Male infertility – identifying a key to sperm survival

A new discovery about a major cause of male infertility could have significant impacts for millions of men worldwide.

The causes of infertility are much less understood in men than in women, despite the fact that currently in Australia about half of all cases of infertility have their source in the male reproductive system.

Now a team of researchers at Hudson Institute, led by Dr Rukmali Wijayarathna and Professor Mark Hedger, in collaboration with researchers at Monash University, Justus-Liebig University in Germany, and Oxford University and the University of Virginia, USA, has identified a key factor that protects a man’s sperm from being destroyed by his own immune system.

Sperm are produced in the testes, but they only reach maturity in the epididymis, and this is the focus of Dr Wijayarathna’s research.

“The epididymis has a unique immune environment that protects against infections but also prevents sperm being recognised as ‘foreign’ by the body,” Dr Wijayarathna said.

Male infertility discovery

“But we’ve discovered that when there is a blockage in the tubes between the testis and the epididymis, that environment changes, because Activins, a key factor that maintains the immune environment in the epididymis, are reduced. This potentially makes it a hostile environment for sperm survival and maturation.”

That type of blockage is often associated with reproductive and urinary (genitourinary) tract infections which affect almost all men at some stage in their lives, or accidental trauma.

This is an important discovery with potential benefits to the study of male infertility and even, potentially, contraception.

“Our study indicates that clinical conditions causing obstruction of testicular outflow may impact ‘immune tolerance’ or the ability of the epididymis to protect testicular sperm from being recognized as “foreign” by the immune system, thus reducing fertility,” Dr Wijayarathna said.

Next steps

“Our research will contribute to understanding the unique immune system in the male reproductive tract,” she said.

“This is the first step towards identifying causes and treatments for male infertility of inflammatory and infectious origins, which contributes to 15% of male infertility cases.”