|Year : 2023 | Volume
| Issue : 1 | Page : 55-59
Positive associations of Chlamydia pneumoniae Immunoglobulin G and Immunoglobulin E antibodies and asthma in Iraqi children
Raghdah Maytham Hameed1, Huda Hadi Al-Hasnawi1, Haidar Abdul Amir Najim Abood2
1 Department of Medical Microbiology, University of Babylon, Babylon, Iraq
2 Department of Pharmacology, University of Kerbala, Kerbala, Iraq
|Date of Submission||20-Nov-2022|
|Date of Decision||17-Jan-2023|
|Date of Acceptance||27-Jan-2023|
|Date of Web Publication||13-Mar-2023|
Raghdah Maytham Hameed
Department of Medical Microbiology, University of Babylon, Babylon
Source of Support: None, Conflict of Interest: None
BACKGROUND: Chlamydia pneumoniae is an intracellular bacterium that causes respiratory tract infection.
AIM AND OBJECTIVE: The objective of the study was to evaluate the association between past C. pneumoniae infection and asthma.
MATERIALS AND METHODS: We examined the presence of C. pneumoniae Immunoglobulin (IgG) and Immunoglobulin E (IgE) antibodies by the commercial quantitative Enzyme-linked immunosorbent assay kits in 87 asthmatic children and 87 controls.
RESULTS: C. pneumoniae IgG antibody was significantly increased in patients (24.89 ± 16.65) as compared with controls (10.93 ± 6.75) P < 0.001. Further, the C. pneumoniae IgE antibody was significantly increased in patients (8.037 ± 4.645) compared to controls (6.52 ± 3.062) P = 0.024. There was a highly significant positive correlation between IgG and IgE levels (P < 0.001* r = 0.466). There was no significant difference in C. pneumoniae IgG and C. pneumoniae IgE levels among asthma severity groups (P = 0.507 and P = 0.539, respectively) and asthma-controlled groups (P = 0.858 and P = 0.517, respectively).
CONCLUSION: Compared to a control group, children with asthma have a significantly higher rate of C. pneumoniae IgG and C. pneumoniae IgE levels. In asthmatic patients, there is a positive correlation between C. pneumoniae IgG and C. pneumonia IgE. Controversially, C. pneumoniae infection has no role in asthma severity and control.
Keywords: Allergy, asthma, chlamydia, immunoglobulin E, immunoglobulin G
|How to cite this article:|
Hameed RM, Al-Hasnawi HH, Najim Abood HA. Positive associations of Chlamydia pneumoniae Immunoglobulin G and Immunoglobulin E antibodies and asthma in Iraqi children. J Prev Diagn Treat Strategies Med 2023;2:55-9
|How to cite this URL:|
Hameed RM, Al-Hasnawi HH, Najim Abood HA. Positive associations of Chlamydia pneumoniae Immunoglobulin G and Immunoglobulin E antibodies and asthma in Iraqi children. J Prev Diagn Treat Strategies Med [serial online] 2023 [cited 2023 Mar 31];2:55-9. Available from: http://www.jpdtsm.com/text.asp?2023/2/1/55/371627
| Introduction|| |
Asthma is one of the most common chronic conditions affecting children and adults. It is a common condition due to chronic inflammation of the lower respiratory tract. Asthma features variable airway obstruction and bronchial hyperresponsiveness.
Asthma is a complex disease whose origins are likely a combination of genetic predisposition and environmental exposures. Respiratory infections have long been considered an environmental risk factor for asthma. Atypical bacteria such as Chlamydia pneumoniae and Mycoplasma pneumoniae play a potential role in inducing and exacerbating asthma.,
C. pneumoniae is an intracellular bacterium that causes respiratory tract infection. C. pneumoniae is thought to promote asthma by increasing immunoglobulin E (IgE) levels and interleukin-4 concentration in asthmatics patients. The presence of C. pneumoniae -specific IgE Abs in stable asthmatics (without acute airway infection) with C. pneumoniae provides further evidence for ongoing stimulation of allergic responses by C. pneumoniae. However, IgE is one of many potential mechanisms that stimulate allergic reactions.
In the current study, we investigated the association of past C. pneumoniae infection that triggers C. pneumoniae IgE antibodies in asthmatics to examine the evidence for an association between atypical bacterial respiratory pathogens and asthma.
| Materials and Methods|| |
Study design and subjects
A case–control association study was performed. One hundred and eighty-seven subjects were recruited from Karbala Teaching Hospital for Children in the period extending from January 25 to May 24, 2022, including children with asthma (asthma group, n = 87) and healthy controls without allergic diseases (control group, n = 87).
The subjects of the present study were 57 male and 30 female children with asthma and children (46 males and 39 females) who were healthy controls [Table 1]. All asthmatic subjects had the European Respiratory Society/American Thoracic Society criteria for asthma. All asthmatic and nonasthmatic subjects underwent a total serum IgE test. The subjects' ages in this study ranged from 1 to 16 years. In this study, 79 asthmatic children visited the clinic regularly and received regular treatment with either inhaled corticosteroids (ICS) or Montelukast, while eight of them were newly diagnosed. The degree of asthma severity and control was identified based on the international standards diagnosed in the National Asthma Education and Prevention Program/Expert Panel Report 3 Guidelines by the specialist pediatrician. Patients with asthma in this study displayed typical clinical histories of mild, moderate, to severe asthma, and most patients had moderate asthma [Table 2].
The study protocol was approved by the Ethical Committee in the Babylon Medical College and the relevant ethical committee in the health directorate. Verbal approval was obtained from patients and/or their parents before sampling.
Sample collection and processing
After sampling 3 ml peripheral blood, serum was separated, divided into several aliquots in Eppendorf tubes, and immediately frozen at −80°C. Sera were collected from each participant to determine the total serum IgE levels by Combiwash Max-Planck-Ring 21 automated immunoassay analyzer (Human, Germany) using AccuBind total IgE Enzyme-linked immunosorbent Assay (ELISA) kit, USA (LOT NO. 25K1D1). Immunoglobulin G (IgG) antibody plasma levels against the C. pneumoniae (Human C. pneumoniae IgG, Cpn IgG ELISA Kit, LOT NO. 20220426, SUNLONG, China) and IgE antibody plasma levels against the C. pneumoniae (Human C. pneumoniae IgE, Cpn IgE ELISA Kit, LOT NO. 20220426, SUNLONG, China) were measured to all subjects using commercial quantitative ELISA kits in an automated instrument (Combiwash Max-Planck-Ring 21).
All the statistical analyses were conducted using the Statistical Package for the Social Sciences (SPSS) version 21 (GraphPad Software, San Diego, California, USA). Quantitative data were expressed as mean ± standard deviation (SD) using a t-test. The Chi-squared test was performed for qualitative data to compare the proportions of subjects. Spearman's test measured the correlation between antibacterial Ab. P <0.05 was considered to indicate the statistical significance and highly significant if P < 0.001.
| Results|| |
The characteristics of the subjects
In the present study, 31 confirmed patients with mild asthma symptoms, 42 had moderate asthma, and ten children with severe asthma were enrolled. Of the total of 87 asthmatic children, 33 (37.9%) cases were well controlled, and 33 (37.9%) patients were partially controlled, whereas 13 (14.9%) cases were not well controlled, and 8 (9.2%) cases were without control [Table 2].
The mean age of 87 patients was 7.833 ± 3.652 years old (ranging from 1 to 16 years old). The mean age in healthy control (N = 87) was 7.520 ± 3.658. The mean age was statistically nonsignificant between these two groups (P = 0.285). Approximately, 65.52% of asthmatic children were male, and 34.48% were female. The healthy control groups were matched in gender, and there were no significant changes between the asthmatic and nonasthmatic groups according to gender (P = 0.127) [Table 1].
Total serum IgE was significantly increased in the patients with asthma (mean ± SD, 398.88 ± 227.156 IU/ml) compared with the healthy controls (49.34 ± 66.831 IU/ml), as shown in [Table 1].
The mean ± SD of C. pneumoniae IgG in asthmatic children and control was 24.89 ± 16.65 ng/L and 10.93 ± 6.75 ng/L, respectively. The mean ± SD of the C. pneumoniae IgG between two groups of asthmatic and control is shown in [Table 3]. According to the t-test, there were statistically significant changes in IgG between the two groups (P < 0.001).
|Table 3: The mean±standard deviation of Chlamydia pneumoniae immunoglobulin G and immunoglobulin E between asthmatic patients and control groups|
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The mean ± SD of C. pneumoniae IgE in asthmatic children and control was 8.037 ± 4.645 ng/L and 6.52 ± 3.062 ng/L, respectively. The mean ± SD of the C. pneumoniae IgE between two groups of asthmatic and control is shown in [Table 3]. According to the t-test, there were statistically significant changes in IgE between the two groups (P = 0.024).
In this study, the correlation between C. pneumoniae IgG and IgE levels in asthmatic patients was investigated by Spearman's test. There was a highly significant positive correlation between IgG and IgE levels (P < 0.001 * r = 0.466), as shown in [Table 4] and [Figure 1].
|Figure 1: Scatterplot to Chlamydia pneumoniae IgE according to Chlamydia pneumoniae IgG. IgE: Immunoglobulin E, IgG: Immunoglobulin G|
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|Table 4: Correlation between Chlamydia pneumoniae immunoglobulin G and Chlamydia pneumoniae immunoglobulin E in asthmatic patients|
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The study did not detect any significant difference between the asthma severity groups according to the immunological parameters (C. pneumoniae IgG and C. pneumoniae IgE), as shown in [Table 5]. Further, the study did not detect any significant difference between the asthma-controlled groups according to the immunological parameters (C. pneumoniae IgG and C. pneumoniae IgE), as shown in [Table 6].
|Table 5: Comparison between asthma severity groups depending on immunological parameters in asthmatic children|
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|Table 6: Comparison between the controlled status of asthma groups depending on immunological parameters in asthmatic children|
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| Discussion|| |
C. pneumoniae is an obligate intracellular bacterium that causes respiratory infections in children and adults. Infections with C. pneumoniae also appear to play a role in the induction and exacerbation of asthma in children and adults.
In this study, we detected a highly significant difference in human C. pneumoniae IgG level between asthmatic children who have a high concentration (chronic infection) compared with clinic control (children without asthma) (P < 0.001), [Table 3]. This result agrees with the previous studies that prove a relationship between C. pneumoniae infection and asthma. Gencay et al. found that chronic infection with C. pneumoniae was more frequent in patients with asthma (18.2%) compared with control subjects (3.0%) (P < 0.01). Similarly, Cunningham et al. concluded that chronic C. pneumoniae infection is common in school-age children. In addition, Ferrari et al. detected high IgG levels more frequently in atopic subjects (P = 0.04). Equally, Miyashita et al. showed that the mean titer of IgG was significantly greater in asthma cases than in controls. In the same way, Calmes et al. mentioned that 65% of the asthmatic population had serum IgG toward C. pneumoniae.
Many reasons may cause this result
First, patients with asthma and other atopic conditions have significantly increased risks of severe infections with viruses and bacteria due to disruption and altered function of the airway epithelium and structural alterations of airways., Second, the inability of the host to completely eradicate the pathogens; as a result, C. pneumoniae can enter a state of dormancy with intermittent periods of replication. Third, ICS negatively affects many aspects of cell-mediated immunity and favors the shift from a T-helper-1-type toward a T-helper-2-type response. Because C. pneumoniae requires a T-helper-1-type immune reaction to be cleared thus, ICS may severely deteriorate the host's ability to eradicate it. Indeed, the associations between ICS use and bacterial respiratory infections remain controversial.
The study showed a significant difference in human C. pneumoniae IgE levels between asthmatic children and control (P = 0.024), [Table 3]. This result agrees with the results of a previous meta-analysis, which detected the possibility of some undetected antigens responsible for generating a cryptic IgE response in some asthma patients with C. pneumoniae. Hahn et al. showed that C. pneumoniae IgE detection was significantly (P = 0.001) associated with asthma when compared to healthy blood donor controls. Similarly, Smith-Norowitz et al. detected that C. pneumoniae IgE levels were higher in asthmatics than in nonasthmatics. Equally, Loeffler et al. found that C. pneumoniae IgE levels were significantly higher in asthmatic patients compared with nonasthmatic subjects (1.015 ± 0.305 vs. 0.39 ± 0.340; P < 0.001). One possible interpretation of these results is that C. pneumoniae -specific IgE antibody levels in asthmatic patients' serum may be induced by five chlamydial antigens (-Lipopolysaccharide antigen (LPS), Crp A, heat shock protein 60, putative outer membrane protein, and 250 kDa).
The current study showed a significant positive linear correlation between C. pneumoniae IgG levels and C. pneumoniae IgE levels in asthmatic children (P < 0.001). This result clarifies that C. pneumoniae antigen stimulates persistence-specific IgE production unless using antibiotics to eradicate the bacteria.
The presence of C. pneumoniae -specific IgE Abs in stable asthmatics (without acute airway infection) with C. pneumoniae provides further evidence for ongoing stimulation of allergic responses by C. pneumoniae.,
The present study detected no significant difference in C. pneumoniae IgG and IgE between asthma severity and controlled groups [Table 5] and [Table 6]. This result disagrees with previous studies that mentioned that C. pneumoniae IgE was strongly and positively associated with asthma severity., The explanation of this difference may result from the previous studies that used the immunoblotting technique to measure C. pneumoniae IgE, while our study used the ELISA technique.
| Conclusion|| |
We conclude that, compared to a control group, children with asthma have a significantly higher rate of C. pneumoniae IgG and C. pneumoniae IgE levels. In asthmatic patients, there is a positive correlation between C. pneumoniae IgG and C. pneumoniae IgE. Hence, the continued presence of C. pneumoniae antigen stimulates persistence-specific IgE production. The presence of C. pneumoniae-specific IgE may provide the ongoing stimulation of allergic responses by C. pneumoniae. Indeed, the study detected that Chlamydial disorders have no role in asthma severity and control. Thus, another study is required to see the role of C. pneumoniae infection in the pathogenesis of asthma.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]