Quantitative Comparison of Conventional and t-SNE-guided Gating Analyses

Dimensionality reduction using the t-Distributed Stochastic Neighbor Embedding (t-SNE) algorithm has emerged as a popular tool for visualizing high-parameter single-cell data. While this approach has obvious potential for data visualization it remains unclear how t-SNE analysis compares to conventional manual hand-gating in stratifying and quantitating the frequency of diverse immune cell populations. We applied a comprehensive 38-parameter mass cytometry panel to human blood and compared the frequencies of 28 immune cell subsets using both conventional bivariate and t-SNE-guided manual gating. t-SNE analysis was capable of stratifying every general cellular lineage and most sub-lineages with high correlation between conventional and t-SNE-guided cell frequency calculations. However, specific immune cell subsets delineated by the manual gating of continuous variables were not fully separated in t-SNE space thus causing discrepancies in subset identification and quantification between these analytical approaches. Overall, these studies highlight the consistency between t-SNE and conventional hand-gating in stratifying general immune cell lineages while demonstrating that particular cell subsets defined by conventional manual gating may be intermingled in t-SNE space.

Pharmacology of AMG 181, a human anti-α4 β7 antibody that specifically alters trafficking of gut-homing T cells

BACKGROUND AND PURPOSE

AMG 181 is a human anti-α4 β7 antibody currently in phase 1 and 2 trials in subjects with inflammatory bowel diseases. AMG 181 specifically targets the α4 β7 integrin heterodimer, blocking its interaction with mucosal addressin cell adhesion molecule-1 (MAdCAM-1), the principal ligand that mediates α4 β7 T cell gut-homing.

EXPERIMENTAL APPROACH

We studied the in vitro pharmacology of AMG 181, and the pharmacokinetics and pharmacodynamics of AMG 181 after single or weekly i.v. or s.c. administration in cynomolgus monkeys for up to 13 weeks.

KEY RESULTS

AMG 181 bound to α4 β7 , but not α4 β1 or αE β7 , and potently inhibited α4 β7 binding to MAdCAM-1 (but not vascular cell adhesion molecule-1) and thus inhibited T cell adhesion. Following single i.v. administration, AMG 181 Cmax was dose proportional from 0.01 to 80 mg·kg(-1) , while AUC increased more than dose proportionally. Following s.c. administration, dose-proportional exposure was observed with single dose ranging from 5 to 80 mg·kg(-1) and after 13 weekly doses at levels between 20 and 80 mg·kg(-1) . AMG 181 accumulated two- to threefold after 13 weekly 80 mg·kg(-1) i.v. or s.c. doses. AMG 181 had an s.c. bioavailability of 80%. The linear elimination half-life was 12 days, with a volume of distribution close to the intravascular plasma space. The mean trend for the magnitude and duration of AMG 181 exposure, immunogenicity, α4 β7 receptor occupancy and elevation in gut-homing CD4+ central memory T cell count displayed apparent correlations.

CONCLUSIONS AND IMPLICATIONS

AMG 181 has in vitro pharmacology, and pharmacokinetic/pharmacodynamic and safety characteristics in cynomolgus monkeys that are suitable for further investigation in humans.

BGC20-761, a novel tryptamine analog, enhances memory consolidation and reverses scopolamine-induced memory deficit in social and visuospatial memory tasks through a 5-HT6 receptor-mediated mechanism

Inhibition of 5-HT(6) receptors has been shown to improve memory consolidation, thus we tested whether a novel tryptamine analog with high affinity for 5-HT(6) receptors, BGC20-761 (5-methoxy-2-phenyl-N,N-dimethyltryptamine, PMDT), can enhance long-term memory. BGC20-761 (10 mg/kg i.p.) alone had no effect on social recognition in young rats, however, at doses of 5 mg/kg and 10 mg/kg i.p, BGC20-761 dose-dependently reversed a deficit of social recognition induced by scopolamine (0.4 mg/kg i.p.), an anticholinergic drug that impairs memory. BGC20-761 (10 mg/kg i.p.), scopolamine (0.2 mg/kg i.p.) or BGC20-761 + scopolamine had no effects on novel object discrimination in young rats (2 months). In mature rats (6 months), recognition of the novel object was improved following administration of BGC20-761. Scopolamine had no effect in object recognition. However, the addition of scopolamine disrupted the memory-enhancing effect of BGC20-761. Based on the high affinity of BGC20-761 for 5-HT(6) receptors, these cognitive enhancing effects are most likely mediated by 5-HT(6) receptor inhibition. The difference in effects of BGC20-761 in young vs. mature rats may reflect the status of memory consolidation in these different age ranges.