Abstract Body (Do not enter title and authors here): Cerebral small vessel disease is a common form of vascular dementia, where dysfunctional endothelial cells (ECs) lead to white matter changes, an early disease feature. EC dysfunction has been established as an early event in the pathogenesis of SVD, occurring before blood-brain-barrier (BBB) breakdown. In this context, identifying novel genes associated with EC dysfunction will help understand the role of ECs in BBB integrity.
It has become apparent that autophagy is associated with the pathophysiology of neurodegenerative and vascular disease, however, the role of autophagy in endothelial barrier function in the BBB is unclear. Mounting evidence shows that autophagic flux within the endothelium is essential in maintaining vascular function, whereas defective autophagy within endothelial cells can promote a pro-inflammatory phenotype. We previously demonstrated a pivotal role for the centriolar protein TCHP in linking EC function with the control of autophagy, showing that the depletion of TCHP in ECs impairs migration and sprouting and triggers cellular inflammation. We then generated endothelial-specific knockout mice for Tchp (Tchp^EC). The analysis of the permeability of the ECs isolated from the brain of Tchp^EC mice and human brain microvascular ECs with Tchp knockdown by ECIS^® revealed an impaired barrier function associated with the knockout of Tchp (unpaired t-test, p=0.0089, p<0.0005). Furthermore, Tchp^EC mice administered with the fluorescently labelled tracer dextran presented a higher tracer accumulation in the brain than WT mice (unpaired t-test, p=0.0352), demonstrating a loss of BBB integrity, further investigated by MRI scan that confirmed an impairment of BBB in the hippocampus (unpaired t-test, p=0.0371).
RNA sequencing demonstrated the activation of chemokine signalling pathways and matrix-metalloproteinases in ECs from Tchp^EC mice (unpaired t-test, p= 0.0348). Gelatine zymography confirmed the increased production and activity of MMP9 in TCHP knockout ECs (unpaired t-test, p=0.0218). Furthermore, immunohistochemistry demonstrated that TCHP knockout affects tight junction integrity (unpaired t-test, p=0.0317). Finally, laser speckle contrast imaging demonstrated that Tchp knockout affects cerebral blood flow in Tchp^EC mice (unpaired t-test, p= 0.0473).
In conclusion, our data suggest that TCHP-mediated defective autophagy in ECs could lead to inflammation and impaired BBB integrity.