Seminal oxidative stress (OS) is highly correlated with sperm DNA damage in men with idiopathic and male-factor infertility

Objective: Seminal OS is due to an imbalance between reactive oxygen species (ROS) and total antioxidant capacity (TAC) in semen and is involved in many aspects of male infertility. Our group has recently introduced the composite ROS-TAC score as an accurate measure of seminal OS. In this study, we examined the correlation of seminal OS with sperm DNA damage and standard sperm parameters in infertile men with idiopathic and male-factor infertility.

Design: Prospective study.

Materials/Methods: The study included 92 infertile men, with a normal female partner, and 16 fertile donors as a control. All men had a genital exam by a male infertility specialist (AJT). Standard semen analysis (SA) was performed as per the World Health Organization guidelines (WHO, 1999). Sperm DNA damage was assessed by sperm chromatin structure

assay and results expressed as DNA fragmentation index (DFI). Levels of seminal ROS and TAC were determined using a chemiluminescence assay.

The composite ROS-TAC score was calculated as a measure of OS. Low score indicates high OS and vice versa.

Results: Patients were classified as idiopathic (normal SA and genital exam; n = 23) (group 1) and male-factor infertility (abnormal SA with/ without abnormal genital exam; n = 69) (group 2). Comparisons between groups are shown in the table. The ROS-TAC scores were correlated positively with sperm concentration (r = 0.37; P = 0.001), motility (r 0.39; P = 0.0007), and normal sperm forms (r = 0.44; P = 0.0001), and negatively with seminal leukocyte concentrations (r = -0.57; P <0.0001) and DFI (r= -0.27; P = 0.009).

Variable                           Fertile Donors        Group 1         Group 2           A               B                C
                                        (n = 16)                (n = 23)      (n = 69)
Concentration                    71 (36, 120)       58 (47, 74)      23 (13, 48)   0.68          0.0008        0.0001

(1 × 10⁶ /mL)
Motility (%)                       62 (54, 70)       65 (58, 77)     42 (30, 52)      0.39          0.0002        0.0001
Normal Sperm                    40 (33, 45)      34 (32, 37)      18 (12, 25)      0.22          0.0001       0.0001
Forms (%)

Seminal Leukocytes            0.0 (0, 0)         0.0 (9.0, 0.4)     0.4 (0.1, 2)     0.12         0.01          0.17
(×10⁶/mL)

ROS-TAC Score                  53 (50, 58)       47 (45, 51)       43 (32, 49)     0.009   0.0001          0.007

DFI (%)                           15 (11, 21)        23 (15, 32)        28 (18, 41)     0.02     0.0001            0.2

Values are median (25% & 75%); A = p-values between fertile donors and group 1;B= p-values between fertile donors and group 2; C = p-values between group 1 and 2. Wilcoxon rank-sum test was used for the analysis; P < 0.05 was significant.

Conclusions: Our study indicates significant increases in seminal OS and sperm DNA damage in men with idiopathic and male-factor infertility. Seminal OS was significantly correlated with sperm DNA damage and
standard sperm parameters. The high levels of seminal OS observed in these infertile patients may be responsible for poor sperm quality and increased DNA damage. Assessment of seminal OS and sperm DNA damage may beuseful diagnostic and prognostic tools for future use in infertility clinics.