Serologic markers for Chlamydia pneumoniae in asthma

Outcomes of Antibiotics in Adults with "Difficult to Treat" Asthma or the Overlap Syndrome

Purpose

Macrolides are a recommended treatment option for severe asthma, but data for “difficult-to-treat” asthma, the asthma-COPD “overlap” syndrome, and treatment duration beyond one year are lacking. We present long-term data from community practice experience providing insights for practice and research.

Methods

We report data from (1) baseline (pre-treatment) chart review of antibiotic-treated asthma patients and (2) follow-up telephone interviews documenting severe exacerbations (NIH criteria), Asthma Control Test (ACT) scores, and asthma controller use at baseline and follow-up, analyzed using a “before-after” model.

Results

A total of 101 patients (mean age 55.6 years (Sd 16.8), 66 females) were included. None had ever taken high dose inhaled corticosteroids and 79 (78.2%) were severely uncontrolled (ACT score ≤15) before treatment. Coexisting COPD was present in 62 (61.4%) patients. Azithromycin or azithromycin plus doxycycline was primarily prescribed with a median treatment duration of 12 months and median follow-up duration of 22 months. Severe exacerbations in the month before treatment occurred in 50.5% vs 17.8% at follow-up (P<0.0001). Mean ACT score increased from 12.2 to 20.6 (P<0.0001). The number of patients taking controller medications decreased (P<0.0001 for inhaled corticosteroids; P<0.001 for long-acting beta agonist/long-acting muscarinic antagonist; P<0.05 for leukotriene receptor antagonists). Of the 79 severely uncontrolled patients, 51 (64.6%) became controlled at follow-up, and of these 51, 27 (52.9%) continued to take antibiotics while 24 (47.1%) had discontinued antibiotics earlier yet remained controlled.

Conclusion

Antibiotic treatment may be beneficial in a significant proportion of “difficult to treat” asthma patients beyond one year, including some patients with the overlap syndrome and/or who fail to meet criteria for refractoriness.

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Chlamydia pneumoniae and chronic asthma: Updated systematic review and meta-analysis of population attributable risk

Background

Chlamydia pneumoniae (Cp) is an obligate intracellular human respiratory pathogen producing persisting lung infection with a plausible link to asthma pathogenesis. The population attributable risk of potentially treatable Cp infection in asthma has not been reported.

Methods

The author searched from 2000 to 2020 inclusive for previously un-reviewed and new cross sectional and prospective controlled studies of Cp biomarkers and chronic asthma in both children and adults. Qualitative descriptive results and quantitative estimates of population attributable risk for selected biomarkers (specific IgG, IgA and IgE) are presented.

Findings

No large, long-term prospective population-based studies of Cp infection and asthma were identified. About half of case-control studies reported one or more significant associations of Cp biomarkers and chronic asthma. Heterogeneity of results by age group (pediatric v adult asthma), severity category (severe/uncontrolled, moderate/partly controlled, mild/controlled) and antibody isotype (specific IgG, IgA, IgE) were suggested by the qualitative results and confirmed by meta-analyses. The population attributable risks for Cp-specific IgG and IgA were nul in children and were 6% (95% confidence interval 2%-10%, p = 0.002) and 13% (9%-18%, p<0.00001) respectively in adults. In contrast to the nul or small population attributable risks for Cp-specific IgG and IgA, the population attributable risk for C. pneumoniae-specific IgE (children and adults combined) was 47% (39%-55%, p<0.00001). In the subset of studies that reported on asthma severity categories, Cp biomarkers were positively and significantly (P<0.00001) associated with asthma severity.

Interpretation

C. pneumoniae-specific IgE is strongly associated with asthma and asthma severity, suggesting a possible mechanism linking chronic Cp infection with asthma in a subset of individuals with asthma. Infection biomarkers should be included in future macrolide treatment trials for severe and uncontrolled asthma.

Infection-mediated asthma: etiology, mechanisms and treatment options, with focus on Chlamydia pneumoniae and macrolides

Asthma is a chronic respiratory disease characterized by reversible airway obstruction and airway hyperresponsiveness to non-specific bronchoconstriction agonists as the primary underlying pathophysiology. The worldwide incidence of asthma has increased dramatically in the last 40 years. According to World Health Organization (WHO) estimates, over 300 million children and adults worldwide currently suffer from this incurable disease and 255,000 die from the disease each year. It is now well accepted that asthma is a heterogeneous syndrome and many clinical subtypes have been described. Viral infections such as respiratory syncytial virus (RSV) and human rhinovirus (hRV) have been implicated in asthma exacerbation in children because of their ability to cause severe airway inflammation and wheezing. Infections with atypical bacteria also appear to play a role in the induction and exacerbation of asthma in both children and adults. Recent studies confirm the existence of an infectious asthma etiology mediated by Chlamydia pneumoniae (CP) and possibly by other viral, bacterial and fungal microbes. It is also likely that early-life infections with microbes such as CP could lead to alterations in the lung microbiome that significantly affect asthma risk and treatment outcomes. These infectious microbes may exacerbate the symptoms of established chronic asthma and may even contribute to the initial development of the clinical onset of the disease. It is now becoming more widely accepted that patterns of airway inflammation differ based on the trigger responsible for asthma initiation and exacerbation. Therefore, a better understanding of asthma subtypes is now being explored more aggressively, not only to decipher pathophysiologic mechanisms but also to select treatment and guide prognoses. This review will explore infection-mediated asthma with special emphasis on the protean manifestations of CP lung infection, clinical characteristics of infection-mediated asthma, mechanisms involved and antibiotic treatment outcomes.

Laboratory diagnosis of persistent human chlamydial infection

Diagnostic assays for persistent chlamydial infection are much needed to conduct high-quality, large-scale studies investigating the persistent state in vivo, its disease associations and the response to therapy. Yet in most studies the distinction between acute and persistent infection is based on the interpretation of the data obtained by the assays developed to diagnose acute infections or on complex assays available for research only and/or difficult to establish for clinical use. Novel biomarkers for detection of persistent chlamydial infection are urgently needed. Chlamydial whole genome proteome arrays are now available and they can identify chlamydial antigens that are differentially expressed between acute infection and persistent infection. Utilizing these data will lead to the development of novel diagnostic assays. Carefully selected specimens from well-studied patient populations are clearly needed in the process of translating the proteomic data into assays useful for clinical practice. Before such antigens are identified and validated assays become available, we face a challenge of deciding whether the persistent infection truly induced appearance of the proposed marker or do we just base our diagnosis of persistent infection on the presence of the suggested markers. Consequently, we must bear this in mind when interpreting the available data.

Chlamydia pneumoniae-specific IgE is prevalent in asthma and is associated with disease severity

Background

Several Chlamydia pneumoniae (Cp) biomarkers have been associated with asthma but Cp-specific IgE (Cp IgE) has not been investigated extensively. Our objective was to investigate Cp IgE in community adult asthma patients.

Methods

(1) Prevalence of Cp IgE (measured by immunoblotting) and Cp DNA (by polymerase chain reaction) in peripheral blood, and biomarker associations with asthma severity. (2) Case-control studies of Cp IgE association with asthma using healthy blood donor (study 1) and non-asthmatic clinic patient (study 2) controls.

Results

Of 66 asthma subjects (mean age 40.9 years, range 5–75, 59% male, 45% ever-smokers) 33 (50%) were Cp IgE positive and 16 (24%) were Cp DNA positive (P = 0.001 for association of Cp IgE and DNA). Cp IgE was detected in 21% of mild intermittent asthma v 79% of severe persistent asthma (test for trend over severity categories, P = 0.002). Cp IgE detection was significantly (P = 0.001) associated with asthma when compared to healthy blood donor controls but not when compared to clinic controls.

Conclusions

Half of this sample of community asthma patients had detectable IgE against C. pneumoniae. Cp IgE was strongly and positively associated with asthma severity and with asthma when healthy blood donor controls were used. These results support the inclusion of Cp IgE as a biomarker in future studies of infectious contributions to asthma pathogenesis.

Refractory asthma: importance of bronchoscopy to identify phenotypes and direct therapy

BACKGROUND

The pathophysiology of refractory asthma is not well understood; thus, treatment modalities are not targeted to specific phenotypes but rather to a broad-based treatment approach. The objective of this study was to develop refractory asthma phenotypes based on bronchoscopic evaluation and to develop from this information specific, directed, personalized therapy.

METHODS

Fifty-eight patients with difficult-to-treat (refractory) asthma were characterized by the use of fiber-optic bronchoscopy with visual scoring systems of the upper and lower airways as well as with BAL, endobronchial biopsy, and brush. Response to changes in therapy was evaluated by changes in the Asthma Control Test and pulmonary function.

RESULTS

Five mutually exclusive phenotypes were formulated based on bronchoscopic evaluation: gastroesophageal reflux, subacute bacterial infection, tissue eosinophilia, combination, and nonspecific. Specific directed therapy yielded a significant improvement in the Asthma Control Test and pulmonary function for the entire group as well as for each defined subgroup except for the nonspecific group. Of interest, visual scoring of the supraglottic abnormalities identified 34 of 35 patients with gastroesophageal reflux and may give a better insight into asthmatic problems associated with chronic proximal reflux than standard testing.

CONCLUSIONS

Bronchoscopic evaluation of the upper and lower airways can provide important information toward characterizing refractory asthma so as to better individualize therapeutic options and improve asthma control and lung function in patients with difficult-to-treat asthma.

Design and synthesis of 2-arylbenzimidazoles and evaluation of their inhibitory effect against Chlamydia pneumoniae

Chlamydia pneumoniae is an intracellular bacterium that responds poorly to antibiotic treatment. Insufficient antibiotic usage leads to chronic infection, which is linked to disease processes of asthma, atherosclerosis, and Alzheimer's disease. The Chlamydia research lacks genetic tools exploited by other antimicrobial research, and thus other approaches to drug discovery must be applied. A set of 2-arylbenzimidazoles was designed based on our earlier findings, and 33 derivatives were synthesized. Derivatives were assayed against C. pneumoniae strain CWL-029 in an acute infection model using TR-FIA method at a concentration of 10 μM, and the effects of the derivatives on the host cell viability were evaluated at the same concentration. Fourteen compounds showed at least 80% inhibition, with only minor changes in host cell viability. Nine most potential compounds were evaluated using immunofluorescence microscopy on two different strains of C. pneumoniae CWL-029 and CV-6. The N-[3-(1H-benzimidazol-2-yl)phenyl]-3-methylbenzamide (42) had minimal inhibitory concentration (MIC) of 10 μM against CWL-029 and 6.3 μM against the clinical strain CV-6. This study shows the high antichlamydial potential of 2-arylbenzimidazoles, which also seem to have good characteristics for lead compounds.

Chlamydial heat shock protein 60 induces acute pulmonary inflammation in mice via the Toll-like receptor 4- and MyD88-dependent pathway

Heat shock protein 60 derived from Chlamydia pneumoniae (cHSP60) activates Toll-like receptor 4 (TLR4) signaling through the MyD88 pathway in vitro, but it is not known how cHSP60 contributes to C. pneumoniae-induced lung inflammation. We treated wild-type (WT), TLR2(-/-), TLR4(-/-), or MyD88(-/-) mice intratracheally (i.t.) with recombinant cHSP60 (50 microg), UV-killed C. pneumoniae (UVCP; 5 x 10(6) inclusion-forming units/mouse), lipopolysaccharide (2 microg), or phosphate-buffered saline (PBS) and sacrificed mice 24 h later. Bronchoalveolar lavage (BAL) was obtained to measure cell counts and cytokine levels, lungs were analyzed for histopathology, and lung homogenate chemokine concentrations were determined. Bone marrow-derived dendritic cells (BMDDCs) were generated and stimulated with live C. pneumoniae (multiplicity of infection [MOI], 5), UVCP (MOI, 5), or cHSP60 for 24 h, and the expression of costimulatory molecules (CD80 and CD86) was measured by fluorescence-activated cell sorting. cHSP60 induced acute lung inflammation with the same intensity as that of UVCP-induced inflammation in WT mice but not in TLR4(-/-) or MyD88(-/-) mice. cHSP60- and UVCP-induced lung inflammation was associated with increased numbers of cells in BAL, increased neutrophil recruitment, and elevated BAL interleukin-6 (IL-6) levels. Both cHSP60 and UVCP induced IL-6 release and CD80 and CD86 expression in WT cells but not in MyD88(-/-) BMDDCs. cHSP60 stimulated DC activation in a TLR4- and MyD88-dependent manner with an intensity similar to that induced by UVCP. These data suggest that cHSP60 promotes lung inflammation and DC activation via TLR4 and MyD88 and therefore may play a significant role in the pathogenesis of C. pneumoniae-induced chronic inflammatory lung diseases.

Airflow limitation, asthma, and Chlamydia pneumoniae-specific heat shock protein 60

BACKGROUND

Chlamydia pneumoniae has been associated with asthma. It has also been suggested that C pneumoniae infection may lead to lung remodeling in a subset of asthmatic patients. Seroreactivity against Chlamydia trachomatis heat shock protein 60 (hsp60), a highly conserved, immunoreactive chaperone protein, is associated with immunopathologic abnormalities, leading to blinding trachoma and tubal infertility. This suggests that the host response to infection may affect chronic inflammatory damage to the eye and the fallopian tubes. The pathogenesis of C trachomatis disease associations is thought to include molecular mimicry (autoimmunity), direct activation of the innate immune response via the CD14/toll-like receptor 4 complex, or both.

OBJECTIVE

To study whether airflow limitation in asthma in C pneumoniae-exposed individuals is associated with a specific antibody response to the C pneumoniae hsp60 molecule and not with a genus-specific response to the hsp60 molecule.

METHODS

In a case-control study, we evaluated 138 C pneumoniae-exposed primary care patients (86 adult asthmatic cases and 52 nonasthmatic controls) for seroreactivity against a C pneumoniae-specific hsp60 fragment and against the C trachomatis hsp60 molecule. We analyzed associations with asthma and irreversible lung remodeling as measured by means of postbronchodilator forced expiratory volume in 1 second.

RESULTS

Twenty-seven percent of asthmatic patients were C pneumoniae hsp60 seropositive vs 8% of controls (P < .01). Controlling for age, sex, and smoking, C pneumoniae hsp60 seropositivity was associated with lower postbronchodilator forced expiratory volume in 1 second in asthmatic patients (P < .05). No comparable associations were present for C trachomatis hsp60.

CONCLUSIONS

In individuals with evidence of previous exposure to C pneumoniae infection, a host antibody response against a C pneumoniae hsp60 fragment but not against C trachomatis hsp60 was associated with airflow limitation in adults with asthma.

Chlamydophila pneumoniae infection in adult asthmatics patients

OBJECTIVES

This study has attempted to investigate the prevalence of Chlamydophila pneumoniae (CP) infection in patients with asthma.

METHODS

A total of 84 patients with stable asthma (58 males + 26 females; mean age +/- SD; 37.3 +/- 11.0 years), 22 patients with asthma exacerbation (17 males + 5 females; mean age +/- SD; 33.2 +/- 9.1 years), and 34 healthy adults (18 males + 16 females; mean age +/- SD; 30.4 +/- 11.5 years) were included in the study. Serum and throat wash samples were obtained from all patients and healthy controls 2 times, 1 month apart. Micro Immuno Fluorescence method for detecting CP antibodies in serum, and polymerase chain reaction (PCR) method for detecting presence of CP infection in the throat wash samples were used.

RESULTS

The frequency of PCR positivity for CP in throat wash samples was higher in the patients with stable asthma (28.6%) than in healthy control group (11.8%) (p < 0.01). However no significant difference was found between healthy control group and asthma exacerbated group (22.7%) (p > 0.05). In addition, seroprevalences of acute and chronic CP infections were not different between patient and control groups (p > 0.05). Serological acute infection for CP was not detected among patients with positive PCR results. In contrast, although not statistically significant, serologically chronic infection for CP was detected in 3 (60%) of 5 patients with asthma exacerbation, in 18 (75%) of 24 patients with stable asthma, and 2 (50%) of 4 with healthy controls (p > 0.05).

CONCLUSION

CP infection detected by the PCR method was more prevalent among patients with stable asthma and chronic/persistent CP infection might have an important role in asthma pathogenesis.

The development of asthma in wheezing infants with Chlamydia pneumoniae infection

Chlamydia pneumoniae infection might play a role in the pathology of asthma, but its role in infantile asthma remains obscure. The presence of Chlamydia pneumoniae was serologically determined in wheezing infants who were then re-examined 1-year later to determine whether or not asthma is associated with this type of infection. Wheezing infants progressed to asthma more frequently after infection with Chlamydia pneumoniae than those who were not infected. These findings suggested that Chlamydia pneumoniae infection triggers asthma in wheezy infants.

Asthmatic persons are prone to the persistence of Chlamydia pneumoniae antibodies

Acute Chlamydia pneumoniae infection may initiate asthma or worsen asthmatic symptoms. In crowded conditions, such as military service, young men are susceptible to respiratory infections, including C. pneumoniae. We recruited 127 asthmatic and 391 nonasthmatic military conscripts, followed up their respiratory tract infections and the kinetics of serum C. pneumoniae antibodies, and assessed the association between C. pneumoniae and asthma during 6 months of military service in 2 intake groups. During the 6-month period, in the July intake group, IgG antibody prevalence decreased from 60.3% to 43.8% in asthmatic and from 55.6% to 22.6% in nonasthmatic conscripts. In the January intake group, IgG antibody prevalence increased from 38.3% to 48.4% in asthmatic and from 37.2% to 43% in nonasthmatic recruits. IgG and IgA antibodies persisted more often in the asthmatic groups. In conclusion, the prevalence of IgG antibodies showed seasonal variation. Military recruits seem to be most vulnerable to C. pneumoniae infections during the period from January to June. The antibody titer changes were more rapid than previously thought.

The role of antibiotics in asthma

There is increasing evidence that atypical respiratory pathogens such as Chlamydophila pneumoniae and Mycoplasma pneumoniae may contribute to the pathogenesis of both stable asthma and asthma exacerbations. It is postulated that these organisms may contribute to inflammation in the airways possibly by activating inflammatory mechanisms in the respiratory tract.

The macrolide class of antibiotics may have a part to play in the management of asthma by exerting anti-inflammatory effects on the chronically inflamed airways in addition to their anti-infective action. The ketolide antibiotics may also have similar properties.

This paper discusses the role of these antibiotics in the management of asthma.

Secondary outcomes of a pilot randomized trial of azithromycin treatment for asthma

OBJECTIVES

The respiratory pathogen Chlamydia pneumoniae (C. pneumoniae) produces acute and chronic lung infections and is associated with asthma. Evidence for effectiveness of antichlamydial antibiotics in asthma is limited. The primary objective of this pilot study was to investigate the feasibility of performing an asthma clinical trial in practice settings where most asthma is encountered and managed. The secondary objectives were to investigate (1) whether azithromycin treatment would affect any asthma outcomes and (2) whether C. pneumoniae serology would be related to outcomes. This report presents the secondary results.

DESIGN

Randomized, placebo-controlled, blinded (participants, physicians, study personnel, data analysts), allocation-concealed parallel group clinical trial.

SETTING

Community-based health-care settings located in four states and one Canadian province.

PARTICIPANTS

Adults with stable, persistent asthma.

INTERVENTIONS

Azithromycin (six weekly doses) or identical matching placebo, plus usual community care.

OUTCOME MEASURES

Juniper Asthma Quality of Life Questionnaire (Juniper AQLQ), symptom, and medication changes from baseline (pretreatment) to 3 mo posttreatment (follow-up); C. pneumoniae IgG and IgA antibodies at baseline and follow-up.

RESULTS

Juniper AQLQ improved by 0.25 (95% confidence interval; -0.3, 0.8) units, overall asthma symptoms improved by 0.68 (0.1, 1.3) units, and rescue inhaler use decreased by 0.59 (-0.5, 1.6) daily administrations in azithromycin-treated compared to placebo-treated participants. Baseline IgA antibodies were positively associated with worsening overall asthma symptoms at follow-up (p = 0.04), but IgG was not (p = 0.63). Overall asthma symptom improvement attributable to azithromycin was 28% in high IgA participants versus 12% in low IgA participants (p for interaction = 0.27).

CONCLUSIONS

Azithromycin did not improve Juniper AQLQ but appeared to improve overall asthma symptoms. Larger community-based trials of antichlamydial antibiotics for asthma are warranted.

Detection of Chlamydia in the peripheral blood cells of normal donors using in vitro culture, immunofluorescence microscopy and flow cytometry techniques

BACKGROUND

Chlamydia trachomatis (Ct) and Chlamydia pneumoniae (Cp) are medically significant infectious agents associated with various chronic human pathologies. Nevertheless, specific roles in disease progression or initiation are incompletely defined. Both pathogens infect established cell lines in vitro and polymerase chain reaction (PCR) has detected Chlamydia DNA in various clinical specimens as well as in normal donor peripheral blood monocytes (PBMC). However, Chlamydia infection of other blood cell types, quantification of Chlamydia infected cells in peripheral blood and transmission of this infection in vitro have not been examined.

METHODS

Cp specific titers were assessed for sera from 459 normal human donor blood (NBD) samples. Isolated white blood cells (WBC) were assayed by in vitro culture to evaluate infection transmission of blood cell borne chlamydiae. Smears of fresh blood samples (FB) were dual immunostained for microscopic identification of Chlamydia-infected cell types and aliquots also assessed using Flow Cytometry (FC).

RESULTS

ELISA demonstrated that 219 (47.7%) of the NBD samples exhibit elevated anti-Cp antibody titers. Imunofluorescence microscopy of smears demonstrated 113 (24.6%) of samples contained intracellular Chlamydia and monoclonals to specific CD markers showed that in vivo infection of neutrophil and eosinophil/basophil cells as well as monocytes occurs. In vitro culture established WBCs of 114 (24.8%) of the NBD samples harbored infectious chlamydiae, clinically a potentially source of transmission, FC demonstrated both Chlamydia infected and uninfected cells can be readily identified and quantified.

CONCLUSION

NBD can harbor infected neutrophils, eosinophil/basophils and monocytes. The chlamydiae are infectious in vitro, and both total, and cell type specific Chlamydia carriage is quantifiable by FC.

Chlamydophila pneumoniae and Mycoplasma pneumoniae: a role in asthma pathogenesis?

The potential role of atypical bacterial infection in the pathogenesis of asthma is a subject of continuing debate. There is an increasing body of literature concerning the association between the atypical bacteria Chlamydophila pneumoniae and Mycoplasma pneumoniae and asthma pathogenesis; however, many studies investigating such a link have been uncontrolled and have provided conflicting evidence, in part due to the difficulty in accurately diagnosing infection with these atypical pathogens. This article reviews the evidence for an association between atypical bacterial respiratory pathogens and the pathogenesis of asthma, and discusses the biological mechanisms that could account for such a link. The possible role of antibacterial therapy in the management of asthma and the need for well-designed studies to investigate this is also discussed.

Chlamydophila (Chlamydia) pneumoniae serology and asthma in adults: a longitudinal analysis

BACKGROUND

Many cross-sectional studies have found an association between Chlamydophila pneumoniae infection and asthma, and a possible causative role of C pneumoniae infection in asthma pathogenesis has been proposed. No longitudinal studies have been undertaken to estimate the effect on asthma incidence of previous or chronic infection.

OBJECTIVE

We evaluated whether serological findings suggestive for recent or chronic C pneumoniae infection affect asthma risk or lung function during follow-up.

METHODS

We followed a population-based adult cohort for 15 years and made a clinical evaluation of persons with new persistent asthma (n = 83) and matched controls (n = 162). Serological testing was performed by microimmunofluorescence and enzyme immunoassay from both baseline and follow-up samples.

RESULTS

Subjects with serologically diagnosed recent or chronic C pneumoniae infection did not run a higher risk of new asthma. An increased risk was found in subjects with allergic rhinitis, low lung function, history of smoking, and positive family background of asthma or allergy. However, chronic C pneumoniae infection was found to accelerate the loss of lung function significantly in subjects who contracted new nonatopic asthma (median change in FEV(1), 89.6 vs 55.9 mL/y; P = .032).

CONCLUSION

Chronic C pneumoniae infection promotes the development of airflow limitation in adults with nonatopic asthma. However, our results indicate that at the population level, any possible effect of C pneumoniae infection on asthma incidence is of minor significance.

A population based seroepidemiological survey of Chlamydia pneumoniae infections in schoolchildren

AIM

A serosurvey was carried out in schoolchildren from a northeastern area of Italy to define the burden of Chlamydia pneumoniae infection.

METHODS

A sample of 649 schoolchildren underwent a simplified version of the International Study of Asthma and Allergies in Childhood questionnaire and IgG and IgA antibodies were investigated using an enzyme immunoassay, followed by a microimmunofluorescence assay in reactive sera.

RESULTS

Of the children examined, 29% and 19.7% had IgG and IgA antibodies, respectively. The IgG prevalence increased with age. No other sociodemographical variable was related to C pneumoniae infection. An association was established between IgA prevalence and previous otitis media.

CONCLUSIONS

A mesoendemic (intermediate between high and low endemic level) pattern of C pneumoniae infection is present in schoolchildren from this area and the prevalence rate is related to age. Moreover, this is the first epidemiological evidence of the role of C pneumoniae in otitis.

Plasma antibodies against heat shock protein 70 correlate with the incidence and severity of asthma in a Chinese population

Background

The heat shock proteins (Hsps) are induced by stresses such as allergic factors and inflammatory responses in bronchi epithelial cells and therefore may be detectable in patients with asthma. However, the etiologic link between anti-Hsps and asthma (its severity and related inflammatory responses such as interleukin-4 and immunoglobulin E) has not been established. We determined whether antibodies against Hsp60 and Hsp70 were present in patients with asthma and evaluated their associations with risk and severity of asthma.

Methods

We determined the levels of anti-Hsp60 and anti-Hsp70 by immunoblot and their associations with risk and symptom severity of asthma in 95 patients with asthma and 99 matched non-symptomatic controls using multivariate logistic regression analysis.

Results

Compared to the controls, asthma patients were more likely to have detectable anti-Hsp60 (17.2% vs 5.1%) and anti-Hsp70 (33.7% vs 8.1%) (p ≤ 0.001). In particular, the presence of anti-Hsp70 was associated with a greater than 2 fold risk for asthma (adjusted OR = 2.21; 95% CI = 1.35~3.59). Furthermore, both anti-Hsp60 and anti-Hsp70 levels were positively correlated with symptom severity (p < 0.05) as well as interleukin-4 and immunoglobulin E (p < 0.05). Individuals with antibodies against anti-Hsp60 and anti-Hsp70 were more likely to have a family history of asthma (p < 0.001) and higher plasma concentrations of total immunoglobulin E (p = 0.001) and interleukin-4 (p < 0.05) than those without antibodies.

Conclusions

These data suggest that anti-Hsp60 and especially anti-Hsp70 correlate with the attacks and severity of asthma. The underlying molecular mechanisms linking antibodies to heat shock proteins and asthma remain to be investigated.

Chlamydia pneumoniae infections in asthma: clinical implications

Chlamydia pneumoniae is an intracellular pathogen that has been suggested to play a role in the pathology of asthma. However, so far none of the studies have provided clear evidence for a causative role of C. pneumoniae infections in asthma, although there is little doubt that chronic C. pneumoniae infection does aggravate asthma and should be treated. The diagnosis of C. pneumoniae infection is still a matter of concern for it is dependent on trained skilled personnel and can vary significantly between different diagnostic laboratories. This fact is also one of the major problems encountered when comparing epidemiological studies investigating the possible role of C. pneumoniae infections and their impact on the pathogenesis of other diseases. With regard to therapy, long-term treatment with macrolides is the best available method to eradicate C. pneumoniae. Successful therapy for C. pneumoniae, however, can also be complicated by the high possibility of de novo infection as epidemiological studies have shown that the prevalence of antibodies to C. pneumoniae increases with age in all populations studied. In the northern hemisphere the prevalence of C. pneumoniae is also affected by seasonal conditions. It is too early to draw any conclusions from the equatorial belt countries. The available data on C. pneumoniae in tropical countries indicate a much faster infection rate during early adulthood with 100% serological prevalence at an age greater than 25 years. This data, if confirmed, would argue against C. pneumoniae causing asthma since the asthma prevalence in those countries does not increase in a parallel pattern. An alternative interpretation of most studies could be that the increased rate of C. pneumoniae infections in patients with asthma results from a modified susceptibility towards the microorganism, due to yet unknown changes of the host cell's physiology. It should be kept in mind that increased prevalence of C. pneumoniae infection is not restricted to asthma. Further studies are needed to understand the role of C. pneumoniae, especially of chronic infection, in the pathogenesis of inflammatory diseases with a specific focus on the effect that the microorganism triggers in the infected host cell. Only when we understand what C. pneumoniae does to its host cell will we be able to judge its impact on the overall status of an affected patient, and this knowledge will help us to develop a successful therapy.

Role of viruses and atypical bacteria in exacerbations of asthma in hospitalized children: a prospective study in the Nord-Pas de Calais region (France)

We studied the role of viruses and atypical bacteria in children hospitalized with exacerbated asthma by a prospective study of children with acute asthma admitted to the Department of Pediatrics in Lille, and to 15 hospitals in the Nord-Pas de Calais region, from October 1, 1998-June 30, 1999. We included children aged 2-16 years with active asthma, defined as three or more recurrent episodes of reversible wheezing. The severity of asthma and of asthmatic exacerbations was recorded. Immunofluorescence assays (IFA) on nasopharyngeal secretions (NPS), serological tests, or both, were used for detection of influenza virus, respiratory syncytial virus (RSV), adenovirus, parainfluenza virus, and coronavirus. Polymerase chain reaction (PCR) assays on NPS were used for rhinovirus and enterovirus. Serological tests for Chlamydia pneumoniae and Mycoplasma pneumoniae were performed. A control group of asymptomatic asthmatic outpatients was examined for respiratory viruses (using IFA and PCR). Eighty-two symptomatic children (mean age, 7.9 years) were examined. Viruses were detected in 38% (enterovirus, 15.8%; rhinovirus, 12%; RSV, 7.3%). Serological tests for atypical bacteria were positive in 10% of patients (C. pneumoniae, 5%; M. pneumoniae, 5%). Among the 27 control subjects (mean age, 7.9 years), one PCR was positive for enterovirus. There was no correlation between severity of chronic asthma or asthmatic exacerbations and the diagnosis of infection. Atypical bacterial pathogen infections were linked with prolonged asthmatic symptoms. In conclusion, we confirmed the high incidence of viral infection in acute exacerbations of asthma, especially enteroviruses or rhinoviruses. Persistent clinical features were more frequently associated with atypical bacterial infections, suggesting that these infections should be investigated and treated in cases of persistent asthmatic symptoms.

Comparison of individuals with and without specific IgA antibodies to Chlamydia pneumoniae: respiratory morbidity and the metabolic syndrome

STUDY OBJECTIVES

To determine whether a correlation exists between markers for persistent Chlamydia pneumoniae infection, respiratory morbidity, and the metabolic syndrome.

DESIGN

Case-control study. A group of individuals with serologic markers (specific IgA > or = 1/128) suggestive of persistent C pneumoniae infection were compared with a group of control subjects without IgA antibodies (< 1/32).

SETTING

Apoteksgårdens Health Care Center, Kopparberg, Sweden.

PARTICIPANTS

One hundred case subjects (61 men and 39 women) and 100 control subjects matched for age and gender (mean age, 55 years).

MEASUREMENTS AND RESULTS

Individuals completed a questionnaire on respiratory symptoms and smoking habits. Body mass index (BMI) was calculated, BP, and peak expiratory flow (PEF) were determined. Blood specimens were drawn for determination of high-sensitivity C-reactive protein (hsCRP), blood glucose level, serum lipids, and Chlamydia antibodies. No significant difference was found between case subjects and control subjects regarding myocardial infarctions, stroke, diabetes type II, BP, BMI, hsCRP, blood glucose levels, and serum lipids. Symptoms of both asthma and chronic bronchitis were more common in case subjects, as were symptoms of chronic upper respiratory tract infections (p < 0.005). Case subjects with asthma or chronic bronchitis had more chronic upper respiratory tract disorders (p < 0.05). Symptoms of chronic respiratory tract diseases increased parallel to increasing specific C pneumoniae IgA antibody titers (p < 0.0005). PEF percentage of the predictive value was inversely correlated (p < 0.0005) to IgA antibody titers.

CONCLUSION

The data show that persistent increased levels of C pneumoniae IgA antibodies were associated with pronounced respiratory dysfunction. These data provide additional evidence suggesting that IgA antibodies may be a marker for persistent C pneumoniae infection.

Seroprevalence of chronic Chlamydia pneumoniae infection in patients affected by chronic stable asthma

OBJECTIVE

To evaluate the seroprevalence of Chlamydia pneumoniae and age, gender and smoking habits in stable asthmatic patients.

METHODS

Over a period of 3 months, 197 adult patients affected by intermittent-to-severe chronic asthma were enrolled from 16 respiratory disease units in the south of Italy. As a control group, we tested 185 healthy, non-asthmatic subjects matched for age and gender, recruited among hospital staff. All patients were submitted to clinical examination, spirometry and blood collection for C. pneumoniae serology. The presence of infection was investigated by microimmunofluorescence (Micro-IF Test) for C. pneumoniae-specific IgG, IgM and IgA antibodies.

RESULTS

C. pneumoniae IgG titers > or =1 : 64 were detected in 30.4% of asthmatics and in 30.8% of controls. Correlation of age, gender and smoking habit with C. pneumoniae seropositivity was evaluated by linear regression analysis. Age was significantly associated with C. pneumoniae IgG titer > or =1 : 64 when seropositive asthmatics were tested. Moreover, C. pneumoniae seroprevalence was higher among smokers with a diagnosis of chronic asthma.

CONCLUSIONS

The seroprevalence of C. pneumoniae in stable asthmatics was comparable with the controls; therefore, the study does not support the association between C. pneumoniae antibody titers and stable asthma. However, the analysis for likely confounders such as age, gender and smoking status suggests a possible association of enhanced susceptibility to C. pneumoniae infection with age and smoking habitus.

Prevalence of antibodies to Chlamydia pneumoniae in an Israeli population without clinical evidence of respiratory infection

AIMS

To estimate the occurrence of recent, past, and "persistent" infections with Chlamydia pneumoniae--as indicated by serology--in an Israeli population without clinical evidence of respiratory infection.

METHODS

Serum samples from 402 subjects (172 children and 230 adults), without known respiratory symptoms, were collected. Antibodies to C pneumoniae (IgG, IgA, and IgM) were evaluated using the microimmunofluorescence (MIF) assay. Antibody prevalence and indication of recent, past, and persistent infections were calculated and their distribution determined according to age, sex, and season.

RESULTS

Antibodies to C pneumoniae were detected in 53 children (31%) and 171 adults (74%). Recent infection was indicated in only one of 50 children under 5 years of age, in nine of 122 older children, and in 19 of 230 adults. IgM antibodies were detected in nine children, but only in three adults. Past infection was indicated in six of 96 young children (aged 1-10 years), in 28 of 76 teenagers, and in 128 of 230 adults. Persistent infection was indicated in three young children, in six teenagers, and in 24 adults, with a significantly higher frequency (p = 0.012) in men (18 of 117) than in women (six of 113). No seasonal differences could be detected.

CONCLUSIONS

Infection with C pneumoniae was detected serologically in children and adults without clinical signs of respiratory disease. These results should serve as a basis for studies on the role of C pneumoniae infections and their sequelae in Israel and contribute to the general understanding of asymptomatic infection with C pneumoniae.

Heat shock protein 60 specific T-cell response in chlamydial infections

Heat shock proteins (HSPs) of most pathogens, including Chlamydia, are major immune targets of both humoral- and cell-mediated immune mechanisms. During the last decade, many investigators have focused their research to elucidate the complex relationship of chlamydial HSPs, especially chlamydial HSP60, and the host immune response. A central issue is whether the pathologic mechanisms in chronic chlamydial diseases are associated with an enhanced immune response to chlamydial HSP60 which can mediate tissue destruction through cytotoxic reactions, or whether they are related to the Th2 type of response that eventually leads to partial or temporary suppression of an effective antichlamydial response. Our review highlights the available knowledge between immune responses to chlamydial HSP60 and chronic chlamydial infections in human.