The crosstalk between glomerular endothelial cells and podocytes controls their responses to metabolic stimuli in diabetic nephropathy

Abstract

In diabetic nephropathy (DN), glomerular endothelial cells (GECs) and podocytes undergo pathological alterations, which are influenced by metabolic changes characteristic of diabetes, including hyperglycaemia (HG) and elevated methylglyoxal (MGO) levels. However, it remains insufficiently understood what effects these metabolic factors have on GEC and podocytes and to what extent the interactions between the two cell types can modulate these effects. To address these questions, we established a co-culture system in which GECs and podocytes were grown together in close proximity, and assessed transcriptional changes in each cell type after exposure to HG and MGO. We found that HG and MGO had distinct effects on gene expression and that the effect of each treatment was markedly different between GECs and podocytes. HG treatment led to upregulation of “immediate early response” genes, particularly those of the EGR family, as well as genes involved in inflammatory responses (in GECs) or DNA replication/cell cycle (in podocytes). Interestingly, both HG and MGO led to downregulation of genes related to extracellular matrix organisation in podocytes. Crucially, the transcriptional responses of GECs and podocytes were dependent on their interaction with each other, as many of the prominently regulated genes in co-culture of the two cell types were not significantly changed when monocultures of the cells were exposed to the same stimuli. Finally, the changes in the expression of selected genes were validated in BTBR ob/ob mice, an established model of DN. This work highlights the molecular alterations in GECs and podocytes in response to the key diabetic metabolic triggers HG and MGO, as well as the central role of GEC-podocyte crosstalk in governing these responses.

Genetic Deletion of Calcium-independent Phospholipase A2γ Protects Mice from Diabetic Nephropathy

“…Studies in cultured GECs may not accurately reflect the diabetic environment in vivo, and more complex cell culture models, e.g. co-culture of cell lines, may be required to address mechanistic questions [46]. Evaluation of iPLA2γ metabolic effects and autophagy in human diabetic kidneys is difficult, although autophagy genes and gene ontology pathways are upregulated in glomeruli in human diabetic nephropathy [47].…”

Deletion of IRE1α in podocytes exacerbates diabetic nephropathy in mice

“…A limitation of studies in cultured GECs is that these cells may not accurately reflect diabetic nephropathy in vivo, and more complex cell culture models, e.g. co-culture of cell lines, may be required to address mechanistic questions 58 .…”

Crosstalk among podocytes, glomerular endothelial cells and mesangial cells in diabetic kidney disease: an updated review

“…Another study established a co-culture system of GECs and podocytes for gene expression analysis and found that both HG and methylglyoxal (MGO) led to the downregulation of genes related to ECM tissue in podocytes. Importantly, this downregulation depended on the cell-to-cell crosstalk between GECs and podocytes [ 128 ]. Notably, none of the identified genes were differentially expressed in single cultures of their respective cells, underscoring the critical role of cellular interactions between GECs and podocytes in the early development of DKD [ 128 ].…”

“…Importantly, this downregulation depended on the cell-to-cell crosstalk between GECs and podocytes [ 128 ]. Notably, none of the identified genes were differentially expressed in single cultures of their respective cells, underscoring the critical role of cellular interactions between GECs and podocytes in the early development of DKD [ 128 ].…”

“…While the role of early growth response-1 (EGR1) in MCs has been extensively studied [ 129 ], little is known about the potential roles of EGR family members in GECs or podocytes. However, recent research indicates that under high glucose conditions, not only EGR1, which has been linked to DKD pathogenesis [ 130 ], but also EGR2 and/or EGR3 were among the upregulated genes in both GECs and podocytes [ 128 ]. Furthermore, another immediate early transcription factor significantly upregulated by HG in GECs is nuclear receptor subfamily 4, group A member 1 (NR4A1).…”