A single-arm pilot study of metformin in patients with autosomal dominant polycystic kidney disease

Delaying Renal Aging: Metformin Holds Promise as a Potential Treatment

Given the rapid aging of the population, age-related diseases have become an excessive burden on global health care. The kidney, a crucial metabolic organ, ages relatively quickly. While the aging process itself does not directly cause kidney damage, the physiological changes that accompany it can impair the kidney's capacity for self-repair. This makes aging kidneys more susceptible to diseases, including increased risks of chronic kidney disease and end-stage renal disease. Therefore, delaying the progression of renal aging and preserving the youthful vitality of the kidney are crucial for preventing kidney diseases. However, effective strategies against renal aging are still lacking due to the underlying mechanisms of renal aging, which have not been fully elucidated. Accumulating evidence suggests that metformin has beneficial effects in mitigating renal aging. Metformin has shown promising anti-aging results in animal models but has not been tested for this purpose yet in clinical trials. These findings indicate the potential of metformin as an anti-renal aging drug. In this review, we primarily discuss the characteristics and mechanisms of kidney aging and the potential effects of metformin against renal aging.

Short-Term Dapagliflozin Administration in Autosomal Dominant Polycystic Kidney Disease-A Retrospective Single-Arm Case Series Study

Treatment with sodium-glucose cotransporter-2 (SGLT2) inhibitors may have pleiotropic and beneficial effects in terms of ameliorating of risk factors for the progression of autosomal dominant polycystic kidney disease (ADPKD). However, there is insufficient evidence regarding the use of these drugs in patients with ADPKD, as they were excluded from several clinical trials conducted to explore kidney protection provided by SGLT2 inhibitors. This retrospective single-arm case series study was performed to investigate the effects of dapagliflozin, a selective SGLT2 inhibitor administered at 10 mg/day, on changes in height-adjusted kidney volume (htTKV) and estimated glomerular filtration rate (eGFR) in ADPKD patients. During a period of 102 ± 20 days (range 70-156 days), eGFR was decreased from 47.9 (39.7-56.9) to 40.8 (33.7-44.5) mL/min/1.73 m2 (p < 0.001), while htTKV was increased from 599 (423-707) to 617 (446-827) mL/m (p = 0.002) (n = 20). The annual increase in htTKV rate was significantly promoted, and urinary phosphate change was found to be correlated with the change in htTKV (rs = 0.575, p = 0.020). In the examined patients, eGFR was decreased and htTKV increased during short-term administration of dapagliflozin. To confirm the possibility of the effects of dapagliflozin on ADPKD, additional interventional studies are required.

Combining Metformin and Drug-Loaded Kidney-Targeting Micelles for Polycystic Kidney Disease

Introduction

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease that leads to eventual renal failure. Metformin (MET), an AMP-activated protein kinase (AMPK) activator already approved for type 2 diabetes, is currently investigated for ADPKD treatment. However, despite high tolerability, MET showed varying therapeutic efficacy in preclinical ADPKD studies. Thus, newer strategies have combined MET with other ADPKD small molecule drug candidates, thereby targeting multiple ADPKD-associated signaling pathways to enhance therapeutic outcomes through potential drug synergy. Unfortunately, the off-target side effects caused by these additional drug candidates pose a major hurdle. To address this, our group has previously developed kidney-targeting peptide amphiphile micelles (KMs), which displayed significant kidney accumulation in vivo, for delivering drugs to the site of the disease.

Methods

To mitigate the adverse effects of ADPKD drugs and evaluate their therapeutic potential in combination with MET, herein, we loaded KMs with ADPKD drug candidates including salsalate, octreotide, bardoxolone methyl, rapamycin, tolvaptan, and pioglitazone, and tested their in vitro therapeutic efficacy when combined with free MET. Specifically, after determining the 40% inhibitory concentration for each drug (IC40), the size, morphology, and surface charge of drug-loaded KMs were characterized. Next, drug-loaded KMs were applied in combination with MET to treat renal proximal tubule cells derived from Pkd1flox/-:TSLargeT mice in 2D proliferation and 3D cyst model.

Results

MET combined with all drug-loaded KMs demonstrated significantly enhanced efficacy as compared to free drugs in inhibiting cell proliferation and cyst growth. Notably, synergistic effects were found for MET and KMs loaded with either salsalate or rapamycin as determined by Bliss synergy scores.

Conclusion

Together, we show drug synergy using drug-loaded nanoparticles and free MET for the first time and present a novel nanomedicine-based combinatorial therapeutic approach for ADPKD with enhanced efficacy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-022-00753-9.

Shared pathobiology identifies AMPK as a therapeutic target for obesity and autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common Mendelian kidney disease, affecting approximately one in 1,000 births and accounting for 5% of end-stage kidney disease in developed countries. The pathophysiology of ADPKD is strongly linked to metabolic dysregulation, which may be secondary to defective polycystin function. Overweight and obesity are highly prevalent in patients with ADPKD and constitute an independent risk factor for progression. Recent studies have highlighted reduced AMP-activated protein kinase (AMPK) activity, increased mammalian target of rapamycin (mTOR) signaling, and mitochondrial dysfunction as shared pathobiology between ADPKD and overweight/obesity. Notably, mTOR and AMPK are two diametrically opposed sensors of energy metabolism that regulate cell growth and proliferation. However, treatment with the current generation of mTOR inhibitors is poorly tolerated due to their toxicity, making clinical translation difficult. By contrast, multiple preclinical and clinical studies have shown that pharmacological activation of AMPK provides a promising approach to treat ADPKD. In this narrative review, we summarize the pleiotropic functions of AMPK as a regulator of cellular proliferation, macromolecule metabolism, and mitochondrial biogenesis, and discuss the potential for pharmacological activation of AMPK to treat ADPKD and obesity-related kidney disease.

Retarding Progression of Chronic Kidney Disease in Autosomal Dominant Polycystic Kidney Disease with Metformin and Other Therapies: An Update of New Insights

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent single-gene disorder leading to renal failure. Current therapies are aimed to treat renal and extrarenal complications of ADPKD, but improved knowledge of the pathophysiological mechanisms leading to the generation and growth of cysts has permitted the identification of new drug candidates for clinical trials. Among these, in this review, we will examine above all the role of metformin, hypothesized to be able to activate the AMP-activated protein kinase (AMPK) pathway and potentially modulate some mechanisms implicated in the onset and the growth of the cysts.

Autosomic dominant polycystic kidney disease and metformin: Old knowledge and new insights on retarding progression of chronic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common congenital kidney disorder, generally caused by mutations in the PKD1 and PKD2 genes, coding for polycystins 1 and 2. Its pathogenesis is accompanied by alterations of the cAMP, mTOR, MAPK/ERK, and JAK/STAT pathways. ADPKD is clinically characterized by the formation of many growing cysts with kidney enlargement and a progressive damage to the parenchyma, up to its complete loss of function, and the onset of end-stage renal disease (ESRD). The current aim of ADPKD therapy is the inhibition of cyst development and retardation of chronic kidney disease progression. Several drugs have been recently included as potential therapies for ADPKD including metformin, the drug of choice for the treatment of type 2 diabetes mellitus, according to its potential inhibitory effects on cystogenesis. In this review, we summarize preclinical and clinical evidence endorsing or rejecting metformin administration in ADPKD evolution and pathological mechanisms. We explored the biology of APDKD and the role of metformin in slowing down cystogenesis searching PubMed and Clinical Trials to identify relevant data from the database inception to December 2020. From our research analysis, evidence for metformin as emerging cure for ADPKD mainly arise from preclinical studies. In fact, clinical studies are still scanty and stronger evidence is awaited. Its effects are likely mediated by inhibition of the ERK pathway and increase of AMPK levels, which are both linked to ADPKD pathogenesis.

Quinomycin A reduces cyst progression in polycystic kidney disease

Polycystic kidney disease (PKD) is a genetic disorder characterized by aberrant renal epithelial cell proliferation and formation and progressive growth of numerous fluid-filled cysts within the kidneys. Previously, we showed that there is elevated Notch signaling compared to normal renal epithelial cells and that Notch signaling contributes to the proliferation of cystic cells. Quinomycin A, a bis-intercalator peptide, has previously been shown to target the Notch signaling pathway and inhibit tumor growth in cancer. Here, we show that Quinomycin A decreased cell proliferation and cyst growth of human ADPKD cyst epithelial cells cultured within a 3D collagen gel. Treatment with Quinomycin A reduced kidney weight to body weight ratio and decreased renal cystic area and fibrosis in Pkd1^RC/RC ; Pkd2^+/- mice, an orthologous PKD mouse model. This was accompanied by reduced expression of Notch pathway proteins, RBPjk and HeyL and cell proliferation in kidneys of PKD mice. Quinomycin A treatments also normalized cilia length of cyst epithelial cells derived from the collecting ducts. This is the first study to demonstrate that Quinomycin A effectively inhibits PKD progression and suggests that Quinomycin A has potential therapeutic value for PKD patients.

The cellular pathways and potential therapeutics of Polycystic Kidney Disease

Polycystic Kidney Disease (PKD) refers to a group of disorders, driven by the formation of cysts in renal tubular cells and is currently one of the leading causes of end-stage renal disease. The range of symptoms observed in PKD is due to mutations in cilia-localising genes, resulting in changes in cellular signalling. As such, compounds that are currently in preclinical and clinical trials target some of these signalling pathways that are dysregulated in PKD. In this review, we highlight these pathways including cAMP, EGF and AMPK signalling and drugs that target them and may show promise in lessening the disease burden of PKD patients. At present, tolvaptan is the only approved therapy for ADPKD, however, it carries several adverse side effects whilst comparatively, no pharmacological drug is approved for ARPKD treatment. Aside from this, drugs that have been the subject of multiple clinical trials such as metformin, which targets AMPK signalling and somatostatins, which target cAMP signalling have shown great promise in reducing cyst formation and cellular proliferation. This review also discusses other potential and novel targets that can be used for future interventions, such as β-catenin and TAZ, where research has shown that a reduction in the overexpression of these signalling components results in amelioration of disease phenotype. Thus, it becomes apparent that well-designed preclinical investigations and future clinical trials into these pathways and other potential signalling targets are crucial in bettering disease prognosis for PKD patients and could lead to personalised therapy approaches.

Limitations and opportunities in the pharmacotherapy of ciliopathies

Ciliopathies are a family of rather diverse conditions, which have been grouped based on the finding of altered or dysfunctional cilia, potentially motile, small cellular antennae extending from the surface of postmitotic cells. Cilia-related disorders include embryonically arising conditions such as Joubert, Usher or Kartagener syndrome, but also afflictions with a postnatal or even adult onset phenotype, i.e. autosomal dominant polycystic kidney disease. The majority of ciliopathies are syndromic rather than affecting only a single organ due to cilia being found on almost any cell in the human body. Overall ciliopathies are considered rare diseases. Despite that, pharmacological research and the strive to help these patients has led to enormous therapeutic advances in the last decade. In this review we discuss new treatment options for certain ciliopathies, give an outlook on promising future therapeutic strategies, but also highlight the limitations in the development of therapeutic approaches of ciliopathies.

Mechanism and application of metformin in kidney diseases: An update

Metformin is an oral antihyperglycemic drug widely used to treat type 2 diabetes mellitus (T2DM), acting via indirect activation of 5' Adenosine monophosphate-activated Protein Kinase (AMPK). Beyond the anti-diabetic effect, accumulative pieces of evidence have revealed that metformin also everts a beneficial effect in diverse kidney diseases. In various acute kidney diseases (AKI) animal models, metformin protects renal tubular cells from inflammation, apoptosis, reactive oxygen stress (ROS), endoplasmic reticulum (ER) stress, epithelial-mesenchymal transition (EMT) via AMPK activation. In diabetic kidney disease (DKD), metformin also alleviates podocyte loss, mesangial cells apoptosis, and tubular cells senescence through AMPK-mediated signaling pathways. Besides, metformin inhibits cystic fibrosis transmembrane conductance regulator (CFTR)-mediated fluids secretion and the mammalian target of rapamycin (mTOR)-involved cyst formation negatively regulated by AMPK in autosomal dominant polycystic kidney disease (APDKD). Furthermore, metformin also contributes to the alleviation of urolithiasis and renal cell carcinoma (RCC). As the common pathway for chronic kidney disease (CKD) progressing towards end-stage renal disease (ESRD), renal fibrosis is ameliorated by metformin, to a great extent dependent on AMPK activation. However, clinical data are not always consistent with preclinical data, some clinical investigations showed the unmeaningful even detrimental effect of metformin on T2DM patients with kidney diseases. Most importantly, metformin-associated lactic acidosis (MALA) is a vital issue restricting the application of metformin. Thus, we conclude the application of metformin in kidney diseases and uncover the underlying molecular mechanisms in this review.