TGM2 and vitamin D deficiency: Recently, in healthy subjects with vitamin D deficiency, we gave evidence of a concomitant increase in mRNA levels of TGM2 and pro-inflammatory cytokines, as well as biomarkers of cell adhesion, such as intercellular adhesion molecule 1 (ICAM) and lymphocyte function-associated antigen 1 (LFA-1), involved in immune activation, indicating that TG2 may be a marker of PBMC activation [24,28].