The primary mechanism of secondary injury after cerebral ischemia may be the brain inflammation that emerges after an ischemic stroke, which promotes neuronal death and inhibits nerve tissue regeneration. As the first immune cells to be activated after an ischemic stroke, microglia play an important immunomodulatory role in the progression of the condition. After an ischemic stroke, peripheral blood immune cells (mainly T cells) are recruited to the central nervous system by chemokines secreted by immune cells in the brain, where they interact with central nervous system cells (mainly microglia) to trigger a secondary neuroimmune response. This review summarizes the interactions between T cells and microglia in the immune-inflammatory processes of ischemic stroke. We found that, during ischemic stroke, T cells and microglia demonstrate a more pronounced synergistic effect. Th1, Th17, and M1 microglia can co-secrete pro-inflammatory factors, such as interferon-γ, tumor necrosis factor-α, and interleukin-1β, to promote neuroinflammation and exacerbate brain injury. Th2, Treg, and M2 microglia jointly secrete anti-inflammatory factors, such as interleukin-4, interleukin-10, and transforming growth factor-β, to inhibit the progression of neuroinflammation, as well as growth factors such as brain-derived neurotrophic factor to promote nerve regeneration and repair brain injury. Immune interactions between microglia and T cells influence the direction of the subsequent neuroinflammation, which in turn determines the prognosis of ischemic stroke patients. Clinical trials have been conducted on the ways to modulate the interactions between T cells and microglia toward anti-inflammatory communication using the immunosuppressant fingolimod or overdosing with Treg cells to promote neural tissue repair and reduce the damage caused by ischemic stroke. However, such studies have been relatively infrequent, and clinical experience is still insufficient. In summary, in ischemic stroke, T cell subsets and activated microglia act synergistically to regulate inflammatory progression, mainly by secreting inflammatory factors. In the future, a key research direction for ischemic stroke treatment could be rooted in the enhancement of anti-inflammatory factor secretion by promoting the generation of Th2 and Treg cells, along with the activation of M2-type microglia. These approaches may alleviate neuroinflammation and facilitate the repair of neural tissues.

Stroke is known for its high disability and mortality rates. Ischemic stroke (IS), the most prevalent form, imposes a considerable burden on affected individuals. Nevertheless, existing treatment modalities are hindered by limitations, including narrow therapeutic windows, substantial adverse effects, and suboptimal neurological recovery. Clarifying the pathological mechanism of IS is a prerequisite for developing new therapeutic strategies. In this context, the functional disruption of mitochondria, the endoplasmic reticulum (ER), and the crosstalk mechanisms between them have garnered increasing attention for their contributory roles in the progression of IS. Therefore, this review provides a comprehensive summary of the current pathomechanisms associated with the involvement of the ER and mitochondria in IS, emphasising Ca²⁺ destabilization homeostasis, ER stress, oxidative stress, disordered mitochondrial quality control, and mitochondrial transfer. Additionally, this article highlights the functional interaction between the ER and mitochondria, as well as the mitochondrial-ER contacts (MERCs) that structurally connect mitochondria and the ER, aiming to provide ideas and references for the research and treatment of IS.

Ischemic stroke, a frequently occurring form of stroke, is caused by obstruction of cerebral blood flow, which leads to ischemia, hypoxia, and necrosis of local brain tissue. After ischemic stroke, both astrocytes and the blood–brain barrier undergo morphological and functional transformations. However, the interplay between astrocytes and the blood–brain barrier has received less attention. This comprehensive review explores the physiological and pathological morphological and functional changes in astrocytes and the blood–brain barrier in ischemic stroke. Post-stroke, the structure of endothelial cells and peripheral cells undergoes alterations, causing disruption of the blood–brain barrier. This disruption allows various pro-inflammatory factors and chemokines to cross the blood–brain barrier. Simultaneously, astrocytes swell and primarily adopt two phenotypic states: A1 and A2, which exhibit different roles at different stages of ischemic stroke. During the acute phase, A1 reactive astrocytes secrete vascular endothelial growth factor, matrix metalloproteinases, lipid carrier protein-2, and other cytokines, exacerbating damage to endothelial cells and tight junctions. Conversely, A2 reactive astrocytes produce pentraxin 3, Sonic hedgehog, angiopoietin-1, and other protective factors for endothelial cells. Furthermore, astrocytes indirectly influence blood–brain barrier permeability through ferroptosis and exosomes. In the middle and late (recovery) stages of ischemic stroke, A1 and A2 astrocytes show different effects on glial scar formation. A1 astrocytes promote glial scar formation and inhibit axon growth via glial fibrillary acidic protein, chondroitin sulfate proteoglycans, and transforming growth factor-β. In contrast, A2 astrocytes facilitate axon growth through platelet-derived growth factor, playing a crucial role in vascular remodeling. Therefore, enhancing our understanding of the pathological changes and interactions between astrocytes and the blood–brain barrier is a vital therapeutic target for preventing further brain damage in acute stroke. These insights may pave the way for innovative therapeutic strategies for ischemic stroke.

Chronic cerebral hypoperfusion can lead to neuronal necrosis, trigger inflammatory responses, promote white matter damage, and ultimately result in cognitive impairment. Consequently, chronic cerebral hypoperfusion is an important factor influencing the onset and progression of vascular dementia. The myelin sheath is a critical component of white matter, and damage and repair of the white matter are closely linked to myelin sheath integrity. This article reviews the role of microglia in vascular dementia, focusing on their effects on myelin sheaths and the potential therapeutic implications. The findings suggest that ischemia and hypoxia cause disruption of the blood–brain barrier and activate microglia, which may worsen blood–brain barrier damage through the release of matrix-degrading enzymes. Microglia-mediated metabolic reprogramming is recognized as an important driver of inflammation. Damage to the blood–brain barrier and subsequent inflammation can lead to myelin injury and accelerate the progression of vascular dementia. Early activation of microglia is a protective response that contributes to the maintenance of blood–brain barrier integrity through sensing, debris-clearing, and defensive mechanisms. However, prolonged activation can trigger a shift in microglia toward the pro-inflammatory M1 phenotype, resulting in myelin damage and cognitive impairment. Triggering receptor expressed on myeloid cells 2 and triggering receptor expressed on myeloid cells 1 have been identified as potential biomarkers for vascular dementia, as both are closely linked to cognitive decline. Although effective clinical treatments for myelin damage in the central nervous system are currently lacking, researchers are actively working to develop targeted therapies. Several drugs, including nimodipine, dopaminergic agents, simvastatin, biotin, and quetiapine, have been evaluated for clinical use in treating microglial and myelin damage. Future research will face challenges in developing targeted therapeutic strategies for vascular dementia, requiring further investigation into the timing, duration, and specific mechanisms of microglial activation, as well as the exploration of new drug combinations and additional therapeutic targets.