Effect of dimethyl fumarate on renal disease progression in a genetic ortholog of nephronophthisis

Repurposing Dimethyl Fumarate for Cardiovascular Diseases: Pharmacological Effects, Molecular Mechanisms, and Therapeutic Promise

Dimethyl fumarate (DMF) is a small molecule that has been shown to assert potent in vivo immunoregulatory and anti-inflammatory therapeutic actions. The drug has been approved and is currently in use for treating multiple sclerosis and psoriasis in the USA and Europe. Since inflammatory reactions have been significantly implicated in the etiology and progression of diverse disease states, the pharmacological actions of DMF are presently being explored and generalized to other diseases where inflammation needs to be suppressed and immunoregulation is desirable, either as a monotherapeutic agent or as an adjuvant. In this review, we focus on DMF, and present an overview of its mechanism of action while briefly discussing its pharmacokinetic profile. We further discuss in detail its pharmacological uses and highlight its potential applications in the treatment of cardiovascular diseases. DMF, with its unique combination of anti-inflammatory and vasculoprotective effects, has the potential to be repurposed as a therapeutic agent in patients with atherosclerotic cardiovascular disease. The clinical studies mentioned in this review with respect to the beneficial effects of DMF in atherosclerosis involve observations in patients with multiple sclerosis and psoriasis in small cohorts and for short durations. The findings of these studies need to be assessed in larger prospective clinical trials, ideally with a double-blind randomized study design, investigating the effects on cardiovascular endpoints as well as morbidity and mortality. The long-term impact of DMF therapy on cardiovascular diseases also needs to be confirmed.

Renal Ciliopathies: Sorting Out Therapeutic Approaches for Nephronophthisis

Nephronophthisis (NPH) is an autosomal recessive ciliopathy and a major cause of end-stage renal disease in children. The main forms, juvenile and adult NPH, are characterized by tubulointerstitial fibrosis whereas the infantile form is more severe and characterized by cysts. NPH is caused by mutations in over 20 different genes, most of which encode components of the primary cilium, an organelle in which important cellular signaling pathways converge. Ciliary signal transduction plays a critical role in kidney development and tissue homeostasis, and disruption of ciliary signaling has been associated with cyst formation, epithelial cell dedifferentiation and kidney function decline. Drugs have been identified that target specific signaling pathways (for example cAMP/PKA, Hedgehog, and mTOR pathways) and rescue NPH phenotypes in in vitro and/or in vivo models. Despite identification of numerous candidate drugs in rodent models, there has been a lack of clinical trials and there is currently no therapy that halts disease progression in NPH patients. This review covers the most important findings of therapeutic approaches in NPH model systems to date, including hypothesis-driven therapies and untargeted drug screens, approached from the pathophysiology of NPH. Importantly, most animal models used in these studies represent the cystic infantile form of NPH, which is less prevalent than the juvenile form. It appears therefore important to develop new models relevant for juvenile/adult NPH. Alternative non-orthologous animal models and developments in patient-based in vitro model systems are discussed, as well as future directions in personalized therapy for NPH.

Dimethyl fumarate protects nucleus pulposus cells from inflammation and oxidative stress and delays the intervertebral disc degeneration

Lower back pain is a common problem in middle-aged and elderly people, and intervertebral disc degeneration (IVDD) is often the main cause. The present study aimed to explore the effects of dimethyl fumarate (DMF) on inflammation and oxidative stress in the intervertebral disc. C57/BL6 mice were used to construct an IVDD model by tail suspension and daily intraperitoneal injections of 10 mg/kg DMF were administered to analyze the effects of DMF on IVDD. In addition, human nucleus pulposus (NP) cells were cultured and stimulated cells with recombinant human IL-1β and DMF to examine the effects of DMF on inflammation and oxidative stress in NP cells. DMF significantly increased the intervertebral disc height index of mice and inhibited the degradation of the extracellular matrix of mouse NP tissue. In addition, DMF also decreased the expression of inflammatory factors [including IL-6, IL-8, matrix metalloproteinase (MMP)3 and MMP13] in NP cells. In terms of oxidative stress, DMF significantly increased the antioxidative stress response in NP cells and reduced endoplasmic reticulum stress. DMF also increased the activity of the nuclear factor erythroid 2-related factor (Nrf) 2/heme oxygenase (HO)-1 signaling pathway in NP cells and increased the phosphorylation of Akt. DMF also increased the anti-inflammatory and antioxidative ability of NP cells by promoting the activity of the Nrf2/HO-1 and PI3K/Akt signaling pathways, thus delaying IVDD.

Filtering through the role of NRF2 in kidney disease

Kidney disease affects ~ 10% of the population worldwide, resulting in millions of deaths each year. Mechanistically, oxidative stress is a major driver of various kidney diseases, and promotes the progression from acute to chronic injury, as well as renal cancer development. NRF2, the master regulator of redox balance, has been shown to protect against kidney disease through its negation of reactive oxygen species (ROS). However, many kidney diseases exhibit high levels of ROS as a result of decreased NRF2 protein levels and transcriptional activity. Many studies have tested the strategy of using NRF2 inducing compounds to alleviate ROS to prevent or slow down the progression of kidney diseases. Oppositely, in specific subsets of renal cancer, NRF2 is constitutively activated and contributes to tumor burden and overall poor prognosis; therefore, there has been a recent interest in studies investigating the benefits of NRF2 inhibition. In this review, we summarize recent literature investigating the role of NRF2 and oxidative stress in various kidney diseases, and how pharmacological modification of NRF2 signaling could play a protective role.

Dimethyl fumarate ameliorates cisplatin-induced renal tubulointerstitial lesions

Dimethyl fumarate (DMF) has an antioxidant effect by activating the nuclear factor erythroid 2-related transcription factor 2 (Nrf2). Cisplatin (CIS) has nephrotoxicity as a frequently associated side effect that is mainly mediated by oxidative stress. In this study, we investigated whether the DMF-mediated antioxidative mechanism activated by Nrf2 can ameliorate CIS-induced renal tubulointerstitial lesions in rats. In Experiments 1 and 2, 25 five-week-old male Wistar rats were divided into five groups: control, CIS, and 3 CIS+DMF groups (300, 1,500, and 7,500 ppm in Experiment 1; 2,000, 4,000, and 6,000 ppm in Experiment 2). Rats were fed their respective DMF-containing diet for 5 weeks. CIS was injected 1 week after starting DMF administration, and the same volume of saline was injected into the control group. CIS-induced severe tubular injury, such as necrosis and degeneration in the outer segment of the outer medulla, was inhibited in the 7,500 ppm DMF group and ameliorated in all DMF groups in Experiment 2. Increased interstitial mononuclear cell infiltration and increased Sirius red-positive areas were also observed in CIS-administered groups, and these increases tended to be dose-dependently inhibited by DMF co-administration in Experiments 1 and 2. The numbers of α-smooth muscle actin (SMA)-positive myofibroblasts, CD68-positive macrophages, and CD3-positive lymphocytes observed in the peritubular area also increased with CIS administration, and these increases were dose-dependently inhibited by DMF co-administration. Moreover, renal cortical mRNA expression of Nrf2-related genes such as NQO1 increased in DMF groups. This investigation showed that DMF ameliorates CIS-induced renal tubular injury via NQO1-mediated antioxidant mechanisms and reduces the consequent tubulointerstitial fibrosis.

Nrf2 activator for the treatment of kidney diseases

Kidney diseases are highly prevalent worldwide, and significantly reduce the quality of life of patients, creating an urgent need for effective therapeutic modalities. Despite this significant unmet medical need, none of the drugs launched to date have demonstrated promising potential to cure kidney diseases. This is likely due to the structural complexity of the kidney as well as difficulties in setting appropriate endpoints for clinical trials and identifying appropriate therapeutic targets. Recently, an alternative endpoint for clinical trials (i.e., a 30% or 40% reduction in estimated glomerular filtration rate [eGFR] from baseline following 2-3 years of observation) has been considered in the United States, European Union, and Japan, and is expected to contribute to the progress of drug development for kidney diseases. Further, oxidative stress and inflammation are currently thought to be key factors in the progression of kidney diseases, prompting more research on drugs targeting the mechanisms related to these factors for treatment. The Kelch-like ECH-associated protein 1-nuclear factor erythroid 2-related factor 2 (Keap1-Nrf2) system has drawn much attention in recent years for its anti-oxidative and anti-inflammatory properties, and its pharmacological potential for treatment of kidney diseases is being widely investigated in both clinical and non-clinical studies. This review summarizes the current issues in the treatment of kidney diseases, including clinical endpoints, Nrf2 activators as treatment options, and perspectives on pharmaceutical applications of Nrf2 activators.

Nephronophthisis: A review of genotype-phenotype correlation

Nephronophthisis is an autosomal recessive cystic kidney disease and one of the most common genetic disorders causing end‐stage renal disease in children. Nephronophthisis is a genetically heterogenous disorder with more than 25 identified genes. In 10%–20% of cases, there are additional features of a ciliopathy syndrome, such as retinal defects, liver fibrosis, skeletal abnormalities, and brain developmental disorders. This review provides an update of the recent advances in the clinical features and related gene mutations of nephronophthisis, and novel approaches for therapy in nephronophthisis patients may be needed.

Nephronophthisis (NPHP) is a renal ciliopathy affecting children and young adults. This review gives an update on the recent advances in the clinical features and related gene mutations of NPHP.