Emerging roles of connexin hemichannels in gastrointestinal and liver pathophysiology

Connexin hemichannels have long been considered as mere structural precursors for gap junctions. In the last decade, it has become clear that they also act as individual channels, connecting the intracellular compartment and the extracellular environment. Impairement of connexin hemichannel functionality may result in disturbance of homeostasis, as exemplified in the current paper for the intestine and the liver. Research in this field still has a number of shortcomings, of which some are also discussed here.

Syphilitic proctitis mimicking rectal cancer: A case report

Syphilitic proctitis is a rare disease. It usually presents as proctitis, ulcer and neoplasm but lacks pathognomonic clinical symptoms. It is, therefore, difficult to diagnose and is occasionally treated inappropriately. We report the case of a 51-year-old man who had a hard, ulcerated mass, which occupied the circumference of the rectal wall and which mimicked a rectal tumor. Fortunately, positive finding from routine toluidine red unheated serum test and treponema pallidum particle agglutination tests made us reevaluate the patient and led us to suspect syphilitic proctitis. This diagnosis was finally confirmed after successful penicillin G benzathine therapy which made surgery unnecessary.

Colo-renal fistula: An unusual cause of hematochezia

A 76 year old woman with bloody stools and symptomatic anemia presented to the Emergency Department approximately 2 wk after computed tomography (CT)-guided cryoablation to a 4.5 cm renal cell carcinoma on her left posterior kidney. The patient was initially prepped for a colonoscopy to view possible causes of lower gastrointestinal bleeding. However, the patient had a CT with PO contrast that revealed a variation of a renoalimentary fistula. The patient was subsequently brought to the operating room, and it was discovered that a colo-renal fistula had formed, with transmural perforation of the posterior descending colon. A left nephrectomy, left colectomy with colostomy and Hartmann’s pouch was performed.

Isolated splenic tuberculosis: A case report

We present a rare case of a 36 year old man who presented with recurrent fever but no other symptoms. Laboratory data provided no specific information for diagnosis. Abdominal ultrasonography revealed splenomegaly with multiple small hypoechoic lesions within the spleen. Computed tomography of abdomen showed a hypodense diffuse lesion. A diagnosis of isolated splenic tuberculosis was confirmed after a splenic puncture and histopathological examination.

Metabolic syndrome and gastro-esophageal reflux: A link towards a growing interest in developed countries

The aim of this Editorial is to describe the growing possibility of a link between gastro-esophageal reflux disease (GERD) and metabolic syndrome on the light of recent epidemiological and pathophysiological evidence. The state of the art of GERD is described, based on recent definitions, pathophysiological evidence, epidemiology in developed countries, clinical subtypes together with a diagnostic approach specifically focussed on the appropriateness of endoscopy. Metabolic syndrome is accurately defined and the pivotal role of insulin resistance is emphasized. The strong relationship between GERD and metabolic syndrome has been pathophysiologically analyzed, taking into account the role of obesity, mechanical factors and metabolic changes. Data collected by our group regarding eating habits and GERD are briefly summarized at the end of a pathophysiological analysis. The literature on the subject strongly supports the possibility that lifestyle and eating habits may be involved in both GERD and metabolic syndrome in developed countries.

Low-grade inflammation plays a pivotal role in gastrointestinal dysfunction in irritable bowel syndrome

The pathogenesis of irritable bowel syndrome (IBS) is considered to be multifactorial and includes psychosocial factors, visceral hypersensitivity, infection, microbiota and immune activation. It is becoming increasingly clear that low-grade inflammation is present in IBS patients and a number of biomarkers have emerged. This review describes the evidence for low-grade inflammation in IBS and explores its mechanism with particular focus on gastrointestinal motor dysfunction. Understanding of the immunological basis of the altered gastrointestinal motor function in IBS may lead to new therapeutic strategies for IBS.

Aberrant DNA methylation profile in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a notoriously lethal epithelial cancer originating from the biliary system. As radical resection offers a poor success rate and limited effective adjuvant modalities exist in its advanced stage, the disease leads to a fairly poor prognosis. As the incidence of CCA is increasing, although the mortality rate remains stable, and few other definite etiologies have yet to be established, renewing our knowledge of its fundamental carcinogenesis is advisable. The latest advances in molecular carcinogenesis have highlighted the roles of epigenetic perturbations and cancer-related inflammation in CCA. This review focuses on the reciprocal effects between aberrant DNA methylation and inflammatory microenvironment in CCA.

Pancreatic secretory trypsin inhibitor: More than a trypsin inhibitor

Kazal-type serine protease inhibitor is one of the most important and widely distributed protease inhibitor families. Pancreatic secretory trypsin inhibitor (PSTI), also known as serine protease inhibitor Kazal type I(SPINK1), binds rapidly to trypsin, inhibits its activity and is likely to protect the pancreas from prematurely activated trypsinogen. Therefore, it is an important factor in the onset of pancreatitis. Recent studies found that PSTI/SPINK1 is also involved in self-regulation of acinar cell phagocytosis, proliferation and growth of a variety of cell lines. In addition, it takes part in the response to inflammatory factor or injury and is highly related to adult type II citrullinemia.

Paediatric cholestatic liver disease: Diagnosis, assessment of disease progression and mechanisms of fibrogenesis

Cholestatic liver disease causes significant morbidity and mortality in children. The diagnosis and management of these diseases can be complicated by an inability to detect early stages of fibrosis and a lack of adequate interventional therapy. There is no single gold standard test that accurately reflects the presence of liver disease, or that can be used to monitor fibrosis progression, particularly in conditions such as cystic fibrosis. This has lead to controversy over how suspected liver disease in children is detected and diagnosed. This review discusses the challenges in using commonly available methods to diagnose hepatic fibrosis and monitor disease progression in children with cholestatic liver disease. In addition, the review examines the mechanisms hypothesised to be involved in the development of hepatic fibrogenesis in paediatric cholestatic liver injury which may ultimately aid in identifying new modalities to assist in both disease detection and therapeutic intervention.

Involvement of cholangiocyte proliferation in biliary fibrosis

Cholangiocytes are the epithelial cells that line the biliary tree. In the adult liver, they are a mitotically dormant cell population, unless ductular reaction is triggered by injury. The ability of cholangiocytes to proliferate is important in many different human pathological liver conditions that target this cell type, which are termed cholangiopathies (i.e. primary biliary cirrhosis, primary sclerosing cholangitis and biliary atresia). In our article, we provide background information on the morphological and functional heterogeneity of cholangiocytes, summarize what is currently known about their proliferative processes, and briefly describe the diseases that target these cells. In addition, we address recent findings that suggest cholangiocyte involvement in epithelial-to-mesenchymal transformation and liver fibrosis, and propose directions for future studies.

Biogenic amines serotonin and dopamine regulate cholangiocyte hyperplastic and neoplastic growth

Biogenic amines, such as serotonin and dopamine, regulate a multitude of cellular responses. A great deal of effort has been invested into understanding the effects of these molecules and their corresponding receptor systems on cholangiocyte and cholangiocarcinoma secretion, apoptosis and growth. This review summarizes the results of these efforts and highlights the importance of these regulatory molecules on the physiology and pathophysiology of cholangiocytes. Specifically we have focused on the recent findings into the effects of serotonin and dopamine on cholangiocyte hyperplasia and neoplastic growth.

Histamine regulation of hyperplastic and neoplastic cell growth in cholangiocytes

Histamine has long been known to be involved in inflammatory events. The discovery of antihistamines dates back to the first half of the 20^th century when a Swiss-Italian pharmacologist, Daniel Bovet began his work. In 1957 he was awarded a Nobel Prize for his production of antihistamines for allergy relief. Since that time, histamine has been found to play a role in other events besides allergic reaction. Possibly unbelievable to Bovet and his peers, histamine has now been marked as playing a role in liver pathologies including hepatobiliary diseases.

Role of sex hormones in the modulation of cholangiocyte function

Over the last years, cholangiocytes, the cells that line the biliary tree, have been considered an important object of study for their biological properties which involves bile formation, proliferation, injury repair, fibrosis and angiogenesis. Cholangiocyte proliferation occurs in all pathologic conditions of liver injury where it is associated with inflammation and regeneration. During these processes, biliary cells start to secrete different cytokines, growth factors, neuropeptides and hormones which represent potential mechanisms for cross talk with other liver cells. Several studies suggest that hormones, and in particular, sex hormones, play a fundamental role in the modulation of the growth of this compartment in the injured liver which functionally conditions the progression of liver disease. Understanding the mechanisms of action and the intracellular pathways of these compounds on cholangiocyte pathophysiology will provide new potential strategies for the management of chronic liver diseases. The purpose of this review is to summarize the recent findings on the role of sex hormones in cholangiocyte proliferation and biology.

Integrin α6β4 in colorectal cancer

The ability of cells to interact with extracellular matrix macromolecules is at the forefront of the regulation of cell phenotype and organization. Indeed most if not all cells bear specific cell surface receptors for these molecules, namely the integrins, which are specific for the ligation of various macromolecules such as the laminins, fibronectins and tenascins. It is now well established that integrins can regulate a variety of biological activities, most notably cell cycle and tissue-specific gene expression. In the intestine, several observations suggest functional roles for cell-matrix interactions in the regulation of epithelial cell functions. This article focuses on integrin α6β4 as a paradigm to illustrate the importance as well as the complexity of integrins in the mediation of cell-matrix interactions. Indeed, α6β4 has been well-characterized for its involvement as a link between the cytoskeleton and extracellular matrix molecules as well as in the activation of a variety of intracellular signalization processes in cooperation with growth factor receptors. Furthermore, recent studies show that distinct forms of α6 and β4 subunits are expressed in the human intestine and, more importantly, recent work provides experimental evidence that various forms of α6β4 can differentially regulate intestinal epithelial cell functions under both normal and pathological conditions. For instance, it has been discovered that colorectal cancer cells express a hybrid form of α6β4 that is never seen in normal cells. Although further work is needed, integrin α6β4 is emerging as a key regulator of intestinal functions in both intestinal health and disease.

Molecular mechanisms of cholangiocarcinoma

Cholangiocarcinoma (CC), the malignant tumor of the epithelial cells lining the biliary ducts, has undergone a worldwide increase in incidence and mortality. The malignant transformation of the biliary cells originates from a multistep process evolving through chronic inflammation of the biliary tract to CC. In the last few years several advances have been towards understanding and clarifying the molecular mechanisms implicated in the cholangiocarcinogenesis process. However, many pathophysiologic aspects governing the growth of CC are still undefined. The poor prognosis of this tumor underlines the urgent need to codify the underlying molecular mechanisms involved in the growth and progression of CC in order to design effective preventive measures and valid treatment regimens. This review reports on progresses made in the last few years in clarifying the molecular pathways involved in the process of cholangiocarcinogenesis.

What is the purpose of launching World Journal of Gastrointestinal Pathophysiology?

The first issue of World Journal of Gastrointestinal Pathophysiology (WJGP), whose preparatory work was initiated in June, 2009, is published on April 15, 2010. The WJGP Editorial Board has now been established and consists of 154 distinguished experts from 27 countries. Our purpose of launching WJGP is to publish peer-reviewed, high-quality articles via an open-access online publishing model, thereby acting as a platform for communication between peers and the wider public, and maximizing the benefits to editorial board members, authors and readers.