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The opioid epidemic endangers not only public health but also social and economic welfare. Growing clinical evidence indicates that chronic use of prescription opioids may contribute to an elevated risk of ischemic stroke and negatively impact post-stroke recovery. In addition, NLRP3 inflammasome activation has been related to several cerebrovascular diseases, including ischemic stroke. Interestingly, an increase in NLRP3 inflammasome activation has also been reported in chronic opioid exposure. Given the pivotal roles of the blood-brain barrier (BBB) and oxidative stress in ischemic stroke pathophysiology, this study focuses on the impact of chronic exposure to prescription opioids on the integrity of cerebrovascular microvasculature, endothelial mitochondrial homeostasis, and the outcomes of ischemic stroke in male wild type and NLRP3-deficient mice. Our results demonstrate that chronic opioid exposure can compromise the integrity of the BBB and elevate the generation of reactive oxygen species (ROS), resulting in endothelial mitochondrial dysfunction and apoptosis activation. We also provide evidence that opioid exposure enhances inflammasome activation, inflammatory responses, and increases the severity of an ischemic stroke. The antioxidant N-acetylcysteine (NAC) ameliorated these opioid-induced alterations and accelerated the post-stroke tissue restoration and functional recovery processes in opioid-exposed mice. Importantly, there was also a significant decrease in ischemic stroke damage in the NLRP3-deficient mice with chronic opioid exposure as compared to wild-type controls. These findings indicate that chronic exposure to prescription opioids impacts the outcome of ischemic stroke by damaging microvascular cerebral integrity through inflammasome activation and mitochondrial dysfunction. Significance Statement Misuse of opioids has become one of the most important public health problems. Growing evidence indicates that chronic use of prescription opioids may contribute to an elevated risk of ischemic stroke, and negatively impact post-stroke recovery. In the present study, we hypothesize that microvascular dysfunction can underlie the impact of prescription opioid on an ischemic stroke. Our novel results demonstrate that opioid exposure leads to mitochondrial dysfunction in the brain microvascular endothelium, compromised blood-brain barrier integrity, enhanced inflammatory responses, and more severe effects of an ischemic stroke. Importantly, the NLRP3 inflammasome-deficient mice or treatment with N-acetylcysteine attenuated these alterations and enhanced post-stroke tissue and functional recovery, providing valuable therapeutic options for people with opioid use disorder., (Copyright © 2025 Sun et al.)

Occludin (ocln) is one of the main regulatory cells of the blood-brain barrier (BBB). Ocln silencing resulted in alterations of the gene expression signatures of a variety of genes of the innate immunity system, including IFN-stimulated genes (ISGs) and the antiviral retinoic acid-inducible gene-1 (RIG-1) signaling pathway, which functions as a regulator of the cytoplasmic sensors upstream of the mitochondrial antiviral signaling protein (MAVS). Indeed, we observed dysfunctional mitochondrial bioenergetics, dynamics, and autophagy in our system. Alterations of mitochondrial bioenergetics and innate immune protection translated into worsened ischemic stroke outcomes in EcoHIV-infected ocln deficient mice. Overall, these results allow for a better understanding of the molecular mechanisms of viral infection in the brain and describe a previously unrecognized role of ocln as a key factor in the control of innate immune responses and mitochondrial dynamics, which affect cerebral vascular diseases such as ischemic stroke., Competing Interests: Declaration of Interests The authors declare no competing interests.

Aim: Elevated brain deposits of amyloid beta (Aβ 40 ) contribute to neuropathology and cognitive dysfunction in Alzheimer's disease (AD). However, the role of the blood-brain barrier (BBB) as an interface for the transfer of Aβ 40 from the periphery into the brain is not well characterized. In addition, a substantial population of neural progenitor cells (NPCs) resides in close proximity to brain capillaries that form the BBB. The aim of this study is to understand the impact of brain endothelium-derived extracellular vesicles (EV) containing Aβ 40 on metabolic functions and differentiation of NPCs., Methods: Endothelial EVs were derived from an in vitro model of the brain endothelium treated with 100 nM Aβ 40 or PBS. We then analyzed the impact of these EVs on mitochondrial morphology and bioenergetic disruption of NPCs. In addition, NPCs were differentiated and neurite development upon exposure to EVs was assessed using the IncuCyte Zoom live cell imaging system., Results: We demonstrate that physiological concentrations of Aβ 40 can be transferred to accumulate in NPCs via endothelial EVs. This transfer results in mitochondrial dysfunction, disrupting crista morphology, metabolic rates, fusion and fission dynamics of NPCs, as well as their neurite development., Conclusion: Intercellular transfer of Aβ 40 is carried out by brain endothelium-derived EVs, which can affect NPC differentiation and induce mitochondrial dysfunction, leading to aberrant neurogenesis. This has pathological implications because NPCs growing into neurons are incorporated into cerebral structures involved in learning and memory, two common phenotypes affected in AD and related dementias., Competing Interests: Conflicts of interest All authors declared that there are no conflicts of interest.