Do gliadin and tissue transglutaminase mediate PPAR downregulation in intestinal cells of patients with coeliac disease

The accumulation of toxic gliadin peptide was proposed to initiate tissue transglutaminase (tTG) upregulation in coeliac intestine.1 Upregulation of tTG drives inflammation through the ubiquitination and proteasomal degradation of the anti-inflammatory peroxisome proliferator-activated receptor (PPAR). To understand further the contribution to mucosal-associated damage in coeliac disease caused by tTG upregulation, we have quantified the expression levels of several proteins directly involved in the PPAR signalling pathway and/or related to PPAR activation. Our study population consisted of patients with coeliac disease at first diagnosis with gut inflammation (n=1 Marsh 2; n=5 Marsh 3; immunoglobulin A (IgA)-tTG ≥cut-off); IgA-tTG-negative patients with coeliac disease who had recovered from intestinal damage while on a gluten-free diet (GFD) (n=4 Marsh 0–1); and control patients with excluded …