Effect of acute Chlamydia pneumoniae infection on lipoprotein metabolism in NIH/S mice

Chlamydia pneumoniae is a well-known cause of respiratory infections, globally. Chronic C. pneumoniae infection has been associated with atherosclerosis. The aim of the present study was to investigate the effects of acute C. pneumoniae infection on serum lipid levels and some regulatory proteins/enzymes in NIH/S mice. Female mice (n = 30) were intranasally infected with 5.3*10 5 inclusion forming units (IFU) of C. pneumoniae and control mice (n = 30) were inoculated with buffer. Six uninoculated mice at day 0 and then six mice from each group 3, 6, 9, 14 and 20 days post-inoculation were killed and serum samples were collected for analysis. Successful infection was confirmed by IgG response to C. pneumoniae and positive Chlamydia cultivation from the lungs. Serum triglycerides and total cholesterol, as well as the activities of hepatic lipase (HL), lecithin-cholesterol acyltransferase (LCAT) and phospholipid transfer protein (PLTP) and the concentration of lipopolysaccharide-binding protein (LBP) were analyzed. In C. pneumoniae infected mice, a minor change in triglyceride (corrected p-value 0.020) levels was observed 9 days post-infection (p.i.). LCAT activity declined remarkably, and the lowest activities were measured on day 9 p.i. (67% from the baseline value). HL and PLTP activities did not differ from those in the control group during the whole experimental period. There was a 2.5-fold increase in the serum LBP concentration owing to the C. pneumoniae infection 9 days p.i. The data indicate that acute C. pneumoniae infection, although clinically almost asymptomatic, causes small, transient changes in serum total lipids and some key proteins involved in lipoprotein metabolism in mice.