RESUMEN

Myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) microscopic polyangiitis is a rare but life-threatening small vessel vasculitis in childhood that affects multiple systems. Emerging clinical evidence suggests a possible association between SARS-CoV-2 infection or multisystem inflammatory syndrome in children (MIS-C) as well as the futuredevelopment of autoimmune diseases. A 14-year-old boy with a diagnosis of MIS-C two years prior to presentation was admitted to our hospital due to edema and left lower limb joint pain along with concomitant upper surface petechia. The patient had a positive higher SARS-CoV-2 IgG than MIS-C diagnosis titers and MPO-ANCA-positive antibody titers. Kidney biopsy favored a pauci-immune crescentic glomerulonephritis. Restrictive lung disease with concomitant diffusion abnormalities was also observed. Pancreatitis and gastrointestinal wall edema were additional clinical manifestations. SARS-CoV-2 breakthrough infection and MIS-C could contribute to the onset of autoimmune vasculitis through various immunological mechanisms. Further research is still needed to elucidate the role of SARS-CoV-2 in the pathophysiology of newly diagnosed autoimmune vasculitis.

RESUMEN

A 75-year-old man presented with MPO-ANCA-positive rapidly progressive glomerulonephritis after COVID-19 vaccination during the treatment of plaque psoriasis vulgaris with bimekizumab. Bimekizumab, an anti-IL17 monoclonal antibody, was regularly administered to control the activity of plaque psoriasis. After receiving the sixth COVID-19 vaccine, his kidney function rapidly declined over the course of weeks. Urinalysis showed microscopic hematuria and proteinuria with deformed red blood cells and granular cast. The immunology test was positive for MPO-ANCA. The patient was clinically diagnosed with MPO-ANCA-associated glomerulonephritis. As the patient lost his appetite and developed lower extremity edema with low eGFR (< 15 ml/min/1.73m2) on admission day, hemodialysis induction was initiated along with methylprednisolone pulse, followed by oral prednisolone. The kidney function and urine volume were improved in response to immunosuppressive therapy, and withdrawal from hemodialysis was considered. However, the patient developed a catheter infection due to methicillin-sensitive Staphylococcus aureus 2 weeks after the initial prednisolone treatment, causing a decline in kidney function. Antibiotics treatment for the catheter infection was effective, but kidney function remained low, resulting in dependence on regular hemodialysis. COVID-19 vaccination provides significant improvement in overall prognosis; however, there have been reports of kidney function decline and exacerbation of hematuria in patients with IgA nephropathy following vaccination. The incidence of MPO-ANCA-associated glomerulonephritis after COVID-19 vaccination was rare. Data accumulation is warranted to understand the risk factors for secondary MPO-ANCA glomerulonephritis after COVID-19 vaccination. Regular monitoring of urinalysis and kidney function after COVID-19 vaccination is recommended in patients with psoriasis vulgaris treated with IL17 monoclonal antibodies.

RESUMEN

To explore the expression patterns and potential roles of mRNAs in exosomes from patients with myeloperoxidase-specific anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (MPO-AAV). Plasma exosomes were isolated from MPO-AAV patients and healthy controls (HCs) to screen for differential mRNA expression via exosomal mRNA sequencing. The differentially expressed mRNAs in exosomes from the 2 groups were comparatively explored by bioinformatics analysis. The six most differentially expressed mRNAs were selected and validated in larger groups of MPO-AAV patients and HCs by real-time quantitative polymerase chain reaction (RT‒qPCR). The relationships between these selected mRNAs and patient characteristics were statistically analyzed. Compared with HCs, a total of 1077 mRNAs in exosomes from MPO-AAV patients were found to be significantly upregulated, including DEPDC1B and TPST1, while NSUN4 and AK4 were significantly downregulated. Statistical analysis did not reveal any correlation between the six selected mRNAs and clinical indicators, including disease activity. GO enrichment analysis revealed that these differentially expressed genes participate in various enzyme activities, protein synthesis, etc. KEGG pathway analysis revealed that metabolic pathways, cell adhesion molecules, epithelial signaling, and mitogen-activated protein kinase (MAPK) signaling pathways were significantly enriched in the exosomal mRNAs. There were significant differences in the expression of exosomal mRNAs between MPO-AAV patients and HCs, which may be related to the occurrence and development of MPO-AAV. These findings provide clues for further investigations of MPO-AAV pathogenesis and the identification of new potential therapeutic targets.

Asunto(s)

Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos , Exosomas , Perfilación de la Expresión Génica , Peroxidasa , ARN Mensajero , Humanos , Exosomas/genética , Exosomas/metabolismo , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/genética , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/sangre , Femenino , Masculino , ARN Mensajero/genética , Peroxidasa/genética , Persona de Mediana Edad , Anciano , Adulto , Biología Computacional , Estudios de Casos y Controles , Transcriptoma

RESUMEN

Microscopic polyangiitis (MPA) is a rare autoimmune disease characterized by the inflammation and necrosis of small vessels, primarily affecting kidneys and lungs. It is classified as an antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) due to the presence of ANCA. MPA can manifest as diffuse alveolar hemorrhage (DAH) and rapidly progressive glomerulonephritis. In contrast, rheumatoid arthritis (RA) is an inflammatory disease that mainly targets the synovial joints. The coexistence of these two conditions presents significant diagnostic challenges, highlighting the need for further research and understanding. We report a case of a 58-year-old male with a past medical history of RA, chronic bronchitis, tobacco use, and recent Legionella pneumonia who presented with acute dyspnea. The patient was intubated for acute hypoxemic respiratory failure. Laboratory workup revealed anemia, hyponatremia, and acute kidney injury. Urinalysis showed hematuria and proteinuria. A CT scan of the chest exhibited bilateral extensive patchy infiltrates. He was transfused with one packed red blood cell (PRBC) unit. Hemoglobin decreased below 6 g/dL after transfusion. A bronchoscopy revealed erythema throughout the tracheobronchial tree, and blood on bronchial alveolar lavage suggested DAH. High-dose steroids were started. Subsequent laboratory results were positive for rheumatoid factor (RF), perinuclear ANCA (p-ANCA), anti-myeloperoxidase (anti-MPO), and antinuclear antibody (ANA). The kidney biopsy demonstrated focal crescentic necrotizing glomerulonephritis pauci-immune type, confirming MPA. RA pathogenesis involves immune dysregulation and activation of various cells, leading to the release of cytokines. Antibodies such as RF and anti-cyclic citrullinated peptide (anti-CCP) can be detected up to 10 years before the clinical manifestation of RA. Recent studies have revealed a predominance of MPA in AAV while coexisting with RA. The underlying mechanism of its occurrence remains unclear. Our patient had recurrent respiratory symptoms and renal dysfunction before hospitalization. MPA-RA overlap syndrome is potentially treatable and clinicians should maintain a high index of suspicion when encountering patients with preexisting RA. Timely initiation of immunosuppressive therapy at early stages is essential to prevent renal and pulmonary complications. ANCA serology should be assessed in these cases.

RESUMEN

An underestimated side effect of rituximab is late-onset neutropenia (R-LON), which often resolves spontaneously and rarely results in a severe infection. We herein report a case of febrile neutropenia due to R-LON in a 91-year-old woman with renal failure who was treated with rituximab to induce remission of MPO-ANCA-associated vasculitis. Fifty-four days after the last rituximab administration, the patient was hospitalized for febrile neutropenia due to R-LON, which improved with granulocyte colony-stimulating factor and antibiotics. Although R-LON may resolve spontaneously and remain unnoticed, it can cause severe infections in the elderly and patients with renal failure.

RESUMEN

Disease manifestations of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), a small vessel vasculitis with multisystemic effects, include respiratory, renal, nervous, gastrointestinal, and skin implications. Muscle weakness and inflammatory myopathy are rare manifestations of AAV. We report the case of a 77-year-old female with a medical history of hypothyroidism and osteoarthritis who presented with a two-month history of worsening muscle weakness (mainly proximal). She endorsed dysphagia, a 40-lb unintentional weight loss, and persistent sinusitis with middle ear effusions, requiring bilateral tympanostomy. The physical examination was notable for 2/5 muscle strength in her hip flexors and extensors, with 4/5 strength in other extremities. Lower extremity MRI showed diffuse intramuscular edema between fat planes and intramuscular septal regions. Erythrocyte sedimentation rate (70 mm/hr), C-reactive protein (141 mg/L), creatine kinase (690 U/L), and anti-myeloperoxidase (MPO) antibodies (>999 AU/mL) were elevated. A thigh biopsy revealed fibrinoid necrosis of small intramuscular arteries, confluent circumferential granulomatous vessel wall inflammation, and associated mild chronic inflammation, including occasional eosinophils and a few plasma cells. She was diagnosed with MPO-positive AAV. The patient was started on high-dose steroids (prednisone), with a taper on a disease-modifying agent, azathioprine, with significant improvement in symptoms over the next four months and complete resolution at 16-month follow-up. This patient's clinical presentation of predominant lower extremity weakness due to inflammatory myositis is an unusual manifestation of AAV. Clinicians should keep a broad differential diagnosis and consider the possibility of AAV, especially in cases of muscle weakness presenting as inflammatory myositis, in the absence of other clinical manifestations of systemic vasculitis or specific myositis serologies.

RESUMEN

A 76-year-old woman was admitted with progressive renal function decline. A kidney biopsy was performed because of myeloperoxidase anti-neutrophil cytoplasmic antibody (ANCA; 333 IU/mL), proteinuria (1.21 g/d), and urinary erythrocyte sediment (10-19/high-power field). Renal-limited ANCA-positive vasculitis with pauci-immune necrotizing crescentic glomerulonephritis (ANCA-associated vasculitis, AAV) was diagnosed. Glucocorticoid therapy was started, and the patient responded well. About 1 year later, avacopan treatment was started and glucocorticoid therapy was discontinued. Avacopan did not normalize ANCA levels and did not make urinary findings negative. However, further progression of renal function decline is prevented. Factors attributed to the development of AAV in this case were investigated; AAV developed after the second dose of the COVID-19 vaccine and ANCA levels re-elevated after the fifth dose. This suggests that the COVID-19 vaccine may have contributed to the development of AAV in this elderly patient. Avacopan monotherapy has been shown to be effective as maintenance therapy to control the progression of renal failure although not sufficient for complete remission of AAV.

RESUMEN

As vaccinations against the SARS-CoV-2 virus have become a crucial tool in controlling the spread of the disease, reports of rare health complications have emerged, including new-onset antineutrophil cytoplasmic autoantibodies (ANCA)-associated vasculitis (AAV). We systematically reviewed new-onset AAV following COVID-19 vaccination case reports and case series published in three databases before January 2024 following PRISMA guidelines to understand the characteristics of possible causal relationships or coincidences. In total, 404 articles were screened respectively by title, abstracts, and full-texts. Thirty-four papers fulfilled the inclusion criteria and have been analyzed, covering 44 patients with new-onset AAV after COVID-19 vaccination with no prior history of COVID-19 infection. Data regarding patients' metrics, comorbidities, vaccination characteristics, symptoms, diagnostics, treatment, and outcomes were investigated and summarized. The cohort consisted predominantly of females. AAV diagnosis was confirmed via biopsy, with renal dysfunction as a prevailing manifestation. In most cases, the first symptoms of AAV developed after the second dose; moreover, Pfizer-BioNTech was the most frequently administered vaccine among the analyzed cohort. Primary treatment involved glucocorticoid therapy, with a mostly favourable response. This systematic review aims to raise awareness among clinicians in the field regarding this rare but possible complication, to promote the prompt recognition and diagnosis of de novo ANCA-positive small-vessel vasculitis in timely association with SARS-CoV-2 vaccination.

RESUMEN

Microscopic polyangiitis (MPA) is predominantly characterized by rapidly progressive glomerulonephritis (RPGN) associated with myeloperoxidase anti-neutrophil cytoplasmic antibodies (MPO-ANCA). Nonetheless, up to 30% of cases of ANCA-associated vasculitis (AAV) may exhibit a more indolent progression toward renal failure, an aspect less frequently discussed and understood in medical literature. This study seeks to clarify the clinical and pathological distinctions between the slowly and rapidly progressive forms of MPA, thereby enhancing understanding of their distinct pathogeneses and treatment responses. We conducted a comparative analysis of two patients diagnosed with MPA under the 2022 American College of Rheumatology/the European Alliance of Associations for Rheumatology (ACR/EULAR) classification. Evaluations included laboratory tests such as serum creatinine levels, serology for MPO-ANCA, and renal biopsies. Patient 1 exhibited a mere 1.07% decrease in estimated glomerular filtration rate (eGFR) over 6 months, significantly below the RPGN threshold, and demonstrated sclerotic glomerular pathology without active inflammation. This patient also showed lower levels of MPO-ANCA, Birmingham Vasculitis Activity Score (BVAS), and C-reactive protein. Conversely, Patient 2 experienced an 89.9% reduction in eGFR over the same timeframe, accompanied by acute systemic inflammation. The comparative clinical analysis of these cases illuminates clear differences in disease activity. Slowly progressive MPA is marked by lesser disease activity that fosters chronic inflammation, leading to a more gradual decline in renal function. Early diagnosis, facilitated by initial measurements of MPO-ANCA, can enhance disease management and improve patient outcomes.

RESUMEN

Antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (GN) is an immune-mediated kidney disease characterized by the inflammation of small blood vessels in the kidney, leading to renal impairment and potentially irreversible damage. Concerns have been raised over the reports of myeloperoxidase/perinuclear (MPO/p) ANCA GN following the coronavirus disease 2019 (COVID-19) vaccination. Our study provides a comprehensive insight into perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCA) GN after COVID-19 vaccination. We conducted a comprehensive literature search on PubMed, Cochrane Library, and EMBASE using the Medical Subject Headings (MeSH) terms related to "covid-19 vaccine," "glomerulonephritis," "p-ANCA," and "MPO-ANCA" up to March 5, 2024, to include cases of p-ANCA-associated GN following COVID-19 vaccination. Of the 4,102 articles, we included 29, reporting 35 patients demonstrating COVID-19 vaccine-induced p-ANCA GN, with 23 (65.7%) females and a median age of 69 years (mean ± SD = 63.22 ± 16). Twenty-six (74.28%) patients received the mRNA vaccine (Pfizer = 19, Moderna = 7). Seventeen (48.57%) patients presented with p-ANCA GN after the second dose of the COVID-19 vaccine, with a median gap of 19 days (1-84 days). Constitutional symptoms (54.28%) and acute kidney injury (42.85%) were the most reported initial presentations, and elevated serum creatinine (mean peak serum creatinine = 4.98 ± 5.02 mg/dL), hematuria, and proteinuria were the laboratory findings. MPO/p-ANCA was positive in 31 (88.6%) patients. All patients underwent renal biopsy, and crescentic GN was the most common finding among 27 (77.14%) patients. Management of p-ANCA GN included steroids in 30 (85.71%) patients, followed by rituximab (28.57%), and plasmapheresis (22.86%). Most patients responded well to treatment, with complete remission in 29 (82.86%) and relapse in four (11.42%) patients. Two patients did not achieve remission and became dialysis dependent. ANCA-associated GN is a rare and life-threatening complication of the COVID-19 vaccine, necessitating urgent evaluation and management. COVID-19 vaccine-induced p-ANCA GN should be included in the differential diagnoses of patients presenting with kidney injury after vaccination.

RESUMEN

Avacopan, an orally administered C5a receptor antagonist, is effective in microscopic polyangiitis via the inhibition of neutrophil priming induced by C5a. However, the exact effect of avacopan on the production of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) is yet to be clearly established. This report presents a microscopic polyangiitis patient without major organ damage where high levels of MPO-ANCA persisted with high-dose steroid therapy and azathioprine, but the addition of avacopan led to a reduction in MPO-ANCA titres. The present case implies that avacopan-mediated inhibition of C5a may lead to a reduction in MPO-ANCA levels, thereby potentially ameliorating the pathophysiology of ANCA-associated vasculitis. Nevertheless, the impact of avacopan on MPO-ANCA production cannot be asserted solely based on this report; therefore, further examination is necessary through subgroup analysis using data from larger-scale studies.

Asunto(s)

Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos , Anticuerpos Anticitoplasma de Neutrófilos , Peroxidasa , Humanos , Anticuerpos Anticitoplasma de Neutrófilos/sangre , Anticuerpos Anticitoplasma de Neutrófilos/inmunología , Peroxidasa/inmunología , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/tratamiento farmacológico , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/diagnóstico , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/complicaciones , Resultado del Tratamiento , Masculino , Femenino , Inmunosupresores/uso terapéutico , Anciano , Poliangitis Microscópica/tratamiento farmacológico , Poliangitis Microscópica/inmunología , Poliangitis Microscópica/diagnóstico , Poliangitis Microscópica/complicaciones , Azatioprina/uso terapéutico , Azatioprina/administración & dosificación , Compuestos de Anilina , Ácidos Nipecóticos

RESUMEN

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.

RESUMEN

Myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) vasculitis manifests as a neutrophilic inflammation impacting small vessels across multiple organs, notably the lungs, kidneys, and skin. We present a unique case of MPO-ANCA vasculitis in a 77-year-old female characterized by glomerulosclerosis, rapidly progressive renal failure necessitating hemodialysis (HD), bullous skin lesions, and hypoxic respiratory failure. The patient, who had a history of type 2 diabetes, presented with progressive dyspnea, hypoxia, and acute kidney injury superimposed on chronic kidney disease (CKD) progressing to renal failure requiring dialysis. A renal biopsy highlighted globally sclerosed glomeruli, interstitial fibrosis, and tubular atrophy, along with increased immunoglobulin M (IgM) deposits on immunofluorescence, differing from typical findings. Prompt initiation of prednisone led to respiratory and cutaneous improvement; however, despite therapy, extensive renal damage led to the permanent requirement of dialysis.  MPO vasculitis primarily targets small vessels, frequently affecting kidneys, with only a subset of patients progressing rapidly to end-stage renal failure necessitating HD, as observed in our case. Contrary to classical histopathological patterns, our patient exhibited augmented IgM deposits. Left untreated, MPO vasculitis with renal involvement poses a mortality risk of up to 90%, underscoring the significance of prompt detection and corticosteroid intervention to avert renal failure and improve patient outcomes. Early recognition and timely treatment are pivotal in mitigating the dire consequences of this condition, emphasizing the importance of considering MPO vasculitis in patients with rapidly deteriorating renal function.

RESUMEN

Although mRNA vaccines for COVID-19 are highly beneficial and are recommended for patients with kidney disease, adverse reactions in some patients after vaccination have been problematic. Various vasculitis and renal disorders have been reported after vaccination; however, a causal relationship has not yet been identified. In this report, we describe a case of rapidly progressive glomerulonephritis that developed after SARS-CoV-2 vaccination, in which both anti-glomerular basement membrane (anti-GBM) and myeloperoxidase antineutrophil cytoplasmic antibodies (MPO-ANCA) were present. The patient's renal biopsy showed that of the 48 glomeruli in total, four showed global sclerosis and none showed segmental sclerosis. The biopsy showed 11 cellular glomerular crescents and 5 fibrocellular glomerular crescents. Renal function improved with steroids, rituximab, and plasma exchange. Approximately 9 months later, MPO-ANCA was again elevated, and the pulmonary lesions worsened, again requiring multidisciplinary treatment. This case suggests that caution should be exercised in the development of double-positive disease after vaccination, and that long-term observation may be necessary because of the possibility of relapse.

Asunto(s)

Autoanticuerpos , COVID-19 , Glomerulonefritis , Nefritis , Humanos , Anticuerpos Anticitoplasma de Neutrófilos , Vacunas contra la COVID-19/efectos adversos , SARS-CoV-2 , Estudios de Seguimiento , Esclerosis/patología , COVID-19/complicaciones , Membrana Basal Glomerular/patología , Nefritis/complicaciones , Enfermedad Crónica , Peroxidasa , Recurrencia , Vacunación/efectos adversos

RESUMEN

Subarachnoid haemorrhage (SAH) is a quite rare but serious central nervous system complication of eosinophilic granulomatosis with polyangiitis (EGPA). We report a case of myeloperoxidase antineutrophil cytoplasmic antibody-positive EGPA in which SAH developed during glucocorticoid induction pulse therapy for skin purpura, peripheral neuropathy, and rapidly progressive glomerulonephritis. In addition to high-dose glucocorticoid and intravenous cyclophosphamide, we administered mepolizumab, a humanised anti-interleukin-5 monoclonal antibody, and this resulted in remission of the SAH. Although the pathogenesis of SAH in EGPA is not fully understood, both necrotising vasculitis and eosinophilic inflammation are thought to be involved. In addition to prompt intensive immunosuppressive therapy, mepolizumab should be considered for SAH associated with EGPA.

Asunto(s)

Anticuerpos Anticitoplasma de Neutrófilos , Anticuerpos Monoclonales Humanizados , Ciclofosfamida , Glucocorticoides , Inmunosupresores , Hemorragia Subaracnoidea , Humanos , Ciclofosfamida/uso terapéutico , Ciclofosfamida/administración & dosificación , Hemorragia Subaracnoidea/etiología , Hemorragia Subaracnoidea/diagnóstico , Hemorragia Subaracnoidea/complicaciones , Hemorragia Subaracnoidea/tratamiento farmacológico , Glucocorticoides/uso terapéutico , Glucocorticoides/administración & dosificación , Anticuerpos Monoclonales Humanizados/uso terapéutico , Anticuerpos Monoclonales Humanizados/administración & dosificación , Anticuerpos Anticitoplasma de Neutrófilos/inmunología , Resultado del Tratamiento , Inmunosupresores/uso terapéutico , Inmunosupresores/administración & dosificación , Síndrome de Churg-Strauss/diagnóstico , Síndrome de Churg-Strauss/complicaciones , Síndrome de Churg-Strauss/tratamiento farmacológico , Peroxidasa/inmunología , Granulomatosis con Poliangitis/tratamiento farmacológico , Granulomatosis con Poliangitis/diagnóstico , Granulomatosis con Poliangitis/complicaciones , Masculino , Quimioterapia Combinada , Persona de Mediana Edad , Femenino

RESUMEN

Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is a systemic autoimmune disease characterized by necrotizing inflammation of small blood vessels. Glucocorticoids (GC) in combination with rituximab or cyclophosphamide can reduce AAV-related mortality and rescue renal function. However, several side effects associated with these agents, including GC toxicity, are concerning. Avacopan, an inhibitor of the C5a receptor, is now available for AAV treatment and is expected to mitigate GC toxicity. We present a case of myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA)-positive microscopic polyangiitis (MPA) with rapidly progressive glomerulonephritis treated with an early switch from GC to avacopan in combination with rituximab during induction therapy. Over a 6-month treatment period, clinical remission was achieved and maintained without infection or elevated liver enzyme levels. Efficacy and safety data regarding avacopan for AAV induction therapy remain limited. Therefore, more case reports are required to clarify the role of avacopan in AAV induction and maintenance therapy. Since the MPO-ANCA titer remained elevated despite the clinical remission of AAV in this case, the ANCA titer may not necessarily be a reliable biomarker for predicting AAV relapse when avacopan is applied as an induction therapy for AAV.

RESUMEN

BACKGROUND: Bruton's tyrosine kinase (Btk) is an enzyme expressed in leukocytes other than T lymphocytes and plasma cells and involved in B-cell receptor- and Fcγ receptor (FcγR)-mediated signal transduction. Btk inhibitors potentially suppress autoantibody production due to the expected inhibitory ability of B lymphocyte differentiation into antibody-producing plasma cells and reduce FcγR-mediated neutrophil activation, including the release of neutrophil extracellular traps (NETs). Microscopic polyangiitis (MPA) is a systemic small-vessel vasculitis characterized by the pathogenic autoantibody, antineutrophil cytoplasmic antibody (ANCA) that reacts with myeloperoxidase (MPO). MPO and MPO-ANCA immune complex (IC)-induced FcγR-mediated NETs are critically involved in MPA pathogenesis. This study aimed to demonstrate the therapeutic efficacy of the Btk inhibitor tirabrutinib on MPA. METHODS: Various doses of tirabrutinib or vehicle were orally administered to Sprague-Dawley rats daily. Four weeks later, the number of peripheral B lymphocytes was counted, and Btk phosphorylation in B lymphocytes was evaluated by flow cytometry. Human peripheral blood neutrophils were stimulated by MPO and anti-MPO antibody ICs (MPO and anti-MPO-ICs), and Btk and its downstream Vav phosphorylation were assessed by western blotting. The effects of tirabrutinib on MPO and anti-MPO-IC-induced NET formation were examined in vitro. Wistar Kyoto rats were immunized with human MPO to induce experimental MPA and given drug-free or tirabrutinib-containing feed (0.0037% or 0.012%) from day 0 or 28. All rats were euthanized on day 42 for serological and histological evaluation. RESULTS: Tirabrutinib inhibited Btk phosphorylation without decreasing B lymphocytes in vivo. Neutrophil Btk and Vav were phosphorylated when stimulated with MPO and anti-MPO-ICs. Tirabrutinib suppressed MPO and anti-MPO-IC-induced NET formation in vitro and ameliorated experimental MPA in a dose-dependent manner in vivo. Although MPO-ANCA production was not affected, NET-forming neutrophils in the blood were significantly reduced by tirabrutinib. CONCLUSIONS: The Btk inhibitor tirabrutinib suppressed MPO and anti-MPO-IC-induced NET formation in vitro and ameliorated experimental MPA by reducing NET-forming neutrophils but not decreasing MPO-ANCA titer in vivo. This study suggests that Btk is a possible therapeutic target in MPA.

Asunto(s)

Poliangitis Microscópica , Humanos , Ratas , Animales , Anticuerpos Anticitoplasma de Neutrófilos , Agammaglobulinemia Tirosina Quinasa , Receptores de IgG , Ratas Sprague-Dawley , Autoanticuerpos , Ratas Endogámicas WKY , Peroxidasa

RESUMEN

Proteinase 3 (PR3) anti-neutrophil cytoplasmic antibodies (ANCA) and anti-double-stranded DNA (anti-dsDNA) antibodies have been associated with a variety of nephritic diseases, most recognizably granulomatosis with polyangiitis and systemic lupus erythematosus (SLE) glomerulonephritis, respectively. We report the first clinical case of positive PR3 and dsDNA in a patient with renal Immunoglobin light chain (AL) amyloidosis. A 75-year-old man presented to the hospital with chronic fatigue, weight loss, and a recent diagnosis of left ventricular infiltrative cardiomyopathy secondary to AL amyloidosis. Autoimmune serology was significant for PR3-ANCA and anti-dsDNA antibodies. A renal biopsy confirmed AL amyloidosis with diffuse Congo red stain. This case report is the first of its kind, showing atypical antibody presentation in the setting of amyloidosis.

RESUMEN

BACKGROUND: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a systemic autoimmune disease characterized by mononuclear cell infiltration and small and medium-sized blood vessel destruction leading to renal failure. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been shown to have the potential to induce the presentation or exacerbation of autoimmune disease. This report describes the clinical features of a case of newly diagnosed ANCA-associated vasculitis after COVID-19 Infection. CASE PRESENTATION: During the COVID-19 pandemic, a 67- year-old female Japanese was undergoing treatment for interstitial pneumonia, diabetes mellitus, and hypertension at her local doctor. About 2 months ago, she was diagnosed with COVID-19 and went to a hotel for treatment, and her condition improved. But a month later, after her COVID-19 infection, she presented with a fever and cough and visited Yodogawa Christian Hospital in Osaka, Japan. The reverse transcription-polymerase chain reaction was negative. She underwent extensive radiological and laboratory investigations. Serologies revealed a high perinuclear-ANCA titer with a specific anti-myeloperoxidase antibody titer of 31.7 units/mL. We suspected ANCA-associated vasculitis and performed a renal biopsy. Renal biopsy showed evidence of crescentic glomerulonephritis, which was consistent with ANCA-associated vasculitis. The patient was referred to the Department of Rheumatology and Clinical Immunology for steroid pulse and cyclophosphamide treatment. CONCLUSIONS: Delayed screening may lead to progression of the autoimmune disease, so prompt diagnosis is necessary. In this case, we could make an immediate diagnosis and refer the patient to the Department of Rheumatology and Clinical Immunology.

Asunto(s)

Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos , Enfermedades Autoinmunes , COVID-19 , Femenino , Humanos , Anciano , SARS-CoV-2 , Anticuerpos Anticitoplasma de Neutrófilos , Pandemias , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/complicaciones , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/diagnóstico

RESUMEN

An eight-year-old girl was admitted with vomiting, gross hematuria, and progressive renal dysfunction. A renal biopsy revealed endocapillary proliferative glomerulopathy and crescent formation. Immunofluorescence staining revealed diffuse granular deposits of IgG and C3. Post-streptococcal acute glomerulonephritis (PSAGN) was suspected, based on the elevated anti-streptolysin O levels, decreased serum C3 concentrations, and histologic findings. The myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) test was positive, and the young patient gradually developed palisaded neutrophilic and granulomatous dermatitis (PNGD), orbital and paranasal sinus granulomatous neoplasms, along with intermittent nose, head, and orbital pain. Finally, she was diagnosed with the rare MPO-ANCA-associated granulomatosis with polyangiitis (GPA) superimposed on PSAGN. The patient was treated with aggressive renal replacement therapy, methylprednisolone pulse therapy, and intravenous pulse cyclophosphamide; her renal function normalized, and her pain symptoms improved.