Cholecystokinin blockade alters the systemic immune response in rats with acute pancreatitis

Regulation of nutrition-associated receptors in blood monocytes of normal weight and obese humans

Obesity, type 2 diabetes and associated metabolic diseases are characterized by low-grade systemic inflammation which involves interplay of nutrition and monocyte/macrophage functions. We suggested that some factors such as nutrient components, neuropeptides involved in the control of gastrointestinal functions, and gastrointestinal hormones might influence immune cell functions and in this way contribute to the disease pathogenesis. The aim of this study was to investigate the mRNA expression of twelve nutrition-associated receptors in peripheral blood mononuclear cells (PBMC), isolated monocytes and monocyte-derived macrophages and their regulation under the switching from the high-carbohydrate low-fat diet to the low-carbohydrate high-fat (LC/HFD) isocaloric diet in healthy humans. The mRNA expression of receptors for short chain fatty acids (GPR41, GPR43), bile acids (TGR5), incretins (GIPR, GLP1R), cholecystokinin (CCKAR), neuropeptides VIP and PACAP (VIPR1, VIPR2), and neurotensin (NTSR1) was detected in PBMC and monocytes, while GPR41, GPR43, GIPR, TGR5, and VIPR1 were found in macrophages. Correlations of the receptor expression in monocytes with a range of metabolic and inflammatory markers were found. In non-obese subjects, the dietary switch to LC/HFD induced the increase of GPR43 and VIPR1 expression in monocytes. No significant differences of receptor expression between normal weight and moderately obese subjects were found. Our study characterized for the first time the expression pattern of nutrition-associated receptors in human blood monocytes and its dietary-induced changes linking metabolic responses to nutrition with immune functions in health and metabolic diseases.

Lasting inhibition of receptor-mediated calcium oscillations in pancreatic acini by neutrophil respiratory burst--a novel mechanism for secretory blockade in acute pancreatitis?

Although overwhelming evidence indicates that neutrophil infiltration is an early event in acute pancreatitis, the effect of neutrophil respiratory burst on pancreatic acini has not been investigated. In the present work, effect of fMLP-induced neutrophil respiratory burst on pancreatic acini was examined. It was found that neutrophil respiratory burst blocked calcium oscillations induced by cholecystokinin or by acetylcholine. Such lasting inhibition was dependent on the density of bursting neutrophils and could be overcome by increased agonist concentration. Inhibition of cholecystokinin stimulation was also observed in AR4-2J cells. In sharp contrast, neutrophil respiratory burst had no effect on calcium oscillations induced by phenylephrine (PE), vasopressin, or by ATP in rat hepatocytes. These data together suggest that inhibition of receptor-mediated calcium oscillations in pancreatic acini by neutrophil respiratory burst would lead to secretory blockade, which is a hallmark of acute pancreatitis. The present work has important implications for clinical treatment and management of acute pancreatitis.

Effect of dexamethasone on peripheral blood leukocyte immune response in bile-pancreatic duct obstruction-induced acute pancreatitis

Our aim was to analyze the effects of dexamethasone (Dx) (1mg/kg), prophylactically or therapeutically administered, on the inflammatory response triggered by peripheral blood leukocytes during acute pancreatitis (AP) induced in rats by bile-pancreatic duct obstruction (BPDO) and their consequences in the progress of the disease. Flow cytometry was used to analyze the distribution of the major leukocyte populations, the CD45 expression and the activated state of monocytes as reflected by the membrane-bound intercellular adhesion molecule-1 (ICAM-1) and the production of tumor necrosis factor-alpha (TNF-alpha) and monocyte chemoattract protein-1 (MCP-1) in response to lipopolysaccaride (LPS). Interleukin-6 (IL-6) plasma levels, pancreatic fluid content and histology of pancreas sections were also evaluated. Dx, given either before or after AP, blunted the monocyte increase induced by BPDO-induced AP, but did not change lymphocyte and neutrophil counts. Membrane-bound ICAM-1 expression did not vary in circulating monocytes during BPDO, either in Dx-treated or non-treated rats. Both Dx treatments inhibited TNF-alpha and MCP-1 production in non-stimulated and LPS-stimulated monocytes, whose response was found to be higher than in controls from early AP. Leukocyte CD45 expression was found to be reduced in rats with AP and shifted to control values in Dx-post-treated rats. Cytokinemia as well as pancreatic edema and leukocyte infiltration found in BPDO rats were reduced by Dx given either before or after AP. We conclude that prophylactic and therapeutic Dx treatments inhibited the inflammatory response triggered by circulating leukocytes in rats with BPDO-induced AP, thus contributing to reducing the severity of the disease.

From acute pancreatitis to end-organ injury: mechanisms of acute lung injury

BACKGROUND

Multi-organ dysfunction, and in particular lung injury, is often responsible for the unfavorable outcome of patients with severe acute pancreatitis. Understanding of the mechanisms by which local inflammation in the pancreas leads to end-organ injury is crucial for the development of new therapeutic strategies.

METHODS

A MEDLINE search was performed with the terms "acute pancreatitis," "lung injury," "inflammatory response," "SIRS," and "multi-organ dysfunction." Pertinent articles were selected for analysis.

RESULTS

Modulation of the inflammatory response using a combination of immunomodulatory agents may decrease the incidence of severe pancreatitis-related acute lung injury and acute respiratory distress syndrome.

CONCLUSION

Clinical trials are of utmost importance to establish the validity of such strategies.

Effect of somatostatin on immune inflammatory response in patients with severe acute pancreatitis

OBJECTIVE

Somatostatin regulates immune inflammatory response via apoptosis and adhesion of leukocytes in many diseases. This article reported a study that aimed to observe the mechanism and effect of somatostatin on the immune inflammatory response through apoptosis and adhesion of leukocytes in severe acute pancreatitis.

METHODS

Thirty-eight patients with severe acute pancreatitis, that fulfilled the guidelines for the treatment of severe acute pancreatitis of China and Balthazar computed tomography severity index (>or=5) were enrolled consecutively. Nineteen of these patients received our routine treatment and 19 received additional somatostatin. In all patients the expressions of CD4, CD8, CD95/CD95 ligand and CD18/CD62 ligand on leukocytes were determined by flow cytometry, both upon admission and on the fourth day. Thirty healthy volunteers constituted the normal healthy group.

RESULTS

In the treatment group, CD4, CD4:CD8 ratio and CD62 ligand on leukocytes increased from 11.4+/-8.2, 0.47+/-0.10 and 25.5+/-9.2 to 22.1+/-9.7, 0.68+/-0.11 and 36.2+/-11.7 (P<0.05) respectively, while CD95 ligand on both lymphocyte and polymorphonuclear cells increased from 0.65+/-0.21 and 0.76+/-0.29 to 1.18+/-0.32 and 1.58+/-0.43 after treatment with somatostatin (P<0.05). Furthermore, lactate dehydrogenase, aspartate aminotransferase, amylase, C reactive protein and acute physiology and chronic healthy evaluation (APACHE II) score in the treatment group reduced faster than those in the control group (P<0.05), though there was no difference in mortality (15.7% vs 5.3%) between the two patient groups (P>0.05).

CONCLUSION

Somatostatin can modulate the immune inflammatory response and the severity of severe acute pancreatitis through apoptosis and adhesion of leukocytes, but this modulatory effect by itself is not strong enough to improve the final.

Effects of octreotide on platelet parameters in patients with acute pancreatitis

AIM: To investigate the changes of platelet parameters in patients with mild and severe acute pancreatitis (MAP and SAP) after treated with octreotide.

METHODS: The full-automatic blood cell counter was used to obtain the platelet count (PLT), mean platelet volume (MPV), and platelet distribution width (PDW) in the patients with MAP and SAP before and 1 wk after treatment with octreotide.

RESULTS: The platelet parameters of the patients with MAP were not significantly different from that of the normal controls. One week after treatment, there was still no significant change in the PLT. However, the MPV and PDW were increased markedly (10.88±2.40 vs 10.11±1.66, P < 0.05; 17.98±4.41 vs 16.62±1.38,P < 0.05). In patients with SAP, the PLT was decreased markedly (161.61±68.30 vs 191.60±31.98, P < 0.05), and the MPV and PDW were increased markedly (11.82±2.33vs 9.81±0.79, P < 0.01; 19.33±7.07 vs 16.36±0.51,P < 0.05) as compared with those in the normal controls. One week after treatment, the PLT was notably elevated (251.61±84.07 vs 161.61±68.30, P < 0.01), while the MPV and PDW were not changed (P >0.05) as compared with those before treatment. For SAP, the PLT increased more (112.53±89.31 vs 57.81±68.24, P<0.05), and the MPV and PDW decreased more (1.29±2.79 vs -0.17±2.04, P < 0.01; 2.75±8.81 vs -0.89±3.44, P < 0.01) at 1 wk in the octreotide treatment patients as compared with those of general treatment ones.

CONCLUSION: The platelet parameters can reflect the severeness of acute pancreatitis. Octreotide can improve the microcirculation by decreasing MPV and PDW, increasing PLT.

Kinetic study of TNF-alpha production and its regulatory mechanisms in acinar cells during acute pancreatitis induced by bile-pancreatic duct obstruction

Cytokines play a critical role in acute pancreatitis (AP) but the contribution of different cell sources to cytokine production is unclear. Unfortunately, there are no data concerning the molecular mechanisms involved in the inflammatory response in humans during AP. For this reason, the aim of this study was to analyse the ability of acinar cells, in comparison with leukocytes, to produce TNF-alpha at different stages of AP induced in rats by bile-pancreatic duct obstruction (BPDO) and to investigate the time course of oxidant-sensitive mechanisms involved in cytokine production. The role of oxygen free radicals as messengers of the mechanisms underlying acinar cell TNF-alpha production was assessed in BPDO rats treated with N-acetylcysteine (NAC). While monocytes were not able to produce TNF-alpha until 12 h after inducing AP, acinar cells triggered TNF-alpha production from 6 h after BPDO, at which time the pancreas develops maximal oxidative stress. Phosphorylated p38-MAPK and activated NF-kappaB were detected in acinar cells from 6 h after BPDO. NAC treatment reduced pancreatic glutathione depletion during the early stages of AP and attenuated the activation of p38-MAPK and NF-kappaB for 48 h following BPDO. As a result, acinar cells in NAC-treated rats failed to produce TNF-alpha during AP. In addition, NAC delayed monocyte TNF-alpha production, thereby maintaining low TNF-alpha levels in plasma during BPDO. In conclusion, acinar cells contribute directly to the inflammatory response during BPDO-induced AP by producing TNF-alpha even before inflammatory cells in the peripheral blood. The blockade of oxidant-mediated signal transduction pathways induced by NAC treatment prevented acinar cell TNF-alpha production.

Deletion of the CCK2 receptor gene reduces mechanical sensitivity and abolishes the development of hyperalgesia in mononeuropathic mice

Previous studies suggest that cholecystokinin (CCK) is implicated in the modulation of pain sensitivity and the development of neuropathic pain. We used CCK(2) receptor deficient (CCK(2) (-/-)) mice and assessed their mechanical sensitivity using Von Frey filaments, as well as the development and time course of mechanical hyperalgesia in a model of neuropathic pain. We found that CCK(2) (-/-) mice displayed mechanical hyposensitivity, which was reversed to the level of wild-type animals after administration of naloxone (0.1-10 mg/kg). On the other hand, injection of L-365260 (0.01-1 mg/kg), an antagonist of CCK(2) receptors, decreased dose-dependently, mechanical sensitivity in wild-type mice. The mechanism of reduced mechanical sensitivity in CCK(2) (-/-) mice may be explained by changes in interactions between CCK and opioid systems. Indeed, CCK(2) (-/-) mice natively expressed higher levels of lumbar CCK(1), opioid delta and kappa receptors. Next, we found that CCK(2) (-/-) mice did not develop mechanical hyperalgesia in the Bennett's neuropathic pain model. Induction of neuropathy resulted in decrease of lumbar pro-opiomelanocortin (POMC) gene expression in wild-type mice, but increase of POMC expression in CCK(2) (-/-) mice. In addition, induction of neuropathy resulted in further increase of opioid delta receptor in CCK(2) (-/-) mice. Gene expression results indicate up-regulation of opioid system in CCK(2) (-/-) mice, which apparently result in decreased neuropathy score. Our study suggests that not only pain sensitivity, but also mechanical sensitivity and the development of neuropathic pain are regulated by antagonistic interactions between CCK and opioid systems.