Complement C3-Targeted Gene Therapy Restricts Onset and Progression of Neurodegeneration in Chronic Mouse Glaucoma

Abstract

Dysregulation of the complement system is implicated in neurodegeneration, including human and animal glaucoma. Optic nerve and retinal damage in glaucoma is preceded by local complement upregulation and activation, but whether targeting this early innate immune response could have therapeutic benefit remains undefined. Because complement signals through three pathways that intersect at complement C3 activation, here we targeted this step to restore complement balance in the glaucomatous retina and to determine its contribution to degeneration onset and/or progression. To achieve this, we combined adeno-associated virus retinal gene therapy with the targeted C3 inhibitor CR2-Crry. We show that intravitreal injection of AAV2.CR2-Crry produced sustained Crry overexpression in the retina and reduced deposition of the activation product complement C3d on retinal ganglion cells and the inner retina of DBA/2J mice. This resulted in neuroprotection of retinal ganglion cell axons and somata despite continued intraocular pressure elevation, suggesting a direct restriction of neurodegeneration onset and progression and significant delay to terminal disease stages. Our study uncovers a damaging effect of complement C3 or downstream complement activation in glaucoma, and it establishes AAV2.CR2-Crry as a viable therapeutic strategy to target pathogenic C3-mediated complement activation in the glaucomatous retina.

Gene delivery to the rat retina by non-viral vectors based on chloroquine-containing cationic niosomes

“…(white and yellow arrows, respectively). Transfection at this level can be of clinical relevance in treatment of devastating ocular pathologies that compromise the function of ganglion cells as glaucoma [48]. Interestingly, EGFP expression was also discerned in the OPL (Fig.…”

GLP-1R agonist NLY01 reduces retinal inflammation, astrocyte reactivity, and retinal ganglion cell death secondary to ocular hypertension

“…A1 astrocytes upregulate complement component 3 (C3) , and C3 inhibitors were shown to reduce RGC cell death in the DBA/2J mouse model of glaucoma (Bosco et al, 2018). We demonstrated elevated C3 production following A1 activation and decreased C3 production following NLY01 inhibition in our glaucoma model.…”

Anaphylatoxin Receptor C3AR1 Promotesoptic Nerve Degeneration in DBA/2J Mice

“…Understanding why C3ar1 de ciency did not provide long-lasting protectionrequires understandingotherdamaging consequences of complement activation.Greater protection in DBA/2J mice has been achieved by disruptingC1qa(37)compared to C3ar1, suggesting that C1qa triggers multiple damaging responses. A therapy targeting sites opsonized by C3b and C4b, achieved by expression of CR2-Crry in retinal ganglion cells, has produced results more similar to C1qa de ciency (14).Crrywould be predicted to inhibit C3 convertase activity of the classical pathway (through C4b) and alternative pathway (through C3b)(58),severely limiting accumulation of both C3a and C3b in the treated DBA/2J mice. Theresults of treatment with CR2-Crry suggest that inhibition of C3a and C3b protects in an additive manner.…”

“…Research in animal models suggests that the complement cascade contributes to pathology in ocular hypertensive eyes (4,(13)(14)(15)(16)(17)(18)(19)(20). This includesmodels of glaucoma like DBA/2J mice, who develop an ocular hypertensive disease in which the complement component 1q complex(C1q)or C5exacerbates neuroin ammation, retinal ganglion cell loss and optic nerve degeneration (20)(21)(22)(23).…”