Figure 2

TLR4- MyD88 signaling in macrophage may regulate cathepsin L activity and vascular remodeling. Common carotid arteries were injured by a 0.4 mm guide wire plus external carotid artery ligation. (A,B) Arterial mRNA levels for cathepsin L was measured by reverse transcription polymerase chain reaction and normalized to 18S transcript levels 3 d following wire injury. Relative mRNA levels compared with the uninjured carotid artery are displayed (n = 4–6). (C) Arterial enzyme activity for cathepsin L was measured by a fluorescence-based assay and normalized to tissue extract protein concentration at d 7 following wire injury. Cathepsin L activity of the injured and uninjured carotid arteries from wild-type, Lyz-TLR4−/− and Lyz-MyD88−/− mice are displayed (n = 4 at each time point). (D-F) Representative hematoxylin and eosin stained sections of carotid arteries from MyD88^loxp/L^oxp mice (n = 6) and Lyz-MyD88^−/− mice (n = 8) are shown. The ratios of intima and media area and vessel medial size were quantified by planimetry at 28 d. The white arrows indicate internal elastic lamina. The black arrows indicate luminal side of the artery. (G) Carotid arteries at 28 d after injury that were immunostained for mouse cathepsin L. The arrows indicate cells stained positive for cathepsin L. Representative hematoxylin and eosin stained and immunofluorescent-stained sections are shown. Data represent the means ± SEM. *P <0.05, **P <0.01 versus respectively controls. Scale bar represents 100 µm.