Update on Mast Cell Biology.

Mast cells (MCs) are heterogeneous tissue-resident effector cells thought to play central roles in allergic inflammatory disease, yet the degree of heterogeneity and nature of these roles has remained elusive. In recent years, advances in tissue culture systems, pre-clinical mouse models, and the continued spread of single-cell RNA sequencing has greatly advanced our understanding of MC phenotypes in health and disease. These approaches have identified novel interactions of MC subsets with immune cells, neurons, and tissue structural cells, changing our understanding of how MCs both drive and help resolve tissue inflammation, reshape tissue microenvironments, and influence host behavior.

Human intraepithelial mast cell differentiation and effector function are directed by TGF-β signaling.

Mast cells (MCs) expressing a distinctive protease phenotype (MCTs) selectively expand within the epithelium of human mucosal tissues during type 2 (T2) inflammation. While MCTs are phenotypically distinct from subepithelial MCs (MCTCs), signals driving human MCT differentiation and this subset's contribution to inflammation remain unexplored. Here, we have identified TGF-β as a key driver of the MCT transcriptome in nasal polyps.

Apparent statistical inference in crows may reflect simple reinforcement learning.

Johnston et al. report results which they argue demonstrate that crows engage in statistical inference during decision-making. They trained two crows to associate a set of stimuli with different reward probabilities (from 10% to 90%) before choice tests between pairs of stimuli.