Anti-TNFA (TNF-α) treatment abrogates radiation-induced changes in vascular density and tissue oxygenation

Ionizing radiation significantly alters the structure and function of microvasculature, which regulates delivery of oxygen to brain tissue. Previous experimental and modeling studies have shown that tissue oxygenation patterns are significantly different in irradiated normal tissue compared to age-matched controls, and the differences are apparent as early as 3 days postirradiation. However, oxygen delivery to irradiated tissue recovers within 6 months postirradiation. Changes in perfusion and oxygenation were studied in a bilaterally (both cerebral hemispheres) and unilaterally (only one hemisphere) irradiated mouse brain model at 6 and 24 h as well as 3, 7, 30, 60 and 120 days postirradiation. The results indicate that significant changes in the number of perfused vessels (as measured by fluorescent DiOC₇ staining) and anatomical vessels (as indicated by CD31 immunohistochemical staining) and tissue oxygenation (by immunohistochemical detection of a fluorescently conjugated monoclonal antibody to EF5) are most pronounced at 3 days postirradiation, while a degree of recovery is observed at later times. However, in the unilaterally irradiated animals, both irradiated and unirradiated (out-of-field) cerebral hemispheres showed similarly significant changes in oxygenation and/or perfusion compared to unirradiated controls. Anti-TNFA treatment inhibited radiation-induced local as well as abscopal effects in the brain tissue.