Serum metabolome and lipidome changes in adult patients with primary dengue infection

Dengue virus and lipid metabolism: unravelling the interplay for future therapeutic approaches

In recent years, Dengue virus (DENV) has continued to pose significant health risks in tropical and subtropical areas worldwide, raising health alerts worldwide. It can cause hyperviremia in humans and can even lead to fatal clinical diseases. The life cycle of DENV is intricately linked to cellular lipids, and the virus selectively utilizes relevant enzymes involved in lipid metabolism to modulate the existing metabolic system in host cells during entry, replication, assembly, and other stages, thereby creating an environment conducive to its complete replication cycle. At present, there is a lack of effective and specific anti-DENV treatment measures. This review summarizes the recently identified lipid metabolism molecules and metabolic related diseases that affect DENV infection, explores the dependence of DENV on lipid metabolism and provides potential targets for the treatment of dengue fever (DF).

The interaction of Orthoflavivirus nonstructural proteins 3 and 5 with human fatty acid synthase

Mosquito-transmitted viruses of the genus Orthoflavivirus impose a significant public health burden in many tropical and sub-tropical countries around the world, yet there is still no therapeutic drug to treat infection by any of these viruses, and so a deeper understanding of the mechanism of viral replication is required to identify potential therapeutic targets. Studies have shown that lipid metabolism is modulated upon virus infection, and that fatty acid synthase (FASN) is a key enzyme in fatty acid biosynthesis. In particular it has been reported that FASN interacts with DENV NS3 and is subsequently located to the replication complex. To further investigate this, the interaction of FASN with NS3 and NS5 of the Orthoflaviviruses dengue virus (DENV), Zika virus (ZIKV), and Japanese encephalitis virus (JEV) was investigated by coimmunoprecipitation and indirect immunofluorescent assay. Unexpectedly, FASN interacted with both NS3 and NS5 independently. The colocalization of NS3 and FASN was found for all investigated viruses, and while NS5 interacted with FASN, colocalization was not observed. Markedly however, FASN colocalized with dsRNA, a marker for the replication complex. FASN is an essential enzyme and plays a role in viral replication complex and cellular membrane remodelling. The interaction of FASN with both NS3 and NS5, as well as some of FASN being localized to the site of replication for DENV, JEV and ZIKV further highlights FASN as an important therapeutic target which may have applications to many mosquito-transmitted Orthoflaviviruses.

A global lipid map of severe fever with thrombocytopenia syndrome virus infection reveals glycerophospholipids as novel prognosis biomarkers

Severe fever with thrombocytopenia syndrome (SFTS) is a rapidly progressing infectious disease caused by a novel bunyavirus characterized by high fever, thrombocytopenia, and multiple organ damage. While lipids play an important role in viral infections, the specific alterations in lipid metabolism during SFTSV infection remain unclear. This study aimed to elucidate the global lipid metabolic profiles of SFTS patients with mild, severe, and fatal outcomes. A total of 60 SFTS patients, consisting of 30 mild, 15 severe and 15 fatal patients, and 30 healthy controls, were enrolled for the investigation of global lipidomics in serum using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Our findings revealed global alterations in the lipid signature induced by SFTSV infection and further confirmed that the glycerophospholipid metabolism pathway was profoundly affected during the progression of mild, severe, and fatal outcomes in SFTS patients. Importantly, LysoPC (20:0) and LysoPC (P-16:0) are strongly correlated with the clinical parameters of SFTSV infection. Furthermore, we demonstrated the substantial prognostic value of LysoPC (20:0) and LysoPC (P-16:0) by receiver operating characteristic (ROC) curve analysis, providing evidence for their remarkable value as prognostic biomarkers for predicting SFTS clinical outcomes. In particular, LysoPC (20:0) and LysoPC (P-16:0), along with APTT, yielded superior prognostic performance for fatal SFTS [area under the curve (AUC) = 98.4%], outperforming routine clinical parameters. Collectively, our findings revealed the lipidomic landscape after SFTSV infection, which offers new insights into the mechanisms of SFTS disease progression and suggests that targeting lipid metabolism may serve as a potential therapeutic strategy.

IMPORTANCE

This study systematically investigated the lipid landscape profile of SFTS-infected patients with different clinical outcomes. Our results revealed a global alteration in the lipid signature, particularly the glycerophospholipid metabolic pathway, induced by SFTSV infection. Notably, LysoPC (20:0) and LysoPC (P-16:0) presented remarkable prognostic value as novel biomarkers for SFTSV infection and may contribute to the prognosis of SFTS progression and appropriate interventions.

Analyzing how SiMiao Wan regulates ferroptosis to prevent RA-ILD using metabolomics and cyberpharmacology

BACKGROUND

Interstitial lung disease (ILD) is a common complication of rheumatoid arthritis (RA) that plays a significant role in the morbidity and mortality of individuals with this condition. In clinical settings, Si Miao Wan (SMW), a traditional Chinese medicine, is often utilized for the management of RA, as it is believed to possess properties that aid in reducing inflammation, eliminating excess moisture, and alleviating joint pain.

PURPOSE

The primary objective of this investigation was to elucidate the potential mechanism of RA-ILD prevention from the perspective of ferroptosis mediated by SMW.

METHODS

UPLC-Q-TOF/MS and network pharmacology were employed to forecast the potential targets of SMW for the early prevention of RA-ILD. Following this, HE staining, metabolomics, and RT-PCR were utilized to investigate the mechanism by which SMW prevents RA-ILD at an early stage.

RESULTS

Following six weeks of continuous administration of SMW extract at a dosage of 2.16 g/kg/day, it was observed that SMW exhibited early preventive effects against RA-ILD. Metabolomics analysis revealed seven potential biomarkers linked to the pharmacological efficacy of SMW in the early prevention of RA-ILD. Additionally, network pharmacology analysis suggested that SMW may exert its therapeutic effects on RA-ILD by modulating signaling pathways associated with lipid metabolism, atherosclerosis, TNF, and IL-17. Ultimately, through the integration of metabolomics and network pharmacology analysis, along with subsequent verification, it was determined that the early prevention of rheumatoid arthritis-associated interstitial lung disease (RA-ILD) by Shenmai injection (SMW) is associated with the ferroptosis pathway.

CONCLUSION

This research offers preliminary insights into the potential mechanism by which traditional Chinese medicine Shen Mai Wan (SMW) may mitigate the early onset of Rheumatoid Arthritis-Interstitial Lung Disease (RA-ILD) via the process of ferroptosis. Furthermore, it establishes a theoretical framework for the development of innovative SMW-based pharmaceuticals for the management of RA-ILD. The signal proteins implicated in this process are anticipated to emerge as crucial targets for the prevention of RA-ILD.

Metabolomic profiling of dengue infection: unraveling molecular signatures by LC-MS/MS and machine learning models

BACKGROUND & OBJECTIVE

The progression of dengue fever to severe dengue (SD) is a major public health concern that impairs the capacity of the medical system to predict and treat dengue patients. Hence, the present study used a metabolomic approach integrated with machine models to identify differentially expressed metabolites in patients with SD compared to nonsevere patients and healthy controls.

METHODS

Comprehensively, the plasma was collected at different clinical phases during dengue without warning signs (DWOW, N = 10), dengue with warning signs (DWW, N = 10), and SD (N = 10) at different stages [i.e., day of admission (DOA), day of defervescence (DOD), and day of convalescent (DOC)] in comparison to healthy control (HC). The samples were subjected to LC‒ESI‒MS/MS to identify metabolites. Statistical and machine learning analyses were performed using R and Python language. Further, biomarker, pathway and correlation analysis was performed to identify potential predictors of dengue.

RESULTS & CONCLUSION

A total of 423 metabolites were identified in all the study groups. Paired and unpaired t-tests revealed 14 highly differentially expressed metabolites between and across the dengue groups, with four metabolites (shikimic acid, ureidosuccinic acid, propionyl carnitine, and alpha-tocopherol) showing significant differences compared to HC. Furthermore, biomarker (ROC) analysis revealed 11 potential molecules with a significant AUC value of 1 that could serve as potential biomarkers for identifying different dengue clinical stages that are beneficial for predicting dengue disease outcomes. The logistic regression model revealed that S-adenosylhomocysteine, hypotaurine, and shikimic acid metabolites could be beneficial indicators for predicting severe dengue, with an accuracy and AUC of 0.75. The data showed that dengue infection is related to lipid metabolism, oxidative stress, inflammation, metabolomic adaptation, and virus manipulation. Moreover, the biomarkers had a significant correlation with biochemical parameters like platelet count, and hematocrit. These results shed some light on host-derived small-molecule biomarkers that are associated with dengue severity and novel insights into metabolomics mechanisms interlinked with disease severity.

Immunometabolites in viral infections: Action mechanism and function

The interplay between viral pathogens and host metabolism plays a pivotal role in determining the outcome of viral infections. Upon viral detection, the metabolic landscape of the host cell undergoes significant changes, shifting from oxidative respiration via the tricarboxylic acid (TCA) cycle to increased aerobic glycolysis. This metabolic shift is accompanied by elevated nutrient accessibility, which is vital for cell function, development, and proliferation. Furthermore, depositing metabolites derived from fatty acids, TCA intermediates, and amino acid catabolism accelerates the immunometabolic transition, facilitating pro-inflammatory and antimicrobial responses. Immunometabolites refer to small molecules involved in cellular metabolism regulating the immune response. These molecules include nutrients, such as glucose and amino acids, along with metabolic intermediates and signaling molecules adenosine, lactate, itaconate, succinate, kynurenine, and prostaglandins. Emerging evidence suggests that immunometabolites released by immune cells establish a complex interaction network within local niches, orchestrating and fine-tuning immune responses during viral diseases. However, our current understanding of the immense capacity of metabolites to convey essential cell signals from one cell to another or within cellular compartments remains incomplete. Unraveling these complexities would be crucial for harnessing the potential of immunometabolites in therapeutic interventions. In this review, we discuss specific immunometabolites and their mechanisms of action in viral infections, emphasizing recent findings and future directions in this rapidly evolving field.

Metabolomic landscape of macrophage discloses an anabolic signature of dengue virus infection and antibody-dependent enhancement of viral infection

Dengue virus (DENV) infection causes dengue fever, the most prevalent arthropod-transmitted viral disease worldwide. Viruses are acellular parasites and obligately rely on host cell machinery for reproduction. Previous studies have indicated metabolomic changes in endothelial cell models and sera of animal models and patients with dengue fever. To probe the immunometabolic mechanism of DENV infection, here, we report the metabolomic landscape of a human macrophage cell model of DENV infection and its antibody-dependent enhancement. DENV infection of THP-1-derived macrophages caused 202 metabolic variants, of which amino acids occupied 23.7%, fatty acids 21.78%, carbohydrates 10.4%, organic acids 13.37%, and carnitines 10.4%. These metabolomic changes indicated an overall anabolic signature, which was characterized by the global exhaustion of amino acids, increases of cellular fatty acids, carbohydrates and pentoses, but decreases of acylcarnitine. Significant activation of metabolic pathways of glycolysis, pentose phosphate, amino acid metabolism, and tricarboxylic acid cycle collectively support the overall anabolism to meet metabolic demands of DENV replication and immune activation by viral infection. Totally 88 of 202 metabolic variants were significantly changed by DENV infection, 36 of which met the statistical standard (P<0.05, VIP>1.5) of differentially expressed metabolites, which were the predominantly decreased variants of acylcarnitine and the increased variants of fatty acids and carbohydrates. Remarkably, 11 differentially expressed metabolites were significantly distinct between DENV only infection and antibody-dependent enhancement of viral infection. Our data suggested that the anabolic activation by DENV infection integrates the viral replication and anti-viral immune activation.

Metabolomic Changes in Rat Serum after Chronic Exposure to Glyphosate-Based Herbicide

Glyphosate-based herbicides (GBHs) have gained extensive popularity in recent decades. For many years, glyphosate has been regarded as harmless or minimally toxic to mammals due to the absence of its primary target, the shikimic acid pathway in humans. Nonetheless, mounting evidence suggests that glyphosate may cause adverse health effects in humans via other mechanisms. In this study, we described the metabolomic changes in the serum of experimental rats exposed to chronic GBH using the highly sensitive LC-MS/MS technique. We investigated the possible relationship between chronic exposure to GBH and neurological disorders. Our findings suggest that chronic exposure to GBH can alter spatial learning memory and the expression of some important metabolites that are linked to neurophysiological disorders in young rats, with the female rats showing higher susceptibility compared to the males. This indicates that female rats are more likely to show early symptoms of the disorder on exposure to chronic GBH compared to male rats. We observed that four important metabolites (paraxanthine, epinephrine, L-(+)-arginine, and D-arginine) showed significant changes and involvement in neurological changes as suggested by ingenuity pathway analysis. In conclusion, our results indicate that chronic exposure to GBH can increase the risk of developing neurological disorders.

Gut microbes consume host energy and reciprocally provide beneficial factors to sustain a symbiotic relationship with the host

The gut microbes thrive by utilizing host energy and, in return, provide valuable benefits, akin to the symbiotic relationship. To study the mutualistic association between the gut microbiota and host, a range of gut microbe populations (85 %, 66 %, 45 % and 38 % at the normal level) with comparable structures were constructed in broiler model. The results revealed that reductions in gut microbial population led to decreased energy consumption, resulting in increased host weight (10.26 %, 30.88 %, 17.65 % and - 12.77 %, respectively). Fecal metabolome revealed that among 85 % and 66 % of the normal population level, the gut microbes downregulated the immune-associated pathways of tryptophan metabolism and catecholamine biosynthesis, while the level of fatty acid oxidation was upregulated at 45 %. In the host, the concentration of gut microbes contributed to regulate functions related to lipid biosynthesis (from glycerophosphoserines to glycerophosphoethanolamines (9.63 %, 12.20 %, 6.66 % and 47.75 %) and glycerophosphocholines (10.78 %, 36.51 %, 2.00 % and 87.11 %)) and inflammation responses (methionine and betaine metabolism). From 85 % to 45 % of gut microbes, broiler showed an inhibited immunity (thymus gland, spleen, SIgG and IgA) and increased low-level inflammation response (ALT and T-SOD). However, at 38 %, the immune indexes exhibited an increase (thymus gland, spleen, SIgG, and IgA increased by 8.67 %, 8.50 %, 20.87 %, and 29.43 %, respectively), indicating the host lipid accumulation and inflammation response were negatively correlated with the immune reaction. Collectively, the gut microbiota maintains a symbiotic relationship with the host through the secretion of beneficial substances to interact with the host.

Flying under the radar - impact and factors influencing asymptomatic DENV infections

The clinical outcome of DENV and other Flaviviruses infections represents a spectrum of severity that ranges from mild manifestations to severe disease, which can ultimately lead to death. Nonetheless, most of these infections result in an asymptomatic outcome that may play an important role in the persistent circulation of these viruses. Also, although little is known about the mechanisms that lead to these asymptomatic infections, they are likely the result of a complex interplay between viral and host factors. Specific characteristics of the infecting viral strain, such as its replicating efficiency, coupled with host factors, like gene expression of key molecules involved in the immune response or in the protection against disease, are among crucial factors to study. This review revisits recent data on factors that may contribute to the asymptomatic outcome of the world's widespread DENV, highlighting the importance of silent infections in the transmission of this pathogen and the immune status of the host.

Serum sphingolipids aid in diagnosing adult HIV-negative patients with pulmonary cryptococcosis: a clinical cohort study

Background

Pulmonary cryptococcosis (PC) contributes to the ongoing global disease burden in human immunodeficiency virus (HIV)-negative populations. Since some PC patients are misdiagnosed under existing diagnostic guidelines, new diagnostic markers are needed to improve diagnostic accuracy and therapeutic efficacy and reduce disease risk.

Methods

Our previously established sphingolipidomic approach was employed to explore the use of serum sphingolipids (SPLs) in diagnosing HIV-negative patients with PC. A clinical cohort of PC, pulmonary aspergillosis (PA), and tuberculosis (TB) patients and healthy controls was assessed to identify SPL biomarkers.

Results

A total of 47 PC, 27 PA, and 18 TB patients and 40 controls were enrolled. PC and TB patients had similar clinical features, laboratory test results and radiological features, excluding plural effusion. The serum ceramide [Cer (d18:1/18:0)] level showed a significant increase in PC patients compared to controls and PA and TB patients (P<0.05). Cer (d18:1/18:0) was identified as a specific diagnostic biomarker for PC. The optimal cut-off value of greater than 18.00 nM showed a diagnostic sensitivity of 76.60% and a specificity of 95.00% and better distinguished PC patients from PA and TB patients. Furthermore, the serum Cer (d18:1/18:0) level gradually decreased after 3 and 6 months of treatment, suggesting the prediction potential for therapeutic efficacy of this biomarker. In addition, Cer (d18:1/18:0) analysis presented a higher sensitivity than the cryptococcal antigen (CrAg) assay.

Conclusions

This is the first study to report the use of the SPL Cer (d18:1/18:0) as a serum biomarker for diagnosing Cryptococcus spp. infection in HIV-negative patients.

Lipid signatures of West Nile virus infection unveil alterations of sphingolipid metabolism providing novel biomarkers

West Nile virus (WNV) is a neurotropic flavivirus transmitted by the bites of infected mosquitoes. Severe forms of West Nile disease (WND) can curse with meningitis, encephalitis or acute flaccid paralysis. A better understanding of the physiopathology associated with disease progression is mandatory to find biomarkers and effective therapies. In this scenario, blood derivatives (plasma and serum) constitute the more commonly used biofluids due to its ease of collection and high value for diagnostic purposes. Therefore, the potential impact of this virus in the circulating lipidome was addressed combining the analysis of samples from experimentally infected mice and naturally WND patients. Our results unveil dynamic alterations in the lipidome that define specific metabolic fingerprints of different infection stages. Concomitant with neuroinvasion in mice, the lipid landscape was dominated by a metabolic reprograming that resulted in significant elevations of circulating sphingolipids (ceramides, dihydroceramides and dihydrosphingomyelins), phosphatidylethanolamines and triacylglycerols. Remarkably, patients suffering from WND also displayed an elevation of ceramides, dihydroceramides, lactosylceramides and monoacylglycerols in their sera. The dysregulation of sphingolipid metabolism by WNV may provide new therapeutic opportunities and supports the potential of certain lipids as novel peripheral biomarkers of WND progression.

Prediction of human protein interactome of dengue virus non-structural protein 5 (NS5) and its downstream immunological implications

The non-structural protein 5 (NS5) is the most conserved protein among flaviviruses, a family that includes the dengue virus. It functions both as an RNA-dependent RNA polymerase and an RNA-methyltransferase and is therefore essential for the replication of viral RNA. The discovery that dengue virus NS5 protein (DENV-NS5) can also localize to the nucleus has resulted in renewed interest in its potential roles at the host-virus interface. In this study, we have used two complementary computational approaches in parallel - one based on linear motifs (ELM) and another based on tertiary structure of the protein (DALI) - to predict the host proteins that DENV-NS5 might interact with. Of the 42 human proteins predicted by both these methods, 34 are novel. Pathway analysis of these 42 human proteins shows that they are involved in key host cellular processes related to cell cycle regulation, proliferation, protein degradation, apoptosis, and immune responses. A focused analysis of transcription factors that directly interact with the predicted DENV-NS5 interacting proteins was performed, followed by the identification of downstream genes that are differentially expressed after dengue infection using previously published RNA-seq data. Our study provides unique insights into the DENV-NS5 interaction network and delineates mechanisms whereby DENV-NS5 could impact the host-virus interface. The novel interactors identified in this study could be potentially targeted by NS5 to modulate the host cellular environment in general, and the immune response in particular, thereby extending the role of DENV-NS5 beyond its known enzymatic functions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03569-0.

Comparative Analysis of Human Hepatic Lesions in Dengue, Yellow Fever, and Chikungunya: Revisiting Histopathological Changes in the Light of Modern Knowledge of Cell Pathology

Arboviruses, such as yellow fever virus (YFV), dengue virus (DENV), and chikungunya virus (CHIKV), present wide global dissemination and a pathogenic profile developed in infected individuals, from non-specific clinical conditions to severe forms, characterised by the promotion of significant lesions in different organs of the harbourer, culminating in multiple organ dysfunction. An analytical cross-sectional study was carried out via the histopathological analysis of 70 samples of liver patients, collected between 2000 and 2017, with confirmed laboratory diagnoses, who died due to infection and complications due to yellow fever (YF), dengue fever (DF), and chikungunya fever (CF), to characterise, quantify, and compare the patterns of histopathological alterations in the liver between the samples. Of the histopathological findings in the human liver samples, there was a significant difference between the control and infection groups, with a predominance of alterations in the midzonal area of the three cases analysed. Hepatic involvement in cases of YF showed a greater intensity of histopathological changes. Among the alterations evaluated, cell swelling, microvesicular steatosis, and apoptosis were classified according to the degree of tissue damage from severe to very severe. Pathological abnormalities associated with YFV, DENV, and CHIKV infections showed a predominance of changes in the midzonal area. We also noted that, among the arboviruses studied, liver involvement in cases of YFV infection was more intense.

Integrated clinical and metabolomic analysis of dengue infection shows molecular signatures associated with host-pathogen interaction in different phases of the disease

PURPOSE

Dengue is a mosquito vector-borne disease caused by the dengue virus, which affects 125 million people globally. The disease causes considerable morbidity. The disease, based on symptoms, is classified into three characteristic phases, which can further lead to complications in the second phase. Molecular signatures that are associated with the three phases have not been well characterized. We performed an integrated clinical and metabolomic analysis of our patient cohort and compared it with omics data from the literature to identify signatures unique to the different phases.

METHODS

The dengue patients are recruited by clinicians after standard-of-care diagnostic tests and evaluation of symptoms. Blood from the patients was collected. NS1 antigen, IgM, IgG antibodies, and cytokines in serum were analyzed using ELISA. Targeted metabolomics was performed using LC-MS triple quad. The results were compared with analyzed transcriptomic data from the GEO database and metabolomic data sets from the literature.

RESULTS

The dengue patients displayed characteristic features of the disease, including elevated NS1 levels. TNF-α was found to be elevated in all three phases compared to healthy controls. The metabolic pathways were found to be deregulated compared to healthy controls only in phases I and II of dengue patients. The pathways represent viral replication and host response mediated pathways. The major pathways include nucleotide metabolism of various amino acids and fatty acids, biotin, etc. CONCLUSION: The results show elevated TNF-α and metabolites that are characteristic of viral infection and host response. IL10 and IFN-γ were not significant, consistent with the absence of any complications.

Ebola virus-like particles reprogram cellular metabolism

Ebola virus can trigger a release of pro-inflammatory cytokines with subsequent vascular leakage and impairment of clotting finally leading to multiorgan failure and shock after entering and infecting patients. Ebola virus is known to directly target endothelial cells and macrophages, even without infecting them, through direct interactions with viral proteins. These interactions affect cellular mechanics and immune processes, which are tightly linked to other key cellular functions such as metabolism. However, research regarding metabolic activity of these cells upon viral exposure remains limited, hampering our understanding of its pathophysiology and progression. Therefore, in the present study, an untargeted cellular metabolomic approach was performed to investigate the metabolic alterations of primary human endothelial cells and M1 and M2 macrophages upon exposure to Ebola virus-like particles (VLP). The results show that Ebola VLP led to metabolic changes among endothelial, M1, and M2 cells. Differential metabolite abundance and perturbed signaling pathway analysis further identified specific metabolic features, mainly in fatty acid-, steroid-, and amino acid-related metabolism pathways for all the three cell types, in a host cell specific manner. Taken together, this work characterized for the first time the metabolic alternations of endothelial cells and two primary human macrophage subtypes after Ebola VLP exposure, and identified the potential metabolites and pathways differentially affected, highlighting the important role of those host cells in disease development and progression. KEY MESSAGES: • Ebola VLP can lead to metabolic alternations in endothelial cells and M1 and M2 macrophages. • Differential abundance of metabolites, mainly including fatty acids and sterol lipids, was observed after Ebola VLP exposure. • Multiple fatty acid-, steroid-, and amino acid-related metabolism pathways were observed perturbed.

Comprehensive Lipidomic Workflow for Multicohort Population Phenotyping Using Stable Isotope Dilution Targeted Liquid Chromatography-Mass Spectrometry

Dysregulated lipid metabolism underpins many chronic diseases including cardiometabolic diseases. Mass spectrometry-based lipidomics is an important tool for understanding mechanisms of lipid dysfunction and is widely applied in epidemiology and clinical studies. With ever-increasing sample numbers, single batch acquisition is often unfeasible, requiring advanced methods that are accurate and robust to batch-to-batch and interday analytical variation. Herein, an optimized comprehensive targeted workflow for plasma and serum lipid quantification is presented, combining stable isotope internal standard dilution, automated sample preparation, and ultrahigh performance liquid chromatography-tandem mass spectrometry with rapid polarity switching to target 1163 lipid species spanning 20 subclasses. The resultant method is robust to common sources of analytical variation including blood collection tubes, hemolysis, freeze-thaw cycles, storage stability, analyte extraction technique, interinstrument variation, and batch-to-batch variation with 820 lipids reporting a relative standard deviation of <30% in 1048 replicate quality control plasma samples acquired across 16 independent batches (total injection count = 6142). However, sample hemolysis of ≥0.4% impacted lipid concentrations, specifically for phosphatidylethanolamines (PEs). Low interinstrument variability across two identical LC-MS systems indicated feasibility for intra/inter-lab parallelization of the assay. In summary, we have optimized a comprehensive lipidomic protocol to support rigorous analysis for large-scale, multibatch applications in precision medicine. The mass spectrometry lipidomics data have been deposited to massIVE: data set identifiers MSV000090952 and 10.25345/C5NP1WQ4S.

Urine metabolomic characteristics of female patients with occupational chronic cadmium poisoning after 15 years of treatment

Occupational chronic cadmium poisoning (OCCP) can cause irreversible organ damage. Currently, no effective treatment is available for OCCP, and effective and sensitive biomarkers for treatment evaluation are still lacking. In this study, metabolomics techniques were used to analyze changes in endogenous metabolites in the urine of patients with OCCP after 15 years of treatment. Thirty urine samples from female patients with OCCP and healthy female controls (n = 15 per group) were assessed using gas chromatography-time-of-flight mass spectrometry and ultra-high-performance liquid chromatography-Q-Exactive mass spectrometry. The OCCP group had higher concentrations of blood urea nitrogen and urinary cadmium but near-normal urinary concentrations of β₂ -microglobulin and retinol-binding protein. Compared with the control group, the OCCP group had 66 significantly different metabolites with a variable importance in projection score >1 and p < 0.05. These differential metabolites were involved in various metabolic pathways, such as creatine metabolism, nicotinate and nicotinamide metabolism, the pentose phosphate pathway, d-glutamine and d-glutamate metabolism, and amino acid metabolism. Compared with the control group, the OCCP group had significantly higher urinary concentrations of creatine, glutamic acid, quinolinic acid and nicotinic acid. In a receiver operator characteristic analysis, the area under the curve of creatine was higher than those for glutamic acid, quinolinic acid and nicotinic acid, indicating that urinary concentrations of creatine could be used as a sensitive biomarker for the diagnosis and prognosis of OCCP and for monitoring its treatment.

Alterations in bile acids as metabolic signatures in the patients with human adenovirus type 7 infection

Objectives

The changes in metabolism by human adenovirus (HAdV) infection was unclear. The potential mechanism of HAdV-7 causing acute respiratory tract infection was explored.

Methods

Totally 35 patients with HAdV-7 infection, 32 asymptomatic cases with HAdV-7 and 14 healthy controls were enrolled from an outbreak of HAdV-7 in the army. The serum samples were analyzed by untargeted and targeted metabolomics. The effects of differential metabolites were verified on HAdV-7 replication in an A549 cell line.

Results

The untargeted metabolomics analysis revealed more significant changes in the classes of sphingolipids, polyketides, glycerolipids, fatty acyls, and carboxylic acids and their derivatives in the patients with HAdV-7 than in healthy controls. Two key metabolic pathways of secondary and primary bile acid biosynthesis were noted from pathway enrichment analysis. Targeted metabolomics analysis showed that the levels of unconjugated bile acids in the patients were significantly lower, while the levels of glyco- and tauro- conjugated bile acids in patients and asymptomatic cases were higher than those in the healthy controls. The profiles of cytokines and peripheral lymphocyte subsets obviously varied at different levels of bile acids, with significant differences after HAdV-7 infection. A cell verification test demonstrated that the replication of HAdV-7 significantly reduced when GCDCA and TCA were added.

Conclusion

Bile acids inhibited HAdV-7 replication in vitro. Alterations in bile acids was metabolic signatures of HAdV-7 infected subjects, and our results suggested bile acids might play protective roles against HAdV-7 infection.

Single-Cell Metabolic Profiling of Macrophages Using 3D OrbiSIMS: Correlations with Phenotype

Macrophages are important immune cells that respond to environmental cues acquiring a range of activation statuses represented by pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes at each end of their spectrum. Characterizing the metabolic signature (metabolic profiling) of different macrophage subsets is a powerful tool to understand the response of the human immune system to different stimuli. Here, the recently developed 3D OrbiSIMS instrument is applied to yield useful insight into the metabolome from individual cells after in vitro differentiation of macrophages into naïve, M1, and M2 phenotypes using different cytokines. This analysis strategy not only requires more than 6 orders of magnitude less sample than traditional mass spectrometry approaches but also allows the study of cell-to-cell variance. Characteristic metabolites in macrophage subsets are identified using a targeted lipid and data-driven multivariate approach highlighting amino acids and other small molecules. The diamino acids alanylasparagine and lipid sphingomyelin SM(d18/16:0) are uniquely found in M1 macrophages, while pyridine and pyrimidine are observed at increased intensity in M2 macrophages, findings which link to known biological pathways. The first demonstration of this capability illustrates the great potential of direct cell analysis for in situ metabolite profiling with the 3D OrbiSIMS to probe functional phenotype at the single-cell level using molecular signatures and to understand the response of the human body to implanted devices and immune diseases.

A global lipid map reveals host dependency factors conserved across SARS-CoV-2 variants

A comprehensive understanding of host dependency factors for SARS-CoV-2 remains elusive. Here, we map alterations in host lipids following SARS-CoV-2 infection using nontargeted lipidomics. We find that SARS-CoV-2 rewires host lipid metabolism, significantly altering hundreds of lipid species to effectively establish infection. We correlate these changes with viral protein activity by transfecting human cells with each viral protein and performing lipidomics. We find that lipid droplet plasticity is a key feature of infection and that viral propagation can be blocked by small-molecule glycerolipid biosynthesis inhibitors. We find that this inhibition was effective against the main variants of concern (alpha, beta, gamma, and delta), indicating that glycerolipid biosynthesis is a conserved host dependency factor that supports this evolving virus.

Metabolomic Profiling Reveals New Insight of Fowl Adenovirus Serotype 4 Infection

Highly pathogenic fowl adenovirus serotype 4 (FAdV-4) is the causative agent of hydropericardium syndrome (HPS), which is characterized by pericardial effusion and hepatitis, and is one of the foremost causes of economic losses to the poultry industry over the last 30 years. However, the metabolic changes in cells in response to FAdV-4 infection remain unclear. In order to understand the metabolic interactions between the host cell and virus, we utilized ultra-high-performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry to analyze the metabolic profiles with hepatocellular carcinoma cell line (LMH) infected with FAdV-4. The results showed that FAdV-4 could restore metabolic networks in LMH cells and tricarboxylic acid cycle, glycolysis, and metabolism of purines, pyrimidines, alanine, aspartate, glutamate, and amino sugar and nucleotide sugar moieties. Moreover, FAdV-4 production was significantly reduced in LMH cells cultured in glucose or glutamine-deficient medium. These observations highlighted the importance of host cell metabolism in virus replication. Therefore, similarities and disparities in FAdV-4-regulation of the metabolism of host cells could help improve targeted drug and reduce infection.

Review of -omics studies on mosquito-borne viruses of the Flavivirus genus

Arboviruses are transmitted by arthropods (arthropod-borne virus) which can be mosquitoes or other hematophagous arthropods, in which their life cycle occurs before transmission to other hosts. Arboviruses such as Dengue, Zika, Saint Louis Encephalitis, West Nile, Yellow Fever, Japanese Encephalitis, Rocio and Murray Valley Encephalitis viruses are some of the arboviruses transmitted biologically among vertebrate hosts by blood-taking vectors, mainly Aedes and Culex sp., and are associated with neurological, viscerotropic, and hemorrhagic reemerging diseases, posing as significant health and socioeconomic concern, as they become more and more adaptive to new environments, to arthropods vectors and human hosts. One of the main families that include mosquito-borne viruses is Flaviviridae, and here, we review the case of the Flavivirus genus, which comprises the viruses cited above, using a variety of research approaches published in literature, including genomics, transcriptomics, proteomics, metabolomics, etc., to better understand their structures as well as virus-host interactions, which are essential for development of future antiviral therapies.

Lipid Interactions Between Flaviviruses and Mosquito Vectors

Mosquito-borne flaviviruses, such as dengue (DENV), Zika (ZIKV), yellow fever (YFV), West Nile (WNV), and Japanese encephalitis (JEV) viruses, threaten a large part of the human populations. In absence of therapeutics and effective vaccines against each flaviviruses, targeting viral metabolic requirements in mosquitoes may hold the key to new intervention strategies. Development of metabolomics in the last decade opened a new field of research: mosquito metabolomics. It is now clear that flaviviruses rely on mosquito lipids, especially phospholipids, for their cellular cycle and propagation. Here, we review the biosyntheses of, biochemical properties of and flaviviral interactions with mosquito phospholipids. Phospholipids are structural lipids with a polar headgroup and apolar acyl chains, enabling the formation of lipid bilayer that form plasma- and endomembranes. Phospholipids are mostly synthesized through the de novo pathway and remodeling cycle. Variations in headgroup and acyl chains influence phospholipid physicochemical properties and consequently the membrane behavior. Flaviviruses interact with cellular membranes at every step of their cellular cycle. Recent evidence demonstrates that flaviviruses reconfigure the phospholipidome in mosquitoes by regulating phospholipid syntheses to increase virus multiplication. Identifying the phospholipids involved and understanding how flaviviruses regulate these in mosquitoes is required to design new interventions.

Unraveling the innate immune responses of Bombyx mori hemolymph, fat body, and midgut to Bombyx mori nucleopolyhedrovirus oral infection by metabolomic analysis

Bombyx mori nucleopolyhedrovirus (BmNPV) infection causes a series of physiological and pathological changes in Bombyx mori (B. mori). Here, a metabolomic study of the innate immunity organs including hemolymph, fat body, and midgut of the silkworm strain Dazao following BmNPV challenge was conducted to reveal the metabolic variations in B. mori. Compared to the control, 4964 and 4942 features with 4077 and 4327 high-quality features were generated under positive and negative modes, respectively, from BmNPV-infected larvae. The principal component analysis and supervised learning method using partial least squares discrimination analysis demonstrated good analytical stability and experimental reproducibility of the metabolic profiles. Based on database annotations, a total of 296, 108, and 215 differential expressed metabolites (DEMs) were identified from BmNPV-infected group of hemolymph, fat body, and midgut, respectively, which were all mainly grouped into carboxylic acids and derivatives, fatty acyls, and glycerophospholipids. Kyoto Encyclopedia of Genes and Genomes Database enrichment analysis of the DEMs showed that amino acid metabolism was increased at 24 h after BmNPV infection. BmNPV induction was adopted to significantly alter a series of immune-related pathways including phospholipase D signaling pathway, FoxO signaling pathway, metabolism of xenobiotics by cytochrome P450, melanogenesis, membrane transport, carbohydrate metabolism, and lipid metabolism. The different levels of expression of several DEMs including l-glutamate, naphthalene, 3-succinoylpyridine 1-acyl-sn-glycerol 3-phosphate, and l-tyrosine which were involved in those pathways exhibited the immune responses of B. mori to BmNPV infection. Our findings are valuable for a better understanding of the antiviral mechanism of B. mori underlying the interaction between the silkworm and BmNPV.

Serum Sphingolipids Aiding the Diagnosis of Adult HIV-Negative Patients with Talaromyces marneffei Infection

Increasing attention has been directed to Talaromyces marneffei (T. marneffei) infection in HIV-negative patients due to its high mortality rate. However, nonspecific symptoms and biological characteristics similar to those of other common pathogenic fungi complicate the rapid and accurate diagnosis of T. marneffei infection. Sphingolipids (SPLs) are bioactive lipids involved in the regulation of various physiological and pathological processes and have been identified as serum biomarkers for several diseases. This study employed a sphingolipidomic approach established in our previous work to explore the use of serum SPLs in the diagnosis of HIV-negative patients with T. marneffei infection. Additional clinical cohorts of patients infected with other microorganisms were also recruited. We found that sphinganine (Sa) (d16:0) exhibited obvious depletion after infection; moreover, its level in patients with T. marneffei infection was significantly lower than that in patients infected with other microorganisms. Therefore, Sa (d16:0) was considered a specific diagnostic biomarker for T. marneffei infection, and 302.71 nM was selected as the optimal cutoff value with a diagnostic sensitivity of 87.5% and specificity of 100%. These results suggested that determination of serum Sa (d16:0) levels can be used as a new alternative tool for the rapid diagnosis of T. marneffei infection in HIV-negative patients.

Multi-Omics Sequencing Provides Insights Into Age-Dependent Susceptibility of Grass Carp (Ctenopharyngodon idellus) to Reovirus

Grass carp (Ctenopharyngodon idellus) is an important aquaculture species in China that is affected by serious diseases, especially hemorrhagic disease caused by grass carp reovirus (GCRV). Grass carp have previously shown age-dependent susceptibility to GCRV, however, the mechanism by which this occurs remains poorly understood. Therefore, we performed transcriptome and metabolome sequencing on five-month-old (FMO) and three-year-old (TYO) grass carp to identify the potential mechanism. Viral challenge experiments showed that FMO fish were susceptible, whereas TYO fish were resistant to GCRV. RNA-seq showed that the genes involved in immune response, antigen presentation, and phagocytosis were significantly upregulated in TYO fish before the GCRV infection and at the early stage of infection. Metabolome sequencing showed that most metabolites were upregulated in TYO fish and downregulated in FMO fish after virus infection. Intragroup analysis showed that arachidonic acid metabolism was the most significantly upregulated pathway in TYO fish, whereas choline metabolism in cancer and glycerophospholispid metabolism were significantly downregulated in FMO fish after virus infection. Intergroup comparison revealed that metabolites from carbohydrate, amino acid, glycerophospholipid, and nucleotide metabolism were upregulated in TYO fish when compared with FMO fish. Moreover, the significantly differentially expressed metabolites showed antiviral effects both in vivo and in vitro. Based on these results, we concluded that the immune system and host biosynthesis and metabolism, can explain the age-dependent viral susceptibility in grass carp.

Metabolomics in infectious diseases and drug discovery

Metabolomics has emerged as an invaluable tool that can be used along with genomics, transcriptomics and proteomics to understand host-pathogen interactions at small-molecule levels. Metabolomics has been used to study a variety of infectious diseases and applications. The most common application of metabolomics is for prognostic and diagnostic purposes, specifically the screening of disease-specific biomarkers by either NMR-based or mass spectrometry-based metabolomics. In addition, metabolomics is of great significance for the discovery of druggable metabolic enzymes and/or metabolic regulators through the use of state-of-the-art flux analysis, for example, via the elucidation of metabolic mechanisms. This review discusses the application of metabolomics technologies to biomarker screening, the discovery of drug targets in infectious diseases such as viral, bacterial and parasite infections and immunometabolomics, highlights the challenges associated with accessing metabolite compartmentalization and discusses the available tools for determining local metabolite concentrations.

Infrared Spectroscopy of Blood

The magnitude of infectious diseases in the twenty-first century created an urgent need for point-of-care diagnostics. Critical shortages in reagents and testing kits have had a large impact on the ability to test patients with a suspected parasitic, bacteria, fungal, and viral infections. New point-of-care tests need to be highly sensitive, specific, and easy to use and provide results in rapid time. Infrared spectroscopy, coupled to multivariate and machine learning algorithms, has the potential to meet this unmet demand requiring minimal sample preparation to detect both pathogenic infectious agents and chronic disease markers in blood. This focal point article will highlight the application of Fourier transform infrared spectroscopy to detect disease markers in blood focusing principally on parasites, bacteria, viruses, cancer markers, and important analytes indicative of disease. Methodologies and state-of-the-art approaches will be reported and potential confounding variables in blood analysis identified. The article provides an up to date review of the literature on blood diagnosis using infrared spectroscopy highlighting the recent advances in this burgeoning field.

Methods of Lipidomic Analysis: Extraction, Derivatization, Separation, and Identification of Lipids

Lipidomics refers to the large-scale study of pathways and networks of cellular lipids in biological systems. A lipidomic analysis often involves the identification and quantification of the thousands of cellular lipid molecular species within a complex biological sample and therefore requires a well optimized method for lipid profiling. In this chapter, the methods for lipidomic analysis, including sample collection and preparation, lipid derivatization and separation, mass spectrometric identification of lipids, data processing and interpretation, and quality control, are overviewed.

Dengue and metabolomics in humans

BACKGROUND

Dengue virus causes dengue fever (DF)disease, transmitted by the mosquito Aedes aegypti. The symptoms could be severe and disable the affected individuals for weeks. The severe form, dengue hemorrhagic fever (DHF), can lead to death if not adequately attended to. Due to global warming, the vector mosquito will advance over new areas and expose more people to this disease over the next decades. Despite the severity, there are no treatments nor efficient vaccines available. Metabolomic studies have shown a new perspective to understand this disease better at a new molecular level.

AIM OF REVIEW

Many published works rely on samples obtained from animal studies. This review will mainly focus on human samples and cell culture experiments to view how the dengue virus affects the metabolomic profile.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The review compiles the sample sources, metabolomic techniques used, the detected compounds, and how they behave in different DF stages. This disease causes a significant change in many metabolites, but some results are still conflicting between studies. The results gathered here show that metabolomic approaches prove to be an excellent and viable way to expand knowledge about DF.

Lipid profiles and differential lipids in serum related to severity of community-acquired pneumonia: A pilot study

This study aimed to characterize the lipidomic responses to community-acquired pneumonia (CAP) and provide new insight into the underlying mechanisms of pathogenesis and potential avenues for diagnostic and therapeutic treatments. This study was performed from January 2017 to October 2018. Lipidomic profiles were generated using ultra high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) platform. Spearman's rank correlation test and multiple linear regression analysis were applied to explore the correlation between changes in the relative abundance of lipids and clinical parameters. Kaplan-Meier methods were used to build 30-day survival curves. From the UHPLC-MS/MS results, a total of 509 and 195 lipid species were detected in the positive and negative ionization mode respectively. Positive ionization covered six lipid classes (glycerol-phospholipids, glycerolipids, sphingolipids, sterol-lipids, prenol-lipids, and fatty acid), whilst negative ionization covered three (glycerol-phospholipids, sphingolipids, fatty acid). Four lipids were selected as targets: PC (16:0_18:1), PC (18:2_20:4), PC (36:4), and PC (38:6). The relative increase of the areas under the curves for all four lipids were superior to the pneumonia severity index and CURB-65 (confusion, urea, respiratory rate, blood pressure, and age ≥65 years old) for discriminating severe CAP from CAP. Decreasing relative levels of PC (18:2_20:4), PC (38:6), and PC (36:4) were negatively related to fraction of inspiration O2; Changes in the relative abundance of PC (16:0_18:1) and PC (18:2_20:4) had significantly linear relationship with procalcitonin. Patients with an elevated level of PC (16:0_18:1) had significantly longer duration of hospital stays. As the relative abundance of PC (18:2_20:4), PC (36:4), and PC (38:6) decreased, the length of hospitalization days and 30-day mortality rate increased significantly (all log-rank p<0.05). Therefore, using the UHPLC-MS/MS platform's serum lipidomic approach can help reveal changes in lipid abundance during CAP and establish lipid profiles related to disease severity.

Insights into the molecular basis of tick-borne encephalitis from multiplatform metabolomics

Background

Tick-borne encephalitis virus (TBEV) is the most prevalent arbovirus, with a tentative estimate of 10,000 to 10,500 infections occurring in Europe and Asia every year. Endemic in Northeast China, tick-borne encephalitis (TBE) is emerging as a major threat to public health, local economies and tourism. The complicated array of host physiological changes has hampered elucidation of the molecular mechanisms underlying the pathogenesis of this disease.

Methodology/Principle findings

System-level characterization of the serum metabolome and lipidome of adult TBEV patients and a healthy control group was performed using liquid chromatography tandem mass spectrometry. By tracking metabolic and lipid changes during disease progression, crucial physiological changes that coincided with disease stages could be identified. Twenty-eight metabolites were significantly altered in the sera of TBE patients in our metabolomic analysis, and 14 lipids were significantly altered in our lipidomics study. Among these metabolites, alpha-linolenic acid, azelaic acid, D-glutamine, glucose-1-phosphate, L-glutamic acid, and mannose-6-phosphate were altered compared to the control group, and PC(38:7), PC(28:3;1), TAG(52:6), etc. were altered based on lipidomics. Major perturbed metabolic pathways included amino acid metabolism, lipid and oxidative stress metabolism (lipoprotein biosynthesis, arachidonic acid biosynthesis, leukotriene biosynthesis and sphingolipid metabolism), phospholipid metabolism and triglyceride metabolism. These metabolites were significantly perturbed during disease progression, implying their latent utility as prognostic markers.

Conclusions/Significance

TBEV infection causes distinct temporal changes in the serum metabolome and lipidome, and many metabolites are potentially involved in the acute inflammatory response and immune regulation. Our global analysis revealed anti- and pro-inflammatory processes in the host and changes to the entire metabolic profile. Relationships between metabolites and pathologies were established. This study provides important insight into the pathology of TBE, including its pathology, and lays the foundation for further research into putative markers of TBE disease.

Tick-borne encephalitis virus (TBEV) with extreme contagiousness is a key danger to public health systems in Europe and Asia. To date, little information is obtained about the molecular mechanism underlying infection, and although commercial vaccines against TBEV exist, there is no specific treatment for the disease. Metabolomics and lipidomics offer multiple-visions of metabolome and lipidome sights and help elucidating metabolic to disease phenotype. Serum metabolism and lipidome analysis were performed based on mass spectrometer (MS) platform on a cohort of TBEV patients. About 400 metabolites performed crucial shifts in TBEV patients compared with healthy subjects. This study revealed that in the stage of infection, the host metabolome is tightly regulated, with anti-inflammatory processes modulating pro-inflammatory processes implying the self-limiting phenotype of TBEV and the inherent regulation in humans. The crucial perturbed metabolic pathways contained amino acid metabolism, fatty acid metabolism and phospholipid metabolism. This study provides a powerful and new approach to decipher the interactions between host and virus. These potential metabolites provide high sensitivity and specificity and have the capacity to function as biomarkers for disease surveillance and estimation of therapeutic interventions.

Exometabolomic Analysis of Decidualizing Human Endometrial Stromal and Perivascular Cells

Differentiation of endometrial fibroblasts into specialized decidual cells controls embryo implantation and transforms the cycling endometrium into a semi-permanent, immune-protective matrix that accommodates the placenta throughout pregnancy. This process starts during the midluteal phase of the menstrual cycle with decidual transformation of perivascular cells (PVC) surrounding the terminal spiral arterioles and endometrial stromal cells (EnSC) underlying the luminal epithelium. Decidualization involves extensive cellular reprogramming and acquisition of a secretory phenotype, essential for coordinated placental trophoblast invasion. Secreted metabolites are an emerging class of signaling molecules, collectively known as the exometabolome. Here, we used liquid chromatography-mass spectrometry to characterize and analyze time-resolved changes in metabolite secretion (exometabolome) of primary PVC and EnSC decidualized over 8 days. PVC were isolated using positive selection of the cell surface marker SUSD2. We identified 79 annotated metabolites differentially secreted upon decidualization, including prostaglandin, sphingolipid, and hyaluronic acid metabolites. Secreted metabolites encompassed 21 metabolic pathways, most prominently glycerolipid and pyrimidine metabolism. Although temporal exometabolome changes were comparable between decidualizing PVC and EnSC, 32 metabolites were differentially secreted across the decidualization time-course. Further, targeted metabolomics demonstrated significant differences in secretion of purine pathway metabolites between decidualized PVC and EnSC. Taken together, our findings indicate that the metabolic footprints generated by different decidual subpopulations encode spatiotemporal information that may be important for optimal embryo implantation.

Sphingolipidomics in Translational Sepsis Research-Biomedical Considerations and Perspectives

Scientific Background: Sphingolipids are a highly diverse group of lipids with respect to physicochemical properties controlling either structure, distribution, or function, all of them regulating cellular response in health and disease. Mass spectrometry, on the other hand, is an analytical technique characterizing ionized molecules or fragments thereof by mass-to-charge ratios, which has been prosperingly developed for rapid and reliable qualitative and quantitative identification of lipid species. Parallel to best performance of in-depth chromatographical separation of lipid classes, preconditions of precise quantitation of unique molecular species by preprocessing of biological samples have to be fulfilled. As a consequence, “lipid profiles” across model systems and human individuals, esp. complex (clinical) samples, have become eminent over the last couple of years due to sensitivity, specificity, and discriminatory capability. Therefore, it is significance to consider the entire experimental strategy from sample collection and preparation, data acquisition, analysis, and interpretation.

Areas Covered: In this review, we outline considerations with clinical (i.e., human) samples with special emphasis on sample handling, specific physicochemical properties, target measurements, and resulting profiling of sphingolipids in biomedicine and translational research to maximize sensitivity and specificity as well as to provide robust and reproducible results. A brief commentary is also provided regarding new insights of “clinical sphingolipidomics” in translational sepsis research.

Expert Opinion: The role of mass spectrometry of sphingolipids and related species (“sphingolipidomics”) to investigate cellular and compartment-specific response to stress, e.g., in generalized infection and sepsis, is on the rise and the ability to integrate multiple datasets from diverse classes of biomolecules by mass spectrometry measurements and metabolomics will be crucial to fostering our understanding of human health as well as response to disease and treatment.

Saliva NMR-Based Metabolomics in the War Against COVID-19

COVID-19 is an emergent, worldwide public health concern. Joint efforts have been made by scientific communities of various fields to better understand the mechanisms of action of SARS-CoV-2. The need to understand the pathophysiological fingerprint and pathways of this disease make metabolomics-related approaches an indispensable tool for properly answering concerns relating to disease course. Determination of the metabolomic profile may help to explain the heterogeneous spectra of COVID-19 clinical phenotypes and be useful in monitoring disease progression as well as therapeutic treatments. In this sense, saliva has proven to be a strategic biofluid, owing not only to its appeal as a noninvasive sampling method but also due to the capacity of the virus to invade epithelial cells of the oral mucosa and salivary gland ducts via ACE2 receptors. Accordingly, important changes in metabolism have been described relating to COVID-19, indicating that metabolomics may open new avenues for understanding the pathophysiology of this disease, especially via longitudinal study designs. Thus, we discuss the importance of comprehending the SARS-CoV-2 salivary metabolomic fingerprint and also highlight the situation of Brazil on the frontlines of the war against COVID-19.

Integrative Metabolomics to Identify Molecular Signatures of Responses to Vaccines and Infections

Approaches to the identification of metabolites have progressed from early biochemical pathway evaluation to modern high-dimensional metabolomics, a powerful tool to identify and characterize biomarkers of health and disease. In addition to its relevance to classic metabolic diseases, metabolomics has been key to the emergence of immunometabolism, an important area of study, as leukocytes generate and are impacted by key metabolites important to innate and adaptive immunity. Herein, we discuss the metabolomic signatures and pathways perturbed by the activation of the human immune system during infection and vaccination. For example, infection induces changes in lipid (e.g., free fatty acids, sphingolipids, and lysophosphatidylcholines) and amino acid pathways (e.g., tryptophan, serine, and threonine), while vaccination can trigger changes in carbohydrate and bile acid pathways. Amino acid, carbohydrate, lipid, and nucleotide metabolism is relevant to immunity and is perturbed by both infections and vaccinations. Metabolomics holds substantial promise to provide fresh insight into the molecular mechanisms underlying the host immune response. Its integration with other systems biology platforms will enhance studies of human health and disease.

Immunotherapy of COVID-19 with poly (ADP-ribose) polymerase inhibitors: starting with nicotinamide

COVID-19 induces a proinflammatory environment that is stronger in patients requiring intensive care. The cytokine components of this environment may determine efficacy or otherwise of glucocorticoid therapy. The immunity modulators, the aryl hydrocarbon receptor (AhR) and the nuclear NAD+-consuming enzyme poly (ADP-ribose) polymerase 1 (PARP 1) may play a critical role in COVID-19 pathophysiology. The AhR is overexpressed in coronaviruses, including COVID-19 and, as it regulates PARP gene expression, the latter is likely to be activated in COVID-19. PARP 1 activation leads to cell death mainly by depletion of NAD+ and adenosine triphosphate (ATP), especially when availability of these energy mediators is compromised. PARP expression is enhanced in other lung conditions: the pneumovirus respiratory syncytial virus (RSV) and chronic obstructive pulmonary disease (COPD). I propose that PARP 1 activation is the terminal point in a sequence of events culminating in patient mortality and should be the focus of COVID-19 immunotherapy. Potent PARP 1 inhibitors are undergoing trials in cancer, but a readily available inhibitor, nicotinamide (NAM), which possesses a highly desirable biochemical and activity profile, merits exploration. It conserves NAD+ and prevents ATP depletion by PARP 1 and Sirtuin 1 (silent mating type information regulation 2 homologue 1) inhibition, enhances NAD+ synthesis, and hence that of NADP+ which is a stronger PARP inhibitor, reverses lung injury caused by ischaemia/reperfusion, inhibits proinflammatory cytokines and is effective against HIV infection. These properties qualify NAM for therapeutic use initially in conjunction with standard clinical care or combined with other agents, and subsequently as an adjunct to stronger PARP 1 inhibitors or other drugs.

Lipid hijacking: a unifying theme in vector-borne diseases

Vector-borne illnesses comprise a significant portion of human maladies, representing 17% of global infections. Transmission of vector-borne pathogens to mammals primarily occurs by hematophagous arthropods. It is speculated that blood may provide a unique environment that aids in the replication and pathogenesis of these microbes. Lipids and their derivatives are one component enriched in blood and are essential for microbial survival. For instance, the malarial parasite Plasmodium falciparum and the Lyme disease spirochete Borrelia burgdorferi, among others, have been shown to scavenge and manipulate host lipids for structural support, metabolism, replication, immune evasion, and disease severity. In this Review, we will explore the importance of lipid hijacking for the growth and persistence of these microbes in both mammalian hosts and arthropod vectors.

Mosquito metabolomics reveal that dengue virus replication requires phospholipid reconfiguration via the remodeling cycle

Dengue virus (DENV) subdues cell membranes for its cellular cycle by reconfiguring phospholipids in humans and mosquitoes. Here, we determined how and why DENV reconfigures phospholipids in the mosquito vector. By inhibiting and activating the de novo phospholipid biosynthesis, we demonstrated the antiviral impact of de novo-produced phospholipids. In line with the virus hijacking lipids for its benefit, metabolomics analyses indicated that DENV actively inhibited the de novo phospholipid pathway and instead triggered phospholipid remodeling. We demonstrated the early induction of remodeling during infection by using isotope tracing in mosquito cells. We then confirmed in mosquitoes the antiviral impact of de novo phospholipids by supplementing infectious blood meals with a de novo phospholipid precursor. Eventually, we determined that phospholipid reconfiguration was required for viral genome replication but not for the other steps of the virus cellular cycle. Overall, we now propose that DENV reconfigures phospholipids through the remodeling cycle to modify the endomembrane and facilitate formation of the replication complex. Furthermore, our study identified de novo phospholipid precursor as a blood determinant of DENV human-to-mosquito transmission.

Influenza virus infection affects insulin signaling, fatty acid-metabolizing enzyme expressions, and the tricarboxylic acid cycle in mice

Although the severity of influenza virus infections has been associated with host energy metabolism, the related mechanisms have not yet been clarified. Here we examined the effects of influenza virus infection on host energy metabolism in mice. After infecting mice with intranasal applications of 500 plaque-forming units of A/Puerto Rico/8/34 (H1N1; PR8) virus, the serum levels of most intermediates in the tricarboxylic acid (TCA) cycle and related metabolic pathways were significantly reduced. These data suggest that substrate supply to the TCA cycle is reduced under these conditions, rather than specific metabolic reactions being inhibited. Then, we focused on glucose and fatty acid metabolism that supply substrates to the TCA cycle. Akt phosphorylation following insulin injections was attenuated in the livers of PR8 virus-infected mice. Furthermore, glucose tolerance tests revealed that the PR8 virus-infected mice showed higher blood glucose levels than the vehicle-inoculated control mice. These results suggest that influenza virus infection impairs insulin signaling, which regulates glucose uptake. However, increases in the hepatic expressions of fatty acid-metabolizing enzymes suggest that fatty acids accumulate in liver cells of infected mice. Collectively, our data indicate that influenza virus infection dysregulates host energy metabolism. This line of investigation provides novel insights into the pathogenesis of influenza.

Single Cell Metabolomics: A Future Tool to Unmask Cellular Heterogeneity and Virus-Host Interaction in Context of Emerging Viral Diseases

Viral emergence is an unpredictable but obvious event, particularly in the era of climate change and globalization. Efficient management of viral outbreaks depends on pre-existing knowledge and alertness. The potential hotspots of viral emergence often remain neglected and the information related to them is insufficient, particularly for emerging viruses. Viral replication and transmission rely upon usurping the host metabolic machineries. So altered host metabolic pathways can be exploited for containment of these viruses. Metabolomics provides the insight for tracing out such checkpoints. Consequently introspection of metabolic alteration at virus-host interface has evolved as prime area in current virology research. Chromatographic separation followed by mass spectrometry has been used as the predominant analytical platform in bulk of the analyses followed by nuclear magnetic resonance (NMR) and fluorescence based techniques. Although valuable information regarding viral replication and modulation of host metabolic pathways have been extracted but ambiguity often superseded the real events due to population effect over the infected cells. Exploration of cellular heterogeneity and differentiation of infected cells from the nearby healthy ones has become essential. Single cell metabolomics (SCM) emerges as necessity to explore such minute details. Mass spectrometry imaging (MSI) coupled with several soft ionization techniques such as electrospray ionization (ESI), laser ablation electrospray ionization (LAESI), matrix assisted laser desorption/ionization (MALDI), matrix-free laser desorption ionization (LDI) have evolved as the best suited platforms for SCM analyses. The potential of SCM has already been exploited to resolve several biological conundrums. Thus SCM is knocking at the door of virus-host interface.

Metabolomics and lipidomics study unveils the impact of polybrominated diphenyl ether-47 on breast cancer mice

Polybrominated diphenyl ether-47 (BDE-47) is a congener of polybrominated diphenyl ethers (PBDEs) and relates to different health risks. However, in vivo study of the association between BDE-47 and breast cancer was scarce. In this study, we performed in vivo exposure of BDE-47 to breast cancer nude mice and conducted mass spectrometry-based metabolomics and lipidomics analysis to investigate the metabolic changes in mice. Results showed that the tumor sizes were positively associated with the dosage of BDE-47. Metabolomics and lipidomics profiling analysis indicated that BDE-47 induced significant alterations of metabolic pathways in livers, including glutathione metabolism, ascorbate and aldarate metabolism, and lipids metabolism, etc. The upregulations of phosphatidylcholines (PCs) and phosphatidylethanolamines (PEs) suggested the membrane remodeling, and the downregulations of Lyso-PCs and Lyso-PEs might be associated with the tumor growth. Targeted metabolomics analysis revealed that BDE-47 inhibited fatty acid β-oxidation (FAO) and induced incomplete FAO. The inhibition of FAO and downregulation of PPARγ would contribute to inflammation, which could promote tumor growth. In addition, BDE-47 elevated the expression of the cytokines TNFRSF12A, TNF-α, IL-1β and IL-6, and lowered the cytokines SOCS3 and the nuclear receptor PPARα. The changes of cytokines and receptor may contribute to the tumor growth of mice.

Vaginal metabolome: towards a minimally invasive diagnosis of microbial invasion of the amniotic cavity in women with preterm labor

Microbial invasion of the amniotic cavity (MIAC) is only identified by amniocentesis, an invasive procedure that limits its clinical translation. Here, we aimed to evaluate whether the vaginal metabolome discriminates the presence/absence of MIAC in women with preterm labor (PTL) and intact membranes. We conducted a case-control study in women with symptoms of PTL below 34 weeks who underwent amniocentesis to discard MIAC. MIAC was defined as amniotic fluid positive for microorganisms identified by specific culture media. The cohort included 16 women with MIAC and 16 control (no MIAC). Both groups were matched for age and gestational age at admission. Vaginal fluid samples were collected shortly after amniocentesis. Metabolic profiles were analyzed by nuclear magnetic resonance (NMR) spectroscopy and compared using multivariate and univariate statistical analyses to identify significant differences between the two groups. The vaginal metabolomics profile of MIAC showed higher concentrations of hypoxanthine, proline, choline and acetylcholine and decreased concentrations of phenylalanine, glutamine, isoleucine, leucine and glycerophosphocholine. In conclusion, metabolic changes in the NMR-based vaginal metabolic profile are able to discriminate the presence/absence of MIAC in women with PTL and intact membranes. These metabolic changes might be indicative of enhanced glycolysis triggered by hypoxia conditions as a consequence of bacterial infection, thus explaining the utilization of alternative energy sources in an attempt to replenish glucose.

Interventional effects of the direct application of "Sanse powder" on knee osteoarthritis in rats as determined from lipidomics via UPLC-Q-Exactive Orbitrap MS

BACKGROUND

Our previous clinical evidence suggested that the direct application of "Sanse powder" the main ingredient of "Yiceng" might represent an alternative treatment for knee osteoarthritis. However, the mechanism underlying its effect is poorly understood. In this study, we investigated the mechanism of the effect of direct "Sanse powder" application for the treatment of knee osteoarthritis (KOA) in rats by using lipidomics.

METHODS

KOA rats were established by cutting the anterior cruciate ligament, and the cold pain threshold and mechanical withdrawal threshold (MWT) of seven rats from each group were measured before modelling (0 days) and at 7, 14, 21 and 28 days after modelling. Histopathological evaluation of the synovial tissue was performed by haematoxylin and eosin (H&E) staining after modelling for 28 days. Interleukin-1β (IL-1β), pro-interleukin-1β (pro-IL-1β) and tumor necrosis factor-α (TNF-α) proteins in synovial tissue were measured by western blot, and the mRNA expression levels of IL-1β and TNF-α in synovial tissue were measured using Real-time reverse transcription polymerase chain reaction (qRT-PCR), the levels of IL-1β and TNF-α in rat serum were measured by enzyme-linked immunosorbent assay (ELISA), Serum lipid profiles were obtained by using ultra-performance liquid chromatography combined with quadrupole-Exactive Orbitrap mass spectrometry (UPLC-Q-Exactive Orbitrap MS).

RESULTS

The results confirmed that the direct application of "Sanse powder" had a significant protective effect against KOA in rats. Treatment with "Sanse powder" not only attenuated synovial tissue inflammation but also increased the levels of the cold pain threshold and MWT. In addition, the lipidomics results showed that the levels of diacylglycerol (DAG), triacylglycerols (TAGs), lysophosphatidylcholine (LPC), phosphatidylcholine (PC), fatty acid esters of hydroxy fatty acids (FAHFAs), and phosphatidylethanolamine (PE) were restored almost to control levels following treatment.

CONCLUSIONS

Lipidomics provides a better understanding of the actions of direct application "Sanse powder" therapy for KOA.