PURPOSE: The aim of this study was to determine whether a neutralizing
transforming growth factor-beta (TGFbeta) antibody can prevent radiation (RT)
induced lung injury.
METHODS AND MATERIALS: Fractionated and sham right lung irradiation in Fischer
344 rats was delivered to assess the radioprotective effect of the antibodies.
Animals were divided into the following groups: (1) control (sham RT, control
antibody 13C4); (2) RT (800cGy x 5)+13C4); (3) RT + 0.1 mg/kg 1D11 anti-TGFbeta
antibody; and (4) RT + 1 mg/kg 1D11 antibody. Antibodies were intraperitoneally
administered immediately after the last fraction of RT. Animals were sacrificed
at 6 and 26 weeks after irradiation. Lungs were assessed for histologic changes,
activation of macrophages, expression/activation of TGFbeta and its signal
transduction pathway.
RESULTS: At 6 weeks post-RT, there was a significant reduction in macrophage
accumulation (p = 0.041), alveolar wall thickness (p = 0.0003), and TGF-beta
activation (p = 0.032) in animals receiving 1.0 mg/kg 1D11 vs. in the control
group. However, at 6 weeks, the low dose of 1D11 antibody (0.1 mg/kg) failed to
produce any significant changes. At 6 months post-RT, radioprotection is apparent
for the group receiving 1.0 mg/kg 1D11, with activated macrophages (p = 0.037),
alveolar wall thickness (p = 0.0002), TGFbeta activation (p = 0.002) and its
signal transduction proteins (p < 0.05) compared with the control group.
CONCLUSIONS: Administration of a single dose of 1.0 mg/kg of the anti-TGFbeta
antibody 1D11 resulted in decreased morphologic changes, inflammatory response,
and reduced expression and activation of TGFbeta 6 weeks and 6 months after 40 Gy
to the right hemithorax. Targeting the TGFbeta pathway may be a useful strategy
to prevent radiation-induced lung injury.