Pancreatic stellate cell: Pandora's box for pancreatic disease biology

Pancreatic stellate cells(PSCs) were identified in the early 1980 s, but received much attention after 1998 when the methods to isolate and culture them from murine and human sources were developed. PSCs contribute to a small proportion of all pancreatic cells under physiological condition, but are essential for maintaining the normal pancreatic architecture. Quiescent PSCs are characterized by the presence of vitamin A laden lipid droplets. Upon PSC activation, these perinuclear lipid droplets disappear from the cytosol, attain a myofibroblast like phenotype and expresses the activation marker, alpha smooth muscle actin. PSCs maintain their activated phenotype via an autocrine loop involving different cytokines and contribute to progressive fibrosis in chronic pancreatitis(CP) and pancreatic ductal adenocarcinoma(PDAC). Several pathways(e.g., JAK-STAT, Smad, Wnt signaling, Hedgehog etc.), transcription factors and mi RNAs have been implicated in the inflammatory and profibrogenic function of PSCs. The role of PSCs goes much beyond fibrosis/desmoplasia in PDAC. It is now shown that PSCs are involved in significant crosstalk between the pancreatic cancer cells and the cancer stroma. These interactions result in tumour progression, metastasis, tumour hypoxia, immune evasion and drug resistance. This is the rationale for therapeutic preclinical and clinical trials that have targeted PSCs and the cancer stroma.

Extracorporeal shock wave lithotripsy for pancreatic and large common bile duct stones

Extraction of large pancreatic and common bile duct(CBD)calculi has always challenged the therapeutic endoscopist.Extracorporeal shockwave lithotripsy(ESWL)is an excellent tool for patients with large pancreatic and CBD calculi that are not amenable to routine endotherapy.Pancreatic calculi in the head and body are targeted by ESWL,with an aim to fragment them to<3 mm diameter so that they can be extracted by subsequent endoscopic retrograde cholangio-pancreatography(ERCP).In our experience,complete clearance of the pancreatic duct was achieved in 76% and partial clearance in 17%of 1006 patients.Short-term pain relief with reduction in the number of analgesics ingested was seen in 84%of these patients.For large CBD calculi,a nasobiliary tube is placed to help target the calculi,as well as bathe the calculi in salinea simple maneuver which helps to facilitate fragmenta-tion.The aim is to fragment calculi to<5 mm size and clear the same during ERCP.Complete clearance of the CBD was achieved in 84.4%of and partial clearance in 12.3%of 283 patients.More than 90%of the patients with pancreatic and biliary calculi needed three or fewer sessions of ESWL with 5000 shocks being de-livered at each session.The use of epidural anesthesia helped in reducing patient movement.This,together with the better focus achieved with newer third-gen-eration lithotripters,prevents collateral tissue damage and minimizes the complications.Complications in our experience with nearly 1300 patients were minimal,and no extension of hospital stay was required.Similar rates of clearance of pancreatic and biliary calculi with minimal adverse effects have been reported from the centers where ESWL is performed regularly.In view of its high efficiency,non-invasive nature and low complication rates,ESWL can be offered as the first-line therapy for selected patients with large pancreatic and CBD calculi.

Autologous mobilized peripheral blood CD34^+ cell infusion in non-viral decompensated liver cirrhosis

AIM: To study the effect of mobilized peripheral blood autologous CD34 positive(CD34+) cell infusion in patients with non-viral decompensated cirrhosis.METHODS: Cirrhotic patients of non-viral etiology were divided into 2 groups based on their willingness to be listed for deceased donor liver transplant(DDLT)(control, n = 23) or to receive autologous CD34+ cell infusion through the hepatic artery(study group, n= 22). Patients in the study group were admitted to hospital and received granulocyte colony stimulating factor injections 520 μg/d for 3 consecutive days to mobilize CD34+ cells from the bone marrow. On day 4,leukapheresis was done and CD34+ cells were isolated using CliniMAC magnetic cell sorter. The isolated CD34+ cells were infused into the hepatic artery under radiological guidance. The patients were discharged within 48 h. The control group received standard of care treatment for liver cirrhosis and were worked up for DDLT as per protocol of the institute. Both groups were followed up every week for 4 wk and then every month for 3 mo.RESULTS: In the control and the study group, the cause of cirrhosis was cryptogenic in 18(78.2%) and16(72.72%) and alcohol related in 5(21.7%) and6(27.27%), respectively. The mean day 3 cell count(cells/μL) was 27.00 ± 20.43 with a viability of 81.84± 11.99%. and purity of 80%-90%. Primary end point analysis revealed that at 4 wk, the mean serum albumin in the study group increased significantly(2.83± 0.36 vs 2.43 ± 0.42, P = 0.001) when compared with controls. This improvement in albumin was,however, not sustained at 3 mo. However, at the end of3 mo there was a statistically significant improvement in serum creatinine in the study group(0.96 ± 0.33 vs 1.42 ± 0.70, P = 0.01) which translated into a significant improvement in the Model for End-Stage Liver Disease score(15.75 ± 5.13 vs 19.94 ± 6.68,P = 0.04). On statistical analysis of secondary end points, the transplant free survival at the end of 1 mo and 3 mo did not show any significant difference(P =0.60) when compared to the control group. There was no improvement in aspartate transaminase, alanine transaminase, and bilirubin at any point in the study population. There was no mortality benefit in the study group. The procedure was safe with no procedural or treatment related complications.CONCLUSION: Autologous CD 34+ cell infusion is safe and effectively improves liver function in the short term and may serve as a bridge to liver transplantation.

Endoscopic management of pancreatic fluid collectionsrevisited

The development of pancreatic fluid collections(PFC) is one of the most common complications of acute severe pancreatitis. Most of the acute pancreatic fluid collections resolve and do not require endoscopic drainage. However, a substantial proportion of acute necrotic collections get walled off and may require drainage. Endoscopic drainage of PFC is now the preferred mode of drainage due to reduced morbidity and mortality as compared to surgical or percutaneous drainage. With the introduction of new metal stents, the efficiency of endoscopic drainage has improved and the task of direct endoscopic necrosectomy has be-come easier. The requirement of re-intervention is less with new metal stents as compared to plastic stents. However, endoscopic drainage is not free of adverse events. Severe complications including bleeding, perforation, sepsis and embolism have been described with endoscopic approach to PFC. Therefore, the endoscopic management of PFC is a multidisciplinary affair and involves interventional radiologists as well as GI surgeons to deal with unplanned adverse events and failures. In this review we discuss the recent advances and controversies in the endoscopic management of PFC.

Efficacy of low dose peginterferon alpha-2b with ribavirin on chronic hepatitis C

AIM: To assess the effi cacy of peginterferon alpha 2b at doses of 50 μg weekly and 80 μg weekly (based on body weight) plus ribavirin in HCV genotype 2 and genotype 3 chronic hepatitis C patients. METHODS: During the study period of Jan 2002 to Dec 2003, all patients diagnosed as chronic hepatitis C or HCV related compensated cirrhosis were treated with peginterferon alpha 2b 50 μg S/C weekly (body weight < 60 kg) or 80 μg S/C weekly (body weight > 60 kg) plus ribavirin 800 mg/d for 24 wk. RESULTS: Overall 28 patients, 14 patients in each group (based on body weight) were treated during the period. Out of 28 patients, 75% were genotype 3, 18% were genotype 2 and 7% were genotype 1. The mean dose of peginterferon alpha 2b was 0.91 μg/kg in group 1 and 1.23 μg/kg in group 2 respectively. The end of treatment and sustained virologic response rates were 82% and 78% respectively. Serious adverse effects were seen in 3.5% patients. CONCLUSION: Low dose peginterferon alpha 2b in combination with ribavirin for 24 wk is effective in HCV genotype 2 and 3 chronic hepatitis C patients.

Thinking outside the liver: Induced pluripotent stem cells for hepatic applications

The discovery of induced pluripotent stem cells (iPSCs) unraveled a mystery in stem cell research, after identification of four re-programming factors for generating pluripotent stem cells without the need of embryos. This breakthrough in generating iPSCs from somatic cells has overcome the ethical issues and immune rejection involved in the use of human embryonic stem cells. Hence, iPSCs form a great potential source for developing disease models, drug toxicity screening and cell-based therapies. These cells have the potential to differentiate into desired cell types, including hepatocytes, under in vitro as well as under in vivo conditions given the proper microenvironment. iPSC-derived hepatocytes could be useful as an unlimited source, which can be utilized in disease modeling, drug toxicity testing and producing autologous cell therapies that would avoid immune rejection and enable correction of gene defects prior to cell transplantation. In this review, we discuss the induction methods, role of reprogramming factors, and characterization of iPSCs, along with hepatocyte differentiation from iPSCs and potential applications. Further, we discuss the location and detection of liver stem cells and their role in liver regeneration. Although tumor formation and genetic mutations are a cause of concern, iPSCs still form a promising source for clinical applications.

Genetics of acute and chronic pancreatitis: An update

Progress made in identifying the genetic susceptibility underlying acute and chronic pancreatitis has benefitted the clinicians in understanding the pathogenesis of the disease in a better way. The identification of mutations in cationic trypsinogen gene(PRSS1 gene; functional gain mutations) and serine protease inhibitor kazal type 1(SPINK1 gene; functional loss mutations) and other potential susceptibility factors in genes that play an important role in the pancreatic secretory functions or response to inflammation during pancreatic injury has changed the current concepts and understanding of a complex multifactorial disease like pancreatitis. An indi-vidual's susceptibility to the disease is governed by ge-netic factors in combination with environmental factors. Candidate gene and genetic linkage studies have iden-tified polymorphisms in cationic trypsinogen(PRSS1), SPINK1, cystic fibrosis trans-membrane conductance regulator(CFTR), Chymotrypsinogen C(CTRC), Ca-thepsin B(CTSB) and calcium sensing receptor(CASR). Individuals with polymorphisms in the mentioned genes and other as yet identified genes are at an enhanced risk for the disease. Recently, polymorphisms in genes other than those involved in "intra-pancreatic trypsin regulatory mechanism" namely Claudin-2(CLDN2) andCarboxypeptidase A1(CPA1) gene have also been iden-tified for their association with pancreatitis. With ever growing number of studies trying to identify the genetic susceptibility in the form of single nucleotide polymor-phisms, this review is an attempt to compile the avail-able information on the topic.

Genetic mechanisms underlying the pathogenesis of tropical calcific pancreatitis

Chronic pancreatitis is known to be a heterogeneous disease with varied etiologies.Tropical calcific pancreatitis(TCP) is a severe form of chronic pancreatitis unique to developing countries.With growing evidence of genetic factors contributing to the pathogenesis of TCP,this review is aimed at compiling the available information in this field.We also propose a two hit model to explain the sequence of events in the pathogenesis of TCP.

Endotherapy in chronic pancreatitis

Chronic pancreatitis(CP)is a progressive disease with irreversible changes in the pancreas.Patients commonly present with pain and with exocrine or endocrine insufficiency.All therapeutic efforts in CP are directed towards relief of pain as well as the management of associated complications.Endoscopic therapy offers many advantages in patients with CP who present with ductal calculi,strictures,ductal leaks,pseudocyst or associated biliary strictures.Endotherapy offers a high rate of success with low morbidity in properly selected patients.The procedure can be repeated and failed endotherapy is not a hindrance to subsequent surgery.Endoscopic pancreatic sphincterotomy is helpful in patients with CP with minimal ductal changes while minor papilla sphincterotomy provides relief in patients with pancreas divisum and chronic pancreatitis.Extracorporeal shock wave lithotripsy is the standard of care in patients with large pancreatic ductal calculi.Long term follow up has shown pain relief in over 60%of patients.A transpapillary stent placed across the disruption provides relief in over 90%of patients with ductal leaks.Pancreatic ductal strictures are managed by single large bore stents.Multiple stents are placed for refractorystrictures.CP associated benign biliary strictures(BBS)are best treated with multiple plastic stents,as the response to a single plastic stent is poor.Covered self expanding metal stents are increasingly being used in the management of BBS though further long term studies are needed.Pseudocysts are best drained endoscopically with a success rate of 80%-95%at most centers.Endosonography(EUS)has added to the therapeutic armamentarium in the management of patients with CP.Drainage of pseudcysts,cannulation of inaccessible pancreatic ducts and celiac ganglion block in patients with intractable pain are all performed using EUS.Endotherapy should be offered as the first line of therapy in properly selected patients with CP who have failed to respond to medical therapy and require intervention.

Pain in chronic pancreatitis: Managing beyond the pancreatic duct

Chronic pancreatitis(CP)continues to be a clinical challenge.Persistent or recurrent abdominal pain is the most compelling symptom that drives patients to seek medical care.Unfortunately,in spite of using several treatment approaches in the clinical setting,there is no single specific treatment modality that can be earmarked as a cure for this disease.Traditionally,ductal hypertension has been associated with causation of pain in CP;and patients are often subjected to endotherapy and surgery with a goal to decompress the pancreatic duct.Recent studies on humans(clinical and laboratory based)and experimental models have put forward several mechanisms,including neuroimmune alterations,which could be responsible for pain.This might explain the partial or no response to single modality treatment in a significant proportion of patients.The current review discusses the recent concepts of pain generation in CP and evidence based therapeutic approaches(other than ductal decompression)to handle persistent or recurrent pain.We focus primarily on parenchymal and neural components;and discuss the role of antioxidants and the existing controversies,drugs that interfere with neural transmission,pancreatic enzyme supplementation,celiac neurolysis,and pancreatic resection procedures.The review concludes with the treatment approach that we follow at our institute.

Identification of circulating CD90^+ CD73^+ cells in cirrhosis of liver

AIM:To identify circulating CD90 + CD73 + CD45 cells and evaluate their in vitro proliferating abilities.METHODS:Patients with cirrhosis(n=43),and healthy volunteers(n=40)were recruited to the study.Mononuclear cells were isolated and cultured from the peripheral blood of controls and cirrhosis patients.Fibroblast-like cells that appeared in cultures were analyzed for morphological features,enumerated by flow cytometry and confirmed by immunocytochemistry(ICC).Colony forming efficiency(CFE)of these cells was assessed and expressed as a percentage.RESULTS:In comparison to healthy volunteers,cells obtained from cirrhotic patients showed a significantincrease(P<0.001)in the percentage of CD90+CD73+ CD45 cells in culture.Cultured cells also showed 10 fold increases in CFE.Flow cytometry and ICC confirmed that the proliferating cells expressed CD90 + CD73 + in the cultures from cirrhosis patients.CONCLUSION:These results indicate the presence of circulating CD90 + CD73 + CD45 cells in patients with liver cirrhosis that have the potential to proliferate at a higher rate.

role of the normal gut microbiota

Relation between the gut microbiota and human health is being increasingly recognised. It is now well established that a healthy gut flora is largely responsible for overall health of the host. The normal human gut microbiota comprises of two major phyla, namely Bacteroidetes and Firmicutes. Though the gut microbiota in an infant appears haphazard, it starts resembling the adult flora by the age of 3 years. Nevertheless, there exist temporal and spatial variations in the microbial distribution from esophagus to the rectum all along the individual's life span. Developments in genome sequencing technologies and bioinformatics have now enabled scientists to study these microorganisms and their function and microbehost interactions in an elaborate manner both in health and disease. The normal gut microbiota imparts specific function in host nutrient metabolism, xenobiotic and drug metabolism, maintenance of structural integrity of the gut mucosal barrier, immunomodulation, and protection against pathogens. Several factors play a role in shaping the normal gut microbiota. They include(1) the mode of delivery(vaginal or caesarean);(2) diet during infancy(breast milk or formula feeds) and adulthood(vegan based or meat based); and(3) use of antibiotics or antibiotic like molecules that are derived from the environment or the gut commensal community. A major concern of antibiotic use is the long-term alteration of the normal healthy gut microbiota and horizontal transfer of resistance genes that could result in reservoir of organisms with a multidrug resistant gene pool.

Comprehensive screening for reg1α gene rules out association with tropical calcific pancreatitis

AIM: To investigate the allelic and haplotypic association of reg1α gene with tropical calcific pancreatitis (TCP). Since TCP is known to have a variable genetic basis, we investigated the interaction between mutations in the susceptibility genes, SPINK1 and CTSB with reg1α polymorphisms. METHODS: We analyzed the polymorphisms in the reg1α gene by sequencing the gene including its promoter region in 195 TCP patients and 150 ethnically matched controls, compared their allele and haplotype frequencies, and their association with the pathogenesis and pancreaticolithiasis in TCP and fibro-calculous pancreatic diabetes. RESULTS: We found 8 reported and 2 novel polymo-rphisms including an insertion-deletion polymorphism in the promoter region of reg1α. None of the 5' UTR variants altered any known transcription factor binding sites, neither did any show a statistically significant association with TCP. No association with any reg1α variants was observed on dichotomization of patients based on their N34S SPINK1 or L26V CTSB status. CONCLUSION: Polymorphisms in reg1α gene, including the regulatory variants singly or in combination with the known mutations in SPINK1 and/or CTSB genes, are not associated with tropical calcific pancreatitis.

Drugs for Non-alcoholic Steatohepatitis (NASH): Quest for the Holy Grail

Nonalcoholic fatty liver disease (NAFLD) is a global epidemic that is likely to become the most common cause of chronic liver disease in the next decade, worldwide. Though numerous drugs have been evaluated in clinical trials, most of them have returned inconclusive results and shown poorly-tolerated adverse effects. None of the drugs have been approved by the Food and Drug Administration for treating biopsy-proven non-alcoholic steatohepatitis (NASH). Vitamin E and pioglitazone have been extensively used in treatment of biopsy-proven nondiabetic NASH patients. Although some amelioration of inflammation has been seen, these drugs did not improve the fibrosis component of NASH. Therefore, dietary modification and weight reduction have remained the cornerstone of treatment of NASH;moreover, they have shown to improve histological activity as well as fibrosis. The search for an ideal drug or ‘Holy Grail’ within this landscape of possible agents continues, as weight reduction is achieved only in less than 10% of patients. In this current review, we summarize the drugs for NASH which are under investigation, and we provide a critical analysis of their up-to-date results and outcomes.

Pathophysiology and Prevention of Paracentesis-induced Circulatory Dysfunction:A Concise Review

Annually,10%of cirrhotic patients with ascites develop refractory ascites for which large-volume paracentesis(LVP)is a frequently used therapeutic procedure.LVP,although a safe method,is associated with circulatory dysfunction in a significant percentage of patients,which is termed para-centesis-induced circulatory dysfunction(PICD).PICD results in faster reaccumulation of ascites,hyponatremia,renal impairment,and shorter survival.PICD is diagnosed through laboratory results,with increases of>50%of baseline plasma renin activity to a value≥4 ng/mL/h on the fifth to sixth day after paracentesis.In this review,we discuss the pathophysi-ology and prevention of PICD.