Biology subjects

Cook, K. D.

Publications and source records attributed to Cook, K. D..

3 recordsLinked to original sources

bioRxiv2025

Targeting Modulated Vascular Smooth Muscle Cells in Atherosclerosis via FAP-Directed Immunotherapy

Vascular smooth muscle cell (VSMC) and immune cell diversification play a central role in driving atherosclerotic coronary artery disease (CAD)1-3. However, the molecular mechanisms governing cell state transitions within the neo-intima in human CAD remain poorly understood, and no lipid-independent therapies are currently approved for its treatment. Here, we performed multi-omic single-cell gene expression profiling, epitope mapping, and spatial transcriptomics from 27 human coronary arteries. Our analysis identified fibroblast activation protein (FAP) as a marker of modulated VSMCs within the neo-intima. Genetic lineage tracing in mice confirmed that FAP cells in the plaque originate from medial VSMCs. Additionally, non-invasive positron emission tomography (PET) imaging in patients with CAD revealed focal FAP uptake in atherosclerotic lesions. Spatial transcriptomics further delineated the distinct localization of VSMC and immune cell subsets within plaques, with FAP states enriched in the neo-intima. To explore the therapeutic potential of targeting de-differentiated VSMCs, we developed an anti-FAP bispecific T-cell engager (BiTE) and demonstrated that it significantly reduced the plaque burden in multiple mouse models of atherosclerosis. Collectively, our study provides the first single-cell and spatially resolved map of human CAD, establishes FAP as a marker of modulated smooth muscle cells, and demonstrates the broader potential of immunotherapeutics for lipid independent targets in atherosclerotic CAD.

genomics↗

bioRxiv2024

Multiplexed functional analysis of TAP2 variants in regulating MHC-I cell surface abundance reveals overexpression of PLK1 downregulates antigen presentation.

The abundance of MHC-I on the cell surface depends on its association with antigenic peptides transported to the endoplasmic reticulum by the Transporter Associated with Antigen Processing (TAP), a peptide channel composed of TAP1 and TAP2. We functionally screened over 1400 TAP2 variants for effects on MHC-I cell surface abundance. Amino-acid substitutions of loss of function (LOF) variants clustered in the NTP-binding domain and along the TAP1-TAP2 binding interface, suggesting that these variants interfered with TAP conformational changes associated with peptide transport. Some LOF variants carried potential phosphomimetic substitutions; one such substitution at Ser251 was embedded in a sequence context consistent with the phosphorylation motif of PLK kinases. Inhibition of PLK kinases increased MHC-I surface expression, while overexpression of PLK1 in cells decreased MHC-I in wild type TAP2, but not in TAP2-S251A-expressing cells. Importantly, site-specific phosphorylation of TAP2 in human tumor samples correlated with alterations of gene expression in the cell cycle and antigen presentation pathways, consistent with the notion that phosphorylation downregulates antigenic peptide transport in human tumors. These data strongly support the hypothesis that in cancer cells, TAP2 phosphorylation by PLK1, and perhaps other kinases, can downregulate the antigen presentation process.

cancer biology↗

bioRxiv2024

Utility of Cellular Measurements of Non-Specific Endocytosis to Assess the Target-Independent Clearance of Monoclonal Antibodies

Past studies have demonstrated higher clearance for monoclonal antibodies possessing increased rates of non-specific endocytosis. However, this metric is oftentimes evaluated indirectly using biophysical techniques or cell surface binding studies that may not provide insight into the specific rates of cellular turnover. Furthermore, few examples evaluating non-specific endocytosis have been reported for a therapeutic antibody that reached clinical assessment. In the current report, we evaluated a therapeutic human immunoglobulin G2 monoclonal antibody targeted against the interleukin-4 receptor alpha chain (IL-4R) that exhibited elevated target independent clearance in previous Phase 1 and 2 studies. We confirmed high non-specific clearance of the anti-IL-4R antibody as compared to a reference antibody during pharmacokinetic assessments in wild type mice where target-mediated disposition was absent. We then developed a cell-based method capable of measuring cellular protein endocytosis and demonstrated the anti-IL-4R antibody exhibited marked non-specific uptake relative to the reference compound. Antibody homology modeling identified the anti-IL-4R antibody possessed positive charge patches whose removal via targeted mutations substantially reduced its non-specific endocytosis. We then expanded the scope of the study by evaluating a panel of consisting of both preclinical and clinical monoclonal antibodies and demonstrate those with the highest rates of non-specific uptake in vitro exhibit elevated target independent clearance, low subcutaneous bioavailability, or both. Our results support the observation that high non-specific endocytosis is a negative attribute in monoclonal antibody development and demonstrate the utility of a generic cell-based screen as a quantitative tool to measure non-specific endocytosis of protein therapeutics at the single-cell level. Highlights- Developed a novel, reproducible cellular assay to directly quantify non-specific endocytosis of therapeutic proteins. - A previous clinical candidate monoclonal antibody with rapid target-independent clearance in mice and humans possessed extensive non-specific endocytosis that was due to exposed positive charge features. - Demonstration of distinct rates of endocytosis into mammalian cells for disparate monoclonal antibodies, even those with common specificity for targets or isoelectric points. - Cell-based assay to quantify the potential impact of non-specific endocytosis on target-independent clearance and/or subcutaneous bioavailability of monoclonal antibodies.

biochemistry↗