Chronic Low-grade Systemic Inflammation and Subfertility

Objective:
Systemic inflammation has been suspected as a possible factor of infertility in recent decades. Correlative studies describe increased inflammatory markers in fertility clinic patients. Specifically, obesity and oral cavity disease are the most common pathologies that involve basal inflammation and are found to be correlated to subfertility. Here we have examined the effect of these pathologies on fertility in mouse model, focusing on epigenetic aspects in oocytes. Recently, the epigenome was discovered as central niche in oocyte function, and thus, we examined oocytes epigenetic function under chronic systemic conditions.

Results:
We used high fat diet and periodontitis as models for chronic low-grade systemic inflammation conditions. After treatment, oocytes were collected from mice and stained to assess their epigenetic function. H3K9me2 presented a decrease in treated animals oocytes in both models, indicating impaired chromatin modulation. Moreover, L1-ORF1- a marker for retrotransposon activity, presented elevation after treatment, displaying damage that occurs due to chromatin deformations.

Discussion:
Though widely described, the connection between systemic inflammation and subfertility is unknown. Our results add a biological link to this context: The epigenetic alterations that occur under stress conditions impair oocytes transcription and DNA integrity.

Impact Statement:
This work presents the direct effects of widely common physiological conditions on oocytes chromatin organization and function. Applying this connection to the clinic, we might offer better prevention and care of subfertility cases.