Two-dimensional electrophoresis of synovial tissue, synovial fluid and serum in patients with rheumatoid arthritis and related diseases

Serum protein profile of rheumatoid arthritis treated with anti-TNF therapy (infliximab)

We analyzed the changes in the serum protein profile by infliximab using two-dimensional gel electrophoresis and mass spectrometry. More than 50 gel spots were seen to increase or decrease in correlation with clinical improvements of RA. The spots corresponding to CRP, C3, and Apo J showed reduced staining intensity, while the spots corresponding to Apo A-I, RBP, and transthyretin were enhanced. The protein profile of RA patients treated with infliximab was mostly similar to that of normal healthy controls except for several protein spots. This suggested that infliximab normalized the serum protein profile of RA patients, leading to modification in the serum lipid profile and antioxidant status in RA.

Human body fluid proteome analysis

The focus of this article is to review the recent advances in proteome analysis of human body fluids, including plasma/serum, urine, cerebrospinal fluid, saliva, bronchoalveolar lavage fluid, synovial fluid, nipple aspirate fluid, tear fluid, and amniotic fluid, as well as its applications to human disease biomarker discovery. We aim to summarize the proteomics technologies currently used for global identification and quantification of body fluid proteins, and elaborate the putative biomarkers discovered for a variety of human diseases through human body fluid proteome (HBFP) analysis. Some critical concerns and perspectives in this emerging field are also discussed. With the advances made in proteomics technologies, the impact of HBFP analysis in the search for clinically relevant disease biomarkers would be realized in the future.

Pasta made from durum wheat semolina fermented with selected lactobacilli as a tool for a potential decrease of the gluten intolerance

A pool of selected lactic acid bacteria was used to ferment durum wheat semolina under liquid conditions. After fermentation, the dough was freeze-dried, mixed with buckwheat flour at a ratio of 3:7, and used to produce the "fusilli" type Italian pasta. Pasta without prefermentation was used as the control. Ingredients and pastas were characterized for compositional analysis. As shown by two-dimensional electrophoresis, 92 of the 130 durum wheat gliadin spots were hydrolyzed almost totally during fermentation by lactic acid bacteria. Mass spectrometry matrix-assisted laser desorption/ionization time-of-flight and reversed phase high-performance liquid chromatography analyses confirmed the hydrolysis of gliadins. As shown by immunological analysis by R5-Western blot, the concentration of gluten decreased from 6280 ppm in the control pasta to 1045 ppm in the pasta fermented with lactic acid bacteria. Gliadins were extracted from fermented and nonfermented durum wheat dough semolina and used to produce a peptic-tryptic (PT) digest for in vitro agglutination tests on cells of human origin. The whole PT digests did not cause agglutination. Affinity chromatography on Sepharose-6-B mannan column separated the PT digests in three fractions. Fraction C showed agglutination activity. The minimal agglutinating activity of fraction C from the PT digest of fermented durum wheat semolina was ca. 80 times higher than that of durum wheat semolina. Pasta was subjected to sensory analysis: The scores for stickiness and firmness were slightly lower than those found for the pasta control. Odor and flavor did not differ between the two types of pasta. These results showed that a pasta biotechnology that uses a prefermentation of durum wheat semolina by selected lactic acid bacteria and tolerated buckwheat flour could be considered as a novel tool to potentially decrease gluten intolerance and the risk of gluten contamination in gluten-free products.

Two-dimensional gel electrophoresis of synovial fluid: method for detecting candidate protein markers for osteoarthritis

Synovial fluid (SF) is a dynamic reservoir for proteins originating from serum, synovial tissue, and cartilage. The composition of the SF proteome may reflect the pathophysiological conditions affecting the circulatory system and cartilage. Our long-term goal is to identify reliable protein markers for osteoarthritis (OA) in SF. We first evaluated the pattern of SF proteins on two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) as a function of protein loading, pH range for isoelectric focusing, and concentration of acrylamide in SDS-PAGE. Removal of albumin and Gamma-globulins from the samples did not improve the detection of protein spots on 2D-PAGE. The repeatability of protein spot intensity was tested by triplicate 2D-PAGE of a given sample; these experiments showed low intrasample variability (correlation coefficients 0.89-0.95). Differences between multiple samples were tested by comparing the 2D-PAGE of four samples. These experiments showed slightly greater variation between samples (correlation coefficients 0.85-0.93) and a number of differentially expressed proteins. The intensity of 18 protein spots differed more than fivefold, and the intensity of nine protein spots differed more than 100-fold. These results show that 2D-PAGE can be used under standard conditions to screen SF samples and identify a small subset of proteins in SF that are potential markers associated with OA.

Proteome Analysis of Diseased Joints from Mice Suffering from Collagen-Induced Arthritis

Strains of mice that are susceptible to autoimmunity have provided experimental models to analyze the molecular basis for the complex multifactorial inheritance of human autoimmune disease. In this study proteins associated with collagen-induced arthritis (CIA) in mice were experimentally identified using a global proteomics approach. Two-dimensional gels of proteins from inflamed and non-inflamed joints showed a distinguished protein profile visualizing about 530 Coomassie-stained protein spots in the pH 4-7 range. A total of 76 spots were identified by peptide mass fingerprinting with good confidence. They included proteins of cytoskeletal origin, chaperones, enzymes and also some signal transduction molecules. Comparison to gels from non-inflamed paws pointed to proteins that were differentially expressed between the control and diseased state. Ferritin light chain and antioxidant protein 2 were slightly more abundant, lymphoid enhancer binding factor 1 slightly, but significantly, less abundant in inflamed paws. Fourteen of the identified proteins were the products of genes that had increased transcript levels in the diseased state. However, on the protein level no significant differences were found in comparison to the controls. This study provides us with the framework for more detailed approaches to understanding the complex disease arthritis that go beyond global proteomics.

Use of two-dimensional gel electrophoresis to measure changes in synovial fluid proteins from patients with rheumatoid arthritis treated with antibody to CD4

Synovial fluid proteins from microliter volumes of synovial fluid were resolved by two-dimensional polyacrylamide gel electrophoresis and detected by silver staining to investigate the feasibility of using two-dimensional (2D) electrophoresis in the clinical research setting and provide global disease information of disease progression. Several hundred proteins could be resolved as spots, many of which displayed the characteristic pattern of plasma-derived glycoproteins. The lowest level of detection was approximately 0.2 ng from a total of 50 microg of protein loaded. Most of the proteins could be identified on the basis of pI and molecular weight when compared with plasma protein maps on the World Wide Web. Unknown proteins were characterized by mass spectrometry of tryptic digests and by comparison with peptide databases. Synovial fluids from patients with rheumatoid arthritis were analyzed using this technique. Each subject received a fixed dose of antibody to CD4 as part of a phase II clinical trial to determine the efficacy of this immunosuppressive treatment in modifying disease activity. Synovial fluid was removed at day 0, followed by administration of antibody. Subsequent removal of synovial fluid and additional administration of antibody were carried out at different times thereafter. Changes in levels of acute-phase proteins were quantified by densitometry of silver-stained 2D polyacrylamide gels. Other parameters of disease progression such as serum C-reactive protein and physician's global assessment of clinical condition were used for comparison. In this way, changes in acute-phase proteins towards normal levels, as measured by 2D polyacrylamide gel electrophoresis, could be correlated with clinical improvement and conventional clinical chemistry measurements. Thus, the system can be used for quantitative analysis of protein expression in sites of autoimmune disease activity such as the synovial fluid of rheumatoid arthritis patients.

Proteins of rat serum V: adjuvant arthritis and its modulation by nonsteroidal anti-inflammatory drugs

The effect of adjuvant arthritis (AA) on the pattern of rat serum proteins includes the upregulation of haptoglobin, orosomucoid, alpha2-macroglobulin, serine protease inhibitor-3, thiostatin, alpha1-antitrypsin, C-reactive protein, and the downregulation of kallikrein-binding protein, alpha1-inhibitor III, apolipoprotein A-I, alpha2-HS-glycoprotein, albumin, apolipoprotein A-IV, transthyretin and transferrin. Minor changes (+/- 20%) are observed for Gc-globulin, ceruloplasmin, and alpha1-macroglobulin. AA thus grossly resembles the acute inflammatory response elicited by the injection of turpentine, although the changes in the levels of negative acute-phase proteins (APP) are smaller in acute inflammation. Indomethacine and ibuprofen inhibit the effects of arthritis on the synthesis of rat serum proteins in different ways: The former is, on average, three times as effective as the latter. Each drug interferes differently with different proteins. In animals without AA, both nonsteroidal anti-inflammatory drugs (NSAID) mimic the inflammatory pattern to a certain extent, with more effect on the negative than on the positive APPs. Overall, the shifts in serum protein levels parallel changes in inflammatory parameters such as joint swelling and serum interleukin-6 (IL-6) activity. Protein quantitation after two-dimensional electrophoresis (2-DE) reveals some effects of the drugs per se which escape detection by other routine tests.

Microelectrophoresis and auxilary micromethods

In this retrospect of approximately 30 years of work with micromethods, some of them developed in our own laboratory, their principles and application to different separation problems are described, such as one- and two-dimensional microelectrophoresis in capillaries and microslab gels, isoelectric focusing in capillaries or microslab gels, microchromatography, microphotometry, and microfluorometry for qualitative and quantitative evaluation of separation patterns. In addition, some useful auxiliary methods are also described, e.g., a method for quantitative protein determination in a microliter volume when neither the volume nor the protein content in that volume are known, and methods for the determination of glycoproteins, amino acids, and sugars in the picomole range.

Proteins of rat serum IV. Time-course of acute-phase protein expression and its modulation by indomethacine

Changes in the concentration of major serum proteins were monitored from day 0 to day 4 in three experimental groups: rats injected with turpentine, rats receiving the turpentine shot and daily doses of indomethacine, and rats given indomethacine alone. In inflamed animals, peak changes for acute-phase reactants, evaluated by two-dimensional electrophoresis (2-DE), were usually observed between 48 and 72 h after the phlogistic stimulus. By itself, indomethacine was found to affect the synthesis of most proteins (except one of the thiostatin variants and ceruloplasmin); the changes in serum levels, whether positive or negative, were the same as upon inflammation (except for kallikrein-binding protein), but their extent and/or timing usually differed. When inflamed animals were given indomethacine, a clear-cut difference in the concentration of some proteins was observed versus inflamed rats not given medication, at 24 h after the start of the treatments. Proteins mainly affected were alpha2-macroglobulin, alpha2-HS-glycoprotein, C-reactive protein and kallikrein-binding protein.

Quantitative photometrical assessment of iron deposits in synovial membranes in different joint diseases

We investigated 86 synovial membranes from patients suffering either from rheumatoid arthritis (RA) or osteoarthritis (OA). Iron deposits in the synovial membrane were stained by the Prussian blue reaction, and the amount of stained iron was quantitatively assessed by microscope photometry. We found a statistically significant increase in iron deposits in the synovial membrane of RA patients when compared to OA patients. The amount of iron deposits correlated with the histological subtype of synovitis, those presenting with more exudative and proliferative features showing greater amounts of iron deposits. We also observed an inverse correlation between the haemoglobin concentration and erythrocytes in the serum and the amount of iron in the synovial membrane. From our data we concluded that iron deposits in the synovial membrane can contribute by several mechanisms, including activation of oxygen radicals, to the chronic inflammatory reaction in RA synovitis.

Clinical applications of two-dimensional electrophoresis

Two-dimensional electrophoresis is increasingly being used as an important tool for biological research although it continues to have few direct clinical applications. In the absence of simple systems to identify and quantify individual proteins or groups of proteins it is unlikely that clinical applications will increase. Measurement of some individual proteins, for example a single acute phase reactant, often yields as much clinically useful information as could be currently expected from quantitation of several proteins with the same physiological role. Cost-containment pressures within the clinical laboratory will prevent the technique from becoming widely used in the clinical laboratory until it can clearly demonstrate that it can produce clinically important and necessary information that can not be obtained by other means. We continue to believe that the technique's greatest potential lies in identifying a protein or proteins whose concentration can be correlated with a disease and whose concentration varies with the progress of the disease. Antibodies to such proteins can then be produced and used to quantify the disease-associated proteins by a simple procedure, such as nephelometry. In spite of our belief of the likely clinical application of the technique there appears to be no systematic use of two-dimensional electrophoresis for this purpose. With clinical specimens a few investigators still run gels of serum or urine from patients with apparently unusual disorders and compare them visually with gels from healthy individuals. Nevertheless, the technique continues to have considerable unmet promise for clinical applications.