Browsing by Author "Altfeld, Marcus."

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Changes in natural killer cell activation and function during primary HIV-1 infection.
(Plos., 2012) Naranbhai, Vivek.; Altfeld, Marcus.; Abdool Karim, Salim Safurdeen.; Ndung'u, Peter Thumbi.; Abdool Karim, Quarraisha.; Carr, William Henry.
Background. Recent reports suggest that Natural Killer (NK) cells may modulate pathogenesis of primary HIV-1 infection. However, HIV dysregulates NK-cell responses. We dissected this bi-directional relationship to understand how HIV impacts NK-cell responses during primary HIV-1 infection. Methodology/Principal Findings. Paired samples from 41 high-risk, initially HIV-uninfected CAPRISA004 participants were analysed prior to HIV acquisition, and during viraemic primary HIV-1 infection. At the time of sampling post-infection five women were seronegative, 11 women were serodiscordant, and 25 women were seropositive by HIV-1 rapid immunoassay. Flow cytometry was used to measure NK and T-cell activation, NK-cell receptor expression, cytotoxic and cytokine-secretory functions, and trafficking marker expression (CCR7, α4β7). Non-parametric statistical tests were used. Both NK cells and T-cells were significantly activated following HIV acquisition (p = 0.03 and p<0.0001, respectively), but correlation between NK-cell and T-cell activation was uncoupled following infection (pre-infection r = 0.68;p<0.0001; post-infection, during primary infection r = 0.074;p = 0.09). Nonetheless, during primary infection NK-cell and T-cell activation correlated with HIV viral load (r = 0.32'p = 0.04 and r = 0.35;p = 0.02, respectively). The frequency of Killer Immunoglobulin-like Receptor-expressing (KIRpos) NK cells increased following HIV acquisition (p = 0.006), and KIRpos NK cells were less activated than KIRneg NK cells amongst individuals sampled while seronegative or serodiscordant (p = 0.001;p<0.0001 respectively). During HIV-1 infection, cytotoxic NK cell responses evaluated after IL-2 stimulation alone, or after co-culture with 721 cells, were impaired (p = 0.006 and p = 0.002, respectively). However, NK-cell IFN-y secretory function was not significantly altered. The frequency of CCR7+ NK cells was elevated during primary infection, particularly at early time-points (p<0.0001). Conclusions/Significance. Analyses of immune cells before and after HIV infection revealed an increase in both NK-cell activation and KIR expression, but reduced cytotoxicity during acute infection. The increase in frequency of NK cells able to traffic to lymph nodes following HIV infection suggests that these cells may play a role in events in secondary lymphoid tissue.
Distinct genital tract HIV-specific antibody profiles associated with Tenofovir gel.
(Nature., 2016) Archary, Derseree.; Seaton, Kelly E.; Passmore, Jo-Ann Shelley.; Werner, Lise.; Deal, Aaron W.; Dunphy, Laura J.; Arnold, Kelly B.; Yates, Nicole L.; Lauffenburger, Douglas A.; Bergin, Philip.; Liebenberg, Lenine Julie.; Samsunder, Natasha.; Mureithi, Marianne W.; Altfeld, Marcus.; Garrett, Nigel Joel.; Abdool Karim, Quarraisha.; Abdool Karim, Salim Safurdeen.; Morris, Lynn.; Tomaras, Georgia D.
Abstract available in PDF file.
Impact of blood processing variations on natural killer cell frequency, activation, chemokine receptor expression and function.
(Elsevier for Association of Medical Laboratory Immunologists., 2010) Naranbhai, Vivek.; Bartman, Pat.; Ndlovu, Dudu.; Ramkalawon, Pamela.; Ndung'u, Peter Thumbi.; Wilson, Douglas Paul Kinghurst.; Altfeld, Marcus.; Carr, William Henry.
Understanding the role of natural killer (NK) cells in human disease pathogenesis is crucial and necessitates study of patient samples directly ex vivo. Manipulation of whole blood by density gradient centrifugation or delays in sample processing due to shipping, however, may lead to artifactual changes in immune response measures. Here, we assessed the impact of density gradient centrifugation and delayed processing of both whole blood and peripheral blood mononuclear cells (PBMC) at multiple timepoints (2–24 h) on flow cytometric measures of NK cell frequency, activation status, chemokine receptor expression, and effector functions. We found that density gradient centrifugation activated the NK cells and modified the chemokine receptor expression. Delays in processing beyond 8 h activated NK cells in PBMC but not in whole blood. Likewise, processing delays decreased chemokine receptor (CCR4 and CCR7) expression in both PBMC and whole blood. Finally, delays in processing PBMC were associated with a decreased ability of NK cells to degranulate (as measured by CD107a expression) or secrete cytokines (IFN-γ and TNF-α). In summary, our findings suggest that density gradient centrifugation and delayed processing of PBMC can alter measures of clinically relevant NK cell characteristics including effector functions; and therefore should be taken into account in designing clinical research studies.
Innate immune activation enhances HIV acquisition in women, diminishing the effectiveness of tenofovir microbicide gel.
(Oxford University Press., 2011) Naranbhai, Vivek.; Abdool Karim, Salim Safurdeen.; Altfeld, Marcus.; Samsunder, Natasha.; Durgiah, Raveshni.; Sibeko, Sengeziwe.; Abdool Karim, Quarraisha.; Carr, William Henry.
The antiretroviral agent, tenofovir, formulated as a vaginal microbicide gel, reduces human immunodeficiency virus (HIV) acquisition by 39% in women. This study assessed the role of preexisting immune activation in HIV acquisition in women from the CAPRISA 004 trial, to identify potential strategies to increase the effectiveness of tenofovir gel. Systemic cytokine and cellular immune mediators (platelets and natural killer [NK] cells) were assessed in women at high risk for HIV assigned to either tenofovir or placebo gel in the CAPRISA 004 trial. Notwithstanding tenofovir gel use, women who acquired HIV had significantly higher systemic innate immune activation prior to infection than women who remained uninfected. Activation of both soluble (cytokine) and cellular (NK cells) immune mediators were associated with HIV acquisition, individually or in combination. Hence, an innate immune activation suppressant could be added to tenofovir gel as a potential combination gel strategy in developing the next generation of higher efficacy antiretroviral microbicides.
Interleukin 1-Beta (IL-1β) production by innate cells following TLR stimulation correlates with TB recurrence in art-treated HIV-infected patients.
(Wolters Kluwer Health., 2017) Thobakgale, Christina Fanesa.; Naidoo, Kewreshini Kasturi.; McKinnon, Lyle R.; Werner, Lise.; Samsunder, Natasha.; Abdool Karim, Salim Safurdeen.; Ndung'u, Peter Thumbi.; Altfeld, Marcus.; Naidoo, Kogieleum.
Abstract available.
Killer-cell Immunoglobulin-like Receptor (KIR) gene profiles modify HIV disease course, not HIV acquisition in South African women.
(BioMed Central., 2016) Naranbhai, Vivek.; de Assis Rosa, Debra.; Werner, Lise.; Moodley, Ramona.; Hong, Heather.; Kharsany, Ayesha Bibi Mahomed.; Mlisana, Koleka Patience.; Sibeko, Sengeziwe.; Garrett, Nigel Joel.; Chopera, Denis Rutendo.; Carr, William Henry.; Abdool Karim, Quarraisha.; Hill, Adrian V. S.; Abdool Karim, Salim Safurdeen.; Altfeld, Marcus.; Gray, Clive M.; Ndung'u, Peter Thumbi.
Abstract available in PDF file.
Natural killer cell function in women at high risk for HIV acquisition: insights from a microbicide trial.
(Lippincott Williams & Wilkins., 2012) Naranbhai, Vivek.; Altfeld, Marcus.; Abdool Karim, Quarraisha.; Ndung'u, Peter Thumbi.; Abdool Karim, Salim Safurdeen.; Carr, William Henry.
Objective: To assess the role of natural killer (NK) cells in HIV acquisition. Design: We conducted a nested case–control substudy to the Center for the AIDS Programme of Research in South Africa (CAPRISA004) tenofovir gel trial. Methods: Thirty women who acquired HIV infection (cases) and 30 women with high-risk sexual activity who remained HIV-negative (controls) were selected. Proliferation, degranulation and interferon-y (IFNy) secretion were measured by multiparametric flow cytometry after culture of recombinant human interleukin-2 (rhIL-2)-activated peripheral blood mononuclear cells with 721.221 cells or in-vitro HIV-infected, autologous CD4+ T-cell blasts. Relationships between pre-acquisition NK cell responses and HIV acquisition were modeled with logistic regression models. Results: NK cells from cases had lower IFNy responses to human leukocyte antigen-deficient 721.221 cells than controls (median %IFNyposNK cells: 13.7 vs. 21.6%, P=0.03). rhIL-2-activated NK cells from cases had responses to autologous HIV-infected target cells distinct from controls: cases had fewer proliferating and more frequent degranulating NK cells. NK cells from cases had significantly lower IFNy responses to in-vitro HIV-infected autologous T cells than controls even after adjusting for responses to uninfected blasts (median %IFNyposNK-cells: 0.53 vs. 2.09%, P=0.007). Responses to in-vitro HIV-infected autologous T cells were significantly lower in herpes simplex virus 2 (HSV-2)-infected women (P=0.003). IFNy NK cell responses to autologous HIV-infected cells were associated with lower risk of HIV acquisition (odds ratio adjusted for age, gel arm, HSV-2 and immune activation: 0.582, 95% confidence interval 0.347–0.977, P=0.04). Conclusion: At the time of exposure to HIV, women with impaired NK cell IFNy responses were more likely to acquire HIV infection. NK cells, as early responders to viral exposure, were associated with lower risk of HIV acquisition, independent of the intercalated effect of HSV-2 infection suppressing NK cell responses.
Preservation HIV-1–specific IFNg+ CD4+ T-Cell responses in breakthrough infections after exposure to tenofovir gel in the CAPRISA 004 microbicide trial.
(Lippincott Williams & Wilkins., 2011) Mureithi, Marianne W.; Poole, Danielle.; Naranbhai, Vivek.; Reddy, Shabashini.; Mkhwanazi, Nompumelelo Prudence.; Sibeko, Sengeziwe.; Werner, Lise.; Abdool Karim, Quarraisha.; Abdool Karim, Salim Safurdeen.; Ndung'u, Peter Thumbi.; Altfeld, Marcus.
Abstract: The Centre for the AIDS Program of Research in South Africa 004 trial demonstrated reduction of sexual HIV-1 acquisition in women using a vaginal microbicide containing tenofovir. A better understanding of the consequences of antiretroviral-containing microbicides for immune responses in individuals with intercurrent HIV-1 infection is needed for future trials combining the use of microbicides with HIV-1 vaccines. Investigation of immune responses in women who acquired HIV-1 although using tenofovir gel showed significantly higher (P = 0.01) Gag-specific IFNγ+ CD4+ T-cell responses. The use of tenofovir-containing gel around the time of infection can modulate HIV-1 immunity, and these immunological changes need to be considered in future trials combining vaccines and microbicides.
TRIM5α and TRIM22 are differentially regulated according to HIV-1 infection phase and compartment.
(American Society for Microbiology., 2014) Singh, Ravesh.; Patel, Vinod B.; Mureithi, Marianne W.; Naranbhai, Vivek.; Ramsuran, Duran.; Tulsi, Sahil.; Hiramen, Keshni.; Werner, Lise.; Mlisana, Koleka Patience.; Altfeld, Marcus.; Luban, Jeremy.; Kasprowicz, Victoria.; Dheda, Keertan.; Abdool Karim, Salim Safurdeen.; Ndung'u, Peter Thumbi.
The antiviral role of TRIM E3 ligases in vivo is not fully understood. To test the hypothesis that TRIM5α and TRIM22 have differential transcriptional regulation and distinct anti-HIV roles according to infection phase and compartment, we measured TRIM5α, TRIM22, and type I interferon (IFN-I)-inducible myxovirus resistance protein A (MxA) levels in peripheral blood mononuclear cells (PBMCs) during primary and chronic HIV-1 infection, with chronic infection samples being matched PBMCs and central nervous system (CNS)-derived cells. Associations with biomarkers of disease progression were explored. The impact of IFN-I, select proinflammatory cytokines, and HIV on TRIM E3 ligase-specific expression was investigated. PBMCs from individuals with primary and chronic HIV-1 infection had significantly higher levels of MxA and TRIM22 than did PBMCs from HIV-1-negative individuals (P < 0.05 for all comparisons). PBMCs from chronic infection had lower levels of TRIM5α than did PBMCs from primary infection or HIV-1-uninfected PBMCs (P = 0.0001 for both). In matched CNS-derived samples and PBMCs, higher levels of MxA (P = 0.001) and TRIM5α (P = 0.0001) in the CNS were noted. There was a negative correlation between TRIM22 levels in PBMCs and plasma viral load (r = -0.40; P = 0.04). In vitro, IFN-I and, rarely, proinflammatory cytokines induced TRIM5α and TRIM22 in a cell type-dependent manner, and the knockdown of either protein in CD4(+) lymphocytes resulted in increased HIV-1 infection. These data suggest that there are infection-phase-specific and anatomically compartmentalized differences in TRIM5α and TRIM22 regulation involving primarily IFN-I and specific cell types and indicate subtle differences in the antiviral roles and transcriptional regulation of TRIM E3 ligases in vivo.