NETosis markers: Quest for specific, objective, and quantitative markers

AbstractMore than 10years have passed since the discovery of neutrophil extracellular traps (NETs) in 2004. NETs are extracellular web-like DNA decorated with antimicrobial proteins, which are released from activated neutrophils. The state of neutrophils with NET formation is called NETosis. It has been realized that NETosis includes suicidal NETosis and vital NETosis. The former state means cell death of neutrophils, whereas the latter state preserves living neutrophilic functions. Although both suicidal and vital NETosis play essential roles in elimination of microorganisms, excessive formation of NETs, especially the ones derived from suicidal NETosis, can harm the hosts. Therefore, the discovery of NETosis markers and development of evaluation methods are important. In this review, we compare the methods for evaluating NETosis, including immunocytological and immunohistological detection of co-localized neutrophil-derived proteins and extracellular DNA, and citrullinated histones, detection of NET remnants in fluid samples, and flow cytometric detection of cell-appendant NET components, with focus on the specificity, objectivity, and quantitativity. Since the gold standard marker of NETosis or method of NET detection has not been established yet, researchers should choose the most appropriate marker or method in each situation based on the knowledge of the respective virtues and faults

Novel process of intrathymic tumor-immune tolerance through CCR2-mediated recruitment of Sirpα + dendritic cells: A murine model

Immune surveillance system can detect more efficiently secretory tumor-specific antigens, which are superior as a target for cancer immunotherapy. On the contrary, immune tolerance can be induced in the thymus when a tumor antigen is massively secreted into circulation. Thus, the secretion of tumor-specific antigen may have contradictory roles in tumor immunity in a context-dependent manner. However, it remains elusive on the precise cellular mechanism of intrathymic immune tolerance against tumor antigens. We previously demonstrated that a minor thymic conventional dendritic cell (cDC) subset, CD8α -Sirpα + cDCs, but not the major subset, CD8α +Sirpα - cDCs can selectively capture blood-borne antigens and crucially contribute to the self-tolerance. In the present study, we further demonstrated that Sirpα + cDCs can capture a blood-borne antigen leaking inside the interlobular vascular-rich regions (IVRs). Blood-borne antigen selectively captured by Sirpα + cDCs can induce antigen-specific Treg generation or negative selection, depending on the immunogenicity of the presented antigen. Furthermore, CCR2 expression by thymic Sirpα + cDCs and abundant expression of its ligands, particularly, CCL2 by tumor-bearing mice prompted us to examine the function of thymic Sirpα + cDCs in tumor-bearing mice. Interestingly, tumor-bearing mice deposited CCL2 inside IVRs in the thymus. Moreover, tumor formation induced the accumulation of Sirpα + cDCs in IVRs under the control of CCR2-CCL2 axis and enhanced their capacity to take up antigens, resulting in the shift from Treg differentiation to negative selection. Finally, intrathymic negative selection similarly ensued in CCR2-competent mice once the tumor-specific antigen was secreted into bloodstream. Thus, we demonstrated that thymic Sirpα + cDCs crucially contribute to this novel process of intrathymic tumor immune tolerance. © 2012 Baba et al

Possible Implication of Fc γ

Leukocytes can “gnaw away” the plasma membrane of other cells. This phenomenon, called trogocytosis, occurs subsequent to cell-to-cell adhesion. Currently, two mechanisms of trogocytosis, adhesion molecule-mediated trogocytosis and Fcγ receptor-(FcγR-) mediated trogocytosis, have been identified. In our earlier study, we established an in vitro model of FcγR-mediated trogocytosis, namely, CD8 translocation model from T cells to neutrophils. By using this model, we demonstrated that the molecules transferred to neutrophils via FcγR-mediated trogocytosis were taken into the cytoplasm immediately. This result suggests that the chance of molecules transferred via FcγR-mediated trogocytosis to play a role on the cell surface could be time-limited. Thus, we consider the physiological role of FcγR-mediated trogocytosis as a means to remove antibodies (Abs) that bind with self-molecules rather than to extract molecules from other cells. This concept means that FcγR-mediated trogocytosis can be a defense mechanism to Ab-mediated autoimmune response. Moreover, the activity of FcγR-mediated trogocytosis was revealed to be parallel to the endocytotic activity of neutrophils, which was critically related to the susceptibility to systemic autoimmune diseases. The collective findings suggest that FcγR-mediated trogocytosis could physiologically play a role in removal of Abs bound to self-antigens and prevent autoimmune diseases

Prediction of response to remission induction therapy by gene expression profiling of peripheral blood in Japanese patients with microscopic polyangiitis

BackgroundMicroscopic polyangiitis (MPA), which is classified as an anti-neutrophil cytoplasmic antibody (ANCA)-associated small vessel vasculitis, is one of the most frequent primary vasculitides in Japan. We earlier nominated 16 genes (IRF7, IFIT1, IFIT5, OASL, CLC, GBP-1, PSMB9, HERC5, CCR1, CD36, MS4A4A, BIRC4BP, PLSCR1, DEFA1/DEFA3, DEFA4, and COL9A2) as predictors of response to remission induction therapy against MPA. The aim of this study is to determine the accuracy of prediction using these 16 predictors.MethodsThirty-nine MPA patients were selected randomly and retrospectively from the Japanese nationwide RemIT-JAV-RPGN cohort and enrolled in this study. Remission induction therapy was conducted according to the Guidelines of Treatment for ANCA-Associated Vasculitis published by the Ministry of Health, Labour, and Welfare of Japan. Response to remission induction therapy was predicted by profiling the altered expressions of the 16 predictors between the period before and 1 week after the beginning of treatment. Remission is defined as the absence of clinical manifestations of active vasculitis (Birmingham Vasculitis Activity Score 2003: 0 or 1 point). Persistent remission for 18 months is regarded as a “good response,” whereas no remission or relapse after remission is regarded as a “poor response.”Results“Poor” and “good” responses were predicted in 7 and 32 patients, respectively. Five out of 7 patients with “poor” prediction and 1 out of 32 patients with “good” prediction experienced relapse after remission. One out of 7 patients with “poor” prediction was not conducted to remission. Accordingly, the sensitivity and specificity to predict poor response was 85.7% (6/7) and 96.9% (31/32), respectively.ConclusionsResponse to remission induction therapy can be predicted by monitoring the altered expressions of the 16 predictors in the peripheral blood at an early point of treatment in MPA patients

Possible implication of disordered neutrophil extracellular traps in the pathogenesis of MPO-ANCA-associated vasculitis

Neutrophil extracellular traps (NETs) are characterized by the presence of extracellular DNA fibers studded with antimicrobial proteins, including myeloperoxidase (MPO). Although NETs play an important role in the innate immune system, the scattered extracellular enzymes, such as MPO, pose risks to the host. Therefore, NETs are strictly regulated by DNase I in the serum, which prevents them from persisting. Recent studies have demonstrated that dysregulation of NETs could be involved in the pathogenesis of autoimmune diseases, including systemic lupus erythematosus. In this review, we interpret the association of disordered NETs with autoimmune diseases, especially propylthiouracil-induced MPO-ANCA-associated vasculitis

Abundant neutrophil extracellular traps in thrombus of patient with microscopic polyangiitis

This is a case study of a patient diagnosed with microscopic polyangiitis (MPA) and complicated with deep vein thrombosis (DVT), who died of respiratory failure despite treatment. Autopsy revealed severe crescentic glomerulonephritis and massive alveolar hemorrhage. The thrombus contained abundant neutrophils. Although it is reported that patients with ANCA-associated vasculitis (AAV) have an increased risk of DVT, it remains elusive why they are prone to thrombosis. A recent study has demonstrated the presence of neutrophil extracellular traps (NETs), a newly recognized mode of neutrophil cell-death, in glomerular crescents of MPA patients. Interestingly, NETs were identified in the thrombus as well as in the glomerular crescents in the present case. When compared to other thrombi unrelated to MPA, the amount of NETs was significantly greater in the MPA patient. On the other hand, NETs are critically involved in thrombogenesis because histones within NETs can bind platelets and blood coagulants. Although this is important in regard to containment of microbes within NETs, excessive NETs could cause thrombosis. The collective findings suggest the possibility that thrombosis could be critically associated with MPA via NETs, and that NETs could be a therapeutic target in MPA patients

Human papillomavirus 16-positive uterine cervical squamous cell carcinoma with coinfection with human papillomavirus 34 has a lower incidence in lymph node metastasis than that without coinfection with human papillomavirus 34

Our earlier study demonstrated high prevalence of multiple human papillomavirus (HPV) infection in patients with invasive uterine cervical cancer, including squamous cell carcinoma (SCC). HPV 16 is the most predominant genotype related to SCC of the uterine cervix. The aim of this study was to reveal the biological significance of multiple HPV infection concerning the tumor progression of invasive uterine cervical SCC. In the present study, the effects of coinfection with genotypes other than HPV 16 on tumor growth and lymph node metastasis of invasive uterine cervical SCC with HPV 16 infection were examined. Although coinfection with most genotypes did not influence tumor progression, the clinical stage of patients coinfected with HPV 16 and HPV 34 was significantly lower than that of those without HPV 34 coinfection (p = 0.0038). Moreover, no patient coinfected with HPV 16 and HPV 34 manifested lymph node metastasis, but about half of the patient population without HPV 34 coinfection did (p = 0.0299). These findings suggested that coinfection with HPV 34 could prevent the tumor progression of invasive uterine cervical SCC with HPV 16 infection. Copyright (C) 2013 S. Karger AG, Base