Figure 2

Plasma IL-18 levels and their correlations with measures of atherosclerotic lesion severity. (a) Plasma IL-18 levels were measured at three time points: 4 weeks before virus inoculation of the SIV-positive group, 4 weeks after virus inoculation of the SIV-positive group, and at the time of killing. IL-18 levels were significantly higher among SIV-infected animals than uninfected animals at the 4-week postinfection time point (P<0.02). SIV positive, animals assigned to SIV-infected group; SIV negative, animals assigned to uninfected control group. (b) Plasma IL-18 levels measured at the 4-week preinoculation time point (baseline) were significantly higher for two animals than for other study group animals (P<0.04). SIV positive, animals assigned to SIV-infected group; SIV negative, animals assigned to uninfected control group. (c) Plasma IL-18 levels measured 4 weeks after virus inoculation differed significantly between the SIV-infected and uninfected control groups (P<0.02) due to infection-associated increases in circulating IL-18 among animals of the SIV-infected group. SIV positive, animals assigned to SIV-infected group; SIV negative, animals assigned to uninfected control group. (d) All significant distinctions in plasma IL-18 levels were lost at the 9-week postinfection time point, corresponding to the time of killing. SIV positive, animals assigned to SIV-infected group; SIV negative, animals assigned to uninfected control group. (e) Plasma IL-18 levels 4 weeks before virus inoculation (baseline) correlated significantly with carotid atherosclerotic plaque cross-sectional area at the time of necropsy (P<0.001, R=0.946). (f) Plasma IL-18 levels 4 weeks before virus inoculation (baseline) correlated significantly with atherosclerotic plaque cross-sectional area at the common iliac bifurcation at the time of necropsy (P<0.01, R=0.789). (g) Plasma IL-18 levels 4 weeks before virus inoculation (baseline) correlated significantly with atherosclerotic plaque cross-sectional area in the cranial abdominal aorta at the time of necropsy (P<0.01, R=0.747). (h) Plasma IL-18 levels 4 weeks before virus inoculation (baseline) correlated significantly with extent of CD3+ cell infiltration in the most severely affected vessel per animal at the time of necropsy (P<0.001, R=0.835). (i) Plasma IL-18 levels 4 weeks before virus inoculation (baseline) correlated significantly with extent of CD68+ signal area in the most severely affected vessel per animal at the time of necropsy (P<0.001, R=0.847).