Psoas muscle size as a magnetic resonance imaging biomarker of progression of pancreatitis.

Abstract

<h4>Objective</h4>Pancreatitis often represents a continuous inflammatory process, from the first episode of acute pancreatitis (FAP) to recurrent acute pancreatitis (RAP) to chronic pancreatitis (CP). Psoas muscle size is a validated surrogate for global skeletal mass, changes in which are associated with inflammation. The objective was to investigate psoas muscle size in individuals following FAP, RAP, and CP, as well as its associations with pro-inflammatory cytokines.<h4>Methods</h4>Individuals following pancreatitis and healthy individuals were recruited. All participants underwent magnetic resonance imaging, from which psoas muscle volume was derived independently by two raters in a blinded fashion. Circulating levels of four major cytokines (interleukin-6, tumour necrosis factor-α, C-C motif chemokine ligand 2, and leptin) were measured. Five linear regression additive models were built to adjust for possible confounders (age, sex, body composition, physical activity, tobacco smoking, alcohol consumption, comorbidities, and endocrine and exocrine pancreatic functions).<h4>Results</h4>A total of 145 participants were enrolled. A significant downward trend in psoas muscle volume was observed between healthy controls and individuals following FAP, RAP, and CP in all adjusted models (p = 0.047, 0.005, 0.004, and < 0.001). Leptin was significantly associated with psoas muscle volume in all models (β = - 0.16, p = 0.030 in the most adjusted model). The other studied cytokines were not significantly associated with psoas muscle volume.<h4>Conclusions</h4>Psoas muscle size is significantly reduced along the continuum from FAP to RAP to CP. Leptin appears to be one of the factors implicated in this. Further studies are warranted to investigate the relationship between skeletal muscle and inflammation of the pancreas.<h4>Key points</h4>• First acute pancreatitis, recurrent acute pancreatitis, and chronic pancreatitis were associated with progressively reduced psoas muscle size. • The findings were independent of age, sex, body fat composition, physical activity, tobacco smoking, alcohol consumption, comorbidities, and exocrine and endocrine functions of the pancreas. • The mechanism underlying the observed findings may involve hyperleptinaemia.