Prevalence and characterization of perinuclear anti-neutrophil cytoplasmic antibodies (P-ANCA) directed against HMG1 and HMG2 in ulcerative colitis (UC)

Fiber Optic Localized Surface Plasmon Resonance Sensor Based on Carboxymethylated Dextran Modified Gold Nanoparticles Surface for High Mobility Group Box 1 (HMGB1) Analysis

Rapid, sensitive, and reliable detection of high mobility group box 1 (HMGB1) is essential for medical and diagnostic applications due to its important role as a biomarker of chronic inflammation. Here, we report a facile method for the detection of HMGB1 using carboxymethyl dextran (CM-dextran) as a bridge molecule modified on the surface of gold nanoparticles combined with a fiber optic localized surface plasmon resonance (FOLSPR) biosensor. Under optimal conditions, the results showed that the FOLSPR sensor detected HMGB1 with a wide linear range (10^-10 to 10^-6 g/mL), fast response (less than 10 min), and a low detection limit of 43.4 pg/mL (1.7 pM) and high correlation coefficient values (>0.9928). Furthermore, the accurate quantification and reliable validation of kinetic binding events measured by the currently working biosensors are comparable to surface plasmon resonance sensing systems, providing new insights into direct biomarker detection for clinical applications.

HMGB1, anti-HMGB1 antibodies, and ratio of HMGB1/anti-HMGB1 antibodies as diagnosis indicator in fever of unknown origin

To evaluate the feasibility of serum HMGB1, anti-HMGB1 antibodies, and HMGB1/anti-HMGB1 ratio as a diagnosis indicator of initial clinical classification in patients with fever of unknown origin (FUO). Ninety-four patients with classical FUO and ninety healthy controls were enrolled in this study. The subjects’ clinical data and serum were collected. The serum concentration of HMGB1 was detected by a commercial HMGB1 ELISA kit, while the serum concentration of anti-HMGB1 antibodies were detected by an in-house built anti-HMGB1 antibodies ELISA kit and further confirmed by immunoblotting. According to the hospital diagnosis on discharge, ninety-four FUO patients were divided into four groups, Infectious disease subgroup, autoimmune disease subgroup, malignant tumor subgroup, and undetermined subgroup. The concentrations of HMGB1 in the infectious disease subgroup and autoimmune disease subgroup were higher than those in the malignant tumor subgroup, undetermined subgroup, and healthy control group. The concentration of anti-HMGB1 antibodies in autoimmune disease subtype group was higher than those in other subgroups as well as healthy control group. According to the distribution of HMGB1 and anti-HMGB1 in scatter plots of the patients with FUO, we found that the ratio of serum HMGB1/anti-HMGB1 is an ideal clinical indicator for differential diagnosis of different subtypes of FUO. The best cut-off was 0.75, and the sensitivity, specificity, and AUC were 66.67%, 87.32%, and 0.8, respectively. Correlation analysis showed that serum concentration of HMGB1 was moderately correlated with CRP in infectious diseases subgroup, and the serum concentration of anti-HMGB1 antibodies was strongly correlated with erythrocyte sedimentation rate in autoimmune disease subgroup. Our study had showed that serum HMGB1/anti-HMGB1 antibodies ratio can help clinicians identify FUO subtypes, thereby avoiding many unnecessary examinations and tests, and improving the effectiveness of clinical diagnosis and treatment of FUO.

HMGB1 Aggravates Pressure Overload-Induced Left Ventricular Dysfunction by Promoting Myocardial Fibrosis

Aim. Fibrosis had important effects on pressure overload-induced left ventricular (LV) dysfunction. High-mobility group box 1 (HMGB1), which was closely associated with fibrosis, was involved in the pressure overload-induced cardiac injury. This study determines the role of HMGB1 in LV dysfunction under pressure overload. Methods. Transverse aortic constriction (TAC) operation was performed on male C57BL/6J mice to build the model of pressure overload, while HMGB1 or PBS was injected into the LV wall. Cardiac function, collagen volume, and relevant genes were detected. Results. Echocardiography demonstrated that the levels of LV ejection fraction (LVEF) were markedly decreased on day 28 after TAC, which was consistent with raised collagen in the myocardium. Moreover, we found that the exposure of mice to TAC + HMGB1 is associated with higher mortality, BNP, and collagen volume in the myocardium and lower LVEF. In addition, real-time PCR showed that the expression of collagen type I, TGF-β, and MMP2 markedly increased in the myocardium after TAC, while HMGB1 overexpression further raised the TGF-β expression but not collagen type I and MMP2 expressions. Conclusion. This study indicated that exogenous HMGB1 overexpression in the myocardium aggravated the pressure overload-induced LV dysfunction by promoting cardiac fibrosis, which may be mediated by increasing the TGF-β expression.

Gastrointestinal Symptoms and Elevated Levels of Anti-Saccharomyces cerevisiae Antibodies Are Associated with Higher Disease Activity in Colombian Patients with Spondyloarthritis

Background

Spondyloarthritis (SpA) is a group of articular inflammatory rheumatic diseases that their gastrointestinal manifestations are around 10% of their extra-articular symptoms, supporting that the inflammatory response of the intestinal mucosa could be associated with the clinical status.

Objectives

To investigate the association between gastrointestinal symptoms and autoantibodies and disease activity between SpA patients, healthy subjects (HS), and patients with inflammatory bowel disease (IBD).

Methods

102 SpA patients, 29 IBD patients, and 117 HS were included. Autoantibodies as ASCA, ANCA, anti-tTG, anti-DGP, ANA, and IgA were measured. The patients were assessed to evaluate clinical and gastrointestinal symptoms. An association analysis was performed using Chi square test and a logistic regression.

Results

Significant differences were found for ASCA levels in SpA (28.2%) compared to IBD (14.2%) and HS (6.0%) (p = 0.029), as well as for ANAS in SpA (49.5%) and IBD (37.9%) (p < 0.001) and abdominal pain (p = 0.012) between SpA (54.3%) and IBD (27.5%). Significant associations were found between BASDAI > 4 and gastrointestinal symptoms (p < 0.05) and IgA (p = 0.007). The association for abdominal bloating was maintained (OR: 3.93, CI-95%, 1.14–13.56; p = 0.030).

Conclusions

Gastrointestinal symptoms, ASCA, ANAS, and IgA levels were associated with high disease activity in SpA compared with IBD and HS.

The western-type diet induces anti-HMGB1 autoimmunity in Apoe(-/-) mice

BACKGROUND AND AIMS

Anti-HMGB1 autoimmunity plays a role in systemic lupus erythematosus (SLE). Because SLE increases atherosclerosis, we asked whether the same autoimmunity might play a role in atherogenesis.

METHODS

We looked for the induction of HMGB1-specific B and T cell responses by a western-type diet (WTD) in the Apoe(-/-) mouse model of atherosclerosis. We also determined whether modifying the responses modulates atherosclerosis.

RESULTS

In the plasma of male Apoe(-/-) mice fed WTD, the level of anti-HMGB1 antibodies (Abs) was detected at ∼50 μg/ml, which was ∼6 times higher than that in either Apoe(-/-) mice fed a normal chow or Apoe(+/+) mice fed WTD (p ≤ 0.0005). The Abs were directed largely toward a novel, dominant epitope of HMGB1 named HMW4; accordingly, compared with chow-fed mice, WTD-fed Apoe(-/-) mice had more activated HMW4-reactive B and T cells (p = 0.005 and p = 0.01, respectively). Compared with mock-immunized mice, Apoe(-/-) mice immunized with HMW4 along with an immunogenic adjuvant showed proportional increases in anti-HMW4 IgG and IgM Abs, HMW4-reactive B-1 and B-2 cells, and HMW4-reactive Treg and Teff cells, which was associated with ∼30% increase in aortic arch lesions (p ≤ 0.01) by two methods. In contrast, Apoe(-/-) mice immunized with HMW4 using a tolerogenic adjuvant showed preferential increases in anti-HMW4 IgM (over IgG) Abs, HMW4-reactive B-1 (over B-2) cells, and HMW4-specific Treg (over Teff) cells, which was associated with ∼40% decrease in aortic arch lesions (p ≤ 0.03).

CONCLUSIONS

Anti-HMGB1 autoimmunity may potentially play a role in atherogenesis.

Neutrophil anti-neutrophil cytoplasmic autoantibody proteins: bactericidal increasing protein, lactoferrin, cathepsin, and elastase as serological markers of inflammatory bowel and other diseases

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract comprising Crohn's disease and ulcerative colitis. Although the pathogenesis of the disease is not clearly defined yet, environmental, genetic and other factors contribute to the onset of the disease. Apart from the clinical and histopathological findings, several serological biomarkers are also employed to detect IBD. One of the most thoroughly studied biomarker is anti-neutrophil cytoplasmic autoantibody (ANCA). We herein provide an overview of the current knowledge on the use of ANCA and certain ANCA proteins, such as bactericidal increasing protein, lactoferrin, cathepsin G and elastase, as serological markers for IBD and other diseases.

Extracellular high-mobility group box 1 mediates pressure overload-induced cardiac hypertrophy and heart failure

Inflammation plays a key role in pressure overload-induced cardiac hypertrophy and heart failure, but the mechanisms have not been fully elucidated. High-mobility group box 1 (HMGB1), which is increased in myocardium under pressure overload, may be involved in pressure overload-induced cardiac injury. The objectives of this study are to determine the role of HMGB1 in cardiac hypertrophy and cardiac dysfunction under pressure overload. Pressure overload was imposed on the heart of male wild-type mice by transverse aortic constriction (TAC), while recombinant HMGB1, HMGB1 box A (a competitive antagonist of HMGB1) or PBS was injected into the LV wall. Moreover, cardiac myocytes were cultured and given sustained mechanical stress. Transthoracic echocardiography was performed after the operation and sections for histological analyses were generated from paraffin-embedded hearts. Relevant proteins and genes were detected. Cardiac HMGB1 expression was increased after TAC, which was accompanied by its translocation from nucleus to both cytoplasm and intercellular space. Exogenous HMGB1 aggravated TAC-induced cardiac hypertrophy and cardiac dysfunction, as demonstrated by echocardiographic analyses, histological analyses and foetal cardiac genes detection. Nevertheless, the aforementioned pathological change induced by TAC could partially be reversed by HMGB1 inhibition. Consistent with the in vivo observations, mechanical stress evoked the release and synthesis of HMGB1 in cultured cardiac myocytes. This study indicates that the activated and up-regulated HMGB1 in myocardium, which might partially be derived from cardiac myocytes under pressure overload, may be of crucial importance in pressure overload-induced cardiac hypertrophy and cardiac dysfunction.

Role of high-mobility group box 1 protein in inflammatory bowel disease

High-mobility group box 1 (HMGB1) protein is a nuclear non-histone DNA-binding protein. It is released into the extracellular milieu and mediates inflammatory responses, which contribute to the pathogenesis of numerous inflammatory diseases, including inflammatory bowel disease (IBD). An online search was performed in PubMed and Web of Science databases for articles providing evidence on the role of HMGB1 in IBD. HMGB1 plays an important role in IBD pathogenesis. Application of HMGB1 antagonists reduced inflammatory reactions and ameliorated colitis in rodent models, which may provide new insights into the diagnosis and treatment of IBD.

Association of circulating level of high mobility group box 1 with disease activity in antineutrophil cytoplasmic autoantibody-associated vasculitis

OBJECTIVE

High mobility group box 1 (HMGB-1), a kind of proinflammatory mediator, is associated with inflammatory conditions and tissue damage. Previous studies have reported that circulating HMGB-1 levels in patients with active antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) were associated with renal manifestations and burdens of granulomatous inflammation. The current study aimed to investigate whether circulating HMGB-1 levels were associated with disease activity in AAV.

METHODS

Plasma samples from 74 patients with AAV in active stage and 65 patients with AAV in remission were collected. The plasma levels of HMGB-1 were determined by enzyme-linked immunosorbent assay. Associations between plasma levels of HMGB-1 with clinical and pathologic parameters were analyzed.

RESULTS

Plasma levels of HMGB-1 in active AAV patients were significantly higher than those in normal controls and AAV patients in remission (median 6.11 [interquartile range (IQR) 3.25-12.79] ng/ml versus median 1.12 [IQR 0.53-1.39] ng/ml, P< 0.001; median 6.11 [IQR 3.25-12.79] ng/ml versus median 3.04 [IQR 1.97-4.63] ng/ml, P < 0.001, respectively). Correlation analysis showed that plasma levels of HMGB-1 correlated with initial serum creatinine (r = 0.275, P = 0.018), estimated glomerular filtration rate (r = -0.277, P = 0.017), the Birmingham Vasculitis Activity Score (r = 0.308, P = 0.008), and C-reactive protein level (r = 0.309, P = 0.008). Among the patients with myeloperoxidase (MPO)-ANCA, those within the first quartile of plasma HMGB-1 levels had a significantly lower level of MPO-ANCA than those within the other 3 quartiles.

CONCLUSION

Circulating HMGB-1 levels might reflect the disease activity and renal involvement of AAV vasculitis.

The spectrum of anti-chromatin/nucleosome autoantibodies: independent and interdependent biomarkers of disease

Autoantibodies directed to chromatin components date back to the discovery of the LE cell and the LE cell phenomenon circa 1950, and subsequent evidence that major components of that reaction were chromatin components and histones in particular. Over time, immunoassays ranging from ELISA and line immunoassays to more modern bead-based assays incorporated histone and DNA mixtures, purified histones, and purified nucleosomes leading to a more thorough understanding of the genesis and pathogenetic relationships of antibodies to chromatin components in systemic lupus erythematosus and other autoimmune conditions. More recently, interest has focussed on other components of chromatin such as high mobility group (HMG) proteins both as targets of B cell responses and pro-inflammatory mediators. This review will focus on immunoassays that utilize chromatin components, their clinical relationships, and newer evidence implicating HMG proteins and DNA neutrophil extracellular traps (NETs) as important players in systemic autoimmune rheumatic diseases.

Anti-high mobility group box 1 and box 2 non-histone chromosomal proteins (HMGB1/HMGB2) antibodies and anti-Saccharomyces cerevisiae antibodies (ASCA): accuracy in differentially diagnosing UC and CD and correlation with inflammatory bowel disease phenotype

BACKGROUND

The development of a supportive diagnostic method has long been required to differentially diagnose ulcerative colitis (UC) and Crohn's disease (CD). Several antibodies circulate in the sera of patients with inflammatory bowel disease. We previously identified the high mobility group box 1 and box 2 non-histone chromosomal proteins (HMGB1 and HMGB2) as novel antigens of perinuclear type anti-neutrophil cytoplasmic antibodies (pANCA) and discovered anti-HMGB1/HMGB2 antibodies in sera from patients with UC. Here, we evaluated the ability of anti-HMGB1/HMGB2 antibodies combined with anti-Saccharomyces cerevisiae antibodies (ASCA) to differentially diagnose UC and CD.

METHODS

We measured titers of anti-HMGB1/HMGB2 antibodies and ASCA in the sera of 213 patients with UC and 93 with CD, using enzyme-linked immunosorbent assays.

RESULTS

Among the patients with UC, 26.8% were positive for anti-HMGB1/HMGB2 antibodies, with 85.0% specificity towards CD and a positive predictive value of 80.3%. Corticosteroids significantly suppressed the titer of anti-HMGB1/HMGB2 antibodies. Among the patients with CD, 24.7% were positive for ASCA, with 96.2% specificity towards UC and a positive predictive value of 74.2%. Interestingly, the positivity rate of anti-HMGB/HMGB2 antibodies was higher (35.7%) in patients with the ileitis type of CD than in patients with CD in the colon (6.2%; significant difference, P < 0.01). The specificity of anti-HMGB1/HMGB2 antibodies in UC for CD in the colon was 93.8%.

CONCLUSIONS

CD in the colon and UC can be differentially diagnosed using anti-HMGB/HMGB2 antibodies combined with ASCA.

Evaluation of inflammatory activity in Crohn’s disease and ulcerative colitis

Crohn’s disease and ulcerative colitis evolve with a relapsing and remitting course. Determination of inflammatory state is crucial for the assessment of disease activity and for tailoring therapy. However, no simple diagnostic test for monitoring intestinal inflammation is available. Noninvasive markers give only indirect assessments of disease activity. Histopathological or endoscopical examinations accurately assess inflammatory activity, but they are invasive, time consuming and expensive and therefore are unsuitable for routine use. Imaging procedures are not applicable for ulcerative colitis. The usefulness of ultrasound and Doppler imaging in assessing disease activity is still a matter of discussion for Crohn’s disease, and an increased interest in computed tomography enterograph (CTE) has been seen, mainly because it can delineate the extent and severity of bowel wall inflammation, besides detecting extraluminal findings. Until now, the available data concerning the accuracy of magnetic resonance enterography in detecting disease activity is less than CTE. Due to this, clinical activity indices are still commonly used for both diseases.

High-mobility group box 1 represents a potential marker of disease activity and novel therapeutic target in systemic lupus erythematosus

High-mobility group box 1 (HMGB1) protein is a nuclear DNA-binding protein, which functions as an alarmin when released from cells. Recent studies implicate extracellular HMGB1 in the pathogenesis of systemic lupus erythematosus (SLE), a prototypical autoimmune disease characterized by the formation of multiple autoantibodies, especially those directed against nucleosomes and double-stranded (ds)DNA. Elevated concentrations of HMGB1 are observed in sera as well as in skin lesions of patients with lupus. Of importance, serum HMGB1 and anti-HMGB1 autoantibody levels correlate with disease activity. In the blood of patients with SLE, HMGB1 is complexed with nucleosomes, at least partially. Moreover, HMGB1-nucleosome complexes from apoptotic cells activate antigen-presenting cells. Injection of HMGB1-nucleosome complexes into nonautoimmune mice results in the formation of autoantibodies against dsDNA and histones in a Toll-like receptor (TLR) 2-dependent manner. Additionally, HMGB1, as a part of DNA-anti-DNA immune complexes, can interact with receptor for advanced glycation end products (RAGE) on the surface of plasmacytoid dendritic cells and B cells leading to TLR9-dependent interferon (IFN)α release and activation of autoreactive B cells, respectively. HMGB1 attached to neutrophil extracellular traps may contribute to IFNα production by facilitating the recognition of self-nucleic acids. Furthermore, HMGB1, complexed with DNA and pathogenic anti-DNA autoantibodies, activates its receptors, TLR2, TLR4 and RAGE, and may thereby be involved in anti-DNA autoantibody-induced kidney damage in lupus nephritis. Collectively, these findings suggest that HMGB1 is a potential marker of disease activity and, because of its probable involvement in the pathogenesis, a novel therapeutic target in SLE.

Nucleic acid-associated autoantigens: pathogenic involvement and therapeutic potential

Autoimmunity to ubiquitously expressed macromolecular nucleic acid-protein complexes such as the nucleosome or the spliceosome is a characteristic feature of systemic autoimmune diseases. Disease-specificity and/or association with clinical features of some of these autoimmune responses suggest pathogenic involvement which, however, has been proven in only a few cases so far. Although the mechanisms leading to autoimmunity against nucleic acid-containing complexes are still far from being fully understood, there is increasing experimental evidence that the nucleic acid component may act as a co-stimulator or adjuvans via activation of nucleic acid-binding receptor systems such as Toll-like receptors in antigen-presenting cells. Dysregulated apoptosis and inappropriate stimulation of nucleic acid-sensing receptors may lead to loss of tolerance against the protein components of such complexes, activation of autoreactive T cells and formation of autoantibodies. This has been demonstrated to occur in systemic lupus erythematosus and seems to represent a general mechanism that may be crucial for the development of systemic autoimmune diseases. This review provides a comprehensive overview of the most thoroughly-characterized nucleic acid-associated autoantigens, describing their structure and biological function, as well as the nature and pathogenic importance of the reactivities directed against them. Furthermore, recent advances in immunotherapy such as antigen-specific approaches targeted at nucleic acid-binding antigens are discussed.

Multidimensional degradomics identifies systemic autoantigens and intracellular matrix proteins as novel gelatinase B/MMP-9 substrates

The action radius of matrix metalloproteinases or MMPs is not restricted to massive extracellular matrix (ECM) degradation, it extends to the proteolysis of numerous secreted and membrane-bound proteins. Although many instances exist in which cells disintegrate, often in conjunction with induction of MMPs, the intracellular MMP substrate repertoire or degradome remains relatively unexplored. We started an unbiased exploration of the proteolytic modification of intracellular proteins by MMPs, using gelatinase B/MMP-9 as a model enzyme. To this end, multidimensional degradomics technology was developed by the integration of broadly available biotechniques. In this way, 100-200 MMP-9 candidate substrates were isolated, of which 69 were identified. Integration of these results with the known biological functions of the substrates revealed many novel MMP-9 substrates from the intracellular matrix (ICM), such as actin, tubulin, gelsolin, moesin, ezrin, Arp2/3 complex subunits, filamin B and stathmin. About 2/3 of the identified candidates were autoantigens described in multiple autoimmune conditions and in cancer (e.g. annexin I, nucleolin, citrate synthase, HMGB1, alpha-enolase, histidyl-tRNA synthetase, HSP27, HSC70, HSP90, snRNP D3). These findings led to the insight that MMPs and other proteases may have novel (immuno)regulatory properties by the clearance of toxic and immunogenic burdens of abundant ICM proteins released after extensive necrosis. In line with the extracellular processing of organ-specific autoantigens, proteolysis might also assist in the generation of immunodominant 'neo-epitopes' from systemic autoantigens. The study of proteolysis of ICM molecules, autoantigens, alarmins and other crucial intracellular molecules may result in the discovery of novel roles for proteolytic modification.

High Mobility Group Box 1: a potential therapeutic target for systemic lupus erythematosus

High Mobility Group Box 1 (HMGB1) is a nuclear protein participating in chromatin architecture and transcriptional regulation. Recently, there is increasing evidence that HMGB1 contributes to the pathogenesis of chronic inflammatory and autoimmune diseases due to its pro-inflammatory and immunostimulatory properties. Elevated expression of HMGB1 was found in the sera of patients and mice with systemic lupus erythematosus (SLE). In addition, it has been shown that HMGB1 may act as a proinflammatory mediator in antibody-induced kidney damage in SLE. All theses findings suggest that HMGB1 have important biological effects in autoimmunity that might be a promising therapeutic target for SLE. In this review, we will briefly discuss the biological features of HMGB1 and summarize recent advances on the role of HMGB1 in the pathogenesis and treatment of SLE.

High-mobility group box-1 in ischemia-reperfusion injury of the heart

BACKGROUND

High-mobility group box-1 (HMGB1) is a nuclear factor released by necrotic cells and by activated immune cells. HMGB1 signals via members of the toll-like receptor family and the receptor for advanced glycation end products (RAGE). Although HMGB1 has been implicated in ischemia/reperfusion (I/R) injury of the liver and lung, its role in I/R injury of the heart remains unclear.

METHODS AND RESULTS

Here, we demonstrate that HMGB1 acts as an early mediator of inflammation and organ damage in I/R injury of the heart. HMGB1 levels were already elevated 30 minutes after hypoxia in vitro and in ischemic injury of the heart in vivo. Treatment of mice with recombinant HMGB1 worsened I/R injury, whereas treatment with HMGB1 box A significantly reduced infarct size and markers of tissue damage. In addition, HMGB1 inhibition with recombinant HMGB1 box A suggested an involvement of the mitogen-activated protein kinases jun N-terminal kinase and extracellular signal-regulated kinase 1/2, as well as the nuclear transcription factor nuclear factor-kappaB in I/R injury. Interestingly, infarct size and markers of tissue damage were not affected by administration of recombinant HMGB1 or HMGB1 antagonists in RAGE(-/-) mice, which demonstrated significantly reduced damage in reperfused hearts compared with wild-type mice. Coincubation studies using recombinant HMGB1 in vitro induced an inflammatory response in isolated macrophages from wild-type mice but not in macrophages from RAGE(-/-) mice.

CONCLUSIONS

HMGB1 plays a major role in the early event of I/R injury by binding to RAGE, resulting in the activation of proinflammatory pathways and enhanced myocardial injury. Therefore, blockage of HMGB1 might represent a novel therapeutic strategy in I/R injury.

Autoantibodies in primary sclerosing cholangitis

The aetiology of primary sclerosing cholangitis (PSC) is not known and controversy exists as to whether PSC should be denominated an autoimmune disease. A large number of autoantibodies have been detected in PSC patients, but the specificity of these antibodies is generally low, and the frequencies vary largely between different studies. The presence of autoantibodies in PSC may be the result of a nonspecific dysregulation of the immune system, but the literature in PSC points to the possible presence of specific antibody targets in the biliary epithelium and in neutrophil granulocytes. The present review aims to give an overview of the studies of autoantibodies in PSC, with a particular emphasis on the prevalence, clinical relevance and possible pathogenetic importance of each individual marker.

The role of cell death in the pathogenesis of autoimmune disease: HMGB1 and microparticles as intercellular mediators of inflammation

Cell death is critical to normal homeostasis, although this process, when increased aberrantly, can lead to the production of pro-inflammatory mediators promoting autoimmunity. Two novel intercellular mediators of inflammation generated during cell death are high mobility group box 1 (HMGB1) protein and microparticles (MPs). HMGB1 is a nuclear protein that functions in transcription when inside the nucleus but takes on pro-inflammatory properties when released during cell death. Microparticles are small, membrane-bound structures that extrude from cells when they die and contain cell surface proteins and nuclear material from their parent cells. MPs circulate widely throughout the vasculature and mediate long-distance communication between cells. Both MPs and HMGB1 have been implicated in the pathogenesis of a broad spectrum of inflammatory diseases, including the prototypic autoimmune conditions systemic lupus erythematosus and rheumatoid arthritis. Given their range of activity and association with active disease, both structures may prove to be targets for effective therapy in these and other disorders.

High mobility group box chromosomal protein 1 in patients with renal diseases

BACKGROUND/AIM

The high mobility group box chromosomal protein 1 (HMGB1), a nuclear DNA-binding protein, has recently been recognized as a new proinflammatory cytokine. The purpose of this study was to examine the significance of HMGB1 in patients with renal diseases.

METHODS

HMGB1 concentrations in sera were measured by enzyme-linked immunosorbent assay, and antibodies against HMGB1 were examined by Western blotting in patients who underwent renal biopsies and in healthy controls. Immunohistochemistry for HMGB1 was also performed.

RESULTS

Serum HMGB1 was more likely to be positive in patients who underwent renal biopsies as compared with the controls. Patients with anti-neutrophil cytoplasmic antibody-related glomerulonephritis (ANCA-GN) and those with Henoch-Schonlein purpura nephritis showed a significantly higher tendency to be HMGB1 positive. The presence of anti-HMGB1 antibody was not associated with the presence of serum HMGB1. Immunohistochemistry revealed that HMGB1 was expressed in mononuclear cells in the interstitium or in the glomeruli of some patients with ANCA-GN or IgA nephropathy (IgAN). Subanalysis demonstrated that among patients with IgAN, those who had crescent formation showed a higher tendency to be HMGB1 positive than those who did not.

CONCLUSIONS

HMGB1 was expressed in the sera of patients with renal diseases who underwent renal biopsies, especially among those who had vasculitis including ANCA-GN, Henoch-Schonlein purpura nephritis, and IgAN with glomerular crescents.

High-mobility group box 1 (HMGB1) protein at the crossroads between innate and adaptive immunity

Tissue damage occurs often in the life of mammals and is usually repaired. Dying cells are swiftly phagocytosed, but before disappearing, they alert surrounding cells to activate homeostatic programs. They release signals that recruit inflammatory cells to the site of injury, promote cell migration and cell division to replace dead cells, and activate the immune system in anticipation of microbial invasion. Many of these events involve high-mobility group box 1 protein (HMGB1), a nuclear protein that is released passively when necrotic cells lose the integrity of their membranes. HMGB1 behaves as a trigger of inflammation, attracting inflammatory cells, and of tissue repair, recruiting stem cells and promoting their proliferation. Moreover, HMGB1 activates dendritic cells (DCs) and promotes their functional maturation and their response to lymph node chemokines. Activated leukocytes actively secrete HMGB1 in the microenvironment. Thus, HMGB1 acts in an autocrine/paracrine fashion and sustains long-term repair and defense programs. DCs secrete HMGB1 several hours after contact with the first maturation stimulus; HMGB1 secretion is critical for their ability to reach the lymph nodes, to sustain the proliferation of antigen-specific T cells, to prevent their activation-dependent apoptosis, and to promote their polarization towards a T-helper 1 phenotype. These immune responses will also be directed against self-antigens that DCs process at the time of injury and can lead to autoimmunity.

Increased serum high mobility group box-1 level in Churg-Strauss syndrome

Churg-Strauss syndrome (CSS) is a rare form of systemic vasculitis occurring in patients with asthma and hypereosinophilia; however, its mechanisms involved in the severe tissue inflammation with vasculitis are poorly understood. High mobility group box 1 (HMGB1) protein, originally identified as a DNA binding protein, also has potent pro-inflammatory and proangiogenic properties. In this study, we hypothesized that HMGB1 might be associated with CSS, and examined serum HMGB1 levels and compared those of asthma patients and healthy volunteers. We also investigated HMGB1 expression in the lesion, and eosinophil HMGB1 amount in CSS patients. We found that the serum HMGB1 levels in CSS patients were significantly higher than those of asthma patients and healthy volunteers. Eosinophils in the CSS lesion expressed HMGB1 and HMGB1 level in eosinophils from CSS patients was significantly higher than that of asthma patients, while there was no significant difference in HMGB1 levels in peripheral mononuclear cells. The serum HMGB1 level in CSS patients decreased after the steroid therapy, and showed significant positive correlations with several molecules, including soluble interleukin-2 receptor, soluble thrombomodulin, and eosinophil cationic protein in sera. We propose that HMGB1 might contribute to the pathogenesis of CSS.

Post-translational methylation of high mobility group box 1 (HMGB1) causes its cytoplasmic localization in neutrophils

High mobility group box 1 (HMGB1) protein plays multiple roles in transcription, replication, and cellular differentiation. HMGB1 is also secreted by activated monocytes and macrophages and passively released by necrotic or damaged cells, stimulating inflammation. HMGB1 is a novel antigen of anti-neutrophil cytoplasmic antibodies (ANCA) observed in the sera of patients with ulcerative colitis and autoimmune hepatitis, suggesting that HMGB1 is secreted from neutrophils to the extracellular milieu. However, the actual distribution of HMGB1 in the cytoplasm of neutrophils and the mechanisms responsible for it are obscure. Here we show that HMGB1 in neutrophils is post-translationally mono-methylated at Lys42. The methylation alters the conformation of HMGB1 and weakens its DNA binding activity, causing it to become largely distributed in the cytoplasm by passive diffusion out of the nucleus. Thus, post-translational methylation of HMGB1 causes its cytoplasmic localization in neutrophils. This novel pathway explains the distribution of nuclear HMGB1 to the cytoplasm and is important for understanding how neutrophils release HMGB1 to the extracellular milieu.

Mechanisms of Disease: the role of high-mobility group protein 1 in the pathogenesis of inflammatory arthritis

High-mobility group protein 1 (HMG1) is a nonhistone nuclear protein that is a prototype of a dual-function alarmin whose immune activity is dependent upon its cellular location. Inside the cell, HMG1 binds to DNA and has a role in transcriptional regulation. Outside the cell, HMG1 acts as a cytokine and has activities that resemble those of tumor necrosis factor. The cytokine activities of HMG1 become manifest when this protein translocates from the nucleus to the cytoplasm and, eventually, into the external milieu; this translocation occurs during cell activation and cell death. Given its cytokine activity, HMG1 has been implicated in the pathogenesis of a broad range of immune-mediated diseases including arthritis. The role for this protein in arthritis was established by observations of the expression of HMG1 in synovial tissue of patients with rheumatoid arthritis as well as in the joints of animals used to model arthritis. Furthermore, in the mouse model of collagen-induced arthritis, treatment with antibodies to HMG1 or to an inhibitory domain of HMG1 can attenuate joint inflammation and damage. These studies identify a novel pathway in the pathogenesis of inflammatory arthritis, as well as a new target for biologic therapy.

Association of IL-10 and TNFalpha genotypes with ANCA appearance in ulcerative colitis

The appearance of autoantibodies is a common characteristic of ulcerative colitis (UC). Specifically, anti-neutrophil cytoplasmic antibodies (ANCA) are the most prevalent in this disease and their synthesis may be genetically conditioned. The aim of the present study was to test the influence on appearance of autoantibodies of IL-10 and TNFalpha genes promoter polymorphisms, which control cytokine levels. Genetic polymorphisms of TNFalpha (-308 G/A) and IL-10 (-1082 G/A) and ANCA and anti-goblet cells antibodies (GAB) presence were determined in 99 UC patients. The -308A* allele and -308AA/AGTNFalpha genotypes (high producer), clearly correlated with ANCA positivity (p = 0.004 and p = 0.007, respectively). Additionally, homozygous carriage of the -1082A*IL-10 allele (low producer) significantly associated with ANCA presence (p = 0.007). Furthermore, combination of both genotypes (low IL-10/high TNFalpha producer genotype) had a greater influence on ANCA positivity than each individual genotype (p = 0.008). ANCA production in UC thus appears to be conditioned by IL-10 and TNFalpha genotypes.

Factors masking HMGB1 in human serum and plasma

High mobility group box 1 protein (HMGB1) is a ubiquitously expressed architectural chromosomal protein. Recently, it has become obvious that HMGB1 can also act as a proinflammatory mediator when actively secreted during cell activation or passively released from necrotic cells. HMGB1 appears to play an important role in the pathogenesis of diseases, including sepsis and rheumatoid arthritis. However, easy, sensitive, and reliable detection systems are required to investigate the clinical significance of HMGB1 in clinical samples for diagnosis and prognosis of diseases. Here, we describe sensitive ELISAs for the detection of HMGB1 in cell culture medium and cell lysates. However, these assays failed to reliably quantitate HMGB1 in serum and plasma when compared with immunoblot analysis. We found that serum/plasma components bind to HMGB1 and interfere with its detection by ELISA systems. In most serum/plasma samples investigated, including those from healthy individuals, we detected IgG antibodies binding to HMGB1. The titers of these antibodies correlated with the capacity of sera to interfere with the detection of recombinant HMGB1 by ELISA. Furthermore, HMGB1 coimmunoprecipitated with several proteins including IgG1, as identified by mass spectrometry. These HMGB1 interacting proteins are currently characterized and may contribute to complex formation, masking, and possibly, modulation of cytokine activity of HMGB1.

Serologic markers in inflammatory bowel disease

Inflammatory bowel disease (IBD) is an enduring disease involving mostly young people, with symptoms of bloody diarrhea and abdominal cramps. Several antibodies have been associated with IBD, the 2 most comprehensively studied being autoantibodies to neutrophils (atypical perinuclear anti-neutrophil cytoplasmic antibodies) and anti-Saccharomyces cerevisiae antibodies. This review focuses on the value of these antibodies for diagnosing IBD, differentiating Crohn disease from ulcerative colitis, indeterminate colitis, monitoring disease, defining clinical phenotypes, predicting response to therapy, and as subclinical markers. Pancreatic antibodies and newly identified anti-microbial antibodies (anti-outer membrane porin C, anti-I2, and anti-flagellin) are also reviewed.

Advances in clinical laboratory tests for inflammatory bowel disease

Inflammatory bowel disease (IBD) is a generic term that refers to Crohn's disease and chronic ulcerative colitis (UC). The CD and UC are considered to be distinct forms of IBD; but there is a subgroup of CD with a UC-like presentation. The genetic factors play a significant role in IBD. IBD is associated with a strong familial pattern. Recent studies support the hypothesis that IBD patients have a dysregulated immune response to endogenous bacteria in the gastrointestinal tract. The serologic responses seen in Crohn's disease include antibodies to Saccharomyces cerevisiae, mycobacteria, bacteroides and E. coli. The pANCA antibody seen in UC and CD has been demonstrated to react with epitopes of H1 histone, Bacteroides caccae (Ton-B linked outer membrane protein), Pseudomonas fluorescens-associated bacterial protein I-2, mycobacterial histone 1 homologue called Hup B. In recent years, several serologic markers have been found to be useful for the diagnosis and differentiation of CD and UC. These markers include the following antibodies: (a) pANCA, (b) ASCA, (c) anti-pancreatic antibody, (d) OmpC antibody and (e) I-2 antibody and antibodies to anaerobic coccoid rods. The application of a panel of markers with the use of an algorithm (i.e. IBD First Step) can identify specific subtypes of IBD that have different clinical courses and progression of the diseases. The serologic markers are useful for the diagnosis and management of CD and UC patients.

Serological markers in inflammatory bowel diseases

This chapter is an overview of the literature on serological markers of inflammatory bowel diseases (IBD), focusing on anti-neutrophil cytoplasm autoantibodies (ANCA) and anti- Saccharomyces cerevisiae mannan antibodies (ASCA). The methodology for ANCA and ASCA testing is first introduced. The value of these markers as diagnostic tools is then discussed. Other chapters are devoted to the potential role of ANCA and ASCA in disease monitoring, disease stratification and as subclinical markers in families. Finally reviewed are other antibodies recently tested in clinical trials such as pancreatic antibodies and antibodies directed against bacterial antigens. The role of these antibodies in the pathophysiology of IBD still needs to be assessed. We also need to identify the ASCA immunogen(s) eliciting the antibody response.

Antibodies against hepatoma-derived growth factor and mucosal repair in ulcerative colitis

Ulcerative colitis is a chronic inflammatory disease of colonic mucosa in which the pathogenesis of any immunological disorders would likely be related. Various circulating autoantibodies have been reported in patients with ulcerative colitis, although their possible roles in this disease process have not yet been clarified. Autoantibody against hepatoma-derived growth factor (HDGF) was detected at high frequency in the serum of patients with ulcerative colitis, especially in patients with total colitis and left-sided colitis. In pursuit of the possible role of anti-HDGF autoantibody in the pathogenesis, we investigated HDGF expression in the intestinal mucosa by Western blotting and immunohistochemistry and the effects of recombinant proteins and antirecombinant HDGF antibody on the proliferation of the colonic epithelial cell-derived cell line, HT-29. HDGF was expressed in the nucleus of the colonic epithelial cells dominantly in the bottom of the crypts. Recombinant HDGF stimulated the proliferation of HT-29 cells significantly, although its effects were small, about 20% greater than the control at 100 ng/ml. On the other hand, the polyclonal IgG antibody against recombinant HDGF generated by rabbits suppressed their proliferation almost completely at 250 microg/ml. These findings suggest that HDGF plays an important role in epithelial cell renewal of intestinal crypts as a growth and survival factor, and that autoantibody against HDGF may delay mucosal healing and repair by inhibiting the stimulatory effects of HDGF on epithelial cell proliferation, resulting in a chronic process of colonic mucosal injury.

Diagnostic methodologies: serology, endoscopy, and radiology

The two major inflammatory bowel diseases, Crohn's disease (CD) and ulcerative colitis (UC), represent clinicopathologic entities that traditionally have been diagnosed on the basis of a combination of clinical, radiologic, endoscopic, and histologic features. Serum perinuclear antineutrophil cytoplasmic antibodies (pANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA) have recently been added to our diagnostic armamentarium. Several studies have demonstrated that UC-associated pANCAs recognize nuclear antigens. Additional studies have demonstrated that the pANCA human monoclonal antibody (mAb) Fab 5-3 reacts with histone H1 and with bacterial and mycobacterial antigens. Several reports have suggested that, in CD, pANCA and ASCA are correlated with colonic and small bowel disease respectively. One study found that higher ASCA levels were correlated with more aggressive CD. Serology may prove to be useful in predicting the evolution of indeterminate colitis. Magnetic resonance imaging (MRI) and leukocyte scintigraphy hold promise in identifying inflammatory CD. MRI enteroclysis is useful in identifying both luminal small bowel disease and extraluminal complications. A recent study of surveillance colonoscopy in extensive Crohn's colitis showed a high risk of dysplasia and cancer.

Screening of a HUVEC cDNA library with transplant-associated coronary artery disease sera identifies RPL7 as a candidate autoantigen associated with this disease

A HUVEC cDNA library was screened with sera from two patients who had developed transplant-associated coronary artery disease (TxCAD) following cardiac transplantation. A total of six positive clones were isolated from a primary screen of 40 000 genes. Subsequent DNA sequence analysis identified these to be lysyl tRNA synthetase, ribosomal protein L7, ribosomal protein L9, beta transducin and TANK. Another gene whose product could not be identified showed homology to a human cDNA clone (DKFZp566M063) derived from fetal kidney. Full-length constructs of selected genes were expressed as his-tag recombinant fusion proteins and used to screen a wider patient base by ELISA to determine prevalence and association with TxCAD. Of these ribosomal protein L7 showed the highest prevalence (55.6%) with TxCAD sera compared to 10% non-CAD.

Detection of anti-neutrophil cytoplasmic antibodies in MRL/Mp-lpr/lpr mice and analysis of their target antigens

Anti-neutrophil cytoplasmic antibodies (ANCA) have been widely studied and recognized to be clinically very important for some human diseases including systemic rheumatic diseases. We analyzed ANCA response and their target antigens in MRL/Mp-lpr/lpr (MRL-lpr) mice, an animal model of systemic rheumatic disease. P-ANCA was detected in 57% of the mice. Antibodies to the known P-ANCA target antigens at the same age were examined. Among these, antibodies to high mobility group (HMG) proteins HMG1 and HMG2 were detected in 57% of the mice, 75% of which were also positive for P-ANCA. These anti-HMG1/HMG2 activities were absorbed by preincubation with a mixture of HMG1 and HMG2. In contrast, antibodies to myeloperoxidase and cathepsin G were detected in 14% and 7%, respectively, but these activities were not inhibited by preincubation with corresponding antigens. In addition, the titers of P-ANCA and anti-HMG1/HMG2 antibodies in MRL-lpr mice were significantly correlated with each other. Thus, HMG1 and HMG2 were considered to be significant target antigens of P-ANCA in MRL-lpr mice.

Autoimmune hepatitis

Autoimmune hepatitis (AIH) is a rare disease, characterized by female predominance, hypergammaglobulinemia, autoantibodies, association with HLA DR3 and HLA DR4 and a good response to immunosuppression. Different subtypes of AIH may be distinguished, based on differences in the autoantibody patterns. AIH type 1 is characterized by anti-nuclear (ANA) and/or anti-smooth muscular (SMA) autoantibodies. AIH type 2 is characterized by liver/kidney microsomal autoantibodies (LKM). AIH type 3 may be distinguished by autoantibodies to soluble liver proteins (SLA) or the liver pancreas antigen (LP). AIH-2 affects predominantly pediatric patients and is characterized by a more severe clinical course, a higher frequency of relapse under immunosuppressive treatment and a more frequent progression to cirrhosis. In contrast, AIH types 1 and 3 show a higher age of onset and a better long-term response to immunosuppressive treatment. At present, the treatment of choice is prednisone alone or a combination with prednisone and azathioprine. Both treatment protocols show high survival rates. However, a rate of 13% of treatment failures and the failure to induce permanent remission in most patients underlines the urgent need to develop additional treatment regimens. A yet unknown genetic predisposition is believed to act as the underlying etiological factor in AIH. This genetic predisposition includes a few known risk factors such as the presence of HLA DR3 or HLA DR4, deletions of C4A alleles and female gender. Furthermore, it has to be postulated that defects in immunoregulatory genes exist. A model for such defects may be the autoimmune polyglandular syndrome type 1 (APS1), which results from the defects in a single gene, the autoimmune regulator type 1 (AIRE-1). Patients with APS1 suffer from mucocutaneous candidiasis and a number of organ-specific autoimmune diseases. Characteristic is a high variability in the number and character of the disease components in APS1, indicating that other genetic and environmental factors may strongly modulate the outcome of disease. Environmental factors may comprise chemical influences, such as nutritional compounds and drugs, or virus infections. Several drugs or chemicals were shown to induce hepatitis with autoimmune involvement, e.g. tienilic acid, dihydralazine and halothane. Adduct formation of an activated metabolite is believed to act as a trigger and to induce a specific immune response. Similarly, viruses were repeatedly shown to trigger autoimmune hepatitis. In virus infections, sequence similarities between viral and self-proteins may trigger autoimmune processes and the simultaneous presence of inflammatory cytokines during virus infection may further increase the risk of developing self-perpetuating autoimmune reactions which overshoot.

Colonic bacteria express an ulcerative colitis pANCA-related protein epitope

Bacteria are a suspected pathogenic factor in inflammatory bowel disease, but the identity of the relevant microbial species remains unresolved. The pANCA autoantibody is associated with most cases of ulcerative colitis (UC) and hence reflects an immune response associated with the disease process. This study addresses the hypothesis that pANCA identifies an antigen(s) expressed by bacteria resident in the human colonic mucosa. Libraries of colonic bacteria were generated using aerobic and anaerobic microbiologic culture conditions, and bacterial pools and clonal isolates were evaluated for cross-reactive antigens by immunoblot analysis using the pANCA monoclonal antibody Fab 5-3. Two major species of proteins immunoreactive to pANCA monoclonal antibodies were detected in bacteria from the anaerobic libraries. Colony isolates of the expressing bacteria were identified as Bacteroides caccae and Escherichia coli. Isolation and partial sequencing of the B. caccae antigen identified a 100-kDa protein without database homologous sequences. The E. coli protein was biochemically and genetically identified as the outer membrane porin OmpC. Enzyme-linked immunosorbent assay with human sera demonstrated elevated immunoglobulin G anti-OmpC in UC patients compared to healthy controls. These findings demonstrate that a pANCA monoclonal antibody detects a recurrent protein epitope expressed by colonic bacteria and implicates colonic bacterial proteins as a target of the disease-associated immune response.

Identification of histone H1 as a cognate antigen of the ulcerative colitis-associated marker antibody pANCA

Perinuclear anti-neutrophil cytoplasmic antibody (pANCA)(4)is a predominant serum marker of ulcerative colitis (UC), and a familial trait associated with disease susceptibility and disease associated MHC haplotypes. This study characterizes the pANCA antigen defined by representative UC-pANCA human monoclonal antibodies, Fab 5-3 and 5-2. Western blot analysis probed with Fab 5-3 revealed specific binding to a nuclear protein doublet (apparent MW=32-33 kDa) expressed in several cell types. Purification and tryptic peptide sequencing identified the protein as histone H1, and this specificity was confirmed by Fab 5-3 binding to purified H1. Rabbit anti-histone H1 immunostaining and Western blot analysis confirmed that the pANCA epitope is preferentially immunoaccessible in polymorphonuclear neutrophils (PMN). The epitope was localized to the COOH-terminal region by site-specific proteolysis, and recombinant deletants further localized binding activity for both Fab 5-2 and 5-3 to two non-overlapping segments (AA 69-171 and 172-226) associated with a recurring PKKAK motif. Serum IgG binding was detectable to these segments, but was not significantly correlated with pANCA titer or disease status. These findings indicate that histone H1 bears a recurring COOH-terminal epitope recognized by monoclonal ulcerative colitis-associated pANCA marker antibodies, but this epitope is not a predominant specificity of serum pANCA.

Established and emerging biological activity markers of inflammatory bowel disease

Assessment of disease activity in inflammatory bowel disease (IBD), i.e., ulcerative colitis (UC) and Crohn's disease (CD), is done using clinical parameters and various biological disease markers. Ideally, a disease marker must: be able to identify individuals at risk of a given disorder, be disease specific, mirror the disease activity and, finally, be easily applicable for routine clinical purposes. However, no such disease markers have yet been identified for IBD. In this article, classical disease markers including erythrocyte sedimentation rate, acute phase proteins (especially orosomucoid and CRP), leukocyte and platelet counts, albumin, neopterin, and beta2-microglobulin will be reviewed together with emerging disease markers such as antibodies of the ANCA/ASCA type, cytokines (e.g., IL-1, IL-2Ralpha, IL-6, IL-8, TNF-alpha, and TNF-alpha receptors) and with various adhesion molecules. It is concluded that none of the pertinent laboratory surrogate markers of disease activity in IBD are specific or sensitive enough to replace basic clinical observation such as the number of daily bowel movements, general well-being, and other parameters in parallel. Further studies are highly warranted to identify and assess the clinical importance and applicability of new laboratory markers for the diagnosis or the disease activity of IBD.

High mobility group (HMG) non-histone chromosomal proteins HMG1 and HMG2 are significant target antigens of perinuclear anti-neutrophil cytoplasmic antibodies in autoimmune hepatitis

BACKGROUND

High mobility group (HMG) non-histone chromosomal proteins HMG1 and HMG2 have been identified as novel antigens of perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCAs), and the existence of anti-HMG1 and anti-HMG2 antibodies in a population of patients with ulcerative colitis has been reported.

AIMS

To investigate whether HMG1 and HMG2 are target antigens for p-ANCAs in autoimmune hepatitis (AIH).

PATIENTS

Serum samples from 28 patients with AIH, 44 patients with primary biliary cirrhosis (PBC), 27 patients with chronic hepatitis C, and 23 patients with chronic hepatitis B were tested.

METHODS

ANCAs were detected by routine indirect immunofluorescence (IIF). Anti-HMG1 and anti-HMG2 antibodies were assayed by enzyme linked immunosorbent assay.

RESULTS

p-ANCAs were detected in 89% (25/28) of patients with AIH, 36% (16/44) of patients with PBC, 11% (3/27) of patients with chronic hepatitis C, and 13% (3/23) of patients with chronic hepatitis B. Anti-HMG1 and/or anti-HMG2 antibodies were detected in 89% (25/28) of patients with AIH, 70% (31/44) with PBC, 26% (7/27) with chronic hepatitis C, and 9% (2/23) with chronic hepatitis B. In AIH, anti-HMG1 and/or anti-HMG2 antibodies were detected in 96% (24/25) of p-ANCA positive patients. The p-ANCA staining pattern detected by IIF using sera from patients with AIH disappeared or decreased in titre after preincubation with a mixture of HMG1/HMG2. The presence and titres of those antibodies in AIH correlated significantly with those of p-ANCA, but not with those of anti-nuclear antibody or anti-smooth muscle antibody.

CONCLUSIONS

HMG1 and HMG2 are significant target antigens of p-ANCA in AIH.

Are anti-neutrophil cytoplasmic antibodies (ANCA) clinically useful in inflammatory bowel disease (IBD)?

Since the first detection of ANCA in IBD, numerous studies have dealt with their prevalence, antigenic specificities, clinical significance, pathophysiological role, and their induction. This review summarizes the information obtained from those studies and shows that ANCA are not directly useful as diagnostic and prognostic factors in IBD. ANCA were detected in 50-85% of patients with ulcerative colitis (UC) and 10-20% of patients with Crohn's disease (CD). Multiple target antigens are recognized by these autoantibodies, including both cytoplasmic and nuclear proteins. A pathophysiological role for ANCA in IBD is far from clear. On the one hand, it is suggested that ANCA are genetic markers of susceptibility for IBD, and on the other hand, the induction of ANCA in those diseases may just be an epiphenomenon of chronic inflammation. We discuss recent evidence that ANCA may be induced by a break-through of tolerance towards bacterial antigens.

Antineutrophil cytoplasmic antibodies in Japanese patients with inflammatory bowel disease: prevalence and recognition of putative antigens

OBJECTIVE

Our aim was to investigate the prevalence of antineutrophil cytoplasmic antibodies (ANCA) in Japanese patients with ulcerative colitis (UC) and Crohn's disease (CD), and the putative antigens recognized by perinuclear staining pattern ANCA (p-ANCA)-positive sera.

METHODS

Sera from UC (n = 52) and CD (n = 43) patients, and from healthy controls (n = 74) were studied. The indirect immunofluorescence (IIF) method was used for the detection of ANCA and its binding pattern. p-ANCA-positive sera were studied further for putative antigens. ELISAs using lactoferrin (Lf), myeloperoxidase (MPO), and cathepsin G (Cat G) as antigens were performed.

RESULTS

ANCA was positive in 40 of the 52 (76.9%) UC (p-ANCA in 33) and in 32 of the 43 (74.4%) CD (p-ANCA in 31) patients. UC and CD patients showed significantly higher titers of p-ANCA than controls; however, no significant difference was observed between UC and CD. In UC, 23, 17, and nine of the 33 patients with p-ANCA-positive sera showed reactivity with Lf, MPO, and Cat-G, respectively. In CD, 21, 20, and 11 of the 31 patients with p-ANCA-positive sera showed reactivity with Lf, MPO, and Cat-G, respectively. Fourteen of the UC and six of the CD patients showed reactivity with two different antigens, and seven of the UC and 11 of the CD patients showed reactivity with all three antigens. The presence of anti-Lf and anti-MPO antibodies was further confirmed by Western blotting.

CONCLUSIONS

ANCA is useful in distinguishing patients with IBD from normal subjects but is not sufficient for the differential diagnosis of CD and UC. p-ANCA reactivity might be derived from the recognition of heterogeneous neutrophil-associated antigens.