Gastrointestinal regulatory peptides in systemic sclerosis

Gastrointestinal involvement commonly occurs in systemic sclerosis (SSc), but its pathogenesis is not well understood. Since there is evidence of a defect in neurotransmitter release, we were interested in examining the relationship between gastrointestinal dysfunction and plasma concentrations of gastrointestinal regulatory peptides in patients with SSc. We studied 43 consecutive patients, 18 with diffuse and 25 with limited cutaneous disease.

Levels of corticotropin-releasing hormone (CRH), gastrin, motilin, neuropeptide Y (NPY), and peptide YY (PYY) were determined by radioimmunoassay and high-performance liquid chromatography (HPLC).

Plasma concentrations of CRH, motilin, NPY, and PYY were significantly increased among SSc patients compared with healthy control subjects, and HPLC-characterization of motilin, NPY, and PYY showed a different pattern of fragments. No correlation was found between esophageal hypomotility and the concentration of peptide. Acid output did not correlate with gastrin levels, but was more often increased in patients with increased CRH and NPY values. Fat malabsorption, assessed by the triolein breath test, was more common among patients with increased motilin and PYY.

This study shows that elevated peptide concentrations commonly occur in patients with SSc. Since regulatory peptides are involved in gastrointestinal motility, secretion, and absorption, further characterization of this neuroendocrine system may help in understanding the complex regulation of gastrointestinal dysfunction in SSc.