Role of isoprostanes in human male infertility

Are F2-isoprostanes a better marker of semen lipid peroxidation than MDA in reproductive pathologies with inflammatory basis?

Many male reproductive pathologies and a part of undiagnosed infertility share an oxidative stress (OS) etiology with high reactive oxygen species and cytokine concentrations. The lack of reliable biomarkers to quantify oxidative injury is a crucial problem in the field of male infertility. In this observational study, IL-1β and the OS markers malondialdehyde (MDA) and F2-isoprostanes (F2-IsoPs) were quantified in seminal plasma of 46 infertile patients with varicocele, genitourinary infections, idiopathic infertility, and 11 fertile men. Semen analysis was performed following WHO guidelines, IL-1β was determined by ELISA, MDA was quantified by HPLC, and F2-IsoPs by GC/NICI-MS analysis. F2-IsoPs were immunolocalized in spermatozoa of fertile and infertile subjects. Results indicated that F2-IsoP, MDA, and IL-1β seminal levels positively correlated pairwise (p < 0.001) and showed negative correlations with sperm parameters (p < 0.001). Then, the studied population was grouped following the cause of infertility and the variables were compared between the different groups and a control sample. Seminal IL-1β, F2-IsoPs, and MDA were significantly higher in varicocele (p < 0.001, for MDA p < 0.01) and genitourinary infections (p < 0.001, for IL-1β p < 0.01) groups than those observed in fertile subjects. F2-IsoPs seemed to discriminate more accurately than MDA the different conditions, in particular idiopathic infertility. ROC curves demonstrated that the three analyzed indices were able to discriminate fertile and infertile patients. The immunofluorescence studies showed a low presence of F2-IsoPs in spermatozoa of fertile men and an evident labeling in the tail, and cytoplasmic residues of spermatozoa from infertile patients. In conclusion, this data confirmed that F2-IsoP level is a suitable marker of OS in seminal plasma, even more accurate than MDA and can be proposed for measuring OS in the clinical setting.

Blood-based biomarkers of frailty in older patients with cancer

PURPOSE OF REVIEW

This review aims to evaluate the current evidence on blood-based biomarkers for frailty detection in older cancer patients. It explores the potential of various biomarkers, including inflammatory markers and microRNAs (miRNAs), to serve as indicators of frailty and examines the limitations of existing studies. The review also highlights the need for further research to validate these biomarkers and improve their clinical applicability.

RECENT FINDINGS

Recent studies have examined blood biomarkers associated with frailty in older cancer patients. Findings suggest that elevated granulocyte levels and lower macrophage-derived stem cells and regulatory T cells are linked to frailty. Inflammatory biomarkers such as interleukin-6 and specific miRNAs, as well as higher neutrophil-to-lymphocyte ratios, have also been identified as potential indicators of frailty. While these biomarkers show promise, no single marker has proven sufficient, and combining them may improve frailty detection. Further research is needed to validate their clinical usefulness in this population.

SUMMARY

Blood-based biomarkers show potential for detecting frailty in older patients with cancer, but further research is needed, particularly beyond an inflammatory focus and with more robust study designs.

PPARγ Expression in Human Spermatozoa and Its Relationship with Seminal F2-Isoprostanes and Resolvin D1 in the Presence of Varicocele and Urogenital Infections

Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) is a regulating agent in antioxidant response also involved in controlling inflammation. The impact of varicocele and urogenital infections on sperm PPARγ expression was studied. The PPARγ gene expression was investigated in spermatozoa of 26 normozoospermic men grouped according to their clinical conditions: normal semen parameters (N), normal semen parameters and varicocele (N + V), and normal semen parameters and urogenital infections (N + UI). Sperm PPARγ expression was correlated with F2-isoprostanes (F2-IsoPs), as markers of lipid peroxidation, and Resolvin D1 (RvD1), a pro-resolving mediator in inflammation. Sperm PPARγ expression was evaluated through comparative real-time PCR, and F2-IsoPs and RvD1 were quantified in the seminal plasma via GC/NCI-MS/MS and immunoassay, respectively. PPARγ expression correlates positively with sperm morphology and vitality and negatively with F2-IsoPs and RvD1. Sperm morphology positively correlates with vitality and negatively with F2-IsoP and RvD1 levels. Despite the normozoospermia in the three examined groups, sperm morphology and PPARγ expression were significantly reduced in N + V and N + UI groups compared to the N group. Additionally, F2-IsoP and RvD1 levels were elevated in N + V and N + UI patients. These data suggest that PPARγ expression is compromised by inflammation and lipoperoxidation, providing new insights to further explore new possibilities of targeted treatment of male infertility.

Melatonin alleviates heat stress-induced spermatogenesis dysfunction in male dairy goats by regulating arachidonic acid metabolism mediated by remodeling the gut microbiota

BACKGROUND

Heat stress (HS) commonly occurring in summer has gradually become a factor threatening the reproductive performance of male dairy goats by reducing their fecundity. Despite the melatonin is applied to relieve HS, it is still unclear whether melatonin protects against reproductive damage induced by HS in dairy goats and how it works. The purpose of the present study is to evaluate the role of melatonin in alleviating HS-induced spermatogenesis dysfunction in male dairy goats and further explore its mechanism.

RESULTS

HS impaired spermatogenesis, sperm formation in the testes, and sperm maturation in the epididymis of dairy goats, resulting in decreased sperm quality. Melatonin rescued the decrease of sperm quality induced by HS via decreasing inflammatory and oxidative stress levels in testicular tissue and enhancing intercellular barrier function within the testes. Amplicon-based microbiota analysis revealed that despite gut microbiota differences between melatonin-treated dairy goats and NC dairy goats to some extent, melatonin administration tends to return the gut microbiota of male dairy goats under HS to the levels of natural control dairy goats. To explore whether the protective role of melatonin in sperm quality is mediated by regulating gut microbiota, fecal microbiota of HS dairy goats with or without melatonin treatment were transferred to HS mice, respectively. We found HS mice that had received fecal bacteria of HS dairy goats experienced serious testicular injury and dyszoospermia, while this phenomenon was ameliorated in HS mice that had received fecal bacteria of dairy goats treated with melatonin, indicating melatonin alleviates HS-induced spermatogenic damage in a microbiota dependent manner. We further found that the testicular tissue of both HS dairy goats and mice transplanted with HS dairy goat feces produced large amounts of arachidonic acid (AA)-related metabolites, which were closely associated with semen quality. Consistently, supplementation with AA has been shown to elevate the levels of inflammation and oxidative stress in the testicular tissue of mice, disrupting intercellular connections and ultimately leading to spermatogenic disorders.

CONCLUSION

This study has revealed that melatonin can effectively alleviate spermatogenic disorders in dairy goats caused by HS. This beneficial effect was primarily achieved through the modulation of gut microbiota, which subsequently inhibited the excessive synthesis of AA in testicular tissue. These discoveries are of great significance for preventing or improving the decline in male livestock reproductive performance caused by HS, enhancing the reproductive efficiency of elite male breeds, and ultimately improving the production efficiency of animal husbandry. Video Abstract.

Redox Homeostasis and Nrf2-Regulated Mechanisms Are Relevant to Male Infertility

Infertility represents a significant global health challenge, affecting more than 12% of couples worldwide, and most cases of infertility are caused by male factors. Several pathological pathways are implicated in male infertility. The main mechanisms involved are driven by the loss of reduction-oxidation (redox) homeostasis and the resulting oxidative damage as well as the chronic inflammatory process. Increased or severe oxidative stress leads to sperm plasma membrane and DNA oxidative damage, dysregulated RNA processing, and telomere destruction. The signaling pathways of these molecular events are also regulated by Nuclear factor-E2-related factor 2 (Nrf2). The causes of male infertility, the role of oxidative stress in male infertility and the Keap1-Nrf2 antioxidant pathway are reviewed. This review highlights the regulatory role of Nrf2 in the balance between oxidants and antioxidants as relevant mechanisms to male fertility. Nrf2 is involved in the regulation of spermatogenesis and sperm quality. Establishing a link between Nrf2 signaling pathways and the regulation of male fertility provides the basis for molecular modulation of inflammatory processes, reactive oxygen species generation, and the antioxidant molecular network, including the Nrf2-regulated antioxidant response, to improve male reproductive outcomes.

A Possible Role for Nerve Growth Factor and Its Receptors in Human Sperm Pathology

Nerve growth factor (NGF) signalling affects spermatogenesis and mature sperm traits. In this paper, we aimed to evaluate the distribution and the role of NGF and its receptors (p75NTR and TrKA) on the reproductive apparatus (testis and epididymis) and sperm of fertile men (F) and men with different pathologies, namely varicocele (V) and urogenital infections (UGIs). We collected semen samples from 21 individuals (31-40 years old) subdivided as follows: V (n = 7), UGIs (n = 7), and F (n = 7). We submitted the semen samples to bacteriological analysis, leucocyte identification, and analysis of sperm parameters (concentration, motility, morphology, and viability). We determined the seminal plasma levels of NGF, interleukin 1β (IL-1β), and F2-isoprostanes (F2-IsoPs), and the gene and protein expression of NGF receptors on sperm. We also used immunofluorescence to examine NGF receptors on ejaculated sperm, testis, and epididymis. As expected, fertile men showed better sperm parameters as well as lower levels of NGF, F2-IsoPs, and IL-1β compared with men with infertility. Notably, in normal sperm, p75NTR and TrKA were localised throughout the entire tail. TrKA was also found in the post-acrosomal sheath. This localisation appeared different in patients with infertility: in particular, there was a strong p75NTR signal in the midpiece and the cytoplasmic residue or coiled tails of altered ejaculated sperm. In line with these findings, NGF receptors were intensely expressed in the epididymis and interstitial tissue of the testis. These data suggest the distinctive involvement of NGF and its receptors in the physiology of sperm from fertile men and men with infertility, indicating a possible role for new targeted treatment strategies.

Pro-Atherogenic and Pro-Oxidant Diets Influence Semen and Blood Traits of Rabbit Bucks

Many dietary factors can affect sperm traits. We compared the effect of diets rich in pro-oxidant (flaxseed oil) and pro-atherogenic (coconut oil) substances without added antioxidants on semen traits, using the rabbit as an animal model. Thirty rabbit bucks (8 months old) were fed three diets for 150 days: CNT (control) a standard diet; HA (high-atherogenic) standard diet + 3% coconut oil, and HO (high-oxidizing) standard diet + 3% flaxseed oil. Semen samples were collected weekly for the evaluation of qualitative traits (kinetics, viability) and the oxidative damage (MDA and cytokines). Blood was collected at the start (T0) and end (T8) of the experimental period for the assessment of the oxidative damage (MDA and isoprostanoids), lipid profile, and testosterone. A worsening of sperm kinetics and viability was recorded in the HA group. Lipid oxidation in seminal plasma, as well as isoprostanoids in blood (F3-IsoPs and F4-NeuroPs), increased in both the HO and HA groups. A high level of TNF-α, a marker of inflammatory status, was recorded in the seminal plasma of the HA group. The resulting outcomes were mainly attributable to the different fatty acid profiles (SFA vs. PUFA) of the diets, which modulated an inflammatory/oxidative response.

Low-polarity untargeted metabolomic profiling as a tool to gain insight into seminal fluid

INTRODUCTION

A decrease in sperm cell count has been observed along the last several decades, especially in the most developed regions of the world. The use of metabolomics to study the composition of the seminal fluid is a promising approach to gain access to the molecular mechanisms underlying this fact.

OBJECTIVES

In the present work, we aimed at relating metabolomic profiles of young healthy men to their semen quality parameters obtained from conventional microscopic analysis.

METHODS

An untargeted metabolomics approach focusing on low- to mid-polarity compounds was used to analyze a subset of seminal fluid samples from a cohort of over 2700 young healthy men.

RESULTS

Our results show that a broad metabolic profiling comprising several families of compounds (including acyl-carnitines, steroids, and other lipids) can contribute to effectively distinguish samples provided by individuals exhibiting low or high absolute sperm counts.

CONCLUSION

A number of metabolites involved in sexual development and function, signaling, and energy metabolism were highlighted as being distinctive of samples coming from either group, proving untargeted metabolomics as a promising tool to better understand the pathophysiological processes responsible for male fertility impairment.

Oxidation of Polyunsaturated Fatty Acids as a Promising Area of Research in Infertility

In this review, the role of fatty acids (FA) in human pathological conditions, infertility in particular, was considered. FA and FA-derived metabolites modulate cell membrane composition, membrane lipid microdomains and cell signaling. Moreover, such molecules are involved in cell death, immunological responses and inflammatory processes. Human health and several pathological conditions are specifically associated with both dietary and cell membrane lipid profiles. The role of FA metabolism in human sperm and spermatogenesis has recently been investigated. Cumulative findings indicate F₂ isoprostanes (oxygenated products from arachidonic acid metabolism) and resolvins (lipid mediators of resolution of inflammation) as promising biomarkers for the evaluation of semen and follicular fluid quality. Advanced knowledge in this field could lead to new scenarios in the treatment of infertility.

Poultry Meat and Eggs as an Alternative Source of n-3 Long-Chain Polyunsaturated Fatty Acids for Human Nutrition

The beneficial effects of n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) on human health are widely known. Humans are rather inefficient in synthesizing n-3 LC-PUFA; thus, these compounds should be supplemented in the diet. However, most Western human diets have unbalanced n-6/n-3 ratios resulting from eating habits and the fact that fish sources (rich in n-3 LC-PUFA) are not sufficient (worldwide deficit ~347,956 t/y) to meet the world requirements. In this context, it is necessary to find new and sustainable sources of n-3 LC-PUFA. Poultry products can provide humans n-3 LC-PUFA due to physiological characteristics and the wide consumption of meat and eggs. The present work aims to provide a general overview of the main strategies that should be adopted during rearing and postproduction to enrich and preserve n-3 LC-PUFA in poultry products. The strategies include dietary supplementation of α-Linolenic acid (ALA) or n-3 LC-PUFA, or enhancing n-3 LC-PUFA by improving the LA (Linoleic acid)/ALA ratio and antioxidant concentrations. Moreover, factors such as genotype, rearing system, transport, and cooking processes can impact the n-3 LC-PUFA in poultry products. The use of a multifactorial view in the entire production chain allows the relevant enrichment and preservation of n-3 LC-PUFA in poultry products.

Seminal Levels of Omentin-1/ITLN1 in Inflammatory Conditions Related to Male Infertility and Localization in Spermatozoa and Tissues of Male Reproductive System

Purpose

Omentin-1/intelectin (ITLN)1 is an adipocytokine with both anti-inflammatory and anti-oxidative stress properties, and little is known about its role in male reproduction. This study was aimed at exploring the relationships among omentin-1/ITLN1, semen parameters and F₂-isoprostanes (F₂-IsoPs), a maker of oxidative stress, in groups of patients affected by different pathologies. In addition, omentin-1/ITLN1 immunolocalization was assessed in ejaculated spermatozoa and in tissues of male reproductive system.

Patients and Methods

Semen samples of infertile patients with varicocele (n = 27), genitourinary infections (n = 17), idiopathic infertility (n = 15) and fertile men (n = 21) were analyzed following WHO guidelines, and seminal plasma were used to determine omentin-1/ITLN1 by ELISA and F₂-IsoP levels by gas chromatography/negative-ion chemical ionization tandem mass spectrometry. Omentin-1/ITLN1 was localized in human sperm and in the tissue of male reproductive system.

Results

Considering all participants, F₂-IsoP and omentin-1/ITLN1 levels were positively correlated (p = 0.000), and both these indices were negatively correlated with sperm parameters. Infertile patients showed lower sperm parameters than fertile ones; varicocele and infection groups had significantly increased levels of F₂-IsoPs (both p = 0.000) and omentin-1/ITLN1 (p = 0.000 and p = 0.001, respectively). Omentin-1/ITLN1 signal was located as a spot in the connecting piece (in 43.5% of cases midpiece was also labeled) of sperm from fertile men and in cytoplasmic residue and in the entire tail in sperm of patients with varicocele and genitourinary infections. A focal omentin-1/ITLN1 immunolabelling was evident in the basal area of epididymal tubule, and a diffuse signal was present in the seminal vesicle epithelium.

Conclusion

Semen omentin-1/ITLN1 originates from seminal vesicles, its levels increase in inflammatory conditions and are negatively correlated with sperm parameters. For this reason, a sort of protective role of omentin-1/ITLN1 can be postulated, as this adipokine shows anti-inflammatory properties also in many other biological systems.

Do Seminal Isoprostanes Have a Role in Assisted Reproduction Outcome?

F₂-isoprostanes (F₂-IsoPs), stereoisomers of prostaglandin F2α generated by the free radical-induced oxidation of arachidonic acid, have been associated with different male infertility conditions. This study aimed to evaluate the role of seminal isoprostane levels and sperm characteristics in the reproductive outcome and embryo quality of 49 infertile couples. Semen analysis was performed following WHO guidelines. Sperm chromatin maturity was detected using an aniline blue (AB) assay, and DNA integrity was assessed using the acridine orange (AO) test. Seminal F₂-IsoP levels were quantified by gas chromatography/negative ion chemical ionization tandem mass spectrometry (GC/NICI–MS/MS) analysis. Correlations among variables and their impact on in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) outcome were investigated. F₂-IsoP levels are positively correlated with double-stranded DNA sperm (p < 0.001) and negatively correlated with mature sperm chromatin (p < 0.001). Patients with positive outcomes had an increased percentage of sperm with double-stranded DNA, as did patients producing high-quality embryo, who showed higher F₂-IsoP levels compared to those detected in the low-quality embryo group. An intriguing relationship between a mild increase in F₂-IsoP levels, DNA integrity, and embryo quality seems to indicate that the non-enzymatic oxidation of arachidonic acid can be also a marker of metabolic activity in human semen.

F4-Neuroprostanes: A Role in Sperm Capacitation

F₄-neuroprostanes (F₄-NeuroPs), derived from the oxidative metabolization of docosahexaenoic acid (DHA), are considered biomarkers of oxidative stress in neurodegenerative diseases. Neurons and spermatozoa display a high DHA content. NeuroPs might possess biological activities. The aim of this in vitro study was to investigate the biological effects of chemically synthetized 4-F_4t-NeuroP and 10-F_4t-NeuroP in human sperm. Total progressive sperm motility (p < 0.05) and linearity (p = 0.016), evaluated by a computer-assisted sperm analyzer, were significantly increased in samples incubated with 7 ng F₄-NeuroPs compared to non-supplemented controls. Sperm capacitation was tested in rabbit and swim-up-selected human sperm by chlortetracycline fluorescence assay. A higher percentage of capacitated sperm (p < 0.01) was observed in samples incubated in F₄-NeuroPs than in the controls. However, the percentage of capacitated sperm was not different in F₄-NeuroPs and calcium ionophore treatments at 2 h incubation. The phosphorylated form of AMPKα was detected by immunofluorescence analysis; after 2 h F₄-NeuroP incubation, a dotted signal appeared in the entire sperm tail, and in controls, sperm were labeled in the mid-piece. A defined level of seminal F₄-NeuroPs (7 ng) showed a biological activity in sperm function; its addition in sperm suspensions stimulated capacitation, increasing the number of sperm able to fertilize.

Protective Effect of Chlorogenic Acid on Human Sperm: In Vitro Studies and Frozen-Thawed Protocol

The study evaluated the chlorogenic acid (CGA) antioxidant potential on oxidative stress (OS) induced in vitro in human spermatozoa and during cryopreservation procedure. Swim-up selected spermatozoa were treated with 100 µM CGA, 100 µM H₂O₂ to induce lipid peroxidation (LPO), and with both compounds and the effects on mitochondrial membrane potential (MMP) by JC-1, DNA integrity by acridine orange (AO), and sperm ultrastructure by transmission electron microscopy (TEM), were evaluated. CGA antioxidant activity was assessed by measuring malondialdehyde (MDA) and F₂-isoprostanes (F₂-IsoPs) in the media. The CGA protective activity and the immunolocalization of Phospho-AMPKα (Thr172) were explored in frozen-thawed sperm. CGA was not toxic for sperm motility, DNA integrity and MMP. The increase in MDA (p < 0.05) and F₂-IsoPs (p < 0.001), DNA damage (p < 0.01) and low MMP (p < 0.01) levels after H₂O₂ treatment were reduced in presence of CGA as well as the percentage of broken plasma membranes (p < 0.01) and altered acrosomes (p < 0.01) detected by TEM. Treated frozen-thawed spermatozoa showed increased sperm motility (p < 0.01), DNA integrity (p < 0.01), MMP (p < 0.01), reduced MDA (p < 0.01) and increased sperm percentage with Phospho-AMPKα labelling in the head (p < 0.001). CGA can be used to supplement culture media during semen handling and cryopreservation where OS is exacerbated.

Tissue Antioxidant Status and Lipid Peroxidation Are Related to Dietary Intake of n-3 Polyunsaturated Acids: A Rabbit Model

Polyunsaturated fatty acid (PUFA) metabolism and tissue distribution is modulated by the oxidation of these molecules. This research aimed to investigate the implication of dietary n-3 PUFA supplementation (precursor and long-chain PUFA) on the PUFA profile and oxidative status of the liver, testis, and brain of adult rabbit bucks. Twenty New Zealand White rabbit bucks were divided into four experimental groups (n = 5 per group) and were fed different diets for 110 days: control (CNT), standard diet containing 50 mg/kg alpha-tocopheryl acetate (vitamin E); CNT+, standard diet + 200 mg/kg vitamin E; FLAX, standard diet + 10% flaxseed + 200 mg/kg vitamin E; or FISH, standard diet + 3.5% fish oil + 200 mg/kg vitamin E. Antioxidants (enzymatic and non-enzymatic), oxidative status (malondialdehyde and isoprostanoids), and n-3 and n-6 PUFAs of tissues were analysed. A chain mechanism of oxidant/antioxidant molecules, which largely depended on the particular PUFA composition, was delineated in the different organs. The liver showed an oxidant/antioxidant profile and lipid pathways widely modulated by PUFA and vitamin E administration; on the other hand, the testis' oxidative profile rather than its lipid profile seemed to be particularly affected, an outcome opposite to that of the brain (modulation operated by dietary PUFA).