Qual o papel das células natural killer na infeção por VIH-SIDA

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

Desenvolvimento de melanoma em animais selecionados pela intensidade de resposta inflamatória aguda (Airmax/Airmin): caracterização das células Natural Killer, NKT, Treg e perfil de citocinas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Valor prognóstico de células TCD8+ E natural killer em carcinoma epidermóide oral e orofaringeano tratado com radioterapia e quimioterapia

The most common malignant neoplasm of the oral cavity and oropharynx are squamous cell carcinoma. Injuries to the same stage and subjected to the same treatment protocol have sometimes different evolutionary courses. The scope of this study was to investigate, through a retrospective cohort, associations between the number of CD8 + T cells and natural killer, identified immunohistochemically in the inflammatory infiltrate in a series of cases of oral squamous cell carcinoma and orofaringeano, and the level of tumor response to radiotherapy and chemotherapy, overall survival and relapse-free survival of patients. We identified 54 patients with unresectable disease were treated exclusively with radiotherapy and chemotherapy. The median follow-up was 22 months. The sample was characterized by the predominance of male subjects, median age 60 years, all were smokers. The most frequent site was the tongue and 81.5% were in stage IV. Patients with disease in the oral cavity had a worse response to treatment (p = 0.006), worse relapse-free survival (p = 0.007), worse overall survival (p = 0.007). The advanced T stage was shown a negative prognostic factor (p= 0.006) for the clinical treatment response made. Immunohistochemistry was performed to select CD8 + cells (anti-CD8) and NK cells (anti-CD57). Lymphocytes positive and negative markings were counted using the program ImageJ ®. Two groups were created for each marking evaluated: Group I patients with more than 50% cells positive, Group II: less than 50% of labeled cells. For CD8 + cells detected in 38 (70.3%) of Group I were CD8 + and 16 (29.7%) Group II CD8 +. For NK cells, 26 (48.15%) Group I NK and 28 (51.85%) Group II NK. Regarding the clinical response to treatment, we observed that 39% of patients achieved a complete response and 25.9% remained without recurrence at the end of follow-up. These results were better in Group I CD8 + (p = 0.2). Identified that 72.2% of patients progressed to death, this finding had no association with the immunohistochemical data. There was no statistically significant differences between the number of CD8 + and NK cells and the ability of tumor response to radiotherapy and chemotherapy, or with overall survival and relapse-free survival of patients. However, especially in relation to a learned response, we found that this group of patients with advanced disease have a low count of CD8 + T cells active. Believing in the role that the immune response plays in the local fight against neoplastic cells, however, our results do not support the use of quantitative analysis of CD8 + T cells and NK cells as a prognostic factors for oral squamous cell carcinoma and oropharynx

Natural killer cell activity in experimental paracoccidioidomycosis of the Syrian hamster

Com o objetivo de avaliar a atividade de células natural killer na paracoccidioidomicose experimental do hamster, 80 hamsters foram infectados por via intratesticular com Paracoccidioides brasiliensis e sacrificados após 24h, 48h, 96h, 1, 2, 4, 8 e 11 semanas de infecção. Como controle foram avaliados 40 hamsters normais, não infectados. Os animais foram submetidos ao estudo da atividade citotóxica de células NK pela técnica de single-cell assay e da resposta imune humoral pelas técnicas de imunodifusão dupla e Elisa. A produção do fator inibidor da migração de macrófagos em presença de Phytohemaglutinina e antígeno de P. brasiliensis e a histopatologia das lesões foram estudadas após 1,4, 8e 11 semanas de infecção. Os animais infectados, quando comparados aos controles, apresentaram níveis de atividade NK significativamente elevados durante as 4 primeiras semanas de infecção, havendo diminuição dessa atividade a partir da 8ª semana. Foi observada correlação inversa entre atividade NK e níveis de anticorpos específicos e, associação entre diminuição da atividade NK, depressão de resposta imune celular e aumento da extensão das lesões histopatológicas. Os resultados sugerem que após ativação inicial, as células NK são incapazes de controlar a disseminação do fungo pelos tecidos. A depressão da atividade NK na fase tardia da infecção parece estar relacionada com os distúrbios imunorregulatórios associados à paracoccidioidomicose.

Target Cell Topography and Cytoskeletal Reorganization in Natural Killer Cell Activity

The immune system has to recognize and destroy abnormal or infected cells to maintain homeostasis. Natural killer (NK) cells directly recognize and kill transformed or virus-infected cells without prior sensitization. We have studied both virus-infected and tumor cells in order to identify the target structures involved in triggering NK activity. Mouse/human cell hybrids containing various human chromosomes were used as targets. The human chromosome responsible for activating NK cell killing was identified to chromosome number 6. The results suggest that activated NK cells recognize ligands that are encoded on human chromosome 6. We showed that the ligand on the target cell side was intercellular adhesion molecule 2 (ICAM-2). There was no difference in the level of expression of ICAM-2, however, but a drastic difference was seen in the distribution of the molecule: ICAM-2 was evenly distributed on the surface of the NK-resistant cells, but almost totally redistributed to the tip of uropods, bud-like extensions, which were absent from the parental cells. Interestingly, the gene coding for cytoskeletal linker protein ezrin has been localized to human chromosome 6, and there was a colocalization of ezrin and ICAM-2 in the uropods. Furthermore, the transfected human ezrin into NK cell-resistant cells induced uropod formation, ICAM-2 and ezrin redistribution to newly formed uropods, and sensitized target cells to NK cell killing. These data reveal a novel form of NK cell recognition: target structures are already present on normal cells; they become detectable only after abnormal redistribution into hot spots on the target cell membrane. NK cells are central players in the defence against virus infections. They inhibit the spread of infection, allowing time for specific immune responses to develop. The virus-proteins that directly activate human NK cell killing are largely unknown. We studied the sensitivity of virus-specific early proteins of Semliki Forest virus (SFV) to NK killing. The viral non-structural proteins (nsP1-4) translated early in the virus cycle were transfected in NK-resistant cells. Viral early gene nsP1 alone efficiently sensitized target cells to NK activity, and the tight membrane association of nsP1 seems to be critical in the triggering of NK killing. NsP1 protein colocalized with (redistributed) ezrin in filopodia-like structures to which the NK cells were bound. The results suggest that also in viral infections NK cells react to rapid changes in membrane topography. Based on the results of this thesis, a new model of target cell recognition of NK cells can be suggested: reorganization of the cytoskeleton induces alterations in cell surface topography, and this new pattern of surface molecules is recognized as "altered-self".

Augmentation of murine natural killer cell and antibody dependent cellular cytotoxicity activities by phyllanthus emblica, a new immunomodulator

When administered orally, Phyllanthus emblica, an excellent source of vitamin C (ascorbate), has been found to enhance natural killer (NK) cell activity and antibody dependent cellular cytotoxicity (ADCC) in syngeneic BALB/c mice, bearing Dalton's lymphoma ascites (DLA) tumor. P. emblica elicited a 2-fold increase in splenic NK cell activity on day 3 post tumor inoculation. Enhanced activity was highly significant on days 3, 5, 7 and 9 after tumor inoculation with respect to the untreated tumor bearing control. A significant enhancement in ADCC was documented on days 3, 7, 9, 11 and 13 in drug treated mice as compared to the control. An increase in life span (ILS) of 35% was recorded in tumor bearing mice treated with P. emblica. This increased survival was completely abrogated when NK cell and killer (K) cell activities were depleted either by cyclophosphamide or anti-asialo-GM, antibody treatment. These results indicate: (a) an absolute requirement for a functional NK cell or K cell population in order that P. emblica can exert its effect on tumor bearing animals, and (b) the antitumor activity of P. emblica is mediated primarily through the ability of the drug to augment natural cell mediated cytotoxicity.

A single amino acid defines cross-species reactivity of tree shrew (Tupaia belangeri) CD1d to human invariant natural killer T (iNKT) cells

P>The non-classical major histocompatibility complex (MHC) class I molecule CD1d presents lipid antigens to invariant natural killer T (iNKT) cells, which are an important part of the innate immune system. CD1d/iNKT systems are highly conserved in evoluti

Mouse Uterine Natural Killer Cell Functions During Early Pregnancy

Early pregnancy is characterized by complex interactions between blood vessels, leukocytes, and conceptus-derived trophoblasts within the gestational uterus. Uterine Natural Killer (uNK) cells become the most abundant leukocyte during decidualization and produce a wide array of angiogenic factors, yet little is known regarding their early pregnancy functions. To characterize the role(s) of uNK cells, whole mount in situ immunohistochemistry of live early implant sites was performed. A timecourse examination of murine early pregnancy (virgin, and gd4.5-9.5) implantation sites was performed. Comparison of Gd6.5, 8.5 and 9.5 implant sites from BALB/c+/+ controls (BALB/c) and BALB/c-Rag2-/-Il2rg-/- (alymphoid) identified anomalies that result from the absence of lymphocytes. In alymphoid decidua basalis, mesometrial angiogenesis was widespread but pruning of nascent vessels within alymphoid decidua basalis was deficient. As early gestation progressed, vessels of alymphoid decidua basalis showed no evidence for remodeling. Alymphoid implantation sites showed ~24h delay in uterine lumen closure and embryonic development. To determine if uNK cells would normalize the anomalies observed in alymphoid implantation sites, adoptive cell transfer of NK+ B- T- marrow to alymphoid mice was performed. All of the above anomalies were reversed by adoptive transfer of NK+B-T- marrow. My results suggest that uNK cells support vascular growth and development which ensures the decidua can support the growing conceptus early in pregnancy prior to formation and function of the placenta. Human decidual NK cells may fill similar roles and be important targets for strategies designed to correct intra-uterine growth restriction.

Defects in acute responses to TLR4 in Btk-deficient mice result in impaired dendritic cell-induced IFN-γ production by natural killer cells

This study defines a critical role for Btk in regulating TLR4-induced crosstalk between antigen presenting cells (APCs) and natural killer (NK) cells. Reduced levels of IL-12, IL-18 and IFN-? were observed in Btk-deficient mice and ex vivo generated macrophages and dendritic cells (DCs) following acute LPS administration, whilst enhanced IL-10 production was observed. In addition, upregulation of activation markers and antigen presentation molecules on APCs was also impaired in the absence of Btk. APCs, by virtue of their ability to produce IL-12 and IL-18, are strong inducers of NK-derived IFN-?. Co-culture experiments demonstrate that Btk-deficient DCs were unable to drive wild-type or Btk-deficient NK cells to induce IFN-? production, whereas these responses could be restored by exogenous administration of IL-12 and IL-18. Thus Btk is a critical regulator of APC-induced NK cell activation by virtue of its ability to regulate IL-12 and IL-18 production in response to acute LPS administration.

Changes in natural killer cells, the CD57CD8 subset, and related cytokines in healthy aging

Aging has been shown to be accompanied by various changes in the lymphocyte subset distribution in the elderly. We have investigated more fully, and in a large number of subjects, age-related changes within several subpopulations bearing natural killer (NK) cell-associated surface antigens and changes in several cytokines involved in NK cell expansion. A total of 229 healthy subjects from all decades of life from 20 to 98 years of age was included in this cross-sectional study. A significant increase with age was found in both the absolute counts and the proportions of CD3-CD(16+56)+, CD3+CD(16+56)+, CD57+CD8+, CD57+CD8(low)+, and CD57+CD8- cells, whereas the CD57+CD8(high)+ subset, which may represent the cytolytic T cell population more precisely, showed less change with age. Some evidence is also provided to suggest that these expanded NK cell populations are in an activated state. Soluble IL-2 receptor levels were also found to increase significantly with age and correlated with certain NK cell subsets. Although the functions of some of these subsets remain to be elucidated, their expansion in the elderly may represent a remodeling of the immune system with increasing age, with an increase in non-MHC-restricted cells perhaps compensating for the previously reported decline in T and B cells in the elderly. Alternatively, increased numbers of these cells may be a direct result of cytokine dysregulation or increased antigenic or neoplastic cell challenge.

Killer immunoglobulin-like Receptors (KIR) haplogroups A and B track with Natural Killer Cells and Cytokine Profile in Aged Subjects: Observations from Octo/Nonagenarians in the Belfast Elderly Longitudinal Free-living Aging STudy (BELFAST)

Background: Natural Killer Cells (NK) play an important role in detection and elimination of virus-infected, damaged or cancer cells. NK cell function is guided by expression of Killer Immunoglobulin-like Receptors (KIRs) and contributed to by the cytokine milieu. KIR molecules are grouped on NK cells into stimulatory and inhibitory KIR haplotypes A and B, through which NKs sense and tolerate HLA self-antigens or up-regulate the NK-cytotoxic response to cells with altered HLA self-antigens, damaged by viruses or tumours. We have previously described increased numbers of NK and NK-related subsets in association with sIL-2R cytokine serum levels in BELFAST octo/nonagenarians. We hypothesised that changes in KIR A and B haplotype gene frequencies could explain the increased cytokine profiles and NK compartments previously described in Belfast Elderly Longitudinal Free-living Aging STudy (BELFAST) octo/nonagenarians, who show evidence of ageing well.

Results: In the BELFAST study, 24% of octo/nonagenarians carried the KIR A haplotype and 76% KIR B haplotype with no differences for KIR A haplogroup frequency between male or female subjects (23% v 24%; p=0.88) or for KIR B haplogroup (77% v 76%; p=0.99). Octo/nonagenarian KIR A haplotype carriers showed increased NK numbers and percentage compared to Group B KIR subjects (p=0.003; p=0.016 respectively). There were no KIR A/ B haplogroup-associated changes for related CD57+CD8 (high or low) subsets. Using logistic regression, KIR B carriers were predicted to have higher IL-12 cytokine levels compared to KIR A carriers by about 3% (OR 1.03, confidence limits CI 0.99–1.09; p=0.027) and 14% higher levels for TGF-ß (active), a cytokine with an anti-inflammatory role, (OR 1.14, confidence limits CI 0.99–1.09; p=0.002).

Conclusion: In this observational study, BELFAST octo/nonagenarians carrying KIR A haplotype showed higher NK cell numbers and percentage compared to KIR B carriers. Conversely, KIR B haplotype carriers, with genes encoding for activating KIRs, showed a tendency for higher serum pro-inflammatory cytokines compared to KIR A carriers. While the findings in this study should be considered exploratory they may serve to stimulate debate about the immune signatures of those who appear to age slowly and who represent a model for good quality survivor-hood.© 2013 Rea et al.; licensee BioMed Central Ltd.

Immunoselection of breast and ovarian cancer cells with trastuzumab and natural killer cells:selective escape of CD44high/CD24low/HER2low breast cancer stem cells

Although trastuzumab (Herceptin) has substantially improved the overall survival of patients with mammary carcinomas, even initially well-responding tumors often become resistant. Because natural killer (NK) cell-mediated antibody-dependent cell-mediated cytotoxicity (ADCC) is thought to contribute to the therapeutic effects of trastuzumab, we have established a cell culture system to select for ADCC-resistant SK-OV-3 ovarian cancer and MCF7 mammary carcinoma cells. Ovarian cancer cells down-regulated HER2 expression, resulting in a more resistant phenotype. MCF7 breast cancer cells, however, failed to develop resistance in vitro. Instead, treatment with trastuzumab and polyclonal NK cells resulted in the preferential survival of individual sphere-forming cells that displayed a CD44(high)CD24(low) "cancer stem cell-like" phenotype and expressed significantly less HER2 compared with non-stem cells. Likewise, the CD44(high)CD24(low) population was also found to be more immunoresistant in SK-BR3, MDA-MB231, and BT474 breast cancer cell lines. When immunoselected MCF7 cells were then re-expanded, they mostly lost the observed phenotype to regenerate a tumor cell culture that displayed the initial HER2 surface expression and ADCC-susceptibility, but was enriched in CD44(high)CD24(low) cancer stem cells. This translated into increased clonogenicity in vitro and tumorigenicity in vivo. Thus, we provide evidence that the induction of ADCC by trastuzumab and NK cells may spare the actual tumor-initiating cells, which could explain clinical relapse and progress. Moreover, our observation that the "relapsed" in vitro cultures show practically identical HER2 surface expression and susceptibility toward ADCC suggests that the administration of trastuzumab beyond relapse might be considered, especially when combined with an immune-stimulatory treatment that targets the escape variants.

Natural Killer Cell-like signature observed in locally advanced rectal cancer after neoadjuvant chemoradiotherapy in a tumour regression grade dependent manner

Background: Around 10-15% of patients with locally advanced rectal cancer (LARC) undergo a pathologically complete response (TRG4) to neoadjuvant chemoradiotherapy; the rest of patients exhibit a spectrum of tumour regression (TRG1-3). Understanding therapy-related genomic alterations may help us to identify underlying biology or novel targets associated with response that could increase the efficacy of therapy in patients that do not benefit from the current standard of care.
Methods: 48 FFPE rectal cancer biopsies and matched resections were analysed using the WG-DASL HumanHT-12_v4 Beadchip array on the illumina iScan. Bioinformatic analysis was conducted in Partek genomics suite and R studio. Limma and glmnet packages were used to identify genes differentially expressed between tumour regression grades. Validation of microarray results will be carried out using IHC, RNAscope and RT-PCR.
Results: Immune response genes were observed from supervised analysis of the biopsies which may have predictive value. Differential gene expression from the resections as well as pre and post therapy analysis revealed induction of genes in a tumour regression dependent manner. Pathway mapping and Gene Ontology analysis of these genes suggested antigen processing and natural killer mediated cytotoxicity respectively. The natural killer-like gene signature was switched off in non-responders and on in the responders. IHC has confirmed the presence of Natural killer cells through CD56+ staining.
Conclusion: Identification of NK cell genes and CD56+ cells in patients responding to neoadjuvant chemoradiotherapy warrants further investigation into their association with tumour regression grade in LARC. NK cells are known to lyse malignant cells and determining whether their presence is a cause or consequence of response is crucial. Interrogation of the cytokines upregulated in our NK-like signature will help guide future in vitro models.

PRDM1 is a tumor suppressor gene in natural killer cell malignancies.

Natural killer cell lymphoma (NKCL) constitutes a rare and aggressive form of non-Hodgkin lymphoma, and there is little insight into its pathogenesis. Here we show that PRDM1 is a tumor suppressor gene in NKCLs that is inactivated by a combination of monoallelic deletion and promoter CpG island hypermethylation. We observed monoallelic deletion of PRDM1 loci in 8 of 18 (44%) NKCL cases. The other allele showed significant promoter methylation in 12 of 17 (71%) cases. In support of its role as a tumor suppressor gene, the reconstitution of PRDM1 in PRDM1-null NK cell lines led to G2/M cell cycle arrest, increased apoptosis, and a strong negative selection pressure with progressive elimination of PRDM1-expressing cells, which was enhanced when IL-2 concentration is limiting. We observed a progressive increase in PRDM1 expression-in particular, PRDM1α-in normal NK cells in response to IL-2 and in normal NK cells activated with an engineered NK cell target, K562-Cl9-mb21, suggesting its role in NK cell homeostasis. In support of this role, knockdown of PRDM1 by shRNA in normal NK cells resulted in the positive selection of these cells. We identified MYC and 4-1BBL as targets of PRDM1 in NK cells. Disruption of homeostatic control by PRDM1 may be an important pathogenetic mechanism for NKCL.