Crohn's disease-specific anti-CUZD1 pancreatic antibodies are absent in ruminants with paratuberculosis

Pancreatic anti-GP2 and anti-Saccharomyces cerevisiae antibodies in ruminants with paratuberculosis: A better understanding of the immunopathogenesis of Crohn's disease

INTRODUCTION

Ruminants (cattle and sheep) with Mycobacterium avium (MAP)-induced paratuberculosis (ptb), the ruminant model of Crohn's disease (CD), exhibit pancreatic specific autoantibodies (PAB) against GP2 but not against CUZD1. Since anti-Saccharomyces cerevisiae antibodies (ASCAs) is a CD marker, we tested MAP-infected ptb ruminants for ASCA, and compared them with ruminants lacking evidence of anti-MAP serology or with ruminants, which were positive for anti-GP2 antibodies.

MATERIAL AND METHODS

A total of 98 samples from ruminants (48 cattle and 50 sheep) were studied. IgG anti-MAP antibodies, and CD-related ASCA and anti-GP2 antibodies were tested by modified ELISAs.

RESULTS

Nine cattle (18.75%) and 20 sheep (40%) were suffered from ptb. ASCA antibodies were present in 21/48 (43.7%) cattle and 10/50 (20%) sheep while anti-GP2 antibodies were present in 14/48 (29.2%) cattle, and 8/50 (16%) sheep. ASCA antibodies were more prevalent in anti-MAP antibody positive (14/29, 48.3%) than in anti-MAP negative ruminants (17/69, 24.6%, P=0.022) and also in anti-GP2 antibody positive (13/23, 56.5%) than in anti-GP2 negative ruminants (18/75, 24%, P=0.003). No association between ASCA and anti-MAP antibody concentrations were found (r=0.159, P=0.117). A significant association between ASCA and anti-GP2 antibody concentration were observed (r=0.211 and P=0.037).

CONCLUSION

ASCA are present in a significant proportion of ruminants with ptb and correlate with anti-GP2 antibody positivity, a finding further supporting the notion that Crohn's disease and ptb share common immunological mechanisms of antigen-driven loss of self-tolerance.

The search for the Holy Grail: autoantigenic targets in primary sclerosing cholangitis associated with disease phenotype and neoplasia

Unlike in other autoimmune liver diseases such as autoimmune hepatitis and primary biliary cholangitis, the role and nature of autoantigenic targets in primary sclerosing cholangitis (PSC), a progressive, chronic, immune-mediated, life threatening, genetically predisposed, cholestatic liver illness, is poorly elucidated. Although anti-neutrophil cytoplasmic antibodies (ANCA) have been associated with the occurrence of PSC, their corresponding targets have not yet been identified entirely. Genome-wide association studies revealed a significant number of immune-related and even disease-modifying susceptibility loci for PSC. However, these loci did not allow discerning a clear autoimmune pattern nor do the therapy options and the male gender preponderance in PSC support a pathogenic role of autoimmune responses. Nevertheless, PSC is characterized by the co-occurrence of inflammatory bowel diseases (IBD) demonstrating autoimmune responses. The identification of novel autoantigenic targets in IBD such as the major zymogen granule membrane glycoprotein 2 (GP2) or the appearance of proteinase 3 (PR3) autoantibodies (autoAbs) have refocused the interest on a putative association of loss of tolerance with the IBD phenotype and consequently with the PSC phenotype. Not surprisingly, the report of an association between GP2 IgA autoAbs and disease severity in patients with PSC gave a new impetus to autoAb research for autoimmune liver diseases. It might usher in a new era of serological research in this field. The mucosal loss of tolerance against the microbiota-sensing GP2 modulating innate and adaptive intestinal immunity and its putative role in the pathogenesis of PSC will be elaborated in this review. Furthermore, other potential PSC-related autoantigenic targets such as the neutrophil PR3 will be discussed. GP2 IgA may represent a group of new pathogenic antibodies, which share characteristics of both type 2 and 3 of antibody-mediated hypersensitive reactions according to Coombs and Gell.