Liraglutide attenuates lipopolysaccharide-induced acute lung injury in mice

DPP-4 inhibition by linagliptin prevents cardiac dysfunction and inflammation by targeting the Nlrp3/ASC inflammasome

We compared the effects of linagliptin (Lina, a DPP4 inhibitor) and GLP-1 receptor activation by exenatide followed by exendin-4 in an infusion pump (EX) on infarct size (IS), post-infarction activation of the inflammasome and remodeling in wild-type (WT) and db/db diabetic mice. Mice underwent 30 min ischemia followed by 24 h reperfusion. IS was assessed by TTC. Additional mice underwent permanent coronary artery occlusion. Echocardiography was performed 2w after infarction. Activation of the inflammasome in the border zone of the infarction was assessed by rt-PCR and ELISA 2w after reperfusion. Further in vitro experiments were done using primary human cardiofibroblasts and cardiomyocytes exposed to simulated ischemia-reoxygenation. Lina and EX limited IS in both the WT and the db/db mice. Lina and EX equally improved ejection fraction in both the WT and the db/db mice. mRNA levels of ASC, NALP3, IL-1β, IL-6, Collagen-1, and Collagen-3 were higher in the db/db mice than in the WT mice. Infarction increased these levels in the WT and db/db mice. Lina more than EX attenuated the increase in ASC, NALP3, IL-1β, IL-6, Collagen-1 and Collagen-3, TNFα and IL-1β, and decreased apoptosis, especially in the db/db mice. In vitro experiments showed that Lina, but not EX, attenuated the increase in TLR4 expression, an effect that was dependent on p38 activation with downstream upregulation of Let-7i and miR-146b levels. Lina and EX had similar effects on IS and post-infarction function, but Lina attenuated the activation of the inflammasome and the upregulation of collagen-1 and collagen-3 more than direct GLP-1 receptor activation. This effect depends on p38 activation with downstream upregulation of miR-146b levels that suppresses TLR4 expression.

Alkannin attenuates lipopolysaccharide-induced lung injury in mice via Rho/ROCK/NF-κB pathway

We investigated the effects and associated mechanism of alkannin (AL) on lipopolysaccharide (LPS)-induced acute lung injury in a mouse model. Pretreatment with AL in vivo significantly reduced the lung wet/dry weight ratio and inhibited lung myeloperoxidase activity and malondialdehyde content, while increasing superoxide dismutase activity. Hematoxylin and eosin staining demonstrated that AL attenuated lung histopathological changes. In addition, AL-inhibited overproduction of proinflammatory cytokines in bronchoalveolar lavage fluid and lung tissues in LPS-injured mice and LPS-exposed A549 cells. Further analysis showed that AL-inhibited induction of the Rho/ROCK/NF-κB pathway via LPS-induced inflammation in mice and A549 cells. Fasudil, a selective ROCK inhibitor, showed similar effects. Overall, the findings indicate that AL suppresses the expression of messenger RNAs and proteins associated with Rho/ROCK/NF-κB signaling to effectively ameliorate lung injury.

Exenatide Delays the Progression of Nonalcoholic Fatty Liver Disease in C57BL/6 Mice, Which May Involve Inhibition of the NLRP3 Inflammasome through the Mitophagy Pathway

Objective

This study is aimed at investigating whether exenatide (Exe) delays the progression of nonalcoholic fatty liver disease (NAFLD) in C57BL/6 mice by targeting the NLRP3 inflammasome through the autophagy/mitophagy pathway.

Methods

Thirty male C57BL/6 mice were randomly divided into three groups: control group (n = 10), model group (n = 10), and Exe (exenatide) group (n = 10). Mouse models of NAFLD and diabetes were established using a high-fat diet and streptozocin.

Results

The levels of fasting blood glucose (FBG), total cholesterol (TC), and triglyceride (TG) in the serum were significantly reduced after Exe treatment. The body weight, liver weight/body weight, and number of lipid droplets in the liver significantly decreased in Exe-treated mice. Treatment with Exe markedly reduced the levels of liver lipids, malondialdehyde (MDA), and alanine aminotransferase (ALT) in serum and livers. The number of autophagosomes increased significantly in the Exe group. The expression of LC3A/B-II/I, Beclin-1, Parkin, and BNIP3L increased significantly, whereas NLRP3 and IL-1β proteins were suppressed after Exe treatment.

Conclusion

We successfully established a mouse model of NAFLD and diabetes. Exe may reduce oxidative stress injury and inhibit the NLRP3 inflammasome by enhancing the autophagy/mitophagy pathway in liver, which has a protective effect on the liver in NAFLD and diabetes in C57BL/6 mice.

Liraglutide attenuates NLRP3 inflammasome-dependent pyroptosis via regulating SIRT1/NOX4/ROS pathway in H9c2 cells

The glucagon-like peptide-1 analog liraglutide has been proved to exert cardioprotective role via activating prosurvival pathways and suppressing inflammation. The activation of NLRP3 inflammasome plays an important role in ischemic injury. The effect of liraglutide on NLRP3 inflammasome-dependent pyroptosis remains unclear. In this study, we established a double stimulation model with TNF-α and hypoxia to mimic ischemic environment and to induce NLRP3 inflammasome activation in H9c2 cardiomyoblasts. Pretreatment with 100 nM liraglutide could efficiently inhibit TNF-α and hypoxia-induced inflammasome activation, as evidenced by the decreased expression of NLRP3, caspase-1 p20 and Gasdermin D N-terminal fragment. Meanwhile, the pyroptosis was also demonstrated to be suppressed, indicated by the increased cell viability and decreased lactate dehydrogenase release in the cells. Mechanistically, liraglutide reversed the level of SIRT1 and the selective SIRT1 inhibitor EX 527 significantly abolished the anti-pyroptosis role of liraglutide. Furthermore, liraglutide diminished the levels of ROS generation and NOX4 expression, which could also be blocked by EX 527. Our results uncovered the anti-pyroptosis role of liraglutide in TNF-α and hypoxia-stimulated H9c2 cells, which was associated with SIRT1/NOX4/ROS pathway.

Anti-inflammatory Role of Pilose Antler Peptide in LPS-Induced Lung Injury

The present study was designed to investigate the effects of pilose antler peptide (PAP) on lipopolysaccharide (LPS)-induced lung injury. BalB/c mice intraperitoneally received PAP (10 and 20 mg/kg) or dexamethasone (2 mg/kg) 1 h prior to intratracheal instillation of LPS. PAP significantly decreased lung wet-to-dry weight (W/D) ratio and lung myeloperoxidase (MPO) activity and restored LPS-induced lung histopathological changes. PAP also increased super oxide dismutase (SOD) level and inhibited malondialdehyde (MDA) content and levels of pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in bronchoalveolar lavage fluid (BALF) in LPS-stimulated mice. Furthermore, we demonstrated that PAP inhibited Rho/NF-κB pathway in LPS-induced mice. Our experimental results indicated that the protective mechanism of PAP might be attributed partly to the inhibition of Rho/NF-κB pathway.

Verapamil Ameliorates Hepatic Metaflammation by Inhibiting Thioredoxin-Interacting Protein/NLRP3 Pathways

Activation of thioredoxin-interacting protein (TXNIP)/nod-like receptor protein 3 (NLRP3) inflammasome plays a critical role in pathogenesis of non-alcoholic fatty liver disease. This study investigated the protective effects of verapamil on hepatic metaflammation in a rodent model of high-fat (HF) diet-induced obesity (DIO). DIO was induced in a subset of mice provided with HF diet (45% kcal fat). After 10 weeks of HF diet, verapamil was administered by intraperitoneal injection. The experimental groups included the following: (1) normal diet group, (2) normal diet + treatment with verapamil (VER) group, (3) HF control group, (4) HF+VER (25 mg/kg/day) group. After 1 week of each treatment, blood and liver tissues were collected, and glucose control, serum triglyceride (TG) level, inflammation, and TXNIP/NLRP3 inflammasome were analyzed. Verapamil administration caused no alteration in food intake. HF diet impaired glucose control and increased body weight and serum TG levels. Hepatic inflammation was aggravated in HF-fed mice, as demonstrated by increased levels of pro-inflammatory markers interleukin-1β (IL-1β) and IL-18 in the liver. On the other hand, verapamil administration significantly improved glucose control, body weight, and serum TG levels. Verapamil treatment also reduced pro-inflammatory marker levels. These improvements were accompanied by alterations in activation of TXNIP/NLRP3 inflammasome. The observed results demonstrate that verapamil ameliorates hepatic metaflammation by inhibiting TXNIP/NLRP3 pathways.

Hyperoxia treatment of TREK-1/TREK-2/TRAAK-deficient mice is associated with a reduction in surfactant proteins

We previously proposed a role for the two-pore domain potassium (K2P) channel TREK-1 in hyperoxia (HO)-induced lung injury. To determine whether redundancy among the three TREK isoforms (TREK-1, TREK-2, and TRAAK) could protect from HO-induced injury, we now examined the effect of deletion of all three TREK isoforms in a clinically relevant scenario of prolonged HO exposure and mechanical ventilation (MV). We exposed WT and TREK-1/TREK-2/TRAAK-deficient [triple knockout (KO)] mice to either room air, 72-h HO, MV [high and low tidal volume (TV)], or a combination of HO + MV and measured quasistatic lung compliance, bronchoalveolar lavage (BAL) protein concentration, histologic lung injury scores (LIS), cellular apoptosis, and cytokine levels. We determined surfactant gene and protein expression and attempted to prevent HO-induced lung injury by prophylactically administering an exogenous surfactant (Curosurf). HO treatment increased lung injury in triple KO but not WT mice, including an elevated LIS, BAL protein concentration, and markers of apoptosis, decreased lung compliance, and a more proinflammatory cytokine phenotype. MV alone had no effect on lung injury markers. Exposure to HO + MV (low TV) further decreased lung compliance in triple KO but not WT mice, and HO + MV (high TV) was lethal for triple KO mice. In triple KO mice, the HO-induced lung injury was associated with decreased surfactant protein (SP) A and SPC but not SPB and SPD expression. However, these changes could not be explained by alterations in the transcription factors nuclear factor-1 (NF-1), NKX2.1/thyroid transcription factor-1 (TTF-1) or c-jun, or lamellar body levels. Prophylactic Curosurf administration did not improve lung injury scores or compliance in triple KO mice.