Impact of interstitial lung disease on mortality in ANCA-associated vasculitis: A systematic literature review and meta-analysis

Presentation and progression of MPO-ANCA interstitial lung disease

The association between MPO-ANCA-associated vasculitis (AAV) and interstitial lung disease (ILD) has been well established. Pulmonary fibrosis may coexist with, follow, or even precede the diagnosis of AAV, and its presence adversely affects the prognosis. The optimal approach to investigating ANCA in patients with ILD remains a subject of ongoing debate. Here we aim to describe presentation and progression of MPO-ANCA ILD. We conducted a retrospective evaluation of a cohort of individuals diagnosed with MPO-ANCA ILD, with or without accompanying renal impairment, at the Immunology and Cell Therapy Unit, Careggi University Hospital, Florence, Italy, between June 2016 and June 2022. Clinical records, imaging studies, pathologic examinations, and laboratory test results were collected. Among the 14 patients identified with MPO-ANCA ILD, we observed a significant association between MPO-ANCA titers assessed at the time of ILD diagnosis and renal involvement. Renal impairment in these cases often manifested as subclinical or slowly progressive kidney damage. Interestingly, complement C3 deposits were consistently found in all renal biopsy specimens, thereby suggesting the potential for novel therapeutic targets in managing renal complications associated with MPO-ANCA ILD. The presentation of MPO-ANCA vasculitis as ILD can be the first and only clinical manifestation. MPO-ANCA levels at ILD diagnosis could warn on the progression to renal involvement in patients with MPO-ANCA ILD, hence caution is needed because renal disease can be subclinical or smoldering.

Interstitial Lung Disease and Anti-Neutrophil Cytoplasmic Antibody–Associated Vasculitis

Interstitial lung disease is a common complication of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). It is seen most commonly in microscopic polyangiitis owing to the pathogenic effect of myeloperoxidase in the lung. Oxidative stress, neutrophil elastase release, and expression of inflammatory proteins by neutrophil extracellular traps result in fibroblast proliferation and differentiation and therefore fibrosis. Usually, interstitial pneumonia pattern fibrosis is common and associated with poor survival. Treatment for patients with AAV and interstitial lung disease lacks evidence, and those with vasculitis are treated with immunosuppression, whereas those with progressive fibrosis may well benefit from antifibrotic therapy.

Long-term survival, causes of death, and prognostic factors for mortality in patients with microscopic polyangiitis and those with anti-neutrophil cytoplasmic antibody-positive interstitial lung disease: A single-center retrospective study

AIM

To elucidate the clinical features, long-term survival, and prognostic factors for mortality among patients with microscopic polyangiitis (MPA), including those with anti-neutrophil cytoplasmic antibody-positive interstitial lung disease (ILD) (ANCA-ILD), which could be a subset of its variant phenotype.

METHODS

We retrospectively included 76 consecutive patients between 2006 and 2014, diagnosed with MPA according to the European Medicines Agency algorithm using the Chapel Hill Consensus Conference definitions or ANCA-ILD. ILD was classified as usual interstitial pneumonia (UIP) or nonspecific interstitial pneumonia pattern using chest computed tomography.

RESULTS

The mean (standard deviation) age of the patients (female, 68%) was 69 (12) years. The median (interquartile range) follow-up period was 68 (33-95) months. Comorbid ILD and glomerulonephritis were observed in 44 (58%) (68% UIP) and 54 (71%) patients, respectively. Comorbid ILD was associated with low survival (P = .0563). There were 17 (39%) and 5 (16%) deaths in the ILD and non-ILD groups, respectively (P = .0404). In the ILD group, 6 and 5 of the deaths were attributed to infection and ILD progression, respectively. In the non-ILD group, 1 and 2 patients expired from subsequently developed ILD and aspiration pneumonia, respectively. Age ≥ 70 years (hazard ratio = 2.78; 95% confidential interval 1.15-6.70) and UIP (3.95; 1.60-9.77) were independent risk factors for mortality.

CONCLUSION

Age ≥ 70 years and ILD with a UIP pattern were associated with high mortality, owing to susceptibility to infection and ILD progression. A more effective and less toxic treatment is required for progressive ILD.

Elevated Level of Serum Interleukin-21 and Its Influence on Disease Activity in Anti-Neutrophil Cytoplasmic Antibodies Against Myeloperoxidase-Associated Vasculitis

Interleukin-21 (IL-21) has been shown to play an important role in the immune system. This study aimed to investigate the changes in the level of IL-21 in patients with anti-neutrophil cytoplasmic antibodies against myeloperoxidase (MPO-ANCA)-associated vasculitis (MPO-AAV), as well as explore its influence on disease activity and the potential mechanism. Flow cytometry was performed to detect the percentage of follicular helper T cells (Tfh) among CD4⁺T cells (Tfh%); the percentage of Tfh-expressing inducible costimulator (ICOS) among Tfh cells (ICOS⁺Tfh%); the percentage of Tfh-expressing programmed cell death protein 1 (PD-1) among Tfh cells (PD-1⁺Tfh%); and mean fluorescence intensity of Tfh-expressing ICOS or PD-1 in the peripheral blood. An enzyme-linked immunosorbent assay was used to measure the levels of serum IL-21 and MPO-ANCA. The Birmingham Vasculitis Activity Score was used to evaluate disease activity. Our results revealed that the level of IL-21 in the patient group was significantly higher than that in the healthy control group (1324.2 ± 125.3 pg/mL vs. 704.2 ± 41.1 pg/mL, P < 0.001), and it was an independent factor affecting the disease activity (P = 0.022). Thus, blocking the activity of IL-21 may represent a potential novel target for the future treatment of MPO-AAV.

Incidence and Patterns of Interstitial Lung Disease and Their Clinical Impact on Mortality in Patients with Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: Korean Single-Centre Observational Study

Objectives

This study investigated the frequency and patterns of interstitial lung disease (ILD) and their clinical effect on all-cause mortality during the follow-up period in patients with antineutrophil cytoplasmic antibody- (ANCA-) associated vasculitis (AAV) in Korea.

Methods

The medical records of 255 AAV patients with ILD were retrospectively reviewed. ILD and its patterns, the usual interstitial pneumonia (UIP) and non-UIP patterns, were confirmed using high-resolution computed tomography both at AAV diagnosis and during follow-up. Forced vital capacity (FVC) and diffusing capacity of the lung for carbon monoxide (DLCO) were also obtained.

Results

The median age was 65.0 years, and 34.9% were male. ILD occurred in 53 patients, among whom 49.1% developed ILD after AAV diagnosis. Among AAV subtypes, the frequencies of ILD were significantly higher in both patients with microscopic polyangiitis (MPA) and those with AAV having myeloperoxidase (MPO)-ANCA (or P-ANCA) compared to other subtypes. However, there was no statistical significance in AAV subtypes or FVC/DLCO ratio between patients with the UIP and non-UIP patterns. In particular, the cumulative patients' survival rate was lower in patients with AAV and ILD than in those without ILD.

Conclusions

ILD occurred in one-fifth of Korean patients with AAV in this study and was associated with MPA and MPO-ANCA (or P-ANCA). In addition, ILD significantly increased the rate of all-cause mortality in these patients with AAV. Therefore, we suggest the need for more attention and more frequent regular visit for patients with AAV and ILD regardless of the time of ILD occurrence.

Antineutrophil cytoplasmic antibody-associated interstitial lung disease: a review

Over the past three decades, an increasing number of publications have reported the association between interstitial lung disease (ILD) and anti-neutrophil cytoplasmic antibody (ANCA) or ANCA-associated vasculitis (AAV). With this increased awareness, we have reviewed the literature to date and provide an update in this narrative review. The vast majority of cases of ILD have been shown to be in the setting of positive anti-myeloperoxidase antibody and can be present in up to 45% of patients of microscopic polyangiitis, though cases of ILD associated with proteinase 3 ANCA have rarely been reported. Pulmonary fibrosis and ANCA positivity can occur with or without systemic involvement. The pathogenetic mechanisms establishing the relationship between ANCA and the development of pulmonary fibrosis remain unclear. Histologic and radiographic features of ANCA-ILD most commonly reveal usual interstitial pneumonia or non-specific interstitial pneumonia patterns, though other atypical features such as bronchiolitis have been described. ILD in the setting of AAV has been associated with worse outcomes, and thus early identification and treatment in these patients is appropriate. We advocate that ANCA antibody testing be performed as a baseline evaluation in patients presenting with idiopathic interstitial pneumonia. Suggested treatment of ANCA-ILD includes immunosuppression and/or antifibrotic agents, though supporting data and clinical trials to substantiate use of these therapies are needed.

ANCA-Associated Vasculitis in a Patient Presenting With Rapid Progressive Glomerulonephritis

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a rare disease distinguished by the presence of circulating ANCA along with inflammation and destruction of primarily small blood vessels. AAV includes granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Overall, AAV occurs more frequently in Caucasian populations with an approximate incidence of 20 per million per year in Europe and North America. This report presents a case of a 70-year-old female with a history of interstitial lung disease who was hospitalized due to markedly reduced renal function and eGFR within the range of end-stage renal disease on admission. The patient tested positive for perinuclear (p)-ANCA, also known as myeloperoxidase (MPO)-ANCA. The patient was subsequently started on hemodialysis and induction therapy of cyclophosphamide and methylprednisolone for glomerulonephritis secondary to p-ANCA vasculitis. The patient was discharged with improved renal function, and she was expected to follow up with nephrology for maintenance therapy to prevent future relapse. This report demonstrates a case of p-ANCA-positive glomerulonephritis treated with cyclophosphamide and methylprednisolone and discusses the current treatment guidelines for glomerulonephritis secondary to p-ANCA vasculitis.