CD40L disruption enhances Abeta vaccine-mediated reduction of cerebral amyloidosis while minimizing cerebral amyloid angiopathy and inflammation.
Amyloid-beta (Abeta) immunization efficiently reduces amyloid plaque load and memory impairment in transgenic mouse models of Alzheimer's disease (AD). Active Abeta immunization has also yielded favorable results in a subset of AD patients. However, a small percentage of patients developed severe aseptic meningoencephalitis associated with brain inflammation and infiltration of T-cells. We have shown that blocking the CD40-CD40 ligand (L) interaction mitigates Abeta-induced inflammatory responses and enhances Abeta clearance. Here, we utilized genetic and pharmacologic approaches to test whether CD40-CD40L blockade could enhance the efficacy of Abeta(1-42) immunization, while limiting potentially damaging inflammatory responses. We show that genetic or pharmacologic interruption of the CD40-CD40L interaction enhanced Abeta(1-42) immunization efficacy to reduce cerebral amyloidosis in the PSAPP and Tg2576 mouse models of AD. Potentially deleterious pro-inflammatory immune responses, cerebral amyloid angiopathy (CAA) and cerebral microhemorrhage were reduced or absent in these combined approaches. Pharmacologic blockade of CD40L decreased T-cell neurotoxicity to Abeta-producing neurons. Further reduction of cerebral amyloidosis in Abeta-immunized PSAPP mice completely deficient for CD40 occurred in the absence of Abeta immunoglobulin G (IgG) antibodies or efflux of Abeta from brain to blood, but was rather correlated with anti-inflammatory cytokine profiles and reduced plasma soluble CD40L. These results suggest CD40-CD40L blockade promotes anti-inflammatory cellular immune responses, likely resulting in promotion of microglial phagocytic activity and Abeta clearance without generation of neurotoxic Abeta-reactive T-cells. Thus, combined approaches of Abeta immunotherapy and CD40-CD40L blockade may provide for a safer and more effective Abeta vaccine.
Obregon
D
D
Neuroimmunology Laboratory, Institute for Research in Psychiatry, Department of Psychiatry and Behavioral Medicine, USA.
Hou
H
H
Bai
Y
Y
Nikolic
W V
WV
Mori
T
T
Luo
Deyan
D
Zeng
J
J
Ehrhart
J
J
Fernandez
F
F
Morgan
D
D
Giunta
B
B
Town
T
T
Tan
J
J
D000544:Alzheimer Disease / Q000097:blood / Q000473:pathology / Q000628:therapy*; D016229:Amyloid beta-Peptides / Q000097:blood / Q000276:immunology*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics; D000704:Analysis of Variance; D000818:Animals; D000906:Antibodies / Q000097:blood; D019013:CD40 Antigens / Q000172:deficiency; D023201:CD40 Ligand / Q000378:metabolism*; D016657:Cerebral Amyloid Angiopathy / Q000628:therapy*; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology; D006801:Humans; D016233:Immunotherapy, Active / Q000379:methods*; D007249:Inflammation / Q000628:therapy*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010446:Peptide Fragments / Q000097:blood / Q000276:immunology*; D053764:Presenilin-1 / Q000235:genetics; D013997:Time Factors
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D000906:Antibodies; D019013:CD40 Antigens; D016207:Cytokines; D010446:Peptide Fragments; D053764:Presenilin-1; C075222:amyloid beta-protein (1-42); D023201:CD40 Ligand