Figure 4.

Pulmonary knockdown of MMP-9 aggravates sepsis-induced oxidative stress in lung tissues. Mice were intratracheally injected with MMP-9 siRNA or control siRNA (1 mg/kg). Forty-eight hours later, mice were subjected to CLP or sham surgery. (a) MDA levels in lung tissues. (b, c) 8-OHdG immunoreactivity (green) was measured as the index of oxidative DNA damage. Nuclei were counterstained with 4′,6-diamidino-2-phenylindole (DAPI) (blue). Areas in white boxes were shown enlarged (b). Original magnification, ×200. Scale bars correspond to 50 μm. (c) The ratio of 8-OHdG-positive cells to the total cell number (%). Data are presented as the mean ± SEM (n = 7). ^∗p < 0.05 and ^∗∗p < 0.01 vs. the sham+control siRNA group. ^##p < 0.01 vs. the CLP+control siRNA group. 8-OHdG: 8-hydroxy-2′-deoxyguanosine.