N J Wald, M R Law, J K Morris, X Zhou, Y Wong, M E Ward et al
Wald N J, Law M R, Morris J K, Zhou X, Wong Y, Ward M E et al.
Chlamydia pneumoniae infection and mortality from ischaemic heart disease: large prospective study
BMJ 2000; 321 :204
doi:10.1136/bmj.321.7255.204
Relation of C pneumoniae infection and ischaemic heart disease cannot be solved serologically
Relation of C pneumoniae infection and ischaemic heart disease cannot be solved serologically
Two papers on inflammation and coronary heart disease are of interest, particularly to
those working on the possible role of Chlamydia pneumoniae in atherosclerosis. Wald et al
showed no association between IgG or IgA antibody to C pneumoniae and death from
ischaemic heart disease. [1] Conversely, Danesh et al showed that 40% of men who had died
of coronary heart disease or had a non-fatal myocardial infarction and 33% of those without
such disease had high concentrations oflgG antibody to C pneumoniae.[2] These
observations seem to put a damper on investigations into the role of C pneumoniae in
coronary heart disease. But should they?
C pneumoniae DNA exists in a large proportion of atheromatous lesions of major
arteries. [3] The problem is that the relation between the existence of serum antibody and the
presence or absence of C pneumoniae throughout the arterial tree will probably never be
known. One study having some bearing on this was by Kuo et al. [4] Subjects who had
coronary atheromatous lesions had a range of C pneumoniae IgG titres, but such antibody
was not associated directly with the finding of C pneumoniae in these arteries. In fact,
subjects without antibody were apparently more likely to have evidence of C pneumoniae in atheromatous coronary arteries than those with high antibody titres.
It might be expected that some subjects who do not have changes or C pneumoniae in
coronary arteries have C pneumoniae organisms in other vessels that are responsible for antibody production. There should be no
difficulty in defining the relation between antibody status and C pneumoniae DNA in
circulating monocytes, such infected cells occurring in a large proportion of middle aged
people, irrespective of whether they have had a coronary event.[3] Even this would not get to
the core of the problem, however, because the relation between C pneumoniae DNA in
circulating monocytes and that in atheromatous arteries--the coronaries in particular--is
unknown. The complexities are such that it seems unwise to draw firm conclusions about the
role of C pneumoniae in coronary heart disease from the largely unsupportive
seroepidemiological investigations.[l ] [2]
The negative seroepidemiological findings are ironic because the first study in which C
pneumoniae was related to coronary heart disease was serologically based.[5] Without it, and
without the mental priming that C pneumoniae might have some role, the existence of C
pneumoniae in atherosclerotic tissue might well have gone unnoticed. That it occurs so often
in such tissue seems remarkable, and the reason for this still needs explaining. This issue
cannot be solved serologically.
David Taylor-Robinson
emeritus professor
Department of Genitourinary Medicine, Division of Medicine, Imperial College School of
Medicine, St. Mary's Campus, London W2 1NY
dtr@vache.freeserve.co.uk
1 Wald NJ, Law MR, Morris JK, Zhou X, Wong Y, Ward ME. Chlamydia pneumoniae
infection and mortality from ischaemic heart disease: large prospective study. BMJ
2000;321 :204- 7. (22 July. )
2 Danesh J, Whincup P, Walker M, Lennon L, Thomson A, Appleby P, et al.
Chlamydia pneumoniae IgG titres and coronary heart disease: prospective study and meta-
analysis. BMJ 2000;321:208-12. (22 July.)
3 Taylor-Robinson D, Thomas BJ. Coronary heart disease and Chlamydia pneumoniae
DNA in blood mononuclear cells. J Am Coll Cardiol 2000;36:657-8.
4 Kuo CC, Shor A, Campbell LA, Fukushi H, Paton L T , Grayston JT. Demonstration of Chamydia pneumoniae in atherosclerotic lesions of coronary arteries. J Infect Dis
1993;167:841-9.
5 Saikku P, Leinonen M, Mattila K, Nieminen MS, Makela PH. Serologic evidence of an association of a novel Chlamydia, TWAR, with chronic coronary heart disease and acute myocardial infection. Lancet 1988;22:983-5.
Competing interests: No competing interests