Biology subjects

Denby, L.

Publications and source records attributed to Denby, L..

3 recordsLinked to original sources

bioRxiv2022

Single cell analysis of senescent epithelia reveals targetable mechanisms promoting fibrosis

Progressive fibrosis and maladaptive organ repair result in significant morbidity and millions of premature deaths annually. Senescent cells accumulate with ageing and after injury and are implicated in organ fibrosis, but the mechanisms by which senescence influences repair are poorly understood. Using two murine models of injury and repair we show that obstructive injury generates senescent epithelia which persist after resolution of the original injury, promote ongoing fibrosis and impede adaptive repair. Depletion of senescent cells with ABT263 reduces fibrosis in reversed ureteric obstruction and after renal ischaemia-reperfusion injury. We validate these findings in humans, showing that senescence and fibrosis persist after relieved renal obstruction. We next characterise senescent epithelia in murine renal injury using single cell RNA-Seq. We extend our classification to human kidney and liver disease and identify conserved pro-fibrotic proteins which we validate in vitro and in human disease. We demonstrate that one such molecule, Protein Disulfide Isomerase Family A Member 3 (PDIA3), is essential for TGF-beta mediated fibroblast activation. Inhibition of PDIA3 in vivo significantly reduces kidney fibrosis during ongoing renal injury and as such represents a new potential therapeutic pathway. Analysis of the signalling pathways of senescent epithelia connects senescence to organ fibrosis, permitting rational design of anti-fibrotic therapies.

cell biology↗

bioRxiv2020

Kidney single-cell atlas reveals myeloid heterogeneity in progression and regression of kidney disease.

The kidney has a limited capacity to repair following injury, however, the endogenous reparative pathways are not well understood. Here we employ integrated droplet- and plate-based scRNA-seq in the murine reversible unilateral ureteric obstruction model to dissect the transcriptomic landscape at the single cell level during renal injury and resolution of fibrosis. We generate a comprehensive catalogue of the changes induced during injury and repair, revealing significant myeloid cell heterogeneity, which would not have been identifiable by conventional flow cytometry. We identify new markers for the myeloid populations within the kidney as well as identification of novel subsets including an Arg1+ monocyte population specific to early injury and a Mmp12+ macrophage subset exclusive to repair. Finally, using paired blood exchange to track circulating immune cells, we confirm that monocytes are recruited to the kidney early after injury and are the source of Ccr2+ macrophages that accumulate in late injury. Our data demonstrate the utility of complementary technologies to identify novel myeloid subtypes that may represent therapeutic targets to inhibit progression or promote regression of kidney disease.

immunology↗

bioRxiv2020

Transfer of hepatocellular microRNA regulates cytochrome P450 2E1 in renal tubular cells

Extracellular microRNAs have been demonstrated to have the ability to enter kidney tubular cells and modify gene expression. We have used a Dicer-hepatocyte-specific microRNA conditional knock-out (Dicer-CKO) mouse to investigate functional microRNA transfer from liver to kidney under physiological conditions and in the context of drug toxicity. Dicer-CKO mice demonstrated a time-dependent decrease in the hepatocyte-derived microRNA, miR-122, in the kidney in the absence of other microRNA changes. During hepatotoxicity, miR-122 increased in kidney tubular cells; this was abolished in Dicer-CKO mice. Depletion of hepatocyte microRNAs increased expression and activity of the miR-122 target - cytochrome (CYP) P450 2E1 - in the kidney. Serum extracellular vesicles (ECVs) from mice with hepatotoxicity increased proximal tubular cell miR-122 and prevented cisplatin proximal tubular cell toxicity. miR-122 also increased in urinary ECVs during hepatotoxicity in humans. Transfer of microRNA was not restricted to liver injury - we detected miR-499 release with murine cardiac injury, and this correlated with an increase in the kidney. In summary, a physiological transfer of microRNA to the kidney exists, which is increased by liver injury. Regulation of renal drug response due to signalling by microRNA of hepatic origin represents a new paradigm for understanding and preventing nephrotoxicity.

pharmacology and toxicology↗