The involvement of NETs in ANCA-associated vasculitis

Neutrophil PPIF exacerbates lung ischemia-reperfusion injury after lung transplantation by promoting calcium overload-induced neutrophil extracellular traps formation

Lung ischemia-reperfusion (I/R) injury is the main risk factor for primary graft dysfunction and patient death after lung transplantation (LTx). It is widely accepted that the main pathological mechanism of lung I/R injury are calcium overload, oxygen free radical explosion and neutrophil-mediated damage, which leading to the lack of effective treatment options. The aim of this study was to further explore the mechanisms of lung I/R injury after LTx and to provide potential therapeutic strategies. Our bioinformatics analysis revealed that the neutrophil extracellular traps (NETs) formation was closely involved in lung I/R injury after LTx, which was accompanied by up-regulation of peptidylprolyl isomerase F (PPIF) and peptidyl arginine deiminase 4 (PADI4). We further established an orthotopic LTx mouse model to simulate lung I/R injury in vivo, and found that PPIF and PADI4 inhibitors effectively reduced neutrophil infiltration, NETs formation, inflammatory response, and lung I/R injury. In the neutrophil model induced by HL-60 cell line in vitro, we found that PPIF inhibitor cyclosporin A (Cys A) better alleviated calcium overload induced inflammatory response, reactive oxygen species content and NETs formation. Further study demonstrated that interfering with neutrophil PPIF protected mitochondrial function by alleviating store-operated calcium entry (SOCE) during calcium overload and played the above positive role. On this basis, we found that the reduction of calcium content in neutrophils was accompanied by the inhibition of calcineurin (CN) and nuclear factor of activated T cells (NFAT). In conclusion, our findings suggested that neutrophil PPIF could serve as a novel biomarker and potential therapeutic target of lung I/R injury after LTx, which provided new clues for its treatment by inhibiting calcium overload-induced NETs formation.

Rare Clinical Manifestation of Vasculitis

BACKGROUND

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitis usually affects small blood vessels and is characterized by the presence of circulating autoantibodies (c-ANCA or p-ANCA). The risk of cardiovascular events is threefold higher compared to general population, and cardiac manifestations include myocarditis, pericarditis, valvulitis, aortitis, or coronary arteritis. Coronary involvement is very rare, but it is a potentially life-threatening manifestation.

METHODS

We present an atypical cardiac scenario of p-ANCA vasculitis.

RESULTS

A 68-year-old woman with known p-ANCA vasculitis and stage 5 chronic kidney disease (CKD) on hemodialysis presented with dizziness accompanied by low blood pressure and chest pain. Electrocardiogram on arrival showed slightly ST-T changes, with negative cardiac biomarkers and no abnormalities in cardiac regional wall motion. Five hours after presentation, the patient repeated chest pain, accompanied by a drop in blood pressure and junctional escape rhythm. The highly sensitive cardiac troponin I (hs-cTnI) was raised at 560 ng/L. Coronary angiography showed coronary arteries without significant stenosis. The provocative test with intracoronary ergonovine demonstrated coronary vasospasm of the anterior descending artery accompanied by chest pain, with resolution after intracoronary nitroglycerin. Under amlodipine, nitrate, acetylsalicylic acid, statin and corticosteroids the patient did not experience the recurrence of angina.

CONCLUSIONS

This case illustrates coronary involvement, manifested as coronary spasm with favorable outcomes, in systemic vasculitis. The underlying mechanism is immune-mediated inflammation in vascular walls.

Clinical impact of ceruloplasmin levels at ANCA-associated vasculitis diagnosis

OBJECTIVES

Ceruloplasmin is an inhibitor of myeloperoxidase (MPO) activity that plays an important role in the pathophysiology of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). This study aimed to evaluate the prognostic impact of serum level of ceruloplasmin at diagnosis in patients with anti-MPO antibody-positive AAV.

METHODS

This retrospective monocentric study in Caen University Hospital involved all consecutive adult anti-MPO antibody-positive patients with microscopic polyangiitis or granulomatosis with polyangiitis, diagnosed between January 2010 and January 2022 with available serum sample at inclusion. Patients outcomes were analyzed from two subgroups constituted according to the median serum level of ceruloplasmin. The same analyses were then performed in anti-proteinase 3 (PR3) antibody-positive patients.

RESULTS

Within the 92 patients analyzed, 50 patients had anti-MPO antibodies with a median ceruloplasmin level of 0.44 [quartiles 1-3, 0.40-0.49] g/L and a median Birmingham Vasculitis Activity Score of 19 [14-22]. After a median follow-up period of 40 [22-86] months, 13 (26%) patients had died: 10 (40%) in the low ceruloplasmin group and 3 (12%) in the high ceruloplasmin group (p = 0.03), with a significantly worse survival rate in the low ceruloplasmin group (p = 0.021). No significant differences in relapse rate or renal failure was observed between the two groups. The same analyses performed in the group of AAV patients with anti-PR3 antibody did not show any differences.

CONCLUSION

In anti-MPO AAV patients, serum level of ceruloplasmin at diagnosis seems to be associated with a significant impact on survival.

Nets in fibrosis: Bridging innate immunity and tissue remodeling

Fibrosis, a complex pathological process characterized by excessive deposition of extracellular matrix components, leads to tissue scarring and dysfunction. Emerging evidence suggests that neutrophil extracellular traps (NETs), composed of DNA, histones, and antimicrobial proteins, significantly contribute to fibrotic diseases pathogenesis. This review summarizes the process of NETs production, molecular mechanisms, and related diseases, and outlines the cellular and molecular mechanisms associated with fibrosis. Subsequently, this review comprehensively summarizes the current understanding of the intricate interplay between NETs and fibrosis across various organs, including the lung, liver, kidney, skin, and heart. The mechanisms by which NETs contribute to fibrogenesis, including their ability to promote inflammation, induce epithelial-mesenchymal transition (EMT), activate fibroblasts, deposit extracellular matrix (ECM) components, and trigger TLR4 signaling were explored. This review aimed to provide insights into the complex relationship between NETs and fibrosis via a comprehensive analysis of existing reports, offering novel perspectives for future research and therapeutic interventions.

Neutrophil extracellular traps and their implications in airway inflammatory diseases

Neutrophil extracellular traps (NETs) are essential for immune defense and have been increasingly recognized for their role in infection and inflammation. In the context of airway inflammatory diseases, there is growing evidence suggesting the involvement and significance of NETs. This review aims to provide an overview of the formation mechanisms and components of NETs and their impact on various airway inflammatory diseases, including acute lung injury/ARDS, asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis. By understanding the role of NETs in airway inflammation, we can gain valuable insights into the underlying pathogenesis of these diseases and identify potential targets for future therapeutic strategies that either target NETs formation or modulate their harmful effects. Further research is warranted to elucidate the complex interactions between NETs and airway inflammation and to develop targeted therapies that can effectively mitigate their detrimental effects while preserving their beneficial functions in host defense.