Ultrasound-mediated blood-brain barrier disruption improves anti-pyroglutamate3 Aβ antibody efficacy and enhances phagocyte infiltration into brain in aged Alzheimer’s disease-like mice

AUTHORS

Qiaoqiao Shi, Tao Sun, Yongzhi Zhang, Chanikarn Power, Camilla Hoesch, Shawna Antonelli, Maren K. Schroeder, Barbara J. Caldarone, Nadine Taudte, Mathias Schenk, Thore Hettmann, Stephan Schilling, Nathan J. McDannold, Cynthia A. Lemere

ABSTRACT

Pyroglutamate-3 amyloid-β (pGlu3 Aβ) is an N-terminally modified, toxic form of amyloid-β that is present in cerebral amyloid plaques and vascular deposits. Using the Fc-competent murine anti-pGlu3 Aβ monoclonal antibody (mAb), 07/2a, we present here a nonpharmacological approach using focused ultrasound (FUS) with intravenous (i.v.) injection of microbubbles (MB) to facilitate i.v. delivery of the 07/2a mAb across the blood brain barrier (BBB) in order to improve Aβ removal and restore memory in aged APP/PS1 mice, an Alzheimer’s disease (AD)-like model of amyloidogenesis.

Compared to sham-treated controls, aged APP/PS1 mice treated with 07/2a immediately prior to FUS-mediated BBB disruption (mAb + FUS-BBBD combination treatment) showed significantly better spatial learning and memory in the Water T Maze. FUS-BBBD treatment alone improved contextual fear learning and memory in aged WT and APP/PS1 mice, respectively. APP/PS1 mice given the combination treatment had reduced Aβ42 and pGlu3 Aβ hippocampal plaque burden compared to PBS-treated APP/PS1 mice.

Hippocampal synaptic puncta density and synaptosomal synaptic protein levels were also higher in APP/PS1 mice treated with 07/2a just prior to BBB disruption. Increased Iba-1+ microglia were observed in the hippocampi of AD mice treated with 07/2a with and without FUS-BBBD, and APP/PS1 mice that received hippocampal BBB disruption and 07/2a showed increased Ly6G+ monocytes in hippocampal CA3. FUS-induced BBB disruption did not increase the incidence of microhemorrhage in mice with or without 07/2a mAb treatment.

Our findings suggest that FUS is useful tool that may enhance delivery of an anti-pGlu3 Aβ mAb for immunotherapy. FUS-mediated BBB disruption in combination with the 07/2a mAb also appears to facilitate monocyte infiltration in this AD model. Overall, these effects resulted in greater sparing of synapses and improved cognitive function without causing overt damage, suggesting the possibility of FUS as a noninvasive method to increase the therapeutic efficacy in AD patients.

Sex differences in the incidence and mode of death in rats with heart failure with preserved ejection fraction

AUTHORS

Khaled Elkholey, Lynsie Morris, Monika Niewiadomska, Jeremy Houser, Michelle Ramirez, Mulan Tang, Mary Beth Humphrey, Stavros Stavrakis

ABSTRACT

Heart failure with preserved ejection fraction (HFpEF) accounts for 50% of heart failure, and sudden death is the leading cause of mortality. We aimed to explore sex differences in outcomes in rats with HFpEF and sought to identify the underlying mechanisms. Dahl salt-sensitive rats of either sex were randomized into high-salt diet (HS diet; 8% NaCl, n = 46, 50% female) or low-salt diet (LS diet; 0.3% NaCl; n = 24, 50% female) at 7 weeks of age. After 6 and 10 weeks of LS or HS diets, the ECG, heart rate variability, cytokines and echocardiographic parameters were measured. The animals were monitored daily for development of HFpEF and survival. Over 6 weeks of HS diet, rats developed significant hypertension and signs of HFpEF. Compared with female HS diet-fed rats, males exhibited more left ventricular dilatation, a longer QT interval, and worse autonomic tone, as assessed by heart rate variability and elevated inflammatory cytokines. Ten of 23 (46%) male rats died during follow-up, compared with two of 23 (9%) female rats (P = 0.01). There were four sudden deaths in males (with ventricular tachycardia documented in one rat), whereas the females died of heart failure. In conclusion, male rats with HFpEF exhibit worse survival compared with females and are at a higher risk for sudden death, attributable in part to QT prolongation, autonomic dysregulation and enhanced inflammation. These data might provide the basis for the development of sex-specific interventions in HFpEF targeting these abnormalities.

Interrelationships between Cellular Density, Mosaic Patterning, and Dendritic Coverage of VGluT3 Amacrine Cells

AUTHORS

Patrick W. Keeley, Mikayla C. Lebo, Jordan D. Vieler, Jason J. Kim, Ace J. St. John and Benjamin E. Reese

ABSTRACT

Amacrine cells of the retina are conspicuously variable in their morphologies, their population demographics, and their ensuing functions. Vesicular glutamate transporter 3 (VGluT3) amacrine cells are a recently characterized type of amacrine cell exhibiting local dendritic autonomy. The present analysis has examined three features of this VGluT3 population, including their density, local distribution, and dendritic spread, to discern the extent to which these are interrelated, using male and female mice. We first demonstrate that Bax-mediated cell death transforms the mosaic of VGluT3 cells from a random distribution into a regular mosaic. We subsequently examine the relationship between cell density and mosaic regularity across recombinant inbred strains of mice, finding that, although both traits vary across the strains, they exhibit minimal covariation. Other genetic determinants must therefore contribute independently to final cell number and to mosaic order. Using a conditional KO approach, we further demonstrate that Bax acts via the bipolar cell population, rather than cell-intrinsically, to control VGluT3 cell number. Finally, we consider the relationship between the dendritic arbors of single VGluT3 cells and the distribution of their homotypic neighbors. Dendritic field area was found to be independent of Voronoi domain area, while dendritic coverage of single cells was not conserved, simply increasing with the size of the dendritic field. Bax-KO retinas exhibited a threefold increase in dendritic coverage. Each cell, however, contributed less dendrites at each depth within the plexus, intermingling their processes with those of neighboring cells to approximate a constant volumetric density, yielding a uniformity in process coverage across the population.

The Relationship Between Macula Retinal Ganglion Cell Density and Visual Function in the Nonhuman Primate

AUTHORS

Kwame Antwi-Boasiako; Louvenia Carter-Dawson; Ronald Harwerth; Margaret Gondo; Nimesh Patel

ABSTRACT

Purpose: Loss of ganglion cell inner plexiform layer (GCIPL) and visual sensitivity in the macula region are known to occur at all stages of glaucoma. While both are dependent on the underlying retinal ganglion cells (RGCs), the relationship between structure and function is modest. We hypothesize that the imprecise relationship is due to a lack of direct correspondence between in vivo measures and RGC counts, as well as the relatively large stimulus size used by standard perimetry, which exceeds spatial summation.

Methods: The relationship between optical coherence tomography (OCT)–derived GCIPL thickness and corresponding inner cell density from retinal flat mounts was determined for four nonhuman primates with varying stages of neuropathy. Normative data for 10-2 threshold using Goldman size I to V stimuli were established for 10 animals, 4 of which were then followed longitudinally with OCT and perimetry. The relationship between GCIPL volume, which incorporated stimulus size after removal of residual thickness, and differential light sensitivity was determined for both experimental glaucoma and healthy eyes.

Results: Peak inner retinal cell density was 63,052 ± 9238 cells/mm2 in the healthy eye. Cell density was related to both GCIPL thickness and eccentricity (R2 = 0.74, P < .01). For all 10-2 eccentricities, size III stimuli were greater than the critical area (P < 0.01). Based on the structural and histologic relationship, the critical area corresponds to approximately 156 RGCs.

Conclusions: The relationship between cell density and GCIPL thickness is dependent on retinal eccentricity. For 10-2 perimetry, perimetric loss, especially at earlier stages of neuropathy, may best be detected using size II or smaller stimuli.

A Novel Resorbable Composite Material Containing Poly(ester-co-urethane) and Precipitated Calcium Carbonate Spherulites for Bone Augmentation—Development and Preclinical Pilot Trials

AUTHORS

Claudia Rode, Ralf Wyrwa, Juergen Weisser, Matthias Schnabelrauch, Marijan Vučak, Stefanie Grom, Frank Reinauer, Adrian Stetter, Karl Andreas Schlegel, Rainer Lutz

ABSTRACT

Polyurethanes have the potential to impart cell-relevant properties like excellent biocompatibility, high and interconnecting porosity and controlled degradability into biomaterials in a relatively simple way. In this context, a biodegradable composite material made of an isocyanate-terminated co-oligoester prepolymer and precipitated calcium carbonated spherulites (up to 60% w/w) was synthesized and investigated with regard to an application as bone substitute in dental and orthodontic application. After foaming the composite material, a predominantly interconnecting porous structure is obtained, which can be easily machined. The compressive strength of the foamed composites increases with raising calcium carbonate content and decreasing calcium carbonate particle size. When stored in an aqueous medium, there is a decrease in pressure stability of the composite, but this decrease is smaller the higher the proportion of the calcium carbonate component is. In vitro cytocompatibility studies of the foamed composites on MC3T3-E1 pre-osteoblasts revealed an excellent cytocompatibility. The in vitro degradation behaviour of foamed composite is characterised by a continuous loss of mass, which is slower with higher calcium carbonate contents. In a first pre-clinical pilot trial the foamed composite bone substitute material (fcm) was successfully evaluated in a model of vertical augmentation in an established animal model on the calvaria and on the lateral mandible of pigs.