Assessment of the activity of the immune system in patients with inflammatory bowel diseases and asymptomatic COVID-19.

Introduction: Although the phenomenon of cytokine storm is well described in patients with severe COVID-19, little is known about the role of the immune system in asymptomatic patients, especially in the group with autoimmune diseases, such as inflammatory bowel disease (IBD).

Aim: To assess the stimulation of the immune system expressed through the production of cytokines in IBD patients with asymptomatic COVID-19.

Material and methods: This is a multi-centre, prospective study in which the concentration of many cytokines (IL-1a, IL-1b, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-13, IL- 15, IL-17, IL-23, IFN-γ, TNF-α, TNF-β) was assessed in patients with IBD and asymptomatic SARS-CoV-2 infection diagnosed by serological tests.

Results: In the group of patients with a recent SARS-CoV-2 infection, defined as positive antibodies in the IgA + IgM class, a higher percentage of patients with the presence of interleukin (IL) 2 (IL-2) was found. No association with other cytokines or effects of IBD activity or treatment was found. However, the effect of the applied treatment on the concentration of some cytokines was found: a negative association of infliximab, vedolizumab, and prednisone with IL-2, a positive correlation of steroids, thiopurines with IL-10, and in the case of tumor necrosis factor-α (TNF-α), negative with infliximab, and positive with vedolizumab.

Conclusions: The increased concentration of IL-2 may result from its regulatory role in inhibiting excessive activation of the immune system; however, considering the studies of patients with severe COVID-19, its role in the initial phase of SARS-CoV-2 infection requires further research.