The incessant communication that takes place between microglia and neurons is essential the development, maintenance, and pathogenesis of the central nervous system (CNS). As mobile phagocytic cells, microglia serve a critical role in surveilling and scavenging the neuronal milieu to uphold homeostasis. This review aims to discuss the various mechanisms that govern the interaction between microglia and neurons, from the molecular to the organ system level, and to highlight the importance of these interactions in the development, maintenance, and pathogenesis of the CNS. Recent research has revealed that microglia-neuron interaction is vital for regulating fundamental neuronal functions, such as synaptic pruning, axonal remodeling, and neurogenesis. The review will elucidate the intricate signaling pathways involved in these interactions, both direct and indirect, to provide a better understanding of the fundamental mechanisms of brain function. Furthermore, gaining insights into these signals could lead to the development of innovative therapies for neural disorders.

Traumatic brain injury (TBI) is linked to several pathologies. The blood-brain barrier (BBB) breakdown is considered to be one of the initial changes. Further, the microenvironmental alteration following TBI-induced BBB breakdown can be multi-scaled, constant, and dramatic. The microenvironmental variations after disruption of BBB includes several pathological changes, such as cerebral blood flow (CBF) alteration, brain edema, cerebral metabolism imbalances, and accumulation of inflammatory molecules. The modulation of the microenvironment presents attractive targets for TBI recovery, such as reducing toxic substances, inhibiting inflammation, and promoting neurogenesis. Herein, we briefly review the pathological alterations of the microenvironmental changes following BBB breakdown and outline potential interventions for TBI recovery based on microenvironmental modulation.

The development of natural membranes as coatings for nanoparticles to traverse the blood-brain barrier (BBB) presents an effective approach for treating central nervous system (CNS) disorders. In this study, we have designed a nanogel loaded with PACAP and estrogen (E2), sheathed with exosomes and responsive to reactive oxygen species (ROS), denoted as HA NGs@exosomes. The objective of this novel design is to serve as a potent drug carrier for the targeted treatment of perimenopausal depression. The efficient cellular uptake and BBB penetration of HA NGs@exosomes has been demonstrated in vitro and in vivo. Following intranasal intervention with HA NGs@exosomes, ovariectomized mice under chronic unpredictable mild stress (CUMS) have shown improved behavioral performance, indicating that HA NGs@exosomes produced a rapid-onset antidepressant effect. Moreover, HA NGs@exosomes exhibit notable antioxidant and anti-inflammatory properties and may regulate the expression of pivotal proteins in the PACAP/PAC1 pathway to promote synaptic plasticity. Our results serve as a proof-of-concept for the utility of exosome-sheathed ROS-responsive nanogel as a promising drug carrier for the treatment of perimenopausal depression. Graphical Abstract

Copper-based nanomaterials demonstrate promising potential in cancer therapy. Cu⁺ efficiently triggers a Fenton-like reaction and further consumes the high level of glutathione, initiating chemical dynamic therapy (CDT) and ferroptosis. Cuproptosis, a newly identified cell death modality that represents a great prospect in cancer therapy, is activated. However, active homeostatic systems rigorously keep copper levels within cells exceptionally low, which hinders the application of cooper nanomaterials-based therapy. Herein, a novel strategy of CRISPR-Cas9 RNP nanocarrier to deliver cuprous ions and suppress the expression of copper transporter protein ATP7A for maintaining a high level of copper in cytoplasmic fluid is developed. The Cu₂O and organosilica shell would degrade under the high level of glutathione and weak acidic environment, further releasing RNP and Cu⁺. The liberated Cu⁺ triggered a Fenton-like reaction for CDT and partially transformed to Cu²⁺, consuming intracellular GSH and initiating cuproptosis and ferroptosis efficiently. Meanwhile, the release of RNP effectively reduced the expression of copper transporter ATP7A, subsequently increasing the accumulation of cooper and enhancing the efficacy of CDT, cuproptosis, and ferroptosis. Such tumor microenvironment responsive multimodal nanoplatform opens an ingenious avenue for colorectal cancer therapy based on gene editing enhanced synergistic cuproptosis/CDT/ferroptosis.