Augumentation of natural killer activity with exogenous interleukins in patients with HIV and pulmonary tuberculosis coinfection

Natural Killer Repertoire Restoration in TB/HIV Co-Infected Individuals Experienced an Immune Reconstitution Syndrome (CAMELIA Trial, ANRS 12153)

IRIS is a common complication in HIV-infected patients treated for tuberculosis (TB) and cART. Our aim was to evaluate NK cell reconstitution in HIV-infected patients with TB-IRIS compared to those without IRIS. 147 HIV-infected patients with TB from the CAMELIA trial were enrolled. HIV+TB+ patients were followed for 32 weeks. The NK cell repertoire was assessed in whole blood at different time points. As CAMELIA has two arms (early and late cART initiation), we analysed them separately. At enrolment, individuals had low CD4 cell counts (27 cells/mm3) and high plasma viral loads (5.76 and 5.50 log/mL for IRIS and non-IRIS individuals, respectively). Thirty-seven people developed IRIS (in the early and late arms). In the early and late arms, we observed similar proportions of total NK and NK cell subsets in TB-IRIS and non-IRIS individuals during follow-up, except for the CD56dimCD16pos (both arms) and CD56dimCD16neg (late arm only) subsets, which were higher in TB-IRIS and non-IRIS individuals, respectively, after cART. Regarding the repertoire and markers of NK cells, significant differences (lower expression of NKp30, NKG2A (CD159a), NKG2D (CD314) were observed in TB-IRIS compared to non-IRIS individuals after the start of cART. In the late arm, some changes (increased expression of CD69, NKG2C, CD158i) were observed in TB-IRIS compared to non-IRIS individuals, but only before cART initiation (during TB treatment). KIR expression by NK cells (CD158a and CD158i) was similar in both groups. CD69 expression by NK cells decreased in all groups. Expression of the NCR repertoire (NKp30, NKp44, NKp46) has similar kinetics in TB-IRIS subjects compared to non-IRIS subjects regardless of the arm analysed. NK cell reconstitution appeared to be better in TB-IRIS subjects. Although NK cell reconstitution is impaired in HIV infection after cART, as previously reported, it does not appear to be affected by the development of IRIS in HIV and TB-infected individuals.

Interleukins 15 and 12 in combination expand the selective loss of natural killer T cells in HIV infection in vitro

The present study evaluated the frequency and receptor expression pattern of invariant natural killer T (iNKT) cells in human immunodeficiency virus (HIV)-infected individuals. Further, the effect of IL-15 + IL-12 stimulation on iNKT cells was also assessed. The study included 15 individuals each from normal healthy subjects, pulmonary tuberculosis patients, HIV-infected individuals, and patients with HIV and tuberculosis coinfection (HIV-TB). The frequency of iNKT cells and the expression of phenotype, cytotoxic and chemokine receptors were studied by flow cytometry. The number of iNKT cells was significantly depleted in HIV and HIV-TB patients, which upon IL-15 + IL-12 stimulation expanded in HIV. The constitutively expressed natural cytotoxicity receptor, NKp46 was increased in HIV and HIV-TB, which might be the host's response to HIV replication. The distinct expression patterns of chemokine and adhesion receptors suggest that iNKT subsets might traffic to different microenvironment and tissues. High expression of chemokine receptor CCR5 by most iNKT cells suggests that these cells might be more favorable targets of HIV infection. Our results show that IL-15 and IL-12 combination has the ability to expand the selective depletion of iNKT cells in vitro in HIV-infected individuals, but of limited value when coinfected with TB.

Effect of recombinant cytokines on the expression of natural killer cell receptors from patients with TB or/and HIV infection

BACKGROUND

NK cells express several specialized receptors through which they recognize and discriminate virally-infected/tumor cells efficiently from healthy cells and kill them. This ability to lyse is regulated by an array of inhibitory or activating receptors. The present study investigated the frequency of various NK receptors expressed by NK cell subsets from HIV-infected TB patients. The effect of IL-15+IL-12 stimulation on the expression of NK receptors was also studied.

METHODOLOGY/PRINCIPAL FINDINGS

The study included 15 individuals each from normal healthy subjects, pulmonary tuberculosis patients, HIV-infected individuals and patients with HIV and tuberculosis co-infection. The expression of NK cell receptors was analyzed on two NK cell subsets within the peripheral blood: CD16+CD3- and CD56+CD3- using flow cytometry. The expression of inhibitory receptors (CD158a, CD158b, KIRp70, CD85j and NKG2A) on NK subsets was increased in HIV, when compared to NHS. But the response in HIV-TB was not uniform. Stimulation with IL-15+IL-12 dropped (p<0.05) the expression of CD85j and NKG2A in HIV. The basal expression of natural cytotoxicity receptors (NKp30 and NKp46) on NK cell subsets was lowered (p<0.05) in HIV and HIV-TB as compared to NHS. However, the expression of NKp44 and NKG2D was elevated in HIV. Enhanced NKp46 and NKG2D expression was observed in HIV with IL-15+IL-12 stimulation. The coreceptor NKp80 was found to be expressed in higher numbers on NK subsets from HIV compared to NHS, which elevated with IL-15+IL-12 stimulation. The expression of NK receptors and response to stimulation was primarily on CD56+CD3- subset.

CONCLUSIONS/SIGNIFICANCE

IL-15+IL-12 has an immunomodulatory effect on NK cell subsets from HIV-infected individuals viz down-regulation of iNKRs, elevation of activatory receptors NKp46 and NKG2D, and induction of coreceptor NKp80. IL-15+IL-12 is not likely to be of value when co-infected with TB probably due to the influence of tuberculosis.

Innate immune natural killer cells and their role in HIV and SIV infection

The findings that early events during HIV-1 and SIV infection of Asian rhesus macaques dictate the levels of viremia and rate of disease progression prior to the establishment of mature and effective adaptive immune responses strongly suggest an important role for innate immune mechanisms. In addition, the fact that the major target of HIV and SIV during this period of acute infection is the gastrointestinal tissue suggests that whatever role the innate immune system plays must either directly and/or indirectly focus on the GI tract. The object of this article is to provide a general overview of the innate immune system with a focus on natural killer (NK) cells and their role in the pathogenesis of lentivirus infection. The studies summarized include our current understanding of the phenotypic heterogeneity, the putative functions ascribed to the subsets, the maturation/differentiation of NK cells, the mechanisms by which their function is mediated and regulated, the studies of these NK-cell subsets, with a focus on killer cell immunoglobulin-like receptors (KIRs) in nonhuman primates and humans, and finally, how HIV and SIV infection affects these NK cells in vivo. Clearly much has yet to be learnt on how the innate immune system influences the interaction between lentiviruses and the host within the GI tract, knowledge of which is reasoned to be critical for the formulation of effective vaccines against HIV-1.

Natural killer cells: versatile roles in autoimmune and infectious diseases

Natural killer (NK) cells are essential members of innate immunity and they rapidly respond to a variety of insults via cytokine secretion and cytolytic activity. Effector functions of NK cells form an important first line of innate immunity against viral, bacterial and parasitic infections, as well as an important bridge for the activation of adaptive immune responses. The control of NK-cell activation and killing is now understood to be a highly complex system of diverse inhibitory and activatory receptor-ligand interactions, sensing changes in MHC expression. NK cells have a functional role in innate immunity as the primary source of NK-cell-derived immunoregulatory cytokines, which have been identified in target organs of patients suffering from autoimmune diseases, and play a critical role in early defense against infectious agents. This review focuses on recent research of NK cells, summarizing their potential immunoregulatory role in modulating autoimmunity and infectious diseases.

Natural killer cell-mediated cytokine response among HIV-positive south Indians with pulmonary tuberculosis

Natural killer (NK) cells control Mycobacterium tuberculosis infection mainly through secreted cytokines. Cytokine dysregulation among HIV may cause rapid disease progression. Our objective was to examine whether impaired production of innate cytokines are responsible for cytokine dysregulation during HIV infection. The study included 30 subjects each of normal healthy subjects (NHS), pulmonary tuberculosis patients (TB), HIV-infected individuals (HIV), and HIV-TB co-infected patients (HIV-TB). Intracellular cytokine staining method was used to enumerate the cytokine-positive NK cells. Unlike NHS (100%), only 27% of HIV-TB and 57% of HIV infected patients have detectable plasma interleukin (IL)-15 levels that signify impaired rather than decreased IL-15 production. Basal type 1 cytokine (IL-2, interferon-gamma [IFN-gamma], and tumor necrosis factor-alpha [TNF-alpha])-secreting NK cells (NK1 cytokines) were decreased significantly (P < 0.05) in TB, HIV, and HIV-TB, when compared with NHS. Stimulation with M. tuberculosis H37Rv enhanced the NK1 cytokines in NHS (P < 0.05), but not in other groups. With IL-15+IL-12 stimulation, we found increased NK1 cytokines (IL-2 and IFN-gamma) in HIV (P < 0.05), but not in HIV-TB, when compared to unstimulated condition. Supplementing IL-15+IL-12 has potential in improving the frequency of NK1 cytokines for HIV, but not HIV-TB, suggesting that TB influences cytokine response during HIV infection.

Natural-killer cell-derived cytolytic molecules in HIV-associated pulmonary tuberculosis-role of exogenous interleukins

OBJECTIVE

The ability of NK cells to produce cytolytic molecules is impaired during HIV infection. The objective of the present study is to investigate whether impairment in production of innate cytokines in HIV-infected individuals is responsible for the defective NK cytolytic response.

MATERIALS AND METHODS

The study included 30 subjects each of normal healthy subjects, pulmonary tuberculosis patients, HIV-infected individuals, and patients with HIV and TB co-infection. Intracellular staining method was adopted to enumerate the NK cells positive for cytolytic molecules. Highest stimulation of cytolytic molecules was seen with IL-15 + IL-12 combination.

RESULTS

Stimulation with IL-15 + IL-12 showed an increased expression of perforin in NHS and HIV groups. Granzyme A was stimulated only in HIV, even with IL-15 + IL-12. Among the cytolytic molecules, maximal stimulation with IL-15 + IL-12 was seen for Granyme A and Granzyme B. Both the HIV and HIV-TB groups showed an increased response with IL-15 + IL-12 for granulysin.

CONCLUSION

Supplementing IL-15 + IL-12 in vitro increased the number of NK cells that are expressing cytolytic molecules in HIV-infected individuals but in HIV-TB, the critical cytolytic molecule, perforin is not apparent perhaps due to the influence of TB on HIV.

The modulation of immunological activities in human NK cells by extracts of ginkgo

OBJECTIVE

To investigate the association between extracts of ginkgo and the immune system by determining changes in natural killer (NK) cell activity and surface markers in human NK cells and by analyzing for surface markers.

METHODS

Natural killer cell activity was determined in peripheral blood samples of three subjects who received ginkgo daily (250 ml/day; (ginkgo concentration 40 mg/ml) for 14 days by the non-radioisotopic Europium (non-RI Eu) release assay. Peripheral blood samples were taken three times during the study period: before ginkgo sample ingestion, on day 7 after ginkgo ingestion, and on day 14 after ginkgo ingestion). The peripheral blood samples were also analyzed for surface markers (CD56, CD3, CD19, CD20, CD4, CD8) using a fluorescence-activated cell sorter (FACScalibur).

RESULTS

The non-RI Eu release assay revealed that the ingestion of ginkgo extracts elevated NK cell activity in the subjects, with the highest activity recorded following treatment with an extract at a concentration of 400-800 μg/ml. The analysis for surface markers using the FACScalibur showed that the expression of CD56 (NK cell surface marker) was elevated and the expression of CD19 had dropped in our subjects by day 14 of ginkgo ingestion. There was no significant difference in surface markers after 7 days of ginkgo ingestion.

CONCLUSION

Ginkgo extracts were found to affect immunological activities and surface markers (CD56) in human NK cells. Our results also reveal an optimal range of ginkgo concentration-from 400 to 800 μg/ml-within which its immunopotentiating activity is highest. It took at least 2 weeks to affect surface markers in human NK cells after ginkgo ingestion, and surface markers were not affected after 7 days of ginkgo ingestion.