The Many Facets of Sphingolipids in the Specific Phases of Acute Inflammatory Response

Ceramide releases exosomes with a specific miRNA signature for cell differentiation

Exosomes are well established effectors of cell-cell communication. Their role on maturation of embryonic cells located in hippocampus, seat of memory, is unknown. Here we show that ceramide facilitates release of exosomes from HN9.10e cells extending information for cell differentiation to neighboring cells. We found only 38 miRNAs differentially expressed in exosomes derived from ceramide-treated cells in comparison with control cells (including 10 up-regulated and 28 down-regulated). Some overexpressed miRNAs (mmu-let-7f-1-3p, mmu-let-7a-1-3p, mmu-let-7b-3p, mmu-let-7b-5p, mmu-miR-330-3p) regulate genes encoding for protein involved in biological, homeostatic, biosynthetic and small molecule metabolic processes, embryo development and cell differentiation, all phenomena relevant for HN9.10e cell differentiation. Notably, the overexpressed mmu-let-7b-5p miRNA appears to be important for our study based on its ability to regulate thirty-five gene targets involved in many processes including sphingolipid metabolism, sphingolipid-related stimulation of cellular functions and neuronal development. Furthermore, we showed that by incubating embryonic cells with exosomes released under ceramide treatment, some cells acquired an astrocytic phenotype and others a neuronal phenotype. We anticipate our study to be a start point for innovative therapeutic strategies to regulate the release of exosomes useful to stimulate delayed brain development in the newborn and to improve the cognitive decline in neurodegenerative disorders.

Anticeramide Improves Sjögren's Syndrome by Blocking BMP6-Induced Th1

T-cell dysfunction has been shown to play an important role in the pathogenesis of Sjögren's syndrome (SS). In recent studies, the increased expression of BMP6 has been reported to be related to SS. However, the roles that BMP6 plays in immune homeostasis in the development of SS as well as the downstream signals activated by BMP6 remain unclear. In this study, we investigated the effects and molecular mechanisms of BMP6 on naive CD4⁺ T cells, showing that BMP6 could upregulate interferon (IFN)-γ secretion from CD4⁺ T cells through a ceramide/nuclear factor-κB pathway, with no effect on T-cell activation or proliferation. Moreover, an in vivo study showed that anticeramide treatment (myriocin) for an SS animal model (NOD/LtJ mice) could significantly decrease the IFN-γ expression and Th1 frequency in the salivary glands and suppress the inflammation infiltration in salivary glands and maintain the salivary flow rates, both of which reflect SS-like symptoms. This study identifies a promising target that could effectively attenuate the abnormal state of CD4⁺ T cells and reverse the progression of SS.

Glycosphingolipids in Diabetes, Oxidative Stress, and Cardiovascular Disease: Prevention in Experimental Animal Models

Diabetes contributes to about 30% morbidity and mortality world-wide and has tidal wave increases in several countries in Asia. Diabetes is a multi-factorial disease compounded by inflammation, dyslipidemia, atherosclerosis, and is sometimes accompanied with gains in body weight. Sphingolipid pathways that interplay in the enhancement of the pathology of this disease may be potential therapeutic targets. Thus, the application of advanced sphingolipidomics may help predict the progression of this disease and therapeutic outcomes in man. Pre-clinical studies using various experimental animal models of diabetes provide valuable information on the role of sphingolipid signaling networks in diabetes and the efficacy of drugs to determine the translatability of innovative discoveries to man. In this review, we discuss three major concepts regarding sphingolipids and diabetes. First, we discuss a possible involvement of a monosialodihexosylceramide (GM3) in insulin-insulin receptor interactions. Second, a potential role for ceramide (Cer) and lactosylceramide (LacCer) in apoptosis and mitochondrial dysfunction is proposed. Third, a larger role of LacCer in antioxidant status and inflammation is discussed. We also discuss how inhibitors of glycosphingolipid synthesis can ameliorate diabetes in experimental animal models.

Frontloading of stress response genes enhances robustness to environmental change in chimeric corals

Background

Chimeras are genetically mixed entities resulting from the fusion of two or more conspecifics. This phenomenon is widely distributed in nature and documented in a variety of animal and plant phyla. In corals, chimerism initiates at early ontogenic states (larvae to young spat) and results from the fusion between two or more closely settled conspecifics. When compared to genetically homogenous colonies (non-chimeras), the literature has listed ecological and evolutionary benefits for traits at the chimeric state, further positioning coral chimerism as an evolutionary rescue instrument. However, the molecular mechanisms underlying this suggestion remain unknown.

Results

To address this question, we developed field monitoring and multi-omics approaches to compare the responses of chimeric and non-chimeric colonies acclimated for 1 year at 10-m depth or exposed to a stressful environmental change (translocation from 10- to 2-m depth for 48h). We showed that chimerism in the stony coral Stylophora pistillata is associated with higher survival over a 1-year period. Transcriptomic analyses showed that chimeras lose transcriptomic plasticity and constitutively express at higher level (frontload) genes responsive to stress. This frontloading may prepare the colony to face at any time environmental stresses which explain its higher robustness.

Conclusions

These results show that chimeras are environmentally robust entities with an enhanced ability to cope with environmental stress. Results further document the potential usefulness of chimeras as a novel reef restoration tool to enhance coral adaptability to environmental change, and confirm that coral chimerism can be an evolutionary rescue instrument.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01371-7.

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.

Development of a Novel Sphingolipid Signaling Pathway-Related Risk Assessment Model to Predict Prognosis in Kidney Renal Clear Cell Carcinoma

This study aimed to explore underlying mechanisms by which sphingolipid-related genes play a role in kidney renal clear cell carcinoma (KIRC) and construct a new prognosis-related risk model. We used a variety of bioinformatics methods and databases to complete our exploration. Based on the TCGA database, we used multiple R-based extension packages for data transformation, processing, and statistical analyses. First, on analyzing the CNV, SNV, and mRNA expression of 29 sphingolipid-related genes in various types of cancers, we found that the vast majority were protective in KIRC. Subsequently, we performed cluster analysis of patients with KIRC using sphingolipid-related genes and successfully classified them into the following three clusters with significant prognostic differences: Cluster 1, Cluster 2, and Cluster 3. We performed differential analyses of transcription factor activity, drug sensitivity, immune cell infiltration, and classical oncogenes to elucidate the unique roles of sphingolipid-related genes in cancer, especially KIRC, and provide a reference for clinical treatment. After analyzing the risk rates of sphingolipid-related genes in KIRC, we successfully established a risk model composed of seven genes using LASSO regression analysis, including SPHK1, CERS5, PLPP1, SGMS1, SGMS2, SERINC1, and KDSR. Previous studies have suggested that these genes play important biological roles in sphingolipid metabolism. ROC curve analysis results showed that the risk model provided good prediction accuracy. Based on this risk model, we successfully classified patients with KIRC into high- and low-risk groups with significant prognostic differences. In addition, we performed correlation analyses combined with clinicopathological data and found a significant correlation between the risk model and patient’s M, T, stage, grade, and fustat. Finally, we developed a nomogram that predicted the 5-, 7-, and 10-year survival in patients with KIRC. The model we constructed had strong predictive ability. In conclusion, we believe that this study provides valuable data and clues for future studies on sphingolipid-related genes in KIRC.

Impacts of Enriched Human Milk Cells on Fecal Metabolome and Gut Microbiome of Premature Infants with Stage I Necrotizing Enterocolitis: A Pilot Study

SCOPE

Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality in preterm infants, occurring more often in formula-fed infants than in breastfed infants. Recent animal studies have shown that cells in fresh breast milk survive in the newborns' digestive tract. However, no clinical studies have been conducted on the effects of human milk cells, and their biological roles in the infants' intestines remain unexplored.

METHODS AND RESULTS

Twenty premature infants are enrolled. Cells from fresh milk of their own mothers are enriched and fed to infants with Bell's Stage I NEC once a day for 7 days since the onset of NEC. Fecal samples are collected at enrollment and 2 weeks later. Fecal sphingolipids are observed to be enriched in NEC patients and positively correlated with calprotectin levels. After intervention with enriched human milk cells, inflammation-associated sphingolipids and microbiome profiles are altered and resembled those of the controls.

CONCLUSION

These preliminary findings reveal the potential impacts of enriched human milk cells on premature infants with Bell's Stage I NEC and provide insight into the roles of fecal sphingolipid metabolism in the neonates' intestinal inflammation. However, the limited sample size of the study indicates the need for further investigation.

Who moves the sphinx? An overview of intracellular sphingolipid transport

Lipid bilayers function as boundaries that enclose their content from the surrounding media, and the composition of different membrane types is accurately and dynamically tailored so that they can perform their function. To achieve this balance, lipid biosynthetic machinery and lipid trafficking events are intertwined into an elegant network. In this review, we focus on the intracellular movement of sphingolipids mediated by sphingolipid transfer proteins. Additionally, we will focus on the best characterized and understood mammalian sphingolipid transfer proteins and provide an overview of how they are hypothesized to function. Some are already well understood, while others remain enigmatic. A few are actual lipid transfer proteins, moving lipids from membrane to membrane, while others may have more of a sensor role, possibly reacting to changes in the concentrations of their ligands. Considering the substrates available for cytosolic sphingolipid transfer proteins, one open question that is discussed is whether galactosylceramide is a target. Another question is the exact mechanics by which sphingolipid transfer proteins are targeted to different organelles, such as how four phosphate adapter protein-2, FAPP2 is targeted to the endoplasmic reticulum. The aim of this review is to discuss what is known within the field today and to provide a basic understanding of how these proteins may work.

Metabolic Reprogramming-A New Era How to Prevent and Treat Graft Versus Host Disease After Allogeneic Hematopoietic Stem Cell Transplantation Has Begun

Allogeneic hematopoietic stem cell transplantation (HSCT) is the solitary therapeutic therapy for many types of hematological cancers. The benefits of this procedure are challenged by graft vs. host disease (GVHD), causing significant morbidity and mortality. Recent advances in the metabolomics field have revolutionized our understanding of complex human diseases, clinical diagnostics and allow to trace the de novo biosynthesis of metabolites. There is growing evidence for metabolomics playing a role in different aspects of GVHD, and therefore metabolomic reprogramming presents a novel tool for this disease. Pre-transplant cytokine profiles and metabolic status of allogeneic transplant recipients is shown to be linked with a threat of acute GVHD. Immune reactions underlying the pathophysiology of GVHD involve higher proliferation and migration of immune cells to the target site, requiring shifts in energy supply and demand. Metabolic changes and reduced availability of oxygen result in tissue and cellular hypoxia which is extensive enough to trigger transcriptional and translational changes. T cells, major players in acute GVHD pathophysiology, show increased glucose uptake and glycolytic activity. Effector T (Teff) cells activated during nutrient limiting conditions in vitro or multiplying during GVHD in vivo, depend more on oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO). Dyslipidemia, such as the increase of medium and long chain fatty and polyunsaturated acids in plasma of GVHD patients, has been observed. Sphingolipids associate with inflammatory conditions and cancer. Chronic GVHD (cGVHD) patients show reduced branched-chain amino acids (BCAAs) and increased sulfur-containing metabolites post HSCT. Microbiota-derived metabolites such as aryl hydrocarbon receptor (AhR) ligands, bile acids, plasmalogens and short chain fatty acids vary significantly and affect allogeneic immune responses during acute GVHD. Considering the multitude of possibilities, how altered metabolomics are involved in GVHD biology, multi-timepoints related and multivariable biomarker panels for prognosticating and understanding GVHD are needed. In this review, we will discuss the recent work addressing metabolomics reprogramming to control GVHD in detail.

Antifungal Drug Development: Targeting the Fungal Sphingolipid Pathway

Fungal infections are becoming more prevalent and problematic due to the continual rise of immune deficient patients as well as the progressive development of drug resistance towards currently available antifungal drugs. There has been a significant increase in the development of antifungal compounds with a similar mechanism of action of current drugs. In contrast, there has been very little progress in developing compounds inhibiting totally new fungal targets or/and fungal pathways. This review focuses on novel compounds recently discovered to target the fungal sphingolipids and their metabolizing enzymes.

Steryl Glycosides in Fungal Pathogenesis: An Understudied Immunomodulatory Adjuvant

Invasive fungal infections pose an increasing threat to human hosts, especially in immunocompromised individuals. In response to the increasing morbidity and mortality of fungal infections, numerous groups have shown great strides in uncovering novel treatment options and potential efficacious vaccine candidates for this increasing threat due to the increase in current antifungal resistance. Steryl glycosides are lipid compounds produced by a wide range of organisms, and are largely understudied in the field of pathogenicity, especially to fungal infections. Published works over the years have shown these compounds positively modulating the host immune response. Recent advances, most notably from our lab, have strongly indicated that steryl glycosides have high efficacy in protecting the host against lethal Cryptococcal infection through acting as an immunoadjuvant. This review will summarize the keystone studies on the role of steryl glycosides in the host immune response, as well as elucidate the remaining unknown characteristics and future perspectives of these compounds for the host-fungal interactions.

Plasma Lipidomic Analyses in Cohorts With mTBI and/or PTSD Reveal Lipids Differentially Associated With Diagnosis and APOE ε4 Carrier Status

The differential diagnosis between mild Traumatic Brain Injury (mTBI) sequelae and Post-Traumatic Stress Disorder (PTSD) is challenging due to their symptomatic overlap and co-morbidity. As such, there is a need to develop biomarkers which can help with differential diagnosis of these two conditions. Studies from our group and others suggest that blood and brain lipids are chronically altered in both mTBI and PTSD. Therefore, examining blood lipids presents a minimally invasive and cost-effective approach to identify promising biomarkers of these conditions. Using liquid chromatography-mass spectrometry (LC-MS) we examined hundreds of lipid species in the blood of healthy active duty soldiers (n = 52) and soldiers with mTBI (n = 21), PTSD (n = 34) as well as co-morbid mTBI and PTSD (n = 13) to test whether lipid levels were differentially altered with each. We also examined if the apolipoprotein E (APOE) ε4 allele can affect the association between diagnosis and peripheral lipid levels in this cohort. We show that several lipid classes are altered with diagnosis and that there is an interaction between diagnosis and the ε4 carrier status on these lipids. Indeed, total lipid levels as well as both the degree of unsaturation and chain lengths are differentially altered with diagnosis and ε4 status, specifically long chain unsaturated triglycerides (TG) and both saturated and mono-unsaturated diglycerides (DG). Additionally, an examination of lipid species reveals distinct profiles in each diagnostic group stratified by ε4 status, mainly in TG, saturated DG species and polyunsaturated phosphatidylserines. In summary, we show that peripheral lipids are promising biomarker candidates to assist with the differential diagnosis of mTBI and PTSD. Further, ε4 carrier status alone and in interaction with diagnosis has a strong influence on peripheral lipid levels. Therefore, examining ε4 status along with peripheral lipid levels could help with differential diagnosis of mTBI and PTSD.

Lysosomal Ceramide Metabolism Disorders: Implications in Parkinson's Disease

Ceramides are a family of bioactive lipids belonging to the class of sphingolipids. Sphingolipidoses are a group of inherited genetic diseases characterized by the unmetabolized sphingolipids and the consequent reduction of ceramide pool in lysosomes. Sphingolipidoses include several disorders as Sandhoff disease, Fabry disease, Gaucher disease, metachromatic leukodystrophy, Krabbe disease, Niemann Pick disease, Farber disease, and GM2 gangliosidosis. In sphingolipidosis, lysosomal lipid storage occurs in both the central nervous system and visceral tissues, and central nervous system pathology is a common hallmark for all of them. Parkinson’s disease, the most common neurodegenerative movement disorder, is characterized by the accumulation and aggregation of misfolded α-synuclein that seem associated to some lysosomal disorders, in particular Gaucher disease. This review provides evidence into the role of ceramide metabolism in the pathophysiology of lysosomes, highlighting the more recent findings on its involvement in Parkinson’s disease.

SILAC-based quantitative proteomics reveals pleiotropic, phenotypic modulation in primary murine macrophages infected with the protozoan pathogen Leishmania donovani

Leishmaniases are major vector-borne tropical diseases responsible for great human morbidity and mortality, caused by protozoan, trypanosomatid parasites of the genus Leishmania. In the mammalian host, parasites survive and multiply within mononuclear phagocytes, especially macrophages. However, the underlying mechanisms by which Leishmania spp. affect their host are not fully understood. Herein, proteomic alterations of primary, bone marrow-derived BALB/c macrophages are documented after 72 h of infection with Leishmania donovani insect-stage promastigotes, applying a SILAC-based, quantitative proteomics approach. The protocol was optimised by combining strong anion exchange and gel electrophoresis fractionation that displayed similar depth of analysis (combined total of 6189 mouse proteins). Our analyses revealed 86 differentially modulated proteins (35 showing increased and 51 decreased abundance) in response to Leishmania donovani infection. The proteomics results were validated by analysing the abundance of selected proteins. Intracellular Leishmania donovani infection led to changes in various host cell biological processes, including primary metabolism and catabolic process, with a significant enrichment in lysosomal organisation. Overall, our analysis establishes the first proteome of bona fide primary macrophages infected ex vivo with Leishmania donovani, revealing new mechanisms acting at the host/pathogen interface. SIGNIFICANCE: Little is known on proteome changes that occur in primary macrophages after Leishmania donovani infection. This study describes a SILAC-based quantitative proteomics approach to characterise changes of bone marrow-derived macrophages infected with L. donovani promastigotes for 72 h. With the application of SILAC and the use of SAX and GEL fractionation methods, we have tested new routes for proteome quantification of primary macrophages. The protocols developed here can be applicable to other diseases and pathologies. Moreover, this study sheds important new light on the "proteomic reprogramming" of infected macrophages in response to L. donovani promastigotes that affects primary metabolism, cellular catabolic processes, and lysosomal/vacuole organisation. Thus, our study reveals key molecules and processes that act at the host/pathogen interface that may inform on new immuno- or chemotherapeutic interventions to combat leishmaniasis.

Bacterial immunogenic α-galactosylceramide identified in the murine large intestine: dependency on diet and inflammation

The glycosphingolipid, α-galactosylceramide (αGalCer), when presented by CD1d on antigen-presenting cells, efficiently activates invariant natural killer T (iNKT) cells. Thereby, it modulates immune responses against tumors, microbial and viral infections, and autoimmune diseases. Recently, the production of αGalCer by Bacteroidetes from the human gut microbiome was elucidated. Using hydrophilic interaction chromatography coupled to MS², we screened murine intestinal tracts to identify and quantify αGalCers, and we investigated the αGalCer response to different dietary and physiologic conditions. In both the cecum and the colon of mice, we found 1-15 pmol of αGalCer per milligram of protein; in contrast, mice lacking microbiota (germ-free mice) and fed identical diet did not harbor αGalCer. The identified αGalCer contained a β(R)-hydroxylated hexadecanoyl chain N-linked to C18-sphinganine, which differed from what has been reported with Bacteroides fragilis Unlike β-anomeric structures, but similar to αGalCers from B. fragilis, the synthetic form of the murine αGalCer induced iNKT cell activation in vitro. Last, we observed a decrease in αGalCer production in mice exposed to conditions that alter the composition of the gut microbiota, including Western type diet, colitis, and influenza A virus infection. Collectively, this study suggests that αGalCer is produced by commensals in the mouse intestine and reveals that stressful conditions causing dysbiosis alter its synthesis. The consequences of this altered production on iNKT cell-mediated local and systemic immune responses are worthy of future studies.

Association between specific plasma ceramides and high-sensitivity C-reactive protein levels in postmenopausal women with type 2 diabetes

AIM

Emerging evidence suggests that specific plasma ceramides are involved in the pathophysiology of cardiovascular disease (CVD) and other inflammation-associated diseases. However, scarce information is currently available on the association between distinct plasma ceramides (that have been associated with increased cardiovascular morbidity and mortality) and plasma high-sensitivity C-reactive protein (hs-CRP) concentrations in patients with type 2 diabetes mellitus (T2DM), a group of individuals at high risk of developing CVD and other chronic inflammation-related conditions.

METHODS

We measured six previously identified high-risk plasma ceramide species [Cer(d18:1/16:0), Cer(d18:1/18:0), Cer(d18:1/20:0), Cer(d18:1/22:0), Cer(d18:1/24:0), Cer(d18:1/24:1)] in 92 postmenopausal women with T2DM attending the diabetes outpatient service over a 3-month period. Plasma ceramide levels were measured using targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay.

RESULTS

Plasma hs-CRP levels were positively associated with all measured ceramides in univariable linear regression analyses. However, only plasma Cer(d18:1/16:0) (standard β coefficient: 0.27, P=0.015), Cer(d18:1/22:0) (standard β coefficient: 0.25, P=0.032) and Cer(d18:1/24:1) (standard β coefficient: 0.30, P=0.007) remained significantly associated with increased plasma hs-CRP levels after adjusting for age, adiposity measures, diabetes duration, HbA_1c, insulin resistance, smoking, hypertension, plasma LDL cholesterol, estimated glomerular filtration rate, preexisting ischaemic heart disease and use of lipid-lowering, antihypertensive, antiplatelet or hypoglycaemic drugs.

CONCLUSION

In postmenopausal women with T2DM, elevated levels of specific plasma ceramides are associated with higher plasma hs-CRP levels independent of established cardiovascular risk factors, diabetes-related variables and other potential confounding factors.

[The role of sphingolipids in cardiovascular pathologies]

Cardiovascular diseases (CVD) remain the leading cause of death in industrialized countries. One of the most significant risk factors for atherosclerosis is hypercholesterolemia. Its diagnostics is based on routine lipid profile analysis, including the determination of total cholesterol, low and high density lipoprotein cholesterol, and triglycerides. However in recent years, much attention has been paid to the crosstalk between the metabolic pathways of the cholesterol and sphingolipids biosynthesis. Sphingolipids are a group of lipids, containing a molecule of aliphatic alcohol sphingosine. These include sphingomyelins, cerebrosides, gangliosides and ceramides, sphingosines, and sphingosine-1-phosphate (S-1-P). It has been found that catabolism of sphingolipids is associated with catabolism of cholesterol. However, the exact mechanism of this interaction is still unknown. Particular attention as CVD inducer attracts ceramide (Cer). Lipoprotein aggregates isolated from atherosclerotic pluques are enriched with Cer. The level of Cer and sphingosine increases after ischemia reperfusion of the heart, in the infarction zone and in the blood, and also in hypertension. S-1-P exhibits pronounced cardioprotective properties. Its content sharply decreases with ischemia and myocardial infarction. S-1-P presents predominantly in HDL, and influences their multiple functions. Increased levels of Cer and sphingosine and decreased levels of S-1-P formed in the course of coronary heart disease can be an important factor in the development of atherosclerosis. It is proposed to use determination of sphingolipids in blood plasma as markers for early diagnosis of cardiac ischemia and for hypertension in humans. There are intensive studies aimed at correction of metabolism S-1-P. The most successful drugs are those that use S-1-P receptors as a targets, since all of its actions are receptor-mediated.

The Potential Antipyretic Mechanism of Gardeniae Fructus and Its Heat-Processed Products With Plasma Metabolomics Using Rats With Yeast-Induced Fever

Gardeniae Fructus (GF), prepared GF (GFP), and carbonized GF (GFC) are widely used in China for the treatment of fever. However, the involved antipyretic mechanism has not been fully elucidated. In this study, rectal temperature and pyrogenic cytokines were used to evaluate the antipyretic effect of raw and processed GF in rats with dry-yeast-induced pyrexia. Reverse phase and hydrophilic interaction liquid chromatography and ultra-high-performance liquid chromatography/mass spectrometry were used to acquire the metabolomics profile of GF, GFP, and GFC in rats with pyrexia. The results showed that the rectal temperature of rats treated with GF, GFP, and GFC was suppressed after 6 h (P < 0.05), compared with that observed in pyrexia model rats. The enzyme-linked immunosorbent assay showed that the expression of tumor necrosis factor α and interleukin 6 were suppressed by GF, GFP, and GFC. Moreover, GFC suppressed the expression of interleukin 6 significantly (P < 0.01). Of note, 11, 15, and 25 feature metabolites were identified in the GF, GFP, and GFC groups. Pathway analysis showed that GF mainly regulated the biosynthesis of valine, leucine, and isoleucine. Notably, GFP was involved in glycerophospholipid metabolism, while GFC was linked to glycerophospholipid and sphingolipid metabolism. These results suggested that GF, GFP, and GFC maintained their antipyretic effect despite heat processing. However, heat processing altered endogenous feature metabolites and certain pathways of GF, GFP, and GFC in rats with yeast-induced pyrexia to exert an antipyretic effect.

Metabolomics analysis of a mouse model for chronic exposure to ambient PM2.5

Chronic ambient fine particulate matter (PM_2.5) exposure correlates with various adverse health outcomes. Its impact on the circulating metabolome-a comprehensive functional readout of the interaction between an organism's genome and environment-has not however been fully understood. This study thus performed metabolomics analyses using a chronic PM_2.5 exposure mouse model. C57Bl/6J mice (female) were subjected to inhalational concentrated ambient PM_2.5 (CAP) or filtered air (FA) exposure for 10 months. Their sera were then analyzed by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS). These analyses identified 2570 metabolites in total, and 148 of them were significantly different between FA- and CAP-exposed mice. The orthogonal partial least-squares discriminant analysis (OPLS-DA) and heatmap analyses displayed evident clustering of FA- and CAP-exposed samples. Pathway analyses identified 6 perturbed metabolic pathways related to amino acid metabolism. In contrast, biological characterization revealed that 71 differential metabolites were related to lipid metabolism. Furthermore, our results showed that CAP exposure increased stress hormone metabolites, 18-oxocortisol and 5a-tetrahydrocortisol, and altered the levels of circadian rhythm biomarkers including melatonin, retinal and 5-methoxytryptophol.

Non-alcoholic fatty liver disease: Insights from sphingolipidomics

Non-alcoholic fatty liver disease (NAFLD) is a major clinical concern and its treatment consumes abundant resources. While accumulation of lipids in hepatocytes initiates the disease, this in itself is not necessarily harmful; rather, initiation of inflammation and subsequent fibrosis and cirrhosis are critical steps in NAFLD pathology. Mechanisms linking lipid overload to downstream disease progression are not fully understood; however, bioactive lipid metabolism may underlie instigation of proinflammatory signaling. With the advent of high-throughput, sensitive, and quantitative mass spectrometry-based methods for assessing lipid profiles in NAFLD, several trends have emerged, including that increases in specific sphingolipids correlate with the transition from the relatively benign condition of simple fatty liver to the much more concerning inflamed state. Continued studies that implement sphingolipid profiling will enable the extrapolations of candidate enzymes and pathways involved in NAFLD, either in biopsies or plasma from human samples, and also in animal models, from which data are much more abundant. While most data thus far are derived from targeted lipidomics approaches, unbiased, semi-quantitative approaches hold additional promise for furthering our understanding of sphingolipids as markers of and players in NAFLD.