Single cell G‐protein coupled receptor profiling of activated kidney fibroblasts expressing transcription factor 21

Abstract

Background and PurposeActivated fibroblasts deposit fibrotic matrix in chronic kidney disease (CKD) and G‐protein coupled receptors (GPCRs) are the most druggable therapeutic targets. Here, we set out to establish a transcriptional profile that identifies activated kidney fibroblasts and the GPCRs that they express.Experimental ApproachRNA sequencing and single cell qRT‐PCR were performed on mouse kidneys after unilateral ureteral obstruction (UUO). Candidate expression was evaluated in mice with UUO or diabetes or injected with adriamycin or folic acid. Intervention studies were conducted in mice with diabetes or UUO. Correlative histology was performed in human kidney tissue.Key ResultsTranscription factor 21 (Tcf21)+ cells that expressed 2 or 3 of Postn, Acta2 and Pdgfra were highly enriched for fibrogenic genes and were defined as activated kidney fibroblasts. Tcf21+ α‐smooth muscle actin (α‐SMA)+ interstitial cells accumulated in kidneys of mice with UUO or diabetes or injected with adriamycin or folic acid, whereas renin‐angiotensin system blockade attenuated increases in Tcf21 in diabetic mice. Fifty‐six GPCRs were up‐regulated in single Tcf21+ kidney fibroblasts, the most up‐regulated being Adgra2 and S1pr3. Adenosine receptors, Adora2a/2b, were up‐regulated in Tcf21+ fibroblasts and the adenosine receptor antagonist, caffeine decreased Tcf21 upregulation and kidney fibrosis in UUO mice. TCF21, ADGRA2, S1PR3 and ADORA2A/2B were each detectable in α‐SMA+ interstitial cells in human kidney samples.Conclusion and ImplicationsTcf21 is a marker of kidney fibroblasts that are enriched for fibrogenic genes in CKD. Further analysis of the GPCRs expressed by these cells may identify new targets for treating CKD.

Analysis of genetic variant associated with heart failure mortality implicates thymic stromal lymphopoietin as mediator of strain‐induced myocardial fibroblast‐mast cell crosstalk and fibrosis

“…Whether TSLP is increased in the hearts of patients with HF and whether such therapy may reduce myocardial remodeling and improve outcomes in HF remains to be tested. Interestingly, we also noted marked TSLP expression in kidney in response to our Tcf21 ‐promoter vector, suggestive of a role of TCF21‐expressing fibroblasts in that tissue also, which was also recently reported in another recent study 29 . Whether TSLP may contribute to kidney fibrosis could thus warrant further study.…”

Therapeutic targets of fibrosis: Translational advances and current challenges

“…Fibrosis in the kidney, leading to chronic kidney disease (CKD), is a common outcome of kidney injury and of multiple diseases including diabetes, high blood pressure and cardiovascular disease. The original research arising from the work of Kaur et al (2023) seeks to further contribute to drug discovery in the CKD field and search for treatments to reverse renal fibrosis. A range of GPCRs expressed on the surface of multiple cell types have been proposed as key therapeutic targets for fibrosis in the kidney (and other organs).…”

“…As illustrated in our Figure 2, the authors utilised kidney RNA sequencing and single‐cell GPCR transcriptomic profiling in a murine preclinical model of kidney inflammation and fibrosis. Bulk RNA sequencing revealed >5000 up‐regulated and ~1200 down‐regulated genes in male renal fibrosis mice, of which the top 10 up‐regulated genes were expected markers of inflammation and fibrosis (Kaur et al, 2023). Curating a library of cell markers, fibrotic genes and GPCRs, the authors probed single fibroblast‐enriched cells, identifying which transcriptional markers of activated fibroblasts (including periostin and PDGF receptor A) are increased.…”

“…It was concluded that activation of interstitial fibroblasts was largely responsible for the decline in kidney function. The single‐cell GPCR screening undertaken here may identify new treatment targets warranting investigation for chronic kidney disease (Kaur et al, 2023).…”

“…Transcription factor 21 (Tcf21) is a potential therapeutic target for treatment of renal fibrosis, as revealed by Kaur et al (2023). UUO, unilateral ureteral obstruction (murine model of kidney fibrosis).…”