Pancreatic exocrine function during acute exacerbation in WBN/Kob rats with spontaneous chronic pancreatitis

Summary Conclusion Pancreatic exocrine hypofunction is markedly deteriorated during acute exacerbation in a rat model with chronic pancreatitis. Background Little is known about pancreatic exocrine function during acute exacerbation in patients with chronic pancreatitis. We investigated changes in pancreatic exocrine function after inducing acute pancreatitis in an animal model of spontaneous chronic pancreatitis. Methods WBN/Kob rats with chronic pancreatitis sequentially underwent pancreatic exocrine function test 1–6 d after surgical preparation with external pancreatic fistula. We induced acute pancreatitis in another WBN/Kob rats by iv administration of cerulein at a rate of 10 μg/kg/h for 4 h 4 after surgical preparation. Pancreatic exocrine function test was undertaken in a conscious state 1 d before and after cerulein administration. Results In WBN/Kob rats not given cerulein, pancreatic exocrine function remained almost constant, at 3–6 d after surgery. Marked hyperamylasemia developed immediately after cerulein administration. After its administration, the pancreas microscopcially showed prominent intersitial edema and intracellular vacuolization of acinar cells in addition to the finding of pre-existing chronic pancreatitis. Basal and chole-cystokinin-stimulated flow rate, bicarbonate output, and protein output, which were substantially impaired 1 d before cerulein administration, were further reduced 1 d after its administration.     

Mitochondrial dysfunction and apoptosis of acinar cells in chronic pancreatitis

BACKGROUND: The mechanism of acinar cell death in human chronic pancreatitis (CP) remains largely unexplored. Previous studies have demonstrated the role played by apoptosis and necrosis in experimental pancreatitis; however, their relationship with the progression of CP remains unknown. The present study was carried out to elucidate the role and extent of apoptosis in CP tissues with different histopathological scores and to examine the possible apoptotic pathway involved. METHODS: Pancreatic tissues (25 CP patients) that had been histopathologically graded (I-III) and ten normal pancreatic tissue samples were evaluated for apoptosis by DNA fragmentation and an in situ TUNEL assay. The expression of various apoptotic and antiapoptotic markers in the tissues were studied by immunohistochemistry and Western blotting. To elucidate the role of the mitochondria in acinar cell death, the mitochondrial membrane potential (DeltaPsim) and ATP levels were determined by flow cytometry and a luminometer. RESULTS: The presence of DNA fragmentation and apoptotic nuclei in all CP tissues confirmed the presence of apoptosis. The apoptotic index in CP tissue ranged from 0.09% to 0.86% +/- 0.02% and was highest in grade II (0.7 +/- 0.04%) tissues. Differential upregulation of the apoptotic mediators p53, Bax, cytochrome c, and caspase-3 and -9, and downregulation of antiapoptotic Bcl-2, was observed in CP. DeltaPsim on the order of 1.2-to 2.2-fold and ATP depletion in the range of 23%-84% in CP tissues was observed. CONCLUSIONS: Apoptosis plays an important role both in the initial stages and during the progression of CP, as evident in all tissue grades. Increased DeltaPsim, loss of ATP, and activation of caspases suggests the involvement of intrinsic pathways.     

Germline mutations in CFTR and PSTI genes in chronic pancreatitis patients

Mutations in the cationic trypsinogen, cystic fibrosis transmembrane conductance regulator (CFTR) and pancreatic secretory trypsinogen inhibitor (PSTI) genes have recently been associated with chronic pancreatitis. This paper investigates the frequency of CFTR and PSTI gene mutation in patients with idiopathic and alcoholic chronic pancreatitis, the clinical course of patients with these two kinds of disease, and examines the clinical differences between carriers and noncarriers of mutation. In idiopathic pancreatitis a significant increase was found in mutation frequency both in the CFTR gene (13%) and N34S mutation in the PSTI gene (3.9%), as well as an increase in familial disposition to pancreatic disorders. In alcohol-induced pancreatitis an increase in calcification, exocrine insufficiency, and diabetes mellitus was observed. In conclusions, mutations in the genes investigated are involved in causing idiopathic pancreatitis. Such mutations have no connection either with the age at onset or the clinical course of the disease.     

Expression of interleukin 8 (IL-8) and substance P in human chronic pancreatitis

BACKGROUND: Changes in substance P content and a relationship between the degree of perineural inflammation and pain has been demonstrated in chronic pancreatitis. Whether a relationship exists between neural alteration and pancreatic inflammation (neurogenic inflammation) is not known. AIMS: In the present study we evaluated gene expression of preprotachykinin A (PPT-A), the gene encoding substance P, and interleukin 8, a proinflammatory and hyperalgesic mediator whose release is co-regulated by substance P. PATIENTS: Pancreatic tissue specimens obtained from 21 patients (16 male, five female) with chronic pancreatitis and 18 healthy organ donors (nine male, nine female) were analysed. METHODS: Gene expression of PPT-A and interleukin 8 was studied by northern blot analysis. Respective proteins were localised using immunohistochemistry. RESULTS: Northern blot analysis showed that PTT-A mRNA expression levels were present at comparable levels in normal and chronic pancreatitis tissue samples. In contrast, interleukin 8 mRNA was expressed at very low levels in normal controls but was increased 41-fold (p<0. 001) in chronic pancreatitis tissue samples. Using immunohistochemistry, interleukin 8 protein was localised mainly in immune cells often found around enlarged pancreatic nerves. In addition, in chronic pancreatitis, intense interleukin 8 immunostaining was present in metaplastic ductal cells of the atrophic pancreatic parenchyma. In chronic pancreatitis samples there was a positive relationship between interleukin 8 mRNA levels and the presence of ductal metaplasia (r=0.795; p<0.001) and the inflammation score (r=0.713; p<0.001). CONCLUSIONS: Our data indicate that in chronic pancreatitis, the increase in substance P in enlarged pancreatic nerves is not caused by enhanced intrapancreatic PTT-A mRNA expression, suggesting that the location of substance P synthesis is outside of the pancreas. In addition, localisation of interleukin 8 positive immune cells around pancreatic nerves further supports the existence of neuroimmune interactions as a pathophysiological mechanism in chronic pancreatitis.     

Up-regulation of p75 neurotrophin receptor (p75NTR) is associated with apoptosis in chronic pancreatitis

Activation of apoptosis in chronic pancreatitis has been demonstrated. The low-affinity neurotrophin receptor p75 (p75NTR) mediates apoptosis in many cell types in vivo and in vitro. The aim of this study was to examine whether p75NTR is involved in the apoptotic process in chronic pancreatitis. The quantity and localization of the receptor was evaluated using northern blot analysis, in situ hybridization, immunohistochemistry, and western blot analysis. Apoptosis was determined by TUNEL assay. By northern blot analysis, p75NTR mRNA levels were increased 40-fold in chronic pancreatitis compared with normal pancreas (P < 0.01). in situ hybridization revealed weak p75NTR mRNA expression in some ductal cells in the normal pancreas. In contrast in chronic pancreatitis moderate p75NTR expression was present in acinar cells next to fibrosis, ductal cells, and cells of ductular structures as well as in some islet cells. Immunostaining of p75NTR in normal pancreas and chronic pancreatitis tissue samples showed a similar intensity and distribution pattern as found by in situ hybridization. Higher p75NTR protein levels could be confirmed by western blot analysis, which revealed an 8.6-fold increase of p75NTR in chronic pancreatitis. TUNEL staining showed, in chronic pancreatitis samples, positivity in some acinar cells next to fibrosis, some ductal cells, and cells of ductular structures. Also some islet cells were positive by TUNEL staining. The presence of p75NTR immunoreactivity was positively correlated (P < 0.05) with the apoptotic index in the exocrine and endocrine pancreas. In conclusion, p75NTR, the low-affinity receptor of neurotrophins which mediates apoptosis, is up-regulated in CP and is involved in the apoptotic process of the exocrine and endocrine pancreas.     

Cholecystokinin antagonist L364,718 induces alterations in acinar cells that prevent improvement of acute pancreatitis induced by obstruction

The aim of this study was to examine the effect of the most potent CCK receptor antagonist, L364,718, on two major factors involved in pancreatitis development: enzyme load and cytosolic calcium (Ca²⁺) levels in acinar cells. L364,718 (0.1 mg/kg/12 hr) was administered from 30 min before inducing acute pancreatitis (AP) by pancreatic duct obstruction (PDO) for 48 hr. The results obtained at different AP stages in PDO rats treated and not treated with the CCK antagonist were compared. Similar increases in the intracellular enzyme content were found at earlier stages of pancreatitis in all PDO rats treated or not treated with L364,718. The CCK antagonist increased cytosolic Ca²⁺ levels up to 6 hr after administration, inducing a higher cytosolic Ca²⁺ overload at the earliest stages of pancreatitis in L364,718-treated PDO rats than in those not treated. This event might justify the higher increases in ascites volume and haematocrit found in PDO rats treated with L364,718 and the exacerbation in pancreatic morphological alterations induced by PDO. The CCK receptor antagonist L364,718 produces alterations in the acinar calcium homeostasis that prevent to reduction in the severity of pancreatitis induced by obstruction.     

Amino acid transporters expression in acinar cells is changed during acute pancreatitis

Pancreatic acinar cells accumulate amino acids against a marked concentration gradient to synthesize digestive enzymes. Thus, the function of acinar cells depends on amino acid uptake mediated by active transport. Despite the importance of this process, pancreatic amino acid transporter expression and cellular localization is still unclear. We screened mouse pancreas for the expression of genes encoding amino acid transporters. We showed that the most highly expressed transporters, namely sodium dependent SNAT3 (Slc38a3) and SNAT5 (Slc38a5) and sodium independent neutral amino acids transporters LAT1 (Slc7a5) and LAT2 (Slc7a8), are expressed in the basolateral membrane of acinar cells. SNAT3 and SNAT5, LAT1 and LAT2 are expressed in acinar cells. Additional evidence that these transporters are expressed in mature acinar cells was gained using acinar cell culture and acute pancreatitis models. In the acute phase of pancreatic injury, when acinar cell loss occurs, and in an acinar cell culture model, which mimics changes occurring during pancreatitis, SNAT3 and SNAT5 are strongly down-regulated. LAT1 and LAT2 were down-regulated only in the in vitro model. At protein level, SNAT3 and SNAT5 expression was also reduced during pancreatitis. Expression of other amino acid transporters was also modified in both models of pancreatitis. The subset of transporters with differential expression patterns during acute pancreatitis might be involved in the injury/regeneration phases. Further expression, localization and functional studies will follow to better understand changes occurring during acute pancreatitis. These findings provide insight into pancreatic amino acid transport in healthy pancreas and during acute pancreatitis injury.     

Arginine induced acute pancreatitis alters the actin cytoskeleton and increases heat shock protein expression in rat pancreatic acinar cells

Arginine induced acute pancreatitis was evaluated as a novel and distinct form of experimental pancreatitis with particular attention to the actin cytoskeleton and expression of heat shock or stress proteins. Arginine induced a dose related necrotising pancreatitis in rats, as shown by histological evaluation, and an increase in serum amylase. Severe pancreatitis induced by 4.5 g/kg arginine was accompanied by dramatic changes in the actin cytoskeleton, as visualised with rhodamine phallodin. Intermediate filaments were also disrupted, as visualised by cytokeratin 8/18 immunocytochemistry. Arginine pancreatitis was accompanied by a stress response with a large increase in the small heat shock protein HSP27, as well as HSP70, peaking at 24 hours and localised to acinar cells. There was a lower increase in HSP60 and HSP90 and no effect on GRP78. HSP27 was also shifted to phosphorylated forms during pancreatitis. A lower dose of arginine (3.0 g/kg) induced less pancreatitis but a larger increase in HSP70 and HSP27 expression and phosphorylation of HSP27. Thus HSP expression can be overwhelmed by severe damage. The present work in conjunction with earlier work on caerulein induced pancreatitis indicates that changes in the actin cytoskeleton are an early component in experimental pancreatitis.     

FoxP3+ regulatory T cells essentially contribute to peripheral CD8+ T-cell tolerance induced by steady-state dendritic cells

Peripheral T-cell tolerance is thought to significantly contribute to the prevention of autoimmunity, and it has been shown that antigen-presenting steady-state dendritic cells efficiently induce peripheral tolerance. We previously showed that dendritic-cell–induced tolerance is a T-cell–intrinsic process that depends on coinhibitory molecules such as programmed death-1. Here we specifically analyze the involvement of FoxP3⁺ regulatory T cells, which are known to be important for maintenance of self-tolerance. We show that antigen presentation by steady-state dendritic cells failed to induce peripheral tolerance in the absence of FoxP3⁺ regulatory T cells but induced protective CD8⁺ T-cell–mediated immunity instead. Regulatory T-cell–depleted mice had massively increased numbers of dendritic cells in lymph nodes. Dendritic cells isolated from mice without regulatory T cells had up-regulated costimulatory molecules and showed stronger T-cell stimulatory capacity ex vivo, suggesting that regulatory T cells contribute to peripheral tolerance by keeping the dendritic cells in an immature state. Using blocking antibodies, we demonstrate that CTLA-4 but not IL-10 is necessary for control of dendritic cells by regulatory T cells.     

No evidence of helicobacter pylori sequences in pancreatic juices of patients affected by chronic pancreatitis

Summary Background: The course of chronic pancreatitis is often unpredictable and many factors are likely to be involved in the progression of the disease. In physiological condition, pancreatic juice exerts significant antibacterial activity, which is impaired in patients with chronic pancreatitis. Aim: Hypothesizing that Helicobacter pylori could, in these conditions, lead to an ascending infection, we aimed to assess the presence of H. pylori sequences in pancreatic juices of patients with chronic pancreatitis. Methods: 40 patients (mean age 52±3 yr) with alcoholic chronic pancreatitis and H. pylori infection were examined. Pancreatic juices were collected during endoscopic retrograde cholangiopancreatography. Using polymerase chain reaction (PCR) with two primers homologous to a portion of urease-C gene, H. pylori DNA was detected. Gastric biopsies, microscopically positive to H. pylori were used as positive controls. Results: All gastric biopsies produced H. pylori-specific DNA products. Conversely, no H. pylori urease-C gene sequences have been detected in any of the pancreatic juices. Conclusion: Our data suggest that the impaired antibacterial activity of pancreatic juices in patients affected by chronic pancreatitis does not have a permissive role for a superimposing H. pylori infection in the pancreas. The possibility that Helicobacter species other than pylori may be involved in a superimposing infection requires further investigation.     

Translational control of protein synthesis in pancreatic acinar cells

Translational control of protein synthesis in the pancreas is important in regulating growth and the synthesis of digestive enzymes. Regulation of translation is primarily directed at the steps in initiation and involves reversible phosphorylation of initiation factors (eIFs) and ribosomal proteins. Major sites include the assembly of the eIF4F mRNA cap binding complex, the activity of guanine nucleotide exchange factor eIF2B, and the activity of ribosomal S6 kinase. All of these involve phosphorylation by different regulatory pathways. Stimulation of protein synthesis in acinar cells is primarily mediated by the phosphatidylinositol 3-kinase-mTOR pathway and involves both release of eIF4E (the limiting component of eIF4F) from its binding protein and phosphorylation of ribosomal S6 protein by S6K. eIF4E is itself phosphorylated by a distinct pathway. Inhibition of acinar protein synthesis can be mediated by inhibition of eIF2B following phosphorylation of eIF2α.     

miR-127-5p靶向IRAK4对肺炎链球菌诱导的肺泡上皮细胞凋亡及炎症因子表达的影响

目的探究miR-127-5p靶向白细胞介素1受体相关激酶4(IRAK4)对肺炎链球菌诱导的肺泡上皮细胞凋亡及炎症因子表达的影响方法首先分为对照组和感染组,感染组用肺炎链球菌感染A549细胞,感染组细胞分别转染miR-127-5p mimic、si-IRAK4及阴性对照质粒,qRT-PCR检测A549细胞中miR-127-5p的表达水平,western blot检测IRAK4、Bax、Bcl-2蛋白水平,流式细胞仪检测细胞凋亡情况,ELISA检测白介素-10(IL-10)、白介素-6(IL-6)水平,双荧光素酶报告基因检测miR-127-5p与IRAK4的靶向关系。结果与对照组比较,肺炎链球菌感染后A549细胞中miR-127-5p、Bcl-2、IL-10水平显著降低,细胞凋亡率、IRAK4、Bax、IL-6水平显著升高(P<0.05);与感染+miR-NC组比较,过表达miR-127-5p后,A549细胞中miR-127-5p、Bcl-2、IL-10水平显著升高,细胞凋亡率、IRAK4、Bax、IL-6显著降低;与感染+si-NC组比较,抑制IRAK4表达后,A549细胞中细胞凋亡率、IRAK4、Bax、IL-6水平显著降低,Bcl-2、IL-10水平显著升高;双荧光素酶报告基因及Western blot结果显示,miR-127-5p可通过与IRAK4特异性结合负向调控IRAK4的表达;与感染+miR-127-5p+pcDNA组比较,感染+miR-127-5p+pcDNA-IRAK4组A549细胞中凋亡率、IRAK4、Bax、IL-6水平显著升高,Bcl-2、IL-10水平显著降低(P<0.05)。结论miR-127-5p靶向IRAK4调控肺炎链球菌诱导的肺泡上皮细胞凋亡及炎症因子IL-10、IL-6的表达。     

Y链细胞因子对慢性乙型肝炎患者CD8+T细胞上TIM-3表达的调节

目的 通过检测T细胞免疫球蛋白黏蛋白分子(TIM-3)在慢性乙型肝炎(CHB)患者外周血单个核细胞(PBMC)CD8+T细胞上的表达,探讨共用γ链细胞因子对CHB患者CD8+T细胞上TIM-3表达的影响.方法 选取2014年1-5月在第四军医大学唐都医院传染科就诊的CHB初治患者15例,以及健康体检者8例.抽取两组全血,利用Ficoll密度梯度离心法分离出PBMC.分别给予γ链细胞因子白细胞介素(IL)2、IL-7、IL-15、IL-21和人抗CD3/CD28刺激,未刺激孔作为阴性对照.培养4d后,用单克隆抗体染色,采用流式细胞仪检测CD8+T细胞上TIM-3的表达情况.计量资料比较采用成组t检验.结果 与未刺激组相比,TIM-3在CD8+T细胞上表达如下:人抗CD3/CD28和IL-2、IL-15、IL-7刺激组显著升高,分别为(9.629 ±9.916)％,P=0.000 1;(3.817 ±2.694)％,P=0.000 6;(5.772±4.732)％,P=0.005 4;(3.560 ±2.045)％,P=0.030 2.IL-21刺激组表达虽有所增加,为(2.503 ±2.117)％,但差异无统计学意义,P=0.934 l.结论 人抗CD3/CD28、γ链细胞因子中的IL-2、IL-7和IL-15都能够有效上调TIM-3在CHB患者CD8+T细胞上的表达,提示通过抑制它们不仅可以下调TIM-3的表达,而且可能会增强CHB患者体内CD8+T细胞的杀伤作用.