Chronic Chlamydia pneumoniae infection inpatients with symptomatic atherothrombosis


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Chronic Chlamydia pneumoniae infection inpatients with symptomatic atherothrombosis by P. Halfon, N. Limal, G. Penaranda, H. Khiri, D. Sene ,M. Andreu, J.M. Feryn, M. Rotily, R. Serra,J.C. Piette, P. Cacoub in Journal of Infection 2005

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Chronic Chlamydia pneumoniae infection inpatients with symptomatic atherothrombosis

  1. 1. ARTICLE IN PRESSJournal of Infection (2005) -, -e- Chlamydia pneumoniae infection inpatients with symptomatic atherothrombosisP. Halfon a,*, N. Limal b, G. Penaranda c, H. Khiri a, D. Sene b,M. Andreu b, J.M. Feryn a, M. Rotily d, R. Serra d,J.C. Piette b, P. Cacoub ba Virological Department, Alphabio Laboratory, 23 Rue de Friedland, 13006 Marseille, Franceb Internal Medecine Department, Pitie ´-Salpe `re Hospital, 91 Boul. de l’ho ˆtrie ˆpital,75013 Paris, Francec CDL Pharma, 23 Rue de Friedland, 13006 Marseille, Franced ´galite 92220 Bagneux, France Department of Statistics, Clinsearch, 1 Rue de l’e ´,Accepted 29 October 2005 KEYWORDS Summary Objectives: The aim of the present study was to search for an association Atherothrombosis; between chronic Chlamydia pneumoniae infection, indicated by elevated antibody titers Cardiovascular risk; against the pathogen, atherothrombosis and the occurrence of arterial ischemic events. Chlamydia Methods: We studied 52 patients presenting at baseline with at least one symptomatic pneumoniae; episode of atherothrombosis. A screening for fasting blood glucose and a lipid profile Anti-chlamydia was performed on all patients who had no known history of diabetes or hypercholester- treatment olemia. Results: The prevalence of IgG and IgA anti-C. pneumoniae antibodies at baseline was 90% (95% CI: 79e97) and 81% (67e90), respectively. Forty-two of the 52 patients (81%) experienced a new arterial ischemic event after a mean follow-up of 9 years [heart: 19 (37%); brain: 12 (23%); lower limbs: 8 (15%); and other: 13 (25%)]. Occurrence of a new arterial ischemic event was related to age (p ¼ 0.003), sex (p ¼ 0.009), and tobac- co smoking (p ¼ 0.06). Prevalences of IgA and IgG anti-C. pneumoniae were significantly higher in patients with atherothrombosis at baseline than that in controls. Conclusion: Our study confirmed the links between C. pneumoniae and atherothrombo- sis. However, neither IgA nor IgG antibodies for C. pneumoniae was a significant predic- tive factor for new ischemic arterial events in patients with atherothrombosis. ª 2005 The British Infection Society. Published by Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: þ33 4 91 25 41 00; fax: þ33 4 91 78 14 75. E-mail address: (P. Halfon).0163-4453/$30 ª 2005 The British Infection Society. Published by Elsevier Ltd. All rights reserved.doi:10.1016/j.jinf.2005.10.027
  2. 2. ARTICLE IN PRESS2 P. Halfon et al.Introduction including hypertension (blood pressure > 140/ 90 mm Hg), past history of smoking (0.5 pack-In addition to the well-established cardiovascular years), diabetes (treated by oral agent or insulinrisk factors such as hypercholesterolemia, hyper- for 1 year), and hypercholesterolemia (LDL cho-tension, and cigarette smoking, multiple additional lesterol 160 mg/dL, untreated). A screening forfactors have been suspected in both the develop- fasting blood glucose and a lipid profile was per-ment and progression of atherothrombosis.1 Chla- formed on all patients who had no known historymydia pneumoniae (C. pneumoniae)has been the of diabetes or hypercholesterolemia. A group offocus of research associating infection with athe- 56 healthy blood donors, mean age 49 years (rangerothrombosis.2,3 C. pneumoniae is an obligate 27e58), have been selected as a control group.intracellular parasite that commonly infects mono-nuclear phagocytes. Macrophages derived from Serological detection of C. pneumoniaemonocytes are localized in human atheroscleroticplaques and provide a mechanism for entry of ELISA was performed on frozen (ÿ80 C) serumthe organism into the vessel wall. C. pneumoniae samples using the Sero C. pneumoniae Quant.8has been identified in atherosclerotic plaques of This test, based on specific C. pneumoniae pepti-patients with cerebrovascular and cardiovascular des, is a semi-quantitative determination of specificdiseases.4,5 The biology of C. pneumoniae is IgG and IgA antibodies to C. pneumoniae. A resultcharacterized by alternate phases of activity and higher than 10 IU/mL was considered positive [9].latency in inflammatory lesions, followed by fibro-sis and scarring, and ultimate degradation, the Statistical methodsantigens being detectable for a considerable lon-ger time than intact DNA.5 For comparisons of categorical variables, Chi- Based on seroepidemiological studies, C. pneu- square and Fisher’s exact tests (2-sided p value)moniae has been suspected to play a role in ath- were used. Continuous variables were comparederosclerosis.6,7 Association of high level of IgA using either t test or Wilcoxon test. The occur-anti-C. pneumoniae with symptomatic disease rence of any new arterial ischemic event was ana-suggests that chronic C. pneumoniae infection lyzed using a logistic regression model. Factorsanywhere in the body could play a role in athero- related to both IgA antibodies and occurrence ofsclerotic plaque activation and be used as a marker a new arterial ischemic event in univariate analysisto target populations in future prevention trials.5 at a significance level of 0.20 were included in theGiven the potential for enhancing pro-inflammatory logistic regression model. The statistical analysesmediators that could lead to plaque rupture or were performed using the SASâ software.luminal thrombosis, we hypothesized that C. pneu-moniae would be present in a significantly largerpercentage of symptomatic vs. asymptomatic Resultspatients with atherothrombosis. The aim of thepresent study was to search for an association The baseline characteristics of the cohort accord-between chronic C. pneumoniae infection, indi- ing to C. pneumoniae serology are presented incated by elevated antibody titers against the path- Table 1. The prevalence of IgG and IgA anti-C.ogen, atherothrombosis and the occurrence of pneumoniae antibodies at baseline was 90% (95%arterial ischemic events. CI: 79e97) and 81% (67e90), respectively. Patients with either IgA or IgG antibodies were significantly older than those without antibodies. Males wereMethods more likely to have either IgA or IgG antibodies than women. All other baseline characteristics,Patients including ischemic area, were not significantly related to anti-C. pneumoniae antibodies.We studied 52 patients presenting at baseline with Forty-two of the 52 patients (81%) experiencedat least one symptomatic episode of atherothrom- a new arterial ischemic event after a mean follow-bosis (i.e. stroke, angina, myocardial infarction, up of 9 years [heart: 19 (37%); brain: 12 (23%); lowerperipheral arterial disease, and others). Patients limbs: 8 (15%); and other: 13 (25%)]. Patients whowere followed-up during a mean period of 9 years, experienced a new arterial ischemic event duringand occurrence of new arterial ischemic events follow-up were as much as likely to have either IgAwas collected for each patient. Risk factors for or IgG antibodies at baseline than those withoutatherothrombosis were recorded in all patients any event (91% vs. 90% for IgG, and 83% vs. 70%,
  3. 3. ARTICLE IN PRESSChlamydia pneumoniae infection 3 Table 1 Baseline characteristics of patients Table 2 Factors related to new arterial ischemic according to Chlamydia pneumoniae serology event (logistic regression model, n ¼ 52) IgG and IgA IgG or IgA p Odds 95% Confidence p negative positive ratio interval of (n ¼ 5) (n ¼ 47) odds ratio Mean age, 47.2 (15.2) 61.0 (12.6) 0.03 Age 1.10 1.02e1.19 0.02 years (std) Sex (female as 13.8 1.4e131.1 0.02 Male sex [n (%)] 1 (20) 34 (72) 0.03 reference) Body mass index 25 2 (40) 17 (36) 1.00 Smoking 5.84 0.83e40.7 0.07 [n (%)] (non-smoking Mean follow-up 7 (3.3) 9.4 (7.2) 0.46 as reference) duration, years (std) Family history of 3.57 0.35e35.9 0.28 Tobacco smoking 4 (80) 31 (66) 1.00 atherothrombosis [n (%)] (no history Hormone 3 (75) 4 (31) 0.25 as reference) replacement IgA anti-C 0.68 0.08e5.82 0.72 therapy, in Pneumoniae women [n (%)] 10 IU/mL Diabetes [n (%)] 0 6 (13) 0.31 (IgA 10 IU/mL Hypertension [n (%)] 3 (60) 21 (45) 0.65 as reference) Hypercholesterolemia 2 (40) 28 (60) 0.64 [n (%)] Familial history of 3 (60) 13 (28) 0.16 atherothrombosis found an absence of association between infec- [n (%)] tious agents, included C. pneumoniae and endo- Arterial ischemic territory thelial function in healthy young men.14 Few Heart 0 14 (30) 0.31 data on the epidemiology of C. pneumoniae in Brain 2 (40) 10 (21) 0.33 blood donors and general population are avail- Legs 4 (80) 21 (45) 0.18 able.15 Our results of 41% seropositivity for IgG Other 0 4 (9) 1.00 contrast with the Irish study that reported a 70% seropositivity in a randomly selected adult popula- tion.16 O’Neill et al. did not find significant relationp ¼ NS). Occurrence of a new arterial ischemic between C. pneumoniae antibodies and age, gen-event was related to age (p ¼ 0.003), sex der or smoking.16 They found, however, that C.(p ¼ 0.009), and tobacco smoking (p ¼ 0.06). The pneumoniae seroprevalence was higher in patientslogistic regression model showed that, after adjust- with low socio-economic status. Further studiesing for sex, age, family history of atherosclerosis are needed for a better knowledge of the epidemi-disease, and tobacco smoking at baseline, IgA ology of C. pneumoniae in general population andanti-C. pneumoniae was not significantly related patients with the occurrence of a new arterial ischemic event The obligate intracellular bacterium C. pneumo-(Table 2). Prevalences of IgA and IgG anti-C. pneu- niae has recently been implicated in the pathogen-moniae were significantly higher in patients with esis of atherosclerosis.[17] In the present study,atherothrombosis at baseline than that in controls using a highly specific test, serological response(Table 3). to C. pneumoniae indicates an increased pre- valence in patients suffering from symptomaticDiscussion atherothrombosis disease. Two recent studies have demonstrated that the detection of a link be-In the present cohort study, the very high preva- tween C. pneumoniae and coronary artery diseaselence of anti-C. pneumoniae antibodies in patients depends on the choice of serologic methods.18,19with atherothrombosis brings further evidence for However, Hermann and colleagues reported thata relationship between such infection and athero- ELISAs that are fast and objective deliver seropre-thrombosis, as reported by others.10e13 However, valence results, sensitivities, and specificitiesneither IgA nor IgG antibodies for C. pneumoniae that are very similar to those of the MIF test.8was a significant predictive factor for new ischemic Our results corroborate other investigations thatarterial events in patients with atherothrombosis. reported the presence of chlamydial structures C. pneumoniae antibodies are more likely to be and even viable C. pneumoniae in atheroscleroticfound among male and older patients. Khairy et al. plaques. Experimental proof, however, of an
  4. 4. ARTICLE IN PRESS4 P. Halfon et al. Table 3 IgG and IgA for Chlamydia Pneumoniae infection in controls and patients with atherothrombosis Controls (n ¼ 56) Patients with p atherothrombosis (n ¼ 52) IgG titers [mean (95% CI)] 40.8 [31.1e51.1] 69.2 [54.2e80.9] 0.001 IgG 10 IU/mL [n (%)] 41 (73%) 47 (90%) 0.02 IgA titers [mean (95% CI)] 18.5 [12.5e24.9] 52.4 [38.1e64.3] 0.0001 IgA 10 IU/mL [n (%)] 18 (32%) 42 (81%) 0.0001etiological role of C. pneumoniae in atherothrom- ischemic heart disease, macrolide antibiotics forbosis has not yet been accomplished since a well- C. pneumoniae did not result in a statistically sig-established animal model and a system of genetic nificant reduction in recurrent cardiac events orrecombination are not yet available. mortality over 3 months to 3 years.24 However, Elevated anti-chlamydial IgA levels are believed other studies using doxycycline in doses prescribedto occur with reinfection of C. pneumoniae.20e21 in routine clinical practice for brucellosis de-IgA titers begin to decline within weeks to several creases the risk of coronary artery disease.25 Thesemonths after reinfection. Persistently elevated conflicting results may be due to the obligate in-IgA levels are believed to be associated with a chron- tracellular infectious life cycle of C. pneumoniae.ic infection state and have been noted in both Only the intracellular forms, i.e. the reticulatechronic and acute coronary diseases. However, no bodies, are metabolically active and can be trea-association was seen between the presence of C. ted with membrane-permeative antibiotics suchpneumoniae in atherosclerotic plaques and immu- as macrolides. The persistent state is character-noglobulin titers. More than 70% of patients with ized by a metabolically active period without rep-plaque positive for C. pneumoniae by PCR did not lication. Until now, no antibiotics have provenshow elevated IgA anti-chlamydial titers. This lack capable of eradicating persistent chlamydialof association makes anti-chlamydial IgA titer levels infections.26,27a poor indicator for intraplaque presence of C. In conclusion, our study suggests the links be-pneumoniae although elevated anti-chlamydial tween C. pneumoniae and atherothrombosis. TheseIgA levels seem associated with symptomatic dis- results must be confirmed on larger cohort. Clinicalease, as previously reported.22,23 Elevated serum evaluation of patients is complicated by the lack ofanti-chlamydial IgA may represent a more chronic a useful parameter to indicate the risk of endovas-infection state, inducing activation of atheroscle- cular infection. At the current state of scientificrotic plaque by circulating activated leukocytes. knowledge, an experimental anti-Chlamydia treat- Another possible explanation for association of ment in patients with atherothrombosis to preventIgA levels with Chlamydia and symptomatic dis- new ischemic events may only be justified in ran-ease is a non-specific increase in immunoglobulin domized controlled clinical trials.response to antigens. Persons who have been pre-viously infected with C. pneumoniae could display Acknowledgementsan elevated anti-chlamydial IgA after exposure toa variety of antigens. This supports the hypothesis We kindly thank Eliane Corre from BMD (Paris,that generalized inflammatory response can acti- France) for providing the anti-chlamydial IgG andvate atherosclerotic plaque, with anti-chlamydial IgA assays (Savyon).IgA acting only as a marker and not as an indicatorof the specific antigen exposure. Further studiesthat focus on intraplaque differences between Referencessymptomatic and asymptomatic patients in pres-ence of C. pneumoniae need to be performed to 1. Wood D. Established and emerging cardiovascular risk factors. Am Heart J 2001;141(2 Suppl.):S49e57.identify causative effect of infectious agents in 2. Siscovick DS, Schwartz SM, Caps M, Wang SP, Grayston JT.atherosclerotic disease. Chlamydia pneumoniae and atherosclerotic risk in popula- Numerous clinical trials that have studied the tions: the role of seroepidemiology. J Infect Dis 2000;use of antibiotics in the secondary prevention of 181(Suppl. 3):S417e20.ischemic heart diseases have had conflicting 3. Saikku P, Leinonen M, Mattila K, Ekman MR, Nieminen MS, Makela PH, et al. Serological evidence of an association ofresults. A recent meta-analysis based on nine a novel Chlamydia, TWAR, with chronic coronary heart dis-published studies, with a total of 11,015 partic- ease and acute myocardial infarction. Lancet 1988;2(8618):ipants, showed that in patients with known 983e6.
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