METTL14 Regulates Adipose Tissue Macrophage Polarization via JAK2 / STAT3 Pathway to Attenuate Obstructive Sleep Apnea‐Related Systemic Inflammation

Obstructive sleep apnea (OSA) is a common sleep disorder in which repeated breathing interruptions during sleep trigger chronic low-oxygen states that drive widespread inflammation and metabolic problems, including insulin resistance and obesity. This study investigated whether a chemical tag on RNA — called m6A methylation — plays a role in that inflammatory process, specifically inside fat tissue. The researchers found that a protein called METTL14, which adds m6A tags to RNA, is abnormally low in OSA patients and in mice and cell models exposed to the oxygen dips characteristic of OSA. When METTL14 levels drop, immune cells called macrophages in fat tissue shift toward a pro-inflammatory state (called M1 polarization) and away from an anti-inflammatory state (M2). The study shows METTL14 normally keeps inflammation in check by tagging the RNA of a key signaling protein, JAK2, which marks that RNA for faster degradation — essentially turning down a major inflammatory switch called the JAK2/STAT3 pathway. Restoring METTL14 activity in lab experiments reversed M1 macrophage polarization and rebalanced the inflammatory response. The findings position METTL14 and m6A RNA methylation as potential therapeutic targets for the metabolic and inflammatory complications of OSA, which currently have limited disease-modifying treatments.

• Global m6A RNA methylation levels and the expression of multiple m6A regulators were altered in OSA patients, with METTL14 mRNA expression negatively correlated with systemic inflammation markers (specific correlation coefficients not reported in the abstract).
• Chronic intermittent hypoxia (CIH) in mice significantly increased macrophage infiltration into epididymal white adipose tissue (eWAT) and downregulated METTL14 at both mRNA and protein levels in eWAT; hypoxia-treated THP-1 macrophages showed the same METTL14 suppression in vitro.
• Overexpression of METTL14 in hypoxia-exposed THP-1 macrophages inhibited M1 polarization, restored the M1/M2 balance, and mechanistically promoted m6A-mediated decay of JAK2 mRNA, thereby suppressing JAK2/STAT3 pathway activation.

The study used a three-part design: (1) a clinical cross-sectional analysis measuring m6A regulator expression and systemic inflammation markers in OSA patients; (2) a mouse model combining high-fat diet feeding with chronic intermittent hypoxia (CIH) to recapitulate OSA-associated metabolic inflammation, with histological evaluation of eWAT; and (3) in vitro mechanistic assays using THP-1 human macrophages exposed to hypoxia, with METTL14 overexpression experiments to interrogate the JAK2/STAT3 axis. Specific sample sizes for the patient cohort and animal groups are not stated in the abstract. Follow-up duration for the mouse model is not specified.

The study does not report sample sizes or detailed patient characteristics, making it difficult to assess statistical power or generalizability of the clinical findings. All mechanistic work was conducted in a single macrophage cell line (THP-1), which may not fully recapitulate primary adipose tissue macrophage biology in humans. Causal directionality in the patient cohort is inferential — the cross-sectional design cannot confirm whether METTL14 loss precedes or follows systemic inflammation. The next critical experiments would include conditional adipose-macrophage-specific METTL14 knockout or knockin mouse models, validation in primary human adipose tissue macrophages from OSA patients, and assessment of whether METTL14 restoration ameliorates downstream metabolic outcomes (e.g., insulin sensitivity) in vivo.

This article extends the OSA pathophysiology literature represented in the corpus by adding an epigenetic-epitranscriptomic dimension to the systemic consequences of intermittent hypoxia, paralleling [§47] and [§43], which link OSA severity to neurological and glymphatic dysfunction through separate mechanistic routes — together painting OSA as a disorder with broad multi-organ molecular consequences. The JAK2/STAT3-mediated macrophage polarization mechanism described here resonates with [§95], which examines OSA's immunological overlap with difficult asthma, as both implicate dysregulated innate immune activation as a downstream consequence of OSA-related hypoxia. The intermittent hypoxia mouse model used in this study can be directly compared to [§110], which characterizes the ventilatory effects of intermittent hypoxia in healthy subjects, offering complementary insight into how the same CIH stimulus produces both physiological and molecular-inflammatory responses. By demonstrating that m6A methylation controls macrophage polarization in adipose tissue, the study also opens a conceptual bridge to [§57], which targets obesity-related inflammation through a different molecular route (calcium butyrate), suggesting that adipose immune remodeling in metabolic sleep disorders may be approachable from multiple therapeutic angles.

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  Both investigate molecular mechanisms driving OSA-related systemic pathology but in different organ systems (adipose immune-metabolic vs. glymphatic-neurological), making comparison useful for understanding the full scope of OSA's multi-system impact.
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• Obstructive Sleep Apnoea and Difficult Asthma (OSADA)
  Examines OSA-driven immune dysregulation in the context of airway inflammation and difficult asthma, providing a clinically relevant parallel to this study's adipose-tissue macrophage polarization findings and raising questions about shared vs. distinct inflammatory pathways.
• Association between obstructive sleep apnea severity and glymphatic-related DTI-ALPS alterations in newly diagnosed, Drug-Naïve Alzheimer's disease
  Investigates OSA severity associations with neurodegeneration markers, offering a contrasting organ-system perspective that, alongside this adipose-inflammation study, supports the view that OSA severity is a transdiagnostic driver of diverse pathological processes.
• Neurocognitive and Health Impact of Sleep Apnea in Elderly Veterans With Comorbid COPD
  Reports neurocognitive and systemic health consequences of OSA in an elderly comorbid population, providing a clinically grounded outcome context for the mechanistic inflammation findings reported in this molecular study.