TLR4 and cerebral cavernous malformation: The molecular pathways involved in CCM development include the kruppel-like factor (KLF)2/4 pathway, endothelial-to-mesenchymal transition, RhoA/ROCK/phospho myosin light chain (pMLC), and, more recently, toll-like receptor 4 (TLR4) signaling through gut microbiome composition [3,9,11–14].