Liyong Chen

Lipid accumulation is ahead of epithelial-to-mesenchymal transition and therapeutic intervention by acetyl-CoA carboxylase 2 silence in diabetic nephropathy.

OBJECTIVE The study investigated the relationship between epithelial-to-mesenchymal transition (EMT) and lipotoxicity in diabetic nephropathy as well as the protective effect of acetyl-CoA carboxylase 2 (ACC2) silence. METHODS High glucose (30mmol/L) cultured human proximal tubular epithelial cells (HK-2 cells) were used. Triglyceride content, fatty acid β-oxidation rate, malonyl CoA content, and marker proteins of EMT, including E-cadherin (E-cad), α-smooth muscle actin (α-SMA) and transforming grow factor-β (TGF-β), were assessed. Silence of ACC2 was achieved by ACC2-shRNA lentivirus transfection. RESULTS In cultured human proximal tubular cells, high glucose induced fatty acid deposit before phenotypical and morphological changes of EMT. At 48h, more triglyceride content, more malonyl CoA content and lower fatty acid β-oxidation rate were detected. However, increased expression of TGF-β, accompanied by loss of E-cad and acquisition of α-SMA, was observed at 98h but not at 48h. The silence of ACC2 in HK-2 cells led to restored cell morphology with less lipid deposition and less malonyl-CoA content, which resulted from faster β-oxidation rate. CONCLUSION The progress of lipotoxicity participates in the development of diabetic nephropathy in early stage before EMT. The manipulation of lipid metabolism might act as a promising therapeutic intervention for diabetic nephropathy.

Acetyl-CoA carboxylase 2 suppression rescues human proximal tubular cells from palmitic acid induced lipotoxicity via autophagy.

Autophagy is a catabolic process that degrades damaged proteins and organelles in mammalian cells. Although acetyl-CoA carboxylase 2 (ACC2) plays a crucial role in the fatty acid metabolism, it keeps unknown whether ACC2 is associated with autophagic activity. The present work was designed to investigate the effects of ACC2 on palmitic acid (PA) induced lipotoxicity in human proximal tubular cells and the putative role of autophagy in this process. Here we show that autophagy was induced by PA in HK-2 cells. Moreover, the PA induced autophagy was regulated both by ACC2 suppression and CPTI inhibitor treatment, which represent an altered fatty acid β-oxidation. And the knockdown of ACC2 reduced PA-induced autophagy and thus protects the cells from PA-induced lipotoxicity with attenuated lipid accumulation and rescued cell viability. Collectively, the present study proposed a novel autophagy-involved mechanism of PA-induced renal lipotoxicity and provided potential therapeutic strategy by modulating lipid β-oxidation for diabetic nephropathy.

A meta-analysis comparing 18F-FLT PET with 18F-FDG PET for assessment of brain tumor recurrence.

ObjectiveThe purpose of this systematic meta-analysis was to evaluate the diagnostic accuracy of 3′-deoxy-3′-18F-fluorothymidine (18F-FLT) PET for the assessment of glioma recurrence and compare it with that of 18F-fluorodeoxyglucose (18F-FDG) PET. MethodsThe authors electronically and manually searched for studies from 1948 to 2014 that evaluated the diagnostic accuracy of 18F-FDG or 18F-FLT PET for glioma recurrence. The primary results of sensitivity, specificity, and diagnostic odds ratio (DOR) were summarized using the random-effects model. Summary receiver operating characteristic (ROC) curves and its area under the curve (AUC were used to summarize the overall diagnostic accuracy. Statistical analysis was performed with the software STATA (version 11.0). ResultsTwenty-four studies that included a total of 799 patients were included in the meta-analysis. The pooled sensitivity, specificity, DOR, and summary ROC AUC for the overall diagnostic accuracy of 18F-FDG PET were 0.78 (95% CI 0.69–0.85), 0.77 (95% CI 0.66–0.85), 12 (95% CI 6–22), and 0.84 (95% CI 0.81–0.87), respectively. The pooled sensitivity, specificity, DOR, and summary ROC AUC for the overall diagnostic accuracy of 18F-FLT PET were 0.82 (95% CI 0.51–0.95), 0.76 (95% CI 0.50–0.91), 15 (95% CI 4–56), and 0.85 (95% CI 0.81–0.88), respectively. Metaregression analysis showed that year of publication, male proportion, average age, and blinding review did not affect the test performance statistically significantly (all P>0.05). ConclusionThis meta-analysis indicates that PET by using 18F-FLT has a moderately better overall accuracy for diagnosing glioma recurrence compared with that by using 18F-FDG. Video abstract: http://links.lww.com/NMC/A41

The renoprotective role of autophagy activation in proximal tubular epithelial cells in diabetic nephropathy

With intensive investigations recently, autophagy is hoped to be a potential therapeutic target to prevent or alleviate diabetic nephropathy (DN). Our previous study revealed that lipotoxicity participated in epithelial-to-mesenchymal transition (EMT) of proximal tubular epithelial cells (PTECs) under diabetic conditions. Based on evidences that autophagy and lipid metabolism are closely related, we investigated autophagy under diabetic conditions and how it contributed in the lipotoxicity and EMT. In high-glucose-cultured PTECs, we found that Beclin1 and LC3-II were elevated, while p62 was decreased. These results indicate that autophagy activity was elevated under diabetic conditions. Autophagy deficiency induced by autophagy inhibitors, chloroquine diphosphate (CQ) and 3-Methyladenine (3-MA), and by Atg5 siRNA transfection exacerbated lipid accumulation and EMT. This supports that the elevated autophagy activity acts as a renoprotective response under diabetic conditions. Treatment of rapamycin, which is a mammalian target of rapamycin (mTOR) receptor-specific inhibitor and a known autophagy activator, attenuated high-glucose-induced lipid accumulation and EMT. The Atg5 silence counteracted the protective effect of rapamycin. The present study deepens our understanding of the role of autophagy in DN, suggesting a complex interplay of autophagy, metabolic pathways, lipotoxicity and EMT.

Autophagy downregulation contributes to insulin resistance mediated injury in insulin receptor knockout podocytes in vitro

It is unknown whether autophagy activity is altered in insulin resistant podocytes and whether autophagy could be a therapeutic target for diabetic nephropathy (DN). Here we used shRNA transfection to knockdown the insulin receptor (IR) gene in cultured human immortalized podocytes as an in vitro insulin resistant model. Autophagy related proteins LC3, Beclin, and p62 as well as nephrin, a podocyte injury marker, were assessed using western blot and immunofluorescence staining. Our results show that autophagy is suppressed when podocytes lose insulin sensitivity and that treatment of rapamycin, an mTOR specific inhibitor, could attenuate insulin resistance induced podocytes injury via autophagy activation. The present study deepens our understanding of the role of autophagy in the pathogenesis of DN.

Autophagy protects human podocytes from high glucose-induced injury by preventing insulin resistance

OBJECTIVE Insulin resistance is correlated with the progress of albuminuria in diabetic patients, and podocytes are crucial for maintaining the normal function of the glomerular filtration barrier. In the present study, we aimed to investigate the high glucose-induced insulin resistance and cell injury in human podocytes and the putative role of autophagy in this process. METHODS Human podocytes were cultured in high glucose-supplemented medium and low glucose and high osmotic conditions were used for the controls. Autophagy in the podocytes was regulated using rapamycin or 3-methyladenine stimulation. Next, autophagy markers including LC3B, Beclin-1, and p62 were investigated using western blot and qPCR, and the insulin responsiveness was analyzed based on glucose uptake and by using the phosphorylation of the insulin receptor with Nephrin as a podocyte injury marker. RESULTS The basal autophagy level decreased under the high glucose conditions, which was accompanied by a decrease in the glucose uptake and phosphorylation of the insulin receptor in the human podocytes. More interestingly, the glucose uptake and the phosphorylation of the insulin receptor were decreased by 3-MA stimulation and increased by rapamycin, illustrating that the responsiveness of insulin was regulated by autophagy. The activation of autophagy by rapamycin also ameliorated cell injury in the human podocytes. CONCLUSIONS The presence or activation of autophagy was found to play a protective role in human podocytes against high glucose-induced insulin resistance and cell injury, which indicates a novel cellular mechanism and provides a potential therapeutic target for diabetic nephropathy (DN).

Activation of the STING-IRF3 pathway promotes hepatocyte inflammation, apoptosis and induces metabolic disorders in nonalcoholic fatty liver disease

BACKGROUND Nonalcoholic fatty liver disease (NAFLD) is a common result of obesity and metabolic syndrome. Hepatocyte injury and metabolic disorders are hallmarks of NAFLD. Stimulator of interferon genes (STING) and its downstream factor interferon regulatory factor 3 (IRF3) trigger inflammatory reaction in response to the presence of cytosolic DNA. STING has recently been shown to play an important role in early alcoholic liver disease. However, little is known about the role of STING-IRF3 pathway in hepatocyte injury. Here, we aimed to examine the effect of STING-IRF3 pathway on hepatocyte metabolism, inflammation and apoptosis. METHODS We examined the activation of the STING-IRF3 pathway, a high-fat diet (HFD)-induced obese mouse model, and determined the role of this pathway in a free fatty acid (FFA)-induced hepatocyte inflammatory response, injury, and dysfunction in L-O2 human liver cells. RESULTS STING and IRF3 were upregulated in livers of HFD-fed mice and in FFA-induced L-O2 cells. Knocking down either STING or IRF3 led to a significant reduction in FFA-induced hepatic inflammation and apoptosis, as evidenced by modulation of the nuclear factor κB (NF-κB) signaling pathway, inflammatory cytokines, and apoptotic signaling. Additionally, STING/IRF3 knockdown enhanced glycogen storage and alleviated lipid accumulation, which were found to be associated with increased expression of hepatic enzymes in glycolysis and lipid catabolism, and attenuated expression of hepatic enzymes in gluconeogenesis and lipid synthesis. CONCLUSIONS Our results suggest that the STING-IRF3 pathway promotes hepatocyte injury and dysfunction by inducing inflammation and apoptosis and by disturbing glucose and lipid metabolism. This pathway may be a novel therapeutic target for preventing NAFLD development and progression.

Smoking is inversely related to cutaneous malignant melanoma: results of a meta‐analysis

DEAR EDITOR, Tobacco smoking poses a great global health burden to > 1 billion smokers and those subject to passive smoking, and is well known to be a causal factor in at least 12 types of cancer. In terms of cutaneous malignant melanoma (CMM), which was reported by the World Health Organization to account for 232 130 new cases and 55 489 deaths in 2012, its association with smoking has so far not been established. To date, only a few epidemiological studies have indicated a positive association, and, interestingly, the remaining majority reported statistically significant or nonsignificant inverse correlations. To shed light on this relationship, we report herein the results of our meta-analysis on the effects of smoking on CMM mortality and incidence. A systematic search of articles was conducted in MEDLINE, Embase and the Cochrane library, from their start dates to January 2015, with ‘melanoma’ OR ‘skin neoplasm’ OR ‘skin cancer’ in the title or abstract, AND ‘smok*’ OR ‘tobacco’ OR ‘cigar*’ OR ‘waterpipe’ OR ‘snuff’ in the full text in order to locate studies directly focused, or indirectly reporting, on smoking related to CMM. Studies were considered if data on smoking status were collected and could be tabulated with CMM, or indexes such as odds ratio (OR), relative risk (RR) and hazard ratio, with corresponding 95% confidence intervals (CIs), were reported. The largest or most recent reports were adopted in terms of repetition. Quality assessment of the studies by the Newcastle–Ottawa scale and data extraction procedures were performed by two independent reviewers; any discrepancy was resolved by discussion. As CMM is rare, we combined and also separately analysed data from case–control and cohort designs. A fixed-effect model was applied if the heterogeneity index I was < 50%; otherwise, a random effects model was adopted in pooling summary estimates. All statistical analyses were performed using RevMan Version 5.3 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark). The systematic search yielded 451 citations. By screening the titles and abstracts, the full text of 88 articles was deemed suitable for assessment. After the exclusion of publications containing irrelevant study types, duplicate reports and studies failing to obtain risk estimates (after contacting the corresponding authors three times), 23 studies were included (Table 1). The quality of the included studies was generally high or moderate, except for five studies, which had total scores < 6. Based on information from one study, which took CMM mortality as the outcome, and one that studied both incidence and mortality, pooled estimated RRs for smoking on CMM mortality were 0 79 (95% CI 0 67–0 92) and 0 91 (95% CI 0 80–1 04) for current and former smokers, respectively (no information on ever smoking was available). Figure 1 presents pooled estimates of smoking on CMM incidence. RR estimates were 0 70 (95% CI 0 63–0 78), 0 90 (95% CI 0 85–0 95) and 0 92 (95% CI 0 87–0 94) for current, former and ever smokers, respectively. Based on these result, an inverse association of smoking with CMM may be seen. This is further strengthened by exploring the dose–response relationship of some of the included studies. In the Health Professionals Follow-up Study cohort, the adjusted RR was 0 77 for men who smoked < 15 cigarettes daily and fell sharply to 0 32 for men who smoked more; the same pattern was also shown in women, although the adjusted estimates were weaker (1 0 and 0 94, respectively). Similar results were obtained in the cohort of Klatsky et al. and the case–control study of Westerdahl et al. Classification of the degree of smoking was set at none and 20 cigarettes daily. The unadjusted RRs fell from 0 9 to 0 6, and the adjusted ORs from 0 7 to 0 6, respectively. The dose–response studies of Østerlind et al. and Freedman et al. resulted in irregular trends but still showed a general inverse relationship for most subgroups. As a group I carcinogen, the traditional harmful impression of tobacco smoking gives rise to some explanations as to the observed ‘protective’ effect on CMM. In one simulation study, Thompson et al. demonstrated that competing risks from smoking-related noncommunicable diseases and cancers may result in an inverse association when smoking has no effect on melanoma. Cohort study results may suffer from this type of bias. Therefore, we separately analysed the results by study type. In cohort studies, the pooled RRs were 0 69 (95% CI 0 62–0 77), 0 88 (95% CI 0 77–1 01) and 0 92 (95% CI 0 83–1 01) for current, former and ever smokers, respectively. However, a similar trend was observed in case–control studies (not affected by competing risk): ORs were 0 70 (95% CI 0 57–0 86), 0 84 (95% CI 0 75–0 95) and 0 83 (95% CI 0 76–0 91) for the three smoking statuses, respectively. In addition, the observed inverse relations were also not influenced by design details, such as matching method and study base (all RR < 1 0). Sensitivity analysis of study quality by

Positive effects of resistant starch supplementation on bowel function in healthy adults: a systematic review and meta-analysis of randomized controlled trials.

Abstract Animal experimental studies have found that resistant starch can significantly improve bowel function, but the outcomes are mixed while conducting human studies. Thus, we conducted a systematic review and meta-analysis of randomized controlled trials to evaluate the relationship between resistant starch supplementation and large intestinal function. Three electronic databases (PubMed, Embase, Scopus) were searched to identify eligible studies. The standardized mean difference (SMD) or weighted mean difference (WMD) was calculated using a fixed-effects model or a random-effects model. The pooled findings revealed that resistant starch significantly increased fecal wet weight (WMD 35.51 g/d, 95% CI 1.21, 69.82) and butyrate concentration (SMD 0.61, 95% CI 0.32, 0.89). Also, it significantly reduced fecal PH (WMD −0.19, 95% CI −0.35, −0.03), but the increment of defecation frequency were not statistically significant (WMD 0.04stools/g, 95% CI −0.08, 0.16). To conclude, our study found that resistant starch elicited a beneficial effect on the function of large bowel in healthy adults.

Effects of omega-3 fatty acids on bone turnover markers in postmenopausal women: systematic review and meta-analysis

Abstract Aim: There is conflicting evidence regarding the effects of omega-3 fatty acids on bone turnover markers in postmenopausal women. Thus, we systematically reviewed the efficacy of omega-3 fatty acids by conducting a meta-analysis of available randomized controlled trials. Methods: PubMed, Embase, Cochrane Library and Scopus were searched in December 2016. The standardized mean difference (SMD) or weighted mean difference (WMD) and the corresponding 95% confidence intervals (CIs) were calculated using a fixed-effects model. Results: Eight trials were included in the present meta-analysis. The pooled findings did not identify significant decreases in bone-specific alkaline phosphatase (SMD −0.08, 95% CI −0.29 to 0.12, p = 0.429) and collagen type I cross-linked C-telopeptide (WMD 0 ng/ml, 95% CI −0.04 to 0.04, p = 0.899). There was a significant decrease in osteocalcin (WMD −0.86 ng/ml, 95% CI −1.68 to −0.04, p = 0.040) as compared with control. Conclusion: Omega-3 fatty acids reduced postmenopausal women’s serum osteocalcin. Further well-designed studies are needed to verify the effects of omega-3 fatty acids on bone mass density and other bone turnover markers in postmenopausal women. Clinical trial registration number: CRD42016053219 (https://www.crd.york.ac.uk/PROSPERO/).