Heme oxygenase-1-derived bilirubin counteracts HIV protease inhibitor-mediated endothelial cell dysfunction

Abstract

The use of HIV protease inhibitors (PIs) has extended the duration and quality of life for HIV-positive individuals. However there is increasing concern that this antiviral therapy may promote premature cardiovascular disease by impairing endothelial cell (EC) function. In the present study, we investigated the effect of HIV PIs on EC function and determined if the enzyme heme oxygenase (HO-1) influences the biological action of these drugs. We found that three distinct PIs, including ritonavir, atazanavir, and lopinavir, stimulated the expression of HO-1 protein and mRNA. The induction of HO-1 was associated with an increase in NF-E2-related factor-2 (Nrf2) activity and reactive oxygen species (ROS). PIs also stimulated HO-1 promoter activity and this was prevented by mutating the antioxidant responsive element or by overexpressing dominant-negative Nrf2. In addition, the PI-mediated induction of HO-1 was abolished by N-acetyl-L-cysteine and rotenone. Furthermore, PIs blocked EC proliferation and migration and stimulated the expression of intercellular adhesion molecule-1 and the adhesion of monocytes on ECs. Inhibition of HO-1 activity or expression potentiated the anti-proliferative and inflammatory actions of PIs which was reversed by bilirubin but not carbon monoxide. Alternatively, adenovirus-mediated overexpression of HO-1 attenuated the growth-inhibitory and inflammatory effect of PIs. In contrast, blocking HO-1 activity failed to modify the anti-migratory effect of the PIs. Thus, induction of HO-1 via the ROS–Nrf2 pathway in human ECs counteracts the anti-proliferative and inflammatory actions of PIs by generating bilirubin. Therapeutic approaches targeting HO-1 may provide a novel approach in preventing EC dysfunction and vascular disease in HIV-infected patients undergoing antiretroviral therapy.

Bilirubin Is Inversely Associated With Cardiovascular Disease Among HIV‐Positive and HIV‐Negative Individuals in VACS (Veterans Aging Cohort Study)

“…17 To potentially explain these mixed findings, atazanavir and other protease inhibitors have been shown to actually increase endothelial dysfunction, oxidative stress, and von Willebrand factor, thereby counteracting some of the benefits of the elevated bilirubin levels. [46][47][48] Because CVD rates did not differ by atazanavir status in the VACS analysis, it is unlikely that the bilirubin effect is merely a surrogate for a protective effect afforded by atazanavir use. If replicated successfully, these results have potential clinical implications not only for CVD risk assessment and reduction but also in other chronic conditions, including cancers, demyelinating neuropathies, seasonal affective disorder, 14 and rheumatoid arthritis.…”

“…In one of these trials, endothelial function improved,16 whereas the second study showed only a reduction in low‐density lipoprotein levels and blood pressure 17. To potentially explain these mixed findings, atazanavir and other protease inhibitors have been shown to actually increase endothelial dysfunction, oxidative stress, and von Willebrand factor, thereby counteracting some of the benefits of the elevated bilirubin levels 46, 47, 48. Because CVD rates did not differ by atazanavir status in the VACS analysis, it is unlikely that the bilirubin effect is merely a surrogate for a protective effect afforded by atazanavir use.…”

Modulation of Antiviral Immunity by Heme Oxygenase-1

“…52 Finally, bilirubin derived from HO-1 has been reported to inhibit the protease activity of HIV, which negatively affects virus replication. 53 The beneficial properties of HO-1 expression have also been reported for viruses that produce lung disease, such as influenza virus infection. Mice that overexpress HO-1 in the lungs display less inflammatory cell infiltration into the lungs and decreased apoptosis of respiratory epithelial cells, as compared to control mice, suggesting that HO-1 expression prevents an exacerbated immune response in this tissue and subsequent damage.…”

The Cytoprotective Enzyme Heme Oxygenase-1 Suppresses Pseudorabies Virus Replication in vitro

“…For example, as a downstream metabolite of HO-1, BV has been demonstrated to act as a key effector against HCV replication by activating the antiviral IFN response and inhibiting the NS3/4A protease activity of HCV (Lehmann et al, 2010;Zhu et al, 2010). HO-1 derived from BR has been reported to suppress human herpes simplex type 1 virus (HSV-1) and EV71 infection, as well as protease activity of DENV and HIV (Santangelo et al, 2012;Olagnier et al, 2014;Liu et al, 2016). Iron ions derived from HO-1 have been demonstrated to participate in key cellular processes that are dependent on this metal, either promoting or suppressing the translation of particular mRNAs, depending on its concentrations (Eisenstein et al, 1991).…”