P686 Expression of CD39 ectonucleotidase on regulatory T cells and on T helper 17 cells in children with IBD receiving anti-TNF therapy

S.V. Petrichuk1, Т. Radygina1, A. Illarionov2, D. Kuptsova1, A. Potapov3, A.P. Fisenko3

1National Medical Research Center for Children’s Health, Laboratory of Experimental Immunology and Virology, Moscow, Russian Federation, 2Sechenov First Moscow State Medical University of the Ministry of Health of the Russian Federation, Department of Pediatrics and Rheumatology, Moscow, Russian Federation, 3National Medical Research Center for Children’s Health, Gastroenterology and Hepatology, Moscow, Russian Federation

Background

CD39, CD73 ectonucleotidases convert extracellular ATP (eATF) to adenosine. eATF is known to have pro-inflammatory activity, and adenosine has anti-inflammatory activity. It was shown decreasement CD39 expression on regulatory T lymphocytes (Treg) during exacerbation in adult patients with IBD. The aim of this study was to evaluate the expression of CD39 on Treg and Th17 lymphocytes (Th17) in children with inflammatory bowel diseases (IBD) with different responses to anti-TNF therapy.

Methods

The study included 68 children with IBD (CD 35 patients, UC 33 patients) aged 4–18 years with duration of the disease from 6 months till 15 years. All patients were treated with anti-TNF (infliximab, adalimumab) during 11–86 weeks. Clinical response was evaluated according to PUCAI (UC) and PCDAI (CD) scores. Group 1 (n = 35) included patients with exacerbation during anti-TNF therapy, in Group 2 (n = 25) patients with sustained remission. The expression of CD39 on Treg (CD3CD4CD25CD127low) and Th17 cells (CD3CD4CD161) was determined by flow cytometry (NovoCyte Acea Biosciences, Inc.). Statistical analysis was performed using nonparametric Mann–Whitney test and ROC analysis (SPSS Statistics 20).

Results

It were observed inflammatory activity increasement according to PUCAI (Med 40 [30–65], p = 0.8 × 10–5) and PCDIA scores (Med 28.8 [15–55], p = 1.2 × 10–5) in Group 1 in comparison with Group 2. The amount of Treg expressing CD39 (Treg CD39) was 6–58% from Treg (6–80 cl/μl), and the amount of Th17 with the CD39 marker (Th17CD39) was 0.5–57% (2–49 cl/μl). A direct correlation was revealed between TregCD39 and Th17CD39 (r=0.55 p = 1 × 10–6). It was shown that the number of TregCD39 and Th17CD39 does not depend on the age of the child. However, with an increase in the duration of the disease, a decrease in the absolute amount of Th17CD39 is observed (r = −0.3, p = 0.016). In patients Group 1 there was a significant reduction of CD39 expression on Treg (p = 0.00002) and on Th17 (p = 0.0009) compared with a Group 2 in both diseases. The dependence of TregCD39 on PUCAI (r = −0.5 p = 0.013) and PCDAI (r = −0.43 p = 0.03) was revealed. ROC analysis showed that the cut-off level for groups 1 and 2 is 31.7% for TregCD39 (AUC=0.77; Se 69%, Sp 68%) and 37 cl/μl (AUC=0.907; Se 88%, Sp 88%). Cut-off level for the absolute amount of Th17CD39 was 21 cl/μl (AUC=0.888; Se 79%, Sp 81%).

Conclusion

The decreasement in the amount of TregCD39 below 31 cl/μl and Th17CD39 below 21 cl/μl is associated with an exacerbation of the disease. The expression level of ectonucleotidase CD39 on Treg and Th17 in children with IBD receiving anti-TNF therapy is independent of age and allows to differentiate the state of remission and exacerbation.