Increased expression of osteopontin in brain arteriovenous malformations

The precise mechanisms responsible for the development and growth of intracranial arteriovenous malformations (AVMs) remain unclear. Osteopontin (OPN) is a phosphorylated glycoprotein with diverse functions. This study aimed to analyze the expression of OPN in human brain AVMs.

The AVM nidus was surgically obtained from patients with AVM, whereas control brain artery specimens were surgically obtained from patients with epilepsy. Reverse transcription-polymerase chain reaction (RT-PCR) was used to examine the expression of OPN mRNA in biopsy specimens. OPN protein expression was localized by immunohistochemistry. The statistical differences between different groups were assessed by two-way analysis of variance (ANOVA).

We analyzed 36 brain AVM specimens and 8 control brain artery specimens. Eleven patients with brain AVM received embolization treatment, and five underwent gamma knife radiotherapy before resection. Nineteen patients with brain AVM had a history of hemorrhage from AVMs. The expression of OPN mRNA was significantly higher in AVMs than that in the control specimens (25.76 ± 2.71 vs. 21.46 ± 2.01, P < 0.01). There was no statistically significant difference in the extent of OPN mRNA expression between the AVM group with and that without history of hemorrhage (26.13 ± 2.45 vs. 25.34 ± 2.99) or gamma knife radiotherapy (24.39 ± 2.10 vs. 24.53 ± 1.85). However, the difference between the AVM group with and that without embolization treatment history was statistically significant (24.39 ± 2.10 vs. 28.80 ± 1.13, P < 0.01). In the group with gamma knife radiotherapy history, OPN expression was found in arteries with early-stage radio-effect.

OPN may contribute to the vascular instability of brain AVMs. It may play an important role in the pathophysiological process related to embolization treatment.