CCR6-Dependent Positioning of Memory B Cells Is Essential for Their Ability To Mount a Recall Response to Antigen

Chemokine-dependent localization of specific B cell subsets within the immune microarchitecture is essential to insure successful cognate interactions. While cognate interactions between T cells and memory B cells (B(mem))() are essential for the secondary humoral immune responses, the chemokine response patterns of B(mem) cells are largely unknown. In contrast to naïve B cells, this study shows that antigen-specific B(mem) cells have heightened expression of CCR6 and a selective chemotactic response to the CCR6 ligand, CCL20. While CCR6 appears be non-essential for the initial clonal expansion and maintenance of B(mem), CCR6 is essential for the ability of B(mem) to respond to a recall response to their cognate antigen. This dependency was deemed intrinsic by studies in CCR6-deficient mice and in bone-marrow chimeric mice where CCR6 deficiency was limited to the B cell lineage. Finally, the mis-positioning of CCR6-deficient B(mem) was revealed by immunohistological analysis with an altered distribution of CCR6-deficient B(mem) from the marginal and perifollicular to the follicular/germinal center area

Hearing loss and brain plasticity: the hyperactivity phenomenon

Many aging adults experience some form of hearing problems that may arise from auditory peripheral damage. However, it has been increasingly acknowledged that hearing loss is not only a dysfunction of the auditory periphery but also results from changes within the entire auditory system, from periphery to cortex. Damage to the auditory periphery is associated with an increase in neural activity at various stages throughout the auditory pathway. Here, we review neurophysiological evidence of hyperactivity, auditory perceptual difficulties that may result from hyperactivity, and outline open conceptual and methodological questions related to the study of hyperactivity. We suggest that hyperactivity alters all aspects of hearing—including spectral, temporal, spatial hearing—and, in turn, impairs speech comprehension when background sound is present. By focusing on the perceptual consequences of hyperactivity and the potential challenges of investigating hyperactivity in humans, we hope to bring animal and human electrophysiologists closer together to better understand hearing problems in older adulthood