Hemeoxygenase-1 as a Novel Driver in Ritonavir-Induced Insulin Resistance in HIV-1-Infected Patients

Restriction of HIV-1 infection in sickle cell trait

Patients with sickle cell disease (SCD) have a lower risk for HIV-1 infection. We reported restriction of ex vivo HIV-1 infection in SCD peripheral blood mononuclear cells (PBMCs) that was due, in part, to the upregulation of antiviral, inflammatory, and hemolytic factors, including heme oxygenase-1 (HO-1). Here, we investigated whether individuals with sickle cell trait (SCT), who develop mild hemolysis, also restrict HIV-1 infection. Ex vivo infection of SCT PBMCs exhibited an approximately twofold reduction of HIV-1 replication and lower levels of HIV-1 reverse transcription products, 2-long terminal repeat circle, HIV-1 integration, and gag RNA expression. SCT PBMCs had higher HO-1 messenger RNA (mRNA) and protein levels and reduced ribonucleotide reductase 2 (RNR2) protein levels. HO-1 inhibition by tin porphyrin eliminated ex vivo HIV-1 restriction. Among Howard University clinic recruits, higher levels of HO-1 and RNR2 mRNA and lower HIV-1 env mRNA levels were found in SCT individuals living with HIV-1. To determine the population-level effect of SCT on HIV-1 prevalence, we assessed SCT among women living with HIV (WLH) in the WIHS (Women Interagency HIV-1 Study). Among WIHS African-American participants, the prevalence of SCT was lower among women with HIV compared with uninfected women (8.7% vs 14.2%; odds ratio, 0.57; 95% confidence interval, 0.36-0.92; P = .020). WIHS WLH with SCT had higher levels of CD4+/CD8+ ratios over 20 years of follow-up (P = .003) than matched WLH without SCT. Together, our findings suggest that HIV-1 restriction factors, including HO-1 and RNR2, might restrict HIV-1 infection among individuals with SCT and limit the pathogenicity of HIV.

HIV protease inhibitor ritonavir induces renal fibrosis and dysfunction: role of platelet-derived TGF-β1 and intervention via antioxidant pathways

OBJECTIVE

Chronic kidney disease (CKD) with tubular injury and fibrosis occurs in HIV infection treated with certain protease inhibitor-based antiretroviral therapies. The pathophysiology is unclear.

DESIGN

We hypothesized that fibrosis, mediated by platelet-derived transforming growth factor (TGF)-β1, underlies protease inhibitor-associated CKD. We induced this in mice exposed to the protease inhibitor ritonavir (RTV), and intervened with low-dose inhaled carbon monoxide (CO), activating erythroid 2-related factor (Nrf2)-associated antioxidant pathways.

METHODS

Wild-type C57BL/6 mice and mice deficient in platelet TGF-β1, were given RTV (10 mg/kg) or vehicle daily for 8 weeks. Select groups were exposed to CO (250 ppm) for 4 h after RTV or vehicle injection. Renal disorder, fibrosis, and TGF-β1-based and Nrf2-based signaling were examined by histology, immunofluorescence, and flow cytometry. Renal damage and dysfunction were assessed by KIM-1 and cystatin C ELISAs. Clinical correlations were sought among HIV-infected individuals.

RESULTS

RTV-induced glomerular and tubular injury, elevating urinary KIM-1 (P = 0.004). It enhanced TGF-β1-related signaling, accompanied by kidney fibrosis, macrophage polarization to an inflammatory phenotype, and renal dysfunction with cystatin C elevation (P = 0.008). Mice lacking TGF-β1 in platelets were partially protected from these abnormalities. CO inhibited RTV-induced fibrosis and macrophage polarization in association with upregulation of Nrf2 and heme oxygenase-1 (HO-1). Clinically, HIV infection correlated with elevated cystatin C levels in untreated women (n = 17) vs. age-matched controls (n = 19; P = 0.014). RTV-treated HIV+ women had further increases in cystatin C (n = 20; P = 0.05), with parallel elevation of HO-1.

CONCLUSION

Platelet TGF-β1 contributes to RTV-induced kidney fibrosis and dysfunction, which may be amenable to antioxidant interventions.

HIV-associated cardiovascular disease: importance of platelet activation and cardiac fibrosis in the setting of specific antiretroviral therapies

HIV infection is a risk factor for cardiovascular disease (CVD). This risk is accentuated by certain combination antiretroviral therapies (cARTs), independent of their effects on lipid metabolism and insulin sensitivity. We sought to define potential mechanisms for this association through systematic review of clinical and preclinical studies of CVD in the setting of HIV/cART from the English language literature from 1989 to March 2018. We used PubMed, Web of Knowledge and Google Scholar, and conference abstracts for the years 2015-March 2018. We uncovered three themes: (1) a critical role for the HIV protease inhibitor (PI) ritonavir and certain other PI-based regimens. (2) The importance of platelet activation. Virtually all PIs, and one nucleoside reverse transcriptase inhibitor, abacavir, activate platelets, but a role for this phenomenon in clinical CVD risk may require additional postactivation processes, including: release of platelet transforming growth factor-β1; induction of oxidative stress with production of reactive oxygen species from vascular cells; suppression of extracellular matrix autophagy; and/or sustained proinflammatory signalling, leading to cardiac fibrosis and dysfunction. Cardiac fibrosis may underlie an apparent shift in the character of HIV-linked CVD over the past decade from primarily left ventricular systolic to diastolic dysfunction, possibly driven by cART. (3) Recognition of the need for novel interventions. Switching from cART regimens based on PIs to contemporary antiretroviral agents such as the integrase strand transfer inhibitors, which have not been linked to clinical CVD, may not mitigate CVD risk assumed under prior cART. In conclusion, attention to the effects of specific antiretroviral drugs on platelet activation and related profibrotic signalling pathways should help: guide selection of appropriate anti-HIV therapy; assist in evaluation of CVD risk related to novel antiretrovirals; and direct appropriate interventions.

HIV and Aging - Perhaps Not as Dramatic as We Feared?

Ever since the introduction of highly active antiretroviral therapy (ART) in 1995, HIV infection has been linked to "metabolic" complications (insulin resistance, dyslipidemia, osteoporosis, and others). Studies suggested increased rates of myocardial infarction, renal insufficiency, neurocognitive dysfunction, and fractures in HIV-postitive patients. Even long-term suppression of HIV seemed to be accompanied by an excess of deleterious inflammation that could promote these complications. The aims of this viewpoint paper are to summarize recent data and to examine the possibility that the problem of aging-related morbidity in HIV might not be as dramatic as previously believed.

HIV protease inhibitor-induced cardiac dysfunction and fibrosis is mediated by platelet-derived TGF-β1 and can be suppressed by exogenous carbon monoxide

Human immunodeficiency virus (HIV) infection is an independent risk factor for cardiovascular disease. This risk is magnified by certain antiretrovirals, particularly the protease inhibitor ritonavir, but the pathophysiology of this connection is unknown. We postulated that a major mechanism for antiretroviral-associated cardiac disease is pathologic fibrosis linked to platelet activation with release and activation of transforming growth factor (TGF)-β1, and that these changes could be modeled in a murine system. We also sought to intervene utilizing inhaled carbon monoxide (CO) as proof-of-concept for therapeutics capable of regulating TGF-β1 signaling and collagen autophagy. We demonstrate decreased cardiac function indices, including cardiac output, ejection fraction and stroke volume, and prominent cardiac fibrosis, in mice exposed to pharmacological doses of ritonavir. Cardiac output and fibrosis correlated with plasma TGF-β1 levels. Mice with targeted deletion of TGF-β1 in megakaryocytes/platelets (PF4CreTgfb1^flox/flox) were partially protected from ritonavir-induced cardiac dysfunction and fibrosis. Inhalation of low dose CO (250ppm), used as a surrogate for upregulation of inducible heme oxygenase/endogenous CO pathways, suppressed ritonavir-induced cardiac fibrosis. This occurred in association with modulation of canonical (Smad2) and non-canonical (p38) TGF-β1 signaling pathways. In addition, CO treatment suppressed the M1 pro-inflammatory subset of macrophages and increased M2c regulatory cells in the hearts of RTV-exposed animals. The effects of CO were dependent upon autophagy as CO did not mitigate ritonavir-induced fibrosis in autophagy-deficient LC3^-/- mice. These results suggest that platelet-derived TGF-β1 contributes to ritonavir-associated cardiac dysfunction and fibrosis, extending the relevance of our findings to other antiretrovirals that also activate platelets. The anti-fibrotic effects of CO are linked to alterations in TGF-β1 signaling and autophagy, suggesting a proof-of-concept for novel interventions in HIV/antiretroviral therapy-mediated cardiovascular disease.