Curcumin supplementation could improve diabetes-induced endothelial dysfunction associated with decreased vascular superoxide production and PKC inhibition

Background  

Curcumin, an Asian spice and food-coloring agent, is known for its anti-oxidant properties. We propose that curcumin can improve diabetes-induced endothelial dysfunction through superoxide reduction.     

姜黄素通过HO/GC途径对抗高糖诱导的血管收缩功能下降

目的:研究姜黄素是否可对抗高糖诱导的血管收缩功能下降,并探讨其作用机制。方法:采用血管环离体灌流装置,观察SD大鼠胸主动脉环的收缩反应;测定主动脉胆红素生成量反映血红素加氧酶-1(HO-1)的活性。结果:(1)与空白对照组(含11mmol/L葡萄糖)相比,经44mmol/L葡萄糖(高糖)孵育血管4h后,主动脉环对苯肾上腺素(PE)引起的血管收缩反应下降;(2)姜黄素(3×10-11-3×10-10mol/L)与高糖联合孵育,均能不同程度地抑制高糖诱导的血管PE收缩反应的下降;(3)姜黄素孵育后可引起血管HO活性增高;HO-1抑制剂锌原卟啉Ⅸ(ZnPP)可完全取消姜黄素的抗高糖损伤作用;(4)鸟苷酸环化酶(GC)抑制剂亚甲蓝可部分阻断姜黄素的保护作用。结论:姜黄素可能通过诱导HO-1活性增加和激活GC途径对抗高糖引起的血管收缩功能降低。     

Tigecycline-induced inhibition of mitochondrial DNA translation may cause lethal mitochondrial dysfunction in humans

BackgroundA 65-year-old patient developed an unexplained and ultimately lethal metabolic acidosis under prolonged treatment with tigecycline. Tigecycline is known to have a selective inhibitory effect on eukaryotic mitochondrial translation. The underlying molecular mechanisms of the metabolic acidosis in this patient were explored.MethodsOxidative phosphorylation system (OXPHOS) analysis, blue native polyacrylamide gel electrophoresis followed by in-gel activity staining in mitochondria, molecular analysis of mitochondrial DNA (mtDNA) for genomic rearrangements and sequencing of the rRNA genes was performed on the subject's skeletal muscle.ResultsOXPHOS analysis revealed a combined deficiency of the complexes I, III, IV and V, with a preserved function of complex II (encoded by nuclear DNA), thus demonstrating a defective mtDNA translation. There were no known underlying mitochondrial genetic defects. The patient had a (m.1391T>A) variant within the 12SrRNA gene in heteroplasmy (50–60%).ConclusionsThis patient developed an ultimately lethal mitochondrial toxicity while receiving prolonged treatment with tigecycline, which was caused by a defective translation of the mtDNA. Tigecycline is known to suppress eukaryotic mitochondrial DNA translation, but until now this effect has been considered to be clinically insignificant. The observations in this patient suggest a clinically significant mitochondrial toxicity of tigecycline in this patient, and warrant further investigation.     

Clk-1 deficiency induces apoptosis associated with mitochondrial dysfunction in mouse embryos

Clk-1 gene encodes demethoxyubiquinone hydroxylase that catalyzes the production of coenzyme Q (CoQ) in mitochondria. Clk-1-deficient mice that lack CoQ fail to survive beyond the embryonic day 10.5 (E10.5). However, the relationship between the clk-1-deficiency and embryonic lethality remains unclear. We show in this study that TUNEL-positive cells are frequently observed in whole bodies of clk-1-deficient mouse embryos at E10.5. In addition, dissociated cells from the embryos exhibited characteristic features of apoptosis, such as externalization of phosphatidylserine on the plasma membrane, caspase-3 activation, and the release of cytochrome c from mitochondria into the cytoplasm, as the first sign of mitochondria-mediated apoptosis. In embryonic cells, the mitochondrial functions such as maintenance of the mitochondrial membrane potential and intracellular ATP level were impaired. Since exogenous CoQ10 rescued the mitochondrial dysfunction and suppressed apoptosis in clk-1-deficent cells, we propose that clk-1-deficency induces apoptosis associated with mitochondrial dysfunction due to a lack of CoQ, which may lead to embryonic lethality in mice around E10.5.     

姜黄素激活自噬干预非酒精性脂肪肝病模型大鼠氧化应激及炎症反应

背景:自噬、氧化应激及炎症反应在非酒精性脂肪肝病中扮演重要角色,姜黄素具有调节自噬、氧化应激及炎症反应等生物活性。目的:探讨姜黄素对非酒精性脂肪肝病大鼠模型保护作用以及机制研究。方法:高糖高脂饮食8周建立非酒精性脂肪肝病大鼠模型,将40只SD大鼠分成对照组、模型组、姜黄素治疗组、姜黄素+3-甲基腺嘌呤组。在第8周末开始干预,对照组和模型组给予PBS灌胃,姜黄素组给予姜黄素500 mg/(kg·d)灌胃,姜黄素+3-甲基腺嘌呤组给予姜黄素500 mg/(kg·d)灌胃及2 mg/(kg·d)自噬抑制剂3-甲基腺嘌呤腹腔注射,干预8周。检测大鼠血清丙氨酸氨基转移酶、天冬氨酸氨基转移酶及总三酰甘油、总胆固醇、空腹血糖浓度;油红O染色观察各组大鼠肝内细胞脂滴分布,透射电镜观察肝细胞线粒体超微结构;采用硫代巴比妥酸法及黄嘌呤氧化酶法测定丙二醛及超氧化物歧化酶活性;Western blot检测自噬及炎症相关蛋白P62、LC3Ⅱ、Beclin-1、NF-κB的表达。实验方案经武汉大学人民医院动物实验伦理委员会批准(批准号2018-541)。结果与结论:①大鼠血清丙氨酸氨基转移酶、天冬氨酸氨基转移酶及总三酰甘油、总胆固醇水平:模型组均高于对照组(P<0.05),姜黄素治疗组显著低于模型组(P<0.05),姜黄素+3-甲基腺嘌呤组高于姜黄素治疗组但低于模型组(均<0.05);②细胞脂质沉积:模型组明显多于对照组;姜黄素治疗组明显少于模型组,姜黄素+3-甲基腺嘌呤组明显高于姜黄素治疗组但低于模型组;③透射电镜观察发现对照组未见明显线粒体损伤,模型组线粒体明显水肿,嵴断裂或消失等,姜黄素可显著缓解线粒体损伤,姜黄素+3-甲基腺嘌呤组对线粒体损失在模型组及姜黄素之间;④肝组织内超氧化物歧化酶水平:模型组显著低于对照组,姜黄素治疗组显著高于模型组,姜黄素+3-甲基腺嘌呤组显著低于姜黄素治疗组但高于模型组;⑤肝组织丙二醛水平:模型组显著高于对照组,姜黄素治疗组显著低于模型组,姜黄素+3-甲基腺嘌呤组显著高于姜黄素治疗组但低于模型组;⑥Western blot检测:与对照组相比,模型组肝组织P62、NF-κB蛋白表达均增加,而Beclin-1、LC3Ⅱ/LC3Ⅰ均降低(P均<0.05),经姜黄素治疗后P62、NF-κB蛋白表达均降低,而Beclin-1、LC3Ⅱ/LC3Ⅰ增加;姜黄素+3-甲基腺嘌呤组P62、NF-κB蛋白表达均低于模型组但高于姜黄素组,而Beclin-1、LC3Ⅱ/LC3Ⅰ高于模型组但低于姜黄素组,差异均有显著性意义(P均<0.05);⑦结果说明,姜黄素通过激活自噬调节炎症反应及氧化应激而改善非酒精脂肪肝病大鼠模型脂肪变性。     

Generalized pustular psoriasis and hepatic dysfunction associated with oral terbinafine therapy

We report a case of 61-yr-old man with stable psoriasis who progressively developed generalized pustular eruption, erythroderma, fever, and hepatic dysfunction following oral terbinafine. Skin biopsy was compatible with pustular psoriasis. After discontinuation of terbinafine and initiating topical corticosteroid and calcipotriol combination with narrow band ultraviolet B therapy, patient's condition slowly improved until complete remission was reached 2 weeks later. The diagnosis of generalized pustular psoriasis (GPP) induced by oral terbinafine was made. To our knowledge, this is the first report of GPP accompanied by hepatic dysfunction associated with oral terbinafine therapy.     

Multisystem failure and hepatic microvesicular fatty metamorphosis associated with tolmetin ingestion

Multisystem toxicity including both renal and hepatic failure has been reported with the use of nonsteroidal anti-inflammatory drugs. We report a fatal case of multisystem failure associated with tolmetin ingestion in a 15-year-old girl. Microvesicular fatty change was found in the liver at autopsy. To our knowledge, this is the first reported case of nonsteroidal anti-inflammatory drug-associated multisystem failure to have this histopathologic finding.     

Raised hepatic free fatty acids in a patient with acute fatty liver after gastric surgery for morbid obesity.

A patient died after gastric surgery for morbid obesity. Necropsy showed severe fatty liver, and biochemical analysis of hepatic lipids showed unusually high free fatty acid concentrations, which may have contributed to the hepatic failure.     

13C-methionine breath test detects distinct hepatic mitochondrial dysfunction in HIV-infected patients with normal serum lactate

OBJECTIVE: To assess mitochondrial respiratory chain dysfunction in different treatment groups of HIV-infected patients with normal serum lactate by measuring hepatic mitochondrial decarboxylation capacity by the C-methionine breath test (MeBT) and to correlate MeBT results with mitochondrial DNA (mtDNA) content in peripheral blood mononuclear cells (PBMCs). METHODS: Four groups were studied: HIV-negative controls (n = 10), treatment-naive patients (n = 15), antiretroviral therapy (ART)-treated patients with asymptomatic disease (n = 15), and patients with long-term treatment and clinical evidence of lipoatrophy (n = 15). After oral administration of C-methionine, CO2 exhalation was determined by infrared spectroscopy. MtDNA content in PBMCs was assessed by real-time polymerase chain reaction quantification. RESULTS: CO2 exhalation in lipoatrophic patients and therapy-naive patients was distinctly decreased when compared with that in healthy controls and asymptomatic patients (P < 0.001). The functional mitochondrial impairment in lipoatrophic patients was associated with a 47% decline in mtDNA content. MeBT results and mtDNA were significantly correlated in ART-treated patients (r = 0.77, P < 0.0001). CONCLUSIONS: MeBT is a simple noninvasive method to detect mitochondrial dysfunction in HIV-infected patients that correlates with mtDNA depletion in PBMCs of ART-treated individuals. Decreased hepatic methionine metabolism in therapy-naive patients may reflect the functional relevance of viral-mediated mitochondrial toxicity.     

Interferon-gamma is associated with hepatic dysfunction in fibrosis,cirrhosis, and hepatocellular carcinoma

The relation between interferon–gamma (IFN-γ) levels and the severity of liver diseases through fibrosis, cirrhosis, and hepatocellular carcinoma (HCC) has not been fully clarified. Thus, we aimed to characterize IFN-γ levels in liver-diseased patients. IFN-γ levels were determined by Western-blot and ELISA in sera from 30 healthy individuals, 53 patients with non-significant fibrosis (F0-F1), 47 with moderate/severe fibrosis (F2-F3), 44 cirrhotic patients (F4), and 50 with HCC. Enhanced levels of IFN-γ were associated with the progression of liver disease. The differences were statistically significant (P < 0.0001) when patients with F2-F3, F4, or HCC were compared with F0-F1 or healthy controls. The increase in IFN-γ was associated with HCC (OR = 0.98, 95% CI 0.97–0.99, P = 0.002). There was no statistically significant association between IFN-γ levels and HCV-RNA (IU/ml) (r = 0.1, P = 0.43) or HCV-NS4 (µg/mL) (r = 0.1, P = 0.17). There was significant (P < 0.0001) association between IFN-γ levels and the fibrosis stages and activity, albumin, platelet count, total bilirubin, and international normalized ratio (INR). In conclusion, elevated concentrations of IFN-γ represent a characteristic feature of liver disease severity regardless of underlying disease. Significant correlations with indices of hepatic dysfunction suggest that enhanced IFN-γ levels represent a consequence of liver dysfunction rather than of inflammatory disease.     

Ethyl pyruvate reduces hepatic mitochondrial swelling and dysfunction in a rat model of sepsis

Sepsis causes mitochondrial oxidative injury and swelling. Ethyl pyruvate (EP) is a cytoprotective agent, while aquaporin-8 (AQP8) is a mitochondrial water channel that can induce mitochondrial swelling. We assessed whether EP protects mitochondria during sepsis, and whether AQP8 contributes to the underlying mechanisms. A cecal ligation and puncture (CLP) sepsis model was established in Sprague-Dawley rats, randomized to 3 groups: sham (n=20), CLP (n=59) and CLP+EP (n=51). All rats received postoperative intraperitoneal fluid resuscitation (30 ml/kg); the CLP+EP group also received intraperitoneal EP (100 mg/kg). Survival was assessed at 24 hours. Hepatic mitochondrial ultrastructure was characterized by electron microscopy. The membrane potential of isolated hepatic mitochondria was determined using JC-1 and flow cytometry. Mitochondrial AQP8 expression and cytochrome C (Cyt C) release were measured by Western blotting (values normalized to ß-actin). Survival in the sham, CLP and CLP+EP groups was 100%, 21% and 41%, respectively. Mitochondrial cross-sectional area was smaller in the CLP+EP group than in the CLP group (0.231±0.110 vs. 0.641±0.460 µm²; P<0.001), with a tendency for a lower form factor (a measure of contour irregularity) in the CLP+EP group. Mitochondrial depolarization by CLP was inhibited by EP. Mitochondrial Cyt C release was higher in the CLP group than in the sham (1.211±0.24 vs. 0.48±0.03) or CLP+EP (0.35±0.39) groups. AQP8 expression was similar between groups, with a trend for lower expression in the CLP+EP group compared with the CLP group. EP improves sepsis outcome by targeting the mitochondrion, possibly through modulation of AQP8 expression.     

The A8296G mtDNA mutation associated with several mitochondrial diseases does not cause mitochondrial dysfunction in cybrid cell lines

Transmitochondrial cybrid cell lines homoplasmic for the A8296G mtDNA transition, a mutation associated with several mitochondrial diseases, have a normal oxidative phosphorylation function, as shown by oxygen consumption, lactate production, respiratory enzyme activities, and growth using galactose as the only source of energy. The synthesis of mitochondrial proteins is also similar in mutant and wild-type cybrids. Our results suggest that the A8296G mutation is a polymorphism and reinforce the necessity of performing functional studies to assess the pathogenicity of mtDNA mutations.     

Regulation of hepatic free fatty acid metabolism by glucagon and insulin.

The roles of glucagon and insulin in the direct short-term regulation of hepatic free fatty acid (FFA) metabolism were studied in hepatocytes isolated from fed, fasted, and streptozotocin-induced diabetic rats. In fed animals, the principal metabolic product of palmitate metabolism was triglyceride, whereas ketones were the major product in fasted and diabetic animals. Glucagon at physiological concentrations increased ketogenesis and decreased triglyceride synthesis from palmitate in hepatocytes from fed rats at FFA concentrations 1.0 mM or less. Insulin had no effect on FFA metabolism when present as the sole hormone, but could antagonize the actions of submaximal concentrations of glucagon. The metabolism of palmitate in fasted or diabetic hepatocytes was unaffected by either hormone. Ketogenesis from octanoate was also unaffected by hormone addition in all cell types. These data are consistent with a locus of hormonal regulation at a step prior to beta-oxidation of fatty acid. Glucagon and insulin may modulate FFA metabolism by both intrahepatic and extrahepatic mechanisms.     

Role of gluconeogenesis in epinephrine-stimulated hepatic glucose production in humans

To evaluate the contribution of gluconeogenesis to epinephrine-stimulated glucose production, we infused epinephrine (0.06 micrograms X kg-1 X min-1) for 90 min into normal humans during combined hepatic vein catheterization and [U-14C]alanine infusion. Epinephrine infusion produced a rise in blood glucose (50-60%) and plasma insulin (30-40%), whereas glucagon levels increased only at 30 min (19%, P less than 0.05). Net splanchnic glucose output transiently increased by 150% and then returned to base line by 60 min. In contrast, the conversion of labeled alanine and lactate into glucose increased fourfold and remained elevated throughout the epinephrine infusion. Similarly, epinephrine produced a sustained increase in the net splanchnic uptake of cold lactate (four- to fivefold) and alanine (50-80%) although the fractional extraction of both substrates by splanchnic tissues was unchanged. We conclude that a) epinephrine is a potent stimulator of gluconeogenesis in humans, and b) this effect is primarily mediated by mobilization of lactate and alanine from extrasplanchnic tissues. Our data suggest that the initial epinephrine-induced rise in glucose production is largely due to activation of glycogenolysis. Thereafter, the effect of epinephrine on glycogenolysis (but not gluconeogenesis) wanes, and epinephrine-stimulated gluconeogenesis becomes the major factor maintaining hepatic glucose production.     

A sequence variation in the mitochondrial glycerol-3-phosphate dehydrogenase gene is associated with increased plasma glycerol and free fatty acid concentrations among French Canadians

FAD-dependent glycerol-3-phosphate dehydrogenase (mGPD) enzyme is located in the mitochondrial inner membrane where it catalyzes irreversible oxidation reactions. Type 2 diabetes mellitus (DM) is a multifactorial disorder associated with physiological abnormalities in the glycerol and free fatty acids (FFA) metabolic pathways. In the present study, we have evaluated the association among the mGPD H264R sequence variation and postabsorptive plasma FFA and glycerol concentrations in a sample of French Canadians with and without type 2 DM. A sample of 81 recently diagnosed type 2 DM and 318 nondiabetic, nonobese, normotriglyceridemic French Canadians were screened for the presence of the mGPD H264R genetic variant using a PCR-RFLP-based method. The 318 nondiabetic subjects were free of known type 2 DM covariates (fasting glucose <7.0 mmol/L, body mass index <29 kg/m(2), fasting glycerol <2.0 mmol/L and absence of the N288D sequence variation in the glycerol kinase gene, fasting triglyceride <2.5 mmol/L). The association of mGPD H264R sequence variation with plasma FFA and glycerol concentrations was assessed in different regression models. Among non-DM individuals, the R allele (HR and RR genotypes) was associated with increased plasma FFA and glycerol concentrations (P < 0.05). However, the mean plasma FFA and glycerol concentrations were not affected by the H264R genotype in the type 2 DM sample. Overall, mean plasma FFA concentrations in non-DM RR homozygotes reached values that were similar to those achieved in patients with type 2 diabetes (0.87 +/- 0.63 vs 0.90 +/- 0.48 mmol/L). After controlling for age, gender, body mass index, fasting glucose, and fasting triglyceride concentrations, the relative odds of having fasting plasma FFA levels above the 90th percentile (0.9 mmol/L) in the absence of DM was increased by twofold in H264R heterozygotes (P = 0.04) and fourfold among R264 homozygotes (P = 0.009) compared to noncarriers. In the absence of DM, the mGPD R allele was also associated with higher plasma glycerol concentrations (P < 0.05). Results in non-DM individuals suggest that the mGPD R allele is associated with DM intermediate phenotypes. The absence of a relation between mGPD genotype and DM is in accordance with the view that DM is a complex phenotype in which increased plasma FFA or glycerol concentrations result from metabolic alterations which might obscure the effect of the mGPD polymorphism.