Matrix metalloproteinase-9 and tissue inhibitors of metalloproteinases 1 in influenza-associated encephalopathy.

Matrix metalloproteinase-9 (MMP-9) and tissue inhibitors of metalloproteinases 1 (TIMP-1) play important roles in the function of the blood-brain barrier. Serum MMP-9 and TIMP-1 concentrations were determined in influenza virus infection with or without neurologic complications. Our results suggest that an imbalance between MMP-9 and TIMP-1 damages the blood-brain barrier and promotes febrile seizure or encephalopathy in influenza virus infection.