Immunolocalization of platelet-derived growth factor receptor-β (PDGFR-β) and pericytes in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

Lucinda J.L Craggs,Raj N Kalaria,Richard Fenwick,Arthur E Oakley,Masafumi Ihara

doi:10.1111/nan.12188

Abstract

AimsCerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is identified by aggregates of NOTCH3 extracellular domain (N3ECD) along capillaries and the deposition of granular osmiophilic material (GOM). We assessed the pattern of distribution of pericytes in relation to N3ECD deposits in cerebral microvessels of CADASIL subjects.MethodsWe assessed post mortem brains from (n = 50) subjects with CADASIL, cerebral small vessel disease, and similar‐age cognitively normal and older controls. Immunohistochemical and immunofluorescent staining methods were used to study the distribution and quantify immunoreactivities of the platelet‐derived growth factor receptor‐β (PDGFR‐β) (for pericytes) and microvascular markers in the frontal cortex and white matter.Results PDGFR‐β antibody stained cells typical of pericytes in capillaries and small arterioles in both the grey and white matter. PDGFR‐β reactive pericytes adopted ‘crescent’ morphology wrapped closely around capillary walls readily evident in cross‐sections. We noted considerable overlap between PDGFR‐β and N3ECD imunoreactivities in capillaries. Quantitative analysis of PDGFR‐β immunoreactivity revealed significant differences in PDGFR‐β %A in CADASIL compared with young controls (P < 0.05). PDGFR‐β %A was further positively correlated with the basement membrane marker collagen IV (r = 0.529, P = 0.009), but was not associated with GLUT‐1, the marker for endothelial cells.ConclusionsOur results suggest increased expression of PDGFR‐β immunoreactive pericytes in cerebral microvessels in CADASIL compared with similar age controls. While we cannot confirm whether PDGFR‐β‐expressing pericytes produce N3ECD and hence GOM, our findings demonstrate that up‐regulation of pericyte‐like cells is associated with microvascular changes, including loss of vascular smooth muscle cells in CADASIL.

Highlights

PDGF receptor-β (PDGFR-β) antibody immunostained pericyte-like cells associated with capillaries of the smallest internal diameters (∼6 μm) and some pre-capillaries in both grey matter (GM) and white matter (WM) (Figure 1)
We observed PDGFR-β staining within the tunica media and adventitia of arterioles more frequently in CADASIL compared with small vessel disease (SVD), and found concomitant immunostaining for N3ECD alongside degeneration of vascular smooth muscle cells (VSMCs) in CADASIL arterioles, a change which was not observed in SVD or controls (Figure 4J–L)
We showed that there is an increase in PDGFR-β immunoreactivity associated with pericytes in CADASIL compared with similar age controls, with a similar trend in SVD compared with respective older controls

Summary

Introduction

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary stroke disorder, affecting over. Pericytes are located abluminal to endothelial cells within the basement membrane of capillaries, precapillary arterioles and post-capillary venules [8,9,10] They have multiple functions beyond contractile control of blood flow, providing paracrine signals during angiogenesis and some phagocytic activity. A study exploring cultured VSMCs derived from a CADASIL patient reported that there was a negative feedback mechanism between the expression of NOTCH3 and PDGFR-β [21], suggesting that NOTCH3 and PDGFR-β signalling may act antagonistically to control VSMC differentiation state Another recent study has further identified signature genes downstream of Notch activity in retinal pericytes and suggests that tight regulation of Notch signalling is crucial for pericyte survival [22]. In an effort to explore some of these mechanisms [2], we primarily aimed to localize and quantify the expression of PDGFR-β in CADASIL in relation to N3ECD and compare against similar age relevant controls

Methods

Results

Discussion