益母草碱抑制NLRP3炎症小体过度激活调控巨噬细胞M1/M2表型分化

目的 研究益母草碱对脂多糖(LPS)诱导小鼠腹腔巨噬细胞免疫应答影响及相关机制.方法 分离小鼠腹腔巨噬细胞,用脂多糖和益母草碱预处理24 h,MMT法检测巨噬细胞活性;Griess法检测NO释放量;ELISA法检测IL-1β、IL-18、IL-6、TNF-α的释放量;RT-PCR法检测NLRP3、ASC、caspase...     

Dexamethasone alleviate allergic airway inflammation in mice by inhibiting the activation of NLRP3 inflammasome

Dexamethasone (DEX) is the mainstay treatment for asthma, which is a common chronic airway inflammation disease. However, the mechanism of DEX resolute symptoms of asthma is not completely clear. Here, we aimed to analyze the effect of DEX on airway inflammation in OVA-induced mice and whether this effect is related to the inhibition of the activation of NLRP3 inflammasome. Female (C57BL/6) mice were used to establish the allergic airway inflammation model by inhalation OVA. The number of inflammatory cells in the bronchi alveolar lavage fluid (BALF) was counted by Swiss-Giemsa staining, and the contents of IL-1β, IL-18, IL-5 and IL-17 were detected by ELISA. The degree of inflammatory cells infiltration and mucous cells proliferation in lung tissue were separately observed by H&E and PAS staining. The proteins expression of NLRP3, pro-caspase-1, caspase-1, IL-1β, IL-6 and IL-17 in lung tissue were detected by Western blotting. We found that DEX significantly inhibited OVA-induced inflammatory cells infiltration, airway mucus secretion and goblet cell proliferation in mice. The total and classified numbers of inflammatory cells and the levels of IL-1β, IL-18, IL-5 and IL-17 in the BALF of the experimental group were significantly lower than those of the model group after DEX treatment. DEX also significantly inhibited the activity of NLRP3 inflammasome and reduced the protein contents of Pro-Caspase-1, Caspase-1, Capase-1/Pro-Caspase-1, IL-1β, IL-6 and IL-17 in lung tissues. Our study suggested that DEX alleviates allergic airway inflammation by inhibiting the activity of NLRP3 inflammasome and the levels of IL-1β and IL-18.     

NLRP3炎性小体与糖尿病心肌病的发生发展

糖尿病心肌病(DCM)是糖尿病特异性心脏并发症,可独立于冠状动脉疾病、高血压或瓣膜性心脏病发生。目前公认的发病机制包括高血糖、蛋白非酶糖基化、氧化应激、钙离子转运异常等,其中炎症是导致左心室舒张功能障碍的独立因素。NLRP3是最常见的炎性小体,可诱导分泌IL-1β、IL-18等促炎细胞因子以及介导细胞焦亡。DCM发生时NLRP3表达上调,加剧胰岛β细胞功能受损、心肌损伤、心肌纤维化进程。已有研究证实,中药可通过抑制NLRP3炎性小体的启动和活化,以及其下游基因的表达,改善DCM心脏功能。本文就NLRP3炎性小体参与DCM发生及中药干预作用进行综述。     

NLRP3 inflammasome activation is associated with PM2.5‐induced cardiac functional and pathological injury in mice

Growing evidences indicate that inflammation induced by PM_2.5 exposure has been considered as a major driving force for the development of cardiovascular diseases. However, the mechanisms underlying PM_2.5‐induced cardiac injury remain unclear. This study aims to investigate the role of NLRP3 inflammasome in PM_2.5‐induced cardiac functional and pathological injury in mice. In this study, BALB/c mice were intratracheally instilled with PM_2.5 suspension (4.0 mg/kg BW) for 5 days to set up a cardiac injury model, which was evaluated by electrocardiogram monitoring, HE and Masson staining. Then, the effects of PM_2.5 on the expression of α‐SMA, NLRP3, IL‐1β, and IL‐18 proteins and the activation of caspase‐1 and IL‐1β were investigated. The results showed that PM_2.5 exposure induced characteristic abnormal ECG changes such as the abnormality of heart rhythm, tachycardia, and T‐wave reduction. Inflammatory cell infiltration and fibrosis were observed in the heart tissues of PM_2.5‐exposed mice. Meanwhile, PM_2.5 exposure increased the expression of α‐SMA. And, NLRP3 activation‐associated proteins of NLRP3, IL‐1β, IL‐18, Cleaved caspase‐1 p10, and Cleaved IL‐1β were upregulated in heart tissue of PM_2.5‐induced mice. In summary, PM_2.5 exposure could induce cardiac functional and pathological injury, which may be associated with the activation of NLRP3 inflammasome.     

Enalapril inhibits tubulointerstitial inflammation and NLRP3 inflammasome expression in BSA-overload nephropathy of rats

Aim:

Proteinuria is not only a common marker of renal disease, but also involved in renal tubulointerstitial inflammation and fibrosis. The aim of this study was to investigate the mechanisms underlying the protective effects of enalapril, an ACEI, against nephropathy in rats.

Methods:

Wistar rats underwent unilateral right nephrectomy, and then were treated with BSA (5 g·kg⁻¹·d⁻¹, ip), or BSA plus enalapril (0.5 g·kg⁻¹·d⁻¹, po) for 9 weeks. The renal lesions were evaluated using histology and immunohistochemistry. The expression of NLRP3, caspase-1, IL-1β and IL-18 was analyzed using immunohistochemistry, RT-PCR and Western blot.

Results:

BSA-overload resulted in severe proteinuria, which peaked at week 7, and interstitial inflammation with prominent infiltration of CD68⁺ cells (macrophages) and CD3⁺ cells (T lymphocytes), particularly of CD20⁺ cells (B lymphocytes). BSA-overload markedly increased the expression of NLRP3, caspase-1, IL-1β and IL-18 in the proximal tubular epithelial cells, and in inflammatory cells as well. Furthermore, the expression of IL-1β or IL-18 was significantly correlated with proteinuria (IL-1β: r=0.757; IL-18: r=0.834). These abnormalities in BSA-overload rats were significantly attenuated by concurrent administration of enalapril.

Conclusion:

Enalapril exerts protective effects against BSA-overload nephropathy in rats via suppressing NLRP3 inflammasome expression and tubulointerstitial inflammation.     

Glyburide attenuates ozone‐induced pulmonary inflammation and injury by blocking the NLRP3 inflammasome

Glyburide is a classic antidiabetic drug that is dominant in inflammation regulation, but its specific role in ozone‐induced lung inflammation and injury remains unclear. In order to investigate whether glyburide prevents ozone‐induced pulmonary inflammation and its mechanism, C57BL/6 mice were intratracheally pre‐instilled with glyburide or the vehicle 1 hour before ozone (1 ppm, 3 hours) or filtered air exposure. After 24 hours, the total inflammatory cells and total protein in bronchoalveolar lavage fluid (BALF) were detected. The pathological alternations in lung tissues were evaluated by HE staining. The expression of NLRP3, interleukin‐1β (IL‐1β), and IL‐18 protein in lung tissues was detected by immunohistochemistry. Western blotting was used to examine the levels of caspase‐1 p10 and active IL‐1β protein. Levels of IL‐1β and IL‐18 in BALF were measured using ELISA kits. Glyburide treatment decreased the total cells in BALF, the inflammatory score, and the mean linear intercept induced by ozone in lung tissues. In addition, glyburide inhibited the expression of NLRP3, IL‐18, and IL‐1β protein in lung tissues, and also suppressed NLRP3 inflammasome activation, including caspase‐1 p10, active IL‐1β protein in lung tissues, IL‐1β, and IL‐18 in BALF. These results demonstrate that glyburide effectively attenuates ozone‐induced pulmonary inflammation and injury via blocking the NLRP3 inflammasome.     

白藜芦醇对急性肝损伤小鼠NLRP3炎性体表达的影响

目的观察白藜芦醇对急性肝损伤(acute liver injury,ALI)小鼠Nod样受体家族3(Nod-like receptor 3,NLRP3)炎性体表达的影响,探讨白藜芦醇对ALI的保护作用及其机制。方法本实验采用四氯化碳制作ALI小鼠模型。将雄性ICR小鼠随机分成正常对照组、模型组、白藜芦醇低、中、高剂量组及阳性对照组,每组7只。白藜芦醇低、中、高剂量组及阳性对照组于造模前24 h及1 h分别腹腔注射剂量为10、20及30 mg/kg的白藜芦醇或剂量为100 mg/kg的乙酰半胱氨酸,对照组及模型组在相应时间点腹腔注射等量生理盐水,造模时模型组及各药物干预组采用腹腔注射5%四氯化碳,对照组腹腔注射等量橄榄油。采用蛋白质印迹(Western blot,WB)法测定小鼠肝组织NLRP3、凋亡相关微粒蛋白(apoptosis-associated speck-like protein contain,ASC)、炎性半胱天冬酶-1(caspase-1)蛋白,酶联免疫吸附测定(enzyme linked immunosorbent assay,ELISA)法检测炎症因子白介素(interleukin,IL)-1β及IL-18,全自动生化分析仪测定小鼠肝功能,病理组织学观察肝脏损伤情况及其程度。结果模型组小鼠谷丙转氨酶(alanine aminotransferase,ALT)及谷草转氨酶(aspartate aminotransferase,AST)水平高于正常对照组(P<0.01);白藜芦醇各剂量组及阳性对照组小鼠ALT及AST水平均低于模型组(P<0.01)。模型组小鼠肝脏炎症积分及损伤面积均高于正常对照组(P<0.01);白藜芦醇各剂量组及阳性对照组小鼠肝脏炎症积分及损伤面积均低于模型组(P<0.05或P<0.01)。模型组小鼠NLRP3、ASC、caspase-1、IL-1β及IL-18表达高于正常对照组(P<0.01);白藜芦醇各剂量组及阳性对照组小鼠NLRP3、ASC、caspase-1、IL-1β及IL-18表达均低于模型组(P<0.05或P<0.01)。病理组织切片显示,模型组小鼠肝细胞结构表现为胞浆疏松,小叶内坏死灶较多,坏死灶中可见中性粒细胞浸润;白藜芦醇各剂量组及阳性对照组小叶内坏死灶及中性粒细胞浸润等改变较模型组减少,肝细胞的受损面积较小。结论白藜芦醇可以显著减轻四氯化碳诱导的ALI,其机制可能与抑制NLRP3炎性体活化及其下游炎症级联反应有关。     

Adenovirus-delivered angiopoietin-1 ameliorates phosgene-induced acute lung injury via inhibition of NLRP3 inflammasome activation

Objective: Angiopoietin-1 (Ang1) is reported to have the ability to attenuate endothelial permeability and inflammation during the stress condition and is considered to play a critical role in vascular stabilization. The aim of this study was to investigate the mechanisms involved in the protective effects of adenovirus-delivered Ang1 in phosgene-induced acute lung injury (ALI).

Methods: ALI was induced in rats by phosgene exposure at 8.33?g/m³ for 5?min, followed by an intravenous injection of adenovirus-Ang1 (Ad/Ang1). The histologic changes of the lung were evaluated with H&;E staining. The levels of cytokines in the serum and bronchoalveolar lavage fluid (BALF) were determined by ELISA. NLRP3 inflammasome activation was assessed with immunohistochemistry, RT-PCR, Western blotting and TUNEL staining.

Results: Histologic analyses suggested that reduced severity in phosgene-induced ALI with Ad/Ang1 treatment. Reduced levels of IL-1β, IL-18 and IL-33 were found in both serum and BALF samples from Ad/Ang1-treated ALI rats induced by phosgene. Moreover, immunohistochemistry analysis revealed that Ad/Ang1 treatment inhibited the NLRP3 inflammasome activation. Decreased mRNA and protein levels of NLRP3 and caspase-1 were found in phosgene-exposed rats treated with Ad/Ang1. In addition, TUNEL staining indicated a decrease in pyroptosis in phosgene-exposed rats treated with Ad/Ang1.

Conclusions: Ang1 exerts beneficial effects on phosgene-induced lung injury via inhibition of NLRP3 inflammasome activation. Disruption of NLRP3 inflammasome activation might be served as therapeutic modality for the treatment of phosgene-induced ALI.     

NLRP3炎症小体激活及调节机制的研究进展

炎症小体是一种由Nod样受体(NLR)家族成员与PYHIN (pyrin and HIN domain)家族成员组成的胞浆多蛋白复合物,能被多种病原相关分子模式或损伤相关分子模式激活。炎症小体的功能是激活半胱天冬酶1(Caspase-1),进而引起促炎细胞因子白细胞介素(IL)-1β和IL-18的成熟和分泌,并诱导细胞焦亡。NLR家族蛋白3(NLRP3)炎症小体是由NLRP3、接头蛋白ASC和效应蛋白Caspase-1组成的大分子多蛋白复合体。与其他炎症小体不同,NLRP3炎症小体可以被多种刺激物活化,包括微生物组分和内源性分子。NLRP3炎症小体在免疫系统和人类疾病中的重要性显而易见,但其激活及调节的机制仍不清楚。在此,主要对NLRP3炎症小体活化和调节的机制进行综述。

     

Costunolide covalently targets NACHT domain of NLRP3 to inhibit inflammasome activation and alleviate NLRP3-driven inflammatory diseases

The NLRP3 inflammasome’s core and most specific protein, NLRP3, has a variety of functions in inflammation-driven diseases. Costunolide (COS) is the major active ingredient of the traditional Chinese medicinal herb Saussurea lappa and has anti-inflammatory activity, but the principal mechanism and molecular target of COS remain unclear. Here, we show that COS covalently binds to cysteine 598 in NACHT domain of NLRP3, altering the ATPase activity and assembly of NLRP3 inflammasome. We declare COS’s great anti-inflammasome efficacy in macrophages and disease models of gouty arthritis and ulcerative colitis via inhibiting NLRP3 inflammasome activation. We also reveal that the α-methylene-γ-butyrolactone motif in sesquiterpene lactone is the certain active group in inhibiting NLRP3 activation. Taken together, NLRP3 is identified as a direct target of COS for its anti-inflammasome activity. COS, especially the α-methylene-γ-butyrolactone motif in COS structure, might be used to design and produce novel NLRP3 inhibitors as a lead compound.     

NLRP3炎性小体影响血管衰老的机制及其相关药物的研发

NOD (nucleotide binding oligomerization domain)样受体家族3(NOD-like receptor protein 3,NLRP3)炎症小体调控天冬氨酸特异蛋白酶-1 (caspase-1)、白细胞介素-18 (interleukin-18,IL-18)和IL-1β等细胞因子...     

Leptin is upregulated in epididymitis and promotes apoptosis and IL-1β production in epididymal epithelial cells by activating the NLRP3 inflammasome

Epididymitis, one of the most common urological disease, is a significant cause of male infertility. Leptin is capable of modulating both reproduction and immune response. We analyzed the serum and seminal plasma levels of leptin in infertile patients with or without chronic epididymitis. Experimental epididymitis models were generated by administrating 200 μg Lipopolysaccharide (LPS) to Sprague-Dawley rats. The expression of leptin in epididymis were detected using qPCR, Western blots 6–72 h after injection, and using immunohistochemistry 72 h after injection. Besides, rat epididymal epithelial cells were isolated as an in vitro model and were treated with leptin (5–40 ng/ml, 6–48 h), LPS (1ug/ml, 6 h), and NLRP3 inflammasome inhibitor MCC950 (10 μM, 2 h). Cell Counting Kits-8 assay and Annexin V/PE assay were used to evaluate cell viability and apoptosis. Quantitive PCR and ELISA assay were used to detected inflammatory cytokines interleukin-1beta (IL-1β) production. Western Blots were used to detect molecular related to cell apoptosis, IL-1β maturation, and NLRP3 inflammasome. We found that patients with chronic epididymitis presented a significantly higher level of seminal plasma leptin and correlated declined sperm progressive motility. Leptin and leptin receptor expression in epididymis was significantly upregulated 24 h after LPS administration both in mRNA and protein level, and highly expressed in the epididymis epithelium 72 h after LPS administration. In epididymal epithelial cells, leptin reduced cell viability and promoted apoptosis in a concentration-dependent manner via cleavage of caspase-9, caspase-3, and PARP. Leptin enhanced the LPS-induced production of IL-1β, which was associated with increased IL-1β maturation and caspase-1 activation. Furthermore, NLRP3 inhibitor MCC950 attenuated the effects of leptin or co-treatment with LPS on NLRP3, ASC expression, IL-1β maturation, and caspase-1 activation, which indicated that leptin promotes IL-1β production via activating the NLRP3 inflammasome. These data suggested that leptin may act as a potential evaluation and treatment target for epididymitis and male subfertility.     

NLRP3 inflammasome and glia maturation factor coordinately regulate neuroinflammation and neuronal loss in MPTP mouse model of Parkinson’s disease

Neuroinflammation plays an active role in the pathogenesis of several neurodegenerative diseases, including Parkinson’s disease (PD). Earlier studies from this laboratory showed that glia maturation factor (GMF), a proinflammatory mediator; is up-regulated in the brain in neurodegenerative diseases and that deficiency of GMF showed decreased production of IL-1β and improved behavioral abnormalities in mouse model of PD. However, the mechanisms linking GMF and dopaminergic neuronal death have not been completely explored. In the present study, we have investigated the expression of NLRP3 inflammasome and caspase-1 in the substantia nigra (SN) of human PD and non-PD brains by immunohistochemistry. Wild-type (WT) and GMF^−/− (GMF knock-out) mice were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydro pyridine (MPTP) and the brains were isolated for neurochemical and morphological examinations. NLRP3 and caspase-1 positive cells were found significantly increased in PD when compared to non-PD control brains. Moreover, GMF co-localized with α-Synuclein within reactive astrocytes in the midbrain of PD. Mice treated with MPTP exhibit glial activation-induced inflammation, and nigrostriatal dopaminergic neurodegeneration. Interestingly, increased expression of the inflammasome components in astrocytes and microglia observed in the SN of MPTP-treated WT mice were significantly reduced in GMF^−/− mice. Additionally, we show that NLRP3 activation in microglia leads to translocation of GMF and NLRP3 to the mitochondria. We conclude that downregulation of GMF may have beneficial effects in prevention of PD by modulating the cytotoxic functions of microglia and astrocytes through reduced activation of the NLRP3 inflammasome; a major contributor of neuroinflammation in the CNS.     

Oridonin ameliorates carbon tetrachloride-induced liver fibrosis in mice through inhibition of the NLRP3 inflammasome

Liver fibrosis is characterized by the activation of hepatic stellate cells (HSCs) and accumulation of the extracellular matrix. There are limitations in the current therapies for liver fibrosis. Recently, oridonin was shown to induce apoptosis in HSCs. Thus, we aimed to determine the roles of oridonin in chronic liver injury and fibrosis. Liver fibrosis was induced by CCl₄ in mice injected intraperitoneally with oridonin for 6 weeks. The administration of oridonin significantly attenuated liver injury and reduced ALT levels. In addition, Sirius Red staining and the expression of α-smooth muscle actin (α-SMA) were significantly reduced by oridonin in murine livers with fibrosis. The expression of NLRP3, caspase-1, and IL-1β was downregulated with the oridonin treatment. Furthermore, the expression of F4/80 in liver tissues was also decreased by oridonin treatment. These results demonstrate that oridonin ameliorates chronic liver injury and fibrosis. Mechanically, oridonin may inhibit the activity of the NLRP3 inflammasome and inflammation in the liver. These results highlight the potential of oridonin as a therapeutic agent for liver fibrosis.     

Dihydroartemisinin prevents dextran sodium sulphate-induced colitis through inhibition of the activation of NLRP3 inflammasome and p38 MAPK signaling

Dihydroartemisinin (DHA), a sesquiterpene lactone derived from artemisinin, has been reported to possess anti-inflammation and anti-cancer activities. But its underlying protective mechanisms on dextran sodium sulphate (DSS)-induced colitis remain rarely reported. We applied a network pharmacology approach to predict the collective targets of DHA and acute colitis. GO and KEGG analyses were performed to investigate the enriched biological functions and signaling pathways of the collective targets. Furthermore, a DSS-induced colitis model was established to observe the protective effects of DHA. 83 common targets of DHA and acute colitis were identified and predominantly involved in several inflammation-related signaling pathways in colitis such as NOD-like receptor and MAPK signaling pathways. Additionally, DHA in vivo improved the clinical symptoms, reduced the production of pro-inflammatory factors IL-1β, IL-6 and TNF-α, and suppressed the formation of NLRP3 inflammasome. Moreover, DHA inhibited the phosphorylation of NF-κB p65 and p38 MAPK, but upregulated PPARγ and Ki-67 levels compared to the DSS group. Additionally, we found that DHA suppressed p38 activator-induced pro-inflammatory response, and p38 inhibitor attenuated the clinical symptoms and reduced the expression levels of pro-inflammatory mediators and NLRP3 while up-regulated the expression levels of PPARγ and Ki-67. Molecular docking analysis further verified the binding mode towards the DHA and p38 MAPK. In conclusion, DHA could protect DSS-induced colitis via suppressing the activation of NLRP3 inflammasome and p38 MAPK signaling.     

Free fatty acids as modulators of the NLRP3 inflammasome in obesity/type 2 diabetes

Free fatty acids (FFAs) are metabolic intermediates that may be obtained through the diet or synthesized endogenously. In addition to serving as an important source of energy, they produce a variety of both beneficial and detrimental effects. They play essential roles as structural components of all cell membranes and as signaling molecules regulating metabolic pathways through binding to nuclear or membrane receptors. However, under conditions of FFAs overload, they become toxic, inducing ROS production, ER stress, apoptosis and inflammation. SFAs (saturated fatty acids), unlike UFAs (unsaturated fatty acids), have recently been proposed as triggers of the NLRP3 inflammasome, a molecular platform mediating the processing of IL-1β in response to infection and stress conditions. Interestingly, UFAs, especially ω-3 FAs, inhibit NLRP3 inflammasome activation in various settings. We focus on emerging models of NLRP3 inflammasome activation with a special emphasis on the molecular mechanisms by which FFAs modulate the activation of this complex. Taking into consideration the current literature and FFA properties, we discuss the putative involvement of mitochondria and the role of cardiolipin, a mitochondrial phospholipid, proposed to be sensed by NLRP3 after release, exposure and/or oxidation. Finally, we review how this SFA-mediated NLRP3 inflammasome activation contributes to the development of both insulin resistance and deficiency associated with obesity/type 2 diabetes. In this context, we highlight the potential clinical use of ω-3 FAs as anti-inflammatory compounds.     

Apolipoprotein E negatively regulates murine allergic airway inflammation via suppressing the activation of NLRP3 inflammasome and oxidative stress

Apolipoprotein E (ApoE) has been reported as a steroid unresponsive gene and functions as a negative regulator of airway hyperreactivity (AHR) and goblet cell hyperplasia in house dust mite (HDM)-challenged mice. However, the role of ApoE in Ovalbumin (OVA)-induced allergic airway inflammation disease and the underlying mechanism are still unknown. In the present study, murine allergic airway inflammation was induced by inhaled OVA for consecutive 7 days in wild type (WT) and ApoE^−/− mice. In the OVA-induced model, the ApoE level in the bronchoalveolar lavage fluid (BALF) and lung tissues was significantly higher than that of control mice. And ApoE deficiency aggravated airway inflammation including leukocytes infiltration, goblet cell hyperplasia and IgE production as compared to those of WT mice after OVA- challenged, suggesting ApoE servers as an endogenous negative regulator of airway inflammation. Furthermore, OVA challenge elevated the activation of NLRP3 inflammasome with higher protein expression of NLRP3, caspase1 and IL-1β, enhanced oxidative stress with higher expression of 8-OHdG, nitrotyrosine and SOD2, increased the expression of mitochondrial fusion/fission markers including Optic Atrophy 1 (OPA1), Mitofusion 2 (Mfn2), dynamin-related protein 1 (DRP1) and Fission 1 (Fis1). However, these OVA-induced changes were augmented in ApoE^−/− mice. Collectively, our results demonstrated that the OVA-induced airway inflammation was aggravated in ApoE^−/− mice, and suggested that the underlying mechanism may be associated with the augmented activation of NLRP3 inflammasome and oxidative stress in ApoE^−/− mice, therefore targeting ApoE pathway might be a novel therapy approach for allergic airway diseases such as asthma.     

Oleanolic Acid Provides Neuroprotection against Ischemic Stroke through the Inhibition of Microglial Activation and NLRP3 Inflammasome Activation

Oleanolic acid (OA), a natural pentacyclic triterpenoid, has been reported to exert protective effects against several neurological diseases through its anti-oxidative and anti-inflammatory activities. The goal of the present study was to evaluate the therapeutic potential of OA against acute and chronic brain injuries after ischemic stroke using a mouse model of transient middle cerebral artery occlusion (tMCAO, MCAO/reperfusion). OA administration immediately after reperfusion significantly attenuated acute brain injuries including brain infarction, functional neurological deficits, and neuronal apoptosis. Moreover, delayed administration of OA (at 3 h after reperfusion) attenuated brain infarction and improved functional neurological deficits during the acute phase. Such neuroprotective effects were associated with attenuation of microglial activation and lipid peroxidation in the injured brain after the tMCAO challenge. OA also attenuated NLRP3 inflammasome activation in activated microglia during the acute phase. In addition, daily administration of OA for 7 days starting from either immediately after reperfusion or 1 day after reperfusion significantly improved functional neurological deficits and attenuated brain tissue loss up to 21 days after the tMCAO challenge; these findings supported therapeutic effects of OA against ischemic stroke-induced chronic brain injury. Together, these findings showed that OA exerted neuroprotective effects against both acute and chronic brain injuries after tMCAO challenge, suggesting that OA is a potential therapeutic agent to treat ischemic stroke.     

Targeting connexin hemichannels to control the inflammasome: the correlation between connexin43 and NLRP3 expression in chronic eye disease

ABSTRACT

Introduction: Chronic inflammatory diseases, including retinal diseases that are a major cause of vision loss, are associated with activation of the nucleotide-binding domain and leucine-rich repeat containing (NLR) protein-3 (NLRP3) inflammasome pathway. In chronic disease, the inflammasome becomes self-perpetuating, indicating a common pathway in such diseases irrespective of underlying etiology, and implying a shared solution is feasible. Connexin43 hemichannels correlate directly with NLRP3 inflammasome complex assembly (shown here in models of retinal disease). Connexin43 hemichannel-mediated ATP release is proposed to be the principal activator signal for inflammasome complex assembly in primary signal-sensitized cells. Connexin hemichannel block on its own is sufficient to inhibit the inflammasome pathway.

Areas covered: We introduce chronic retinal disease, discuss available preclinical models and examine findings from these models regarding the targeting of connexin43 hemichannels and its effects on the inflammasome.

Expert opinion: In over 25 animal disease models, connexin hemichannel regulation has shown therapeutic benefit, and one oral connexin hemichannel blocker, tonabersat (Xiflam), is Phase II ready with safety evidence in over 1000 patients. Regulating the connexin hemichannel provides a means to move quickly into clinical trials designed to ameliorate the progression of devastating chronic diseases of the eye, but also elsewhere in the body.