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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 16  |  Issue : 3  |  Page : 262-269

Study of plasma homocysteine level in patients with bronchial asthma and its relation to asthma severity


1 Department of Chest Disease, Faculty of Medicine, Al-Azhar University, New Damietta, Egypt
2 Department of Internal Medicine and Clinical Pathology, Faculty of Medicine, Al-Azhar University, New Damietta, Egypt
3 Department of Clinical Pathology, Faculty of Medicine, Al-Azhar University, New Damietta, Egypt

Date of Submission13-Jul-2018
Date of Acceptance27-Jan-2019
Date of Web Publication15-Apr-2019

Correspondence Address:
Ramadan S Abdel-Aziz
No. 102, Flat 11, Mubark 70, New Damietta, Post Office: 1105, Madinat Dmyat Al-Jdydh
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/AZMJ.AZMJ_69_18

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  Abstract 


Background Homocysteine (HCY) may play a role in activation of immune system in some chronic diseases, like asthma and chronic obstructive pulmonary disease.
Aim The aim was to study the plasma HCY values in patients with bronchial asthma and its correlation to asthma severity.
Patients and methods A total of 80 patients were enrolled, and their ages ranged from 20 to 40 years. The study populations were categorized into three groups: high reversibility asthma (n=30), low reversibility asthma (n=30), and healthy nonasthmatics (Controls n=20). For all patients, full history taking, clinical examination, chest radiography, routine laboratory investigations, pulmonary function tests, and the HCY and immunoglobulin E levels were estimated.
Results The HCY measurements were found to be 8.7±0.6 µmol/l in the control group, 5.5±0.2 µmol/l in patients with high reversibility asthma, and 6.1±0.8 µmol/l in patients with low reversibility asthma. So, there was a significant variance between studied groups regarding HCY levels, but both high and low reversibility groups had low HCY when compared with control group. Moreover, the high reversibility asthma had low HCY levels when compared with low reversibility groups but without significant difference.
Conclusion Plasma HCY levels, instead of being increased, may be in the low normal range or decreased in patients with asthma, most probably owing to hypoxia and in the absence of factors leading to increased HCY levels.

Keywords: asthma, chronic obstructive pulmonary disease, homocysteine


How to cite this article:
Abdel-Aziz RS, Al Adl AS, Alsayyad MM, Emaran TM, Abdelsamee H. Study of plasma homocysteine level in patients with bronchial asthma and its relation to asthma severity. Al-Azhar Assiut Med J 2018;16:262-9

How to cite this URL:
Abdel-Aziz RS, Al Adl AS, Alsayyad MM, Emaran TM, Abdelsamee H. Study of plasma homocysteine level in patients with bronchial asthma and its relation to asthma severity. Al-Azhar Assiut Med J [serial online] 2018 [cited 2020 Jul 6];16:262-9. Available from: http://www.azmj.eg.net/text.asp?2018/16/3/262/255860




  Introduction Top


Total homocysteine (tHCY) is an amino acid with four carbons attached to a sulphydryl group. Homocysteine (HCY) is involved in the transmission of methyl groups and is an intermediate product of the metabolism of methionine [1], the process in which many coenzymes and cofactors are involved. In this procedure, two significant intermediates are produced: S-adenosylmethionine and S-adenosylhomocysteine. Generally, the ratio of S-adenosylmethionine to S-adenosylhomocysteine should be balanced. Under certain circumstances, this balance is disrupted, and the imbalance may be lined to specific disorders like inflammatory bowel diseases, diabetes (type 2), ischemic heart disease, and stroke [2]. On the basis of the finding that plasma levels of tHCY are proportionally associated with equivalent increases in plasma SAH concentrations and lymphocyte DNA hypomethylation, HCY pathogenicity is attributed to inhibition of DNA methyltransferase with subsequent disruption of DNA methylation and subsequent modifications in gene representation, which may be of critical importance in chronic disorders, many of which are related to increase in HCY [3].

According to the threshold, the normal levels of HCY were confined to 5–15 µmol/l. When the values exceeded 15 µmol/l, hyperhomocysteinemia was defined. It has been hypothesized that an increased HCY level in plasma could stimulate endothelial dysfunction, increase manufacture of reactive oxygen species, and reduce endothelial nitric oxide, which may be considered as the precursor of atherosclerosis. In addition, activating the immune system could also exert a key function in the origin and progression of cardiovascular diseases. In this situation, many cells of immune system and inflammatory factors are stimulated. In addition, other elements, including adhesion molecules, metalloproteins, and C-reactive protein, have been established in some trials to be positively linked to the values of HCY [2].

HCY is an amino acid that is ubiquitous in nature; its increased levels are associated with many disorders such as thrombotic disorders and lung. A significant association between cardiac disorders and HCY values has already been recognized. Many studies suggest that HCY is linked to chronic obstructive pulmonary disease (COPD) development and is accountable for changes in redox system with development of oxidative stress in COPD. However, the etiology and consequences of increased HCY in COPD are not well known [4].

It is known that HCY may exert a determinal action on the lung endothelial cells, but it is not known whether HCY could infiltrate airway epithelium or not [3].

Different studies reported conflicting data regarding the correlation between severity of airflow obstruction and plasma levels of HCY, but according to Nunomiya et al. [5], poor lung function was linked with higher levels of HCY. In addition, increased values of HCY were found to predict forced expiratory volume in the first second (FEV1) reduction among male smokers. HCY measurements were high in people with restrictive, obstructive, or mixed ventilatory lung diseases. In addition, HCY values were significantly increased in patients with mixed ventilatory diseases when compared with restrictive or obstructive lung disorders. During follow-up, patients with reduction in FEV1 had higher values of HCY than those who did not. Regression analysis proved that HCY levels are predictive for a reduction in FEV1.

However, HCY values are affected by other issues, such as sex, BMI, cigarette smoke inhalation, blood pressure, diabetic nephropathy, hyperlipidemia, liver function, and renal function (serum creatinine levels). Therefore, data in relation to measurements of HCY need to be wisely assessed, with consideration of background variations of the patients [5].

In patients with asthma, high airway bronchodilator reversibility (HR) (HR=ΔFEV1 postbronchodilator≥20%) has developed as a dependable physiologic indicator associated with severe airflow obstruction, increased utilization of healthcare resources, and poor control of such diseases. By contrast, traditional serum and blood indicators have not reliably correlated with disease activity [6].

HR asthma denotes a separate phenotype with worse lung functions and less-controlled disorder than low reversibility (LR) subgroups [7].


  Aim Top


The aim of this study was to evaluate the plasma HCY levels in bronchial asthma and its relation to asthma severity.


  Patients and methods Top


Study design

This study was conducted on 80 asthmatic patients and controls, whose ages ranged between 20 and 40 years. All patients with asthma were recruited from the inpatients of Chest Diseases Department, Al-Azhar University Hospital (New Damietta). The study populations were divided into three groups: HR asthma group (n=30), LR asthma group (n=30), and healthy nonasthmatic persons (controls: n=20). For all patients, full history taking and clinical examination, chest radiography, complete blood count, liver functions, kidney functions, pulmonary function tests, and the assay of HCY and immunoglobulin (Ig) E levels were done.

Ethical approval

The consent was signed by all participants. The research protocol did not disrupt any medical recommendations or prescriptions. In addition, the study protocol was approved by the local research and ethics committee of Al-Azhar Faculty of Medicine.

Inclusion criteria

The study included patients with age above 18 years and of both sexes.

Exclusion criteria

Obesity, cigarette smoking, hypertension, diabetes, liver and renal diseases, and conditions that may affect HCY level were the exclusion criteria.

Study protocol

Spirometry

All individuals underwent standard spirometry. Techniques were carried out according to the American Thoracic Society/European Respiratory Society standards (2005) using ZAN spirometry (ZAN MeBgerate GmbH, Oberthulba, Germany) [8].

Morning spirometry was done, and all patients had FEV1/forced vital capacity (FVC) of less than 70%, and postbronchodilator spirometry was performed after giving the patient a bronchodilator, such as an inhaled β-agonist, for example, salbutamol 400 μg. The following parameters were specifically measured: (a) FEV1 prebronchodilator and postbronchodilator, (b) FVC, (c) FEV1/FVC ratio, and (d) peak expiratory flow rate.

Sample collection

Approximately 10 ml of peripheral blood was obtained from all participants. Serum was separated from peripheral blood by microcentrifuge at 1008g at room temperature and stored in aliquots at −80°C until analysis.

Measurement of plasma homocysteine

This was performed with high-performance liquid chromatography (HPLC) (Agilent Technologies 1200 Series, USA; kits: Immuchrom GmbH, Heppenheim, Germany). Our study was done according to manufacturer’s directions: First, samples were concentrated and centrifuged for the estimation of HCY. Then, albumin-bound and the oxidized forms of HCY were decreased and changed into a fluorescent probe. In the precipitation phase, high-molecular materials were detached. The samples were correspondingly cooled, centrifuged, and injected into the HPLC system. The isocratic separation was done through HPLC at 30°C by a ‘reversed phase’ column. One run was for 5 min. The quantifications were carried out by the supplied plasma calibrator; the levels were calculated by the ‘internal standard (IS) method’. Calculation: Concentration sample (μmol/l) = [peak area patient × concentration calibrator (μmol/l)/peak area IS patient]×F. F=Peak area IS of the calibrator/peak area HCY of the calibrator.

Statistical methodology

Data entry and analysis were done using SPSS, version 17 (SPSS Inc., Chicago, IL, USA). Data were presented as mean, SD, median, number, and percentage. Cochran–Armitage χ2-test was used to compare qualitative data between the two groups of patients. Independent samples t-test was used to compare quantitative data of groups. Paired samples t-test was used to measure difference between means before and after the procedure (coronary angiography or percutaneous coronary intervention) in the same group. P value was considered significant when it is less than 0.05. Regression analysis was done and/or was calculated for independent risk factors.


  Results Top


In this study, there was no significant difference between studied groups regarding patient age, sex, white blood cells, and eosinophil count (%). However, there was a statistically significant difference between studied groups regarding pH, partial pressure of carbon dioxide (PaCO2), partial pressure of oxygen (PO2), bicarbonate (HCO3), and oxygen saturation (SO2), where both LR and HR groups had higher pH and HCO3 and low PaCO2, PO2, and SO2 ([Table 1]).
Table 1 Patient demographics, white blood cells, eosinophil count%, and arterial blood gases in studied groups

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In our study, there was a statistically significant difference between studied groups regarding vital capacity, FEV1/FVC; FEF25–75, PEF, and FEV1 before treatment and FEV1 at revision. In addition, there was a statistically significant difference between studied groups regarding PEF after treatment. Moreover, there was a significant increase after treatment when compared with corresponding values before treatment in each of HR and LR groups regarding all studied pulmonary functions ([Table 2]).
Table 2 Pulmonary function tests in studied groups before and after treatment

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In the studied groups, there was a statistically significant difference between studied groups regarding HCY levels, where both LR and HR groups had low HCY when compared with control group. On the contrary, there was no significant variance between studied groups regarding total IgE ([Table 3]).
Table 3 Total immunoglobulin E and homocysteine in studied groups

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Regarding asthma characteristics, all patients in LR and HR groups had daytime symptoms, whereas one (3.3%) patient in high both developed and developing countries reversibility group and three (10.0%) patients in LR group had limitation of activity. Nocturnal symptoms were positive in 26.7 and 10.0% of HR and LR groups, respectively, whereas the need for reliever was reported in all subjects in HR group and in 73.3% in LR group. Asthma exacerbations were reported in 23.3 and 70.0% of HR and LR groups, respectively. Finally, 73.3 and 26.7% in HR group were partially controlled and uncontrolled, respectively, compared with 23.3 and 76.7% of the LR group, respectively ([Table 4]).
Table 4 Asthma characteristics in studied groups

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In this work, there was a negative (inverse) correlation between total IgE and each of HCY, PO2, SO2, and FEF25–75 before and after treatment and FEV1 before and after treatment. On the contrary, there was significant proportional (positive) correlation between total IgE and each of eosinophilic count, pH, and HCO3 ([Table 5]). Moreover, there was a negative correlation between HCY and each of total IgE, eosinophilic count ([Figure 2]), pH, HCO3, and revision FEV1, whereas the correlation was positive with PaCO2, PO2 ([Figure 1]), SO2, vital capacity before treatment, FEV1/FVC before treatment, FEF25–75 before treatment, PEF before treatment, and FEV1 before treatment ([Table 5]).
Table 5 Correlation between homocysteine and other parameters in the studied populations

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Figure 1 Correlation between homocysteine and partial pressure of oxygen (PO2).

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Figure 2 Correlation between homocysteine and eosinophilic count.

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  Discussion Top


Asthma and COPD are marked etiologies of increasing morbidity and mortality all over the world [9]. So, respiratory diseases are a major socioeconomic problem all over the world [10]. Asthma is a simple disease, but it is a heterogenous condition marked by chronic airway inflammation [11]. The HR has developed as a dependable physiologic indicator linked to severe airflow obstruction, increased utilization of healthcare resource, and poor disease control. In contrast, classic physiologic indicators have not reliably correlated with disease activity [6],[12]. Indeed, several studies yielded paradoxical results, suggesting that increased values of some cytokines may be associated with milder phenotypes [12].

Asthma is characterized by an inflammation of systemic and chronic nature with an oxidative stress [13]. The oxidative stress is as important as various factors like age, duration, and lifestyle, which play a role in pathogenesis and overall effect of asthma. Increased creation of reactive oxygen species in asthma has been confirmed in previous studies and is also associated with changes in antioxidant activity of the lung and blood. Oxidative stress was blamed to play a role in the development of airway hyper-responsiveness [14].

It is widely supposed that increased HCY levels in blood can stimulate endothelial dysfunction, resulting in atherosclerosis and other cardiovascular diseases. In addition, the active inflammatory/immune systems might also take part in the lesion process [15],[16]. Anderson et al. [17] investigated the difference in plasma HCY in patients with COPD and healthy subjects and found that high plasma HCY levels were associated with reduced glutathione measurements in patients with COPD.

This had established an almost negative relation between HCY and reduced glutathione and gave rise to the hypothesis that HCY should be elevated in COPD because of impaired oxidative stress [3]. Cardiovascular disease is a frequent cause of morbidity encountered in patients with asthma and COPD. The most significant proof of this condition is the endothelial dysfunction in the pathogenesis of lung disease [5].

Moreover, endothelial dysfunction is stimulated by increased HCY [1], but it is not known if HCY penetrates the airway epithelium or not [3]. However, it is unknown whether oxidative stress is a consequence or a cause of HCY elevation.

Hence, we aimed to determine HCY levels in individuals with asthma to detect its potential role in the pathogenesis of asthma as a chronic inflammatory disease, or its link with the state of oxidative in asthma.

This study revealed that there was a statistically significant difference between studied groups regarding HCY levels, where both LR and HR groups had low HCY when compared with control group. Moreover, HCY levels were lower in the HR than LR group, but without statistically significant difference. Moreover, there was no significant correlation between spirometric issues and HCY levels in patients with asthma, whether HR or LR. So, we can conclude that there are no significant associations between HCY levels and asthma and its severity.

In contrast to our study, Avci and Avci [18] had found that the HCY values in asthma and COPD were significantly increased than the control group (P<0.05). Moreover, the relationship between sex and HCY in patients with asthma and COPD was assessed, and the significance of sex was revealed in those patients. When the association between HCY levels and male sex was examined in their study, a significant association was found (P<0.05).

Besides, the highest HCY level in male sex is stated in many studies as in their study [5],[19]. Seemungal et al. [20] also found tHCY levels were increased in male patients with COPD when compared with women with COPD, and in patients with low FEV1/FVC ratio and low FEV1% predicted.

However, they stated that the possible pathogenic mechanism remains unsolved, and convincing evidence to support a causal relationship between elevated concentrations of HCY and risk of developing COPD is absent. Plasma HCY concentrations may be altered by several physiological factors: age, sex, and body mass [3].

Smoking is by consensus the most significant risk factor in the occurrence of COPD [21]. Cigarette smoking leads to high levels of plasma HCY [22],[23], though the effect may be variable [24].

In the study by Khan et al. [4], they reported a significant reduction of elevated HCY measurements through daily supplementation by folic acid for 6 weeks, however; it did not affect the lung function in COPD. Their data strongly suggested that hyperhomocysteinemia may result from poor folic acid status in patients with COPD which are recognized cofactors in tHCY degradation [1].

In our study, we selected the age to be from 20 to 40 years old to avoid the effect of age on HCY level; thus, there was no correlation between HCY level and age in this study. However, there are several factors that could contribute to hyperhomocysteinemia such as vitamin B deficiency [25], ageing [26], hypertension [27], renal dysfunction [28], diabetic nephropathy [29], and cigarette smoking [30],[31]. Because many elements may adjust HCY levels, so defining the main etiologies of hyperhomocysteinemia in separate patient is complex [20],[22],[32].Fimognari et al. [32] demonstrated that HCY measurements were elevated in patients with COPD, and that low levels of folate and vitamin B12, as well as hypertriglyceridemia were independent predictors of hyperhomocysteinemia. They concluded that the mechanism for hyperhomocysteinemia observed in patients with COPD may simply be owing to a reduction in folate and vitamin B12 or increased triglyceride levels.

Although in our study there was a negative (inverse) correlation between HCY and total IgE, Li et al. [2] had studied if serum HCY concentration is significantly associated with inflammatory/immune factors and concluded that C4, C-reactive protein, and IgM in serum are significantly associated with HCY concentration, but they recommended further studies about the mechanism of this interaction.

In this study, there was a positive correlation between HCY level and PO2 as well as SO2. According to Kai et al. [22], there is a likelihood that hypoxia plays a role in the reduction of the plasma HCY measurements via downregulation of methionine adenosyltransferase gene transcription. The difficulty with this hypothesis was that it had been based on a very small subset difference in an already small study. However, in our study, the addition of the hypoxia to the absence of associating factors that lead to hyperhomocysteinemia can explain why HCY measurements are lower in the patients than the controls, in addition to its lower levels in HR than LR group despite being statistically nonsignificant.


  Conclusion Top


Plasma HCY level may be on the low normal range or even decrease in patients with asthma under the effect of hypoxia and in absence of factors that lead to hyperhomocysteinemia. So, in our trial, there was no link between HCY measurements and HR or LR asthma in adults from 20 to 40 years old. Accordingly, we can speculate on that the elevation of HCY level in COPD and patients with asthma in the other studies and absence of this elevation in patients with asthma in our study may be owing to the association of elements that lead to upsurge in the HCY level rather than being initially participating in the inflammatory or immune response or even resulting from the oxidative stress states.

Acknowledgements

The authors acknowledge Dr Mahmoud Helmy, Assistant Professor of Forensic Medicine and toxicology, for his technical help in preparing manuscript for publications.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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