Fucosyl monosialoganglioside: Quantitative analysis of specific potential biomarkers of lung cancer in biological matrices using immunocapture extraction/tandem mass spectrometry

Astaxanthin alleviates ganglioside metabolism disorder in the cortex of Alzheimer's disease mice

The present study analyzed the amelioration effect and mechanism of two kinds of astaxanthin (AST), including free-AST (F-AST) and docosahexaenoic acid-acylated AST monoester (AST-DHA), on ganglioside (GLS) metabolism in the cortex of APP/PS1 mice using the LC-MS strategy in combination with molecular biology. Water maze and immunohistochemical experiments demonstrated that AST significantly improved the cognitive level of APP/PS1 mice and reduced Aβ deposition in the cortex. After the dietary intake of AST, the composition and level of 84 GLS molecular species in the mouse cortex were determined using the LC-MS strategy. The results showed that the total GLS was reduced, most complex GLS was decreased, and simple GLS (GM3 and GM1a) was increased in the APP/PS1 mouse cortex. Notably, F-AST mainly regulated complex GLS (p < 0.001), whereas AST-DHA primarily reacted with simple GLS (p < 0.001). OAc-GQ1a(38:1), OAc-GQ1a(36:1), GD1a(36:1), and GM3(38:1) decreased 3.73, 2.31, and 2.29-fold and increased 3.54-fold, respectively, and were identified as potential AD biomarkers in the cortices of APP/PS1 mice. Additionally, the AST diet significantly upregulated the mRNA expression of GLS synthesizing genes (st3gal5, st8sia1, b3galt4, st3fal2, and soat) and siae (p < 0.05) and down-regulated that of the GLS catabolizing gene hexa (p < 0.01). In conclusion, improving GLS homeostasis in the AD mouse cortex might be a critical pathway to explain the AD-preventing effect of AST.

An integrated Qual/Quan strategy for ganglioside lipidomics using high-resolution mass spectrometry and Skyline software

RATIONALE

Gangliosides (GS) are attractive targets in biomarker discovery because of their physiological significance in numerous human diseases including certain cancers and developmental and metabolic disorders. The robust strategy described here enables the profiling of numerous GS while obtaining quantitative data of exploratory biomarkers present in human plasma and whole blood.

METHOD

The GS from human blood, human plasma, and several cell lines were extracted using a mixture of methanol and isopropanol/0.1% formic acid followed by direct analysis of the supernatant. The simultaneous Qualitative and Quantitative (Qual/Quan) approach involves micro flow (20 μL/min) high pressure liquid chromatography (HPLC)/high-resolution mass spectrometry (HRMS) and post-acquisition data processing with Skyline software for profiling numerous GS in biological matrices. The quantitative assay involves reverse-phase liquid chromatography/HRMS and calibration curves using commercially available GS.

RESULTS

Protein precipitation resulted in ~60%-80% GS recovery from biological matrices. Direct injection of the extract allowed for quantification of targeted GS in human blood, plasma, and cancer cell lines. The lower limit of detection for the target analytes, GM1, GT1, GD1, spiked into 1% BSA/PBS, ranged from 1 to 10 ng/mL. Human lung cancer cell lines contained variable amounts (1-130 ng/mL) of soluble Fuc-GM1 analogs, potential biomarkers of lung cancer.

CONCLUSIONS

A combination of simple extraction and micro-HPLC/HRMS allowed for quantification of GS in human serum and whole blood. Integration of HRMS with Skyline allowed for GS profiling in the same samples using post-acquisition HRMS data without the need for reanalysis. The strategy presented here is expected to play an important role in profiling exploratory GS biomarkers in discovery bioanalytical research.

iTRAQ-based quantitative proteomics analysis of immune thrombocytopenia patients before and after Qishunbaolier treatment

RATIONALE

Treatment of immune thrombocytopenia (ITP) usually involves long-term use of immunosuppressive corticosteroids and splenectomy. However, these treatments often have side effects in patients. The Mongolian medicine Qishunbaolier (QSBLE) has a high curative effect, reduces the chances of relapse, and has no obvious side effects. This study was designed to identify potential therapeutic targets of QSBLE for treating ITP.

METHODS

To reveal differences in protein expression between ITP patients (ITPs) before and after QSBLE treatment, comparative proteomics studies were performed using isobaric tags for relative and absolute quantification (iTRAQ). The analysis used nanospray liquid chromatography/tandem mass spectrometry (nano-LC/MS/MS) in positive ion electrospray ionization mode. Key proteins relevant to ITP were revealed by the Kyoto Encyclopedia of Genes and Genomes (KEGG) and other bioinformatics tools. Real-time polymerase chain reaction (RT-PCR) analysis was carried out for confirmation of differentially expressed proteins.

RESULTS

A total of 982 differentially expressed proteins were identified in ITPs compared with the controls. Compared with the pre-QSBLE treatment group, 61 differentially expressed proteins were identified in the post-QSBLE treatment group, with 48 proteins being significantly upregulated and 13 downregulated. Twenty-nine pathways were significantly enriched. Q6N030 and other proteins were the key players in the protein-pathway network. Twenty proteins that may play important roles in the treatment of ITP were further filtered. RT-PCR and Western blot analyses further confirmed that MIF, PGK1 and IGHM were upregulated in ITPs after QSBLE treatment, in accordance with the proteomics data.

CONCLUSIONS

It is believed that the identified proteins and the results of bioinformatics analysis will provide a potential therapeutic target site for QSBLE for ITP therapy and biomarkers.

Human prorenin determination by hybrid immunocapture liquid chromatography/mass spectrometry: A mixed-solvent-triggered digestion utilizing D-optimal design

RATIONALE

Human prorenin, representing the precursor of mature renin, has been discussed as a potential biomarker, e.g. in diagnosing primary hyperaldosteronism or diabetes-induced nephropathy. Currently, only immunoassays are available for prorenin quantification. As the similarity of prorenin to active renin impedes its accurate determination by immunoassay, mass spectrometry appears as an accurate alternative for differentiation of that protein.

METHODS

Immunoaffinity purification plus a mixed-solvent-triggered digestion was combined with liquid chromatography/mass spectrometry (LC/MS) to enable a fast, sensitive, and less laboratory-intensive approach to the quantification of prorenin. Statistical experimental planning, which is known as Design of Experiments (DOE), was used to identify the optimal conditions for the generation of the signature peptides within a manageable number of experiments. The efficiency of the mixed-solvent-triggered digestion by trypsin was investigated using four different organic solvents: acetonitrile, acetone, tetrahydrofuran and methanol.

RESULTS

By utilizing a D-optimal design, we found that the optimal mixed-solvent type for the generation of both signature peptides was acetonitrile at a concentration of 84% and an incubation temperature of 16°C. Using the mixed-solvent-triggered digestion, the procedure time allowed a fast analysis of active renin and prorenin with a short digestion time of 98 min. This optimized mixed-solvent-triggered digestion procedure was applied to detect renin and prorenin successfully in human plasma by the newly developed hybrid approach.

CONCLUSIONS

The identification of unique surrogates for human prorenin enabled the mass spectrometric differentiation between the two similar proteins. The novel hybrid approach successfully proved its ability to purify, detect and distinguish between prorenin and active renin in human plasma.