Effects of peroxisome proliferator-activated receptor-γ activation on apoptosis in rats with acute pancreatitis

Effect of microRNA-27a-5p on apoptosis and inflammatory response of pancreatic acinar cells in acute pancreatitis by targeting PTEN

To investigate the apoptosis and inflammatory response of microRNA-27a-5p (miR-27a-5p) in pancreatic acinar cells of acute pancreatitis (AP) and its related mechanisms. Rat pancreatic acinar cell line AR42J was treated with caerulein (10nmol/L) to construct an acute pancreatitis cell model. Quantitative real-time polymerase chain reaction was performed to measure the expression of miR-27a-5p; The miR-27a-5p mimic was transfected into cell, and the apoptosis rate of the cells was detected by flow cytometry; The levels of TNF-α, IL-1, and IL-6 in the culture supernatant were determined by enzyme-linked immunosorbent assay; TargetScans database predicted and dual luciferase reporter gene assay verified the relationship between miR-27a-5p and the phosphatase and tensin homolog deleted on chromosome 10 (PTEN); The recovery experiment explored the apoptosis and the effects of inflammatory responses. The expression of miR-27a-5p decreased gradually (P < 0.05) and the expression of PTEN increased gradually (P < 0.05) with the prolongation of acting time. Upregulation of miR-27a-5p significantly promoted cell apoptosis (P < 0.05) and inhibited inflammatory response (P < 0.05); The TargetScans database predicted that the 3'UTR of PTEN contains a base complementary to the miR-27a-5p seed region. Cotransfection of wild-type vector (PTEN-WT) with miR-27a-5p mimic or miR-27a-5p inhibitor significantly affected the relative activity of luciferase (P < 0.05), and no significant impact was observed in mutant PTEN-MUT. Compared with miR-27a-5p + pcDNA group, transfection of miR-27a-5p mimic and pcDNA-PTEN significantly increased the expression of PTEN (P < 0.05), decreased the apoptotic rate (P < 0.05), and increased the inflammatory response (P < 0.05). miR-27a-5p induced apoptosis and inhibited the inflammatory response of pancreatic acinar cells in AP by targeting PTEN.

Moringa concanensis Nimmo extracts ameliorates hyperglycemia-mediated oxidative stress and upregulates PPARγ and GLUT4 gene expression in liver and pancreas of streptozotocin-nicotinamide induced diabetic rats

The current study investigates the effects of ethanolic extract of M. concanensis Nimmo leaves (EEMCNL) with respect to its potent protective tissue damage, antioxidant properties in serum, liver and kidney, histopathological evaluation, and PPARγ and GLUT4 gene expression in liver and pancreatic tissue of Streptozotocin-Nicotinamide (STZ-NA) induced diabetic rats. Animals were divided into five groups (n = 5): control; diabetic; diabetic + EEMCNL; control + EEMCNL; and diabetic + glibenclamide. After 45 days of treatment with EEMCNL, MDA levels were significantly decreased in the diabetic-induced group when compared with the STZ-induced diabetic group (P < 0.05). The activities of serum enzymes AST, ALT, ALP, ACP and LDH were significantly decreased in serum and kidney, and increased in liver tissues of the EEMCNL-treated group as compared with the STZ-NA induced diabetic group (P < 0.05). The levels of total protein, urea, creatinine and uric acid observed in the diabetic group returned to normal by administration of EEMCNL (250 mg/kg) as relative to the STZ-NA induced diabetic group (P < 0.05). Furthermore, EEMCNL upregulated PPARγ and GLUT4 expression in liver and pancreatic tissue of the STZ-NA induced diabetic group rats. Taken together, these findings contribute to a better understanding of the hepatoprotective and renoprotective potential of EEMCNL against oxidative stress in the diabetic state, which was evidenced by the capacity of EEMCNL to modulate the antioxidant defence and to decrease lipid peroxidation in these tissues.

Therapeutic effect and potential mechanism of pioglitazone in rats with severe acute pancreatitis

Caspase recruitment domain-containing protein 9 (Card9) is located upstream of the nuclear factor kappa B (NF-κB) and p38 mitogen-activated protein kinase (MAPK) inflammatory pathways. This study investigated the therapeutic effect and potential mechanism of pioglitazone in rats with severe acute pancreatitis (SAP). SAP was induced by a retrograde infusion of 5.0% sodium taurocholate into the biliopancreatic duct of Sprague Dawley rats (n=54), which were then treated with pioglitazone. Blood and pancreatic tissues were harvested at 3, 6, and 12 h after SAP induction. Pancreatic pathological damage was evaluated by hematoxylin and eosin staining. Serum amylase, serum pro-inflammatory cytokines, and pancreatic myeloperoxidase (MPO) activities were determined by enzyme-linked immunosorbent assay. The expression of Card9 mRNA and protein in pancreatic tissues was detected by real-time polymerase chain reaction and western blotting. Pioglitazone had a therapeutic effect in treating rats with SAP by decreasing the level of amylase activity, ameliorating pancreatic histological damage, decreasing serum pro-inflammatory cytokine levels and tissue MPO activity, and downregulating the expression of NF-κB, p38MAPK, and Card9 mRNAs and proteins (P<0.05). The present study demonstrated that the inhibition of Card9 expression could reduce the severity of SAP. Card9 has a role in the pathogenic mechanism of SAP.

Clinical relevance of peroxisome proliferator-activated receptor-γ gene polymorphisms with sepsis

BACKGROUND

Peroxisome proliferator-activated receptor-γ (PPARγ) is a regulator of inflammation. This study aimed to explore associations between PPARγ gene single-nucleotide polymorphisms (SNPs) and susceptibility to and clinical outcome of sepsis in the North China Han population.

METHODS

This study included 303 patients with sepsis and 303 controls. We conducted genetic typing for 13 common PPARγ gene SNPs (improved multiplex ligation detection reaction), linkage disequilibrium mapping, and haplotype inference. Associations between SNP genotypes/haplotypes and sepsis susceptibility and outcome (septic shock, organ dysfunction, or death) were assessed using unconditional logistic regression analysis.

RESULTS

For rs2972164, patients with genotypes CT/CT+TT had higher risk of sepsis than genotype CC (odds ratio [95% CI]: 1.74 [1.05-2.86], P = .03 and 1.72 [1.06-2.80], P = .026, respectively); the T allele was associated with increased sepsis risk compared with the C allele (1.64 [1.04-2.58], P = .033). For rs1801282, genotypes CG/CG+GG had lower risk of sepsis than genotype CC (0.55 [0.33-0.92], P = .024 and 0.57 [0.35-0.95], P = .03, respectively); the G allele was associated with decreased sepsis risk compared with the C allele (0.62 [0.39-1.01], P = .055). For rs4135275, genotypes AG/AG+GG had higher risk of severe organ dysfunction (multiple organ dysfunction syndrome score >8) than genotype AA (2.66 [1.16-6.09], P = .038 and 2.21 [1.00-4.85], P = .042, respectively). Haplotype TAT (rs2972164, rs4684846, and rs17036188) was associated with increased sepsis risk (1.66 [1.03-2.67], P = .038).

CONCLUSIONS

No mutation was correlated with septic shock or death. PPARγ gene polymorphisms may play a role in the occurrence and progression of sepsis in the North China Han population.

Translational Insights Into Peroxisome Proliferator-Activated Receptors in Experimental Acute Pancreatitis

Acute pancreatitis (AP) is an inflammatory disorder of the exocrine pancreas frequently associated with metabolic causes, contributing factors, or consequences, including hypertriglyceridemia, obesity, and disorders of intermediary metabolism, respectively. To date, there is no specific therapy for this disease. Future optimal therapy should correct both inflammatory and metabolic components of the disease. Peroxisome proliferator-activated receptors (PPARs) are lipid-sensing nuclear receptors that control inflammatory and metabolic pathways via ligand-dependent and ligand-independent mechanisms. There are 3 known subtypes, PPAR-α, PPAR-β/δ, and PPAR-γ, which are differentially expressed in various tissues. The PPARs interact closely with other transcription factors such as nuclear factor κB and signal tranducers and activators of transcription that have pivotal roles in the pathobiology of AP. In this comprehensive review, we summarize the role of PPARs in AP, highlighting important in vitro and in vivo experimental findings. Finally, we propose future research directions as well as potential translational use of PPAR agonists in the treatment of AP.

Apoptotic Mechanisms of Peroxisome Proliferator-Activated Receptor-γ Activation in Acinar Cells During Acute Pancreatitis

OBJECTIVE

The objective of this study was to determine the mechanism by which activation of peroxisome proliferator-activated receptor-γ promotes apoptosis of acinar cells in pancreatitis.

METHODS

AR42j cells pretreated with the peroxisome proliferator-activated receptor-γ agonist pioglitazone were activated by cerulein as an in vitro model of acute pancreatitis. Inflammatory cytokines and amylase were detected by enzyme-linked immunosorbent assay. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell apoptosis was measured by flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining. Activity of caspases was determined. Bax and Bcl-2 levels were assayed by Western blot.

RESULTS

Cytokines, amylase, and cellular proliferation decreased in pioglitazone-pretreated cells. Pioglitazone increased the activity of caspases 3, 8, and 9 in cerulein-activated AR42j cells as well as in the pancreas of rats 3 hours after induction of severe acute pancreatitis. Acinar cell apoptosis was induced by reducing the mitochondrial membrane potential in the pioglitazone group. Pioglitazone increased expression of proapoptotic Bax proteins and decreased antiapoptotic Bcl-2 in cerulein-induced AR42j cells and decreased Bcl-2 levels in pancreatic tissue of severe acute pancreatitis rats 1 and 3 hours after induction.

CONCLUSION

Pioglitazone may promote apoptosis of acinar cells through both intrinsic and extrinsic apoptotic pathways in acute pancreatitis.

Promoter methylation status and expression of PPAR-γ gene are associated with prognosis of acute-on-chronic hepatitis B liver failure

Background

Peroxisome proliferator-activated receptor gamma (PPAR-γ) has been demonstrated to be involved in anti-inflammatory reactions, but its role in acute-on-chronic hepatitis B liver failure (ACHBLF) is unclear. Therefore, DNA methylation patterns and expression level of PPAR-γ gene were detected in peripheral blood mononuclear cells (PBMCs) from 81 patients with ACHBLF, 50 patients with chronic hepatitis B (CHB), and 30 healthy controls, and the possible role of PPAR-γ in ACHBLF was analyzed.

Results

We found that aberrant PPAR-γ promoter methylation was attenuated in ACHBLF patients compared with CHB patients and was responsible for the elevated PPAR-γ expression level, which was negatively correlated with total bilirubin and international normalized ratio. Plasma level of TNF-α and IL-6 in ACHBLF patients were higher than CHB patients and healthy controls and significantly reduced in unmethylated group. ACHBLF patients with PPAR-γ promoter methylation had poorer outcomes than those without. Correspondingly, PPAR-γ messenger RNA (mRNA) level was higher in survivors than non-survivors and gradually increased in survivors with time, while remained low level in non-survivors.

Conclusions

Aberrant promoter methylation decline and PPAR-γ expression rebound occurred in ACHBLF compared with CHB and could improve prognosis of ACHBLF by negatively regulating cytokines.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0149-2) contains supplementary material, which is available to authorized users.

Protective effects of pioglitazone and/or liraglutide on pancreatic β-cells in db/db mice: Comparison of their effects between in an early and advanced stage of diabetes

The aim was to compare the protective effects of pioglitazone (PIO) and/or liraglutide (LIRA) on β-cells with the progression of diabetes. Male db/db mice were treated with PIO and/or LIRA for 2 weeks in an early and advanced stage. In an early stage insulin biosynthesis and secretion were markedly increased by PIO and LIRA which was not observed in an advanced stage. In concomitant with such phenomena, expression levels of various β-cell-related factors were up-regulated by PIO and LIRA only in an early stage. Furthermore, β-cell mass was also increased by the treatment only in an early stage. Although there was no difference in apoptosis ratio between the two stages, β-cell proliferation was augmented by the treatment only in an early stage. In conclusion, protective effects of pioglitazone and/or liraglutide on β-cells were more powerful in an early stage of diabetes compared to an advanced stage.

Small intestinal smooth muscle cell apoptosis in rats with severe acute pancreatitis

AIM: To investigate whether small intestinal smooth muscle cell apoptosis occurs in rats with severe acute pancreatitis (SAP) and the underlying mechanism.

METHODS: Male SD rats were randomly divided into a sham operation group (SO) and an SAP group. SAP was induced by injecting 3.8% sodium taurocholate solution into the subcapsular region of the pancreas of SD rats. Rats in the SO group were injected with 1 mL/kg normal saline. Forty-eight hours later, pancreatic pathological changes and the transit rate of the small bowel were determined. Cell apoptosis, expression of adenine nucleotide translocator (ANT) mRNA, mitochondrial membrane potential, and cytochrome C (Cyt-C) protein expression in the small intestinal smooth muscle were determined by TUNEL method, RT-PCR, flow cytometry and immunohistochemistry, respectively.

RESULTS: Compared with rats in the SO group, rats in the SAP group developed typical SAP symptoms, with a higher pancreatic pathology score (6.85 ± 1.21 vs 1.13 ± 0.91, P < 0.001). Compared with rats in the SO group, the transit rate of the small intestine was significantly lower (55.91% ± 2.93% vs 68.9% ± 5.69%, P < 0.05), the apoptosis of smooth muscle cells in the small intestine increased significantly (0.056 ± 0.184 vs 0.029 ± 0.038, P < 0.05), the expression of ANT mRNA and Cyt-C protein (0.024 ± 0.001 vs 0.057 ± 0.168, P < 0.001) in the smooth muscle of the small intestine increased significantly, and the mitochondrial membrane potential decreased significantly (5.07 ± 0.92 vs 2.40 ± 0.50, P < 0.05) in the SAP group.

CONCLUSION: The mitochondrial signal transduction pathway contributes to smooth muscle cell apoptosis in the small intestine, which may play a role in small intestinal motility dysfunction in SAP rats.

Astragalus membranaceus modulates Th1/2 immune balance and activates PPARγ in a murine asthma model

Astragalus membranaceus, a traditional Chinese herb, has been used to improve airway inflammation and asthma. The present study investigated whether A. membranaceus has immunotherapeutic effects on asthma, a chronic inflammatory mucosal disease that is associated with excess production of IgE, eosinophilia, T helper 2 (Th2) cytokines, and bronchial hyperresponsiveness. An ovalbumin (OVA)-induced, chronic inflammatory airway murine asthma model was used to examine the status of pulmonary inflammation after the administration of A. membranaceus. The IgE levels in serum and bronchoalveolar lavage fluid showed a tendency to decrease after the administration of A. membranaceus. The number of eosinophils decreased and infiltration of inflammatory cells and collagen deposition declined in lung sections after A. membranaceus administration. The RNA and protein levels of Th2 cytokines and the ratio of the GATA3/T-bet mRNA levels decreased after A. membranaceus treatment. Furthermore, the mRNA level of peroxisome proliferator-activated receptor γ (PPARγ), a nuclear hormone receptor, increased in the lung tissues of A. membranaceus-treated mice. Finally, an A. membranaceus water extract activated PPARγ activity in either human embryonic kidney 293 (HEK293) or A549 cells in a PPARγ-responsive element-containing luciferase reporter assay. These results indicate that A. membranaceus has an inhibitory effect on airway inflammation in a murine model of asthma through modulating the imbalanced relationship between Th1 and Th2 cytokines.

Antihyperglycemic Activity of Houttuynia cordata Thunb. in Streptozotocin-Induced Diabetic Rats

Present study is an attempt to investigate plausible mechanism involved behind antidiabetic activity of standardized Houttuynia cordata Thunb. extract in streptozotocin-induced diabetic rats. The plant is used as a medicinal salad for lowering blood sugar level in North-Eastern parts of India. Oral administration of extract at 200 and 400 mg/kg dose level daily for 21 days showed a significant (P < 0.05) decrease in fasting plasma glucose and also elevated insulin level in streptozotocin-induced diabetic rats. It also significantly reversed all the alterations in biochemical parameters, that is, total lipid profile, blood urea, creatinine, protein, and antioxidant enzymes in liver, pancreas, and adipose tissue of diabetic rats. Furthermore, we have demonstrated that the extract significantly reversed the expression patterns of various glucose homeostatic enzyme genes like GLUT-2, GLUT-4, and caspase-3 levels but did not show any significant effect on PPAR- γ protein expressions. Additionally, the extract positively regulated mitochondrial membrane potential and succinate dehydrogenase (SDH) activity in diabetic rats. The findings justified the antidiabetic effect of H. cordata which is attributed to an upregulation of GLUT-4 and potential antioxidant activity, which may play beneficial role in resolving complication associated with diabetes.