Ether Lipids Research Articles

Ether lipids and a peroxisomal riddle in sperm.

Sperm are terminally differentiated cells that lack most of the membranous organelles, resulting in a high abundance of ether glycerolipids found across different species. Ether lipids include plasmalogens, platelet activating factor, GPI-anchors and seminolipid. These lipids play important roles in sperm function and performance, and thus are of special interest as potential fertility markers and therapeutic targets. In the present article, we first review the existing knowledge on the relevance of the different types of ether lipids for sperm production, maturation and function. To further understand ether-lipid metabolism in sperm, we then query available proteomic data from highly purified sperm, and produce a map of metabolic steps retained in these cells. Our analysis pinpoints the presence of a truncated ether lipid biosynthetic pathway that would be competent for the production of precursors through the initial peroxisomal core steps, but devoid of subsequent microsomal enzymes responsible for the final synthesis of all complex ether-lipids. Despite the widely accepted notion that sperm lack peroxisomes, the thorough analysis of published data conducted herein identifies nearly 70% of all known peroxisomal resident proteins as part of the sperm proteome. In view of this, we highlight open questions related to lipid metabolism and possible peroxisomal functions in sperm. We propose a repurposed role for the truncated peroxisomal ether-lipid pathway in detoxification of products from oxidative stress, which is known to critically influence sperm function. The likely presence of a peroxisomal-derived remnant compartment that could act as a sink for toxic fatty alcohols and fatty aldehydes generated by mitochondrial activity is discussed. With this perspective, our review provides a comprehensive metabolic map associated with ether-lipids and peroxisomal-related functions in sperm and offers new insights into potentially relevant antioxidant mechanisms that warrant further research.

Phase behavior and structure of a biocompatible microemulsion based on Tween 20, 2-ethylhexylglycerine and isopropyl palmitate in water

Microemulsions are thermodynamically stable mixtures of water and oil. For many applications, such as in cosmetics, it is important that the components are biocompatible. For the formulation of a new biocompatible microemulsion based on Tween 20 (Tw20) surfactant, the glycerol ether 2-ethylhexylglycerin (EHG) is employed as an alternative to commonly used short- to medium chain alcohols as cosurfactant. Tw20 itself is not capable of any significant solubilization but the addition of EHG allows to enhance the solubilization capacity for the polar oil isopropyl palmitate (IPP) largely. At a Tw20 to EHG molar ratio of 1:12, i.e., very large excess of cosurfactant, the solubilization capacity is increased by nearly three orders of magnitude compared to a pure Tw20 solution. The resulting oil-in-water (O/W) microemulsion is studied using static and dynamic light scattering (SLS/DLS) and small-angle neutron scattering (SANS). The SANS spectra are analyzed with a core–shell ellipsoid model, which indicates formation of oblate droplets at higher EHG content. Dynamic light scattering experiments confirm the presence of microemulsion droplets with hydrodynamic radii increasing from 3.8 to 19.8 nm upon addition of cosurfactant. In summary, this study shows that EHG is a cosurfactant that enhances the solubilization properties of a biocompatible surfactant largely and thereby renders it very useful for formulations.

Comprehensive Screening for EPA/DHA-Structured Phospholipids in Aquatic Products by a Specific Precursor Ion Scanning-Based HILIC-MS/MS Method

Comprehensive screening for functional substances from natural resources is always a hot research topic. Eicosapentaenoic acid- (EPA) and docosahexaenoic acid (DHA)-structured phospholipids (PLEPA/DHA) have versatile cardiovascular benefits as well as superior bioavailability. Herein, the abundance of PLEPA/DHA in 16 aquatic products was specifically and selectively screened using a recently developed precursor ion scan-driven hydrophilic interaction chromatography-mass spectrometry (PreIS-HILIC/MS) method with the fatty acyl moieties of EPA (m/z 301.6) and DHA (m/z 327.6) locked. The aim focused on the characteristics and differences in the varieties and contents of EPA/DHA-structured phosphatidylcholine (PCEPA/DHA) and EPA/DHA-structured phosphatidylethanolamine (PEEPA/DHA) molecular species. A total of 80 PLEPA/DHA molecules were identified in these natural sources, including 47 PCEPA/DHA and 33 PEEPA/DHA. After analysis, PC 16:0/20:5 and PC 16:0/22:6 are present in all aquatic products and at high levels. Antarctic krill was found to be the best resource of PLEPA/DHA in total (2574.69 μg·g-1), followed by mackerel (2330.11 μg·g-1), salmon (2109.91 μg·g-1), and Farrer's scallop (1883.59 μg·g-1), while abalone contained the lowest level of PLEPA/DHA (310.44 μg·g-1). Besides, sea cucumber and sea bass contained the highest contents of EPA-structured and DHA-structured ether phospholipids, respectively, which could be highly recommended as dietary sources of special functional phospholipids. Finally, the multiple discrepancies between the 16 aquatic products were revealed by multivariate statistical analysis. These findings improve the awareness of the composition and content of PLEPA/DHA contained in aquatic products, providing a reference for their integrated development.

Development of a toughened and antibacterial Poly(lactide acid) (PLA) with preserved strength by elemental sulfur-based bio-renewable dynamically crosslinked elastomers

The toughening of PLA is usually realized by blending with elastomers or plasticizers, but often conflicted with lowered mechanical strength and complicated preparation steps. In the current study, inverse vulcanization was used to synthesize a series of dynamically cross-linked polysulfide (SOA) elastomers based on refining by-product elemental sulfur, soybean oil (SO) and allyl glyceryl ether (AGE), which provides dynamically reversible S-S bonds, flexible triglyceride segments and reactive epoxy functions.Melt blended with PLA, the SOAs exhibit great toughening effects and produce droplet-matrix typed blends with good interfacial compatibilization verified by rheology. SOA composition was decisive in dictating toughening efficiency. A high AGE content induces self-polymerization of epoxy groups, resulting in dominance of permanent crosslinking in SOA, giving rise to rigid SOA particles with bad processability and dispersity in PLA, hence poor toughener cavitations under external forces with unsatisfying toughening effect. A high sulfur and low AGE content results in dominance of dynamic crosslinking, providing soft SOA particles in favor of processing and dispersion in PLA matrix with small domains and thin ligament thickness, thus favoring internal cavitation of SOA particles to achieve good toughness. However, the presence of unreacted sulfur with a too high sulfur content can mitigate the toughening effect. In particular, a highly toughened blend with optimized SOA composition (PLA-S50O25A25) was obtained with excellent toughness (elongation at break 235.7% and tensile toughness 76.5 MJ/m3) balanced by only slightly impaired strength (tensile strength 50–60 MPa and modulus ∼ 900 Mpa). Moreover, the PLA-SOA exhibits excellent broad-spectrum anti-bacterial effects. This study reported the unprecedented use of fully sustainable dynamically-crosslinked elastomers as tougheners of PLA, paving new ways for PLA modification with balanced stiffness-toughness and antibacterial activity.

Lipid droplets and peroxisomes are co-regulated to drive lifespan extension in response to mono-unsaturated fatty acids

Dietary mono-unsaturated fatty acids (MUFAs) are linked to longevity in several species. But the mechanisms by which MUFAs extend lifespan remain unclear. Here we show that an organelle network involving lipid droplets and peroxisomes is critical for MUFA-induced longevity in Caenorhabditis elegans. MUFAs upregulate the number of lipid droplets in fat storage tissues. Increased lipid droplet number is necessary for MUFA-induced longevity and predicts remaining lifespan. Lipidomics datasets reveal that MUFAs also modify the ratio of membrane lipids and ether lipids—a signature associated with decreased lipid oxidation. In agreement with this, MUFAs decrease lipid oxidation in middle-aged individuals. Intriguingly, MUFAs upregulate not only lipid droplet number but also peroxisome number. A targeted screen identifies genes involved in the co-regulation of lipid droplets and peroxisomes, and reveals that induction of both organelles is optimal for longevity. Our study uncovers an organelle network involved in lipid homeostasis and lifespan regulation, opening new avenues for interventions to delay aging.

A BRAF mutation-associated gene risk model for predicting the prognosis of melanoma

BRAF mutation plays an important role in the pathogenesis and progression of melanoma and is correlated to the prognosis of melanoma patients. However, fewer studies have attempted to develop a BRAF mutation-associated gene risk model for predicting the prognosis of melanoma. The current research explores BRAF mutation-related biological features in melanoma and establishes a prognostic signature. First, we identified three significantly enriched KEGG pathways (glycosphingolipid biosynthesis - ganglio series, ether lipid metabolism, and glycosaminoglycan biosynthesis - keratan sulfate) and corresponding genes in the BRAF mutant group by gene set enrichment analysis. We then developed a prognostic signature based on 7 BRAF-associated genes (PLA2G2D, FUT8, PLA2G4E, PLA2G5, PLA2G1B, B3GNT2, and ST3GAL5) and assessed its prediction accuracy using ROC curve analysis. Finally, the nomogram was established according to the prognostic signature and independent clinical characteristics to predict the survival of melanoma patients. Furthermore, we found higher proportions of naive B cells, plasma cells, CD8 T cells, CD4 memory-activated T cells, and regulatory T cells in the low-risk group. Whereas lower proportions of M0, M1, and M2 macrophages and resting NK cells were observed in the high-risk group. The analysis also showed a significantly higher expression of immune checkpoint molecules (PD-1, PD-L1, CTLA4, BTLA, CD28, CD80, CD86, HAVCR2, ICOS, LAG3, and TIGIT) in the low-risk group. Our results provide novel insights into the effect of BRAF mutation on melanoma growth and indicate a promising direction toward immunotherapy and precision medicine in melanoma patients.

A platelet lipidomics signature in patients with COVID-19

Ischemic cardiovascular and venous thromboembolic events are a frequent cause of death in severe COVID-19 patients. Platelet activation plays a key role in these complications, however platelet lipidomics have not been studied yet. The aim of our pilot investigation was to perform a preliminary study of platelet lipidomics in COVID-19 patients compared to healthy subjects. Lipid extraction and identification of ultrapurified platelets from eight hospitalized COVID-19 patients and eight age- and sex-matched healthy controls showed a lipidomic pattern almost completely separating COVID-19 patients from healthy controls. In particular, a significant decrease of ether phospholipids and increased levels of ganglioside GM3 were observed in platelets from COVID-19 patients. In conclusion, our study shows for the first time that platelets from COVID-19 patients display a different lipidomics signature distinguishing them from healthy controls, and suggests that altered platelet lipid metabolism may play a role in viral spreading and in the thrombotic complications of COVID-19.

Platelet-activating factor receptor in GtoPdb v.2023.1

Platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is an ether phospholipid mediator associated with platelet coagulation, but also subserves inflammatory roles. The PAF receptor (provisional nomenclature recommended by NC-IUPHAR [38]) is activated by PAF and other suggested endogenous ligands are oxidized phosphatidylcholine [74] and lysophosphatidylcholine [98]. It may also be activated by bacterial lipopolysaccharide [91].

Response of microbial community to climate change in Liaohe Delta since the Last Glacial Maximum

Estuarine delta is a critical zone for a series of biogeochemical processes including greenhouse gas emissions, organic matter transport and burial. These processes are mainly mediated by microbial activities such as heterotroph, methanogenesis, and methanotroph. However, response of microbial activities in the delta to paleoenvironmental change is less constrained. In this study, we analyzed the concentrations and compositions of microbial ether lipids (branched GDGTs and isoprenoid GDGTs) in a core from the Liaohe Delta, the northeast China, to explore the response of bacteria and archaea communities to climate change since 32 ka BP. During the glacial periods, the concentrations of branched GDGTs and isoprenoid GDGTs were low possibly due to the low temperature inhibiting the growth of microorganisms. After the Last Glacial Maximum (LGM), the abundance of GDGT concentrations increased, and reached the maximum during the Bølling/Allerød (B/A) period, then decreased during the Younger Dryas (YD) and increased again during the early Holocene. This pattern indicated that the abundance of the microorganisms in the Liaohe Delta was mainly controlled by temperature since 32 ka BP. In addition to temperature, sea level fluctuation and local hydrological disturbance may also effect microbial growth in the Liaohe Delta. Significant increase in the ratio of GDGT-0 versus crenarchaeol (R0/5) indicates that the rise of lake level provided a favorable anaerobic environment for methanogen blooming during the B/A and the early Holocene. Low lake level and strong water mixing made oxygen content increase, thus inhibited methanogen growth and further led to the decrease of the R0/5 values in the YD, suggesting that methanogenesis in global estuaries may impact atmospheric methane content. Our results provide a means to interpret response of microbial abundance and biogeochemical processes to paleoclimate change since the Last Glacial Maximum in estuarine delta.

Ether phospholipids are required for mitochondrial reactive oxygen species homeostasis

Mitochondria are hubs where bioenergetics, redox homeostasis, and anabolic metabolism pathways integrate through a tightly coordinated flux of metabolites. The contributions of mitochondrial metabolism to tumor growth and therapy resistance are evident, but drugs targeting mitochondrial metabolism have repeatedly failed in the clinic. Our study in pancreatic ductal adenocarcinoma (PDAC) finds that cellular and mitochondrial lipid composition influence cancer cell sensitivity to pharmacological inhibition of electron transport chain complex I. Profiling of patient-derived PDAC models revealed that monounsaturated fatty acids (MUFAs) and MUFA-linked ether phospholipids play a critical role in maintaining ROS homeostasis. We show that ether phospholipids support mitochondrial supercomplex assembly and ROS production; accordingly, blocking de novo ether phospholipid biosynthesis sensitized PDAC cells to complex I inhibition by inducing mitochondrial ROS and lipid peroxidation. These data identify ether phospholipids as a regulator of mitochondrial redox control that contributes to the sensitivity of PDAC cells to complex I inhibition.

Smartwater Synergy with Chemical EOR: Studying the Potential Synergy with Surfactants

Summary The potential synergy between smartwater and various enhanced oil recovery (EOR) processes has recently attracted significant attention. In previous work, we demonstrated such favorable synergy for polymer floods not only from a viscosity standpoint but also in terms of wettability. Recent studies suggest that smartwater synergy might even extend to surfactant floods. In this work, we investigate the potential synergy between smartwater and surfactant flooding. Opposed to previous work, the potential synergy is investigated from ground zero. We concurrently developed two surfactant formulations for conventional high-salinity injection water and low-salinity smartwater. To design the optimal surfactant-polymer (SP) formulations, we followed a systematic all-inclusive laboratory workflow. Oil displacement studies were performed in preserved core samples using the two developed formulations with conventional injection water and smartwater. The results demonstrated the promising potential of binary surfactant mixtures of olefin sulfonate (OS) and alkyl glyceryl ether sulfonate (AGES) for both waters. The designed binary formulations were able to form Winsor Type III emulsions besides achieving ultralow interfacial tensions (IFTs). Most importantly, in terms of oil displacement, the developed SP formulations in both injection water and low-salinity smartwater were capable of recovering more than 60% of the remaining oil post waterflooding. A key novelty of this work is that it investigates the potential synergy between smartwater and surfactant-based processes from the initial step of surfactant formulation design. Through well-designed from-scratch evaluation, we demonstrate that surfactant-based processes exhibit limited synergies with smartwater. Comparable processes in terms of performance can be designed for both high-salinity and low-salinity waters. It is also quite possible that the synergistic benefits of smartwater on oil recovery cannot be effective in SP flooding processes, especially with specific surfactant formulations under optimal salinity conditions.

Tert-Butyl Ethers of Renewable Diols as Oxygenated Additives for Motor Gasoline. Part I: Glycerol and Propylene Glycol Ethers

The study investigates tert-butoxy alkanols (otherwise defined as polyol tert-butyl ethers) that have vicinal tert-butoxy and hydroxy groups in their molecules from the perspective of their usability as oxygenated additives for motor gasoline. A series of propylene glycol mono-tert-butyl ether (PTBE) and glycerol di-tert-butyl ether (di-GTBE) samples were prepared: PTBE by direct acid-catalytic alkylation of diols with tert-butanol, and di-GTBE by alkylation of epichlorohydrin. Adding PTBE and di-GTBE to base motor gasoline was found to improve its antiknock performance: the average blending research octane number to blending motor octane number ratios (bRON/bMON) equaled 120/111 and 124/104 for PTBE and di-GTBE, respectively. Furthermore, the effects of the ether additives on the properties of ethanol-blended base gasoline were characterized. Finally, the study describes the effect of polyol tert-butyl ether additives on the cloud point depression of ethanol-blended gasoline (low-temperature phase stabilization) and demonstrates a positive synergistic effect of adding the ethers mixed with ethanol

COVID-19, Blood Lipid Changes, and Thrombosis

Although there is increasing evidence that oxidative stress and inflammation induced by COVID-19 may contribute to increased risk and severity of thromboses, the underlying mechanism(s) remain to be understood. The purpose of this review is to highlight the role of blood lipids in association with thrombosis events observed in COVID-19 patients. Among different types of phospholipases A2 that target cell membrane phospholipids, there is increasing focus on the inflammatory secretory phospholipase A2 IIA (sPLA2-IIA), which is associated with the severity of COVID-19. Analysis indicates increased sPLA2-IIA levels together with eicosanoids in the sera of COVID patients. sPLA2 could metabolise phospholipids in platelets, erythrocytes, and endothelial cells to produce arachidonic acid (ARA) and lysophospholipids. Arachidonic acid in platelets is metabolised to prostaglandin H2 and thromboxane A2, known for their pro-coagulation and vasoconstrictive properties. Lysophospholipids, such as lysophosphatidylcholine, could be metabolised by autotaxin (ATX) and further converted to lysophosphatidic acid (LPA). Increased ATX has been found in the serum of patients with COVID-19, and LPA has recently been found to induce NETosis, a clotting mechanism triggered by the release of extracellular fibres from neutrophils and a key feature of the COVID-19 hypercoagulable state. PLA2 could also catalyse the formation of platelet activating factor (PAF) from membrane ether phospholipids. Many of the above lipid mediators are increased in the blood of patients with COVID-19. Together, findings from analyses of blood lipids in COVID-19 patients suggest an important role for metabolites of sPLA2-IIA in COVID-19-associated coagulopathy (CAC).

Development of novel dimethyl ether – Glycerol blends with improved viscosity and miscibility for potential compression-ignition engine application

Dimethyl Ether is a promising diesel alternative fuel due to its significantly low well-to-wheels greenhouse gas emissions from certain renewable pathways and soot-free combustion characteristic. However, in a compression-ignition engine, the fuel injection system exhibits decreased durability due to the dimethyl ether’s extremely low viscosity (i.e., 0.15 cSt @ 40 °C). In this study, the viscosity of dimethyl ether is improved to the level of No.2 diesel fuel (i.e., 1.9 cSt @ 40 °C) via glycerol blending. To prevent the phase separation between glycerol and dimethyl ether, effective co-solvents are determined based on different selection criteria: Hansen Solubility Parameter-based “averaged solubility distance”, viscosity, oxygen mass content, health and environmental impacts, and renewable production capability. As a result, propylene glycol and di-propylene glycol are selected as the final co-solvents and are used to form the two final dimethyl ether blends: i) Michigan DME blend I (i.e., dimethyl ether/dipropylene glycol/glycerol); and ii) Michigan DME blend II (i.e., dimethyl ether/propylene glycol/glycerol). The minimum mass ratio of co-solvent to glycerol to prevent the phase separation is measured to be 1.5 and 1.65 for Michigan DME blend I and II, respectively, at 40 wt% dimethyl ether content. The kinematic viscosity of the two final blends was successfully improved to the level of No. 2 diesel fuel at around 40–43 wt% dimethyl ether content, a higher dimethyl ether content than any previous blends reported. A preliminary engine demonstration result with one of the final dimethyl ether blends (i.e., Michigan DME blend I) is also briefly presented here with suggestions for future improvement. While the current article covers the blend development part of the current research, its companion article covers the life-cycle greenhouse gas emissions assessment for one of the final dimethyl ether blends (i.e., Michigan DME blend II).

Monitoring of age- and gender-related alterations of endocannabinoid levels in selected brain regions with the use of SPME probes

IntroductionThe endocannabinoid system consists of different types of receptors, enzymes and endocannabinoids (ECs), which are involved in several physiological processes, but also play important role in the development and progression of central nervous system disorders.ObjectivesThe purpose of this study was to apply precise and sensitive methodology for monitoring of four ECs, namely anandamide (AEA), 2-arachidonoyl glycerol (2-AG), N-arachidonoyl dopamine (NADA), 2-arachidonyl glyceryl ether (2-AGe) in selected brain regions of female and male rats at different stages of development (young, adult and old).MethodsBiocompatible solid-phase microextraction (SPME) probes were introduced into the intact (non-homogenized) brain structures for isolation of four ECs, and the extracts were subjected to LC–MS/MS analysis. Two chemometric approaches, namely hierarchical cluster analysis (HCA) and Principal Component Analysis (PCA) were applied to provide more information about the levels of 2-AG and AEA in different brain structures.Results2-AG and AEA were extracted and could be quantified in each brain region; the level of 2-AG was significantly higher in comparison to the level of AEA. Two highly unstable ECs, NADA and 2-AGe, were captured by SPME probes from intact brain samples for the first time.ConclusionSPME probes were able to isolate highly unstable endogenous compounds from intact tissue, and provided new tools for precise analysis of the level and distribution of ECs in different brain regions. Monitoring of ECs in brain samples is important not only in physiological conditions, but also may contribute to better understanding of the functioning of the endocannabinoid system in various disorders.

Disrupted intercellular bridges and spermatogenesis in fatty acyl-CoA reductase 1 knockout mice: A new model ofether lipid deficiency.

Peroxisomal fatty acyl-CoA reductase 1 (FAR1) is a rate-limiting enzyme for ether lipid (EL) synthesis. Gene mutations in FAR1 cause a rare human disease. Furthermore, altered EL homeostasis has also been associated with various prevalent human diseases. Despite their importance in human health, the exact cellular functions of FAR1 and EL are not well-understood. Here, we report the generation and initial characterization of the first Far1 knockout (KO) mouse model. Far1 KO mice were subviable and displayed growth retardation. The adult KO male mice had smaller testes and were infertile. H&E and immunofluorescent staining showed fewer germ cells in seminiferous tubules. Round spermatids were present but no elongated spermatids or spermatozoa were observed, suggesting a spermatogenesis arrest at this stage. Large multi-nucleated giant cells (MGC) were found lining the lumen of seminiferous tubules with many of them undergoing apoptosis. The immunofluorescent signal of TEX14, an essential component of intercellular bridges (ICB) between developing germ cells, was greatly reduced and mislocalized in KO testis, suggesting the disrupted ICBs as an underlying cause of MGC formation. Integrative analysis of our total testis RNA-sequencing results and published single-cell RNA-sequencing data unveiled cell type-specific molecular alterations underlying the spermatogenesis arrest. Many genes essential for late germ cell development showed dramatic downregulation, whereas genes essential for extracellular matrix dynamics and cell-cell interactions were among the most upregulated genes. Together, this work identified the cell type-specific requirement of ELs in spermatogenesis and suggested a critical role of Far1/ELs in the formation/maintenance of ICB during meiosis.

1-O-Octadecyl-2-O-benzyl-sn-glyceryl-3-phospho-GS-441524 (V2043). Evaluation of Oral V2043 in a Mouse Model of SARS-CoV-2 Infection and Synthesis and Antiviral Evaluation of Additional Phospholipid Esters with Enhanced Anti-SARS-CoV-2 Activity.

Early antiviral treatments, including intravenous remdesivir (RDV), reduce hospitalization and severe disease caused by COVID-19. An orally bioavailable RDV analog may facilitate earlier treatment of non-hospitalized COVID-19 patients. Here we describe the synthesis and evaluation of alkyl glyceryl ether phosphodiesters of GS-441524 (RVn), lysophospholipid analogs which allow for oral bioavailability and stability in plasma. Oral treatment of SARS-CoV-2-infected BALB/c mice with 1-O-octadecyl-2-O-benzyl-sn-glyceryl-3-phospho-RVn (60 mg/kg orally, once daily for 5 days starting 12h after infection) reduced lung viral load by 1.5log10 units versus vehicle at day 2 and to below the limit of detection at day 5. Structure/activity evaluation of additional analogs that have hydrophobic ethers at the sn-2 of glycerol revealed improved in vitro antiviral activity by introduction of a 3-fluoro-4-methoxy-substituted benzyl or a 3- or 4-cyano-substituted benzyl. Collectively, our data support the development of RVn phospholipid prodrugs as oral antiviral agents for prevention and treatment of SARS-CoV-2 infections.

Toxic effects of Tripterygium glycoside tablets on the reproductive system of male rats by metabolomics, cytotoxicity, and molecular docking

BackgroundTripterygium glycoside tablets (TGT) is the most common preparation from Tripterygium wilfordii Hook F, which is widely used in clinical for treating rheumatoid arthritis (RA) and other autoimmune diseases. However, its serious reproductive toxicity limits its application. PurposeThis study aimed to elucidate the toxic effects of TGT on the reproductive system of male RA rats and its potential toxic components and mechanism. MethodsCollagen-induced arthritis (CIA) rat model was established, and TGT suspension was given at low, medium, and high doses. Gonadal index, pathological changes, and the number of spermatogenic cells were used to evaluate the toxic effects of TGT on the reproductive system. Non-targeted metabolomics of testicular tissue was conducted by UHPLC-QTOF/MS. Combined with network toxicology, the key targets of TGT-induced reproductive toxicity were screened and RT-qPCR was used to validation. In vitro toxicity of 19 components of TGT was evaluated using TM3 and TM4 cell lines. Molecular docking was used to predict the interaction between toxic components and key targets. ResultsTGT reduced testicular and epididymis weight. Pathology analysis showed a lot of deformed and atrophic spermatogenic tubules. The number of spermatogenic cells decreased significantly (P<0.0001). A total of 58 different metabolites including platelet-activating factor (PAF), lysophosphatidylcholine (Lyso PC), phosphatidylinositol (PI), glutathione (GSH), and adenosine monophosphate (AMP) were identified by testicular metabolomics. Glycerophospholipid metabolism, ether lipid metabolism, and glutathione metabolism were key pathways responsible for the reproductive toxicity of TGT. Ten key reproductive toxicity targets were screened by network toxicology. The cytotoxicity test showed that triptolide, triptonide, celastrol, and demethylzeylasteral could significantly reduce the viability of TM3 and TM4 cells. Alkaloids had no apparent toxic effects. Molecular docking showed that the four toxic components had a good affinity with 10 key targets. All binding energies were less than -7 kcal/mol. The RT-qPCR results showed the Cyp19a1 level was significantly up-regulated. Pik3ca and Pik3cg levels were significantly down-regulated. ConclusionThrough testicular metabolomics, we found that TGT may cause reproductive toxicity through CYP19A1, PIK3CA, and PIK3CG three target, which was preliminarily revealed. This study laid the foundation for elucidating the toxicity mechanism of TGT and evaluating its safety and quality.

Abstract 1683: Ether phospholipids metabolism is a latent vulnerability for pancreatic cancer resistance

Abstract Mitochondria are hubs where bioenergetics, redox homeostasis, and anabolic metabolism pathways integrate through a tightly coordinated flux of metabolites. The essential contributions of mitochondrial metabolism to fuel tumor growth and resistance to therapy are now evident in multiple contexts. However, targeting of mitochondrial metabolism in the clinical setting has repeatedly failed, owing to a narrow therapeutic window and the remarkable ability of tumor cells to activate compensatory metabolic programs. Thus, it is essential to uncover additional mechanisms that may render cancer cells selectively susceptible to treatment and those that enable them to survive when exposed to mitochondrial metabolism-targeted drugs. Here, using pancreatic ductal adenocarcinoma (PDAC) as a disease model, we report that cellular and, in particular, mitochondrial lipid composition affects the sensitivity of cancer cells to pharmacological inhibition of electron transport chain complex I. Metabolomic, including lipidomic, analyses of patient-derived PDAC models uncovered a critical role for monounsaturated fatty acids (MUFAs) and demonstrated that MUFA-linked ether phospholipids have a critical role to sustain homeostasis of mitochondrial reactive oxygen species (ROS). Blocking de novo ether phospholipid biosynthesis in the peroxisomes, sensitized PDAC cells to mitochondrial complex I inhibition by inducing mitochondrial ROS and lipid peroxidation. Biochemical analysis revealed a role of ether phospholipids in the assembly of mitochondrial supercomplexes and ROS production. Together, our data identify an ether phospholipid-dependent mechanism that regulates mitochondrial redox control and contributes to the sensitivity of PDAC cells to complex I inhibition. These findings might lead to novel approaches to target mitochondrial metabolism in cancer cells. Citation Format: Ziheng Chen, I-Lin Ho, Melinda Soeung, Er-Yen Yen, Johnathon Rose, Sanjana Srinivasan, Angela Deem, Sisi Gao, Haoqiang Ying, Giulio Draetta. Ether phospholipids metabolism is a latent vulnerability for pancreatic cancer resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1683.

Temperature responsive crosslinked starch-kraft lignin macromolecule

Starch is a natural polymer with a relatively simple structure and limited solubility in water. Kraft lignin (KL) is a complex biopolymer obtained as a by-product from the delignification of wood and grasses. The present work reports developing a temperature-responsive high molecular weight macromolecule from crosslinking KL and starch (KLS). The NMR and XPS analyses quantified the changes in the aromatic and anhydroglucose units of KL and starch, observing a higher content of C-O-C bonds, which confirms the presence of glycerol ether cross-linkages between starch and KL in KLS. The rheological analysis of KLS dispersions revealed the formation of a thermo-responsive structured network. The temperature-dependent water solubility and rheological characteristics of KLS were related to the presence of hydrophilic starch chains, crosslinking degree, and physicochemical characteristics of KL. The incorporation of KL and ether crosslinks increased the thermal stability of KLS. Because of its multiple functional groups and large molecular weight (3.6–4.2 × 105 g/mol) that was arranged in an extended globular shape, KLS-5 formed a gel-like structure after a heating-cooling treatment. Overall, the results confirmed that incorporating lignin in starch would fabricate sustainable materials with potentially altered applications, such as temperature-responsive hydrogels and films.