Gastrointestinal Manifestations and Pathophysiological Mechanisms in Systemic Sclerosis
Sammanfattning: Systemic sclerosis (SSc) is a rare systemic, autoimmune disease characterized by vascular changes and fibrosis of the skin and internal organs.Patients with SSc more frequently than healthy controls reported upper gastrointestinal (GI) symptoms, which was more abundant in the diffuse cutaneous form (dcSSc) of the disease than in the limited (lcSSc). One-third of a population-based cohort of 79 SSc patients reported faecal incontinence, compared to 11% in 158 healthy matched controls (p<0.001), and this symptom negatively influenced general well-being and social life. Impaired rectal sensibility, rectal bleeding, irritable bowel syndrome-like symptoms, abdominal pain, the need for manual assistance at defecation, and the use of oral laxatives were more common in patients than in controls. SSc patients reported lower scores in both physical and mental scales of the SF-36 questionnaire than controls, indicating worse health-related quality of life.Gastric emptying was slower in patients than in controls, and a higher prevalence of delayed gastric emptying in patients with dcSSc indicated more severe GI tract involvement than in lcSSc. Electrogastrographic recordings did not correlate to gastric emptying results, indicating factors other than defective myoelectric signals contributed to disturbed gastric function.SSc patients with faecal incontinence had lower anal squeeze pressures than patients without this symptom. Only patients with faecal incontinence had ultrasonographic abnormalities in the internal and external anal sphincters, and absence of the rectoanal inhibitory reflex. Thus, faecal incontinence in SSc patients may depend on both neurogenic and structural mechanisms. A discrete increase in fibre density observed in a majority of SSc patients might have implications from a disease mechanistic perspective.Sera from 47% of 70 SSc patients had the capacity to induce interferon (IFN)-α, production which correlated to the presence of anti-RNP and anti-SSA autoantibodies. Increased serum levels of IFN-inducible protein were associated with vascular manifestations, and increased serum levels of IFN-α with digital ulcers. Increased serum levels of monocyte chemoattractant protein-1 or IFN-α were associated with lung fibrosis. An activated type I IFN system previously observed in several other systemic autoimmune diseases is also present in SSc and may contribute to vascular pathology and the pro-fibrotic process.
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