Diabetic kidney disease (DKD) is a common microvascular complication of diabetes and remains a major global health concern despite existing therapies. Persistent residual risk with current treatments motivates investigation of adjunctive strategies that target key pathogenic mechanisms. Impaired mitophagy, increased apoptosis, and progressive fibrosis are central mechanisms driving DKD progression. The present study evaluated whether supplementing dapagliflozin (DAPA), an SGLT2 inhibitor, with recombinant human klotho (rh-KL) improves renal outcomes by restoring mitophagy and limiting apoptotic and fibrotic pathways.
Two preclinical DKD models were used. An in vivo model comprised streptozotocin-induced Type 1 diabetes in Sprague-Dawley rats. An in vitro model used NRK-52E renal tubular epithelial cells stimulated with high glucose plus recombinant human TGF-β1 (HG + rh-TGF-β1) to simulate diabetic and profibrotic conditions. Treatments included rh-KL, DAPA, and their combination. After treatment, samples (urine, plasma, and renal tissues) and cultured cells were collected for downstream analyses. Additionally, siRNA-mediated klotho knockdown was performed to probe the specific role of klotho in regulating apoptosis and fibrosis under diabetic conditions.
The study assessed metabolic and renal function parameters, renal histology, and molecular markers. Analytical methods included biochemical assays on urine and plasma, histological and immunohistochemical analysis of renal tissue, immunocytochemistry in cultured NRK-52E cells, and qRT-PCR for gene expression. The molecular panel evaluated regulators of mitochondrial quality control and survival (SIRT1, PGC-1α, PINK1, Parkin, Bcl-2), and pro-fibrotic or inflammatory mediators (TGF-β, NF-κB), as well as fibrosis and apoptosis effectors (vimentin, collagen-I, Bax).
Combination therapy with rh-KL and DAPA produced greater improvements in metabolic and renal function measures than monotherapy, as reported in the study abstract. Histological evaluation showed marked preservation of renal architecture in the co-treated diabetic animals relative to untreated or singly treated groups. These results indicate that adjunctive rh-KL enhances the renoprotective impact of DAPA in the experimental DKD model.
Co-treatment was associated with upregulation of mediators linked to mitochondrial biogenesis and mitophagy, specifically increased expression of SIRT1, PGC-1α, PINK1, and Parkin, together with increased Bcl-2—a pro-survival protein. Concurrently, levels of TGF-β and NF-κB, both implicated in fibrosis and inflammation, were reduced in diabetic rat kidneys, based on immunohistochemistry and qRT-PCR findings reported in the source.
In the NRK-52E cell model exposed to HG + rh-TGF-β1, the rh-KL + DAPA combination reduced expression of fibrosis and apoptosis markers including vimentin, collagen-I, and Bax, as demonstrated by immunocytochemistry and qRT-PCR. Collectively, these molecular changes are consistent with restored mitophagy, inhibition of apoptosis, and attenuation of fibrotic signaling under diabetic stress when klotho and dapagliflozin are combined.
siRNA-mediated reduction of klotho expression was employed to clarify klotho’s contribution. The study reports that klotho knockdown worsened apoptosis and fibrosis in diabetic conditions, supporting a protective role for klotho in the renal response to diabetic injury. This finding reinforces the interpretation that exogenous klotho contributes directly to the antifibrotic and antiapoptotic effects observed with combination therapy.
The authors conclude that recombinant human klotho, when used as an adjunct to dapagliflozin, enhances renoprotection in experimental models of DKD by restoring mitophagy and mitigating apoptosis and fibrosis. The combination produced superior molecular and histological outcomes compared with monotherapies, and the authors suggest that a rh-KL + DAPA strategy may permit use of lower DAPA doses, potentially reducing adverse effects while improving therapeutic efficacy.
Details not provided in the abstract: the source abstract does not report specific doses, treatment durations, numerical effect sizes, or statistical values for the reported outcomes. Those details would be required to assess translational potential, dose optimization, safety, and comparative magnitude of benefit.
Overall, the study supports further preclinical evaluation of klotho as an adjunct to SGLT2 inhibition in DKD, but full assessment of translational relevance requires access to dosing, safety, and quantitative outcome data not provided in the abstract.