Cardiotrophin-1 therapy reduces disease severity in a murine model of glomerular disease.

Cardiotrophin-1 (CT-1), a member of the interleukin (IL)-6 cytokine family, has renoprotective effects in mouse models of acute kidney disease and tubulointerstitial fibrosis, but its role in glomerular disease is unknown. To address this, we used the mouse model of nephrotoxic nephritis to test the hypothesis that CT-1 also has a protective role in immune-mediated glomerular disease. Using immunohistochemistry and analysis of single-cell RNA-sequencing data of isolated glomeruli, we demonstrate that CT-1 is expressed in the glomerulus in male mice, predominantly in parietal epithelial cells and is downregulated in mice with nephrotoxic nephritis. Furthermore, analysis of data from patients revealed that human glomerular disease is also associated with reduced glomerular CT-1 transcript levels. In male mice with nephrotoxic nephritis and established proteinuria, administration of CT-1 resulted in reduced albuminuria, prevented podocyte loss, and sustained plasma creatinine, compared with mice administered saline. CT-1 treatment also reduced fibrosis in the kidney cortex, peri-glomerular macrophage accumulation and the kidney levels of the pro-inflammatory mediator complement component 5a. In conclusion, CT-1 intervention therapy delays the progression of glomerular disease in mice by preserving kidney function and inhibiting renal inflammation and fibrosis.

A microfluidic platform integrating functional vascularized organoids-on-chip.

The development of vascular networks in microfluidic chips is crucial for the long-term culture of three-dimensional cell aggregates such as spheroids, organoids, tumoroids, or tissue explants. Despite rapid advancement in microvascular network systems and organoid technologies, vascularizing organoids-on-chips remains a challenge in tissue engineering. Most existing microfluidic devices poorly reflect the complexity of in vivo flows and require complex technical set-ups. Considering these constraints, we develop a platform to establish and monitor the formation of endothelial networks around mesenchymal and pancreatic islet spheroids, as well as blood vessel organoids generated from pluripotent stem cells, cultured for up to 30 days on-chip. We show that these networks establish functional connections with the endothelium-rich spheroids and vascular organoids, as they successfully provide intravascular perfusion to these structures. We find that organoid growth, maturation, and function are enhanced when cultured on-chip using our vascularization method. This microphysiological system represents a viable organ-on-chip model to vascularize diverse biological 3D tissues and sets the stage to establish organoid perfusions using advanced microfluidics.

Systemic gene therapy with thymosin ß4 alleviates glomerular injury in mice.

Plasma ultrafiltration in the kidney occurs across glomerular capillaries, which are surrounded by epithelial cells called podocytes. Podocytes have a unique shape maintained by a complex cytoskeleton, which becomes disrupted in glomerular disease resulting in defective filtration and albuminuria. Lack of endogenous thymosin ß4 (TB4), an actin sequestering peptide, exacerbates glomerular injury and disrupts the organisation of the podocyte actin cytoskeleton, however, the potential of exogenous TB4 therapy to improve podocyte injury is unknown. Here, we have used Adriamycin (ADR), a toxin which injures podocytes and damages the glomerular filtration barrier leading to albuminuria in mice. Through interrogating single-cell RNA-sequencing data of isolated glomeruli we demonstrate that ADR injury results in reduced levels of podocyte TB4. Administration of an adeno-associated viral vector encoding TB4 increased the circulating level of TB4 and prevented ADR-induced podocyte loss and albuminuria. ADR injury was associated with disorganisation of the podocyte actin cytoskeleton in vitro, which was ameliorated by treatment with exogenous TB4. Collectively, we propose that systemic gene therapy with TB4 prevents podocyte injury and maintains glomerular filtration via protection of the podocyte cytoskeleton thus presenting a novel treatment strategy for glomerular disease.

Diverse species-specific phenotypic consequences of loss of function sorting nexin 14 mutations.

Mutations in the SNX14 gene cause spinocerebellar ataxia, autosomal recessive 20 (SCAR20) in both humans and dogs. Studies implicating the phenotypic consequences of SNX14 mutations to be consequences of subcellular disruption to autophagy and lipid metabolism have been limited to in vitro investigation of patient-derived dermal fibroblasts, laboratory engineered cell lines and developmental analysis of zebrafish morphants. SNX14 homologues Snz (Drosophila) and Mdm1 (yeast) have also been conducted, demonstrated an important biochemical role during lipid biogenesis. In this study we report the effect of loss of SNX14 in mice, which resulted in embryonic lethality around mid-gestation due to placental pathology that involves severe disruption to syncytiotrophoblast cell differentiation. In contrast to other vertebrates, zebrafish carrying a homozygous, maternal zygotic snx14 genetic loss-of-function mutation were both viable and anatomically normal. Whilst no obvious behavioural effects were observed, elevated levels of neutral lipids and phospholipids resemble previously reported effects on lipid homeostasis in other species. The biochemical role of SNX14 therefore appears largely conserved through evolution while the consequences of loss of function varies between species. Mouse and zebrafish models therefore provide valuable insights into the functional importance of SNX14 with distinct opportunities for investigating its cellular and metabolic function in vivo.