A spatial multi-omics atlas of the human lung reveals a novel immune cell survival niche

Multiple distinct cell types of the human lung and airways have been defined by single cell RNA sequencing (scRNAseq). Here we present a multi-omics spatial lung atlas to define additional heterogeneity and novel cell types which we map back into the macro- and micro-anatomical tissue context to define functional tissue microenvironments. First, we have generated a single cell and nuclei RNA sequencing, VDJ-sequencing and Visium Spatial Transcriptomics data set from 5 different locations of the human lung and airways. Second, we define additional cell types/states, as well as spatially map novel and known human airway cell types, such as chondrocytes, submucosal gland (SMG) duct cells, distinct pericyte and smooth muscle subtypes, immune-recruiting fibroblasts, peribronchial and perichondrial fibroblasts, peripheral nerve associated fibroblasts and Schwann cells. Finally, we define a survival niche for IgA-secreting plasma cells at the SMG, comprising the newly defined epithelial SMG-Duct cells, and B and T lineage immune cells. Using our transcriptomic data for cell-cell interaction analysis, we propose a signalling circuit that establishes and supports this niche. Overall, we provide a transcriptional and spatial lung atlas with multiple novel cell types that allows for the study of specific tissue microenvironments such as the newly defined gland-associated lymphoid niche (GALN).

The vasoconstrictor endothelin system involvement in chronic kidney diseases pathogenesis is now the most often employed treatment method

Over 30,000 publications have been published about the vasoconstrictor endothelin-1, which was identified by Yanagisawa and co-workers in 1988. While the evidence is quite compelling, scientists can only speculate on how the endothelin (ET) system affects blood pressure and renal function at this time. ET system involvement in chronic kidney diseases (CKD) pathogenesis is now the most often employed treatment method. ET1, ET2, and ET3 are all members of the endothelin family. Endothelium, renal, and smooth muscle cells all generate ET-1, a significant isoform found in both cardiovascular and renal systems.Kidney cells act on, and contain, ET-1. The ETA receptor is found in the brain and medulla, but not in the vasa recta or glomeruli. Epithelial and endothelial cells contain the ETB receptor, which is most prominent in collecting duct cells. 3 In several experiments, ET-1 has been established to be largely a preglomerular vasoconstrictor. Mesangial proliferation, contraction, and collagen production are regulated by ET-1 and ETB receptors in podocytes. The epithelium in the collecting duct cells in the medulla is important in controlling Na excretion and BP. Without the ET-1 gene, the mice have hypertension and reduced natriuresis in response to salt loading. Et-1, ETB receptor, and hypertension are shown in mice that have lost the ETB receptor gene. There is no correlation between blood pressure regulation and natriuresis.Combined disruption of the ETA and ETB receptors has greater effects on blood pressure and Na reabsorption than when ETB receptor activity is missing. It appears that the ETB receptor doesn't work until ETB is present. Collecting duct-derived ET receptors reduces the transport of sodium. Src kinase and MAPK1/2 decrease epidermal Na channel (ENaC) function, decreasing water and salt reabsorption. Moreover, inner medullary collecting duct cells and vasa recta-bearing cells will release NO, which decreases sodium transport.

Gender-Dependent Phenotype in Polycystic Kidney Disease Is Determined by Differential Intracellular Ca2+ Signals

Autosomal dominant polycystic kidney disease (ADPKD) is caused by loss of function of PKD1 (polycystin 1) or PKD2 (polycystin 2). The Ca2+-activated Cl− channel TMEM16A has a central role in ADPKD. Expression and function of TMEM16A is upregulated in ADPKD which causes enhanced intracellular Ca2+ signaling, cell proliferation, and ion secretion. We analyzed kidneys from Pkd1 knockout mice and found a more pronounced phenotype in males compared to females, despite similar levels of expression for renal tubular TMEM16A. Cell proliferation, which is known to be enhanced with loss of Pkd1−/−, was larger in male when compared to female Pkd1−/− cells. This was paralleled by higher basal intracellular Ca2+ concentrations in primary renal epithelial cells isolated from Pkd1−/− males. The results suggest enhanced intracellular Ca2+ levels contributing to augmented cell proliferation and cyst development in male kidneys. Enhanced resting Ca2+ also caused larger basal chloride currents in male primary cells, as detected in patch clamp recordings. Incubation of mouse primary cells, mCCDcl1 collecting duct cells or M1 collecting duct cells with dihydrotestosterone (DHT) enhanced basal Ca2+ levels and increased basal and ATP-stimulated TMEM16A chloride currents. Taken together, the more severe cystic phenotype in males is likely to be caused by enhanced cell proliferation, possibly due to enhanced basal and ATP-induced intracellular Ca2+ levels, leading to enhanced TMEM16A currents. Augmented Ca2+ signaling is possibly due to enhanced expression of Ca2+ transporting/regulating proteins.

Hnf1b-CreER, a model used for fate mapping pancreatic lineages, achieves efficient Cre-mediated recombination in duct and islet δ cells

The Hnf1b-CreERT2 BAC transgenic (Tg(Hnf1b-cre/ERT2)1Jfer) has been used extensively to trace the progeny of pancreatic ducts in development, regeneration, or cancer. This model originally showed that duct-like plexus cells of the embryonic pancreas are bipotent duct-endocrine progenitors, whereas adult mouse duct cells are not a common source of δ cells in various regenerative settings. We have now examined Hnf1b-CreERT2 mice with a Rosa26-RFP reporter transgene. This showed inducible recombination of up to 96% adult duct cells, a much higher efficiency than the previously used β-galactosidase reporter. Despite this high duct-cell excision, recombination in α and β cells remained very low, similar to the previously used reporter transgene (Rosa26-βgalactosidase). However, nearly half of somatostatin-expressing δ cells showed reporter activation, which was due to Cre expression in δ cells rather than an indication of duct to δ cell conversions. The high recombination efficiency in duct cells indicates that the Hnf1b-CreERT2 model can be useful for both ductal fate mapping and genetic inactivation studies. The recombination in δ cells does not modify the interpretation of studies that failed to show duct conversions to other cell types, but needs to be considered in studies that use this model to modify the plasticity of pancreatic duct cells.

Single cell transcriptome analysis defines heterogeneity of the murine pancreatic ductal tree

To study disease development, an inventory of an organ's cell types and understanding of physiologic function is paramount. Here, we performed single-cell RNA sequencing to examine heterogeneity of murine pancreatic duct cells, pancreatobiliary cells, and intrapancreatic bile duct cells. We describe an epithelial-mesenchymal transitory axis in our three pancreatic duct subpopulations and identify osteopontin as a regulator of this fate decision as well as human duct cell dedifferentiation. Our results further identify functional heterogeneity within pancreatic duct subpopulations by elucidating a role for geminin in accumulation of DNA damage in the setting of chronic pancreatitis. Our findings implicate diverse functional roles for subpopulations of pancreatic duct cells in maintenance of duct cell identity and disease progression and establish a comprehensive road map of murine pancreatic duct cell, pancreatobiliary cell, and intrapancreatic bile duct cell homeostasis.

The Angiotensin II Type 1 Receptor-Associated Protein Attenuates Angiotensin II-Mediated Inhibition of the Renal Outer Medullary Potassium Channel in Collecting Duct Cells

Adjustments in renal K+ excretion constitute a central mechanism for K+ homeostasis. The renal outer medullary potassium (ROMK) channel accounts for the major K+ secretory route in collecting ducts during basal conditions. Activation of the angiotensin II (Ang II) type 1 receptor (AT1R) by Ang II is known to inhibit ROMK activity under the setting of K+ dietary restriction, underscoring the role of the AT1R in K+ conservation. The present study aimed to investigate whether an AT1R binding partner, the AT1R-associated protein (ATRAP), impacts Ang II-mediated ROMK regulation in collecting duct cells and, if so, to gain insight into the potential underlying mechanisms. To this end, we overexpressed either ATRAP or β-galactosidase (LacZ; used as a control), in M-1 cells, a model line of cortical collecting duct cells. We then assessed ROMK channel activity by employing a novel fluorescence-based microplate assay. Experiments were performed in the presence of 10−10 M Ang II or vehicle for 40 min. We observed that Ang II-induced a significant inhibition of ROMK in LacZ, but not in ATRAP-overexpressed M-1 cells. Inhibition of ROMK-mediated K+ secretion by Ang II was accompanied by lower ROMK cell surface expression. Conversely, Ang II did not affect the ROMK-cell surface abundance in M-1 cells transfected with ATRAP. Additionally, diminished response to Ang II in M-1 cells overexpressing ATRAP was accompanied by decreased c-Src phosphorylation at the tyrosine 416. Unexpectedly, reduced phospho-c-Src levels were also found in M-1 cells, overexpressing ATRAP treated with vehicle, suggesting that ATRAP can also downregulate this kinase independently of Ang II-AT1R activation. Collectively, our data support that ATRAP attenuates inhibition of ROMK by Ang II in collecting duct cells, presumably by reducing c-Src activation and blocking ROMK internalization. The potential role of ATRAP in K+ homeostasis and/or disorders awaits further investigation.

Saliva and its potential in covid-19 cannot be ignored: a point of view

It has been demonstrated that salivary gland duct cells have similar receptors as ACE2-positive cells/keratin epithelial cells of the lung which have high potential to be infected by SARS-CoV 2 virus. The aerosols carrying virus have penetration into the healthy human body and lungs via inhalation through nose or mouth.