Contribution of CD3+CD8- and CD3+CD8+ T Cells to TNF-α Overexpression in Crohn Disease–Associated Perianal Fistulas and Induction of Epithelial-Mesenchymal Transition in HT-29 Cells

Abstract

Background Fistulas represent a frequent and severe complication in patients with Crohn disease (CD). Tumor necrosis factor-alpha (TNF-α), transforming growth factor-beta, and interleukin (IL)-13 are known to trigger epithelial-mesenchymal transition (EMT), promoting fistula formation. Here, we investigated the role of T-lymphocytes (T cells) in fistula pathogenesis. Methods CD3+CD8-, CD3+CD8+, or CD45+CD3- cells from healthy volunteers, patients with CD, and patients with CD with perianal fistula were co-cultured with HT-29 cells. The EMT, cytokine production, and mRNA expression were analyzed. Perianal CD fistula specimens were immunohistochemically stained for cytokines and their receptors. The effect of cytokines on EMT induction was investigated using an EMT spheroid model. Results Patients with CD with fistula revealed more CD3+CD8- and less CD3+CD8+ T cells in blood than healthy control patients and patients with CD without fistula. In perianal fistula specimens, CD4+ cells—and to a lesser extent CD8+ cells—were highly present around fistula tracts. When co-cultured with HT-29 cells, both cell subsets promoted EMT-related gene expression and TNF-α production in a time-dependent manner. The CD3+CD8- T cells from patients with CD with fistula also produced higher amounts of IL-13 than cells from healthy control patients or patients with CD without a fistula. We found that IL-22 and IL-22Rα1 were highly expressed in perianal CD fistula specimens and that IL-22 cotreatment potentiated TNF-α-induced EMT in HT-29 spheroids. Conclusions Our data indicate that both CD3+CD8- and CD3+CD8+ T cells play an important role in the pathogenesis of perianal CD fistulas by the secretion of TNF-α. Our data support clinical evidence indicating that anti-TNF-α therapy is effective in fistula treatment and identify IL-13 and IL-22 as possible novel therapeutic targets for fistula therapy.

New Insights on CD8+ T Cells in Inflammatory Bowel Disease and Therapeutic Approaches

“…Although the notion of the involvement of CD8 + T cells in IBD has been long considered and published ( 12 , 17 ), new attention has been given in more recent years (for summary of articles see Table 1 ). Throughout the years, the role of CD8 + T cells in IBD has been controversial, with some reports indicating anti-colitogenic properties ( 11 , 42 – 44 ) with others showing their contribution to tissue inflammation ( 5 , 12 , 16 – 18 , 20 , 31 , 36 , 39 , 45 – 47 ). Such ambivalent findings might be explained, at least partially, by the source from where CD8 + T cells were obtained (e.g.…”

“…Moreover, Boschetti and colleagues found that circulating and mucosal GrB + perforin + Tc1 cells are abundant in Crohn’s disease patients with endoscopic recurrence, compared to endoscopic remission and controls ( 39 ). In addition, Bruckner et al reported on the inflammatory effects of Tc1 cells on the mucosa of Crohn’s disease patients leading to fistulas ( 31 ), common ulcers in up to 50% of the patients. In fact, activated perforin + Tc1 cells are increased in the affected intestinal mucosa of active stages of the disease course in IBD patients ( 12 , 17 ).…”

Pathogenesis of Fistulating Crohn’s Disease: A Review

“…Both T-cell subsets secreted high amounts of TNF- and interleukin (IL)-13 in co-culture experiments, both of which are recognized as key cytokines in the pathogenesis of fistulating CD ( Figure 1 ). 14 …”

Journey through Crohn’s Disease Complication: From Fistula Formation to Future Therapies

“…Particularly, around the fistula tract, CD4 + cells were highly present. Then, both cell subsets promoted the expression of EMT-related genes when co-cultured with HT-29 cells [ 42 ].…”