P-048 Male obesity with or without sperm parameters alteration: a seminal proteomic comparison

Abstract Study question Is there a difference in seminal protein expression between men with obesity with or without changes in sperm parameters? Summary answer Men with obesity and changes in their sperm parameters present lower concentrations of seminal proteins compared to men with obesity and normal sperm parameters. What is known already Through multifactorial pathophysiology, obesity can interfere with sperm parameters, (concentration, motility, morphology, and viability); however, literature has shown that not every man with obesity presents changes in his sperm features. Moreover, the seminal proteomics from men with obesity (without considering the sperm status) showed the presence of molecules that justify an interference with sperm, but simultaneously showed the existence of proteins that promote homeostasis. Thereby, we want to verify if the seminal proteins expression is capable to explain/to reflect why men with the same diagnosis, obesity, can present different effects in their gametes. Study design, size, duration A prospective study was conducted with the inclusion of 73 men who were distributed into 3 groups according to their percentage of body fat (according to bioelectrical impedance) and sperm features (results above or below the fifth percentile from WHO manual, 2021). These groups were called control eutrophic (n = 19), obesity normal semen (n = 33), and obesity altered semen (n = 21). The study lasted two years. Participants/materials, setting, methods All men collected seminal samples after 2 to 7 days of ejaculatory abstinence by masturbation; with this sample, conventional semen analysis was performed (WHO, 2021), which assisted in group distribution. With the remained sample, centrifugation was performed to obtain seminal plasma. Then, seminal plasma obtained was used to evaluate protein levels. To this end, we quantified total proteins, prepared each sample, and performed shotgun proteomic analysis using mass spectrometry (LC-MS/MS). Main results and the role of chance As expected, the fat percentage was higher in the obesity groups; however, there was no statistical difference between those with and without alteration of sperm features. Conventional semen analysis indicated significant results for the variables progressive motility (p < 0,0001), non-progressive motility (p = 0,006), immotile (p < 0,0001), sperm concentration and count (p < 0,0001), morphology (p < 0,0001), and viability (p = 0,002) with the worst values always being observed in the obesity altered semen group, with the exception of the non-progressive motility variable, in which the significant result was between the eutrophic and obesity normal semen group (the latter presenting a lower percentage of sperm with non-progressive motility). Finally, in the proteomic analysis, 746 proteins were found in which 30 were differentially represented between the groups. In the obesity altered semen group, we found that 3 proteins were practically absent (Kunitz-type protease inhibitor 3, Ovochymase-2, Dipeptidase 3). Furthermore, the other proteins showed significant results that varied between the groups, always with lower concentrations in the obesity groups and even lower concentrations in the obesity altered semen group; it is important to highlight that samples from men with obesity and normal semen already presented diminished proteins concentrations in relation to samples from eutrophic men. Limitations, reasons for caution The onset time of obesity can be a reason for the presence of alterations in sperm parameters; however, we do not have a specific tool to determine this variable. Wider implications of the findings Semen from men with obesity and altered sperm present greater damage at the molecular level. However, even though men with obesity with normal sperm characteristics present a good concentration of proteins that justify this normality, such molecules already show decline in relation to eutrophic men predicting a possible sperm alteration. Trial registration number No