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Nr1d1 Mediates Microglial Inflammatory Activation Induced by Intermittent Hypoxia: A Transcriptomic and Machine
Zhuoran Sun1,2, Tengqun Shen1, Mengfan Li1
1Department of Neurology, Weihai Municipal Hospital, Shandong University, Jinan, Shandong, China.
Abstract:
Obstructive sleep apnea is characterized by recurrent intermittent hypoxia (IH), which contributes to neuroinflammation and neurological dysfunction. Microglia are pivotal regulators of inflammatory responses in the central nervous system, but the molecular mechanisms underlying IH-induced microglial activation remain unclear. This study aimed to identify key genes mediating this phenomenon and to elucidate their functional significance. An IH model was established in BV2 cells, with inflammation assessed via western blot for cyclooxygenase-2 (COX2) /inducible nitric oxide synthase (iNOS) and ELISA for Interleukin-6 (IL-6) /Tumour necrosis factor-alpha (TNF-α). RNA sequencing was performed to profile transcriptional changes induced by IH. Differential expression analysis, functional enrichment analysis, protein interaction network analysis, transcription factor prediction, and machine learning-based screening were integrated to identify candidate key genes. Pharmacological modulation of Nr1d1 was then performed to evaluate its role in IH-induced inflammation. IH significantly increased COX2, iNOS, IL-6 and TNF-α levels in BV2 cells. Transcriptomics showed distinct profiles between control and IH groups. Enrichment analyses linked IH-related genes to immune regulation, stress responses, and metabolic pathways. Network analysis highlighted a circadian gene cluster as a prominent component of the IH-responsive transcriptional network. Integrated network and machine learning analyses further identified Nr1d1 as a key candidate. Pharmacological experiments showed that inhibition of Nr1d1 attenuated IH-induced inflammatory responses. IH induces pronounced inflammatory activation and transcriptional reprogramming in BV2 cells. Nr1d1 may represent a circadian-associated candidate regulator involved in IH-induced microglial inflammatory activation.
Insights
Obstructive sleep apnea causes intermittent hypoxia, leading to brain inflammation. This study identifies Nr1d1 as a key gene involved in microglial activation during this process.
Area of Science:
- Neuroscience
- Immunology
- Genetics
Background:
- Obstructive sleep apnea (OSA) involves recurrent intermittent hypoxia (IH), a known contributor to neuroinflammation and neurological deficits.
- Microglia, the brain's immune cells, play a crucial role in inflammatory responses, but the specific molecular pathways activated by IH are not fully understood.
Purpose of the Study:
- To identify key genes mediating microglial activation under IH conditions.
- To investigate the functional significance of these genes in IH-induced neuroinflammation.
Main Methods:
- An in vitro model of IH was established using BV2 microglial cells.
- Inflammation markers (COX2, iNOS, IL-6, TNF-α) were measured using Western blot and ELISA.
- RNA sequencing was employed to analyze transcriptional changes.
- Bioinformatic analyses including differential expression, enrichment, network, and machine learning were performed.
- Pharmacological inhibition of candidate gene Nr1d1 was used to assess its role.
Main Results:
- IH significantly elevated inflammatory markers (COX2, iNOS, IL-6, TNF-α) in BV2 cells.
- Transcriptomic profiling revealed distinct gene expression patterns between control and IH conditions.
- Network analysis identified a cluster of circadian genes, including Nr1d1, as central to IH-responsive transcriptional changes.
- Inhibition of Nr1d1 demonstrably reduced IH-induced inflammatory responses in microglial cells.
Conclusions:
- Intermittent hypoxia triggers significant inflammatory activation and transcriptional reprogramming in microglial cells.
- Nr1d1 emerges as a potential key regulator, linking circadian rhythms to microglial inflammatory activation in the context of IH.
- Targeting Nr1d1 may offer a therapeutic strategy for mitigating neuroinflammation associated with obstructive sleep apnea.
