Anti-CD14 Monoclonal antibody, clone Tb3-9 [PerCP/Cy5.5®]

As cancer strategies shift toward immunotherapy, the need for new binding ligands to target and isolate specific immune cell populations has soared. Based on prior work identifying a peptide specific for murine M2-like macrophages, we sought to identify an aptamer that could bind human M2-like macrophages. Tumor-associated macrophages (TAMs) adopt an M2-like phenotype and support tumor progression and dissemination. Here, we employed cell-SELEX to identify an aptamer ligand that targets this cell population over tissue resident (M0-like) or tumoricidal (M1-like) macrophages. Instead, we identified an aptamer that binds both human M0- and M2-like macrophages and monocytes, with highest binding affinity to M2-like macrophage (K-d similar to 20 nM) and monocytes (K-d similar to 45 nM) and minimal binding to other leukocytes. The aptamer binds to CD14(+) but not CD16(+) monocytes, and is rapidly internalized by these cells. We also demonstrate that this aptamer is able to bind human monocytes when both are administered in vivo to mice. Thus, binding to these cell populations (monocytes, M0-like and M2-like macrophages), this aptamer lends itself toward monocyte-specific applications, such as monocyte-targeted drug delivery or column selection.

BackgroundNatural products may provide a source for the discovery and development of adjunctive pharmacological interventions to modulate the inflammatory pathways contributing to chronic disease. Xanthohumol, a flavonoid from the hops plant (Humulus lupulus), has antioxidant and anti-inflammatory properties and may act as a prebiotic to the intestinal microbiota. Xanthohumol is not currently approved as a drug by the US Food and Drug Administration (FDA), but is available as a dietary supplement and ingredient in medical foods. To formally test the safety of xanthohumol, a phase I clinical trial ("XMaS") was designed and approved under an Investigational New Drug application to the US FDA. The main objective is to examine the clinical safety and subjective tolerability of xanthohumol in healthy adults compared to placebo. Additional aims are to monitor biomarkers related to inflammation, gut permeability, bile acid metabolism, routes, and in vivo products of xanthohumol metabolism, and to evaluate xanthohumol's impact on gut microbial composition.MethodsThe safety and tolerability of xanthohumol in healthy adults will be evaluated in a triple-masked, randomized, placebo-controlled trial. Participants will be randomized to either 24mg/day of xanthohumol or placebo for 8 weeks. Blood cell counts, hepatic and renal function tests, electrolytes, and self-reported health-related quality of life measures will be collected every 2 weeks. Participants will be queried for adverse events throughout the trial. Xanthohumol metabolites in blood, urine, and stool will be measured. Biomarkers to be evaluated include plasma tumor necrosis factor-alpha, various interleukins, soluble CD14, lipopolysaccharide-binding protein, fecal calprotectin, and bile acids to assess impact on inflammatory and gut permeability-related mechanisms in vivo. Stool samples will be analyzed to determine effects on the gut microbiome.DiscussionThis phase I clinical trial of xanthohumol will assess safety and tolerability in healthy adults, collect extensive biomarker data for assessment of potential mechanism(s), and provide comparison data necessary for future phase II trials in chronic disease(s). The design and robustness of the planned safety and mechanistic evaluations planned provide a model for drug discovery pursuits from natural products.Trial registrationClinicalTrials.gov NCT03735420. Registered on November 8, 2018