Biology subjects

Grigorieva, I.

Publications and source records attributed to Grigorieva, I..

3 recordsLinked to original sources

bioRxiv2024

The Hyaluronan Synthase isoforms direct distinct patterns of fibroblast activation linked to fibrosis progression versus resolution following renal ischaemia

BackgroundThe stroma plays a key role during renal development and in regeneration after injury. However, following injury, the stroma expands driving progressive fibrosis. Hyaluronan (HA) is a glycosaminoglycan that is absent in healthy kidney stroma but highly expressed in disease. To understand strategies to modulate stromal HA towards therapeutic advantage, this study compares HA and HA Synthase (HAS) enzyme expression in kidney development, health, disease, and recovery. MethodsRats underwent ischaemia reperfusion injury (IRI) with/without ischaemic preconditioning (IPC) and kidneys histologically analysed. Kidneys from C57BL/6 embryos and HAS1/3-/- mice were also analysed and parallel mechanistic cell studies performed using primary human fibroblasts. ResultsIn health, stromal HA was absent from the renal cortex. HAS1 was expressed in some epithelial cells, whilst HAS2 was not expressed. Following IRI there was increased stromal HA in areas of chronic fibrosis, alongside increased HAS2 (but not HAS1) expression. In contrast, during development prominent stromal HA matrices were evident in areas of tubular generation, with strong HAS1 (not HAS2) expression. Following IPC+IRI, stromal HA and HAS2 were attenuated; whilst HAS1+ cells expanded but were distinct from -SMA+ myofibroblasts. Cell studies demonstrated that HAS1+ fibroblasts had a functionally distinct phenotype, with enhanced migration and FAP expression but attenuated -SMA, EDA-FN and COL1A1 expression, whereas HAS2+ fibroblasts demonstrated a classic -SMA+ contractile myofibroblast phenotype with high EDA-FN and COL1A1. ConclusionsHA is a key regulator of stromal fibroblast heterogeneity, with HAS1 and HAS2 defining phenotypically distinct populations that may influence divergent renal outcomes following injury. SIGNIFICANCE STATEMENTHyaluronan (HA) is a matrix glycosaminoglycans that is absent in healthy kidney cortex but demonstrates increased expression in the renal stroma during progressive fibrosis. This study makes comparisons of HA accumulation, localisation, and HA Synthase (HAS) protein expression during kidney development, in health, following ischaemic kidney injury and during renal recovery. The study identifies that different HAS isoenzymes (HAS1 and HAS2) mediate distinct functional fibroblast phenotypes in vitro and are localised in distinct stromal localisations and cell sub-populations in vivo. The data provides interesting insights into HA dependent regulation of fibroblast stromal heterogeneity and identifies the novel finding that HAS1 defines cell populations that are associated with kidney recovery following ischaemic injury and are protective against progressive renal fibrosis.

pathology↗

bioRxiv2023

Ischaemic Preconditioning attenuates Chronic Renal Damage following Ischaemia Reperfusion Injury

Acute Kidney Injury (AKI) is a common cause of Chronic Kidney Disease (CKD). The leading cause of AKI worldwide is Ischaemia Reperfusion Injury (IRI), seen most commonly in the clinical setting as a result of sepsis-driven hypotension. We are increasingly recognising, however, that AKI and CKD are one closely associated continuum of disease, rather than distinct entities. Ischaemic Preconditioning (IPC) is a strategy aimed at reducing the deleterious effects of IRI. This study demonstrates an efficacious model of kidney IRI, and the protective influence of IPC in attenuating renal injury/fibrosis. A rat model of bilateral kidney IRI was used: Male Lewis rats (n=84) were assigned to IRI, sham or IPC. In IRI, renal pedicles were clamped for 45 minutes. IPC groups underwent pulsatile IPC prior to IRI. Kidneys were retrieved at 24-hours, 48-hours, 7-days, 14-days and 28-days, and assessed histologically. IRI led to marked histological damage and renal fibrosis development by 28 days. Histological injury scores and degree of fibrosis were significantly increased following IRI and attenuated with IPC. IPC resulted in a 66% reduction in renal fibrosis at 28 days (p<0.001). IRI also led to a significant increase in serum creatinine acutely, which was attenuated by IPC (p<0.0001). Interestingly at 14-days, there was limited histological damage and differentiation between IRI and IPC kidneys was difficult. IPC can protect from both acute and chronic kidney damage. 14-days post IRI represents a transitional phase, which maybe a timepoint for commitment to either fibrosis or recovery, and hence offers potential for therapeutic intervention.

pathology↗

bioRxiv2023

Sex-specific Proximal Tubular Cell differentiation pathways identified by single-nucleus RNA

BackgroundPostpartum kidney growth is substantial but proliferation and differentiation pathways underpinning nephron elongation are not well defined. Here we performed sequential characterization of mouse kidney transcriptomics at the single cell level to address this. MethodsSingle nuclear RNA sequencing (snRNA-seq) was performed on kidney tissue from male and female mice at 1, 2, 4 and 12 weeks of age using the 10x Chromium platform. ResultsUnbiased clustering was performed on 68,775 nuclei from 16 animals. 31 discrete cellular clusters were seen, which were identified through comparison of their gene expression profiles to canonical markers of kidney cell populations. High levels of proliferation were evident at early time points in some cell types, especially tubular cells, but not in other cell types, for example podocytes. Proliferation was especially evident in Proximal Tubular Cells (PTCs) which are the most abundant cell type in the adult kidney. Uniquely when compared to other kidney cell types, PTCs demonstrated sex-specific expression profiles at late, but not early, time points. Mapping of PTC differentiation pathways using techniques including trajectory and RNA Velocity analyses delineated increasing PTC specialization and sex-specific phenotype specification. ConclusionOur single-cell transcriptomics data characterise cellular states observed during kidney growth. We have identified PTC differentiation pathways that lead to sex-specific tubular cell phenotypes.

cell biology↗