Ethyl pyruvate confers protection against endotoxemia and sepsis by inhibiting caspase-11-dependent cell pyroptosis

Ethyl pyruvate exerts a special protective effect on endotoxin-induced endotoxemia and experimental sepsis, but the underlying mechanism remains elusive. We recently demonstrated that ethyl pyruvate inhibited caspase-11-mediated macrophage pyroptotic cell death. Gasdermin D is a key molecule in caspase-11 mediated non-canonical inflammasome-induced pyroptosis. We proved that ethyl pyruvate significantly decreased caspase-11 and gasdermin D-mediated pyroptosis induced by cytoplasmic lipopolysaccharide (LPS) and bacterial outer membrane vesicles (OMVs). Ethyl pyruvate treatment offered effective protection against lethal endotoxemia and reduced the release of IL-1α and IL-1β. Similar results were observed in the mouse cecal ligation and puncture (CLP) peritonitis sepsis model. These findings identified ethyl pyruvate as an inhibitor against LPS-mediated activation of cytoplasmic caspase-11 and gasdermin D. This mechanism is believed to contribute to the further explanation of the protective action of ethyl pyruvate in experimental sepsis and endotoxemia and the potential application of ethyl pyruvate for rescuing sepsis.     

Nipradilol inhibits apoptosis by preventing the activation of caspase-3 via S-nitrosylation and the cGMP-dependent pathway

To study whether nipradilol, which is used as an ophthalmic solution for the treatment of glaucoma, has a cytoprotective effect, we investigated its effect on the apoptosis induced by serum withdrawal in PC12 cells. Nipradilol has alpha1- and beta-adrenoceptor-blocking and nitric oxide (NO)-donating properties. We also investigated the effects of timolol, prazosin and S-nitroso-N-acetylpenicillamine (SNAP) on PC12 cell death. Serum withdrawal from PC12 cells resulted in apoptosis, and the survival rate was decreased in a time-dependent manner. The addition of nipradilol to the medium showed a cytoprotective effect on PC12 cell death in a dose-dependent manner, but timolol and prazosin did not. We measured caspase-3 activity to clarify the mechanism of the inhibition of apoptosis in the presence or absence of dithiothreitol (DTT). The caspase-3 activity could be reactivated by DTT. In addition, to investigate the relationship of the cGMP-dependent pathway to the nipradilol-induced cytoprotective effect, we tested the effect of the protein kinase G inhibitor KT5823. KT5823 partially reversed the nipradilol-mediated cytoprotective effect. These results indicate that the cytoprotective effect of nipradilol in PC12 cell death was due to the caspase-3 inhibition mediated by NO-related S-nitrosylation and activation of protein kinase G.     

芍药苷通过JAK2/STAT3信号通路抑制高糖诱导的RAW264.7巨噬细胞激活

目的探讨芍药苷(paeoniflorin,PF)抑制高糖(high glucose,HG)诱导的RAW264.7巨噬细胞激活是否通过JAK2/STAT3信号通路。方法体外HG激活巨噬细胞RAW264.7, PF及JAK2/STAT3干扰RNA(siRNA)进行干预,分别检测巨噬细胞的增殖、趋化、炎症因子表达分泌、JAK2和STAT3蛋白表达及其磷酸化水平。结果在HG刺激下,巨噬细胞趋化功能增强,诱生型一氧化氮合酶(iNOS)、肿瘤坏死因子α(TNF-α)、白细胞介素1β(IL-1β)及单核细胞趋化因子1(MCP-1)的mRNA表达,以及细胞培养基中TNF-α、IL-1β、MCP-1分泌水平均增加(P<0.05,P<0.01),JAK2、STAT3蛋白磷酸化表达明显增加(P<0.05)。JAK2/STAT3基因沉默可抑制HG刺激下iNOS和炎症因子(TNF-α、IL-1β、MCP-1)mRNA水平和细胞培养液中炎症因子的分泌,抑制JAK2、STAT3蛋白磷酸化水平(P<0.05,P<0.01)。PF能明显下调HG诱导的巨噬细胞趋化迁徙、炎症因子表达分泌及JAK2、STAT3蛋白磷酸化水平(P<0.01)。结论 HG可通过诱导JAK2/STAT3信号通路刺激巨噬细胞激活,PF抑制巨噬细胞激活的机制主要与抑制JAK2/STAT3信号通路相关。     

Exogenous stromal cell-derived factor-1 (SDF-1) suppresses the NLRP3 inflammasome and inhibits pyroptosis in synoviocytes from osteoarthritic joints via activation of the AMPK signaling pathway

Inflammopharmacology - NLRP3 inflammasome may play a key role in OA pathogenesis. Stromal cell-derived factor-1 (SDF-1) is a homeostatic CXC chemokine. Since the role of SDF-1 in OA has not been...     

GPR84 signaling promotes intestinal mucosal inflammation via enhancing NLRP3 inflammasome activation in macrophages

The putative medium-chain free fatty acid receptor GPR84 is a G protein-coupled receptor primarily expressed in myeloid cells that constitute the innate immune system, including neutrophils, monocytes, and macrophages in the periphery and microglia in the brain. The fact that GPR84 expression in leukocytes is remarkably increased under acute inflammatory stimuli such as lipopolysaccharide (LPS) and TNFα suggests that it may play a role in the development of inflammatory and fibrotic diseases. Here we demonstrate that GPR84 is highly upregulated in inflamed colon tissues of active ulcerative colitis (UC) patients and dextran sulfate sodium (DSS)-induced colitis mice. Infiltrating GPR84⁺ macrophages are significantly increased in the colonic mucosa of both the UC patients and the mice with colitis. Consistently, GPR84^−/− mice are resistant to the development of colitis induced by DSS. GPR84 activation imposes pro-inflammatory properties in colonic macrophages through enhancing NLRP3 inflammasome activation, while the loss of GPR84 prevents the M1 polarization and properties of proinflammatory macrophages. CLH536, a novel GPR84 antagonist discovered by us, suppresses colitis by reducing the polarization and function of pro-inflammatory macrophages. These results define a unique role of GPR84 in innate immune cells and intestinal inflammation, and suggest that GPR84 may serve as a potential drug target for the treatment of UC.     

灯盏花乙素对J774A.1巨噬细胞中ATP诱导的炎症小体活化和细胞焦亡的影响

目的以LPS致敏的小鼠巨噬细胞J774A.1作为炎症细胞模型,研究灯盏花乙素对ATP诱导的炎症小体活化和细胞焦亡的影响及其机制。方法利用碘化丙锭(PI)染色法检测LPS+ATP诱导的小鼠J774A.1巨噬细胞发生细胞焦亡的情况;免疫印迹法检测细胞裂解液和上清中IL-1β、caspase-1、HMGB1等蛋白的表达水平;基于微珠的免疫测定法(CBA)检测细胞上清中IL-1β的分泌水平。结果 ATP能够明显诱导LPS致敏的J774A.1巨噬细胞中caspase-1活化、成熟IL-1β(17 ku)和HMGB1释放至培养上清中,并诱导细胞焦亡;而灯盏花乙素预处理能够剂量依赖性地抑制ATP诱导的caspase-1活化以及成熟IL-1β、HMGB1的释放,并抑制细胞焦亡;同时,经腺苷酸环化酶抑制剂MDL12330A和蛋白激酶A(PKA)抑制剂H89处理,可以逆转灯盏花乙素对ATP诱导的细胞焦亡的抑制作用。结论灯盏花乙素通过调节PKA活性,抑制NLRP3炎症小体的活化与细胞焦亡,从而发挥抗炎作用。     

Baicalein inhibits lipid accumulation by regulating early adipogenesis and m-TOR signaling

Baicalein is a type of flavonoid that originates from Scutellaria baicalensis. In this study, we examined how baicalein inhibits lipid accumulation during adipogenesis in 3T3-L1 cells. Our data show that baicalein inhibited lipid accumulation during adipogenesis in a dose-dependent manner. Baicalein inhibition was limited to the early adipogenic stage. Cell cycle analysis showed that baicalein induced cell cycle arrest in the G0/G1 phase through cyclin downregulation. In addition, baicalein suppressed the mRNA expression of early adipogenic factors leading to downregulation of late adipogenic factors at mRNA and protein levels. Inhibition of adipogenic factors by baicalein was correlated with downregulation of lipid synthetic enzymes. Additionally, baicalein negatively regulated the m-TOR signaling pathway involved in lipid accumulation during adipogenesis, thus inhibiting phosphorylation of m-TOR and p70S6 K. In a zebrafish study, baicalein significantly reduced lipid accumulation in Nile Red staining. Consistent with a report using cell lines, mRNA expression of adipogenic factors was decreased in a dose-dependent manner by baicalein. This result reflects a reduction in total triglyceride levels based on a triglyceride assay. Our data suggest that baicalein inhibits lipid accumulation by controlling the cell cycle and m-TOR signaling in 3T3-L1 cells, and its anti-adipogenic effect was found in a zebrafish model.     

Organic solvent-induced proximal tubular cell apoptosis via caspase-9 activation

Long-term exposure to solvents is associated with apoptosis, which is implicated in the development and progression of tubulo-interstitial fibrosis and chronic renal failure. In our previous study, we demonstrated that toluene and p-xylene as the most commonly used organic solvents induced proximal tubular cells apoptosis. This study was conducted to assess the apoptotic pathway of toluene and p-xylene induced proximal tubular apoptosis. This was assessed by measuring the caspase-9 activity LLC-PK1 cells exposed to both compounds. A model of proximal tubular cell (LLC-PK1) cytotoxicity exposed to 1 mM of either p-xylene or toluene was compared to untreated control for caspase-9 activity and Bax/Bcl-2 protein level. Furthermore, DNA fragmentation in the presence of caspase-9 inhibitor (Z-LEHD-FMK) in a dose-dependent manner was assessed. Both compounds induced caspase-9 activity, which was accompanied by up-regulation of Bax, whereas Bcl-2 level did not change. DNA fragmentation induced by both solvents was inhibited by caspase-9 inhibitor in dose-dependent manner. This data suggest that p-xylene or toluene induces nephrotoxicity via mitochondrial caspase-9 pathway. This mechanism involves up-regulation of the apoptotic protein, Bax.     

Organic solvent-induced proximal tubular cell toxicity via caspase-3 activation

BACKGROUND: Occupational exposure to solvents may be associated with development and progression of tubulo-interstitial fibrosis and chronic renal failure. However, the cellular mechanisms by which this occurs remain elusive. MATERIALS AND METHODS: The cytotoxicity of proximal tubular cells (LLC-PK1) exposed to 106 mg/mL of p-xylene or 92 mg/mL of toluene was compared with untreated controls using cell viability (MTS assay) and caspase-3 activity, with or without caspase-3 selective inhibitor. RESULTS: Both compounds reduced cell viability and increased caspase-3 activation (P < 0.005). Inhibition of caspase-3 by the selective inhibitor DEVD-CHO prevented injury (P < 0.001) and inhibited solvent-induced caspase-3 activation (P < 0.005). CONCLUSION: Inhibition of caspase-3, the critical caspase in the apoptosis process, prevents cell injury in LLC-PK1. This suggests that caspase-3 may play a pivotal role in solvent-induced proximal tubular cell injury.     

Curcumin inhibits renal cyst formation and enlargement in vitro by regulating intracellular signaling pathways

Autosomal dominant polycystic kidney disease, a common inherited disease affecting about 1/1000 and 1/400 live births, is characterized by massive enlargement of fluid-filled cysts and eventually causes renal failure. The purpose of this study is to identify the inhibitory effect of curcumin on renal cyst development and to investigate the inhibitory mechanism. Madin–Darby canine kidney (MDCK) cyst model and murine embryonic kidney cyst model were used to evaluate inhibitory activity. Cell viability, proliferation, apoptosis, CFTR function and expression, and signaling pathways in MDCK cells were determined to explore the mechanism of cyst inhibition. Curcumin was found to significantly inhibit MDCK cyst development. At maximum dose curcumin caused 62% inhibition of the cyst formation (IC₅₀ was 0.12 μM). Curcumin slowed cyst enlargement in both MDCK cyst model and embryonic kidney cyst model with dose–response relationship. Curcumin neither induced cytotoxicity nor apoptosis in MDCK cells at < 100 μM. Curcumin failed to affect the chloride transporter CFTR expression and function. Interestingly, curcumin inhibited forskolin-promoted cell proliferation and promoted the tubule formation in MDCK cells, which indicates curcumin promotes MDCK cell differentiation. Furthermore, curcumin reduced the intracellular signaling proteins Ras, B-raf, p-MEK, p-ERK, c-fos, Egr-1, but increased Raf-1 and NAB2 in MDCK cells exposed to forskolin. These results define that curcumin inhibits renal cyst formation and enlargement and suggest that curcumin might be developed as a candidate drug for polycystic kidney disease.     

Scutellarin exerts its anti-hypertrophic effects via suppressing the Ca2+-mediated calcineurin and CaMKII signaling pathways

Scutellarin is a flavonoid extracted from a traditional Chinese herb, Erigeron breviscapus Hand Mazz, which has been broadly used in treating various cardiovascular diseases. In this study, we investigated its effect on cardiac hypertrophy and the underlying mechanism. Both in vitro and in vivo cardiac hypertrophy models were employed to explore the anti-hypertrophic action of scutellarin. We found that scutellarin significantly suppressed the hypertrophic growth of neonatal cardiac myocytes exposed to phenylephrine (PE) and mouse heart subjected to pressure overload induced by aortic banding, accompanied with the decreased expression of hypertrophic markers β-myosin heavy chain and atrial natriuretic peptide. We then measured the change of free intracellular calcium using laser scanning confocal microscope. We found that scutellarin alleviated the increment of free intracellular calcium during cardiac hypertrophy either induced by PE or aortic banding. The expression of calcium downstream effectors calcineurin and phosphorylated calmodulin kinase II (CaMKII) were significantly suppressed by scutellarin. Our study indicated that scutellarin exerts its anti-hypertrophic activity via suppressing the Ca²⁺-mediated calcineurin and CaMKII pathways, which supports the observation that clinical application of scutellarin is beneficial for cardiovascular disease patients.     

4-hydroxynonenal induces apoptosis via caspase-3 activation and cytochrome c release

We investigated the mechanism by which 4-hydroxynonenal (HNE), a major aldehydic product of lipid peroxidation, induces apoptosis in tumor cells. Treatment of human colorectal carcinoma (RKO) cells with HNE-induced poly-ADP-ribose-polymerase (PARP) cleavage and DNA fragmentation in a dose- and time-dependent manner. The induction of PARP cleavage and DNA fragmentation paralleled caspase-2, -3, -8, and -9 activation. Pretreatment of cells with an inhibitor of caspase-3, z-DEVD-fmk, or a broad spectrum caspase inhibitor, z-VAD-fmk, abolished caspase activation and subsequent PARP cleavage. Constitutive expression of high levels of Bcl-2 protected cells from HNE-mediated apoptosis. In addition, Bcl-2 overexpression inhibited cytochrome c release from mitochondria and subsequent caspase-2, -3, and -9 activation. These findings demonstrate that HNE triggers apoptotic cell death through a mitochondrion-dependent pathway involving cytochrome c release and caspase activation. Bcl-2 overexpression protected cells from HNE-induced apoptosis through inhibition of cytochrome c release.     

中介素通过激活AMPK信号通路对脂多糖诱导巨噬细胞极化的影响

目的探讨中介素(intermedin,IMD)对脂多糖(lipopolysaccharide,LPS)诱导小鼠单核巨噬细胞系RAW 264.7极化的影响及其作用机制。方法RAW 264.7细胞随机分为对照组、LPS组、LPS+IMD组、LPS+IMD+CC(AMPK抑制剂Compound C)组。Real time-PCR法检测TNF-α、CD86、iNOS、Arg^-1、CD206 mRNA表达,Western blot法检测p-AMPK、AMPK、TNF-α、IL-6和IL^-10蛋白表达,流式细胞术检测巨噬细胞亚型,ELISA法检测培养基上清IL-6和TNF-α浓度。结果与对照组及LPS组比较,IMD处理可增加AMPK磷酸化水平,增加p-AMPK/AMPK比值;与对照组相比,LPS诱导可导致巨噬细胞发生M1极化,M1型标志分子CD86、TNF-α及iNOS mRNA表达升高,M2型标志分子CD206、Arg^-1 mRNA表达降低,上调促炎因子TNF-α、IL-6表达,降低抑炎因子IL^-10表达,使M1型细胞数量增加,细胞上清中TNF-α、IL-6分泌增加;而IMD处理可抑制LPS诱导的M1极化,AMPK抑制剂Compound C组处理可在一定程度上拮抗这一作用。结论IMD通过激活AMPK信号通路抑制LPS诱导的巨噬细胞M1型极化。     

The anti-diabetic drug repaglinide induces vasorelaxation via activation of PKA and PKG in aortic smooth muscle

We investigated the vasorelaxant effect of repaglinide and its related signaling pathways using phenylephrine (Phe)-induced pre-contracted aortic rings. Repaglinide induced vasorelaxation in a concentration-dependent manner. The repaglinide-induced vasorelaxation was not affected by removal of the endothelium. In addition, application of a nitric oxide synthase inhibitor (L-NAME) and a small-conductance Ca^2 +-activated K⁺ (SK_Ca) channel inhibitor (apamin) did not alter the vasorelaxant effect of repaglinide on endothelium-intact arteries. Pretreatment with an adenylyl cyclase inhibitor (SQ 22536) or a PKA inhibitor (KT 5720) effectively reduced repaglinide-induced vasorelaxation. Also, pretreatment with a guanylyl cyclase inhibitor (ODQ) or a PKG inhibitor (KT 5823) inhibited repaglinide-induced vasorelaxation. However, pretreatment with a voltage-dependent K⁺ (Kv) channel inhibitor (4-AP), ATP-sensitive K⁺ (K_ATP) channel inhibitor (glibenclamide), large-conductance Ca^2 +-activated K⁺ (BK_Ca) channel inhibitor (paxilline), or the inwardly rectifying K⁺ (Kir) channel inhibitor (Ba^2 +) did not affect the vasorelaxant effect of repaglinide. Furthermore, pretreatment with a Ca^2 + inhibitor (nifedipine) and a sarco-endoplasmic reticulum Ca^2 +-ATPase (SERCA) inhibitor (thapsigargin) did not affect the vasorelaxant effect of repaglinide. The vasorelaxant effect of repaglinide was not affected by elevated glucose (50 mM). Based on these results, we conclude that repaglinide induces vasorelaxation via activation of adenylyl cyclase/PKA and guanylyl cyclase/PKG signaling pathways independently of the endothelium, K⁺ channels, Ca^2 + channels, and intracellular Ca^2 + ([Ca^2 +]_i).     

红景天苷调控KLF4/eNOS信号抑制Hcy诱导内皮-间质转分化的作用

目的基于KLF4/eNOS信号,研究红景天苷(salidroside,SAL)对同型半胱氨酸(Hcy)诱导内皮细胞间质转分化(EndMT)的作用及机制。方法(1)研究SAL对Hcy诱导EndMT的作用。不同剂量SAL预处理后,给予Hcy(1 mmol·L^-1)共孵育48 h诱导EndMT。采用Western blot检测VE-cadherin、α-SMA、KLF4及eNOS的蛋白水平,划痕修复实验检测细胞迁移能力,硝酸还原酶法检测细胞内NO水平,细胞免疫荧光技术检测KLF4表达及定位。(2)基于KLF4/eNOS信号,研究SAL抑制EndMT的信号机制。采用siRNA技术实现细胞内KLF4的沉默,Western blot检测VE-cadherin与α-SMA,KLF4及eNOS的蛋白水平。结果(1)SAL上调Hcy诱导的VE-cadherin及下调α-SMA的表达,降低细胞迁移能力,上调eNOS/NO信号轴水平,并抑制KLF4的表达及向胞核转位。(2)沉默KLF4可下调α-SMA及KLF4的表达,上调VE-cadherin和eNOS的表达。与SAL+siKLF4组比较,SAL组及siKLF4组对表型标志物的作用无明显差异。结论SAL抑制Hcy诱导的EndMT,其作用与调节KLF4/eNOS信号途径有关。     

Isoalantolactone inhibits RANKL-induced osteoclast formation via multiple signaling pathways

The metabolic osteopathy known as postmenopausal osteoporosis is caused by disruption of the balance between bone resorption and osteogenesis, processes that are mediated by osteoclasts and osteoblasts, respectively. The current therapeutic approaches to treating osteoporosis have several limitations. In this study, we demonstrated that the natural chemical compound isoalantolactone (IAL) could inhibit osteoclastogenesis, without affecting osteogenesis. This is the first study reporting a role of IAL in suppressing the receptor activator of nuclear factor-kappa B ligand (RANKL)-induced osteoclast formation in a dose-dependent manner, and downregulating the expression of osteoclast-related marker genes. Furthermore, IAL abrogated the phosphorylation of c-Jun N-terminal kinase (JNK)/p38, NF-κB, and phosphatidylinositol 3-kinase (PI3K)-AKT, and also diminished the expression of osteoclastogenesis-related proteins. In conclusion, our results indicated that IAL has promise for the treatment of osteoporosis and other metabolic bone diseases.     

黄芩苷通过调控c-Myc介导的细胞周期抑制胆管癌细胞增殖

目的　探究黄芩苷（BC）对人胆管癌（CCA）细胞QBC939和RBE增殖的影响及其潜在机制。方法　取对数生长期QBC939和RBE细胞,不同浓度的BC处理细胞24 h后,采用CCK-8法分别检测BC对CCA细胞增殖及敲低原癌基因蛋白质（c-Myc）后对BC引起细胞增殖活性改变的影响;高倍显微镜观察BC对细胞生长状态的影响;流式细胞术检测BC对CCA细胞周期的影响;蛋白免疫印迹（Western blot）实验分别检测BC及小干扰RNA（siRNA）敲低CCA细胞中c-Myc后对周期相关蛋白周期素依赖激酶抑制剂（p27）、细胞周期蛋白D1（Cyclin D1）及c-Myc表达的影响。结果　与0 μmol/L组相比,BC明显抑制QBC939和RBE细胞的增殖活性（P＜0.01）,且高倍显微镜下观察到细胞生长减缓;BC可将QBC939细胞周期阻滞于S期（P＜0.05）;随着BC浓度的增加,p27的蛋白水平明显上调,而Cyclin D1则显著降低（P＜0.01）;BC可下调c-Myc的蛋白表达,且敲低c-Myc后p27和Cyclin D1蛋白表达的变化趋势与BC处理时一致（P＜0.05）;单独敲低c-Myc后可明显抑制QBC939和RBE细胞的存活率（P＜0.01）,并能进一步增强BC的抑制作用。结论　BC通过抑制c-Myc信号通路阻滞细胞周期,进而抑制CCA细胞的增殖。