Figure 11. Mmp-9 deficiency in lung parenchymal cells led to reduced mortality following H1N1 infection.

Bone marrow (BM) transplantation studies were performed to generate Mmp-9^–/– BM-chimeric mice. All groups were infected with an LD₈₀ H1N1 inoculum via the intranasal route and survival or moribundity was monitored daily for 14 days. (A) Kaplan-Meier survival curves for WT recipients with WT BM (n = 11) versus WT recipients with Mmp-9^–/– BM (n = 10). (B) Kaplan-Meier survival curves for Mmp-9^–/– recipients with Mmp-9^–/– BM (n = 5) versus Mmp-9^–/– recipients with WT BM (n = 13). A Gehan-Breslow-Wilcoxon analysis was performed on the groups having the same recipient genotype. P = 0.671 (A) and P = 0.907 (B).