Shared and Distinct Renal Transcriptome Signatures in 3 Standard Mouse Models of Chronic Kidney Disease

INTRODUCTION

Several mouse models with diverse disease etiologies are used in preclinical research for chronic kidney disease (CKD). Here, we performed a head-to-head comparison of renal transcriptome signatures in standard mouse models of CKD to assess shared and distinct molecular changes in three mouse models commonly employed in preclinical CKD research and drug discovery.

METHODS

All experiments were conducted on male C57BL/6J mice. Mice underwent sham, unilateral ureter obstruction (UUO), or unilateral ischemic-reperfusion injury (uIRI) surgery and were terminated two- and 6-weeks post-surgery, respectively. The adenine-supplemented diet-induced (ADI) model of CKD was established by feeding with adenine diet for 6 weeks and compared to control diet feeding. For all models, endpoints included plasma biochemistry, kidney histology, and RNA sequencing.

RESULTS

All models displayed increased macrophage infiltration (F4/80 IHC) and fibrosis (collagen 1a1 IHC). Compared to corresponding controls, all models were characterized by an extensive number of renal differentially expressed genes (≥11,000), with a notable overlap in transcriptomic signatures across models. Gene expression markers of fibrosis, inflammation, and kidney injury supported histological findings. Interestingly, model-specific transcriptome signatures included several genes representing current drug targets for CKD, emphasizing advantages and limitations of the three CKD models in preclinical target and drug discovery.

CONCLUSION

The UUO, uIRI, and ADI mouse models of CKD have significant commonalities in their renal global transcriptome profile. Model-specific renal transcriptional signatures should be considered when selecting the specific model in preclinical target and drug discovery.

(ABS-36) alleviates acute and chronic renal injury under in vitro and in vivo models (Ischemic reperfusion and unilateral ureter obstruction)

The study aimed to identify small molecules having potentiality in alleviating renal injury. Two natural compounds cyclo(Val-Pro) (1) and cyclo(Leu-Hydroxy-Pro) (2) were first evaluated under acute renal injury model of ischemic reperfusion at different doses of 25, 50 and 75 mg/kg body weight. Further, the compounds were subjected to antimycin A-induced ischemic in vitro study (NRK-52E cell lines). Both the compounds significantly decreased plasma IL-1β levels (P < 0.05). Also, the mRNA expression levels of inflammatory markers (TNF-α, IL-6 and IL-1β) and renal injury markers (KIM-1, NGAL, α-GST and π-GST) in the renal tissues were significantly alleviated (P < 0.01) along with the improvement in histological damage and control over neutrophil infiltration as a result of ischemic reperfusion. The in vitro study revealed the protective effect against antimycin A-induced cytotoxicity (P < 0.05) and antiapoptotic effect acting through the regulation of Bax, caspase 3 (pro and cleaved) and BCL2 with reduction in Annexin⁺PI⁺ cells. Further, the compound cyclo(Val-Pro) (1) was evaluated (50 mg/kg body weight dose) in chronic unilateral ureter obstruction model of renal injury in mice and TGF-β-induced in vitro fibrotic model (NRK-49F cell lines). Cyclo(Val-Pro) (1) significantly reduced the expression levels of fibrotic markers (collagen-1, α-SMA and TGF-β) and showed marked alleviation of renal fibrosis (sirius red staining). Also, the proliferation of TGF-β-induced NRK-49F cells was significantly reduced along with decreased levels of collagen-1 and α-SMA in immunohistochemistry studies. In conclusion, the compounds significantly abrogated ischemic injury by inhibiting renal inflammation and tubular epithelial apoptosis. Further, cyclo (Val-Pro) (1) exhibited significant anti-fibrotic activity through the inhibition of fibroblast activation and proliferation. Thus, these proline-based cyclic dipeptides are recommended as drug leads for treating renal injury.

Surfactant protein A deficiency exacerbates renal interstitial fibrosis following obstructive injury in mice

Renal interstitial fibrosis is an inevitable consequence of virtually every type of chronic kidney disease. The underlying mechanisms, however, are not completely understood. In the present study, we identified surfactant protein A (SP-A) as a novel protein factor involved in the renal fibrosis induced by unilateral ureter obstruction (UUO). UUO induced SP-A expression in mouse kidney epithelium, likely due to the increased acidic stress and inflammation. Interestingly, SP-A deficiency aggravated UUO-prompted kidney structural damage, macrophage accumulation, and tubulointerstitial fibrosis. SP-A deficiency appeared to worsen the fibrosis by enhancing interstitial myofibroblast accumulation. Moreover, SP-A deficiency increased the expression of TGF-β1, the major regulator of kidney fibrosis, particularly in the interstitial cells. Mechanistically, SP-A deficiency increased the expression and release of high mobility group box 1 (HMGB1), a factor regulating TGF-β expression/signaling and implicated in renal fibrosis. SP-A also blocked HMGB1 activities in inducing TGF-β1 expression and myofibroblast transdifferentiation from kidney fibroblasts, demonstrating that SP-A protected kidney by impeding both the expression and fibrogenic function of HMGB1. Since SP-A physically interacted with HMGB1 both in vitro and in kidney tissue in vivo, SP-A may exert its protective role by binding to HMGB1 and thus titrating its activity during UUO-induced renal fibrosis.