Antibodies to cytoskeletal proteins in patients with Crohn's disease

Animal models of gastrointestinal inflammation and cancer

Inflammation and cancer are the two major disorders in the gastrointestinal tract. They are causally related in their pathogenesis. It is important to study animal models' causal relationship and, in particular, to discover new therapeutic agents for such diseases. There are several criteria for these models in order to make them useful in better understanding the etiology and treatment of the said diseases in humans. In this regard, animal models should be similar as possible to human diseases and also be easy to produce and reproducible and also economic to allow a continuous replication in different laboratories. In this review, we summarize the various animal models for inflammatory and cancerous disorders in the upper and lower gastrointestinal tract. Experimental approaches are as simple as by giving a single oral dose of alcohol or other noxious agents or by injections of multiple dosages of ulcer inducing agents or by parenteral administration or in drinking water of carcinogens or by modifying the genetic makeups of animals to produce relatively long-term pathological changes in particular organs. With these methods they could induce consistent inflammatory responses or tumorigenesis in the gastrointestinal mucosa. These animal models are widely used in laboratories in understanding the pathogenesis as well as the mechanisms of action for therapeutic agents in the treatment of gastrointestinal inflammation and cancer.

IgA anti-actin antibodies in children with celiac disease: comparison of immunofluorescence with Elisa assay in predicting severe intestinal damage

BACKGROUND

Previous studies have demonstrated that the presence of serum IgA antibodies against actin filaments (AAA) in patients with celiac disease (CD) is strongly associated with mucosal damage and severe degrees of villous atrophy.The aims of the present study were (1) to verify the effectiveness of IgA-AAA in newly diagnosed CD patients in a clinical setting (2) to compare the immunofluorescence assay with ELISA assay; (3) to compare the correlation of our IgA anti-tissue transglutaminase antibodies (tTG-Ab) class with mucosal intestinal lesions.

METHODS

90 patients underwent endoscopy and multiple biopsies for suspected CD on the basis of symptoms, in presence of positive tTG-Ab tests. Twenty biopsied and 25 not-biopsied subjects with negative tTG-Ab were tested as control groups. IgA-AAA assays were performed by indirect immunofluorescence using rat epithelial intestinal cells, and by ELISA with a commercial kit. tTG-Ab assay was a radio-binding assay. Intestinal specimens were collected by upper endoscopy and the histological study was done according to the Marsh's classification modified by Oberhuber (M/O). Auto-antibodies assays and histological evaluation have been performed blindly by skilled operators.

RESULTS

CD diagnosis was confirmed in 82 patients (type I M/O in 2 patients, IIIA in 18 patients, IIIB in 29 patients and IIIC in 33 patients). Two patients with type 1 lesion in presence of positive tTG-Ab and abdominal complaints, started a gluten free diet. The rate of IgA-AAA positivity (sensitivity) by IFI and ELISA in histologically proven celiac disease patients, were 5.5% and 25% patients in IIIA, 27.5% and 34.4% patients in IIIB, 78.8% and 75% in IIIC patients, respectively.Patients with normal or nearly normal mucosa, regardless of tTG-Ab status, presented negative IgA-AAA IFI assay. On the other hand, 1 patient with normal mucosa but positive tTG-Ab, also presented positive IgA-AAA ELISA. All healthy non biopsied controls had negative IgA-AAA. tTG-Ab serum concentration was significantly correlated with more severe intestinal lesion (IIIB, IIIC M/O).

CONCLUSIONS

IgA-AAA may be undetectable in presence of severe mucosal damage. Histology is still necessary to diagnose celiac disease and IgA-AAA cannot be included in usual screening tests, because it has little to offer if compared to the well-established tTG-Ab.IgA-AAA could be an adjunctive, very useful tool to support the diagnosis of CD in case of suboptimal histology, when the biopsy is to be avoided for clinical reasons, or in case of negative parents' consensus.

IgA autoreactivity: a feature common to inflammatory bowel and connective tissue diseases

The immunopathogenic mechanisms in inflammatory bowel disease (IBD) are not yet fully established. The aim of this study was to determine the profile and magnitude of IgA and IgG autoantibodies in IBD patients. The autoantigen profile defined by IgA and IgG antibodies from 24 IBD (14 Crohn's disease CD], 10 ulcerative colitis UC]), three coeliac, 12 connective tissue disease (CTD) patients and 10 healthy individuals was studied in human cellular extracts by Western blotting. The magnitude of the IgA and IgG1-4 subclass responses was measured by ELISA. IBD patients could not be distinguished from healthy individuals on the basis of IgG autoantibodies to Western blotted proteins. IgG subclass analysis indicated no clear bias towards Th1 or Th2 immune responses in IBD or CTD. In accordance with previous work, we found that IgA autoreactivity was strongest in coeliac disease patients. Unexpectedly, IBD as well as CTD patients exhibited strong IgA autoantibody reactivities to components of similar molecular weights (16-80 kD) in intestinal and non-intestinal epithelial cell lines. Our data indicate immunopathogenic similarities between IBD and CTD.

Detection of antivimentin antibody in sera of patients with idiopathic pulmonary fibrosis and non-specific interstitial pneumonia

It has been suggested that the humoral immune system plays a role in the pathogenesis of non-specific interstitial pneumonia (NSIP). Although some circulating autoantibodies to cytoskeletal protein(s) have been suggested, the antimyofibroblast antibody has not been investigated in patients with idiopathic pulmonary fibrosis (IPF) and NSIP. The purpose of this study is to evaluate the existence of antimyofibroblast antibody in the sera of patients with IPF and NSIP. The MRC5 cell line was used as a model of myofibroblast. The anti-MRC5 cell antibody was characterized in a patient with NSIP using Western blotting. Since we found that one of the anti-MRC5 antibodies was an antivimentin antibody, we established an enzyme-linked immunosorbent assay (ELISA) to measure the levels of antivimentin antibody in the sera of patients with IPF (n = 12) and NSIP (n = 23). Initially, two anti-MRC5 cell antibodies were detected in the sera of patients with NSIP, one of which was characterized as the antivimentin antibody by Western blotting. The other was characterized as an antivimentin fragment antibody. We established an ELISA to measure the antivimentin antibody and found significantly higher levels in patients with IPF and NSIP than in normal volunteers. One of the anti-MRC5 cell antibodies in the serum of a patient with NSIP was against vimentin. The serum levels of antivimentin antibody were increased in patients with IPF and NSIP compared with that of normal volunteers. These results suggest that the antivimentin antibody may be involved in the process of lung injury in IPF and NSIP.

Non-muscle myosin as target antigen for human autoantibodies in patients with hepatitis C virus-associated chronic liver diseases

Three patients with hepatitis C virus (HCV)-related chronic liver disease were shown to have autoantibodies strongly reacting with cytoskeletal fibres of non-muscle cells. The heavy chain of non-muscle myosin microfilament was the main target for those autoantibodies, as determined by (i) cell and tissue immunofluorescence studies showing colocalization with an anti-myosin antibody prototype; (ii) primary reactivity in immunoblotting with a 200-kD protein, using either MOLT-4 cells, human platelets, or affinity-purified non-muscle myosin as antigen extract; and (iii) immunoblotting of similar immunoreactive fragments in papain-digested MOLT-4 cell extracts, by using those human sera and antibody prototype. Autoantibodies to non-muscle myosin heavy chain were not previously reported in patients with chronic liver diseases, especially in those associated with HCV infection.