1101. GENE EXPRESSION IN INTRACRANIAL ANEURYSMS – COMPARISION ANALYSIS OF ANEURYSMAL WALLS WITH EXTRACRANIAL ARTERIES WITH RT-PCR AND IMMUNOHISTOCHEMISRTY
Authors: Dwarakanath Srinivas, MBBS, MS, MCh; Gaurav Tyagi, MCh; Vani Santosh, MD; Meera Purushottam, PhD; Sanjeev Jain, MD (Bangalore, India)
The walls of aneurysms have a different microscopic profile when compared to normal extracranial artery. The study was aimed on evaluating the gene expression levels of four genes in the intracranial aneurysm wall and comparing them with extracranial arteries. The analysis was done using real‑time polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC). Also a correlation of the differential genetic expression was done with various patient clinical and radiological factors.
The quantitative assessment of RNA levels was done with RT-PCR and was validated with IHC. The genes studied were Collagen 1A2 (COL1A2), Tissue inhibitor of metalloproteinase 4 (TIMP4), Cathepsin B (CTSB) and Alpha – 1 antitrypsin (alpha-1 AT). The analysis was done on 24 aneurysm sacs and superficial temporal/occipital artery samples from patients undergoing surgical clipping
The mean fold change of COL1A2 gene in aneurysm sample was 8.89, that of TIMP4 gene was 10.16, CTSB gene was 1.02 and alpha-1 AT was 1.46 when compared to normal control vessel on PCR. Upon semi quantitative IHC, COL1A2 was 94.44%, alpha-1 AT was 77.8% overexpressed, CTSB was positive in 50% and the expression of TIMP-4 was 94.4% under expressed in aneurysmal walls. There was no statistically significant correlation between patient profile and gene expression.
Upon RT-PCR and IHC analysis COL1A2 and alpha-1 AT genes were overexpressed, and CTSB gene was marginally overexpressed, and TIMP4 gene had equivocal expression in the aneurysmal sac when compared to normal extracranial vessel. This is the first of its kind study in Indian population with the largest sample size on live human patients.