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P070 The level of nuclear factor kappa B (NF-kB) translocation during infliximab therapy in children with IBD

S. Petrichuk1, T. Radigina1, D. Gerasimova1, A. Illarionov2,3, A. Anushenko2, T. Erlikh-Fox4, A. Potapov*2

1National Medical Research Center for Children's Health, Laboratory of Experimental Immunology and Virology, Moscow, Russian Federation, 2National Medical Research Center for Children's Health, Gastroenterology and Hepatology, Moscow, Russian Federation, 3Sechenov First Moscow State Medical University, Department of Pediatrics and Pediatric Rheumatology, Moscow, Russian Federation, 4National Medical Research Center for Children's Health, Cytochemical Research Center, Moscow, Russian Federation

Background

NF-kB is a universal transcription factor located in the cell cytoplasm that translocates into the nucleus when it is activated. This leads to the synthesis of proinflammatory cytokines, chemokines, growth factors and activation of cell effector functions. The aim of this study was to assess the level of NF-kB translocation in lymphocyte populations during treatment with infliximab (IFX) in children with IBD.

Methods

In total, 31 children aged 12–18 years were examined: 21 patients with IBD (12 UC, 9 CD) (Group 1) and 10 clinically healthy children (Group 2). Blood samples were taken from Group 1 patient before the infusion of IFX and next day after infusion. Intracellular NF-kB localisation was quantitatively analysed in lymphocyte populations by Amnis NF-kB kit by ImageStreamX MKII (Amnis). For populations of CD3 + CD4 + (Th), CD3 + CD8 + (Tc), CD3-CD19 + (B cell), CD3-CD16 / 56 + (NK), CD3 + CD4 + CD161 + (Th17), CD3 + CD4 + CD25highCD127low (Treg) was estimated the total number of cells and the percentage of cells with NF-kB translocation (the level of activation). The IDEAS image analysis software was applied. Similarity score algorithm was used for assess events of translocation.

Results

In Group 1 on IFX treatment with clinical and endoscopic relapse there is an increase in cells with NF-kB translocation in the main populations of lymphocytes compared with a Group 2, mostly in Th (37.7 ± 2.7% vs. 14.9 ± 1.0, p < 0.01) and Tc (39.4 ± 3.0% vs. 15.3 ± 1.5, p < 0.01). The total number of Th17 (% of CD4 +) in Group 1 before the IFX infusion averaged 34.6%, and Treg (% of CD4 +) – 11.6%, which exceeded the level of these populations in Group 2 (Th17 18.6%; Treg 7.8%). At the same time, NF-kB translocation level of in the Treg population did not differ from Group 2, and in the population of Th17 lymphocytes the level of NF-kB translocation was 1.7 times higher. It was observed a 1.4 times decrease in the activation level of Th17 and 2 times increase in the activation of Treg while the quantity of those lymphocyte populations were stable.

Conclusion

The level of translocation NF-kB, measured by the ImageStream platform, is a rapidly changing index that allows to evaluate the functional activity of the lymphocyte populations at the time of the laboratory investigation. The level of NF-kB translocation in the lymphocyte populations, which is an important marker of the autoimmune activity in IBD (Treg, Th17) reflects the body's response to the administration of IFX. An increase in Treg activity and a decrease in Th17 activity under the action of a TNFα blocker explains the molecular mechanism leading to a weakening of the inflammatory process.