Characterization of Interleukin 10 gene variations and serum levels as predictive factors for the clinical outcome of Non-Hodgkin Lymphoma patients and Analysis of molecular mechanisms of Interleukin 10 gene regulation in B cells

Abstract

Aggressive Non-Hodgkin lymphoma (aNHL) comprises a heterogeneous group of lymphatic malignancies. Although current treatment regiments can achieve high response rates, many patients do not achieve complete remission. Reliable and clinically applicable prognostic markers are needed to improve treatment strategies. Previous studies suggested a role for the cytokine interleukin 10 (IL10) for the initiation and progression of lymphomas. Conflicting data about associations of IL10 gene variations or elevated IL10 serum levels with the clinical outcome of aNHL exists. Therefore, this study aimed at elucidating whether these two factors could be of prognostic relevance for aNHL outcome in independent larger clinical cohorts and to investigate molecular mechanisms contributing to this. Overall 1724 aNHL patients from three different clinical trials (NHL-B, RICOVER-60 and MInT) have been included into this study. 604 patients were from RICOVER-60 trial, of which sera were available from 523 patients. Survival analyses revealed that patients with low IL10 serum levels had a better treatment outcome compared to patients with elevated IL10 serum levels. This is also true for patients, treated with Rituximab in addition to chemotherapy, which is the current standard therapy. Therefore, circulating levels of IL10 could be of prognostic relevance for aNHL outcome. In addition, in vitro studies showed that IL10 treatment of target cells seems to reduce Rituximab-mediated antibody dependent cellular cytotoxicity (ADCC) but not complement dependent cytotoxicity (CDC). Furthermore, it was found that homozygous carriers the of IL10-11.668AA far distal IL10 gene variation, located within an evolutionary conserved sequence, showed a better treatment outcome compared to carriers of the other two genotypes in the RICOVER-60 cohort (OS: HR=0.6; CI= 0.38-0.95; EFS: HR=0.6; CI= 0.41-0.87). Chromatin immunoprecipitation (ChIP) of modified histones revealed enhancer specific histone modifications around IL10-11.668G/A and other conserved sequences in transformed B cells. Therefore, they seem to be involved in IL10 gene regulation. Moreover, a very long non-coding RNA has been found to be transcribed from the IL10 gene locus. The results of this study confirm an important role for IL10 in the clinical course of aNHL and provide new insight into the structure and regulation of the IL10 gene.