Microvascular Function in Aging Among Women Living with HIV

Nucleus-mitochondria positive feedback loop formed by ERK5 S496 phosphorylation-mediated poly (ADP-ribose) polymerase activation provokes persistent pro-inflammatory senescent phenotype and accelerates coronary atherosclerosis after chemo-radiation

The incidence of cardiovascular disease (CVD) is higher in cancer survivors than in the general population. Several cancer treatments are recognized as risk factors for CVD, but specific therapies are unavailable. Many cancer treatments activate shared signaling events, which reprogram myeloid cells (MCs) towards persistent senescence-associated secretory phenotype (SASP) and consequently CVD, but the exact mechanisms remain unclear. This study aimed to provide mechanistic insights and potential treatments by investigating how chemo-radiation can induce persistent SASP. We generated ERK5 S496A knock-in mice and determined SASP in myeloid cells (MCs) by evaluating their efferocytotic ability, antioxidation-related molecule expression, telomere length, and inflammatory gene expression. Candidate SASP inducers were identified by high-throughput screening, using the ERK5 transcriptional activity reporter cell system. Various chemotherapy agents and ionizing radiation (IR) up-regulated p90RSK-mediated ERK5 S496 phosphorylation. Doxorubicin and IR caused metabolic changes with nicotinamide adenine dinucleotide depletion and ensuing mitochondrial stunning (reversible mitochondria dysfunction without showing any cell death under ATP depletion) via p90RSK-ERK5 modulation and poly (ADP-ribose) polymerase (PARP) activation, which formed a nucleus-mitochondria positive feedback loop. This feedback loop reprogramed MCs to induce a sustained SASP state, and ultimately primed MCs to be more sensitive to reactive oxygen species. This priming was also detected in circulating monocytes from cancer patients after IR. When PARP activity was transiently inhibited at the time of IR, mitochondrial stunning, priming, macrophage infiltration, and coronary atherosclerosis were all eradicated. The p90RSK-ERK5 module plays a crucial role in SASP-mediated mitochondrial stunning via regulating PARP activation. Our data show for the first time that the nucleus-mitochondria positive feedback loop formed by p90RSK-ERK5 S496 phosphorylation-mediated PARP activation plays a crucial role of persistent SASP state, and also provide preclinical evidence supporting that transient inhibition of PARP activation only at the time of radiation therapy can prevent future CVD in cancer survivors.

Senescent Phenotype Induced by p90RSK-NRF2 Signaling Sensitizes Monocytes and Macrophages to Oxidative Stress in HIV-Positive Individuals

BACKGROUND

The incidence of cardiovascular disease is higher in HIV-positive (HIV⁺) patients than it is in the average population, and combination antiretroviral therapy (cART) is a recognized risk factor for cardiovascular disease. However, the molecular mechanisms that link cART and cardiovascular disease are currently unknown. Our study explores the role of the activation of p90RSK, a reactive oxygen species-sensitive kinase, in engendering senescent phenotype in macrophages and accelerating atherogenesis in patients undergoing cART.

METHODS

Peripheral whole blood from cART-treated HIV⁺ individuals and nontreated HIV-negative individuals was treated with H₂O₂ (200 µmol/L) for 4 minutes, and p90RSK activity in CD14⁺ monocytes was measured. Plaque formation in the carotids was also analyzed in these individuals. Macrophage senescence was determined by evaluating their efferocytotic ability, antioxidation-related molecule expression, telomere length, and inflammatory gene expression. The involvement of p90RSK-NRF2 signaling in cART-induced senescence was assessed by p90RSK-specific inhibitor (FMK-MEA) or dominant-negative p90RSK (DN-p90RSK) and NRF2 activator (NRF2A). Further, the severity of atherosclerosis was determined in myeloid cell-specific wild-type and DN-p90RSK transgenic mice.

RESULTS

Monocytes from HIV⁺ patients exhibited higher levels of p90RSK activity and were also more sensitive to reactive oxygen species than monocytes from HIV-negative individuals. A multiple linear regression analysis involving cART, Reynolds cardiovascular risk score, and basal p90RSK activity revealed that cART and basal p90RSK activity were the 2 significant determinants of plaque formation. Many of the antiretroviral drugs individually activated p90RSK, which simultaneously triggered all components of the macrophage senescent phenotype. cART inhibited antioxidant response element reporter activity via ERK5 S496 phosphorylation. NRF2A reversed the H₂O₂-induced overactivation of p90RSK in cART-treated macrophages by countering the induction of senescent phenotype. Last, the data obtained from our gain- or loss-of-function mice conclusively showed the crucial role of p90RSK in inducing senescent phenotype in macrophages and atherogenesis.

CONCLUSIONS

cART increased monocyte/macrophage sensitivity to reactive oxygen species- in HIV⁺ individuals by suppressing NRF2-ARE activity via p90RSK-mediated ERK5 S496 phosphorylation, which coordinately elicited senescent phenotypes and proinflammatory responses. As such, our report underscores the importance of p90RSK regulation in monocytes/macrophages as a viable biomarker and therapeutic target for preventing cardiovascular disease, especially in HIV⁺ patients treated with cART.

Special Topics in the Care of Older People with HIV

PURPOSE OF REVIEW

Antiretroviral therapy has enabled many people with HIV to live long lives with their infection, but the literature suggests that long term survivors are developing comorbidities and aging-related syndromes at earlier ages than their non-infected counterparts. In addition, there is evidence or sex-based differences in comorbidity risk.

RECENT FINDINGS

How to best care for people aging with HIV is not known, but the tools of comprehensive geriatric assessment can identify people at risk for decline. Newer antiretroviral therapies offer promise of fewer side effects and drug interactions. We will also discuss special needs of women aging with HIV.

SUMMARY

People with HIV and their providers are often unprepared to confront issues of aging, and each clinical program must develop methods to assess older patient and manage age-related complications and syndromes.

Release of Soluble Insulin Receptor From Neurons by Cerebrospinal Fluid From Patients With Neurocognitive Dysfunction and HIV Infection

Previously, we found that high levels of soluble insulin receptor (sIR) in the cerebrospinal fluid (CSF) of an HIV-infected women cohort were associated with the presence and severity of HIV-associated neurocognitive disorders (HAND). In this study we investigated if CSF from this population, HIV-1 Tat, and selected cytokines induces sIR secretion from human neuronal cells. Twenty-three (23) HIV-seropositive women stratified by cognitive status and five HIV- seronegative women were evaluated. Soluble IR levels were measured in the extracellular medium of neuronal cells (SH-SY5Y) that were exposed (for 24 h) to the CSF of patients. The levels of sIR, HIV-1 Tat, and cytokine levels (IL-2, IL4, IL-6, IFNγ, TNFα, and IL-10) were quantified in the CSF of participants by ELISA and flow cytometry. Neuronal secretion of sIR was measured after exposure (24 h) to HIV-1 Tat (0.5–250 nM), or specific cytokines. The effects of TNFα and HIV-1 Tat on sIR secretion were also evaluated in the presence of R7050 (TNFα antagonist; 10 nM). Neurons exposed to the CSF of HIV-infected women had higher sIR levels according to the severity of neurocognitive impairment of the participant. Increased CSF sIR levels were associated with the presence and severity of HAND and were positively correlated with CSF HIV-1 Tat levels in HIV-infected women with cognitive impairment. CSF levels of IL-2, IFNγ, and TNFα were significantly increased with HAND. However, only TNFα (5 pg/mL) and HIV-1 Tat (100 nM) induced a significant increase in neuronal sIR secretion after 24 h exposure, an effect that was antagonized when each were combined with R7050. Our data suggests that TNFα and HIV-1 Tat from the CSF of HIV-infected women may regulate the secretion of sIR from neuronal cells and that the effect of HIV-1 Tat on sIR secretion may depend on TNFα receptor activation.