Most publications on the relationship between infection with Chlamydia pneumoniae and coronary heart disease (CHD) propose an association, but negative studies are also reported. Seroepidemiological studies vary in the use of different serological methods, different cutoff limits, different sampling times in relation to acute cardiac events, and different clinical stages of CHD. We wanted to compare three different commercially available methods for measuring Chlamydia antibodies to see how the choice of method influenced the prevalence of seropositive individuals in CHD patients and in healthy individuals and to see if sampling time in relation to an acute cardiac event or the stage of atherothrombotic disease influenced the results. Blood samples from 197 CHD patients and 197 individually matched healthy control individuals were tested at baseline and after 6 months; the mean age was 55 years in both groups, and 18% were women. Among the CHD patients, 166 were included at a median of 16 days after an acute cardiac event and 31 had chronic disease with the latest acute event being >3 months earlier. The difference in prevalence of antibodies between the CHD patients and the healthy controls was significant when Chlamydia lipopolysaccharide antibodies were measured, while no significant differences between the study groups were observed by the two methods detecting Chlamydia pneumoniae major outer membrane protein antibodies. The number of seropositive individuals was quite similar at inclusion and 6 months later, and no significant differences were observed between patients with a recent cardiac event and those with a more remote cardiac event. We conclude that the choice of serological method is of major importance when evaluating a possible relationship between C. pneumoniae and CHD.The old hypothesis that atherosclerosis could be caused by infectious agents has received new attention during the last 15 years, and Chlamydia pneumoniae is one of the main pathogens under suspicion. Since Saikku et al. (31) proposed an association between C. pneumoniae and coronary heart disease (CHD), many reports from different countries have been published, with diverging results (10,11,14,17,25,37). Although some investigations are based on direct immunofluorescence or PCR demonstrating C. pneumoniae in situ in the atherosclerotic plaque, most studies are based on serology, using different methods to detect human antibodies against the organism. Two basic methods are used: microimmunofluorescence tests (MIF) or enzyme immunoassays (EIA and ELISA techniques). Some tests detect antibodies to the species-specific major outer membrane proteins (MOMP), and some detect antibodies to the chlamydia lipopolysaccharide (LPS), which is common to Chlamydia pneumoniae, Chlamydia trachomatis, and Chlamydia psittaci. Furthermore, the titer end points used as cutoff values for seropositivity when comparing various groups differ in various studies.The aim of the present study was to compare three different, commonly used methods for measuri...

Summary Background:  Obese patients are at high risk of developing cardiovascular disease. Several studies suggest obesity as an independent risk factor. Adipose tissue is now accepted as an endocrine organ that produces and secretes a variety of cytokines, hormones and other metabolic players involved in the pathogenesis of atherosclerosis. Among this versatile group of mediators and effectors of inflammation and atherothrombosis, we have studied the expression of matrix metalloproteinase‐9 (MMP‐9), tissue inhibitor of metalloproteinase‐1 (TIMP‐1), plasminogen activator inhibitor‐1 (PAI‐1), interleukin‐18 (IL‐18) and interleukin‐6 (IL‐6). All these markers, in their circulatory form, have been associated with cardiovascular disease. However, there is no much data available on their expression in adipose tissue in human subjects with and without cardiovascular disease. Material and methods:  We successfully isolated RNA from subcutaneous fat biopsies of 61 patients with or without cardiovascular disease. We then measured the RNA expression of MMP‐9, TIMP‐1, PAI‐1, IL‐18 and IL‐6 with Real‐Time PCR, using relative quantification. Results:  Albeit not statistically significant, all inflammatory mediators – except IL‐18 – were highly expressed in patients with cardiovascular disease (n = 16) compared with those without (n = 45). Pooling the gene expression data, trying to capture the overall inflammatory activity in adipose tissue in a score system, we observed a highly significant association with CVD. Conclusions:  Trying to capture the overall inflammatory activity, in addition to the mass of adipose tissue, could provide useful hints towards a pathogenetic link between obesity and presence of cardiovascular disease.

We have investigated the effect of fish oil supplementation on the association between serum non-esterified fatty acid (NEFA) pattern and atherosclerotic activity. We studied correlations between serum non-esterified very long-chain eicosapentaenoic (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) and biochemical markers of endothelial activation before and after 18-months intervention with fish oil supplementation. The fish oil supplementation consisted of 2.4 g of EPA and DHA per day, with corn oil as placebo. Elderly men ( n =171) with high risk for coronary heart disease were divided into four intervention groups in a factorial design: fish oil supplementation ( n =44), dietary intervention ( n =42), fish oil supplementation+dietary intervention ( n =47) or placebo ( n =38). The composition of fasting NEFA was analysed before and after intervention by GLC. Circulating endothelial markers were analysed by ELISA. A statistically significant positive correlation between the change in serum non-esterified DHA and soluble vascular cell adhesion molecule-1 (sVCAM-1) was found in the pooled group that received fish oil supplementation ( n =91; Spearman's correlation coefficient r =0.24, P =0.02). No such correlation was found in the pooled group without fish oil supplementation ( n =80). Furthermore, there was a significant negative correlation between the change in serum non-esterified EPA and the relative change in sVCAM-1 in the group that did not receive fish oil supplementation ( r =-0.34, P =0.002). No such correlation was found in the group with fish oil supplementation. We conclude that large increase in serum non-esterified EPA and DHA, which can only be attained by supplementation, might increase inflammation in vascular endothelium. A moderate dietary increase in fish oil intake may, however, have an effect on decreasing inflammatory markers.

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Our results may indicate that C. pneumoniae contributes to increased inflammation in CHD, and that this contribution is even more pronounced when present in combination with H. pylori IgA antibodies.

In summary, we demonstrated an association between Chlamydia LPS IgA seropositivity and elevated levels of IFNgamma, IL-10, TNFalpha, sVCAM-1 and sE-selectin in CHD patients that might indicate persistent Chlamydia infection and a proinflammatory state. On the other hand, C. pneumoniae MOMP antibodies were not associated with elevated inflammatory markers and might merely be indicative of past infection, possibly with successful microbe clearance.

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