Michael Mullan, M.B.B.S., Ph.D. - US grants

DESCRIPTION (provided by applicant): The over-arching area of enquiry of the original RO1 (AG19250) was to understand the origin of the cerebrovascular abnormalities characteristic of Alzheimer's Disease (AD). Numerous structural and functional cerebromicrovascular abnormalities have been identified in AD subjects, including decreased capillary diameter and microvessel density, thinning of capillary basement membrane, attenuation of capillary endothelium and cerebrovascular muscle atrophy supporting the possibility of an alternation of the angiogenic process in AD brain. Microvessels undergoing angiogenesis and sprouting, normally proliferate by growth of the endothelium, which subsequently secretes the basement membrane. The opposite result has been observed in Alzheimer's disease, where microvessels associated with Abeta deposits displayed non-functional endothelium along with thinning of the basement membrane. To understand how the cerebrovascular pathological abnormalities of AD occur we first focused on the prostaglandin producing pro-inflammatory sPLA2-MAPK-cPLA2-AA-LOX/COX pathway is activated in the vasculature which we have shown is activated by low doses of freshly solubilized Abeta. The specific aims of the current proposal have arisen directly from our observations made in R01 NIA-AG19250 the results of which are detailed below. Observation that the sPLA2-MAPK-cPLA2-AA-LOX-COX pathway is activated in the vasculature by Abeta load us to the question of whether Abeta could stimulate an imflammatory angiogenesis. Surprisingly we found that although at low doses of Abeta there is evidence that Aa can stimulate angiogenesis at higher doses (with greater aggregation of Abeta) a profound anti-angiogenic response occurs. We have explored the anti-angiogenic response of Abeta for two distinct reasons: firstly it could account for some of the pathological cerebrovascular pathologies observed in the course of the AD process and secondly Abeta or related peptides may be a potential candidate for anti-tumor therapies based on it's antiangiogenic properties. The purpose of this proposal is to increase our understanding of how and why Abeta has such potent anti-angiogenic properties.

Abstract: Karenia brevis (K. brevis), the microalgae responsible for Red Tide harmful algal blooms, regularly releases a suite of potent neurotoxic brevetoxins in southwest Florida and is intermittently responsible for massive marine life morbidity and mortality. While these blooms have been documented in the Gulf of Mexico since the 16th century, evidence suggests that their frequency and intensity have been increasing in recent decades, most likely driven by human development in Florida and higher Gulf water temperatures. Although the acute negative consequences of Red Tide exposure on pulmonary health in humans are relatively well-documented, recent studies of ER admissions during Red Tide blooms also demonstrate increased diagnoses of neurological conditions. The impact on the central nervous system of repeat exposure of brevetoxin in humans is not known, but frequent exposure to the closely-related ciguatoxin can result in chronic neurological illness including conditions similar to chronic fatigue syndrome. Furthermore, other chronically exposed mammals, like manatees and dolphins, display a wide variety of neurological signs most likely due to the known mechanism of action of brevetoxins on voltage-gated ion channels in the peripheral and central nervous systems. One of the longest Red Tide blooms on record, November 2017 to February 2019, exposed southwest Florida residents to prolonged and intense aerosolized brevetoxin levels. We have begun enrolling volunteer residents from the two-county region of Manatee and Sarasota (collectively ?Manasota?) who were differentially exposed during this bloom by virtue of their home or work locations. These subjects have provided demographic, health history, and zone/activity information as well as biological samples. These subjects will be part of the cohort that we would like to follow over 18 months during periods of absence or presence of subsequent blooms. The cohort recruitment will be completed with volunteers who live in coastal regions as well as those who live further inland and who will have experienced much lower, or no, brevetoxin aerosol exposure. We will correlate their exposure to aerosolized brevetoxins with neurological diagnoses. Furthermore, we will examine biomarkers of brevetoxin exposure in relation to the same neurological sequelae. The purpose of this study is to determine how exposure relates to neurological diagnoses and to begin to characterize differences between those that develop neurological diagnoses and those that do not. For instance, exposure dose, duration, or markers of immune response may predict neurological outcomes. This work will be the first to provide longitudinal data on the neurological consequences of repeat brevetoxin exposure, generate a cohort for the examination of long-term outcomes and will establish a biorepository for studies of brevetoxin exposure and human health.