Expression of Toll-like receptors in nasal epithelium in allergic rhinitis.

Toll-like receptors (TLRs) are important in barrier homeostasis, but their role in airborne allergies is not fully understood. The aim was to evaluate baseline and allergen-induced expression of TLR proteins in nasal epithelium during allergic rhinitis. Nineteen otherwise healthy non-smoking volunteers both allergic to birch pollen and non-allergic controls were enrolled. We took nasal biopsies before and after off-seasonal intranasal birch pollen or diluent challenge. The expression of epithelial TLR1-7, TLR9-10, and MyD88 proteins was immunohistochemically evaluated from the nasal biopsies. The TLR1-3 and TLR5-10 mRNAs were observed by RNA-microarray. Baseline epithelial expression of TLR proteins was wide and identical in controls and atopics. After off-seasonal intranasal birch pollen challenge, a negative change in the expression score of TLR1 and TLR6 proteins was detected in the atopic group. TLR mRNA expression was not affected by birch pollen challenge. Nasal epithelium seems to express all known TLRs. The mechanisms by which TLR1, and TLR6 proteins could affect pollen allergen transport need further studies.

Label-free mass spectrometry proteome quantification of human embryonic kidney cells following 24 hours of sialic acid overproduction.

BACKGROUND: Cell surface glycoprotein sialylation is one of the most ubiquitous glycan modifications found on higher eukaryotes. The surface sialylation pattern of cells is influenced by the cellular environment but also by the Golgi sialyltransferase activity and flux of metabolites through sialic acid producing pathways. Altered cell surface sialic acid patterns have been observed in several cancers and other pathological conditions. In this experiment we examined the cellular proteomic changes that occur in human embryonic kidney cells after 24 hours of sialic acid overproduction using N-Acetylmannosamine. We utilized high resolution mass spectrometry and label free protein quantification to characterize the relative changes in protein abundance as well as multiple reaction monitoring to quantify the cellular sialic acid levels. RESULTS: Using N-Acetylmannosamine we were able to induce sialic acid production to almost 70-fold compared to non-induced control cells. Mass spectrometric analysis of cellular proteome of control and induced cells identified 1802 proteins of which 105 displayed significant changes in abundance. Functional analysis of the resulting relative changes in protein abundance revealed regulation of several cellular pathways including protein transport, metabolic and signaling pathways and remodeling of epithelial adherens junctions. We also identified several physically interacting co-regulated proteins in the set of changed proteins. CONCLUSIONS: In this experiment we show that increased metabolic flux through sialic acid producing pathway affects the abundance of several protein transport, epithelial adherens junction, signaling and metabolic pathway related proteins.

Searching for cellular partners of hantaviral nonstructural protein NSs: Y2H screening of mouse cDNA library and analysis of cellular interactome.

Hantaviruses (Bunyaviridae) are negative-strand RNA viruses with a tripartite genome. The small (S) segment encodes the nucleocapsid protein and, in some hantaviruses, also the nonstructural protein (NSs). The aim of this study was to find potential cellular partners for the hantaviral NSs protein. Toward this aim, yeast two-hybrid (Y2H) screening of mouse cDNA library was performed followed by a search for potential NSs protein counterparts via analyzing a cellular interactome. The resulting interaction network was shown to form logical, clustered structures. Furthermore, several potential binding partners for the NSs protein, for instance ACBD3, were identified and, to prove the principle, interaction between NSs and ACBD3 proteins was demonstrated biochemically.

Relative quantification of several plasma proteins during liver transplantation surgery.

Plasma proteome is widely used in studying changes occurring in human body during disease or other disturbances. Immunological methods are commonly used in such studies. In recent years, mass spectrometry has gained popularity in high-throughput analysis of plasma proteins. In this study, we tested whether mass spectrometry and iTRAQ-based protein quantification might be used in proteomic analysis of human plasma during liver transplantation surgery to characterize changes in protein abundances occurring during early graft reperfusion. We sampled blood from systemic circulation as well as blood entering and exiting the liver. After immunodepletion of six high-abundant plasma proteins, trypsin digestion, iTRAQ labeling, and cation-exchange fractionation, the peptides were analyzed by reverse phase nano-LC-MS/MS. In total, 72 proteins were identified of which 31 could be quantified in all patient specimens collected. Of these 31 proteins, ten, mostly medium-to-high abundance plasma proteins with a concentration range of 50-2000 mg/L, displayed relative abundance change of more than 10%. The changes in protein abundance observed in this study allow further research on the role of several proteins in ischemia-reperfusion injury during liver transplantation and possibly in other surgery.

Human L-selectin preferentially binds synthetic glycosulfopeptides modeled after endoglycan and containing tyrosine sulfate residues and sialyl Lewis x in core 2 O-glycans.

Endoglycan is a mucin-like glycoprotein expressed by endothelial cells and some leukocytes and is recognized by L-selectin, a C-type lectin important in leukocyte trafficking and extravasation during inflammation. Here, we show that recombinant L-selectin and human T lymphocytes expressing L-selectin bind to synthetic glycosulfopeptides (GSPs). These synthetic glycosulfopeptides contain 37 amino acid residues modeled after the N-terminus of human endoglycan and contain one or two tyrosine sulfates (TyrSO(3)) along with a nearby core-2-based Thr-linked O-glycan with sialyl Lewis x (C2-SLe(x)). TyrSO(3) at position Y118 was more critical for binding than at Y97. C2-SLe(x) at T124 was required for L-selectin recognition. Interestingly, under similar conditions, neither L-selectin nor T lymphocytes showed appreciable binding to the sulfated carbohydrate epitope 6-sulfo-SLe(x). P-selectin also bound to endoglycan-based GSPs but with lower affinity than toward GSPs modeled after PSGL-1, the physiological ligand for P- and L-selectin that is expressed on leukocytes. These results demonstrate that TyrSO(3) residues in association with a C2-SLe(x) moiety within endoglycan and PSGL-1 are preferentially recognized by L-selectin.

Allergens are transported through the respiratory epithelium.

We used a top-down approach with a wide repertoire of wet laboratory and in silico techniques for analyzing the pathogenesis of early events within the type I allergic reactions. We could show a caveolar-dependent transport of the birch pollen allergen through the respiratory epithelium of allergic patients but not of their healthy controls. The application of discovery-driven methodologies can provide new hypotheses worth further analyses of complex multifactorial diseases such as type I allergy.

Network analysis of single nucleotide polymorphisms in asthma.

BACKGROUND: Asthma is a chronic inflammatory disease of the airways with a complex genetic background. In this study, we carried out a meta-analysis of single nucleotide polymorphisms (SNPs) thought to be associated with asthma. METHODS: The literature (PubMed) was searched for SNPs within genes relevant in asthma. The SNP-modified genes were converted to corresponding proteins, and their protein-protein interactions were searched from six different databases. This interaction network was analyzed using annotated vocabularies (ontologies), such as the Gene Ontology and Nature pathway interaction databases. RESULTS: In total, 127 genes with SNPs related to asthma were found in the literature. The corresponding proteins were then entered into a large protein-protein interaction network with the help of various databases. Ninety-six SNP-related proteins had more than one interacting protein each, and a network containing 309 proteins and 644 connections was generated. This network was significantly enriched with a gene ontology entitled "protein binding" and several of its daughter categories, including receptor binding and cytokine binding, when compared with the background human proteome. In the detailed analysis, the chemokine network, including eight proteins and 13 toll-like receptors, were shown to interact with each other. Of great interest are the nonsynonymous SNPs which code for an alternative amino acid sequence of proteins and, of the toll-like receptor network, TLR1, TLR4, TLR5, TLR6, TLR10, IL4R, and IL13 are among these. CONCLUSIONS: Protein binding, toll-like receptors, and chemokines dominated in the asthma-related protein interaction network. Systems level analysis of allergy-related mutations can provide new insights into the pathogenetic mechanisms of disease.