Transcript The use of A 1-15 multi-antigen peptide as a potential
Aß Immunotherapy: Lessons From Mice, Monkeys and Men
Cynthia A. Lemere Center for Neurologic Diseases Brigham and Women’s Hospital Harvard Medical School Boston, MA USA
Silver Stained Plaques and Tangles
Alzheimer’s Disease
A syndrome arising from a
production and Aß clearance
accumulation of Aß 42 .
chronic imbalance between Aß
that leads to gradual cerebral The imbalance can be caused by numerous distinct genetic (or environmental) alterations (e.g., mutations in APP, PS1 or PS2 lead to increased Aß production and early onset FAD).
Aß aggregates: toxic
in vitro
and cause impaired memory and learning, gliosis and neuritic dystrophy
in vivo
(APP, PSAPP tg mice)
Several Therapeutic Approaches Based Upon the Importance of ß-Amyloid in AD
•
inhibit Aß-generating proteases (ß- or
g
-secretase)
•
prevent the aggregation of Aß into oligomers and fibrils
•
prevent the deposition of Aß into plaques
•
enhance Aß clearance
•
interfere with the toxic response of neurons to amyloid
•
inhibit the inflammatory process around amyloid plaques
Aß Vaccination: Potential Therapy For Alzheimer’s Disease
Mouse Studies
• • •
Active Aß immunization in APP and APP/PS1 Tg mice: Generates anti-Aß titers
–
Lowers cerebral Aß levels (if early enough)
Nature
1999; Weiner, Lemere et al.,
Ann Neurol
publications) (Schenk et al., 2000; and many other
– –
B cell epitopes within Aß amino-terminus, Aß1-15 T cell epitopes within Aß16-42 Increases peripheral levels of Aß in blood (Lemere et al,
Neurobiol Dis
2003) Improves behavior/cognition on certain tasks (Janus et al.,
Nature NS
2002, etc.) 2000; Morgan et al.,
Nature
2000; Dodart et al.,
Nature
Passive Transfer of Aß Antibodies in Mice
• •
Results: - direct application of Aß antibodies to brain surface clears local plaques (Bacskai et al.,
Nat Med
2001) - i.p. injections decreased brain Aß (Bard et al.,
Nat Med
- increased Aß in blood (DeMattos et al.,
PNAS
2000) 2001) - improved behavior
J Neurosci
(Dodart et al,
Nat Neurosci
2002; Kotilinek et al., 2002; Wilcock et al.,
J Neuroinflammation
2004) HC injections of 2 Aß Mabs in 3xAD-Tg mice cleared extracellular and intracellular Aß as well as early tau aggregates but not hyperphosphorylated tau (Oddo et al.,
Neuron
2004)
• • •
Intracerebral ventricular injections of Aß antibodies protected APP tg mice from synaptic loss and gliosis (Chuahan et al.,
J Neurosci Res,
2002) Passive transfer protected neurons from induced seizures in APP tg mice (Mohajeri et al.,
J Biol Chem
2002) Microhemorrhage observed in very old APP tg mice with CAA (Pfiefer et al.,
Science
al.,
J Neurosci
2005 ) 2002; Wilcock et al.,
J Neuroinflamm
2004; Racke et
Passive immunization in PDAPP Tg mice
Aß Pab by i.p. weekly for 6 months: 93% reduction Bard et al.,
Nature Medicine
, 2000
Aß Immunization of Caribbean Vervet Monkeys (Chlorocebus atheiops)
•
African Green Monkeys
•
Imported to St. Kitts ~1670
•
Collaboration with BSF -- 8 s.c. injections 1 mg Aß40/42 + CFA/IFA over 10 months -- 5 vervets immunized, 5 controls (all between 15 and 30 yr) -- B cell epitope in Aß N-terminus, reduced cerebral Aß load and gliosis, increased plasma Aß, no T or B cells in brain (Lemere et al., Am J Pathol 2004)
600 500 400 300 200 100 0
Aß Immunization Reduced Cerebral Aß
Aßx-42 in Brain Homogenates Plaque Burden in Frontal Cortex ** control immunized
80 70 60 50 40 30 20 10 0 0 5 10 15 20
Monkey Age (yr)
25 30
Soluble Aßx-42 Insoluble Aßx-42
Controls Immunized
Proposed Mechanisms
• •
Aß antibodies prevent Aß aggregation and/or dissolve Aß aggregates
in vitro
(Solomon et al.,
PNAS
1996, 1997) Fc-mediated microglial phagocytosis of Aß in brain (Bard et al.,
Nature Med
2000 ) - Fc-mediated response not required (Fab; FcR-/- mice) ( Bacskai et al.,
J Neurosci
2002; Das et al., J Neurosci 2003)
•
Peripheral Sink Hypothesis: shift in gradient across the BBB such that there is an increase in efflux of Aß from
Dis
, 2003) brain to blood (DeMattos et al.,
PNAS
2001; Lemere et al.,
Neurobiol
• • • • • •
ELAN/AHP/Wyeth Human Clinical Trials
Trial halted (January 2002): ~ 6 % of Aß-immunized patients (18/300) developed meningoencephalitis; anti-Aß antibodies detected in serum in subset (Schenk,
Nature Rev
2002; Orgogozo et al,
Neurology
2003; Gilman et al.,
Neurology
2005) Anti-Aß antibodies recognize AD plaques and CAA but not soluble Aß 42 nor APP (Hock et al.,
Nature Med
2002) ; epitopes against free N-terminus of Aß (Lee et al.,
Ann Neurol
2005) Some slowing of cognitive decline (Hock et al.,
Neuron
2003; Gilman et al.,
Neurology
2005) Reduced Aß deposition in brain (Case Studies: Nicoll et al.,
Nature Med
2003; Ferrer et al.,
Brain Pathol
2004; Masliah et al.,
Neurology
2005) Reduced tau levels in CSF (Gilman et al.,
Neurology
2005) Cortical shrinkage by MRI in patients who generated Aß antibodies even though some clinical improvement observed (Fox et al.,
Neurology
2005)
Reduced Plaque Burden in Immunized Pt
From Nicoll et al., Nature Medicine 2003
Possible explanations for the adverse effects?
• • • • •
The immunogen, Aß1-42, may have been recognized as self antigen by some, leading to an autoimmune, toxic T cell response in the CNS The adjuvant, QS-21, purified saponin, is known to have prodominantly Th1/CD4+ cellular immune effects and can induce CTL against antigens (Kenney et al.,
Vaccine
2002; Cribbs et al.,
Int Immunol
2003) Increased T cell response to Aß in aged humans (Monsonego et al.,
JCI
2003) Addition of polysorbate 80 to vaccine formulation (Nicholl et al.,
Nature Med
2003) Thus, development of an active Aß vaccine that would produce a strong humoral response but avoid an Aß-specific T cell response may be beneficial.
Novel Immunogens to Short Aß Peptides: Publications in Preparation (cannot show immunogens yet)
Intranasal Aß Immunization: Our previous work
•
Intranasal (i.n.) Aß immunization without adjuvant resulted in a modest humoral immune response that lowered cerebral A
in PDAPP tg mice (Weiner et al., Ann Neurol, 2000; Lemere et al., NY Acad Sci, 2000).
•
Adjuvant LT(R192G), a mutant form of E. coli heat labile toxin that is less toxic than its native form, enhanced the generation of Aß antibodies when administered intranasally with Aß peptides (Lemere et al., Neurobiol Aging, 2002).
Immunization of J20 APP tg mice with 2 novel Aß immunogens
•
J20 APP-tg mice (hAPP Sw , Ind )/PDGF-promoter on a mixed C57BL/6 x DBA background (L. Mucke, UCSF)
•
6 month-old mice received intranasal immunization weekly (n = 7 mice/ group) Treatment Groups: 100
g Aß Immunogen 1 + 5
g LT(R192G) 50 µg Aß Immunogen 2 + 5 µg LT(R192G) 5 µg LT(R192G) H2O
•
Treated for 24 weeks; at end, 5 mice per group except vehicle (6).
New Aß Immunogens: Summary
• • • • •
Intranasal immunization using our novel short Aß immunogens led to a robust humoral response in both WT and J20 APP tg mice.
Ig isotypes were mainly of the Th2 type; B cell epitopes were located within the amino-terminus of Aß. Splenocytes proliferated against the immunizing peptides but not full-length Aß.
Immunization resulted in lowering of plaque burden and plaque-associated pathology in APP tg mice.
No toxicity or untoward affects were observed. B and T cells were absent from brain.
Aß Immunotherapy: Conclusions
• • • • •
Active Aß vaccination prevents or reduces AD-like pathology and improves cognition but needs to be made safer. Generating a humoral immune response while avoiding an Aß specific cellular response may improve safety.
Passive transfer of Aß antibodies is also effective at lowering cerebral Aß and improving cognition but has been associated with microhemorrhage in the presence of abundant CAA in old APP tg mice. Human trials are underway.
Ultimately, an active vaccine would be less costly and would allow coverage of a much larger population compared to passive transfer.
Our novel immunogens appear to be safe. Further testing is required but first an animal model is needed.
“All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.” Arthur Schopenhauer (1788-1860) German Philosopher
Acknowledgements
Center for Neurologic Diseases
Lemere Lab
Tim Seabrook Gal Bitan Marcel Maier
Others
Weiming Xia Liying Jiang Katelyn Thomas Dominic Walsh Ying Peng Jackie Sears Noel Lazo Amy Huynh
Former Lab Members
Edward Spooner Jeanne Bloom Diana Li Dr. Lennart Mucke (J20 APP tg mice) -- Gladstone Institute, SF, CA Dr. John Clements [LT(R192G)] -- Tulane U. Medical School, LA Elan Pharmaceuticals (ELISA Mabs) -- So. San Francisco, CA Drs. Todd Golde and Pritam Das (ELISA) -- Mayo Clinic, Jacksonville, FA Funding: Alzheimer’s Association, (AG20159) to CAL, and a special thanks to the Brunozzi Family.
NIH