Combined Active Humoral and Cellular Immunization Approaches for the Treatment of Synucleinopathies

Abstract

Dementia with Lewy bodies, Parkinson's disease, and Multiple System Atrophy are age-related neurodegenerative disorders characterized by progressive accumulation of α-synuclein (α-syn) and jointly termed synucleinopathies. Currently, no disease-modifying treatments are available for these disorders. Previous preclinical studies demonstrate that active and passive immunizations targeting α-syn partially ameliorate behavioral deficits and α-syn accumulation; however, it is unknown whether combining humoral and cellular immunization might act synergistically to reduce inflammation and improve microglial-mediated α-syn clearance. Since combined delivery of antigen plus rapamycin (RAP) in nanoparticles is known to induce antigen-specific regulatory T cells (Tregs), we adapted this approach to α-syn using the antigen-presenting cell-targeting glucan microparticle (GP) vaccine delivery system. PDGF-α-syn transgenic (tg) male and female mice were immunized with GP-alone, GP-α-syn (active humoral immunization), GP+RAP, or GP+RAP/α-syn (combined active humoral and Treg) and analyzed using neuropathological and biochemical markers. Active immunization resulted in higher serological total IgG, IgG1, and IgG2a anti-α-syn levels. Compared with mice immunized with GP-alone or GP-α-syn, mice vaccinated with GP+RAP or GP+RAP/α-syn displayed increased numbers of CD25-, FoxP3-, and CD4-positive cells in the CNS. GP-α-syn or GP+RAP/α-syn immunizations resulted in a 30-45% reduction in α-syn accumulation, neuroinflammation, and neurodegeneration. Mice immunized with GP+RAP/α-syn further rescued neurons and reduced neuroinflammation. Levels of TGF-β1 were increased with GP+RAP/α-syn immunization, while levels of TNF-α and IL-6 were reduced. We conclude that the observed effects of GP+RAP/α-syn immunization support the hypothesis that cellular immunization may enhance the effects of active immunotherapy for the treatment of synucleinopathies. We show that a novel vaccination modality combining an antigen-presenting cell-targeting glucan particle (GP) vaccine delivery system with encapsulated antigen (α-synuclein) + rapamycin (RAP) induced both strong anti-α-synuclein antibody titers and regulatory T cells (Tregs). This vaccine, collectively termed GP+RAP/α-syn, is capable of triggering neuroprotective Treg responses in synucleinopathy models, and the combined vaccine is more effective than the humoral or cellular immunization alone. Together, these results support the further development of this multifunctional vaccine approach for the treatment of synucleinopathies, such as Parkinson's disease, dementia with Lewy bodies, and multiple systems atrophy.

Neuroinflammation is associated with infiltration of T cells in Lewy body disease and ɑ-synuclein transgenic models.

“…In support of this possibility, we found increased levels of TNFα and have previously shown increased IL-1β and IL-6 mRNA expression in this model, which are known to correlate with astrogliosis and inflammation in PD/DLB mouse models [46,83] and patients [84]. Remarkably, we have also shown that reducing the progressive accumulation of α-syn in the CNS with antibodies or antibodies in combination with anti-inflammatory or cytoregulatory approaches, such as enhancing CD25 + T reg cell trafficking to the CNS, rescues the astroglial inflammatory phenotype and reduces the levels of TNFα and IL-6 in tg models [51,69,85].…”

“…Briefly, as previously described [51], paraffin (6 µm) and vibratome (40 µm) sections of human and mouse brains were incubated overnight at 4 °C with primary antibodies: CD3 (abcam ab16669, rabbit…”

Immune system responses in Parkinson's disease: Early and dynamic

“…This vaccination strategy was associated with modifications of the peripheral T‐cell compartment, hence supporting the role of the peripheral immune system in PD‐like degeneration (Christiansen, Olesen, Otzen, Romero‐Ramos, & Sanchez‐Guajardo, ). Therefore, a careful combination of cellular and humoral responses seems like a valid and promising approach, which has been recently corroborated in an a‐syn transgenic mouse (Rockenstein et al., ). Another novel active vaccination strategy combines a‐syn with the chaperone Glucose‐related protein‐94 (Grp94), which has been shown to result in specific cellular immune responses (Labrador‐Garrido et al., ) that could ameliorate the microglia activation response in the MPTP mouse model of dopaminergic degeneration, both directly and also by adoptive transfer of the resulting splenocytes (Villadiego et al., ).…”

Targeting α-Synuclein for PD Therapeutics: A Pursuit on All Fronts

“…This GP vaccine induced a strong immune response with activation of T-regulatory cells in the CNS as well as a strong α-syn antibody production. This in turn reduced α-syn accumulation, neuron loss, and microglial activation, which could not be observed without the combined immunization [209].…”