Vitamin D deficiency and interleukin-17 relationship in severe obstructive sleep apnea–hypopnea syndrome

PURPOSE: We aimed to assess Vitamin D (VD) abnormalities in patients with severe obstructive sleep apnea–hypopnea syndrome (OSAHS), to study its association with clinical and polygraphic data, and to correlate VD levels with interleukin-17 (IL-17). METHODS: Ninety-two patients with severe OSAHS were consecutively enrolled between September 2014 and February 2016 and compared to age-, sex-, and body mass index (BMI)-matched controls. Anthropometric parameters and medical history were collected. The serum levels of VD and IL-17 were determined by radioimmunoassay and enzyme-linked immunosorbent assay, respectively. RESULTS: Ninety-two severe OSAHS patients and thirty controls were enrolled in the study. All OSAHS patients had VD deficiency. The mean level of VD was at 7.9 ng/ml among OSAHS group versus 16.8 ng/ml among control group. IL-17A levels were elevated (20.3 pg/ml) in OSAHS group compared to healthy group (10.05 pg/ml). VD levels were negatively correlated with nocturia severity (r = −0.26; P = 0.01) and positively correlated with mean O(2) saturation (r = 0.59; P = 0.02) and lowest O(2) saturation (r = 0.3; P = 0.03). IL-17 levels were positively correlated with nocturia severity (r = 0.24; P = 0.03) and negatively correlated with mean O(2) saturation (r = −0.42; P = 0.03). A significant negative association was observed between IL-7 and VD levels (r = −0.64, P = 0.2 10(−4)). The magnitude of this correlation was higher for important nocturia, lower MSaO(2), or higher BMI. CONCLUSIONS: VD deficiency in patients with severe OSAHS is common with a negative association between IL-17 and VD serum levels. Hypoxia could play an important role in this association. Further studies are needed to clarify this relationship.