A MALDI MS Investigation of the Lysophosphatidylcholine/Phosphatidylcholine Ratio in Human Spermatozoa and Erythrocytes as a Useful Fertility Marker

Combined Use of MALDI-TOF Mass Spectrometry and 31P NMR Spectroscopy for the Analysis of (Phospho)Lipids

Lipids are important and abundant constituents of all biological tissues and body fluids. In particular, phospholipids (PLs) constitute a major part of the cellular membrane and play a role in signal transduction, and some selected PLs are increasingly considered as potential disease markers. Unfortunately, methods of lipid analysis are less established in comparison to techniques of protein analysis. Mass spectrometry (MS) is an increasingly used technique to analyze lipids, especially in combination with electrospray ionization MS, which is the most commonly used ionization technique in lipidomics. Matrix-assisted laser desorption/ionization coupled to time-of-flight MS (MALDI-TOF MS) has itself proven to represent a useful tool in the field of lipid analysis. ³¹P nuclear magnetic resonance (NMR) spectroscopy, another powerful method for PL analysis, represents a direct quantitative method and does not suffer from suppression effects.This paper gives an overview of methodological aspects of MALDI-TOF MS and ³¹P NMR in lipid research and summarizes the specific advantages and drawbacks of both methods. In particular, suppression effects in MS will be highlighted, and possible ways to overcome this problem, e.g., the use of different matrices and separation of the relevant lipid mixture prior to analysis, will be discussed.

The Lipidomics of Spermatozoa and Red Blood Cells Membrane Profile of Martina Franca Donkey: Preliminary Evaluation

Fatty acid-based lipidomic analysis has been widely used to evaluate health status in human medicine as well as in the veterinary field. In equine species, there has been a developing interest in fertility and sperm quality. Fatty acids, being the principal components of the membranes, play an active role in the regulation of the metabolic activities, and their role on spermiogenesis seems to be of great importance for the resulting quality of the sperm and, thus, fertility. With the application of widely used lipidomic techniques, the aim of this study was to evaluate: (a) the fatty acid content of the spermatozoa's membranes of 26 healthy male Martina Franca donkeys and its possible correlation with sperm parameters, and (b) the evaluation of the composition of the red blood cells' membrane. PUFA omega-6 are the principal components (40.38%) of the total PUFA content (47.79%) in both types of cells; however, DPA is the predominant one on the spermatozoa's membrane (27.57%) but is not present in the erythrocyte's membrane. Spermatozoa's motility (%) is positively correlated with stearic acid and EPA, and progressive motility (%), with oleic acid. These findings offer information on the composition of both types of cells' membranes in healthy male MF donkeys and reflect the metabolic transformations of the spermatozoa's membrane during the maturation period, providing a better perception of the role of fatty acids in sperm parameters and fertility.

Oral Lycopene Administration Attenuates Inflammation and Oxidative Stress by Regulating Plasma Lipids in Rats with Lipopolysaccharide-Induced Epididymitis

Purpose

Epididymitis histological alterations and related long-term reproductive issues cannot be cured by antibiotics alone. Few studies have been done on the effect of lycopene on epididymitis, despite the fact that it is an efficient antioxidant. The objective of this study was to assess the impact of lycopene on Lipopolysaccharide (LPS)-induced epididymis and lipid metabolism.

Methods

Thirty-one 260–290g rats were separated into the blank control group (n=10), the oil-control group (n=10), the single intraperitoneal injection of 5 mg/kg LPS (n=5), and the continuous intragastric of 5 mg/kg lycopene (n=6). The animals were euthanized after four weeks, and blood and the epididymis were removed for analysis.

Results

Lycopene significantly decreased IL-1α, IL-1β, TNF-α, MCP-1, IL-6 and lipid peroxidation product Malondialdehyde in serum and epididymis. It significantly increased the epididymis’s antioxidant enzyme and total antioxidant capacity. According to LC-MS plasma lipidomics, lycopene increased phosphatidylcholine, lysophosphatidylcholine, decreased phosphatidylethanolamine, triacylglycerol, and diacylglycerol levels, changed the composition of lipids, altered metabolic pathways, and these changes were related to the mechanism of anti-inflammatory and oxidative stress. 20 lipids, including PC (20:5e) and LPC (14:0), were identified through additional Spearman correlation analysis as being related to cytokines and oxidation indices. They served as possible lipid markers that may be utilized to gauge the severity of inflammation.

Conclusion

Lycopene has anti-inflammatory and antioxidant properties that improve histopathological and functional damage in LPS-induced epididymitis and is an alternate supplement for treating epididymitis. Lipidomics provide new perspectives on the possible mechanism of lycopene in protecting against LPS-induced epididymitis by integrating lipid metabolism and inflammation.

Effects of Heat Stress on Motion Characteristics and Metabolomic Profiles of Boar Spermatozoa

Heat stress (HS) commonly causes boar infertility and economic loss in the swine industry. The heat tolerance of boar semen presents obvious differences among individuals. However, whether heat stress affects motion characteristics and the metabolome profile in boar sperm remains unclear. In this study, the kinetic features of sperm from HS and non-HS (NHS) groups were detected by computer-assisted sperm analysis, and metabolomic profiling was performed by liquid chromatography−mass spectrometry. The results showed that heat stress significantly reduced sperm motility, average path distance (APD), straight-line velocity (VSL), straightness (STR), and linearity (LIN) (p < 0.05). A total of 528 and 194 metabolites in sperm were identified in the positive and negative ion modes, respectively. Lipids and lipid-like molecules, and organic acids and derivatives were major metabolic classes in the two modes. Furthermore, we separately identified 163 and 171 differential metabolites in the two modes between HS and NHS groups. Clustering analysis further revealed significant metabolic changes in sperm after heat stress. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that differential metabolites in the two modes were enriched in glycerophospholipid, choline, and alanine, aspartate, and glutamate and lysine metabolism. Taken together, these results demonstrate that heat stress can alter the motion characteristics and metabolomic profiles of boar sperm.

Seminal lipid profiling and antioxidant capacity: A species comparison

On their way to the oocyte, sperm cells are subjected to oxidative stress, which may trigger the oxidation of phospholipids (PL). Applying MALDI-TOF MS, HPTLC and ESI-IT MS, we comparatively analyzed the PL compositions of semen and blood of species differing in their reproductive systems and types of nutrition (bull, boar, stallion, lion and man) with regard to the sensitivity to oxidation as well as the accumulation of harmful lyso-PL (LPL), transient products of lipid oxidation. In addition, the protective capacity of seminal fluid (SF) was also examined. The PL composition of erythrocytes and blood plasma is similar across the species, while pronounced differences exist for sperm and SF. Since the blood function is largely conserved across mammalian species, but the reproductive systems may vary in many aspects, the obtained results suggest that the PL composition is not determined by the type of nutrition, but by the relatedness of species and by functional requirements of cell membranes such as fluidity. Sperm motion and fertilization of oocytes require a rather flexible membrane, which is accomplished by significant moieties of unsaturated fatty acyl residues in sperm lipids of most species, but implies a higher risk of oxidation. Due to a high content of plasmalogens (alkenyl ether lipids), bull sperm are most susceptible to oxidation. Our data indicate that bull sperm possess the most effective protective power in SF. Obviously, a co-evolution of PL composition and protective mechanisms has occurred in semen and is related to the reproductive characteristics. Although the protective capacity in human SF seems well developed, we recorded the most pronounced individual contaminations with LPL in human semen. Probably, massive oxidative challenges related to lifestyle factors interfere with natural conditions.

Drosophila Lysophospholipase Gene swiss cheese Is Required for Survival and Reproduction

Simple Summary

Biological evolution implies fitness of newly evolved organisms that have inherent adaptive traits because of mutations in genes. However, most mutations are detrimental, and they spoil the organism’s life, its survival and its ability to leave progeny. Some genes are extremely vital for an organism, and therefore, they tend to save their structure and do not mutate or do it very composedly. That is the case of the gene encoding PNPLA6 lysophospholipase domain that evolved in bacteria, and evolution obliged it to save its function in higher animals. In mammals, complete dysfunction of such a gene is lethal because of its high importance in placenta for early embryo development. Why is it conserved in other species, for instance insects, that have no placenta? Here we studied the role of the PNPLA6-encoding gene named swiss cheese in Drosophila melanogaster fitness. We have found that its dysfunction results in premature death of specimens and their inability to leave enough progeny. Thus, we provide the first evidence for significance of the gene that encodes the lysophospholipase enzyme in fitness of insects.

Abstract

Drosophila melanogaster is one of the most famous insects in biological research. It is widely used to analyse functions of different genes. The phosphatidylcholine lysophospholipase gene swiss cheese was initially shown to be important in the fruit fly nervous system. However, the role of this gene in non-nervous cell types has not been elucidated yet, and the evolutional explanation for the conservation of its function remains elusive. In this study, we analyse expression pattern and some aspects of the role of the swiss cheese gene in the fitness of Drosophila melanogaster. We describe the spatiotemporal expression of swiss cheese throughout the fly development and analyse the survival and productivity of swiss cheese mutants. We found swiss cheese to be expressed in salivary glands, midgut, Malpighian tubes, adipocytes, and male reproductive system. Dysfunction of swiss cheese results in severe pupae and imago lethality and decline of fertility, which is impressive in males. The latter is accompanied with abnormalities of male locomotor activity and courtship behaviour, accumulation of lipid droplets in testis cyst cells and decrease in spermatozoa motility. These results suggest that normal swiss cheese is important for Drosophila melanogaster fitness due to its necessity for both specimen survival and their reproductive success.

Phospholipases and Reactive Oxygen Species Derived Lipid Biomarkers in Healthy and Diseased Humans and Animals - A Focus on Lysophosphatidylcholine

Phospholipids (PL) are converted into lipid biomarkers by the action of phospholipases and reactive oxygen species (ROS), which are activated or released under certain physiological and pathophysiological conditions. Therefore, the in vivo concentration of such lipid biomarkers [e.g., lysophospholipids (LPLs)] is altered in humans and animals under different conditions such as inflammation, stress, medication, and nutrition. LPLs are particularly interesting because they are known to possess pro- and anti-inflammatory properties and may be generated by two different pathways: either by the influence of phospholipase A₂ or by different reactive oxygen species that are generated in significant amounts under inflammatory conditions. Both lead to the cleavage of unsaturated acyl residues. This review provides a short summary of the mechanisms by which lipid biomarkers are generated under in vitro and in vivo conditions. The focus will be on lysophosphatidylcholine (LPC) because usually, this is the LPL species which occurs in the highest concentration and is, thus, easily detectable by chromatographic and spectroscopic methods. Finally, the effects of lipid biomarkers as signaling molecules and their roles in different human and animal pathologies such as infertility, cancer, atherosclerosis, and aging will be shortly discussed.

Changes in Bull Semen Metabolome in Relation to Cryopreservation and Fertility

Semen cryopreservation determines several sperm damages, including the loss of fertility-associated proteins. The purpose of the study was to compare the metabolite contents in bovine sperm and seminal plasma before and after cryopreservation, and between high- and low-fertility bulls in vitro. Forty-eight ejaculates, collected from eight bulls (six per bull), were analyzed by liquid chromatography-mass spectrometry. Cryopreservation resulted in an over-expression of lysophosphatidylcholine (0:0/18:2(9Z,12Z)) in seminal plasma. In addition, higher levels of glycine betaine and pyro-l-glutaminyl-l-glutamine were observed in cryopreserved compared to fresh spermatozoa. The fresh seminal plasma of high-fertility bulls showed an over-expression of l-acetylcarnitine, glycerol tripropanoate, 2,3-diacetoxypropyl stearate and glycerophosphocholine, and an under-expression of lysophosphatidylcholine and butyrylcarnitine, compared to low-fertility bulls. Higher levels of glycerophosphocholine and lysophosphatidylcholine (16:0/0:0) were recorded in fresh spermatozoa from high-fertility bulls. In high-fertility bulls, a greater content of glycerophosphocholine and lower levels of butyrylcarnitine, glycine betaine and l-carnitine were found in cryopreserved seminal plasma, and lower levels of glycine betaine were detected in cryopreserved spermatozoa. In conclusion, cryopreservation affects bovine semen metabolome at both plasmatic and cellular compartments, and metabolic profile differs between high- and low-fertility bulls.

Exploring metabolomics biomarkers for evaluating the effectiveness of concurrent radiochemotherapy for cervical cancers

Background

Cervical cancer is the second most common female malignancy worldwide. The main method to evaluate the effect of concurrent chemoradiotherapy (CCRT) in the locally advanced stage is imaging which cannot meet the clinical needs. This study aimed to explore potential cervical cancer biomarkers via plasma metabolomics and evaluate the effectiveness of CCRT and disease progression.

Methods

Twenty-four primary and thirty recurrent patients were enrolled between November 2016 and November 2017. Plasma samples were obtained by centrifugation of whole blood collected from enrolled patients at admission and from primary patients after CCRT. Plasma metabolic profiles were determined via ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry. Multivariate analyses and public databases were used to screen and identify differential metabolites. Pathway analysis was conducted using MetaboAnalyst.

Results

Metabolic profiles obtained were significantly different among primary, post-CCRT-treated, and recurrent patients. Multivariate analyses showed that 37 metabolites differed significantly among the three groups, of which the levels of 22 metabolites changed significantly after CCRT and recovered or even exceeded the levels in primary patients when the tumor reappeared. These 22 metabolites were mainly lipids involved in sphingolipid and glycerophospholipid metabolism. Among them, 8 metabolites with area under curve values above 0.75 between each pair of groups exhibited great potential for evaluating CCRT effectiveness and disease progression.

Conclusions

Our results show significantly different plasma metabolic profiles among the three cervical cancer groups; 8 metabolites were identified as potential biomarkers to evaluate the effectiveness of CCRT and disease progression, which can help evaluate the prognosis and treatment of cervical cancer in a timely manner.

Alteration of Cholesterol Sulfate/Seminolipid Ratio in Semen Lipid Profile of Men With Oligoasthenozoospermia

The reduction of sperm motility and count, or oligoasthenozoospermia, is one of the major causes of reduced fertility or infertility in men. Lipid composition of spermatozoa is important in determining their functional characteristics, in particular on motility, acrosomal exocytosis or fusogenic properties of the sperm. Here we investigated the levels of semen lipids in 11 infertile patients with severe oligoasthenozoospermia and 9 normozoospermic subjects with normal motility values. Sperm polar and neutral lipids were analyzed by thin-layer chromatography (TLC) and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Semen of patients with oligoasthenozoospermia showed a reduction of the degree of fatty acid unsaturation in the phospholipids chains that might affect the membrane fluidity. Furthermore, a significant higher cholesterol sulfate/seminolipid ratio was found in semen of oligoasthenozoospermic patients than in subjects with normal motility values, suggesting a critical role of sulfolipids in semen quality. The results may facilitate the understanding of the role of lipids on male fertility and offer interesting perspectives to find innovative treatments for oligoasthenozoospermia.

Prognostic biomarkers of cervical squamous cell carcinoma identified via plasma metabolomics

Cervical cancer is the second most common female malignancy worldwide. The metabolic profile of plasma associated with the prognosis of cervical cancer remains poorly understood. In this cross-sectional study, plasma samples were collected from three groups of patients with CSCC, namely primary patients before treatment (BT group), patients with a poor prognosis (PP group, including patients with distant metastasis and local recurrence), and patients with a good prognosis within two years after the first treatment (GP group). The plasma metabolomics was conducted to detect the dynamic changes of metabolites via ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry. Multivariate analyses, including principle component, partial least square-discriminant, and orthogonal projection to latent structure-discriminant analyses, were performed to compare each pair of the three groups. The differential metabolites were identified by comparison of the exact m/z values and mass spectrometry (MS)/MS spectra with the structural information of the metabolites obtained from the Human Metabolome Database (http://www.hmdb.ca/) and LIPID MAPS (http://www.lipidmaps.org/). To screen for potential markers, receiver operating characteristic curve analysis of the differential metabolites. Finally, thirty plasma samples were collected from each group. Multivariate analyses showed that 31 metabolites were significantly different among the 3 groups studied. Of those, the 5 metabolites phosphatidyl choline (15:0/16:0), phosphatidyl glycerol (12:0/13:0), actosylceramide (d18:1/16:0), D-Maltose, and phthalic acid, with an area under the curve above 0.75, were identified as potential biomarkers. The present findings provide evidence for biomarkers to monitor prognosis of patients with CSCC, which may help in better managing the disease.

Metabolomic profiling reveals correlations between spermiogram parameters and the metabolites present in human spermatozoa and seminal plasma

In 50% of all infertility cases, the male is subfertile or infertile, however, the underlying mechanisms are often unknown. Even when assisted reproductive procedures such as in vitro fertilization and intracytoplasmic sperm injection are performed, the causes of male factor infertility frequently remain elusive. Since the overall activity of cells is closely linked to their metabolic capacity, we analyzed a panel of 180 metabolites in human sperm and seminal plasma and elucidated their associations with spermiogram parameters. Therefore, metabolites from a group of 20 healthy donors were investigated using a targeted LC-MS/MS approach. The correlation analyses of the amino acids, biogenic amines, acylcarnitines, lysophosphatidylcholines, phosphatidylcholines, sphingomyelins and sugars from sperm and seminal plasma with standard spermiogram parameters revealed that metabolites in sperm are closely related to sperm motility, whereas those in seminal plasma are closely related to sperm concentration and morphology. This study provides essential insights into the metabolome of human sperm and seminal plasma and its associations with sperm functions. This metabolomics technique could be a promising screening tool to detect the factors of male infertility in cases where the cause of infertility is unclear.

Combined Use of MALDI-TOF Mass Spectrometry and 31P NMR Spectroscopy for Analysis of Phospholipids

Lipids are important and abundant constituents of all biological tissues and body fluids. In particular, phospholipids (PL) constitute a major part of the cellular membrane, play a role in signal transduction, and some selected PL are increasingly considered as potential disease markers. However, methods of lipid analysis are less established in comparison to techniques of protein analysis. Mass spectrometry (MS) is an increasingly used technique to analyze lipids, especially in combination with electrospray ionization (ESI) MS which is the so far best established ionization method. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS has itself proven to be also useful in the field of lipid analysis. ³¹P nuclear magnetic resonance (NMR) spectroscopy is another powerful method of PL analysis, represents a direct quantitative method, and does not suffer from suppression effects.This chapter gives an overview of methodological aspects of MALDI-TOF MS and ³¹P NMR in lipid research and summarizes the specific advantages and drawbacks of both methods. In particular, suppression effects in MS will be highlighted and possible ways to overcome this problem (use of different matrices, separation of the relevant lipid mixture prior to analysis) will be discussed.

Lysophosphatidylcholines to phosphatidylcholines ratio predicts advanced knee osteoarthritis

OBJECTIVE

To identify novel biomarker(s) for predicting advanced knee OA.

METHODS

Study participants were derived from the Newfoundland Osteoarthritis Study and the Tasmania Older Adult Cohort Study. All knee OA cases were patients who underwent total knee replacement (TKR) due to primary OA. Metabolic profiling was performed on fasting plasma. Four thousand and eighteen plasma metabolite ratios that were highly correlated with that in SF in our previous study were generated as surrogates for joint metabolism.

RESULTS

The discovery cohort included 64 TKR cases and 45 controls and the replication cohorts included a cross-sectional cohort of 72 TKR cases and 76 controls and a longitudinal cohort of 158 subjects, of whom 36 underwent TKR during the 10-year follow-up period. We confirmed the previously reported association of the branched chain amino acids to histidine ratio with advanced knee OA (P = 9.3 × 10(-7)) and identified a novel metabolic marker-the lysophosphatidylcholines (lysoPCs) to phosphatidylcholines (PCs) ratio-that was associated with advanced knee OA (P = 1.5 × 10(-7)) after adjustment for age, sex and BMI. When the subjects of the longitudinal cohort were categorized into two groups based on the optimal cut-off of the ratio of 0.09, we found the subjects with the ratio ⩾0.09 were 2.3 times more likely to undergo TKR than those with the ratio <0.09 during the 10-year follow-up (95% CI: 1.2, 4.3, P = 0.02).

CONCLUSION

We identified the ratio of lysoPCs to PCs as a novel metabolic marker for predicting advanced knee OA. Further studies are required to examine whether this ratio can predict early OA change.

Lipidomic analysis of plasma, erythrocytes and lipoprotein fractions of cardiovascular disease patients using UHPLC/MS, MALDI-MS and multivariate data analysis

Differences among lipidomic profiles of healthy volunteers, obese people and three groups of cardiovascular disease (CVD) patients are investigated with the goal to differentiate individual groups based on the multivariate data analysis (MDA) of lipidomic data from plasma, erythrocytes and lipoprotein fractions of more than 50 subjects. Hydrophilic interaction liquid chromatography on ultrahigh-performance liquid chromatography (HILIC-UHPLC) column coupled with electrospray ionization mass spectrometry (ESI-MS) is used for the quantitation of four classes of polar lipids (phosphatidylethanolamines, phosphatidylcholines, sphingomyelins and lysophosphatidylcholines), normal-phase UHPLC-atmospheric pressure chemical ionization MS (NP-UHPLC/APCI-MS) is applied for the quantitation of five classes of nonpolar lipids (cholesteryl esters, triacylglycerols, sterols, 1,3-diacylglycerols and 1,2-diacylglycerols) and the potential of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is tested for the fast screening of all lipids without a chromatographic separation. Obtained results are processed by unsupervised (principal component analysis) and supervised (orthogonal partial least squares) MDA approaches to highlight the largest differences among individual groups and to identify lipid molecules with the highest impact on the group differentiation.