Pathophysiology

COMPLEMENT ACTIVATION TRIGGERS A CHAIN OF ASTROCYTE DESTRUCTION IN AQP4-IgG+ NMOSD1-3

Activated complement leads to the destruction of astrocytes, chronic inflammation, demyelination, neuronal death, and the creation of lesions in the central nervous system (CNS), ultimately ending in physical disability and, possibly, death.1-5

AQP4-IgG+, aquaporin-4 immunoglobulin G positive; NMOSD, neuromyelitis optica
spectrum disorder.

This is a hypothetical patient.

THE COMPLEMENT PATHWAY

The complement cascade, or complement pathway, is a vital component of the body’s immune system, responsible for the formation of the membrane attack complex and bacterial lysis. Following injury or infection, the complement system acts quickly to detect, destroy, and eliminate microbes or cellular debris.6,7

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


COMPLEMENT ACTIVATION BEGINS IN NMOSD WHEN AQP4-IgG AUTOANTIBODIES BIND TO AQP4 WATER CHANNELS ON ASTROCYTES1,9,10

In anti-aquaporin 4 (AQP4) antibody-positive NMOSD, terminal complement activation can lead to
inflammation and destruction of astrocytes.10,11

Anti-AQP4 antibody
binds to AQP41,4,9-11
Anti-AQP4 antibody binds to AQP4 graphic

Anti-AQP4 antibody crosses the
blood-brain barrier and binds to AQP4 on astrocyte foot processes in the CNS.

Complement activation1-5,9,10
Complement activation graphic

Anti-AQP4 antibody binding to AQP4 activates complement. When terminal complement is activated, the complement component C5 is cleaved into C5a and C5b.

Astrocyte and neuronal death10,11
Astrocyte and neuronal death graphic

This contributes to chronic inflammation and the formation of the C5b-9 membrane attack complex (MAC) that leads to cell lysis and perforation of the astrocyte cell membrane, resulting in demyelination and cell death.

WALLS

IN PRECLINICAL STUDIES, COMPLEMENT ACTIVATION QUICKLY RESULTED IN PERMANENT DAMAGE TO THE CNS5,10

Watch video of complement activation results Watch video of complement activation results

EACH ATTACK MAY PUT PATIENTS AT RISK FOR A STEPWISE ACCUMULATION OF DISABILITY3,12

IMPACT OF ATTACKS

ATTACKS CAN BE RECURRENT AND MAY PREDICT FUTURE DISABILITY3,13

CYCLE OF ATTACKS
References: 1. 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. 2. Mealy MA, Kessler RA, Rimler Z, et al. Mortality in neuromyelitis optica is strongly associated with African ancestry. Neurol Neuroimmunol Neuroinflamm. 2018;5(4):e468. 3. Jarius S, Ruprecht K, Wildemann B, et al. Contrasting disease patterns in seropositive and seronegative neuromyelitis optica: a multicentre study of 175 patients. J Neuroinflammation. 2012;9:14. 4. Chamberlain JL, Huda S, Whittam DH, Matiello M, Morgan BP, Jacob A. Role of complement and potential of complement inhibitors in myasthenia gravis and neuromyelitis optica spectrum disorders: a brief review. J Neurol. 2021;268(5):1643-1664. 5. Winkler A, Wrzos C, Haberl M, et al. Blood-brain barrier resealing in neuromyelitis optica occurs independently of astrocyte regeneration. J Clin Invest. 2021;131(5):e141694. 6. Merle NS, Noe R, Halbwachs-Mecarelli L, Fremeaux-Bacchi V, Roumenina LT. Complement system part II: role in immunity. Front Immunol. 2015;6:257. 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. 9. Weinshenker BG, Wingerchuk DM. Neuromyelitis spectrum disorders. Mayo Clin Proc. 2017;92(4):663-679. 10. Papadopoulos MC, Verkman AS. Aquaporin water channels in the nervous system. Nat Rev Neurosci. 2013;14(4):265-277. 11. Wingerchuk DM, Lennon VA, Lucchinetti CF, Pittock SJ, Weinshenker BG. The spectrum of neuromyelitis optica. Lancet Neurol. 2007;6(9):805-815. 12. Brod SA. Review of approved NMO therapies based on mechanism of action, efficacy and long-term effects. Mult Scler Relat Disord. 2020;46:102538. 13. Kitley J, Leite MI, Nakashima I, et al. Prognostic factors and disease course in aquaporin-4 antibody-positive patients with neuromyelitis optica spectrum disorder from the United Kingdom and Japan. Brain. 2012;135(pt 6):1834-1849.