BRONCHIAL ASTHMA AND CHLAMYDIA PNEUMONIAE ANTIBODIES IN CHILDREN AGED 4 – 8 YEARS IN OLOMOUC DISTRICT

BACKGROUND. Although several studies have demonstrated an association between infection with Chlamydia pneumoniae and asthma, these were mainly limited to exacerbation of symptoms in adults with known asthma OBJECTIVE. We investigated the role of C. pneumoniae infection in l49 atopic children with chronic cough and asthma, comparing them with 241 control non-atopic subjects presenting at Olomouc hospital between 1999 and 2003 with non-specific symptoms (temperature above normal (subfebrile), abdominal pain, arthralgia, and other symptoms. METHODS. The levels of C. pneumoniae-specific antibodies were measured using Chlamydien-rELISA kits (Medac, Hamburg, Germany). RESULTS. In a group of 83 atopic children with chronic cough, IgM and IgG antibodies to C. pneumoniae were demonstrated in 20 children (24 %). Among children with bronchial asthma, positive antibody was present in 29 children (44 %; /p = 0,052/); of this number, 24 (36 %; /p = 0,06/) had IgM and IgG antibodies while 5 children (8 %) had IgA and IgG antibodies against C. pneumoniae. A group of non-atopic children with non-specific symptoms included 38 children (16 %) with antibody positivity; 27 children (11 %) with IgM and IgG antibodies and 11 children (5 %) with IgA and IgG antibodies against C. pneumoniae. CONCLUSIONS. Asthma in children was associated with elevated levels of IgM and IgG antibodies to C. pneumoniae.


INTRODUCTION
Chlamydia pneumoniae is common intracellular respiratory pathogen, and although many infections are believed to be asymptomatic, a growing body of evidence suggests an association between C. pneumoniae infection and asthma in some individuals 1 .For the clinician, the diagnosis of C. pneumoniae infection may be difficult because of the lack of widespread availability of diagnostic facilities for either organism identification or serologic testing, and because of controversies surrounding serodiagnostic criteria.The association was first described by Hahn et al., who reported wheezing in 9 out of 19 adult patients with serologic evidence of current or recent C. pneumoniae infection 2 .In another study 11 % asthmatic and 5 % control children found to have positive cultures for C. pneumoniae 3 .Although some results were controversial, several studies confirmed these findings 4,5,6 .Our study aimed to investigate the current situation in the seroprevalence of C. pneumoniae infection in Olomouc district in a group of atopic children with chronic cough and asthma compared with a control group of non-atopic children with non-specific symptoms, i.e., temperature above normal, abdominal pain, arthralgia, fatigue.1).Each child had a detailed history taken and total serum immunoglobulin E (S-IgE) levels determined.Atopic children had a positive skin test (wheal ≥ 3 mm) to at least one of the most common aeroallergens from our area (house-dust-mites, grass pollen, birch pollen, cat and dog danger, and mold mixture).Ineligible for the study were children with congenital respiratory tract anomalies and those with a serious respiratory disease, e.g., cystic fibrosis.
S-IgE levels were determined by nephelometry.S-IgE values of 150 IU/ml, determined in our laboratory, are considered a significant marker of allergy.All atopic children had total S-IgE levels higher than 150 IU/ml.The same investigations were undertaken in a control group of non-atopic 241 (170 boys and 71 girls) children with subfebrile, abdominal pain, arthralgia, fatigue.None of these control children showed S-IgE levels over 150 IU/ml.
Our data were analyzed statistically using contingence table and χ square test.
In the group of 241 non-atopic children with nonspecific symptoms, positive antibodies were found in 38 children (16 %), i.e. 27 children (11 %) with IgM and IgG antibodies and 11 children (5 %) with IgA and IgG antibodies against C. pneumoniae.

DISCUSSION
Chlamydia pneumoniae is a ubiquitous Gram-negative bacterium, an obligate intracellular parasite with a unique developmental cycle, and a common respiratory pathogen in children as well as adults 8 .Many infections are believed to be asymptomatic.Wheezing and cough are common features of chlamydial lung infections.The mechanism of this apparent association between C. pneumoniae infection and asthma is not clear, but presumably relates to chronic bronchial inflammation.Increased production of IL-1, IL-6, TNF-α and granulocyte macrophage-colony stimulating factor(GM-CSF) has been demonstrated in bronchial epithelial cells infected with C. pneumoniae.Inflammation in the airways in asthmatics is associated with healing processes resulting in scar formation and tissue remodeling, which seems to be present in almost all asthmatics whatever the severity, duration, or etiology of the asthma.C. pneumoniae may be one contributory factor in the development of irreversible changes in the airways.It has been suggested that bronchial hyper-reactivity may be caused by anti-C.pneumoniae IgE antibodies (implying allergic sensitization) 9 .
Our study supports the association between C. pneumoniae infection and asthma in children.One possible explanation is the finding of an association between variants of the alleles for mannose-binding lectin responsible for the increased incidence of C. pneumoniae infection in asthmatic children 10 .Cook et al. found that elevated levels of IgG antibody to C. pneumoniae were significantly associated with severe chronic asthma and this association was not modified by potential confounding factors 11 .The presence of short-lived IgA antibodies has been proposed to indicate chronic infection or reinfection, whereas stable elevated levels of more long-lived IgG antibodies may reflect suffer infection in the past or chronic infection.The study by Black et al. showed an association of the severity of asthma and the mean IgG and IgA titers with C. pneumoniae infection 12 .Results of our study indirectly confirm the conclusions drawn in the above papers.A new diagnostic option is polymerase chain reaction (PCR).
If these associations are important, can we identify individuals at risk for asthma?The answer is: possibly, in the future.To survive within a macrophage, chlamydiae must not elicit a TH1-type CD4 lymphocyte response, such as would be promoted by interferon-γ. 13Individuals with particular HLA class II genotypes might therefore be at a higher risk of chronic C. pneumoniae-associated disease 14 .
Persistent or recurrent C. pneumoniae may both initiate the inflammatory process in some individuals, and amplify the inflammation in patients with early mild asthma leading to permanent changes in the airways and chronic disease.Macrolides are antibiotics with both antimicrobic and antiinflammatory activities and thus their use in asthmatic patients could lead to reduction of the airways inflammation and therefore improvement of symptoms and pulmonary function.Further studies are needed to examine the role of macrolides in asthma therapy.C. pneumoniae may persist in the lung after treatment 15 .
An association does not mean causality and it is possible that C. pneumoniae is coincidental in the bronchi of asthmatic children without playing a contributory role in the amplification of inflammation and progression of asthma.
We conclude that asthma in children was associated with elevated levels of IgM and IgG antibodies to C. pneumoniae.Our results are consistent with the hypothesis that C. pneumoniae infection may be involved in the development of asthma.

Table 2 .
Number of examined children with chronic cough, bronchial asthma, non-specific symptoms and proportion of positive anti-Chlamydia Ab

Table 3 .
Number of children with positive anti-Chlamydia Ab in individual groups Non -atopic patients with subfebrile, abdominal pain, arthralgia, fatigue F. Kopřiva, J. Szotkowská, M. Zápalka