Heat shock protein and heat shock factor expression in sperm: relation to oligozoospermia and varicocele

Varicocele may be associated with normozoospermia or oligozoospermia. Much controversy still exists regarding the diagnosis, management and pathophysiology of spermatogenesis alterations associated with varicocele. The increased temperature induced by varicocele and stress in general may activate heat shock proteins and heat shock factors with a protective function in cells. We analyzed the expression of 5 heat shock proteins and heat shock factors in the sperm of men with normozoospermia and oligozoospermia with or without varicocele.

We performed a prospective study between June 2008 and February 2009 at an academic clinic in 117 consecutive patients with varicocele and 68 controls without varicocele. Four groups were based on the presence/absence of varicocele and normozoospermia/oligozoospermia. Subjects were studied by history, physical examination, scrotal Doppler ultrasound, semen analysis, reproductive hormone plasma levels and quantitative real-time polymerase chain reaction in RNA extracted from ejaculated sperm to analyze HSP90, HSPA4, HSF1, HSF2 and HSFY expression.

Increased HSPA4, HSF1 and HSF2 were observed in the sperm of men with varicocele and in those with oligozoospermia. Levels were maximum when the 2 conditions were present. Increased HSP90 was observed in oligozoospermia cases independent of varicocele. HSFY was up-regulated only in patients with varicocele, especially those with normozoospermia.

To our knowledge we describe for the first time the expression of different heat shock proteins and heat shock factors in ejaculated sperm. While some of these proteins are up-regulated in men with oligozoospermia and varicocele, HSFY is up-regulated only in the presence of varicocele and especially in men with normozoospermia. This suggests that it may be a molecular marker of an adequate or inadequate response to the damaging effect of varicocele on spermatogenesis.