Sphingosine in apoptosis signaling

Unveiling enigmatic essence of Sphingolipids: A promising avenue for glaucoma treatment

Treatment of glaucoma, the leading cause of irreversible blindness, remains challenging. The apoptotic loss of retinal ganglion cells (RGCs) in glaucoma is the pathological hallmark. Current treatments often remain suboptimal as they aim to halt RGC loss secondary to reduction of intraocular pressure. The pathophysiological targets for exploring direct neuroprotective approaches, therefore are highly relevant. Sphingolipids have emerged as significant target molecules as they are not only the structural components of various cell constituents, but they also serve as signaling molecules that regulate molecular pathways involved in cell survival and death. Investigations have shown that a critical balance among various sphingolipid species, particularly the ceramide and sphingosine-1-phosphate play a role in deciding the fate of the cell. In this review we briefly discuss the metabolic interconversion of sphingolipid species to get an insight into "sphingolipid rheostat", the dynamic balance among metabolites. Further we highlight the role of sphingolipids in the key pathophysiological mechanisms that lead to glaucomatous loss of RGCs. Lastly, we summarize the potential drug candidates that have been investigated for their neuroprotective effects in glaucoma via their effects on sphingolipid axis.

Alzheimer's disease manifests abnormal sphingolipid metabolism

Introduction

Alzheimer's disease (AD) is associated with disturbed metabolism, prompting investigations into specific metabolic pathways that may contribute to its pathogenesis and pathology. Sphingolipids have garnered attention due to their known physiological impact on various diseases.

Methods

We conducted comprehensive profiling of sphingolipids to understand their possible role in AD. Sphingolipid levels were measured in AD brains, Cerad score B brains, and controls, as well as in induced pluripotent stem (iPS) cells (AD, PS, and control), using liquid chromatography mass spectrometry.

Results

AD brains exhibited higher levels of sphingosine (Sph), total ceramide 1-phosphate (Cer1P), and total ceramide (Cer) compared to control and Cerad-B brains. Deoxy-ceramide (Deoxy-Cer) was elevated in Cerad-B and AD brains compared to controls, with increased sphingomyelin (SM) levels exclusively in Cerad-B brains. Analysis of cell lysates revealed elevated dihydroceramide (dhSph), total Cer1P, and total SM in AD and PS cells versus controls. Multivariate analysis highlighted the relevance of Sph, Cer, Cer1P, and SM in AD pathology. Machine learning identified Sph, Cer, and Cer1P as key contributors to AD.

Discussion

Our findings suggest the potential importance of Sph, Cer1P, Cer, and SM in the context of AD pathology. This underscores the significance of sphingolipid metabolism in understanding and potentially targeting mechanisms underlying AD.

Alterations in Proteostasis Mechanisms in Niemann-Pick Type C Disease

Niemann-Pick Type C (NPC) represents an autosomal recessive disorder with an incidence rate of 1 in 150,000 live births, classified within lysosomal storage diseases (LSDs). The abnormal accumulation of unesterified cholesterol characterizes the pathophysiology of NPC. This phenomenon is not unique to NPC, as analogous accumulations have also been observed in Alzheimer's disease, Parkinson's disease, and other neurodegenerative disorders. Interestingly, disturbances in the folding of the mutant protein NPC1 I1061T are accompanied by the aggregation of proteins such as hyperphosphorylated tau, α-synuclein, TDP-43, and β-amyloid peptide. These accumulations suggest potential disruptions in proteostasis, a regulatory process encompassing four principal mechanisms: synthesis, folding, maintenance of folding, and protein degradation. The dysregulation of these processes leads to excessive accumulation of abnormal proteins that impair cell function and trigger cytotoxicity. This comprehensive review delineates reported alterations across proteostasis mechanisms in NPC, encompassing changes in processes from synthesis to degradation. Additionally, it discusses therapeutic interventions targeting pharmacological facets of proteostasis in NPC. Noteworthy among these interventions is valproic acid, a histone deacetylase inhibitor (HDACi) that modulates acetylation during NPC1 synthesis. In addition, various therapeutic options addressing protein folding modulation, such as abiraterone acetate, DHBP, calnexin, and arimoclomol, are examined. Additionally, treatments impeding NPC1 degradation, exemplified by bortezomib and MG132, are explored as potential strategies. This review consolidates current knowledge on proteostasis dysregulation in NPC and underscores the therapeutic landscape targeting diverse facets of this intricate process.

Trifunctional Sphinganine: A New Tool to Dissect Sphingolipid Function

Functions and cell biology of the sphingolipids sphingosine and sphinganine in cells are not well understood. While some signaling roles for sphingosine have been elucidated, the closely related sphinganine has been described only insofar as it does not elicit many of the same signaling responses. Here, we prepared multifunctionalized derivatives of the two lipid species that differ only in a single double bond of the carbon backbone. Using these novel probes, we were able to define their spatiotemporal distributions within cells. Furthermore, we used these tools to systematically map the protein interactomes of both lipids. The lipid-protein conjugates, prepared through photo-crosslinking in live cells and extraction via click chemistry to azide beads, revealed significant differences in the captured proteins, highlighting their distinct roles in various cellular processes. This work elucidates mechanistic differences between these critical lipids and sets the foundation for further studies of the cellular functions of sphingosine and sphinganine.

Assessing Metabolic Differences Associated with Exposure to Polybrominated Biphenyl and Polychlorinated Biphenyls in the Michigan PBB Registry

BACKGROUND

Polybrominated biphenyls (PBB) and polychlorinated biphenyls (PCB) are persistent organic pollutants with potential endocrine-disrupting effects linked to adverse health outcomes.

OBJECTIVES

In this study, we utilize high-resolution metabolomics (HRM) to identify internal exposure and biological responses underlying PCB and multigenerational PBB exposure for participants enrolled in the Michigan PBB Registry.

METHODS

HRM profiling was conducted on plasma samples collected from 2013 to 2014 from a subset of participants enrolled in the Michigan PBB Registry, including 369 directly exposed individuals (F0) who were alive when PBB mixtures were accidentally introduced into the food chain and 129 participants exposed to PBB in utero or through breastfeeding, if applicable (F1). Metabolome-wide association studies were performed for PBB-153 separately for each generation and Σ PCB (PCB-118, PCB-138, PCB-153, and PCB-180) in the two generations combined, as both had direct PCB exposure. Metabolite and metabolic pathway alterations were evaluated following a well-established untargeted HRM workflow.

RESULTS

Mean levels were 1.75  ng / mL [standard deviation (SD): 13.9] for PBB-153 and 1.04  ng / mL (SD: 0.788) for Σ PCB . Sixty-two and 26 metabolic features were significantly associated with PBB-153 in F0 and F1 [false discovery rate (FDR) p < 0.2 ], respectively. There were 2,861 features associated with Σ PCB (FDR p < 0.2 ). Metabolic pathway enrichment analysis using a bioinformatics tool revealed perturbations associated with Σ PCB in numerous oxidative stress and inflammation pathways (e.g., carnitine shuttle, glycosphingolipid, and vitamin B9 metabolism). Metabolic perturbations associated with PBB-153 in F0 were related to oxidative stress (e.g., pentose phosphate and vitamin C metabolism) and in F1 were related to energy production (e.g., pyrimidine, amino sugars, and lysine metabolism). Using authentic chemical standards, we confirmed the chemical identity of 29 metabolites associated with Σ PCB levels (level 1 evidence).

CONCLUSIONS

Our results demonstrate that serum PBB-153 is associated with alterations in inflammation and oxidative stress-related pathways, which differed when stratified by generation. We also found that Σ PCB was associated with the downregulation of important neurotransmitters, serotonin, and 4-aminobutanoate. These findings provide novel insights for future investigations of molecular mechanisms underlying PBB and PCB exposure on health. https://doi.org/10.1289/EHP12657.

Clethra fimbriata hexanic extract triggers alteration in the energy metabolism in epimastigotes of Trypanosoma cruzi

Chagas disease (ChD), caused by Trypanosoma cruzi, is endemic in American countries and an estimated 8 million people worldwide are chronically infected. Currently, only two drugs are available for therapeutic use against T. cruzi and their use is controversial due to several disadvantages associated with side effects and low compliance with treatment. Therefore, there is a need to search for new tripanocidal agents. Natural products have been considered a potential innovative source of effective and selective agents for drug development to treat T. cruzi infection. Recently, our research group showed that hexanic extract from Clethra fimbriata (CFHEX) exhibits anti-parasitic activity against all stages of T. cruzi parasite, being apoptosis the main cell death mechanism in both epimastigotes and trypomastigotes stages. With the aim of deepening the understanding of the mechanisms of death induced by CFHEX, the metabolic alterations elicited after treatment using a multiplatform metabolomics analysis (RP/HILIC-LC-QTOF-MS and GC-QTOF-MS) were performed. A total of 154 altered compounds were found significant in the treated parasites corresponding to amino acids (Arginine, threonine, cysteine, methionine, glycine, valine, proline, isoleucine, alanine, leucine, glutamic acid, and serine), fatty acids (stearic acid), glycerophospholipids (phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine), sulfur compounds (trypanothione) and carboxylic acids (pyruvate and phosphoenolpyruvate). The most affected metabolic pathways were mainly related to energy metabolism, which was found to be decrease during the evaluated treatment time. Further, exogenous compounds of the triterpene type (betulinic, ursolic and pomolic acid) previously described in C. fimbriata were found inside the treated parasites. Our findings suggest that triterpene-type compounds may contribute to the activity of CFHEX by altering essential processes in the parasite.

Sphingolipids: From structural components to signaling hubs

In late November 2019, Prof. Lina M. Obeid passed away from cancer, a disease she spent her life researching and studying its intricate molecular underpinnings. Along with her husband, Prof. Yusuf A. Hannun, Obeid laid down the foundations of sphingolipid biochemistry and oversaw its remarkable evolution over the years. Lipids are a class of macromolecules that are primarily associated with cellular architecture. In fact, lipids constitute the perimeter of the cell in such a way that without them, there cannot be cells. Hence, much of the early research on lipids identified the function of this class of biological molecules as merely structural. Nevertheless, unlike proteins, carbohydrates, and nucleic acids, lipids are elaborately diverse as they are not made up of monomers in polymeric forms. This diversity in structure is clearly mirrored by functional pleiotropy. In this chapter, we focus on a major subset of lipids, sphingolipids, and explore their historic rise from merely inert structural components of plasma membranes to lively and necessary signaling molecules that transmit various signals and control many cellular processes. We will emphasize the works of Lina Obeid since she was an integral pillar of the sphingolipid research world.

Metabolomic analysis of follicular fluid from women with Hashimoto thyroiditis

Hashimoto thyroiditis is an autoimmune disease characterized by hypothyroidism and a high level of anti-thyroid autoantibodies. It has shown to negatively impact female fertility; however, the mechanisms are unclear. Ovarian follicular fluid appears to be the key to understanding how Hashimoto thyroiditis affecst fertility. Thus, we aimed to evaluated the metabolic profile of follicular fluid and antithyroid autoantibody levels in the context of Hashimoto thyroiditis. We collected follicular fluid from 61 patients, namely 38 women with thyroid autoantibody positivity and 23 women as negative controls, undergoing in vitro fertilization treatment. Follicular fluid samples were analyzed using metabolomics, and thyroid autoantibodies were measured. Fifteen metabolites with higher concentrations in the follicular fluid samples from Hashimoto thyroiditis were identified, comprising five possible affected pathways: the glycerophospholipid, arachidonic acid, linoleic acid, alpha-linolenic acid, and sphingolipid metabolism pathways. These pathways are known to regulate ovarian functions. In addition, antithyroglobulin antibody concentrations in both serum and follicular fluid were more than tenfold higher in women with Hashimoto thyroiditis than in controls. Our data showed that the metabolic profile of follicular fluid is altered in women with Hashimoto thyroiditis, suggesting a potential mechanistic explanation for the association of this disease with female infertility.

Promoting liver cancer cell apoptosis effect of Tribulus terrestris L. via reducing sphingosine level was confirmed by network pharmacology with metabolomics

Background

Tribulus terrestris L. (TT) is one of the most common Chinese herbs and distributes in various regions in China. TT was first documented to treat breast cancer in Shen-Nong-Ben-Cao-Jing. However, the pharmacological activities of TT extract on liver cancer have not been reported. In this study, we investigated its anti-liver cancer activity and underlying mechanism.

Methods

Traditional Chinese Medicine Systems Pharmacology (TCMSP) and PharmMapper databases were used to obtain the active ingredients and the targets of TT. Genecards database was employed to acquire TT targets in liver cancer. Furthermore, Venny 2.1, Cytoscape 3.8.2, DAVID 6.8 software were utilized to analyze the relationship between TT and liver cancer. In vivo experiment: The animal model of liver cancer was established by injection of H22 cells into Balb/c mice. After five days, drugs were intragastrically administered to the mice daily for 10 days. Body weight, tumor size and tumor weight were recorded. Tumor inhibitory rate was calculated. Protein levels were examined by Western blotting. Pathological changes of liver cancer tissues were evaluated by HE and Tunel staining. Metabolomics study: LC-MS was used to analyze different metabolites between model and TTM groups.

Results

12 active ingredients of TT, 127 targets of active ingredients, 17,378 targets of liver cancer, and 125 overlapping genes were obtained. And then, 118 items of GO biological processes (BP), 54 items of GO molecular function (MF), 35 items of GO cellular component (CC) and 128 pathways of KEGG were gotten (P < 0.05). Moreover, 47 differential metabolites were affirmed and 66 pathways of KEGG (P < 0.05) were obtained. In addition, after TT and sorafenib treatment, tumor size was markedly reduced, respectively, compared with model group. Tumor weight was significantly decreased and tumor inhibitory rate was more than 44% in TTM group. After TT treatment, many adipocytes, cracks between tumor cells and apoptosis were found. The levels of pro-Cathepsin B, Cathepsin B, Bax, Bax/Bcl2, Caspase3 and Caspase7 were markedly increased, but the level of Bcl2 was significantly reduced after TT treatment.

Conclusion

TT has a broad range of effects on various signaling pathways and biological processes, including the regulation of apoptosis. It exhibits antitumor activity in an animal model of liver cancer and activates the apoptotic pathway by decreasing Sph level. This study provides valuable information regarding the potential use of TT extract in the treatment of liver cancer and highlights the importance of investigating the underlying molecular mechanisms of traditional medicines for the development of new therapeutic drugs in liver cancer.

Phase I study of opaganib, an oral sphingosine kinase 2-specific inhibitor, in relapsed and/or refractory multiple myeloma

Multiple myeloma (MM) remains an incurable disease and there is an unmet medical need for novel therapeutic drugs that do not share similar mechanisms of action with currently available agents. Sphingosine kinase 2 (SK2) is an innovative molecular target for anticancer therapy. We previously reported that treatment with SK2 inhibitor opaganib inhibited myeloma tumor growth in vitro and in vivo in a mouse xenograft model. In the current study, we performed a phase I study of opaganib in patients with relapsed/refractory multiple myeloma (RRMM). Thirteen patients with RRMM previously treated with immunomodulatory agents and proteasome inhibitors were enrolled and treated with single-agent opaganib at three oral dosing regimens (250 mg BID, 500 mg BID, or 750 mg BID, 28 days as a cycle). Safety and maximal tolerated dose (MTD) were determined. Pharmacokinetics, pharmacodynamics, and correlative studies were also performed. Opaganib was well tolerated up to a dose of 750 mg BID. The most common possibly related adverse event (AE) was decreased neutrophil counts. There were no serious AEs considered to be related to opaganib. MTD was determined as at least 750 mg BID. On an intent-to-treat basis, one patient (7.7%) in the 500 mg BID dose cohort showed a very good partial response, and one other patient (7.7%) achieved stable disease for 3 months. SK2 is an innovative molecular target for antimyeloma therapy. The first-in-class SK2 inhibitor opaganib is generally safe for administration to RRMM patients, and has potential therapeutic activity in these patients. Clinicaltrials.gov: NCT02757326.

Modulations of urinary lipid mediators in acute bladder cystitis

Bioactive lipids, such as lysophospholipids, ceramides, and eicosanoids and related mediators, have been demonstrated to be involved in inflammation. We aimed to investigate the possible orchestral modulations of these bioactive lipids in human inflammation. We simultaneously measured the urinary levels of lysophospholipids, ceramides, and eicosanoids and related mediators by a liquid chromatography-mass spectrometry method in patients with cystitis and control subjects. The urinary levels of lysophosphatidylcholine, lysophosphatidylethanolamine, sphingosine 1-phosphate, ceramides, prostaglandin (PG)E₂ and its metabolites represented by tetranor-PGEM, several oxylipins, DHA, and lysoPAF were higher in patients with cystitis. Urinary levels of some species of glycerolysophospholipids were highly positively correlated with those of other species of the same glycerolysophospholipids. Cluster analyses revealed that lysophosphatidylcholine was close to a PGE₂ metabolite, lysophosphatidylethanolamine was close to DHA, and sphingosine 1-phosphate and ceramides were close to lysoPAF. The orchestral dynamism of the lipid mediators was observed in the urine of cystitis, suggesting the necessity for simultaneous investigation of lipid mediators for translational research.

Pretreatment of human retinal pigment epithelial cells with sterculic acid forestalls fenretinide-induced apoptosis

The ratio of saturated to monounsaturated fatty acids, thought to play a critical role in many cellular functions, is regulated by stearoyl-CoA desaturase (SCD), a rate-limiting enzyme in the biosynthesis of monounsaturated fatty acids. Previously, we observed a decrease in both SCD protein and enzymatic activity in apoptosis induced by fenretinide, a synthetic analog of retinoic acid, in the human retinal pigment epithelial (RPE) cell line ARPE-19. Here, we investigated the effect of pretreating ARPE-19 with sterculic acid, a cyclopropenoic fatty acid inhibitor of SCD, on preventing fenretinide-induced apoptosis, given the role of SCD in cell proliferation and apoptosis. We show that sterculic acid pretreatment prevents the effects of fenretinide-induced apoptosis shown by changes in cell morphology, viability, and caspase-3 activation. Analysis of endoplasmic reticulum (ER)-associated proteins shows that sterculic acid pretreatment reduced the fenretinide-induced upregulation of heme oxygenase-1, ATF3 and GADD153 expression that are in response to reactive oxygen species (ROS) generation. Sterculic acid is as effective as allopurinol in inhibition of xanthine oxidase (XDH), and this may play a role in reducing the potential role of XDH in fenretinide-induced ROS generation. Sterculic acid pretreatment also results in a reduction in SOD2 mRNA expression. Dihydroceramide accumulation, compared to ceramide, and ROS generation indicate that a ceramide-independent pathway mediates fenretinide-induced apoptosis, and ROS mediation is borne out by activation of the NF-κBp50 and NF-κBp65 downstream signaling cascade. Its prevention by sterculic acid pretreatment further indicates the latter's antioxidant/anti-inflammatory effect. Taken together, our results suggest that sterculic acid pretreatment can mitigate ROS-mediated fenretinide-induced apoptosis. Thus, sterculic acid may serve as a potential antioxidant and therapeutic agent. These effects may be independent of its effects on SCD activity.

Thermal Stress Induces Metabolic Responses in Juvenile Qingtian Paddy Field Carp Cyprinus carpio var qingtianensis

Extreme fluctuations in water temperature lead to significant economic losses for the aquaculture industry. Cyprinus carpio var qingtianensis (locally called Qingtian paddy field carp), is a local variety commonly found in Zhejiang province, China. Unlike traditional aquaculture environments, the water temperature range between day and night in the rice field environment is much larger, and the high temperature in summer may exceed the growth threshold of fish because there is no manual intervention; therefore, the study of how the Qingtian paddy field carp (PF carp) adapts to high-temperature conditions can shed light how the species adapt to the rice field environment. To investigate the molecular mechanisms of this fish under thermal stress, the liver metabolomics of Qiangtian paddy field carp (PF carp) were analyzed. In this study, metabolomics was used to examine the metabolic reaction of PF carp (102 days old, 104.69 ± 3.08 g in weight, 14.65 ± 0.46 cm in length) at water temperatures of 28 °C (control group, CG), 34 °C (experimental group (EG) 34), and 38 °C (EG38). The results show that 175 expression profile metabolites (DEMs), including 115 upregulated and 60 downregulated metabolites, were found in the CG vs. EG34. A total of 354 DEMs were inspected in CG vs. EG38, with 85 metabolites downregulated and 269 metabolites upregulated. According to the pathway enrichment study, various pathways were altered by thermal stress, including those of lipid, amino-acid, and carbohydrate metabolism. Our study presents a potential metabolic profile for PF carp under thermal stress. It also demonstrates how the host responds to thermal stress on a metabolic and molecular level.

Differences in the Distribution of Ceramides and Sphingosine among Lipoprotein and Lipoprotein-Depleted Fractions in Patients with Type 2 Diabetes Mellitus

AIM

In addition to the quantity and quality, the carriers, such as lipoproteins and albumin, can affect the physiological properties and clinical significance of lipids. This study aimed to elucidate the modulation of the levels of ceramides and sphingosine, which are considered as proatherosclerotic lipids, in lipoproteins and lipoprotein-depleted fractions in subjects with type 2 diabetes.

METHODS

We separated the serum samples collected from healthy subjects (n=22) and subjects with type 2 diabetes (n=39) into Triglyceride (TG)-rich lipoproteins (TRL), low-density lipoprotein (LDL), high-density lipoprotein (HDL), and lipoprotein-depleted fractions via ultracentrifugation. Then, we measured the levels of six species of ceramides, sphingosine, and dihydrosphingosine via LC-MS/MS and statistically analyzed them to identify the sphingolipids in each fraction, which are associated with diabetes as well as cardiovascular and renal complications.

RESULTS

In subjects with diabetes, the levels of sphingosine and dihydrosphingosine in the TRL, LDL, and lipoprotein-depleted fractions were higher, whereas those in the HDL were lower. In addition, the ceramide levels in HDL were lower, whereas those in lipoprotein-depleted fractions were higher. Furthermore, The levels of ceramides in lipoproteins, especially LDL, were negatively associated with the presence of cardiovascular diseases and stage 4 diabetic nephropathy.

CONCLUSIONS

The contents of ceramides and sphingosine in lipoproteins and lipoprotein-depleted fractions were differently modulated in diabetes and associated with cardiovascular diseases and diabetic nephropathy. The carrier might be an important factor for the biological properties and clinical significance of these sphingolipids.

Advancements on the Multifaceted Roles of Sphingolipids in Hematological Malignancies

Dysregulation of sphingolipid metabolism plays a complex role in hematological malignancies, beginning with the first historical link between sphingolipids and apoptosis discovered in HL-60 leukemic cells. Numerous manuscripts have reviewed the field including the early discoveries that jumpstarted the studies. Many studies discussed here support a role for sphingolipids, such as ceramide, in combinatorial therapeutic regimens to enhance anti-leukemic effects and reduce resistance to standard therapies. Additionally, inhibitors of specific nodes of the sphingolipid pathway, such as sphingosine kinase inhibitors, significantly reduce leukemic cell survival in various types of leukemias. Acid ceramidase inhibitors have also shown promising results in acute myeloid leukemia. As the field moves rapidly, here we aim to expand the body of literature discussed in previously published reviews by focusing on advances reported in the latter part of the last decade.

The nutritional functions of dietary sphingomyelin and its applications in food

Sphingolipids are common structural components of cell membranes and are crucial for cell functions in physiological and pathophysiological conditions. Sphingomyelin and its metabolites, such as sphingoid bases, ceramide, ceramide-1-phosphate, and sphingosine-1-phosphate, play signaling roles in the regulation of human health. The diverse structures of sphingolipids elicit various functions in cellular membranes and signal transduction, which may affect cell growth, differentiation, apoptosis, and maintain biological activities. As nutrients, dietary sphingomyelin and its metabolites have wide applications in the food and pharmaceutical industry. In this review, we summarized the distribution, classifications, structures, digestion, absorption and metabolic pathways of sphingolipids, and discussed the nutritional functioning of sphingomyelin in chronic metabolic diseases. The possible implications of dietary sphingomyelin in the modern food preparations including dairy products and infant formula, skin improvement, delivery system and oil organogels are also evaluated. The production of endogenous sphingomyelin is linked to pathological changes in obesity, diabetes, and atherosclerosis. However, dietary supplementations of sphingomyelin and its metabolites have been shown to maintain cholesterol homeostasis and lipid metabolism, and to prevent or treat these diseases. This seemly paradoxical phenomenon shows that dietary sphingomyelin and its metabolites are candidates for food additives and functional food development for the prevention and treatment of chronic metabolic diseases in humans.

"Flash & Click": Multifunctionalized Lipid Derivatives as Tools To Study Viral Infections

In this perspective article, we describe the current status of lipid tools for studying host lipid-virus interactions at the cellular level. We discuss the potential lipidomic changes that viral infections impose on host cells and then outline the tools available and the resulting options to investigate the host cell lipid interactome. The future outcome will reveal new targets for treating virus infections.

Non-Small Cell Lung Cancer Detection and Subtyping by UPLC-HRMS-Based Tissue Metabolomics

Non-small cell lung cancer (NSCLC) is the prevalent histological subtype of lung cancer. In this study, we performed ultraperformance liquid chromatography-high-resolution mass spectrometry (UPLC-HRMS)-based metabolic profiling of 227 tissue samples from 79 lung cancer patients with adenocarcinoma (AC) or squamous cell carcinoma (SCC). Orthogonal partial least squares-discriminant analysis (oPLS-DA) analyses showed that AC, SCC, and NSCLC tumors were discriminated from adjacent noncancerous tissue (ANT) and distant noncancerous tissue (DNT) samples with good accuracies (91.3, 100, and 88.3%), sensitivities (85.7, 100, and 83.9%), and specificities (94.3, 100, and 90.7%), using 12, 4, and 7 discriminant metabolites, respectively. The discriminant panel for AC detection included valine, sphingosine, glutamic acid γ-methyl ester, and lysophosphatidylcholine (LPC) (16:0), levels of which in tumor tissues were significantly altered. Valine, sphingosine, LPC (18:1), and leucine derivatives were used for SCC detection. The discrimination between AC and SCC had 96.8% accuracy, 98.2% sensitivity, and 85.7% specificity using a five-metabolite panel, of which valine and creatine had significant differences. The classification models were further verified with external validation sets, showing a promising prospect for NSCLC tissue detection and subtyping.

Lipidomics Analysis Reveals a Protective Effect of Myriocin on Cerebral Ischemia/Reperfusion Model Rats

Ceramide accumulation has been associated with ischemic stroke. Myriocin is an effective serine palmitoyltransferase (SPT) inhibitor that reduces ceramide levels by inhibiting the de novo synthesis pathway. However, the role of myriocin in cerebral ischemia/reperfusion (I/R) injury and its underlying mechanism remain unknown. The present study established an experimental rat model of middle cerebral artery occlusion (MCAO). We employed ultra-performance liquid chromatograph quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS)-based lipidomic analysis to identify the disordered lipid metabolites and the effects of myriocin in cerebral cortical tissues of rats. In this study, we found 15 characterized lipid metabolites involved in sphingolipid and glycerophospholipid metabolism in cerebral I/R-injured rats, and these alterations were significantly alleviated by myriocin. Specifically, the mRNA expression of metabolism-related enzyme genes was detected by real-time quantitative polymerase chain reaction (RT-qPCR). We demonstrated that myriocin could regulate the mRNA expression of ASMase, NSMase, SGMS1, SGMS2, ASAH1, ACER2, and ACER3, which are involved in sphingolipid metabolism and PLA2, which is involved in glycerophospholipid metabolism. Moreover, TUNEL and Western blot assays showed that myriocin plays a key role in regulating neuronal cell apoptosis. In summary, the present work provides a new perspective for the systematic study of metabolic changes in ischemic stroke and the therapeutic applications of myriocin.

Biodegradation of arsenobetaine to inorganic arsenic regulated by specific microorganisms and metabolites in mice

Arsenobetaine (AsB) is a primary arsenic (As) compound found in marine organisms. However, in mammals, the metabolic mechanism of AsB remains indistinct. Therefore, in this study, we investigated the biotransformation and regulatory mechanism of AsB, particularly the biodegradation process, in a mouse model to assess the underlying health hazards of AsB. We studied the biotransformation process of AsB in mice through the food chain [AsB feed-marine fish (Epinephelus fuscoguttatus)-mice (Mus musculus)]. Our results showed the significant bioaccumulation of total As, AsB, and, in particular, arsenate [As(V)] through biodegradation in mice tissues. As the abundance of Staphylococcus and Blautia (phylum, Firmicutes) increased, the expression of aqp7 (absorption) and methyltransferase (as3mt) (methylation) was upregulated. In contrast, the expression of S-adenosyl methionine (sam) (methylation) was downregulated. These findings suggest that demethylation and methylation occurred simultaneously in the intestines, with demethylation capacity being greater than that of methylation. Furthermore, Firmicutes such as Staphylococcus and Blautia showed a significant inverse relationship with arachidonic acid, choline, and sphingosine. Gene, microbiome, and metabolomics analyses indicated that Staphylococcus and Blautia and arachidonic acid, choline, and sphingosine participated in the degradation of AsB to As(V) in mouse intestines. Therefore, long-term AsB ingestion through marine fish consumption could cause potential health hazards in humans.

Metabolomic Profiling Analysis of Physiological Responses to Acute Hypoxia and Reoxygenation in Juvenile Qingtian Paddy Field Carp Cyprinus Carpio Var Qingtianensis

The Qingtian paddy field carp (Cyprinus carpio var qingtianensis) is a local carp cultivated in the rice field of Qingtian county, Zhejiang province, China. The paddy field environment is distinct from the pond environment. Due to the inability to artificially increase oxygen, the dissolved oxygen greatly changes during the day. Therefore, investigating the physiological regulation to the changes of acute dissolved oxygen in Qingtian paddy field carp (PF-carp) will dramatically clarify how it adapts to the paddy breeding environment. The high tolerance of Qingtian paddy field carp to hypoxia makes it an ideal organism for studying molecular regulatory mechanisms during hypoxia process and reoxygenation following hypoxia in fish. In this study, we compared the changes of metabolites in the hepatopancreas during hypoxia stress and the following reoxygenation through comparative metabolomics. The results showed 131 differentially expressed metabolites between the hypoxic groups and control groups. Among them, 95 were up-regulated, and 36 were down-regulated. KEGG Pathway enrichment analysis showed that these differential metabolites were mainly involved in regulating lipid, protein, and purine metabolism PF-carps could require energy during hypoxia by enhancing the gluconeogenesis pathway with core glutamic acid and glutamine metabolism. A total of 63 differentially expressed metabolites were screened by a comparison between the reoxygenated groups and the hypoxic groups. Specifically, 15 were up-regulated, and 48 were down-regulated. The KEGG Pathway enrichment analysis supported that PF-carp could continue to gain energy by consuming glutamic acid and the glutamine accumulated during hypoxia and simultaneously weaken the ammonia-transferring effect of amino acids and the toxicity of ammonia. By consuming glycerophospholipids and maintaining the Prostaglandin E content, cell damage was improved, sphingosinol synthesis was reduced, and apoptosis was inhibited. Additionally, it could enhance the salvage synthesis and de novo synthesis of purine, reduce purine accumulation, promote the synthesis of nucleotide and energy carriers, and assist in recovering physiological metabolism. Overall, results explained the physiological regulation mechanism of PF-carp adapting to the acute changes of dissolved oxygen at the metabolic level and also provided novel evidence for physiological regulation of other fish in an environment with acute changes in dissolved oxygen levels.

Implications of Sphingolipid Metabolites in Kidney Diseases

Sphingolipids, which act as a bioactive signaling molecules, are involved in several cellular processes such as cell survival, proliferation, migration and apoptosis. An imbalance in the levels of sphingolipids can be lethal to cells. Abnormalities in the levels of sphingolipids are associated with several human diseases including kidney diseases. Several studies demonstrate that sphingolipids play an important role in maintaining proper renal function. Sphingolipids can alter the glomerular filtration barrier by affecting the functioning of podocytes, which are key cellular components of the glomerular filtration barrier. This review summarizes the studies in our understanding of the regulation of sphingolipid signaling in kidney diseases, especially in glomerular and tubulointerstitial diseases, and the potential to target sphingolipid pathways in developing therapeutics for the treatment of renal diseases.

Extracellular Lipids in the Lung and Their Role in Pulmonary Fibrosis

Lipids are major actors and regulators of physiological processes within the lung. Initial research has described their critical role in tissue homeostasis and in orchestrating cellular communication to allow respiration. Over the past decades, a growing body of research has also emphasized how lipids and their metabolism may be altered, contributing to the development and progression of chronic lung diseases such as pulmonary fibrosis. In this review, we first describe the current working model of the mechanisms of lung fibrogenesis before introducing lipids and their cellular metabolism. We then summarize the evidence of altered lipid homeostasis during pulmonary fibrosis, focusing on their extracellular forms. Finally, we highlight how lipid targeting may open avenues to develop therapeutic options for patients with lung fibrosis.

GFI1-Dependent Repression of SGPP1 Increases Multiple Myeloma Cell Survival

Simple Summary

New therapies have greatly improved the progression-free and overall survival for patients with “standard risk” multiple myeloma (MM). However, patients with “high risk” MM, in particular patients whose MM cells harbor non-functional p53, have very short survival times because of the early relapse and rapid development of highly therapy-resistant MM. In this report, we identify a novel mechanism responsible for Growth Factor Independence-1 (GFI1) regulation of the growth and survival of MM cells through its modulation of sphingolipid metabolism, regardless of their p53 status. We identify the Sphingosine-1-Phosphate Phosphatase (SGPP1) gene as a novel direct target of GFI1 transcriptional repression in MM cells, thus increasing intracellular sphingosine-1-phosphate levels, which stabilizes c-Myc. Our results support GFI1 as an attractive therapeutic target for all types of MM, including the “high risk” patient population with non-functional p53, as well as a possible therapeutic approach for other types of cancers expressing high levels of c-Myc.

Abstract

Multiple myeloma (MM) remains incurable for most patients due to the emergence of drug resistant clones. Here we report a p53-independent mechanism responsible for Growth Factor Independence-1 (GFI1) support of MM cell survival by its modulation of sphingolipid metabolism to increase the sphingosine-1-phosphate (S1P) level regardless of the p53 status. We found that expression of enzymes that control S1P biosynthesis, SphK1, dephosphorylation, and SGPP1 were differentially correlated with GFI1 levels in MM cells. We detected GFI1 occupancy on the SGGP1 gene in MM cells in a predicted enhancer region at the 5’ end of intron 1, which correlated with decreased SGGP1 expression and increased S1P levels in GFI1 overexpressing cells, regardless of their p53 status. The high S1P:Ceramide intracellular ratio in MM cells protected c-Myc protein stability in a PP2A-dependent manner. The decreased MM viability by SphK1 inhibition was dependent on the induction of autophagy in both p53WT and p53mut MM. An autophagic blockade prevented GFI1 support for viability only in p53mut MM, demonstrating that GFI1 increases MM cell survival via both p53WT inhibition and upregulation of S1P independently. Therefore, GFI1 may be a key therapeutic target for all types of MM that may significantly benefit patients that are highly resistant to current therapies.

Effects of Cage and Floor Rearing Systems on the Metabolic Components of the Uropygial Gland in Ducks

Simple Summary

With the development of the modern poultry industry, people have gradually transformed the floor rearing system into a cage rearing system. However, due to some factors, including the environment and management, the feather condition of caged ducks is generally poor, which impairs the healthy growth of ducks and the economic efficiency of breeders. It is believed that birds usually collect secretions from their uropygial gland and smear them on their feathers and cuticle scales during preening to improve their waterproofing and resistance to pathogens, thus protecting their health and growth. Therefore, we studied the uropygial glands of ducks in different rearing systems. The results showed that the cage rearing system affected the weight and metabolic components in the uropygial gland of ducks. Caged ducks have a lower relative weight of their uropygial gland and lower levels of certain amino acids and fatty acids that contribute to their development. This allows us to better understand the causes of the poor appearance of feathers in caged ducks.

Abstract

Background: As a unique skin derivative of birds, the uropygial gland has a potential role in maintaining feather health and appearance. Cage-reared ducks usually have a worse feather condition than floor-reared ducks. We suspected that the metabolic components in the uropygial gland might play a vital role in their feather conditions. Methods: Herein, the uropygial glands of floor- and cage-reared ducks were weighed, and a nontargeted metabolic analysis was performed. Results: At 20 weeks of age, the relative weight of floor-reared duck uropygial glands was significantly higher than that of cage-reared ducks, indicating that the floor rearing system is better for inducing the development of uropygial glands. The nontargeted metabolic data revealed 1190 and 1149 differential metabolites under positive and negative ion modes, respectively. Among them, 49 differential metabolites were annotated between the two rearing systems. Three sulfur-containing amino acids, namely, 2-ketobutyric acid, L-aspartate-semialdehyde, and N-formyl-L-methionine, and some lipids, including inositol and sphingosine, might be responsible for the changes in plumage appearance among the various rearing conditions. Conclusions: The results of our study revealed the differences in the metabolic components of the uropygial gland in ducks reared under different rearing systems and found metabolic components to be possibly responsible for the poor feather condition of caged ducks.

Anticancer Effects of New Ceramides Isolated from the Red Sea Red Algae Hypnea&nbsp;musciformis in a Model of Ehrlich Ascites Carcinoma: LC-HRMS Analysis Profile and Molecular Modeling

Different classes of phytochemicals were previously isolated from the Red Sea algae Hypnea&nbsp;musciformis as sterols, ketosteroids, fatty acids, and terpenoids. Herein, we report the isolation of three fatty acids-docosanoic acid 4, hexadecenoic acid 5, and alpha hydroxy octadecanoic acid 6-as well as three ceramides-A (1), B (2), and C (3)-with 9-methyl-sphinga-4,8-dienes and phytosphingosine bases. Additionally, different phytochemicals were determined using the liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry (LC-ESI-HRMS) technique. Ceramides A (1) and B (2) exhibited promising in vitro cytotoxic activity against the human breast adenocarcinoma (MCF-7) cell line when compared with doxorubicin as a positive control. Further in vivo study and biochemical estimation in a mouse model of Ehrlich ascites carcinoma (EAC) revealed that both ceramides A (1) and B (2) at doses of 1 and 2 mg/kg, respectively, significantly decreased the tumor size in mice inoculated with EAC cells. The higher dose (2 mg/kg) of ceramide B (2) particularly expressed the most pronounced decrease in serum levels of vascular endothelial growth factor -B (VEGF-B) and tumor necrosis factor-α (TNF-α) markers, as well as the expression levels of the growth factor midkine in tumor tissue relative to the EAC control group. The highest expression of apoptotic factors, p53, Bax, and caspase 3 was observed in the same group that received 2 mg/kg of ceramide B (2). Molecular docking simulations suggested that ceramides A (1) and B (2) could bind in the deep grove between the H2 helix and the Ser240-P250 loop of p53, preventing its interaction with MDM2 and leading to its accumulation. In conclusion, this study reports the cytotoxic, apoptotic, and antiangiogenic effects of ceramides isolated from the Red Sea algae Hypnea&nbsp;musciformis in an experimental model of EAC.

Lipid Profiles of the Heads of Four Shrimp Species by UPLC-Q-Exactive Orbitrap/MS and Their Cardiovascular Activities

Lipids are key factors in nutrition, structural function, metabolic features, and other biological functions. In this study, the lipids from the heads of four species of shrimp (Fenneropenaeus chinensis (FC), Penaeus japonicus (PJ), Penaeus vannamei (PV), and Procambarus clarkia (PCC)) were compared and characterized based on UPLC-Q-Exactive Orbitrap/MS. We compared the differences in lipid composition of four kinds of shrimp head using multivariate analysis. In addition, a zebrafish model was used to evaluate pro-angiogenic, anti-inflammatory, anti-thrombotic, and cardioprotective activities of the shrimp head lipids. The lipids from the four kinds of shrimp head had different degrees of pro-angiogenic activities, and the activities of PCC and PJ shrimp lipids were more significant than those of the other two species. Four lipid groups displayed strong anti-inflammatory activities. For antithrombotic activity, only PCC (25 μg/mL) and PV (100 μg/mL) groups showed obvious activity. In terms of cardioprotective activity, the four kinds of lipid groups significantly increased the zebrafish heart rhythms. The heart distances were shortened, except for those of the FC (100 μg/mL) and PJ (25 μg/mL) groups. Our comprehensive lipidomics analysis and bioactivity study of lipids from different sources could provide a basis for the better utilization of shrimp.

Podocyte Sphingolipid Signaling in Nephrotic Syndrome

Podocytes play a vital role in the pathogenesis of nephrotic syndrome (NS), which is clinically characterized by heavy proteinuria, hypoalbuminemia, hyperlipidemia, and peripheral edema. The pathogenesis of NS has evolved through several hypotheses ranging from immune dysregulation theory and increased glomerular permeability theory to the current concept of podocytopathy. Podocytopathy is characterized by dysfunction or depletion of podocytes, which may be caused by unknown permeability factor, genetic disorders, drugs, infections, systemic disorders, and hyperfiltration. Over the last two decades, numerous studies have been done to explore the molecular mechanisms of podocyte injuries or NS and to develop the novel therapeutic strategies targeting podocytopathy for treatment of NS. Recent studies have shown that normal sphingolipid metabolism is essential for structural and functional integrity of podocytes. As a basic component of the plasma membrane, sphingolipids not only support the assembly of signaling molecules and interaction of receptors and effectors, but also mediate various cellular activities, such as apoptosis, proliferation, stress responses, necrosis, inflammation, autophagy, senescence, and differentiation. This review briefly summarizes current evidence demonstrating the regulation of sphingolipid metabolism in podocytes and the canonical or noncanonical roles of podocyte sphingolipid signaling in the pathogenesis of NS and associated therapeutic strategies.

Alterations in lipid profile upon uterine fibroids and its recurrence

Uterine fibroids (UF) is the most common (about 70% cases) type of gynecological disease, with the recurrence rate varying from 11 to 40%. Because UF has no distinct symptomatology and is often asymptomatic, the specific and sensitive diagnosis of UF as well as the assessment for the probability of UF recurrence pose considerable challenge. The aim of this study was to characterize alterations in the lipid profile of tissues associated with the first-time diagnosed UF and recurrent uterine fibroids (RUF) and to explore the potential of mass spectrometry (MS) lipidomics analysis of blood plasma samples for the sensitive and specific determination of UF and RUF with low invasiveness of analysis. MS analysis of lipid levels in the myometrium tissues, fibroids tissues and blood plasma samples was carried out on 66 patients, including 35 patients with first-time diagnosed UF and 31 patients with RUF. The control group consisted of 15 patients who underwent surgical treatment for the intrauterine septum. Fibroids and myometrium tissue samples were analyzed using direct MS approach. Blood plasma samples were analyzed using high performance liquid chromatography hyphened with mass spectrometry (HPLC/MS). MS data were processed by discriminant analysis with projection into latent structures (OPLS-DA). Significant differences were found between the first-time UF, RUF and control group in the levels of lipids involved in the metabolism of glycerophospholipids, sphingolipids, lipids with an ether bond, triglycerides and fatty acids. Significant differences between the control group and the groups with UF and RUF were found in the blood plasma levels of cholesterol esters, triacylglycerols, (lyso) phosphatidylcholines and sphingomyelins. Significant differences between the UF and RUF groups were found in the blood plasma levels of cholesterol esters, phosphotidylcholines, sphingomyelins and triacylglycerols. Diagnostic models based on the selected differential lipids using logistic regression showed sensitivity and specificity of 88% and 86% for the diagnosis of first-time UF and 95% and 79% for RUF, accordingly. This study confirms the involvement of lipids in the pathogenesis of uterine fibroids. A diagnostically significant panel of differential lipid species has been identified for the diagnosis of UF and RUF by low-invasive blood plasma analysis. The developed diagnostic models demonstrated high potential for clinical use and further research in this direction.

Cerebrospinal Fluid C18 Ceramide Associates with Markers of Alzheimer's Disease and Inflammation at the Pre- and Early Stages of Dementia

Background:

Understanding how dysregulation in lipid metabolism relates to the severity of Alzheimer‘s disease (AD) pathology might be critical in developing effective treatments.

Objective:

To identify lipid species in cerebrospinal fluid (CSF) associated with signature AD pathology and to explore their relationships with measures reflecting AD-related processes (neurodegeneration, inflammation, deficits in verbal episodic memory) among subjects at the pre- and early symptomatic stages of dementia.

Methods:

A total of 60 subjects that had been referred to an Icelandic memory clinic cohort were classified as having CSF AD (n = 34) or non-AD (n = 26) pathology profiles. Untargeted CSF lipidomic analysis was performed using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) for the detection of mass-to-charge ratio (m/z) features. CSF proteins reflecting neurodegeneration (neurofilament light [NFL]) and inflammation (chitinase-3-like protein 1 [YKL-40], S100 calcium-binding protein B [S100B], glial fibrillary acidic protein [GFAP]) were also measured. Rey Auditory Verbal Learning (RAVLT) and Story tests were used for the assessment of verbal episodic memory.

Results:

Eight out of 1008 features were identified as best distinguishing between the CSF profile groups. Of those, only the annotation of the m/z feature assigned to lipid species C18 ceramide was confirmed with a high confidence. Multiple regression analyses, adjusted for age, gender, and education, demonstrated significant associations of CSF core AD markers (Aβ₄₂: st.β= –0.36, p = 0.007; T-tau: st.β= 0.41, p = 0.005) and inflammatory marker S100B (st.β= 0.51, p = 0.001) with C18 ceramide levels.

Conclusion:

Higher levels of C18 ceramide associated with increased AD pathology and inflammation, suggesting its potential value as a therapeutic target.

Biophysical impact of sphingosine and other abnormal lipid accumulation in Niemann-Pick disease type C cell models

Niemann-Pick disease type C (NPC) is a complex and rare pathology, which is mainly associated to mutations in the NPC1 gene. This disease is phenotypically characterized by the abnormal accumulation of multiple lipid species in the acidic compartments of the cell. Due to the complexity of stored material, a clear molecular mechanism explaining NPC pathophysiology is still not established. Abnormal sphingosine accumulation was suggested as the primary factor involved in the development of NPC, followed by the accumulation of other lipid species. To provide additional mechanistic insight into the role of sphingosine in NPC development, fluorescence spectroscopy and microscopy were used to study the biophysical properties of biological membranes using different cellular models of NPC. Addition of sphingosine to healthy CHO-K1 cells, in conditions where other lipid species are not yet accumulated, caused a rapid decrease in plasma membrane and lysosome membrane fluidity, suggesting a direct effect of sphingosine rather than a downstream event. Changes in membrane fluidity caused by addition of sphingosine were partially sustained upon impaired trafficking and metabolization of cholesterol in these cells, and could recapitulate the decrease in membrane fluidity observed in NPC1 null Chinese Hamster Ovary (CHO) cells (CHO-M12) and in cells with pharmacologically induced NPC phenotype (treated with U18666A). In summary, these results show for the first time that the fluidity of the membranes is altered in models of NPC and that these changes are in part caused by sphingosine, supporting the role of this lipid in the pathophysiology of NPC.

Sphingolipids as multifaceted mediators in ovarian cancer

Ovarian cancer is the most lethal gynaecological malignancy. It is commonly diagnosed at advanced stage when it has metastasised to the abdominal cavity and treatment becomes very challenging. While current standard therapy involving debulking surgery and platinum + taxane-based chemotherapy is associated with high response rates initially, the large majority of patients relapse and ultimately succumb to chemotherapy-resistant disease. In order to improve survival novel strategies for early detection and therapeutics against treatment-refractory disease are urgently needed. A promising new target against ovarian cancer is the sphingolipid pathway which is commonly hijacked in cancer to support cell proliferation and survival and has been shown to promote chemoresistance and metastasis in a wide range of malignant neoplasms. In particular, the sphingosine kinase 1-sphingosine 1-phosphate receptor 1 axis has been shown to be altered in ovarian cancer in multiple ways and therefore represents an attractive therapeutic target. Here we review the roles of sphingolipids in ovarian cancer progression, metastasis and chemoresistance, highlighting novel strategies to target this pathway that represent potential avenues to improve patient survival.

Sphingolipids as critical players in retinal physiology and pathology

Sphingolipids have emerged as bioactive lipids involved in the regulation of many physiological and pathological processes. In the retina, they have been established to participate in numerous processes, such as neuronal survival and death, proliferation and migration of neuronal and vascular cells, inflammation, and neovascularization. Dysregulation of sphingolipids is therefore crucial in the onset and progression of retinal diseases. This review examines the involvement of sphingolipids in retinal physiology and diseases. Ceramide (Cer) has emerged as a common mediator of inflammation and death of neuronal and retinal pigment epithelium cells in animal models of retinopathies such as glaucoma, age-related macular degeneration (AMD), and retinitis pigmentosa. Sphingosine-1-phosphate (S1P) has opposite roles, preventing photoreceptor and ganglion cell degeneration but also promoting inflammation, fibrosis, and neovascularization in AMD, glaucoma, and pro-fibrotic disorders. Alterations in Cer, S1P, and ceramide 1-phosphate may also contribute to uveitis. Notably, use of inhibitors that either prevent Cer increase or modulate S1P signaling, such as Myriocin, desipramine, and Fingolimod (FTY720), preserves neuronal viability and retinal function. These findings underscore the relevance of alterations in the sphingolipid metabolic network in the etiology of multiple retinopathies and highlight the potential of modulating their metabolism for the design of novel therapeutic approaches.

Characteristics of apoptosis induction in human breast cancer cells treated with a ceramidase inhibitor

Cancer is a complex disease with high mortality rates. Breast cancer is one of the most fatal diseases both for men and woman. Despite the positive developments on cancer treatment, a successful treatment agent/method has not been developed, yet. Recently, cancer research has been involved in sphingolipid metabolism. The key molecule here is ceramide. Ceramides mediate growth suppress, apoptosis and aging regulation. Ceramidases metabolize ceramide and decrease its level in cells and cause escape the death. Inhibition of ceramidases as new targets for cancer treatment is shown in the literature. Herein, we found that d-erythro-MAPP and its nanoparticle formulation, reduce the viability of MCF-7 cells in a dose-dependent manner with IC₅₀ value of 4.4 µM, and 15.6 µM, respectively. Confocal and transmission electron microscopy results revealed apoptotic morphological and ultrastructural changes for both agents. Apoptosis and cell cycle arrest were supported by annexin-V, mitochondrial membrane potential changings and cell cycle analysis, respectively.

Alkaline ceramidase family: The first two decades

Ceramidases are a group of enzymes that catalyze the hydrolysis of ceramide, dihydroceramide, and phytoceramide into sphingosine (SPH), dihydrosphingosine (DHS), and phytosphingosine (PHS), respectively, along with a free fatty acid. Ceramidases are classified into the acid, neutral, and alkaline ceramidase subtypes according to the pH optima for their catalytic activity. YPC1 and YDC1 were the first alkaline ceramidase genes to be identified and cloned from the yeast Saccharomyces cerevisiae two decades ago. Subsequently, alkaline ceramidase genes were identified from other species, including one Drosophila melanogaster ACER gene (Dacer), one Arabidopsis thaliana ACER gene (AtACER), three Mus musculus ACER genes (Acer1, Acer2, and Acer3), and three Homo sapiens ACER genes (ACER1, ACER2, and ACER3). The protein products of these genes constitute a large protein family, termed the alkaline ceramidase (ACER) family. All the biochemically characterized members of the ACER family are integral membrane proteins with seven transmembrane segments in the Golgi complex or endoplasmic reticulum, and they each have unique substrate specificity. An increasing number of studies suggest that the ACER family has diverse roles in regulating sphingolipid metabolism and biological processes. Here we discuss the discovery of the ACER family, the biochemical properties, structures, and catalytic mechanisms of its members, and its role in regulating sphingolipid metabolism and biological processes in yeast, insects, plants, and mammals.

Antiproliferative Activity, Proapoptotic Effect, and Cell Cycle Arrest in Human Cancer Cells of Some Marine Natural Product Extract

Bioactive constituents of numerous marine organisms have been investigated recently for their preclinical and clinical anticancer activity. Three marine organisms: black-spotted sea cucumber: Pearsonothuria graeffei (Pg), lollyfish: Holothuria atra (Ha), and sea hare: Aplysia dactylomela (Ad), were collected during winter 2019 from Gulf of Aqaba, Red Sea, Egypt, and macerated with ethanol into three different extracts: PgE, HaE, and AdE, where each was in vitro assessed for its antiproliferative and proapoptotic properties on HepG2, HCT-116, and MCF-7 cancer cells. PgE dose-dependently inhibited the growth of HepG2, HCT-116, and MCF-7 cells within IC₅₀ values 16.22, 13.34, and 18.09 μg/mL, respectively, while the IC₅₀ values for the antiproliferative activity of HaE were 12.48, 10.45, and 10.36 μg/mL, respectively, and the IC₅₀ values of AdE were 6.51, 5.33, and 6.87 μg/mL, respectively. All extracts were found to induce G₀/G₁ cell cycle arrest for HepG2 cells side by side with their inhibition of CDK2 on all three cell lines while all extracts were also showed to induce apoptosis in HepG2 cell line at pre-G ₁ phase supplemented by their anticancer activity via proapoptotic protein Bax, caspase-3, and cleavage PARP increase, and antiapoptotic protein Bcl-2 downturn. Moreover, necrosis has been relatively noticed in HepG2 cell line as an additional anticancer activity for each extract. Our data introduced three ethanolic marine extracts as natural chemotherapeutic agents to be further developed for cancer control.

Lipid Players of Cellular Senescence

Lipids are emerging as key players of senescence. Here, we review the exciting new findings on the diverse roles of lipids in cellular senescence, most of which are enabled by the advancements in omics approaches. Senescence is a cellular process in which the cell undergoes growth arrest while retaining metabolic activity. At the organismal level, senescence contributes to organismal aging and has been linked to numerous diseases. Current research has documented that senescent cells exhibit global alterations in lipid composition, leading to extensive morphological changes through membrane remodeling. Moreover, senescent cells adopt a secretory phenotype, releasing various components to their environment that can affect the surrounding tissue and induce an inflammatory response. All of these changes are membrane and, thus, lipid related. Our work, and that of others, has revealed that fatty acids, sphingolipids, and glycerolipids are involved in the initiation and maintenance of senescence and its associated inflammatory components. These studies opened up an exciting frontier to investigate the deeper mechanistic understanding of the regulation and function of these lipids in senescence. In this review, we will provide a comprehensive snapshot of the current state of the field and share our enthusiasm for the prospect of potential lipid-related protein targets for small-molecule therapy in pathologies involving senescence and its related inflammatory phenotypes.

Metabolomic Biomarkers in Gynecology: A Treasure Path or a False Path?

Omic-technologies (genomics, transcriptomics, proteomics and metabolomics) have become more important in current medical science. Among them, it is metabolomics that most accurately reflects the minor changes in body functioning, as it focuses on metabolome - the group of the metabolism products, both intermediate and end. Therefore, metabolomics is actively engaged in fundamental and clinical studies and search for potential biomarkers. The biomarker could be used in diagnostics, management and stratification of the patients, as well as in prognosing the outcomes. The good example is gynecology, since many gynecological diseases lack effective biomarkers. In the current review, we aimed to summarize the results of the studies, devoted to the search of potential metabolomic biomarkers for the most common gynecological diseases.

Lipid Fingerprinting of Different Material Sources by UPLC-Q-Exactive Orbitrap/MS Approach and Their Zebrafish-Based Activities Comparison

Lipids are considered to be critical contributors to nutrition, structural function, metabolic function, and other biological roles. They vary from one biological source to another. Here, the lipids from three common sources (soybean, egg yolk, and shrimp head) were comprehensively compared and characterized using the lipidomics approach, together with the UPLC-Q-Exactive Orbitrap/MS method. A total of 3027 lipid structures containing 778 fatty acids, 750 glycerolipids, 1283 glycerophospholipids, 200 sphingolipids, and 16 sterol lipids were first identified and quantified in these resources. The characteristic lipid species with significant differences among groups were determined by lipidomics analysis. Besides, the antithrombotic, antioxidant, and anti-inflammatory activities were evaluated based on the zebrafish model. The correlation between differential lipids and activities was also analyzed. Our comprehensive lipidomics profiling and bioactivities of lipids from different sources in vivo can provide evidence for their future applications.

Sphingolipids in the Heart: From Cradle to Grave

Cardiovascular diseases are the leading cause of mortality worldwide and this has largely been driven by the increase in metabolic disease in recent decades. Metabolic disease alters metabolism, distribution, and profiles of sphingolipids in multiple organs and tissues; as such, sphingolipid metabolism and signaling have been vigorously studied as contributors to metabolic pathophysiology in various pathological outcomes of obesity, including cardiovascular disease. Much experimental evidence suggests that targeting sphingolipid metabolism may be advantageous in the context of cardiometabolic disease. The heart, however, is a structurally and functionally complex organ where bioactive sphingolipids have been shown not only to mediate pathological processes, but also to contribute to essential functions in cardiogenesis and cardiac function. Additionally, some sphingolipids are protective in the context of ischemia/reperfusion injury. In addition to mechanistic contributions, untargeted lipidomics approaches used in recent years have identified some specific circulating sphingolipids as novel biomarkers in the context of cardiovascular disease. In this review, we summarize recent literature on both deleterious and beneficial contributions of sphingolipids to cardiogenesis and myocardial function as well as recent identification of novel sphingolipid biomarkers for cardiovascular disease risk prediction and diagnosis.

Mammalian sphingoid bases: Biophysical, physiological and pathological properties

Sphingoid bases encompass a group of long chain amino alcohols which form the essential structure of sphingolipids. Over the last years, these amphiphilic molecules were moving more and more into the focus of biomedical research due to their role as bioactive molecules. In fact, free sphingoid bases interact with specific receptors and target molecules and have been associated with numerous biological and physiological processes. In addition, they can modulate the biophysical properties of biological membranes. Several human diseases are related to pathological changes in the structure and metabolism of sphingoid bases. Yet, the mechanisms underlying their biological and pathophysiological actions remain elusive. Within this review, we aimed to summarize the current knowledge on the biochemical and biophysical properties of the most common sphingoid bases and to discuss their importance in health and disease.

Sphingolipids as Emerging Mediators in Retina Degeneration

The sphingolipids ceramide (Cer), sphingosine-1-phosphate (S1P), sphingosine (Sph), and ceramide-1-phosphate (C1P) are key signaling molecules that regulate major cellular functions. Their roles in the retina have gained increasing attention during the last decade since they emerge as mediators of proliferation, survival, migration, neovascularization, inflammation and death in retina cells. As exacerbation of these processes is central to retina degenerative diseases, they appear as crucial players in their progression. This review analyzes the functions of these sphingolipids in retina cell types and their possible pathological roles. Cer appears as a key arbitrator in diverse retinal pathologies; it promotes inflammation in endothelial and retina pigment epithelium (RPE) cells and its increase is a common feature in photoreceptor death in vitro and in animal models of retina degeneration; noteworthy, inhibiting Cer synthesis preserves photoreceptor viability and functionality. In turn, S1P acts as a double edge sword in the retina. It is essential for retina development, promoting the survival of photoreceptors and ganglion cells and regulating proliferation and differentiation of photoreceptor progenitors. However, S1P has also deleterious effects, stimulating migration of Müller glial cells, angiogenesis and fibrosis, contributing to the inflammatory scenario of proliferative retinopathies and age related macular degeneration (AMD). C1P, as S1P, promotes photoreceptor survival and differentiation. Collectively, the expanding role for these sphingolipids in the regulation of critical processes in retina cell types and in their dysregulation in retina degenerations makes them attractive targets for treating these diseases.

Sphingosine kinase-1 predicts overall survival outcomes in non-small cell lung cancer patients treated with carboplatin and navelbine

Sphingosine 1-phosphate (S1P) is a bioactive lipid metabolite associated with cancer cell proliferation, survival, migration and regulation of tumor angiogenesis in various cellular and animal models. Sphingosine kinase-1 (SphK1) and S1P lyase are the main enzymes that respectively control the synthesis and degradation of S1P. The present study analyzed the prognostic and predictive value of SphK1 and S1P lyase expression in patients with non-small cell lung cancer (NSCLC), treated with either surgery alone or in combination with adjuvant carboplatin and navelbine. Formalin-fixed, paraffin-embedded tissue samples from 176 patients with NSCLC were stained immunohistochemically using antibodies against SphK1 and S1P lyase, and their expression was correlated with all available clinicopathological factors. Increased expression of SphK1 was significantly associated with shorter overall and disease free survival in patients treated with adjuvant platinum-based chemotherapy. No prognostic relevance for S1P lyase expression was observed. Collectively, the results suggest that the immunohistochemical detection of SphK1 may be a promising predictive marker in NSCLC patients treated with adjuvant platinum-based chemotherapy.

Mammalian sphingoid bases: Biophysical, physiological and pathological properties

Sphingoid bases encompass a group of long chain amino alcohols which form the essential structure of sphingolipids. Over the last years, these amphiphilic molecules were moving more and more into the focus of biomedical research due to their role as bioactive molecules. In fact, free sphingoid bases interact with specific receptors and target molecules, and have been associated with numerous biological and physiological processes. In addition, they can modulate the biophysical properties of biological membranes. Several human diseases are related to pathological changes in the structure and metabolism of sphingoid bases. Yet, the mechanisms underlying their biological and pathophysiological actions remain elusive. Within this review, we aimed to summarize the current knowledge on the biochemical and biophysical properties of the most common sphingoid bases and to discuss their importance in health and disease.

Bioactive sphingolipid profile in a xenograft mouse model of head and neck squamous cell carcinoma

The purpose of this study was to determine the profile of bioactive sphingolipids in xenograft mouse tissues of head and neck squamous cell carcinoma. We utilized UHPLC-MS/MS to determine the profile of full set of ceramides, sphingosine, and sphingosine 1-phosphate in this xenograft mouse model. The tissues isolated and investigated were from brain, lung, heart, liver, spleen, kidney, bladder, tumors and blood. With the exception of equal volume of blood plasma (100ul), all tissues were studied with the same amount of protein (800ug). Results demonstrated that brain contained the highest level of ceramide and kidney had the highest level of sphingosine, whereas sphingosine 1-phosphate and dihydrosphingosine 1-phosphate were heavily presented in the blood. Brain also comprised the highest level of phospholipids. As for the species, several ceramides, usually present in very low amounts in cultured tumor cells, showed relatively high levels in certain tissues. This study highlights levels of bioactive sphingolipids profiles in xenograft mouse model of head and neck squamous cell carcinoma, and provides resources to investigate potential therapeutic targets and biomarkers that target bioactive sphingolipids metabolism pathways.

Sphingolipid-induced cell death in Arabidopsis is negatively regulated by the papain-like cysteine protease RD21

It is now well established that sphingoid Long Chain Bases (LCBs) are crucial mediators of programmed cell death. In plants, the mycotoxin fumonisin B1 (FB1) produced by the necrotrophic fungus Fusarium moniliforme disrupts the sphingolipid biosynthesis pathway by inhibiting the ceramide synthase leading to an increase in the amount of phytosphingosine (PHS) and dihydrosphingosine (DHS), the two major LCBs in Arabidopsis thaliana. To date, the signaling pathway involved in FB1-induced cell death remains largely uncharacterized. It is also well acknowledged that plant proteases such as papain-like cysteine protease are largely involved in plant immunity. Here, we show that the papain-like cysteine protease RD21 (responsive-to-desiccation-21) is activated in response to PHS and FB1 in Arabidopsis cultured cells and leaves, respectively. Using two allelic null mutants of RD21, and two different PCD bioassays, we demonstrate that the protein acts as a negative regulator of FB1-induced cell death in Arabidopsis.

A biplot correlation range for group-wise metabolite selection in mass spectrometry

Background

Analytic methods are available to acquire extensive metabolic information in a cost-effective manner for personalized medicine, yet disease risk and diagnosis mostly rely upon individual biomarkers based on statistical principles of false discovery rate and correlation. Due to functional redundancies and multiple layers of regulation in complex biologic systems, individual biomarkers, while useful, are inherently limited in disease characterization. Data reduction and discriminant analysis tools such as principal component analysis (PCA), partial least squares (PLS), or orthogonal PLS (O-PLS) provide approaches to separate the metabolic phenotypes, but do not offer a statistical basis for selection of group-wise metabolites as contributors to metabolic phenotypes.

Methods

We present a dimensionality-reduction based approach termed ‘biplot correlation range (BCR)’ that uses biplot correlation analysis with direct orthogonal signal correction and PLS to provide the group-wise selection of metabolic markers contributing to metabolic phenotypes.

Results

Using a simulated multiple-layer system that often arises in complex biologic systems, we show the feasibility and superiority of the proposed approach in comparison of existing approaches based on false discovery rate and correlation. To demonstrate the proposed method in a real-life dataset, we used LC-MS based metabolomics to determine spectrum of metabolites present in liver mitochondria from wild-type (WT) mice and thioredoxin-2 transgenic (TG) mice. We select discriminatory variables in terms of increased score in the direction of class identity using BCR. The results show that BCR provides means to identify metabolites contributing to class separation in a manner that a statistical method by false discovery rate or statistical total correlation spectroscopy can hardly find in complex data analysis for predictive health and personalized medicine.

Electronic supplementary material

The online version of this article (10.1186/s13040-019-0191-2) contains supplementary material, which is available to authorized users.

Crosstalk between Fas and S1P1 signaling via NF-kB in osteoclasts controls bone destruction in the TMJ due to rheumatoid arthritis

Rheumatoid arthritis (RA) mainly affects various joints of the body, including the temporomandibular joint (TMJ), and it involves an infiltration of autoantibodies and inflammatory leukocytes into articular tissues and the synovium. Initially, the synovial lining tissue becomes engaged with several kinds of infiltrating cells, including osteoclasts, macrophages, lymphocytes, and plasma cells. Eventually, bone degradation occurs. In order to elucidate the best therapy for RA, a comprehensive study of RA pathogenesis needs to be completed. In this article, we discuss a Fas-deficient condition which develops into RA, with an emphasis on the role of sphingosine 1-phosphate (S1P)/S1P receptor 1 signaling which induces the migration of osteoclast precursor cells. We describe that Fas/S1P₁ signaling via NF-κB activation in osteoclasts is a key factor in TMJ-RA severity and we discuss a strategy for blocking nuclear translocation of the p50 NF-κB subunit as a potential therapy for attenuating osteoclastogenesis.