The molecular basis of arteriovenous malformations (AVMs): Review of inflammation in AVM pathogenesis

Brain arteriovenous malformations (bAVMs) are vascular anomalies characterized by direct arterial to venous shunting without an intervening capillary bed, predisposing patients to intracranial hemorrhage and subsequent neurological morbidity and mortality. Evidence suggests that development and evolution of bAVMs are influenced by ongoing molecular and inflammatory processes. Chronic inflammation within the AVM microenvironment has emerged as a key driver of dysregulated angiogenesis, vascular instability, and hemorrhage risk. The objective of this review is to examine the molecular and cellular mechanisms through which inflammatory pathways contribute to AVM development, rupture, and treatment response. A comprehensive search of the Web of Science database was performed from database inception through September 2024. Following removal of duplicate articles, titles and abstracts were screened and full texts were reviewed for relevance. Experimental, translational, and clinical studies investigating inflammatory signaling pathways, immune cell involvement, molecular biomarkers, and therapeutic implications in AVMs were included. A total of 342 studies were included in the final review. Current evidence demonstrates that inflammatory signaling plays a central role in AVM pathobiology. Pro-inflammatory cytokines including interleukin-1β, interleukin-6, and tumor necrosis factor-α promote endothelial activation, leukocyte recruitment, and abnormal angiogenesis within the AVM nidus. Dysregulation of signaling pathways such as VEGF, TGF-β/BMP, NF-κB, Notch, and KRAS/MAPK-ERK contributes to extracellular matrix degradation, vascular remodeling, and vessel fragility. Infiltration by macrophages and neutrophils further amplifies inflammatory cascades through the release of matrix metalloproteinases and reactive oxygen species, increasing rupture risk. In addition to its pathogenic role, inflammation also contributes to success of AVM obliteration using stereotactic radiosurgery through radiation-induced endothelial injury, immune cell recruitment, and progressive vascular fibrosis. Inflammation is a fundamental component of AVM formation, progression, and therapeutic response. Targeting these pathways, in combination with surgical or radiosurgical interventions, may offer new opportunities for improving AVM management and improving approaches in cerebrovascular neurosurgery.