Procollagen-III peptide identifies adipose tissue-associated inflammation in type 2 diabetes with or without nonalcoholic liver disease.

Background: Procollagen-III peptide (PIIINP) is a marker of fibrosis associated with increased cardiometabolic risk and progression of chronic liver diseases such as nonalcoholic fatty liver disease (NAFLD) and steatohepatitis; its association with type 2 diabetes mellitus (T2DM) has not been elucidated yet. The aim of this study was to investigate the relationship among circulating PIIINP levels, metabolic traits, and body fat distribution in subjects with T2DM with or without NAFLD.

Methods: Data from 62 T2DM subjects recruited in our diabetes outpatient clinics at Sapienza University of Rome, Italy, were analysed. Participants underwent metabolic and inflammatory profiling (CRP, TNFα, IL-6, IL-8, WISP1, and adiponectin) and magnetic resonance imaging for diagnosing NAFLD on the basis of hepatic fat fraction (≥5.5%) and quantifying visceral and subcutaneous adipose tissue (AT) areas. Serum PIIINP was measured by human-PIIINP ELISA kits.

Results: Higher PIIINP levels correlated with greater BMI and visceral AT area and were associated with systemic signatures of AT-associated inflammation-ie, higher WISP-1, IL-8, and lower adiponectin levels; conversely, PIIINP did not differ significantly between T2DM patients with or without NAFLD and were not associated with hepatic fat fraction, Fatty Liver Index, FIB-4, or transaminases.

Conclusions: Elevated circulating PIIINP levels specifically identify T2DM individuals with AT expansion and systemic proinflammatory profile suggestive for AT dysfunction; our results point toward a new role of PIIINP as a marker of fibroinflammation in dysmetabolic conditions, likely related to AT expansion.