Sleep apnea and autoimmune diseases: How are they connected?
In a new study, researchers investigated inflammatory cytokines that are associated with both obstructive sleep apnea (OSA) and autoimmune diseases. They found that cytokine levels are abnormal in people with untreated OSA.
It is impossible to overstate the importance of a good night’s sleep. Getting the right amount of sleep can lower the risk of weight gain, reduce inflammation, improve productivity, and much more.
Many people struggle to get enough rest each night. For some, this is due to sleep disorders, such as insomnia and sleep apnea.
OSA was the focus of a new study, which appears in the journal Clinical Immunology. Researchers at the University of Georgia (UGA) in Athens looked at the connection between untreated OSA and autoimmune diseases.
According to the National Institutes of Health (NIH), sleep apnea occurs “when the upper airway becomes blocked repeatedly during sleep, reducing or completely stopping airflow.”
A person with sleep apnea may momentarily stop breathing multiple times per hour while sleeping.
Signs and symptoms of sleep apnea include:
gasping for breath while asleep
Various factors can contribute to a person developing OSA. These include obesity, enlarged tonsils, and heart or kidney failure.
Doctors often treat sleep apnea with airway therapy, using a continuous positive airway pressure (CPAP) machine. CPAP machines keep the upper airway from becoming blocked during sleep. Some people with OSA use mouthguards to help keep their airways open.
OSA can increase the risk of serious medical problems. The American Sleep Apnea Association believe that at least 38,000 people die each year from heart issues associated with sleep apnea.
Bradley Phillips, director of UGA’s Biomedical and Health Sciences Institute, led the new study. The team’s goal was to investigate the connection between OSA and autoimmune diseases.
In autoimmune diseases, the immune system attacks healthy cells in error. Autoimmune diseases include rheumatoid arthritis, lupus, and multiple sclerosis.
While the authors acknowledge that scientists have known about connections between sleep apnea and autoimmune disorders for some time, they explain that the relationship is “poorly understood.”
“This paper looks at what may be the underlying mechanisms that increase someone’s risk for autoimmune disorders because they have untreated obstructive sleep apnea,” says Phillips.
Various cells in the body release cytokines, which are small proteins that have specific effects on the ways that cells communicate.
The researchers looked at the levels of four inflammatory cytokines: APRIL, CD30, IFN-Alpha-2, and IL-2. The scientists chose these cytokines because they are often elevated in people with autoimmune disorders.
A total of 46 people participated in the study. The researchers divided them into three groups, the first of which included 19 people receiving treatment for OSA. In this group, 18 people received airways therapy via a CPAP machine, and the other person used a mouthguard.
The second group comprised 19 participants with untreated OSA. The final group — the control subjects — included eight people without sleep apnea.
For three of the four autoimmune-related cytokines, the researchers observed that levels in participants with OSA were low compared with those in the control group. However, the tests indicated that cytokine levels in people receiving airways therapy were closer to the cytokine levels of people without OSA.
According to the authors, “We found the levels of four cytokines with previously reported [roles] in autoimmunity were significantly different in airways treated OSA patients relative to untreated OSA patients.”
The researchers believe that long-term hypoxia may contribute to the difference in cytokine levels. Hypoxia refers to the body being unable to get enough oxygen, which can happen when OSA goes untreated.
In the study, the authors note that:
“Airways therapy of OSA patients appears to be an effective way to control aberrant levels of these four cytokines involved in autoimmune disease and immune processes.”
People with sleep apnea can also have cardiovascular problems. Phillips notes that the relationship between OSA and other diseases is complex, making it challenging to study.
“OSA in adults is commonly first diagnosed in midlife but increases with age,” says Phillips. “With increased age, you are also at risk for other diseases, and it’s very challenging for clinicians and researchers to determine if it’s OSA alone that causes other disorders, or if OSA only worsens the severity and progression of an underlying disease. In the case of high blood pressure, we know untreated OSA can cause hypertension and make blood pressure drug therapy ineffective. If OSA is a key player, then it should be evaluated and treated along with other conditions.”