Supplementary Material for: Intestinal inflammation and permeability in patients recovered from SARS-CoV-2 infection.

Introduction: Different works suggest a close link between Long COVID Gastrointestinal (GI) manifestations
and the post-infection disorders of gut-brain interaction (PI-DGBIs). However, the actual mechanisms underlying long-term GI sequelae are still not clear. Our study was aimed to assess both intestinal inflammation and permeability among subjects recovered from SARS-CoV-2 infection and their eventual correlation with long-term GI sequelae.

Methods: Eighty-six subjects attending the Post-COVID Service and recovered from SARS-CoV-2 infection for six months, were investigated for Long COVID manifestations. Those subjects complaining of long-term GI symptoms were further evaluated by Rome IV questionnaire to assess PI-DGBIs. Intestinal inflammation (by fecal calprotectin, FC), and
permeability (by serum and fecal levels of zonulin) were evaluated in all subjects. The Hospital Anxiety and Depression Scale (HADS) and The Gastrointestinal Quality of Life Index (GIQLI) questionnaires were further provided to all participants.

Results: Thirty-seven subjects (43%) complained of long-term GI symptoms, while 49 subjects (57%) did not. Thirty-three subjects fulfilled Rome IV criteria for PI-DGBIs. FC values resulted higher in those subjects who did not complain GI symptoms (p=0.03), although remaining quite close to the normal range. No significant differences were shown
regarding the assessment of intestinal permeability. By GIQLI, long-term gastrointestinal sequelae were inversely correlated with quality of life (p=0.009).

Conclusion: Long COVID GI complaints unlikely recognize underlying local inflammatory mechanisms. Since the healthcare, economic, and social burden of post‐COVID DGBIs, a deeper understanding of this emerging condition should be encouraged to improve management of the affected subjects.