The Impact of Paternal Cytokine Administration on Sperm Small Rnas and Offspring Physiology and Behaviour in Mice

Background Paternal pre-conceptual exposure to parasitic, bacterial, and viral infections are all known to impact offspring phenotype via sperm epigenetic changes. Even in the absence of infection, paternal immune activation (PIA) can alter offspring behaviour and physiology through changes to sperm small RNAs. While this implicates the immune response, the specific component responsible for the phenomenon remains unknown. Aims & Objectives Cytokines offer a potential mechanism as they are a shared factor across different types of immune activation. As such, we investigated whether key pro-inflammatory cytokines elevated during PIA could recapitulate changes to offspring phenotype. Method C57BL/6J mice were injected with either TNF-α (250ug/kg) or IL-1β (50ug/kg); or saline at 8-weeks old. Following one spermatogenesis cycle (4-weeks), F0 male mice (fathers) were mated with age matched naïve female mice to produce F1 mice (offspring). F1 mice underwent a series of behavioural tests to assess anxiety-like, depression-like, and cognitive behavioural changes. Paternal sperm was collected following breeding and later extracted, sequenced and analysed to identify differentially expressed small RNAs. Results Offspring from cytokine treated fathers showed increased anxiety-like behaviour in the elevated plus maze and lost significantly more bodyweight following a 24-hour fast during the novelty suppressed feeding test. Despite no difference in whole brain weight, hypothalamus weights for cytokine offspring were both significantly less than controls. The analysis on paternal sperm is underway with results expected shortly. Discussion & Conclusions Together, these results suggest that paternal cytokine treatment is sufficient in altering offspring phenotype in a manner which partially recapitulates PIA models. In particular, cytokines play a role in increasing offspring anxiety-like behaviour. These findings contribute to a growing body of literature which suggests that environmental exposure, particularly of an inflammatory nature, may increase risk of mental health conditions in offspring.