Glycomic Analysis Reveals That Sialyltransferase Inhibition Is Involved in the Antiviral Effects of Arbidol.

Due to the high mutation rate of influenza virus and the rapid increase of drug resistance, it is imperative to discover host-targeting antiviral agents with broad-spectrum antiviral activity. Considering the discrepancy between the urgent demand of antiviral drugs during an influenza pandemic and the long-term process of drug discovery and development, it is feasible to explore host-based antiviral agents and strategies from antiviral drugs on the market. In the current study, the antiviral mechanism of arbidol (ARB), a broad-spectrum antiviral drug with potent activity at early stages of viral replication, was investigated from the aspect of hemagglutinin (HA) receptors of host cells. N-glycans that act as the potential binding receptors of HA on 16-human bronchial epithelial (16-HBE) cells were comprehensively profiled for the first time by using an in-depth glycomic approach based on TiO2-PGC chip-Q-TOF MS. Their relative levels upon the treatment of ARB and virus were carefully examined by employing an ultra-high sensitive qualitative method based on Chip LC-QQQ MS, showing that ARB treatment led to significant and extensive decrease of sialic acid (SA)-linked N-glycans (SA receptors), and thereby impaired the virus utilization on SA receptors for rolling and entry. The SA-decreasing effect of ARB was demonstrated to result from its inhibitory effect on sialyltransferases (ST), ST3GAL4 and ST6GAL1 of 16-HBE cells. Silence of STs, natural ST inhibitors, as well as sialidase treatment of 16-HBE cells, resulted in similar potent antiviral activity, whereas ST-inducing agent led to the diminished antiviral effect of ARB. These observations collectively suggesting the involvement of ST inhibition in the antiviral effect of ARB. IMPORTANCE This study revealed, for the first time, that ST inhibition and the resulted destruction of SA receptors of host cells may be an underlying mechanism for the antiviral activity of ARB. ST inhibition has been proposed as a novel host-targeting antiviral approach recently and several compounds are currently under exploration. ARB is the first antiviral drug on the market that was found to possess ST inhibiting function. This will provide crucial evidence for the clinical usages of ARB, such as in combination with neuraminidase (NA) inhibitors to exert optimized antiviral effect, etc. More importantly, as an agent that can inhibit the expression of STs, ARB can serve as a novel lead compound for the discovery and development of host-targeting antiviral drugs.

CERS4 predicts positive anti-PD-1 response and promotes immunomodulation through Rhob-mediated suppression of CD8+Tim3+ exhausted T cells in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) is one of the main malignant tumors with high mortality and short survival time. Immunotherapy has become the standard treatment for advanced NSCLC, but it has the problems of drug resistance and low response rate. Therefore, obtaining effective biomarkers to predict and enhance immune checkpoint inhibitors (ICIs) efficacy in NSCLC is important. Sphingolipid metabolism is recently found to be closely involved in tumor immunotherapy. CERS4, an important sphingolipid metabolizing enzyme, is positively correlated with the efficacy of anti-PD-1 therapy for NSCLC. Upregulation of CERS4 expression could improve the efficacy of anti-PD-1 therapy for NSCLC. High expression of CERS4 could downregulate the expression of Rhob in tumor. Significantly, the ratio of CD4+/CD8+ T cell increased and the ratio of Tim-3+/CD8+ T cell decreased in spleen and peripheral blood cells. When Rhob was knocked out, the efficacy of PD-1 mAb treatment increased, and the frequency of Tim-3+ CD8+ T cell decreased. This finding further confirmed the role of sphingolipid metabolites in regulating the immunotherapeutic function of NSCLC. These metabolites may improve the efficacy of PD-1 mAb in NSCLC by regulating the CERS4/Rhob/Tim-3 axis. Overall, this study provided a potential and effective target for predicting and improving the efficacy of ICIs for NSCLC. It also provided a new perspective for the study on the mechanisms of ICIs resistance for NSCLC.

Comprehensive Glycomic Profiling of Respiratory Tract Tissues of Tree Shrews by TiO2-PGC Chip Mass Spectrometry.

Due to its relatively small size, homology to humans, and susceptibility to human viruses, the tree shrew becomes an ideal alternative animal model for the study of human viral infectious diseases. However, there is still no report for the comprehensive glycan profile of the respiratory tract tissues in tree shrews. In this study, we characterized the structural diversity of N-glycans in the respiratory tract of tree shrews using our well-established TiO2-PGC chip-Q-TOF-MS method. As a result, a total of 219 N-glycans were identified. Moreover, each identified N-glycan was quantitated by a high sensitivity and accurate MRM method, in which 13C-labeled internal standards were used to correct the inherent run-to-run variation in MS detection. Our results showed that the N-glycan composition in the turbinate and lung was significantly different from the soft palate, trachea, and bronchus. Meanwhile, 28 high-level N-glycans in turbinate were speculated to be correlated with the infection of H1N1 virus A/California/04/2009. This study is the first to reveal the comprehensive glycomic profile of the respiratory tract of tree shrews. Our results also help to better understand the role of glycan receptors in human influenza infection and pathogenesis.

LC-MS based sphingolipidomic study on A549 human lung adenocarcinoma cell line and its taxol-resistant strain.

BACKGROUND: Resistance to chemotherapy drugs (e.g. taxol) has been a major obstacle in successful cancer treatment. In A549 human lung adenocarcinoma, acquired resistance to the first-line chemotherapy taxol has been a critical problem in clinics. Sphingolipid (SPL) controls various aspects of cell growth, survival, adhesion, and motility in cancer, and has been gradually regarded as a key factor in drug resistance. To better understand the taxol-resistant mechanism, a comprehensive sphingolipidomic approach was carried out to investigate the sphingolipid metabolism in taxol-resistant strain of A549 cell (A549T). METHODS: A549 and A549T cells were extracted according to the procedure with optimal condition for SPLs. Sphingolipidomic analysis was carried out by using an UHPLC coupled with quadrupole time-of-flight (Q-TOF) MS system for qualitative profiling and an UHPLC coupled with triple quadrupole (QQQ) MS system for quantitative analysis. The differentially expressed sphingolipids between taxol-sensitive and -resistant cells were explored by using multivariate analysis. RESULTS: Based on accurate mass and characteristic fragment ions, 114 SPLs, including 4 new species, were clearly identified. Under the multiple reaction monitoring (MRM) mode of QQQ MS, 75 SPLs were further quantified in both A549 and A549T. Multivariate analysis explored that the levels of 57 sphingolipids significantly altered in A549T comparing to those of A549 (p < 0.001 and VIP > 1), including 35 sphingomyelins (SMs), 14 ceramides (Cers), 3 hexosylceramides (HexCers), 4 lactosylceramides (LacCers) and 1 sphingosine. A significant decrease of SM and Cer levels and overall increase of HexCer and LacCer represent the major SPL metabolic characteristic in A549T. CONCLUSIONS: This study investigated sphingolipid profiles in human lung adenocarcinoma cell lines, which is the most comprehensive sphingolipidomic analysis of A549 and A549T. To some extent, the mechanism of taxol-resistance could be attributed to the aberrant sphingolipid metabolism, "inhibition of the de novo synthesis pathway" and "activation of glycosphingolipid pathway" may play the dominant role for taxol-resistance in A549T. This study provides insights into the strategy for clinical diagnosis and treatment of taxol resistant lung cancer.

Improved sphingolipidomic approach based on ultra-high performance liquid chromatography and multiple mass spectrometries with application to cellular neurotoxicity.

The emerging field of sphingolipidomics calls for accurate quantitative analyses of sphingolipidome. Existing analytical methods for sphingolipid (SPL) profiling often suffer from isotopic/isomeric interference, leading to the low-abundance, but biologically important SPLs being undetected. In the current study, we have developed an improved sphingolipidomic approach for reliable and sensitive quantification of up to 10 subclasses of cellular SPLs. By integratively utilizing high efficiency chromatographic separation, quadrupole time-of-flight (Q-TOF) and triple quadrupole (QQQ) mass spectrometry (MS), our approach facilitated unambiguous identification of several groups of potentially important but low-abundance SPLs that are usually masked by isotopic/isomeric species and hence largely overlooked in many published methods. The methodology, which featured a modified sample preparation and optimized MS parameters, permitted the measurement of 86 individual SPLs in PC12 cells in a single run, demonstrating great potential for high throughput analysis. The improved characterization, along with increased sensitivity for low-abundance SPL species, resulted in the highest number of SPLs being quantified in a single run in PC12 cells. The improved method was fully validated and applied to a lipidomic study of PC12 cell samples with or without amyloid ß peptide (Aß) treatment, which presents a most precise and genuine sphingolipidomic profile of the PC12 cell line. The adoption of the metabolomics protocol, as described in this study, could avoid misidentification and bias in the measurement of the analytically challenging low-abundance endogenous SPLs, hence achieving informative and reliable sphingolipidomics data relevant to discovery of potential SPL biomarkers for Aß-induced neurotoxicity and neurodegenerative disease.

Quantitative analysis of the flavonoid glycosides and terpene trilactones in the extract of Ginkgo biloba and evaluation of their inhibitory activity towards fibril formation of ß-amyloid peptide.

The standard extract of Ginkgo biloba leaves (EGb761) is used clinically in Europe for the symptomatic treatment of impaired cerebral function in primary degenerative dementia syndromes, and the results of numerous in vivo and in vitro studies have supported such clinical use. The abnormal production and aggregation of amyloid ß peptide (Aß) and the deposition of fibrils in the brain are regarded as key steps in the onset of Alzheimer's Disease (AD), and the inhibition of Aß aggregation and destabilization of the preformed fibrils represent viable approaches for the prevention and treatment of AD. Flavonoid glycosides and terpene trilactones (TTLs) are the two main components of EGb761 which represent 24 and 6% of the overall content, respectively. In our research, seven abundant flavonoid glycosides 1-7 were isolated from the extract of Ginkgo biloba leaves and characterized by spectroscopic analysis. Furthermore, an ultra-high performance liquid chromatography method was established for the simultaneous quantification of these seven flavonoids. The inhibitory activities of these flavonoids, as well as four TTLs, i.e., ginkgolides A, B, and C and bilobalide (compounds 8-11), were evaluated towards Aß42 fibril formation using a thioflavin T fluorescence assay. It was found that three flavonoids 1, 3 and 4 exhibited moderate inhibitory activities, whereas the other four flavonoids 2, 5, 6 and 7, as well as the four terpene trilactones, showed poor activity. This is the first report of the inhibition of Aß fibril formation of two characteristic acylated flavonoid glycosides 6, 7 in Ginkgo leaves, on the basis of which the structure-activity relationship of these flavonoids 1-7 was discussed.

Catechins and procyanidins of Ginkgo biloba show potent activities towards the inhibition of ß-amyloid peptide aggregation and destabilization of preformed fibrils.

Catechins and procyanidins, together with flavonoid glycosides and terpene trilactones, are three important categories of components in the standard extract of Ginkgo biloba leaves (EGb761). In this research, catechins and proanthocyanidins were found to exist in both the extract of Ginkgo leaves and Ginkgo products. By comparing with reference compounds, six of them were identified as (+)-catechin, (-)-epicatechin, (-)-gallocatechin, (-)-epigallocatechin and procyanidins B1 and B3. The activities of these polyphenols in the inhibition of Aß42 aggregation and the destabilization of preformed fibrils were evaluated using biochemical assays, which showed that all six of the polyphenols, as well as a fraction of the extract of Ginkgo biloba leaves (EGb) containing catechins and procyanidins, exerted potent inhibitory activities towards Aß42 aggregation and could also destabilize the performed fibrils. Catechins and procyanidins can therefore be regarded as the potent active constituents of EGb761 in terms of their inhibition of Aß42 aggregation and destabilization of the fibrils. Although quantitative mass spectroscopic analysis revealed that the catechins and procyanidins are only present in low concentrations in EGb761, these components should be studied in greater detail because of their potent inhibitory effects towards Aß42 aggregation and their ability to destabilize preformed fibrils, especially during the quality control of Ginkgo leaves and the manufacture of Ginkgo products.

Discrimination of Baphicacanthis Cusiae Rhizoma et radix and its adulterant species and establishment of an assay method for quality control.

BACKGROUND: Baphicacanthis Cusiae Rhizoma et Radix, commonly known as Nan-Ban-Lan-Gen (NBLG), is an essential traditional Chinese medicine that possesses diverse bioactivities, particularly noteworthy for its antiviral properties. Although NBLG has been listed in the Chinese Pharmacopoeia as an independent Chinese medicine, the establishment of a comprehensive quality standard for NBLG remains elusive. The absence of assay for marker compound in its quality standards has led to the lack of corresponding quality control measures for NBLG-containing preparations, and its discrimination from adulterant species in the market which thereby can significantly impact the efficacy and safety of NBLG-containing products. METHODS: Ultra-high performance liquid chromatography (UHPLC) coupled with quadrupole-time-of-flight mass spectrometry (Q-TOF-MS) was employed for comprehensive profiling of the chemical constituents of NBLG, the stem of Baphicacanthus cusia (Nees) Bremek (NBLJ), and the roots of Isatis indigotica Fort. (Bei-Ban-Lan-Gen, BBLG). Additionally, multivariate analysis was conducted to compare the chemical components of NBLG with those of NBLJ and BBLG. Furthermore, we established an optimized and validated HPLC method to obtain the fingerprint of NBLG and quantify the content of 2-benzoxazolinone and acteoside in the samples. RESULTS: A total of 73 compounds belonging to six classes were assigned in NBLG, with alkaloids being the most abundant and diverse species. High compositional similarities with significant differences in content were observed between NBLG and NBLJ. Moreover, the chemical profile of BBLG markedly differed from that of NBLG. An informative high performance liquid chromatography (HPLC) fingerprint of NBLG comprising seven characteristic peaks that can be used for quality assessment was established. Notably, we propose a quality control standard for NBLG, stipulating that the limit of content in dry weight for both 2-benzoxazolinone and acteoside should not be less than 0.010%. CONCLUSION: This study provides the most comprehensive chemical information to date on NBLG, offering valuable insights into its authentication and quality control. Our findings highlight the importance of comprehensive chemical profiling to differentiate potential substitutions and adulterations of herbal medicines, particularly when the original source is scarce or unavailable. These results can aid in the development of quality control measures for NBLG-containing preparations, ensuring their safety and efficacy.

Robust quantitation of gangliosides and sulfatides in human brain using UHPLC-MRM-MS: Method development and application in Alzheimer's disease.

Gangliosides (GAs) and sulfatides (STs) are acidic glycosphingolipids that are particularly abundant in the nervous system and are closely related to aging and neurodegenerative disorders. To explore their roles in brain diseases, in-depth molecular profiling, including structural variations of sphingoid backbone, fatty acyl group, and sugar chain of GAs and STs was performed. A total of 210 GAs and 38 STs were characterized in the inferior frontal gyrus (IFG) of human brain, with 90 GAs discovered in brain tissues for the first time. Influential MS parameters for detecting GAs and STs in multiple reaction monitoring (MRM) mode were systematically examined and optimized to minimize in-source fragmentation, resulting in remarkable signal intensity enhancement for GAs and STs, especially for polysialylated species. To eliminate analytical variations, isotopic interference-free internal standards were prepared by simple and fast reduction reaction. The final established method facilitated the simultaneous quantitation of 184 GAs and 30 STs from 25 subtypes, which represents the highest number of GAs quantitated among all quantitation methods recorded in literature so far. The method was further validated and applied to reveal the aberrant change of GAs and STs in the IFG of 12 Alzheimer's disease (AD) patients. Four GAs exhibited high classification capacity for AD (AUC ≥0.80) and were thereby considered the most promising signatures for AD. These findings suggested the close correlation between GAs and the pathogenesis of AD, highlighting the achievements of our robust method for investigating the roles of GAs and STs in various physiological states and diseases.

Hydroxyapatite-based nano-drug delivery system for nicotinamide mononucleotide (NMN): significantly enhancing NMN bioavailability and replenishing in vivo nicotinamide adenine dinucleotide (NAD+) levels.

OBJECTIVES: This study addresses the bioavailability challenges associated with oral nicotinamide mononucleotide (NMN) administration by introducing an innovative NMN formulation incorporated with hydroxyapatite (NMN-HAP). METHODS: The NMN-HAP was developed using a wet chemical precipitation and physical adsorption method. To assess its superiority over conventional free NMN, we examined NMN, nicotinamide adenine dinucleotide (NAD+), and nicotinamide riboside (NR) levels in mouse plasma and tissues following oral administration of NMN-HAP. KEY FINDINGS: NMN-HAP nanoparticles demonstrated a rod-shaped morphology, with an average size of ~50 nm, along with encapsulation efficiency and drug loading capacity exceeding 40%. In vitro, drug release results indicated that NMN-HAP exhibited significantly lower release compared with free NMN. In vivo studies showed that NMN-HAP extended circulation time, improved bioavailability compared with free NMN, and elevated plasma levels of NMN, NAD+, and NR. Moreover, NMN-HAP administration displayed tissue-specific distribution with a substantial accumulation of NMN, NAD+, and NR in the brain and liver. CONCLUSION: NMN-HAP represents an ideal formulation for enhancing NMN bioavailability, enabling tissue-specific delivery, and ultimately elevating in vivo NAD+ levels. Considering HAP's biocompatible nature and versatile characteristics, we anticipate that this system has significant potential for various future applications.

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.

Identification of Cannabidivarin Metabolites in Different Mouse Organs Using Ultra-Performance Liquid Chromatography Coupled to a Quadrupole Time-of-Flight Mass Spectrometer.

Background and Objectives: As a natural analog of cannabidiol (CBD), nonpsychoactive cannabidivarin (CBDV) has therapeutic potential. However, the precise metabolism of CBDV either in vivo or in vitro has not been fully understood. Objective and Experimental Approach: Therefore, mice were intragastrically administered CBDV, and metabolite-rich and potential target organs and tissues were collected and analyzed by ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. The metabolic pathways of CBDV in mice were illustrated more comprehensively for the first time. Results: Twenty-one metabolites were found, all of which, except decarbonylated CBDV, were initially identified. Compared with CBD, the newly identified metabolic pathways were single dehydrogenation, combined decarbonylation and monohydroxylation, and glutathione conjugations of CBDV and its phase I metabolite. Conclusions: According to the very low response in plasma and the extremely high response in intestinal contents 1 h later after the administration, it was assumed that the oral bioavailability of CBDV was as poor as that of CBD, and the major forms to excrete were conjugates of glutathione and glucuronic acid. In contrast to CBDV, decarbonylated CBDV in the keto form and enol form had considerable responses in plasma and preferred to target fatty tissues and organs owing to their higher lipophilicity. Whether these forms can function as genuine active substances in vivo instead of CBDV is worthy of investigation. These results and supposes contribute notable information regarding the pharmacokinetics and pharmacodynamics of CBDV.

Characterization of deglycosylated metabolites of platycosides reveals their biotransformation after oral administration.

Platycodon grandiflorus is a well-known edible and medicinal plant that has been developed for dietary supplements or functional foods to relieve pulmonary disorders. Platycosides are the main active constituents of P. grandiflorus with multiple pharmacological activities. However, their metabolic fates after dietary consumption are still unclear. Herein, 25 deglycosylated metabolites of platycosides were identified, most of which were identified in vivo for the first time. Notably, 3-O-ß-d-glucopyranosyl platycosides could be absorbed into the bloodstream, and their structures were unambiguously characterized with the aid of chemically prepared standards, including two new compounds (M3 and M11). These findings reveal that both intestinal bacterial metabolism and hydrolysis of ester linkage at C-28 by carboxylesterases in liver are the possible in vivo deglycosylation metabolism pathway of platycosides. This study greatly facilitated our understanding of the fate of the platycosides after dietary consumption of P. grandiflorus products.

Improvement of tissue-specific distribution and biotransformation potential of nicotinamide mononucleotide in combination with ginsenosides or resveratrol.

Decreased Nicotinamide adenine dinucleotide (NAD+ ) level has received increasing attention in recent years since it plays a critical role in many diseases and aging. Although some research has proved that supplementing nicotinamide mononucleotide (NMN) could improve the level of NAD+ , it is still uncertain whether the NAD+ level in specific tissues could be improved in combination with other nutrients. So far, a variety of nutritional supplements have flooded the market, which contains the compositions of NMN coupled with natural products. However, the synergy and transformation process of NMN has not been fully elucidated. In this study, oral administration of NMN (500 mg/kg) combined with resveratrol (50 mg/kg) or ginsenoside Rh2&Rg3 (50 mg/kg) was used to validate the efficacy of appropriate drug combinations in mice. Compared with NMN alone, NMN combined with resveratrol could increase the levels of NAD+ in the heart and muscle by about 1.6 times and 1.7 times, respectively, whereas NMN coupled with ginsenoside Rh2&Rg3 could effectively improve the level of NAD+ in lung tissue for approximately 2.0 times. Our study may provide new treatment ideas for aging or diseases in cardiopulmonary caused by decreased NAD+ levels.

Cough Inhibition Activity of Schisandra chinensis in Guinea Pigs.

Chronic cough is very common in respiratory clinics, and no effective drugs are available. Schisandra chinensis (Turcz.) Baill. (S. chinensis), an important traditional Chinese medicine, has been extensively prescribed for patients with a persistent cough. Preliminary research indicated that 95% ethanol extracts (EE) of S. chinensis showed remarkable antitussive activity in guinea pigs exposed to cigarette smoke (CS). To find out the antitussive ingredients of S. chinensis, EE was divided into four fractions according to the polarity: petroleum ether extract (PEE), ethyl acetate extract (ECE), n-butyl alcohol extract, and residue extract. The antitussive, antioxidant, and anti-inflammatory effects of the four fractions were evaluated in a guinea pig model of cough hypersensitivity induced by CS exposure. Eighteen main constituents of the two effective fractions, PEE and ECE, were identified using ultra-high-pressure liquid chromatography electronic spray ion time-of-flight mass spectrometry. The cough inhibition activities of compound 1, 3, 9, 10, 17 were evaluated on citric acid induced acute cough guinea pigs. The results showed that the antitussive activity of EE was almost all contained in PEE and ECE. The 16 major peaks in PEE were identified as 15 lignans (1-12 and 14-16) and 1 triterpene (compound 13), and 3 major peaks (1, 17, and 18) in ECE were also identified as lignans. Three doses of five compounds brought about a significant decrease in number of cough efforts (P < .01), and the cough inhibition rates were between 40.9% and 85.1%. Therefore, lignans are the antitussive ingredients of S. chinensis.

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.

Quantitative comparison of ginsenosides and polyacetylenes in wild and cultivated American ginseng.

Quantitative comparison of seven ginsenosides in wild and cultivated American ginseng revealed that the Rg(1)/Rd ratio presented a significantly large difference between cultivated and type-I (one of the defined chemotypes) wild American ginseng, facilitating this ratio as a characteristic marker for differentiating these two groups. Similarly, the ratio (Rg(1)+Re)/Rd, and the ratio of protopanaxatriol (PPT)-type ginsenosides to protopanaxadiol (PPD)-type ginsenosides showed a large difference between these two groups. On the other hand, type-II wild samples were found to have high Rg(1)/Rb(1) and Rg(1)/Re ratios and low panaxydol/panaxynol ratio, which is entirely different from Type-I American ginseng, but is very similar to that of Asian ginseng. This not only suggests that the chemotype should be taken into consideration properly when using these parameters for differentiating American and Asian ginseng, but also indicates that type-II wild American ginseng may have distinct pharmacological activities and therapeutic effects.

Characterization and Evolutionary Analysis of a Novel H3N2 Influenza A Virus Glycosylation Motif in Southern China.

An influenza A (H3N2) virus epidemic occurred in China in 2017 and the causative strain failed to bind red blood cells (RBCs), which may affect receptor binding and antibody recognition. The objective of this study was to analyze the genetic characteristics and glycosylation changes of this novel H3N2 strain. We directly sequenced the hemagglutinin (HA) genes of H3N2 clinical specimens collected from patients with acute respiratory tract infection during 2017 in Guangdong, China. We aligned these sequences with those of A/Hong Kong/1/1968 (H3N2) and A/Brisbane/10/2007 (H3N2). Glycosylation changes were analyzed by C18 Chip-Q-TOF-MS. A/China/LZP/2017 (H3N2) was negative by HA assay, but was positive by quantitative real-time Polymerase Chain Reaction (qPCR) and direct immunofluorescence assay (DFA). We found that the HA1 residue 160T of A/China/LZP/2017 (H3N2) could block virus binding to receptors on RBCs. Furthermore, the ASN (N)-X-Thr (T) motif at HA1 residues 158-160, encoding a glycosylation site as shown by C18 Chip-Q-TOF-MS, predominated worldwide and played a critical role in RBC receptor binding. Ten glycoforms at HA1 residue 158 were identified [4_3_1_0, 5_6_0_1, 3_3_0_1, 4_4_3_0, 6_7_0_0 (SO3), 3_6_2_0, 4_3_1_2 (SO3), 7_5_2_0 (SO3), 3_6_2_1 (SO3), and 3_7_0_2]. Glycosylation changes at HA1 residues 158-160 of a circulating influenza A (H3N2) virus in Guangdong, China, in 2017 blocked binding to RBC receptors. Changes to these HA1 residues may have reduced protective antibody responses as well. Understanding these critical epitopes is important for selecting vaccine strains.

Chemerin isoform analysis in human biofluids using an LC/MRM-MS-based targeted proteomics approach with stable isotope-labeled standard.

Targeted proteomics has advantages over earlier conventional technologies for protein detection. We developed and validated an LC/MRM-MS-based targeted proteomic method combined with immunoaffinity precipitation for the enrichment and detection of low abundance chemerin isoforms in human biofluids. After tryptic digestion, each chemerin isoform was characterized by isoform-specific peptides, and the absolute quantification was achieved by using stable isotope-labeled peptides as internal standards. In serum, follicular fluid and synovial fluid, a total of 6 chemerin isoforms were identified and quantified, among which a novel natural isoform 153Q was discovered for the first time. The relative content of the six chemerin isoforms in human serum was 157S ≫ 156F ≫ 158K > 154F ≥ 155A > 153Q in the ratio of 25:17:5:2.5:2.2:1, respectively. The absolute contents were in the range of 88-3.5 ng/mL. This distribution remained consistent among the 3 biofluids analyzed. Total chemerin were found to be increased in both polycystic ovary syndrome (serum and follicular fluid) and rheumatoid arthritis (serum) patients. However, chemerin isoform analysis revealed that only 156F & 157S were increased in the former, while 155A, 156F & 157S were increased in the latter. This demonstrates the potential of this method in detailed characterization of changes in chemerin isoforms that may be of clinical relevance.

An integrated approach for comprehensive profiling and quantitation of IgG-Fc glycopeptides with application to rheumatoid arthritis.

Glycosylation plays an important role in the maintenance of the structure and function of glycoproteins, while aberrant protein glycosylation is correlated with various diseases. Human immunoglobulin G (IgG), which is composed of four subclasses (IgG1, IgG2, IgG3 and IgG4), is one of the most dominant and significant glycoprotein in human serum. The glycosylation on IgG-Fc moiety is known to be alternated with various physiological and pathological states. We herein report an integrated approach for comprehensive profiling and quantitation of IgG-Fc glycopeptides. Firstly, IgG N-glycans were profiled by using mAb-Glyco chip quadrupole time-of-flight mass spectrometry (Q-TOF-MS), resulting characterization of 87 N­glycans originating from 29 different oligosaccharide compositions. Secondly, subclass-specific glycopeptides were identified on the basis of high-resolution MS and MS/MS data by using ultra high performance liquid chromatography (UHPLC) coupled to Q-TOF-MS. As a result, 83 IgG-Fc glycopeptides from human serum, including 17 sialylated glycopeptides, were identified. In addition, a quantitation method with high sensitivity and repeatability was established by using UHPLC triple quadrupole (QQQ) MS. We applied this approach to carry out quantitative analysis of IgG glycosylation in RA patients. Finally, 36 potential glycopeptide biomarkers, including 13 species from IgG1, 12 species from IgG2/3 and 11 species from IgG4 were identified.