Complement activation is an important cause of damage in AQP4-IgG+ NMOSD1-4

Complement activation leads to astrocytopathy, inflammation, and neuronal death.2,4




AQP4-IgG antibodies1-3

Aquaporin-4 immunoglobulin G (AQP4-IgG) antibodies cross the blood-brain barrier and bind to AQP4 on astrocyte foot processes.

Complement activation2-4

AQP4-IgG antibody binding activates complement, leading to inflammation and membrane attack complex formation.

Astrocytopathy leading to neuronal destruction2,4

In Neuromyelitis Optica Spectrum Disorder (NMOSD), activated complement leads to astrocyte necrosis, inflammatory damage, and neuronal death.



The complement pathway is an innate immune component responsible for the formation of the membrane attack complex and bacterial lysis.5,6

Imbalances in the activation or regulation of the complement pathway are implicated in autoimmune diseases.8

Complement cascade, or complement pathway, is a vital component of the body’s immune system, most abundant in blood.5,6

Following injury or infection, the complement system acts quickly to detect, destroy, and eliminate microbes or cellular debris.7

The cascade is executed by a complex and tightly regulated group of more than 40 blood proteins known as complement proteins.5 The proteins include soluble and cell surface–bound components that work with receptors and regulators.7

Imbalances in the activation or regulation of the complement pathway are implicated in autoimmune diseases.8

References: 1. Weinshenker BG, Wingerchuk DM. Neuromyelitis spectrum disorders. Mayo Clin Proc. 2017;92(4):663-679. 2. Papadopoulos MC, Verkman AS. Aquaporin water channels in the nervous system. Nat Rev Neurosci. 2013;14(4):265-277. 3. Piatek P, Domowicz M, Lewkowicz N, et al. C5a-preactivated neutrophils are critical for autoimmune-induced astrocyte dysregulation in neuromyelitis optica spectrum disorder. Front Immunol. 2018;9:1694. 4. Wingerchuk DM, Lennon VA, Lucchinetti CF, Pittock SJ, Weinshenker BG. The spectrum of neuromyelitis optica. Lancet Neurol. 2007;6(9):805-815. 5. Merle NS, Noe R, Halbwachs-Mecarelli L, Fremeaux-Bacchi V, Roumenina LT. Complement system part II: role in immunity. Front Immunol. 2015;6:257. 6. Walport MJ. Complement: first of two parts. N Engl J Med. 2001;344(14):1058-1066. 7. Dunkelberger JR, Song WC. Complement and its role in innate and adaptive immune responses. Cell Res. 2010;20(1):34-50. 8. Ricklin D, Mastellos DC, Reis ES, Lambris JD. The renaissance of complement therapeutics. Nat Rev Nephrol. 2018;14(1):26-47.


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