T lymphocytes are one of the main immune cells of the body and are important in damaging the bowel in IBD. Regulatory T lymphocytes (“Tregs”) however are a subtype thought to suppress other immune cells from damaging the body and therefore have an anti-inflammatory effect. It is known that there are fewer Treg cells in the blood of IBD patients, possibly because they have moved to the bowel, and that defective Treg cells have been associated with other autoimmune diseases.
Apoptosis is the process of planned cell death, which is a normal process in many human cells, particularly T cells. Previously it has been shown that there is increased apoptosis of some cell types in patients with IBD. It was the aim of this study to see if this was true of Treg cells and if the apoptosis (cell death) was reversed by treatment with anti-TNFα treatment (in this case infliximab).
The study showed that in there were indeed more Treg cells in the bowel of patients with IBD than in healthy people, but that these cells had increased apoptosis. In the blood, there were fewer Treg cells in IBD patients than healthy people but still more apoptosis. After infliximab, the cell numbers and apoptosis improved in patients who got better, but didn’t change in those that remained unwell.
The authors suggest that the death of these Treg cells may be involved in the process that leads to the development of IBD, and that this may be a target of anti-TNFα treatment such as infliximab. Monitoring Treg apoptosis may also become a new way of monitoring disease activity or treatment response in IBD patients.