Experimental acute pancreatitis in PAP/HIP knock-out mice

BACKGROUND AND AIMS: PAP/HIP was first reported as an additional pancreatic secretory protein expressed during the acute phase of pancreatitis. It was shown in vitro to be anti-apoptotic and anti-inflammatory. This study aims to look at whether PAP/HIP plays the same role in vivo. METHODS: A model of caerulein-induced pancreatitis was used to compare the outcome of pancreatitis in PAP/HIP(-/-) and wild-type mice. RESULTS: PAP/HIP(-/-) mice showed the normal phenotype at birth and normal postnatal development. Caerulein-induced pancreatic necrosis was, however, less severe in PAP/HIP(-/-) mice than in wild-type mice, as judged by lower amylasemia and lipasemia levels and smaller areas of necrosis. On the contrary, pancreas from PAP/HIP(-/-) mice was more sensitive to apoptosis, in agreement with the anti-apoptotic effect of PAP/HIP in vitro. Surprisingly, pancreatic inflammation was more extensive in PAP/HIP(-/-) mice, as judged from histological parameters, increased myeloperoxidase activity and increased pro-inflammatory cytokine expression. This result, in apparent contradiction with the limited necrosis observed in these mice, is, however, in agreement with the anti-inflammatory function previously reported in vitro for PAP/HIP. This is supported by the observation that activation of the STAT3/SOCS3 pathway was strongly decreased in the pancreas of PAP/HIP(-/-) mice and by the reversion of the apoptotic and inflammatory phenotypes upon administration of recombinant PAP/HIP to PAP/HIP(-/-) mice. CONCLUSION: The anti-apoptotic and anti-inflammatory functions described in vitro for PAP/HIP have physiological relevance in the pancreas in vivo during caerulein-induced pancreatitis.     

Caerulein-induced acute pancreatitis results in mild lung inflammation and altered respiratory mechanics

Acute lung injury is a common complication of acute pancreatitis (AP) and contributes to the majority of AP-associated deaths. Although some aspects of AP-induced lung inflammation have been demonstrated, investigation of resultant changes in lung function is limited. The aim of this study was to characterize lung injury in caerulein-induced AP. Male Sprague Dawley rats (n = 7-8/group) received 7 injections of caerulein (50 μg/kg) at 12, 24, 48, 72, 96, or 120 hours before measurement of lung impedance mechanics. Bronchoalveolar lavage (BAL), plasma, pancreatic, and lung tissue were collected to determine pancreatic and lung measures of acute inflammation. AP developed between 12 and 24 hours, as indicated by increased plasma amylase activity and pancreatic myeloperoxidase (MPO) activity, edema, and abnormal acinar cells, before beginning to resolve by 48 hours. In the lung, MPO activity peaked at 12 and 96 hours, with BAL cytokine concentrations peaking at 12 hours, followed by lung edema at 24 hours, and BAL cell count at 48 hours. Importantly, no significant changes in BAL protein concentration or arterial blood gas-pH levels were evident over the same period, and only modest changes were observed in respiratory mechanics. Caerulein-induced AP results in minor lung injury, which is not sufficient to allow protein permeability and substantially alter respiratory mechanics.     

Skeletal overgrowth in transgenic mice that overexpress brain natriuretic peptide

Longitudinal bone growth is determined by the process of endochondral ossification in the cartilaginous growth plate, which is located at both ends of vertebrae and long bones and involves many systemic hormones and local regulators. Natriuretic peptides organize a family of three structurally related peptides: atrial natriuretic peptide, brain natriuretic peptide (BNP), and C-type natriuretic peptide. Atrial natriuretic peptide and BNP are cardiac hormones that are produced predominantly by the atrium and ventricle, respectively. C-type natriuretic peptide occurs in a wide variety of tissues, where it acts as a local regulator. These peptides can influence body fluid homeostasis and blood pressure control through the activation of two guanylyl cyclase (GC)-coupled natriuretic peptide receptor subtypes—GC-A and GC-B. We report here marked skeletal overgrowth in transgenic mice that overexpress BNP. Transgenic mice with elevated plasma BNP concentrations exhibited deformed bony skeletons characterized by kyphosis, elongated limbs and paws, and crooked tails. Bone abnormalities resulted from a high turnover of endochondral ossification accompanied by overgrowth of the growth plate. Studies using an in vitro organ culture of embryonic mouse tibias revealed that BNP increases the height of cartilaginous primordium directly, thereby stimulating the total longitudinal bone growth. The present study demonstrates that natriuretic peptides can affect the process of endochondral ossification.     

Human cancers overexpress genes that are specific to a variety of normal human tissues

We have analyzed gene expression data from three different kinds of samples: normal human tissues, human cancer cell lines, and leukemic cells from lymphoid and myeloid leukemia pediatric patients. We have searched for genes that are overexpressed in human cancer and also show specific patterns of tissue-dependent expression in normal tissues. Using the expression data of the normal tissues, we identified 4,346 genes with a high variability of expression and clustered these genes according to their relative expression level. Of 91 stable clusters obtained, 24 clusters included genes preferentially expressed either only in hematopoietic tissues or in hematopoietic and one to two other tissues; 28 clusters included genes preferentially expressed in various nonhematopoietic tissues such as neuronal, testis, liver, kidney, muscle, lung, pancreas, and placenta. Analysis of the expression levels of these two groups of genes in the human cancer cell lines and leukemias identified genes that were highly expressed in cancer cells but not in their normal counterparts and, thus, were overexpressed in the cancers. The different cancer cell lines and leukemias varied in the number and identity of these overexpressed genes. The results indicate that many genes that are overexpressed in human cancer cells are specific to a variety of normal tissues, including normal tissues other than those from which the cancer originated. It is suggested that this general property of cancer cells plays a major role in determining the behavior of the cancers, including their metastatic potential.     

Pomalidomide suppresses cerulein-induced acute pancreatitis in mice

Background  

An overproduction of proinflammatory mediators in severe acute pancreatitis contributes to the systemic inflammatory response, which may lead to multiorgan damage and even death. Thus, inflammatory cytokines, e.g., tumor necrosis factor (TNF)-α and interleukin (IL)-1β, may be novel targets for the treatment of acute pancreatitis. The aim of this study was to investigate the therapeutic effects of pomalidomide (or CC-4047), a thalidomide analog and immunomodulatory agent, in acute pancreatitis.     

N-acetylcysteine decreases severity of acute pancreatitis in mice

Oxidative stress plays a major role in the early stage of acute pancreatitis. This study assessed the effects of N-acetylcysteine (NAC), a reduced glutathione (GSH) provider and a direct scavenger of reactive oxygen intermediates, in the course of acute pancreatitis in mice. Acute pancreatitis (AP) was induced by intraperitoneal (i.p.) injections of cerulein. Mice received NAC (1,000 mg/kg, i.p.) every 3 h, starting either 1 h before the first cerulein injection (prophylactic group) or 1 h after the first cerulein injection (therapeutic group), or i.p. saline injections for controls. Severity of AP was evaluated by histology, serum hydrolase levels, and serum and intrapancreatic levels of MCP-1 and interleukin 6 (IL-6). Pancreatic conjugated dienes and intrapancreatic and intrahepatic GSH levels were measured to assess the local and systemic oxidative processes. Acute pancreatitis was also induced with a CDE diet in controls and mice receiving either both NAC ad libidum in drinking water and 1,000 mg/kg i.p. injection once daily. The severity of pulmonary lesions was assessed by arterial blood gases (pO2) and intrapulmonary myeloperoxidase (MPO content) measurements as well as the survival of mice. The severity of cerulein-induced AP was significantly decreased in the prophylactic group compared with the therapeutic and control groups. Prophylactic administration of NAC also decreased the intrapancreatic levels of conjugated dienes compared with controls. The intrapancreatic and systemic release of MCP- 1 and IL-6 was also decreased in the prophylactic group 3 and 6 hours after AP induction. In addition, NAC pretreatment also reduced hepatic IL-6 production at 3 and 6 hours after starting cerulein challenge. In CDE-induced AP, the severity of lung injury (hypoxemia, MPO content) was decreased, and survival was improved by NAC. NAC administered in a prophylactic protocol limits the severity of experimental acute pancreatitis in mice, as well as its systemic complications and related mortality.     

Lipase/amylase ratio in biliary acute pancreatitis and alcoholic acute/acutized chronic pancreatitis

BACKGROUND: Alcoholic or biliary acute pancreatitis may need different therapeutic approaches. AIM: Assessing the validity of lipase/amylase ratio in differentiating biliary from alcoholic acute pancreatitis/acutized chronic pancreatitis. METHODS: Nine male patients (mean age and standard deviation: 39.8 +/- 7.0 years) with alcoholic acute pancreatitis/acutized chronic pancreatitis (group I) and 29 patients, 8 male and 21 female (mean age: 43.6 +/-19.9 years), with biliary acute pancreatitis (group II) were evaluated. Serum lipase and amylase levels were measured in patients with symptoms for no more than 48 hours. The lipase/amylase ratio was calculated based on serum lipase and amylase levels and expressed as multiples of their respective superior reference values. RESULTS: Mean levels of serum lipase (4,814 +/- 3,670 U/L) and amylase (1,282 +/- 777 U/L) in patients of group I were comparable to group II (2,697 +/- 2,391 and 1,878 +/- 1,319 U/L, respectively), but the mean lipase/amylase ratio was significantly higher in group I (4.4 +/- 3.6) than in group II (2.2 +/- 2.2). Lipase/amylase ratio >3 occurred at significantly higher proportions in patients of group I (66.7%) than of group II (24.1%), differentiating the two groups with sensitivity of 67% and specificity of 76%. CONCLUSIONS: 1) Amylase and lipase serum levels did not differ in the two groups evaluated; 2) the lipase/amylase ratio >3 was more often seen in alcoholic acute pancreatitis/acutized chronic pancreatitis than biliary acute pancreatitis, and it may be useful in differentiating these two causes of pancreatitis.     

Enhanced survival and mucosal repair after dextran sodium sulfate-induced colitis in transgenic mice that overexpress growth hormone

BACKGROUND & AIMS: Growth hormone (GH) is used as therapy for inflammatory bowel disease (IBD), but the specific effects on intestine are unknown. Transgenic mice overexpressing GH (MT1-bGH-TG) were used to test whether increased plasma GH levels alter inflammation or crypt damage during dextran sodium sulfate (DSS)-induced colitis. METHODS: MT1-bGH-TG and wild-type (WT) littermates were given 3% DSS for 5 days followed by up to 10 days of recovery. Colitis and epithelial cell proliferation were evaluated histologically. Plasma insulin-like growth factor (IGF)-I and colonic IGF-I, interleukin (IL)-1beta, and intestinal trefoil factor (ITF) messenger RNAs (mRNAs) were measured. RESULTS: DSS induced similar disease onset in MT1-bGH-TG and WT. More MT1-bGH-TG survived than WT. By recovery day 7, MT1-bGH-TG had less inflammation and crypt damage, elevated plasma IGF-I, and increased colonic ITF expression relative to WT. Colonic IL-1beta was elevated in DSS-treated MT1-bGH-TG and WT, but IL-1beta mRNA abundance correlated with disease only in WT. MT1-bGH-TG showed earlier increases in epithelial cell proliferation than WT during recovery but only WT showed atypical repair. CONCLUSIONS: GH does not alter susceptibility to acute DSS-induced colitis but enhances survival, remission of inflammation, and mucosal repair during recovery. GH therapy may be beneficial during active IBD by improving mucosal repair.     

Antibody-mediated blockade of IL-15 reverses the autoimmune intestinal damage in transgenic mice that overexpress IL-15 in enterocytes

Celiac disease (CD) is an autoimmune inflammatory disease with a relatively high prevalence especially in the western hemisphere. A strong genetic component is involved in the pathogenesis of CD with virtually all individuals that develop the disease carrying HLA-DQ alleles that encode specific HLA-DQ2 or HLA-DQ8 heterodimers. Consumption of cereals rich in gluten triggers a chronic intestinal inflammation in genetically susceptible individuals leading to the development of CD. Emerging evidence has implicated a central role for IL-15 in the orchestration and perpetuation of inflammation and tissue destruction in CD. Therefore, IL-15 represents an attractive target for development of new therapies for CD. Transgenic mice that express human IL-15 specifically in enterocytes (T3^b-hIL-15 Tg mice) develop villous atrophy and severe duodeno-jejunal inflammation with massive accumulation of NK-like CD8⁺ lymphocytes in the affected mucosa. We used these mice to demonstrate that blockade of IL-15 signaling with an antibody (TM-β1) that binds to murine IL-2/IL-15Rbeta (CD122) leads to a reversal of the autoimmune intestinal damage. The present study, along with work of others, provides the rationale to explore IL-15 blockade as a test of the hypothesis that uncontrolled expression of IL-15 is critical in the pathogenesis and maintenance of refractory CD.     

p38 MAPK inhibition alleviates experimental acute pancreatitis in mice

BACKGROUND: The mitogen-activated protein kinases (MAPKs) signaling pathway is involved in inflammatory process. However,the mechanism is not clear. The present study was to investigate the role of p38 MAPK in acute pancreatitis in mice.METHODS: Mice were divided into 4 groups: saline control; acute pancreatitis induced with repeated injections of cerulein; control plus p38 MAPK inhibitor SB203580; and acute pancreatitis plus SB203580. The pancreatic histology, pancreatic enzymes, cytokines, myeloperoxidase activity, p38 MAPK and heat shock protein (HSP) 60 and 70 were evaluated.RESULTS: Repeated injections of cerulein resulted in acute pancreatitis in mice, accompanying with the activation of p38 MAPK and overexpression of HSP60 and HSP70 in the pancreatic tissues. Treatment with SB203580 significantly inhibited the activation of p38 MAPK, and furthermore, inhibited the expression of HSP60 and HSP70 in the pancreas, the inflammatory cytokines in the serum, and myeloperoxidase activity in the lung.CONCLUSION: The p38 MAPK signaling pathway is involved in the regulation of inflammatory response and the expression of HSP60 and HSP70 in acute pancreatitis.     

Diabetes aggravates acute pancreatitis and inhibits pancreas regeneration in mice

Aims/hypothesis  

It is well established that acute pancreatitis often causes diabetes and that a high blood glucose level associated with pancreatitis is a marker of poor prognosis. The aim of this study was to evaluate if diabetes merely reflects the severity of pancreatitis or whether it can also aggravate the progression of this disease in a vicious circle.     

髓样细胞表达的激发受体-1在急性坏死性胰腺炎小鼠中的表达

目的 检测急性坏死性胰腺炎(ANP)小鼠外周血及胰腺组织中髓样细胞表达的激发受体-1(TREM-1)的表达,探讨其在ANP发生、发展中的作用.方法 50只雄性昆明小鼠按随机表法分为对照组,ANP 24、48、72、96 h组.以腹腔注射20%L-精氨酸4 mg/g体重、间隔1 h重复一次的方法制备ANP模型.对照组腹腔注射等容积生理盐水.取血检测淀粉酶、肌酐和谷丙转氨酶含量;取胰腺组织行病理学检查并评分;采用实时定量PCR法检测外周血白细胞TREM-1 mRNA的表达;免疫组化法检测胰腺组织TREM-1蛋白表达.结果 ANP 24 h组小鼠血清淀粉酶、肌酐、谷丙转氨酶水平为(9439±1273)U/L、(84.8±75.9)μmol/L、(158.1±122.1)U/L,均较对照组的(2412±297)U/L、(29.2±19.1)μmol/L、(41.4±7.9)U/L显著升高.ANP组胰腺组织的病理评分随着时间推移而增加.ANP 24、48、72、96 h组的TREM-1 mRNA相对表达量分别为15.55、30.36、15.77、28.32,ANP 48 h组的表达量显著高于其他时间点组(P值均<0.01),而胰腺组织TREM-1蛋白表达随胰腺炎的病程进展无显著变化.结论 TREM-1可能还通过促发其他炎症因子参与ANP的进展过程.