Multivalent design of the monoclonal SynO2 antibody improves binding strength to soluble α-Synuclein aggregates

• Soluble aggregates are reported to be the most neurotoxic species of alpha-Synuclein (alpha Syn) in Parkinson's disease (PD) and hence are a promising target for diagnosis and treatment of PD. However, the predominantly intracellular location of alpha Syn limits its accessibility, especially for antibody-based molecules and prompts the need for exceptionally strong soluble alpha Syn aggregate binders to enhance their sensitivity and efficacy for targeting the extracellular alpha Syn pool. In this study, we have created the multivalent antibodies TetraSynO2 and HexaSynO2, derived from the alpha Syn oligomer-specific antibody SynO2, to increase avidity binding to soluble alpha Syn aggregate species through more binding sites in close proximity. The multivalency was achieved through recombinant fusion of single-chain variable fragments of SynO2 to the antibodies' original N-termini. Our ELISA results indicated a 20-fold increased binding strength of the multivalent formats to alpha Syn aggregates, while binding to alpha Syn monomers and unspecific binding to amyloid beta protofibrils remained low. Kinetic analysis using LigandTracer revealed that only 80% of SynO2 bound bivalently to soluble aSyn aggregates, whereas the proportion of TetraSynO2 and HexaSynO2 binding bi- or multivalently to soluble alpha Syn aggregates was increased to similar to 95% and 100%, respectively. The overall improved binding strength of TetraSynO2 and HexaSynO2 implies great potential for immunotherapeutic and diagnostic applications with targets of limited accessibility, like extra-cellular alpha Syn aggregates. The ability of the multivalent antibodies to bind a wider range of alpha Syn aggregate species, which are not targetable by conventional bivalent antibodies, thus could allow for an earlier and more effective intervention in the progression of PD.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Neurovetenskaper (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Neurosciences (hsv//eng)

Nyckelord

Avidity

multivalent antibodies

Parkinson's disease (PD)

soluble aggregates

alpha-Synuclein (alpha syn)

Publikations- och innehållstyp

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