Tissue Transglutaminase Research Papers - Academia.edu (original) (raw)

Malignancies arising from biliary tract epithelia, or cholangiocarcinoma, are rare tumors that have a poor prognosis. The incidence of these tumors is gradually increasing in many countries. Recent advances have been made in identifying... more

Malignancies arising from biliary tract epithelia, or cholangiocarcinoma, are rare tumors that have a poor prognosis. The incidence of these tumors is gradually increasing in many countries. Recent advances have been made in identifying some of the risk factors, and the need for appropriate classification is emerging. The diagnosis of cholangiocarcinoma is often difficult and requires multiple complementary studies. The use of molecular approaches may improve the diagnostic utility of biliary cytology. Treatment of these tumors is complex, and there are many different treatment options. Although surgical resection can be curative, many patients with cholangiocarcinoma are diagnosed at an advanced stage when only palliative approaches can be used. Photodynamic therapy is emerging as a useful modality.

In 2012 the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) published an updated guideline for the diagnosis of Coeliac disease, allowing symptomatic individuals with appropriate serology and HLA... more

In 2012 the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) published an updated guideline for the diagnosis of Coeliac disease, allowing symptomatic individuals with appropriate serology and HLA genotype to be diagnosed without a small bowel biopsy. This retrospective study aimed to assess the applicability of this guideline to children in . Children less than 16 years of age investigated for coeliac disease with small bowel biopsy in between January 2010 and December 2012 were identified. The results of those with tissue transglutaminase IgA (tTG) levels greater than 50 units (10 times upper limit of normal), positive endomysial antibodies and HLA DQ2/DQ8 were used to calculate sensitivity and specificity. Data from 160 children was available: 70 had biopsy-confirmed Coeliac disease, and 90 had negative biopsies. Limited data precluded application of the guidelines to all patients. Using only tTG data, levels above 50 units provided a sensitivity of 67% and a specificity of 92%. Specificity increased to 97% when limited EMA and HLA DQ2/DQ8 data was added. Despite limited data, applying the ESPGHAN guidelines in the paediatric population over this period produced a high specificity (97%). Prospective studies are now required to confirm these findings.

The surge in incidence of celiac disease (CD) is due more to environmental than to genetic changes. It is paralleled by a food industry that is continuously introducing additives to processed products. Microbial transglutaminase (mTG) is... more

The surge in incidence of celiac disease (CD) is due more to environmental than to genetic changes. It is paralleled by a food industry that is continuously introducing additives to processed products. Microbial transglutaminase (mTG) is an enzyme that deamidates/transamidates proteins, enabling cross-linkage of molecules and revolutionizing the properties of many food products. It belongs to the family of transaminases and tissue transglutaminase (tTG) has been identified as the autoantigen in CD. Both enzymes de/transamidate gluten, the nutritional environmental factor that induces CD. Although several studies have shown that mTG transamidation of wheat flour/gluten can detoxify gluten peptide in vitro, by inhibiting the response to intestinal gliadin, inducing T cells and reducing INFγ production without influencing their main technological properties, a word of caution is advised. The oral challenge of adult CD patients with mTG transamidated flour was found to be only partially effective, not fulfilling expectations, and there have been multiple recent observations that indicate that mTG transamidated flour/gluten could be dangerous to gluten sensitive populations: mTG cross-linking of gluten may be hazardous in CD since the enzyme can deamidate gluten, thus mimicking endogenous tTG, it can link an extensive repertoire of proteins and other macromolecules with immunogenic potential, mTG treated gluten peptides are immunogenic to celiac patients, inducing specific IgA antibodiesand are recognized by gluten-specific humanT cells. Their effect on CD intestinal permeability has not yet been studied. To better understand the actual processes and events, associated with the suggested mTG therapy, long-term ex vivo and in vitro studies are needed. Until then, it is best to respect the data but suspect the safety of the gluten sensitive populations.

Celiac disease (CD) is the most common autoimmune enteropathy in the western world caused by the intolerance to gluten in genetically predisposed individuals. CD is characterized by a remarkable rearrangement of the mucosal architecture,... more

Celiac disease (CD) is the most common autoimmune enteropathy in the western world caused by the intolerance to gluten in genetically predisposed individuals. CD is characterized by a remarkable rearrangement of the mucosal architecture, in which process myofibroblasts play a crucial role. Myofibroblasts (intestinal subepithelial myofibroblasts and interstitial cells of Cajal) are the most represented mesenchymal cell types in the gut mucosa and are involved in a broad range of biological processes including growth, mucosal protection, repair, inflammation and fibrosis. Myofibroblasts actively contribute to the mucosal changes in CD due to their ability to produce an excessive amount of extracellular matrix and basement membrane components (e.g. collagens, fibronectin, and specific enzymes including tissue transglutaminases) and through the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs). The enhanced production of ECM components and MMPs and the altered shape and motility of myofibroblasts in the duodenal mucosa of patients with CD suggest that myofibroblasts may play an essential role in the pathogenesis of CD.

Effects of acetylcholine and of the cholinergic precursors choline, cytidine 5′-diphosphocholine (CDP-choline) and α-glyceril-phosphorylcholine (α-GPC) on transglutaminase (TG) and cyclin D1 expression were studied in primary astrocyte... more

Effects of acetylcholine and of the cholinergic precursors choline, cytidine 5′-diphosphocholine (CDP-choline) and α-glyceril-phosphorylcholine (α-GPC) on transglutaminase (TG) and cyclin D1 expression were studied in primary astrocyte cultures by confocal laser microscopy (CLSM) with monodansyl-cadaverine uptake as a marker of enzyme activity and by immunochemistry (Western blotting). CLSM analysis showed an increased cytofluorescence in 0.1 μM choline-treated astrocytes. Treatment with CDP-choline dose-dependently increased TG. A total of 1 μM CDP-choline exposure in 14 days in vitro (DIV) astrocyte cultures increased cytofluorescence. A total of 1 μM α-GPC 24 h-treated cultures revealed increased cytofluorescence both in cytosol and nuclei. Western blot analysis showed an increased TG expression in cultures exposed for 24 h to 1 μM choline or α-GPC, whereas in 24 h 1 μM CDP-choline and acetylcholine-treated astrocytes TG expression was unaffected. Treatment with 1 μM acetylcholine reduced TG expression at 21 DIV. In cultures at 14 and 35 DIV cholinergic precursor treatment for 24 h induced a marked down-regulation of cyclin D1 expression, with reduced cyclin D1 expression in 1 μM α-GPC treated astrocytes. Our data suggest a role of cholinergic precursors investigated independent from acetylcholine on maturation and differentiation of astroglial cells in vitro, rather than on their growth, proliferation and development in culture.

Imatinib, a tyrosine kinase inhibitor directed against the enzymatic domain of KIT protein, was found to produce dramatic clinical responses in metastatic gastrointestinal stromal tumors (GISTs). However, resistance usually develops thus... more

Imatinib, a tyrosine kinase inhibitor directed against the enzymatic domain of KIT protein, was found to produce dramatic clinical responses in metastatic gastrointestinal stromal tumors (GISTs). However, resistance usually develops thus determining treatment failure. The present study was performed to analyse the expression of somatostatin receptor (SSTR) subtypes, modulators of tissue transglutaminase, in a series of GISTs and leiomyosarcomas by immunohistochemistry to identify a new potential therapeutic target. Sixteen cases (8 males and 8 females, age range: 38–73; 11 GISTs, 4 leiomyosarcomas, 1 leiomyoma) were studied. Immunohistochemical detection of the relevant SSTRs was performed on paraffin-embedded tissue sections, stained with polyclonal antibodies directed against the five somatostatin receptor subtypes. We found 7 out of 16 (44%) tumors expressing all SSTRs and 14 out of 16 (87%) tumors positive for at least 3 subtypes. SSTR2A was the most represented subtype in the tumors studied, being expressed in approximately 70% of cases exhibiting an intense labeling in most of these cases. The significant expression of SSTRs shown in this series of GISTs and gastrointestinal leiomyosarcomas suggests a potential therapeutic target to be explored alone and/or in combination with other therapeutic agents in the setting of refractory GI stromal tumors.