Despite a robust literature associating IL-31 with pruritic inflammatory skin diseases, its influence on cutaneous inflammation and on the interplay between inflammatory and neurosensory pathways remain unmapped. Here, we examined the effects of IL-31 and its receptor IL31RA on both inflammation and pruritus in mouse models of dermatitis, including chronic topical house dust mite (HDM) exposure. Unexpectedly, Il31 deficiency increased cutaneous adaptive type 2 cytokine-producing cells and serum IgE. In addition, M2-like macrophages capable of fueling feedforward pro-inflammatory loops were selectively enriched in Il31ra-deficient skin. Thus, IL-31 is not strictly a pro-inflammatory cytokine, but rather an immunoregulatory factor that limits the magnitude of allergic skin inflammation. In contrast, Il31-deficient mice displayed a deficit in HDM-induced scratching. Itch reduction occurred despite intact - and in some cases increased - responsiveness of sensory neurons to other pruritogens released during HDM challenge, highlighting the non-redundant contribution of IL-31-receptive sensory afferents to pruritus in environmental allergen-induced dermatitis. When present, therefore, IL-31 uncouples circuits driven by sensory neurons and immune cells that converge in inflamed skin.

Background: The kidney is a highly complex organ that performs multiple functions necessary to maintain systemic homeostasis, with complex interplay from different kidney sub-structures and the coordinated response of diverse cell types, few known and likely many others, as yet undiscovered. Traditional global sequencing techniques are limited in their ability to identify unique and functionally diverse cell types in complex tissues. Methods: Herein we characterize over 45,000 cells from 10 normal human kidneys using unbiased single-cell RNA sequencing. We also apply, for the first time, an approach of multiplexing kidney samples (Mux-Seq), pooled from different individuals, to save input sample amount and cost. We applied the computational tool Demuxlet to assess differential expression across multiple individuals by pooling human kidney cells for scRNA sequencing, utilizing individual genetic variability to determine the identity of each cell. Results: Multiplexed droplet single-cell RNA sequencing results were highly correlated with the singleplexed sample run data. One hundred distinct cell cluster populations in total were identified across the major cell types of the kidney, with varied functional states. Proximal tubular and collecting duct cells were the most heterogeneous, displaying multiple clusters with unique ontologies. Novel proximal tubular cell subsets were identified with regenerative potential. Trajectory analysis demonstrated evolution of cell states between intercalated and principal cells in the collecting duct. Conclusions: Healthy kidney tissue has been successfully analyzed to detect all known renal cell types, inclusive of resident and infiltrating immune cells in the kidney. Mux-Seq is a unique method that allows for rapid and cost-effective single cell, in depth, transcriptional analysis of human kidney tissue. .