Classification of clinical subtypes, patient survival, kidney prognosis, and relapse in patients with MPO-ANCA-associated vasculitis: a single-center experience

Rituximab induction and reinduction in granulomatosis with polyangiitis and microscopic polyangiitis: A retrospective multicenter study in Taiwan

OBJECTIVES

This study aimed to investigate the clinical outcomes of granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) under rituximab induction and reinduction therapy in Taiwan.

METHODS

We performed a retrospective study in patients with GPA or MPA receiving rituximab therapy from August 2008 to July 2020 in seven medical centers in Taiwan. The clinical characteristics and outcomes of these patients were analyzed.

RESULTS

In total, 53 patients (18 with GPA and 35 with MPA) were included. Kidney involvement (82.9% vs. 22.2%, p < .001) and initial creatinine (3.25 ± 2.37 vs. 1.07 ± 0.82, p < .001) were significantly higher in MPA. Within 24 weeks after the first course of rituximab, there were seven deaths (five due to infection and two due to active disease) in patients with MPA (7/35, 20%) compared to 0 in patients with GPA. Of 33 patients receiving rituximab for kidney involvement, 23 survived and were free from renal replacement therapy at 24 weeks. Their chronic kidney disease (CKD) stages improved in 2 but progressed in 7, while 24 had stable CKD stages. Death or end-stage renal disease (ESRD) was associated with infection and higher initial creatinine. Reinduction therapy for relapse was required in 18 (39.1%) of 46 survivors, which was associated with anti-proteinase 3 (PR3) positive (odds ratio 3.667, p = .049) and younger age with a cutoff of 49.4 (AUC = 0.679, p = .030, sensitivity = 66.67%, specificity = 75%).

CONCLUSION

Significant mortality occurred after rituximab induction, especially in patients with MPA. In survivors, age younger than 50 and anti-PR3 positive were associated with the risk of relapse requiring reinduction.

Interstital lung disease in ANCA vasculitis

Anti-neutrophil cytoplasmic antibodies (ANCA) vasculitides are immune-mediated disorders that primarily affect small blood vessels of the airway and kidneys. Lung involvement, one of the hallmarks of microscopic polyangiitis and granulomatosis with polyangiitis, is associated with increased mortality and morbidity. In recent years, several retrospective series and case reports have described the association of interstitial lung disease (ILD) and ANCA vasculitis, particularly those positive for ANCA specific for myeloperoxidase. In the majority of these patients pulmonary fibrosis occurs concurrently or predates the diagnosis of ANCA vasculitis. More importantly, these studies have shown that ILD has an adverse impact on the long-term prognosis of ANCA vasculitis. This review focuses on the main clinical and radiologic features of pulmonary fibrosis associated with anti-neutrophil cytoplasmic antibodies. Major histopathology features, prognosis and therapeutic options are summarized.

Dual myeloperoxidase-antineutrophil cytoplasmic antibody- and antiglomerular basement membrane antibody-positive cases associated with prior pulmonary fibrosis: a report of four cases

BACKGROUND

Both myeloperoxidase-associated antineutrophil cytoplasmic antibody (MPO-ANCA) and antiglomerular basement membrane antibody (anti-GBM Ab) positivity have been demonstrated in patients with rapidly progressive glomerulonephritis (RPGN), either with or without pulmonary hemorrhage; however, the implications of these antibodies in such patients have not yet been elucidated. The cases with dual positive antibodies were studied clinically, serologically, and pathologically, and the implications of antibodies are discussed here.

PATIENTS AND METHODS

Four patients with prior pulmonary fibrosis, who subsequently developed RPGN and pulmonary hemorrhage, were studied clinically, serologically, and pathologically. The clinical data were reviewed extensively and the dual positive antibodies were detected by enzyme-linked immunosorbent assays. Pathological studies were performed with a renal biopsy in one patient, a gastric biopsy in another patient, and autopsy materials in the remaining 2 patients.

RESULTS

All 4 patients had prior pulmonary fibrosis before the symptoms of RPGN when the dual positivity of MPO-ANCA and anti-GBM Ab was detected. Three cases were accompanied by pulmonary hemorrhage around the time of RPGN whereas the remaining case demonstrated pulmonary hemorrhage a few years later. Renal tissue specimens in 3 cases showed circumferential crescents and linear immunoglobulin G deposits along the glomerular capillary loops in glomeruli. Two autopsy specimens revealed vasculitis of the small arteries and arterioles of the kidney, and one of them showed similar vasculitic findings in both the gastrointestinal tract walls and the adipose tissues of the adrenal glands. Additionally, a case with pulmonary hemorrhage occurring after remission was associated with re-elevated MPO-ANCA levels but without anti-GBM Ab positivity. A gastric biopsy was unremarkable and non-contributory for the diagnosis, but this case showed vasculitic symptoms of peripheral neuritis and retinal hemorrhage. Taken together, all 4 cases demonstrated prior pulmonary fibrosis and dual positivity of MPO-ANCA as well as anti-GBM Abs at the time of RPGN, and were associated with either pulmonary hemorrhage or its occurrence thereafter.

CONCLUSION

Four cases that showed prior pulmonary fibrosis as well as subsequent RPGN and pulmonary hemorrhage were both MPO-ANCA- and anti-GBM Ab-positive at the time of RPGN. The glomeruli disclosed features compatible with anti-GBM Ab disease, but the clinical and pathological vasculitic manifestations, including prior pulmonary fibrosis that might be an early manifestation of ANCA disease, suggested the occurrence of MPO-ANCA-associated vasculitis. Furthermore, 1 case subsequently showed repetitive pulmonary hemorrhage with re-elevated MPO-ANCA positivity but without anti-GBM Ab positivity, and this event was possibly due to MPO-ANCA-associated alveolar capillaritis. As anti-GBM Ab disease is generally thought not to manifest the clinical and pathological features of vasculitis excluding the kidney, MPO-ANCA might be a key factor regarding the occurrence of this dual positive disease.