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Phospholipids (PL) are major components of cellular membranes and changes in PL metabolism have been associated with the pathogenesis of numerous diseases. Lysophosphatidylcholine (LPC) in particular, is a comparably abundant component of oxidatively damaged tissues. LPC originates from the cleavage of phosphatidylcholine (PC) by phospholipase A 2 or the reaction of lipids with reactive oxygen species (ROS) such as HOCl. Another explanation of increased LPC concentration is the decreased re-acylation of LPC into PC. While there are also several other lysophospholipids, LPC is the most abundant lysophospholipid in mammals and will therefore be the focus of this review. LPC is involved in many physiological processes. It induces the migration of lymphocytes, fostering the production of pro-inflammatory compounds by inducing oxidative stress. LPC also "signals" via G protein-coupled and Toll-like receptors and has been implicated in the development of different diseases. However, LPCs are not purely "bad": this is reflected by the fact that the concentration and fatty acyl composition of LPC varies under different conditions, in plasma of healthy and diseased individuals, in tissues and different tumors. Targeting LPC and lipid metabolism and restoring homeostasis might be a potential therapeutic method for inflammation-related diseases., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The incidence of nonalcoholic fatty liver disease (NAFLD) has been steadily increasing in Western society in recent years and has been recognized as a risk factor for the development of hepatocellular carcinoma (HCC). However, the molecular mechanisms underlying the progression from NAFLD to HCC are still unclear, despite the use of suitable mouse models. To identify the transcriptional and lipid profiles of livers from mice with NAFLD-HCC, we induced both NAFLD and NAFLD-HCC pathologies in C57BL/6J mice and performed RNA-sequencing (RNA-seq) and targeted lipidomic analysis. Our RNA-seq analysis revealed that the transcriptional signature of NAFLD in mice is characterized by changes in inflammatory response and fatty acid metabolism. Moreover, the signature of NAFLD-HCC is characterized by processes typically observed in cancer, such as epithelial to mesenchymal transition, angiogenesis and inflammatory responses. Furthermore, we found that the diet used in this study inhibited cholesterol synthesis in both models. The analysis of lipid composition also showed a significant impact of the provided diet. Therefore, our study supports the idea that a Western diet (WD) affects metabolic processes and hepatic lipid composition. Additionally, the combination of a WD with the administration of a carcinogen drives the progression from NAFLD to HCC., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

The molecular mechanisms underlying the transition from nonalcoholic fatty liver disease (NAFLD) to hepatocellular carcinoma (HCC) are incompletely understood. During the development of NAFLD, Perilipin 5 (PLIN5) can regulate lipid metabolism by suppressing lipolysis and preventing lipotoxicity. Other reports suggest that the lack of PLIN5 decreases hepatic injury, indicating a protective role in NAFLD pathology. To better understand the role of PLIN5 in liver disease, we established mouse models of NAFLD and NAFLD-induced HCC, in which wild-type and Plin5 null mice were exposed to a single dose of acetone or 7,12-dimethylbenz[a]anthracene (DMBA) in acetone, followed by a 30-week high-fat diet supplemented with glucose/fructose. In the NAFLD model, RNA-seq revealed significant changes in genes related to lipid metabolism and immune response. At the intermediate level, pathways such as AMP-activated protein kinase (AMPK), signal transducer and activator of transcription 3 (STAT3), c-Jun N-terminal kinase (JNK), and protein kinase B (AKT) were blunted in Plin5-deficient mice (Plin5 -/- ) compared to wild-type mice (WT). In the NAFLD-HCC model, only WT mice developed liver tumors, while Plin5 -/- mice were resistant to tumorigenesis. Furthermore, only 32 differentially expressed genes associated with NALFD progession were identified in Plin5 null mice. The markers of mitochondrial function and immune response, such as the peroxisome proliferator-activated receptor-γ, coactivator 1-α (PGC-1α) and phosphorylated STAT3, were decreased. Lipidomic analysis revealed differential levels of some sphingomyelins between WT and Plin5 -/- mice. Interestingly, these changes were not detected in the HCC model, indicating a possible shift in the metabolism of sphingomelins during carcinogenesis., (© 2024. The Author(s).)

The occurrence of free fatty acids (FFAs) and the generation of reactive oxygen species (ROS) such as hydroxyl radicals (HO ● ) or hypochlorous acid (HOCl) is characteristic of inflammatory diseases, for instance, rheumatoid arthritis. Unsaturated fatty acids react with ROS yielding a variety of important products such as peroxides and chlorohydrins as primary and chain-shortened compounds (e.g., aldehydes and carboxylic acids) as secondary products. These modified fatty acids are either released from phospholipids by phospholipases or oxidatively modified subsequent to their release. There is increasing evidence that oligomeric products are also generated upon these processes. Fatty acid esters of hydroxy fatty acids (FAHFAs) are considered as very important products, but chlorinated compounds may be converted into dimeric and (with smaller yields) oligomeric products, as well. Our review is structured as follows: first, the different types of FFA oligomers known so far and the mechanisms of their putative generation are explained. Industrially relevant products as well as compounds generated from the frying of vegetable oils are also discussed. Second, the different opinions on whether dimeric fatty acids are considered as "friends" or "foes" are discussed., Competing Interests: The authors declare no conflict of interest.

The UDP-glucose receptor P2RY14, a rhodopsin-like G protein-coupled receptor (GPCR), was previously described as receptor expressed in A-intercalated cells of the mouse kidney. Additionally, we found P2RY14 is abundantly expressed in mouse renal collecting duct principal cells of the papilla and epithelial cells lining the renal papilla. To better understand its physiological function in kidney, we took advantage of a P2ry14 reporter and gene-deficient (KO) mouse strain. Morphometric studies showed that the receptor function contributes to kidney morphology. KO mice had a broader cortex relative to the total kidney area than wild-type (WT) mice. In contrast, the area of the outer stripe of the outer medulla was larger in WT compared to KO mice. Transcriptome comparison of the papilla region of WT and KO mice revealed differences in the gene expression of extracellular matrix proteins (e.g., decorin, fibulin-1, fibulin-7) and proteins involved in sphingolipid metabolism (e.g., small subunit b of the serine palmitoyltransferase) and other related GPCRs (e.g., GPR171). Using mass spectrometry, changes in the sphingolipid composition (e.g., chain length) were detected in the renal papilla of KO mice. At the functional level, we found that KO mice had a reduced urine volume but an unchanged glomerular filtration rate under normal chow and salt diets. Our study revealed P2ry14 as a functionally important GPCR in collecting duct principal cells and cells lining the renal papilla and the possible involvement of P2ry14 in nephroprotection by regulation of decorin., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Baalmann, Brendler, Butthof, Popkova, Engel, Schiller, Winter, Lede, Ricken, Schöneberg and Schulz.)

Transition metal carbides have numerous applications and are known to excel in terms of hardness, thermal stability and conductivity. In particular, the Pt-like behavior of Mo and W carbides has led to the popularization of metal carbides in catalysis, ranging from electrochemically-driven reactions to thermal methane coupling. Herein, we show the active participation of carbidic carbon in the formation of C 2 products during methane coupling at high temperature that is associated with the dynamics of Mo and W carbides. A detailed mechanistic study reveals that the catalyst performance of these metal carbides can be traced back to its carbon diffusivity and exchange capability upon interaction with methane (gas phase carbon). A stable C 2 selectivity over time on stream for Mo carbide (Mo 2 C) can be rationalized by fast carbon diffusion dynamics, while W carbide (WC) shows loss of selectivity due to slow diffusion leading to surface carbon depletion. This finding showcases that the bulk carbidic carbon of the catalyst plays a crucial role and that the metal carbide is not only responsible for methyl radical formation. Overall, this study evidences the presence of a carbon equivalent to the Mars-Van Krevelen type mechanism for non-oxidative coupling of methane., Competing Interests: The authors declare no competing interests., (This journal is © The Royal Society of Chemistry.)

Obesity and high abdominal fat mass are risk factors for developing the chronic inflammatory skin disease psoriasis. They are associated with increased incidence, prevalence and severity of the disease. A positive effect of weight loss on psoriasis activity has been shown in several studies. Obesity-related factors such as the dysregulation of glucose and lipid metabolism, the activation of adipose tissue and resultant persistent low-grade inflammation have been discussed as links of obesity and inflammatory diseases. Recently, we demonstrated a critical role of free fatty acids (FFAs) in obesity-mediated exacerbation of psoriatic skin inflammation in both mice and humans. In the present study, we translated these findings into a therapeutic intervention. An open-label study focusing on the dietary reduction of FFAs was conducted in patients with mild-to-moderate plaque psoriasis, and disease severity and serum markers of inflammation were analyzed. Here, we show that such a dietary intervention improves psoriatic disease activity independently of weight loss. Diet-related metabolic changes, such as a reduction in saturated free fatty acids (SFAs), may thus be more important than weight loss itself. Moreover, dietary intervention inhibited the overall pro-inflammatory activation status in patients, as shown by analysis of serum inflammatory parameters using the Olink platform. From our pilot study, we conclude that dietary intervention focusing on SFA reduction has the capacity to reduce disease activity and general inflammatory status in psoriasis patients.

Matrix-assisted laser desorption and ionization (MALDI) is a widely used soft-ionization technique of modern mass spectrometry (MS). MALDI enables the analysis of nearly all chemical compounds-including polar and apolar (phospho)lipids-with a minimum extent of fragmentation. MALDI has some particular advantages (such as the possibility to acquire spatially-resolved spectra) and is competitive with the simultaneously developed ESI (electrospray ionization) MS. Although there are still some methodological aspects that need to be elucidated in more detail, it is obvious that the careful selection of an appropriate matrix plays the most important role in (lipid) analysis. Some lipid classes can be detected exclusively if the optimum matrix is used, and the matrix determines the sensitivity by which a particular lipid is detected within a mixture. Since the matrix is, thus, crucial for optimum results, we provide here an update on the progress in the field since our original review in this journal in 2018. Thus, only the development during the last five years is considered, and lipids are sorted according to increasing complexity, starting with free fatty acids and ending with cardiolipins and phosphoinositides.

The nearly exclusive use of cryopreserved semen in cattle breeding enables long shipping distances, higher storage times, quarantine to avoid germ transmission and easy dispersal of high genetic value bulls. Spermatozoa from bulls are well freezable and improvement of cryopreservation protocols over decades has led to high semen quality. However, there is still some loss of spermatozoa in each semen dose due to detached acrosomes after thawing. There are even individual bulls with extremely high numbers of detached acrosomes after cryopreservation, called "bad freezers". This study screened 1092 ejaculates from 59 Holstein bulls for the difference in detached acrosomes before and after cryopreservation (ΔAC). The individual bull influenced ΔAC (P < 0.001) and allowed selection for individuals with repeatedly low ΔAC (good freezers) or high ΔAC (bad freezers). Good freezers were superior to bad freezers in a thermo-resistance test (78.2% vs. 33.6% total motility, respectively, P = 0.047) and had higher non-return rates (NRR: 46.8% vs. 40.8%, respectively, P = 0.016). Since oxidative stress is one possible explanation for premature acrosome reaction, the radical reduction capacity of the seminal fluid was measured, finding that this parameter was reduced in bad freezer bulls during cryopreservation (P = 0.043). Analysis of lipid species in sperm cells by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) showed a reduction of ether lipids and plasmalogens as well as an increase in formyl-lysophosphatidylcholines only within the bad freezers during cryopreservation (P = 0.043). In conclusion these findings show, that lipid alteration caused by oxidative stress is one essential reason for highly augmented acrosome reacted spermatozoa in bad freezer bulls. Therefore, increased use of antioxidants in the extender could be a possible starting point for developing individualized extenders for bad freezer bulls of high genetic value, in order to raise sperm quality after cryopreservation even in those bulls., (Copyright © 2022 Elsevier Inc. All rights reserved.)

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. 31 P 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 31 P 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., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Honeybees of the same colony combine a near-homogeneous genetic background with a high level of phenotypic plasticity, making them ideal models for functional lipidomics. The only external lipid source of the colony is pollen, a diet rich in polyunsaturated fatty acids (PUFA). It has been suggested that differences in exposure to pollen-derived PUFA could partly explain differences in longevity between honeybee castes. We here investigated whether the membrane composition of honeybees plays roles in the physiological adaptation to tasks of individuals within the colony. Membranes of cell heaters, a group of workers producing heat from their flight muscles to uphold brood nest temperature, were compared to those of different types of non-heaters. We found that the lipidomic profiles of these groups fall into clearly different "lipotypes", characterized by chain length and saturation of phospholipid-bound fatty acyl residues. The nutritional exposure to PUFA during early adult life and pupal development at the lower edge of the natural range of brood nest temperature both suppressed the expression of the cell heater-"lipotype". Because cardiolipins (CL) are the lipid class most clearly differentiating honeybee phenotypes, and CL plays central roles in mitochondrial function, dysfunction and aging, our findings could help to understand these processes in other animals and humans. Taken together, the lipidome analysis of different life stages of workers, fertile queens, and drones lead to the hypothesis that honeybee "lipotypes" might represent adaptations to different energetic profiles and the likelihood of exposure to low temperatures., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Palladium promotion and deposition on monoclinic zirconia are effective strategies to boost the performance of bulk In 2 O 3 in CO 2 -to-methanol and could unlock superior reactivity if well integrated into a single catalytic system. However, harnessing synergic effects of the individual components is crucial and very challenging as it requires precise control over their assembly. Herein, we present ternary Pd-In 2 O 3 -ZrO 2 catalysts prepared by flame spray pyrolysis (FSP) with remarkable methanol productivity and improved metal utilization, surpassing their binary counterparts. Unlike established impregnation and co-precipitation methods, FSP produces materials combining low-nuclearity palladium species associated with In 2 O 3 monolayers highly dispersed on the ZrO 2 carrier, whose surface partially transforms from a tetragonal into a monoclinic-like structure upon reaction. A pioneering protocol developed to quantify oxygen vacancies using in situ electron paramagnetic resonance spectroscopy reveals their enhanced generation because of this unique catalyst architecture, thereby rationalizing its high and sustained methanol productivity., (© 2022. The Author(s).)

Background: Human life without sperm is not possible. Therefore, it is alarming that the fertilizing ability of human spermatozoa is continuously decreasing. The reasons for that are widely unknown, but there is hope that metabolomics-based investigations may be able to contribute to overcoming this problem. This review summarizes the attempts made so far., Methods: We will discuss liquid chromatography-mass spectrometry (LC-MS), gas chromatography (GC), infrared (IR) and Raman as well as nuclear magnetic resonance (NMR) spectroscopy. Almost all available studies apply one of these methods., Results: Depending on the methodology used, different compounds can be detected, which is (in combination with sophisticated methods of bioinformatics) helpful to estimate the state of the sperm. Often, but not in all cases, there is a correlation with clinical parameters such as the sperm mobility., Conclusions: LC-MS detects the highest number of metabolites and can be considered as the method of choice. Unfortunately, the reproducibility of some studies is poor, and, thus, further improvements of the study designs are needed to overcome this problem. Additionally, a stronger focus on the biochemical consequences of the altered metabolite concentrations is also required.

Matrix-assisted laser desorption and ionization (MALDI) mass spectrometry (MS) is an indispensable tool in modern lipid research since it is fast, sensitive, tolerates sample impurities and provides spectra without major analyte fragmentation. We will discuss some methodological aspects, the related ion-forming processes and the MALDI MS characteristics of the different lipid classes (with the focus on glycerophospholipids) and the progress, which was achieved during the last ten years. Particular attention will be given to quantitative aspects of MALDI MS since this is widely considered as the most serious drawback of the method. Although the detailed role of the matrix is not yet completely understood, it will be explicitly shown that the careful choice of the matrix is crucial (besides the careful evaluation of the positive and negative ion mass spectra) in order to be able to detect all lipid classes of interest. Two developments will be highlighted: spatially resolved Imaging MS is nowadays well established and the distribution of lipids in tissues merits increasing interest because lipids are readily detectable and represent ubiquitous compounds. It will also be shown that a combination of MALDI MS with thin-layer chromatography (TLC) enables a fast spatially resolved screening of an entire TLC plate which makes the method competitive with LC/MS., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Tuberculosis (TB), which is caused by the bacterium Mycobacterium tuberculosis ( Mtb ), is still one of the deadliest infectious diseases. Understanding how the host and pathogen interact in active TB will have a significant impact on global TB control efforts. Exosomes are increasingly recognized as a means of cell-to-cell contact and exchange of soluble mediators. In the case of TB, exosomes are released from the bacillus and infected cells. In the present study, a comprehensive lipidomics and proteomics analysis of size exclusion chromatography-isolated plasma-derived exosomes from patients with TB lymphadenitis (TBL) and treated as well as untreated pulmonary TB (PTB) was performed to elucidate the possibility to utilize exosomes in diagnostics and knowledge building. According to our findings, exosome-derived lipids and proteins originate from both the host and Mtb in the plasma of active TB patients. Exosomes from all patients are mostly composed of sphingomyelins (SM), phosphatidylcholines, phosphatidylinositols, free fatty acids, triacylglycerols (TAG), and cholesterylesters. Relative proportions of, e.g., SMs and TAGs, vary depending on the disease or treatment state and could be linked to Mtb pathogenesis and dormancy. We identified three proteins of Mtb origin: DNA-directed RNA polymerase subunit beta (RpoC), Diacyglycerol O-acyltransferase (Rv2285), and Formate hydrogenase (HycE), the latter of which was discovered to be differently expressed in TBL patients. Furthermore, we discovered that Mtb infection alters the host protein composition of circulating exosomes, significantly affecting a total of 37 proteins. All TB patients had low levels of apolipoproteins, as well as the antibacterial proteins cathelicidin, Scavenger Receptor Cysteine Rich Family Member (SSC5D), and Ficolin 3 (FCN3). When compared to healthy controls, the protein profiles of PTB and TBL were substantially linked, with 14 proteins being co-regulated. However, adhesion proteins (integrins, Intercellular adhesion molecule 2 (ICAM2), CD151, Proteoglycan 4 (PRG4)) were shown to be more prevalent in PTB patients, while immunoglobulins, Complement component 1r (C1R), and Glutamate receptor-interacting protein 1 (GRIP1) were found to be more abundant in TBL patients, respectively. This study could confirm findings from previous reports and uncover novel molecular profiles not previously in focus of TB research. However, we applied a minimally invasive sampling and analysis of circulating exosomes in TB patients. Based on the findings given here, future studies into host-pathogen interactions could pave the way for the development of new vaccines and therapies.

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., Competing Interests: The authors have declared that no competing interests exist.

Rationale : In obesity the fine-tuned balance of macrophage phenotypes is disturbed towards a dominance of pro-inflammatory macrophages resulting in exacerbation and persistence of inflammation and impaired tissue repair. However, the underlying mechanisms are still poorly understood. Methods : Impact of obesity on macrophage differentiation was studied in high fat diet induced obese and db/db mice during skin inflammation and wound repair, respectively. Mechanisms of S100A9-mediated effects on macrophage differentiation was studied on in vitro generated macrophages by genomic and proteomic approaches. The role of S100A9 on macrophage differentiation was investigated by pharmacological inhibition of S100A9 during skin inflammation and wound repair in obese and db/db mice. Results : We demonstrate an overexpression of S100A9 in conditions of obesity-associated disturbed macrophage differentiation in the skin. We show that saturated free fatty acids (SFA), which are increased in obesity, together with S100A9 induce TLR4 and inflammasome-dependent IL-1β release in macrophages which in turn amplifies S100A9 expression initiating a vicious cycle of sustained S100A9 overexpression in skin inflammation in obesity. We reveal a yet unrecognized impact of obesity-associated S100A9 overexpression on macrophage differentiation. S100A9 binding to TLR4 and activation of NFkB attenuates development of M2-like macrophages and induces pro-inflammatory functions in these cells. Consequently, inhibition of S100A9 restores disturbed M2-like macrophage differentiation in mouse models of obesity-associated skin inflammation and wound repair. Similarly, breaking the vicious cycle of S100A9 overexpression by dietary reduction of SFA restored M2-like macrophage activation. Improvement of skin inflammation and wound repair upon reduction of S100A9 by pharmacological inhibition or by reduction of SFA uncovers the pathogenic role of S100A9 overexpression in obesity. Conclusion : This study identifies S100A9 as a previously unrecognized vital component in obesity-associated disturbed macrophage differentiation and subsequent impaired regulation of inflammation and wound repair. The findings open new opportunities for therapeutic implications for inflammatory diseases and wound repair in obesity., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Currently, spermiogram analysis is the most relevant method used to clarify the potential infertility of a couple. However, in some cases, the reasons for infertility remain obscure. Smoking is among the factors that have been described to adversely affect male fertility. Smoking increases oxidative stress and thus promotes various pathological processes. Comparative studies, particularly those on metabolomic changes in sperm and seminal plasma caused by smoking, have not yet been published. Thus, the present pilot study aimed at the mass spectrometric characterization of the metabolomes of specimens from both smoking and nonsmoking subjects and the comparison of the evaluated data in terms of sperm apoptosis and spermiogram parameters. The results provided evidence that the conventional spermiogram is not altered in smokers compared to nonsmokers. However, a more careful investigation of sperm cells by metabolomic profiling reveals profound effects of smoking on sperm: first, nitrogen oxide synthase, a marker of oxidative stress, is activated. Second, the uptake of fatty acids into sperm mitochondria is reduced, leading to an impaired energy supply. Third, phenylalanine hydroxylation and tryptophan degradation, which are both indications of altered tetrahydrobiopterin biosynthesis, are reduced. Moreover, flow cytometry approaches indicated increased sperm caspase-3 activity, a sign of apoptosis. The present study clearly shows the negative effects of smoking on semen quality. Especially for idiopathic cases, metabolomic profiling can help to shed light on male subfertility or infertility., (© The Author(s) 2021. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Mass spectrometry has emerged as an extremely powerful analytical tool, which is widely used in many fields. This broad application range became possible with the invention of MALDI and ESI as "soft ionization" techniques that keep fragmentation of the analyte to a minimum. However, when these techniques are applied to mixture analysis, less-sensitively detectable compounds may be suppressed by more sensitively detectable compounds, a process called "ion suppression". Thus, previous separation of the mixture into the individual lipid classes is necessary to be able to detect all compounds. This review summarizes the current knowledge in the field of combined TLC/MS and discusses the most important strengths and weaknesses of the different MS (particularly ionization) techniques with respect to phospholipids. This comprises techniques such as MALDI and ESI, but less established approaches such as plasma desorption will be also discussed., (Copyright © 2021 Elsevier B.V. All rights reserved.)

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 A 2 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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Engel, Schiller, Galuska and Fuchs.)

The fungus growing termite species Macrotermes bellicosus ( M. bellicosus ) is used in nutrition and traditional medicine in the Republic of Benin for the treatment of infectious and inflammatory diseases. Previous findings demonstrated evidence of anti-inflammatory and spasmolytic properties of M. bellicosus . The aim of the present study was to evaluate the antimicrobial potential of different extracts of M. bellicosus samples and determine the chemical profile of an ethanolic M. bellicosus extract. Chemical profiling was conducted using centrifugal partition chromatography and 13 C-NMR, followed by MALDI-TOF MS. Major identified compounds include hydroquinone (HQ), methylhydroquinone (MHQ), 3,4-dihydroxyphenethyl glycol (DHPG), N -acetyldopamine (NADA) and niacinamide. The fatty acid mixture of the extract was mainly composed of linoleic and oleic acid and highlights the nutritional purpose of M. bellicosus . Using the Kirby-Bauer disc diffusion and broth microdilution assay, an antibacterial activity of M. bellicosus samples was observed against various clinical strains with a highest growth inhibition of S. aureus . In addition, HQ and MHQ as well as fractions containing DHPG, niacinamide and NADA inhibited S. aureus growth. The reported antimicrobial activity of M. bellicosus and identified active substances provide a rationale for the traditional medicinal use of M. bellicosus .

Rationale: Glycolipids play important roles in many physiological processes - despite their commonly low abundance. This study summarizes selected data on the (glyco)lipid composition of sperm from different fish species., Methods: Lipid extraction of fish sperm was performed according to the procedure by Bligh and Dyer. The lipid composition of the organic extracts was analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and electrospray ionization ion trap (ESI-IT)MS coupled to high-performance thin-layer chromatography (HPTLC)., Results: It was shown that sperm from carp, northern pike, rainbow trout and burbot contain high amounts of neutral and acidic glycosphingolipids as well as sulfoglycolipids. These particular lipids are presumably involved in reproduction requirements., Conclusions: Phospholipids and glycolipids in crude lipid extracts can be analyzed in parallel by MS coupled to TLC. The direct application of tandem mass spectrometry (MS/MS) helps to elucidate the glycolipid structure. Thus, compositional analysis can be performed very rapidly., (© 2020 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd.)

Nonalcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver diseases with an increasing prevalence due to rising rates of obesity, metabolic syndrome and type II diabetes. Untreated NAFLD may progress to steatohepatitis (NASH) and ultimately liver cirrhosis. NAFLD is characterized by lipid accumulation, and when sufficient excess lipids are obtained, irreversible liver injury may follow. Perilipin 5 (PLIN5), a known lipid droplet coating protein and triglyceride metabolism regulator, is highly expressed in oxidatively modified tissues but it is still unclear how it affects NAFLD/NASH progress. We here studied how PLIN5 affects NAFLD development induced by a 30-week high-fat diet (HFD) administration in wild type and PLIN5 knock out ( Plin5 -/- ) mice. The disruption of PLIN5 induced differences in lipid metabolism during HFD feeding and was associated with reduced hepatic fat accumulation. Surprisingly, Plin5 -/- mice showed mitigated activation of the NLR family pyrin domain-containing 3 (NLRP3) inflammasome, leading to minor hepatic damage. We conclude that PLIN5 is a pleiotropic regulator of hepatic homeostasis in NASH development. Targeting the PLIN5 expression appears critical for protecting the liver from inflammatory activation during chronic NAFLD.

Populations of industrialized countries have registered a dramatically increasing prevalence in obesity for many years. Despite continuous research, mechanisms involved in the storage and utilization of chemical energy in adipocytes are still under investigation. Adipocytes have the task to store excessive energy in the form of triacylglycerols (TG) and it is already well-known that the fatty acyl composition of TG is largely determined by the composition of the diet. In contrast to TG, the composition of adipocyte phospholipids was less comprehensively investigated. In this study, the compositions of the most abundant phospholipid classes of 3T3-L1 undifferentiated (preadipocytes) and differentiated cells (adipocytes) were determined. The lipid fractions were isolated by normal phase high-performance thin-layer chromatography and subsequently analyzed by electrospray ionization mass spectrometry. Additionally, the fatty acyl (FA) compositions were determined by gas chromatography. The positions of the FA residues were additionally confirmed by phospholipase A 2 digestion. The advantages and disadvantages of the different analytical approaches will be discussed. It will be shown that undifferentiated 3T3-L1 and mature adipocytes differ extremely regarding their compositions. This goes along with an increase in odd-chain fatty acids. Graphical abstract.

The lipid composition of sperm membranes is crucial for fertilization and differs among species. As the evolution of internal fertilization modes in fishes is not understood, a comparative study of the sperm lipid composition in freshwater representatives of externally and internally fertilizing fishes is needed for a better understanding of taxa-specific relationships between the lipid composition of the sperm membrane and the sperm physiology. The lipidomes of spermatozoa from stingray, a representative of cartilaginous fishes possessing internal fertilization, and sterlet, a representative of chondrostean fishes with external fertilization, have been studied by means of nuclear magnetic resonance (NMR), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), electrospray MS, gas chromatography-(GC) MS, and thin-layer chromatography (TLC). NMR experiments revealed higher cholesterol content and the presence of phosphatidylserine in stingray compared to sterlet sperm. Unknown MS signals could be assigned to different glycosphingolipids in sterlet (neutral glycosphingolipid Gal-Cer(d18:1/16:0)) and stingray (acidic glycosphingolipid sulpho-Gal-Cer(d18:1/16:0)). Free fatty acids in sterlet sperm indicate internal energy storage. GC-MS experiments indicated a significant amount of adrenic acid, but only a low amount of docosahexaenoic acid in stingray sperm. In a nutshell, this study provides novel data on sperm lipid composition for freshwater stingray and sterlet possessing different modes of fertilization., Competing Interests: The authors declare no conflict of interest.

The spawning behavior of different fish species is as diverse as their habitats. A lot of factors influence the (phospho)lipid composition of fish sperm, including the water temperature at which spawning takes place. Therefore, this study aimed on the elucidation of the phospholipid composition of sperm from three fish species from different orders (common carp - Cyprinus carpio, northern pike - Esox lucius and burbot - Lota lota) with different spawning temperatures by nuclear magnetic resonance spectroscopy (NMR), matrix-assisted laser desorption/ionization mass spectrometry and thin-layer chromatography (TLC) coupled to electrospray ionization mass spectrometry as well as gas chromatography. Next to the lipid composition that was different for carp, northern pike and burbot, regarding the moieties of the different (phospho)lipid classes (particularly sphingomyelin and acidic phospholipids) and the saturation degree of the fatty acyl residues, there were differences observed depending on the analytical method that was used. The results from TLC and NMR investigations differed regarding the amounts of the different phospholipids. Reasons for these discrepancies are discussed in detail., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Rationale: Normal-phase thin-layer chromatography (NP-TLC) is an established method for the separation of all major phospholipid classes according to the different polarities of the head groups. In contrast, reversed-phase (RP)-TLC is much less frequently used for this purpose. This study aimed to compare the NP and the RP approach regarding their separation potential of phospholipid oxidation products., Methods: Commercially available 1-palmitoyl-2-oleoyl-sn-phosphatidylcholine (POPC) (PC 16:0/18:1) and 1-palmitoyl-2-linoleoyl-sn-phosphatidylcholine (PLPC) (PC 16:0/18:2) were oxidized by NaMnO 4 . Oxidation products were subsequently separated by NP- and RP-TLC and analyzed by electrospray ionization mass spectrometry., Results: In comparison with NP-TLC, RP-TLC was clearly superior regarding the separation of oxidation products of phospholipids. RP-TLC enabled the separation not only of primary oxidation products of POPC such as alcohols and ketones but also of secondary oxidation products. Furthermore some oxidation products, such as aldehydes, were only detectable by ESI after RP-TLC but not after NP-TLC., Conclusions: RP-TLC is the method of choice to characterize oxidized PL such as oxidized phosphatidylcholines., (© 2018 John Wiley & Sons, Ltd.)

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., Competing Interests: The authors have declared that no competing interests exist.

Next to clinical investigations, the evaluation of male fertility relies mainly on detailed sperm analyses, for example, cell counting, motility, cell morphology and vitality testing. The manual creation of a spermiogram is time- and material-consuming. Therefore, reliable high-throughput systems that may be substituted for manual methods are urgently needed. The present study aimed to compare conventional sperm analysis performed as per WHO 5th guidelines and semen analysis performed with the SQA Vision ® machine. SQA Vision ® is a commercial device for automated sperm analysis. Data obtained independently by both methods were compared by statistical analyses using Bland-Altman plots and Passing-Bablok regression analyses. The analyses revealed that the results for sperm concentration and total motility were comparable. The agreement for progressive motility was poor, and there were clear deviations in the determination of normal sperm morphology. Passing-Bablok regression analyses and the consideration of the 95% confidence intervals pointed out systematic and proportional differences between the manual semen analysis and the automated approach., (© 2018 Blackwell Verlag GmbH.)

Biochemical properties of polyunsaturated fatty acids (PUFAs) are fundamental to sperm movements. Amongst all adjustments operated during epididymal maturation, sperm membrane lipid composition is remodelled. Specifically, the proportion of PUFAs usually increases from the caput towards the cauda epididymidis. In mammals, PUFAs are predominantly acquired through the diet, which can consequently impact male fertility. We aimed at analysing to what extent n-6 and n-3 PUFAs are incorporated into sperm in the Seba's short-tailed bat (Carollia perspicillata), and at demonstrating the effect of the sperm fatty acid composition on sperm mobility. We therefore provided food varying in fatty acid composition to males of C. perspicillata and measured the fatty acid composition and mobility traits in spermatozoa collected from the caput and cauda epididymides. We found that n-6 and n-3 PUFAs and saturated fatty acids were significantly related to sperm velocity but not to the proportion of progressive sperm (i.e. motility). Concomitant to an increase in sperm velocity, the level of fatty acid saturation increased from the caput to the cauda epididymidis, while the proportion of PUFAs remained similar along the epididymis. A reduction in n-6 PUFAs counterbalanced an increase in n-3 PUFAs. The food treatments did not affect the sperm fatty acid composition. Our results suggest that a precise endogenous control rather than dietary effects determines sperm fatty acid composition in C. perspicillata.

Matrix-assisted laser desorption/ionization (MALDI) is one of the most successful "soft" ionization methods in the field of mass spectrometry and enables the analysis of a broad range of molecules, including lipids. Although the details of the ionization process are still unknown, the importance of the matrix is commonly accepted. Both, the development of and the search for useful matrices was, and still is, an empirical process, since properties like vacuum stability, high absorption at the laser wavelength, etc. have to be fulfilled by a compound to become a useful matrix. This review provides a survey of successfully used MALDI matrices for the lipid analyses of complex biological samples. The advantages and drawbacks of the established organic matrix molecules (cinnamic or benzoic acid derivatives), liquid crystalline matrices, and mixtures of common matrices will be discussed. Furthermore, we will deal with nanocrystalline matrices, which are most suitable to analyze small molecules, such as free fatty acids. It will be shown that the analysis of mixtures and the quantitative analysis of small molecules can be easily performed if the matrix is carefully selected. Finally, some basic principles of how useful matrix compounds can be "designed" de novo will be introduced.

Introduction: Mass spectrometry imaging (MSI) techniques are nowadays widely used to obtain spatially resolved metabolite information from biological tissues. Since (phospho)lipids occur in all animal tissues and are very sensitively detectable, they are often in the focus of such studies. This particularly applies for phosphatidylcholines (PC) which are very sensitively detectable as positive ions due to the permanent positive charge of their choline headgroup. Areas covered: After a short introduction of lipid species occurring in biological systems and approaches normally used to obtain spatially resolved mass spectra (with the focus on matrix-assisted laser desorption/ionization coupled to time-of-flight (MALDI-TOF) MSI) a survey will be given which diseases have so far been characterized by changes of the PC composition. Expert commentary: Since PC species are very sensitively detectable by MS, sensitivity is not a major issue. However, spatial resolution is still limited and cellular dimensions can be hardly resolved by MALDI-TOF MSI, which is a critical point of the available approaches. Due to lacks of reproducibility and standardization further development is required.

To study apoptosis as a functional pathway in mature spermatozoa and apoptosis correlated to the acrosome reaction via the intracellular calcium concentration, semen samples from 27 healthy human donors were treated with inducers of apoptosis (betulinic acid, thapsigargin), inducers of the acrosome reaction (thapsigargin, calcium ionophore) or hydrogen peroxide to produce reactive oxygen species with and without prior incubation with a calcium chelator. Computer-assisted sperm analysis, flow cytometry, and transmission electron microscopy were performed to analyze changes in the acrosomal status and in apoptotic features. Betulinic acid, thapsigargin, and the calcium ionophore treatment resulted in an increased number of sperm cells with caspase 9 and caspase 3 activation, disrupted mitochondrial membrane potential, and a reacted acrosome. Sperm motility was decreased in all cases. Transmission electron analyses showed ultra-morphological changes, such as membrane integrity, membrane blebbing, the formation of head vacuoles, defects of the nuclear envelope, nuclear fragmentation, and the acrosome reaction. Acrosome reaction and apoptotic features decreased due to the reduction in intracellular calcium by the calcium chelator NP-EGTA, AM. Therefore, apoptotic cell death in acrosome-reacted sperm cells mediated by high intracellular calcium levels is possible., (© 2018 American Society of Andrology and European Academy of Andrology.)

Cryopreservation of kangaroo sperm has not been successful so far, and yet there is no promising cryopreservation protocol for these cells available. However, conservation of gametes is extremely important, particularly in the context of preserving endangered species. As spermatozoa are comprised of different membrane systems, the composition of these membranes might account for difficulties in cryopreservation. Lipids, as the main components, affect the physical properties of biological membranes and play a major role in sperm maturation. Therefore, knowledge of the lipid composition is crucial for any further step toward the preservation of the species. We used MALDI-TOF, ESI-IT, tandem mass spectrometry, and thin layer chromatography to investigate the lipid composition of epididymal spermatozoa of four different kangaroo species. Spectra of these species were very similar with respect to the identified lipid species. Tremendous changes in the lipid composition during the transit of sperm from caput to cauda epididymis could be seen, specifically an increase in poly-unsaturated fatty acids, ether lipids, and plasmalogens, as well as a reduction in mono- and di-unsaturated fatty acids. Additionally, phosphatidylcholines containing docosatrienoic acid (22:3), a heretofore unknown fatty acid for sperm membranes, showed the highest abundance in kangaroo sperm.

Oxidized (phospho)lipids are of paramount interest for different reasons: besides their in vivo relevance as markers of inflammatory diseases, they are often needed in the laboratory to study the response of selected cells to oxidized lipids. Mass spectrometry (MS) is nowadays one of the most powerful methods to identify lipid oxidation products. Although MALDI and ESI MS are both widely used, it is so far not clear whether all potential phospholipid oxidation products can be detected by both methods This aspect will be studied here using NaMnO 4 -oxidized phosphatidylcholine 16:0/18:1 and 16:0/18:2 as simple, but reliable model systems. We will show that chain-shortened products such as aldehydes and carboxylic acids (generated by cleavage at the double bond position) can be easily detected by both ionization methods: without the need of any derivatization. However, primary oxidation products such as hydroperoxides can be predominantly detected by ESI MS while MALDI-TOF MS detects secondary oxidation products derived thereof more sensitively. Potential reasons for these differences will be discussed and put in the context of biological mixture analysis., (Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.)

Background: The glyoxalase (GLO)1 is part of a ubiquitous detoxification system in the glycolytic pathway of normal and tumor cells. It protects against cellular damage caused by cytotoxic metabolites., Methods: Aiming at exploring the role of GLO1 in prostate cancer, we evaluated and targeted the expression of GLO1 in prostate cancer tissues and cell lines and analyzed its correlation with grading systems and tumor growth indices., Results: Immunohistochemical studies on 37 prostate cancer specimens revealed a positive correlation between Helpap-grading and the cytoplasmic (P = 0.002)/nuclear (P = 0.006) GLO1 level. A positive correlation between Ki-67 proliferation marker and the cytoplasmic GLO1 (P = 0.006) was evident. Furthermore, the highest GLO1 level was detected in the androgen-sensitive LNCaP compared to the androgen-independent Du-145 and PC-3 prostate cell lines and the breast cancer cell MCF-7, both at protein and mRNA level. Treating cancer cells with ethyl pyruvate was found to defang some malignancy-associated properties of cancer cells including proliferation, invasion and anchorage-independent growth. In vitro results revealed that the potency of ethyl pyruvate is increased when cells are metabolically activated by growth stimulators, for example, by fetal calf serum, dihydrotestosterone, tumor growth factor-β1 and leptin., Conclusions: The positive correlation of GLO1 expression level in prostate cancer tissues with the pathological grade and proliferation rate may assign GLO1 as a risk factor for prostate cancer development and progression. Furthermore, our data indicate that inhibitors of GLO1 might be useful to decelerate the cancer cell growth by a novel therapeutic approach that we may call "induced metabolic catastrophe.", (© 2013 Wiley Periodicals, Inc.)

The X-chromosomal GPR34 gene encodes an orphan G(i) protein-coupled receptor that is highly conserved among vertebrates. To evaluate the physiological relevance of GPR34, we generated a GPR34-deficient mouse line. GPR34-deficient mice were vital, reproduced normally, and showed no gross abnormalities in anatomical, histological, laboratory chemistry, or behavioral investigations under standard housing. Because GPR34 is highly expressed in mononuclear cells of the immune system, mice were specifically tested for altered functions of these cell types. Following immunization with methylated BSA, the number of granulocytes and macrophages in spleens was significantly lower in GPR34-deficient mice as in wild-type mice. GPR34-deficient mice showed significantly increased paw swelling in the delayed type hypersensitivity test and higher pathogen burden in extrapulmonary tissues after pulmonary infection with Cryptococcus neoformans compared with wild-type mice. The findings in delayed type hypersensitivity and infection tests were accompanied by significantly different basal and stimulated TNF-α, GM-CSF, and IFN-γ levels in GPR34-deficient animals. Our data point toward a functional role of GPR34 in the cellular response to immunological challenges.

G protein-coupled receptors (GPCR) are involved in the regulation of numerous physiological functions. Therefore, GPCR variants may have conferred important selective advantages during periods of human evolution. Indeed, several genomic loci with signatures of recent selection in humans contain GPCR genes among them the X-chromosomally located gene for GPR82. This gene encodes a so-called orphan GPCR with unknown function. To address the functional relevance of GPR82 gene-deficient mice were characterized. GPR82-deficient mice were viable, reproduced normally, and showed no gross anatomical abnormalities. However, GPR82-deficient mice have a reduced body weight and body fat content associated with a lower food intake. Moreover, GPR82-deficient mice showed decreased serum triacylglyceride levels, increased insulin sensitivity and glucose tolerance, most pronounced under Western diet. Because there were no differences in respiratory and metabolic rates between wild-type and GPR82-deficient mice our data suggest that GPR82 function influences food intake and, therefore, energy and body weight balance. GPR82 may represent a thrifty gene most probably representing an advantage during human expansion into new environments., (© 2011 Engel et al.)

Activated macrophages have been characterized as M1 and M2 according to their inflammatory response pattern. Here we analyzed the M2 marker expression and intracellular signal transduction in the course of cytokine-driven differentiation. We found elevated spontaneous production of the chemokines CCL17, CCL18 and CCL22 and increased expression of CD206 by alveolar macrophages from patients with lung fibrosis. Stimulation of normal human AM with Th2 cytokines IL-4 and/or IL-10 in vitro revealed IL-4 as the most powerful inducer of M2-phenotype in AM and monocytes. Importantly, IL-10 enhanced IL-4-induced expression of CCL18 and IL-1RA in a synergistic fashion. IL-4/IL-10 stimulation induces a strong activation of STAT3 in AM from fibrosis patients. These results suggest an important role for M2 polarized AM in the pathogenesis of pulmonary fibrosis and indicate that both IL-4 and IL-10 account for human AM phenotype shift to M2, as seen in patients with fibrotic interstitial lung diseases., (Copyright © 2010 Elsevier Inc. All rights reserved.)