Biology subjects

Nehete, P. N.

Publications and source records attributed to Nehete, P. N..

5 recordsLinked to original sources

bioRxiv2026

Integration of Neuroimaging and Histopathology in a Squirrel Monkey Model of Spontaneous Cerebral Amyloid Angiopathy and Amyloid-Related Imaging Abnormalities

Cerebral amyloid angiopathy (CAA) is a prevalent cerebrovascular pathology in AD and contributes to amyloid-related imaging abnormalities (ARIA), a major complication of current anti-amyloid immunotherapy. Despite its growing clinical importance, critical gaps remain in the development of reliable biomarkers for antemortem diagnosis of CAA. Squirrel monkeys (SQMs) are a valuable non-human primate model with translational relevance due to their universal propensity to develop abundant CAA and spontaneous ARIA in geriatric animals. The present study employed R2*, the apparent transverse relaxation rate, which is sensitive to susceptibility-related tissue properties, including iron content and blood oxygenation levels, to monitor age-related brain pathology in SQMs with varying CAA severity. Young, early geriatric, and late geriatric SQMs underwent 7T MRI using a dual-purpose T2*-w 3D multi-gradient-echo sequence for high-resolution anatomy and quantitative R2* mapping, alongside T2-w/FLAIR imaging. Whole-brain and gray matter R2* increased with age. In contrast, white matter R2* showed an initial increase followed by a late-life reversal, likely reflecting age-related changes in myelin integrity, tissue microstructure, and tissue water content. MRI-histopathology correlation linked T2*-w MRI hypointensities to CAA-positive iron-laden vessels associated with perivascular inflammation and, in some cases, hemosiderin deposits. Here we confirmed the occurrence of ARIA-H and ARIA-E events in geriatric animals. SQMs provided a valuable opportunity to examine the underlying pathology of spontaneous ARIA-E, revealing distinctive tissue signatures associated with its manifestation. ARIA-E hyperintensities were characterized by reactive gliosis and BBB disruption, whereas more advanced lesions exhibited perivascular lymphocytic infiltration and evidence of myelin and axonal injury. The current study presents compelling evidence linking R2* alterations with CAA severity and ARIA-related tissue injury, providing a foundation for further advancing early detection of CAA, ARIA risk assessment, and treatment strategies.

neuroscience↗

bioRxiv2022

Ultra-long-acting refillable nanofluidic implant confers full protection against SHIV infection in non-human primates

The impact of pre-exposure prophylaxis (PrEP) on slowing the global human immunodeficiency virus (HIV) epidemic hinges on effective drugs and delivery platforms. Oral regimens have represented the pillar of HIV PrEP for years. However, variable adherence has spurred development of long-acting delivery systems, which also aim at increasing PrEP access, uptake and persistence. Here we present an ultra-long-acting and transcutaneously refillable subcutaneous nanofluidic implant for constant and sustained release of islatravir (ISL), a nucleoside reverse transcriptase translocation inhibitor, for HIV PrEP. In rhesus macaques, the ISL-eluting implants (nISL) achieved constant plasma ISL levels (median 3.14 nM) and peripheral blood mononuclear cells (PBMCs) ISL-triphosphate levels (ISL-TP) (median 0.16 pmol/106 cells) for over 20 months uninterrupted. These drug concentrations are above the established PrEP protection threshold. In two non-blinded, placebo-controlled studies with repeated low-dose rectal and vaginal SHIVSF162P3 challenges in male and female rhesus macaques, respectively, nISL implants conferred 100% protection against infection (p=0.0005 and 0.0009, respectively between nISL and placebo control groups). The nISL implants were well tolerated with mild local tissue inflammation and no signs of systemic toxicity over the 20-month period. Overall, our refillable nISL implant is a promising ultra-long-acting delivery technology for HIV PrEP. One Sentence SummaryAn ultra-long-acting and subcutaneous refillable nanofluidic implant achieved preventive levels of islatravir in non-human primates for 20 months without refilling and conferred 100% protection against rectal and vaginal SHIV transmission.

bioengineering↗

bioRxiv2020

Effects of relocation on Immunological and physiological measures in squirrel monkeys ( Saimiri boliviensis boliviensis)

In the present study, we have quantified the effects of transport, relocation and acclimate/adapt to their new surroundings on squirrel monkey. These responses are measured in blood samples obtained from squirrel monkeys, at different time points relative to their relocation from their old home to their new home. A variety of immunological assays are performed on the phenotype and function of peripheral blood mononuclear cells (PBMCs) in a group of squirrel monkeys that were transported by road for approximately 10 hours from one facility to another. Using a panel of human antibodies and a set of standardized human immune assays, we evaluated the phenotype of lymphocyte subsets by flow, mitogen-specific immune responses of PBMCs in vitro, and levels of cytokines at various time points including immediately before transport, immediately upon arrival, and after approximately 150 days of acclimation. We observed significant changes in T cells and subsets, NK and B cells (CD4+, CD8+, CD4+/CD8+, CD16+, and CD20+). Mitogen specific (e.g. PHA, PWM and LPS) proliferation responses, IFN-g by ELISPOT assay, and cytokines (IL-2, IL-4 and VEGF) significant changes were observed. Changes seen in the serum chemistry measurements mostly complement those seen in the hematology data. The specific goal was to empirically assess the effects of relocation stress in squirrel monkeys in terms of changes in the numbers and functions of various leukocyte subsets in the blood and the amount of time require for acclimating to their new environment. Such data will help to determine when newly arrived animals become available for use in research studies.

immunology↗

bioRxiv2020

Preventive efficacy of a tenofovir alafenamide fumarate nanofluidic implant in SHIV-challenged nonhuman primates

Pre-exposure prophylaxis (PrEP) using antiretroviral oral drugs is effective at preventing HIV transmission when individuals adhere to the dosing regimen. Tenofovir alafenamide (TAF) is a potent antiretroviral drug, with numerous long-acting (LA) delivery systems under development to improve PrEP adherence. However, none has undergone preventive efficacy assessment. Here we show that LA TAF using a novel subcutaneous nanofluidic implant (nTAF) confers partial protection from HIV transmission. We demonstrate that sustained subcutaneous delivery through nTAF in rhesus macaques maintained tenofovir diphosphate concentration at a median of 390.00 fmol/106 peripheral blood mononuclear cells, 9 times above clinically protective levels. In a non-blinded, placebo-controlled rhesus macaque study with repeated low-dose rectal SHIVSF162P3 challenge, the nTAF cohort had a 62.50% reduction (95% CI: 1.72% to 85.69%; p=0.068) in risk of infection per exposure compared to the control. Our finding mirrors that of tenofovir disoproxil fumarate (TDF) monotherapy, where 60.00% protective efficacy was observed in macaques, and clinically, 67.00% reduction in risk with 86.00% preventive efficacy in individuals with detectable drug in the plasma. Overall, our nanofluidic technology shows potential as a subcutaneous delivery platform for long-term PrEP and provides insights for clinical implementation of LA TAF for HIV prevention.

bioengineering↗

bioRxiv2018

Comparative analysis of cellular immune responses in conventional and SPF Baboons (Papio spp.)

Baboons (papio spp.) have served as a successful model of human disease such as cardiac and respiratory, infectious, diabetes, genetics, immunology, aging, and xenotransplantation. The development of an immunologically defined specific-pathogen free (SPF) baboon model has further advanced research, especially with studies involving the immune system and immunosuppression. In this study, we compare normal immunological changes of peripheral blood mononuclear cell (PBMC) subsets, and their function in age-matched conventional and SPF baboons. Our results demonstrate that both groups have comparable numbers of different lymphocyte subsets, but there are phenotypic differences in central and effector memory T cells subsets that are more pronounced in the CD4+ T cells. Despite equal proportions of CD3+ T cells among the conventional and SPF baboon groups, PBMC show higher proliferative responses to mitogens PHA and PWM and higher IFN-{gamma} producing cells to Con A and PWM in the conventional group. Plasma levels of the inflammatory cytokine TNF- were significantly higher in SPF baboons. Exposure of PBMC from conventional baboons to various Toll like ligands (TLR ligands) TLR-3, TLR-4 and TLR-8 show higher IFN-{gamma} producing cells while PBMC from SPF baboons stimulated with TLR-5 and TLR-6 ligand show higher IFN-{gamma} producing cells. These findings suggest that while the lymphocyte subsets in conventional and SPF baboons share many phenotypic and functional similarities, specific differences exist in immune function of lymphocytes which could impact the quality and quantity of innate and adaptive immune responses. These differences should be considered for better experimental outcomes, specifically in studies measuring immunological endpoints.

immunology↗