S'ha establert un sistema experimental autòleg per a poder estudiar la resposta de les cèl.lules Natural Killer (NK) contra les cèl.lules dendrítiques derivades de monòcits (moDC), infectades pel Cytomegalovirus humà (HCMV). Els nostres resultats mostren que les cèl.lules NK responen contra les moDC infectades per HCMV, que presenten una expressió de les molècules MHC de classe I a superficie reduïda. Específicament, demostrem que la infecció per HCMV disminueix l'expressió en superficie d'HLA-E en les moDC, alliberant així la inhibició de les cèl.lules NK NKG2A+. Mostrem que els NKR anomenats NKp46 i DNAM-1 tenen un paper dominant en el reconeixement de les moDC infectades per HCMV i evidenciem la importància de la dinàmica dels mecanismes d'immunoevassió en la susceptibilitat a la resposta NK. Finalment, trobem que els interferons de tipus I i la IL-12 secretats en resposta a la infecció per HCMV, a més de participar en l'activació de la cèl.lula NK i en la secreció d'IFN-, inhibeixen l'expressió i la funció de NKG2D en les cèl.lules NK, com un mecanisme de regulació potencial per prevenir la reactivitat NK contra cèl.lules veïnes sanes. / Suitable experimental conditions have been established to dissect the role of NK cell receptors (NKR) and cytokines in the NK cell response against autologous human cytomegalovirus (HCMV) infected monocyte derived dendritic cells (moDC). Our results reveal that NK cells are capable of responding to HCMV infected moDC that have down-regulated surface MHC class I molecules. In particular, we prove that HCMV infection decreases surface HLA-E expression on moDC, thus releasing NKG2A+ NK cells from inhibition. We show that NKp46 and DNAM-1 NKR play a dominant role in the recognition of HCMV infected moDC and we provide evidences stressing the importance of the dynamics of viral immune evasion mechanisms in NK cell susceptibility. Finally, we find that type I interferons and IL-12 secreted in response to HCMV infection, beyond their participation in NK cell activation and IFN- secretion, transiently inhibit the expression and function of NKG2D in NK cells, thus providing a potential regulatory feedback mechanism to prevent NK cell reactivity against bystander healthy cells.

Serous epithelial ovarian cancer (EOC) is a potent suppressor of the immune defense. Here, we studied interactions between EOC and the immune system that lead to escape from tumor immune surveillance. We explored: 1) tumor escape from cytotoxicity by exosome-mediated modulation of the NK-cell receptors NKG2D and DNAM-1; 2) cytokine mRNA profiles in the EOC microenvironment and peripheral blood and their role in the suppression of the anti-tumor immune responses; 3) expression of long non-coding (lnc) RNAs in EOC tumors and exosomes. We found that EOC-secreted exosomes carried MICA/B and ULBP1-3, ligands of NKG2D, and could downregulate the NKG2D receptor and impair NKG2D-mediated cytotoxicity. In contrast, the DNAM-1 receptor ligands PVR and nectin-2 were seldom found in exosomes and were not associated with the exosomal membrane leaving the DNAM-1 receptor-mediated cytotoxicity intact. We compared cytokine mRNA expression in the tumor microenvironment and in immune cells of peripheral blood in EOC patients and patients with benign ovarian conditions. EOC patients were unable to mount an IFN-gamma mRNA response needed for tumor cell elimination. Instead, there was a significant up-regulation of inflammation and immune suppression i.e. responses promoting tumorigenesis and T-regulatory cell priming that suppress anti-tumor immunity. In addition, we studied lncRNAs in tissues and sera exosomes from EOC and benign ovarian conditions aiming to assess the lncRNA(s) expression profile and look for lncRNA(s) as possible marker(s) for early diagnosis. We found a deregulated lncRNAs expression in EOC tissues that correlated well with the lncRNAs expression in exosomes. Candidate lncRNAs with the highest expression and abundance were suggested for evaluation as EOC diagnostic markers in a future large cohort study. Our studies of EOC tissue and EOC exosomes highlight the immunosuppressive tumor microenvironment and the complex tumor exosome-mediated network of immunosuppressive mechanisms, and provide a mechanistic explanation of the observation that NKG2D-mediated cytotoxicity does not function in EOC patients and is partially replaced by the accessory DNAM-1 dependent cytotoxic pathway. The deregulated lncRNAs expression in EOC tissues and exosomes might serve for diagnostic purposes but could also be a potential risk of spreading tumor-derived lncRNAs in EOC exosomes to recipient cells throughout the body.