NLRP3 Inflammasome in Metabolic-Associated Kidney Diseases: An Update

The role of perirenal adipose tissue deposition in chronic kidney disease progression: Mechanisms and therapeutic implications

Chronic kidney disease (CKD) represents a significant and escalating global health challenge, with morbidity and mortality rates rising steadily. Evidence increasingly implicates perirenal adipose tissue (PRAT) deposition as a contributing factor in the pathogenesis of CKD. This review explores how PRAT deposition may exert deleterious effects on renal structure and function. The anatomical proximity of PRAT to the kidneys not only potentially causes mechanical compression but also leads to the dysregulated secretion of adipokines and inflammatory mediators, such as adiponectin, leptin, visfatin, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and exosomes. Additionally, PRAT deposition may contribute to renal lipotoxicity through elevated levels of free fatty acids (FFA), triglycerides (TAG), diacylglycerol (DAG), and ceramides (Cer). PRAT deposition is also linked to the hyperactivation of the renin-angiotensin-aldosterone system (RAAS), which further exacerbates CKD progression. Recognizing PRAT deposition as an independent risk factor for CKD underscores the potential of targeting PRAT as a novel strategy for the prevention and management of CKD. This review further discusses interventions that could include measuring PRAT thickness to establish a baseline, managing metabolic risk factors that promote its deposition, and inhibiting key PRAT-induced signaling pathways.

Icariin Reduces Cadmium-induced Renal Injury in Rats

Icariin (ICA), an active ingredient found in Epimedium, possesses antioxidant and anti-inflammatory properties and has garnered widespread attention in recent years. This study investigated the protective effects of ICA against cadmium (Cd)-induced kidney injury in rats. Healthy male specific pathogen-free Sprague-Dawley rats were randomly divided into a control group, Cd group, a low-dose ICA group, a middle-dose ICA group, and a high-dose ICA group using a random number table. Tissue and blood samples were analyzed for renal function markers, histopathology, and gene expression. We found that ICA intervention ameliorates Cd-induced nephrotoxicity by enhancing glomerular filtration, mitigating renal tubular epithelial cell damage, reducing cellular degeneration and edema, and decreasing oxidative stress. ICA demonstrated anti-apoptotic activity through the regulation of pro- and anti-apoptotic gene transcription and by inhibiting apoptosis, thus protecting the kidneys. ICA also exhibited anti-inflammatory effects by reducing the transcription of Cd-induced pro-inflammatory genes, inhibiting nucleotide oligomerization domain-like receptor pyrin domain-containing 3 (NLRP3) inflammasome formation, and preventing pyroptosis. ICA potentially regulated the Toll-like receptor 4/P2rx7/nuclear factor kappa B signaling pathway, which modulated the activation of the NLRP3 inflammasome and contributed to its anti-inflammatory action. ICA reduced Cd-induced renal injury in rats, likely through a mechanism involving antioxidant, anti-apoptotic, and anti-inflammatory effects.

Exploring the role of NLRP3 inflammasome in diabetic nephropathy and the advancements in herbal therapeutics

Diabetic nephropathy (DN), a prevalent complication of diabetes mellitus (DM), is clinically marked by progressive proteinuria and a decline in glomerular filtration rate. The etiology and pathogenesis of DN encompass a spectrum of factors, including hemodynamic alterations, inflammation, and oxidative stress, yet remain incompletely understood. The NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome, a critical component of the body's innate immunity, plays a pivotal role in the pathophysiology of DN by promoting the release of inflammatory cytokines, thus contributing to the progression of this chronic inflammatory condition. Recent studies highlight the involvement of the NLRP3 inflammasome in the renal pathology associated with DN. This article delves into the activation pathways of the NLRP3 inflammasome and its pathogenic implications in DN. Additionally, it reviews the therapeutic potential of traditional Chinese medicine (TCM) in modulating the NLRP3 inflammasome, aiming to provide comprehensive insights into the pathogenesis of DN and the current advancements in TCM interventions targeting NLRP3 inflammatory vesicles. Such insights are expected to lay the groundwork for further exploration into TCM-based treatments for DN.

Role of mitochondria in pathogenesis and therapy of renal fibrosis

Renal fibrosis, specifically tubulointerstitial fibrosis, represents the predominant pathological consequence observed in the context of progressive chronic kidney conditions. The pathogenesis of renal fibrosis encompasses a multifaceted interplay of mechanisms, including but not limited to interstitial fibroblast proliferation, activation, augmented production of extracellular matrix (ECM) components, and impaired ECM degradation. Notably, mitochondria, the intracellular organelles responsible for orchestrating biological oxidation processes in mammalian cells, assume a pivotal role within this intricate milieu. Mitochondrial dysfunction, when manifest, can incite a cascade of events, including inflammatory responses, perturbed mitochondrial autophagy, and associated processes, ultimately culminating in the genesis of renal fibrosis. This comprehensive review endeavors to furnish an exegesis of mitochondrial pathophysiology and biogenesis, elucidating the precise mechanisms through which mitochondrial aberrations contribute to the onset and progression of renal fibrosis. We explored how mitochondrial dysfunction, mitochondrial cytopathy and mitochondrial autophagy mediate ECM deposition and renal fibrosis from a multicellular perspective of mesangial cells, endothelial cells, podocytes, macrophages and fibroblasts. Furthermore, it succinctly encapsulates the most recent advancements in the realm of mitochondrial-targeted therapeutic strategies aimed at mitigating renal fibrosis.

Inulin Reduces Kidney Damage in Type 2 Diabetic Mice by Decreasing Inflammation and Serum Metabolomics

This study is aimed at assessing the impact of soluble dietary fiber inulin on the treatment of diabetes-related chronic inflammation and kidney injury in mice with type 2 diabetes (T2DM). The T2DM model was created by feeding the Institute of Cancer Research (ICR) mice a high-fat diet and intraperitoneally injecting them with streptozotocin (50 mg/kg for 5 consecutive days). The thirty-six ICR mice were divided into three dietary groups: the normal control (NC) group, the T2DM (DM) group, and the DM + inulin diet (INU) group. The INU group mice were given inulin at the dose of 500 mg/kg gavage daily until the end of the 12th week. After 12 weeks, the administration of inulin resulted in decreased serum levels of fasting blood glucose (FBG), low-density lipoprotein cholesterol (LDL-C), blood urea nitrogen (BUN), and creatinine (CRE). The administration of inulin not only ameliorated renal injury but also resulted in a reduction in the mRNA expressions of inflammatory factors in the spleen and serum oxidative stress levels, when compared to the DM group. Additionally, inulin treatment in mice with a T2DM model led to a significant increase in the concentrations of three primary short-chain fatty acids (SCFAs) (acetic acid, propionic acid, and butyric acid), while the concentration of advanced glycation end products (AGEs), a prominent inflammatory factor in diabetes, exhibited a significant decrease. The results of untargeted metabolomics indicate that inulin has the potential to alleviate inflammatory response and kidney damage in diabetic mice. This beneficial effect is attributed to its impact on various metabolic pathways, including glycerophospholipid metabolism, taurine and hypotaurine metabolism, arginine biosynthesis, and tryptophan metabolism. Consequently, oral inulin emerges as a promising treatment option for diabetes and kidney injury.

Long-Term Protective Effects and Mechanisms of Gastric Bypass Surgery on the Kidneys in Hypertensive Obese Rat

OBJECTIVE

Investigate the long-term protective effects of gastric bypass surgery on the kidneys of hypertensive obese rats to better understand the role of gastric bypass surgery in preventing renal injury in humans with hypertension and obesity.

METHODS

Compare 6-week-old spontaneously hypertensive rats, including 30 Roux-en-Y gastric bypass (RYGB) and 30 sham operations. Body weight and blood pressure were monitored before and up to 12 months after the operation. Blood lipids, blood creatinine, and blood urea nitrogen were measured. Kidney pathology was assessed using HE staining, while renal fibrosis was observed via Masson staining. Inflammatory indicators were examined by ELISA. The expression of the NLRP3 gene in the kidney was measured using immunofluorescence and western blot, and the changes in key pathways including ASC/IL-1β protein were verified.

RESULTS

RYGB reduced the body weight of hypertensive obese rats and had a protective effect on blood pressure. Additionally, the bypass effectively mitigated renal inflammation and fibrosis. Moreover, RYGB modulated the expression of NLRP3 and prevented kidney damage via the ASC/IL-1 pathway.

CONCLUSION

This study validates that RYGB effectively attains sustained blood pressure control in hypertensive obese rats and has a potential kidney-protective mechanism via the NLRP3-ASC/IL-1β pathway.

Comprehensive analysis of the relationship between xanthine oxidoreductase activity and chronic kidney disease

Chronic kidney disease (CKD) is a common disease that seriously endangers human health. However, the potential relationship between xanthine oxidoreductase (XOR) activity and CKD remains unclear. In this study, we used clinical data, CKD datasets from the Gene Expression Omnibus database, and untargeted metabolomics to explain the relationship between XOR activity and CKD. First, XOR activity showed high correlation with the biomarkers of CKD, such as serum creatinine, blood urea nitrogen, uric acid, and estimated glomerular filtration rate. Then, we used least absolute shrinkage and selection operator logical regression algorithm and random forest algorithm to screen CKD molecular markers from differentially expressed genes, and the results of qRT-PCR of XDH, KOX-1, and ROMO1 were in accordance with the results of bioinformatics analyses. In addition, untargeted metabolomics analysis revealed that the purine metabolism pathway was significantly enriched in CKD patients in the simulated models of kidney fibrosis.

C/EBPβ-TFAM-Mediated NLRP3 Inflammasome Activation Contributes to Arsenic-Induced Rat Kidney Injury

Compelling evidence has demonstrated that arsenic (As) exposure is associated with kidney injuries. Given that inflammatory responses and immune imbalances are the root causes of several kidney diseases, this study investigated the potential mechanisms underlying NLRP3 inflammasome activation in As-induced kidney injury. A rat model of sub-chronic As exposure was established via oral administration of NaAsO2. The results revealed that urinary β-2-microglobulin (β2-MG), N-acetyl-β-D-glucosidase (NAG) and albumin (ALB) were increased in the As-exposed group, reflecting kidney impairment. Moreover, significant glomerular vacuole-like changes, tubular dilatation and inflammatory cell infiltration were observed. Meanwhile, the expression levels of neutrophil gelatinase-associated lipocalin (NGAL), IL-1β and IL-18 were enhanced in the kidney tissues of As-treated rats. Further, increased expression of NLRP3, ASC and caspase-1, which are NLRP3 inflammasome-associated proteins, were observed in the kidney tissues of rats in the As-treated groups. The expression levels of the NLRP3 upstream regulators C/EBPβ and TFAM were also elevated. These findings suggest that sub-chronic As exposure triggers inflammatory responses in rat kidney tissue and impairs kidney function. The underlying mechanisms may be related to the C/EBPβ-TFAM pathway and activation of the NLRP3 inflammasome pathway.

The Interplay between Immune and Metabolic Pathways in Kidney Disease

Kidney disease is a significant health problem worldwide, affecting an estimated 10% of the global population. Kidney disease encompasses a diverse group of disorders that vary in their underlying pathophysiology, clinical presentation, and outcomes. These disorders include acute kidney injury (AKI), chronic kidney disease (CKD), glomerulonephritis, nephrotic syndrome, polycystic kidney disease, diabetic kidney disease, and many others. Despite their distinct etiologies, these disorders share a common feature of immune system dysregulation and metabolic disturbances. The immune system and metabolic pathways are intimately connected and interact to modulate the pathogenesis of kidney diseases. The dysregulation of immune responses in kidney diseases includes a complex interplay between various immune cell types, including resident and infiltrating immune cells, cytokines, chemokines, and complement factors. These immune factors can trigger and perpetuate kidney inflammation, causing renal tissue injury and progressive fibrosis. In addition, metabolic pathways play critical roles in the pathogenesis of kidney diseases, including glucose and lipid metabolism, oxidative stress, mitochondrial dysfunction, and altered nutrient sensing. Dysregulation of these metabolic pathways contributes to the progression of kidney disease by inducing renal tubular injury, apoptosis, and fibrosis. Recent studies have provided insights into the intricate interplay between immune and metabolic pathways in kidney diseases, revealing novel therapeutic targets for the prevention and treatment of kidney diseases. Potential therapeutic strategies include modulating immune responses through targeting key immune factors or inhibiting pro-inflammatory signaling pathways, improving mitochondrial function, and targeting nutrient-sensing pathways, such as mTOR, AMPK, and SIRT1. This review highlights the importance of the interplay between immune and metabolic pathways in kidney diseases and the potential therapeutic implications of targeting these pathways.

Peroxiredoxin-4 and Dopamine D5 Receptor Interact to Reduce Oxidative Stress and Inflammation in the Kidney

Aims: Reactive oxygen species are highly reactive molecules generated in different subcellular compartments. Both the dopamine D5 receptor (D5R) and endoplasmic reticulum (ER)-resident peroxiredoxin-4 (PRDX4) play protective roles against oxidative stress. This study is aimed at investigating the interaction between PRDX4 and D5R in regulating oxidative stress in the kidney. Results: Fenoldopam (FEN), a D1R and D5R agonist, increased PRDX4 protein expression, mainly in non-lipid rafts, in D5R-HEK 293 cells. FEN increased the co-immunoprecipitation of D5R and PRDX4 and their colocalization, particularly in the ER. The efficiency of Förster resonance energy transfer was increased with FEN treatment measured with fluorescence lifetime imaging microscopy. Silencing of PRDX4 increased hydrogen peroxide production, impaired the inhibitory effect of FEN on hydrogen peroxide production, and increased the production of interleukin-1β, tumor necrosis factor (TNF), and caspase-12 in renal cells. Furthermore, in Drd5-/- mice, which are in a state of oxidative stress, renal cortical PRDX4 was decreased whereas interleukin-1β, TNF, and caspase-12 were increased, relative to their normotensive wild-type Drd5+/+ littermates. Innovation: Our findings demonstrate a novel relationship between D5R and PRDX4 and the consequent effects of this relationship in attenuating hydrogen peroxide production in the ER and the production of proinflammatory cytokines. This study provides the potential for the development of biomarkers and new therapeutics for renal inflammatory disorders, including hypertension. Conclusion: PRDX4 interacts with D5R to decrease oxidative stress and inflammation in renal cells that may have the potential for translational significance. Antioxid. Redox Signal. 38, 1150-1166.

PROPHYLACTIC n CMT-3 ATTENUATES SEPSIS-INDUCED ACUTE KIDNEY INJURY IN ASSOCIATION WITH NLRP3 INFLAMMASOME ACTIVATION AND APOPTOSIS

ABSTRACT

Background: The kidney is the most common extrapulmonary organ injured in sepsis. The current study examines the ability of aerosolized nanochemically modified tetracycline 3 (nCMT-3), a pleiotropic anti-inflammatory agent, to attenuate acute kidney injury (AKI) caused by intratracheal LPS. Methods: C57BL/6 mice received aerosolized intratracheal nCMT-3 (1 mg/kg) or saline, followed by intratracheal LPS (2.5 mg/kg) to induce acute lung injury-induced AKI. Tissues were harvested at 24 h. The effects of nCMT-3 and LPS on AKI were assessed by plasma/tissue levels of serum urea nitrogen, creatinine, neutrophil gelatinase-associated lipocalin, kidney injury molecule 1, and renal histology. Renal matrix metalloproteinase (MMP) level/activity, cytochrome C, Bax, Bcl-2, caspase-3, p38 mitogen-activated protein kinase activation, NLRP3, and caspase-1 were also measured. Apoptotic cells in kidney were determined by TUNEL assay. Renal levels of IL-1β and IL-6 were measured to assess inflammation. Results: Acute lung injury-induced AKI was characterized by increased plasma blood urea nitrogen, creatinine, injury biomarkers (neutrophil gelatinase-associated lipocalin, kidney injury molecule 1), and histologic evidence of renal injury. Lipopolysaccharide-treated mice demonstrated renal injury with increased levels of inflammatory cytokines (IL-1β, IL-6), active MMP-2 and MMP-9, proapoptotic proteins (cytochrome C, Bax/Bcl-2 ratio, cleaved caspase-3), apoptotic cells, inflammasome activation (NLRP3, caspase-1), and p38 signaling. Intratracheal nCMT-3 significantly attenuated all the measured markers of renal injury, inflammation, and apoptosis. Conclusions: Pretreatment with aerosolized nCMT-3 attenuates LPS-induced AKI by inhibiting renal NLRP3 inflammasome activation, renal inflammation, and apoptosis.

SGLT-2 Inhibitors and the Inflammasome: What's Next in the 21st Century?

The nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome in the kidney and the heart is increasingly being suggested to play a key role in mediating inflammation. In the kidney, NLRP3 activation was associated with the progression of diabetic kidney disease. In the heart, activation of the NLRP3 inflammasome was related to the enhanced release of interleukin-1β (IL-1β) and the subsequent induction of atherosclerosis and heart failure. Apart from their glucose-lowering effects, SGLT-2 inhibitors were documented to attenuate activation of the NLRP3, thus resulting in the constellation of an anti-inflammatory milieu. In this review, we focus on the interplay between SGLT-2 inhibitors and the inflammasome in the kidney, the heart and the neurons in the context of diabetes mellitus and its complications.

Nephroprotective plant species used in traditional Mayan Medicine for renal-associated diseases

ETHNOPHARMACOLOGICAL RELEVANCE

The prevalence of kidney disease has increased rapidly in recent years and has emerged as one of the leading causes of mortality worldwide. Natural products have been suggested as valuable nephroprotective agents due to their multi-target and synergistic effects on modulating important proteins involved in kidney injury. There is a large number of plant species that have been used traditionally for kidney-related conditions in Mesoamerican medicine by different cultural groups that could provide a valuable source of nephroprotective therapeutic candidates and could lead to potential drug discovery.

AIM OF REVIEW

This review aims to provide an overview of the currently known efficacy of plant species used traditionally in Mesoamerica by Mayan groups to treat kidney-related conditions and to analyze the phytochemical, pharmacological, molecular, toxicological, and clinical evidence to contribute to public health efforts and for directing future research.

METHODS

Primary sources of plant use reports for traditional kidney-related disorders in Mesoamerica were searched systematically from library catalogs, theses, and scientific databases (PubMed, Google Scholar; and Science Direct), and were filtered according to usage frequency in Mayan groups and plant endemism. The database of traditional plants was further analyzed based on associations with published reports of the phytochemical, pharmacological, molecular, toxicological, and clinical evidence.

RESULTS

The most reported kidney-related conditions used traditionally in Mayan medicine involve reducing renal damage (a cultural interpretation that considers an inflammatory or infectious condition), cleaning or purifying the blood and kidney, reducing kidney pain, and eliminating kidney stones. A total of 208 plants used for kidney-related problems by 10 Mayan groups were found, representing 143 native species, where only 42 have reported pharmacological activity against kidney damage, mainly approached by in vitro and in vivo models of chemical- or drug-induced nephrotoxicity, diabetes nephropathy, and renal injury produced by hypertension. Nephroprotective effects are mainly mediated by reducing oxidative stress, inflammatory response, fibrosis mechanisms, and apoptosis in the kidney. The most common nephroprotective compounds associated with traditional Mayan medicine were flavonoids, terpenoids, and phenolic acids. The most widely studied traditional plants in terms of pharmacological evidence, bioactive compounds, and mechanisms of action, are Annona muricata L., Carica papaya L., Ipomoea batatas (L.) Lam., Lantana camara L., Sechium edule (Jacq.) Sw., Tagetes erecta L., and Zea mays L. Most of the plant species with reported pharmacological activity against kidney damage were considered safe in toxicological studies.

CONCLUSION

Available pharmacological reports suggest that several herbs used in traditional Mayan medicine for renal-associated diseases may have nephroprotective effects and consistent pharmacological evidence, nephroprotective compounds, and mechanisms of action in different models of kidney injury. However, more research is required to fully understand the potential of traditional Mayan medicine in drug discovery given the limited ethnobotanical studies and data available for most species with regards to identification on bioactive components, pharmacological mechanisms, and the scarce number of clinical studies.

DNA methylation in diabetic retinopathy: pathogenetic role and potential therapeutic targets

Background

Diabetic retinopathy (DR), a specific neuron-vascular complication of diabetes, is a major cause of vision loss among middle-aged people worldwide, and the number of DR patients will increase with the increasing incidence of diabetes. At present, it is limited in difficult detection in the early stages, limited treatment and unsatisfactory treatment effects in the advanced stages.

Main body

The pathogenesis of DR is complicated and involves epigenetic modifications, oxidative stress, inflammation and neovascularization. These factors influence each other and jointly promote the development of DR. DNA methylation is the most studied epigenetic modification, which has been a key role in the regulation of gene expression and the occurrence and development of DR. Thus, this review investigates the relationship between DNA methylation and other complex pathological processes in the development of DR. From the perspective of DNA methylation, this review provides basic insights into potential biomarkers for diagnosis, preventable risk factors, and novel targets for treatment.

Conclusion

DNA methylation plays an indispensable role in DR and may serve as a prospective biomarker of this blinding disease in its relatively early stages. In combination with inhibitors of DNA methyltransferases can be a potential approach to delay or even prevent patients from getting advanced stages of DR.

The Interplay between Ghrelin and Microglia in Neuroinflammation: Implications for Obesity and Neurodegenerative Diseases

Numerous studies have shown that microglia are capable of producing a wide range of chemokines to promote inflammatory processes within the central nervous system (CNS). These cells share many phenotypical and functional characteristics with macrophages, suggesting that microglia participate in innate immune responses in the brain. Neuroinflammation induces neurometabolic alterations and increases in energy consumption. Microglia may constitute an important therapeutic target in neuroinflammation. Recent research has attempted to clarify the role of Ghre signaling in microglia on the regulation of energy balance, obesity, neuroinflammation and the occurrence of neurodegenerative diseases. These studies strongly suggest that Ghre modulates microglia activity and thus affects the pathophysiology of neurodegenerative diseases. This review aims to summarize what is known from the current literature on the way in which Ghre modulates microglial activity during neuroinflammation and their impact on neurometabolic alterations in neurodegenerative diseases. Understanding the role of Ghre in microglial activation/inhibition regulation could provide promising strategies for downregulating neuroinflammation and consequently for diminishing negative neurological outcomes.

Evaluation of Subclinical Vascular Disease in Diabetic Kidney Disease: A Tool for Personalization of Management of a High-Risk Population

Background: Patients with diabetic kidney disease (DKD) are at increased risk for cardiovascular events but traditional risk factors do not fully explain this association. Evaluation of subclinical vascular disease might improve risk stratification and management of these patients. The aim of the study was to compare the prevalence of markers of arterial stiffness, carotid atherosclerosis and peripheral arterial disease between patients with DKD and patients with type 2 diabetes mellitus (T2DM) and preserved kidney function. Methods: We prospectively enrolled patients with DKD and age- and gender-matched patients with T2DM but without DKD (estimated glomerular filtration rate < and ≥60 mL/min/1.73 m2, respectively). The presence of arterial stiffness was evaluated by measuring pulse wave velocity (PWV), augmentation index (AIx), AIx adjusted to a heart rate of 75 beats/min (AIx@75) and central systolic, diastolic, pulse and mean blood pressure. The presence of carotid atherosclerosis was evaluated by measuring carotid stenosis, carotid intima-media thickness and maximal plaque thickness. The presence of PAD was evaluated with the measurement of ankle-brachial index (ABI). Results: Forty patients with T2DM were included in the study (mean age 71.6 ± 8.9 years). The prevalence of cardiovascular risk factors was similar in patients with and without DKD. PWV was higher in the former (9.8 ± 5.5 and 6.6 ± 4.4 m/s, respectively; p < 0.05) and carotid stenosis of the left carotid artery was also greater in patients with DKD (36.5 ± 12.6 and 22.1 ± 17.2%, respectively; p < 0.05). Other markers of arterial stiffness and carotid atherosclerosis and ABI did not differ between patients with DKD and those without DKD. Conclusions: Patients with DKD appear to have more pronounced arterial stiffness and carotid atherosclerosis than patients with T2DM and preserved kidney function despite the similar prevalence of traditional cardiovascular risk factors in the two groups. Therefore, evaluating the presence of subclinical vascular disease in these patients could be a useful tool for the personalization of their management.

Signaling pathways of chronic kidney diseases, implications for therapeutics

Chronic kidney disease (CKD) is a chronic renal dysfunction syndrome that is characterized by nephron loss, inflammation, myofibroblasts activation, and extracellular matrix (ECM) deposition. Lipotoxicity and oxidative stress are the driving force for the loss of nephron including tubules, glomerulus, and endothelium. NLRP3 inflammasome signaling, MAPK signaling, PI3K/Akt signaling, and RAAS signaling involves in lipotoxicity. The upregulated Nox expression and the decreased Nrf2 expression result in oxidative stress directly. The injured renal resident cells release proinflammatory cytokines and chemokines to recruit immune cells such as macrophages from bone marrow. NF-κB signaling, NLRP3 inflammasome signaling, JAK-STAT signaling, Toll-like receptor signaling, and cGAS-STING signaling are major signaling pathways that mediate inflammation in inflammatory cells including immune cells and injured renal resident cells. The inflammatory cells produce and secret a great number of profibrotic cytokines such as TGF-β1, Wnt ligands, and angiotensin II. TGF-β signaling, Wnt signaling, RAAS signaling, and Notch signaling evoke the activation of myofibroblasts and promote the generation of ECM. The potential therapies targeted to these signaling pathways are also introduced here. In this review, we update the key signaling pathways of lipotoxicity, oxidative stress, inflammation, and myofibroblasts activation in kidneys with chronic injury, and the targeted drugs based on the latest studies. Unifying these pathways and the targeted therapies will be instrumental to advance further basic and clinical investigation in CKD.

Role of Sodium-Glucose Co-Transporter 2 Inhibitors in the Regulation of Inflammatory Processes in Animal Models

Sodium-glucose co-transporter 2 inhibitors, also known as gliflozins, were developed as a novel class of anti-diabetic agents that promote glycosuria through the prevention of glucose reabsorption in the proximal tubule by sodium-glucose co-transporter 2. Beyond the regulation of glucose homeostasis, they resulted as being effective in different clinical trials in patients with heart failure, showing a strong cardio-renal protective effect in diabetic, but also in non-diabetic patients, which highlights the possible existence of other mechanisms through which gliflozins could be exerting their action. So far, different gliflozins have been approved for their therapeutic use in T2DM, heart failure, and diabetic kidney disease in different countries, all of them being diseases that have in common a deregulation of the inflammatory process associated with the pathology, which perpetuates and worsens the disease. This inflammatory deregulation has been observed in many other diseases, which led the scientific community to have a growing interest in the understanding of the biological processes that lead to or control inflammation deregulation in order to be able to identify potential therapeutic targets that could revert this situation and contribute to the amelioration of the disease. In this line, recent studies showed that gliflozins also act as an anti-inflammatory drug, and have been proposed as a useful strategy to treat other diseases linked to inflammation in addition to cardio-renal diseases, such as diabetes, obesity, atherosclerosis, or non-alcoholic fatty liver disease. In this work, we will review recent studies regarding the role of the main sodium-glucose co-transporter 2 inhibitors in the control of inflammation.

Fucoidan Alleviates Renal Fibrosis in Diabetic Kidney Disease via Inhibition of NLRP3 Inflammasome-Mediated Podocyte Pyroptosis

Background: Fucoidan (FPS) has been widely used to treat renal fibrosis (RF) in patients with diabetic kidney disease (DKD); however, the precise therapeutic mechanisms remain unclear. Recently, research focusing on inflammation-derived podocyte pyroptosis in DKD has attracted increasing attention. This phenomenon is mediated by the activation of the nucleotide-binding oligomerization domain (Nod)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, leading to RF during DKD progression. Therefore, we designed a series of experiments to investigate the ameliorative effects of FPS on RF in DKD and the mechanisms that are responsible for its effect on NLRP3 inflammasome-mediated podocyte pyroptosis in the diabetic kidney.

Methods: The modified DKD rat models were subjected to uninephrectomy, intraperitoneal injection of streptozotocin, and a high-fat diet. Following induction of renal injury, the animals received either FPS, rapamycin (RAP), or a vehicle for 4 weeks. For in vitro research, we exposed murine podocytes to high glucose and MCC950, an NLRP3 inflammasome inhibitor, with or without FPS or RAP. Changes in the parameters related to RF and inflammatory podocyte injury were analyzed in vivo. Changes in podocyte pyroptosis, NLRP3 inflammasome activation, and activation of the adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin complex 1 (mTORC1)/NLRP3 signaling axis involved in these changes were analyzed in vivo and in vitro.

Results: FPS and RAP ameliorated RF and inflammatory podocyte injury in the DKD model rats. Moreover, FPS and RAP attenuated podocyte pyroptosis, inhibited NLRP3 inflammasome activation, and regulated the AMPK/mTORC1/NLRP3 signaling axis in vivo and in vitro. Notably, our data showed that the regulative effects of FPS, both in vivo and in vitro, on the key signaling molecules, such as p-AMPK and p-raptor, in the AMPK/mTORC1/NLRP3 signaling axis were superior to those of RAP, but similar to those of metformin, an AMPK agonist, in vitro.

Conclusion: We confirmed that FPS, similar to RAP, can alleviate RF in DKD by inhibiting NLRP3 inflammasome-mediated podocyte pyroptosis via regulation of the AMPK/mTORC1/NLRP3 signaling axis in the diabetic kidney. Our findings provide an in-depth understanding of the pathogenesis of RF, which will aid in identifying precise targets that can be used for DKD treatment.

Emerging Role of LncRNA Regulation for NLRP3 Inflammasome in Diabetes Complications

Diabetes is a widespread metabolic disease with various complications, including diabetic nephropathy, retinopathy, cardiomyopathy, and other cardiovascular or cerebrovascular diseases. As the prevalence of diabetes increases in all age groups worldwide, diabetes and its complications cause an emerging public health burden. NLRP3 inflammasome is a complex of several proteins that play a critical role in inflammatory response and various diseases, including diabetes and its complications. Accumulating evidences indicate that NLRP3 inflammasome contributes to the development of diabetes and diabetic complications and that NLRP3 inflammation inactivation is beneficial in treating these illnesses. Emerging evidences suggest the critical role of long non-coding RNAs (lncRNAs) in regulating NLRP3 inflammasome activity in various diseases. LncRNAs are non-coding RNAs exceeding 200 nucleotides in length. Its dysregulation has been linked to the development of diseases, including diabetes. Recently, growing evidences hint that regulating lncRNAs on NLRP3 inflammasome is critical in developing and progressing diabetes and diabetic complications. Here, we discuss the role of lncRNAs in regulating NLRP3 inflammasome as well as its participation in diabetes and diabetic complications, providing novel insights into developing future therapeutic approaches for diabetes.

Activation of angiotensin-converting enzyme 2 ameliorates metabolic syndrome-induced renal damage in rats by renal TLR4 and nuclear transcription factor κB downregulation

BACKGROUND

Metabolic syndrome (MetS) is an independent risk factor for chronic kidney disease (CKD) through many mechanisms, including activation of the renin-angiotensin system. The deleterious effects of angiotensin II (Ang II) can be counterbalanced by angiotensin-converting enzyme 2 (ACE2). Diminazene aceturate (DIZE), an anti-trypanosomal drug, can activate ACE2.

OBJECTIVE

This study aimed to investigate the possible reno-protective effects of DIZE in MetS rats with elucidation of related mechanisms.

MATERIALS AND METHODS

Thirty adult male Wistar albino rats were divided equally into control, MetS, and MetS + DIZE groups. Body weight, systolic blood pressure (SBP), and urinary albumin levels were measured. Serum levels of fasting blood glucose (FBG), insulin, uric acid, lipid profile, urea, and creatinine were measured. Homeostasis Model Assessment Index (HOMA-IR) was estimated. Subsequently, renal levels of ACE2, Ang II, malondialdehyde (MDA), reduced glutathione (GSH), and tumor necrosis factor-α (TNF-α) were measured with histopathological and immunohistochemical assessment of TLR4 and NF-κB in renal tissues.

RESULTS

MetS caused dyslipidemia with significant increases in body weight, SBP, FBG, serum insulin, HOMA-IR, uric acid, urea, creatinine, urinary albumin, and renal levels of Ang II, MDA, and TNF-α, whereas renal ACE2 and GSH were significantly decreased. Renal TLR4 and NF-κB immunoreactivity in MetS rats was upregulated. DIZE supplementation of MetS rats induced significant improvements in renal function parameters; this could be explained by the ability of DIZE to activate renal ACE2 and decrease renal Ang II levels with downregulation of renal TLR4 and NF-κB expression.

CONCLUSION

DIZE exerts a reno-protective effect in MetS, mainly by downregulating renal TLR4 and NF-κB levels.

Erianin: A Direct NLRP3 Inhibitor With Remarkable Anti-Inflammatory Activity

Erianin (Eri) is the extract of Dendrobium chrysotoxum Lindl. The NLRP3 inflammasome is a multiprotein complex that plays key roles in a wide variety of chronic inflammation-driven human diseases. Nevertheless, little is known about the protection of Eri against NLRP3 inflammasome-related diseases. In this study, we demonstrated that Eri inhibited NLRP3 inflammasome activation in vitro and in vivo. Mechanistically, Eri directly interacted with NLRP3, leading to inhibition of NLRP3 inflammasome assembly. Eri associated with the Walker A motif in the NACHT domain and suppressed NLRP3 ATPase activity. In mouse models, Eri had therapeutic effects on peritonitis, gouty arthritis and type 2 diabetes, via NLRP3. More importantly, Eri was active ex vivo for synovial fluid cells and monocytes from patients with IAV infection and gout. Eri may serve as a potential novel therapeutic compound against NLRP3-driven diseases.