A High-Throughput Workflow for FFPE Tissue Proteomics.

Laser capture microdissection (LCM) has become an indispensable tool for mass spectrometry-based proteomic analysis of specific regions obtained from formalin-fixed paraffin-embedded (FFPE) tissue samples in both clinical and research settings. Low protein yields from LCM samples along with laborious sample processing steps present challenges for proteomic analysis without sacrificing protein and peptide recovery. Automation of sample preparation workflows is still under development, especially for samples such as laser-capture microdissected tissues. Here, we present a simplified and rapid workflow using adaptive focused acoustics (AFA) technology for sample processing for high-throughput FFPE-based proteomics. We evaluated three different workflows: standard extraction method followed by overnight trypsin digestion, AFA-assisted extraction and overnight trypsin digestion, and AFA-assisted extraction simultaneously performed with trypsin digestion. The use of AFA-based ultrasonication enables automated sample processing for high-throughput proteomic analysis of LCM-FFPE tissues in 96-well and 384-well formats. Further, accelerated trypsin digestion combined with AFA dramatically reduced the overall processing times. LC-MS/MS analysis revealed a slightly higher number of protein and peptide identifications in AFA accelerated workflows compared to standard and AFA overnight workflows. Further, we did not observe any difference in the proportion of peptides identified with missed cleavages or deamidated peptides across the three different workflows. Overall, our results demonstrate that the workflow described in this study enables rapid and high-throughput sample processing with greatly reduced sample handling, which is amenable to automation.

The PRIDE database resources in 2022: a hub for mass spectrometry-based proteomics evidences.

The PRoteomics IDEntifications (PRIDE) database (https://www.ebi.ac.uk/pride/) is the world's largest data repository of mass spectrometry-based proteomics data. PRIDE is one of the founding members of the global ProteomeXchange (PX) consortium and an ELIXIR core data resource. In this manuscript, we summarize the developments in PRIDE resources and related tools since the previous update manuscript was published in Nucleic Acids Research in 2019. The number of submitted datasets to PRIDE Archive (the archival component of PRIDE) has reached on average around 500 datasets per month during 2021. In addition to continuous improvements in PRIDE Archive data pipelines and infrastructure, the PRIDE Spectra Archive has been developed to provide direct access to the submitted mass spectra using Universal Spectrum Identifiers. As a key point, the file format MAGE-TAB for proteomics has been developed to enable the improvement of sample metadata annotation. Additionally, the resource PRIDE Peptidome provides access to aggregated peptide/protein evidences across PRIDE Archive. Furthermore, we will describe how PRIDE has increased its efforts to reuse and disseminate high-quality proteomics data into other added-value resources such as UniProt, Ensembl and Expression Atlas.

SBSA: an online service for somatic binding sequence annotation.

Efficient annotation of alterations in binding sequences of molecular regulators can help identify novel candidates for mechanisms study and offer original therapeutic hypotheses. In this work, we developed Somatic Binding Sequence Annotator (SBSA) as a full-capacity online tool to annotate altered binding motifs/sequences, addressing diverse types of genomic variants and molecular regulators. The genomic variants can be somatic mutation, single nucleotide polymorphism, RNA editing, etc. The binding motifs/sequences involve transcription factors (TFs), RNA-binding proteins, miRNA seeds, miRNA-mRNA 3'-UTR binding target, or can be any custom motifs/sequences. Compared to similar tools, SBSA is the first to support miRNA seeds and miRNA-mRNA 3'-UTR binding target, and it unprecedentedly implements a personalized genome approach that accommodates joint adjacent variants. SBSA is empowered to support an indefinite species, including preloaded reference genomes for SARS-Cov-2 and 25 other common organisms. We demonstrated SBSA by annotating multi-omics data from over 30,890 human subjects. Of the millions of somatic binding sequences identified, many are with known severe biological repercussions, such as the somatic mutation in TERT promoter region which causes a gained binding sequence for E26 transformation-specific factor (ETS1). We further validated the function of this TERT mutation using experimental data in cancer cells. Availability:http://innovebioinfo.com/Annotation/SBSA/SBSA.php.

Proteomic analysis using isobaric tags for relative and absolute quantification technology reveals mechanisms of toxic effects of tris (1,3-dichloro-2-propyl) phosphate on RAW264.7 macrophage cells.

Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP) is one of the most commonly used organophosphorus flame retardants. Immuno-toxicity induced by TDCIPP is becoming of increasing concern. However, effects of TDCIPP on immune cells and mechanisms resulting in those effects are poorly understood. In this study, it was determined, for the first time, by use of isobaric tags for relative and absolute quantification (iTRAQ) based proteomic techniques expression of global proteins in RAW264.7 cells exposed to 10 µM TDCIPP. A total of 180 significantly differentially expressed proteins (DEPs) were identified. Of these, 127 were up-regulated and 53 were down-regulated. The DEPs associated with toxic effects of TDCIPP were then screened by use of Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes for enrichment analysis. Results showed that these DEPs were involved in a number of pathways including apoptosis, DNA damage, cell cycle arrest, immune-toxicity, and signaling pathways, such as the Toll-like receptor, PPAR and p53 signaling pathways. The complex regulatory relationships between different DEPs, which might play an important role in cell death were also observed in the form of a protein-protein interaction network. Meanwhile, mitochondrial membrane potential (MMP) in RAW264.7 cells after TDCIPP treatment was also analyzed, the collapse of the MMP was speculated to play an important role in TDCIPP induced apoptosis. Moreover, some of the important regulator proteins discovered in this study, such as Chk1, Aurora A, would provide novel insight into the molecular mechanisms involved in toxic responses to TDCIPP.

A map of neutrophil granules by proteomics / Mapa dos neutrófilos por proteômica (OU) Mapa dos grânulos do neutrófilo por proteômica

Neutrophils are polymorphonuclear leukocytes that play a key role in the organism defense. These cells enroll in a range of actions to ensure pathogen elimination and orchestrate both innate and adaptative immune responses. The main physiological structures of neutrophils are their storage organelles that are essential since the cells activation and participate in all their functions. The storage organelles are divided into 2 types: granules and secretory vesicles. The granules are subdivided into azurophilic, specific and gelatinase. The granules are distinguished by their protein content, and since they play an important role on the neutrophil function, the knowledge of the proteins stored in these organelles can help to better understand these cells. Some proteins are present in high abundance and are used as markers for each storage organelle. These proteins are myeloperoxidase (MPO) for azurophil granules, neutrophil gelatinase associated with lipocalin-2 (NGAL) and lactoferrin (LTF) for specific granules, matrix metalloproteinase-9 (MMP9) for gelatinase granules and alkaline phosphatase (AP) for secretory vesicles. The isolation of neutrophils granules, however, is challenging and the existing procedures rely on large sample volumes, about 400 mL of peripheral blood or 3 x 108 neutrophils, not allowing for multiple biological and technical replicates. Therefore, the aim of this study was to develop a miniaturized neutrophil granules isolation method and to use biochemical assays, mass spectrometry-based proteomics and a machine learning approach to investigate the protein content of the neutrophils storage organelles. With that in mind, 40 mL of the peripheral blood of three apparently healthy volunteers were collected. The neutrophils were isolated, disrupted using nitrogen cavitation and organelles were fractionated with a discontinuous 3-layer Percoll density gradient. The presence of granules markers in each fraction was assessed using western blot , gelatin zymography and enzymatic assays. The isolation was proven successful and allowed for a reasonable separation of all neutrophils storage organelles in a gradient of less than 1 mL, about 37 times smaller than the methodsdescribed in the literature. Moreover, mass spectrometry-based proteomics identified 369 proteins in at least 3 of the 5 samples, and using a machine learning strategy, the localization of 140 proteins was predicted with confidence. Furthermore, this study was the first to investigate the proteome of neutrophil granules using technical and biological replicates, creating a reliable database for further studies. In conclusion, the developed miniaturized method is reproducible, cheaper, and reliable. In addition, it provides a resource for further studies exploring neutrophil granules protein content and mobilization during activation with different stimuli

Neutrófilos são leucócitos polimorfonucleares que possuem papel fundamental na defesa do organismo. Essas células desempenham diversas ações a fim de assegurar a eliminação de um patógeno e, além disso, orquestram a resposta imune inata e adaptativa. O conjunto composto pelos grânulos de armazenamento e as vesículas secretórias compõe a principal estrutura fisiológica dos neutrófilos. Estes componentes são essenciais desde a ativação celular, participando de todas as funcionalidades desta célula. Os grânulos são subdivididos em azurófilos, específicos e gelatinase. Eles podem ser distinguidos por meio de seu conteúdo proteico e, como são importantes na funcionalidade dos neutrófilos, identificar quais proteínas são armazenadas nestas organelas é imprescindível para entender melhor essa célula como um todo. Algumas proteínas, estão presentes de forma abundante e, portanto, são utilizadas como marcadores dos grânulos. Tais proteínas são mieloperoxidase (MPO) para os grânulos azurófilos, gelatinase de neutrófilo associada a lipocalina (NGAL) e lactoferrina (LTF) para os específicos, metaloproteinase de matrix 9 (MMP9) para os grânulos de gelatinase e fosfatase alcalina (AP) para as vesículas secretórias. Isolar estas estruturas, no entanto, é desafiador visto que os protocolos existentes na literatura utilizam grandes volumes de amostra, cerca de 400 mL de sangue ou 3 x 108 neutrófilos, para apenas um isolamento, impedindo a realização de replicatas técnicas e biológicas. Desta forma, o objetivo do presente estudo foi desenvolver um protocolo miniaturizado de isolamento dos grânulos neutrofílicos e utilizar métodos bioquímicos, de proteômica e machine learning para investigar o conteúdo proteico destas estruturas celulares. Para isto, 40 mL de sangue periférico de três voluntários aparentemente saudáveis foi coletado. Os neutrófilos foram então isolados, lisados com cavitação de nitrogênio e o fracionamento subcelular foi realizado baseado em um gradiente descontínuo de 3 camadas de Percoll. O método de isolamento foi avaliado através da investigação dos marcadores utilizando western blotting (WB), zimografia de gelatina e ensaios enzimáticos em cada fração coletada. O isolamento demonstrou-se eficiente e permitiu uma ótima separação dos grânulosem um gradiente menor que 1 mL, cerca de 37 vezes menor que os métodos atualmente descritos na literatura. Além disso, a análise proteômica foi capaz de identificar 369 proteínas presentes em pelo menos 3 das 5 réplicas investigadas e, utilizando ferramentas de machine learning, 140 proteínas foram classificadas como pertencentes a um dos tipos de grânulos ou vesícula secretória com alto nível de confiabilidade. Por fim, o presente estudo foi o primeiro a investigar o proteoma dos grânulos utilizando replicatas técnicas e biológicas, criando e fornecendo uma base de dados robusta que poderá ser utilizada em estudos futuros. Conclui-se, portanto, que a metodologia miniaturizada desenvolvida é eficaz, reprodutível e mais barata, além de permitir estudos mais complexos e profundos sobre o proteoma dos grânulos dos neutrófilos em diferentes momentos celulares, tais como quando ativados via estímulos distintos

Proteomics: a tool to investigate of composition and function of HDL in hyperlipidemia / Proteômica: uma ferramenta para a investigação da composição e função da HDL em hiperlipidemia

The inverse relationship between HDL-C (high-density lipoprotein cholesterol) and cardiovascular disease is well established. However, it is consensus that the cholesterol content present in HDL does not capture its complexity, and other metrics need to be explored. HDL is a heterogeneous, protein-enriched particle with functions going beyond lipid metabolism. In this way, its protein content seems to be attractive to investigate its behavior in the face of pathologies. Many of the proteins with important function in HDL are in low abundance (<1% of total proteins), which makes their detection challenging. Quantitative proteomics allows detecting proteins with high precision and robustness in complex matrix. However, quantitative proteomics is still poorly explored in the context of HDL. In this sense, in the second chapter of this thesis, the analytical performance of two quantitative methodologies was carefully investigated. These methods achieved adequate linearity and high precision using labeled peptides in a pool HDL, in addition to comparable ability to differentiate proteins from HDL subclasses of healthy subjects. Another bottleneck that waits for a solution in proteomics is the lack of standardization in data processing and analysis after mass spectrometry acquisition. In addition, interest in the cardioprotective properties of omega-3 is growing, but little is known about its effects on the HDL proteome. Thus, in the third chapter of this thesis, we compared five protein quantification strategies using Skyline and MaxDIA software platforms in order to investigate the HDL proteome from mice submitted to a high-fat diet supplemented or not with omega-3. MaxDIA with label-free quantification (MaxLFQ) achieved high precision to show that polyunsaturated fatty acids remodel the HDL proteome to a less inflammatory profile. Therefore, the two studies presented in this thesis begin to open new paths for a deeper and more reliable understanding of HDL, both at the level of protein quantification by mass spectrometry and after data acquisition

A inversa relação entre HDL-C (do inglês, high-density lipoprotein cholesterol) e doenças cardiovasculares é bem estabelecida. No entanto, é consenso que o conteúdo de colesterol presente na HDL não captura sua complexidade, e outras métricas precisam ser exploradas. A HDL é uma partícula heterogênea, enriquecida em proteínas, com funções que vão além do metabolismo de lipídeos. Dessa forma, seu conteúdo proteico parece ser mais atrativo para exprimir seu comportamento frente às patologias. Muitas das proteínas com função importante estão em baixa abundância (<1% do total de proteínas), o que torna a detecção desafiadora. Métodos quantitativos de proteômica permitem detectar proteínas com alta precisão e robustez em matrizes complexas. No entanto, a proteômica quantitativa ainda é pouco explorada no contexto da HDL. Nesse sentido, no segundo capítulo dessa tese, a performance analítica de dois métodos quantitativos foi criteriosamente investigada, os quais alcançaram adequada linearidade e alta precisão usando peptídeos marcados em um pool de HDL, além de comparável habilidade em diferenciar as proteínas das subclasses da HDL de indivíduos saudáveis. Outro gargalo que aguarda por solução em proteômica é a falta de padronização no processamento e análise de dados após a aquisição por espectrometria de massas. Além disso, é crescente o interesse das propriedades cardioprotetivas do ômega-3, porém pouco se conhece sobre seus efeitos no proteoma da HDL. Então, no terceiro capítulo dessa tese, comparamos cinco estratégias de quantificação de proteínas utilizando os softwares Skyline e MaxDIA com o intuito de comparar o proteoma da HDL de camundongos submetidos a uma dieta hiperlipídica suplementados ou não com ômega-3. MaxDIA com quantificação label-free (MaxLFQ) apresentou alta precisão para mostrar que o ômega-3 remodela o proteoma da HDL para um perfil menos inflamatório. Portanto, os dois estudos apresentados nessa tesa começam a abrir novos caminhos para o entendimento mais profundo e confiável da HDL tanto por meio da quantificação das proteínas por espectrometria de massas quanto após à aquisição dos dados

Assessing target engagement using proteome-wide solvent shift assays.

Recent advances in mass spectrometry (MS) have enabled quantitative proteomics to become a powerful tool in the field of drug discovery, especially when applied toward proteome-wide target engagement studies. Similar to temperature gradients, increasing concentrations of organic solvents stimulate unfolding and precipitation of the cellular proteome. This property can be influenced by physical association with ligands and other molecules, making individual proteins more or less susceptible to solvent-induced denaturation. Herein, we report the development of proteome-wide solvent shift assays by combining the principles of solvent-induced precipitation (Zhang et al., 2020) with modern quantitative proteomics. Using this approach, we developed solvent proteome profiling (SPP), which is capable of establishing target engagement through analysis of SPP denaturation curves. We readily identified the specific targets of compounds with known mechanisms of action. As a further efficiency boost, we applied the concept of area under the curve analysis to develop solvent proteome integral solubility alteration (solvent-PISA) and demonstrate that this approach can serve as a reliable surrogate for SPP. We propose that by combining SPP with alternative methods, like thermal proteome profiling, it will be possible to increase the absolute number of high-quality melting curves that are attainable by either approach individually, thereby increasing the fraction of the proteome that can be screened for evidence of ligand binding.

Light-mediated discovery of surfaceome nanoscale organization and intercellular receptor interaction networks.

The molecular nanoscale organization of the surfaceome is a fundamental regulator of cellular signaling in health and disease. Technologies for mapping the spatial relationships of cell surface receptors and their extracellular signaling synapses would unlock theranostic opportunities to target protein communities and the possibility to engineer extracellular signaling. Here, we develop an optoproteomic technology termed LUX-MS that enables the targeted elucidation of acute protein interactions on and in between living cells using light-controlled singlet oxygen generators (SOG). By using SOG-coupled antibodies, small molecule drugs, biologics and intact viral particles, we demonstrate the ability of LUX-MS to decode ligand receptor interactions across organisms and to discover surfaceome receptor nanoscale organization with direct implications for drug action. Furthermore, by coupling SOG to antigens we achieved light-controlled molecular mapping of intercellular signaling within functional immune synapses between antigen-presenting cells and CD8+ T cells providing insights into T cell activation with spatiotemporal specificity. LUX-MS based decoding of surfaceome signaling architectures thereby provides a molecular framework for the rational development of theranostic strategies.

CoolTip: Low-Temperature Solid-Phase Extraction Microcolumn for Capturing Hydrophilic Peptides and Phosphopeptides.

Reversed-phase solid-phase extraction (SPE) techniques are commonly used for desalting samples before LC/MS/MS in shotgun proteomics. However, hydrophilic peptides are often lost during the desalting step under the standard SPE conditions. Here, we describe a simple protocol in which a stop-and-go extraction tip packed with a poly(styrene-divinylbenzene) copolymer disc is used at 4 °C during sample loading without any organic solvent. Using this method, which we designate as the CoolTip protocol, we identified 2.9-fold more tryptic peptides and 6.1-fold more tryptic phosphopeptides from HeLa lysates than the standard SPE protocol for hydrophilic peptides, with a mobile phase of less than 8% acetonitrile in LC/MS/MS. There was no decrease in the recovery of hydrophobic peptides. CoolTip also provided better quantitative reproducibility in LC/MS/MS analysis. We anticipate that this protocol will provide improved performance in many kinds of shotgun proteomics experiments.

High-throughput and high-efficiency sample preparation for single-cell proteomics using a nested nanowell chip.

Global quantification of protein abundances in single cells could provide direct information on cellular phenotypes and complement transcriptomics measurements. However, single-cell proteomics is still immature and confronts many technical challenges. Herein we describe a nested nanoPOTS (N2) chip to improve protein recovery, operation robustness, and processing throughput for isobaric-labeling-based scProteomics workflow. The N2 chip reduces reaction volume to <30 nL and increases capacity to >240 single cells on a single microchip. The tandem mass tag (TMT) pooling step is simplified by adding a microliter droplet on the nested nanowells to combine labeled single-cell samples. In the analysis of ~100 individual cells from three different cell lines, we demonstrate that the N2 chip-based scProteomics platform can robustly quantify ~1500 proteins and reveal membrane protein markers. Our analyses also reveal low protein abundance variations, suggesting the single-cell proteome profiles are highly stable for the cells cultured under identical conditions.

Dried blood sample analysis by antibody array across the total testing process.

Dried blood samples (DBSs) have many advantages; yet, impediments have limited the clinical utilization of DBSs. We developed a novel volumetric sampling device that collects a precise volume of blood, which overcomes the heterogeneity and hematocrit issues commonly encountered in a traditional DBS card collection as well as allowing for more efficient extraction and processing procedures and thus, more efficient quantitation, by using the entire sample. We also provided a thorough procedure validation using this volumetric DBS collection device with an established quantitative proteomics analysis method, and then analyzed 1000 proteins using this approach in DBSs concomitantly with serum for future consideration of utility in clinical applications. Our data provide a first step in the establishment of a DBS database for the broad application of this sample type for widespread use in clinical proteomic and other analyses applications.

Tear Proteomics in Keratoconus: A Quantitative SWATH-MS Analysis.

Purpose: To elucidate dysregulated proteins in keratoconus (KC) to provide a better understanding of the molecular mechanisms that lead to the development of the disease using sequential window acquisition of all theoretical mass spectra (SWATH-MS) as a protein quantification tool of the tear proteomic profile. Methods: Prospective cross-sectional study that includes 25 keratoconic eyes and 25 healthy eyes. All participants underwent a clinical, tomographic, and aberrometric exam. Tear sample was collected using Schirmer strips and analyzed by liquid chromatography with tandem mass spectrometry. SWATH-MS was used as a quantification tool of the tear proteomic profile. The expression of the quantified proteins was compared between groups, and the biological and molecular functions of the dysregulated proteins as well as their functional relationships were studied by in silico analysis. Results: A total of 203 proteins were quantified in tear samples of patients with KC and control participants, of which 18 showed differential expression between groups (P < 0.05). An increase in the expression of 7 proteins and a decrease in the expression of 11 proteins were observed. Protein-protein interactions and gene ontology analysis showed the involvement of these dysregulated proteins in structural, inflammatory-immune, iron homeostasis, oxidative stress, and extracellular matrix proteolysis processes. Conclusions: Tear protein quantification has revealed the dysregulation of proteins involved in biological processes previously associated with KC. Among them, iron homeostasis should be highlighted as a relevant pathway in the KC pathophysiology, and it should be taken into account in the development of therapeutic targets to cope with tissue damage derived from iron accumulation and toxicity.

Pandora box of BCA assay. Investigation of the accuracy and linearity of the microplate bicinchoninic protein assay: Analytical challenges and method modifications to minimize systematic errors.

Bicinchoninic colorimetric assay is very widely used for total protein quantitative analysis. We report that bicinchoninic (BCA) total protein assay linearity range and the assay sensitivity are counterbalancing factors. BCA assay true linear range may be considerably narrower than the 20-2000 µg/ml and therefore the choice of the assay calibration range should not solely be dictated by the general recommendations of the user guide, however by the test specific needs and subsequent assay quality control. Expanding the BCA assay range up to 2000 µg/ml comes together with unavoidable heavy negative biases at low protein concentrations. The negative bias at low protein concentration only exacerbates with longer incubation time and/or increased sample to working reagent ratio. To minimize the lack of accuracy at low protein concentration of a wide range BCA assay, we proposing an alternative approach: a two-step incubation and calibration. With a minimum of extra work, the two-step incubation/calibration approach is devoid of the standard BCA workflow disadvantages and biases.

Application across species of a one health approach to liquid sample handling for respiratory based -omics analysis.

Airway inflammation is highly prevalent in horses, with the majority of non-infectious cases being defined as equine asthma. Currently, cytological analysis of airway derived samples is the principal method of assessing lower airway inflammation. Samples can be obtained by tracheal wash (TW) or by lavage of the lower respiratory tract (bronchoalveolar lavage (BAL) fluid; BALF). Although BALF cytology carries significant diagnostic advantages over TW cytology for the diagnosis of equine asthma, sample acquisition is invasive, making it prohibitive for routine and sequential screening of airway health. However, recent technological advances in sample collection and processing have made it possible to determine whether a wider range of analyses might be applied to TW samples. Considering that TW samples are relatively simple to collect, minimally invasive and readily available in the horse, it was considered appropriate to investigate whether, equine tracheal secretions represent a rich source of cells and both transcriptomic and proteomic data. Similar approaches have already been applied to a comparable sample set in humans; namely, induced sputum. Sputum represents a readily available source of airway biofluids enriched in proteins, changes in the expression of which may reveal novel mechanisms in the pathogenesis of respiratory diseases, such as asthma and chronic obstructive pulmonary disease. The aim of this study was to establish a robust protocol to isolate macrophages, protein and RNA for molecular characterization of TW samples and demonstrate the applicability of sample handling to rodent and human pediatric bronchoalveolar lavage fluid isolates. TW samples provided a good quality and yield of both RNA and protein for downstream transcriptomic/proteomic analyses. The sample handling methodologies were successfully applicable to BALF for rodent and human research. TW samples represent a rich source of airway cells, and molecular analysis to facilitate and study airway inflammation, based on both transcriptomic and proteomic analysis. This study provides a necessary methodological platform for future transcriptomic and/or proteomic studies on equine lower respiratory tract secretions and BALF samples from humans and mice.

Characterization of Extracellular Vesicle Cargo in Sjögren's Syndrome through a SWATH-MS Proteomics Approach.

Primary Sjögren's syndrome (pSS) is a complex heterogeneous disease characterized by a wide spectrum of glandular and extra-glandular manifestations. In this pilot study, a SWATH-MS approach was used to monitor extracellular vesicles-enriched saliva (EVs) sub-proteome in pSS patients, to compare it with whole saliva (WS) proteome, and assess differential expressed proteins between pSS and healthy control EVs samples. Comparison between EVs and WS led to the characterization of compartment-specific proteins with a moderate degree of overlap. A total of 290 proteins were identified and quantified in EVs from healthy and pSS patients. Among those, 121 proteins were found to be differentially expressed in pSS, 82% were found to be upregulated, and 18% downregulated in pSS samples. The most representative functional pathways associated to the protein networks were related to immune-innate response, including several members of S100 protein family, annexin A2, resistin, serpin peptidase inhibitors, azurocidin, and CD14 monocyte differentiation antigen. Our results highlight the usefulness of EVs for the discovery of novel salivary-omic biomarkers and open novel perspectives in pSS for the identification of proteins of clinical relevance that could be used not only for the disease diagnosis but also to improve patients' stratification and treatment-monitoring. Data are available via ProteomeXchange with identifier PXD025649.

New Interface for Faster Proteoform Analysis: Immunoprecipitation Coupled with SampleStream-Mass Spectrometry.

Different proteoform products of the same gene can exhibit differing associations with health and disease, and their patterns of modifications may offer more precise markers of phenotypic differences between individuals. However, currently employed protein-biomarker discovery and quantification tools, such as bottom-up proteomics and ELISAs, are mostly proteoform-unaware. Moreover, the current throughput for proteoform-level analyses by liquid chromatography mass spectrometry (LCMS) for quantitative top-down proteomics is incompatible with population-level biomarker surveys requiring robust, faster proteoform analysis. To this end, we developed immunoprecipitation coupled to SampleStream mass spectrometry (IP-SampleStream-MS) as a high-throughput, automated technique for the targeted quantification of proteoforms. We applied IP-SampleStream-MS to serum samples of 25 individuals to assess the proteoform abundances of apolipoproteins A-I (ApoA-I) and C-III (ApoC-III). The results for ApoA-I were compared to those of LCMS for these individuals, with IP-SampleStream-MS showing a >7-fold higher throughput with >50% better analytical variation. Proteoform abundances measured by IP-SampleStream-MS correlated strongly to LCMS-based values (R2 = 0.6-0.9) and produced convergent proteoform-to-phenotype associations, namely, the abundance of canonical ApoA-I was associated with lower HDL-C (R = 0.5) and glycated ApoA-I with higher fasting glucose (R = 0.6). We also observed proteoform-to-phenotype associations for ApoC-III, 22 glycoproteoforms of which were characterized in this study. The abundance of ApoC-III modified by a single N-acetyl hexosamine (HexNAc) was associated with indices of obesity, such as BMI, weight, and waist circumference (R ∼ 0.7). These data show IP-SampleStream-MS to be a robust, scalable workflow for high-throughput associations of proteoforms to phenotypes.

A New Parallel High-Pressure Packing System Enables Rapid Multiplexed Production of Capillary Columns.

Reversed-phase HPLC is the most commonly applied peptide-separation technique in MS-based proteomics. Particle-packed capillary columns are predominantly used in nanoflow HPLC systems. Despite being the broadly applied standard for many years, capillary columns are still expensive and suffer from short lifetimes, particularly in combination with ultra-high-pressure chromatography systems. For this reason, and to achieve maximum performance, many laboratories produce their own in-house packed columns. This typically requires a considerable amount of time and trained personnel. Here, we present a new packing system for capillary columns enabling rapid, multiplexed column packing with pressures reaching up to 3000 bar. Requiring only a conventional gas pressure supply and methanol as the driving fluid, our system replaces the traditional setup of helium-pressured packing bombs. By using 10× multiplexing, we have reduced the production time to just under 2 min for several 50 cm columns with 1.9-µm particle size, speeding up the process of column production 40 to 800 times. We compare capillary columns with various inner diameters and lengths packed under different pressure conditions with our newly designed, broadly accessible high-pressure packing station.

Endometrium On-a-Chip Reveals Insulin- and Glucose-induced Alterations in the Transcriptome and Proteomic Secretome.

The molecular interactions between the maternal environment and the developing embryo are key for early pregnancy success and are influenced by factors such as maternal metabolic status. Our understanding of the mechanism(s) through which these individual nutritional stressors alter endometrial function and the in utero environment for early pregnancy success is, however, limited. Here we report, for the first time, the use of an endometrium-on-a-chip microfluidics approach to produce a multicellular endometrium in vitro. Isolated endometrial cells (epithelial and stromal) from the uteri of nonpregnant cows in the early luteal phase (Days 4-7) were seeded in the upper chamber of the device (epithelial cells; 4-6 × 104 cells/mL) and stromal cells seeded in the lower chamber (1.5-2 × 104 cells/mL). Exposure of cells to different concentrations of glucose (0.5, 5.0, or 50 mM) or insulin (Vehicle, 1 or 10 ng/mL) was performed at a flow rate of 1 µL/minute for 72 hours. Quantitative differences in the cellular transcriptome and the secreted proteome of in vitro-derived uterine luminal fluid were determined by RNA-sequencing and tandem mass tagging mass spectrometry, respectively. High glucose concentrations altered 21 and 191 protein-coding genes in epithelial and stromal cells, respectively (P < .05), with a dose-dependent quantitative change in the protein secretome (1 and 23 proteins). Altering insulin concentrations resulted in limited transcriptional changes including transcripts for insulin-like binding proteins that were cell specific but altered the quantitative secretion of 196 proteins. These findings highlight 1 potential mechanism by which changes to maternal glucose and insulin alter uterine function.