Pemafibrate inhibited renal dysfunction and fibrosis in a mouse model of adenine-induced chronic kidney disease

Role of peroxisomes in the pathogenesis and therapy of renal fibrosis

Renal fibrosis is a pathological consequence of end-stage chronic kidney disease, driven by factors such as oxidative stress, dysregulated fatty acid metabolism, extracellular matrix (ECM) imbalance, and epithelial-to-mesenchymal transition. Peroxisomes play a critical role in fatty acid β-oxidation and the scavenging of reactive oxygen species, interacting closely with mitochondrial functions. Nonetheless, current research often prioritizes the mitochondrial influence on renal fibrosis, often overlooking the contribution of peroxisomes. This comprehensive review systematically elucidates the fundamental biological functions of peroxisomes and delineates the molecular mechanisms underlying peroxisomal dysfunction in renal fibrosis pathogenesis. Here, we discuss the impact of peroxisome dysfunction and pexophagy on oxidative stress, ECM deposition, and renal fibrosis in various cell types including mesangial cells, endothelial cells, podocytes, epithelial cells, and macrophages. Furthermore, this review highlights the recent advancements in peroxisome-targeted therapeutic strategies to alleviate renal fibrosis.

Huangqi and Danshen improve the chronic nephrotoxicity of cyclosporin A by regulating lipid metabolism

BACKGROUND

The clinical application of cyclosporine A (CsA) is limited due to nephrotoxicity. Lipid metabolism disorders play important roles in renal injury, but their role in CsA nephrotoxicity is not yet clear. Huangqi (Astragalus mongholicus Bunge) and Danshen (Salvia miltiorrhiza Bunge) (HD) play roles in ameliorating the nephrotoxicity of CsA, but their mechanisms still need to be fully clarified.

OBJECTIVE

This study innovatively aimed to analyse the coexpression of renal proteins and serum metabolites for the identification of key pathways and targets. This study provides novel insight into the mechanism by which HD ameliorates CsA-induced nephrotoxicity.

METHODS

We utilized HD to intervene in both in vivo and in vitro nephrotoxicity models induced by CsA. For the in vivo experiments, we constructed a coexpression network of renal proteins and serum metabolites, which was used to screen for key pathways. To validate these findings, we knocked down key proteins in vivo. For the in vitro studies, we employed MTT, Transwell, flow cytometry, and immunofluorescence assays to monitor the epithelial-mesenchymal transition (EMT) of HK-2 cells. Additionally, we used electron microscopy and Seahorse assays to examine the effects of HD on mitochondrial structure and function. Furthermore, we overexpressed Ppara to further confirm the mechanism by which HD improves renal function.

RESULTS

HD can improve renal pathological damage and function; regulate blood lipids, inflammation and oxidative stress indicators; and reduce apoptosis in renal tissues. Joint protein and metabolomics analyses revealed that two lipid metabolism-related pathways (the PPAR signalling pathway and linoleic acid metabolism pathway) were coenriched, involving six differential proteins (Cyp2e1, Cyp4a10, Gk, Lpl, Ppara, and Pck1) and two differentially abundant metabolites (alpha-Dimorphecolic acid and 12,13-EpOME). Western blot was used to verify differentially expressed proteins. HD improved mitochondrial damage and lipid accumulation, as demonstrated by transmission electron microscopy (TEM) analysis and Oil Red O staining. Knockdown of the key protein Ppara affected the expression of ACOX1 and exacerbated RF. In vitro verification demonstrated that HD significantly inhibited CsA-induced EMT in HK-2 cells and improved mitochondrial structure and function. Ppara overexpression promoted HD-mediated regulation of mitochondrial function, reduced apoptosis, and improved HK-2 RF.

CONCLUSION

HD can ameliorate CsA nephrotoxicity through renal protein-serum metabolism coexpression, the PPAR signalling pathway, and linoleic acid metabolism. HD-induced upregulation of Ppara to regulate lipid metabolism, improve mitochondrial function and reduce apoptosis are important mechanisms. The Ppara/ACOX1/TGF-β1 axis may play an important role in this process. These findings offer potential targets for the future development of therapeutic strategies and novel drugs.

Oxybaphus himalaicus alleviates diabetic kidney disease by suppressing the lipid metabolism and inflammation via PPARα signaling

Diabetic kidney disease (DKD) is a common complication in patients with diabetes, and glycolipid metabolism disorders are an important cause of DKD. The root of Oxybaphus himalaicus (Edgew.) Heimerl is a traditional Tibetan medicine commonly used to treat kidney-related diseases. Nevertheless, contemporary pharmacological investigations into O. himalaicus, especially those associated with the treatment of renal disorders, remain scarce. The objective of this research was to explore the pharmaceutical impacts and mechanisms of action of O. himalaicus in the treatment of DKD. The active fraction and potential pharmacological effects of O. himalaicus were determined through network pharmacology. Then, in vivo and in vitro efficacy and mechanism studies were conducted through streptozotocin-induced DKD mice and high glucose-induced HK-2 cells. Network pharmacology research speculated the ethyl acetate (EA) fraction as the main active component of O. himalaicus for treating DKD. In vivo and in vitro experiments showed that EA reduces renal lipotoxicity by upregulating PPARα pathway proteins, enhancing fatty acid oxidation (FAO), and downregulating inflammatory factors such as TNF-α and IL-6. Molecular docking studies revealed that the active components of EA with a high affinity for PPARα are mainly rotenoid compounds. EA mitigates DKD through the activation of PPARα, which serves to augment FAO, abate lipid accumulation, and impede the expression of inflammatory factors. Among these, rotenoids may be the main active components that exert pharmacological effects.

Repurposing mitochondria-targeted therapeutics for kidney diseases

The kidney is one of the most metabolically demanding organs in the human body and requires a large amount of energy, in the form of adenosine triphosphate (ATP), to perform and maintain normal kidney functions. To meet this energy demand, proximal tubule cells within the nephron segments of the renal cortex are mitochondrially dense with high oxygen consumption rates. Mitochondria are complex organelles involved in diverse cellular and molecular functions, including the production of ATP, calcium homeostasis, and phospholipid regulation. Mitochondrial dysfunction is critical in the onset and progression of kidney disease. Dysfunctional renal mitochondria have been linked with alterations in redox homeostasis, impaired bioenergetics, oxidative stress, and inflammation, all of which result in renal cell injury and death, as well as fibrotic accumulation in kidney injury and disease. As such, interest in the development and/or repurposing of mitochondria-targeted therapeutics for the potential treatment of kidney diseases has recently surged. Although novel therapeutics and promising new drug targets have been identified, drug repurposing for kidney diseases offers numerous advantages over traditional drug discovery initiatives, including reduced cost, time of therapeutic development, and preclinical testing, in addition to known pharmacokinetics/pharmacodynamics and safety profiles. Here, we provide an overview of mitochondrial dysfunction in the context of kidney injury and disease and shed light on promising mitochondria-targeted therapeutic agents that display repurposing potential for the restoration of kidney function and/or acceleration of renal recovery.

Managing Dyslipidemia in Chronic Kidney Disease: Implications for Cardiovascular and Renal Risk

PURPOSE OF REVIEW

The review aims to address the complex relationship between dyslipidemia and chronic kidney disease (CKD), emphasizing its dual role in driving cardiovascular disease (CVD) risk and contributing to CKD progression. It explores pathophysiological mechanisms, highlights recent biomarker discoveries, and evaluates contemporary and emerging lipid-lowering therapies tailored for CKD patients.

RECENT FINDINGS

Recent studies have highlighted the inadequacy of traditional lipid markers like LDL-C in reflecting cardiovascular risk in CKD. Novel biomarkers, such as remnant cholesterol and lipoprotein(a), demonstrate stronger associations with adverse outcomes. Emerging lipid-lowering agents, including bempedoic acid, pemafibrate, and PCSK9 inhibitors, show promise for risk reduction, especially in non-dialysis-dependent CKD. However, evidence remains limited for advanced stages of CKD and dialysis patients. Furthermore, alterations in lipid metabolism, such as dysfunctional HDL and triglyceride-rich lipoproteins, are now recognized as significant contributors to CVD and renal damage in CKD populations. Dyslipidemia is a pivotal modifiable risk factor in CKD, exacerbating both cardiovascular risk and disease progression. While statins remain the cornerstone of therapy in early-to-moderate CKD, their efficacy diminishes in advanced stages. The advent of novel therapeutic options and a deeper understanding of dyslipidemia's pathophysiology hold potential for improving outcomes. Future research should prioritize personalized approaches, focusing on the unique metabolic derangements of CKD and advancing treatments for high-risk and dialysis-dependent patients.

Lipid abnormality in diabetic kidney disease and potential treatment advancements

Numerous studies have shown that dyslipidemia increases the risk of atherosclerotic cardiovascular disease (ASCVD) and significantly impacts the occurrence and progression of diabetic kidney disease (DKD). Early interventions for lipid metabolism disorders in DKD may improve renal function. This article reviews the clinical characteristics of dyslipidemia, mechanisms of lipid-induced renal injury, and advances in lipid-lowering therapy in DKD. We searched PubMed, Web of Science, and EMBASE to identify relevant articles, using keywords such as "diabetic kidney disease", "diabetic nephropathy", "diabetes", "dyslipidemia", "kidney", "cardiovascular disease", and "lipid therapy". High triglyceride (TG) and low high-density lipoprotein (HDL) are associated with increased risks of albuminuria and estimated glomerular filtration rate (eGFR) decline. Abnormal lipid metabolism may damage glomerular podocytes and renal tubular epithelial cells via ectopic lipid deposition, eventually impairing glomerular filtration function and increasing urinary albumin excretion. Lipid-lowering therapies can ameliorate lipid accumulation, downregulate inflammatory mediator expressions, and alleviate renal fibrosis. Fibrate and statin applications exhibit beneficial effects, reducing albuminuria and slowing eGFR decline in early DKD. However, the long-term effects of statins and fibrates on renal outcomes remain controversial. Pro-protein convertase subtilisin/kexin 9 (PCSK9)-targeted interventions have minimal side effects on the kidneys and seem effective in reducing inflammation and improving renal impairment compared with statins and fibrates. In addition, LDL apheresis (LDL-A) and double filtration plasmapheresis (DFPP) are promising clinical applications in diabetic patients with severe hypercholesterolemia or lipid-lowering drug intolerance.

Apocynin and Hyperbaric Oxygen Therapy Improve Renal Function and Structure in an Animal Model of CKD

BACKGROUND/OBJECTIVES

Chronic kidney disease (CKD) is a progressive pathological condition which results in the severe fibrosis of the kidneys. However, the mechanisms of CKD progression and fibrogenesis remain unclear. We wanted to examine the effects that apocynin and hyperbaric oxygen therapy (HBOT) have on renal function and structure in animals with CKD induced through 5/6 nephrectomy (5/6 Nx-L).

METHODS

Male Wistar rats were divided in 5 groups (n = 8/group) as follows: control-sham-operated rats; Nx-L-rats with 5/6 Nx-L; APO-5/6 Nx-L + apocynin treatment; HBOT-5/6 Nx-L + hyperbaric oxygen treatment, and APO+HBOT-5/6 Nx-L, treated with both treatments. All treatments started 4 weeks after the final step of CKD induction and lasted for 4 weeks. At the end of the experiment, urine samples were collected for the proteinuria assessment and the mean arterial pressure (MAP) was measured. Kidneys were collected for histopathological, Western blot, and immunohistochemical analyses.

RESULTS

All treatments significantly decreased MAP compared to the Nx-L group (p < 0.001). In the APO and APO+HBOT groups, the level of proteinuria was decreased compared to the Nx-L group (p < 0.05 and p < 0.01, respectively). All examined treatments significantly decreased the intensity of lesions in the kidney compared to those observed in the Nx-L group (p < 0.001). Isolated treatments with apocynin and HBOT induced a significant decrease in desmin expression compared to the Nx-L group (p < 0.05); meanwhile, they did not affect the levels of fibronectin (FN) and hypoxia-inducible factor-1α (HIF-1α). Combined treatment did not affect desmin expression levels; however, it induced a significant increase in fibronectin expression compared to Nx-L (p < 0.001).

CONCLUSIONS

Apocynin treatment decreased BP and protein loss, and it improved renal morphology at least partly through the downregulation of desmin expression without changing FN and HIF-1α. Hyperbaric oxygen therapy improved hypertension but failed to significantly affect the level of proteinuria. Combined treatment (apocynin and HBOT) normalized blood pressure (BP) values, renal function, and improved kidney structure by modulating FN and HIF-1α, without affecting desmin protein expression. Further studies are needed to elucidate the mechanisms of slowing down the progression of CKD in this experimental model.

Therapeutic approaches and novel antifibrotic agents in renal fibrosis: A comprehensive review

Renal fibrosis (RF) is one of the underlying pathological conditions leading to progressive loss of renal function and end-stage renal disease (ESRD). Over the years, various therapeutic approaches have been explored to combat RF and prevent ESRD. Despite significant advances in understanding the underlying molecular mechanism(s), effective therapeutic interventions for RF are limited. Current therapeutic strategies primarily target these underlying mechanisms to halt or reverse fibrotic progression. Inhibition of transforming growth factor-β (TGF-β) signaling, a pivotal mediator of RF has emerged as a central strategy to manage RF. Small molecules, peptides, and monoclonal antibodies that target TGF-β receptors or downstream effectors have demonstrated potential in preclinical models. Modulating the renin-angiotensin system and targeting the endothelin system also provide established approaches for controlling fibrosis-related hemodynamic changes. Complementary to pharmacological strategies, lifestyle modifications, and dietary interventions contribute to holistic management. This comprehensive review aims to summarize the underlying mechanisms of RF and provide an overview of the therapeutic strategies and novel antifibrotic agents that hold promise in its treatment.

Lessons from PROMINENT and prospects for pemafibrate

The neutral result of the PROMINENT trial has led to questions about the future for pemafibrate. This commentary discusses possible reasons for the lack of benefit observed in the trial. There were, however, indicators suggesting therapeutic potential in microvascular ischaemic complications associated with peripheral artery disease, with subsequent analysis showing reduction in the incidence of lower extremity ischaemic ulceration or gangrene. Reassurance about the safety of pemafibrate, together with emerging data from PROMINENT and experimental studies, also suggest benefit with pemafibrate in non-alcoholic fatty liver disease (alternatively referred to as metabolic dysfunction-associated steatotic liver disease) and microangiopathy associated with diabetes, which merit further study.

Kokusaginine attenuates renal fibrosis by inhibiting the PI3K/AKT signaling pathway

Kokusaginine is an active ingredient alkaloid that has been isolated and extracted from Ruta graveolens L. Some researches have indicated that alkaloids possess anti-inflammatory and antioxidant effects. Nevertheless, the potential nephroprotective effects of kokusaginine on renal fibrosis remain undetermined. This study was conducted to examine the protective effect of kokusaginine on renal fibrosis and to explore the underlying mechanisms using both in vivo and in vitro models. Renal fibrosis was induced in male C57BL/6 J mice by feeding with 0.2% adenine-containing food and UUO surgery. Kokusaginine was administered orally simultaneously after the establishment of renal fibrosis. Renal function was measured by serum levels of creatinine and urea nitrogen. Renal pathological changes were assessed by HE staining and Masson staining. Western blotting was employed to detect the expression levels of fibrosis-related proteins in mice and cells. Additionally, network pharmacology analysis and RNA-seq were utilized to predict the pathways through which kokusaginine could exert its anti-fibrotic effects. The treatment with kokusaginine enhanced renal function, alleviated renal histoarchitectural lesions, and mitigated renal fibrosis in the renal fibrosis models. The network pharmacology and RNA-seq enrichment analysis of the KEGG pathway demonstrated that kokusaginine could exert anti-renal fibrosis activity via the PI3K/AKT signaling pathway. And the results were verified in both in vitro and in vivo experiments. In conclusion, our data implied that kokusaginine inhibited the activation of the PI3K/AKT signaling pathway both in vitro and in vivo, and suppressed the formation of renal fibrosis. Thus, the kokusaginine-mediated PI3K/AKT signaling pathway may represent a novel approach for the treatment of renal fibrosis.

Association of NAFLD/NASH, and MAFLD/MASLD with chronic kidney disease: an updated narrative review

Chronic kidney disease (CKD) and nonalcoholic fatty liver disease (NAFLD), metabolic dysfunction-associated fatty liver disease (MAFLD) and metabolic dysfunction-associated steatotic liver disease (MASLD) account for substantial financial burden worldwide. These alarming features call for enhanced efforts to prevent and manage the development and progression of CKD. Accumulating evidence supporting a causal role of NAFLD/MAFLD/MASLD-in CKD opens new horizons to achieve this aim. Recent epidemiological studies and meta-analyses exploring the association of NAFLD/MAFLD/MASLD with CKD and the characteristics of NAFLD/MAFLD/MASLD associated with the odds of incident CKD are discussed. The involved pathomechanisms, including the common soil hypothesis, genetics, gut dysbiosis, and portal hypertension, are examined in detail. Finally, lifestyle changes (diet and physical exercise), direct manipulation of gut microbiota, and drug approaches involving statins, renin-angiotensin-aldosterone system inhibitors, GLP-1 Receptor Agonists, Sodium-glucose cotransporter-2, pemafibrate, and vonafexor are examined within the context of prevention and management of CKD among those with NAFLD/MAFLD/MASLD. The evolving NAFLD/MAFLD/MASLD nomenclature may generate confusion among practicing clinicians and investigators. However, comparative studies investigating the pros and contra of different nomenclatures may identify the most useful definitions among NAFLD/MAFLD/MASLD and strategies to identify, prevent, and halt the onset and progression of CKD.

Renoprotective strategies

Kidney disease remains a condition with an increasing incidence, high morbidity and mortality associated with cardiovascular events. The incidence of end-stage renal disease is expected to increase. Despite of the technical improvement, dialysis never achieved a full clearance of the blood dialysis. Therefore, the demand for new renoprotective measures has never been greater. Here, we report new strategies for preventing renal damage.

Oleoylethanolamide attenuates acute-to-chronic kidney injury: in vivo and in vitro evidence of PPAR-α involvement

Chronic kidney disease (CKD) development after acute kidney injury (AKI) involves multiple mechanisms, including inflammation, epithelial-mesenchymal transition (EMT), and extracellular matrix deposition, leading to progressive tubulointerstitial fibrosis. Recently, a central role for peroxisome-proliferator activated receptor (PPAR)-α has been addressed in preserving kidney function during AKI. Among endogenous lipid mediators, oleoylethanolamide (OEA), a PPAR-α agonist, has been studied for its metabolic and anti-inflammatory effects. Here, we have investigated OEA effects on folic acid (FA)-induced kidney injury in mice and the underlying mechanisms. OEA improved kidney function, normalized urine output, and reduced serum BUN, creatinine, and albuminuria. Moreover, OEA attenuated tubular epithelial injury, as shown by histological analysis, and decreased expression of neutrophil gelatinase-associated lipocalin and kidney injury molecule-1. Gene expression analysis of kidney tissue indicated that OEA limited immune cell infiltration and inflammation. Moreover, OEA significantly inhibited Wnt7b and Catnb1 gene transcription and α-smooth muscle actin expression, indicating suppression of EMT. Accordingly, OEA exhibited an anti-fibrotic effect, as shown by Masson staining and the reduced levels of transforming growth factor (TGF)-β1, fibronectin, and collagen IV. Mechanistically, the nephroprotective effect of OEA was related to PPAR-α activation since OEA failed to exert its beneficial activity in FA-insulted PPAR-α-/- mice. PPAR-α involvement was also confirmed in HK2 cells where GW6471, a PPAR-α antagonist, blunted OEA activity on the TGF-β1 signalling pathway and associated pro-inflammatory and fibrotic patterns. Our findings revealed that OEA counteracts kidney injury by controlling inflammation and fibrosis, making it an effective therapeutic tool for limiting AKI to CKD progression.

Focus on Mitochondrial Respiratory Chain: Potential Therapeutic Target for Chronic Renal Failure

The function of the respiratory chain is closely associated with kidney function, and the dysfunction of the respiratory chain is a primary pathophysiological change in chronic kidney failure. The incidence of chronic kidney failure caused by defects in respiratory-chain-related genes has frequently been overlooked. Correcting abnormal metabolic reprogramming, rescuing the "toxic respiratory chain", and targeting the clearance of mitochondrial reactive oxygen species are potential therapies for treating chronic kidney failure. These treatments have shown promising results in slowing fibrosis and inflammation progression and improving kidney function in various animal models of chronic kidney failure and patients with chronic kidney disease (CKD). The mitochondrial respiratory chain is a key target worthy of attention in the treatment of chronic kidney failure. This review integrated research related to the mitochondrial respiratory chain and chronic kidney failure, primarily elucidating the pathological status of the mitochondrial respiratory chain in chronic kidney failure and potential therapeutic drugs. It provided new ideas for the treatment of kidney failure and promoted the development of drugs targeting the mitochondrial respiratory chain.