Papel de receptores activadores e inhibidores en la educación de células NK y su relación con la progresión y supervivencia de pacientes con cánceres sólidos (Melanoma, Vejiga y Ovario)

Resumen

INTRODUCTION Survival of cancer patients has progressively improved in recent decades as new, increasingly effective treatments have become available. Chemotherapy has shown good results in early stages of cancer. However, a significant number of tumors are resistant to known drugs, this has let to various biologic drugs that attempt to boost the patient's immune system to attack the tumor. Some drugs only manage to extend survival by a few months, and others, at very high prices and for very specific types of cancer, have managed to cure patients who did not respond to other treatments. Among these treatments, NK cell-based therapies offer hopeful results in patients with solid tumors. The adequate selection of donors, the optimization of the methods to expand NKs in vitro and the education of these cells aim to improve their interactions with the neoplastic cells of patients, increasing their life expectancy. The evaluation and study of receptor genes and KIR ligands and the expression levels of different membrane proteins will help us to know the relationship at the molecular level that determine the interaction of NK cells with tumor cells, thus allowing us to select more effective cells. MATERIALS AND METHODS The studies included 621 healthy Caucasian volunteers (control group) and 249 Caucasian patients with melanoma (n=80), bladder (n=80), and ovarian (n=89) tumors. In the bladder cancer study, a second group of patients (n=84) was included in a retrospective analysis to reach a total of 164 patients with bladder tumors. Peripheral blood was obtained in EDTA tubes from all patients (n=249) and from 42 healthy controls between 2014 and 2016 at the Virgen de la Arrixaca University Clinical Hospital and the Santa Lucia General University Hospital (Murcia, Spain). For in vivo assays, proliferation of T lymphocytes and expression of surface markers, peripheral blood anticoagulated with sodium heparin was obtained. HLA class-I (KIR ligands) and KIR genotyping was performed on all samples in the series. Further, the expression of CD3, CD4, CD8, CD16, CD226 and inhibitory and activating KIR receptors and NKG2A on T and NK cells was analyzed by flow cytometry. Patients were followed up until July 2017 to estimate progression-free survival (PFS) and overall survival (OS), in relation to KIR/ligand interactions and CD226 expression. RESULTS The interaction of the inhibitory molecules with their ligands produces an overexpression of the CD226 costimulatory molecule and a reduction in the expression of the inhibitory receptor interaction. It has been possible to verify how patients with higher CD226 expression or higher CD226/inhibitor ratios have longer survival. In the other hand, it was possible to demonstrate that the interaction of the KIR activators is associated with a decrease in the expression of CD226 in the educated NK cells, without the alteration of the expression of CD226 in the uneducated ones. Finally, a possible KIR2DL5/HLA-C*16 interaction was identified, other combinations of KIR receptors with their ligands, allowing to differentiate 3 groups of risk of progression (low, medium and high) and overall survival in patients affected by bladder cancer. CONCLUSIONS Unfortunately, therapies are currently personalized based on clinicopathological criteria and, therefore, patients with a poor prognosis can undergo, for example, removal of the urinary vesicle and have survival rates of more than 10 years or, conservative therapies in patients with a good prognosis who subsequently have an aggressive course of the disease and might have benefited from early removal of the bladder. Therefore, there must be additional factors that determine the survival of these patients, and one of the main factors is the diversity of the immune system, which after the cytoreduction to which the patient is subjected in the early stages of treatment, can favor more antitumor responses effective against residual tumor tissue in some patients than in others. Although NK cells are known to be one of the major cell populations of the immune system involved in the antitumor response and in immunosurveillance against tumors, the role played by the interactions of inhibitory and activating molecules that guide their formation and functional activity It has been little explored, in general and, in particular, in solid tumors. In this thesis study, in a large number of patients with solid tumors (melanoma, ovary and bladder), it is shown that in NK cells the interaction of inhibitory receptors with their corresponding ligands has a notable effect on the expression of their receptors activators and inhibitors and therefore the activator/inhibitor ratio.