Hepatocyte growth factor activator inhibitor-2 prevents shedding of matriptase.

Hepatocyte growth factor activator inhibitor-2 (HAI-2) is an inhibitor of many proteases in vitro, including the membrane-bound serine protease, matriptase. Studies of knock-out mice have shown that HAI-2 is essential for placental development only in mice expressing matriptase, suggesting that HAI-2 is important for regulation of matriptase. Previous studies have shown that recombinant expression of matriptase was unsuccessful unless co-expressed with another HAI, HAI-1. In the present study we show that when human matriptase is recombinantly expressed alone in the canine cell line MDCK, then human matriptase mRNA can be detected and the human matriptase ectodomain is shed to the media, suggesting that matriptase expressed alone is rapidly transported through the secretory pathway and shed. Whereas matriptase expressed together with HAI-1 or HAI-2 accumulates on the plasma membrane where it is activated, as judged by cleavage at Arg614 and increased peptidolytic activity of the cell extracts. Mutagenesis of Kunitz domain 1 but not Kunitz domain 2 abolished this function of HAI-2. HAI-2 seems to carry out its function intracellularly as this is where the vast majority of HAI-2 is located and since HAI-2 could not be detected on the basolateral plasma membrane where matriptase resides. However, minor amounts of HAI-2 not undergoing endocytosis could be detected on the apical plasma membrane. Our results suggest that Kunitz domain 1 of HAI-2 cause matriptase to accumulate in a membrane-bound form on the basolateral plasma membrane.

Fasting serum concentration of short-chain fatty acids in subjects with microscopic colitis and celiac disease: no difference compared with controls, but between genders.

BACKGROUND: Short-chain fatty acids (SCFAs), particularly propionic and butyric acids, have been shown to have many positive health effects. The amount and type of SCFAs formed from dietary fibre by the colonic microbiota depends on the substrate available and is reflected in blood. The total intake and type of dietary fibre in people with gastrointestinal diseases differs considerably from healthy subjects. OBJECTIVE: To compare fasting SCFA concentrations in subjects with microscopic colitis (MC), celiac disease and controls without these diseases. SCFAs were also analysed over 6.5 h in young healthy subjects, who had eaten a fibre-rich breakfast, to identify a possible peak concentration of SCFAs after a meal. METHODS: SCFAs in serum were pre-concentrated using hollow fibre-supported liquid membrane extraction and gas chromatography. RESULTS: The MC group had a higher concentration of valeric acid than the control group (p < 0.01). No significant differences in other SCFA concentrations were seen between groups, but the control group tended to have higher concentration of acetic acid (p = 0.1). Furthermore, males had higher concentrations of SCFAs (with the exception of valeric acid) than females (p < 0.05), which were independent of groups. The peaks for acetic, propionic and butyric acids came approximately 5 h, 6.5 h and 2-3 h, respectively, after breakfast. CONCLUSION: The fasting concentrations of SCFAs were quite similar, although the fibre intake had probably been quite different for a long time. The results might have been different if SCFAs had been recorded over a longer period.

Collagen mRNA levels changes during colorectal cancer carcinogenesis.

BACKGROUND: Invasive growth of epithelial cancers is a complex multi-step process which involves dissolution of the basement membrane. Type IV collagen is a major component in most basement membranes. Type VII collagen is related to anchoring fibrils and is found primarily in the basement membrane zone of stratified epithelia. Immunohistochemical studies have previously reported changes in steady-state levels of different alpha(IV) chains in several epithelial cancer types. In the present study we aimed to quantitatively determine the mRNA levels of type IV collagen (alpha1/alpha 4/alpha 6) and type VII collagen (alpha1) during colorectal cancer carcinogenesis. METHODS: Using quantitative RT-PCR, we have determined the mRNA levels for alpha1(IV), alpha 4(IV), alpha 6(IV), and alpha1(VII) in colorectal cancer tissue (n = 33), adenomas (n = 29) and in normal tissue from the same individuals. In addition, corresponding tissue was examined from healthy volunteers (n = 20). mRNA levels were normalized to beta-actin. Immunohistochemical analysis of the distributions of type IV and type VII collagens were performed on normal and affected tissues from colorectal cancer patients. RESULTS: The alpha1(IV) and alpha1(VII) mRNA levels were statistically significantly higher in colorectal cancer tissue (p < 0.001) as compared to corresponding tissue from healthy controls. This is an early event as tissue from adenomas also displayed a higher level. There were small changes in the levels of alpha 4(IV). The level of alpha 6(IV) was 5-fold lower in colorectal cancer tissue as compared to healthy individuals (p < 0.01). The localisation of type IV and type VII collagen was visualized by immunohistochemical staining. CONCLUSION: Our results suggest that the down-regulation of alpha 6(IV) mRNA coincides with the acquisition of invasive growth properties, whereas alpha1(IV) and alpha1(VII) mRNAs were up-regulated already in dysplastic tissue. There are no differences in collagen expression between tissues from healthy individuals and normal tissues from affected individuals.

Deamidation and cross-linking of gliadin peptides by transglutaminases and the relation to celiac disease.

Activation of small intestinal gluten-reactive CD4+ T cells is a critical event in celiac disease. Such cells predominantly recognise gluten peptides in which specific glutamines are deamidated. Deamidation may be catalysed by intestinal tissue transglutaminase (TG2), a protein which is also the main autoantigen in celiac disease. Our aim was to study how the two main catalytic activities of transglutaminase--deamidation and transamidation (cross-linking) of an immunodominant gliadin epitope--are influenced by the presence of acceptor amines in the intestinal mucosa, and thereby contribute to further elucidation of the pathogenetic mechanisms in celiac disease. We prepared monoclonal antibodies, reacting specifically with the non-deamidated epitope QPFPQPQLPYPQPQ-amide and/or the deamidated epitope QPFPQPELPYPQPQ-amide. A solid phase immunoassay combined with gel filtration chromatography was used to analyse deamidation and cross-linking of these peptides to proteins. Our results show that QPFPQPQLPYPQPQ-amide was deamidated when incubated with purified TG2, with fresh mucosal sheets and with mucosal homogenates. Of other transglutaminases tested, only Streptoverticillium transglutaminase was able to generate the deamidated epitope. A fraction of the non-deamidated epitope was cross-linked to proteins, including TG2. The results suggest that intestinal TG2 is responsible for generation of the active deamidated epitope. As the epitope often occurs in a repeat structure, the result may be cross-linking of a deamidated, i.e., activated cell epitope. Alternatively, the deamidation may occur by reversal of the cross-linking reaction. The results provide a basis for the suggestion that binding of a peptide to a protein, in connection to its modification to a T cell epitope, might be a general explanation for the role of TG2 in celiac disease and a possible mechanism for the generation of autoantigens.

Celiac disease: diagnosis and treatment.

This national clinical guideline approved by the Danish Society for Gastroenterology and Hepatology describes the diagnosis and treatment of celiac disease (CD) in adults. CD is a chronic immune-mediated enteropathy of the small intestine triggered by the ingestion of gluten-containing proteins, which are found in wheat, rye, and barley. The disease prevalence is 0.5-1.0%, but CD remains under-diagnosed. The diagnosis relies on the demonstration of lymphocyte infiltration, crypt hyperplasia, and villous atrophy in duodenal biopsies. Serology, malabsorption, biochemical markers, and identification of specific HLA haplotypes may contribute to CD diagnosis. Classical CD presents with diarrhoea and weight loss, but non-classical CD with vague or extraintestinal symptoms is common. The treatment for CD is a lifelong gluten-free diet (GFD), which, in the majority of patients, normalises the small intestinal mucosa and absorption. Adherence to a GFD usually requires dietary advice from a clinical dietician. The monitoring of antibody levels and malabsorption markers is crucial during follow-up and allows for early treatment of disease complications. Important complications include osteoporosis, iron and vitamin deficiencies, and enteropathy-associated T-cell lymphoma.

[Celiac disease--a diagnostic and scientific challenge]. / Cøliaki--en diagnostisk og videnskabelig udfordring.

It is possible that Denmark has a high proportion of patients with undiagnosed coeliac disease in the general population and in such risk groups as patients with autoimmune endocrinological and neurological disorders. An active diagnostic strategy, with screening of patients at risk is proposed. Several gliadin epitopes that might be pathogenetically important are described. Tissue transglutaminase is an autoantigen and a deamidating factor in vitro.

[Septic shock after exposure to Vibrio vulnificus]. / Havkolera--septisk shock udløst af bløddelsinfektion med Vibrio vulnificus.

Vibrio vulnificus (Vv) is a rare cause of infections in Denmark. In this case, a patient suffering from chronic diseases developed wound infection, severe sepsis and despite adequate treatment, septic shock after exposure to seawater and fish. The fact that the condition was caused by Vv was not identified until the results of the blood cultures. Vv is the cause of primary sepsis, wound infections and gastroenteritis. The infection is treated with fluid resuscitation, broad-spectrum antibiotics and surgical intervention. In low-incidence areas as in Denmark, there should be an obligation to notify the health authorities about infection with Vv to ensure proper monitoring of and focus on these cases.