An insult-inducible vector system activated by hypoxia and oxidative stress for neuronal gene therapy

2022 ISPNE Bruce McEwen Lifetime Achievement award: Stress, from molecules to societies

The International Society for Psychoneuroendocrinology meeting in Chicago in 2022 was thrilled to recognize Dr. Robert Sapolsky with the Bruce McEwen Lifetime Achievement award. This is the second year for the award to be named to honor Bruce McEwen and it marks the completion of a special issue edited by Blazej Miziak and Robert Paul Juster in the journal Psychoneuroendocrinology dedicated to Bruce's legacy and the unfathomable contribution of Allostatic Load to the stress field. Yet, as our award winner writes, Bruce's legacy is more than scientific as he was well known for mentorship and being an exemplary person, theorist, and scientist. Perhaps understandably for a career favored by humble introverts and shy reclusives, the science shines in the spotlight and personal reflections are cut to accommodate word count limits. For scholars entering the field, stargazing at larger than life luminaries in the field is thrilling yet intimidating as it feels impossible that these experts have the same doubts and distractions as the rest of us primates. Thus, Psychoneuroendocrinology is thrilled to kick off the first perspectives piece in the Cell to Selves series with Dr. Robert Sapolsky sharing that, like his Baboon troops in Kenya, he too sometimes has a bad-hair day. This paper is a written version of a lecture I gave on September 8th, 2022, when receiving the first Bruce McEwen Lifetime Achievement Award from the ISPNE. This was a bittersweet honor; Bruce was my graduate advisor at Rockefeller University and over the next forty years, he was my mentor, teacher and father figure. His death in 2020 left a hole in my life.

Intracerebral Hemorrhage, Oxidative Stress, and Antioxidant Therapy

Hemorrhagic stroke is a common and severe neurological disorder and is associated with high rates of mortality and morbidity, especially for intracerebral hemorrhage (ICH). Increasing evidence demonstrates that oxidative stress responses participate in the pathophysiological processes of secondary brain injury (SBI) following ICH. The mechanisms involved in interoperable systems include endoplasmic reticulum (ER) stress, neuronal apoptosis and necrosis, inflammation, and autophagy. In this review, we summarized some promising advances in the field of oxidative stress and ICH, including contained animal and human investigations. We also discussed the role of oxidative stress, systemic oxidative stress responses, and some research of potential therapeutic options aimed at reducing oxidative stress to protect the neuronal function after ICH, focusing on the challenges of translation between preclinical and clinical studies, and potential post-ICH antioxidative therapeutic approaches.

ZNT-1 Expression Reduction Enhances Free Zinc Accumulation in Astrocytes After Ischemic Stroke

Excess intracellular zinc has been implicated in ischemic brain cell death. We previously reported that extracellular zinc increases intracellular free zinc level only in hypoxic astrocytes but not in normoxia astrocytes. However, the underlying mechanisms remain to be elucidated. Zinc transporters ZnTs and ZIPs mediate intracellular zinc efflux and extracellular zinc influx. In the present study, we determined the effect of hypoxia/reoxygenation on ZnT-1 and ZIP-1. Hypoxia/reoxygenation did not change the ZIP-1 level in astrocytes. Remarkably, hypoxia/reoxygenation dramatically decreased ZnT-1 expression, which can be difficult to reverse by the addition of extracellular zinc, although extracellular zinc treatment significantly increased ZnT-1 level at normoxia. These results suggest that hypoxia/reoxygenation blocked zinc efflux, whereas zinc influx may be at a similar level to that in normoxia, providing a novel mechanism for intracellular free zinc accumulation after ischemic stroke.

ROS and brain diseases: the good, the bad, and the ugly

The brain is a major metabolizer of oxygen and yet has relatively feeble protective antioxidant mechanisms. This paper reviews the Janus-faced properties of reactive oxygen species. It will describe the positive aspects of moderately induced ROS but it will also outline recent research findings concerning the impact of oxidative and nitrooxidative stress on neuronal structure and function in neuropsychiatric diseases, including major depression. A common denominator of all neuropsychiatric diseases including schizophrenia and ADHD is an increased inflammatory response of the brain caused either by an exposure to proinflammatory agents during development or an accumulation of degenerated neurons, oxidized proteins, glycated products, or lipid peroxidation in the adult brain. Therefore, modulation of the prooxidant-antioxidant balance provides a therapeutic option which can be used to improve neuroprotection in response to oxidative stress. We also discuss the neuroprotective role of the nuclear factor erythroid 2-related factor (Nrf2) in the aged brain in response to oxidative stressors and nanoparticle-mediated delivery of ROS-scavenging drugs. The antioxidant therapy is a novel therapeutic strategy. However, the available drugs have pleiotropic actions and are not fully characterized in the clinic. Additional clinical trials are needed to assess the risks and benefits of antioxidant therapies for neuropsychiatric disorders.

The tumor microenvironment: characterization, redox considerations, and novel approaches for reactive oxygen species-targeted gene therapy

The tumor microenvironment is a complex system that involves the interaction between malignant and neighbor stromal cells embedded in a mesh of extracellular matrix (ECM) components. Stromal cells (fibroblasts, endothelial, and inflammatory cells) are co-opted at different stages to help malignant cells invade the surrounding ECM and disseminate. Malignant cells have developed adaptive mechanisms to survive under the extreme conditions of the tumor microenvironment such as restricted oxygen supply (hypoxia), nutrient deprivation, and a prooxidant state among others. These conditions could be eventually used to target drugs that will be activated specifically in this microenvironment. Preclinical studies have shown that modulating cellular/tissue redox state by different gene therapy (GT) approaches was able to control tumor growth. In this review, we describe the most relevant features of the tumor microenvironment, addressing reactive oxygen species-generating sources that promote a prooxidative microenvironment inside the tumor mass. We describe different GT approaches that promote either a decreased or exacerbated prooxidative microenvironment, and those that make use of the differential levels of ROS between cancer and normal cells to achieve tumor growth inhibition.

Neuroprotection of neurotrophin-3 against focal cerebral ischemia/reperfusion injury is regulated by hypoxia-responsive element in rats

Exogenous delivery of the neurotrophin-3 (NT-3) gene may provide a potential therapeutic strategy for ischemic stroke. To investigate the neuroprotective effects of NT-3 expression controlled by 5HRE after focal cerebral ischemia, we constructed a recombinant retrovirus vector (RV) with five copies of hypoxia-responsive elements (5HRE or 5H) and NT-3 and delivered it to the rat brain. Three groups of rats received RV-5H-NT3, RV-5H-EGFP or saline injection. Three days after gene transfer, the rats underwent 90min of transient middle cerebral artery occlusion (tMCAO), followed by 1-28days of reperfusion. Three days after tMCAO, brain NT-3 expression was significantly increased in the RV-5H-NT3-transduced animals compared with the RV-5H-EGFP or saline group, and brain infarct volume was smaller in the RV-5H-NT3-transduced group than the RV-5H-EGFP or saline group. The percentage of TUNEL-positive cells was reduced in RV-5H-NT3-transduced brains compared with the RV-5H-EGFP or saline group 3 and 7days after tMCAO. Furthermore, the neurological status of RV-5H-NT3-transduced rats was better than that of RV-5H-EGFP- or saline-transduced animals from 1day to 4weeks after tMCAO. Our results demonstrated that 5HRE could modulate NT-3 expression in the ischemic brain environment and that the up-regulated NT-3 could effectively improve neurological status following tMCAO due to decreased initial damage. To avoid unexpected side effects, 5HRE-controlled gene expression might be a useful tool for gene therapy of ischemic disorders in the central nervous system.