Blood dendritic cells in chronically HIV-1 infected individuals in South Africa: Phenotype, function and immune modulation

De Swardt, Dalene (2016-12)

Thesis (PhD)--Stellenbosch University, 2016

Thesis

ENGLISH ABSTRACT :HIV-1 infection detrimentally affects CD4 T lymphocytes as well as the blood plasmacytoid (pDC) and myeloid dendritic cell (mDC) compartment. DCs act as innate sensors and as initiators and directors of antigen-specific immune responses. Whereas, mDCs have the unique ability to prime naïve T-lymphocytes and activate adaptive immune responses, pDCs are primary producers of type 1 interferons (IFNs), playing a pivotal role in anti-viral immunity. In the current study both pDCs and mDCs from chronically HIV-1 infected South African individuals (on or naïve for ARV therapy) as well as with and without concurrent TB disease, were compared to matched uninfected controls. Similar to CD4 T lymphocytes, bothpDCs and mDCs, were significantly depleted during HIV-1 infection, (reduction of pDC, mDC and CD4 T lymphocyte was 63% (p 0.001), 80% (p 0.001) and 31% (p 0.01), respectively). In parallel, significantly higher levels of generalised immune activation and exhaustion (CD38+CD8+, PD-1+CD8+ and CD38+PD-1+CD8+ T lymphocytes) were observed. ARV treatment ( 1 year) did not result in DC number recovery despite a significant increase of CD4 T lymphocytes numbers (CD4 T lymphocyte number gain of 89% (p 0.01), it fell short of full recovery).TB co-infection did not exacerbate number loss. Phenotypic characterisation of DC populations in circulation during HIV-1 infection may indicate the underlying reasons for the loss from circulation. Phenotypic profiling by multiparameter flow cytometry included: markers of activation (CD86, CD80 and CD62L), maturation (CD83), apoptosis (TNF-R2, FAS, FASL and TRAIL R1-R4) and chemotaxis (CCR5, CCR7, CCR9 and CXCR6). HIV-infection was associated with a significantly higher percentage of CD86+mDCs which may be indicative of early maturation or transition to secondary lymphoid tissue. The frequency of the CD86+mDCs subset normalised upon ARV therapy. Also, HIV-1 infection influenced the distribution of TNF-R2+pDCs and TNF-R2+mDCs. Increased TNF-R2 expression in both subsets, may attest to enhanced survival function. Functionally, DCs of HIV-1 infected individuals were reactive to TLR-L stimulation and in some cases showed enhanced responses compared to uninfected individuals. A significantly higher frequency of TNF-R2+pDCs, IFN- +pDCs, and TNF +mDCs was observed in whole blood TLR cultures of HIV-1 infected individuals (TNF-R2+pDCs: LPS (p = 0.002) and R848 (p = 0.01), IFN- +pDCs: R848 (p = 0.04), TNF +mDCs: LPS (p = 0.003))s.In addition, whole blood TLR cultures of the ARV treated study group generally showed normalisation of the responses, however; in certain cases ARV therapy reduced responsiveness to levels significantly lower than the control study group (i.e.TNF-R2+pDCs and TNF-R2+mDCs in CpG ODN stimulation). In contrast, a significantly lower frequency of IL12p40+mDCs was observed during HIV-1 infection (p = 0.02). TLR-L cultures of the ARV treated study groups showed normalisation of IL12p40+mDCsfrequency. Notably, treatment with the immunomodulating peptide VIP induced a decline in IL12p40+mDCs to levels lower than the control study group.The frequency of TNF +pDCs in TLR-L whole blood cultures was similar between the healthy, untreated and treated HIV-1 infected study groups, however, significantly reduced frequencies were observed in these study groups upon VIP treatment. These data indicate unique phenotypic and functional changes in DC subsets in chronic HIV- 1 infection which may provide potential targets for immunotherapeutic intervention.

AFRIKAANSE OPSOMMING : Die CD4 T limfosiet asook die plasmasito ede (pDSe) en myelo ede dendritiese selle (mDSe) word nadelig geraak deur `n MIV-1 infeksie. Dendrietiese selle tree op as aangebore sensors en as inisieerders en reguleerders van antigeen-spesifieke immuun reaksies. mDSe het `n besonderse funksie om naïewe T limfosiete teinisieer en so die verworwe immune reaksies te aktiveer. pDSe is primêre produseerders van tipe 1 Interferon wat `n rol speel in anti-virale immuniteit. In die studie is beide die pDSe en mDSe van Suid- Afrikaners met chroniese MIV-1 infeksie (ARV en nie ARV gebruikers) met of sonder TB siekte vergelyk met ooreenstemmende MIV-1 negative kontroles. Soortgelyk aan CD4 T limfosiete, was beide die pDSe en mDSe beduidend verminder tydens `n MIV-1 infeksie (die verlaging in pDSe, mDSe en CD4 T limfosiete was onderskeidelik 63% (p 0.001), 80% (p 0.001) en 31% (p 0.01). Terselfdertyd is `n verhoogde vlak van algemene immuun aktivering en uitputting (CD38+CD8+, PD-1+CD8+T en CD38+PD-1+CD8+ T limfosiete) waargeneem. ARV behandeling ( 1 jaar) het nie gelei tot die herstel in DSe getalle alhoewel die studie `n beduidende vermeerdering in CD4 T limfosiete waargeneem het (CD4 T limfosiet vermeerdering van 89% (p 0.01), die verhogingwas nie voldoende nie). TB mede-infeksie het nie die vermindering van DSe vererger nie. Fenotipiese karakterising van die DS populasie in sirkulasie tydens MIV-1 infeksie mag die onderliggende rede vir die verlaging aandui. Fenotipiese profilering deur multi-parametriese vloeisitrometrie het ingesluit merkers van aktivering (CD86, CD80 en CD60L), maturasie (CD83), seldood (TNF-R2, FAS, FASL en TRAIL R1-R4) en chemotaksiese (CCR5, CCR7, CCR9 en CXCR6). MIV-1 infeksie was geassosieer met beduidende hoër persentasie van CD86+mDSe wat moontlik vroeë maturasie of transisie na die sekondêre limfoïedeweefsel aandui. Die frekwensie van die CD86+mDSe subpopulasie normaliseer tydens ARV terapie. MIV-1 infeksie het ook `n invloed op die distribusie van TNF-R2+pDSe en TNFR2 +mDSe gehad. Verhoogde TNF-R2 uitdrukking in beide DS populasies mag moontlik getuig van `n verhoogde oorlewings funksie.Op `n funksionele vlak het DSe van MIV-1 geinfekteerde individue reaksie tot TLR-L stimulasie getoon en in sommige gevalle was die reaksie hoër as in MIV-1 negatiewe individue. `n Beduidende hoër frekwensie van TNF-R2+pDSe, IFN- +pDSe, TNF +mDSe was waargeneem in heel bloed TLR-L kulture van MIV-1 geinfekteerde individue (TNF-R2+pDSe: LPS (p = 0.002) and R848 (p = 0.01), IFN- +pDSe: R848 (p = 0.04), TNF +mDSe: LPS (p = 0.003)) terwyl die heel bloed kulture van die ARV studie groep in die algemeen normalisering getoon het. In sekere gevalle het ARV terapie reaksies verlaag tot vlakke beduidend laer as die van die kontrole studie groep (i.e.TNF-R2+pDSe and TNF-R2+mDSe met CpG ODN stimulasie). In kontras, `n beduidende laer frekwensie van IL12p40+mDSe is opgemerk gedurende MIV-1 infeksie (p = 0.02). TLR-L kulture van die ARV studie groep het normalisering van die IL12p40+mDSe frekwensie getoon. Behandeling met die immunomodulerende VIP peptied het `n verlaging in IL12p40+mDSe vlakke geinduseer wat laer was as die van die kontrole groep. Normalisering van die IL12p40+mDSe vlakke is waargeeem in die TLR-L kulture van die ARV studie groep. Die frekwensie van TNF +pDSe in TLR-L heel bloed kulture was soortgelyk tussen die MIV-1 negatiewe, onbehandelde and behandelde MIV-1 geinfekteerde studie groepe. `n Beduidende verlaagde frekwensie was waargeneem in hierdie studie groepe tydens VIP behandeling. Hierdie data wys op unieke fenotipiese en funksionele veranderinge in die DS populasies tydens chroniese MIV-1 infeksie wat`n moontlik potensiele teiken vir immunoterapeutiese intervensie kan wees.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/100127
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