Figure 1.

Distribution of bacterial DNA in temporal arteries. Tissue sections were probed with fluorescently labeled oligonucleotide probes against bacterial DNA (green). Sections were counterstained with DAPI (blue) and Concanavalin A (red) to delineate nuclei and glycoproteins, respectively. Sections were scanned by confocal microscopy. In a control temporal artery (A), bacterial DNA is scattered throughout the media, with select examples highlighted by green arrows. Notably, no/negligible bacterial DNA staining is apparent in the lumen or intima (A, bar graph). The green channel emitted from the internal elastic lamina is a result of autofluorescence. In a temporal artery with histopathological evidence of GCA (B), bacterial DNA is scattered throughout the media and at a higher mean intensity than control (bar graph). Arterial layers are more disorganized and less distinct compared to a control temporal artery, as evidenced by weak autofluorescence and less distinct internal elastic lamina. There is an absence of bacterial DNA at the external edge of a GCA-involved temporal artery specimen (C, bar graph).