Gaurav Syal

Advances in cholangiocyte immunobiology

Cholangiocytes, or bile duct epithelia, were once thought to be the simple lining of the conduit system comprising the intra- and extrahepatic bile ducts. Growing experimental evidence demonstrated that cholangiocytes are in fact the first line of defense of the biliary system against foreign substances. Experimental advances in recent years have unveiled previously unknown roles of cholangiocytes in both innate and adaptive immune responses. Cholangiocytes can release inflammatory modulators in a regulated fashion. Moreover, they express specialized pattern-recognizing molecules that identify microbial components and activate intracellular signaling cascades leading to a variety of downstream responses. The cytokines secreted by cholangiocytes, in conjunction with the adhesion molecules expressed on their surface, play a role in recruitment, localization, and modulation of immune responses in the liver and biliary tract. Cholangiocyte survival and function is further modulated by cytokines and inflammatory mediators secreted by immune cells and cholangiocytes themselves. Because cholangiocytes act as professional APCs via expression of major histocompatibility complex antigens and secrete antimicrobial peptides in bile, their role in response to biliary infection is critical. Finally, because cholangiocytes release mediators critical to myofibroblastic differentiation of portal fibroblasts and hepatic stellate cells, cholangiocytes may be essential in the pathogenesis of biliary cirrhosis.

MCP-1 downregulates MMP-9 export via vesicular redistribution to lysosomes in rat portal fibroblasts

Portal fibroblasts (PF) are one of the two primary cell types contributing to the myofibroblast population of the liver and are thus essential to the pathogenesis of liver fibrosis. Monocyte chemoattractant protein‐1 (MCP‐1) is a known profibrogenic chemokine that may be of particular importance in biliary fibrosis. We examined the effect of MCP‐1 on release of matrix metalloproteinase‐9 (MMP‐9) by rat PF. We found that MCP‐1 blocks PF release of MMP‐9 in a posttranslational fashion. We employed an optical and electron microscopic approach to determine the mechanism of this downregulation. Our data demonstrated that, in the presence of MCP‐1, MMP‐9‐containing vesicles were shunted to a lysosome‐like compartment. This is the first report of a secretory protein to be so regulated in fibrogenic cells.

Recurrent Obstructive Giant Inflammatory Polyposis of the Colon.

Inflammatory polyps are relatively common in patients with inflammatory bowel disease. The term giant inflammatory polyposis is used to describe inflammatory polyps greater than 1.5 cm in any dimension. Their clinical presentation can be varied, ranging from asymptomatic, with incidental detection on radiological or endoscopic testing, to symptomatic, with rectal bleeding and colonic obstruction. Although giant inflammatory polyposis is a rare finding, it is of clinical importance, since it is easily mistaken for colon cancer, with patients sometimes undergoing radical surgeries. We describe an unusual case of giant inflammatory polyposis causing recurrent symptomatic obstruction despite multiple segmental colectomies in a patient with indeterminate colitis. This is the first such reported case in English literature to the best of our knowledge.

Leg Swelling and Mildly Deranged Liver Tests: An Unusual Presentation of a Usual Diagnosis

Gastroenterology 2015;149:e10–e11 Question: A 72year-old woman presented to the hospital with progressively worsening left lower extremity swelling and pain of 1 weeks’ duration. She also reported vague right upper abdominal discomfort, but did not complain of nausea, vomiting, shortness of breath, chest pain, fever, or jaundice.Her past history was significant for hypertension and Meniere disease. She had had no prior surgeries and was a lifetime nonsmoker. Her current medications were hydrochlorothiazide-triamtrene, aspirin, calcium-vitamin D, and amultivitamin. On examination, she had 2þ pitting pedal edema with mild tenderness of left lower extremity. Abdomen was soft and nontender with no palpable organomegaly or mass. The rest of the physical examination was unremarkable. Laboratory tests showed: hemoglobin, 11.8 g/dL; platelets, 277,000/mL; International Normalized Ratio, 1.3; total bilirubin, 1.4 mg/dL; alkaline phosphatase, 279 IU/L; alanine aminotransferase, 39 IU/L; and aspartate aminotransferase, 38 IU/L. Lower extremity ultrasound duplex examination was performed and showed deep venous thrombosis of left femoral vein. CT of the abdomen with oral and intravenous contrast was subsequently obtained (coronal sections; Figure A, B). What is the diagnosis? See the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI.

Rare Synchronous Gastrointestinal Plasmacytomas of Colon and Stomach.

Gastrointestinal (GI) plasmacytomas, though relatively uncommon, can occur with or without multiple myeloma. The small intestine is the most commonly involved GI site, followed by stomach, colon, and esophagus. Synchronous plasmacytomas involving 2 anatomically distinct regions of gastrointestinal tract have never been reported in the literature. We report a case of a multiple myeloma patient who had acute-onset hematochezia and was found to have synchronous plasmacytomas of the colon and stomach.

Su1684 Adenosine Regulates Cholangiocyte IL-6 Secretion via the A2B Receptor

Background. Although the kidney is believed to play a minor role in bile acid (BA) excretion, chronic renal failure (CRF) has been reported to be associated with increased serum bile acid levels and alterations in BA homeostasis. According to a recent report, rats studied 3 weeks after 5/6 nephrectomy and fed a high-protein diet exhibited increased activities of hepatic HMG-CoA reductase (HMG-CoAR) and cholesterol 7 alpha-hydroxylase (Cyp7a1), despite normal corresponding mRNA levels. Design and Methods. This study was designed to examine the effects of naturally progressing CRF of longer duration on the hepatic and renal mRNA and protein levels of the bile acid synthesizing enzyme Cyp7a1 and the bile acid transporters, Ntcp, Bsep, Mrp3, Ost-alpha and OST-beta. Sprague-Dawley rats were randomized to the CRF group (5/6 nephrectomy) or to the sham-operated, placebo-treated normal control group. They were allowed free access to regular rat chow and were analyzed 8 weeks after surgery. Results obtained in CRF rats were compared to those obtained in rats that had undergone uninephrectomy (UNX). Results. The CRF group exhibited significantly increased plasma cholesterol and bile acid concentrations. Hepatic Cyp7a1 mRNA, and protein levels were almost identical in the two groups. Hepatic Mrp3, Ostα and Ost-β expression was increased at both the mRNA and protein levels, suggesting increased basolateral efflux of bile acids into basolateral blood. However, no such changes in bile acid transporter expression were observed in kidney. In UNX rats, similar changes in plasma bile acid levels and in the expression of bile acid transporters were found. We hypothesize, that the increase in plasma bile acids is an early event in the progression of CRF and is caused by increased efflux across the basolateral hepatocyte membrane.