Background: Celiac disease (CD) is a systemic inflammatory disease, which primarily affects the gastrointestinal tract. It has been recently demonstrated that adipose-tissue infiltration by proinflammatory immune cells causes a chronic low-grade inflammation in obese patients. Magnetic resonance imaging (MRI) has already proved to be useful in evaluation of inflammatory states. The aim of the present study was to determine whether alterations of visceral and subcutaneous adipose tissue, identified with MRI, could serve as markers of local and systemic inflammation in patients with CD.
Methods: A pilot study was conducted comparing alterations in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) in CD patients vs obese patients and healthy controls. Fifty patients were enrolled and assigned to one of the following groups: Group A: 11 active CD patients; Group B: 11 CD patients in remission; Group C: 16 obese patients; Group D: 12 healthy controls. A 3-T MRI unit was used and T2-weighted TSE images of VAT and SAT were obtained in specific regions of interest. Serum cytokine concentrations (TNF-α, IL-6, adiponectin, leptin, IL-2, IFN-γ) were determined.
Results: There was a significant difference in VAT T2 relaxation time between Group A and B (p < 0.001), A and D (p < 0.01), B and C (p < 0.001). There was a statistically significant difference in SAT T2 relaxation time between Group A and B (p < 0.001), A and C (p < 0.05), A and D (p < 0.001), B and C (p < 0.01). In addition, VAT/SAT T2 relaxation time ratio showed a statistically significant difference between Group A and C (p < 0.05) and between Group B and C (p < 0.01). Only TNF-α and IL-6 significantly correlated with both VAT and VAT/SAT ratio in active CD.
Conclusions: MRI showed similar increased visceral inflammatory signals in patients with active CD and obese patients. However, subcutaneous inflammatory signals were higher in active CD than in all the other groups. These data show that there is a systemic inflammatory state in active CD, whereas chronic inflammation appears confined to VAT in obesity. These data were only partially confirmed by serological cytokine profiles, which showed less specificity than MRI.
Keywords: Adipose tissue; Celiac disease; Cytokines; Inflammation; Magnetic resonance imaging; Obesity.