Abstract
ObjectivesThe pathogenesis of intestinal involvement in systemic sclerosis (SSc) is thought to be a sequential process (vascular, neuronal, and consecutive muscular impairment), but understanding of the underlying histological changes and how they translate to symptoms, is still lacking. Therefore, we systematically investigated histological characteristics of SSc in the intestines, compared to controls.MethodsAutopsy material from the small bowel and colon was used for histological semiquantitative evaluation of the vasculature, enteric nervous system, interstitial cells of Cajal (ICC), and muscle layers, using a combination of histochemical and immunohistochemical stainings, according to guidelines of the Gastro 2009 International Working Group.ResultsVascular changes were most frequently encountered, represented by intima fibrosis in both arteries and small vessels, and represented by venous dilatation. Second, generalized fibrosis of the circular muscle layer was significantly more found in SSc patients than in controls. Third, reduction of submucosal nerve fibers and myenteric neurons was shown in the colon of four SSc patients, which may explain severe symptoms of intestinal dysmotility. The density of myenteric ICC network was decreased in the small bowel of SSc patients.ConclusionsThe postulated sequential processes of intestinal involvement in SSc could not be supported by our histological evaluation. The interpatient diversity suggests that parallel processes occur, explaining the variety of histological features and clinical symptoms.Key Points• Histological analysis showed vascular changes, fibrosis in the muscularis propria, and reduction of the ENS and ICC network in the intestines of SSc patients.• Pathophysiological mechanisms leading to intestinal dysmotility in SSc may be parallel rather than sequential.• The interpatient diversity suggests parallel pathophysiological processes, explaining the variety of histological features and clinical symptoms.
Highlights
Systemic sclerosis (SSc) is an autoimmune disease characterized by inflammation, vasculopathy, and fibrosis of the skin and internal organs
The SSc group consisted of 14 small bowel and 18 colon cases; from 11 patients, tissues of both locations were analyzed
We found collagen patterns similar to that in the esophagus, defined here as “fibrosis.” Polyglucosan inclusion bodies were significantly more frequently observed in SSc cases, which may be associated with intestinal myopathy [30]
Summary
Systemic sclerosis (SSc) is an autoimmune disease characterized by inflammation, vasculopathy, and fibrosis of the skin and internal organs. The major causes of death in SSc are pulmonary fibrosis, Clin Rheumatol (2021) 40:981–990 pulmonary hypertension, and cardiac disease, the most common organ complication is involvement of the gastrointestinal (GI) tract [1, 3, 4]. The esophagus is most commonly involved (up to 96% of patients), followed by the small intestine (40– 88%) and colon (10–50%) [5, 6]. The major symptom is hypomotility, sometimes leading to pseudo-obstruction and bacterial overgrowth [10,11,12]. Cholinergic neurotransmission may be inhibited by the presence of autoantibodies in these patients [16] and deposition of collagen in the small intestinal wall may result in pseudo-obstruction [11]. Hypomotility can result in delayed transit and constipation [11]
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