Pioglitazone attenuates the severity of sodium taurocholate-induced severe acute pancreatitis

Phosphoinositide 3‑kinase/protein kinase B regulates inflammation severity via signaling of Toll‑like receptor 4 in severe acute pancreatitis

Phosphatidylinositol 3‑kinase (PI3K)/protein kinase B (Akt) has been indicated to serve an important role in the pathogenesis of inflammatory diseases. It was previously demonstrated that the PI3K/Akt inhibitor wortmannin alleviated the severity of inflammation and improved the survival rate in rats with induced severe acute pancreatitis (SAP), which indicates that PI3K/Akt may serve a role in the pathogenesis of acute pancreatitis. To date, the mechanism by which PI3K/Akt regulates inflammation has not been elucidated. In the present study, it was hypothesized that PI3K/Akt may be invovled in SAP inflammation via regulation of the Toll‑like receptor 4 (TLR4) signaling pathway. Rats with SAP were treated with the PI3K/Akt agonist insulin‑like growth factor (IGF)‑1, which alleviated the severity of inflammation in a dose‑dependent manner. Furthermore, to better understand the role of PI3K/Akt in inflammation, RAW264.7 murine macrophages were stimulated with IGF‑1 and wortmannin alone or together before the induction of inflammation by treatment with lipopolysaccharide (LPS). The results indicated that LPS stimulated overexpression of TLR4, myeloid differentiation primary response gene 88 (MyD88), PI3K, Akt, p38MAPK and NF‑κBp65 mRNA, and increased the levels of tumor necrosis factor (TNF)‑α and interleukin (IL)‑6 in RAW264.7 cells compared with the control group. The levels of all detected factors were increased by stimulation with IGF‑1, whereas these levels were decreased following treatment with wortmannin alone, and the effect of IGF‑1 was abolished by wortmannin in RAW264.7 cells. In vivo studies indicated that IGF‑1 produced the same anti‑inflammatory effect as wortmannin and that expression of TLR4, p38MAPK and NF‑κBp65 decreased following treatment with IGF‑1. These findings indicate that PI3K/Akt may take part in the progression of SAP by regulating the TLR4 signaling pathway and that IGF‑1 can inhibit inflammation in SAP rats.

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.

Artesunate ameliorates severe acute pancreatitis (SAP) in rats by inhibiting expression of pro-inflammatory cytokines and Toll-like receptor 4

Severe acute pancreatitis (SAP) is a severe clinical condition with significant morbidity and mortality. Multiple organs dysfunction (MOD) is the leading cause of SAP-related death. The over-release of pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α is the underlying mechanism of MOD; however, there is no effective agent against the inflammation. Herein, artesunate (AS) was found to increase the survival of SAP rats significantly when injected with 3.5% sodium taurocholate into the biliopancreatic duct in a retrograde direction, improving their pancreatic pathology and decreasing serum amylase and pancreatic lipase activities along with substantially reduced pancreatic IL-1β and IL-6 release. In vitro, AS-pretreatment strongly inhibited IL-1β and IL-6 release and their mRNA expressions in the pancreatic acinar cells treated with lipopolysaccharide (LPS) but exerted little effect on TNF-α release. Additionally, AS reduced the mRNA expressions of Toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) p65 as well as their protein expressions in the pancreatic acinar cells. In conclusion, our results demonstrated that AS could significantly protect SAP rats, and this protection was related to the reduction of digestive enzyme activities and pro-inflammatory cytokine expressions via inhibition of TLR4/NF-κB signaling pathway. Therefore, AS may be considered as a potential therapeutic agent against SAP.

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.

Pathophysiological Effects of Pancreatic Sympathetic Denervation in Acute Necrotizing Pancreatitis in Dogs

OBJECTIVE

The aim of this study was to investigate the influence of the greater splanchnic nerve (GSN) transection on the pathophysiological process of acute necrotizing pancreatitis (ANP).

METHODS

The dogs were divided into a sham operation (SO) group, ANP group, and ANP with bilateral GSN transection (GSNT) group. Dogs in the GSNT group underwent bilateral GSNT immediately after ANP induction. The levels of serum pancreatic amylase (AMY), calcium, high-sensitivity C-reactive protein (HCRP), tumor necrosis factor α (TNF-α), interleukin 10 (IL-10), and neutrophile granulocyte (NEU) counts were monitored dynamically, and the pathological examinations of the pancreas was performed at postoperative day 7.

RESULTS

All the parameters among the 3 groups showed no differences before the experiment (P > 0.05). At different postoperative times, the NEU count and serum AMY, TNF-α, HCRP, and IL-10 were significantly increased; however, the serum calcium had decreased in the ANP group versus SO (P < 0.05). The postoperative serum IL-10 and calcium levels were higher, and TNF-α, HCRP, and NEU counts were lower in the GSNT group compared with those in the ANP group (P < 0.05); as for AMY, no significant difference was found between the 2 groups (P > 0.05). The pancreas pathological scoring of the GSNT group was lower versus the ANP group (P < 0.05).

CONCLUSIONS

Greater splanchnic nerve transection can alleviate development of pathophysiological processes in ANP.

Rosmarinic Acid Attenuates Sodium Taurocholate-Induced Acute Pancreatitis in Rats by Inhibiting Nuclear Factor-κB Activation

Rosmarinic Acid (RA), a caffeic acid ester, has been shown to exert anti-inflammation, anti-oxidant and antiallergic effects. Our study aimed to investigate the effect of RA in sodium taurocholate ( NaTC )-induced acute pancreatitis, both in vivo and in vitro. In vivo, RA (50 mg/kg) was administered intraperitoneally 2 h before sodium taurocholate injection. Rats were sacrificed 12 h, 24 h or 48 h after sodium taurocholate injection. Pretreatment with RA significantly ameliorated pancreas histopathological changes, decreased amylase and lipase activities in serum, lowered myeloperoxidase activity in the pancreas, reduced systematic and pancreatic interleukin-1 β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) levels, and inhibited NF-κB translocation in pancreas. In vitro, pretreating the fresh rat pancreatic acinar cells with 80 μ mol/L RA 2 h before 3750 nmol/L sodium taurocholate or 10 ng/L TNF-α administration significantly attenuated the reduction of isolated pancreatic acinar cell viability and inhibited the nuclear activation and translocation of NF-κB. Based on our findings, RA appears to attenuate damage in sodium taurocholate-induced acute pancreatitis and reduce the release of inflammatory cytokines by inhibiting the activation of NF-κB. These findings might provide a basis for investigating the therapeutic role of RA in managing acute pancreatits.

Beneficial effect of splanchnic nerve transection and harmful effect of vagotomy on acute necrotizing pancreatitis in the dog

BACKGROUND

The nervous system interacts dynamically with the immune system to modulate inflammation through humoral and neural pathways. However, the influence of visceral nerve (VN) on acute necrotizing pancreatitis (ANP) has drawn little attention.

AIM

To investigate the influence of VN on the pathophysiological process of ANP in dogs.

METHODS

The dogs were divided into a sham operation (SO) group, ANP group, ANP + vagal nerve trunk transection (VNTT) group, and ANP + greater splanchnic nerve transection (GSNT) group. The VNTT and GSNT groups underwent VNTT and GSNT respectively immediately after ANP induction. The levels of serum pancreatic amylase (AMY), calcium, high-sensitivity C-reactive protein (HCRP), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-10 (IL-10) were monitored dynamically and the pathological examinations of the pancreas was performed at postoperative day 7.

RESULTS

All serum parameters among the four groups showed no differences before the experiment (p > 0.05). At different postoperative times, the serum TNF-α, IL-1β, HCRP, and AMY were significantly increased, however, the serum calcium and IL-10 had dropped in the ANP group versus SO group (p < 0.05); an alike variation trend occurred between the VNTT group and ANP group (p < 0.05); an opposite variation trend occurred between the GSNT group and the ANP group (p < 0.05). The pancreas pathological scoring of VNTT group was highest in the four groups (p < 0.05) and GSNT group was lower versus ANP group (p < 0.05).

CONCLUSIONS

The GSNT has been shown to alleviate development of ANP, however, VNTT may exacerbate the ANP.

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

PURPOSE

To investigate the effects and mechanisms of peroxisome proliferator-activated receptor-γ (PPAR-γ) activation on the induction of apoptosis in rats with acute pancreatitis.

METHODS

Severe acute pancreatitis (SAP) and mild acute pancreatitis (MAP) were induced and pre-treated with pioglitazone, which is a ligand of PPAR-γ. The expression of inflammatory factors (TNF-α and IL6) of the pancreas was detected by ELISA. The apoptosis in pancreas were detected by TUNEL assay and the activity of caspase 3 was determined. Phosphorylation of p65 in pancreas of SAP or MAP was determined by western-blot.

RESULTS

Expression levels of PPAR-γ proteins were elevated in the pancreases of SAP or MAP rats pre-injected with pioglitazone intraperitoneally. Downregulation of the expression TNF-α and IL6 and relief of pathological changes in the pancreas suggested that pioglitazone had protective effects on acute panceatitis. In pioglitazone pre-treated groups, a TUNEL assay indicated a high level of apoptosis in SAP but little apoptosis in MAP, showing pioglitazone could promote taurocholate-induced apoptosis but inhibit ceruleininduced apoptosis in pancraeatic aniniar cells. Furthermore, caspase 3 activity was high in SAP but low in MAP, implying that the apoptotic mechanism in pancreatic acinar cells of AP rats was correlated with caspase 3 activity. Phosphorylation of p65 was reduced in SAP or MAP group pretreated with pioglitazone, indicating that pioglitazone reduced the inflammation reaction by inhibiting the activation of the NF-κB.

CONCLUSIONS

These results indicated that activation of PPAR-γ induced apoptosis in pancreatic acinar cells of SAP rats but inhibited apoptosis in pancraeatic acinar cells of MAP rats, which demonstrated that PPAR-γ may be an efficiently therapeutic target in pancreatic inflammation.

Effects of dexamethasone and Salvia miltiorrhiza on multiple organs in rats with severe acute pancreatitis

OBJECTIVE

To investigate the protective effects and mechanisms of action of dexamethasone and Salvia miltiorrhiza on multiple organs in rats with severe acute pancreatitis (SAP).

METHODS

The rats were divided into sham-operated, model control, dexamethasone treated, and Salvia miltiorrhiza treated groups. At 3, 6, and 12 h after operation, the mortality rate of different groups, pathological changes, Bcl-2-associated X protein (Bax) and nuclear factor-κB (NF-κB) protein expression levels in multiple organs (the pancreas, liver, kidneys, and lungs), toll-like receptor 4 (TLR-4) protein levels (only in the liver), intercellular adhesion molecule 1 (ICAM-1) protein levels (only in the lung), and terminal deoxynucleotidy transferase mediated deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) staining expression levels, as well as the serum contents of amylase, glutamate-pyruvate transaminase (GPT), glutamic-oxaloacetic transaminase (GOT), blood urea nitrogen (BUN), and creatinine (CREA) were observed.

RESULTS

The mortality rate of the dexamethasone treated group was significantly lower than that of the model control group (P<0.05). The pathological changes in multiple organs in the two treated groups were relieved to different degrees (P<0.05 and P<0.01, respectively), the expression levels of Bax and NF-κB proteins, and apoptotic indexes of multiple organs were reduced (P<0.05 and P<0.01, respectively). The contents of amylase, GPT, GOT, BUN, and CREA in the two treated groups were significantly lower than those in model control groups (P<0.05 and P<0.01, respectively). The expression level of ICAM-1 protein in the lungs (at 3 and 12 h) in the dexamethasone treated group was significantly lower than that in the Salvia miltiorrhiza treated group (P<0.05). The serum contents of CREA (at 12 h) and BUN (at 6 h) of the Salvia miltiorrhiza treated group were significantly lower than those in the dexamethasone treated group (P<0.05).

CONCLUSIONS

Both dexamethasone and Salvia miltiorrhiza can reduce the inflammatory reaction, regulate apoptosis, and thus protect multiple organs of rats with SAP.

Pancreatitis-associated ascitic fluid induces proinflammatory cytokine expression in THP-1 cells by inhibiting anti-inflammatory signaling

OBJECTIVES

We investigated whether pancreatitis-associated ascitic fluid (PAAF) could induce the expression of tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) in THP-1 cells and the mechanism(s) involved.

METHODS

THP-1 cells were divided into control and PAAF groups. The PAAF group was incubated with different final concentrations of PAAF, whereas the control group was incubated with culture medium. Effects and mechanisms were determined by measuring the levels of TNF-α and IL-6 mRNA expression; phospho-p38-MAPK, nuclear factor κB, peroxisome proliferator-activated receptor γ activation; and the effect on the inhibitory activity of SB203580 and BAY-117082.

RESULTS

In response to PAAF, overexpression of TNF-α and IL-6 mRNA was found in THP-1 cells compared with those of the corresponding control (P < 0.05), and in a dose-dependent manner. The levels of phospho-p38 and nuclear factor κB p65 were also increased in different PAAF groups, whereas low expression of peroxisome proliferator-activated receptor γ was found compared with the control group (P < 0.05). Furthermore, we presented that the inflammatory response could be partly alleviated by inhibitors SB203580 or BAY-117082, whereas it was markedly inhibited by the simultaneous treatment of 2 inhibitors.

CONCLUSIONS

Pancreatitis-associated ascitic fluid up-regulated proinflammatory cytokines by interfering with proinflammatory and anti-inflammatory signaling pathways, thus exacerbating activation in acute pancreatitis.

Rosiglitazone improves survival and hastens recovery from pancreatic inflammation in obese mice

Obesity increases severity of acute pancreatitis (AP) by unclear mechanisms. We investigated the effect of the PPAR-gamma agonist rosiglitazone (RGZ, 0.01% in the diet) on severity of AP induced by administration of IL-12+ IL-18 in male C57BL6 mice fed a low fat (LFD) or high fat diet (HFD), under the hypothesis that RGZ would reduce disease severity in HFD-fed obese animals. In both LFD and HFD mice without AP, RGZ significantly increased body weight and % fat mass, with significant upregulation of adiponectin and suppression of erythropoiesis. In HFD mice with AP, RGZ significantly increased survival and hastened recovery from pancreatic inflammation, as evaluated by significantly improved pancreatic histology, reduced saponification of visceral adipose tissue and less severe suppression of erythropoiesis at Day 7 post-AP. This was associated with significantly lower circulating and pancreas-associated levels of IL-6, Galectin-3, osteopontin and TIMP-1 in HFD + RGZ mice, particularly at Day 7 post-AP. In LFD mice with AP, RGZ significantly worsened the degree of intrapancreatic acinar and fat necrosis as well as visceral fat saponification, without affecting other parameters of disease severity or inflammation. Induction of AP lead to major suppression of adiponectin levels at Day 7 in both HFD and HFD + RGZ mice. In conclusion, RGZ prevents development of severe AP in obese mice even though it significantly increases adiposity, indicating that obesity can be dissociated from AP severity by improving the metabolic and inflammatory milieu. However, RGZ worsens selective parameters of AP severity in LFD mice.

Pioglitazone: a promising therapeutic tool in sodium taurocholate-induced severe acute pancreatitis

BACKGROUND

Studies suggest that peroxisome proliferator-activated receptor γ(PPARγ) ligands may represent a therapeutic option in acute pancreatitis, yet most of them have been prophylactic administrated.

AIMS

To evaluate the therapeutic effect of pioglitazone in rats with severe acute pancreatitis induced by sodium taurocholate.

METHODS

Severe acute pancreatitis (SAP) was induced in male Sprague-Dawley rats by the retrograde injection of 5% sodium taurocholate into the pancreatic duct. After SAP was induced, pioglitazone was injected intraperitoneally and its role on the severity of inflammatory response and pancreatic injury was investigated. Amylase activity, inflammatory cytokines production, pathological changes of pancreas, PPARγ mRNA expression, and the survival rate were examined.

RESULTS

Treatment with pioglitazone decreased the level of amylase activity, proinflammatory factors IL-6 and TNF-α, ameliorated pancreatic histological score, and upregulated the expression of PPARγ mRNA. The survival rate in the early stage of severe acute pancreatitis was also improved.

CONCLUSIONS

Pioglitazone can be used as a therapeutic drug and relieve the damages caused by SAP, which suggests PPARγ ligand-pioglitazone offers a potent approach for the treatment of severe acute pancreatitis.

Pioglitazone attenuates ischemia/reperfusion-induced liver injury in rats

INTRODUCTION

Hepatic ischemia/reperfusion (I/R) injury leads to free radical generation and acute inflammatory responses that cause liver damage, an important problem for liver transplantation. Pioglitazone is known to protect I/R injury in various tissues; however, the mechanism of cytoprotection is not well understood. This study investigated the effects of pioglitazone administration in a warm hepatic I/R model on tumor necrosis factor (TNF)-alpha level, tissue injury, and antioxidant enzyme activity.

MATERIALS AND METHODS

Eighty wistar strain rats were divided into 4 groups (n = 20): Group 1 sham hosts; Group 2 hepatic I/R; Group 3 hepatic I/R + pioglitazone (10 mg/kg); and Group 4 hepatic I/R + vehicle. Rat livers were subjected to 30 minutes of ischemia followed by 6 hours of reperfusion. After reperfusion rats were humanely killed to obtain liver tissue to study glutathione peroxidase (GPx), superoxide dysmutase (SOD), malondialdehyde (MDA) levels and for histopathologic assessment. TNF-alpha, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were measured in serum.

RESULTS

Pioglitazone pretreatment significantly reduced liver enzyme content (ALT, 176.80 +/- 13.75 vs 235.28 +/- 31.92 and AST, 748.20 +/- 79.29 vs 944.85 +/- 101.87) and TNF-alpha level (9:8.60 +/- 8.67 vs 138.28 +/- 9.99) after I/R compared with the control group. MDA level (3.02 +/- 0.37 vs 4.36 +/- 0.38) and hepatocytic degeneration were reduced in the pioglitazone-treated group. GPx (2.40 +/- 0.25 vs 1.36 +/- 0.31) and SOD activity (2.22 +/- 0.30 vs 1.40 +/- 0.35) were significantly higher in the pioglitazone-treated group compared with the control group.

CONCLUSION

The present study showed that pioglitazone administration improved hepatic I/R injury that was associated with enhanced antioxidant enzyme activities and suppression of TNF-alpha, ALT, and AST levels. Because peroxisome proliferator-activated receptor-gamma agonists are widely used to treat diabetic patients, it may be relatively easy to expand their clinical indication. However, further investigations will be required to delineate protective mechanisms by which pioglitazone attenuates hepatic tissue injury after I/R.

Advances in research of severe acute pancreatitis complicated by lung injury

Lung injury is one of the most common complications of severe acute pancreatitis (SAP). At present, the pathogenesis of SAP complicated by lung injury still remains unclear. However, great attention has been paid to it at home and abroad. Many factors such as pancreatic enzyme, polymorphonuclear neutrophil, oxygen free radical, cytokine, microcirculatory disturbance, complement, kinin, NO and ET play an important role in the pathogenesis of SAP by interacting with each other. This paper reviews the advances in the pathogenesis of SAP complicated by lung injury and related studies in order to provide the theoretical basis for its effective prevention and treatment.