicin (DOX) is a most common anthracycline chemotherapeutic agent; however, its clinical efficacy is limited due to its severe and irreversible cardiotoxicity. Ferroptosis, characterized by iron overload and lipid peroxidation, plays a pivotal role in DOX-induced cardiotoxicity. Resveratrol (RSV) displays cardioprotective and anticancer effects, owing to its antioxidative and anti-inflammatory properties. However, the role and mechanism of RSV in DOX-mediated ferroptosis in cardiomyocytes is unclear. This study showed that DOX decreased cell viability, increased iron accumulation and lipid peroxidation in H9c2 cells; however, these effects were reversed by RSV and ferroptosis inhibitor ferrostatin-1 (Fer-1) pre-treatment. Additionally, RSV significantly increased the cell viability of H9c2 cells treated with ferroptosis inducers Erastin (Era) and RSL3. Mechanistically, RSV inhibited mitochondrial reactive oxygen species (mtROS) overproduction and upregulated the p62-NRF2/HO-1 pathway. RSV-induced NRF2 activation was partially dependent on p62, and the selective inhibition of p62 (using p62-siRNA interference) or NRF2 (using NRF2 specific inhibitor, ML385) significantly abolished the anti-ferroptosis function of RSV. Furthermore, RSV treatment protected mice against DOX-induced cardiotoxicity, including significantly improving left ventricular function, ameliorating myocardial fibrosis and suppressing ferroptosis. Consistent with in vitro results, RSV also upregulated the p62-NRF2/HO-1 expression, which was inhibited by DOX, in the myocardium. Notably, the protective effect of RSV in DOX-mediated ferroptosis was similar to that of Fer-1 in vitro and in vivo. Thus, the p62-NRF2 axis plays a critical role in regulating DOX-induced ferroptosis in cardiomyocytes. RSV as a potent p62 activator has potential as a therapeutic target in preventing DOX-induced cardiotoxicity via ferroptosis modulation.

Hyperuricemia contributes to glucose intolerance of hepatic inflammatory macrophages and impairs the insulin signaling pathway via IRS2-proteasome degradation.

Aim: Numerous reports have demonstrated the key importance of macrophage-elicited metabolic inflammation in insulin resistance (IR). Our previous studies confirmed that hyperuricemia or high uric acid (HUA) treatment induced an IR state in several peripheral tissues to promote the development of type 2 diabetes mellitus (T2DM). However, the effect of HUA on glucose uptake and the insulin sensitivity of macrophages and its mechanism is unclear. Methods: To assess systemic IR, we generated hyperuricemic mice by urate oxidase knockout (UOX-KO). Then, glucose/insulin tolerance, the tissue uptake of 18F-fluorodeoxyglucose, body composition, and energy balance were assessed. Glucose uptake of circulating infiltrated macrophages in the liver was evaluated by glucose transporter type 4 (GLUT-4) staining. Insulin sensitivity and the insulin signaling pathway of macrophages were demonstrated using the 2-NBDG kit, immunoblotting, and immunofluorescence assays. The immunoprecipitation assay and LC-MS analysis were used to determine insulin receptor substrate 2 (IRS2) levels and its interacting protein enrichment under HUA conditions. Results: Compared to WT mice (10 weeks old), serum uric acid levels were higher in UOX-KO mice (WT, 182.3 ± 5.091 µM versus KO, 421.9 ± 45.47 µM). Hyperuricemic mice with metabolic disorders and systemic IR showed inflammatory macrophage recruitment and increased levels of circulating proinflammatory cytokines. HUA inhibited the nuclear translocation of GLUT-4 in hepatic macrophages, restrained insulin-induced glucose uptake and glucose tolerance, and blocked insulin IRS2/PI3K/AKT signaling. Meanwhile, HUA mediated the IRS2 protein degradation pathway and activated AMPK/mTOR in macrophages. LC-MS analysis showed that ubiquitination degradation could be involved in IRS2 and its interacting proteins to contribute to IR under HUA conditions. Conclusion: The data suggest that HUA-induced glucose intolerance in hepatic macrophages contributed to insulin resistance and impaired the insulin signaling pathway via IRS2-proteasome degradation.

Comprehensive analysis reveals a 5-gene signature and immune cell infiltration in Alzheimer's disease with qPCR validation.

Over 50 million people around the world currently are suffering from Alzheimer's disease (AD) without any effective therapy. Neuroinflammation plays a pivotal role in AD, which leads us to probe the profile of immune cell infiltration in AD. Here, we analyzed a microarray dataset (GSE44770) containing 115 AD and 115 control samples to determine biomarkers and immune infiltration characteristics of AD by multiple bioinformatics methods. First, we identified 3,840 DEGs (1892 upregulated and 1948 downregulated) by using the limma package and 2,697 hub genes by constructing a weighted gene correlation network, and they had a total of 2,167 intersecting genes. Second, combining the LASSO logistic regression and SVM-RFE, we obtained five biomarkers (DGKG, MAP3K7IP2, NFKBIE, VIP, and PCCB), which may reveal the key pathogenetic features of AD and serve as diagnostic markers assessed by the ROC curve (AUC = 0.9716) and validation of another AD dataset (GSE33000) (AUC = 0.9388). Third, immune cell infiltration analysis revealed that compared with control samples, plasma cells, CD8 T cells, T follicular helper cells, and activated NK cells infiltrated less in AD; Monocytes, M2 macrophages, and neutrophils infiltrated more in AD. Neutrophils and activated NK cells demonstrated the most significant and negative correlation. Then, Spearman correlation analysis between the five biomarkers and immune infiltrating cells revealed that all of them were significantly associated with plasma cells. Finally, mRNA levels of VIP and PCCB were conformed in a murine AD model. In conclusion, DGKG, MAP3K7IP2, NFKBIE, VIP, and PCCB may be used as diagnostic markers of AD, and the disruption of the delicate immune balance may be a key process in the onset and development of AD.

Receptor of Advanced Glycation End Products Deficiency Attenuates Cisplatin-Induced Acute Nephrotoxicity by Inhibiting Apoptosis, Inflammation and Restoring Fatty Acid Oxidation.

Cisplatin is a widely used and potent anti-neoplastic agent, but severe and inescapable side effects in multiple normal tissues and organs limit its application, especially nephrotoxicity. Molecular mechanisms of cisplatin nephrotoxicity involve mitochondrial damage, oxidative stress, endoplasmic reticulum stress, inflammation, apoptosis, necroptosis, etc. Receptor of advanced glycation end products (RAGE) is a multiligand pattern recognition receptor, engaged in inflammatory signaling and mitochondrial homeostasis. Whether inhibition of RAGE alleviates cisplatin-induced nephropathy has not been investigated. Here, we revealed that RAGE deficiency attenuates cisplatin-induced acute nephrotoxicity, as evidenced by reduced apoptosis, inflammation, lipid accumulation, restored mitochondrial homeostasis and fatty acid oxidation in renal tubular epithelial cells (TECs). In vitro studies showed that, the RAGE-specific inhibitor FPS-ZM1 attenuated the cisplatin-induced decrease of cell viability and fatty acid oxidation in the normal rat renal TEC line NRK-52E cells. Taken together, RAGE knockout mitigated cisplatin-induced acute nephrotoxicity by inhibiting apoptosis, inflammation, and restoring fatty acid oxidation in TECs, suggesting that RAGE inhibition could be a therapeutic option for cisplatin-induced acute nephrotoxicity.