Toll-like receptor expression and responsiveness are increased in viraemic HIV-1 infection.
OBJECTIVE
Toll-like receptors (TLR) are important in pathogen recognition and may play a role in HIV disease. We evaluated the effect of chronic untreated and treated HIV-1 infection on systemic TLR expression and TLR signalling.


METHODS
Two hundred HIV-infected and uninfected women from a Kenya cohort participated in the studies. TLR1 to TLR10 messenger RNA expression was determined by quantitative reverse transcriptase polymerase chain reaction in peripheral blood mononuclear cells (PBMC). TLR ligand responsiveness was determined in or using ex-vivo PBMC by cytokine production in culture supernatants.


RESULTS
Chronic, untreated HIV-1 infection was significantly associated with increased mRNA expression of TLR6, TLR7, and TLR8 and when analysis was limited to those with advanced disease (CD4 cell count < 200 cells/ml) TLR2, TLR3, and TLR4 were additionally elevated. TLR expression correlated with the plasma HIV-RNA load, which was significant for TLR6 and TLR7. In vitro HIV single-stranded RNA alone could enhance TLR mRNA expression. PBMC of HIV-infected subjects also demonstrated profoundly increased proinflammatory responsiveness to TLR ligands, suggesting sensitization of TLR signalling in HIV. Finally, viral suppression by HAART was associated with a normalization of TLR levels.


CONCLUSIONS
Together, these data indicate that chronic viraemic HIV-1 is associated with increased TLR expression and responsiveness, which may perpetuate innate immune dysfunction and activation that underlies HIV pathogenesis, and thus reveal potential new targets for therapy.
Lester
Richard T
RT
Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada. rlester@csrtkenya.org
Yao
Xiao-Dan
XD
Ball
T Blake
TB
McKinnon
Lyle R
LR
Kaul
Rupert
R
Wachihi
Charles
C
Jaoko
Walter
W
Plummer
Francis A
FA
Rosenthal
Kenneth L
KL
D019380:Anti-HIV Agents / Q000627:therapeutic use; D023241:Antiretroviral Therapy, Highly Active; D016022:Case-Control Studies; D005260:Female; D015658:HIV Infections / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism*; D015497:HIV-1; D006801:Humans; D007630:Kenya; D008024:Ligands; D008213:Lymphocyte Activation; D018655:Lymphocyte Count; D012333:RNA, Messenger / Q000032:analysis; D012367:RNA, Viral / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D051195:Toll-Like Receptor 2 / Q000097:blood; D051196:Toll-Like Receptor 3 / Q000097:blood; D051197:Toll-Like Receptor 4 / Q000097:blood; D051216:Toll-Like Receptor 6 / Q000097:blood; D051199:Toll-Like Receptor 7 / Q000097:blood; D051200:Toll-Like Receptor 8 / Q000097:blood; D051193:Toll-Like Receptors / Q000097:blood* / Q000378:metabolism; D019562:Viral Load; D014766:Viremia / Q000276:immunology
D019380:Anti-HIV Agents; D008024:Ligands; D012333:RNA, Messenger; D012367:RNA, Viral; D051195:Toll-Like Receptor 2; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D051216:Toll-Like Receptor 6; D051199:Toll-Like Receptor 7; D051200:Toll-Like Receptor 8; D051193:Toll-Like Receptors