Changes in inflammatory mediators as a result of intermittent hypoxia in obstructive sleep apnea syndrome.

Background: Inflammation plays an important role in obstructive sleep apnea syndrome (OSAS). The objective of this study was to investigate the relationship of serum C-reactive protein (CRP), pentraxin-3 (PTX-3), procalcitonin (ProCT), interleukin-33 (IL-33) and its soluble receptor ST2 (sST2) with the syndrome severity and to show theirs importance as biomarkers.

Methods: This study comprises a total of 84 identical (sex and age wise) cases. Full-night polysomnography was performed in each patient. OSAS diagnosis and severity index being based on the widely used criterion known as Apnea Hypopnea Index(AHI). Subgroups were as follows: 24(AHI < 5) controls, 28 mild-moderate OSAS(AHI 5-30) and 32 severe OSAS(AHI > 30).

Results: PTX-3, IL-33 and sST2 receptors were significantly higher in OSAS groups than the control group (P < .001). However, both CRP and ProCT levels were similar in all subjects. There was a positive correlation between PTX-3 and BMI (r = 0.446; P < .01), ODI (r = 0.555; P < .01), IL-33 (r = 0.348; P = .001) and sST2 (r = 326; P = .002), while there was a negative correlation with minimum SaO (r = -0.672; P < .01) in patient group. PTX-3 as a predictor of OSAS showed highest specificity (%91.7) and sensitivity (%91.7) (P < .001).

Conclusions: PTX-3 can be a new indicator reflecting the inflammatory state in patients with OSAS. Since patients with OSAS could have more hypoxic state during sleep, we found higher PTX-3 level in those patients and a negative correlation between PTX-3 and minimum SaO , which could explain that PTX-3 levels can increase with the severity of disease. Our results suggest that PTX-3 as an inflammatory biomarker may play a crucial role as an indicator of syndrome severity in OSAS.