Microscopic Polyangiitis: from Pathogenesis to Treatment

Abstract

Microscopic Polyangiitis (MPA) is a systemic pauci-immune necrotizing vasculitis of small-calibre vessels characterized by the absence of granulomas. MPA is an autoimmune disease but its aetiology remains obscure. MPA is associated with presence of antineutrophil cytoplasmatic autoantibodies (ANCAs) but not all patients with MPA have ANCAs. There is strong evidence that not all ANCAs are pathogenetic. It seems that specific epitopes determine ANCAs pathogenicity. Given that MPA is a systemic vasculitis, multiple organs could be affected resulting in a wide spectrum of signs and symptoms. The kidneys and lungs are the most typical organs involved in MPA. Notably, MPA is the major cause of pulmo-renal syndrome. MPA has a poor prognosis if not treated but the use of aggressive immunosuppressive treatment has improved the prognosis and the patient's survival. Rituximab could be considered as an alternative treatment for severe disease, for patients who do not respond adequately to the immunosuppressive treatment and for patients with relapses. However, the long-term safety of Rituximab in MPA is unknown and it should be elucidated by further studies. Interestingly, kidney transplantation is safe and effective and it has a good prognosis in MPA patients with ESRD.

A case report of microscopic polyangiitis presenting as diffuse pulmonary symptoms with no renal involvement

“…Microscopic Polyangiitis (MPA) is a systemic pauciimmune necrotizing vasculitis of small blood vessels characterized by the absence of granulomas. 1 MPA is an autoimmune disease but its etiology remains unknown, which demands extensive research about the disorder. MPA is associated with presence of antineutrophil cytoplasmatic autoantibodies (ANCAs) but not all patients with MPA have ANCAs, yet ANCA'S are considered as pathognomonic feature of MPA.…”

“…MPA is associated with presence of antineutrophil cytoplasmatic autoantibodies (ANCAs) but not all patients with MPA have ANCAs, yet ANCA'S are considered as pathognomonic feature of MPA. 1 Although, there is imminent evidence that not all ANCAs are pathogenetic, there are several epitopes of ANCA, which might determine their pathogenicity individually. 1 Since, it is known that MPA is a systemic disorder, multiple organs could be affected that could lead to differentiating features between each case of MPA with different signs and symptoms.…”

“…1 Although, there is imminent evidence that not all ANCAs are pathogenetic, there are several epitopes of ANCA, which might determine their pathogenicity individually. 1 Since, it is known that MPA is a systemic disorder, multiple organs could be affected that could lead to differentiating features between each case of MPA with different signs and symptoms. The kidneys are most commonly affected in MPA, it has a poor prognosis if not treated but the use of aggressive immunosuppressive treatment has improved the prognosis and the patient's survival.…”

“…The kidneys are most commonly affected in MPA, it has a poor prognosis if not treated but the use of aggressive immunosuppressive treatment has improved the prognosis and the patient's survival. 1 Since the disorder is most commonly associated with kidney organ dysfunction, Interestingly, kidney transplantation is safe and effective and it has a good prognosis in MPA patients. 1 The main clinical presentation in MPA is rapidly progressive glomerulonephritis (RPGN) characterized by rapid decrease of glomerular filtration rate (GFR), microscopic hematuria, erythrocyte cast, presence of proteinuria (usually less than 3g) and hypertension.…”

“…1 Since the disorder is most commonly associated with kidney organ dysfunction, Interestingly, kidney transplantation is safe and effective and it has a good prognosis in MPA patients. 1 The main clinical presentation in MPA is rapidly progressive glomerulonephritis (RPGN) characterized by rapid decrease of glomerular filtration rate (GFR), microscopic hematuria, erythrocyte cast, presence of proteinuria (usually less than 3g) and hypertension. 1 Males are commonly found to be affected by the disorder than females.…”