József Tőzsér

Aloe vera downregulates LPS-induced inflammatory cytokine production and expression of NLRP3 inflammasome in human macrophages

Aloe vera has been used in traditional herbal medicine as an immunomodulatory agent inducing anti-inflammatory effects. However, its role on the IL-1β inflammatory cytokine production has not been studied. IL-1β production is strictly regulated both at transcriptional and posttranslational levels through the activity of Nlrp3 inflammasome. In this study we aimed to determine the effect of Aloe vera on the molecular mechanisms of Nlrp3 inflammasome-mediated IL-1β production in LPS-activated human THP-1 cells and monocyte-derived macrophages. Our results show that Aloe vera significantly reduced IL-8, TNFα, IL-6 and IL-1β cytokine production in a dose dependent manner. The inhibitory effect was substantially more pronounced in the primary cells. We found that Aloe vera inhibited the expression of pro-IL-1β, Nlrp3, caspase-1 as well as that of the P2X7 receptor in the LPS-induced primary macrophages. Furthermore, LPS-induced activation of signaling pathways like NF-κB, p38, JNK and ERK were inhibited by Aloe vera in these cells. Altogether, we show for the first time that Aloe vera-mediated strong reduction of IL-1β appears to be the consequence of the reduced expression of both pro-IL-1β as well as Nlrp3 inflammasome components via suppressing specific signal transduction pathways. Furthermore, we show that the expression of the ATP sensor P2X7 receptor is also downregulated by Aloe vera that could also contribute to the attenuated IL-1β cytokine secretion. These results may provide a new therapeutic approach to regulate inflammasome-mediated responses.

Quantitative analysis of proteins in the tear fluid of patients with diabetic retinopathy

Diabetic retinopathy is the leading cause of new cases of legal blindness among adults in the developed countries. Approximately 40% of all people with diabetes have diabetic retinopathy and 5% of these have sight-threatening form. As the advanced stage, where there is a high risk for vision loss, can develop without any serious symptoms, sometimes it is hard to detect it. A non invasive method to detect biomarkers characteristic for diabetic retinopathy from the tear fluid was developed. Tear samples from diabetic patients with no retinopathy, non proliferative and proliferative stages of diabetic retinopathy were analyzed and the protein content of each sample was compared to the protein content of tear pool from healthy volunteers. The samples were labeled with iTRAQ fourplex labels and were analyzed with nanoHPLC coupled ESI-MS/MS mass spectrometry. The lipocalin 1, lactotransferrin, lacritin, lysozyme C, lipophilin A and immunoglobulin lambda chain were identified as possible biomarker candidates with significantly higher relative levels in the tear of patients with diabetic retinopathy.

Clustering of Class I HLA Oligomers with CD8 and TCR: Three-Dimensional Models Based on Fluorescence Resonance Energy Transfer and Crystallographic Data

Fluorescence resonance energy transfer (FRET) data, in accordance with lateral mobility measurements, suggested the existence of class I HLA dimers and oligomers at the surface of live human cells, including the B lymphoblast cell line (JY) used in the present study. Intra- and intermolecular class I HLA epitope distances were measured on JY B cells by FRET using fluorophore-conjugated Ag-binding fragments of mAbs W6/32 and L368 directed against structurally well-characterized heavy and light chain epitopes, respectively. Out-of-plane location of these epitopes relative to the membrane-bound BODIPY-PC (2-(4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholine) was also determined by FRET. Computer-simulated docking of crystallographic structures of class I HLA and epitope-specific Ag-binding fragments, with experimentally determined interepitope and epitope to cell surface distances as constraints, revealed several sterically allowed and FRET-compatible class I HLA dimeric and tetrameric arrangements. Extension of the tetrameric class I HLA model with interacting TCR and CD8 resulted in a model of a supramolecular cluster that may exist physiologically and serve as a functionally significant unit for a network of CD8-HLA-I complexes providing enhanced signaling efficiency even at low MHC-peptide concentrations at the interface of effector and APCs.

Research Applications of Proteolytic Enzymes in Molecular Biology

Proteolytic enzymes (also termed peptidases, proteases and proteinases) are capable of hydrolyzing peptide bonds in proteins. They can be found in all living organisms, from viruses to animals and humans. Proteolytic enzymes have great medical and pharmaceutical importance due to their key role in biological processes and in the life-cycle of many pathogens. Proteases are extensively applied enzymes in several sectors of industry and biotechnology, furthermore, numerous research applications require their use, including production of Klenow fragments, peptide synthesis, digestion of unwanted proteins during nucleic acid purification, cell culturing and tissue dissociation, preparation of recombinant antibody fragments for research, diagnostics and therapy, exploration of the structure-function relationships by structural studies, removal of affinity tags from fusion proteins in recombinant protein techniques, peptide sequencing and proteolytic digestion of proteins in proteomics. The aim of this paper is to review the molecular biological aspects of proteolytic enzymes and summarize their applications in the life sciences.

Natural Compounds as Regulators of NLRP3 Inflammasome-Mediated IL-1β Production

IL-1β is one of the main proinflammatory cytokines that regulates a broad range of immune responses and also participates in several physiological processes. The canonical production of IL-1β requires multiprotein complexes called inflammasomes. One of the most intensively studied inflammasome complexes is the NLRP3 inflammasome. Its activation requires two signals: one signal “primes” the cells and induces the expression of NLRP3 and pro-IL-1β, while the other signal leads to the assembly and activation of the complex. Several stimuli were reported to function as the second signal including reactive oxygen species, lysosomal rupture, or cytosolic ion perturbation. Despite very intensive studies, the precise function and regulation of the NLRP3 inflammasome are still not clear. However, many chronic inflammatory diseases are related to the overproduction of IL-1β that is mediated via the NLRP3 inflammasome. In this review, we aimed to provide an overview of studies that demonstrated the effect of plant-derived natural compounds on NLRP3 inflammasome-mediated IL-1β production. Although many of these studies lack the mechanistic explanation of their action, these compounds may be considered as complementary supplements in the treatment of chronic inflammatory diseases, consumed as preventive agents, and may also be considered as molecular tools to study NLRP3 function.

Quantitative body fluid proteomics in medicine - A focus on minimal invasiveness

Identification of new biomarkers specific for various pathological conditions is an important field in medical sciences. Body fluids have emerging potential in biomarker studies especially those which are continuously available and can be collected by non-invasive means. Changes in the protein composition of body fluids such as tears, saliva, sweat, etc. may provide information on both local and systemic conditions of medical relevance. In this review, our aim is to discuss the quantitative proteomics techniques used in biomarker studies, and to present advances in quantitative body fluid proteomics of non-invasively collectable body fluids with relevance to biomarker identification. The advantages and limitations of the widely used quantitative proteomics techniques are also presented. Based on the reviewed literature, we suggest an ideal pipeline for body fluid analyses aiming at biomarkers discoveries: starting from identification of biomarker candidates by shotgun quantitative proteomics or protein arrays, through verification of potential biomarkers by targeted mass spectrometry, to the antibody-based validation of biomarkers. The importance of body fluids as a rich source of biomarkers is discussed. SIGNIFICANCE Quantitative proteomics is a challenging part of proteomics applications. The body fluids collected by non-invasive means have high relevance in medicine; they are good sources for biomarkers used in establishing the diagnosis, follow up of disease progression and predicting high risk groups. The review presents the most widely used quantitative proteomics techniques in body fluid analysis and lists the potential biomarkers identified in tears, saliva, sweat, nasal mucus and urine for local and systemic diseases.

Highly abundant defense proteins in human sweat as revealed by targeted proteomics and label-free quantification mass spectrometry.

The healthy human skin with its effective antimicrobial defense system forms an efficient barrier against invading pathogens. There is evidence suggesting that the composition of this chemical barrier varies between diseases, making the easily collected sweat an ideal candidate for biomarker discoveries.

Ragweed pollen extract intensifies lipopolysaccharide‐induced priming of NLRP3 inflammasome in human macrophages

Ragweed pollen extract (RWE) possesses intrinsic NADPH oxidase activity that induces oxidative stress by initiating the production of intracellular reactive oxygen species (ROS). The ROS are important contributors to the manifestation of allergic inflammation; furthermore, concomitant exposure to an allergen and an endotoxin trigger a stronger inflammatory response. One of the main pro‐inflammatory cytokines produced in inflammatory responses is interleukin‐1β (IL‐1β), and its production is associated with caspase‐1‐containing inflammasome complexes. Intracellular ROS have been implicated in NLRP3 inflammasome‐mediated IL‐1β production, therefore, we aimed to study whether RWE influences the function of NLRP3 inflammasome. Here we describe that, in the presence of NADPH, RWE significantly elevates lipopolysaccharide‐induced IL‐1β production of THP‐1 cells as well as human primary macrophages and dendritic cells. We also demonstrate that increased IL‐1β production is mediated through NLRP3 inflammasome in THP‐1 macrophages. We provide evidence that RWE elevates cytosolic ROS level in these cells, and ROS inhibitors abolish IL‐1β production. Furthermore, we show that RWE enhances lipopolysaccharide‐induced gene transcription/expression of pro‐IL‐1β and key components of the inflammasome via a ROS‐dependent mechanism.

Changes in the chemical barrier composition of tears in Alzheimer's disease reveal potential tear diagnostic biomarkers

Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases, with increasing prevalence affecting millions of people worldwide. Currently, only autopsy is able to confirm the diagnosis with a 100% certainty, therefore, biomarkers from body fluids obtained by non-invasive means provide an attractive alternative for the diagnosis of Alzheimer`s disease. Global changes of the protein profile were examined by quantitative proteomics; firstly, electrophoresis and LC-MS/MS were used, thereafter, SRM-based targeted proteomics method was developed and applied to examine quantitative changes of tear proteins. Alterations in the tear flow rate, total tear protein concentration and composition of the chemical barrier specific to AD were demonstrated, and the combination of lipocalin-1, dermcidin, lysozyme-C and lacritin was shown to be a potential biomarker, with an 81% sensitivity and 77% specificity.

A molecular model of the full-length human NOD-like receptor family CARD domain containing 5 (NLRC5) protein

BackgroundPattern recognition receptors of the immune system have key roles in the regulation of pathways after the recognition of microbial- and danger-associated molecular patterns in vertebrates. Members of NOD-like receptor (NLR) family typically function intracellularly. The NOD-like receptor family CARD domain containing 5 (NLRC5) is the largest member of this family that also contains the largest number of leucine-rich repeats (LRRs).Due to the lack of crystal structures of full-length NLRs, projects have been initiated with the aim to model certain or all members of the family, but systematic studies did not model the full-length NLRC5 due to its unique domain architecture.Our aim was to analyze the LRR sequences of NLRC5 and some NLRC5-related proteins and to build a model for the full-length human NLRC5 by homology modeling.ResultsLRR sequences of NLRC5 were aligned and were compared with the consensus pattern of ribonuclease inhibitor protein (RI)-like LRR subfamily. Two types of alternating consensus patterns previously identified for RI repeats were also found in NLRC5. A homology model for full-length human NLRC5 was prepared and, besides the closed conformation of monomeric NLRC5, a heptameric platform was also modeled for the opened conformational NLRC5 monomers.ConclusionsIdentification of consensus patterns of leucine-rich repeat sequences helped to identify LRRs in NLRC5 and to predict their number and position within the protein. In spite of the lack of fully adequate template structures, the presence of an untypical CARD domain and unusually high number of LRRs in NLRC5, we were able to construct a homology model for both the monomeric and homo-heptameric full-length human NLRC5 protein.