Immunohistochemical Expression of Antitissue Transglutaminase 2 in Tissue Injuries: An Interpretation Beyond Celiac Disease

Appl Immunohistochem Mol Morphol. 2018 Jul;26(6):425-430. doi: 10.1097/PAI.0000000000000430.

Abstract

Tissue transglutaminase 2 enzyme plays a diverse role in intracellular and extracellular functioning. Aberrant expression of anti-TG2 antibody has recently been proposed for extraintestinal identification of celiac disease (CeD), but its utility is questionable. To examine whether anti-TG2 immunohistochemical (IHC) staining can be of diagnostic value in identifying extraintestinal involvement in CeD, tissue blocks of patients with IgA nephropathies (IgAN), minimal change disease, membranous glomerulonephritis, membrano-proliferative glomerulonephritis, normal kidney, intestinal biopsies from CeD, tropical sprue, nonspecific duodenitis, and inflammatory bowel disease; liver biopsies from patients with chronic hepatitis B and C, acute liver failure (ALF), and CeD-associated liver diseases were retrieved and subjected to IHC staining for anti-tissue transglutaminase 2 enzyme. H-score was calculated by multiplying the area of positivity and stain intensity. Anti-TG2 stain H-scores were almost similar in IgAN and non-IgANs (H-score 6.31±3 vs. 7.03±2.7); however, H-scores in both of these groups were significantly higher than in normal renal parenchyma (1.6±1.5). Only 6.2% patients with IgAN with anti-TG2 immunostain positivity showed a positive anti-tTG antibody serology and villous abnormalities, suggestive of CeD. Intestinal biopsies from patients with CeD, tropical sprue, nonspecific duodenitis, and inflammatory bowel disease also showed high anti-TG2 H-scores, with no statistically significant differences. Liver biopsies from patients with both ALF, as well as chronic liver diseases showed high anti-TG2 H-scores; with highest stain expression in ALF. In conclusion, IHC expression of anti-TG2 stain correlates with both acute and chronic tissue injuries, irrespective of etiology and organ involvement. It is not a reliable marker for diagnosis of CeD.

MeSH terms

  • Autoantibodies / metabolism
  • Autoantigens / immunology*
  • Biomarkers / metabolism
  • Biopsy
  • Celiac Disease / diagnosis*
  • Celiac Disease / immunology
  • GTP-Binding Proteins / immunology*
  • Hepatitis, Viral, Human / diagnosis*
  • Humans
  • Immunoglobulin A / metabolism
  • Immunohistochemistry
  • Kidney Diseases / diagnosis*
  • Predictive Value of Tests
  • Prognosis
  • Protein Glutamine gamma Glutamyltransferase 2
  • Transglutaminases / immunology*

Substances

  • Autoantibodies
  • Autoantigens
  • Biomarkers
  • Immunoglobulin A
  • TGM2 protein, human
  • Protein Glutamine gamma Glutamyltransferase 2
  • Transglutaminases
  • GTP-Binding Proteins