Clinical features and prognosis of ANCA-associated vasculitis patients who were double-seropositive for myeloperoxidase-ANCA and proteinase 3-ANCA

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) patients with dual positivity for proteinase 3-ANCA (PR3-ANCA) and myeloperoxidase-ANCA (MPO-ANCA) are uncommon. We aimed to investigate these idiopathic double-positive AAV patients' clinical features, histological characteristics, and prognosis. We reviewed all the electronic medical records of patients diagnosed with AAV to obtain clinical data and renal histological information from January 2010 to December 2020 in a large center in China. Patients were assigned to the MPO-AAV group or PR3-AAV group or idiopathic double-positive AAV group by ANCA specificity. We explored features of idiopathic double-positive AAV. Of the 340 patients who fulfilled the study inclusion criteria, 159 (46.76%) were female, with a mean age of 58.41 years at the time of AAV diagnosis. Similar to MPO-AAV, idiopathic double-positive AAV patients were older and had more severe anemia, lower Birmingham Vasculitis Activity Score (BVAS) and C-reactive protein (CRP) levels, less ear, nose, and throat (ENT) involvement, higher initial serum creatinine and a lower estimated glomerular filtration rate (eGFR) when compared with PR3-AAV (P < 0.05). The proportion of normal glomeruli of idiopathic double-positive AAV was the lowest among the three groups (P < 0.05). The idiopathic double-positive AAV patients had the worst remission rate (58.8%) among the three groups (P < 0.05). The relapse rate of double-positive AAV (40.0%) was comparable with PR3-AAV (44.8%) (P > 0.05). Although there was a trend toward a higher relapse rate of idiopathic double-positive AAV (40.0%) compared with MPO-AAV (23.5%), this did not reach statistical significance (P > 0.05). The proportion of patients who progressed to ESRD was 47.1% and 44.4% in the idiopathic double-positive AAV group and MPO-AAV group respectively, without statistical significance. Long-term patient survival also varied among the three groups (P < 0.05). Idiopathic double-positive AAV is a rare clinical entity with hybrid features of MPO-AAV and PR3-AAV. MPO-AAV is the "dominant" phenotype in idiopathic double-positive AAV.

Elevated first-trimester neutrophil elastase and proteinase 3 increase the risk of gestational diabetes mellitus and adverse fetal outcomes

BACKGROUND

Chronic inflammation plays a vital role in the development of gestational diabetes mellitus (GDM). Studies in mouse models show that neutrophil serine proteases (NSPs), neutrophil elastase (NE) and proteinase-3 (PR3) are important drivers of chronic inflammation with consequent metabolic disturbances. This study evaluated the association of NE and PR3 with GDM development and adverse fetal outcomes.

METHOD(S)

This was a prospective cohort study. Serum PR3 and NE concentration was measured in all enrolled pregnant women in the first and the second trimester to determine the connection between NSPs and GDM and adverse fetal outcomes. Logistic regression, spline regression and linear regression analyses were applied to investigate the association of NE or PR3 with GDM development and adverse fetal outcomes. The concentration of NE and PR3 in placental biopsies was evaluated by semi-quantitative analysis of immunohistochemistry staining.

RESULT(S)

NE or PR3 concentration in the first trimester, rather than the second, increased more significantly in women with GDM than in those without, regardless of pre-pregnancy body mass index and age. There was a stepwise increase in GDM occurrence as well as comprehensive adverse fetal outcomes across tertiles of NE and PR3. NE and PR3 were positively associated with neutrophil count, pre-pregnancy BMI, plasma glucose level and newborn weight. Logistic regression revealed NE or PR3 to be independent risk factors for the development of GDM and comprehensive adverse fetal outcomes. Spline regression showed a significant increased risk of GDM occurrence and comprehensive adverse fetal outcomes when serum NE concentration exceeded 417.60 ng/mL and a similar result for PR3 and GDM occurrence when the latter exceeded 88.52 ng/mL. Immunohistochemistry data confirmed that enriched NE and PR3 content in placental tissue may have contributed to the development of GDM.

CONCLUSION(S)

This work demonstrates that excessive first-trimester NE and PR3 increase the risk of GDM development and comprehensive adverse fetal outcomes.

Isolation and characterisation of PR3-specific B cells and their immunoglobulin sequences

BACKGROUND

PR3 autoantibodies are essential to the diagnosis and monitoring of granulomatosus with polyangiitis, but to date no PR3 autoantibody sequences have been published.

OBJECTIVES

To identify and characterise PR3-specific B cells from the peripheral blood of patients with PR3 autoantibodies.

METHODS

Peripheral blood mononuclear cells from seven patients with PR3 autoantibodies were stained with PR3. B cells that bound PR3 underwent single cell sorting, transcriptome sequencing, and their immunoglobulin sequences expressed as antibodies and tested for PR3-specificity by ELISA.

RESULTS

We identified 19 PR3-specific B cells from only one PR3-seropositive patient at a low frequency (0.0075 % of B cells) in the peripheral blood. These were polyclonal, IgG+ and enriched for IgG4, lambda pairing, IGHJ6 gene usage, CDRH3 length, IGHE and CD71 expression. They demonstrated relatively low levels of somatic hypermutation and variably reduced PR3 binding when reverted to germline.

CONCLUSIONS

Identifying PR3-specific B cells in the peripheral blood is possible but challenging and those we did identify exhibited features suggesting that PR3-self reactivity may occur early in B-cell development.

Cathepsin C role in inflammatory gastroenterological, renal, rheumatic, and pulmonary disorders

Cathepsin C (CatC, syn. Dipeptidyl peptidase I) is a lysosomal cysteine proteinase expressed in several tissues including inflammatory cells. This enzyme is important for maintaining multiple cellular functions and for processing immune cell-derived proteases. While mutations in the CatC gene were reported in Papillon-Lefèvre syndrome, a rare autosomal recessive disorder featuring hyperkeratosis and periodontitis, evidence from clinical and preclinical studies points toward pro-inflammatory effects of CatC in various disease processes that are mainly mediated by the activation of neutrophil serine proteinases. Moreover, tumor-promoting effects were ascribed to CatC. The aim of this review is to highlight current knowledge of the CatC as a potential therapeutic target in inflammatory disorders.

Integrated proteogenomic characterization reveals an imbalanced hepatocellular carcinoma microenvironment after incomplete radiofrequency ablation

BACKGROUND

Efforts to precisely assess tumor-specific T-cell immune responses still face major challenges, and the potential molecular mechanisms mediating hepatocellular carcinoma (HCC) microenvironment imbalance after incomplete radiofrequency ablation (iRFA) are unclear. This study aimed to provide further insight into the integrated transcriptomic and proteogenomic landscape and identify a new target involved in HCC progression following iRFA.

METHODS

Peripheral blood and matched tissue samples were collected from 10 RFA-treated HCC patients. Multiplex immunostaining and flow cytometry were used to assess local and systemic immune responses. Differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) were explored via transcriptomic and proteogenomic analyses. Proteinase-3 (PRTN3) was identified in these analyses. And then, the ability of PRTN3 to predict overall survival (OS) was assessed in 70 HCC patients with early recurrence after RFA. In vitro CCK-8, wound healing and transwell assays were conducted to observe interactions between Kupffer cells (KCs) and HCC cells induced by PRTN3. The protein levels of multiple oncogenic factors and signaling pathway components were detected by western blotting. A xenograft mouse model was built to observe the tumorigenic effect of PRTN3 overexpression on HCC.

RESULTS

Multiplex immunostaining revealed no immediate significant change in local immune cell counts in periablational tumor tissues after 30 min of iRFA. Flow cytometry showed significantly increased levels of CD4⁺ T cells, CD4⁺CD8⁺ T cells, and CD4⁺CD25⁺CD127^- Tregs and significantly decreased the levels of CD16⁺CD56⁺ natural killer cells on day 5 after cRFA (p < 0.05). Transcriptomics and proteomics revealed 389 DEGs and 20 DEPs. Pathway analysis showed that the DEP-DEGs were mainly enriched in the immunoinflammatory response, cancer progression and metabolic processes. Among the DEP-DEGs, PRTN3 was persistently upregulated and closely associated with the OS of patients with early recurrent HCC following RFA. PRTN3 expressed in KCs may affect the migration and invasion of heat stress-treated HCC cells. PRTN3 promotes tumor growth via multiple oncogenic factors and the PI3K/AKT and P38/ERK signaling pathways.

CONCLUSIONS

This study provides a comprehensive overview of the immune response and transcriptomic and proteogenomic landscapes of the HCC milieu induced by iRFA, revealing that PRTN3 promotes HCC progression after iRFA.

TRIAL REGISTRATION

ChiCTR2200055606, http://www.chictr.org.cn/showproj.aspx?proj=32588 .

Dipeptidyl peptidase-1 inhibition with brensocatib reduces the activity of all major neutrophil serine proteases in patients with bronchiectasis: results from the WILLOW trial

BACKGROUND

Brensocatib is an oral, selective, reversible inhibitor of dipeptidyl peptidase-1 (DPP-1), responsible for activating neutrophil serine proteases (NSPs) including neutrophil elastase (NE), proteinase 3 (PR3), and cathepsin G (CatG). In chronic inflammatory lung diseases such as non-cystic fibrosis bronchiectasis (NCFBE), neutrophils accumulate in the airways resulting in excess active NSPs that cause damaging inflammation and lung destruction.

METHODS

The 24-week WILLOW trial (NCT03218917) was a randomized, double-blind, placebo-controlled, parallel-group trial in patients with NCFBE conducted at 116 sites across 14 countries. In this trial, treatment with brensocatib was associated with improvements in clinical outcomes including time to first exacerbation, reduction in exacerbation frequency and a reduction in NE activity in sputum. An exploratory analysis of NE activity in white blood cell (WBC) extracts and NE, PR3 and CatG activity in sputum was conducted to further characterize brensocatib's effect and identify potential correlated effects.

RESULTS

NE, PR3 and CatG activities were reduced in sputum and NE activity was reduced in WBC extracts in a dose-dependent manner after four weeks of brensocatib treatment, with a return to baseline four weeks after the end of treatment. Brensocatib produced the greatest reduction in the sputum activity of CatG, followed by NE and then PR3. Positive correlations among the sputum NSPs were observed both at baseline and in response to treatment, with the strongest correlation among the sputum NSPs for NE and CatG.

CONCLUSIONS

These results suggest a broad anti-inflammatory effect of brensocatib underlying its clinical efficacy observed in NCFBE patients.

TRIAL REGISTRATION

The study was approved by the corresponding ethical review boards of all participating centers. The trial was approved by the Food and Drug Administration and registered at clinicaltrials.gov (NCT03218917) on July 17, 2017 and approved by the European Medicines Agency and registered at the European Union Clinical trials Register (EudraCT No. 2017-002533-32). An independent, external data and safety monitoring committee (comprising physicians with pulmonary expertise, a statistician experienced in the evaluation of clinical safety, and experts in periodontal disease and dermatology) reviewed all adverse events.

Association of admission neutrophil serine proteinases levels with the outcomes of acute ischemic stroke: a prospective cohort study

BACKGROUND

Neutrophil serine proteinases (NSPs), released by activated neutrophils, are key proteins involved in the pathophysiologic processes of stroke. NSPs are also implicated in the process and response of thrombolysis. This study aimed to analyze three NSPs (neutrophil elastase, cathepsin G, and proteinase 3) in relation to acute ischemic stroke (AIS) outcomes and in relation to the outcomes of patients treated with intravenous recombinant tissue plasminogen activator (IV-rtPA).

METHODS

Among 736 patients prospectively recruited at the stroke center from 2018 to 2019, 342 patients diagnosed with confirmed AIS were included. Plasma neutrophil elastase (NE), cathepsin G (CTSG), and proteinase 3 (PR3) concentrations were measured on admission. The primary endpoint was unfavorable outcome defined as modified Rankin Scale score 3-6 at 3 months, and the secondary endpoints were symptomatic intracerebral hemorrhage (sICH) within 48 h, and mortality within 3 months. In the subgroup of patients who received IV-rtPA, post-thrombolysis early neurological improvement (ENI) (defined as National Institutes of Health Stroke Scale score = 0 or decrease of ≥ 4 within 24 h after thrombolysis) was also included as the secondary endpoint. Univariate and multivariate logistic regression analyses were performed to evaluate the association between NSPs levels and AIS outcomes.

RESULTS

Higher NE and PR3 plasma levels were associated with the 3-month mortality and 3-month unfavorable outcome. Higher NE plasma levels were also associated with the risk of sICH after AIS. After adjusting for potential confounders, plasma NE level > 229.56 ng/mL (odds ratio [OR] = 4.478 [2.344-8.554]) and PR3 > 388.77 ng/mL (OR = 2.805 [1.504-5.231]) independently predicted the 3-month unfavorable outcome. Regarding rtPA treatment, patients with NE plasma concentration > 177.22 ng/mL (OR = 8.931 [2.330-34.238]) or PR3 > 388.77 ng/mL (OR = 4.275 [1.045-17.491]) were over 4 times more likely to suffer unfavorable outcomes after rtPA treatment. The addition of NE and PR3 to clinical predictors of unfavorable functional outcome after AIS and the outcome after rtPA treatment improved discrimination as well as reclassification (integrated discrimination improvement = 8.2% and 18.1%, continuous net reclassification improvement = 100.0% and 91.8%, respectively).

CONCLUSIONS

Plasma NE and PR3 are novel and independent predictors of 3-month functional outcomes after AIS. Plasma NE and PR3 also possess predictive value to identify patients with unfavorable outcomes after rtPA treatment. NE is probably an important mediator of the effects of neutrophils on stroke outcomes, which worth further investigation.

Performance of MPO-ANCA and PR3-ANCA immunoassays for the stratification of specific ANCA-associated vasculitis: A systematic review and meta-analysis

OBJECTIVE

To determine the impact of myeloperoxidase (MPO) and proteinase 3 (PR3) antigen-specific immunoassays in the stratification of patients at-risk for anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitides (AAV) at diagnosis.

METHODS

A Medline search was conducted to identify diagnostic accuracy studies using PR3-ANCA or MPO-ANCA for the evaluation of granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Studies estimates were pooled using the bivariate method.

RESULTS

Diagnostic accuracy varied by analyte and AAV subtype. PR3-ANCA had greater sensitivity than MPO-ANCA for GPA (74% vs 11%, p < 0.001) and MPO-ANCA greater sensitivity for MPA (73% vs 7%, p < 0.001). Specificities of both MPO-ANCA and PR3-ANCA were consistently high (mean 97%, range: 93-99%) for both AAV subtypes. There was insufficient data to perform meta-analysis for the diagnostic accuracy of EPGA.

CONCLUSION

These results validate the use of high quality MPO-ANCA and PR3-ANCA immunoassays to screen patients at-risk for AAV as well as to categorize disease as GPA or MPA subtype. However, caution must be exercised in doing so, since some assays may not have optimal performance. Each laboratory should validate appropriate algorithms based on the tests used and testing population.

Increased Neutrophil elastase and proteinase 3 are closely associated with occurrence and severity of stroke and acute myocardial infarction in patients with type 2 diabetes mellitus

AIMS

The role of Neutrophil elastase (NE) and proteinase 3 (PR3) in the occurrence and severity of stroke and acute myocardial infarction (AMI) have not been explored in type 2 diabetes mellitus (T2DM). This study aimed to investigate the relationship and predictive ability of NE and PR3 in the development of stroke and AMI in patients with T2DM, and to explore the pattern of NE and PR3 in atherosclerotic plaques.

METHODS

465 patients with T2DM (stroke or AMI, n = 234; non stroke or AMI, n = 231) were recruited. Clinical characteristics, and NE and PR3 concentration were measured in all subjects. Semi-quantitative analysis of immunohistochemistry staining for NE and PR3 was performed in detached emboli and stable plaques.

RESULTS

Patients with stroke or AMI had a higher level of NE and PR3, with a more pronounced increase in more severe cases (higher mRS score in stroke and Gensini score in AMI) and associated with clinical markers. An increase in NE and PR3 was an independent risk factor for stroke (OR = 4.318, P = 0.017; OR = 2.979, P = 0.048, respectively) and AMI (OR = 8.385, P = 0.015; OR = 5.540, P = 0.047). Finally, immunohistochemistry staining revealed that the NE and PR3 positive area increased significantly in detached emboli compared with stable plaques.

CONCLUSION

Increased NE and PR3 was associated with occurrence and severity of stroke and AMI in patients with T2DM. Enriched NE and PR3 in detached emboli may be associated with plaque vulnerability.

Does peri-implant bone loss affect the LL-37 and proteinase 3 levels in peri-implant sulcus fluid?

BACKGROUND

Inactive human cathelicidin antimicrobial peptide is present in neutrophils, and proteinase 3 activates this peptide by producing active LL-37 peptide. LL-37 acts as a defensive peptide in the oral tissues. In the present study, the aim was to evaluate LL-37 and proteinase 3 levels in peri-implant sulcus fluid (PISF) in implants with and without peri-implantitis.

METHODS

Patients who simultaneously had dental implants with peri-implantitis and without peri-implantitis were included in the study. Forty-four samples with peri-implantitis and 34 samples without peri-implantitis from 16 patients were obtained. Intraoral evaluations such as pocket depth, modified sulcus bleeding index, and modified plaque index were noted. Enzyme-linked immunosorbent assay was used for the evaluation of PISF LL-37 and proteinase 3 levels.

RESULTS

PISF volume was significantly increased in the implants with peri-implantitis than those without peri-implantitis (p < 0.05). No difference was present between PISF LL-37 and proteinase 3 total amounts between the implants with and without peri-implantitis (p > 0.05). Pocket depths and PISF LL-37 and proteinase 3 levels were not correlated in the groups (p > 0.05).

CONCLUSIONS

PISF volume might be increased in response to peri-implant bone destruction. However, peri-implant tissue destruction caused by peri-implantitis does not seem to affect PISF LL-37 and proteinase 3 levels.

Remote Activation of a Latent Epitope in an Autoantigen Decoded With Simulated B-Factors

Mutants of a catalytically inactive variant of Proteinase 3 (PR3)—iPR3-Val¹⁰³ possessing a Ser195Ala mutation relative to wild-type PR3-Val¹⁰³—offer insights into how autoantigen PR3 interacts with antineutrophil cytoplasmic antibodies (ANCAs) in granulomatosis with polyangiitis (GPA) and whether such interactions can be interrupted. Here we report that iHm5-Val¹⁰³, a triple mutant of iPR3-Val¹⁰³, bound a monoclonal antibody (moANCA518) from a GPA patient on an epitope remote from the mutation sites, whereas the corresponding epitope of iPR3-Val¹⁰³ was latent to moANCA518. Simulated B-factor analysis revealed that the binding of moANCA518 to iHm5-Val¹⁰³ was due to increased main-chain flexibility of the latent epitope caused by remote mutations, suggesting rigidification of epitopes with therapeutics to alter pathogenic PR3·ANCA interactions as new GPA treatments.

Expression of serine proteases in neutrophils from women and men: Regulation by endocrine disruptor bisphenol A

Bisphenol A (BPA) is a well-known endocrine disruptor. However, little information is available about its immunological effects. In the present study, we aimed to evaluate cytotoxic activity of BPA on human polymorphonuclear neutrophils (PMNs) according to gender and examine its effect on the expression of neutrophil serine proteases. Results indicated that exposure to BPA (above 16 μM) leads to a decrease in viability of PMNs and to morphological changes in these cells of both genders. The experiments showed different effects of BPA on the expression of proteinase 3, elastase, and cathepsin G in PMNs of both men and women, depending on the gender and concentration used. Thus, our findings suggest for the first time that through dysregulation of the expression of these enzymes, BPA may lead to disorders of the nonspecific cellular response in people exposed to this xenoestrogen.

[Changes and clinical significance of serum proteinase 3 in latent autoimmune diabetes in adults]

Objective: To investigate the changes of circulating proteinase 3 (PR3) in latent autoimmune diabetes mellitus in adults (LADA) patients, type 2 diabetes mellitus (T2DM) patients, obese patients without diabetes and healthy controls, and explore the value of serum PR3 in differentiating LADA and T2DM. Methods: Forty LADA patients, 29 T2DM patients, 26 obesity patients without diabetes, and 76 healthy controls were enrolled in Department of Metabolism & Endocrinology, the Second Xiangya Hospital, Central South University. Serum PR3 was detected by enzyme-linked immunosorbent assay (ELISA). The differences of serum PR3 among the four groups were compared. The correlation between serum PR3 and other metabolic indexes was analyzed. The value of serum PR3 in the differential diagnosis between LADA and T2DM was evaluated. Results: There was no significant difference in age among LADA patients, T2DM patients, obesity patients without diabetes and healthy controls [(50±13) years, (49±6) years, (49±6) years vs (47±7) years, P=0.254], while there was significant difference in gender among the four groups (χ(2)=18.28, P<0.001). Serum PR3 was significantly increased in LADA patients compared to the other three groups [195.4 (127.6, 288.1) μg/L vs 43.4 (30.9, 53.7) μg/L, 36.0 (29.2, 46.4) μg/L, 41.2 (30.2, 52.8) μg/L, all P<0.01], whereas there was no significant differences among the other three groups. After adjustment for age, gender and body mass index (BMI), serum PR3 remained higher in LADA patients compared to the other three groups. Correlation analysis indicated that PR3 correlated positively with fasting and 2-hour postprandial blood glucose (r=0.346, r=0.357, both P<0.001). Receiver operating characteristic (ROC) curve showed that the cut-off value of PR3 (71.7 μg/L) for differentiating LADA and T2DM had a sensitivity of 97.5% and specificity of 89.7% and rendered an area under the curve of 0.955 (95%CI: 0.894~1.000, compared to 0.5, P<0.01). Conclusion: Serum PR3 significantly elevated in LADA patients, and may serve as a biomarker for differentiating LADA and T2DM patients.

Distinction between MPO-ANCA and PR3-ANCA-associated glomerulonephritis in Chinese patients: a retrospective single-center study

OBJECTIVES

To retrospectively investigate the clinical and histological features and outcomes of ANCA-associated glomerulonephritis (AAGN) with different ANCA serotypes.

METHOD

A total of 467 AAGN patients were divided into MPO-AAGN (MPO) and PR3-AAGN (PR3) groups according to ANCA serotype. Clinical and histological features and renal outcomes were compared.

RESULTS

In this study, 429 (91.9%) patients tested positive for MPO-ANCA, and 38 (8.1%) for PR3-ANCA. The median age at diagnosis (P = 0.017) and proportion of females (P = 0.003) were higher in the MPO group. Joint (P < 0.001), ENT (P = 0.000), skin (P = 0.007), and eye (P = 0.014) involvements were more common in the PR3 group. Compared with that in the PR3-group, a higher proportion of patients in the MPO group had microscopic polyangiitis (P = 0.000), and a lower proportion of exhibited granulomatosis with polyangiitis (P = 0.000). Patients in the MPO group also exhibited lower BVAS scores (P = 0.003) and higher serum albumin levels (P = 0.009). Histologically, a lower proportion of MPO patients had crescentic glomerulonephritis (P = 0.028) and acute tubule-interstitial lesion scores (P = 0.007), but a higher proportion of these patients exhibited mixed class glomerulonephritis (P = 0.032) than in the PR3 group. The relapse rate was lower (P = 0.020), and the 5-year relapse-free survival rate (P = 0.003) was higher in the MPO group than in the PR3 group. However, the 5-year renal survival rates (P = 0.106) were not significantly different.

CONCLUSIONS

MPO-ANCA was predominant in Chinese patients with ANCA-associated vasculitis and renal disease. The epidemiological characteristics, extra-renal involvement, and histopathological classes and outcomes were different between MPO-positive and PR3-positive patients, implying that they might be two different disease entities.

Non-invasive profiling of protease-specific elastin turnover in lung cancer: biomarker potential

PURPOSE

Elastin is a signature protein of lungs. Increased elastin turnover driven by altered proteolytic activity is an important part of lung tumorigenesis. Elastin-derived fragments have been shown to be pro-tumorigenic, however, little is known regarding the biomarker potential of such elastin fragments. Here, we present an elastin turnover profile by non-invasively quantifying five specific elastin degradation fragments generated by different proteases.

METHODS

Elastin fragments were assessed in serum from patients with stage I-IV non-small cell lung cancer (NSCLC) (n = 40) and healthy controls (n = 30) using competitive ELISAs targeting different protease-generated fragments of elastin: ELM12 (generated by matrix metalloproteinase MMP-9 and -12), ELM7 (MMP-7), EL-NE (neutrophil elastase), EL-CG (cathepsin G) and ELP-3 (proteinase 3).

RESULTS

ELM12, ELM7, EL-NE and EL-CG were all significantly elevated in NSCLC patients (n = 40) when compared to healthy controls (n = 30) (ELM12, p = 0.0191; ELM7, p < 0.0001; EL-NE, p < 0.0001; EL-CG, p < 0.0001). ELP-3 showed no significant difference between patients and controls (p = 0.8735). All fragments correlated positively (Spearman, r: 0.69-0.81) when compared pairwise, except ELM12 (Spearman, r: 0.042-0.097). In general, all fragments were detectable across all stages of the disease.

CONCLUSIONS

Elastin fragments generated by different proteases are elevated in lung cancer patients compared to healthy controls but differ in their presence. This demonstrates non-invasive biomarker potential of elastin fragments in serum from lung cancer patients and suggests that different pathological mechanisms may be responsible for the elastin turnover, warranting further validation in clinical trials.

Proteinase 3 Limits the Number of Hematopoietic Stem and Progenitor Cells in Murine Bone Marrow

Hematopoietic stem and progenitor cells (HSPCs) undergo self-renewal and differentiation to guarantee a constant supply of short-lived blood cells. Both intrinsic and extrinsic factors determine HSPC fate, but the underlying mechanisms remain elusive. Here, we report that Proteinase 3 (PR3), a serine protease mainly confined to granulocytes, is also expressed in HSPCs. PR3 deficiency intrinsically suppressed cleavage and activation of caspase-3, leading to expansion of the bone marrow (BM) HSPC population due to decreased apoptosis. PR3-deficient HSPCs outcompete the long-term reconstitution potential of wild-type counterparts. Collectively, our results establish PR3 as a physiological regulator of HSPC numbers. PR3 inhibition is a potential therapeutic target to accelerate and increase the efficiency of BM reconstitution during transplantation.

•

Proteinase 3 (PR3) is expressed in hematopoietic stem and progenitor cells (HSPCs)

•

Deficiency of PR3 leads to expansion of HSPCs in murine bone marrow

•

PR3 regulates spontaneous HSPC apoptosis by cleaving and activating caspase-3

Lung tissue destruction by proteinase 3 and cathepsin G mediated elastin degradation is elevated in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by high levels of protease activity leading to degradation of elastin followed by loss of elasticity of the lung and the development of emphysema. Elastin is an essential structural component of the lung parenchyma to support the expansion and recoil of the alveoli during breathing. The lung extracellular matrix is vulnerable to pathological structural changes upon upregulation of serine proteases, including cathepsin G (CG) and proteinase 3 (PR3). In this study, we explored the diagnostic features of elastin neo-epitopes generated by CG and PR3. Two novel competitive enzyme-linked immunosorbent assays (ELISA) measuring CG and PR3 generated elastin fragments (EL-CG and ELP-3 respectively) were developed for assessment in serum. Both assays were technically robust and biologically validated in serum from patients with COPD. Serological levels of both elastin fragments were significantly elevated in patients with COPD compared to healthy controls. These data suggest that EL-CG and ELP-3 may serve as plausible biologic markers of destructive changes in COPD.

Myeloperoxidase-ANCA-positive granulomatosis with polyangiitis is a distinct subset of ANCA-associated vasculitis: A retrospective analysis of 455 patients from a single center in China

OBJECTIVE

Antineutrophil cytoplasmic antibody (ANCA) directed to proteinase 3 (PR3) used to be considered the serologic marker for granulomatosis with polyangiitis (GPA). However, patients with myeloperoxidase (MPO)-ANCA positive GPA have been increasingly reported. The aim of this study was to analyze the clinical and pathological characteristics and outcome of Chinese patients with MPO-ANCA positive GPA.

METHODS

The clinical and renal histology data, renal outcomes, response to treatment, relapse and mortality were compared between patients with MPO-ANCA positive GPA and MPO-ANCA positive microscopic polyangiitis (MPA) as well as proteinase 3 (PR3)-ANCA positive GPA.

RESULTS

455 patients with ANCA-associated vasculitis (AAV) were recruited in this study. 276/455 patients were classified as MPO-ANCA positive MPA, 4/455 patients were classified as PR3-ANCA positive MPA, 124/455 were MPO-ANCA positive GPA and 51/455 were PR3-ANCA positive GPA. Compared with MPO-ANCA positive MPA patients, MPO-ANCA positive GPA patients had significantly higher level of BVAS and milder renal lesion at diagnosis. The probability of developing ESRD was significantly higher in patients with MPO-ANCA positive MPA than MPO-ANCA positive GPA. MPO-ANCA positive GPA patients were likely to have relapse than MPO-ANCA positive MPA patients. Compared with PR3-ANCA positive GPA patients, MPO-ANCA positive GPA patients had significantly higher proportion of female, less constitutional symptoms and milder renal lesion at diagnosis.

CONCLUSIONS

Patients with MPO-ANCA positive GPA should be regarded as a unique subset of AAV. This subset of AAV patients had relatively milder renal injury. Although ANCA specificities play an important role in differentiating AAV, taking the disease type together to classify AAV may be more rational.

JMJD3 is involved in neutrophil membrane proteinase 3 overexpression during the hyperinflammatory response in early sepsis

Excessive production of pro-inflammatory cytokines in early sepsis causes high early mortality rates. Membrane proteinase 3 (mPR3) expression on neutrophils plays a critical role in pro-inflammatory cytokine production. However, the mechanism underlying mPR3 overexpression in early sepsis is unknown. Here, we explored mPR3 expression in early sepsis and its regulatory mechanism. Thirty-two patients with sepsis and 20 healthy controls were prospectively enrolled. On day 1 after the onset of sepsis, mPR3 and jumonji domain-containing protein D3 (JMJD3) expression levels were measured in peripheral blood neutrophils. Lipopolysaccharide (LPS) was employed to induce JMJD3 expression in vitro, and GSK-J4 was used to inhibit JMJD3. Neutrophils were divided into four groups, control, LPS, LPS + GSK-J4, and GSK-J4, and cultured with THP-1 cells respectively. Plasma and culture supernatant cytokine levels were measured by enzyme-linked immunosorbent assays. Neutrophil mPR3 levels were significantly higher in patients with early sepsis than in healthy controls. Plasma cytokine (IL-1β and TNF-α) levels were increased in patients with sepsis exhibiting high mPR3 expression. Additionally, JMJD3 expression levels in neutrophils were increased in early sepsis. In vitro, both mPR3 on neutrophils and IL-1β in culture supernatants increased in response to LPS stimulation. Neutrophil mPR3 expression and IL-1β levels were significantly reduced by GSK-J4 in cells treated with LPS. IL-1β level was significantly higher in LPS-stimulated co-culture supernatants than in the corresponding individual cultured cells. Thus, our results suggest that JMJD3 contributes to the high expression of neutrophil mPR3, which promotes the production of proinflammatory IL-1β in early sepsis.

IL-32-induced Inflammatory Cytokines Are Selectively Suppressed by α1-antitrypsin in Mouse Bone Marrow Cells

The induction of interleukin (IL)-32 in bone marrow (BM) inflammation is crucial in graft versus host disease (GvHD) that is a common side effect of allogeneic BM transplantation. Clinical trials on α-1 antitrypsin (AAT) in patients with GvHD are based on the preliminary human and mouse studies on AAT reducing the severity of GvHD. Proteinase 3 (PR3) is an IL-32-binding protein that was isolated from human urine. IL-32 primarily induces inflammatory cytokines in myeloid cells, probably due to PR3 expression on the membrane of the myeloid lineage cells. The inhibitory activity of AAT on serine proteinases may explain the anti-inflammatory effect of AAT on GvHD. However, the anti-inflammatory activity of AAT on BM cells remains unclear. Mouse BM cells were treated with IL-32γ and different inflammatory stimuli to investigate the anti-inflammatory activity of AAT. Recombinant AAT-Fc fusion protein inhibited IL-32γ-induced IL-6 expression in BM cells, but failed to suppress that induced by other stimuli. In addition, the binding of IL-32γ to PR3 was abrogated by AAT-Fc. The data suggest that the specific anti-inflammatory effect of AAT in mouse BM cells is due to the blocking of IL-32 binding to membrane PR3.

Microscopic polyangiitis: Advances in diagnostic and therapeutic approaches

Microscopic polyangiitis (MPA) is an idiopathic autoimmune disease characterized by systemic vasculitis. The disease predominantly affects small-calibre blood vessels and is associated with the presence of antineutrophil cytoplasmic autoantibodies (ANCA). Microscopic polyangiitis was considered to be a disease entity by Savage et al. in 1985. Microscopic polyangiitis has a reported low incidence and a slight male predominance. The aetiology of MPA remains unknown. There is, however, increased evidence that MPA is an autoimmune disease in which ANCAs, particularly those reacting with MPO, are pathogenic. MPA belongs to the systemic vasculitides, indicating that multiple organs can be affected. The major organs involved in MPA are the kidneys and the lungs. As expected for an illness that affects multiple organ systems, patients with MPA can present with a myriad of different symptoms. Ear, nose and throat (ENT) manifestations are not considered to be clinical symptoms of MPA, but in the majority of populations described, ENT involvement was found in surprisingly high percentages. MPA is part of the ANCA-associated vasculitides, which are characterized by necrotizing vasculitis of small vessels. Diagnosis is mainly established by clinical manifestations, computed tomography (TC), ANCA antibody detection and renal and pulmonary biopsy. The introduction of aggressive immunosuppressive treatment has substantially improved the prognosis. The standardized therapeutic regimen is based on cyclophosphamide and corticosteroids. Using this regimen, remission can be achieved in most of the patients. Rituximab may represent an important alternative to cyclophosphamide for patients who may not respond adequately to antimetabolite therapies.

Allosteric modulation of proteinase 3 activity by anti-neutrophil cytoplasmic antibodies in granulomatosis with polyangiitis

Anti-neutrophil cytoplasmic antibodies (ANCA) with proteinase 3 (PR3) specificity are a useful laboratory biomarker for the diagnosis of Granulomatosis with Polyangiitis (GPA) and are believed to be implicated in the pathogenesis. It has been repeatedly suggested that disease activity of GPA is more closely related to the appearance and rise of PR3-inhibiting ANCA than to an increase of total ANCA. Previous studies on a limited number of patient samples, however, have yielded inconclusive results. To overcome the previous methodological limitations, we established a new ultrasensitive method to quantify the inhibitory capacity of PR3-ANCA using small volumes of plasma from patients with GPA. A large collection of longitudinally-collected samples from the Wegener Granulomatosis Etanercept Trial (WGET) became available to us to determine the functional effects of ANCA on PR3 in comparison to clinical disease manifestations. In these patient samples we not only detected PR3-ANCA with inhibitory capacity, but also PR3-ANCA with enhancing effects on PR3 activity. However no correlation of these activity-modulating PR3-ANCA with disease activity at either the time of enrollment or over the course of disease was found. Only patients with pulmonary involvement, especially patients with nodule formation in the respiratory tract, showed a slight, but not significant, decrease of inhibitory capacity. Epitope mapping of the activity-modulating PR3-ANCA revealed a binding on the active site surface of PR3. Yet these ANCA were able to bind to PR3 with an occupied active site cleft, indicating an allosteric mechanism of inhibition. The recently described signal ratio between the MCPR3-3 and MCPR3-2 capture ELISA was consistent with the binding of activity-modulating ANCA to the active site surface. Evidence for a shared epitope between activity-modulating PR3-ANCA and MCPR3-7, however, was very limited, suggesting that a majority of PR3-ANCA species do not inhibit PR3 by the same mechanism as previously reported for MCPR3-7.

Two homologous neutrophil serine proteases bind to POPC vesicles with different affinities: When aromatic amino acids matter

Neutrophil serine proteases Proteinase 3 (PR3) and human neutrophil elastase (HNE) are homologous antibiotic serine proteases of the polymorphonuclear neutrophils. Despite sharing a 56% sequence identity they have been shown to have different functions and localizations in the neutrophils. In particular, and in contrast to HNE, PR3 has been detected at the outer leaflet of the plasma membrane and its membrane expression is a risk factor in a number of chronic inflammatory diseases. Although a plethora of studies performed in various cell-based assays have been reported, the mechanism by which PR3, and possibly HNE bind to simple membrane models remains unclear. We used surface plasmon resonance (SPR) experiments to measure and compare the affinity of PR3 and HNE for large unilamellar vesicles composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). We also conducted 500-nanosecond long molecular dynamics simulations of each enzyme at the surface of a POPC bilayer to map the interactions between proteins and lipids and rationalize the difference in affinity observed in the SPR experiment. We find that PR3 binds strongly to POPC large unilamellar vesicles (Kd=9.2×10(-7)M) thanks to the insertion of three phenylalanines, one tryptophan and one leucine beyond the phosphate groups of the POPC lipids. HNE binds in a significantly weaker manner (Kd>10(-5)M) making mostly electrostatic interactions via lysines and arginines and inserting only one leucine between the hydrophobic lipid tails. Our results support the early reports that PR3, unlike HNE, is able to directly and strongly anchor directly to the neutrophil membrane.

Antineutrophil cytoplasm antibody: positivity and clinical correlation

OBJECTIVE

To determine positivity and clinical correlation of anti-neutrophil cytoplasmic antibodies (ANCA), taking into account the interference of antinuclear antibodies (ANA).

MATERIAL AND METHODS

A prospective study was conducted in the Laboratory of Immunology of the National Cuban Center of Medical Genetic during one year. Two hounded sixty-seven patients with indication for ANCA determination were included. ANCA and ANA determinations with different cut off points and assays were determined by indirect immunofluorescense. Anti proteinase 3 and antimyeloperoxidase antibodies were determined by ELISA.

RESULTS

Most positivity for ANCA was seen in patients with ANCA associated, primary small-vessel vasculitides, rheumatoid arthritis and systemic lupus erythematosus. Presence of ANCA without positivity for proteinase 3 and myeloperoxidase was higher in patients with ANA and little relation was observed between the perinuclear pattern confirmed in formalin and specificity by myeloperoxidase. Highest sensibility and specificity values for vasculitides diagnostic were achieved by ANCA determination using indirect immunofluorescense with a cut off 1/80 and confirming antigenic specificities with ELISA.

CONCLUSION

ANCA can be present in a great number of chronic inflammatory or autoimmune disorders in the population studied. This determination using indirect immunofluorescence and following by ELISA had a great value for vasculitis diagnosis. Anti mieloperoxidasa assay has a higher utility than the formalin assay when ANA is present.

Are anti-proteinase-3 ANCA a useful marker of granulomatosis with polyangiitis (Wegener's) relapses? Results of a retrospective study on 126 patients

OBJECTIVES

Predicting granulomatosis with polyangiitis (Wegener's) (GPA) relapses based on ANCA titers remains a source of debate. Our objective was to evaluate the relevance of monitoring PR3-ANCA titers for GPA management.

METHODS

This retrospective study included 126 patients fulfilling the 1990 ACR criteria for GPA and PR3-ANCA-positive at the time of diagnosis. Disease activity was assessed with BVAS/WG and Disease Extent Index. For each patient, a median of 12 serum samples was analyzed, i.e., one every 5.5months.

RESULTS

Induction therapy obtained remission in 88% of the patients. ANCA became negative by IF for 70/115 (60.9%) patients and by ELISA for 90/115 (78.3%). After median follow-up of 70months, 85/126 (67.5%) patients had 154 clinical relapses associated with cANCA and PR3-ANCA-positivity for 122 (79.2%) and 102 (66.2%) of them, respectively. Relapse-free survival was significantly longer for patients who remained PR3-ANCA-negative (HR 0.60 [95% CI 0.39-0.92], P=0.02). Individual ANCA-profile analysis revealed that, for 60% of GPA patients, clinical outcomes and ANCA-titer changes were closely associated, i.e., ANCA were always positive during relapses and negative during remission. The 35 patients with fluctuating ANCA-positivity during remission were in partial remission or had developed grumbling GPA.

CONCLUSION

Although ANCA were positive during most systemic relapses or residual disease, no strict clinical-immunological correspondence was observed for 25% of the patients. Thus, GPA management cannot be based on ANCA levels alone.

A monoclonal antibody (MCPR3-7) interfering with the activity of proteinase 3 by an allosteric mechanism

Proteinase 3 (PR3) is an abundant serine protease of neutrophil granules and a major target of autoantibodies (PR3 anti-neutrophil cytoplasmic antibodies) in granulomatosis with polyangiitis. Some of the PR3 synthesized by promyelocytes in the bone marrow escapes the targeting to granules and occurs on the plasma membrane of naive and primed neutrophils. This membrane-associated PR3 antigen may represent pro-PR3, mature PR3, or both forms. To discriminate between mature PR3 and its inactive zymogen, which have different conformations, we generated and identified a monoclonal antibody called MCPR3-7. It bound much better to pro-PR3 than to mature PR3. This monoclonal antibody greatly reduced the catalytic activity of mature PR3 toward extended peptide substrates. Using diverse techniques and multiple recombinant PR3 variants, we characterized its binding properties and found that MCPR3-7 preferentially bound to the so-called activation domain of the zymogen and changed the conformation of mature PR3, resulting in impaired catalysis and inactivation by α1-proteinase inhibitor (α1-antitrypsin). Noncovalent as well as covalent complexation between PR3 and α1-proteinase inhibitor was delayed in the presence of MCPR3-7, but cleavage of certain thioester and paranitroanilide substrates with small residues in the P1 position was not inhibited. We conclude that MCPR3-7 reduces PR3 activity by an allosteric mechanism affecting the S1' pocket and further prime side interactions with substrates. In addition, MCPR3-7 prevents binding of PR3 to cellular membranes. Inhibitory antibodies targeting the activation domain of PR3 could be exploited as highly selective inhibitors of PR3, scavengers, and clearers of the PR3 autoantigen in granulomatosis with polyangiitis.

Twenty-eight years with antineutrophil cytoplasmic antibodies (ANCA): how to test for ANCA - evidence-based immunology?

Wegener’s granulomatosis, microscopic polyangiitis, Churg-Strauss syndrome, and primary pauci-immune crescentic glomerulonephritis are associated with circulating antineutrophil cytoplasmic autoantibodies (ANCA) (collectively called ANCA-associated vasculitides, AAV). Two types of ANCA, one with a cytoplasmic fluorescence pattern (C-ANCA) and specificity for proteinase 3 (PR3-ANCA) and the other with a perinuclear pattern (P-ANCA) and specificity for myeloperoxidase (MPO-ANCA), account for this association and are highly specific markers for these vasculitides. AAV most often require therapy with cytotoxic and antiinflammatory agents, and hence a well-established diagnosis is mandatory to avoid unnecessary and risky treatment. The widespread use of ANCA screening in the past decade has resulted in the occurrence of greater numbers of false-positive results and has led to greater difficulty in test interpretation. Methods for ANCA detection have been standardized internationally in large multicentre studies and an international consensus statement on testing and reporting of ANCA has been pub lished (1999 and 2003). Despite these advances, problems with the extended use of ANCA testing in daily clinical practice remain. They may be summarized as follows: (1) the basic standards for ANCA testing are not uniformly met; (2) there is still controversy over the value of formalin fixation of neutrophils in differentiating P-ANCA from antinuclear antibodies (what is the place of this substrate in ANCA testing?); (3) the new generation of PR3-ANCA and MPO-ANCA ELISAs are more sensitive and specific than immunofluorescence testing (should ELISAs replace the immunofluorescence test?); and (4) should alternative methods for ANCA detection such as image analysis and/or multiplex immunoassays be used for screening? In this paper, we review these issues, identify areas of uncertainty, and provide practical guidelines where possible.