The lymphatic drainage systems in the brain:a novel target for ischemic stroke?

Recent studies have proposed three lymphatic drainage systems in the brain,that is,the glymphatic system,the intramural periarterial drainage pathway,and meningeal lymphatic vessels,whose roles in various neurological diseases have been widely explored.The glymphatic system is a fluid drainage and waste clearance pathway that utilizes perivascular space and aquaporin-4 protein located in the astrocyte endfeet to provide a space for exchange of cerebrospinal fluid and interstitial fluid.The intramural periarterial drainage pathway drives the flow of interstitial fluid through the capillary basement membrane and the arterial tunica media.Meningeal lymphatic vessels within the dura mater are involved in the removal of cerebral macromolecules and immune responses.After ischemic stroke,impairment of these systems could lead to cerebral edema,accumulation of toxic factors,and activation of neuroinflammation,while restoration of their normal functions can improve neurological outcomes.In this review,we summarize the basic concepts of these drainage systems,including drainage routes,physiological functions,regulatory mechanisms,and detection technologies.We also focus on the roles of lymphatic drainage systems in brain injury after ischemic stroke,as well as recent advances in therapeutic strategies targeting these drainage systems.These findings provide information for potential novel strategies for treatment of stroke.

Meningeal lymphatic vessel crosstalk with central nervous system immune cells in aging and neurodegenerative diseases

Meningeal lymphatic vessels form a relationship between the nervous system and periphery, which is relevant in both health and disease. Meningeal lymphatic vessels not only play a key role in the drainage of brain metabolites but also contribute to antigen delivery and immune cell activation. The advent of novel genomic technologies has enabled rapid progress in the characterization of myeloid and lymphoid cells and their interactions with meningeal lymphatic vessels within the central nervous system. In this review, we provide an overview of the multifaceted roles of meningeal lymphatic vessels within the context of the central nervous system immune network, highlighting recent discoveries on the immunological niche provided by meningeal lymphatic vessels. Furthermore, we delve into the mechanisms of crosstalk between meningeal lymphatic vessels and immune cells in the central nervous system under both homeostatic conditions and neurodegenerative diseases, discussing how these interactions shape the pathological outcomes. Regulation of meningeal lymphatic vessel function and structure can influence lymphatic drainage, cerebrospinal fluid-borne immune modulators, and immune cell populations in aging and neurodegenerative disorders, thereby playing a key role in shaping meningeal and brain parenchyma immunity.

Functional aspects of the brain lymphatic drainage system in aging and neurodegenerative diseases

The phenomenon of an aging population is advancing at a precipitous rate.Alzheimer's disease(AD)and Parkinson's disease(PD)are two of the most common age-associated neurodegenerative diseases,both of which are primarily characterized by the accumulation of toxic proteins and the progressive demise of neuronal structures.Recent discoveries about the brain lymphatic drainage system have precipitated a growing body of investigations substantiating its novel roles,including the clearance of macromolecular waste and the trafficking of immune cells.Notably,aquaporin 4-mediated glymphatic transport,crucial for maintaining neural homeostasis,becomes disrupted during the aging process and is further compromised in the pathogenesis of AD and PD.Functional meningeal lymphatic vessels,which facilitate the drainage of cerebrospinal fluid into the deep cervical lymph nodes,are integral in bridging the central nervous system with peripheral immune responses.Dysfunction in these meningeal lymphatic vessels exacerbates pathological trajectory of the age-related neurodegenerative disease.This review explores modulatory influence of the glymphatic system and meningeal lymphatic vessels on the aging brain and its associated neurodegenerative disorders.It also encapsulates the insights of potential mechanisms and prospects of the targeted non-pharmacological interventions.

Meningeal lymphatic vasculature,a general target for glioblastoma therapy?

Glioblastoma(GBM)causes nearly universal mortality as a result of the failure of conventional therapies including surgical resection,targeted radiation therapy,and chemotherapy.An increasingly important treatment option is combining immunotherapy with other therapies in both preclinical and clinical studies.The central nervous system(CNS)has been historically considered an immune privileged area,but increasing evidence,including the recent rediscovery of meningeal lymphatic vessels(MLVs),has overturned this notion.MLVs are populated by multiple immune cells and connect the CNS to the periphery by draining cerebrospinal fluid with soluble CNS antigens and immune cells into cervical lymph nodes.In the past few years,more and more studies have indicated that MLVs are involved in the regulation of inflammation and the immune response in the pathogenesis of various CNS diseases including GBM.Here,we explore the critical interlinkages between MLVs and GBM therapies including chemotherapy,radiotherapy and immunotherapy,and propose the meningeal lymphatic vasculature as a general target for GBM therapy.