Correction: Comparison of the broncoalveolar lavage fluid proteomics between foals and adult horses.

[This corrects the article DOI: 10.1371/journal.pone.0290778.].

Aging-related alterations in mechanistic target of rapamycin signaling promote platelet hyperreactivity and thrombosis.

BACKGROUND: Aging is an independent risk factor for the development of cardiovascular, thrombotic, and other chronic diseases. However, mechanisms of platelet hyperactivation in aging remain poorly understood. OBJECTIVES: Here, we examine whether and how aging alters intracellular signaling in platelets to support platelet hyperactivity and thrombosis. METHODS: Quantitative mass spectrometry with tandem mass tag labeling systematically measured protein phosphorylation in platelets from healthy aged (>65 years) and young human (<45 years) subjects. The role of platelet mechanistic target of rapamycin (mTOR) in aging-induced platelet hyperreactivity was assessed using pharmacologic mTOR inhibition and a platelet-specific mTOR-deficient mouse model (mTORplt-/-). RESULTS: Quantitative phosphoproteomics uncovered differential site-specific protein phosphorylation within mTOR, Rho GTPase, and MAPK pathways in platelets from aged donors. Western blot confirmed constitutive activation of the mTOR pathway in platelets from both aged humans and mice, which was associated with increased aggregation compared with that in young controls. Inhibition of mTOR with either Torin 1 in aged humans or genetic deletion in aged mice reversed platelet hyperreactivity. In a collagen-epinephrine pulmonary thrombosis model, aged wild-type (mTORplt+/+) mice succumbed significantly faster than young controls, while time to death of aged mTORplt-/- mice was similar to that of young mTORplt+/+ mice. Mechanistically, we noted increased Rac1 activation and levels of mitochondrial reactive oxygen species in resting platelets from aged mice, as well as increased p38 phosphorylation upstream of thromboxane generation following agonist stimulation. CONCLUSION: Aging-related changes in mTOR phosphorylation enhance Rac1 and p38 activation to enhance thromboxane generation, platelet hyperactivity, and thrombosis.

The amniotic fluid proteome changes across gestation in humans and rhesus macaques.

Amniotic fluid is a complex biological medium that offers protection to the fetus and plays a key role in normal fetal nutrition, organogenesis, and potentially fetal programming. Amniotic fluid is also critically involved in longitudinally shaping the in utero milieu during pregnancy. Yet, the molecular mechanism(s) of action by which amniotic fluid regulates fetal development is ill-defined partly due to an incomplete understanding of the evolving composition of the amniotic fluid proteome. Prior research consisting of cross-sectional studies suggests that the amniotic fluid proteome changes as pregnancy advances, yet longitudinal alterations have not been confirmed because repeated sampling is prohibitive in humans. We therefore performed serial amniocenteses at early, mid, and late gestational time-points within the same pregnancies in a rhesus macaque model. Longitudinally-collected rhesus amniotic fluid samples were paired with gestational-age matched cross-sectional human samples. Utilizing LC-MS/MS isobaric labeling quantitative proteomics, we demonstrate considerable cross-species similarity between the amniotic fluid proteomes and large scale gestational-age associated changes in protein content throughout pregnancy. This is the first study to compare human and rhesus amniotic fluid proteomic profiles across gestation and establishes a reference amniotic fluid proteome. The non-human primate model holds promise as a translational platform for amniotic fluid studies.

Unraveling the role of TGFß signaling in thoracic aortic aneurysm and dissection using Fbn1 mutant mouse models.

Although abnormal TGFß signaling is observed in several heritable forms of thoracic aortic aneurysms and dissections including Marfan syndrome, its precise role in aortic disease progression is still disputed. Using a mouse genetic approach and quantitative isobaric labeling proteomics, we sought to elucidate the role of TGFß signaling in three Fbn1 mutant mouse models representing a range of aortic disease from microdissection (without aneurysm) to aneurysm (without rupture) to aneurysm and rupture. Results indicated that reduced TGFß signaling and increased mast cell proteases were associated with microdissection. In contrast, increased abundance of extracellular matrix proteins, which could be reporters for positive TGFß signaling, were associated with aneurysm. Marked reductions in collagens and fibrillins, and increased TGFß signaling, were associated with aortic rupture. Our data indicate that TGFß signaling performs context-dependent roles in the pathogenesis of thoracic aortic disease.

Adaptor protein complex 2 in the orbitofrontal cortex predicts alcohol use disorder.

Alcohol use disorder (AUD) is a life-threatening disease characterized by compulsive drinking, cognitive deficits, and social impairment that continue despite negative consequences. The inability of individuals with AUD to regulate drinking may involve functional deficits in cortical areas that normally balance actions that have aspects of both reward and risk. Among these, the orbitofrontal cortex (OFC) is critically involved in goal-directed behavior and is thought to maintain a representation of reward value that guides decision making. In the present study, we analyzed post-mortem OFC brain samples collected from age- and sex-matched control subjects and those with AUD using proteomics, bioinformatics, machine learning, and reverse genetics approaches. Of the 4,500+ total unique proteins identified in the proteomics screen, there were 47 proteins that differed significantly by sex that were enriched in processes regulating extracellular matrix and axonal structure. Gene ontology enrichment analysis revealed that proteins differentially expressed in AUD cases were involved in synaptic and mitochondrial function, as well as transmembrane transporter activity. Alcohol-sensitive OFC proteins also mapped to abnormal social behaviors and social interactions. Machine learning analysis of the post-mortem OFC proteome revealed dysregulation of presynaptic (e.g., AP2A1) and mitochondrial proteins that predicted the occurrence and severity of AUD. Using a reverse genetics approach to validate a target protein, we found that prefrontal Ap2a1 expression significantly correlated with voluntary alcohol drinking in male and female genetically diverse mouse strains. Moreover, recombinant inbred strains that inherited the C57BL/6J allele at the Ap2a1 interval consumed higher amounts of alcohol than those that inherited the DBA/2J allele. Together, these findings highlight the impact of excessive alcohol consumption on the human OFC proteome and identify important cross-species cortical mechanisms and proteins that control drinking in individuals with AUD.

Comparison of the broncoalveolar lavage fluid proteomics between foals and adult horses.

Neonates have different cellular composition in their bronchoalveolar lavage fluid (BALF) when compared to foals and adult horses; however, little is known about the non-cellular components of BALF. The objective of this study was to determine the proteomic composition of BALF in neonatal horses and to compare it to that of foals and adult horses. Bronchoalveolar lavage fluid samples of seven neonates (< 1 week age), four 5 to 7-week-old foals, and six adult horses were collected. Quantitative proteomics of the fluid was performed using tandem mass tag labeling followed by high resolution liquid chromatography tandem mass spectrometry and protein relative abundances were compared between groups using exact text. A total of 704 proteins were identified with gene ontology terms and were classified. Of these, 332 proteins were related to the immune system in neonates, foals, and adult horses. The most frequent molecular functions identified were binding and catalytic activity and the most common biological processes were cellular process, metabolic process, and biological regulation. There was a significant difference in the proteome of neonates when compared to foals and to adult horses. Neonates had less relative expression (FDR < 0.01) of many immune-related proteins, including immunoglobulins, proteins involved in the complement cascade, ferritin, BPI fold-containing family B member 1, and macrophage receptor MARCO. This is the first report of equine neonate BALF proteomics and reveals differential abundance of proteins when compared to BALF from adult horses. The lower relative abundance of immune-related proteins in neonates could contribute to their susceptibility to pulmonary infections.

MicroRNA137-loaded lipid nanoparticles regulate synaptic proteins in the prefrontal cortex.

Genome-wide association studies indicate that allele variants in MIR137, the host gene of microRNA137 (miR137), confer an increased risk of schizophrenia (SCZ). Aberrant expression of miR137 and its targets, many of which regulate synaptic functioning, are also associated with an increased risk of SCZ. Thus, miR137 represents an attractive target aimed at correcting the molecular basis for synaptic dysfunction in individuals with high genetic risk for SCZ. Advancements in nanotechnology utilize lipid nanoparticles (LNPs) to transport and deliver therapeutic RNA. However, there remains a gap in using LNPs to regulate gene and protein expression in the brain. To study the delivery of nucleic acids by LNPs to the brain, we found that LNPs released miR137 cargo and inhibited target transcripts of interest in neuroblastoma cells. Biodistribution of LNPs loaded with firefly luciferase mRNA remained localized to the mouse prefrontal cortex (PFC) injection site without circulating to off-target organs. LNPs encapsulating Cre mRNA preferentially co-expressed in neuronal over microglial or astrocytic cells. Using quantitative proteomics, we found miR137 modulated glutamatergic synaptic protein networks that are commonly dysregulated in SCZ. These studies support engineering the next generation of brain-specific LNPs to deliver RNA therapeutics and improve symptoms of central nervous system disorders.

Adaptor protein complex 2 in the orbitofrontal cortex predicts alcohol use disorder.

Alcohol use disorder (AUD) is a life-threatening disease characterized by compulsive drinking, cognitive deficits, and social impairment that continue despite negative consequences. The inability of individuals with AUD to regulate drinking may involve functional deficits in cortical areas that normally balance actions that have aspects of both reward and risk. Among these, the orbitofrontal cortex (OFC) is critically involved in goal-directed behavior and is thought to maintain a representation of reward value that guides decision making. In the present study, we analyzed post-mortem OFC brain samples collected from age- and sex-matched control subjects and those with AUD using proteomics, bioinformatics, machine learning, and reverse genetics approaches. Of the 4,500+ total unique proteins identified in the proteomics screen, there were 47 proteins that differed significantly by sex that were enriched in processes regulating extracellular matrix and axonal structure. Gene ontology enrichment analysis revealed that proteins differentially expressed in AUD cases were involved in synaptic and mitochondrial function, as well as transmembrane transporter activity. Alcohol-sensitive OFC proteins also mapped to abnormal social behaviors and social interactions. Machine learning analysis of the post-mortem OFC proteome revealed dysregulation of presynaptic (e.g., AP2A1) and mitochondrial proteins that predicted the occurrence and severity of AUD. Using a reverse genetics approach to validate a target protein, we found that prefrontal Ap2a1 expression significantly correlated with voluntary alcohol drinking in male and female genetically diverse mouse strains. Moreover, recombinant inbred strains that inherited the C57BL/6J allele at the Ap2a1 interval consumed higher amounts of alcohol than those that inherited the DBA/2J allele. Together, these findings highlight the impact of excessive alcohol consumption on the human OFC proteome and identify important cross-species cortical mechanisms and proteins that control drinking in individuals with AUD.

Proteomic profiling of retina and retinal pigment epithelium combined embryonic tissue to facilitate ocular disease gene discovery.

To expedite gene discovery in eye development and its associated defects, we previously developed a bioinformatics resource-tool iSyTE (integrated Systems Tool for Eye gene discovery). However, iSyTE is presently limited to lens tissue and is predominantly based on transcriptomics datasets. Therefore, to extend iSyTE to other eye tissues on the proteome level, we performed high-throughput tandem mass spectrometry (MS/MS) on mouse embryonic day (E)14.5 retina and retinal pigment epithelium combined tissue and identified an average of 3300 proteins per sample (n = 5). High-throughput expression profiling-based gene discovery approaches-involving either transcriptomics or proteomics-pose a key challenge of prioritizing candidates from thousands of RNA/proteins expressed. To address this, we used MS/MS proteome data from mouse whole embryonic body (WB) as a reference dataset and performed comparative analysis-termed "in silico WB-subtraction"-with the retina proteome dataset. In silico WB-subtraction identified 90 high-priority proteins with retina-enriched expression at stringency criteria of ≥ 2.5 average spectral counts, ≥ 2.0 fold-enrichment, false discovery rate < 0.01. These top candidates represent a pool of retina-enriched proteins, several of which are associated with retinal biology and/or defects (e.g., Aldh1a1, Ank2, Ank3, Dcn, Dync2h1, Egfr, Ephb2, Fbln5, Fbn2, Hras, Igf2bp1, Msi1, Rbp1, Rlbp1, Tenm3, Yap1, etc.), indicating the effectiveness of this approach. Importantly, in silico WB-subtraction also identified several new high-priority candidates with potential regulatory function in retina development. Finally, proteins exhibiting expression or enriched-expression in the retina are made accessible in a user-friendly manner at iSyTE ( https://research.bioinformatics.udel.edu/iSyTE/ ), to allow effective visualization of this information and facilitate eye gene discovery.

Proteomic profiling of retina and retinal pigment epithelium combined embryonic tissue to facilitate ocular disease gene discovery.

To expedite gene discovery in eye development and its associated defects, we previously developed a bioinformatics resource-tool iSyTE (integrated Systems Tool for Eye gene discovery). However, iSyTE is presently limited to lens tissue and is predominantly based on transcriptomics datasets. Therefore, to extend iSyTE to other eye tissues on the proteome level, we performed high-throughput tandem mass spectrometry (MS/MS) on mouse embryonic day (E)14.5 retina and retinal pigment epithelium combined tissue and identified an average of 3,300 proteins per sample (n=5). High-throughput expression profiling-based gene discovery approaches-involving either transcriptomics or proteomics-pose a key challenge of prioritizing candidates from thousands of RNA/proteins expressed. To address this, we used MS/MS proteome data from mouse whole embryonic body (WB) as a reference dataset and performed comparative analysis-termed "in silico WB-subtraction"-with the retina proteome dataset. In silico WB-subtraction identified 90 high-priority proteins with retina-enriched expression at stringency criteria of ³2.5 average spectral counts, ³2.0 fold-enrichment, False Discovery Rate <0.01. These top candidates represent a pool of retina-enriched proteins, several of which are associated with retinal biology and/or defects (e.g., Aldh1a1, Ank2, Ank3, Dcn, Dync2h1, Egfr, Ephb2, Fbln5, Fbn2, Hras, Igf2bp1, Msi1, Rbp1, Rlbp1, Tenm3, Yap1, etc.), indicating the effectiveness of this approach. Importantly, in silico WB-subtraction also identified several new high-priority candidates with potential regulatory function in retina development. Finally, proteins exhibiting expression or enriched-expression in the retina are made accessible in a user-friendly manner at iSyTE (https://research.bioinformatics.udel.edu/iSyTE/), to allow effective visualization of this information and facilitate eye gene discovery.

Cell derived matrices from bovine corneal endothelial cells as a model to study cellular dysfunction.

PURPOSE: Fuchs endothelial corneal dystrophy (FECD) is a progressive corneal disease that impacts the structure and stiffness of the Descemet's membrane (DM), the substratum for corneal endothelial cells (CECs). These structural alterations of the DM could contribute to the loss of the CECs resulting in corneal edema and blindness. Oxidative stress and transforming growth factor-ß (TGF-ß) pathways have been implicated in endothelial cell loss and endothelial to mesenchymal transition of CECs in FECD. Ascorbic acid (AA) is found at high concentrations in FECD and its impact on CEC survival has been investigated. However, how TGF-ß and AA effect the composition and rigidity of the CEC's matrix remains unknown. METHODS: In this study, we investigated the effect of AA, TGF-ß1 and TGF-ß3 on the deposition, ultrastructure, stiffness, and composition of the extracellular matrix (ECM) secreted by primary bovine corneal endothelial cells (BCECs). RESULTS: Immunofluorescence and electron microscopy post-decellularization demonstrated a robust deposition and distinct structure of ECM in response to treatments. AFM measurements showed that the modulus of the matrix in BCECs treated with TGF-ß1 and TGF-ß3 was significantly lower than the controls. There was no difference in the stiffness of the matrix between the AA-treated cell and controls. Gene Ontology analysis of the proteomics results revealed that AA modulates the oxidative stress pathway in the matrix while TGF-ß induces the expression of matrix proteins collagen IV, laminin, and lysyl oxidase homolog 1. CONCLUSIONS: Molecular pathways identified in this study demonstrate the differential role of soluble factors in the pathogenesis of FECD.

Tandem mass tag-based quantitative proteomic analysis of cervical cancer.

BACKGROUND: Cervical cancer is a common cancer in women caused by high-risk human papillomavirus (Hr-HPV). Many potential biomarkers have been proposed for precancerous lesions and cancer diagnosis and some of these markers studied for prognosis. This study determined potential biomarkers for cervical cancer diagnosis in regard to HPV genotype by using isobaric labeling quantitative proteomics. METHODS: in the current study, there were 75 formalin fixed paraffin embedded (FFPE) uterine cervical samples that used to determine the 14 HPV genotypes and the viral load of each genotype was determined. The tandem mass tag (TMT) proteomic work was performed on four FFPE samples of cervical cancer and four FFPE of control samples. The validation of biomarkers from cervical proteome were evaluated using Immunohistochemistry (IHC) testing. RESULTS: The most frequent HPV genotype among all other genotypes was HPV 16. There were 2753 proteins quantified by TMT and 336 of these proteins had significant differential abundances. KPNA2, MCM2, COL1A1, and DCN were selected based on functional enrichment analysis and validated by Immunohistochemistry (IHC) testing. The staining of IHC confirmed the upregulation of KPNA2 and MCM2 expression in cervical neoplasia and the downregulation of DCN and COL1A1 in some cervical cancer group subjects. CONCLUSION: The KPNA2 marker was compared to other previously reported biomarkers and is a putative biomarker to be validated in further studies, specifically the relationship with HPV load.

Membrane Proteomic Profiling of Soybean Leaf and Root Tissues Uncovers Salt-Stress-Responsive Membrane Proteins.

Cultivated soybean (Glycine max (L.)), the world's most important legume crop, has high-to-moderate salt sensitivity. Being the frontier for sensing and controlling solute transport, membrane proteins could be involved in cell signaling, osmoregulation, and stress-sensing mechanisms, but their roles in abiotic stresses are still largely unknown. By analyzing salt-induced membrane proteomic changes in the roots and leaves of salt-sensitive soybean cultivar (C08) seedlings germinated under NaCl, we detected 972 membrane proteins, with those present in both leaves and roots annotated as receptor kinases, calcium-sensing proteins, abscisic acid receptors, cation and anion channel proteins, proton pumps, amide and peptide transporters, and vesicle transport-related proteins etc. Endocytosis, linoleic acid metabolism, and fatty acid biosynthesis pathway-related proteins were enriched in roots whereas phagosome, spliceosome and soluble NSF attachment protein receptor (SNARE) interaction-related proteins were enriched in leaves. Using label-free quantitation, 129 differentially expressed membrane proteins were found in both tissues upon NaCl treatment. Additionally, the 140 NaCl-induced proteins identified in roots and 57 in leaves are vesicle-, mitochondrial-, and chloroplast-associated membrane proteins and those with functions related to ion transport, protein transport, ATP hydrolysis, protein folding, and receptor kinases, etc. Our proteomic results were verified against corresponding gene expression patterns from published C08 RNA-seq data, demonstrating the importance of solute transport and sensing in salt stress responses.

Mucus secretions from a conditionally reprogrammed primary endocervical cell culture.

OBJECTIVE: To determine if the secretions collected from a conditionally reprogrammed primary endocervical cell culture are suitable surrogates for mucus studies. DESIGN: Experimental. SETTING: University research center. ANIMAL(S): Female rhesus macaque (n = 2). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Quantitative proteomic analysis using tandem mass tag mass spectrometry liquid chromatography/tandem mass spectrometry. RESULT(S): We identified 3,047 proteins, common proteins present in both primary endocervical cell cultures and the mucus of rhesus macaques. We found a 71% overlap in the top 500 most prevalent proteins in the samples. Cell culture secretions contained many essential mucus proteins, including MUC5B, the primary mucin of the endocervix. CONCLUSION(S): Similarities in secreted proteins suggest that conditionally reprogrammed primary endocervical cells could be used to study mucus secretion in vitro.

Proteomic profiling of concurrently isolated primary microvascular endothelial cells, pericytes, and vascular smooth muscle cells from adult mouse heart.

The microcirculation serves crucial functions in adult heart, distinct from those carried out by epicardial vessels. Microvessels are governed by unique regulatory mechanisms, impairment of which leads to microvessel-specific pathology. There are few treatment options for patients with microvascular heart disease, primarily due to limited understanding of underlying pathology. High throughput mRNA sequencing and protein expression profiling in specific cells can improve our understanding of microvessel biology and disease at the molecular level. Understanding responses of individual microvascular cells to the same physiological or pathophysiological stimuli requires the ability to isolate the specific cell types that comprise the functional units of the microcirculation in the heart, preferably from the same heart, to ensure that different cells have been exposed to the same in-vivo conditions. We developed an integrated process for simultaneous isolation and culture of the main cell types comprising the microcirculation in adult mouse heart: endothelial cells, pericytes, and vascular smooth muscle cells. These cell types were characterized with isobaric labeling quantitative proteomics and mRNA sequencing. We defined microvascular cell proteomes, identified novel protein markers, and confirmed established cell-specific markers. Our results allow identification of unique markers and regulatory proteins that govern microvascular physiology and pathology.

Effects of ex vivo blood anticoagulation and preanalytical processing time on the proteome content of platelets.

BACKGROUND: Ex vivo assays of platelet function critically inform mechanistic and clinical hematology studies, where effects of divergent blood processing methods on platelet composition are apparent, but unspecified. OBJECTIVE: Here, we evaluate how different blood anticoagulation options and processing times affect platelet function and protein content ex vivo. METHODS: Parallel blood samples were collected from healthy human donors into sodium citrate, acid citrate dextrose, EDTA or heparin, and processed over an extended time course for functional and biochemical experiments, including platelet proteome quantification with multiplexed tandem mass tag (TMT) labeling and triple quadrupole mass spectrometry (MS). RESULTS: Each anticoagulant had time-dependent effects on platelet function in whole blood. For instance, heparin enhanced platelet agonist reactivity, platelet-monocyte aggregate formation and platelet extracellular vesicle release, while EDTA increased platelet α-granule secretion. Following platelet isolation, TMT-MS quantified 3357 proteins amongst all prepared platelet samples. Altogether, >400 proteins were differentially abundant in platelets isolated from blood processed at 24 h versus 1 h post-phlebotomy, including proteins pertinent to membrane trafficking and exocytosis. Anticoagulant-specific effects on platelet proteomes included increased complement system and decreased α-granule proteins in platelets from EDTA-anticoagulated blood. Platelets prepared from heparinized blood had higher levels of histone and neutrophil-associated proteins in a manner related to neutrophil extracellular trap (NET) formation and platelet:NET interactions in whole blood ex vivo. CONCLUSION: Our results demonstrate that different anticoagulants routinely used for blood collection have varying effects on platelets ex vivo, where methodology-associated alterations in platelet proteome may influence mechanistic, translational and biomarker studies.

De Novo Arginine Synthesis Is Required for Full Virulence of Xanthomonas arboricola pv. juglandis During Walnut Bacterial Blight Disease.

Walnut blight (WB) disease caused by Xanthomonas arboricola pv. juglandis (Xaj) threatens orchards worldwide. Nitrogen metabolism in this bacterial pathogen is dependent on arginine, a nitrogen-enriched amino acid that can either be synthesized or provided by the plant host. The arginine biosynthetic pathway uses argininosuccinate synthase (argG), associated with increased bacterial virulence. We examined the effects of bacterial arginine and nitrogen metabolism on the plant response during WB by proteomic analysis of the mutant strain Xaj argG-. Phenotypically, the mutant strain produced 42% fewer symptoms and survived in the plant tissue with 2.5-fold reduced growth compared with wild type, while showing itself to be auxotrophic for arginine in vitro. Proteomic analysis of infected tissue enabled the profiling of 676 Xaj proteins and 3,296 walnut proteins using isobaric labeling in a data-dependent acquisition approach. Comparative analysis of differentially expressed proteins revealed distinct plant responses. Xaj wild type (WT) triggered processes of catabolism and oxidative stress in the host under observed disease symptoms, while most of the host biosynthetic processes triggered by Xaj WT were inhibited during Xaj argG- infection. Overall, the Xaj proteins revealed a drastic shift in carbon and energy management induced by disruption of nitrogen metabolism while the top differentially expressed proteins included a Fis transcriptional regulator and a peptidyl-prolyl isomerase. Our results show the critical role of de novo arginine biosynthesis to sustain virulence and minimal growth during WB. This study is timely and critical as copper-based control methods are losing their effectiveness, and new sustainable methods are urgently needed in orchard environments.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Compositional Analysis of Extracellular Aggregates in the Eyes of Patients With Exfoliation Syndrome and Exfoliation Glaucoma.

Purpose: Exfoliation syndrome (XFS) is a condition characterized by the production of insoluble fibrillar aggregates (exfoliation material; XFM) in the eye and elsewhere. Many patients with XFS progress to exfoliation glaucoma (XFG), a significant cause of global blindness. We used quantitative mass spectrometry to analyze the composition of XFM in lens capsule specimens and in aqueous humor (AH) samples from patients with XFS, patients with XFG and unaffected individuals. Methods: Pieces of lens capsule and samples of AH were obtained with consent from patients undergoing cataract surgery. Tryptic digests of capsule or AH were analyzed by high-performance liquid chromatography-mass spectrometry and relative differences between samples were quantified using the tandem mass tag technique. The distribution of XFM on the capsular surface was visualized by SEM and super-resolution light microscopy. Results: A small set of proteins was consistently upregulated in capsule samples from patients with XFS and patients with XFG, including microfibril components fibrillin-1, latent transforming growth factor-ß-binding protein-2 and latent transforming growth factor-ß-binding protein-3. Lysyl oxidase-like 1, a cross-linking enzyme associated with XFS in genetic studies, was an abundant XFM constituent. Ligands of the transforming growth factor-ß superfamily were prominent, including LEFTY2, a protein best known for its role in establishing the embryonic body axis. Elevated levels of LEFTY2 were also detected in AH from patients with XFG, a finding confirmed subsequently by ELISA. Conclusions: This analysis verified the presence of suspected XFM proteins and identified novel components. Quantitative comparisons between patient samples revealed a consistent XFM proteome characterized by strong expression of fibrillin-1, lysyl oxidase-like-1, and LEFTY2. Elevated levels of LEFTY2 in the AH of patients with XFG may serve as a biomarker for the disease.

The potential of tear proteomics for diagnosis and management of orbital inflammatory disorders including Graves' ophthalmopathy.

BACKGROUND: Orbital compartments harbor a variety of tissues that can be independently targeted in a plethora of disorders resulting in sight-threatening risks. Orbital inflammatory disorders (OID) including Graves' ophthalmopathy, sarcoidosis, IgG4 disease, granulomatosis with polyangiitis, and nonspecific orbital inflammation constitute an important cause of pain, diplopia and vision loss. Physical examination, laboratory tests, imaging, and even biopsy are not always adequate to classify orbital inflammation which is frequently deemed "nonspecific". Tear sampling and testing provide a potential "window" to the orbital disease process through a non-invasive technique that allows longitudinal sampling as the disease evolves. Using PubMed/Medline, we identified potentially relevant articles on tear proteomics published in the English language between 1988 and 2021. Of 303 citations obtained, 225 contained empirical data on tear proteins, including 33 publications on inflammatory conditions, 15 in glaucoma, 15 in thyroid eye disease, 1 in sarcoidosis (75) and 2 in uveitis (77,78). Review articles were used to identify an additional 56 relevant articles through citation search. In this review, we provide a short introduction to the potential use of tears as a diagnostic fluid and tool to investigate the mechanism of ocular diseases. A general review of previous tear proteomics studies is also provided, with a focus on Graves' ophthalmopathy (GO), and a discussion of unmet needs in the diagnosis and treatment of orbital inflammatory disease (OID). The review concludes by pointing out current limitations of mass spectrometric analysis of tear proteins and summarizes future needs in the field.