Figure 4.

Increased SMA-immunostaining and collagen deposition 20 weeks after radiation is abrogated by GRP blockade. A: Normal SMA immunostaining (red) in sham plus PBS lung occurs in airway and vascular smooth muscle. In subpleural lung (photomicrographs for ImageJ), a few small blood vessels are present. B: Mice exposed to radiation plus PBS have widespread, patchy SMA⁺ cells throughout the alveolar interstitium (white arrows). C: In radiation plus 77427 mice, SMA immunostaining is mostly restricted to normal small blood vessels. D: Normal trichrome staining (blue to purplish blue) in sham plus PBS lung occurs around airways and blood vessels. In the subpleural region shown here and used for ImageJ analysis, blue outlines of small blood vessels are visible (black arrows). E: Mice exposed to radiation plus PBS have collagen deposition in the alveolar interstitium (some blue to purplish blue interstitium, white arrows), as well as blue outlines of small blood vessels (black arrows). F: In radiation plus 77427 mice, collagen is mostly restricted to small blood vessels (black arrows). G: Quantitative image analysis was performed as detailed in Materials and Methods. For both SMA and trichrome, ^∗P < 0.0001 for radiation plus PBS versus sham plus PBS; ^†P < 0.001 for radiation plus PBS versus radiation plus 77427. Asterisks in A and C indicate pleural surface. Scale bars: 25 μm (A–F). V, blood vessel.