Abstract
BackgroundOxidative stress plays a key role in the etiology of male infertility. Significant alterations in the sperm proteome are associated with poor semen quality. The aim of the present study was to examine if elevated levels of reactive oxygen species cause an alteration in the proteomic profile of spermatozoa.MethodsThis prospective study consisted of 52 subjects: 32 infertile men and 20 normal donors. Seminal ejaculates were classified as ROS+ or ROS- and evaluated for their proteomic profile. Samples were pooled and subjected to LC-MS/MS analysis through in-solution digestion of proteins for peptide characterization. The expression profile of proteins present in human spermatozoa was examined using proteomic and bioinformatic analysis to elucidate the regulatory pathways of oxidative stress.ResultsOf the 74 proteins identified, 10 proteins with a 2-fold difference were overexpressed and 5 were underexpressed in the ROS+ group; energy metabolism and regulation, carbohydrate metabolic processes such as gluconeogenesis and glycolysis, protein modifications and oxidative stress regulation were some of the metabolic processes affected in ROS+ group.ConclusionsWe have identified proteins involved in a variety of functions associated with response and management of oxidative stress. In the present study we focused on proteins that showed a high degree of differential expression and thus, have a greater impact on the fertilizing potential of the spermatozoa. While proteomic analyses identified the potential biomarkers, further studies through Western Blot are necessary to validate the biomarker status of the proteins in pathological conditions.
Highlights
Oxidative stress plays a key role in the etiology of male infertility
46.8% (15/32) had > 1 × 106 round cells / mL compared to donors 35% (7/20) of the donors, of these 15 patients, 15.6% were positive for the Endtz test – a marker for granulocytes, which are the major contributors of reactive oxygen species (ROS) production
Oxidative stress plays a key role in the etiology of male infertility, possibly by altering protein expression levels in spermatozoa, causing molecular and genetic defects
Summary
Oxidative stress plays a key role in the etiology of male infertility. Significant alterations in the sperm proteome are associated with poor semen quality. The aim of the present study was to examine if elevated levels of reactive oxygen species cause an alteration in the proteomic profile of spermatozoa. Male-factor infertility contributes to 50% of infertile couples worldwide, and while the causes are multifactorial, current research has focused on oxidative stress. Oxidative stress may lead to alterations in protein expression levels in spermatozoa, causing molecular and genetic defects. Research has already shown that oxidative stress is associated with a variety of male infertility diagnosis such as varicocele, idiopathic infertility, spinal cord injury, prostatitis and leukocytospermia [1,2,3,4,5,6,7,8]. Understanding the protein profile of spermatozoa is essential for identifying the protein alterations that occur as a result of increased production of ROS and for better diagnosis of male infertility. Numerous studies have reported the presence of proteins in studies involving human spermatozoa through the implementation of proteomic techniques such as 2-
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