Immune activation in HIV-positive patients on combined anti-retroviral treatment (cART) as a high risk group for the development of cardiovascular diseases

Teer, Eman Aboajla (2017-12)

Thesis (PhD)--Stellenbosch University, 2017.

Thesis

ENGLISH ABSTRACT: Although roll-out of combined anti-retroviral treatment (cART) has blunted HIV-AIDS onset, studies show increased development of cardio-metabolic complications in HIV-infected individuals. For this study we hypothesized that HIV-induced low-grade inflammation perturbs immune cell function/activation, thereby contributing to an increased risk for cardiovascular diseases (CVD) onset. Here we aimed to identify changes in monocyte and T cell subsets and determine its relationship to: (a) classical markers of HIV progression (CD4 count, viral load); (b) immune activation status; (c) endothelial dysfunction; and (d) traditional lipid profile and subclasses. Eighty participants were recruited from the Worcester Community Day Center (Worcester, Western Cape, South Africa): n=13 HIV-negative, n=67 HIV-positive. Recruits were divided as HIV-naïve and HIV-treated (on cART), and also groups based on CD4 count (control group, HIV-positive with CD4count > 500 cells/µL, CD4 count from 200–500 cells/µL and CD4 count < 200 cells/µL). Clinical histories and a validated lifestyle questionnaire were completed. Fasted blood was collected and used to assess monocyte subpopulation phenotype (non-classical, intermediate, classical) by flow cytometry together with tissue factor (a marker for thrombus formation) and CD38 (a marker for immune activation) expression on monocyte and T cell subsets (CD4, CD8). Classical regulatory T cells (CD4+CD25++FOXP3+) with activation markers (glycoprotein A repetitions predominant [GARP] and special AT-rich sequence binding protein 1 [SATB-1]) were also evaluated together with an assessment of endothelial function (flow-mediated dilatation). C-reactive protein levels together with the traditional lipid profile were also evaluated. In addition, an assessment of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) subclasses was also completed. Our data revealed a robust increase in inflammation/immune activation and coagulation markers on CD8+ and CD4+ T cell populations, respectively (CD8+CD142+ [P = 0.01] and CD4+CD142+ [P = 0.0003]). Increased co-expression of inflammation and coagulation markers were also observed on both CD8+ and CD4+ T cells (CD8+142+CD38+ [P = 0.0001] and CD4+142+38+ [< 0.0001]). In addition, we found an expansion of both non-classical (P = 0.0001) and intermediate monocytes (P = 0.05) that were highly correlated with immune activation, coagulation and HIV disease progression markers. There was also an expansion of CD4+FOXP3+ regulatory T cells (P = 0.0005), together with higher levels of GARP (P = 0.001) and SATB-1 (P = 0.04) (especially in patients with relatively low CD4 counts). The lipid profile data revealed interesting changes, i.e. a significant decrease during early HIV-infection but with substantial increase after cART initiation. In addition, we also found significant changes in HDL and LDL subclasses. The most novel findings of this study are: a) the identification of a unique coagulation marker (CD142) expressed on CD8 and CD4 T cells and its relatively early expression in HIV-infected individuals (treatment naïve). CD142 is also co-expressed with immune activation and strongly correlates with disease progression markers; b) changes in lipid subclasses that significantly correlate to HIV immunological markers despite a decrease in terms of the traditional lipid profile expected. Such subclass changes may also be a driver for CVD onset, although further research is needed to pursue this question; and c) upregulation of both antiinflammatory GARP and pro-inflammatory SATB-1 in regulatory T cells in HIV-treated individuals (with immune dysregulation) altering regulatory T cell function and also potentially contributing to CVD onset. Thus we propose that clinicians could be aware of immune activation and coagulation with HIV infection (even at relatively early stages of disease progression) as monitoring and control of these factors could result in improved healthcare and the long-term well-being for such patients.

AFRIKAANSE OPSOMMING: Hoewel die uitrol van gekombineerde anti-retrovirale behandeling (kARK) die aanvang van MIV-VIGS laat daal het, toon studies die verhoogde ontwikkeling van kardio-metaboliese komplikasies in MIVgeïnfekteerde individue. In hierdie projek word daar vermoed dat MIV-geïnduseerde laegraadse inflammasie immuunsel funksie / aktivering ontwrig en sodoende bydra tot 'n verhoogde risiko vir kardiovaskulêre siektes (KVS). Die studie het die volgende doelwitte: identifiseer veranderinge in monosiet en regulerende T-sel subtipes en hul verhouding tot: (a) klassieke merkers van MIV vordering (CD4-telling, virale lading); (b) immuun aktivering status en; (c) endoteel wanfunksie. Tagtig deelnemers is gewerf (Worcester CDC [Wes-Kaap]): n=13 MIV-negatief, n=67 MIV-positief (gegroepeer as MIV-naïewe, MIV-behandeling op kARK), asook groepe op grond van CD4-telling (kontrole groep, MIV-positief met CD4-telling > 500 selle/μL, CD4-telling 200-500 selle/μL en CD4-telling < 200 selle/μL) Kliniese geskiedenis is aangeteken en 'n gevestigde leefstyl vraelys is voltooi. Bloed monsters, geneem tydens ‘n tydeperk van vas, is ingesamel en gebruik om monosiet subpopulasie (nie-klassieke, intermediêre, klassieke) fenotipe deur vloeisitometrie te evalueer tesame met weefsel faktor (merker: trombus ontwikkeling) en CD38 (merker: immuun aktivering) uitdrukking op monosiet subtipes en CD8 T-selle. Klassieke regulerende T-selle (CD4+CD25++Foxp3+) met aktivering merkers (GARP en SATB-1) is ook beoordeel tesame met endoteel funksie toets (vloei-bemiddelde ontsluiting). CRP met tradisionele lipiedprofiel is ook geëvalueer en verdere evaluering van HDL met LDL subklasse is uitgevoer. Die data het 'n beduidende toename in inflammasie / immuun aktivering (P <0.0001) en stolling merkers CD8+CD142+ (P = 0,01) getoon. 'n Hoë mede-uitdrukking van inflammasie en stolling merkers CD8+42+CD38+ is ook waargeneem (P = 0,0001). Die resultate het opregulering van beide nie-klassieke monosiete (P = 0,0001) en intermediêre monosiete (P = 0,05) getoon, en hierdie subtipes het hoogs gekorreleer met immuun aktivering en stolling en MIV siekte progressie merker. Daar was ook 'n uitbreiding van CD4+Foxp3+ T-selle (P = 0,0005), tesame met hoër vlakke van bykomende T-reg merkers GARP (P = 0,001) en SATB-1 (P = 0,04) (veral in pasiënte met relatiewe lae CD4 tellings). 'n Beduidende afname in lipiedprofiel vroeg na MIV-infeksie, met ‘n aansienlike toename na kARK inisiasie, saam met 'n beduidende verandering in HDL en LDL subklasse, is ook waargeneem. Die mees beduidende nuwe bevindinge van hierdie studie is: a) die identifisering van 'n unieke koagulasie merker (CD142) wat op CD8 T-selle uitgedruk word en sy relatiewe vroeë uitdrukking in MIV-geïnfekteerde individue (naïewe). Verder het ons gevind dat dit ‘n mede-uitdrukking met immuun aktivering deel en sterk ooreenstem met die siekte merkers; b) veranderinge in lipied subklasse wat beduidend korreleer met MIV immunologiese merkers ten spyte van 'n afname in terme van die verwagte tradisionele lipiedprofiel. Sulke subklas veranderinge kan dalk ook die aanvang van KVS bevorder, alhoewel verdere navorsing benodig word om hierdie interessante idee aan te spreek; en c) opregulering van beide anti-inflammatoriese GARP en pro-inflammatoriese SATB-1 in Treg selle in MIV-behandelde individue (met immuun wanregulering) kan die balaans van Treg sel funksie ontwrig en ook potensiëel bydra tot die aanvang van KVS. Ons stel voor dat dokters moet bewus wees van immuun aktivering en stolling met MIV-infeksie (selfs by relatiewe vroeë stadiums van die siekte) aangesien dit sal lei tot verbeterde gesondheidsorg en welsyn vir sulke pasiënte.

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