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Immunology

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Browsing Immunology by Author "Thobakgale, Christina Fanesa."

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    Protective HLA class I alleles : investigation of viral control and lack of control in chronic HIV-1 subtype C infection.
    (2015) Koofhethile, Catherine Kegakilwe.; Ndung'u, Peter Thumbi.; Thobakgale, Christina Fanesa.
    Abstract available in PDF file.
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    Sex differences in the Kinetics of immune reconstitution under antiretroviral therapy.
    (2017) Mazibuko, Noluthando Y.; Thobakgale, Christina Fanesa.; Ndung'u, Peter Thumbi.
    The human immunodeficiency virus type 1 (HIV-1) remains a global health threat and is increasingly becoming a female epidemic due to gender inequalities. The introduction of antiretroviral therapy (ART) has greatly increased the life span while reducing AIDS-related deaths in HIV-1-infected people. However, some patients experience adverse effects during ART due to an acute inflammatory response termed immune reconstitution inflammatory syndrome (IRIS), which is a paradoxical clinical worsening upon initiation of ART that is thought to be due to a hyperactive or uncontrolled immune restoration. Studies have shown that females infected with HIV-1 elicit a stronger immune response and faster disease progression compared to men with the same viral load. Given the above mentioned higher baseline levels of immune activation in HIV-1 infected females, we hypothesized that immune restoration during ART will have significant sex-based differential outcomes. The aim of this project was to understand the impact of immune reconstitution in HIV-1-infected men and women during ART by investigating antigen presenting cells (monocytes, myeloid dendritic cells (mDCs) and plasmacytoid dendritic (pDCs) cells) phenotype and function. In total, we investigated cryopreserved samples from eleven HIV-1-infected males and thirteen HIV-1-infected females from which peripheral blood mononuclear cells (PBMCs) and plasma samples were longitudinally collected at defined time points, including before the initiation of ART (TP01), after 1-4 months (TP02) and after 5-8 months of treatment initiation. Changes in toll-like receptor (TLR) responsiveness were analyzed following stimulation with the following toll-like receptor (TLR) ligands: TLR4 ligand Lipopolysaccharide, TLR7/8 ligand CL097, and the TLR9 ligand ODN2216/ CpG. Multiparameter flow cytometry was used to analyze the cytokine production upon TLR stimulation as well as the level of immune activation by analyzing phenotypic characteristics of antigen-presenting cells including monocytes subsets. In addition, multiplex analysis was used to determine levels of plasma pro-inflammatory cytokines (IFN-ɣ, IFN-α, IL-1β, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-13, TNF-α, IL-12p70, GM-CSF, MIP-1β and IP-10), in males and females at all time-points. Our results show that the expression of immune activation markers (measured by HLA-DR+ and CD38+ on T cells) did not significantly differ between males and females, although females showed elevated levels of both activated CD8+ and CD4+ T cells at baseline, the activation levels decreased upon ART initiation. Furthermore, our results demonstrated an increase in the proportion of classical monocytes (CD14++CD16-) in females compared to males at baseline (p=0.03). We did not observe any significant differences in the percentage of intermediate (CD14++CD16+) and non-classical monocytes (CD14+CD16++) between males and females at any time point analyzed. Similarly, no sex differences were evident after TLR ligand stimulation on monocytes in terms of cytokines measured (IFN-α, TNF-α, MIP-1β and IL-12). Interestingly, upon TLR9 stimulation, a significantly higher percentage of pDCs from females produced IFN-α (p=0.001, TP03), MIP-1β (p=0.001, at TP02) and TNF-α (p˂0.01, p˂0.001, TP02 and TP03 respectively) during ART compared to males. In addition, females had increased IFN-α (p=0.01) and TNF-α (p=0.004) production on pDCs during ART compared to baseline following TLR9 stimulation. Taken together, our data suggest sex-specific differences in the level of immune reconstitution during ART, as females show signs of elevated immune response and inflammation compared to males Therefore, these findings may provide a basis for future studies in larger cohorts aimed at adapting ART therapy based on sex differences in disease progression rates in men and women.