Faculty Bibliography

Inheritance of the apolipoprotein E4 (apoE4) genotype has been identified as the major genetic risk factor for late-onset Alzheimer's disease (AD). Studies have shown that the binding between apoE and amyloid-beta (Abeta) peptides occurs at residues 244-272 of apoE and residues 12-28 of Abeta. ApoE4 has been implicated in promoting Abeta deposition and impairing clearance of Abeta. We hypothesized that blocking the apoE/Abeta interaction would serve as an effective new approach to AD therapy. We have previously shown that treatment with Abeta12-28P can reduce amyloid plaques in APP/PS1 transgenic (Tg) mice and vascular amyloid in TgSwDI mice with congophilic amyloid angiopathy (CAA). In the present study, we investigated whether the Abeta12-28P elicits a therapeutic effect on tau-related pathology in addition to amyloid pathology using old triple transgenic Alzheimer's disease mice (3xTg, with PS1M146V , APPS we and tauP30 IL transgenes) with established pathology from the ages of 21 to 26 months. We show that treatment with Abeta12-28P substantially reduces tau pathology both immunohistochemically and biochemically, as well as reducing the amyloid burden and suppressing the activation of astrocytes and microglia. These affects correlate with a behavioral amelioration in the treated Tg mice

The accumulation of aggregated, hyperphosphorylated tau as neurofibrillary tangles and neuropil threads are cardinal features of Alzheimer's disease (AD). The other lesions found in AD include amyloid plaques and congophilic amyloid angiopathy, both associated with the extracellular accumulation of the amyloid-beta (Abeta) peptide. AD is the most common cause of dementia globally. Currently, there are no effective means to treat AD or even to slow it down. The dominant theory for the causation of AD is the amyloid cascade hypothesis, which suggests that the aggregation of Abeta as oligomers and amyloid plaques is central to the pathogenesis of AD. Numerous therapies have been developed directed to Abeta-related pathology, in particular various immunotherapeutic approaches. So far all of these have failed in clinical trials. Recently, there has been more focus on therapy directed to tau-related pathology, which correlates better with the cognitive status of patients, compared to the amyloid burden. Immunotherapeutic targeting of tau pathology has shown great potential in treating tau pathologies in mouse models of AD. A number of studies have shown the efficacy of both passive and active immunization. This review summarizes recent advances in therapy targeting pathological tau protein, in particular focusing on immunotherapeutic approaches which are showing great promise. (c) 2014 S. Karger AG, Basel.

Anti-amyloid beta (Abeta) immunotherapy provides potential benefits in Alzheimer's disease patients. Nevertheless, strategies based on Abeta1-42 peptide induced encephalomyelitis and possible microhemorrhages. These outcomes were not expected from studies performed in rodents. It is critical to determine if other animal models better predict side effects of immunotherapies. Mouse lemur primates can develop amyloidosis with aging. Here we used old lemurs to study immunotherapy based on Abeta1-42 or Abeta-derivative (K6Abeta1-30). We followed anti-Abeta40 immunoglobulin G and M responses and Abeta levels in plasma. In vivo magnetic resonance imaging and histology were used to evaluate amyloidosis, neuroinflammation, vasogenic edema, microhemorrhages, and brain iron deposits. The animals responded mainly to the Abeta1-42 immunogen. This treatment induced immune response and increased Abeta levels in plasma and also microhemorrhages and iron deposits in the choroid plexus. A complementary study of untreated lemurs showed iron accumulation in the choroid plexus with normal aging. Worsening of iron accumulation is thus a potential side effect of Abeta-immunization at prodromal stages of Alzheimer's disease, and should be monitored in clinical trials.

Although the mechanisms underlying mild traumatic brain injury (mTBI) are becoming well understood, treatment options are still limited. In the present study, mTBI was induced by a weight drop model to produce a closed head injury to mice and the effect of inhaled nitric oxide (INO) was evaluated by a short term memory task (object recognition task) and immunohistochemical staining of glial fibrillary acidic protein (GFAP) and CD45 for the detection of reactive astrocytes and microglia. Results showed that mTBI model did not produce brain edema, skull fracture or sensorimotor coordination dysfunctions. Mice did however exhibit a significant deficit in short term memory (STM) and strong inflammatory reaction in the ipsilateral cortex and hippocampus compared to sham-injured controls 24h after mTBI. Additional groups of untreated mice tested 3 and 7 days later, demonstrated that recognition memory had recovered to normal levels by Day 3. Mice treated with 10ppm INO for 4 or 8h, beginning immediately after TBI demonstrated significantly improved STM at 24h when compared with room air controls (p<0.05). Whereas mice treated with 10ppm INO for 24h showed no improvement in STM. Mice treated with INO 10ppm for 8h exhibited significantly reduced microglia and astrocyte activation compared with room air controls. These data demonstrate that mTBI produces a disruption of STM which is evident 24h after injury and persists for 2-3 days. Treatment with low concentration or short durations of INO prevents this memory loss and also attenuates the inflammatory response. These findings may have relevance for the treatment of patients diagnosed with concussion.

Amyloid plaques are a key pathological hallmark of Alzheimer's disease (AD). The detection of amyloid plaques in the brain is important for the diagnosis of AD, as well as for following potential amyloid targeting therapeutic interventions. Our group has developed several contrast agents to detect amyloid plaques using magnetic resonance microimaging (microMRI) in AD transgenic mice, where we used mannitol to enhance blood brain barrier (BBB) permeability. In the present study, we used bifunctional ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles, chemically coupled with Abeta1-42 peptide to image amyloid plaque deposition in the mouse brain. We coupled the nanoparticles to polyethylene glycol (PEG) in order to improve BBB permeability. These USPIO-PEG-Abeta1-42 nanoparticles were injected intravenously in AD model transgenic mice followed by initial and subsequent muMRI. A 3D gradient multi-echo sequence was used for imaging with a 100 microm isotropic resolution. The amyloid plaques detected by T2*-weighted muMRI were confirmed with matched histological sections. The region of interest-based quantitative measurement of T2* values obtained from the muMRI showed contrast injected AD Tg mice had significantly reduced T2* values compared to wild-type mice. In addition, the scans were examined with voxel-based analysis (VBA) using statistical parametric mapping (SPM) for comparison of USPIO-PEG-Abeta1-42 injected AD transgenic and USPIO alone injected AD transgenic mice. The regional differences seen by VBA in the USPIO-PEG-Abeta1-42 injected AD transgenic correlated with the amyloid plaque distribution histologically. Our results indicate that USPIO-PEG-Abeta1-42 can be used for amyloid plaque detection by intravenous injection without the need to co-inject an agent which increases permeability of the BBB. This technique could aid the development of novel amyloid targeting drugs by allowing therapeutic effects to be followed longitudinally in model AD mice.

Alzheimer's disease (AD) is the leading cause for dementia in the world. It is characterized by two biochemically distinct types of protein aggregates: amyloid beta (A beta ) peptide in the forms of parenchymal amyloid plaques and congophilic amyloid angiopathy (CAA) and aggregated tau protein in the form of intraneuronal neurofibrillary tangles (NFT). Several risk factors have been discovered that are associated with AD. The most well-known genetic risk factor for late-onset AD is apolipoprotein E4 (ApoE4) (Potter and Wisniewski (2012), and Verghese et al. (2011)). Recently, it has been reported by two groups independently that a rare functional variant (R47H) of TREM2 is associated with the late-onset risk of AD. TREM2 is expressed on myeloid cells including microglia, macrophages, and dendritic cells, as well as osteoclasts. Microglia are a major part of the innate immune system in the CNS and are also involved in stimulating adaptive immunity. Microglia express several Toll-like receptors (TLRs) and are the resident macrophages of the central nervous system (CNS). In this review, we will focus on the recent advances regarding the role of TREM2, as well as the effects of TLRs 4 and 9 on AD.

CONTEXT: Surgery-induced neuroinflammation has been implicated in the development of postoperative cognitive dysfunction (POCD). OBJECTIVE: To test the hypothesis that meloxicam, a selective cyclooxygenase (COX)-2 inhibitor, preserves postoperative cognitive function and inhibits surgery-induced neuroinflammation in a mouse model. DESIGN: A mouse model of splenectomy-induced inflammation. METHODS: Sixty Swiss Webster male mice (6-8 week old) were randomised into six groups that underwent splenectomy. Animals in groups 1-4 were tested once on day 1, 5, 9 or 14 to determine the time course of delayed transient cognitive dysfunction associated with splenectomy. Animals in groups 5 and 6 were tested once on day 5 or 9 to determine the ability of the NSAID meloxicam to attenuate cognitive dysfunction. INTERVENTION: Animals in groups 1-4 received one dose 500 mul intraperitoneal physiological saline 24 h after splenectomy. Animals in groups 5 and 6 received one dose of intraperitoneal meloxicam (60 mg kg in 500 mul saline) 24 h after splenectomy. MAIN OUTCOME MEASURES: Short-term working memory as determined by Object Recognition Test (ORT) index on days 1, 5, 9 and 14 was the first main outcome. Tomato lectin staining histochemistry of glial cells was assessed on days 1, 5, 9 and 14 as a second main outcome. RESULTS: Compared with day 1 (group 1), the mean ORT indices at day 5 (group 2) and day 9 (group 3) were decreased by 27.5% [95% confidence interval (CI): 0.9 to 54.1%, P = 0.04] and 23.8% (95% CI, 4.3 to 51.9%, P = 0.09), respectively. At day 5 (group 5) and day 9 (group 6), the ORT indices in the meloxicam groups were reduced by 6.6% (95% CI: -11.4 to 24.5%) and 4.3% (95% CI: -25.3 to 34.0). Thus, the administration of meloxicam attenuated the decrease in ORT indices (P = 0.031). Histochemical staining with tomato lectin showed features of microglia activation at day 5 and 9, which was reduced by the administration of meloxicam. CONCLUSION: These findings suggest that COX-2-dependent mechanisms may play a role in the development of POCD. This effect may be dependent on the modulation of glial cell activation.

In the last couple of decades, substantial progress has been made in the development of transgenic mouse models developing amyloid-beta deposits and/or neurofibrillary tangles. These mouse models of Alzheimer's disease and related disorders provide an excellent tool for investigating etiology, pathogenic mechanisms, and potential treatments. An essential component of their characterization is a detailed behavioral assessment, which clarifies the functional consequences of these pathologies. We have selected and refined a series of cognitive and sensorimotor tasks that are ideal for studying these models and the efficacy of various treatments.

Background: Anti-amyloid immunotherapy reduces Ab plaques and prevents cognitive decline in transgenic mouse models of Alzheimer's disease (AD) (Asuni et al, 2006). Nevertheless, in humans, a strategy based on Ab1- 42 peptide induced encephalomyelitis and possibly microhemorrhages (Orgogozo et al, 2003; Ferrer et al, 2004). These outcomes were not expected from studies in rodents. Mouse lemur, as a primate model may be more predictive of human side effects. A small proportion of old animals develop spontaneously Ab plaques (Mestre-Franc-es et al, 2000). Thus this primate models prodromal AD stages, and we used it to evaluate side effects of immunotherapies. Methods: Animals were treated with K6Ab1-30 (n = 4; 5.860.2 years) or Ab1-42 (n = 4; 5.960.2 years) immunogens in alum adjuvant. They were followed-up for 9 months with biochemistry (anti-Ab40 antibodies and Ab40 levels in the plasma), as well as T2-weighted (T2w) and T2-weighted (T2w) MRI (7T PharmaScan-Bruker; resolutions =(234x234x234)mm3. Histological analyses was performed to evaluate amyloidosis, neuroinflammation, and iron deposits/microhemorrhages. Age-associated occurrences of hypointense signals were evaluated in twenty other naive animals (1.5 to 4.9 years). Results: In this particular study, the animals responded mainly to the Ab1-42 immunogen, which differs from our prior study with this Ab derivative (Trouche et al, 2009). This treatment induced an immune response and increased Ab levels in plasma. No severe neuroinflammation were observed (either on MRI or histology). Compared to K6Ab1-30 vaccine, Ab1-42 immunogen increased microhemorrhages (Mann Whitney test U=1, P<0.05) and the size of hypointense signal corresponding to iron deposits in the choroid plexus (CP) (F(2,5)= 4.627; P<0.05). The study in naive lemurs showed that iron accumulates in the CP with normal aging (r=0.60; P<0.001). Hence, immunotherapy with Ab1-42 immunogen accelerated this age-associated phenomenon. Conclusions: Ab-immunization can lead to side effects such as microhemorrhages in a primate model of normal aging or prodromal stage of AD with minimal extracellular Ab deposition. Also, iron accumulation in the CP is a potential side effect of Ab-immunization. This should be taken into account in future evaluations of clinical trials with AD patients

Neurofibrillary tangles (NFTs) are one of the pathological hallmarks of Alzheimer's disease (AD) and are primarily composed of aggregates of hyperphosphorylated forms of the microtubule associated protein tau. It is likely that an imbalance of kinase and phosphatase activities leads to the abnormal phosphorylation of tau and subsequent aggregation. The wide ranging therapeutic approaches that are being developed include to inhibit tau kinases, to enhance phosphatase activity, to promote microtubule stability, and to reduce tau aggregate formation and/or enhance their clearance with small molecule drugs or by immunotherapeutic means. Most of these promising approaches are still in preclinical development whilst some have progressed to Phase II clinical trials. By pursuing these lines of study, a viable therapy for AD and related tauopathies may be obtained