RESPIRATORY-INFECTION IN LIPID-FED RABBITS ENHANCES SUDANOPHILIA AND THE EXPRESSION OF VCAM-1

The pathogenesis of atherosclerosis has been related to infection of t he arterial wall, but it is not clear whether this occurs before or af ter the development of lipid-containing lesions, Respiratory bacterial infection increases the expression of vascular cell adhesion molecule -1 (VCAM-1). We therefore examined whether a similar infection would e nhance atherosclerosis in New Zealand White rabbits fed chow supplemen ted by 15% (w/w) egg yolk for 50 days, Rabbits with naturally acquired respiratory infection by Pasteurella multocida, pathogen-free (SPF) a nimals infected by P. multocida in the laboratory, and age matched SPF rabbits maintained in a disease-free environment were used, Endotheli al cells expressing VCAM-1 in the aorta between intercostal arteries 3 and 5 were identified using anti-VCAM-1 (Rb1/9) and an alkaline-phosp hatase-linked secondary antibody and quantified in Hautchen preparatio ns, The remainder of the aorta was stained with Sudan TV to show Lipid deposition, The expression of VCAM-1 (mean +/- SEM per 10,000 cells) was 22 +/- 8 (n = 5) in the lipid-fed SPF rabbits, significantly diffe rent from that in the lipid-fed rabbits with naturally occurring infec tion (190 +/- 51 (n = 5)) or from rabbits infected in the laboratory ( 106 +/- 25 (n = 5)), The extent of Sudanophilia was significantly grea ter in the naturally infected rabbits (8.3 +/- 1.2%) or infected SPF r abbits (10.3 +/- 1.8%) than in the SPF rabbits (2.7 +/- 0.8%; P < 0.05 ). Antibiotic treatment in naturally infected rabbits reduced the numb er of cells expressing VCAM-1 and the extent of the Sudanophilia to ba seline levels, Thus, Sudanophilia is enhanced by bacterial infection i n rabbits fed egg yolk and is associated with a significant increase i n VCAM-1.