According to a new study, men with a high-risk form of the cervical cancer-causing virus (HPV) had higher amounts of dead sperm, which may negatively impact their fertility.
Human papillomavirus (HPV), a sexually transmitted infection, includes high-risk and low-risk viruses. While the former carries a high risk of developing a malignant disease, the latter largely causes benign warts or marks, researchers explained in the study published in the journal Frontiers in Cellular and Infection Microbiology.
Argentine researchers, including those from the National University of Cordoba, studied the semen quality of 205 adult men.
Nearly a fifth of them, 39, tested positive for HPV — 20 had a high-risk form of the virus, seven had a low-risk form and 12 were the ones the team couldn't identify as high risk or low risk. The 39 HPV-positive men were compared with 43 HPV-negative men.
Although there was no difference in the quality of the semen between the men in these groups, looking more closely the researchers found that samples taken from the high-risk men infected with the virus had significantly lower numbers of immune cells, cells known to help fight infection – CD45 white blood cells.
Senior author Virginia Rivero explained that the low numbers of immune cells seen in these samples were a result of HPV's known ability to evade the immune response.
This would reduce the number of white blood cells that go to the site of HPV infection, reducing their ability to clear the infection, said Rivero, a professor at the National University of Cordoba.
The researchers also found evidence that sperm from men infected with a high-risk version of HPV may be more frequently damaged due to oxidative stress, which could be assessed by higher production of reactive oxygen species (ROS) in these men.
While low levels of ROS result in normal sperm function, high levels can lead to rupture of the outer covering of cells, breaks in genetic material, and cell death.
Consistent with this, the researchers found higher numbers of dead sperm cells in HPV-positive men with high-risk virus.
The authors wrote, “…a higher frequency of ROS dead sperm was observed in HR-HPV infected individuals compared to individuals infected with the LR-HPV genotype.”
“We conclude that increased sperm mortality was due to oxidative stress and a weakened local immune response in the urogenital tract in men infected with high-risk HPV, but not in men infected with low-risk HPV,” Rivero said.
Rivero said the results suggest that men infected with the high-risk form of the virus may have impaired fertility.
The authors reported that high-risk forms of HPV can be found in nearly all cervical cancers in women, and also in anal, genital, and mouth and throat cancers in both men and women.
He said the low-risk form of HPV can typically be detected in abnormal but benign cervical cells in women and in moles on the surface of the larynx (voice box) and genitals in both men and women, but it does not cause cancer.