Overexpression of peroxisome proliferator‐activated receptor γ and retinoid X receptor α in gastric carcinomatous tissue

OBJECTIVE: To investigate the expression of peroxisome proliferator‐activated receptor γ (PPAR‐γ) and retinoid X receptor α (RXR‐α) in chronic gastritis, gastric mucosal dysplasia and gastric carcinoma and to identify any correlations between PPAR‐γ and RXR‐α expression in this progression sequence. METHODS: Immunohistochemical methods (avidin? biotin?peroxidase complex) were used to examine the expression of PPAR‐γ and RXR‐α in 53 patients with gastric carcinoma, 18 with gastric mucosal dysplasia and 30 with chronic atrophic gastritis. Thirty‐one patients with chronic non‐atrophic gastritis acted as controls. RESULTS: The positive rates of PPAR‐γ and RXR‐α in gastric carcinoma were 41.5 and 54.7%, 27.8 and 38.9% in gastric mucosal dysplasia, 10.0 and 20.0% in chronic atrophic gastritis, and 6.5 and 16.1% in chronic non‐atrophic gastritis, respectively. The expression of PPAR‐γ and RXR‐α increased during the progression from chronic non‐atrophic gastritis to chronic atrophic gastritis, then to gastric carcinoma. Compared with chronic gastritis, the expression of PPAR‐γ and RXR‐α in gastric mucosal dysplasia and gastric carcinoma was significantly increased (P < 0.05, P < 0.01). In gastric carcinoma, the expression of PPAR‐γ and RXR‐α was not associated with tumor cell differentiation or metastasis in the lymph nodes (P > 0.05). There was a positive correlation between the expression of PPAR‐γ and RXR‐α in gastric carcinoma (r= 0.54, P < 0.01). CONCLUSIONS: Overexpression of PPAR‐γ and RXR‐α protein is apparent in human gastric cancer. This might be an early event in carcinogenesis, and both PPAR‐γ and RXR‐α may play independent and/or synergistic roles in the progression of gastric carcinoma.     

Effects of γ‐interferon gene‐modified hepatocytes on murine implanted liver carcinoma

OBJECTIVE : Cancer immunotherapy and gene therapy are attractive approaches that have been widely investigated in different types of cancer. The present study examined the therapeutic effects of intrasplenically transplanted γ‐interferon (IFN‐γ) gene‐modified hepatocytes on murine implanted liver carcinoma. METHODS : Embryonic murine hepatocytes (BNL.CL2) were transfected with a recombinant adenovirus encoding IFN‐γ; two cell lines, BNL.LacZ and BNL.CL2, were used as controls. One week after intrasplenic C26 (colon carcinoma) cells were injected, 60 tumor‐bearing syngeneic mice underwent the intrasplenic transplantation of IFN‐γ gene‐modified hepatocytes and were divided into treatment (BNL.IFN‐γ) and control groups (BNL.LacZ and BNL.CL2). Two weeks later, the serum levels of IFN‐γ, tumor necrosis factor‐α (TNF‐α) and nitric oxide (NO) in the implanted liver carcinoma‐bearing mice were assayed, the cytotoxicity of splenic cytotoxic T lymphocytes (CTL) were measured, and the mor‐phology of the hepatic tumors was studied to evaluate the therapeutic effects of the treatment. RESULTS : In the treatment group, the serum levels of IFN‐γ, TNF‐α and NO increased significantly (P < 0.01), and the splenic CTL activity also increased markedly (P < 0.01), accompanied by a substantial decrease in tumor volume and an increase in survival. CONCLUSIONS : These data indicate that the IFN‐γ recombinant adenovirus was able to exert potent therapeutic effects and that the intrasplenic transplantation of adenovirus‐mediated IFN‐γ gene‐ modified hepatocytes could be used as a treatment for implanted liver carcinoma.     

Agrocybe aegerita polysaccharide combined with chemotherapy improves tumor necrosis factor‐α and interferon‐γ levels in rat esophageal carcinoma

Natural compounds have generated great interest as alternative treatments of diseases like cancer. Here, we investigated the anti‐tumor mechanism of one such compound, Agrocybe aegerita polysaccharide, by assessing expression of tumor necrosis factor‐α (TNF‐α) and interferon‐γ (IFN‐γ) in rat esophageal carcinoma (EC). EC was induced in healthy Wistar rats by methyl‐n‐amyl nitrosamine. Subsequently, rats were administered cancer treatment daily for 4 weeks, as follows: the normal control group (the only group not treated with methyl‐n‐amyl nitrosamine) and model group received only distilled water; the chemotherapy group received tegafur treatment; and the combination group received tegafur combined with A. aegerita polysaccharide. In normal and combination groups, body weight increased gradually after each week of treatment (P < 0.05), while body weights did not change in model and chemotherapy groups. Using enzyme linked immunosorbent assay, we found serum TNF‐α was lower in the combination group (31.56 ± 7.20 pg/L) than either the model (46.24 ± 8.52 pg/L) or chemotherapy (52.39 ± 9.16 pg/L) group, and, while higher, was more similar to the normal controls (25.08 ± 2.93 pg/L; P < 0.05), a finding that was confirmed by the immunohistochemistry of esophageal samples. In contrast, serum IFN‐γ was higher in the combination group (97.20 ± 10.92 pg/L) than in either the model (76.11 ± 11.92 pg/L) or chemotherapy (76.04 ± 9.85 pg/L) group, but lower than in the normal group (117.56 ± 10.88; P < 0.05), also confirmed by immunohistochemistry. Therefore, Agrocybe aegerita polysaccharide, when combined with chemotherapy, can regulate immune function in EC, potentially by modulating cytokine activity, specifically downregulation of TNF‐α and upregulation of IFN‐γ.     

Increased apoptosis in HepG2.2.15 cells with hepatitis B virus expression by synergistic induction of interferon‐γ and tumour necrosis factor‐α

Background: Interferon‐γ (IFN‐γ) and tumour necrosis factor‐α (TNF‐α) were thought to be important immune mediators in host defence against hepatitis B virus (HBV) infection. Aims: To examine the synergistic effect of IFN‐γ and TNF‐α on HBV‐expressing HepG2.2.15 cells and its potential mechanisms. Methods: Cell viability was quantitatively measured by 3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5‐diphenyl tetrazolium bromide assay. Cell morphology was captured using light microscopy. The typical DNA ladder test was performed using agarose gel electrophoresis. HBsAg and HBeAg titre changes were quantified by the enzyme‐linked immunosorbent assay method. Gene expression was analysed using cDNA macroarrays. Results: Interferon‐γ (1000 U/ml) alone or combined with TNF‐α (5 ng/ml) treatment resulted in apoptosis in HepG2.2.15 cells, but no significant apoptosis in the parent non‐virus expressing HepG2 cells. IFN‐γ‐ and TNF‐α‐mediated apoptosis was reduced by lamivudine treatment in HepG2.2.15 cells. IFN‐γ combined with TNF‐α reduced the titre of hepatitis B surface antigen and hepatitis B e antigen in the HepG2.2.15 cell line. For apoptosis‐related gene changes, IFN regulatory factor 1 (IRF‐1) (12.2‐fold), c‐myc (V00568 4.7‐fold, L00058 2.4‐fold) and caspase 7 (2.3‐fold) genes were upregulated in the combination treatment group. Conclusion: Interferon‐γ and TNF‐α play a role in the cell death of HBV‐expressing HepG2.2.15 cells. Expression of HBV leads to IFN‐γ‐ and TNF‐α‐mediated apoptosis in the cells. Increased IRF‐1, c‐myc and caspase 7 gene expression may be responsible for the synergistic induction of apoptosis by IFN‐γ and TNF‐α.     

Melatonin prevents Drp1‐mediated mitochondrial fission in diabetic hearts through SIRT1‐PGC1α pathway

Myocardial contractile dysfunction is associated with an increase in mitochondrial fission in patients with diabetes. However, whether mitochondrial fission directly promotes diabetes‐induced cardiac dysfunction is still unknown. Melatonin exerts a substantial influence on the regulation of mitochondrial fission/fusion. This study investigated whether melatonin protects against diabetes‐induced cardiac dysfunction via regulation of mitochondrial fission/fusion and explored its underlying mechanisms. Here, we show that melatonin prevented diabetes‐induced cardiac dysfunction by inhibiting dynamin‐related protein 1 (Drp1)‐mediated mitochondrial fission. Melatonin treatment decreased Drp1 expression, inhibited mitochondrial fragmentation, suppressed oxidative stress, reduced cardiomyocyte apoptosis, improved mitochondrial function and cardiac function in streptozotocin (STZ )‐induced diabetic mice, but not in SIRT 1^?/? diabetic mice. In high glucose‐exposed H9c2 cells, melatonin treatment increased the expression of SIRT 1 and PGC ‐1α and inhibited Drp1‐mediated mitochondrial fission and mitochondria‐derived superoxide production. In contrast, SIRT 1 or PGC ‐1α siRNA knockdown blunted the inhibitory effects of melatonin on Drp1 expression and mitochondrial fission. These data indicated that melatonin exerted its cardioprotective effects by reducing Drp1‐mediated mitochondrial fission in a SIRT 1/PGC ‐1α‐dependent manner. Moreover, chromatin immunoprecipitation analysis revealed that PGC ‐1α directly regulated the expression of Drp1 by binding to its promoter. Inhibition of mitochondrial fission with Drp1 inhibitor mdivi‐1 suppressed oxidative stress, alleviated mitochondrial dysfunction and cardiac dysfunction in diabetic mice. These findings show that melatonin attenuates the development of diabetes‐induced cardiac dysfunction by preventing mitochondrial fission through SIRT 1‐PGC 1α pathway, which negatively regulates the expression of Drp1 directly. Inhibition of mitochondrial fission may be a potential target for delaying cardiac complications in patients with diabetes.     

The role of IL‐1β in reduced IL‐7 production by stromal and epithelial cells: a model for impaired T‐cell numbers in the gut during HIV‐1 infection

Abstract. Thang PH, Ruffin N, Brodin D, Rethi B, Cam PD, Hien NT, Lopalco L, Vivar N, Chiodi F (Karolinska Institutet, Stockholm, Sweden; National Institute of Hygiene and Epidemiology, Hanoi, Vietnam; San Raffaele Scientific Institute, Milan, Italy). The role of IL‐1β in reduced IL‐7 production by stromal and epithelial cells: a model for impaired T‐cell numbers in the gut during HIV‐1 infection. J Intern Med 2010; 268 : 181–193. Objectives. Interleukin (IL)‐7 is a key cytokine in T‐cell homeostasis. Stromal cells, intestinal epithelial cells and keratinocytes are known to produce this cytokine. The mechanisms and cellular factors regulating IL‐7 production are still unclear. We assessed whether IL‐1β and interferon (IFN)‐γ, cytokines produced during inflammatory conditions, may impact on IL‐7 production. Design. We used human intestinal epithelial cells (DLD‐1 cell line) and bone marrow stromal cells (HS27 cell line), known to produce IL‐7; IL‐7 production was evaluated at the mRNA and protein levels. To assess whether treatment of HS27 cells with IL‐1β and/or IFN‐γ leads to changes in the gene expression of cytokines, Toll‐like receptors (TLRs) and chemokines, we analysed gene expression profiles using the whole‐genome microarray Human Gene 1.0 ST. Results. We found that IFN‐γ enhanced the expression of IL‐7 mRNA (P < 0.001) in both cell lines. IL‐1β treatment led to a significant down‐regulation (P < 0.001) of IL‐7 mRNA expression in both cell lines. The IL‐7 concentration in supernatants collected from treated DLD‐1 and HS27 cell cultures reflected the trend of IL‐7 mRNA levels. The gene profiles revealed dramatic changes in expression of cytokines and their receptors (IL‐7/IL‐7Rα; IL‐1α,IL‐1β/IL‐1R1; IFN‐γ/IFN‐γR1), of IFN regulatory factors (IRF‐1 and 2), of TLRs and of important chemo‐attractants for T cells. The microarray results were verified by additional methods. Conclusions. Our results are discussed in the setting of inflammation and T‐cell survival in the gut compartment during HIV‐1 infection where stromal and epithelial cells may produce factors that contribute to impaired IL‐7 homeostasis and homing of T cells.     

Flt3 ligand treatment modulates parasitemia during infection with rodent malaria parasites via MyD88‐ and IFN‐γ‐dependent mechanisms

We previously showed that treatment of mice with the Flt3 ligand (Flt3L) prevents development of lethal experimental cerebral malaria and inhibits parasitemia during Plasmodium berghei ANKA (PbA) infection. In this study, we investigated the mechanisms underlying the reduction of parasitemia in Flt3L‐treated mice. Studies using gene knockout mice and antibody treatment indicated that the anti‐parasitemia effect of Flt3L was mediated by innate immune system and was dependent on MyD88, IFN‐γ, IL‐12 and natural killer (NK) cells. The number of NK cells and their ability to produce IFN‐γ was enhanced in Flt3L‐treated mice. Phagocytic activity of splenocytes was increased in Flt3L‐treated mice after PbA infection when compared with that in untreated mice, and this activity was mainly mediated by the accumulation of F4/80^midCD11b⁺ cells in the spleen. In both MyD88^?/? and IFN‐γ^?/? mice, the proportion of F4/80^midCD11b⁺ cells was not increased in the spleen of Flt3L‐treated mice after infection. These correlations suggest that NK cells produce IFN‐γ in Flt3L‐treated mice, and accumulation of F4/80^midCD11b⁺ cells in the spleen is promoted by an IFN‐γ ‐dependent manner, culminating in the inhibition of parasitemia. These findings imply that Flt3L promotes effective innate immunity against malaria infection mediated by interplay among varieties of innate immune cells.     

Increased peripheral RORα and RORγt mRNA expression is associated with acute‐on‐chronic hepatitis B liver failure

Summary. T helper cells17 (Th17) have accurate but inconclusive roles in the pathogenesis of acute‐on‐chronic hepatitis B liver failure (ACHBLF). Retinoic acid‐related orphan receptor γ t(RORγt) and RORα are two lineage‐specific nuclear receptors directly mediating Th17 differentiation. This study was aimed to evaluate the gene expression of RORα and RORγt and their potential role in ACHBLF. Forty patients with liver failure, 30 with chronic hepatitis B (CHB) and 20 healthy controls were studied. The mRNA levels of RORα and RORγt in peripheral mononuclear cells were determined by quantitative real‐time polymerase chain reaction. The frequency of peripheral Th17 cells was determined using flow cytometry. The serum levels of interleukin‐6(IL‐6), transforming growth factor –β (TGF‐β), interleukin‐17(IL‐17), interleukin‐23(IL‐23) and interferon‐γ (IFN‐γ) were measured by enzyme‐linked immunosorbent assay. The frequency of peripheral Th17 cells in patients with liver failure was significantly increased compared to patients with CHB and controls. The peripheral mRNA levels of RORα and RORγt in hepatitis B‐associated acute‐on‐chronic liver failure were significantly higher than in patients with CHB and controls as were the serum levels of IL‐6 and TGF‐β. The serum level of IFN‐γ in patients with acute‐on‐chronic liver failure from HBV was significantly higher than patients with CHB but lower than controls. In patients with acute‐on‐chronic liver failure associated with HBV, RORγt, IL‐6 and IL‐23 were positively correlated with the frequency of Th17 cells, while RORα, TGF‐β and IFN‐γ had no correlation with the latter. The mRNA level of RORγt was positively correlated with model of end‐stage liver disease (MELD) score, but there was no correlation of RORα and MELD score. RORγt plays an important role in the pathogenesis of acute‐on‐chronic HBV‐associated liver failure and might be considered to be a candidate factor consistent with the severity of disease.     

Association of circulating proinflammatory marker,leucine‐rich‐α2‐glycoprotein (LRG1), following metabolic/bariatric surgery

Background

Obesity confers substantial excess risk for morbidity and mortality, especially for type 2 diabetes (T2D). Leucine‐rich‐α2‐glycoprotein 1 (LRG1), a novel proinflammatory factor, was recently reported to be higher in patients with T2D with complications of peripheral arterial disease. Association of LRG1, obesity, and weight loss is unknown. We examined whether plasma LRG1 is associated with obesity in health screening participants and if it predicts future weight loss in morbidly obese patients after metabolic/bariatric surgery.

Methods

Cohort 1 was a cross‐sectional study from a Health Screening program (n = 616) in a tertiary hospital. Cohort 2 was a prospective study of morbidly obese patients (n = 231) who underwent metabolic/bariatric surgery with follow‐up weight measurements. Anthropometric data, baseline fasting glucose, plasma adiponectin, high sensitivity C‐reactive protein (HsCRP), and LRG1 were measured. Postsurgery blood, after metabolic/bariatric surgery, were available for LRG1and HsCRP measurements in 57 patients.

Results

In the group with highest tertile of LRG1, body mass index (BMI), waist circumference, and HsCRP were significantly higher, while total cholesterol, high‐density lipoprotein, low‐density lipoprotein, and adiponectin were lower than tertiles 1 and 2. Generalized linear model analysis showed that female gender (P < .0001), non‐Chinese ethnicity (P < .019), and higher HsCRP (P < .0001) levels were independent and significant determinants of higher plasma LRG1 levels. After adjustment for age, gender, ethnicity, and baseline BMI, female gender (P = .020), higher presurgery BMI (P = .001), and lower presurgery LRG1 (P = .002) remained statistically significant predictors for greater weight loss. Plasma LRG1 increased significantly [from 28.2 (21.9‐36.8) to 34.9 (22.6‐49.5)] μg/mL (P = .003) within 1.5 months, after metabolic/bariatric surgery.

Conclusions

Our study demonstrates that LRG1 level is positively associated with obesity and a lower level of plasma LRG1 predicts weight loss in metabolic/bariatric surgery. Our novel findings suggest LRG1, itself or in combination with other known factors, is a potential biomarker of inflammation and obesity.     

Peroxisome proliferator‐activated receptor α ligands and modulators from dietary compounds: Types,screening methods and functions

Peroxisome proliferator‐activated receptor α (PPARα) plays a key role in lipid metabolism and glucose homeostasis and a crucial role in the prevention and treatment of metabolic diseases. Natural dietary compounds, including nutrients and phytochemicals, are PPARα ligands or modulators. High‐throughput screening assays have been developed to screen for PPARα ligands and modulators in our diet. In the present review, we discuss recent advances in our knowledge of PPARα, including its structure, function, and ligand and modulator screening assays, and summarize the different types of dietary PPARα ligands and modulators.     

An association between Type 2 diabetes and α1‐antitrypsin deficiency

Aims α₁‐Antitrypsin (AAT) is a serine protease inhibitor which recently has been shown to prevent Type 1 diabetes development, to prolong islet allograft survival and to inhibit pancreatic B‐cell apoptosis in vivo. It has also been reported that Type 1 diabetic patients have significantly lower plasma concentrations of AAT, suggesting the potential role of AAT in the pathogenesis of Type 1 diabetes. We have investigated whether plasma AAT levels are altered in Type 2 diabetes. Methods The study included patients with Type 2 diabetes (n = 163) and non‐diabetic control subjects matched for age, sex and smoking habits (n = 158) derived from the population‐based Malmö Diet and Cancer study. Plasma samples were analysed for AAT concentration and phenotype and serum glucose, insulin, C‐reactive protein and lipid levels were measured. Glycated haemoglobin was also measured. Results In the diabetic group, the women had higher mean plasma AAT levels than men (P < 0.05). The mean plasma AAT levels did not differ between diabetic and control subjects. However, the number of individuals with low AAT levels (< 1.0 mg/ml) was 50% higher in the diabetic group (P < 0.05) and the frequency of AAT deficiency genotypes was 50% higher (NS) in diabetic compared with control subjects. In the group of diabetic patients with AAT < 1 mg/ml, AAT directly correlated with systolic blood pressure (P = 0.048) and inversely correlated with waist–hip ratio (P = 0.031). Conclusions Our results provide evidence that deficiency of AAT may be associated with an increased risk of developing Type 2 diabetes.     

The effects of oleoylethanolamide,an endogenous PPAR‐α agonist,on risk factors for NAFLD: A systematic review

Non‐alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease. Recently, some novel compounds have been investigated for the prevention and treatment of NAFLD. Oleoylethanolamide (OEA), an endogenous PPAR‐α agonist, has exhibited a plethora of pharmacological properties for the treatment of obesity and other obesity‐associated metabolic complications. This systematic review was performed with a focus on the effects of OEA on the risk factors for NAFLD. PubMed, Scopus, Embase, ProQuest, and Google Scholar databases were searched up to December 2018 using relevant keywords. All articles written in English evaluating the effects of OEA on the risk factors for NAFLD were eligible for the review. The evidence reviewed in this article illustrates that OEA regulates multiple biological processes associated with NAFLD, including lipid metabolism, inflammation, oxidative stress, and energy homeostasis through different mechanisms. In summary, many beneficial effects of OEA have led to the understanding that OEA may be an effective therapeutic strategy for the management of NAFLD. Although a wide range of studies have demonstrated the most useful effects of OEA on NAFLD and the associated risk factors, further clinical trials, from both in vivo studies and in vitro experiments, are warranted to verify these outcomes.     

Coronary Flow Velocity Reserve is Improved by PPAR‐α Agonist Fenofibrate in Patients with Hypertriglyceridemia

Summary Introduction: Fenofibrate, an agonist of peroxisome proliferator‐activated receptor‐α (PPAR‐α), has a vascular protective effect. Aims: We investigated the effect of the PPAR‐α agonist on coronary artery endothelial function in patients with hypertriglyceridemia. Methods: Fifty‐eight patients with hypertriglyceridemia were divided into two groups: control (no treatment; n = 23) and fenofibrate treatment (n = 35), 200 mg/d, for 6 months. The patients had undergone rest and adenosine treatment to induce hyperemia for quantification of coronary flow velocity reserve (CFVR) by noninvasive Doppler echocardiography before treatment and at 6‐month follow‐up. Pulse wave velocity (PWV) was measured before treatment and at 6‐month follow‐up. Results: CFVR was significantly improved with fenofibrate treatment as compared with baseline level and control group (3.14 ± 0.36 vs. 2.80 ± 0.58 and 2.79 ± 0.65, P < 0.01 and 0.05, respectively), with no difference between baseline levels and untreated controls. In addition, at 6 months, plasma level of homocysteine was significantly increased with fenofibrate treatment as compared with at baseline and control group (median 18.13 [range 14.46–22.02]μmol/L vs. 14.09 [12.01–18.81] and 13.34 [9.69–17.06]μmol/L, P < 0.001 and 0.01, respectively). Furthermore, at 6 months, PWV was significantly decreased with fenofibrate treatment as compared with control group (1446 ± 136 cm/s vs. 1570 ± 203 cm/s, P < 0.05). Conclusions: Treatment with PPAR‐α agonist fenofibrate significantly improved CFVR and arterial stiffness in patients with hypertriglyceridemia. This endothelial protective effect may be reduced in part by the side effect of increasing homocysteine.