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

The role of anti-HMGB1 antibody and anti-moesin antibody in ANCA-associated vasculitis

OBJECTIVE

The study aims to evaluate the role of anti-high mobility group box 1 (HMGB1) antibody and anti-moesin antibody in the diagnosis of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and its possible relationship with the different clinical manifestations.

METHODS

The study involved 60 AAV patients, 58 patients with autoimmune disease other than AAV and 50 healthy subjects. The serum levels of anti-HMGB1 and anti-moesin antibodies were determined by enzyme-linked immunosorbent assay (ELISA), and the second determination was made 3 months after treatment of AAV patients.

RESULTS

Serum levels of anti-HMGB1 and anti-moesin antibodies in AAV group were significantly higher than those in non-AAV group and HC group. The area under the curve (AUC) of anti-HMGB1 and anti-moesin in diagnosing AAV were 0.977 and 0.670, respectively. Anti-HMGB1 levels were significantly elevated in AAV patients with pulmonary involvement, while the concentrations of anti-moesin were significantly increased in patients with renal damage. Anti-moesin were positively correlated with BVAS (r=0.261, P=0.044), creatinine (r=0.296, P=0.024) and negatively correlated with complement C3 (r=-0.363, P=0.013). Besides, anti-moesin levels of active AAV patients were significantly higher than those in inactive patients. The concentrations of serum anti-HMGB1 could be significantly decreased after induction remission treatment (P<0.05).

CONCLUSION

Anti-HMGB1 and anti-moesin antibodies play important roles in the diagnosis and prognosis of AAV, which may act as potential disease markers for AAV.

Pathogenesis of anti-neutrophil cytoplasmic antibody-associated vasculitis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) encompasses a group of potentially life-threatening disorders characterized by necrotizing small vessel vasculitis with positive serum ANCA. To date, the pathogenesis of AAV has not been fully elucidated, but remarkable progress has been achieved in the past few decades. In this review, we summarize the mechanism of AAV. The pathogenesis of AAV involves various factors. ANCA, neutrophils, and the complement system play key roles in disease initiation and progression, forming a feedback amplification loop leading to vasculitic injury. Neutrophils activated by ANCA undergo respiratory burst and degranulation, as well as releasing neutrophils extracellular traps (NETs), thus causing damage to vascular endothelial cells. Activated neutrophils could further activate the alternative complement pathway, leading to the generation of complement 5a (C5a), which amplifies the inflammatory response by priming neutrophils for ANCA-mediated overactivation. Neutrophils stimulated with C5a and ANCA could also activate the coagulation system, generate thrombin, and subsequently cause platelet activation. These events in turn augment complement alternative pathway activation. Moreover, disturbed B-cell and T-cell immune homeostasis is also involved in disease development. In-depth investigation in pathogenesis of AAV might help to offer more effective targeted therapies.

Metabolomics combined with clinical analysis explores metabolic changes and potential serum metabolite biomarkers of antineutrophil cytoplasmic antibody-associated vasculitis with renal impairment

Background

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is an autoimmune systemic disease, and the majority of AAV patients have renal involvement presenting as rapid progressive glomerulonephritis (GN). Currently, the clinically available AAV markers are limited, and some of the newly reported markers are still in the nascent stage. The particular mechanism of the level changes of various markers and their association with the pathogenesis of AAV are not well defined. With the help of metabolomics analysis, this study aims to explore metabolic changes in AAV patients with renal involvement and lay the foundation for the discovery of novel biomarkers for AAV-related kidney damage.

Methods

We performed liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based on serum samples from patients with AAV (N = 33) and healthy controls (N = 33) in order to characterize the serum metabolic profiling. The principal component analysis (PCA) and orthogonal partial least-squares-discriminant analysis (OPLS-DA) were used to identify the differential metabolites. Least Absolute Shrinkage and Selection Operator (LASSO) and eXtreme Gradient Boosting (XGBoost) analysis were further conducted to identify the potential diagnostic biomarker. A receiver operating characteristic (ROC) curve analysis was conducted to evaluate the diagnostic performance of the identified potential biomarker.

Results

A total of 455 metabolites were detected by LC-MS analysis. PCA and OPLS-DA demonstrated a significant difference between AAV patients with renal involvement and healthy controls, and 135 differentially expressed metabolites were selected, with 121 upregulated and 14 downregulated. Ninety-two metabolic pathways were annotated and enriched based on the KEGG database. N-acetyl-L-leucine, Acetyl-DL-Valine, 5-hydroxyindole-3-acetic acid, and the combination of 1-methylhistidine and Asp-phe could accurately distinguish AAV patients with renal involvement from healthy controls. And 1-methylhistidine was found to be significantly associated with the progression and prognosis of AAV with renal impairment. Amino acid metabolism exhibits significant alternations in AAV with renal involvement.

Conclusion

This study identified metabolomic differences between AAV patients with renal involvement and non-AAV individuals. Metabolites that could accurately distinguish patients with AAV renal impairment from healthy controls in this study, and metabolites that were significantly associated with disease progression and prognosis were screened out. Overall, this study provides information on changes in metabolites and metabolic pathways for future studies of AAV-related kidney damage and lays a foundation for the exploration of new biomarkers of AAV-related kidney damage.

Increased levels of immature and activated low density granulocytes and altered degradation of neutrophil extracellular traps in granulomatosis with polyangiitis

Granulomatosis with Polyangiitis (GPA) is a small vessel vasculitis typically associated with release of neutrophil extracellular traps (NETs) by activated neutrophils. In this study, we further aimed to investigate the contributions of neutrophils and NETs to the complex disease pathogenesis. We characterized the phenotype of neutrophils and their capacity to induce NETs. In addition, the level of circulating NETs, determined by neutrophil elastase/DNA complexes, and the capacity of patient sera to degrade NETs were investigated from blood samples of 12 GPA patients, 21 patients with systemic lupus erythematosus (SLE) and 21 healthy donors (HD). We found that GPA patients had significantly increased levels of low-density granulocytes (LDGs) compared to HD, which displayed an activated and more immature phenotype. While the propensity of normal-density granulocytes to release NETs and the levels of circulating NETs were not significantly different from HD, patient sera from GPA patients degraded NETs less effectively, which weakly correlated with markers of disease activity. In conclusion, increased levels of immature and activated LDGs and altered degradation of circulating NETs may contribute to pathogenesis of GPA, potentially by providing a source of autoantigens that trigger or further enhance autoimmune responses.

Old known and possible new biomarkers of ANCA-associated vasculitis

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) comprises a group of multisystem disorders involving severe, systemic, small-vessel vasculitis with short- and long term serious and life-threating complications. Despite the simplification of treatment, fundamental aspects concerning assessment of its efficacy and its adaptation to encountered complications or to the relapsing/remitting/subclinical disease course remain still unknown. The pathogenesis of AAV is complex and unique, and despite the progress achieved in the last years, much has not to be learnt. Foremost, there is still no accurate marker enabling us to monitoring disease and guide therapy. Therefore, the disease management relays often on clinical judgment and follows a" trial and error approach". In the recent years, an increasing number of new molecules s have been explored and used for this purpose including genomics, B- and T-cell subpopulations, complement system factors, cytokines, metabolomics, biospectroscopy and components of our microbiome. The aim of this review is to discuss both the role of known historical and clinically established biomarkers of AAV, as well as to highlight potential new ones, which could be used for timely diagnosis and monitoring of this devastating disease, with the goal to improve the effectiveness and ameliorate the complications of its demanding therapy.

Alarmins in autoimmune diseases

Alarmins are endogenous, constitutively expressed, chemotacting and immune activating proteins or peptides released because of non-programmed cell death (i.e. infections, trauma, etc). They are considered endogenous damage-associated molecular patterns (DAMPs), able to induce a sterile inflammation. In the last years, several studies highlighted a possible role of different alarmins in the pathogenesis of various autoimmune and immune-mediated diseases. We reviewed the relevant literature about this topic, for about 160 articles. Particularly, we focused on systemic autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, idiopathic inflammatory myopathies, ANCA-associated vasculitides, Behçet's disease) and cutaneous organ-specific autoimmune diseases (vitiligo, psoriasis, alopecia, pemphigo). Finally, we discussed about future perspectives and potential therapeutic implications of alarmins in autoimmune diseases. In fact, identification of receptors and downstream signal transducers of alarmins may lead to the identification of antagonistic inhibitors and agonists, with the capacity to modulate alarmins-related pathways and potential therapeutic applicability.

The Role of HMGB1 in Rheumatic Diseases

HMGB1, a highly conserved non-histone nuclear protein, is widely expressed in mammalian cells. HMGB1 in the nucleus binds to the deoxyribonucleic acid (DNA) to regulate the structure of chromosomes and maintain the transcription, replication, DNA repair, and nucleosome assembly. HMGB1 is actively or passively released into the extracellular region during cells activation or necrosis. Extracellular HMGB1 as an alarmin can initiate immune response alone or combined with other substances such as nucleic acid to participate in multiple biological processes. It has been reported that HMGB1 is involved in various inflammatory responses and autoimmunity. This review article summarizes the physiological function of HMGB1, the post-translational modification of HMGB1, its interaction with different receptors, and its recent advances in rheumatic diseases and strategies for targeted therapy.

Dynamics of HMBG1 (High Mobility Group Box 1) during radiochemotherapy correlate with outcome of HNSCC patients

Purpose

High Mobility Group Box 1 (HMGB1) protein has been described as a consensus marker for immunogenic cell death (ICD) in cancer. To personalize treatments, there is a need for biomarkers to adapt dose prescription, concomitant chemotherapy, and follow-up in radiation oncology. Thus, we investigated the levels of HMGB1 in plasma of patients with head and neck squamous cell carcinoma (HNSCC) during the course of radiochemotherapy and follow-up in correlation with oncologic outcome and clinical confounders.

Methods

In our pilot study, 11 patients with advanced HNSCC were treated with definitive radiochemotherapy. Blood samples were taken weekly during treatment and frequently at follow-up visits. HMGB1 levels as well as routine laboratory values were measured and clinical information was collected including tumor volume, infections, toxicity, and follow-up data.

Results

In total, 85 samples were analyzed. In eight patients, HMGB1 levels (baseline vs. last available sample during treatment) were increasing and in three patients HMGB1 values were decreasing toward the end of treatment. All three patients with decreasing values developed tumor recurrence. By contrast, no relapse occurred in patients that showed increasing HMGB1 levels during therapy. Moreover, a positive correlation of HMGB1 levels with tumor volumes, C‑reactive protein (CRP) levels, infections, and grade three toxicity (RTOG) was observed.

Conclusion

HMGB1 might be a promising marker to monitor ICD in HNSCC during the course of radiochemotherapy. However, HMGB1 seems to reflect complex and diverse immunogenic responses and potential confounders. Infections and treatment-associated toxicity should be considered when interpreting the dynamics of HMGB1.

Association Between Serum Alarmin Levels and Disease-specific Indices in Patients With Anti-neutrophil Cytoplasmic Antibody-associated Vasculitis

BACKGROUND/AIM

We evaluated the relationship between serum alarmin levels and disease-specific indices in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV).

PATIENTS AND METHODS

Sera and data from 79 patients were utilized. For AAV-specific indices, Birmingham vasculitis activity score (BVAS), five-factor score (FFS), and vasculitis damage index (VDI) were collected and serum levels of four alarmins (hepatoma-derived growth factor, high mobility group box protein 1, S100A9, and S100A12) were measured using enzyme-linked immunosorbent assay. Associations between alarmin levels, AAV-specific indices, and inflammatory laboratory markers were assessed.

RESULTS

S100A9 levels were significantly correlated with C-reactive protein levels (r=0.316, p=0.005) and S100A12 levels correlated with VDI (r=0.232, p=0.040), which was consistent in a subgroup of patients with myeloperoxidase (perinuclear)-ANCA positivity. No other associations were found between alarmin levels and BVAS, FFS, and VDI.

CONCLUSION

The serum S100A12 level was associated with organ damage in AAV, especially in myeloperoxidase (perinuclear)-ANCA-positive patients.

HMGB1 in kidney diseases

High mobility group box 1 (HMGB1) is a highly conserved nucleoprotein involving in numerous biological processes, and well known to trigger immune responses as the damage-associated molecular pattern (DAMP) in the extracellular environment. The role of HMGB1 is distinct due to its multiple functions in different subcellular location. In the nucleus, HMGB1 acts as a chaperone to regulate DNA events including DNA replication, repair and nucleosome stability. While in the cytoplasm, it is engaged in regulating autophagy and apoptosis. A great deal of research has explored its function in the pathogenesis of renal diseases. This review mainly focuses on the role of HMGB1 and summarizes the pathway and treatment targeting HMGB1 in the various renal diseases which may open the windows of opportunities for the development of desirable therapeutic ends in these pathological conditions.

Microparticles expressing myeloperoxidase as potential biomarkers in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV)

Abstract

To investigate presence of circulating myeloperoxidase-positive microparticles (MPO⁺MPs) in relation to disease activity in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Forty-six patients with AAV and 23 age- and sex-matched healthy controls were included. Vasculitis disease activity was assessed using the Birmingham Vasculitis Activity Score (BVAS). MPs were analyzed in citrate plasma by flow cytometry and phenotyped based on MPO expression and co-expression of pentraxin-3 (PTX3), high mobility group box 1 protein (HMGB1), and tumor necrosis factor-like weak inducer of apoptosis (TWEAK). Serum levels of PTX3, sTWEAK, and HMGB1 were also determined. Twenty-three patients had active vasculitis (BVAS ≥ 1). Concentrations of MPO⁺MPs expressing PTX3, HMGB1, and TWEAK were significantly higher in patients compared to healthy controls (p < 0.001, p < 0.01, p < 0.001, respectively), while concentrations of PTX3⁺ and HMGB1⁺MPO⁺MPs were significantly higher in active AAV compared to patients in remission. MPO⁺MPs expressing either PTX3 or HMGB1 were associated with BVAS (r = 0.5, p < 0.001; r = 0.3, p = 0.04, respectively). Significantly higher serum PTX3 levels were found in active- than in inactive AAV (p < 0.001), correlating strongly with BVAS (r = 0.7, p < 0.001). Serum levels of sTWEAK and HMGB1 did not differ between patients and controls. Concentration of MPO⁺MPs is increased in plasma from AAV patients compared to healthy individuals. PTX3 in serum as well as PTX3 and HMGB1 expressed on MPO⁺MPs were associated with disease activity in the investigated patients.

Key messages

Myeloperoxidase-positive microparticles (MPO⁺MPs) are increased in plasma from patients with ANCA-associated vasculitis.

Concentrations of MPO⁺MPs expressing PTX3, HMGB1, and TWEAK were significantly higher in patients compared to healthy controls.

MPO⁺MPs expressing PTX3 and HMGB1 are associated with disease activity in ANCA-associated vasculitis.

Electronic supplementary material

The online version of this article (10.1007/s00109-020-01955-2) contains supplementary material, which is available to authorized users.

Unraveling the Role of Receptor for Advanced Glycation End Products (RAGE) and Its Ligands in Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune T cell-dependent B cell-mediated disorder of the neuromuscular junction (NMJ) characterized by fluctuating skeletal muscle weakness, most commonly attributed to pathogenic autoantibodies against postsynaptic nicotinic acetylcholine receptors (AChRs). Although MG pathogenesis is well-documented, there are no objective biomarkers that could effectively correlate with disease severity or MG clinical subtypes, and current treatment approaches are often ineffective. The receptor for advanced glycation end products (RAGE) is a multiligand cell-bound receptor highly implicated in proinflammatory responses and autoimmunity. Preclinical evidence demonstrates that RAGE and its ligand S100B are upregulated in rat models of experimental autoimmune myasthenia gravis (EAMG). S100B-mediated RAGE activation has been shown to exacerbate EAMG, by enhancing T cell proinflammatory responses, aggravating T helper (Th) subset imbalance, increasing AChR-specific T cell proliferative capacity, and promoting the production of antibodies against AChRs from the spleen. Soluble sRAGE and esRAGE, acting as decoys of RAGE ligands, are found to be significantly reduced in MG patients. Moreover, MG has been associated with increased serum levels of S100A12, S100B and HMGB1. Several studies have shown that the presence of thymic abnormalities, the onset age of MG, and the duration of the disease may affect the levels of these proteins in MG patients. Herein, we discuss the emerging role of RAGE and its ligands in MG immunopathogenesis, their clinical significance as promising biomarkers, as well as the potential therapeutic implications of targeting RAGE signaling in MG treatment.

Effect of high mobility group box 1 on Toll-like receptor 9 in B cells in myeloperoxidase-ANCA-associated vasculitis

High mobility group box 1 (HMGB1) played pathogenic role in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Recent findings demonstrated that Toll-like receptor 9 (TLR9) was involved in B cell tolerance breaking of autoimmune disease, including AAV. Here, we investigated the effect of HMGB1 on TLR9 in B cells of AAV. In the present work, patients with myeloperoxidase (MPO)-AAV in active stage were recruited. Intracellular TLR9 expression in various B cell subpopulations of the whole blood was detected by flow cytometry and the correlation with clinical data was analysed. Our results showed that intracellular TLR9 expression in B cells, memory B cells and plasmablasts correlated with erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP). In particular, TLR9 expression in plasma cells correlated with ESR, CRP, serum creatinine, eGFR, and Birmingham Vasculitis Activity Score. To further explore the effect of HMGB1 on B cell, peripheral blood mononuclear cells (PBMCs) from AAV patients were isolated. After stimulated with HMGB1, TLR9 expression in various B cell subpopulations and proliferation ratio of live B cells were analysed by flow cytometry. We found that TLR9 expression in plasma cells and the proliferation ratio of live B cells by HMGB1 stimulation were significantly upregulated compared with the control group. Therefore, TLR9 expression in plasma cells was associated with disease activity of MPO-AAV. HMGB1 could enhance TLR9 expression in plasma cells and B cell proliferation. These indicated a role of HMGB1 on TLR9 in B cells in MPO-AAV, which would provide potential clues for intervention strategies.

Association of serum high mobility group box 1 levels with disease activity and renal involvement in patients with systemic vasculitis

High mobility group box 1 (HMGB1) is a kind of proinflammatory mediator that acts as an alarmin when released by dying, injured or activated cells. Previous studies have reported that HMGB1 are closely linked to antineutrophil cytoplasmic antibody-associated vasculitis (AAV). The present study aimed to evaluate whether serum HMGB1 levels were associated with systemic vasculitis (VAs).The study population consisted of 51 patients with VAs, 46 patients with essential hypertension (EH) and 46 healthy controls (HC). Thirty-five patients with VAs had in active stage and 16 patients with VAs in an inactive stage. Furthermore, 31 patients with VAs had renal involvement, the other 20 patients were selected for without renal involvement. Serum HMGB1 levels were measured by enzyme-linked immunosorbent assay. Associations between serum HMGB1 levels with clinical and laboratory parameters were analyzed.Serum HMGB1 levels in patients with VAs were significantly higher than in EH and HC (all P < .05), and no difference regarding serum HMGB1 levels could be found between EH and HC (P = .208). Serum HMGB1 levels in VAs patients with active stage were significantly higher than those in HC and VAs patients with inactive stage (all P < .05). Patients with renal involvement and non-renal involvement had increased HMGB1 levels compared with HC (all P < .05). In addition, serum HMGB1 levels were significantly higher in patients with renal involvement compared with non-renal involvement patients (P = .001). Correlation analysis showed that serum HMGB1 levels were positive significant correlated with the Birmingham Vasculitis Activity Score, hypersensitive C reactive protein (Hs-CRP), serum creatinine (Scr) and 24-hour proteinuria (all P < .05). Among the subsets of VAs, serum HMGB1 levels were significantly higher in AAV, polyarteritis nodosa (PAN) and takayasu arteritis (TA) than in HC (all P < .05). More interestingly, serum HMGB1 were significantly higher in patients with PAN compared with AAV and TA patients (all P < .05). Furthermore, there was positive correlation between serum HMGB1 levels and Hs-CRP, Scr, and 24-hour proteinuria in patients with PAN (all P < .05).Serum HMGB1 levels are increased in patients with VAs compared with HC and EH and can reflect the disease activity and renal involvement.

Endothelial activation and injury by microparticles in patients with systemic lupus erythematosus and rheumatoid arthritis

BACKGROUND

Endothelial activation and damage is commonly observed in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) and is related to development of atherosclerosis and cardiovascular diseases. Different components of the immune system seem to participate in the endothelial injury, such as generation of autoantibodies and formation of immune complexes (ICs). Microparticles (MPs) and their immune complexes (MPs-ICs) are increased in the circulation of patients with SLE and RA; therefore, we propose these extracellular vesicles could interact and modulate the function of endothelial cells. Hence, the effect of MPs and MPs-ICs from patients with SLE and RA in endothelial cells was evaluated.

METHODS

Macrovascular and microvascular endothelial cells were exposed to MPs and MPs-ICs from healthy donors and patients with SLE and RA. Vesicles uptake/binding, expression of adhesion molecules, cytokine and chemokine production, monocyte adherence, and alterations of endothelial monolayer were evaluated by flow cytometry and fluorescence microscopy.

RESULTS

Endothelial cells internalized MPs and MPs-ICs and increased CD54 and CD102 expression and CCL2, CCL5, and IL-6 production after the treatment with these extracellular vesicles, which led to an increase in the adherence of classic monocytes. These vesicles also induced low expression of VE-cadherin in membrane, depolymerization of actin filaments, and formation of intercellular spaces, which led to endothelial death and increased permeability after MPs and MPs-ICs exposure.

CONCLUSIONS

MPs and MPs-ICs from patients with SLE and RA increase adhesion molecules expression, chemokine production, and structural alterations in macrovascular and microvascular endothelial cells. Therefore, high counts of these vesicles in patients would promote endothelial alterations and secondary tissue leukocyte infiltration.

Association of serum/plasma high mobility group box 1 with autoimmune diseases: A systematic review and meta-analysis

BACKGROUND

High mobility group box 1 (HMGB1) is a kind of proinflammatory mediator to stimulate the innate and adaptive immune system and participates in a number of acute and chronic inflammatory processes after sterile injury or microbial invasion. HMGB1 has been suggested to be involved in the pathogenesis of many autoimmune diseases. However, the results are contradictory or inconclusive among these findings. The aim of this study was to investigate whether serum/plasma HMGB1 levels are associated with autoimmune diseases by comparing the serum/plasma HMGB1 levels in patients with autoimmune disease and healthy controls and to further evaluate whether serum/plasma HMGB1 levels are associated with disease state.

METHODS

PubMed, Medline, and Web of science databases (up to October 1, 2017) were used to obtain all relative published literature. Study quality was assessed by the Newcastle-Ottawa scale (NOS). Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by fixed-effects or random-effect model analysis.

RESULTS

A total of 23 original articles of autoimmune diseases were finally included in the meta-analysis. Results revealed that the serum/plasma HMGB1 levels were increased in patients with autoimmune disease, compared to healthy controls. Subgroup analysis showed that serum/plasma HMGB1 levels in patients with active disease state were significantly higher than in those with inactive state. In addition, subgroup analysis based on disease type has indicated that the serum/plasma HMGB1 levels in patients with small vessel vasculitis, systemic lupus erythematosus, rheumatoid arthritis, ankylosing spondylitis and sjogren syndrome were significantly higher, compared to healthy controls. Further subgroup analyses by region showed that plasma/serum HMGB1 levels were higher in Asian and European patients with autoimmune diseases.

CONCLUSIONS

Serum/plasma HMGB1 levels in patients with autoimmune diseases are significantly higher than in healthy controls, and may reflect the disease activity.

Comorbid Conditions are Associated With Emergency Department Visits, Hospitalizations, and Medical Charges of Patients With Systemic Lupus Erythematosus

BACKGROUND/OBJECTIVES

In addition to increase mortality, comorbidities can increase medical costs for systemic lupus erythematosus (SLE). Healthcare utilization can dramatically increase medical costs. It is essential to better understand the comorbidities that can lead to healthcare utilization, such as emergency department visit and/or hospitalization, for SLE patients. Therefore, the objective of this study was to examine the associations between comorbidities and healthcare utilization and medical charges of patients with SLE.

METHODS

Nebraska statewide emergency departments (ED) discharge and hospitals discharge data from 2007 to 2012 were used to study the comorbid conditions of patients with SLE. SLE was defined using the standard International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) diagnosis codes (710.0).

RESULTS

There were more comorbid conditions in patients with SLE than patients without SLE. Comorbid conditions were majorly related to ED visits and hospitalizations of patients with SLE. Chest pain, abdominal pain, injury, acute respiratory infections, symptoms of digestive systems, headache, myalgia and myositis, noninfectious gastroenteritis and colitis, and symptoms of skin and other integumentary systems are common comorbid conditions for ED visits. Infections, cardiovascular diseases, fractures, chronic obstructive pulmonary disease (COPD) and allied conditions, cerebrovascular diseases, and episodic mood disorder are common comorbid conditions for hospitalizations of patients with SLE. In addition, the numbers of comorbid conditions were significantly associated with the length of hospital stay and hospital charges for SLE patients.

CONCLUSION

The findings in this study indicated that comorbid conditions are associated with healthcare utilization and medical charges of patients with SLE.

High mobility group box-1 contributes to anti-myeloperoxidase antibody-induced glomerular endothelial cell injury through a moesin-dependent route

Background

Our previous study found that circulating and urinary levels of high mobility group box-1 (HMGB1) were closely associated with disease activity in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Moreover, HMGB1 participates in ANCA-induced neutrophil activation. Cross-reactivity between moesin and anti-myeloperoxidase (MPO) antibody has been reported in both human and mouse. The current study investigated whether HMGB1 participated in MPO-ANCA-induced glomerular endothelial cell (GEnC) injury, which is one of the most important aspects in the pathogenesis of AAV.

Methods

The effects of HMGB1 on expression of moesin on GEnCs and anti-MPO antibody binding to GEnCs were measured. MPO expression on GEnCs was explored. The effects of HMGB1 in MPO-ANCA induced GEnC injury were measured, during which the role of moesin was explored. Antagonists for various relevant receptors were employed.

Results

Sera from AAV patients at the active stage could mediate GEnC injury, while this effect could be attenuated by preblocking HMGB1. HMGB1 could increase the expression of moesin on GEnCs and the binding of anti-MPO antibody to moesin. The colocalization of moesin expression and anti-MPO antibody binding can be detected. Little, if any, MPO was expressed in GEnCs. HMGB1 increased GEnC activation and injury in the presence of patient-derived MPO-ANCA-positive IgGs through moesin. The effects of HMGB1 on expression of moesin on GEnCs, anti-MPO antibody binding to GEnCs, GEnC activation and injury were mainly toll like receptor 4 (TLR4) dependent.

Conclusions

HMGB1 can increase the expression of moesin but not MPO on GEnCs, and can further participate in MPO-ANCA-induced GEnC activation and injury by cross-reactivity between moesin and anti-MPO antibody.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1339-4) contains supplementary material, which is available to authorized users.

Down-Regulation of Serum High-Mobility Group Box 1 Protein in Patients with Pulmonary Tuberculosis and Nontuberculous Mycobacterial Lung Disease

Background

Recently, increased levels of high-mobility group box 1 protein (HMGB1) have been identified in various inflammatory conditions and infections. However, no studies have evaluated the HMGB1 level in nontuberculous mycobacterial (NTM) lung disease, and compared it to mycobacterial lung disease.

Methods

A total of 60 patients newly diagnosed with NTM lung disease, 44 culture-positive pulmonary tuberculosis (TB) patients, and 34 healthy controls, were included in this study. The serum HMGB1 concentrations were quantified using HMGB1 enzyme-linked immunosorbent assay kits.

Results

Serum HMGB1 level in patients with pulmonary TB or NTM lung disease, was significantly lower than that of the healthy controls. In addition, the serum HMGB1 level in TB patients was significantly lower than patients with NTM lung disease. However, the levels in NTM patient subgroups did not differ according to the causative species, disease progression, and disease phenotype.

Conclusion

Although low levels of serum HMGB1 has the potential to be a marker of mycobacterial lung disease, these levels were unable to differentiate disease progression and disease phenotype in NTM lung diseases.

Complement in ANCA-associated vasculitis: mechanisms and implications for management

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of potentially life-threatening autoimmune diseases. The main histological feature in the kidneys of patients with AAV is pauci-immune necrotizing crescentic glomerulonephritis with little immunoglobulin and complement deposition in the glomerular capillary walls. The complement system was not, therefore, initially thought to be associated with the development of AAV. Accumulating evidence from animal models and clinical observations indicate, however, that activation of the complement system - and the alternative pathway in particular - is crucial for the development of AAV, and that the complement activation product C5a has a central role. Stimulation of neutrophils with C5a and ANCA not only results in the neutrophil respiratory burst and degranulation, but also activates the coagulation system and generates thrombin, thus bridging the inflammation and coagulation systems. In this Review, we provide an overview of the clinical, in vivo and in vitro evidence for a role of complement activation in the development of AAV and discuss how targeting the complement system could provide opportunities for therapy.

HMGB1 contributes to glomerular endothelial cell injury in ANCA-associated vasculitis through enhancing endothelium-neutrophil interactions

Our previous studies demonstrated that high mobility group box‐1 (HMGB1), a typical damage‐associated molecular pattern (DAMP) protein, is associated with the disease activity of antineutrophil cytoplasmic antibody (ANCA)‐associated vasculitis (AAV). Moreover, HMGB1 participates in ANCA‐induced neutrophil activation. The current study aimed to investigate whether HMGB1 regulated the interaction between neutrophils and glomerular endothelial cells (GEnC) in the presence of ANCA. Correlation analysis on HMGB1 levels in AAV patients and soluble intercellular cell adhesion molecule‐1 (sICAM‐1) levels or vascular endothelial growth factor (VEGF) levels, which are markers of endothelial cell activation, was performed. The effect of HMGB1 on neutrophil migration towards GEnC, respiratory burst and degranulation of neutrophils in coculture conditions with GEnC was measured. The activation of neutrophils, the activation and injury of GEnC, and the consequent pathogenic role of injured GEnC were evaluated. Plasma levels of HMGB1 correlated with sICAM‐1 and VEGF (r = 0.73, P < 0.01; r = 0.41, P = 0.04) in AAV patients. HMGB1 increased neutrophil migration towards GEnC, as well as respiratory burst and degranulation of neutrophils in the presence of ANCA in the coculture system. In the presence of robust neutrophil activation, GEnC were further activated and injured in the coculture system of GEnC and neutrophils. In addition, injured GEnC could produce TF‐positive leuco‐endothelial microparticles and endothelin‐1 (ET‐1), while NF‐κB was phosphorylated (S529) in the injured GEnC. Plasma levels of HMGB1 correlated with endothelial cell activation in AAV patients. HMGB1 amplified neutrophil activation and the activation and injury of GEnC in the presence of ANCA.

Neutrophil Extracellular Traps in ANCA-Associated Vasculitis

A group of pauci-immune vasculitides, characterized by neutrophil-rich necrotizing inflammation of small vessels and the presence of antineutrophil cytoplasmic antibodies (ANCAs), is referred to as ANCA-associated vasculitis (AAV). ANCAs against proteinase 3 (PR3) (PR3-ANCA) or myeloperoxidase (MPO) (MPO-ANCA) are found in over 90% of patients with active disease, and these ANCAs are implicated in the pathogenesis of AAV. Dying neutrophils surrounding the walls of small vessels are a histological hallmark of AAV. Traditionally, it has been assumed that these neutrophils die by necrosis, but neutrophil extracellular traps (NETs) have recently been visualized at the sites of vasculitic lesions. AAV patients also possess elevated levels of NETs in the circulation. ANCAs are capable of inducing NETosis in neutrophils, and their potential to do so has been shown to be affinity dependent and to correlate with disease activity. Neutrophils from AAV patients are also more prone to release NETs spontaneously than neutrophils from healthy blood donors. NETs contain proinflammatory proteins and are thought to contribute to vessel inflammation directly by damaging endothelial cells and by activating the complement system and indirectly by acting as a link between the innate and adaptive immune system through the generation of PR3- and MPO-ANCA. Injection of NET-loaded myeloid dendritic cells into mice results in circulating PR3- and MPO-ANCA and the development of AAV-like disease. NETs have also been shown to be essential in a rodent model of drug-induced vasculitis. NETs induced by propylthiouracil could not be degraded by DNaseI, implying that disordered NETs might be important for the generation of ANCAs. NET degradation was also highlighted in another study showing that AAV patients have reduced DNaseI activity resulting in less NET degradation. With this in mind, it might be that prolonged exposure to proteins in the NETs due to the overproduction of NETs and/or reduced clearance of NETs is important in AAV. However, not all ANCAs are pathogenic and some might possibly also aid in the clearance of NETs. A dual role for ANCAs in relation to circulating NET levels has been proposed because a negative correlation was observed between PR3-ANCA and NET remnants in patients in remission.

HMGB1Modulates the Treg/Th17 Ratio in Atherosclerotic Patients

AIM

Atherosclerosis (AS) characterized as a chronic inflammatory disease. Multiple immune cells and inflammatory cytokines, such as high mobility group protein (HMGB1), regulatory T (Treg) cells, T helper (Th17) cells, and inflammation-related cytokines, play a key role in its pathophysiology. A large number of studies report that HMGB1 and Th17 cells may promote atherosclerosis progression, whereas Treg cells may play a protective role in atherosclerosis; thus, alterations in the Treg/Th17 ratio may exist in atherosclerosis diseases. Up till now, the relationships between HMGB1 levels and the Treg/Th17 ratio remain incompletely understood. The major purpose of this study was to investigate the relationship between HMGB1 levels and the Treg/Th17 ratio in patients with coronary artery atherosclerotic plaques.

METHODS

We enrolled patients with coronary atherosclerosis and normal coronary artery as the research subjects. Flow cytometry was used to analyze the Treg cells, the Th17 cells frequency, and the Treg/Th17 ratio. Otherwise, real-time polymerase chain reaction was used for assays the mRNA expressions of HMGB1, retinoic acid-related orphan nuclear receptor C (RORC), and forkhead-winged helix transcription factor (Foxp3). Moreover, enzyme-linked immunosorbent assays were used to detect the level of protein and cytokines, such as HMGB1, IL-10, TGF-β1, IL-17A, and IL-23.

RESULTS

Using flow cytometry, we observed a significantly increased of Th17 cell frequency, whereas Treg cell frequency significantly decreased in atherosclerotic patients. Consistently, the levels of RORC mRNA were significantly increased in coronary atherosclerosis (AS) group compared to normal coronary artery (NCA) group (P＜0.01). In contrast, the expression of Foxp3 mRNA was markedly lower in the AS group than in the NCA group (P＜0.01). Furthermore, we observed the serum concentrations of HMGB1, IL-17A, and IL-23 were significantly higher in the AS group than in the NCA group (P＜0.01, respectively), whereas the concentrations of serum IL-10 and TGF-β1 were significantly lower in the AS group than in the NCA group (P＜0.01, respectively). In addition, we also found that HMGB1 levels showed negative correlation with the Treg/Th17 ratio in the two groups (r=－0.6984, P＜0.01).

CONCLUSIONS

The data in our study indicated that HMGB1 may promote atherosclerosis progression via modulating the imbalance in the Treg/Th17 ratio.

Disruption of a Regulatory Network Consisting of Neutrophils and Platelets Fosters Persisting Inflammation in Rheumatic Diseases

A network of cellular interactions that involve blood leukocytes and platelets maintains vessel homeostasis. It plays a critical role in the response to invading microbes by recruiting intravascular immunity and through the generation of neutrophil extracellular traps (NETs) and immunothrombosis. Moreover, it enables immune cells to respond to remote chemoattractants by crossing the endothelial barrier and reaching sites of infection. Once the network operating under physiological conditions is disrupted, the reciprocal activation of cells in the blood and the vessel walls determines the vascular remodeling via inflammatory signals delivered to stem/progenitor cells. A deregulated leukocyte/mural cell interaction is an early critical event in the natural history of systemic inflammation. Despite intense efforts, the signals that initiate and sustain the immune-mediated vessel injury, or those that enforce the often-prolonged phases of clinical quiescence in patients with vasculitis, have only been partially elucidated. Here, we discuss recent evidence that implicates the prototypic damage-associated molecular pattern/alarmin, the high mobility group box 1 (HMGB1) protein in systemic vasculitis and in the vascular inflammation associated with systemic sclerosis. HMGB1 could represent a player in the pathogenesis of rheumatic diseases and an attractive target for molecular interventions.

The role of high mobility group box 1 (HMGB1) in the pathogenesis of kidney diseases

High mobility group box 1 (HMGB1) is a nuclear protein that can bind to DNA and act as a co-factor for gene transcription. When released into extracellular fluid, it plays a proinflammatory role by acting as a damage-associated molecular pattern molecule (DAMP) (also known as an alarmin) to initiate innate immune responses by activating multiple cell surface receptors such as the receptor for advanced glycation end-products (RAGE) and toll-like receptors (TLRs), TLR2, TLR4 or TLR9. This proinflammatory role is now considered to be important in the pathogenesis of a wide range of kidney diseases whether they result from hemodynamic changes, renal tubular epithelial cell apoptosis, kidney tissue fibrosis or inflammation. This review summarizes our current understanding of the role of HMGB1 in kidney diseases and how the HMGB1-mediated signaling pathway may constitute a new strategy for the treatment of kidney diseases.

The Prevalence and Management of Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis in China

BACKGROUND

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) comprises microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA) and eosinophilic GPA (EGPA). Myeloperoxidase (MPO) and proteinase 3 (PR3) are the main antigens for ANCA. AAV is a common multisystem autoimmune disease and most of the studies on AAV have been conducted in Western countries. Nowadays in China many efforts are made to investigate this disease.

SUMMARY

This review highlights the progress in the prevalence, management and outcomes of AAV in Chinese patients. With respect to the prevalence of AAV, though there are no precise data, AAV is not rare in the Chinese population. In Chinese patients with AAV there is a striking preponderance of MPA, and MPO-ANCA is much more common than PR3-ANCA. Even in patients with GPA there is a predominance of MPO-ANCA over PR3-ANCA. Propylthiouracil-induced AAV and ANCA-negative pauci-immune glomerulonephritis are stated in this review as well. With respect to the management of AAV, glucocorticoids in combination with cyclophosphamide remain the mainstay of induction therapy. Besides, we describe predictors of different outcomes in Chinese patients, including mortality, relapse, treatment resistance and end-stage renal disease.

KEY MESSAGES

AAV is not rare in the Chinese population. The disease spectrum and subtypes of ANCA are different between patients with AAV in China and Western countries. The treatment strategy for AAV in China is in consistency with that in Western countries. Predictors of different clinical outcomes are provided.

FACTS FROM EAST AND WEST

Treatment options for AAV are shared between the East and West, with corticosteroid combined with cyclophosphamide being the standard regimen for inductive therapy and switching to azathioprine after remission. The major cause of death in treated patients is infection related to immunosuppressive therapy within the first year after diagnosis, and this rate might be higher in China than in Western countries. Western studies demonstrated the efficacy and safety of rituximab for induction of remission in cases with relatively mild disease and maintenance therapy, but this agent is rarely used in China.

High-mobility group box 1 potentiates antineutrophil cytoplasmic antibody-inducing neutrophil extracellular traps formation

Background

Recent studies found that the circulating high-mobility group box 1 (HMGB1) levels could reflect the disease activity of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). HMGB1 could prime neutrophils by increasing ANCA antigens translocation for ANCA-mediated respiratory burst and degranulation. The current study aimed to investigate whether HMGB1 participates in ANCA-induced neutrophil extracellular traps (NETs) formation, which is one of the most important pathogenic aspects in the development of AAV.

Methods

NETs were induced by treating neutrophils with HMGB1 and ANCA-positive IgG in vitro. NETs formation was assessed using immunofluorescence microscopy and fluorescence probe. Antagonist for relevant receptors Toll-like receptor (TLR)2, TLR4 and the receptor for advanced glycation end products (RAGE), as well as NADPH oxidase molecules were employed.

Results

The percentage of NETs formation was significantly higher in neutrophils stimulated with HMGB1 plus ANCA-positive IgG than that in neutrophils incubated with HMGB1 or ANCA-positive IgG alone. Consistently, compared with the nonstimulated neutrophils, the cell-free DNA (cfDNA) concentration of NETs was significantly increased from 334.09 ± 46.89 ng/ml to 563.32 ± 122.07 ng/ml in the neutrophils incubated with HMGB1 plus MPO-ANCA-positive IgG (P < 0.001), and from 303.44 ± 37.14 ng/ml to 563.79 ± 145.94 ng/ml in the neutrophils incubated with HMGB1 plus PR3-ANCA-positive IgG (P < 0.001). The aforementioned effect was significantly attenuated by antagonist for relevant receptors TLR2, TLR4 and RAGE, as well as blocking NADPH oxidase.

Conclusions

HMGB1 can potentiate ANCA-inducing NETs formation and may be involved in the pathogenesis of AAV. HMGB1 exerts effects on NETs formation through interaction with TLR2, TLR4 and RAGE, and the process is NADPH oxidase dependent.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0903-z) contains supplementary material, which is available to authorized users.

Involvement of high mobility group box 1 in the activation of C5a-primed neutrophils induced by ANCA

C5a plays a central role in antineutrophil cytoplasmic antibody (ANCA)-mediated neutrophil recruitment and activation. A previous study showed that C5a played a crucial role in the regulation of high mobility group box 1 (HMGB1) release from human neutrophils. The current study further investigated the interaction between C5a and HMGB1 in ANCA-induced neutrophil activation. The effects of HMGB1 inhibitors on the translocation of ANCA antigens, ANCA-induced respiratory burst and degranulation of C5a-primed neutrophils were tested. We found that blocking HMGB1 decreased C5a-mediated translocation of ANCA antigens, as well as ANCA-induced respiratory burst and degranulation of C5a-primed neutrophils. Further study showed that supernatant of C5a-primed neutrophils, which contained HMGB1, also caused translocation of ANCA antigens of primary neutrophils, whereas blocking HMGB1 decreased the translocation. In conclusion, blocking HMGB1 may attenuate ANCA-induced activation of C5a-primed neutrophils. The interaction between HMGB1 and C5a might play an important role in ANCA-induced neutrophil activation.

Urinary levels of high mobility group box-1 are associated with disease activity in antineutrophil cytoplasmic autoantibody-associated vasculitis

Background

High mobility group box-1 (HMGB1), a kind of pro-inflammatory mediator, is associated with inflammatory conditions and tissue damage. Our previous study demonstrated that the circulating levels of HMGB1 correlated with disease activity of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). In the current study, we aimed to measure urinary levels of HMGB1 in AAV patients, correlated them to clinical activity index and analysed the immunohistochemical HMGB1 staining in kidney specimens.

Methods

50 patients with AAV in active stage and 56 patients with AAV in remission were recruited. The urinary levels of HMGB1 were determined by enzyme-linked immunosorbent assay. Moreover, renal biopsy specimens from 27 patients with active AAV were randomly collected to evaluate the deposition of HMGB1.

Results

Urinary HMGB1 levels in AAV patients in active stage were significantly higher than those in AAV patients in remission and healthy controls (1.46 [0.56-3.43] versus 0.38 [0.10-1.35] mg/μmolCr, P=0.001; 1.46 [0.56-3.43] versus 0.48 [0.40-0.60] mg/μmolCr, P=0.000, respectively). Further analysis found that urinary levels of HMGB1 correlated with erythrocyte sedimentation rate (r=0.354, p=0.012), C-reactive protein (r=0.289, p=0.042), and Birmingham Vasculitis Activity Score (r=0.350, p=0.013). Renal tissue of active AAV patients showed HMGB1 was mainly expressed in the cytoplasm and the extracellular space. The percentage of HMGB1-negative nuclei in renal tissue of patients with active AAV was significantly higher than that in normal controls (60.6±20.2 % versus 2.7±0.6 %, p<0.01).

Conclusion

Urinary levels of HMGB1 may be associated with the disease activity in AAV patients.

High mobility group box 1 contributes to anti-neutrophil cytoplasmic antibody-induced neutrophils activation through receptor for advanced glycation end products (RAGE) and Toll-like receptor 4

Introduction

High mobility group box-1 (HMGB1), a typical damage-associated molecular pattern (DAMP) protein, is associated with inflammatory conditions and tissue damage. Our recent study found that circulating HMGB1 levels could reflect the disease activity of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The current study aimed to investigate whether HMGB1 participated in ANCA-induced neutrophil activation, which is one of the most important pathogenic aspects in the development of AAV.

Methods

The various effects of HMGB1 in ANCA-induced neutrophil activation were measured. Antagonists for relevant receptors and signaling molecules were employed.

Results

ANCA antigens translocation on neutrophils primed with HMGB1 was significantly higher than non-primed neutrophils. The levels of respiratory burst and degranulation increased significantly in HMGB1-primed neutrophils activated with ANCA-positive IgG, as compared with non-primed neutrophils. Furthermore, blocking Toll-like receptor 4 (TLR4) and receptor for advanced glycation end products (RAGE), rather than TLR2, resulted in a significant decrease in HMGB1-induced ANCA antigens translocation, respiratory burst and degranulation. Similar effects were also found when blocking MyD88 and NF-κB.

Conclusions

HMGB1 could prime neutrophils by increasing ANCA antigens translocation, and the primed neutrophils could be further induced by ANCA, resulting in the respiratory burst and degranulation. This process is TLR4- and RAGE-dependent through the MyD88/NF-κB pathway.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0587-4) contains supplementary material, which is available to authorized users.

C-reactive protein enhances activation of coagulation system and inflammatory response through dissociating into monomeric form in antineutrophil cytoplasmic antibody-associated vasculitis

Background

C-reactive protein (CRP) exerts prothrombotic effects through dissociating from pentameric CRP (pCRP) into modified or monomeric CRP (mCRP). However, although the high prevalence of venous thromboembolism (VTE) in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) has been identified, it remains unclear whether the high levels of circulating pCRP potentially contribute to this hypercoagulable state in AAV. ANCA can induce the generation of neutrophil extracellular traps (NETs). In this study, the NETs-dependent generation of mCRP from pCRP and the influences of mCRP on the activation of coagulation system and inflammatory response in AAV were investigated.

Results

NETs were induced after TNF-α primed neutrophils were incubated with ANCA-containing IgG. After ANCA-induced netting neutrophils were incubated statically with platelet-rich plasma (PRP) containing mCRP (60 μg/mL), the proportion of platelets expressing CD62p increased significantly, while no increased CD62p expression of platelets was observed after static incubation with PRP containing pCRP (60 μg/mL). Under flow conditions, perfusing immobilized ANCA-induced netting neutrophils with pCRP-containing PRP caused platelets activation and mCRP deposition. The newly generated mCRP induced platelets activation on ANCA-induced netting neutrophils, enhanced D-dimer formation, and enhanced high mobility group box 1 secretion by platelets.

Conclusions

Under flow conditions, ANCA-induced netting neutrophils can activate platelets and then prompt the formation of mCRP on activated platelets. Then the newly generated mCRP can further enhance the activation of platelets, the process of thrombogenesis, and the inflammatory response. So the high level of circulating pCRP is not only a sensitive marker for judging the disease activity, but also a participant in the pathophysiology of AAV.