MicroRNA‐27a‐3p suppression of peroxisome proliferator‐activated receptor‐γ contributes to cognitive impairments resulting from sevoflurane treatment

Sevoflurane is the most widely used anaesthetic administered by inhalation. Exposure to sevoflurane in neonatal mice can induce learning deficits and abnormal social behaviours. MicroRNA (miR)‐27a‐3p, a short, non‐coding RNA that functions as a tumour suppressor, is up‐regulated after inhalation of anaesthetic, and peroxisome proliferator‐activated receptor γ (PPAR‐γ) is one of its target genes. The objective of this study was to investigate how the miR‐27a‐3p–PPAR‐γ interaction affects sevoflurane‐induced neurotoxicity. A luciferase reporter assay was employed to identify the interaction between miR‐27a‐3p and PPAR‐γ. Primary hippocampal neuron cultures prepared from embryonic day 0 C57BL/6 mice were treated with miR‐27a‐3p inhibitor or a PPAR‐γ agonist to determine the effect of miR‐27a‐3p and PPAR‐γ on sevoflurane‐induced cellular damage. Cellular damage was assessed by a flow cytometry assay to detect apoptotic cells, immunofluorescence to detect reactive oxygen species, western blotting to detect NADPH oxidase 1/4 and ELISA to measure inflammatory cytokine levels. In vivo experiments were performed using a sevoflurane‐induced anaesthetic mouse model to analyse the effects of miR‐27a‐3p on neurotoxicity by measuring the number of apoptotic neurons using the Terminal‐deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL) method and learning and memory function by employing the Morris water maze test. Our results revealed that PPAR‐γ expression was down‐regulated by miR‐27a‐3p following sevoflurane treatment in hippocampal neurons. Down‐regulation of miR‐27a‐3p expression decreased sevoflurane‐induced hippocampal neuron apoptosis by decreasing inflammation and oxidative stress‐related protein expression through the up‐regulation of PPAR‐γ. In vivo tests further confirmed that inhibition of miR‐27a‐3p expression attenuated sevoflurane‐induced neuronal apoptosis and learning and memory impairment. Our findings suggest that down‐regulation of miR‐27a‐3p expression ameliorated sevoflurane‐induced neurotoxicity and learning and memory impairment through the PPAR‐γ signalling pathway. MicroRNA‐27a‐3p may, therefore, be a potential therapeutic target for preventing or treating sevoflurane‐induced neurotoxicity.

     

α‐Lipoic acid inhibits sevoflurane‐induced neuronal apoptosis through PI3K/Akt signalling pathway

Sevoflurane is a widely used anaesthetic agent, including in anaesthesia of children and infants. Recent studies indicated that the general anaesthesia might cause the cell apoptosis in the brain. This issue raises the concerns about the neuronal toxicity induced by the application of anaesthetic agents, especially in the infants and young children. In this study, we used Morris water maze, western blotting and immunohistochemistry to elucidate the role of α‐lipoic acid in the inhibition of neuronal apoptosis. We found that sevoflurane led to the long‐term cognitive impairment in the young rats. This adverse effect may be caused by the neuronal death in the hippocampal region, mediated through PI3K/Akt signalling pathway. We also showed that α‐lipoic acid offset the effect of sevoflurane on the neuronal apoptosis and cognitive dysfunction. This study elucidated the potential clinical role of α‐lipoic acid, providing a promising way in the prevention and treatment of long‐term cognitive impairment induced by sevoflurane general anesthesia. Copyright © 2016 John Wiley & Sons, Ltd.     

Sodium hydrosulphide restores tumour necrosis factor‐α‐induced mitochondrial dysfunction and metabolic dysregulation in HL‐1 cells

Tumour necrosis factor (TNF)‐α induces cardiac metabolic disorder and mitochondrial dysfunction. Hydrogen sulphide (H₂S) contains anti‐inflammatory and biological effects in cardiomyocytes. This study investigated whether H₂S modulates TNF‐α‐dysregulated mitochondrial function and metabolism in cardiomyocytes. HL‐1 cells were incubated with TNF‐α (25 ng/mL) with or without sodium hydrosulphide (NaHS, 0.1 mmol/L) for 24 hours. Cardiac peroxisome proliferator‐activated receptor (PPAR) isoforms, pro‐inflammatory cytokines, receptor for advanced glycation end products (RAGE) and fatty acid metabolism were evaluated through Western blotting. The mitochondrial oxygen consumption rate and adenosine triphosphate (ATP) production were investigated using Seahorse XF24 extracellular flux analyzer and bioluminescence assay. Fluorescence intensity using 2′, 7′‐dichlorodihydrofluorescein diacetate was used to evaluate mitochondrial oxidative stress. NaHS attenuated the impaired basal and maximal respiration, ATP production and ATP synthesis and enhanced mitochondrial oxidative stress in TNF‐α‐treated HL‐1 cells. TNF‐α‐treated HL‐1 cells exhibited lower expression of PPAR‐α, PPAR‐δ, phosphorylated 5′ adenosine monophosphate‐activated protein kinase‐α2, phosphorylated acetyl CoA carboxylase, carnitine palmitoyltransferase‐1, PPAR‐γ coactivator 1‐α and diacylglycerol acyltransferase 1 protein, but higher expression of PPAR‐γ, interleukin‐6 and RAGE protein than control or combined NaHS and TNF‐α‐treated HL‐1 cells. NaHS modulates the effects of TNF‐α on mitochondria and the cardiometabolic system, suggesting its therapeutic potential for inflammation‐induced cardiac dysfunction.     

Inhibition of TIM‐4 protects against cerebral ischaemia‐reperfusion injury

TIM‐4 plays an important role in ischaemia‐reperfusion injury of liver and kidney; however, the effects of TIM‐4 on cerebral ischaemia‐reperfusion injury (IRI) are unknown. The purpose of the present study was to investigate the potential role of TIM‐4 in experimental brain ischaemia‐reperfusion injury. In this study, cerebral ischaemia reperfusion was induced by transient middle cerebral artery occlusion (MCAO) for 1 hour in C57/BL6 mice. The TIM‐4 expression was detected in vivo or vitro by real‐time quantitative polymerase chain reaction, Western blot and flow cytometric analysis. In vivo, the administration of anti‐TIM‐4 antibodies significantly suppressed apoptosis, inhibited inflammatory cells and enhanced anti‐inflammatory responses. In vitro, activated microglia exhibited reduced cellular proliferation and induced IRI injury when co‐cultured with neurons; these effects were inhibited by anti‐TIM‐4 antibody treatment. Similarly, microglia transfected with TIM‐4 siRNA and stimulated by LPS + IFN‐γ alleviated the TIM‐4‐mediated damage to neurons. Collectively, our data indicate that the inhibition of TIM‐4 can improve the inflammatory response and exerts a protective effect in cerebral ischaemia‐reperfusion injury.     

Anti‐arthritis activity of cationic materials

Cationic materials exhibit remarkable anti‐inflammatory activity in experimental arthritis models. Our aim was to confirm this character of cationic materials and investigate its possible mechanism. Adjuvant‐induced arthritis (AIA) models were used to test cationic materials for their anti‐inflammatory activity. Cationic dextran (C‐dextran) with different cationic degrees was used to investigate the influence of the cationic elements of materials on their anti‐inflammatory ability. Peritoneal macrophages and spleen cells were used to test the expression of cytokines stimulated by cationic materials. Interferon (IFN)‐γ receptor‐deficient mice and macrophage‐depleted rats were used to examine the possible mechanisms of the anti‐inflammatory activity of cationic materials. In AIA models, different cationic materials shared similar anti‐inflammatory characters. The anti‐inflammatory activity of C‐dextran increased with as the cationic degree increased. Cationic materials stimulated interleukin (IL)‐12 expression in peritoneal macrophages, and strong stimulation of IFN‐γ secretion was subsequently observed in spleen cells. In vivo experiments revealed that circulating IL‐12 and IFN‐γ were enhanced by the cationic materials. Using IFN‐γ receptor knockout mice and macrophage‐depleted rats, we found that IFN‐γ and macrophages played key roles in the anti‐inflammatory activity of the materials towards cells. We also found that neutrophil infiltration at inflammatory sites was reduced when AIA animals were treated with C‐dextran. We propose that cationic signals act through an unknown receptor on macrophages to induce IL‐12 secretion, and that IL‐12 promotes the expression of IFN‐γ by natural killer cells (or T cells). The resulting elevated systemic levels of IFN‐γ inhibit arthritis development by preventing neutrophil recruitment to inflammatory sites.     

Spinal cord injury causes bone loss through peroxisome proliferator‐activated receptor‐γ and Wnt signalling

It has long been recognized that spinal cord injury (SCI) leads to a loss of bone mineral. However, the mechanisms of bone loss after SCI remain poorly understood. The aim of this study was to investigate whether SCI causes a shift in skeletal balance between osteoblastogenesis and adipogenesis. Eighty male Sprague‐Dawley rats at 6 weeks of age were randomly divided into two groups: sham‐operated (SHAM) group and SCI group. The rats were killed after 3 weeks, 3 months and 6 months, and their femora, tibiae and humeri were collected for mesenchymal stem cells (MSCs) culture, bone mineral density (BMD) measurement, RNA analysis and Western Blot analysis. Osteogenic and adipogenic differentiation potential of MSCs from SCI rats and SHAM rats was evaluated. We found increased marrow adiposity in sublesional tibiae of SCI rats. SCI caused increased peroxisome proliferator‐activated receptor‐γ (PPARγ) expression and diminished Wnt signalling in sublesional tibiae. Interestingly, in MSCs from SCI rats treated with the PPARγ inhibitor GW9662, the ratios of RANKL to OPG expression were significantly decreased. On the contrary, in MSCs from SCI rats treated with the PPARγ ligand troglitazone, the ratios of RANKL to OPG expression in SCI rats were significantly increased. High expression of PPARγ may lead to increased bone resorption through the RANKL/OPG axis after SCI. In addition, high expression also results in the suppression of osteogenesis and enhancement of adipogenesis in SCI rats. SCI causes a shift in skeletal balance between osteoblastogenesis and adipogenesis, thus leading to bone loss after SCI.     

Hesperidin regresses cardiac hypertrophy by virtue of PPAR‐γ agonistic,anti‐inflammatory,antiapoptotic, and antioxidant properties

Hesperidin (HES), a flavanone glycoside, predominant in citrus fruits, has an agonistic activity on peroxisome proliferator‐activated receptor gamma (PPAR‐γ). PPAR‐γ is an inhibitor of cardiac hypertrophy (CH) signaling pathways. In this study, we investigated the cardioprotective effect of HES in isoproterenol (ISO)‐induced CH through PPAR‐γ agonistic activity. For this, male albino Wistar rats were divided into six groups (n = 6), that is, normal, ISO‐control, HES treatment group (200 mg kg^?1; p.o.), HES per se (200 mg kg^?1; p.o.), enalapril treatment group (30 mg kg^?1; p.o.), and combination group (HES 200 mg kg^?1; p.o.+enalapril 30 mg kg^?1; p.o.). ISO (3 mg kg^?1; s.c.) was administered to all groups except normal and per se to induce CH. HES or enalapril treatment of 28 days significantly attenuated pathological changes, improved cardiac hemodynamics, suppressed oxidative stress, and apoptosis along with an increased PPAR‐γ expression. The combination of enalapril with HES exhibited an effect similar to that of HES or enalapril alone on all the aforementioned parameters. Therefore, HES may be further evaluated as a promising molecule for the alleviation of CH.     

Rosiglitazone via PPARγ‐dependent suppression of oxidative stress attenuates endothelial dysfunction in rats fed homocysteine thiolactone

To explore whether rosiglitazone (RSG), a selective peroxisome proliferator‐activated receptor γ (PPARγ) agonist, exerts beneficial effects on endothelial dysfunction induced by homocysteine thiolactone (HTL) and to investigate the potential mechanisms. Incubation of cultured human umbilical vein endothelial cells with HTL (1 mM) for 24 hrs significantly reduced cell viabilities assayed by 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide, as well as enhanced productions of reactive oxygen species, activation of nuclear factor kappa B, and increased intercellular cell adhesion molecule‐1 secretion. Pre‐treatment of cells with RSG (0.001–0.1 mM), pyrollidine dithiocarbamate (PDTC, 0.1 mM) or apocynin (0.1 mM) for 1 hr reversed these effects induced by HTL. Furthermore, co‐incubation with GW9662 (0.01 mM) abolished the protective effects of RSG on HTL‐treated cells. In ex vivo experiments, exposure of isolated aortic rings from. rats to HTL (1 mM) for 1 hr dramatically impaired acetylcholine‐induced endothelium‐dependent relaxation, reduced release of nitric oxide and activity of superoxide dismutase, and increased malondialdehyde content in aortic tissues. Preincubation of aortic rings with RSG (0.1, 0.3, 1 mM), PDTC or apocynin normalized the disorders induced by HTL. In vivo analysis indicated that administration of RSG (20 mg/kg/d) remarkably suppressed oxidative stress and prevented endothelial dysfunction in rats fed HTL (50 mg/kg/d) for 8 weeks. RSG improves endothelial functions in rats fed HTL, which is related to PPARγ‐dependent suppression of oxidative stress.     

Effect of an acute moderate‐exercise session on metabolic and inflammatory profile of PPAR‐α knockout mice

Peroxisome proliferator‐activated receptors (PPARs) play a major role in metabolism and inflammatory control. Exercise can modulate PPAR expression in skeletal muscle, adipose tissue, and macrophages. Little is known about the effects of PPAR‐α in metabolic profile and cytokine secretion after acute exercise in macrophages. In this context, the aim of this study was to understand the influence of PPAR‐α on exercise‐mediated immune metabolic parameters in peritoneal macrophages. Mice C57BL/6 (WT) and PPAR‐α knockout (KO) were examined in non‐exercising control (n = 4) or 24 hours after acute moderate exercise (n = 8). Metabolic parameters (glucose, non‐esterified fatty acids, total cholesterol [TC], and triacylglycerol [TG]) were assessed in serum. Cytokine concentrations (IL‐1β, IL‐6, IL‐10, TNF‐α, and MCP‐1) were measured from peritoneal macrophages cultured or not with LPS (2.5 μg/mL) and Rosiglitazone (1 μM). Exercised KO mice exhibited low glucose concentration and higher TC and TG in serum. At baseline, no difference in cytokine production between the genotypes was observed. However, IL‐1β was significantly higher in KO mice after LPS stimulus. IL‐6 and IL‐1β had increased concentrations in KO compared with WT, even after exercise. MCP‐1 was not restored in exercised KO LPS group. Rosiglitazone was not able to reduce proinflammatory cytokine production in KO mice at baseline level or associated with exercise. Acute exercise did not alter mRNA expression in WT mice. Conclusion: PPAR‐α seems to be needed for metabolic glucose homeostasis and anti‐inflammatory effect of acute exercise. Its absence may induce over‐expression of pro‐inflammatory cytokines in LPS stimulus. Moreover, moderate exercise or PPAR‐γ agonist did not reverse this response.     

Seizure‐induced impairment in neuronal ketogenesis: Role of zinc‐α2‐glycoprotein in mitochondria

Ketone bodies (KBs) were known to suppress seizure. Untraditionally, neurons were recently reported to utilize fatty acids and produce KBs, but the effect of seizure on neuronal ketogenesis has not been researched. Zinc‐α2‐glycoprotein (ZAG) was reported to suppress seizure via unclear mechanism. Interestingly, ZAG was involved in fatty acid β‐oxidation and thus may exert anti‐epileptic effect by promoting ketogenesis. However, this promotive effect of ZAG on neuronal ketogenesis has not been clarified. In this study, we performed immunoprecipitation and mass spectrometry to identify potential interaction partners with ZAG. The mechanisms of how ZAG translocated into mitochondria were determined by quantitative coimmunoprecipitation after treatment with apoptozole, a heat shock cognate protein 70 (HSC70) inhibitor. ZAG level was modulated by lentivirus in neurons or adeno‐associated virus in rat brains. Seizure models were induced by magnesium (Mg²⁺)‐free artificial cerebrospinal fluid in neurons or intraperitoneal injection of pentylenetetrazole kindling in rats. Ketogenesis was determined by cyclic thio‐NADH method in supernatant of neurons or brain homogenate. The effect of peroxisome proliferator–activated receptor γ (PPARγ) on ZAG expression was examined by Western blot, quantitative real‐time polymerase chain reaction (qRT‐PCR) and chromatin immunoprecipitation qRT‐PCR. We found that seizure induced ketogenesis deficiency via a ZAG‐dependent mechanism. ZAG entered mitochondria through a HSC70‐dependent mechanism, promoted ketogenesis by binding to four β‐subunits of long‐chain L‐3‐hydroxyacyl‐CoA dehydrogenase (HADHB) and alleviated ketogenesis impairment in a neuronal seizure model and pentylenetetrazole‐kindled epileptic rats. Additionally, PPARγ activation up‐regulated ZAG expression by binding to promoter region of AZGP1 gene and promoted ketogenesis through a ZAG‐dependent mechanism.     

Minocycline attenuates post‐operative cognitive impairment in aged mice by inhibiting microglia activation

Although it is known that isoflurane exposure or surgery leads to post‐operative cognitive dysfunction in aged rodents, there are few clinical interventions and treatments available to prevent this disorder. Minocycline (MINO) produces neuroprotection from several neurodegenerative diseases and various experimental animal models. Therefore, we set out to investigate the effects of MINO pre‐treatment on isoflurane or surgery induced cognitive impairment in aged mice by assessing the hippocampal‐dependent spatial memory performance using the Morris water maze task. Hippocampal tissues were isolated from mice and evaluated by Western blot analysis, immunofluorescence procedures and protein array system. Our results elucidate that MINO down‐regulated the isoflurane‐induced and surgery‐induced enhancement in the protein levels of pro‐inflammatory cytokine tumour necrosis factor alpha, interleukin (IL)‐1β, interferon‐γ and microglia marker Iba‐1, and up‐regulated protein levels of the anti‐inflammatory cytokine IL‐4 and IL‐10. These findings suggest that pre‐treatment with MINO attenuated isoflurane or surgery induced cognitive impairment by inhibiting the overactivation of microglia in aged mice.     

LIGHT/IFN‐γ triggers β cells apoptosis via NF‐κB/Bcl2‐dependent mitochondrial pathway

LIGHT recruits and activates naive T cells in the islets at the onset of diabetes. IFN‐γ secreted by activated T lymphocytes is involved in beta cell apoptosis. However, whether LIGHT sensitizes IFNγ‐induced beta cells destruction remains unclear. In this study, we used the murine beta cell line MIN6 and primary islet cells as models for investigating the underlying cellular mechanisms involved in LIGHT/IFNγ – induced pancreatic beta cell destruction. LIGHT and IFN‐γ synergistically reduced MIN6 and primary islet cells viability; decreased cell viability was due to apoptosis, as demonstrated by a significant increase in Annexin V⁺ cell percentage, detected by flow cytometry. In addition to marked increases in cytochrome c release and NF‐κB activation, the combination of LIGHT and IFN‐γ caused an obvious decrease in expression of the anti‐apoptotic proteins Bcl‐2 and Bcl‐xL, but an increase in expression of the pro‐apoptotic proteins Bak and Bax in MIN6 cells. Accordingly, LIGHT deficiency led to a decrease in NF‐κB activation and Bak expression, and peri‐insulitis in non‐obese diabetes mice. Inhibition of NF‐κB activation with the specific NF‐κB inhibitor, PDTC (pyrrolidine dithiocarbamate), reversed Bcl‐xL down‐regulation and Bax up‐regulation, and led to a significant increase in LIGHT‐ and IFN‐γ‐treated cell viability. Moreover, cleaved caspase‐9, ‐3, and PARP (poly (ADP‐ribose) polymerase) were observed after LIGHT and IFN‐γ treatment. Pretreatment with caspase inhibitors remarkably attenuated LIGHT‐ and IFNγ‐induced cell apoptosis. Taken together, our results indicate that LIGHT signalling pathway combined with IFN‐γ induces beta cells apoptosis via an NF‐κB/Bcl2‐dependent mitochondrial pathway.     

Modulatory effects of interferon‐γ and interleukin‐4 on cellular immune responses against Hypoderma lineatum antigens

This study investigates the in vitro modulatory effects of interferon‐γ (IFN‐γ) and interleukin‐4 (IL‐4) on both proliferative bovine T cell responses and IL‐10 production induced by different antigens [crude larval extract and the purified fractions hypodermin A, B and C (HyA, HyB, HyC)] obtained from first instars of Hypoderma lineatum (Diptera: Oestridae), alone or in the presence of the mitogen concanavalin A. Incubation with the different parasitic antigens resulted in significant inhibition of T cell proliferation and IL‐10 production, which, in general, did not revert after the addition of IFN‐γ and IL‐4. In the absence of antigens, IL‐4 induced significant inhibition of mitogen‐induced T cell responses. Exogenous IFN‐γ exhibited an inhibitory effect on cell proliferation in the presence of the purified fractions HyB and HyC. These in vitro data suggest that far from neutralizing the effects of larval antigens, the addition of IFN‐γ potentiates their anti‐proliferative activity; by contrast, IL‐4 had no consistent effects on proliferative responses to Hypoderma. IL‐4 provoked an increment of IL‐10 levels in supernatants of HyB‐stimulated cells. In conclusion, exogenous IFN‐γ and IL‐4 were unable to counteract the suppressor effects of H. lineatum antigens.     

Eliciting α7‐nAChR exerts cardioprotective effects on ischemic cardiomyopathy via activation of AMPK signalling

Our previous studies have reported that agonist of α7 nicotinic acetylcholine receptors prevented electrophysiological dysfunction of rats with ischaemic cardiomyopathy (ICM) by eliciting the cholinergic anti‐inflammatory pathway (CAP). Adenosine monophosphate‐activated protein kinase (AMPK) signalling is widely recognized exerting cardioprotective effect in various cardiomyopathy. Here, we aimed to investigate whether the protective effects of the CAP are associated with AMPK signalling in ICM. In vivo, coronary artery of rats was ligated for 4 weeks to induce the ICM and then treated with PNU‐282987 (CAP agonist) and BML‐275 dihydrochloride (AMPK antagonist) for 4 weeks. In vitro, primary macrophages harvested from rats were induced inflammation by Lipopolysaccharide (LPS) treatment and then treated with PNU‐282987 and BML‐275 dihydrochloride. In vivo, exciting CAP by PUN‐282987 elicited an activation of AMPK signalling, alleviated ventricular remodeling, modified the cardiac electrophysiological function, reduced the cardiac expression of collagens and inflammatory cytokines and maintained the integrity of ultrastructure in the ischemic heart. However, the benefits of CAP excitation were blunted by AMPK signaling antagonization. In vitro, excitation of the CAP was observed inhibiting the nuclear transfer of NF‐κB p65 of macrophages and promoting the transformation of Ly‐6C^high macrophages into Ly‐6C^low macrophages. However, inhibiting AMPK signalling by BML‐275 dihydrochloride reversed the CAP effect on LPS‐treated macrophages. Finally, our findings suggest that eliciting the CAP modulates the inflammatory response in ICM through regulating AMPK signalling.     

MeCP2‐421‐mediated RPE epithelial‐mesenchymal transition and its relevance to the pathogenesis of proliferative vitreoretinopathy

Proliferative vitreoretinopathy (PVR) is a blinding eye disease. Epithelial‐mesenchymal transition (EMT) of RPE cells plays an important role in the pathogenesis of PVR. In the current study, we sought to investigate the role of the methyl‐CpG‐binding protein 2 (MeCP2), especially P‐MeCP2‐421 in the pathogenesis of PVR. The expressions of P‐MeCP2‐421, P‐MeCP2‐80, PPAR‐γ and the double labelling of P‐MeCP2‐421 with α‐SMA, cytokeratin, TGF‐β and PPAR‐γ in human PVR membranes were analysed by immunohistochemistry. The effect of knocking down MeCP2 using siRNA on the expressions of α‐SMA, phospho‐Smad2/3, collagen I, fibronectin and PPAR‐γ; the expression of α‐SMA stimulated by recombinant MeCP2 in ARPE‐19; and the effect of TGF‐β and 5‐AZA treatment on PPAR‐γ expression were analysed by Western blot. Chromatin immunoprecipitation was used to determine the binding of MeCP2 to TGF‐β. Our results showed that P‐MeCP2‐421 was highly expressed in PVR membranes and was double labelled with α‐SMA, cytokeratin and TGF‐β, knocking down MeCP2 inhibited the activation of Smad2/3 and the expression of collagen I and fibronectin induced by TGF‐β. TGF‐β inhibited the expression of PPAR‐γ, silence of MeCP2 by siRNA or using MeCP2 inhibitor (5‐AZA) increased the expression of PPAR‐γ. α‐SMA was up‐regulated by the treatment of recombinant MeCP2. Importantly, we found that MeCP2 bound to TGF‐β as demonstrated by Chip assay. The results suggest that MeCP2 especially P‐MeCP2‐421 may play a significant role in the pathogenesis of PVR and targeting MeCP2 may be a potential therapeutic approach for the treatment of PVR.     

Antagonizing peroxisome proliferator‐activated receptor γ facilitates M1‐to‐M2 shift of microglia by enhancing autophagy via the LKB1–AMPK signaling pathway

Microglia‐mediated neuroinflammation plays a dual role in various brain diseases due to distinct microglial phenotypes, including deleterious M1 and neuroprotective M2. There is growing evidence that the peroxisome proliferator‐activated receptor γ (PPARγ) agonist rosiglitazone prevents lipopolysaccharide (LPS)‐induced microglial activation. Here, we observed that antagonizing PPARγ promoted LPS‐stimulated changes in polarization from the M1 to the M2 phenotype in primary microglia. PPARγ antagonist T0070907 increased the expression of M2 markers, including CD206, IL‐4, IGF‐1, TGF‐β1, TGF‐β2, TGF‐β3, G‐CSF, and GM‐CSF, and reduced the expression of M1 markers, such as CD86, Cox‐2, iNOS, IL‐1β, IL‐6, TNF‐α, IFN‐γ, and CCL2, thereby inhibiting NFκB–IKKβ activation. Moreover, antagonizing PPARγ promoted microglial autophagy, as indicated by the downregulation of P62 and the upregulation of Beclin1, Atg5, and LC3‐II/LC3‐I, thereby enhancing the formation of autophagosomes and their degradation by lysosomes in microglia. Furthermore, we found that an increase in LKB1–STRAD–MO25 complex formation enhances autophagy. The LKB1 inhibitor radicicol or knocking down LKB1 prevented autophagy improvement and the M1‐to‐M2 phenotype shift by T0070907. Simultaneously, we found that knocking down PPARγ in BV2 microglial cells also activated LKB1–AMPK signaling and inhibited NFκB–IKKβ activation, which are similar to the effects of antagonizing PPARγ. Taken together, our findings demonstrate that antagonizing PPARγ promotes the M1‐to‐M2 phenotypic shift in LPS‐induced microglia, which might be due to improved autophagy via the activation of the LKB1–AMPK signaling pathway.