Bromocriptine protects perilesional spinal cord neurons from lipotoxicity after spinal cord injury

Recent studies have revealed that lipid droplets accumulate in neurons after brain injury and evoke lipotoxicity,damaging the neurons.However,how lipids are metabolized by spinal cord neurons after spinal cord injury remains unclear.Herein,we investigated lipid metabolism by spinal cord neurons after spinal cord injury and identified lipid-lowering compounds to treat spinal cord injury.We found that lipid droplets accumulated in perilesional spinal cord neurons after spinal cord injury in mice.Lipid droplet accumulation could be induced by myelin debris in HT22 cells.Myelin debris degradation by phospholipase led to massive free fatty acid production,which increased lipid droplet synthesis,β-oxidation,and oxidative phosphorylation.Excessive oxidative phosphorylation increased reactive oxygen species generation,which led to increased lipid peroxidation and HT22 cell apoptosis.Bromocriptine was identified as a lipid-lowering compound that inhibited phosphorylation of cytosolic phospholipase A2 by reducing the phosphorylation of extracellular signal-regulated kinases 1/2 in the mitogen-activated protein kinase pathway,thereby inhibiting myelin debris degradation by cytosolic phospholipase A2 and alleviating lipid droplet accumulation in myelin debris-treated HT22 cells.Motor function,lipid droplet accumulation in spinal cord neurons and neuronal survival were all improved in bromocriptine-treated mice after spinal cord injury.The results suggest that bromocriptine can protect neurons from lipotoxic damage after spinal cord injury via the extracellular signal-regulated kinases 1/2-cytosolic phospholipase A2 pathway.

Insufficient TRPM5 Mediates Lipotoxicity-induced Pancreaticβ-cell Dysfunction

Objective:While the reduction of transient receptor potential channel subfamily M member 5(TRPM5)has been reported in islet cells from type 2 diabetic(T2D)mouse models,its role in lipotoxicity-induced pancreaticβ-cell dysfunction remains unclear.This study aims to study its role.Methods:Pancreas slices were prepared from mice subjected to a high-fat-diet(HFD)at different time points,and TRPM5 expression in the pancreaticβcells was examined using immunofluorescence staining.Glucose-stimulated insulin secretion(GSIS)defects caused by lipotoxicity were mimicked by saturated fatty acid palmitate(Palm).Primary mouse islets and mouse insulinoma MIN6 cells were treated with Palm,and the TRPM5 expression was detected using qRT-PCR and Western blotting.Palm-induced GSIS defects were measured following siRNA-based Trpm5 knockdown.The detrimental effects of Palm on primary mouse islets were also assessed after overexpressing Trpm5 via an adenovirus-derived Trpm5(Ad-Trpm5).Results:HFD feeding decreased the mRNA levels and protein expression of TRPM5 in mouse pancreatic islets.Palm reduced TRPM5 protein expression in a time-and dose-dependent manner in MIN6 cells.Palm also inhibited TRPM5 expression in primary mouse islets.Knockdown of Trpm5 inhibited insulin secretion upon high glucose stimulation but had little effect on insulin biosynthesis.Overexpression of Trpm5 reversed Palm-induced GSIS defects and the production of functional maturation molecules unique toβcells.Conclusion:Our findings suggest that lipotoxicity inhibits TRPM5 expression in pancreaticβcells both in vivo and in vitro and,in turn,drivesβ-cell dysfunction.

Lipotoxicity in the liver

Obesity due to excessive food intake and the lack of physical activity is becoming one of the most serious public health problems of the 21stcentury. With the increasing prevalence of obesity, non-alcoholic fatty liver disease is also emerging as a pandemic. While previously this pathophysiological condition was mainly attributed to triglyceride accumulation in hepatocytes,recent data show that the development of oxidative stress, lipid peroxidation, cell death, inflammation and fibrosis are mostly due to accumulation of fatty acids,and the altered composition of membrane phospholipids. In fact, triglyceride accumulation might play a protective role, and the higher toxicity of saturated or trans fatty acids seems to be the consequence of a blockade in triglyceride synthesis. Increased membrane saturation can profoundly disturb cellular homeostasis by impairing the function of membrane receptors,channels and transporters. However, it also inducesendoplasmic reticulum stress via novel sensing mechanisms of the organelle's stress receptors. The triggered signaling pathways in turn largely contribute to the development of insulin resistance and apoptosis. These findings have substantiated the lipotoxic liver injury hypothesis for the pathomechanism of hepatosteatosis.This minireview focuses on the metabolic and redox aspects of lipotoxicity and lipoapoptosis, with special regards on the involvement of endoplasmic reticulum stress responses.

Identification of a natural PLA2 inhibitor from the marine fungus Aspergillus sp.c1 for MAFLD treatment that suppressed lipotoxicity by inhibiting the IRE-1a/XBP-1s axis and JNK signaling

Lipotoxicity is a pivotal factor that initiates and exacerbates liver injury and is involved in the development of metabolic-associated fatty liver disease(MAFLD).However,there are few reported lipotoxicity inhibitors.Here,we identified a natural anti-lipotoxicity candidate,HN-001,from the marine fungus Aspergillus sp.C1.HN-001 dose-and time-dependently reversed palmitic acid(PA)-induced hepatocyte death.This protection was associated with IRE-1a-mediated XBP-1 splicing inhibition,which resulted in suppression of XBP-1s nuclear translocation and transcriptional regulation.Knockdown of XBP-1s attenuated lipotoxicity,but no additional ameliorative effect of HN-001 on lipotoxicity was observed in XBP-1s knockdown hepatocytes.Notably,the ER stress and lipotoxicity amelioration was associated with PLA2.Both HN-001 and the PLA2 inhibitor MAFP inhibited PLA2 activity,reduced lysophosphatidylcholine(LPC)level,subsequently ameliorated lipotoxicity.In contrast,overexpression of PLA2 caused exacerbation of lipotoxicity and weakened the anti-lipotoxic effects of HN-001.Additionally,HN-001 treatment suppressed the downstream pro-apoptotic JNK pathway.In vivo,chronic administration of HN-001(i.p.)in mice alleviated all manifestations of MAFLD,including hepatic steatosis,liver injury,inflammation,and fibrogenesis.These effects were correlated with PLA2/IRE-1a/XBP-1s axis and JNK signaling suppression.These data indicate that HN-001 has therapeutic potential for MAFLD because it suppresses lipotoxicity,and provide a natural structural basis for developing anti-MAFLD candidates.

The role of fatty acid metabolism and lipotoxicity in pancreatic β-cell injury:Identification of potential therapeutic targets

Over the last 20 years,intensive research has been focused on the specific mechanisms mediating the pancreatic β-cell injury.Both the decreased viability and the dysfunction of β-cells have become the key factors in the development of dia betes mellitus.Thus,it is of utmost importance to elucidate the discrete pathological changes in pancreatic β-cells within the context of the various lipotoxicity models.The goal of these studies is to generate evidence to improve not only the clinical treatment for dia betics,but also modulate the diet and activities of groups at high risk for diabetes.In this regard,we review the role of lipotoxicity in pancreatic β-cell injury and identify potential therapeutic targets in this cell model.

The role of lipotoxicity in cardiovascular disease

Fatty acids are the primary fuel for cardiac muscle.The physiological equilibrium of lipid uptake and oxidation may aid in the prevention of excessive lipid accumulation.Several pathological states,such as myocardial ischemia,obesity,and insulin resistance,are routinely associated with disorders of lipid metabolism.There is growing evidence that certain types of lipids trigger cardiac lipotoxicity and ultimately heart failure.This review focuses on recent advances in the pathogenesis of lipotoxic cardiomyopathy and the treatment prospects for the repair of cardiac damage caused by lipotoxicity.

Nutrition, insulin resistance and dysfunctional adipose tissue determine the different components of metabolic syndrome

Obesity is an excessive accumulation of body fat that may be harmful to health. Today, obesity is a major public health problem, affecting in greater or lesser proportion all demographic groups. Obesity is estimated by body mass index(BMI) in a clinical setting, but BMI reports neither body composition nor the location of excess body fat. Deaths from cardiovascular diseases, cancer and diabetes accounted for approximately 65% of all deaths, and adiposity and mainly abdominal adiposity are associated with all these disorders. Adipose tissue could expand to inflexibility levels. Then, adiposity is associated with a state of low-grade chronic inflammation, with increased tumor necrosis factor-α and interleukin-6 release, which interfere with adipose cell differentiation, and the action pattern of adiponectin and leptin until the adipose tissue begins to be dysfunctional. In this state the subject presents insulin resistance and hyperinsulinemia, probably the first step of a dysfunctional metabolic system. Subsequent to central obesity, insulin resistance, hyperglycemia, hypertriglyceridemia, hypoalphalipoproteinemia, hypertension and fatty liver are grouped in the so-called metabolic syndrome(MetS). In subjects with MetS an energy balance is critical to maintain a healthy body weight, mainly limiting the intake of high energy density foods(fat). However, high-carbohydrate rich(CHO) diets increase postprandial peaks of insulin and glucose. Triglyceride-rich lipoproteins are also increased, which interferes with reverse cholesterol transport lowering highdensity lipoprotein cholesterol. In addition, CHO-rich diets could move fat from peripheral to central deposits and reduce adiponectin activity in peripheral adipose tissue. All these are improved with monounsaturated fatty acid-rich diets. Lastly, increased portions of ω-3 and ω-6 fatty acids also decrease triglyceride levels, and complement the healthy diet that is recommended in patients with MetS.

Lean heart: Role of leptin in cardiac hypertrophy and metabolism

Leptin is an adipokine that has been linked with the cardiovascular complications resulting from obesity such as hypertension and heart disease. Obese patients have high levels of circulating leptin due to increased fat mass. Clinical and population studies have correlated high levels of circulating leptin with the development of cardiac hypertrophy in obesity. Leptin has also been demonstrated to increase the growth of cultured cardiomyocytes. However, several animal studies of obese leptin deficient mice have not supported a role for leptin in promoting cardiac hypertrophy so the role of leptin in this pathological process remains unclear. Leptin is also an important hormone in the regulation of cardiac metabolism where it supports oxidation of glucose and fatty acids. In addition, leptin plays a critical role in protecting the heart from excess lipid accumulation and the formation of toxic lipids in obesity a condition known as cardiac lipotoxicity. This paper focuses on the data supporting and refuting leptin's role in promoting cardiac hypertrophy as well as its important role in the regulation of cardiac metabolism and protection against cardiac lipotoxicity.

Lipidomics in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease(NAFLD),the most common chronic liver disorder in Western countries,comprises steatosis to nonalcoholic steatohepatitis(NASH),with the latter having the potential to progress to cirrhosis.The transition from isolated steatosis to NASH is still poorly understood,but lipidomics approach revealed that the hepatic lipidome is extensively altered in the setting of steatosis and steatohepatitis and these alterations correlate with disease progression.Recent data suggest that both quantity and quality of the accumulated lipids are involved in pathogenesis of NAFLD.Changes in glycerophospholipid,sphingolipid,and fatty acid composition have been described in both liver biopsies and plasma of patients with NAFLD,implicating that specific lipid species are involved in oxidative stress,inflammation,and cell death.In this article,we summarize the findings of main human lipidomics studies in NAFLD and delineate the currently available information on the pathogenetic role of each lipid class in lipotoxicity and disease progression.

Pathophysiological mechanisms involved in non-alcoholic steatohepatitis and novel potential therapeutic targets

Non-alcoholic fatty liver disease(NAFLD) is a major health care problem and represents the hepatic expression of the metabolic syndrome. NAFLD is classified as nonalcoholic fatty liver(NAFL) or simple steatosis,and non-alcoholic steatohepatitis(NASH). NASH is characterized by the presence of steatosis and inflammation with or without fibrosis. The physiopathology of NAFL and NASH and their progression to cirrhosis involve several parallel and interrelated mechanisms,such as,insulin resistance(IR),lipotoxicity,inflammation,oxidative stress,and recently the gut-liver axis interaction has been described. Incretin-based therapies could play a role in the treatment of NAFLD. Glucagon-like peptide-1(GLP-1) is an intestinal mucosa-derived hormone which is secreted into the bloodstream in response to nutrient ingestion; it favors glucose-stimulated insulin secretion,inhibition of postprandial glucagon secretion and delayed gastric emptying. It also promotes weight loss and is involved in lipid metabolism. Once secreted,GLP-1 is quickly degraded by dipeptidyl peptidase-4(DPP-4). Therefore,DPP-4 inhibitors are able to extend the activity of GLP-1. Currently,GLP-1 agonists and DPP-4 inhibitors represent attractive options for the treatment of NAFLD and NASH. The modulation of lipid and glucose metabolism through nuclear receptors,such as the farsenoid X receptor,also constitutes an attractive therapeutic target. Obeticholic acid is a potent activator of the farnesoid X nuclear receptor and reduces liver fat content and fibrosis in animal models. Ursodeoxycholic acid(UDCA) is a hydrophilic bile acid with immunomodulatory,antiinflammatory,antiapoptotic,antioxidant and antifibrotic properties. UDCA can improve IR and modulate lipid metabolism through its interaction with nuclear receptors such as,TGR5,farnesoid X receptor-a,or the small heterodimeric partner. Finally,pharmacologic modulation of the gut microbiota could have a role in the therapy of NAFLD and NASH. Probiotics prevent bacterial translocation and epithelial invasion,inhibit mucosal adherence by bacteria,and stimulate host immunity. In animal models,probiotics prevent obesity,decrease transaminase levels,and improve IR and liver histology in NASH.

Apoptosis of Pancreatic Beta Cells in Pregnant Insulin-resistant Rats Fed with High-fat Diet

Objective The aim of this study is by observing the number change of islets beta cells in gestational rats exposed to high fat diet, tofurther reveal the mechanism of gestational diabetes mellitus. Methods Female Wistar rats were exposed to high fat diet for five weeks, and then became pregnant. During pregnancy dynamically detected indicators of glucose and fat. Until the third trimester of pregnancy evaluated the sensitivity of insulin and glucose tolerance. After executed rats, selected pancreatic tail tissue and fixed, further slides were stained with insulin antibody by immunohistochemistry to confirm the location of beta cells. Image analysis system determined mean area stained positive cells in each islet, which stood for total number of beta cells. The apoptotic beta cells in islet were detected and quantified by the Tunel technology to calculate apoptosis ratio. Results The level of free fatty acids in rats exposed to high fat diet was significantly higher than the control groups, and insulin resistance was more serious. Compared mean stained positive area among each group, the largest was gestational rats fed high fat diet, and gestational rats was larger than virgin rats, but the difference had no statistical significance. About apoptoticratio of beta cells was higher in diet intervened rats, gestational rats were higher than virgin rats. The same trend happened in the number of positive cells, but discrepancy was not remarkable. Conclusion Based on insulin resistance, apoptosis of pancreatic beta cellsincreased in gestational ratstaking high fat diet, through changing the number of beta cells to down regulate the pancreas endocrine function. That may be the mechanism of gestational mellitus.

A key problem and challenge for hepatology:Obesity-related metabolic liver diseases

With the arrival of the new millennium,gastroenterologists have been faced with the problem of metabolic liver diseases associated with obesity.The active role of the liver in metabolism and inflammation make it a key organ in the war against the rapidly-spreading worldwide epidemic of obesity.Many lives and much money could be saved if the work of hepatologists led to the development of effective diagnostic and therapeutic strategies against this growing leader of cirrhosis.

Human skeletal muscle perilipin 2 and 3 expression varies with insulin sensitivity

Background: Impaired insulin sensitivity may partly arise from a dysregulated lipid metabolism in human skeletal muscle. This study investigates the expression levels of perilipin 2, 3, and 5, and four key lipases in human skeletal muscle from the subjects that exhibit a range from normal to very low insulin sensitivity. Methods: 25 middle aged male participants were matched for lean body mass and recruited into three groups;type 2 diabetes patients (T2D), impaired glucose tolerance (IGT), and healthy sedentary controls (CON) according to their glucose tolerance and VO2peak. A muscle biopsy was obtained from vastus lateralis, and a two-step sequential euglycaemic-hyperinsulinaemic clamp was performed. Muscle samples were analyzed by Western blot for expression of perilipin 2, 3, 5, adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), endothelial lipase (EL) and lipoprotein lipase (LPL). Results: Perilipin 3 expression was higher in T2D compared to CON. Perilipin 2 expression was higher in CON than T2D. We observed no difference in expression of perili pin 5, ATGL, HSL, EL or LPL between the groups. Conclusions: In the present study the muscle perilipin 3 expression and perilipin 2 expression varied markedly with insulin sensitivity. This difference in perilipin expression may indicate that the lipid droplet function and thus storage and release of fatty acid-vary with insulin sensitivity.

Effect of changing the proportion of C16:0 and cis-9 C18:1 in fat supplements on rumen fermentation,glucose and lipid metabolism,antioxidation capacity,and visceral fatty acid profile in finishing Angus bulls

This study evaluated the effects of different proportions of palmitic(C16:0)and oleic(cis-9 C18:1)acids in fat supplements on rumen fermentation,glucose(GLU)and lipid metabolism,antioxidant function,and visceral fat fatty acid(FA)composition in Angus bulls.The design of the experiment was a randomized block design with 3 treatments of 10 animals each.A total of 30 finishing Angus bulls(21±0.5 months)with an initial body weight of 626±69 kg were blocked by weight into 10 blocks,with 3 bulls per block.The bulls in each block were randomly assigned to one of three experimental diets:(1)control diet without additional fat(CON),(2)CON+2.5%palmitic calcium salt(PA;90%C16:0),(3)CON+2.5%mixed FA calcium salts(MA;60%C16:0+30%cis-9 C18:1).Both fat supplements increased C18:0 and cis-9 C18:1 in visceral fat(P<0.05)and up-regulated the expression of liver FA transport protein 5(FATP5;P<0.001).PA increased the insulin concentration(P<0.001)and aspartate aminotransferase activity(AST;P=0.030)in bull's blood while reducing the GLU concentration(P=0.009).PA increased the content of triglycerides(TG;P=0.014)in the liver,the content of the C16:0 in visceral fat(P=0.004),and weight gain(P=0.032),and up-regulated the expression of liver diacylglycerol acyltransferase 2(DGAT2;P<0.001)and stearoyl-CoA desaturase 1(SCD1;P<0.05).MA increased plasma superoxide dismutase activity(SOD;P=0.011),reduced the concentration of acetate and total volatile FA(VFA)in rumen fluid(P<0.05),and tended to increase plasma non-esterified FA(NEFA;P=0.069)concentrations.Generally,high C16:0 fat supplementation increased weight gain in Angus bulls and triggered the risk of fatty liver,insulin resistance,and reduced antioxidant function.These adverse effects were alleviated by partially replacing C16:0 with cis-9 C18:1.

Rab18 maintains homeostasis of subcutaneous adipose tissue to prevent obesity-induced metabolic disorders

Metabolically healthy obesity refers to obese individuals who do not develop metabolic disorders.These people store fat in subcutaneous adipose tissue(SAT)rather than in visceral adipose tissue(VAT).However,the molecules participating in this specific scenario remain elusive.Rab18,a lipid droplet(LD)-associated protein,mediates the contact between the endoplasmic reticulum(ER)and LDs to facilitate LD growth and maturation.In the present study,we show that the protein level of Rab18 is specifically upregulated in the SAT of obese people and mice.Rab18 adipocyte-specific knockout(Rab18 AKO)mice had a decreased volume ratio of SAT to VAT compared with wildtype mice.When subjected to high-fat diet(HFD),Rab18 AKO mice had increased ER stress and inflammation,reduced adiponectin,and decreased triacylglycerol(TAG)accumulation in SAT.In contrast,TAG accumulation in VAT,brown adipose tissue(BAT)or liver of Rab18AKO mice had a moderate increase without ER stress stimulation.Rab18 AKO mice developed insulin resistance and systematic inflammation.Rab18 AKO mice maintained body temperature in response to acute and chronic cold induction with a thermogenic SAT,similar to the counterpart mice.Furthermore,Rab18-deficient 3T3-L1 adipocytes were more prone to palmitate-induced ER stress,indicating the involvement of Rab18 in alleviating lipid toxicity.Rab18 AKO mice provide a good animal model to investigate metabolic disorders such as impaired SAT.In conclusion,our studies reveal that Rab18 is a key and specific regulator that maintains the proper functions of SAT by alleviating lipid-induced ER stress.

Nuclear factor-Y mediates pancreatic β-cell compensation by repressing reactive oxygen species-induced apoptosis under metabolic stress

Background:Pancreaticβ-cells elevate insulin production and secretion through a compensatory mechanism to override insulin resistance under metabolic stress conditions.Deficits inβ-cell compensatory capacity result in hyperglycemia and type 2 diabetes(T2D).However,the mechanism in the regulation ofβ-cell compensative capacity remains elusive.Nuclear factor-Y(NF-Y)is critical for pancreatic islets’homeostasis under physiological conditions,but its role inβ-cell compensatory response to insulin resistance in obesity is unclear.Methods:In this study,using obese(ob/ob)mice with an absence of NF-Y subunit A(NF-YA)inβ-cells(ob,Nf-yaβKO)as well as rat insulinoma cell line(INS1)-based models,we determined whether NF-Y-mediated apoptosis makes an essential contribution toβ-cell compensation upon metabolic stress.Results:Obese animals had markedly augmented NF-Y expression in pancreatic islets.Deletion ofβ-cell Nf-ya in obese mice worsened glucose intolerance and resulted inβ-cell dysfunction,which was attributable to augmentedβ-cell apoptosis and reactive oxygen species(ROS).Furthermore,primary pancreatic islets from Nf-yaβKO mice were sensitive to palmitate-inducedβ-cell apoptosis due to mitochondrial impairment and the attenuated antioxidant response,which resulted in the aggravation of phosphorylated c-Jun N-terminal kinase(JNK)and cleaved caspase-3.These detrimental effects were completely relieved by ROS scavenger.Ultimately,forced overexpression of NF-Y in INS1β-cell line could rescue palmitate-inducedβ-cell apoptosis,dysfunction,and mitochondrial impairment.Conclusion:Pancreatic NF-Y might be an essential regulator ofβ-cell compensation under metabolic stress.

Mechanisms of insulin resistance in obesity

Obesity increases the risk for type 2 diabetes through induction of insulin resistance.Treatment of type 2 diabetes has been limited by little translational knowledge of insulin resistance although there have been several well-documented hypotheses for insulin resistance.In those hypotheses,inflammation,mitochondrial dysfunction,hyperinsulinemia and lipotoxicity have been the major concepts and have received a lot of attention.Oxidative stress,endoplasmic reticulum(ER)stress,genetic background,aging,fatty liver,hypoxia and lipodystrophy are active subjects in the study of these concepts.However,none of those concepts or views has led to an effective therapy for type 2 diabetes.The reason is that there has been no consensus for a unifying mechanism of insulin resistance.In this review article,literature is critically analyzed and reinterpreted for a new energy-based concept of insulin resistance,in which insulin resistance is a result of energy surplus in cells.The energy surplus signal is mediated by ATP and sensed by adenosine monophosphate-activated protein kinase(AMPK)signaling pathway.Decreasing ATP level by suppression of production or stimulation of utilization is a promising approach in the treatment of insulin resistance.In support,many of existing insulin sensitizing medicines inhibit ATP production in mitochondria.The effective therapies such as weight loss,exercise,and caloric restriction all reduce ATP in insulin sensitive cells.This new concept provides a unifying cellular and molecular mechanism of insulin resistance in obesity,which may apply to insulin resistance in aging and lipodystrophy.

Hepatocyte nuclear factor 4α in the pathogenesis of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is emerging as the most common chronic liver disease worldwide. It refers to a range of liver conditions affecting people who drink little or no alcohol. NAFLD comprises non-alcoholic fatty liver and non-alcoholic steatohepatitis (NASH), the more aggressive form of NAFLD. NASH is featured by steatosis, lobular inflammation, hepatocyte injury, and various degrees of fibrosis. Although much progress has been made over the past decades, the pathogenic mechanism of NAFLD remains to be fully elucidated. Hepatocyte nuclear factor 4α (HNF4α) is a nuclear hormone receptor that is highly expressed in hepatocytes. Hepatic HNF4α expression is markedly reduced in NAFLD patients and mouse models of NASH. HNF4α has been shown to regulate bile acid, lipid, glucose, and drug metabolism. In this review, we summarize the recent advances in the understanding of the pathogenesis of NAFLD with a focus on the regulation of HNF4α and the role of hepatic HNF4α in NAFLD. Several lines of evidence have shown that hepatic HNF4α plays a key role in the initiation and progression of NAFLD. Recent data suggest that hepatic HNF4α may be a promising target for treatment of NAFLD.

Qushi Huayu Decoction (祛湿化瘀方) Inhibits Protein and Gene Expression of Cathepsin B in HepG2 Cells Induced by Free Fatty Acids

Objective： To study the experimental efficacy of Qushi Huayu Decoction （祛湿化瘀方,QHD） on protein and gene expression of cathepsin B （ctsb） in HepG2 cells induced by free fatty acids （FFAs）.Methods： The model of HepG2 steatosis and tumor necrosis factor-α （TNF-α） secretion was induced by long-chain FFAs.HepG2 cells were divided into 4 groups： control group （group C）,model group （group M）,low-dose QHD group （group L） and high-dose QHD group （group H ）.Long-chain FFAs were added to groups M,L and H.The 10% blank-control serum was added to group C and M,while 5% and 10% QHD-containing sera were added to group L and H,respectively.The levels of serum TNF-α and cellular triglyceride （TG） were detected.Cellular p-IκB and ctsb expression were detected using Western blot and PCR.The expression and distribution of ctsb were observed by immunofluorescence.Results： After incubating with FFA for 24 h,TG deposition in HepG2,TNF-α content in cell supernatant,the protein expression of cellular ctsb and P-IκB,as well as mRNA expression of ctsb increased markedly in group M compared with group C （P〈0.05,P〈0.01）.Compared with group M,TG deposition,the expression of cellular ctsb,P-IκB and ctsb mRNA in groups L and H,as well as TNF-α content in group H,decreased significantly （P〈0.05）.Cell immunochemical fluorescence studies showed that ctsb was released from lysosomes and distributed in the cytoplasm extensively and diffusedly after being stimulated with FFA.In this study,these above-mentioned changes were inhibited markedly in groups L and H.Conclusion： QHD might have a direct inhibitory effect on the ctsb target in the FFA-ctsb-TNFα pathway of hepatic lipotoxicity.

Sangguayin preparation prevents palmitate-induced apoptosis by suppressing endoplasmic reticulum stress and autophagy in db/db mice and MIN6 pancreatic β-cells

Sangguayin preparation(SGY-P) is refined from the traditional Chinese medicinal compound Sangguayin, which"clears heat and promotes fluid" and "tonifies kidney and spleen" for "Xiaoke", commonly known as ‘Diabetes mellitus’ in clinics.Previous studies have shown that SGY-P could reduce insulin resistance and repair damaged pancreas in db/db mice, but the underlying mechanisms were unclear. Here, we investigated whether treatment with SGY-P could protect pancreatic β-cells from apoptosis and uncovered the underlying mechanisms. db/db mice were used to observe the hypoglycemic and islet protective effect in vivo. Apoptosis was induced in mouse insulinoma 6(MIN6) cells by palmitate, following which the cells were treated with SGY-P for elucidating the anti-apoptotic mechanism in vitro. Cell viability and nuclear morphology were detected by CCK-8 assay and Hoechst 33258 staining. The expression levels of apoptosis-, endoplasmic reticulum(ER) stress-, and autophagy-related proteins were measured by western blot. The results showed that SGY-P reduced fasting blood glucose, pancreatic pathological changes, and islet β-cell apoptosis in db/db mice. Palmitate-induced apoptosis in MIN6 cells was decreased by SGY-P treatment. Hence, SGY-P therapy exhibited a protective effect on pancreatic β-cells by decreasing the expression of cleaved caspase-3, cleaved PARP and Bax, and increasing Bcl-2 by suppressing ER stress(Bip/XBP1/IRE1α/CHOP/Caspase-12) and autophagy(LC3/p62/Atg5) pathways.2/Atg5 pathways.