P. Cohen-Bacrie

ANTIOXIDANTS TO REDUCE SPERM DNA FRAGMENTATION: AN UNEXPECTED ADVERSE EFFECT

Reactive oxygen species (ROS) have a negative impact on sperm DNA, leading to the formation of oxidative products such as 8-oxo-7,8-dihydroxyguanosine. This compound causes fragmentation and, thus, has a mutagenic effect. Patient treatment with oral antioxidant vitamins is, therefore, standard practice for male infertility, in an attempt to decrease formation of ROS and improve fertility. In this study, the DNA fragmentation index and the degree of sperm decondensation were measured using the sperm chromatin structure assay before and after 90 days treatment with antioxidant vitamins associated with zinc and selenium. Antioxidant treatment led to a decrease in sperm DNA fragmentation (-19.1%, P < 0.0004), suggesting that at least part of the decay was linked to ROS. However, it also led to an unexpected negative effect: an increase in sperm decondensation with the same order of magnitude (+22.8%, P < 0.0009). The opening of interchain disulphide bridges in protamines may explain this aspect, as antioxidant vitamins, especially vitamin C, are able to open the cystin net, thus interfering with paternal gene activity during preimplantation development. This observation might explain the discrepancy observed concerning the role of these antioxidant treatments in improving male fertility.

Correlation between DNA damage and sperm parameters: a prospective study of 1,633 patients

OBJECTIVE To investigate DNA fragmentation by using terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling in relation to World Health Organization parameters and computer-aided sperm analysis (CASA) in sperm to determine the possibility of obtaining a correlation among CASA parameters, sperm morphology, and DNA fragmentation. DESIGN Sperm analysis according to World Health Organization parameters, terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) for sperm DNA fragmentation, and CASA for sperm movement. Prospective study. SETTING All the patients were under clinical management, consulting for hypofertility at a fertility center in France. PATIENT(S) One thousand six hundred thirty-three men who were referred for infertility investigation, including a complete sperm analysis. INTERVENTION(S) Sperm analysis and DNA damage testing. MAIN OUTCOME MEASURE(S) Sperm morphology, DNA fragmentation, and movement characteristics. RESULT(S) One third of the patients had a TUNEL rate of >30%. Analysis of the 21 semen parameters tested revealed that 7 of them were significantly correlated with the TUNEL results. CONCLUSION(S) World Health Organization sperm parameters and DNA damage are complementary, rather than strongly linked. This should be considered to more fully understand the paternal contribution in assisted reproductive technologies failures.

Effect of maternal and paternal age on pregnancy and miscarriage rates after intrauterine insemination

More than 17,000 intrauterine insemination (lUI) cycles were analysed retrospectively with respect to outcome according to differing aetiologies of infertility. The quantity and motility of spermatozoa in the final preparation used for insemination had a positive effect on the outcome, as classically observed in the past. It was found that advanced maternal age had a negative effect on the pregnancy rate and was associated with increased miscarriage rate. More interestingly, an exactly parallel effect was found for paternal age. The impact of increased age on necrospermia and sperm DNA structure is discussed as a probable direct cause of this paternal effect.

Sperm transcriptome profiling in oligozoospermia

PurposeInvestigate in what extent sperm transcriptome of infertile men is different from that of fertile individuals.MethodsSemen samples were collected for determination of sperm parameters as well as for RNA isolation. Gene expression profile was investigated in spermatozoa of 8 infertile and 3 fertile men by microarray analysis using the Affymetrix Chip HG-U133 Plus 2.0.Result(s)We observed up to 33-fold reduction expression of genes involved in spermatogenesis and sperm motility. Furthermore, there is an important decrease in expression of genes involved in DNA repair as well as oxidative stress regulation. In this study, we also show a striking drop in expression of histone modification genes.Conclusion(s)We found that transcription profile in germ cells of men with idiopathic infertility is different from that of fertile individuals. Interestingly, about 15% of the regulated genes (Eddy Rev Reprod 4:23–30, 1999) play a role in spermatogenesis.

Malonaldehyde formation and DNA fragmentation: two independent sperm decays linked to reactive oxygen species

Malondialdehyde (MDA), a product involved in membrane lipid peroxidation, was dosed in the sperm of 163 patients who had consulted the clinic regarding hypofertility. We attempted to determine if there was correlation between MDA content, sperm World Health Organization parameters and DNA fragmentation that results mainly from reactive oxygen species assaults. We found that no correlation could be established; however MDA and sperm decondensation were shown to be significantly linked. The impact of membrane polyunsaturated fatty acids and the role of phospholipid hydroperoxide glutathione peroxidase are discussed.

Methylation changes in mature sperm deoxyribonucleic acid from oligozoospermic men: assessment of genetic variants and assisted reproductive technology outcome

OBJECTIVE To characterize a potential genetic cause for methylation errors described in oligozoospermia. DESIGN Analysis of PEG1/MEST-DMR and H19-DMR methylation level in sperm, in parallel with the study of several genes on the Y chromosome, DNMT3A, and DNMT3L. Clinical outcome was also looked at regarding PEG1/MEST-DMR and H19-DMR methylation level in sperm. SETTING Research and diagnostic laboratories. PATIENT(S) One hundred nineteen normospermic and 175 oligozoospermic men consulting for couple infertility. INTERVENTION(S) We studied PEG1/MEST-DMR and H19-DMR methylation profiles in 294 men. We searched for Y chromosome gene aberrations and for mutations in both DNMT3A and DNMT3L genes in men showing epimutations. Assisted reproductive technology (ART) outcomes were also investigated. MAIN OUTCOME MEASURE(S) Sperm samples were collected from 294 volunteers for genomic DNA isolation that was used to study methylation profiles in imprinted loci and Y chromosome SMCY, DNMT3A, and DNMT3L genes. Pregnancy rate was also studied after ART treatment using sperm showing epimutations. RESULT(S) Epimutations in H19-DMR and PEG1/MEST-DMR were found in 20% and 3% of oligozoospermic men, respectively. We identified an amino acid change in DNMT3A in one case and in DNMT3L in eight men with altered methylation profiles. No mutations were detected in SMCY or in selected Y chromsome genes. No correlation between ART outcome and epimutations was found. CONCLUSION(S) We observed epimethylations in spermatozoa of oligozoospermic individuals, but no association was found with genetic variants or in the ART outcome.

Polymorphisms in MTHFR and MTRR genes associated with blood plasma homocysteine concentration and sperm counts

OBJECTIVE To investigate the relationship between MTHFR and MTRR genetic variants with respect to both blood plasma homocysteine concentration and sperm counts. DESIGN Polymerase chain reaction followed by specific enzymatic digestion to determine the genotype of the individuals and blood plasma homocysteine quantification by high-performance liquid chromatography. SETTING Research laboratory. PATIENT(S) Two hundred sixty-eight men seeking infertility counseling and 254 partners of infertile women. INTERVENTION(S) We studied three MTHFR (c.1286A → C, c.665C → T and c.203G → A) and two MTRR (c.66A → G and c.524C → T) single-nucleotide polymorphisms and characterized sperm parameters in both oligozoospermic and normospermic men. A cohort of 522 men was examined for this study. A subgroup of 103 men was constituted for quantification of Hcy levels. MAIN OUTCOME MEASURE(S) Semen samples were collected for determinations of sperm concentration, motility, and morphology according to World Health Organization guidelines as well as for DNA isolation. Blood samples of the corresponding individuals were obtained to quantify plasma homocysteine levels. RESULT(S) We did not observe a relationship between homocysteinemia and sperm counts. The MTHFR c.665C → T variant is associated with mild hyperhomocysteinemia in blood plasma in the TT homozygous state. CONCLUSION(S) No association was found between MTHFR/MTRR genetic variants and sperm counts. Although no association was observed with reduced sperm counts, the MTHFR 665TT genotype is associated with a significant increase in blood plasma homocysteine levels.

Imprinting: RNA expression for homocysteine recycling in the human oocyte

OBJECTIVE To investigate whether homocysteine, a well known inhibitor of methylation, which is produced after imprinting and other methylation processes, can be recycled to methionine in the oocyte, at least until the stage of maternal to zygotic transition (i.e., four- to eight-cell stage); before this stage, most of the biochemical processes are carried out with the use of maternal stores of protein and mRNA. DESIGN A first approach using microarrays and then reverse-transcription polymerase chain reaction (RT-PCR) for methionine synthase (5-methyltetrahydrofolate-homocysteine methyltransferase [MTR]), betaine-homocysteine methyltransferase (BHMT), and cystathionine-beta synthase (CBS). SETTING Two private hospitals. PATIENT(S) Patients involved in IVF/ICSI procedures. INTERVENTION(S) Germinal vesicle oocytes collected at the time of oocyte retrieval, RNA extraction amplification, RT-PCR, microarrays. MAIN OUTCOME MEASURE(S) mRNA expression of all the enzymes involved in the chain of methylation and recycling of homocysteine to methionine. RESULT(S) All of the enzymes required for methylation are present in the oocyte. Homocysteine can be recycled with BHMT and MTR. CONCLUSION(S) The human oocyte is able to regulate its Hcy level via remethylation using MTR and BHMT but not CBS. This aspect is important, because recent studies have shown that controlled ovarian hyperstimulation affects the homocysteine concentration in follicular fluid. This may regulate, at least in part, the risk of imprinting problems during IVF procedures.

Combined use of proacrosion immunocytochemistry and autosomal DNA in situ hybridisation for evaluvation of human ejaculated germ cells

The recently reported human pregnancies and births after fertilising oocytes with round spermatids recovered from the ejaculate of men with non-obstructive azoospermia have underscored the need for a more accurate evaluation of the nuclear and cytoplasmic maturation status of ejaculated germ cells. In this study we describe our first experience with a method combining the immunocytochemical visualisation of proacrosin with autosomal DNA fluorescence in situ hybridisation (FISH) to assess ejaculated germ cells from patients with a spermiogenesis defect. The proacrosin immunoreactivity, analysed with the use of the monoclonal antibody 4D4, has been detected in cells of round spermatid size presenting a haploid FISH figure as well as in larger cells whose ploidy corresponds to primary and secondary spermatocytes. These observations are in agreement with previously published results obtained, with the use of the same antibody, by immunocytochemical analysis of histological sections of testicular tissue. All the cells of round spermatid size possessing proacrosin immunoreactivity were found to be haploid by FISH. On the other hand, some of the haploid cells of round spermatid size did not possess proacrosin immunoreactivity. The structural pattern of proacrosin immunoreactivity was highly variable both in spermatids and in younger spermatogenic cells. These data show that cell size is the main criterion to be used for the identification of ejaculated round spermatids, whereas the presence of the developing acrosome represents only an auxiliary criterion. The scoring of acrosomal development in ejaculated spermatids may be useful as part of pre-treatment diagnosis before the inclusion of infertile couples in a spermatid conception programme.

La tératozoospermie à l’heure de l’ intracytoplasmic morphologically selected sperm injection (IMSI)

Until now, the morphological sperm analysis (spermocytogram) allows to define sperm normality, but the relationship between sperm morphology and fertility is not yet assessed. Although several studies do not report any relationship between abnormal sperm morphology and ICSI results, nevertheless, the success rate of ICSI sems to be dependent on injected sperm morphological aspect. Detailed morphological sperm examination (especially sperm head) at high magnification (from x 6600 to x 12500) (MSOME) in real time allows to select the best spermatozoa before oocyte injection (IMSI). In some cases, implantation and ongoing pregnancy rates were improved with this sperm selection method. Ultramorphologic criteria were established and the most predictive factor of sperm quality is the presence of vacuoles in the sperm head. Those vacuoles appear to be related to DNA damage (fragmentation and/or denaturation) and affect embryo development. To standardize those observations, several authors tried to establish sperm MSOME classifications in order to be used in routine and to replace the conventional spermocytogram in the next future.