Tbx1 alleviated hepatic encephalopathy by promoting meningeal lymphangiogenesis and drainage of senescent astrocytes via a CCL21-dependent manner

Aim Emerging evidence suggests that meningeal lymphatic vessels (mLVs) are involved in intra-cranial drainage including senescent astrocytes in CNS disorders. Enhanced lymphangiogenesis is reported in hepatic encephalopathy (HE), when astrocyte senescence is potentially related to irreversible cognitive decline in HE. Therefore, based on single-cell RNA sequencing (scRNA-seq) of meninges, we aim to investigate the role of mLVs in HE. Methods scRNA-seq is performed on meninges from the rat model of HE induced by common bile duct ligation (BDL). mLVs and senescent astrocytes are visualized by immunofluorescence (IF) staining. To trace the drainage pathway, fluorescent labeled senescent astrocytes are injected into hippocampus. Intra-cranial lymphatic drainage efficiency is evaluated by OVA-FITC distribution in deep cervical lymph nodes (dCLNs). Results scRNA-seq analysis suggests significant lymphangiogenesis and glial cell migration in HE. In vivo studies demonstrate that HE rats exhibit significant hippocampal accumulation of senescent astrocytes, which are further detected in mLVs and dCLNs. Exogenous tracer confirms the direct drainage of senescent astrocytes from hippocampus to dCLNs through mLVs. Ligation of dCLNs impedes senescent astrocyte efflux via mLVs and exacerbates HE. Tbx1 overexpression enhances meningeal lymphangiogenesis and senescent astrocyte drainage, improving cognitive impairment and neuroinflammation, which are partially reversed by CCL21 neutralization. Conclusion Our findings demonstrate that mLVs mediate drainage of hippocampal senescent astrocytes to dCLNs in HE rats, which plays a vital role in ameliorating cognitive decline and neuroinflammation in HE. Tbx1 emerges as a novel regulator of mLVs, attenuating HE by promoting senescent astrocyte clearance in a CCL21-dependent manner.