Apolipoprotein A-I infiltration in rheumatoid arthritis synovial tissue: a control mechanism of cytokine production?

Targeting the vivid facets of apolipoproteins as a cardiovascular risk factor in rheumatoid arthritis

Mostly, cardiovascular diseases are blamed for casualties in rheumatoid arthritis (RA) patients. Customarily, dyslipidemia is probably the most prevalent underlying cause of untimely demise in people suffering from RA as it hastens the expansion of atherosclerosis. The engagement of inflammatory cytokines like tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), etc., is crucial in the progression and proliferation of both RA and abnormal lipid parameters. Thus, lipid abnormalities should be monitored frequently in patients with both primary and advanced RA stages. An advanced lipid profile examination, i.e., direct role of apolipoproteins associated with various lipid molecules is a more dependable approach for better understanding of the disease and selecting suitable therapeutic targets. Therefore, studying their apolipoproteins is more relevant than assessing RA patients' altered lipid profile levels. Among the various apolipoprotein classes, Apo A1 and Apo B are primarily being focused. In addition, it also addresses how calculating Apo B:Apo A1 ratio can aid in analyzing the disease's risk. The marketed therapies available to control lipid abnormalities are associated with many other risk factors. Hence, directly targeting Apo A1 and Apo B would provide a better and safer option.

Apolipoprotein A1 Modulates Teff/Treg Balance Through Scavenger Receptor Class B Type I-Dependent Mechanisms in Experimental Autoimmune Uveitis

Purpose

Experimental autoimmune uveitis (EAU) is a representative animal model of human uveitis. In this study, we investigated whether apolipoprotein A1 (APOA1) can alleviate EAU and explored its underlying mechanism.

Methods

Mice were immunized with interphotoreceptor retinoid-binding protein 1-20 and treated with APOA1 or vehicle. The retinas, draining lymph nodes (DLNs), and spleens were analyzed. Isolated T cells were used for proliferation, differentiation, and function assays in vitro. Selective inhibitors and pathway agonists were used to study signaling pathways. The effect of APOA1 on peripheral blood mononuclear cells (PBMCs) from uveitis patients was also examined.

Results

Administration of APOA1 ameliorated EAU. APOA1 suppressed pathogenic CD4+ T cell expansion in DLNs and spleen, and decreased the infiltration of effector T (Teff) cells into retina. APOA1 also inhibited T cell proliferation and T helper 1 cell differentiation in vitro and promoted regulatory T (Treg) cell differentiation. APOA1 restricted inflammatory cytokine production from lipopolysaccharide-stimulated PBMCs. Mechanistic studies revealed that the effect of APOA1 was mediated by scavenger receptor class B type I (SR-BI) and downstream signals including phosphatidylinositol 3-kinase/Protein kinase B (PKB, or Akt), p38 mitogen-activated protein kinase, and nuclear factor–κB.

Conclusions

APOA1 ameliorates EAU by regulating the Teff/Treg partially through SR-BI. Our results suggest that APOA1 can be a therapeutic alternative for autoimmune uveitis.

Will rheumatologists ever pick up the arthroscope again?

Conditions prompting physicians and surgeons first adapting endoscopes to peer into joints were mainly the sort of synovial conditions that would concern today's rheumatologists. Rheumatologists were among the pre-World War II pioneers developing and documenting arthroscopy. The post-War father of modern arthroscopy, Watanabe, found rheumatologists among his early students, who took back the technique to their home countries, teaching orthopedists and rheumatologists alike. Rheumatologists described and analyzed the intra-articular features of their common diseases in the '60s and '70s. A groundswell of interest from academic rheumatologists in adapting arthroscopy grew considerably in the '90s with development of "needle scopes" that could be used in an office setting. Rheumatologists helped conduct the very trials the findings of which reduced demand for their arthroscopic services by questioning the efficacy of arthroscopic debridement in osteoarthritis (OA) and also developing biological compounds that greatly reduced the call for any resective intervention in inflammatory arthropathies. The arthroscope has proven an excellent tool for viewing and sampling synovium and continues to serve this purpose at several international research centers. While cartilage is now imaged mainly by magnetic resonance imaging, some OA features - such as a high prevalence of visible calcinosis - beg further arthroscopy-directed investigation. A new generation of "needle scopes" with far superior optics awaits future investigators, should they develop interest.

The anti-inflammatory properties of HDLs are impaired in gout

OBJECTIVE

We sought to determine whether high-density lipoprotein (HDL) function was altered in gout patients.

RESEARCH DESIGN AND METHODS

The study included 95 gout patients and 68 healthy controls. The concentrations of interleukin (IL)-1β and IL-9 were measured by ELISA, and indicators such as blood uric acid, liver and kidney function, blood glucose, and blood lipids were detected. To test for the anti-inflammatory and reverse cholesterol transport (RCT) function of HDL, 11 gout patients and 11 healthy controls were randomly selected for the BioVision cholesterol efflux test, which detects the RCT activity of HDL. To assess the anti-inflammatory function of HDL, cells in co-culture with HDL were treated with inflammatory stimuli such as tumor necrosis factor-α (TNF-α), and then, the cells were assayed for the expression of intercellular adhesion molecules (ICAMs) and vascular cell adhesion molecule-1 (VCAM-1).

RESULTS

In total, this study enrolled 163 participants, including 95 non-hyperlipidemic gout patients and 68 healthy controls. IL-1β and IL-9 levels were significantly higher in the gout group than in the control group (85.26 ± 23.16 vs. 41.47 ± 6.48 and 33.77 ± 12.68 vs. 23.66 ± 4.53, respectively, P < 0.001). Additionally, plasma IL-1β and IL-9 levels were increased along with those of blood uric acid (R² = 0.4116 and R² = 0.4150, respectively, P < 0.001). Compared with the healthy controls, gout patients showed no differences in plasma apoA-1 levels or in the cholesterol efflux assay. Gout patients had increased ICAM-1 expression compared with the healthy controls (88.79 ± 3.68 vs. 86.27 ± 4.64, P < 0.05), but no difference in VCAM-1 expression was found (0.87 ± 0.43 vs. 0.98 ± 0.96, P > 0.05). In this assay, higher values indicate less suppression of ICAM-1 induction, which correlates with a reduced anti-inflammatory capacity.

CONCLUSIONS

The anti-inflammatory activities of HDLs are impaired in gout patients. Key Points • Gout patients show chronic inflammation. • The anti-inflammatory activity of high-density lipoprotein is impaired in gout patients.

Biomarkers of subclinical atherosclerosis in patients with psoriatic arthritis

Background: Psoriatic arthritis (PsA) is a chronic immune-mediated disease. It is associated with an increase in cardiovascular risk factors (obesity, hypertension, diabetes, and dyslipidemia), giving a higher risk of major adverse cardiovascular events. Patients with PsA have an increased incidence of subclinical atherosclerosis and endothelial dysfunction. The aim of this study is to perform a review of the biomarkers of subclinical atherosclerosis in patients with PsA.

Methods: A search was performed in the electronic databases (PubMed, Web of Science, Scopus, and Embase) up until July 2017. Studies were considered if they included data on biomarkers of subclinical atherosclerosis in PsA, and each article was then reviewed for quality and clinical relevance. After completing the literature search, all screened literature was summarized and discussed in our study group (CaRRDs study group).

Results: The initial search produced 532 abstracts, which were limited to 258 potentially relevant articles by preliminary review of the titles and by excluding review articles and case reports (n=274). A further 102 articles were deemed ineligible after examining the abstracts. Full texts of the remaining 156 articles were retrieved. Most articles were excluded because they were not relevant to the biomarkers of subclinical atherosclerosis in psoriasis and/or PsA. In the end, 54 articles were deemed eligible for this review.

Conclusion: Patients with PsA showed more severe atherosclerotic disease compared with patients with only psoriasis. This may have been due to the higher systemic inflammatory burden from the combination of both diseases. In patients with PsA some molecules may be considered as markers of atherosclerotic disease, and their detection may be a prognostic marker, in addition to imaging procedures, for the development of atherosclerotic disease, and could be suitable for the management of patients with PsA.

Cardiovascular Risk Markers and Major Adverse Cardiovascular Events in Psoriatic Arthritis Patients

BACKGROUND

Psoriatic arthritis is a chronic inflammatory arthropathy that affects 14%- 30% of patients with skin and/or nail psoriasis, leading to severe physical limitations and disability. It has been included in the group of spondyloarthropathy with which it shares clinical, radiologic, and serologic features in addition to familial and genetic relationship. Beyond skin and joint involvement, psoriatic arthritis is characterized by a high prevalence of extra-articular manifestation and comorbidities, such as autoimmune, infectious and neoplastic diseases. In particular, an increased risk of cardiovascular comorbidity has been observed in psoriatic arthritis patients.

METHODS

A systematic search was performed in the electronic databases (PubMed, Web of Science, Scopus, EMBASE) up until January 2017. Studies were included if they contained data on CV disease and/or risk factors in PsA and each article was then reviewed for quality and clinical relevance. After completing the literature search all screened literature was summarized and discussed in our study group (CaRDDs study group). All literature and comments were included in the systematic review.

RESULTS

The initial search produced 278 abstracts, which were narrowed to 83 potentially relevant articles by preliminary review of the titles and by excluding review articles and case report (n = 195). Thirty articles were deemed ineligible after examining the abstracts. Full texts of the remaining 53 articles were retrieved. The majority of articles excluded were due to only providing data on patients with psoriasis or due to being not relevant to the CV risk in PsA. In the end, 32 articles were deemed eligible for this review.

CONCLUSION

Psoriatic arthritis appeared significantly associated with subclinical atherosclerosis and endothelial dysfunction and, in turn, with an increased cardiovascular risk. Thus, patients with psoriatic arthritis may benefit from a periodic assessment of surrogate markers of cardiovascular risk. This could help to establish more specific cardiovascular prevention strategies for these patients.

Plasma proteomic analysis of systemic lupus erythematosus patients using liquid chromatography/tandem mass spectrometry with label-free quantification

CONTEXT

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease with unknown etiology.

OBJECTIVE

Human plasma is comprised of over 10 orders of magnitude concentration of proteins and tissue leakages. The changes in the abundance of these proteins have played an important role in various human diseases. Therefore, the research objective of this study is to identify the significantly altered expression levels of plasma proteins from SLE patients compared with healthy controls using proteomic analysis. The plasma proteome profiles of both SLE patients and controls were compared.

METHODS

A total of 19 active SLE patients and 12 healthy controls plasma samples were analyzed using high-resolution electrospray ionization liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS) followed by label-free quantification.

RESULTS

A total of 19 proteins showed a significant level of expression in the comparative LC-ESI-MS/MS triplicate analysis; among these, 14 proteins had >1.5- to three-fold up-regulation and five had <0.2- to 0.6-fold down-regulation. Gene ontology and DAVID (Database Annotation Visualization, and Integrated Discovery) functional enrichment analysis revealed that these proteins are involved in several important biological processes including acute phase inflammatory responses, complement activation, hemostasis, and immune system regulation.

CONCLUSION

Our study identified a group of differentially expressed proteins in the plasma of SLE patients that are involved in the imbalance of the immune system and inflammatory responses. Therefore, these findings may have the potential to be used as prognostic/diagnostic markers for SLE disease assessment or disease monitoring.

High levels of oxidized fatty acids in HDL are associated with impaired HDL function in patients with active rheumatoid arthritis

The objective of this study was to evaluate oxidation products of arachidonic acid and linoleic acid in lipoproteins and synovial fluid (SF) from patients with active rheumatoid arthritis (RA) compared to non-RA controls. High-density lipoproteins (HDL) and low-density lipoproteins (LDL) were isolated from plasma using fast protein liquid chromatography and HDL was isolated from SF using dextran sulfate precipitation. 5-Hydroxyeicosatetraenoic acid (HETE), 12-HETE, 15-HETE, 9 hydroxyoctadecadienoic (HODE), and 13-HODE levels were measured in HDL, LDL, and SF by liquid chromatography-tandem mass spectrometry. HDL's anti-inflammatory function, cholesterol levels, myeloperoxidase (MPO) and paraoxonase 1 (PON1) activities were determined as previously. 5-HETE, 15-HETE, 9-HODE, and 13-HODE levels were significantly increased in HDL and LDL from patients with active RA (n = 10) compared to healthy controls (n = 8) and correlated significantly with measures of systemic inflammation, particularly in HDL (r = 0.65-0.80, p values < 0.004). Higher HETES and HODES in HDL were also significantly correlated with impaired HDL function as measured by the HDL inflammatory index (HII) (r = 0.54-0.58; p values < 0.03). 15-HETE levels and MPO activity were higher in RA SF (n = 10) compared to osteoarthritis (OA) SF(n = 11), and HDL from RA SF had worse function compared to OA SF HDL (HII = 2.1 ± 1.9 and 0.5 ± 0.1), respectively (p < 0.05). Oxidation products of arachidonic acid and linoleic acid are increased in HDL and LDL from patients with active RA compared to healthy controls, and are associated with worse anti-oxidant function of HDL. These results suggest a potential mechanism by which oxidative stress from active RA increases oxidized fatty acids in HDL, promoting HDL dysfunction, and thereby increasing atherosclerotic risk.

Tumor necrosis factor α stimulates endogenous apolipoprotein A-I expression and secretion by human monocytes and macrophages: role of MAP-kinases, NF-κB, and nuclear receptors PPARα and LXRs

Apolipoprotein A-I (ApoA-I) is the main structural and functional protein component of high-density lipoprotein. ApoA-I has been shown to regulate lipid metabolism and inflammation in macrophages. Recently, we found the moderate expression of endogenous apoA-I in human monocytes and macrophages and showed that pro-inflammatory cytokine tumor necrosis factor α (TNFα) increases apoA-I mRNA and stimulates ApoA-I protein secretion by human monocytes and macrophages. Here, we present data about molecular mechanisms responsible for the TNFα-mediated activation of apoA-I gene in human monocytes and macrophages. This activation depends on JNK and MEK1/2 signaling pathways in human monocytes, whereas inhibition of NFκB, JNK, or p38 blocks an increase of apoA-I gene expression in the macrophages treated with TNFα. Nuclear receptor PPARα is a ligand-dependent regulator of apoA-I gene, whereas LXRs stimulate apoA-I mRNA transcription and ApoA-I protein synthesis and secretion by macrophages. Treatment of human macrophages with PPARα or LXR synthetic ligands as well as knock-down of LXRα, and LXRβ by siRNAs interfered with the TNFα-mediated activation of apoA-I gene in human monocytes and macrophages. At the same time, TNFα differently regulated the levels of PPARα, LXRα, and LXRβ binding to the apoA-I gene promoter in THP-1 cells. Obtained results suggest a novel tissue-specific mechanism of the TNFα-mediated regulation of apoA-I gene in monocytes and macrophages and show that endogenous ApoA-I might be positively regulated in macrophage during inflammation.

Production of serum amyloid A in equine articular chondrocytes and fibroblast-like synoviocytes treated with proinflammatory cytokines and its effects on the two cell types in culture

OBJECTIVE

To investigate the role of the major equine acute phase protein serum amyloid A (SAA) in inflammation of equine intraarticular tissues.

SAMPLE

Articular chondrocytes and fibroblast-like synoviocytes (FLSs) from 8 horses (4 horses/cell type).

PROCEDURES

Chondrocytes and FLSs were stimulated in vitro for various periods up to 48 hours with cytokines (recombinant interleukin [IL]-1β, IL-6, tumor necrosis factor-α, or a combination of all 3 [IIT]) or with recombinant SAA. Gene expression of SAA, IL-6, matrix metalloproteinases (MMP)-1 and -3, and cartilage-derived retinoic acid-sensitive protein were assessed by quantitative real-time PCR assay; SAA protein was evaluated by immunoturbidimetry and denaturing isoelectric focusing and western blotting.

RESULTS

All cytokine stimulation protocols increased expression of SAA mRNA and resulted in detectable SAA protein production in chondrocytes and FLSs. Isoforms of SAA in lysed chondrocytes and their culture medium corresponded to those previously detected in synovial fluid from horses with joint disease. When exposed to SAA, chondrocytes and FLSs had increased expression of IL-6, SAA, and MMP3, and chondrocytes had increased expression of MMP-1. Chondrocytes had decreased expression of cartilage-derived retinoic acid-sensitive protein.

CONCLUSIONS AND CLINICAL RELEVANCE

Upregulation of SAA in chondrocytes and FLSs stimulated with proinflammatory cytokines and the proinflammatory effects of SAA suggested that SAA may be involved in key aspects of pathogenesis of the joint inflammation in horses.

Validation of semaphorin 7A and ala-β-his-dipeptidase as biomarkers associated with the conversion from clinically isolated syndrome to multiple sclerosis

BACKGROUND

In a previous proteomics study using pooled cerebrospinal fluid (CSF) samples, we proposed apolipoprotein AI, apolipoprotein AIV, vitronectin, plasminogen, semaphorin 7A, and ala-β-his-dipeptidase as candidate biomarkers associated with the conversion to clinically definite multiple sclerosis (CDMS) in patients with clinically isolated syndromes (CIS). Here, we aimed to validate these results in individual CSF samples using alternative techniques.

METHODS

In a first replication study, levels of apolipoproteins AI and AIV, vitronectin, and plasminogen were measured by ELISA in CSF and serum of 56 CIS patients (29 patients who converted to CDMS (MS converters) and 27 patients who remained with CIS during follow-up (MS non-converters)) and 26 controls with other neurological disorders. Semaphorin 7A and ala-β-his-dipeptidase levels were determined by selected reaction monitoring (SRM) in CSF of 36 patients (18 MS converters, 18 non-converters) and 20 controls. In a second replication study, apolipoprotein AI levels were measured by ELISA in CSF of 74 CIS patients (47 MS converters, 27 non-converters) and 50 individual controls, and levels of semaphorin 7A and ala-beta-his-dipeptidase were determined by SRM in 49 patients (24 MS converters, 25 non-converters) and 22 controls.

RESULTS

CSF levels of apolipoprotein AI were increased (P = 0.043) and levels of semaphorin 7A and ala-β-his-dipeptidase decreased (P = 4.4 × 10(-10) and P = 0.033 respectively) in MS converters compared to non-converters. No significant differences were found in serum levels for apolipoproteins AI and AIV, vitronectin, and plasminogen. Findings with semaphorin 7A and ala-β-his-dipeptidase were also validated in the second replication study, and CSF levels for these two proteins were again decreased in MS converters versus non-converters (P = 1.2 × 10(-4) for semaphorin 7A; P = 3.7 × 10(-8) for ala-β-his-dipeptidase). Conversely, apolipoprotein AI findings were not replicated and CSF levels for this protein did not significantly differ between groups. Furthermore, CSF semaphorin 7A levels were negatively associated with the number of T2 lesions at baseline and one-year follow-up.

CONCLUSIONS

These results validate previous findings for semaphorin 7A and ala-β-his-dipeptidase, and suggest that these proteins play a role as CSF biomarkers associated with the conversion to CDMS in CIS patients.

Biomarkers identified from serum proteomic analysis for the differential diagnosis of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that involves different organs. Its most important feature is the production of specific autoantibodies against nuclear or cytoplasmic antigens. Proteomic analysis of serum, as one of the most readily available body fluids, can be used as a method for clarifying the pathogenesis of SLE. In this study the serum proteome of 13 patients with SLE was evaluated and compared with seven healthy control participants. A specific kit was used to remove high-abundance proteins. After depletion, the protein expression patterns created by two-dimensional gel electrophoresis (2-DE) and MALDI-TOF/TOF-MS were used to identify disease-associated proteins. We found differential expression of 15 protein spots, including seven up-regulated and eight down-regulated proteins in SLE samples, in comparison with healthy participants. These spots were identified by MALDI-TOF/TOF-MS and classified into three groups include keratins, apolipoproteins and albumin, and individual proteins such as transthyretin, haptoglobin and prothrombin. These findings can help to clarify the pathophysiology and mechanism of SLE.

Endogenous apolipoprotein A-I stabilizes ATP-binding cassette transporter A1 and modulates Toll-like receptor 4 signaling in human macrophages

Apolipoprotein A-I (ApoA-I) is the main functional protein component of human high-density lipoproteins. ApoA-I shows various anti-inflammatory and atheroprotective properties toward macrophages; however, endogenous apoA-I expression has not been investigated in macrophages. We have shown that endogenous apoA-I gene is expressed in human macrophages at both mRNA and protein levels. Endogenous ApoA-I is localized in intracellular vesicles and at the external side of the plasma membrane in association with ATP-binding cassette transporter A1 (ABCA1) and lipid rafts in macrophages. We have shown that endogenous ApoA-I stabilizes ABCA1, moreover, down-regulation of ApoA-I by siRNA results in an increase of Toll-like receptor 4 (TLR4) mRNA and membrane surface protein expression, as well as an enhancement of bacterial lipopolysaccharide (LPS)-induced expression of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), and inducible nitric oxide synthase (NOS2) genes in human macrophages. TNF-α stimulates ApoA-I expression and secretion (1.2±0.2 vs. 4.3±0.9 ng/mg total protein) in macrophages. Obtained results suggest that endogenous ApoA-I has anti-inflammatory properties, presumably due to ABCA1 stabilization in macrophages; these results elucidate the cell type-specific mechanism of the TNF-α-mediated regulation of apoA-I gene expression in monocytes and macrophages.

Effect of corticotherapy on proteomics of endometrial fluid from mares susceptible to persistent postbreeding endometritis

The objective was to determine the effects of corticotherapy, in the presence and absence of uterine inflammation, on proteomics of endometrial fluid from mares susceptible to endometritis. In 11 mares, estrus was induced seven times with 5 mg PGF(2α) given at 14-day intervals. The first estrus was a control (no treatment). During the third estrus, mares received glucocorticoid (GC) treatment (20 mg isoflupredone acetate) every 12 h, for three consecutive days. The fifth estrus was the Infected treatment (intrauterine infusion of 1 × 10(9) colony-forming unit/mL Streptococcus equi subspecies zooepidemicus). Finally, the seventh was a combination of GC + Infected treatment (infusion of bacteria 24 h after the first GC treatment). At 12 h after the end of each treatment, uterine samples were collected and submitted to two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) for protein separation and mass spectrometry. Both GC treatment and uterine lumen infection induced proteomic alterations in the endometrial fluid of susceptible mares, characterized by an increase, decrease, or both in the relative optic density and/or frequency of inflammatory acute phase proteins (APP), with major alterations occurring when corticotherapy was applied in the presence of an infectious process. Corticotherapy in the presence of infection increased α(1)-antitrypsin (AAT), transthyretin (TT), and actin, but reduced immunoglobulin G, whereas intrauterine infection increased haptoglobin (Hp) and apolipoprotein A-1 (ApoA-1) and decreased transferrin (TF). Infection reduced levels of α(1)-antitrypsin and transthyretin, whereas corticotherapy in the presence of infection increased their frequency. We concluded that GC influenced the immune response, not only as suppressors, but also as enhancers of local defense mechanisms, through an immunomodulatory action. Short-term corticotherapy could be beneficial for treatment of uterine infectious processes in the mare.

Apolipoprotein A-I exerts bactericidal activity against Yersinia enterocolitica serotype O:3

Apolipoprotein A-I (apoA-I), the main protein component of high density lipoprotein (HDL), is well recognized for its antiatherogenic, antioxidant, and antiinflammatory properties. Here, we report a novel role for apoA-I as a host defense molecule that contributes to the complement-mediated killing of an important gastrointestinal pathogen, Gram-negative bacterium Yersinia enterocolitica. We specifically show that the C-terminal domain of apoA-I is the effector site providing the bactericidal activity. Although the presence of the lipopolysaccharide O-antigen on the bacterial surface is absolutely required for apoA-I to kill the bacteria, apoA-I does not interact with the bacteria directly. To the contrary, exposure of the bacteria by serum proteins triggers apoA-I deposition on the bacterial surface. As our data show that both purified lipid-free and HDL-associated apoA-I displays anti-bacterial potential, apoA-I mimetic peptides may be a promising therapeutic agent for the treatment of certain Gram-negative infections.

The impact of plasma triglyceride and apolipoproteins concentrations on high-density lipoprotein subclasses distribution

OBJECTIVE

To investigate the effect of triglyceride (TG) integrates with plasma major components of apolipoproteins in HDL subclasses distribution and further elicited the TG-apolipoproteins (apos) interaction in the processes of high density lipoprotein (HDL) mature metabolic and atherosclerosis related diseases.

METHODS

Contents of plasma HDL subclasses were quantities by two-dimensional gel electrophoresis associated with immunodetection in 500 Chinese subjects.

RESULTS

Contents of preβ1-HDL, HDL3a, and apoB-100 level along with apoB-100/A-I ratio were significantly increased, whereas there was a significant reduction in the contents of HDL2, apoA-I level as well as apoC-III/C-II ratio with increased TG concentration. Moreover, preβ1-HDL contents is elevated about 9 mg/L and HDL2b contents can be reduced 21 mg/L for 0.5 mmol/L increment in TG concentration. Moreover, with increase of apoA-I levels, HDL2b contents were marginally elevated in any TG concentration group. Furthermore, despite of in the apoB-100/A-I < 0.9 group, the contents of preβ1-HDL increased, and those of HDL2b decreased significantly for subjects in both high and very high TG levels compared to that in normal TG levels. Similarly, in the apoB-100/A-I ≥ 0.9 group, the distribution of HDL subclasses also showed abnormality for subjects with normal TG levels.

CONCLUSIONS

The particle size of HDL subclasses tend to small with TG levels increased which indicated that HDL maturation might be impeded and efficiency of reverse cholesterol transport(RCT) might be weakened. These data suggest that TG levels were not only significantly associated with but liner with the contents of preβ1-HDL and HDL2b. They also raise the possibility that the TG levels effect on HDL maturation metabolism are subjected to plasma apolipoproteins and apolipoproteins ratios.

Apolipoprotein A-I modulates regulatory T cells in autoimmune LDLr-/-, ApoA-I-/- mice

The immune system is complex, with multiple layers of regulation that serve to prevent the production of self-antigens. One layer of regulation involves regulatory T cells (Tregs) that play an essential role in maintaining peripheral self-tolerance. Patients with autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis have decreased levels of HDL, suggesting that apoA-I concentrations may be important in preventing autoimmunity and the loss of self-tolerance. In published studies, hypercholesterolemic mice lacking HDL apoA-I or LDLr(-/-), apoA-I(-/-) (DKO), exhibit characteristics of autoimmunity in response to an atherogenic diet. This phenotype is characterized by enlarged cholesterol-enriched lymph nodes (LNs), as well as increased T cell activation, proliferation, and the production of autoantibodies in plasma. In this study, we investigated whether treatment of mice with lipid-free apoA-I could attenuate the autoimmune phenotype. To do this, DKO mice were first fed an atherogenic diet containing 0.1% cholesterol, 10% fat for 6 weeks, after which treatment with apoA-I was begun. Subcutaneous injections of 500 μg of lipid-free apoA-I was administered every 48 h during the treatment phase. These and control mice were maintained for an additional 6 weeks on the diet. At the end of the 12-week study, DKO mice showed decreased numbers of LN immune cells, whereas Tregs were proportionately increased. Accompanying this increase in Tregs was a decrease in the percentage of effector/effector memory T cells. Furthermore, lipid accumulation in LN and skin was reduced. These results suggest that treatment with apoA-I reduces inflammation in DKO mice by augmenting the effectiveness of the LN Treg response.

HDL interfere with the binding of T cell microparticles to human monocytes to inhibit pro-inflammatory cytokine production

Background

Direct cellular contact with stimulated T cells is a potent mechanism that induces cytokine production in human monocytes in the absence of an infectious agent. This mechanism is likely to be relevant to T cell-mediated inflammatory diseases such as rheumatoid arthritis and multiple sclerosis. Microparticles (MP) generated by stimulated T cells (MP_T) display similar monocyte activating ability to whole T cells, isolated T cell membranes, or solubilized T cell membranes. We previously demonstrated that high-density lipoproteins (HDL) inhibited T cell contact- and MP_T-induced production of IL-1β but not of its natural inhibitor, the secreted form of IL-1 receptor antagonist (sIL-1Ra).

Methodology/Principal Findings

Labeled MP_T were used to assess their interaction with monocytes and T lymphocytes by flow cytometry. Similarly, interactions of labeled HDL with monocytes and MP_T were assessed by flow cytometry. In parallel, the MP_T-induction of IL-1β and sIL-1Ra production in human monocytes and the effect of HDL were assessed in cell cultures. The results show that MP_T, but not MP generated by activated endothelial cells, bond monocytes to trigger cytokine production. MP_T did not bind T cells. The inhibition of IL-1β production by HDL correlated with the inhibition of MP_T binding to monocytes. HDL interacted with MP_T rather than with monocytes suggesting that they bound the activating factor(s) of T cell surface. Furthermore, prototypical pro-inflammatory cytokines and chemokines such as TNF, IL-6, IL-8, CCL3 and CCL4 displayed a pattern of production induced by MP_T and inhibition by HDL similar to IL-1β, whereas the production of CCL2, like that of sIL-1Ra, was not inhibited by HDL.

Conclusions/Significance

HDL inhibit both MP_T binding to monocytes and the MP_T-induced production of some but not all cytokines, shedding new light on the mechanism by which HDL display their anti-inflammatory functions.

Synovial fluid proteins differentiate between the subtypes of juvenile idiopathic arthritis

OBJECTIVE

Juvenile idiopathic arthritis (JIA) is a heterogeneous group of inflammatory diseases, and no clinically useful prognostic markers to predict disease outcome in children with JIA are currently available. Synovial fluid likely reflects the proteins present in the inflamed synovium. The purpose of this study was to delineate the synovial fluid proteome and determine whether protein expression differs in the different subtypes of JIA.

METHODS

Synovial fluid samples obtained from children with oligoarticular JIA, polyarticular JIA, or systemic JIA were compared. Two-dimensional gel electrophoresis for protein separation and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and quadripole time-of-flight mass spectrometry for protein identification were used for this study. Synovial fluid cells were analyzed by polymerase chain reaction (PCR) for the presence of haptoglobin messenger RNA (mRNA).

RESULTS

The synovial fluid proteome of the samples was delineated. The majority of proteins showed overexpression in JIA synovial fluid as compared with noninflammatory control samples. There were 24 statistically significantly differentially expressed spots (>2-fold change; P < 0.05) between the subtypes of JIA. PCR analysis revealed haptoglobin mRNA, suggesting that haptoglobin is locally produced in an inflamed joint in JIA.

CONCLUSION

Despite the similar histologic appearance of inflamed joints in patients with different subtypes of JIA, there are differences in protein expression according to the subtype of JIA. Haptoglobin is differentially expressed between the subtypes of JIA and is locally produced in an inflamed joint in JIA. Haptoglobin and other differentially expressed proteins may be potential biomarkers in JIA.

Acute serum amyloid A induces migration, angiogenesis, and inflammation in synovial cells in vitro and in a human rheumatoid arthritis/SCID mouse chimera model

Serum amyloid A (A-SAA), an acute-phase protein with cytokine-like properties, is expressed at sites of inflammation. This study investigated the effects of A-SAA on chemokine-regulated migration and angiogenesis using rheumatoid arthritis (RA) cells and whole-tissue explants in vitro, ex vivo, and in vivo. A-SAA levels were measured by real-time PCR and ELISA. IL-8 and MCP-1 expression was examined in RA synovial fibroblasts, human microvascular endothelial cells, and RA synovial explants by ELISA. Neutrophil transendothelial cell migration, cell adhesion, invasion, and migration were examined using transwell leukocyte/monocyte migration assays, invasion assays, and adhesion assays with or without anti-MCP-1/anti-IL-8. NF-kappaB was examined using a specific inhibitor and Western blotting. An RA synovial/SCID mouse chimera model was used to examine the effects of A-SAA on cell migration, proliferation, and angiogenesis in vivo. High expression of A-SAA was demonstrated in RA patients (p < 0.05). A-SAA induced chemokine expression in a time- and dose-dependent manner (p < 0.05). Blockade with anti-scavenger receptor class B member 1 and lipoxin A4 (A-SAA receptors) significantly reduced chemokine expression in RA synovial tissue explants (p < 0.05). A-SAA induced cell invasion, neutrophil-transendothelial cell migration, monocyte migration, and adhesion (all p < 0.05), effects that were blocked by anti-IL-8 or anti-MCP-1. A-SAA-induced chemokine expression was mediated through NF-kappaB in RA explants (p < 0.05). Finally, in the RA synovial/SCID mouse chimera model, we demonstrated for the first time in vivo that A-SAA directly induces monocyte migration from the murine circulation into RA synovial grafts, synovial cell proliferation, and angiogenesis (p < 0.05). A-SAA promotes cell migrational mechanisms and angiogenesis critical to RA pathogenesis.

Comparison of serum apolipoprotein A-I between Chinese multiple sclerosis and other related autoimmune disease

Background

Serum apolipoprotein (apo) A-I was considered to be an immune regulator and could suppress pro-inflammatory cytokines generated by activated T cell in some autoimmune diseases. However, the change of serum apoA-I levels in multiple sclerosis (MS) patients is unknown.

Methods

In the presentation we performed a study on serum apoA-I levels in the patients with MS. We enrolled some age and gender matched patients with MS, autoimmune demyelinating diseases (Guillain-Barre Syndrome and Clinically Isolated Syndrome), neuroinflammatory diseases (viral encephalitis), autoimmune connective diseases (rheumatoid arthritis and systemic lupus erythematosus) and healthy control groups, and tested their serum lipids levels: total cholesterol (TC), triglyceride (TG), high-density lipoproteins (HDL), apolipoproteinB100 (apoB100), apolipoproteinA-I (apoA-I).

Results

For all patients, age had no effect on serum apoA-I levels (P > 0.05). Meanwhile, we proved the highest serum apoA-I levels in MS patients and the lowest serum apoA-I levels in SLE patients. Serum apoA-I levels was significantly elevated in female MS patients (P = 0.033; P < 0.05).

Conclusion

In short we believed that patients with MS and other autoimmune demyelination had significantly decreased serum levels of apo A-I.

Cerebrospinal fluid chitinase 3-like 1 levels are associated with conversion to multiple sclerosis

In most patients with multiple sclerosis, the disease initiates with a first attack or clinically isolated syndrome. At this phase, magnetic resonance imaging is an important predictor of conversion to multiple sclerosis. With the exception of oligoclonal bands, the role of other biomarkers in patients with clinically isolated syndrome is controversial. In the present study, we aimed to identify proteins associated with conversion to multiple sclerosis in patients with clinically isolated syndrome. We applied a mass spectrometry-based proteomic approach (isobaric labelling) to previously collected pooled cerebrospinal fluid samples from patients with clinically isolated syndrome, who subsequently converted to clinically definite multiple sclerosis (n=30) and patients who remained as having clinically isolated syndrome (n=30). Next, three of the most represented differentially expressed proteins, i.e. ceruloplasmin, vitamin D-binding protein and chitinase 3-like 1 were selected for validation in individual cerebrospinal fluid samples by enzyme-linked immunosorbent assay. Only chitinase 3-like 1 was validated and cerebrospinal fluid levels were increased in patients who converted to clinically definite multiple sclerosis compared with patients who continued as clinically isolated syndrome (P=0.00002) and controls (P=0.012). High cerebrospinal fluid levels of chitinase 3-like 1 significantly correlated with the number of gadolinium enhancing lesions and the number of T2 lesions observed in brain magnetic resonance imaging scans performed at baseline, and were associated with disability progression during follow-up and shorter time to clinically definite multiple sclerosis (log-rank P-value=0.003). Cerebrospinal fluid chitinase 3-like 1 levels were also measured in a second validation clinically isolated syndrome cohort and found to be increased in patients who converted to multiple sclerosis compared with patients who remained as having clinically isolated syndrome (P=0.018). Our results indicate that patients who will convert to clinically definite multiple sclerosis could be distinguished from those patients who will remain as clinically isolated syndrome by proteomic analysis of cerebrospinal fluid samples. Although protein levels are also increased in other disorders characterized by chronic inflammation, chitinase 3-like 1 may serve as a prognostic biomarker for conversion to multiple sclerosis and development of disability which may help to improve the understanding of the aetiopathogenesis in the early stages of multiple sclerosis.

Blockade of T cell contact-activation of human monocytes by high-density lipoproteins reveals a new pattern of cytokine and inflammatory genes

BACKGROUND

Cellular contact with stimulated T cells is a potent inducer of cytokine production in human monocytes and is likely to play a substantial part in chronic/sterile inflammatory diseases. High-density lipoproteins (HDL) specifically inhibit the production of pro-inflammatory cytokines induced by T cell contact.

METHODOLOGY/PRINCIPAL FINDINGS

To further elucidate the pro-inflammatory functions of cellular contact with stimulated T cells and its inhibition by HDL, we carried out multiplex and microarray analyses. Multiplex analysis of monocyte supernatant revealed that 12 out of 27 cytokines were induced upon contact with stimulated T cells, which cytokines included IL-1Ra, G-CSF, GM-CSF, IFNgamma, CCL2, CCL5, TNF, IL-1beta, IL-6, IL-8, CCL3, and CCL4, but only the latter six were inhibited by HDL. Microarray analysis showed that 437 out of 54,675 probe sets were enhanced in monocytes activated by contact with stimulated T cells, 164 probe sets (i.e., 38%) being inhibited by HDL. These results were validated by qPCR. Interestingly, the cytokines induced by T cell contact in monocytes comprised IL-1beta, IL-6 but not IL-12, suggesting that this mechanism might favor Th17 polarization, which emphasizes the relevance of this mechanism to chronic inflammatory diseases and highlights the contrast with acute inflammatory conditions that usually involve lipopolysaccharides (LPS). In addition, the expression of miR-155 and production of prostaglandin E(2)-both involved in inflammatory response-were triggered by T cell contact and inhibited in the presence of HDL.

CONCLUSIONS/SIGNIFICANCE

These results leave no doubt as to the pro-inflammatory nature of T cell contact-activation of human monocytes and the anti-inflammatory functions of HDL.

Plasma levels of apolipoprotein A1 in malaria-exposed primigravidae are associated with severe anemia

Background

Plasmodium falciparum placental malaria (PM) contributes to 10,000 maternal deaths due to severe anemia (SA) each year in Africa, primarily among primigravid women who are most susceptible. Increased levels of proinflammatory cytokines like TNF-α are associated with maternal anemia in first time mothers but not in other women. Here we aimed to identify additional changes in the plasma proteome associated with pregnancy malaria that may contribute to the development of malaria-related maternal anemia.

Principal Findings

A semi-quantitative mass spectrometry approach was used to compare the relative abundance of plasma proteins in anemic versus non-anemic women with PM. Levels of 24 proteins differed significantly between anemic and non-anemic primigravidae, including several lipid metabolism proteins and molecular transport proteins involved in the acute phase response signaling network. These differences were not observed in multigravid women who enjoy specific immunity that protect them from PM. In a confirmatory study of a larger cohort of primigravid women, levels of the lipid metabolism protein Apolipoprotein (Apo)-AI were significantly lower in PM+ women with SA.

Conclusions

Apo-AI levels are significantly lower in severely anemic primigravidae with PM, and ApoA1 levels positively correlate with hemoglobin levels in primigravid but not multigravid women. Apo-AI is known to have anti-inflammatory effects, and thus Apo-AI reductions may contribute to the inflammatory processes that result in SA.

High-density lipoprotein affects antigen presentation by interfering with lipid raft: a promising anti-atherogenic strategy

Atherosclerosis is a chronic inflammatory disease. Immunomodulation of atherosclerosis emerges as a promising approach to prevention and treatment of this widely prevalent disease. The function of high-density lipoprotein (HDL) to promote reverse cholesterol transport may explain the ability of its protection against atherosclerosis. Findings that HDL and apolipoprotein A-I (apoA-I) inhibited the ability of antigen presenting cells (APCs) to stimulate T cells might be attributed to lipid raft, a cholesterol-rich microdomain exhibiting functional properties depending largely upon its lipid composition. Thus, modulating cholesterol in lipid raft may provide a promising anti-atherogenic strategy.

Is GRP78/BiP a potential salivary biomarker in patients with rheumatoid arthritis?

PURPOSE

In the last few years, serum and joint synovial fluid have been extensively analyzed for the proteomic research of rheumatoid arthritis (RA) biomarkers. Nonetheless, to date, there have been no studies investigating salivary biomarkers in this condition. Therefore, aim of this study is to investigate the presence of potential biomarkers of RA in human whole saliva.

EXPERIMENTAL DESIGN

We combined 2-DE and MS to analyze the whole saliva protein profile of 20 RA patients in comparison with 20 sex- and age-matched healthy subjects.

RESULTS

Eight salivary proteins resulted differentially expressed, namely calgranulin A, calgranulin B, apolipoprotein A-1, 6-phosphogluconate dehydrogenase, peroxiredoxin 5, epidermal fatty acid-binding protein, 78 kDa glucose-regulated protein precursor (GRP78/BiP), and 14-3-3 proteins. It is particularly interesting that chaperone GRP78/BiP showed the greatest increase in RA patients. This finding was validated by Western Blot analysis and the over-expression of GRP78/BiP appear to be distinctive of RA and drugs treatment independent.

CONCLUSIONS AND CLINICAL RELEVANCE

This study provides a rationale for further studies aimed at evaluating any correlation between GRP78/BiP and different clinical/serological aspects of the disease in order to improve the diagnostic algorithms of RA.

Diagnostic and prognostic biomarker discovery strategies for autoimmune disorders

Current clinical, laboratory or radiological parameters cannot accurately diagnose or predict disease outcomes in a range of autoimmune disorders. Biomarkers which can diagnose at an earlier time point, predict outcome or help guide therapeutic strategies in autoimmune diseases could improve clinical management of this broad group of debilitating disorders. Additionally, there is a growing need for a deeper understanding of multi-factorial autoimmune disorders. Proteomic platforms offering a multiplex approach are more likely to reflect the complexity of autoimmune disease processes. Findings from proteomic based studies of three distinct autoimmune diseases are presented and strategies compared. It is the authors' view that such approaches are likely to be fruitful in the movement of autoimmune disease treatment away from reactive decisions and towards a preventative stand point.

Stratification and monitoring of juvenile idiopathic arthritis patients by synovial proteome analysis

Juvenile idiopathic arthritis (JIA) comprises a poorly understood group of chronic, childhood onset, autoimmune diseases with variable clinical outcomes. We investigated whether profiling of the synovial fluid (SF) proteome by a fluorescent dye based, two-dimensional gel (DIGE) approach could distinguish patients in whom inflammation extends to affect a large number of joints, early in the disease process. SF samples from 22 JIA patients were analyzed: 10 with oligoarticular arthritis, 5 extended oligoarticular and 7 polyarticular disease. SF samples were labeled with Cy dyes and separated by two-dimensional electrophoresis. Multivariate analyses were used to isolate a panel of proteins which distinguish patient subgroups. Proteins were identified using MALDI-TOF mass spectrometry with expression further verified by Western immunoblotting and immunohistochemistry. Hierarchical clustering based on the expression levels of a set of 40 proteins segregated the extended oligoarticular from the oligoarticular patients (p < 0.05). Expression patterns of the isolated protein panel have also been observed over time, as disease spreads to multiple joints. The data indicates that synovial fluid proteome profiles could be used to stratify patients based on risk of disease extension. These protein profiles may also assist in monitoring therapeutic responses over time and help predict joint damage.

Comparative analysis of synovial fluid and plasma proteomes in juvenile arthritis--proteomic patterns of joint inflammation in early stage disease

Synovial fluid is a potential source of novel biomarkers for many arthritic disorders involving joint inflammation, including juvenile idiopathic arthritis. We first compared the distinctive protein 'fingerprints' of local inflammation in synovial fluid with systemic profiles within matched plasma samples. The synovial fluid proteome at the time of joint inflammation was then evaluated across clinical subgroups to identify early disease associated proteins. We measured the synovial fluid and plasma proteomes using the two-dimensional fluorescence difference gel electrophoresis approach. Image analysis software was used to highlight the expression levels of joint and subgroup associated proteins across the study cohort (n = 32). A defined subset of 30 proteins had statistically significant differences (p < 0.05) between sample types such that synovial fluid could be differentiated from plasma. Furthermore distinctive synovial proteome expression patterns segregate patient subgroups. Protein expression patterns localized in the chronically inflamed joint therefore have the potential to identify patients more likely to suffer disease which will spread from a single joint to multiple joints. The proteins identified could act as criteria to prevent disease extension by more aggressive therapeutic intervention directed at an earlier stage than is currently possible.

Apolipoprotein A-I and its role in lymphocyte cholesterol homeostasis and autoimmunity

OBJECTIVE

The purpose of this study was to determine the effects of an atherogenic diet on immune function in LDLr(-/-), ApoA-I(-/-) mice.

METHODS AND RESULTS

When LDLr(-/-), ApoA-I(-/-) (DKO), and LDLr(-/-) (SKO) mice were fed an atherogenic diet, DKO had larger peripheral lymph nodes (LNs) and spleens compared to SKO mice. LNs were enriched in cholesterol and contain expanded populations of T, B, dendritic cells, and macrophages. Expansion of all classes of LN cells was accompanied by a approximately 1.5-fold increase in T cell proliferation and activation. Plasma antibodies to dsDNA, beta2-glycoprotein I, and oxidized LDL were increased in DKO, similar to levels in diet-fed Fas(lpr/lpr) mice, suggesting the development of an autoimmune phenotype. Both LN enlargement and cellular cholesterol expansion were "prevented" when diet-fed DKO mice were treated with helper dependent adenovirus expressing apoA-I. Independent of the amount of dietary cholesterol, DKO mice consistently showed lower plasma cholesterol than SKO mice, yet greater aortic cholesterol deposition and inflammation.

CONCLUSIONS

ApoA-I prevented cholesterol-associated lymphocyte activation and proliferation in peripheral LN of diet-fed DKO mice. A approximately 1.5-fold increase in T cell activation and proliferation was associated with a approximately 3-fold increase in concentrations of circulating autoantibodies and approximately 2-fold increase in the severity of atherosclerosis suggesting a common link between plasma apoA-I, inflammation, and atherosclerosis.

Apolipoproteins inhibit the innate immunity activated by necrotic cells or bacterial endotoxin

We suggested earlier that the hydrophobic portions (Hyppos) of molecules, which are normally embedded in the membranes of cells or the core of molecular structures so as to be separated from the aqueous environment, might serve as evolutionarily ancient alarm signals of injury or stress to initiate innate immune responses when they are exposed on the surface. Under normal physiological conditions, the Hyppos released from endogenous or exogenous sources might be handled by 'Hyppo-quenchers'in vivo to maintain the tissue homeostasis and immune modulation. To test this idea, we selected apolipoproteins, which have been known to transport blood lipids and play a role in a number of pathological inflammatory conditions. We examined their role as Hyppo-quenchers in early immune responses and found that apolipoproteins showed significant inhibition of the nuclear factor-kappaB-dependent gene expression in recombinant Chinese hamster ovary (CHO) cells and dendritic cells stimulated by necrotic cells or bacterial endotoxin. In addition, our results indicate that apolipoproteins could dramatically abrogate complement fixation on the surface of necrotic cells. These findings suggest that apolipoproteins, besides having known functions in lipid metabolism, also have a role in preventing the initiation of innate immunity, potentially through neutralizing Hyppos from injured cells or exogenous endotoxin.

Inflammatory lipids as a target for therapy in the rheumatic diseases

As patients with autoimmune rheumatic diseases live longer due to improved therapies and preventive measures, death and disability from cardiovascular events are increasing. Patients with rheumatoid arthritis and systemic lupus erythematosus have an increased risk of atherosclerosis that persists even after accounting for traditional cardiac risk factors. Recent studies strongly suggest that the mechanism is due in part to increased levels of oxidized lipids (such as oxidized low density lipoprotein and pro-inflammatory high density lipoproteins) which cause the inflammatory cascade that ultimately leads to plaque formation. The objective of this review is to discuss how inflammatory lipids contribute to the increased risk of atherosclerosis in rheumatoid arthritis and systemic lupus erythematosus, as well as to propose that these oxidized lipids are a rational target for therapeutic intervention in autoimmune diseases. Published literature was examined to review treatments for pro-inflammatory lipids in autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. In conclusion, it is possible that these oxidized lipids may also contribute to increased disease manifestations in rheumatic conditions. Several new and existing therapies, including statins and high density lipoprotein-associated protein peptide mimetics such as D-4F (apoA-1) target these oxidized lipids and may be useful in both preventing atherosclerosis and treating inflammation in patients with rheumatic diseases.

Apolipoprotein A-I and platelet factor 4 are biomarkers for infliximab response in rheumatoid arthritis

OBJECTIVES

The use of biologicals such as infliximab has dramatically improved the treatment of rheumatoid arthritis (RA). However, factors predictive of therapeutic response need to be identified. A proteomic study was performed prior to infliximab therapy to identify a panel of candidate protein biomarkers of RA predictive of treatment response.

METHODS

Plasma profiles of 60 patients with RA (28 non-responders (as defined by the American College of Rheumatology 20% improvement criteria (ACR20)) negative and 32 responders (ACR70 positive) to infliximab) were studied by surface enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI-TOF MS) technology on two types of arrays, an anion exchange array (SAX2) and a nickel affinity array (IMAC3-Ni). Biomarker characterisation was carried out using classical biochemical methods (purification by ammonium sulfate precipitation or metal affinity chromatography) and identification by matrix assisted laser desorption/ionisation time-of-flight (MALDI-TOF) MS analysis.

RESULTS

Two distinct protein profiles were observed on both arrays and several proteins were differentially expressed in both patient populations. Five proteins at 3.86, 7.77, 7.97, 8.14 and 74.07 kDa were overexpressed in the non-responder group, whereas one at 28 kDa was increased in the responder population (sensitivity>56%, specificity>77.5%). Moreover, combination of several biomarkers improved the sensitivity and specificity of the detection of patient response to over 97%. The 28 kDa protein was characterised as apolipoprotein A-I and the 7.77 kDa biomarker was identified as platelet factor 4.

CONCLUSIONS

Six plasma biomarkers are characterised, enabling the detection of patient response to infliximab with high sensitivity and specificity. Apolipoprotein A-1 was predictive of a good response to infliximab, whereas platelet factor 4 was associated with non-responders.

Proteomic biomarkers for prenatal bisphenol A-exposure in mouse immune organs

Many investigators have encountered difficulty in clarifying the risks of exposure to bisphenol A (BPA), an endocrine disrupting chemical in epidemiological studies or animal experiments. In the present study, we developed biomarkers of BPA-induced proteomic alterations in immune organs of mouse offspring that were prenatally exposed to BPA (15 and 300 mg/L of drinking water; they were exposed to 8.9 +/- 1.8 mg of BPA/kg/day and 171.1 +/- 16.8 mg of BPA/kg/day, respectively) that were evaluated in terms of sex, age, and BPA-exposure levels. We performed 2D-gel analyses of samples from various tissues (thymus and spleen), exposure levels, sex, and ages (3- and 7-week-old) (N = 48), and found seven proteins that were altered in a BPA dose-dependent manner. Among them, we further studiedapo-AI, DPPIII, and VAT1, which are suspected to be associated with endocrine disorders. By performing Western blots, we confirmed BPA upregulation of all three proteins. Moreover, the apo-AI mRNA levels were increased in a BPA dose-dependent manner in 3- and 7-week-old female mice. Females and young offspring were somewhat more sensitive to protein alterations than others. Our study, which is based on proteome analyses, suggests that apo-AI, DPPIII, and VAT represent protein biomarkers for BPA and provide useful mechanistic clues for BPA-induced endocrine disruption.

Treatment with an apolipoprotein A-1 mimetic peptide in combination with pravastatin inhibits collagen-induced arthritis

To evaluate the therapeutic potential of an apolipoprotein A-1 (apoA-1) mimetic peptide, D-4F, in combination with pravastatin in collagen-induced arthritis (CIA), syngeneic Louvain rats were immunized with type II collagen and randomized to vehicle control, D-4F monotherapy, pravastatin monotherapy, or D-4F + pravastatin combination therapy. Clinical arthritis activity was evaluated and radiographs, type II collagen antibody titers, cytokine/chemokine levels, and HDL function analysis were obtained. There was significant reduction in clinical severity scores in the high and medium dose D-4F + pravastatin groups compared to controls (p< or =0.0001). Reduction in erosive disease occurred in the medium/high dose combination groups compared to non-combination groups (p< or =0.01). Favorable changes in cytokines/chemokines were noted with treatment, and response to combination D-4F/pravastatin therapy was associated with improvement in HDL's anti-inflammatory properties. Combination D-4F/pravastatin significantly reduced clinical disease activity in CIA, and may have dual therapeutic potential in other autoimmune diseases with increased cardiovascular morbidity and mortality.

Alpha-1-antitrypsin and complement component C7 are involved in asthma exacerbation

Asthma is the most common chronic disorder in childhood and asthma exacerbation is an important cause of childhood morbidity and hospitalization. Allergic responses are known to be biased toward T-helper type 2 in asthmatics; however, the pathogenesis of asthma is not simple, and our understanding of the disease mechanism remains incomplete. The aim of the present study was to identify protein expression signatures that reflect acute exacerbation of asthma. Plasma was taken twice from pediatric asthmatic patients, once during asthma exacerbation and once during a stable period. Plasma was also taken from healthy children as a control. The protein profiles of plasma during asthma exacerbation were analyzed by 2-DE and 49 spots were differentially expressed during asthma exacerbation. Thirty-eight of the spots were successfully identified by MALDI-TOF MS. Proteins up- or down-regulated during asthma exacerbation were involved in responses to stress and pathogens, in the complement and coagulation cascades, and in acute-phase responses. Among the differentially expressed proteins, up-regulation of alpha-1-antitrypsin and complement component C7 was confirmed by nephelometry and ELISA. Our present results suggest that protease inhibitors and complement components may be involved in asthma exacerbation, and plasma level of alpha-1-antitrypsin may be a potential biomarker for asthma.

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.

Diagnostic performance of amyloid A protein quantification in fat tissue of patients with clinical AA amyloidosis

OBJECTIVE

Amyloid A protein quantification in fat tissue is a new immunochemical method for detecting AA amyloidosis, a rare but serious disease. The objective was to assess diagnostic performance in clinical AA amyloidosis.

METHODS

Abdominal subcutaneous fat tissue of patients with AA amyloidosis was studied at the start of an international clinical trial with eprodisate (NC-503; 1,3-propanedisulfonate; Kiacta), an antiamyloid compound. All patients had renal findings, i.e. proteinuria (> or =1 g/day) or reduced creatinine clearance (20 - 60 ml/min). Controls were patients with other types of amyloidosis and arthritic patients without amyloidosis. Amyloid A protein was quantified by ELISA using monoclonal antihuman serum amyloid A antibodies. Congo red stained slides were scored by light microscopy in a semiquantitative way (0 to 4+).

RESULTS

Ample fat tissue (>50 mg) was available for analysis in 154 of 183 patients with AA amyloidosis and in 354 controls. The sensitivity of amyloid A protein quantification for detection of AA amyloidosis (>11.6 ng/mg fat tissue) was 84% (95% CI: 77 - 89%) and specificity 99% (95% CI: 98 - 100%). Amyloid A protein quantification and semiquantitative Congo red scoring were concordant. Men had lower amyloid A protein values than women (p < 0.0001) and patients with familial Mediterranean fever had lower values than patients with arthritis (p < 0.001) or other inflammatory diseases (p < 0.01).

CONCLUSIONS

Amyloid A protein quantification in fat tissue is a sensitive and specific method for detection of clinical AA amyloidosis. Advantages are independence from staining quality and observer experience, direct confirmation of amyloid AA type, and potential for quantitative monitoring of tissue amyloid over time.

Cells of the synovium in rheumatoid arthritis. Macrophages

The multitude and abundance of macrophage-derived mediators in rheumatoid arthritis and their paracrine/autocrine effects identify macrophages as local and systemic amplifiers of disease. Although uncovering the etiology of rheumatoid arthritis remains the ultimate means to silence the pathogenetic process, efforts in understanding how activated macrophages influence disease have led to optimization strategies to selectively target macrophages by agents tailored to specific features of macrophage activation. This approach has two advantages: (a) striking the cell population that mediates/amplifies most of the irreversible tissue destruction and (b) sparing other cells that have no (or only marginal) effects on joint damage.

Concentrations of serum amyloid A in serum and synovial fluid from healthy horses and horses with joint disease

OBJECTIVE

To determine serum amyloid A (SAA) concentrations in serum and synovial fluid from healthy horses and horses with joint disease and assess the effect of repeated arthrocentesis on SAA concentrations in synovial fluid. Animals-10 healthy horses and 21 horses with various types of joint disease.

PROCEDURES

Serum and synovial fluid samples were obtained from each horse. In 5 of the 10 healthy horses, arthrocentesis was repeated 9 times. Concentrations of SAA were determined via immunoturbidometry.

RESULTS

Serum and synovial fluid SAA concentrations were less than the assay detection limit in healthy horses and did not change in response to repeated arthrocentesis. Synovial fluid SAA concentrations were significantly higher in horses with suspected bacterial joint contamination or infectious arthritis, or tenovaginitis than in healthy controls, and serum concentrations were significantly higher in horses with infectious conditions than in the other groups. Neither serum nor synovial fluid SAA concentrations in horses with low-inflammation joint conditions differed significantly from those in healthy controls. Concentrations of SAA and total protein in synovial fluid were significantly correlated.

CONCLUSIONS AND CLINICAL RELEVANCE

Synovial fluid SAA concentration was a good marker of infectious arthritis and tenovaginitis and appeared to reflect changes in inflammatory activity. The advantages of use of SAA as a marker include the ease and speed of measurement and the fact that concentrations in synovial fluid were not influenced by repeated arthrocentesis in healthy horses. Further study of the SAA response in osteoarthritic joints to assess its usefulness in diagnosis and monitoring of osteoarthritis is warranted.

Role of apolipoproteins in gammadelta and NKT cell-mediated innate immunity

Recent findings reveal unanticipated connections between the fields of lipid metabolism and immunology. They concern gammadelta and NKT cells, nonconventional T cell populations that do not recognize protein antigens and are involved in immunity against cancer, defense against infections, or in regulation of classical immune responses. In this review, we summarize data linking perturbations of apolipoprotein levels and nonconventional T cells with inflammatory processes such as autoimmune diseases or atherosclerosis. We integrate and discuss recent findings on the implication of apolipoproteins in antigen recognition by gammadelta and NKT cells, with emphasis on apolipoproteins A-I and E. These findings also provide indications that apolipoproteins influence antitumor immunosurveillance.

Disease-specific proteins from rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a chronic inflammatory disease that mainly destroys cartilages or bones at the joints. This inflammatory disorder is initiated by self-attack using own immune system, but the detail of pathological mechanism is unclear. Features of autoantigens leading to autoimmune disease are also under veil although several candidates including type II collagen have been suggested to play a role in pathogenesis. In this report, we tried to identify proteins responding to antibodies purified from RA patients and screen proteins up-regulated or down-regulated in RA using proteomic approach. Fibronectin, semaphorin 7A precursor, growth factor binding protein 7 (GRB7), and immunoglobulin mu chain were specifically associated with antibodies isolated from RA synovial fluids. In addition, some metabolic proteins such as adipocyte fatty acid binding protein, galectin-1 and apolipoprotein A1 precursor were overexpressed in RA synovium. Also, expression of peroxiredoxin 2 was up-regulated in RA. On the contrary, expression of vimentin was severely suppressed in RA synoviocytes. Such findings might give some insights into understanding of pathological mechanism in RA.

Amyloid contained in the knee joint meniscus is formed from apolipoprotein A-I

OBJECTIVE

To determine the chemical nature of amyloid deposits found in knee joint menisci.

METHODS

Amyloid was extracted from the menisci of 3 adults who underwent knee joint replacement surgery. The primary structural features of the purified proteins were determined by sequential Edman degradation and tandem mass spectrometry (MS/MS). Tissue specimens were also subjected to in situ hybridization analysis, as well as complementary DNA cloning by reverse transcriptase-polymerase chain reaction (RT-PCR). Additionally, specimens from these 3 patients, as well as other patients with amyloid in the knee joint menisci, were examined immunohistochemically.

RESULTS

Amino acid sequence and MS/MS analyses of the extracts revealed the presence of 60-77-residue components identical to the N-terminal portion of apolipoprotein A-I (Apo A-I). The Apo A-I nature of the amyloid was confirmed by the demonstration that the green birefringent congophilic deposits in the 7 meniscus samples were recognized by an anti-human Apo A-I antibody. That the meniscus itself was the source of the amyloidogenic protein was evidenced through Southern blot analysis, in which an Apo A-I product was generated by RT-PCR from synovial tissue, and further, by the demonstration that the cytoplasm of chondrocytes reacted with the specific Apo A-I probe used for in situ hybridization and was immunostained by the anti-Apo A-I antiserum.

CONCLUSION

Amyloid in the knee joint menisci is formed from Apo A-I that is produced by chondrocytes within the meniscal cartilage. This entity represents yet another localized form of amyloidosis associated with the aging process and may be of pathophysiologic import.

Protective Molecules–C-Reactive Protein (CRP), Serum Amyloid P (SAP), Pentraxin3 (PTX3), Mannose-Binding Lectin (MBL), and Apolipoprotein A1 (Apo A1), and Their Autoantibodies: Prevalence and Clinical Significance in Autoimmunity

Apoptotic defects and impaired clearance of cellular debris are considered key events in the development of autoimmunity, as they can contribute to autoantigen overload, and may initiate an autoimmune response. The pentraxins are a group of highly conserved proteins including the short pentraxins, C-reactive protein (CRP) and serum amyloid-P (SAP), and the long pentraxin-3 (PTX3), which are all involved in innate immunity and in acute-phase responses. Mannan-binding lectin (MBL) is an activator of the complement system, and Apolipoprotein A-1 (Apo A-1) is pivotal in the cholesterol homeostasis and has anti-inflammatory properties. In addition to their role in innate immunity and inflammation, each of these five proteins participates in the removal of damaged and apoptotic cells. In this review, we discuss the clinical significance of different levels of these proteins, their role in the induction or protection from autoimmunity, and the presence of specific autoantibodies against them in the different autoimmune diseases.

[T cell-dependent monocyte activation, TNFalpha and apolipoprotein A-I in autoimmunity and inflammation]

Rheumatoid arthritis is characterized by a massive overproduction of monokines like TNFalpha, IL-6 and IL-1beta, which are predominantly produced by monocytes and macrophages. To date, the exact mechanisms of monocyte/macrophage activation have not been fully elucidated. One possible mechanism is their cell contact-dependent activation by activated T cells. The direct cell contact of monocytes/macrophages and T cells leads to an increased production of pro-inflammatory cytokines such as TNFalpha and IL-1beta. Stringent control of this mechanism by inhibitory factors appears mandatory under physiological conditions in order to avoid systemic cytokine release syndromes. The presence of inhibitory factors in the serum could represent such a mechanism. In healthy donors, apolipoprotein A-I was identified as such an inhibitory serum protein. In patients with rheumatoid arthritis, apolipoprotein A-I is found in decreased concentrations, possibly due to its role as a negative acute phase protein. The role of this and other inhibitory serum molecules are discussed.