SEARCH RESULTS FOR: Granulomatosis-with-Polyangiitis-Pathogenesis

Granulomatosis with Polyangiitis Pathogenesis

Granulomatosis with polyangiitis: Pathogenesis Author: Oswald Chen Reviewers: Ben Campbell *Liam Martin * MD at time of publication Drugs Thiol- and hydrazine-containing medications (e.g., hydralazine, propylthiouracil, allopurinol) Environmental exposures Silica dust, cigarette smoke, infections (Staphylococcus aureus) Genetic factors Alpha-1 antitrypsin deficiency, proteinase 3 gene mutation ↑ Production of cytokines and antineutrophil cytoplasmic antibodies (ANCAs) (mechanism unknown) Cytokines bind to endothelial cells (that line blood vessels) and neutrophils, priming them Proteinase 3 (PR3), an enzyme that degrades extracellular matrix proteins, migrates from neutrophil granules to neutrophil cell surface Circulating ANCAs bind to PR3 on neutrophils PR3 stimulates maturation of dendritic cells in lungs Dendritic cells present antigen (PR3) to naïve CD4+ T cells in peripheral lymph nodes T cells differentiate into type 1 and type 17 helper T cells (Th1 and Th17 cells) Th1 and Th17 cells secrete cytokines (interferon γ (INF-γ) and tumor necrosis factor α (TNF-α)) in lungs Secreted cytokines trigger macrophage maturation Formation of granulomas (giant cells with central necrosis surrounded by plasma cells, lymphocytes, and dendritic cells) primarily in lungs and upper airways ANCA-activated neutrophils release proinflammatory cytokines, attracting more neutrophils to endothelium (blood vessel wall) ANCA-activated neutrophils undergo firm adhesion to endothelium ANCAs stimulate ↑ secretion of proteolytic enzymes and reactive oxygen species from neutrophils Endothelial damage and tissue injury Granulomatosis with polyangiitis (GPA) ANCA-associated vasculitis affecting medium and small-sized arteries, associated with necrotizing granulomas Constitutional symptoms with involvement of multiple organ systems (see slide on clinical findings) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published December 4, 2022 on www.thecalgaryguide.com Granulomatosis with polyangiitis: Clinical findings Inflammation-mediated endothelial damage and granuloma formation (see slide on pathogenesis) Granulomatosis with polyangiitis (GPA) Author: Oswald Chen Reviewers: Ben Campbell *Liam Martin * MD at time of publication ANCA-associated vasculitis affecting medium and small-sized arteries, associated with necrotizing granulomas Constitutional symptoms Fever, unintentional weight loss, night sweats, arthralgias Skin involvement Inflammation of cutaneous vessels Systemic inflammation obstructing blood flow, with granulomatous lesions primarily in upper airways and lungs Ear, nose, and throat involvement ↑ C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) (markers of inflammation) Necrotizing granulomas on biopsy of affected tissue Positive PR3-ANCA/c-ANCA blood test (antibodies present in ~90% of patients, described in GPA Pathogenesis slide) Renal involvement Inflammation of renal vessels Rupture of basement membrane (layer that filters blood from glomerular capillaries into Bowman’s capsule) Pauci-immune glomerulonephritis (see Nephritic Syndrome slide) Rapidly progressive glomerulonephritis Eye involvement Inflammation of ocular tissue Conjunctivitis Scleritis/ episcleritis (painful red eye) Lower respiratory tract involvement Inflammation of pulmonary vessels Vessel occlusion and ischemia Skin necrosis Vessels burst and blood pools under skin Round and retiform (net- like) palpable purpura of lower extremities Granulomatous destruction of nasal cartilage Collapse of nasal bridge Saddle nose deformity Inflammation of paranasal sinus and nasal cavity vessels ↓ Perfusion of lungs Dyspnea Damage to interstitial capillaries Hemoptysis Diffuse alveolar hemorrhage Rhinitis/ sinusitis Granulomatous obstruction of eustachian tube Otitis media (see Otitis Media slide) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published December 4, 2022 on www.thecalgaryguide.com