Characterisation of follicular helper T (Tfh) cells in early treated HIV-infected children: relationship to immune activation and inflammation.

Simple item page
dc.contributor.advisorGlashoff, Richard Helmuthen_ZA
dc.contributor.authorOlifant, Paulinaen_ZA
dc.contributor.otherStellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Pathology: Division of Medical Microbiology.en_ZA
dc.date.accessioned2022-11-24T08:48:58Zen_ZA
dc.date.accessioned2023-01-16T12:50:35Zen_ZA
dc.date.available2022-11-24T08:48:58Zen_ZA
dc.date.available2023-01-16T12:50:35Zen_ZA
dc.date.issued2022-11-24en_ZA
dc.descriptionPathology: Medical Microbiologyen_ZA
dc.description.abstractENGLISH ABSTRACT: Background: South Africa has a high burden of Human Immunodefiency Virus (HIV) infection. Babies of HIV-positive pregnant women can become HIV-infected or exposed through vertical transmission. Follicular helper T (Tfh) cells have been of particular interest in HIV infection due to their preferential expansion, contribution to the HIV reservoir and dysregulation within HIV-infected individuals. The aim of this study was to investigate the Tfh cell population within children from the Children with HIV Early Antiretroviral Therapy (CHER) trial who started treatment within the first six months of life to determine whether the numbers of these cells is altered as compared to uninfected children and also whether persistent immune activation and inflammation in these children is associated with Tfh cell dysregulation. Methodology: This retrospective cross-sectional observational study consisted of three groups, i.e., early antiretroviral-treated HIT (HIV Infected Treated), HEU (HIV Exposed Uninfected) and HUU (HIV Uninfected Unexposed), of children. Cryopreserved peripheral mononuclear blood cells (PBMCs) were stained with an 11-colour antibody panel designed and optimised for phenotypic identification and quantification of T cell populations using flow cytometry. Tfh cells populations were characterised as CD4+CXCR5+PD-1+ with/without ICOS+. CD4, CD8 and Treg cells were defined as follicular/ follicular-homing based on CXCR5+ expression and activated based on CD38+ and/or CD69+ expression. Secondary data of clinical parameters and inflammatory cytokines for each group were evaluated. Statistical comparisons between groups were made using the Mann-Whitney test to identify significant differences. Significant correlations between Tfh cells and clinical parameters, other T cell populations and inflammatory cytokines were identified using Spearman’s rank order test. Results: Phenotypic results generally indicated significantly increased proportions of CD38+ subsets in HIT group and CD69+ subsets in HEU group. Although there was no significant difference in median CD4+CXCR5+PD-1+ Tfh cell percentage between groups, the ICOS-expressing subset namely CD4+CXCR5+PD-1+ICOS+ Tfh cells was significantly higher in the HIT (33.6% vs 19.2%; p = 0.016) and HEU group (31.6% vs 19.2%; p = 0.006) compared to the HUU group. In the HIT group, CD4+CXCR5+PD-1+ Tfh cells shared significant negative correlations with a majority of activated T cell subsets. A significant positive correlation between CD4+CXCR5+PD-1+ Tfh and CD8+PD-1+ Tc cells, general indicator of immune exhaustion, was demonstrated. Lastly, the HIT group showed the highest level of INF-α and hsCRP inflammatory cytokines and levels of IL-1β and hsCRP significantly correlated with CD4+CXCR5+PD-1+ICOS+ Tfh cells within this group. Conclusions: Overall levels of immune activation were significantly higher in HIT and HEU groups. Several activated T cell subsets inversely correlated with CD4+CXCR5+PD-1+ Tfh cells, suggesting high levels of immune activation can lead to decreased proportions of circulating Tfh cells. Even though no significant difference in the proportion of CD4+CXCR5+PD-1+ Tfh cells was found between groups, the ICOS+ subset was significantly expanded in HIT and HEU children in comparison to HUU children. The significant positive correlation between IL-1β and ICOS-expressing Tfh cells, within the entire study population and HIT group, suggested that increased inflammation resulted in an Tfh cell increase.en_ZA
dc.description.abstractAFRIKAANS OPSOMMING: Agtergrong: Suid Afrika het ‘n hoë las van Menslike Immuniteitsgebreksvirus (MIV) infeksie. Babas van MIV-positiewe vrouens kan MIV-besmet word of blootgestel word deur vertikale oordraging. Tfh selle is van besondere belang in MIV infeksie as gevolg van voorkeuruitbreiding, bydrae tot die MIV reservoir en wanregulering in persone wat MIV besmet is. Die doel van hierdie studie was om te ondersoek op die Tfh sel populasie, in kinders van die CHER studie wie ART begin het binne die eerste ses maande van lewe, se getalle veranderd is in vergelyking met kinders wat nie besmet is en ook of aanhoudende immuun aktivering en inflammasie in hierdie kinders geassosieer is met Tfh sel wanregulasie. Metodes: Hierdie retrospektiwe observasie deurneestudies bestaan uit drie groepe, dit is vroegtydige ART-behandelde MIV Infeksie (sogenaamde HIT), MIV blootgestel en nie geinfekteerd (sogenaamde HEU) en MIV nie geinfekteerd en nie blootgestel (sogenaamde HUU) kinders. Gekruipreserveerde PBMCs was verwerk met ‘n elf-kleur teenliggaam paneel wat ontwerp en optimiseer is vir fenotipiese identifikasie en kwantifisering van T cell populasie deur van vloeisitometrie gebruik te maak. Tfh sel populasie was gekenmerk as CD4+CXCR5+PD-1+ met/sonder ICOS+. CD4, CD8 and Treg selle was gedefineer as follikulêre/follikulêrmigrerende gebaseer op CXCR5 uitdrukking en aktivering gebaseer op CD38+ en/of CD69+ uitdrukking. Sekondere data van kliniese parameters en inflammatoriese sitokiene vir elke groep was geevalueer. Statistiese vergelykings tussen groepe was gemaak deur die Mann-Whitney toets te gebruik om betekenisvolle verskille te identifiseer. Die Spearman’s rank orde toets was gebruik om betekenisvolle vergelykings tussen Tfh selle en kliniese parameters, ander T sel populasies en inflammatoriese sitokiene te identifiseer. Resultate: Finotipiese resultate het in die algemeen ‘n aansienlikke verhoogde proporsie van CD38+ substel in die HIT groep en CD69+ substel in die HEU groep getoon. Alhoewel daar nie n aansienlikke verskil in mediaan CD4+CXCR5+PD-1+ Tfh selle persentasie tussen die groepe was nie, was die ICOS-uitdrukking substel naamlik CD4+CXCR5+PD-1+ICOS+ Tfh sel aansienlik hoër in die HIT groep (33.6% vs 19.2%; p = 0.016) en HEU groep (31.6% vs 19.2%; p = 0.006) in vergelyking met die HUU groep. In die HIT groep, CD4+CXCR5+PD-1+ Tfh selle het n aansienlike negatiewe korrelasie met die meerderheid geaktiveerde T cell subgroup. ‘n Aansienlikke positiewe korrelasie tussen CD4+CXCR5+PD-1+ Tfh selle en CD8+PD-1+ Tc selle, ‘n algemene aanwyser van immuun uitpitting, was gedemonstreer. Ten laaste, die HIT groep het die hoogste vlak van INF-α en hsCRP inflammatoriese sitokiene getoon en vlakke van IL-1β en hsCRP het negatief gekorreleer met CD4+CXCR5+PD-1+ICOS+ Tfh selle binne hierdie groep. Gevolgtrekking: Die algehele vlakke van immuun aktivering was beduidend hoër in die HIT en HEU groepe. Verskeie geaktiveerde T sel substelle het omgekeerd gekorreleer met CD4+CXCR5+PD-1+ Tfh selle, suggererend dat hoë vlakke van immuun aktivering kan lei tot n verlaagde proporsie van Tfh selle. Tfh selle word gereguleer deur CD8 T selle, Tfc en Tfr selle. Uitbreiding van CD8 T selle, CD38-geaktiveerde Tfc selle en Tfr selle in die HIT groep korreleer negatief met CD4+CXCR5+PD-1+ Tfh selle. Die negatiewe korrelasie tussen hsCRP en ICOS-uitdrukking Tfh selle, het verhoog in die HIT groep, wat suggereer dat inflammasie wat in HIT kinders voortgaan lei tot ‘n afname in Tfh selle. Hierdie stuudie demonstreer die uitbreiding van ICOS-uitdrukking Tfh selle (mees algemeen beskou as ware perifere Tfh selle) in vroeg behandelde HIT kinders wat aansienlik gereguleer was deur immuun aktivering en inflammasie.af_ZA
dc.description.versionMastersen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/126110en_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subjectImmunologyen_ZA
dc.subjecten_ZA
dc.titleCharacterisation of follicular helper T (Tfh) cells in early treated HIV-infected children: relationship to immune activation and inflammation.en_ZA
dc.typeThesisen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
olifant_follicular_2022.pdf
Size:
3.68 MB
Format:
Adobe Portable Document Format
Description:
Download
Collections
Masters Degrees (Medical Microbiology)