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Introduction

Obstructive sleep apnea hypopnea syndrome (OSAHS) is a common sleep disorder with potential risks, such as cardio-cerebrovascular events and multiple organ injury. The key clinical manifestations of OSAHS include disturbances in sleep structure and nocturnal hypoxemia and hypercapnia, which may lead to excessive daytime sleepiness, cardiocerebrovascular events and multiple organ injury that may seriously affect the quality of life (QOL) and life expectancy of OSAHS patients (1). The incidence of OSAHS is ~2–4% in adults worldwide; however, recent epidemiological studies have suggested that the incidence of OSAHS is increasing in the younger members of the population (2–4).

The interest in OSAHS has increased in healthcare settings and society in recent years due to the high incidence and mortality rate of the disorder (5,6). Clinical statistical data have suggested that the 5-year mortality rate of OSAHS patients without treatment is as high as 11–13%, and ~3,000 mortalities per day are associated with OSAHS worldwide (7). In addition, excessive daytime sleepiness decreases the QOL and cognitive and social functions of OSAHS patients (8), and has been associated with a 3–7-fold increase in road traffic accidents (9). However, the main clinical risk associated with OSAHS is severe multi-organ injury, and OSAHS has emerged as an independent risk factor contributing to hypertension, coronary heart disease, cerebrovascular diseases, diabetes and cor pulmonale (10). Previous studies demonstrated that patients with OSAHS experience systemic inflammation and oxidative stress, which are extensively involved in the development, occurrence and progression of OSAHS, resulting in numerous complications (11–14).

At present, OSAHS may be treated using holistic therapies, medical treatment (tricyclic and serotonergic agents), medical devices, including oral appliances and continuous positive airway pressure (CPAP), and surgery (15). However, no effective drug currently exists for the treatment of OSAHS, and OSAHS patients typically have a poor compliance and tolerance with mechanical treatments (16,17). In addition, surgery has been associated with potential complications, such as profuse bleeding, cardiopathy and hypertension, and uncertainty regarding its long-term therapeutic effect (18,19). Therefore, additional research is required in order to develop more effective therapeutic strategies for the treatment of OSAHS.

Natural Chinese herbal medicines that exert anti-OSAHS activities have emerged as a potential strategy for the treatment of OSAHS (20). In Traditional Chinese Medicine (TCM), the treatment and prevention of the inflammatory responses and oxidative stress associated with OSAHS involves a holistic approach using multi-level and multi-channel control (21). TCM differs from Western medicine in that Western medicine adopts strategies that block a single step in a particular process, whereas TCM uses an overall therapeutic approach to treat and prevent inflammatory responses and oxidative stress with the aim of improving the patient QOL (4). These unique advantages of TCM treatment have attracted the attention of numerous researchers searching for novel ways to combat OSAHS-associated inflammatory responses and oxidative stress (22,23). Among them, Jaiwei Di Tan Tang is a natural Chinese herbal medicine, which may serve a role in anri-OSAHS activities (24,25)

The present study aimed to investigate the potential clinical application of TCM to the treatment of patients with OSAHS, in particular in the prevention of OSAHS inflammatory responses and oxidative stress.

Materials and methods

Study design

A total of 60 outpatients at the Department of Respiratory Diseases of The Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine (Fuzhou, China), complaining of snoring, nocturnal apnea and daytime sleepiness, were enrolled in the present study between October 2013 and July 2014. The patients were diagnosed with OSAHS based on the results of a polysomnography (PSG). Informed consent was obtained from all patients prior to initiation of the study. The present study was approved by the local Ethics Committee of Fujian Medical University (Fuzhou, China). Patients were excluded if they had a history of asthma, bronchiectasis, chronic obstructive pulmonary disease, severe systemic diseases or allergic rhinitis, and if they were active smokers or pregnant. Patients with asthmatic symptoms, including episodic breathlessness, wheezing, coughing and chest tightness, were also excluded. The body mass index (BMI) was calculated for all patients and the sleeping status of the patients was assessed using the Epworth sleepiness scale (ESS). The 60 OSAHS patients that met the inclusion criteria were randomly allocated into experimental or control groups using the Java random number method using SPSS software 16.0 (SPSS, Inc., Chicago, IL, USA).

Treatment

Patients in the control group received the conventional therapeutic strategy, which included lifestyle changes such as quitting smoking, abstaining from alcohol, discontinued use of sedative and hypnotic drugs (as well as any other drugs that may induce or exacerbate OSAHS), alterations to the patient's sleeping position, including adopting side-sleeping positions and avoiding the supine position and limiting overexertion during the daytime. In addition, the patients received instructions on exercise and planned sports programs, as follows: i) Walking had to be the main sports form; ii) the patient had to gradually increase the activity intensity within the range of the target heart rate [target heart rate =(220-age) × (70–85%)]; iii) the patient had to walk ~3,000–4,000 steps per day in ~30 min for 3 months; and iv) the patients had to perform appropriate exercise 4–5 times per week. Appropriate exercise was referred to as a feeling of normal energy following each exercise. The patient was permitted 2–3 breaks during each episode of exercise, with each break not exceeding 5 min. The patients were advised that exercise should be terminated immediately upon experiencing heart palpitations, chest stuffiness or dyspnea.

In addition to the conventional treatment, the patients in the experimental group received oral administration of Jiawei Di Tan Tang, which consisted of 15 g Dangshen, 30 g Huangqi, 15 g Baizhu, 9 g Chenpi, 9 g Fabanxia, 15 g Fuling, 9 g Zhishi, 12 g Zhuru, 15 g Shichangpu, 12 g Dannanxing, 15 g Danshen, 15 g Chuanxiong, 9 g Taoren, 15 g Yujin, 15 g Jiangcan and 15 g Dilong. The herbal components of Jiawei Di Tan Tang were prepared by the TCM pharmacy Kang Ren Tang Medical Hall Pte., Ltd. (Beijing, China) in the form of granules. Jiawei Di Tan Tang was administered orally in two doses (morning and evening), dissolved in boiling water. The patients were monitored weekly by telephone or outpatient visits to record their compliance with their exercise and medical treatments. The treatment course lasted for 12 weeks, and the parameters recorded during the course of treatment were statistically analyzed in order to evaluate the therapeutic effect of Jiawei Di Tan Tang.

Clinical symptoms

Snoring, nocturnal apnea, sleepiness, fatigue and chest congestion were scored by the patients in the two groups prior to and following treatment, as follows: 0 for none of the above, 1 for mild presentation, 2 for moderate presentation and 3 for severe presentation. Clinical syndromes were defined according to 2002 Guidelines for Research on New Chinese Herbal Medicines (26).

ESS

The ESS is a simple eight-item self-administered scale that has been widely used in clinical practice to quantify the level of daytime sleepiness in various situations. This has a score range of 0–24 and scores >10 are indicative of excessive daytime sleepiness (27).

PSG

The patients in both groups underwent a full overnight in-laboratory, diagnostic PSG using the Compumedics E-Series EEG/PSG Recording System (Compumedics USA, Inc., Charlotte, NC, USA) or the Alice 5 Diagnostic Sleep System (Philips Medical Systems, Inc., Bothell, WA, USA), depending on which hospital they were examined in, prior to and following treatment. The electroencephalography (EEG) electrodes were positioned according to the international 10–20 system. Each PSG involved monitoring the sleep status of the patient by EEG, electrooculography and electromyography, and an analysis of airflow and respiratory muscle effort by monitoring electrocardiographic rhythms and blood oxygen saturation (SaO2). The thoracoabdominal plethysmograph (Colsan Company, Guangzhou, China), oronasal temperature thermistor and nasal-cannula pressure transducer systems (Sinochip Electronics Co., Ltd., Nanjing, China) were used to identify apnea and hypopnea. The transcutaneous finger pulse oximeter was used to measure SaO2. Sleep was recorded and scored according to a standard method (28). The apnoea-hypopnea index (AHI) was defined as the sum of the number of apneas and hypopneas per hour of sleep. OSAHS was defined as an AHI of 5 events/h and the presence of clinical symptoms, including excessive daytime sleepiness, loud snoring, witnessed apneas and nocturnal apnea or an AHI of 5 events/h without any OSAHS symptoms (29). An AHI <5 events/h was considered within the normal limit. No split-night studies were performed.

Biochemical evaluation

Morning fasting venous blood samples (5 ml) were drawn from each patient in the two groups prior to and following treatment, and centrifuged at 1,409 × g for 10 min to separate the serum. The upper-layer supernatant (0.25 ml) containing growth factors was accurately weighed and stored at −70°C prior to use. Serum levels of C-reactive protein (CRP; cat. no. E02481), interleukin (IL)-6 (cat. no. E03811) and tumor necrosis factor (TNF)-α (cat. no. E037114) were detected using the enzyme-linked immunosorbent assay kits (Shanghai Source Biological Technology Co., Ltd., Shanghai, China), according to the manufacturer's protocol. Serum superoxide dismutase (SOD) levels were detected by the xanthine oxidase method (SOD Assay Kit; cat. no. 19160; Sigma-Aldrich, St. Louis, MO, USA). Serum malondialdehyde (MDA) levels were detected using the thiobarbituric acid colorimetric method (Nanjing JianCheng Bioengineering Institute, Nanjing, China), according to the manufacturer's protocol.

Statistical analysis

Data were analyzed using SPSS software 16.0 and expressed as the mean ± standard deviation. Inter-group comparisons were performed using the Student's t-test for normally distributed data, the Wilcoxon rank-sum test for non-normally distributed data, or a paired t-test. In addition, counted data were analyzed using a χ2 test. P<0.05 was considered to indicate a statistically significant difference.

Results

Subjects

The control group constituted 20 males and 10 females, who ranged in age from 35–67 years old, with a mean age of 50.36±14.15 years old. The mean disease duration ranged from 2–13 years with a mean disease duration of 5.98±4.02 years. The mean AHI was 32.18±15.67 events/h and the mean BMI was 24.47±2.65 kg/m2. The mean ESS was 13.52±5.17. The study group consisted of 19 males and 11 females, who ranged in age from 33–65 years old, with a mean age of 49.87±13.59 years old. The disease duration ranged from 3–12 years with a mean disease duration of 6.32±3.15 years. The mean AHI was 32.66±15.95 events/h, the mean BMI of this group was 24.29±2.08 kg/m2 and the mean ESS was 13.15±4.98. There was no significant difference in age, gender, disease duration, BMI and AHI and ESS scores between the two groups (P>0.05; Table I). The results suggest that the two sets of data are comparable.

Table I. Comparison between the control and study groups.

Table I.

Comparison between the control and study groups.

Metric	Control group (n=30)	Study group (n=30)	P-value
Age, years	50.36±14.15	49.87±13.59	0.41
Gender, M/F	20/10	19/11	0.65
Disease course	5.98±4.02	6.32±3.15	0.52
AHI	32.18±15.67	32.66±15.95	0.49
BMI, kg/m2	24.47±2.65	24.29±2.08	0.28
ESS	13.52±5.17	13.15±4.98	0.58

[i] Data are presented as the mean ± standard deviation. AHI, apnea hypopnea index; BMI, body mass index; ESS, epworth sleepiness scale; M, male; F, female.

Clinical symptom scores

Snoring, nocturnal apnea, daytime sleepiness and chest pain scores were significantly decreased in the experimental group following treatment, compared with those pre-treatment (P<0.05; Table II). Conversely, there was no significant difference in these scores prior to and following treatment in the control group (P>0.05). In addition, the post-treatment clinical symptoms scores were significantly decreased in the experimental group compared with those in the control group (P<0.05; Table II). The results suggest that there are significant differences between the experimental and control group.

Table II. Clinical symptom scores pre- and post-treatment.

Table II.

Clinical symptom scores pre- and post-treatment.

Symptom	Control group (n=30)	Experimental group (n=30)
Snoring
Pre-treatment	3.25±0.50	3.22±0.47
Post-treatment	3.11±0.48	2.86±0.49a,b
Nocturnal apnea
Pre-treatment	2.86±0.41	2.78±0.39
Post-treatment	2.67±0.45	2.47±0.34a,b
Sleepiness
Pre-treatment	2.91±0.57	2.95±0.61
Post-treatment	2.73±0.62	2.44±0.58a,b
Fatigue
Pre-treatment	3.28±0.48	3.24±0.52
Post-treatment	3.26±0.51	2.89±0.55a,b
Chest stuffiness
Pre-treatment	2.81±0.49	2.76±0.54
Post-treatment	2.67±0.52	2.39±0.59a,b

{ label (or @symbol) needed for fn[@id='tfn2-etm-0-0-3484'] } Data are presented as the mean ± standard deviation.

a P<0.05 vs. pre-treatment

b P<0.05 vs. control group.

Evaluation of ESS and PSG results

The mean ESS score was significantly lower in the experimental group post-treatment compared with that pre-treatment (P<0.05), whereas there was no significant difference in the ESS score prior to and following treatment in the control group (P>0.05). In addition, the mean ESS score in the experimental group post-treatment was significantly decreased compared with that of the control group (P<0.05; Table III).

Table III. ESS and AHI scores and SaO2 pre- and post-treatment.

Table III.

ESS and AHI scores and SaO2 pre- and post-treatment.

Metric	Control group (n=30)	Experimental group (n=30)
ESS
Pre-treatment	13.52±5.17	13.15±4.98
Post-treatment	11.27±5.26	9.03±4.74a,b
AHI
Pre-treatment	32.18±15.67	32.66±15.95
Post-treatment	26.47±13.71	20.44±13.25a,b
Lowest nocturnal SaO2
Pre-treatment (%)	84.17±6.49	83.92±6.41
Post-treatment (%)	86.33±7.25	89.53±7.16a,b

{ label (or @symbol) needed for fn[@id='tfn5-etm-0-0-3484'] } Data are presented as the mean ± standard deviation.

a P<0.05 vs. pre-treatment

b P<0.05 vs. control group. AHI, apnea hypopnea index; ESS, Epworth sleepiness scale; SaO₂, blood oxygen saturation.

In the experimental group, the AHI was significantly lower and the lowest nocturnal SaO2 was significantly higher post-treatment compared with these pre-treatment (P<0.05). Conversely, there was no significant difference in the AHI and the lowest nocturnal SaO2 prior to and following treatment in the control group (P>0.05). In addition, the AHI and the lowest nocturnal SaO2 score in the experimental group post-treatment was significantly decreased compared with the control group (P<0.05) (Table III). The results suggest that there are significantly differences in ESS, PSG, and AHI between the experimental and control group.

Serum biomarkers of oxidative stress

Levels of the oxidative markers SOD and MDA were significantly lower in the experimental group post-treatment compared with those pre-treatment (P<0.05), whereas there was no significant difference in the SOD and MDA levels prior to and following treatment in the control group (P>0.05). In addition, the SOD and MDA levels in the experimental group post-treatment were significantly decreased compared with the control group (P<0.05; Table IV). The results suggest that oral administration of the traditional Chinese herbal formula Jiawei Di Tan Tang is able to attenuate serum biomarkers of oxidative stress.

Table IV. SOD and MDA levels pre- and post-treatment.

Table IV.

SOD and MDA levels pre- and post-treatment.

Factor	Control group (n=30)	Experimental group (n=30)
SOD, U/ml
Pre-treatment	87.03±7.62	86.35±8.18
Post-treatment	90.58±8.93	101.24±9.52a,b
MDA, nmol/ml
Pre-treatment	11.35±1.51	11.27±1.24
Post-treatment	10.80±1.46	9.64±1.35a,b

{ label (or @symbol) needed for fn[@id='tfn8-etm-0-0-3484'] } Data are presented as the mean ± standard deviation.

a P<0.05 vs. pre-treatment

b P<0.05 vs. control group. SOD, superoxide dismutase; MDA, malondialdehyde.

Serum inflammatory cytokines

The levels of the serum inflammatory cytokines TNF-α, IL-6 and CRP following treatment were significantly reduced in the experimental group post-treatment compared with those pre-treatment (P<0.05). Conversely, there was no significant difference in the serum levels of TNF-α, IL-6 and CRP prior to and following treatment in the control group (P>0.05). In addition, the post-treatment levels of these factors were significantly lower in the experimental group compared with those in the control group (P<0.05; Table V). The results suggest that oral administration of the traditional Chinese herbal formula Jiawei Di Tan Tang is able to attenuate inflammatory responses in patients with OSAHS.

Table V. Serum levels of inflammatory cytokines pre- and post-treatment.

Table V.

Serum levels of inflammatory cytokines pre- and post-treatment.

Serum factor	Control group (n=30)	Experimental group (n=30)
TNF-α, pg/ml
Pre-treatment	57.86±12.33	58.96±11.59
Post-treatment	53.08±9.85	39.54±10.26a,b
IL-6, pg/ml
Pre-treatment	86.97±16.72	87.32±16.28
Post-treatment	80.15±15.68	73.18±15.15a,b
CRP, µg/ml
Pre-treatment	13.12±5.23	13.25±4.95
Post-treatment	10.96±6.01	7.93±5.16a,b

{ label (or @symbol) needed for fn[@id='tfn11-etm-0-0-3484'] } Data are presented as the mean ± standard deviation.

a P<0.05 vs. pre-treatment

b P<0.05 vs. control group. TNF, tumor necrosis factor; IL, interleukin; CRP, C-reactive protein.

Discussion

According to the TCM theory, turbid phlegm and blood stasis are the main factors contributing to the pathogenesis of OSAHS, implying that the disease is predominantly located in the pulmonary tissues (pharynx, larynx and airway) (30,31). Pulmonary, spleen or renal dysfunctions resulting from a congenital abnormality or improper post-birth recuperation may lead to intrinsic production of turbid phlegm, phlegm and blood stagnation, airway roughness, spleen qi deficiency, qi deficiency to attenuate blood stasis and weakness of the pharyngeal muscle due to insufficient qi blood nourishment (32). These factors may result in airway collapse and airway flow resistance (33,34).

Previous studies have implicated systemic inflammation and oxidative stress in the pathogenesis of OSAHS (11–13,18,35), leading to multiple complications, such as cardiovascular disease, cognitive impairment and metabolic syndrome. Therefore, reducing oxidative stress and inflammatory responses may ameliorate the symptoms of OSAHS and improve the QOL of OSAHS patients.

Vgontzas et al (36) reported that the levels of pro-inflammatory cytokines, including IL-6 and TNF-α, were elevated in OSAHS patients, and associated them with the clinical manifestation of daytime sleepiness. Similarly, Guven et al (37) demonstrated that the levels of CRP and IL-6 were markedly upregulated in OSAHS patients, and were restored to within the normal range following CPAP therapy. Furthermore, Constantinidis et al (38) reported that the stimulation of peripheral mononuclear cells with lipopolysaccharides (LPS) resulted in the upregulation of TNF-α and IL-6 in OSAHS patients, which is consistent with the elevation of plasma TNF-α and IL-6 in OSAHS patients (39). In addition, the extent of TNF-α and IL-6 upregulation was associated with the frequency of apnea and the duration of hypopnea.

An imbalance exists between oxidation and antioxidation in OSAHS patients (39). A previous study demonstrated that serum levels of oxidative stress biomarkers were significantly elevated in OSAHS patients compared with a control group, and they were significantly decreased following CPAP therapy (13,37). In addition, Priou et al (40) reported that the levels of reactive oxygen species were elevated in OSAHS patients. Furthermore, Chen et al (41) demonstrated that the levels of lipid peroxides, including MDA, were significantly elevated, whereas the levels of antioxidants were decreased, in the myocardial tissue of rats exposed to an intermittent hypoxic condition compared with a control group. These results suggested that intermittent hypoxia in patients with OSAHS may induce oxidative stress.

Previous studies have demonstrated that Chinese herbal medicines that tonify qi and inhibit blood stagnation are able to relieve the symptoms of OSAHS and attenuate oxidative stress and inflammatory responses (42–44). In the present study, Jiawei Di Tan Tang, which consists of 16 classic Chinese herbal products, Dangshen, Huangqi, Baizhu, Chenpi, Fabanxia, Fuling, Zhishi, Zhuru, Shichangpu, Dannanxing, Danshen, Chuanxiong, Taoren, Yujin, Jiangcan and Dilong, was used. This has been demonstrated to tonify qi, remove and dissolve phlegm, inhibit stagnation, induce coughing, eliminate dampness, reduce temperature and improve lung function (45). Previous studies reported that Huangqi was able to protect against lipid peroxidation by binding to SOD in the body in order to increase its activity (46–48). Furthermore, in vitro studies demonstrated oxygen free radical (OFR) clearing activities for the three extracts of Huangqi (49–51), and Huangqi injection was revealed to reduce the plasma levels of MDA, CRP and IL-6, and increase the levels of SOD in a rat model of chronic bronchitis (43), indicating that Huangqi injection is able to attenuate oxidative stress and the inflammatory response in rats with chronic bronchitis. Dangshen exerts antioxidant, anti-oxidative stress and numerous other biological activities (52,53), and was demonstrated to reduce the TNF-α concentration in insulin resistant rats (54). In addition, Danshen was shown to reduce the content of OFR, increase SOD activity and slightly increase the levels of nitric oxide (55). Tanshinone has been reported to inhibit the production of inflammatory cytokines, protect endothelial cells, exert antioxidant activity and inhibit cell apoptosis (56). Similarly, Ligustrazine was able to attenuate the apoptosis of vascular tissue cells by inhibiting the formation of large quantities of OFR during the oxidative stress response, and ameliorate vascular endothelial injury due to oxidative stress (57). Furthermore, Ligustrazine was reported to reduce the secretion of TNF-α and IL-6 from LPS-induced macrophages (58). In a previous study, Yujin was able to inhibit Helicobacter pylori-induced gastritis and reduce the blood level of IL-6 (59), and anti-oxidative activities have been reported for Zhishi, Banxia and Chenpi (60–62). In the present study, the serum levels of SOD, MDA, TNF-α, IL-6 and CRP were significantly decreased in the OSHAS patients of the experimental group following treatment with Jiawei Di Tan Tang compared with those of the control group (P<0.05). Conversely, there were no significant changes in the OSHAS patients who received the conventional treatment only (P>0.05). In the experimental group, the serum levels of SOD, MDA, TNF-α, IL-6 and CRP significantly decreased post-treatment compared with pre-treatment levels (P<0.05). These results suggested that Jiawei Di Tan Tang was able to protect against oxidation and inhibit the production of inflammatory cytokines in patients with OSHAS.

The present study selected OSAHA outpatients whose AHI and ESS scores and BMI were higher than 30, 13 and 26, respectively, in the absence of comorbidities. This was consistent with two previous studies that also included homogenous populations of OSAHS patients without comorbidities (63,64). The results of the present study demonstrated that AHI and ESS scores were significantly decreased in the experimental group following treatment with Jiawei Di Tan Tang, as compared with those pre-treatment (P<0.05). Conversely, there were no significant alterations in these parameters in the control group (P>0.05). Furthermore, the clinical symptom scores were significantly improved in the experimental group post-treatment compared with pre-treatment scores (P<0.05), whereas there was no significant change in the clinical symptom scores of the control group (P>0.05). Compared with the control group, the AHI and ESS scores and nocturnal minimum SaO2, were significantly reduced in the experimental group following treatment with Jiawei Di Tan Tang (P<0.05).

In conclusion, the present study demonstrated that Jiawei Di Tan Tang has a protective effect against oxidative stress and inflammatory responses in patients with OSAHS, and that it attenuates the symptoms of OSHAS. These results suggested that the clinical application of Jiawei Di Tan Tang may improve the QOL of OSHAS patients. Furthermore, the results of the present study may provide an experimental foundation for assessing the use of Chinese herbal medicines in the treatment of OSAHS.

Acknowledgements

The present study was supported by a grant from the Fujian Provincial Bureau of Public Health for Chinese Herbal Medicine Research (grant no. wzln201307).

References