Correlation of ultrastructural changes of endothelial cells and astrocytes occurring during blood brain barrier damage after traumatic brain injury with biochemical markers of BBB leakage and inflammatory response

Focal cerebral contusion can be dynamic and expansive. It has been proved that subsequent expansive contusion is caused by brain parenchyma damage, especially BBB damage. We investigated a group of patients with traumatic brain injury. The patients (n=18) were divided into group I (n=7) of patients submitted to neurosurgery due to expansive contusion, and group II (n=11) of patients without surgery. Serum concentrations of NSE and S-100B protein were measured by electrochemiluminescence immunoassay, interleukin-6 (IL-6) was measured by chemiluminescent sequential immunometric assay and matrix metalloproteinases (MMP-9, MMP-2) were measured by immunoassays. Cortical biopsy specimens of brain were investigated by electron microscopy in patients with trauma brain injury submitted to neurosurgery. Biochemical investigation from first day up to third day after traumatic brain injury proved increased values of IL-6 (302.2+/-119.9 vs. 59.6+/-11.9 ng/l, p<0.02) and S-100B protein (3.064+/-1.064 vs. 0.649+/-0.182 microg/l, p<0.05) in patients with expansive lesion compared to patients without expansive contusion. Significantly higher levels of MMP-9 (150.4+/-28.46 vs. 74.11+/-13.16 ng/l, p<0.05) and of MMP-2 (814.5+/-126.3 vs. 523.1+/-25.28 ng/l, p<0.05) were found during first 3 days after admission in group I compared to group II. MMP-9 has also elevated in group II from lower values after admission (74.11+/-13.16 ng/l) up to high levels on the 10th day of hospitalization (225.1+/-49.35 ng/l). Ultrastructural investigation of endothelial cells and surrounded tissue revealed perivascular hemorrhage, increased pinocytic activity of endothelial cells, and cytotoxic edema of astroglial cells. Multivesical bodies were disclosed inside the endothelial cells. Higher levels of serum protein S-100B and IL-6 correlated with ultrastructural changes of endothelial cells, and with inflammatory response following TBI, respectively.