Effect of combined hirudin treatment and PAR-2 deficiency. (A) Survival of LPS-treated PAR-2^+/+ mice with saline (solid line; n = 10), LPS-treated PAR-2^+/+ mice with hirudin (dashed line; n = 17), and LPS-treated PAR-2^–/– mice with hirudin (dotted line; n = 17). Hirudin statistically increased the survival time of PAR-2^+/+ mice (P = .0001) and PAR-2^–/– mice (P = .0001) compared with saline-treated PAR-2^+/+ mice. The difference in survival between PAR-2^+/+ and PAR-2^–/– mice treated with hirudin is also statistically significant (P = .037). (B) LPS-induced IL-6 expression (8 hours) in PAR-2^+/+ and PAR-2^–/– mice treated with either saline or hirudin. Data are shown as mean ± SE (more than 6 mice per group).