Higher levels of inflammatory markers are found in patients with obstructive sleep apnea (OSA) vs healthy patients, suggesting adipocytokines contribute to OSA pathology; this, in turn, implies that management of OSA symptoms is possible with therapeutic modification of adipocytokine levels. These are among meta-analysis findings published in Respiratory Medicine.
Adipocytokines mediate inflammatory responses in OSA, and previous research has suggested that OSA may be related to a change in serum levels of adipocytokines. Investigators therefore sought to evaluate the relationship between OSA and circulating levels of adipocytokines in adults and children.
The researchers conducted a systematic review and meta-analysis of articles from Scopus and Medline/PubMed databases from inception to July 2022 of studies reporting on OSA-related changes in serum levels of adipocytokines. The reviewers found 83 studies that included 9292 participants. Among these studies, 67 involved adults (n=7681) and 16 involved children (n=1611). All studies of resistin, vaspin, visfatin, and chemerin involved adults and all studies of interleukin (IL)-23 involved children. There were 21 studies that exclusively recruited men.
Inclusion criteria included peer-reviewed case-control studies that reported mean and standard deviations or sufficient data to calculate mean and standard deviations for at least 1 of the adipocytokines (including IL-1β, IL-2, IL-4, IL-5, IL-8, IL-10, IL-12, IL-17, IL-18, IL-23, interferon [IFN]-gamma, resistin, vaspin, visfatin, chemerin, and apelin) between OSA cases and control individuals.
The meta-analysis revealed a significant reduction in adipocytokine serum levels in IL-10 in patients with OSA vs control groups. Higher levels of IL1β, IL-4, IL-8, IL-17, and IFN-gamma were found in patients with OSA vs control groups (P <.05). Investigators found an association between adult patients with OSA and greater serum levels of IL-1β, IL-8, IL-17, IL-18, vaspin, visfatin, and chemerin. Serum levels of IL-5 and IL-10 were significantly lower in adults with OSA vs healthy adults (P <.05). The researchers found no significant differences in serum levels of IL-2, IL-5, IL-12, IL-18 and apelin between adults with and without OSA.
Among children, significantly higher serum levels were found in children with OSA vs healthy children for IL-4, IL-8, IL-12, IL-17, IL-23, and IFN-gamma (P <.05). Egger’s test revealed significant publication bias for studies on IL-1β, IL-10, and IL-17.
Heterogeneity was significant across studies. Pooled analysis of studies on adults showed no significant differences in serum levels of IL-4 in patients with OSA vs healthy adults. Subgroup meta-analysis in adult patients according to severity of OSA, sex, and obesity showed a nonsignificant difference in IL-4 between patients with OSA and healthy adults. Decreased IL-10 was seen in all subgroups except in studies on men and in participants with obesity.
Review and meta-analyses limitations include the inherent limitations of a review design, publication bias, inclusion of only studies published in English for analysis, lack of generalizability, and significant heterogeneity.
“The levels of inflammatory markers were found to be higher in OSA patients compared with control individuals, suggesting that adipocytokines may contribute to the pathology of OSA,” investigators concluded. They wrote “Our data offered direct evidence that IL-8 is elevated in OSA adults and children and that magnitude of this increase is associated significantly with the severity of OSA, and obesity status (suggesting the role of BMI as confounder in airways inflammation).”
Janmohammadi P, Raeisi T, Zarei M, et al. Adipocytokines in obstructive sleep apnea: A systematic review and meta-analysis. Respir Med. Published online January 19, 2023. doi:10.1016/j.rmed.2023.107122