Vladimir Jurisic

A comparison of the NK cell cytotoxicity with effects of TNF-α against K-562 cells, determined by LDH release assay

Effects of r h TNF-alpha as a single cytotoxic mediator against K-562 cells was examined by LDH release and compared with NK cell cytotoxicity. The mean values of the percentage of LDH release (x = 6.25 +/- 3.68%, for ten individual experiments) from K-562 cells cultured for 2 h with r h TNF-alpha 100 U/ml of culture medium did not give significant difference in comparison with mean values of percentage LDH release (x = 6.43 +/- 2.97%, for 37 individual experiments) from K-562 cells which were cultured without r h TNF-alpha (Students t-test, P > 0.05). The results also showed, that in the presence of increasing concentrations of r h TNF-alpha there was no significant increase of LDH release through the cell membrane in these short term incubations. However, significant difference in LDH release from K-562 cells was found after 6 h between cultures treated for 30 min with or without r h TNF-alpha (Mann-Whitney test, P < 0.05). Since TNF-alpha alone shows a lower degree of K-562 cell membrane damage than NK effectors, this suggested that TNF-alpha is neither an only nor a major mediator of cell destruction, based on determination of LDH release.

The difference in NK-cell activity between patients with non-Hodgkin's lymphomas and Hodgkin's disease

Natural killer (NK) cells play an important role in immune surveillance against malignant diseases. Considering the lymphoid origin of malignant lymphomas, as well as scarce data concerning NK‐cell function in these neoplasms, we evaluated NK‐cell activity in 49 patients with non‐Hodgkins lymphomas (NHL) and 47 patients with Hodgkins disease (HD), prior to therapy. Using the recommended International Working Formulation and the Ann Arbor staging system for classification of lymphomas we found, by the LDH release cytotoxicity assay, that decreased NK‐cell activity (P < 0.05) in NHL patients was essentially related to unfavourable histology (13 indolent lymphomas, 25 intermediate and 11 very aggressive lymphomas were included), but that within these categories clinical stage of the disease also contributed to the degree of NK‐cell dysfunction. In contrast, in HD, NK‐cell activity was persistently decreased (P < 0.05), compared to controls, irrespective of histological type and clinical stage. It is of interest also that the most profound NK‐cell dysfunction that is present and persistent from the onset of HD, and which appears in very aggressive NHL was associated with the phenomenon of increased spontaneous lactate acid dehydrogenase (LDH) release activity from the separated PBMC of these patients. The difference in the level of NK‐cell impairment between patients with various histological grades of malignancy in NHL and HD suggests different initial participation of innate immune reactions in these diseases.

Association of NK cell dysfunction with changes in LDH characteristics of peripheral blood lymphocytes (PBL) in breast cancer patients.

The cytotoxic activity of NK (natural killer) cells is very important in immunological surveillance against the appearance and especially the spread of malignant disease. The aim of this study was to investigate the function of this subpopulation of cells in breast cancer patients in different clinical stages of disease prior to therapy. NK cell activity was determined in breast cancer patients and healthy controls by three different methods: standard 51-chromium-release assay and by the original colorimetric uncorrected and corrected lactate dehydrogenase (LDH) release assay. A discrepancy was shown between the assays, as the uncorrected LDH assay showed, not only, much higher values, but no stage-dependent depression in NK cell activity compared to the chromium-release assay. Further analyses of separately cultured peripheral blood lymphocytes (PBL) revealed that this difference arose from an increasing, clinical stage-dependent, spontaneous LDH release from PBL of breast cancer patients. Furthermore, a stage-dependent increase in intracellular LDH activity of PBL was found, although without difference in LDH-H and LDH-M isotype ratio, compared to controls. Increased spontaneous LDH release and intracellular LDH activity was more evident in young patients, under 40 years. Correction of the original LDH-release assay for the spontaneous LDH release activity from PBL present in the assay, gave values of NK cell activity comparable to those determined by the chromium assay and indicated that breast cancer patients have a significant depression in NK cell activity which correlates with the stage-dependent increase in spontaneous LDH release. Moreover, as both assays measure the secretory, perforin-mediated, NK cell cytotoxic pathway against tumor cells, it can be concluded that the appearance of spontaneous LDH release is an indicator of cell membrane damage which not only allows the loss of LDH, but also of the components of the secretory killing pathway, resulting in NK cell dysfunction with the progression of disease. The novel findings obtained in this work reveal the association of PBL membrane damage with clinical stage of breast cancer that can, aside from reflecting NK cell depression, underlie the defect in other PBL subsets and subsequently facilitate progression of the malignant process.

Biomarkers of suppressed natural killer (NK) cell function in metastatic melanoma: Decreased NKG2D and increased CD158a receptors on CD3―CD16+ NK cells

In metastatic melanoma (MM) patients we evaluated natural killer (NK)-cell activity, distribution of several NK receptors and their correlation with NK function. Peripheral blood lymphocytes (PBL) of MM patients and controls were analysed for NK activity and expression of activating NKG2D, CD161 and KIR, CD158a and CD158b receptors on CD3–CD16+ NK cells. MM patients not only had significantly decreased NK activity and NK-cell interferon (IFN)-γ production, a redistribution of NK-cell subsets with an increase in CD16dim and a reduction in CD16bright NK subsets. There was a decreased CD161 and NKG2D and an increased CD158a NK-cell expression in MM patients, with a positive correlation between NKG2D expression and NK cytotoxicity and an inverse correlation between CD158b expression and NK-cell cytotoxicity in patients. Furthermore, patients’ CD3-CD16bright NK subset showed lower expression of CD161 and CD158a. Therefore, NKG2D, CD158a and CD158b expression in MM patients may represent several clinically useful ‘biomarkers’ of suppressed NK function.

Activity of MMP-2 and MMP-9 in sera of breast cancer patients

Gelatinase A (MMP-2) and gelatinase B (MMP-9) are proteolytic enzymes involved in the process of tumor invasion, and they are considered as possible tumor markers in breast cancer patients. In this study, we examined serum activity of proMMP-2 and proMMP-9 in relation to TNM stage, tumor size, lymph node involvement, grade of differentiation of tumors, as well as steroid and Her2/neu receptor status in breast cancer patients. The activity of gelatinase in the sera of 52 patients was analyzed by SDS-PAGE zymography. The activity of proMMP-2 and proMMP-9 significantly increased with each advancing clinical stage of disease (p=0.02-0.0009) and compared to controls (p=0.015 to p<0.01). We found a positive correlation between the activity of proMMP-2 and proMMP-9 and tumor size (p=0.007; p=0.05). Patients with lymph node-positive cancer have higher proMMP-2 and proMMP-9 activity than those with node-negative cancer. ProMMP-2 and proMMP-9 activity is not associated with the expression of Her2/neu receptors, but patients with Her2/neu overexpression (3+) showed increased proMMP-2 activity. Steroid receptor score is not associated with enhanced gelatinase activity. The relationship between the increase in proMMP-2 and proMMP-9 activity in serum and tumor size and lymph node status suggests the usefulness of these enzymes as staging markers of breast cancer patients.

Investigation of NK cell function and their modulation in different malignancies

NK cells have become a subject of investigation not only in the field of tumor immunology and infectious diseases, but also within all aspects of immunology, such as transplantation, autoimmunity, and hypersensitivity. Our early studies aside from investigating NK cell activity in experimental animals and humans included studies of perforin expression and modulation in this lymphocyte subset. As NK cell activity is modified by their environment, we showed clinical stage–dependent impairment of their activity and in vitro effect of different sera, Th1 cytokines, and their combination in breast cancer, Hodgkin’s disease, and non-Hodgkin’s lymphoma patients, especially with respect to metabolic and cell membrane changes of peripheral blood lymphocytes evaluated by spontaneous release of the enzyme lactate dehydrogenase (LDH) that led to the correction of the LDH enzyme release assay for natural cytotoxicity. By long-term immuno-monitoring of patients with malignancies, we also showed the kinetics of NK cell modulation during chemo-immunotherapy. In our more recent studies, we give data of NK function and novel families of NK cell receptor expression in healthy individuals that may be of help in NK cell profiling, by giving referent values of basic and cytokine-induced expression of some NK cell receptors either in evaluation of disease or in immuno-monitoring during cytokine therapy of patients with malignancies. Moreover, we give novel aspects of modulation of NK cell activity by cytokines approved for immunotherapy, IFN and IL-2, in melanoma and other malignancies with respect to alterations in new activating (NKG2D and CD161) and inhibitory (CD158a and CD158b) receptor characteristics and signaling molecules in CD16- and CD56-defined NK cells and their small immunoregulatory and large cytotoxic subsets in peripheral blood and lymph nodes, as NK cell-mediated killing of tumor cells depends on the balance between stimulatory and inhibitory signaling.

Correlation of sera TNF-α with percentage of bone marrow plasma cells, LDH, β2-microglobulin, and clinical stage in multiple myeloma

Tumor necrosis factor-α (TNF-α) is important for function, differentiation, and transformation of B-lymphocytes in multiple myeloma (MM) but can also induce apoptosis of myeloma cells. Based on this opposite effect, it is very crucial to analyze the correlation of the serum level of TNF-α with clinical parameters of the patients. In this article, we analyzed 18 MM patients, 48% male and 52% female, with a mean age of 52 yr (range: 35–81 yr), clinical stage I in 21.4%, stage II in 26.4%, and stage III in 52.2% of patients. Patients with advanced clinical stage, presence of osteolysis, and elevated lactate dehydrogenase (LDH) had a significant difference (Mann-Whitney U-test, p<0.05) in the serum level of TNF-α in comparison with those in the early stage, without osteolysis, and normal LDH. The correlation of individual values of TNF-α with the percentage of plasma cells in the bone marrow, LDH, β2-microglobulin, fibrinogen, and sedimentation rate was significant (p<0.05). However, we have not found a significant correlation between TNF-α and concentration of hemoglobin, the number of white blood cells or platelets (p>0.05). We concluded that our data indicate determination of TNF-α as a good parameter for estimation of tumor mass presence, among individual patients with MM, and may by used for monitoring during application of different therapy protocols.

Estrogens: mechanisms of neuroprotective effects

Within the last few years, there has been a growing interest in the neuroprotective effects of estrogen and the possible beneficial effects of estrogen in neurodegenerative diseases such as stroke, Alzheimer’s disease, and Parkinson’s disease. The concept of neuroprotective effects of estrogen in women remains controversial because these effects may vary with the timing of treatment. Research increasingly suggests that changes in estrogen levels during aging may increase risk for Alzheimer’s disease, the most common type of dementia. This update reviews the newest information about estrogen and cognitive aging, including information regarding the role of bioavailable estrogen in older women and men.

Values of MMP-2 and MMP-9 in Tumor Tissue of Basal-Like Breast Cancer Patients

Gelatinase A (MMP-2) and gelatinase B (MMP-9) are proteolytic enzymes involved in process of tumor invasion, and they are considered as possible tumor markers in breast cancer patients. In this study, we measured activity of latent and active form of MMP-2 and MMP-9 in tumor and adjacent tissue of 60 breast cancer patients by SDS-PAGE zymography. The activity of both form of gelatinases significantly increased with each advancing clinical stage of disease. ProMMP-9 and aMMP-9 activity in tumor tissue shows a positive association with tumor size. Patients with lymph node involvement have higher proMMP-2, aMMP-2 and aMMP-9 activity than node negative patients. Steroid receptor-negative tumors had enhanced aMMP-2 and aMMP-9 activity. Patients with basal-like cancers had higher proMMP-2 tumor activity and aMMP-2 adjacent tissue activity compared to patients with luminal A tumors. Patients with negative hormone receptors are associated with increased activity of both form of gelatinases in adjacent tissue. Reported increased activity of MMP-2 in tumor and adjacent tissue of basal-like tumors implicates that MMP-2 might have a role in aggressive biology of basal-like cancers. Additional investigations regarding molecular pathways in adjacent tissue could give better insight into aggressive nature of basal-like carcinomas.

IL-2-mediated augmentation of NK-cell activity and activation antigen expression on NK- and T-cell subsets in patients with metastatic melanoma treated with interferon-α and DTIC

Considering that well-defined and comprehensive immunological monitoring is the basis for the evaluation of the obtained immunmodulatory effects, we evaluated NK-cell activity, the number of CD3+CD4+, CD3+CD8+ T cells and CD16+CD56+ NK cells, as well as the expression of activation antigens, CD69, CD38 and HLA-DR on CD56+ NK cells, CD8+ and CD3+ T cells, simultaneously with IL-2 and TNF-α production, during chemoimmunotherapy with dacarbazine (DTIC) and interferon-α (IFN-α) in 39 patients with metastatic melanoma. In the first cycle of therapy, there was a significant rise in NK-cell activity, CD4+ T helper cell number, CD4/CD8 T-cell ratio, and the expression of activation antigens CD69 and CD38, on NK and T cells, respectively. However, in the following cycles there was a significant increase only in activation antigens without an increase in the percent or activity of NK cells. The early, but transient, immunopotentiation, present only in the first cycle of combined DTIC and IFN-α therapy, suggests that, in spite of increased IL-2 level, associated with augmented NK-cell activity, this therapy has a limited effect probably owing to the adverse effect of persistently high level of TNF-α in metastatic disease.