Update on the aetiopathogenesis of obstructive sleep apnea: Role of inflammatory and immune mediated mechanisms

Table 1 Multifactorial causes of obstructive sleep apnea

Anatomic factors	Nonanatomic factors	Functional factors	Miscellaneous
Micrognathia, retrognathia; facial elongation; mandibular hypoplasia; adenoid and tonsillar hypertrophy; inferior displacement of the hyoid	Central fat distribution; obesity, BMI > 30 kg/m2; advanced age; male gender; supine sleeping position; pregnancy	Impaired pharyngeal dilator muscle function; low respiratory arousal threshold; unstable control of breathing	Alcohol use; smoking; sedatives and hypnotics use; hereditary

BMI: Body mass index.

Table 2 Immune cell and obstructive sleep apnea

Immune cells	Effect
Monocyte	There were significant alterations in the distribution of monocyte subsets in response to OSAS, characterized by an increase in intermediate and non-classical monocytes and a decrease in classical monocytes[12]
Neutrophils	OSA is independently associated with increased neutrophil counts and inflammation[38]
B-lymphocytes	When B cells are depleted or dysregulated, it can lead to an imbalance in the immune system, potentially resulting in increased inflammation as seen in OSA[38]
T-lymphocytes	There is an imbalance of CD4+ and CD8+ cells in individuals with OSAS, with a high proportion of CD8+ cells and a low proportion of CD4+ cells. These changes are dependent on the AHI[38]
Neutrophil lymphocyte ratio	NLR increases and is directly correlates with AHI[28]

AHI: Apnea–hypopnea index; OSA: Obstructive sleep apnea; NLR: Neutrophil lymphocyte ratio.

Table 3 Inflammatory mediators and obstructive sleep apnea

Inflammatory Mediators	Effect
TNF-α	Elevated levels of inflammatory
IL-6, IL-8, CRP, ESR	Markers correlate with severity of OSA[22,25,38]
Adipokines
Key adipokines studied include: Leptin, Chemerin, Resistin, Adiponectin, Omentin-1	OSA is associated with elevated levels of leptin, chemerin, and resistin, and decreased levels of adiponectin and omentin-1. These changes may contribute to metabolic dysfunction, inflammation, and cardiovascular risks[38]

TNF-α: Tumour necrosis factor alpha; IL: Interleukin; CRP: C-reactive protein; ESR: Erythrocyte sedimentation rate; OSA: Obstructive sleep apnea.