The role of the glucocorticoid-dependent mechanism in the progression of sodium taurocholate-induced acute pancreatitis in the rat

Pharmacological prevention of post-operative pancreatitis: systematic review and meta-analysis of randomized controlled trials on animal studies

BACKGROUND

Postoperative pancreatic fistula (POPF) remains a significant complication of pancreatic resection with recent evidence showing a strong association between post-operative pancreatitis and subsequent development of POPF. Incidence and severity of pancreatitis following endoscopic therapy has been effectively reduced with indomethacin prophylaxis, however further agents require evaluation. We present a systematic literature review and meta-analysis of the prophylactic treatment with corticosteroids or n-acetyl cysteine (NAC) of induced pancreatitis in rodent models.

METHODS

A systematic literature search was conducted using Pubmed, Medline, Embase and Cochrane library to identify eligible randomized control trials (RCT) involving animal models that examined NAC or corticosteroids. The primary outcome was the subsequent effect on serum amylase and IL-6 and the histopathological markers of severity such as pancreatic oedema and necrosis.

RESULTS

Four RCTs (n = 178) met inclusion criteria examining NAC and eight RCTs (n = 546) examining corticosteroid agents (dexamethasone, hydrocortisone, methylprednisolone). Prophylactic administration of all corticosteroid agents showed a net effect in favour of reducing markers of severity of pancreatitis. NAC showed a significant reduction in severity of amylase and necrosis.

CONCLUSION

The RCTs examined suggest that prophylactic administration of corticosteroid agents and NAC can reduce the severity of pancreatitis as indicated by histopathologic markers, serum amylase and IL-6 levels.

Wedelolactone alleviates acute pancreatitis and associated lung injury via GPX4 mediated suppression of pyroptosis and ferroptosis

Acute pancreatitis (AP) is an inflammatory disorder associated with multiple organ failure. Pyroptosis and ferroptosis are two newly recognized cell death, and whether pyroptosis and ferroptosis are involved in AP remain largely elusive. The nature compound Wedelolactone (Wed) exhibits strong anti-inflammatory and antioxidant activities, the present study aims to investigate the effect of Wed on AP and unravel whether Wed could protect against AP and relevant lung injury against pyroptosis and ferroptosis. Our results showed that the pyroptosis inhibitor disulfiram or ferroptosis inhibitor ferrostatin-1 significantly alleviated AP and associated lung injury in the taurocholate or caerulein-induced murine AP model. Administration with Wed ameliorated AP and lung injury as evidenced by improved pathological injuries, reduced serum pancreatic digestive enzymes, and proinflammatory cytokines. The in vivo and in vitro data demonstrated that Wed broadly inhibited caspase1/caspase11 activation, reduced mature interleukin-1β (IL-1β) and N-terminal domain of gasdermin D (GSDMD-N) level. The oxidative stress and lipid peroxidation were also suppressed along with the up-regulation of the ferroptosis antagonism marker glutathione peroxidase-4 (GPX4) in Wed treatment group. Wed promoted the transcriptional activity and the selenium sensitivity of GPX4. Moreover, the protective effects of Wed in caerulein-stimulated pancreatic acinar cells were markedly abrogated by the down-regulation of GPX4. Collectively, our data suggest that pyroptosis and ferroptosis play crucial roles in AP. Wed mitigated AP and associated lung injury via GPX4 mediated suppression of pyroptosis and ferroptosis.

Regulation of p38 MAPK and glucocorticoid receptor activation by hydrocortisone in mono-and co-cultured pancreatic acinar and stellate cells

BACKGROUND/OBJECTIVES

Acute pancreatitis develops as an inflammatory response to pancreatic tissue injury. Postoperative pancreatitis has recently been associated with increased occurrence of complications. Activation of the mitogen-activated protein kinase p38 (p38 MAPK) pathway occurs early in acute pancreatitis and its inhibition has been suggested to alleviate pancreatic inflammation. Glucocorticoids are potent anti-inflammatory steroids whose use in the management of acute pancreatitis remains controversial. Our aim was to examine the effect of crosstalk between pancreatic acinar cells (PACs) and stellate cells (PSCs) on p38 MAPK and glucocorticoid receptor (GR) activation and to assess the impact of hydrocortisone on these events.

METHODS

The long-term co-culture setting for mouse PACs and PSCs developed in our laboratory was used. Parallel 4d mono- and co-cultures with or without 10 nM hydrocortisone were performed followed by immunocytochemical analysis of nuclear GR and phospho-p38 MAPK (pp38 MAPK).

RESULTS

Hydrocortisone inhibited pp38 MAPK up-regulation evoked by co-culture in PACs and PSCs and increased nuclear translocation of GR in PAC monocultures and in co-cultured PACs and PSCs. In PSC monocultures and co-cultured PACs, ligand-independent expression of nuclear GR was observed. In the former no change in nuclear GR but a significant decrease in total GR as analyzed by Western blot was caused by hydrocortisone.

CONCLUSIONS

Cellular microenvironment plays a significant role on p38 MAPK and GR activation in PACs and PSCs. Hydrocortisone is an effective means to inhibit p38 MAPK activation in PACs and PSCs. Both ligand-dependent and -independent regulatory roles for GR are suggested in the exocrine pancreas.

Experimental Acute Pancreatitis Models: History, Current Status, and Role in Translational Research

Acute pancreatitis is a potentially severe inflammatory disease that may be associated with a substantial morbidity and mortality. Currently there is no specific treatment for the disease, which indicates an ongoing demand for research into its pathogenesis and development of new therapeutic strategies. Due to the unpredictable course of acute pancreatitis and relatively concealed anatomical site in the retro-peritoneum, research on the human pancreas remains challenging. As a result, for over the last 100 years studies on the pathogenesis of this disease have heavily relied on animal models. This review aims to summarize different animal models of acute pancreatitis from the past to present and discuss their main characteristics and applications. It identifies key studies that have enhanced our current understanding of the pathogenesis of acute pancreatitis and highlights the instrumental role of animal models in translational research for developing novel therapies.

Protective Effects of Emodin-Induced Neutrophil Apoptosis via the Ca2+-Caspase 12 Pathway against SIRS in Rats with Severe Acute Pancreatitis

Severe acute pancreatitis (SAP) results in high mortality. This is partly because of early multiple organ dysfunction syndromes that are usually caused by systemic inflammatory response syndrome (SIRS). Many studies have reported the beneficial effects of emodin against SAP with SIRS. However, the exact mechanism underlying the effect of emodin remains unclear. This study was designed to explore the protective effects and underlying mechanisms of emodin against SIRS in rats with SAP. In the present study, cytosolic Ca²⁺ levels, calpain 1 activity, and the expression levels of the active fragments of caspases 12 and 3 decreased in neutrophils from rats with SAP and increased after treatment with emodin. Delayed neutrophil apoptosis occurred in rats with SAP and emodin was able to reverse this delayed apoptosis and inhibit SIRS. The effect of emodin on calpain 1 activity, the expression levels of the active fragments of caspases 12 and 3, neutrophil apoptosis, and SIRS scores were attenuated by PD150606 (an inhibitor of calpain). These results suggest that emodin inhibits SIRS in rats with SAP by inducing circulating neutrophil apoptosis via the Ca²⁺-calpain 1-caspase 12-caspase 3 signaling pathway.

Effect of Previous High Glutamine Infusion on Inflammatory Mediators and Mortality in an Acute Pancreatitis Model

Parenteral glutamine supplementation in acute inflammatory conditions is controversial. We evaluated the inflammatory and survival responses after parenteral glutamine infusion in sodium taurocholate-induced acute pancreatitis (AP) model. Lewis rats received 1 g/kg parenteral glutamine (n = 42), saline (n = 44), or no treatment (n = 45) for 48 h before AP induction. Blood, lung, and liver samples were collected 2, 12, and 24 h after AP to measure serum cytokines levels and tissue heat shock protein (HSP) expression. From each group, 20 animals were not sacrificed after AP for a 7-day mortality study. Serum cytokine levels did not differ among groups at any time point, but the intragroup analysis over time showed higher interferon-γ only in the nontreatment and saline groups at 2 h (versus 12 and 24 h; both p ≤ 0.05). The glutamine group exhibited greater lung and liver HSP90 expression than did the nontreatment group at 2 and 12 h, respectively; greater liver HSP90 and HSP70 expression than did the saline group at 12 h; and smaller lung HSP70 and liver HSP90 expression than did the nontreatment group at 24 h (all p ≤ 0.019). The 7-day mortality rate did not differ among groups. In experimental AP, pretreatment with parenteral glutamine was safe and improved early inflammatory mediator profiles without affecting mortality.

Poly(ADP-ribose) polymerase inhibition suppresses inflammation and promotes recovery from adrenal injury in a rat model of acute necrotizing pancreatitis

Background

Poly(ADP-ribose) polymerase (PARP) participates in multi-organ failure in various inflammatory diseases including acute necrotizing pancreatitis (ANP). Since pancreatitis-associated adrenal insufficiency is partly caused by inflammatory damage to the adrenal cortex, we examined whether PARP antagonism could alleviate adrenal insufficiency in a rat model of ANP.

Methods

ANP was induced by retrograde infusion of sodium taurocholate into the bile-pancreatic duct. At 30 min prior to taurocholate infusion, rats were pretreated with the PARP inhibitor 3-Aminobenzamide (3-AB, 20 mg/kg) or vehicle. Pancreatic pathological injury, adrenal histology, neutrophil infiltration, cell apoptosis, and serum corticosterone level were assessed at various times points. Activities of poly(ADP-ribosyl)ated protein (PAR), nuclear factor-kappaB (NF-kB), tumor necrosis factor-α (TNF-α), intercellular adhesion molecule-1 (ICAM-1) and inducible nitric oxide synthase (iNOS) in the adrenal were also examined.

Results

PARP overactivation in ANP rats is associated with reduced serum corticosterone level and marked cellular alterations in adrenocortical tissue. Inflammatory stress caused by ANP reduced adrenal corticosterone release. 3-AB reduced the activation of PARP and inflammatory markers, decreased myeloperoxidase activity, attenuated adrenal morphologic lesions and cells apoptosis, simultaneously improved the impaired adrenal function.

Conclusions

Our data demonstrate the involvement of PARP overactivation in the pathogenesis of adrenal dysfunction after ANP. PARP inhibition may suppress inflammation and promote functional recovery from adrenal injury.

Dexamethasone down-regulates the inflammatory mediators but fails to reduce the tissue injury in the lung of acute pancreatitis rat models

Pulmonary complications are frequent in the course of acute pancreatitis. We investigate the effects of dexamethasone on lung injury in mild and severe AP. Mild and severe acute pancreatitis was induced in rats by bile-pancreatic duct obstruction and infusion of 3.5% sodium taurocholate into the bile-pancreatic duct, respectively. Dexamethasone (1 mg/kg) was given by intramuscular injection 1 h after acute pancreatitis. Plasma amylase activity was measured to evaluate the pancreas damage. Lungs were harvested for analysing mRNA expression of monocyte chemoattractant protein-1 (MCP-1), cytokine-induced neutrophil chemoattractant (CINC), P-selectin and intercellular adhesion molecule-1 (ICAM-1), myeloperoxidase (MPO) activity (as index of neutrophil infiltration) and histological examination. Dexamethasone reduced the hyperamylasemia and hindered the pulmonary upregulation of MCP-1, CINC, P-selectin and ICAM-1, in both mild and severe acute pancreatitis. Despite this, dexamethasone treatment failed to reduce MPO activity and histological alterations developed in lungs during acute pancreatitis, either in bile-pancreatic duct obstruction or sodium taurocholate model. We conclude that pulmonary local factors different from inflammatory mediators contribute to leukocyte recruitment, so that although dexamethasone down-regulated the lung expression of chemokines and adhesion molecules during acute pancreatitis it was not able to prevent leukocyte infiltration, which could be responsible for maintaining the lung injury in either mild or severe acute pancreatitis.

Review of experimental animal models of biliary acute pancreatitis and recent advances in basic research

Acute pancreatitis (AP) is a formidable disease, which, in severe forms, causes significant mortality. Biliary AP, or gallstone obstruction-associated AP, accounts for 30-50% of all clinical cases of AP. In biliary AP, pancreatic acinar cell (PAC) death (the initiating event in the disease) is believed to occur as acinar cells make contact with bile salts when bile refluxes into the pancreatic duct. Recent advances have unveiled an important receptor responsible for the major function of bile acids on acinar cells, namely, the cell surface G-protein-coupled bile acid receptor-1 (Gpbar1), located in the apical pole of the PAC. High concentrations of bile acids induce cytosolic Ca(2+) overload and inhibit mitochondrial adenosine triphosphate (ATP) production, resulting in cell injury to both PACs and pancreatic ductal epithelial cells. Various bile salts are employed to induce experimental AP, most commonly sodium taurocholate. Recent characterization of taurolithocholic acid 3-sulphate on PACs has led researchers to focus on this bile salt because of its potency in causing acinar cell injury at relatively low, sub-detergent concentrations, which strongly implicates action via the receptor Gpbar1. Improved surgical techniques have enabled the infusion of bile salts into the pancreatic duct to induce experimental biliary AP in mice, which allows the use of these transgenic animals as powerful tools. This review summarizes recent findings using transgenic mice in experimental biliary AP.

Study of dexamethasone, baicalin and octreotide on brain injury of rats with severe acute pancreatitis

OBJECTIVE

To investigate the protecting effects of dexamethasone (DXM), baicalin and octreotide on brain injury of rats with severe acute pancreatitis (SAP) and explore their underlying mechanism.

METHODS

This experiment was divided into two different parts: (1) In the first part, 90 SAP rats were randomly divided into a model control group and a DXM treated group (n = 45, respectively). (2) In the second part, 135 SAP rats were randomly divided into a model control group, a baicalin treated group and an octreotide treated group (n = 45, respectively). In two different experiments, the same number of normal rats were considered as the sham-operated group (n = 45, respectively). At 3, 6 and 12 h after operation, the pathological changes in the brain were observed. The expression levels of nuclear factor-κB (NF-κB), Bax and Bcl-2 proteins were detected and apoptosis indexes were calculated, using brain tissue microarray section.

RESULTS

(1) First part: The expression levels of Bax and Bcl-2 were significantly higher in the DXM treated group than those in the model control group at different time points, while the content of NF-κB protein and pathological changes were significantly lower in the treated group than those in the model control group (P < 0.05, P < 0.01 or P < 0.001). But the apoptotic indexes of brain tissue were not significantly different at different time points (P > 0.05). (2) Second part: At all time points after operation, the expression levels of NF-κB in the brain of treated groups were, to varying degrees, significantly lower than those in the model control group while the expression levels of Bcl-2 protein in baicalin and octreotide group were significantly higher than those in model control group (P < 0.01, P < 0.01 and P < 0.05, respectively). At 12 h after operation, the expression level of Bax protein in baicalin treated group was significantly higher than those in model control group and octreotide treated group (P < 0.05 and P < 0.01, respectively).

CONCLUSIONS

Dexamethasone, baicalin and octreotide can exert protective effects against brain injury in SAP rats mainly through inhibiting the expression of NF-κB protein.

Clinical observation on the effect of dexamethasone and Chinese herbal decoction for purgation in severe acute pancreatitis patients

OBJECTIVE

To investigate the effect of dexamethasone (Dx) combined with modified Dachengqi Decoction (DCQD), a Chinese herbal decoction for purgation, on patients with severe acute on patients with severe acute, a Chinese herbal decoction for purgation, on patients with severe acute pancreatitis (SAP) accompanied with systematic inflammatory response syndrome (SIRS).

METHODS

A total of 81 patients diagnosed as SAP were randomly assigned to a control group or treatment group according to a random number table generated from an SPSS software. The patients in the control group (38 cases) received standard treatment and Chinese herbal decoction for purgation; those in the treatment group (43 cases) received additional 1 mg/(kg·d) dexamethasone (Dx) treatment for three days based on the above treatment. The mortality rate, acute respiratory distress syndrome (ARDS), renal failure, hemorrhage, sepsis, pancreatic pseudocyst, pancreatic abscess, operability, and days of hospitalization were compared between the two groups.

RESULTS

Three patients in the control group and eight patients in the treatment group dropped out from the study with a drop-out rate of 7.8% and 18.6%, respectively, and no statistics difference was shown between the two groups (P>0.05). Dx treatment significantly reduced ARDS rate and shortened the length of hospitalization compared to those in the control group (7/35, 20.0% versus 15/35, 42.9%, P=0.0394; 32.5±13.2 days versus 40.2±17.5 days, P=0.0344). Other parameters including the mortality rate were not significant different between the two groups.

CONCLUSION

Dx combined with DCQD could decrease the risk of developing ARDS in SAP patients with SIRS and shorten their length of hospitalization.

Effects of dexamethasone on intercellular adhesion molecule 1 expression and inflammatory response in necrotizing acute pancreatitis in rats

OBJECTIVES

Adhesion molecules are involved in the inflammatory response during acute pancreatitis (AP). We investigated the effect of dexamethasone (Dx) on intercellular adhesion molecule 1 (ICAM-1) expression during AP and its consequences on leukocyte recruitment and pancreatic damage.

METHODS

Acute pancreatitis was induced in rats by 3.5% sodium taurocholate for 3 hours and 6 hours. Dexamethasone (1 mg/kg) was administered either 30 minutes before or 1 hour after inducing AP. Messenger RNA ICAM-1 expression in pancreas and lung, membrane-bound ICAM-1 in acinar cells, and ICAM-1 plasma levels were analyzed. Histological examination of the pancreas and neutrophil infiltration in pancreas and lung were also measured.

RESULTS

Prophylactic and therapeutic administration of Dx down-regulated ICAM-1 expression in pancreas and lung from early AP. Dexamethasone given before AP reduced the pancreatic damage, but lung inflammation was not prevented. Therapeutic Dx treatment was ineffective in avoiding leukocyte recruitment into the pancreas and lung in rats with AP. High ICAM-1 concentration was found in plasma during AP, which was not reduced by Dx treatments.

CONCLUSIONS

Dexamethasone down-regulates ICAM-1 expression, but it does not completely prevent leukocyte recruitment during sodium taurocholate-induced AP.

Mechanisms of dexamethasone-mediated chemokine down-regulation in mild and severe acute pancreatitis

This study aimed to investigate the role of therapeutic dexamethasone (Dex) treatment on the mechanisms underlying chemokine expression during mild and severe acute pancreatitis (AP) experimentally induced in rats. Regardless of the AP severity, Dex (1 mg/kg), administered 1 h after AP, reduced the acinar cell activation of extracellular signal-regulated kinase (ERK) and c-Jun-NH(2)-terminal kinase (JNK) but failed to reduce p38-mitogen-activated protein kinase (MAPK) in severe AP. In both AP models, Dex inhibited the activation of nuclear factor-kappaB (NF-kappaB) and signal transducers and activators of transcription (STAT) factors. All of this resulted in pancreatic down-regulation of the chemokines monocyte chemoattractant protein-1 (MCP-1) and cytokine-induced neutrophil chemoattractant (CINC). Lower plasma chemokine levels as well as decreased amylasemia, hematocrit and plasma interleukin-1beta (Il-1beta) levels were found either in mild or severe AP treated with Dex. Pancreatic neutrophil infiltration was attenuated by Dex in mild but not in severe AP. In conclusion, by targeting MAPKs, NF-kappaB and STAT3 pathways, Dex treatment down-regulated the chemokine expression in different cell sources during mild and severe AP, resulting in decreased severity of the disease.

The effect of synacthen on acute necrotizing pancreatitis in rats

OBJECTIVES

This study investigates the hypothesis that an adrenocorticotropic hormone-analog therapy may ameliorate relative adrenal insufficiency in the early phase of acute necrotizing pancreatitis (NP) by boosting endogenous glucocorticoid production.

METHODS

Forty Wistar rats with taurocholate-induced NP were divided into 5 groups: the first group received low-dose Synacthen (0.5 mg/kg); the second, high-dose Synacthen (5mg/kg); the third,low-dose cortisol (10 mg/kg); the fourth, high-dose cortisol (100 mg/kg); and the fifth, the control group, received no treatment. All animals were killed after 6 hours: concentrations of plasma corticosterone, interleukin 1 (IL-1), IL-6, IL-10, tumor necrosis factor alpha, amylase, and lipase in ascites, myeloperoxidase activity in the pancreas, and a histological score were evaluated.

RESULTS

Corticosterone increased neither in the low-dose nor in the high-dose Synacthen group. Synacthen did not improve the early course of NP in terms of laboratory and histological results. A reduction of pancreatic necrosis and inflammation was observed in the low-dose cortisol group.

CONCLUSIONS

Endogenous glucocorticoid release seemed to be at its maximum during the early stage of NP and could not be further increased by Synacthen. Low-dose exogenous cortisol ameliorated the disease. These findings support the existence of relative adrenal insufficiency in the early phase of acute NP.

Protecting effects of dexamethasone on thymus of rats with severe acute pancreatitis

Purpose. To study the protecting effects of dexamethasone on thymus of rats with severe acute pancreatitis (SAP). Methods. The SAP rats were randomly assigned to the model group and dexamethasone-treated group, the other normal healthy rats were assigned to the sham operation group. The rat survival, thymus pathological changes, apoptotic index, as well as expression levels of NF-κB, P-selectin, Bax, Bcl-2, and Caspase-3 protein of all groups were observed, respectively, at 3 hours, 6 hours, and 12 hours. The contents of amylase and endotoxin in plasma as well as the contents of TNF-α, PLA2, and NO in serum were determined. Results. There was no marked difference between the model group and treated group in survival. The contents of different indexes in blood of treated group were lower than those of the model group to various degrees at different time points. The thymus pathological score was lower in treated group than in model group at 12 hours.The treated group in Caspase-3 protein expression of thymus significantly exceeded the model group at 12 hours. The apoptotic index was significantly higher in treated group than in model group. Conclusion. Dexamethasone has protecting effects on thymus of SAP rats.

Effects of glucocorticoid agonist and antagonist on the pathogenesis of L-arginine-induced acute pancreatitis in rat

OBJECTIVES

To investigate the consequences of treatment with an exogenous glucocorticoid agonist (methylprednisolone) and antagonist (RU-38486) on the local and systemic responses in L-arginine-induced acute pancreatitis in rats.

METHODS

The methylprednisolone and RU-38486 were administered just before pancreatitis induction. Plasma amylase activity, interleukin 6 activity, pancreatic weight/body weight ratio, plasma macrophage migration inhibitory factor (MIF) concentration, and pancreatic nuclear transcription factor (NF) kappaB activity were determined. The extents of pancreas, liver, and lung injuries were assessed by histology.

RESULTS

Acute pancreatitis resulted in NF-kappaB activation and proinflammatory cytokine release in rats. In the glucocorticoid agonist group, plasma amylase and interleukin 6 levels were significantly decreased as compared with those of RU-38486 and nontreated groups. Antagonist treatment led to significantly higher MIF production at 8 and 12 hours after L-arginine injection as compared with the agonist-treated and nontreated groups. Glucocorticoid agonist treatment significantly decreased the level of NF-kappaB 24 hours after pancreatitis induction. Histological investigations showed protective effect of agonist treatment on acute pancreatitis-induced tissue damage in the pancreas and lung.

CONCLUSIONS

These results corroborated the importance of MIF in acute pancreatitis. The glucocorticoid-dependent mechanisms seem to play a crucial role in the control of the inflammatory response and tissue damage in L-arginine-induced experimental acute pancreatitis.

Dexamethasone affects inflammation but not trypsinogen activation in experimental acute pancreatitis

BACKGROUND/AIMS

Trypsinogen activation and inflammation are early events in acute pancreatitis. This experimental study aimed to show the effects of dexamethasone on them.

METHODS

Cerulein and taurocholate pancreatitis were induced in 2 groups of 12 Wistar rats each. Six animals per group were injected with dexamethasone 1 h prior to the induction of acute pancreatitis. Amylase, phospholipase A2, TNF-alpha, IL-6, IL-10, alpha2-antiplasmin in plasma and trypsinogen activation peptide (TAP) in urine were measured in healthy rats, then 0.5 and 6 h after pancreatitis induction. A severity score based on edema, necrosis and ascites was calculated at 6 h. TNF-alpha, IL-6 and IL-10 were measured 0.5 h after laparotomy in a control sham-operated group of 6 rats.

RESULTS

Inflammatory markers increased early in the course of both mild and severe acute pancreatitis and were significantly lowered by dexamethasone. The severity score was higher in taurocholate than in cerulein pancreatitis. It was significantly decreased by dexamethasone only in rats with mild pancreatitis. TAP remained unchanged in mild pancreatitis compared to healthy animals but increased late in the course of taurocholate pancreatitis. Trypsinogen activation was not affected by dexamethasone at all.

CONCLUSION

Inflammation occurred earlier than the increase in urinary TAP in severe pancreatitis in rats. Dexamethasone inhibited inflammation but had no influence on TAP levels in experimental mild and severe acute pancreatitis.

Pathogenesis and treatment of acute pancreatitis with liver injury

Acute pancreatitis is a frequent acute abdomen in clinic, causes damages not only to pancreas, but also to distant organs. Liver is one of the mainly involved organs. The development of liver injury may aggravate pancreatitis. The pathogenesis of acute pancreatitis with liver injury is mainly related to cytokines, pancreatic enzyme, oxidative stress, microcirculation disturbance, apoptosis and pancreatitis-associated ascitic fluid, etc. Its treatment is also to eradicate these factors. However, more methods are still under animal studies. Their clinical application requires further study.

Effects of large dose of dexamethasone on inflammatory mediators and pancreatic cell apoptosis of rats with severe acute pancreatitis

AIM: To investigate the influence of high dose of dexamethasone on inflammatory mediators and apoptosis of rats with severe acute pancreatitis (SAP).

METHODS: SAP rats were randomly assigned to the model group and treatment group while the normal rats were assigned to the sham operation group. The mortality, ascite volumes, ascites/body weight ratio and pancreas pathological changes of all rats were observed at 3, 6 and 12 h after operation. Their contents of amylase and endotoxin in plasma and contents of tumor necrosis factor (TNF-α), phospholipase A₂ (PLA₂) and IL-6 in serum were also determined. The microarray sections of their pancreatic tissues were prepared, terminal transferase dUTP nick end labeling (TUNEL) staining was performed and apoptotic indexes were calculated.

RESULTS: There was no marked difference between treatment group and model group in survival. The contents of amylase and endotoxin in plasma and contents of TNF-α, PLA₂ and IL-6 in serum, ascite volumes, ascites/body weight ratio and pancreas pathological scores were all lower in treatment group than in model group to different extents at different time points [P < 0.05, 58.3 (26.4) ng/L vs 77.535 (42.157) ng/L in TNF-α content, 8.00 (2.00) points vs 9.00 (2.00) points in pathological score of pancreas respectively; P < 0.01, 0.042 (0.018) EU/mL vs 0.056 (0.0195) EU/mL in endotoxin content, 7791 (1863) U/L vs 9195 (1298) U/L in plasma amylase content, 1.53 (0.79) vs 2.38 (1.10) in ascites/body weight ratio, 8.00 (1.00) points vs 11.00 (1.50) points in pathological score of pancreas; P < 0.001, 3.36 (1.56) ng/L vs 5.65 (1.08) ng/L in IL-6 content, 4.50 (2.00) vs 7.20 (2.00), 4.20 (1.60) vs 6.40 (2.30), 3.40 (2.70) vs 7.90 (1.70) in ascite volumes, respectively]. The apoptotic indexes of pancreas head and pancreas tail were all higher in treatment group than in model group at 6 h [P < 0.01, 0.00 (2.00)% vs 0.00 (0.00)%, 0.20 (1.80) vs 0.00 (0.00) in apoptosis indexes, respectively].

CONCLUSION: The mechanism of dexamethasone treatment in acute pancreatitis is related to its inhibition of inflammatory mediator generation and induction of pancreatic acinar cell apoptosis.

Relative adrenal insufficiency in patients with severe acute pancreatitis

OBJECTIVE

Inadequate cortisol levels and adrenal dysfunction may play a role in the pathophysiology of severe acute pancreatitis. This study aimed to analyse the incidence of relative adrenal insufficiency (RAI) in these patients, to identify factors associated with RAI and to describe how adrenal responsiveness affects outcome.

DESIGN

Prospective observational multicenter study.

PATIENTS

Twenty-five patients with severe acute pancreatitis.

INTERVENTIONS

A short Synacthen test (SST) was performed within 5 days after admission to the hospital. The incidence of RAI, defined as an increment after SST of less than 9 microg/dl was the primary endpoint of the study. Serum cortisol was measured at baseline and at 30 and 60 min after administration of 250 microg adrenocorticotropic hormone.

MEASUREMENTS AND RESULTS

Median baseline cortisol level was 26.6 microg/dl, and increased to 43.2 microg/dl and 48.8 microg/dl after 30 min and 60 min respectively. RAI was found in 16% of all patients and in 27% of patients with organ dysfunction. Patients with RAI were more severely ill and had higher SOFA scores from days 4 to 7 after admission. All patients with RAI developed pancreatic necrosis, and all of them needed surgical intervention. Twenty-eight-day mortality was significantly higher in patients with RAI (75% vs. 5%, p =0.007). Patients who died had a lower increment in cortisol levels after the SST than patients who survived.

CONCLUSION

RAI is frequent in patients with severe acute pancreatitis and organ dysfunction. It occurs in patients with more severe pancreatitis and is associated with increased mortality.

Acute pancreatitis: animal models and recent advances in basic research

Acute pancreatitis (AP) is characterized by edema, acinar cell necrosis, hemorrhage, and severe inflammation of the pancreas. Patients with AP present with elevated blood and urine levels of pancreatic digestive enzymes, such as amylase and lipase. Severe AP may lead to systemic inflammatory response syndrome and multiorgan dysfunction syndrome, which account for the high mortality rate of AP. Although most (>80%) cases of AP are associated with gallstones and alcoholism, some are idiopathic. Although the pathogenesis of AP has not yet been elucidated, a common feature is the premature activation of trypsinogen within pancreatic tissues, which triggers autodigestion of the gland. Recent advances in basic research suggest that etiologic factors including cyclooxygenase-2, substance P, and angiotensin II may have novel roles in this disease. Basic research data obtained thus far have been based on animal models of AP ranging from mild edematous pancreatitis to severe necrotizing pancreatitis. In view of this, an adequate selection of experimental animal models is of paramount importance. Notwithstanding these animal models, it should be emphasized that none of these models mimic the clinical situation where varying degrees of severity usually occur. In this review, commonly used animal models of AP will be critically evaluated. A discussion of recent advances in our knowledge about AP risk factors is also included.

Dexamethasone mediates protection against acute pancreatitis via upregulation of pancreatitis-associated proteins

AIM

To examine the influence of dexamethasone on pancreatitis-associated protein (PAP) gene expression using both in vitro and in vivo models of acute pancreatitis and to study how PAP gene expression correlates with severity of pancreatitis.

METHODS

In vitro, IL-6 stimulated pancreas acinar AR42J cells were cultured with increasing concentrations of dexamethasone and assayed for PAP expression (RT-PCR). In vivo, pancreatitis was induced in rats by retrograde injection of 40 g/L taurocholate into the pancreatic duct. Animals were pretreated with dexamethasone (2 mg/kg) daily or saline for 4 d. Pancreata and serum were harvested after 24 h and gene expression levels of PAP I, II and III were measured by RT-PCR. Severity of pancreatitis was based on serum amylase, pancreatic wet weight, and histopathological score.

RESULTS

In vitro, dexamethasone and IL-6 induced a marked transcription of PAP I, II and III genes in AR42J cells at 24 h (P < 0.05 for all comparisons). In vivo, pancreas mRNA levels of PAP I, II or III increased by 2.6-fold, 1.9-fold, and 1.3-fold respectively after dexamethasone treatment, compared with saline treated animals. Serum amylase levels and edema were significantly lower in the dexamethasone group compared with the saline group. Histopathologic evaluation revealed less inflammation and necrosis in pancreata obtained from dexamethasone treated animals (P < 0.05).

CONCLUSION

Dexamethasone significantly decreases the severity of pancreatitis. The protective mechanism of dexamethasone may be via upregulating PAP gene expression during injury.

Toxic effect of pregnancy intrahepatic cholestasis on liver and placenta in pregnant rats

AIM: To investigate the toxic effect of intrahepatic cholestasis of pregnancy (ICP) on the liver and placenta in pregnant rats.

METHODS: The animal model of ICP was induced by 17-a-ethinylestradiol and progesterone. Pathohistological changes of the liver and placenta of the pregnant rats were observed under light and electronic microscope.

RESULTS: The levels of serum alanine transaminase (ALT), aspartate transaminase (AST), and total bile acid (TBA) were significantly higher in ICP rats than the control (AST: 3 784±155 vs 747±158; ALT: 7 076±220 vs 847±198; TBA: 78.5±4.5 vs 25.2±3.7; P<0.01 for all of the three). Granule- and vacuole-like cells were observed in liver of ICP rats under light microscope and Bile canaliculi were dilated and deposition of substances with high electronic density was found in bile canaliculi and hepatocytes of ICP rats by electronic microscopy. Granule- and vacuole-like changes were also found in some placenta syncytiotrophoblast of ICP rats by light microscopy.

CONCLUSION: ICP with hyperbileacidemia has marked toxicity to hepatocytes and placenta trophoblasts of pregnant rats.