The effect of bacteriospermia and leukocytospermia on conventional and nonconventional semen parameters in healthy young normozoospermic males

• Bacteriospermia and leukocytospermia compromise the sperm quality in healthy young normozoospermic males.
• Mitochondria-dependent apoptosis and necrosis coexist in ejaculated human spermatozoa during semen bacterial infection in situ.
• Oxidative stress is a major cause of sperm damage in leukocytospermic healthy young males.

Bacterial semen inflammation/infection is an important diagnostic and therapeutic problem in contemporary andrology. The molecular mechanism by which inflammatory mediators compromise the fertilizing potential of germ cells is complex and multifactorial, and it remains unclear. To improve the understanding of the pathophysiology of human subfertility/infertility caused or complicated by reproductive tract inflammation/infection, we simultaneously evaluated a set of conventional (standard semen analysis) and nonconventional sperm parameters, including subcellular changes in sperm membranes (phospholipid scrambling, peroxidative damage, and phosphatidylserine (PS) externalization), mitochondria (mitochondrial transmembrane potential, ΔYm, and oxidoreductive capability), and DNA fragmentation in healthy young normozoospermic males with asymptomatic bacteriospermia and leukocytospermia. Both bacteriospermia and leukocytospermia had a deleterious effect on standard sperm parameters, including sperm concentration, motility and morphology. Bacteriospermia was associated with a simultaneous decrease in mitochondrial transmembrane potential and an increase in PS externalization, and with DNA fragmentation in both live and dead sperm. The highest MDA concentrations in sperm lysates were observed in the presence of leukocytes. This study demonstrates for the first time that bacteriospermia and leukocytospermia compromise sperm quality in healthy young normozoospermic males. Bacteria mainly participate in intrinsic mitochondria-dependent apoptotic cell death mechanisms. Oxidative stress plays a relevant role in decreasing routine sperm parameters during leukocytospermia. The value of these observations may be significant and may support the development of a new diagnostic platform (biomarkers) for infertile males with infections in the reproductive tract.