Endoglin deficiency impairs stroke recovery

Abstract

Background and purpose: Endoglin deficiency causes hereditary hemorrhagic telangiectasia-1 and impairs myocardial repair. Pulmonary arteriovenous malformations in patients with hereditary hemorrhagic telangiectasia-1 are associated with a high incidence of paradoxical embolism in the cerebral circulation and ischemic brain injury. We hypothesized that endoglin deficiency impairs stroke recovery.

Methods: Eng heterozygous (Eng+/-) and wild-type mice underwent permanent distal middle cerebral artery occlusion (pMCAO). Pial collateral vessels were quantified before pMCAO. Infarct/atrophic volume, vascular density, and macrophages were quantified in various days after pMCAO, and behavioral function was assessed using corner and adhesive removal tests on days 3, 15, 30, and 60 after pMCAO. The association between ENG 207G>A polymorphism and brain arteriovenous malformation rupture and surgery outcome was analyzed using logistic regression analysis in 256 ruptured and 157 unruptured patients.

Results: After pMCAO, Eng+/- mice showed larger infarct/atrophic volumes at all time points (P<0.05) and showed worse behavior performance (P<0.05) at 15, 30, and 60 days when compared with wild-type mice. Eng+/- mice had fewer macrophages on day 3 (P=0.009) and more macrophages on day 60 (P=0.02) in the peri-infarct region. Although Eng+/- and wild-type mice had similar numbers of pial collateral vessels before pMCAO, Eng+/- mice had lower vascular density in the peri-infarct region (P=0.05) on day 60 after pMCAO. In humans, ENG 207A allele has been associated with worse outcomes after arteriovenous malformation rupture or surgery of patients with unruptured arteriovenous malformation.

Conclusions: Endoglin deficiency impairs brain injury recovery. Reduced angiogenesis, impaired macrophage homing, and delayed inflammation resolution could be the underlying mechanism.

Keywords: angiogenesis effect; macrophages; telangiectasia, hereditary hemorrhagic.

Figure 1. Behavior dysfunction

A. Quantification of the adhesive removal test from the right paw. *p=0.001 vs. WT on day 0; #: P=0.13 vs. WT on day 3 B. Quantification of the corner test on day 0 and day 3. *: P<0.001 vs WT on day 0. #: P=0.78 vs. WT on day 3. C. Quantification of the adhesive removal test from the right paw on days 15, 30 and 60 after pMCAO. *: P<0.05 vs. corresponding WT groups. D. Quantification of the corner test on days 15, 30 and 60. *: P<0.05 vs. corresponding WT group. D0, D3, D15, D30 and D60 are 0, 3, 15, 30 and 60 days, respectively, after pMCAO.

Figure 2. Infarct/atrophic volumes

A. Infarct volume on day 1. n=13 (Eng^+/−) and n=12 (WT mice). *: P=0.03. B. Infarct volume on day 3. #: P= 0.04. n= 7. C. Atrophic volume on day 60. *: P=0.03. n=7. Bars=2 mm.

Figure 3. CD68⁺ cells in the peri-infarct area

A. Coronal section showing the areas (squares) used for quantification. B. Representative images of CD68 antibody-stained (green) section. The nuclei were counterstained with DAPI (blue). Bar=50µm. C. Quantification of CD68⁺ cells in the peri-infarct area 3 (D3) and 60 days (D60) after pMCAO. *: P=0.009, #: P=0.02. N=10.

Figure 4. Pial collateral vessels at baseline and vessel density in the peri-infarct cortex

A. Representative photographs of collateral vessels of 3-week-old WT and Eng^+/− mice. Bar=1 mm. B. Quantification of collateral vessel number of 3-week-old mice (WT: N=6, Eng^+/−: N=6) and 11-week-old mice (WT: N=8, Eng^+/−: N=4). C. Representative images of CD31 antibody-stained sections. Bar=100µm. D. Quantification of vessel density. *P=0.05, N=6.