Differences in tolerogenic status of NK cells between luminal A type, luminal B type, and triple-negative breast cancer.

Globally, breast cancer is the main cause of death among female cancer patients. The tumor-infiltrating lymphocytes (TILs) in breast cancer are associated with a more favorable outcome of a disease. Natural killer (NK) cells are important cytotoxic cells involved in tumor immunosurveillance, causing the direct killing of tumor cells. In solid tumors, peripheral NK cells and tumor-infiltrating NK cells display an altered phenotype characterized by reduced cytotoxicity or anergy. The goal of this study was to investigate the NK cells' phenotype and activation status in order to get into the pathological process of breast cancer subtypes. In our study, the normal tissues and tumoral breast tissue were fixed in formalin, embedded in paraffin, and the phenotypic marker CD56 and proinflammatory cytokine IL-15 were identified by immunohistology. The distribution and expression of receptors repertoire (NKG2A, NKG2C, NKp46, CD94, CD69, and CD107a) were investigated in peripheral NK cells of mononuclear cells by flow cytometry. mRNA of cytolytic mediators was determined by real-time PCR. The frequency of CD56+ and IL-15+ cells were significantly higher in triple-negative breast cancer tissue. The frequency of NK cell activating receptors was decreased in investigated breast cancer subtypes while the inhibitory NKG2A receptor was increased. Decreased percentage of CD69+/CD107a+ in NK cells could indicate lower cellular activation and cytotoxicity. In luminal B breast cancer, the mRNA of cytolytic mediators was upregulated. In conclusion, modulation of activation status in tumor-infiltration NK cells could be involved in the pathogenesis of molecular breast cancer subtypes. This highlights the importance of NK cells as an appropriate target for potent anti-tumor response in the immunosuppressive tumor microenvironment of breast cancer.

The Role of Innate Immunity in the Pathogenesis of Breast Cancer.

BACKGROUND: Breast carcinoma is the most common malignant disease in the female population and one of the leading causes of death among women worldwide. One crucial hallmark of cancer is chronic inflammation where the immunosuppressive environment is dominant. The immunosuppressive environment is largely achieved by the interaction of tumor cells and infiltrating leukocytes. SUMMARY: Usually, human macrophages and natural killer cells are involved in antitumor immunity. The therapeutic potential of this population against cancers has stimulated their study and led to the discovery of several different tumor-associated macrophages and natural killer cell subsets, each of which is endowed with different immunoregulatory functions. Both heterogeneity and plasticity of the tumor-associated macrophages and natural killer cell compartment, which are both tightly linked to the tumor microenvironment of different breast cancer types. KEY MESSAGES: The identification of specific tumor-associated macrophages and natural killer cell subsets endowed with particular functional capabilities might help monitor tumor-mediated responses in breast cancer patients. Currently, one of the most used strategies for breast cancer of newly diagnosed patients is neoadjuvant chemotherapy.

Granulysin expression and the interplay of granulysin and perforin at the maternal-fetal interface.

Granulysin (GNLY) is a cytolytic/apoptotic molecule highly expressed in immune cells, particularly NK cells, at the maternal-fetal interface. The primary function of GNLY is to carry out lysis or apoptosis induction in target cells, tumor cells or cells infected by intracellular pathogens. To exert some of its functions GNLY needs to collaborate with perforin. The purpose of this study was to determine: (a) the expression of GNLY at the gene and protein levels at the maternal-fetal interface, (b) the relationship(s) between GNLY and perforin, and (c) GNLY secretion by NK cells stimulated by the NK-sensitive K562 cell line and its HLA-C and HLA-G transfectants. GNLY and perforin genes were found to be highly activated at the interface. GNLY mRNA was present at significantly higher levels compared with other cytolytic/apoptotic molecules. Confocal microscopy analysis showed that most first trimester pregnancy decidual lymphocytes simultaneously contained both GNLY and perforin protein in their cytoplasm, with a punctuate pattern consistent with granule localization. In contrast to peripheral blood, in unstimulated decidual lymphocytes GNLY and perforin rarely co-localized (10% of GNLY-positive cells and 20% of perforin-positive cells were positive for both proteins). Contact between decidual lymphocytes and K562 cells caused GNLY and perforin to be expressed in the same granules (approximately 50% co-localization), i.e., to attain the pattern seen in peripheral blood lymphocytes. The abundant GNLY secretion by decidual NK cells compared with peripheral blood NK cells after 2h of contact with the NK-sensitive K562 cells and K562 transfectants was striking.

Cell death mechanisms at the maternal-fetal interface: insights into the role of granulysin.

During mammal pregnancy, a sensitive balance between hormones, cytokines, humoral factors, and local cellular interactions must be established. Cytotoxic cells infiltrating the decidua are heavily equipped with cytolytic molecules, in particular perforin and granulysin. Granulysin is especially abundant in NK cells which are able to spontaneously secrete high quantities of granulysin. Besides being a potent bactericidal and tumoricidal molecule, granulysin is also found to be a chemoattractant and a proinflammatory molecule. The precise role(s) of granulysin at the maternal-fetal interface has not been elucidated yet. It is possible that it behaves as a double-edged sword simultaneously acting as an immunomodulatory and a host defense molecule protecting both the mother and the fetus from a wide spectrum of pathogens, and on the other hand, in case of an NK cell activation, acting as an effector molecule causing the apoptosis of semiallograft trophoblast cells and consequently leading to various pregnancy disorders or pregnancy loss.