Varicocele is one of causes of the declined sperm quality and low sperm production, which can lead to
infertility in males. There are several experimental and epidemiological findings which support the idea that inflammatory mechanisms play an essential role in
varicocele pathogenesis. Besides, in this pathological state, interleukin-37 (IL-37) as an anti-inflammatory
cytokine is able to bind interleukin-18-binding
protein (IL-18BP), and subsequently binds
IL-18 receptor β, inhibiting the pro-inflammatory activity of
IL-18. To explore the interaction between IL-37 and
IL-18 in
infertility, we measured the amount of these
cytokines in the seminal fluid of infertile men affected by
varicocele. The seminal plasma levels of IL-37 and
IL-18 were measured in 75 infertile men with
varicocele and 75 healthy fertile controls (age range, 30-48 years) using
enzyme-linked
immunosorbent assay. The seminal levels of IL-37 and
IL-18 were significantly increased in infertile men with
varicocele when compared to fertile controls (p < .0001). Because of the essential role(s) of
cytokines in inflammatory response of cell systems, it could be possible that sperm motility is reduced following increased
IL-18, activated neutrophils and
reactive oxygen species in semen of infertile patients with
varicocele. Moreover, the results of this study indicated that interaction between IL-37 and IL-18Rβ can lead to reduced inflammatory responses. It seems that IL-37 might be a potential
biomarker and therapeutic target for
male infertility.