About the Lab

For the last 25 years, the Holtzman lab has been trying to better understand mechanisms underlying neurodegeneration, particularly as they are relevant to Alzheimer’s disease (AD). The lab has published extensively on the neurobiology of apoE and its receptors, how apoE, Aβ binding molecules, and other factors such as neuronal activity, glucose, insulin, and sleep influence Aβ metabolism. More recently, we have also been studying tau metabolism and how anti-tau antibodies may affect its potential role in spreading in its pathophysiology as well as how apoE influences tau-mediated neurodegeneration. Recently, we have been studying how microglia and specific microglial genes such as TREM2 influence neurodegeneration in the setting of Aβ and tau pathology. From the therapeutic perspective, we have shown that certain anti-Aβ antibodies have therapeutic potential in animal models including an antibody m266. This use of this antibody for potential therapeutic and diagnostic purposes was licensed by Washington University to Eli Lilly and subsequently humanized (Solanezumab). It did not hit its primary endpoint in a phase III trial in mild dementia due to AD; however, it is still in 2 secondary prevention trials in AD at much higher doses than used previously (A4 and DIAN-TU). The Holtzman lab also developed an anti-tau antibody that based on cellular and animal model data was humanized and entered human clinical trials. After completing a phase I trial in progressive supranuclear palsy (PSP), it has now entered 2 phase II trials by AbbVie in November of 2016 in both PSP and AD. The lab has developed 2 techniques to allow us to better study Aβ, tau, apoE, and metabolism of other proteins in the CNS including 1) a protein microdialysis method that is used to assess proteins as frequently as every 30 minutes in the brain interstitial fluid of awake rodents and humans, and 2) a metabolic labeling technique using 13C-labeled amino acids following by sampling of human CSF or rodent brain to measure rates of protein synthesis and clearance in the CNS. In humans, we have worked extensively on the development of antecedent biomarkers of AD.

Some of the areas the lab is working on and has published on are listed below:

  1. Active and passive immunization against the Aβ peptide remains a potential future therapy to most likely delay the onset/prevent and possibly treat AD. My laboratory has been involved in utilizing animal models of Aβ deposition to demonstrate that passive administration with certain antibodies has potential as a therapy against AD, characterizing the mechanism of action of different anti-Aβ antibodies, and demonstrating the potential utilization of antibodies for diagnostic purposes in AD. Some of our work highlighted below was the first demonstration that an antibody to soluble forms of Aβ can both decrease Aβ deposition in the brain but also increase plasma Aβ that is derived from the brain. This antibody, called m266 can also bind soluble forms of Aβ in the CNS after peripheral administration. The antibody was subsequently humanized by Eli Lilly and is now called Solanezumab. In 2016, it did not hit its primary endpoint in a phase III trial in mild dementia; however, it remains in 2 prevention trials (DIAN-TU and A4).
    1. DeMattos RB, Bales KR, Cummins DJ, Dodart J-C, Paul SM, Holtzman DM. (2001) Peripheral anti-Aβ antibody alters CNS and plasma Aβ clearance and decreases brain Aβ burden. Proceedings of the National Academy of Science USA 98: 8850-8855:10.1073/pnas.151261398.
    2. DeMattos RB, Bales KR, Cummins DJ, Paul SM, Holtzman DM. (2002) Brain to plasma amyloid-β efflux: A measure of brain amyloid burden in a mouse model of Alzheimer's disease. Science 295:2264-2267.
    3. Dodart JC, Bales KR, Gannon KS, Greene SJ, DeMattos RB, Mathis C, DeLong CA, Wu S, Wu X, Holtzman DM, Paul SM. (2002) Immunization reverses memory deficits without reducing Aβ burden in Alzheimer's disease model. Nature Neuroscience 5:452-457.
    4. Brendza RP, Bacskai BJ, Cirrito JR, Simmons KA, Skoch JM, Klunk WE, Mathis CA, Bales KR, Paul SM, Hyman BT, Holtzman DM. (2005) Anti-Aβ antibody treatment promotes the rapid recovery of amyloid-associated neuritic dystrophy in PDAPP transgenic mice. Journal of Clinical Investigation 115:428-433.
  2. The apolipoprotein E gene (APOE) is the strongest genetic risk factor for AD. One copy of the ε4 isoform of APOE increases AD risk by ~3.7 fold whereas 2 copies of the ε4 isoform increases risk by ~12-fold relative to the ε3 allele. One copy of the ε2 allele of APOE decreases AD risk by ~0.6. The ε4 allele also increases risk for CAA. While there are several ways that apoE may be contributing to AD risk, our data demonstrates, along with data from other labs, that a major mechanism by which apoE contributes to AD risk is via apoE’s effects on both Aβ clearance and aggregation. Using mouse models, we showed that apoE isoforms modulate Aβ deposition in a pattern very similar to that seen in humans. We found that apoE isoforms directly modify endogenous soluble ISF Aβ clearance (but not synthesis) in the brain ISF in vivo with Aβ clearance being in the order E2>E3>E4. This suggests that the reason for the apoE-isoform specific effects on Aβ deposition are due to differential effects of apoE isoforms on soluble Aβ clearance. We also found that the LDL receptor and ABCA1 strongly influence apoE levels and Aβ deposition in the brain via distinct mechanisms. Recently, we have also found that ApoE strongly influences tau-mediated neurodegeneration via a mechanism in part linked to effects on the brain’s innate system. This finding provides novel insights into the links between apoE and neurodegenerative diseases. All the work referenced below was carried out in my lab and all experiments, personnel, data analysis, and writing of manuscripts were under my direction.
    1. Holtzman DM, Bales KR, Tenkova T, Fagan AM, Parsadanian M, Sartorius LJ, Mackey B, Olney J, McKeel D, Wozniak D, Paul SM (2000). Apolipoprotein E isoform-dependent amyloid deposition and neuritic degeneration in a mouse model of Alzheimer's disease. Proc. Natl. Acad. Sci. USA 97:2892-2897.
    2. Kim J, Castellano JM, Jiang H, Basak JM, Parsadanian M, Pham V, Mason SM, Paul SM, Holtzman DM. Overexpression of low-density lipoprotein receptor in the brain markedly inhibits amyloid deposition and increases extracellular Abeta clearance. Neuron. 2009 Dec 10;64(5):632-44. PMCID: PMC2787195
    3. Castellano JM, Kim J, Stewart FR, Hong J, DeMattos RB, Patterson BW, Fagan AM, Morris JC, Mawuenyega KG, Cruchaga C, Goate AM, Bales KR, Paul SM, Bateman RJ, Holtzman DM. (2011) Human apoE Isoforms Differentially Regulate Brain Amyloid-β Peptide Clearance. Science Translational Medicine 29;3(89):89ra57. PMCID: PMC3192364
    4. Shi Y, Yamada K, Liddelow SA, Smith ST, Zhao Z, Luo W, Tsai RM, Spina S, Grinberg LT, Rojas JC, Gallardo G, Wang K, Roh J, Robinson G, Finn MB, Jiang H, Sullivan PM, Baufeld CB, Wood MW, Sutphen C, McCue L, Xiong C, Del-Aguila JL, Morris JC, Cruchaga C, Fagan AM, Miller BL, Boxer AL, Seeley WW, Butovsky O, Barres BA, Paul SM, Holtzman DM (2017) ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature 2017 Sep 28;549(7673):523-527. NIHMS 910420
  3. Following up work by Malinow and colleagues that demonstrated in cultured neurons that synaptic activity stimulated an increase in Aβ release, we showed for the first time that levels of soluble, monomeric Aβ peptide in the brain in vivo, in both mice and humans, are directly regulated by synaptic activity, specifically, by synaptic vesicle release. This finding, together with our additional papers below, strongly suggests that the reason Aβ deposition in the human brain occurs first and to the greatest extent in regions of the brain overlapping with what is called the “default mode network” is due to greater metabolic and synaptic activity in these regions over a lifetime resulting in higher monomeric Aβ levels leading to earlier Aβ aggregation in these regions. All the work referenced below was carried out in my lab and all experiments, personnel, data analysis, and writing of manuscripts were under my direction.
    1. Cirrito JR, Yamada KA, Finn MB, Sloviter RS, Bales KR, May PC, Schoepp DD, Paul SM, Mennerick S, Holtzman DM. (2005) Synaptic activity regulates interstitial fluid amyloid- levels in vivo. Neuron 48(6):913-922.
    2. Cirrito JR, Kang J-E, Lee J, Stewart FR, ¬¬Verges D, Silverio LM Bu G, Mennerick S, Holtzman DM. (2008) Endocytosis is required for synaptic activity-dependent release of amyloid- in vivo. Neuron 58:42-51. PMCID: PMC2390913
    3. Brody DL, Magnoni S, Schwetye KE, Spinner M, Esparza TJ, Stocchetti N, Zipfel GJ, Holtzman DM. (2008) Amyloid-β Dynamics Correlate with Neurological Status in the Injured Human Brain Science 321:1221–1224. PMCID: PMC2577829
    4. Bero AW, Yan P, Roh JH, Cirrito JR, Stewart FR, Raichle ME, Lee JM, Holtzman DM. Neuronal activity regulates the regional vulnerability to amyloid-β deposition. Nat Neurosci. 2011 14(6):750-6. PMCID:PMC3102784
  4. We found that in the brain ISF in mice and in CSF in humans, Aβ is higher during wakefulness and lower during sleep. We also found that at least part of these fluctuations are due to differences in synaptic activity and Aβ generation between the wake and sleep states. Increasing wakefulness by sleep deprivation and with orexin both acutely increased Aβ as well as chronically increased Aβ deposition. Increasing sleep with an orexin receptor antagonist acutely decreased Aβ and chronically decreased Aβ deposition. We also found that genetic manipulation of orexin produces similar results and that this effect appears to be due to the effect of orexin on sleep. Once Aβ deposition occurs, this results in disrupted sleep and even greater Aβ production. This work has important implications for not only a mechanism of how normal brain function and its dysfunction could predispose to AD but also suggests that understanding and treating sleep disorders may provide a new way to decrease AD risk. We have also found that hyperglycemia acute increases ISF Aβ, and this also occurs via a synaptic activity-dependent mechanism via KATP channels. All the work below was carried out in my lab and all experiments, personnel, data analysis, and writing of manuscripts were under my direction.
    1. Kang JE, Lim MM, Bateman RJ, Lee JJ, Smyth LP, Cirrito JR, Fujiki N, Nishino S, Holtzman DM. (2009) Amyloid-β Dynamics Are Regulated by Orexin and the Sleep-Wake Cycle. Science. 326:1005-1008. PMCID:PMC2789838
    2. Roh JH, Huang Y, Bero AW, Kasten T, Stewart FR, Bateman RJ, Holtzman DM. Disruption of the sleep-wake cycle and diurnal fluctuation of amyloid-β in mice with Alzheimer’s disease pathology. Science Translational Medicine 2012 Sep 5;4(150):150ra122. PMCID: PMC3654377
    3. Macauley SL, Stanley M, Caesar EE, Yamada SA, Raichle ME, Perez R, Mahan TE, Sutphen CL, Holtzman DM. Hyperglycemia modulates extracellular amyloid-β concentrations and neuronal activity in vivo. J Clin Invest. 2015 May 4. Pii:79742. Doi: 10.1172/JCI79742. PMCID: PMC4497756
    4. Musiek ES, Holtzman DM. Mechanisms linking circadian clocks, sleep, and neurodegeneration. Science. 2016 Nov 25;354(6315):1004-1008. PMCID: PMC5219881
  5. Increasing evidence suggests that tau pathology spreads from initially affected regions to synaptically connected regions. We hypothesized that if the spreading of tau pathology occurs in a prion-like manner extracellularly, then studying extracellular tau metabolism would provide insight into what regulates the levels of both monomeric and oligomeric tau in the brain ISF and ultimately the spread of tau pathology. We rationalized that certain antibodies to tau might be able to block tau pathology and neurodegeneration bind binding to extracellular forms of tau to block tau spreading. We have been able to characterize ISF tau metabolism utilizing in vivo microdialysis and what influences ISF tau levels. We found that excitatory synaptic activity increases extracellular tau in vivo. We also found that certain anti-tau antibodies that were able to block cellular tau seeding in vitro in collaboration with the Diamond lab. When tested in vivo, the antibody that best blocked tau seeding was most potent at suppressing tau pathology, decreasing brain atrophy, and improving behavior when administered either centrally or peripherally. One of these antibodies has now been humanized and is in clinical trials in tauopathies. Interestingly, we found that plasma tau is derived from the CNS and that it is increased markedly in the plasma after injection of an anti-tau antibody. The increase in plasma tau following anti-tau antibody administration reflects the concentration of extracellular tau in the CNS. All the work in the papers below except for the seeding assays in reference b were carried out in my lab and all experiments, personnel, data analysis, and writing of manuscripts were under my direction.
    1. Yamada K, Holth JK, Liao F, Stewart FR, Mahan TE, Jiang H, Cirrito JR, Patel TK, Hochgräfe K, Mandelkow EM, Holtzman DM. Neuronal activity regulates extracellular tau in vivo. J Exp Med. 2014 10;211(3):387-93. PMCID: PMC3949564
    2. Yanamandra K, Kfoury N, Jiang H, Mahan TE, Ma S, Maloney SE, Wozniak DF, Marc, Diamond MI, Holtzman DM. Anti-tau antibodies that block tau aggregate seeding in vitro markedly decrease pathology and improve cognition in vivo. Neuron 2013 Oct 16;80(2):402-14. PMCID: PMC3924573
    3. Ising C, Gallardo G, Leyns CEG, Wong CH, Stewart F, Koscal LJ, Roh J, Robinson GO, Remolina Serrano J, Holtzman DM. AAV-mediated expression of anti-tau scFvs decreases tau accumulation in a mouse model of tauopathy. J Exp Med. 2017 Apr 17. pii: jem.20162125. doi: 10.1084/jem.20162125. PMCID:PMC5502435
    4. Yanamandra K, Patel TK, Jiang H, Schindler S, Ulrich JD, Boxer AL, Miller BL, Kerwin DR, Gallardo G, Stewart F, Finn MB, Cairns NJ, Verghese PB, Fogelman I, West T, Braunstein J, Robinson G, Keyser J, Roh J, Knapik SS, Hu Y, Holtzman DM. Anti-tau antibody administration increases plasma tau in transgenic mice and patients with tauopathy. Sci Transl Med. 2017 Apr 19;9(386). NIHMS 924558