Alternatively-Spliced Extra Domain A of Fibronectin Promotes Acute Inflammation and Brain Injury After Cerebral Ischemia in Mice

• Published in: Stroke (1970) 2012-05, Vol.43 (5), p.1376-1382
• Main Authors: Khan, Mohammad Moshahid, Gandhi, Chintan, Chauhan, Neelam, Stevens, Jeff W., Motto, David G., Lentz, Steven R., Chauhan, Anil K.
• Format: Article
• Language: English
• Subjects: Alternative Splicing - genetics; Animals; Biological and medical sciences; Brain Injuries - blood; Brain Injuries - etiology; Brain Injuries - physiopathology; Brain Ischemia - blood; Brain Ischemia - complications; Brain Ischemia - physiopathology; Cyclooxygenase 2 - physiology; Cytokines - physiology; Encephalitis - blood; Encephalitis - etiology; Encephalitis - physiopathology; Fibronectins - blood; Fibronectins - genetics; Fibronectins - physiology; Male; Medical sciences; Mice; Mice, Inbred C57BL; Models, Animal; Neurology; Neuropharmacology; Neuroprotective agent; NF-kappa B - physiology; Pharmacology. Drug treatments; Protein Structure, Tertiary - genetics; Time Factors; Toll-Like Receptor 4 - physiology; Up-Regulation - physiology; Vascular diseases and vascular malformations of the nervous system
• ISSN: 0039-2499; 1524-4628
• DOI: 10.1161/STROKEAHA.111.635516

The fibronectin isoform containing the alternatively spliced extra domain A (EDA(+)-FN) is normally absent from the circulation, but plasma levels of EDA(+)-FN can become markedly elevated in several human pathological conditions associated with inflammation including ischemic stroke. It remains unknown whether EDA(+)-FN contributes to stroke pathogenesis or is simply an associative marker. Several in vitro studies suggest that EDA(+)-FN can activate Toll-like receptor 4, an innate immune receptor that triggers proinflammatory responses. We undertook a genetic approach in mice to investigate the ability of EDA(+)-FN to mediate inflammatory brain damage in a focal cerebral ischemia/reperfusion injury model. We used genetically modified EDA(+/+) mice, which constitutively express EDA(+)-FN. Extent of injury, neurological outcome, and inflammatory mechanisms were assessed after 1-hour cerebral ischemia/23-hour reperfusion injury and compared with wild-type mice. We found that EDA(+/+) mice developed significantly larger infarcts and severe neurological deficits that were associated with significant increased neutrophil and macrophage infiltration as quantitated by immunohistochemistry. Additionally, we found upregulation of nuclear factor-κB, cyclo-oxygenase-2, and inflammatory cytokines tumor necrosis factor-α, interleukin-1β, and interleukin-6 in the EDA(+/+) mice compared with wild-type mice. Interestingly, increased brain injury and neurological deficits were largely abrogated in EDA(+/+) mice by treatment with a specific Toll-like receptor 4 inhibitor. These findings provide the first evidence that EDA(+)-FN promotes inflammatory brain injury after ischemic stroke and suggest that the elevated levels of plasma EDA(+)-FN observed in chronic inflammatory conditions could worsen injury and outcome in patients after acute stroke.