Publications

HIV evades eradication because transcriptionally dormant proviral genomes persist in long-lived reservoirs of resting CD4(+) T cells and myeloid cells, which are the source of viral rebound after cessation of antiretroviral therapy. Dormant HIV genomes readily produce infectious virus upon cellular activation because host transcription factors activated specifically by cell stress and heat shock mediate full-length HIV transcription. The molecular chaperone heat shock protein 90 (Hsp90) is overexpressed during heat shock and activates inducible cellular transcription factors. Here we show that heat shock accelerates HIV transcription through induction of Hsp90 activity, which activates essential HIV-specific cellular transcription factors (NF-κB, NFAT, and STAT5), and that inhibition of Hsp90 greatly reduces gene expression mediated by these factors. More importantly, we show that Hsp90 controls virus transcription in vivo by specific Hsp90 inhibitors in clinical development, tanespimycin (17-(allylamino)-17-demethoxygeldanamycin) and AUY922, which durably prevented viral rebound in HIV-infected humanized NOD scid IL-2Rγ(-/-) bone marrow-liver-thymus mice up to 11 weeks after treatment cessation. Despite the absence of rebound viremia, we were able to recover infectious HIV from PBMC with heat shock. Replication-competent virus was detected in spleen cells from these nonviremic Hsp90 inhibitor-treated mice, indicating the presence of a tissue reservoir of persistent infection. Our novel findings provide in vivo evidence that inhibition of Hsp90 activity prevents HIV gene expression in replication-competent cellular reservoirs that would typically cause rebound in plasma viremia after antiretroviral therapy cessation. Alternating or supplementing Hsp90 inhibitors with current antiretroviral therapy regimens could conceivably suppress rebound viremia from persistent HIV reservoirs.

PURPOSE OF REVIEW

The purpose is to review recent insights into the impact of HIV-associated immune activation on AIDS and non-AIDS morbidity and mortality.

RECENT FINDINGS

Immune activation has long been recognized as an important consequence of untreated HIV infection and predictor of AIDS progression, which declines but fails to normalize during suppressive antiretroviral therapy, and continues to predict disease in this setting. Thus, a major research agenda is to develop novel therapies to reduce persistent immune activation in treated HIV infection. Yet, the optimal targets for interventions remain unclear. Both the specific root causes of immune activation and the many interconnected pathways of immune activation that are most likely to drive disease risk in HIV-infected individuals remain incompletely characterized, but recent studies have shed new light on these topics.

SUMMARY

In the context of this review, we will summarize recent evidence helping to elucidate the immunologic pathways that appear most strongly predictive of infectious and noninfectious morbidity. We will also highlight the likelihood that not all root drivers of immune activation - and the discrete immunologic pathways to which they give rise - are likely to produce the same disease manifestations and/or be equally attenuated by early antiretroviral therapy initiation.

HIV infection is associated with arterial stiffness, but no studies have assessed this relationship in sub-Saharan Africa. We enrolled 205 participants over 40 years old in Uganda: 105 on antiretroviral therapy for a median of 7 years, and a random sample of 100 age and sex-matched HIV-uninfected controls from the clinic catchment area. The prevalence of arterial stiffness (ankle brachial index  > 1.2) was 33%, 18%, 19% and 2% in HIV+ men, HIV- men, HIV+ women, and HIV- women. In multivariable models adjusted for cardiovascular risk factors, HIV+ individuals had over double the prevalence of arterial stiffness (adjusted prevalence ratio 2.86, 95% confidence interval 1.41-5.79, P = 0.003).