Exposure of Men to PTSD-Promoting Trauma Elevates Levels of Sperm miRNAs with Anxiety and Depression-Inducing Activities

Abstract

Chronically stressing male rodents can induce stress-specific epigenetic changes in sperm that contribute to altered offspring phenotypes. Whether similar phenomena occur in men is unclear. This study addresses this knowledge gap by analyzing sperm microRNAs (miRNAs) from 51 men exposed to various levels of adult trauma including crime, disaster, and physical or sexual violence, quantified by the Trauma History Questionnaire (THQ), a measure of risk for Post-Traumatic Stress Disorder (PTSD). Four sperm miRNAs, miR-532-3p, 491-5p, 375-3p and 361-3p correlated positively with mens THQ scores, showing 4X to 130X over expression in sperm from the most highly traumatized men. These changes were independent of mens adverse childhood experiences (ACEs), which we previously linked to decreased miR-34/449 in their sperm; and sperm miR-34/449 levels were not associated with THQ scores. Injecting these 4 miRNAs into fertilized mouse oocytes at levels comparable to those found in men reporting high THQ scores yielded offspring with elevated anxiety-and depression-like phenotypes. This finding differs from the stress related phenotypes we observed in offspring of mice fertilized by sperm with reduced levels of miR-34/449. Consistent with only a small subset of men with high THQ scores developing PTSD, we observed no statistically significant increase in overall anxiety or depression among this highly traumatized group, however there were indications of increased sleeplessness, appetite and concentration difficulties and negative self-concept among this group. Nevertheless, almost all men reporting high THQ scores had elevated levels of all 4 of these miRNAs in their sperm, suggesting these trauma-induced epigenetic changes may raise mental health risks in the offspring of men with only subtle mental health problems. Since [~]20 % of men report either THQ or ACE scores in the ranges linked here and in our earlier study to changes in sperm miRNAs that in mice lead to elevated levels of stress-related behaviors, a large human population with an elevated risk of transmitting stress-related traits to their offspring likely exists.