Suresh C. Sikka

Relative impact of oxidative stress on male reproductive function

Impairment of normal spermatogenesis and sperm function are the most common causes of male factor infertility. Abnormal sperm function is difficult to evaluate and treat. There is a lack of understanding of the factors contributing to normal and abnormal sperm function leading to infertility. Many recent studies indicate that oxygen-derived free radicals induce damage to spermatozoa. The excessive generation of these reactive oxygen species (superoxide, hydroxyl, nitric oxide, peroxide, peroxynitrile) by immature and abnormal spermatozoa and by contaminating leukocytes associated with genitourinary tract inflammation have been identified with idiopathic male infertility. Mammalian spermatozoa membranes are rich in polyunsaturated fatty acids. This makes them very susceptible to oxygen-induced damage, which is mediated by lipid peroxidation. In a normal situation, the antioxidant mechanisms present in the reproductive tissues and their secretions are likely to quench these reactive oxygen species (ROS) and protect against oxidative damage to gonadal cells and mature spermatozoa. During chronic disease states, aging, toxin exposure, or genitourinary infection/inflammation, these cellular antioxidant mechanisms downplay and create a situation called oxidative stress. Thus, a balance between ROS generation and antioxidant capacity plays a critical role in the pathophysiology of disease state. Recent efforts towards the development of new reliable assays to evaluate this oxidative stress status have resulted in the establishment of ROS-TAC score. Such assessment of oxidative stress status (OSS) may help in designing newer modes of male factor infertility treatment by suitable antioxidants.

Oxidative stress and role of antioxidants in normal and abnormal sperm function.

Defective sperm function is the most common cause of infertility, and until recently, it was difficult to evaluate and treat. Part of this difficulty was due to our incomplete understanding of the factors contributing to normal and abnormal sperm function leading to male infertility. Mammalian spermatozoa membranes are rich in high unsaturated fatty acids and are sensitive to oxygen induced damage mediated by lipid peroxidation. Limited endogenous mechanisms exist to reverse these damages. The excessive generation of reactive oxygen species (ROS) by abnormal spermatozoa and by contaminating leukocytes (leukocytospermia) has been identified as one of the few defined etiologies for male infertility. In a normal situation, the seminal plasma contains antioxidant mechanisms which are likely to quench these ROS and protect against any likely damage to spermatozoa. However, during genitourinary infection/inflammation these antioxidant mechanisms may downplay and create a situation called oxidative stress. In addition, aging and environmental toxicants are also likely to further induce this oxidative stress. Assessment of such oxidative stress status (OSS) may help in the medical treatment of this male factor infertility by suitable antioxidants.

The role of free radicals and antioxidants in reproduction.

Purpose of review This review summarizes the role of free radicals and oxidative stress in the pathophysiology of human reproduction. Recent findings An extensive review of the literature on the role of oxidative stress in influencing assisted reproduction and its outcome is described in this article. Free radicals or reactive oxygen species mediate their action through many of the proinflammatory cytokines and this mechanism has been proposed as a common underlying factor for endometriosis, ovarian cancer, polycystic ovary disease, and various other pathologies affecting the female reproductive process, as highlighted in this review. Oxidative stress, sperm DNA damage, and apoptosis have been implicated in male infertility. Elevated reactive oxygen species levels correlate with the poor fertility outcomes seen in the assisted reproductive technology setting. Summary Oxidative stress has been implicated in male and female infertility, including fetal dysmorphogenesis, abortions, and intrauterine growth restriction. Accurate evaluation of seminal oxidative stress by standardized assays may help in the diagnosis and management of male infertility. There is evidence in the literature on the beneficial effects of oral antioxidant supplementation in male infertility. Current ongoing trials will provide answers on the safety and effectiveness of antioxidants in improving maternal and fetal outcomes. Further studies need to be conducted to determine if antioxidant supplementation will prevent fetal developmental defects in high-risk pregnancy with diabetes.

Evaluation of nuclear DNA damage in spermatozoa from infertile men with varicocele

OBJECTIVE To examine levels of sperm DNA damage and oxidative stress (OS) in infertile men with varicocele. DESIGN Prospective controlled study. SETTING Male infertility clinic, Glickman Urological Institute, Cleveland Clinic Foundation, Cleveland, Ohio. PATIENT(S) Thirty-one infertility patients and 16 fertile controls. INTERVENTION(S) Sperm DNA fragmentation index (DFI), levels of seminal reactive oxygen species (ROS), and total antioxidant capacity (TAC) were assessed using the sperm chromatin structure assay, chemiluminescence assay, and enhanced chemiluminescence assay, respectively. ROS-TAC score was calculated as a measure of OS. MAIN OUTCOME MEASURE(S) Median (interquartile range) DFI and ROS-TAC scores. RESULT(S) Sixteen of the 31 patients had left varicocele [grade I (n = 3), grade II (n = 10), and grade III(n = 3)], and the remaining 15 had normal genital examination. Patients with varicoceles had significantly higher percent DFI than controls (25%, range: 20%-35%; vs. 15%, range: 10%-22%). Patients with varicoceles had significantly lower ROS-TAC scores (21, range: 9.5-31) than the infertile patients with normal genital examination (34, range: 28-42) or the controls (40.3, range: 38-44). CONCLUSION(S) Infertile men with varicoceles showed significantly increased spermatozoal DNA damage that appears to be related to high levels of OS in semen.

Characterization of reactive oxygen species induced effects on human spermatozoa movement and energy metabolism.

Reactive oxygen species (ROS) inhibit sperm movement and have been implicated in male infertility. In this study, we determined the effects of specific ROS produced by activated leukocytes on human spermatozoa and investigated their metabolic site of action. We used chemiluminescence and electron paramagnetic resonance (EPR) to characterize the ROS generated by both blood and seminal leukocytes. We also determined the effects of these ROS on sperm energy metabolism using biochemical analyses and flow cytometry. Both blood and seminal leukocytes produced the same characteristic ROS which were determined to be hydrogen peroxide (H2O2) and superoxide radicals (O2*-). EPR using the spin trapping technique indicated that superoxide radical-dependent hydroxyl radicals (HO.) were also generated. ROS generated by PMA-stimulated blood leukocytes (2-5 x 10(6)/ml) caused inhibition of sperm movement in 2 h (p < .01). Using the hypoxanthine/ xanthine oxidase (0.5 U/ml) system to generate ROS, we determined that spermatozoa ATP levels, after ROS treatment, were reduced approximately eight-fold in 30 min (0.10 x 10(10) moles/10(6) sperm cells) compared to control (0.84 X 10(-10) moles/10(6) sperm cells) (p < .01). Sperm ATP reduction paralleled the inhibition of sperm forward progression. Neither superoxide dismutase (100 U/ml) nor dimethyl sulfoxide (100 mM) reversed these effects; however, protection was observed with catalase (4 X 10(3) U/ml). Flow cytometric analyses of sperm treated with various doses of H2O2 (0.3 mM-20.0 mM) showed a dose-dependent decrease in sperm mitochondrial membrane potential (MMP); however, at low concentrations of H2O2, sperm MMP was not significantly inhibited. Also, sperm MMP uncoupling with CCClP had no effect on either sperm ATP levels or forward progression. These results indicate that H2O2 is the toxic ROS produced by activated leukocytes causing the inhibition of both sperm movement and ATP production. O2*- and HO. do not play a significant role in these processes. Low concentrations of H2O2 causing complete inhibition of sperm movement and ATP levels inhibit sperm energy metabolism at a site independent of mitochondrial oxidative phosphorylation.

Effects of Smoking on Testicular Function, Semen Quality and Sperm Fertilizing Capacity

PURPOSE The effects of smoking on testicular function and sperm physiology were studied. MATERIALS AND METHODS Left testicular biopsy was performed in 49 smokers and 28 nonsmokers. Seminal specimens from these men were analyzed. RESULTS Testosterone levels in the left testicular vein, left testicular androgen-binding protein secretion rate (in vitro), sperm motility, percentage of morphologically normal spermatozoa, sperm morphometric parameters and outcome of sperm function tests were significantly lower (p < 0.05) in smokers than in nonsmokers. CONCLUSIONS Morphological sperm abnormalities due to secretory dysfunction of the Leydig and Sertoli cells may be the cause of impaired sperm fertilizing capacity in smokers.

Single-Blind, Multicenter, Placebo Controlled, Parallel Study to Assess the Safety and Efficacy of Intralesional Interferon α-2b for Minimally Invasive Treatment for Peyronie’s Disease

PURPOSE We investigated the efficacy and safety of intralesional interferon alpha-2b for the treatment of Peyronies disease. MATERIALS AND METHODS A total of 117 consecutive patients with a mean age of 55.1 years who had Peyronies disease were enrolled in a single-blind, multicenter, placebo controlled, parallel study to determine the efficacy and safety of intralesional interferon alpha-2b therapy (Schering, Kenilworth, New Jersey), including 62 who received placebo and 55 who received interferon alpha-2b. Saline (10 ml) in controls and interferon alpha-2b (5 x 10(6) U) were administered biweekly for 12 weeks. Each patient was evaluated for penile curvature, plaque size and density, penile pain, erectile function and penile hemodynamics before and after study completion. Improvement in these parameters was statistically compared between the groups. RESULTS A total of 53 patients in the control arm and 50 in the interferon alpha-2b arm completed the study. Improvement in penile curvature, plaque size and density, and pain resolution was significantly greater in patients treated with interferon alpha-2b vs placebo. The increase in mean International Index of Erectile Function scores was not significantly different between the groups. Penile blood flow improvement was observed in interferon alpha-2b treated patients but not in those who received placebo. The decrease in the number of penile vascular pathologies was significantly higher in interferon alpha-2b cases. Side effects, mostly flu-like symptoms, which were frequently noted in patients on interferon alpha-2b, were mild to moderate in degree and of short duration. CONCLUSIONS This single-blind, multicenter, placebo controlled, parallel study demonstrates that intralesional interferon alpha-2b at a dose of 5 x 10(6) units biweekly for 12 weeks is effective and safe as minimally invasive therapy for Peyronies disease.

Effect of sodium nitroprusside on sperm motility, viability, and lipid peroxidation

OBJECTIVE To analyze the effect of sodium nitroprusside, a nitric oxide releaser, on sperm motion and lipid peroxidation-induced membrane damage in cryopreserved human sperm. DESIGN Post-thaw, cryopreserved, human sperm samples were washed and divided into three aliquots. Each aliquot was incubated with either 0, 50, or 100 nM sodium nitroprusside. INTERVENTIONS Samples were analyzed for lipid peroxidation (measured by malonaldehyde-thiobarbituric acid reactivity) at 3 hours post-thaw. MAIN OUTCOME MEASURES Percent viability and motion parameters were assessed at 0, 10, and 30 minutes and 2, 3, 5, and 6 hours post-thaw. RESULTS All results represent a mean +/- SEM, n = 10. Lipid peroxidation in samples incubated with 50 nM sodium nitroprusside (15.1 +/- 2.1 nM malonaldehyde/10(8) sperm) or 100 nM sodium nitroprusside (13.2 +/- 2.1 nM malonaldehyde/10(8) sperm) was significantly lower than in controls (22.7 +/- 3.1 nM malonaldehyde/10(8) sperm). Percent viability was significantly reduced from 0 minutes (60.6% +/- 3.5%) to 6 hours post-thaw in controls (38.0% +/- 5.1%) but not in 50 nM (46.8% +/- 10.4%) or 100 nM (48.8% +/- 6.5%) sodium nitroprusside-treated samples. Compared with controls (18.3% +/- 3.4%), maintenance of percent motility at 3 hours post-thaw was significantly improved in 50 nM (24.5% +/- 2.9%) and in 100 nM (26.3% +/- 3.2%) sodium nitroprusside-treated samples. Straight line velocity maintenance was significantly improved in 50 nM (37.3 +/- 1.3) and in 100 nM (37.0 +/- 1) sodium nitroprusside-treated samples as compared with controls (30.5 +/- 1.7). Significant improvements in curvilinear velocity maintenance compared with controls (56.3 +/- 2.9) also were observed in 50 nM (65.9 +/- 2.1) and 100 nM (72.1 +/- 4.1) sodium nitroprusside-treated samples. Significant differences in the motion parameters of sodium nitroprusside-treated samples were maintained at 5 and 6 hours post-thaw in comparison to controls. CONCLUSION These results suggest that sodium nitroprusside is beneficial to the maintenance of post-thaw sperm motion and viability for up to 6 hours and that reduction of lipid peroxidative damage to sperm membranes may be the mechanism for these benefits.

Clinical relevance of oxidative stress and sperm chromatin damage in male infertility: an evidence based analysis

Oxidative stress (OS) in the reproductive tract is now a real entity and concern due to the potential harmful effects of high levels of reactive oxygen species (ROS) on sperm number, motility, quality, and function including damage to sperm nuclear DNA. Evaluation of OS related damage to non-functional sperm is highly relevant as intracytoplasmic sperm injection (ICSI) technique, an effective therapy for severe male factor infertility, bypasses the majority of reproductive tract deficiencies. Despite the controversial findings in the existing literature, there is now enough evidence to show that sperm DNA damage is detrimental to reproductive outcomes. In addition, spermatozoa of infertile men are suggested to carry more DNA damage than do the spermatozoa from fertile men. Besides impairment of fertility such damage is likely to increase the transmission of genetic diseases during the assisted reproductive procedures. Standardization of protocols to assess reactive oxygen species and DNA damage is very important in introducing these tests in such clinical practice. Thus evaluation of seminal ROS levels and extent of sperm DNA damage especially in an infertile male may help develop new therapeutic strategies and improve success of assisted reproductive techniques (ART).

Oxidative stress and interleukins in seminal plasma during leukocytospermia

OBJECTIVE To quantify the levels of reactive oxygen species, superoxide dismutase (SOD), and interleukins (IL) 2 and 8 in seminal plasma of infertile patients as well as to examine the possible relationship between oxidative stress and proinflammatory cytokines. DESIGN Semen collected from normal fertile donors, infertile men without symptoms of genitourinary (GU) inflammation, and infertile men with symptoms of infection-inflammation of the GU tract was evaluated for the levels of granulocyte elastase, reactive oxygen species, SOD, IL-2, and IL-8. Any correlation between the levels of reactive oxygen species and other parameters in these population was analyzed statistically. RESULTS Significantly high levels of granulocyte elastase (18.32 +/- 1.52 U/L), reactive oxygen species (6 x 10(5) cpm), IL-8 (3.7 +/- 0.10 microgram/L), and IL-2 (18.32 +/- 1.47 ng/L) were observed in semen of infertile patients with leukocytospermia compared with the other two groups. In leukocytospermic samples, the activity of SOD was significantly lower (624.89 +/- 41.16 NU/mL) compared with nonleukocytospermic samples (787.85 +/- 24.26 NU/mL) or fertile donors (816.29 +/- 50.16 NU/mL). A significant positive correlation was observed between the levels of reactive oxygen species and IL-8. CONCLUSIONS These findings suggest that increased oxidative stress observed during leukocytospermia may modulate the level of proinflammatory cytokines. The increased oxidative stress may be due to a defect in the reactive oxygen species scavenging system.