Uric acid regulates NLRP3/IL-1β signaling pathway and further induces vascular endothelial cells injury in early CKD through ROS activation and K+ efflux

Construction and validation of a risk model of proteinuria in patients with omicron COVID-19: retrospective cohort study

BACKGROUND

To explore the risk factors of proteinuria in Omicron variant patients and to construct and verify the risk predictive model.

METHODS

1091 Omicron patients who were hospitalized from August 2022 to November 2022 at Tianjin First Central Hospital were defined as the derivation cohort. 306 Omicron patients who were hospitalized from January 2022 to March 2022 at the same hospital were defined as the validation cohort. The risk factors of proteinuria in derivation cohort were screened by univariate and multivariate logistic regression analysis, and proteinuria predicting scoring system was constructed and the receiver operating characteristic(ROC)curve was drawn to test the prediction ability. The proteinuria risk model was externally validated in validation cohort.

RESULTS

7 factors including comorbidities, blood urea nitrogen (BUN), serum sodium (Na), uric acid (UA), C reactive protein (CRP) and vaccine dosages were included to construct a risk predictive model. The score ranged from -5 to 16. The area under the ROC curve(AUC) of the model was 0.8326(95% CI 0.7816 to 0.8835, p < 0.0001). Similarly to that observed in derivation cohort, the AUC is 0.833(95% CI 0.7808 to 0.9002, p < 0.0001), which verified good prediction ability and diagnostic accuracy in validation cohort.

CONCLUSIONS

The risk model of proteinuria after Omicron infection had better assessing efficiency which could provide reference for clinical prediction of the risk of proteinuria in Omicron patients.

Correlation between serum uric acid to high-density lipoprotein cholesterol ratio and atrial fibrillation in patients with NAFLD

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is independently associated with atrial fibrillation (AF) risk. The uric acid (UA) to high-density lipoprotein cholesterol (HDL-C) ratio (UHR) has been shown to be closely associated with cardiovascular disease (CVD) and NAFLD. The aim of this study is to clarify whether elevated UHR is associated with the occurrence of AF in patients with NAFLD and to determine whether UHR predicted AF.

METHODS

Patients diagnosed with NAFLD in the Department of Cardiovascular Medicine of the Second Hospital of Shanxi Medical University from January 1, 2020, to December 31, 2021, were retrospectively enrolled in this study. The study subjects were categorized into AF group and non-AF group based on the presence or absence of combined AF. Logistic regression was performed to evaluate the correlation between UHR and AF. Sensitivity analysis and subgroup interaction analysis were performed to verify the robustness of the study results. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal cutoff value for UHR to predict the development of AF in patients with NAFLD.

RESULTS

A total of 421 patients with NAFLD were included, including 171 in the AF group and 250 in the non-AF group. In the univariate regression analysis, NAFLD patients with higher UHR were more likely to experience AF, and the risk of AF persisted after confounding factors were adjusted for (OR: 1.010, 95%CI: 1.007-1.013, P<0.001). AF risk increased with increasing UHR quartile (P for trend < 0.001). Despite normal serum UA and HDL-C, UHR was still connected with AF in patients with NAFLD. All subgroup variables did not interact significantly with UHR in the subgroup analysis. The ROC curve analysis showed that the areas under the curve for UA, HDL-C, and UHR were 0.702, 0.606, and 0.720, respectively, suggesting that UHR has a higher predictive value for AF occurrence in NAFLD patients compared to HDL-C or UA alone.

CONCLUSION

Increased UHR level was independently correlated with a high risk of AF in NAFLD patients.

Recent Advances in Dysuricemia: Toward Optimal Serum Urate Level

We are pleased to present the Special Issue "Dysuricemia: Recent Advances in Urate Research from Hypouricemia to Hyperuricemia/Gout" [...].

Catalpol ameliorates fructose-induced renal inflammation by inhibiting TLR4/MyD88 signaling and uric acid reabsorption

Accumulating evidence suggests that excess fructose uptake induces metabolic syndrome and kidney injury. Here, we primarily investigated the influence of catalpol on fructose-induced renal inflammation in mice and explored its potential mechanism. Treatment with catalpol improved insulin sensitivity and hyperuricemia in fructose-fed mice. Hyperuricemia induced by high-fructose diet was associated with increases in the expressions of urate reabsorptive transporter URAT1 and GLUT9. Treatment with catalpol decreased the expressions of URAT1 and GLUT9. Futhermore, treatment with catalpol ameliorated renal inflammatory cell infiltration and podocyte injury, and these beneficial effects were associated with inhibiting the production of inflammatory cytokines including IL-1β, IL-18, IL-6 and TNF-α. Moreover, fructose-induced uric acid triggers an inflammatory response by activiting NLRP3 inflammasome, which then processes pro-inflammatory cytokines. Treatment with catalpol could inhibit the activation of NLRP3 inflammasome as well. Additionally, TLR4/MyD88 signaling was activated in fructose-fed mice, while treatment with catalpol inhibited this activation along with promoting NF-κB nuclear translocation in fructose-fed mice. Thus, our study demonstrated that catalpol could ameliorate renal inflammation in fructose-fed mice, attributing its beneficial effects to promoting uric acid excretion and inhibit the activation of TLR4/MyD88 signaling.

Models of gouty nephropathy: exploring disease mechanisms and identifying potential therapeutic targets

Gouty nephropathy (GN) is a metabolic disease with persistently elevated blood uric acid levels. The main manifestations of GN are crystalline kidney stones, chronic interstitial nephritis, and renal fibrosis. Understanding the mechanism of the occurrence and development of GN is crucial to the development of new drugs for prevention and treatment of GN. Currently, most studies exploring the pathogenesis of GN are primarily based on animal and cell models. Numerous studies have shown that inflammation, oxidative stress, and programmed cell death mediated by uric acid and sodium urate are involved in the pathogenesis of GN. In this article, we first review the mechanisms underlying the abnormal intrinsic immune activation and programmed cell death in GN and then describe the characteristics and methods used to develop animal and cell models of GN caused by elevated uric acid and deposited sodium urate crystals. Finally, we propose potential animal models for GN caused by abnormally high uric acid levels, thereby provide a reference for further investigating the methods and mechanisms of GN and developing better prevention and treatment strategies.

Targeting toll-like receptor 4 (TLR4) and the NLRP3 inflammasome: Novel and emerging therapeutic targets for hyperuricaemia nephropathy

The clinical manifestation of hyperuricaemia, known as hyperuricaemia nephropathy, is relatively common. Its pathophysiology is largely based on chronic inflammation in circulatory and renal tissues. Toll-like receptor 4 (TLR4), a subclass of innate immune receptors, detects both pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), initiating inflammatory and immune responses that lead to the release of pro-inflammatory cytokines interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α). These cytokines are pivotal in renal inflammation, especially in conditions like hyperuricaemia, acute renal injury, ischemia-reperfusion injury, and acute renal failure. The nucleotide-binding oligomerization domain (NOD)-like receptor pyrin domain-containing 3 (NLRP3) inflammasome, an essential component of the innate immune signaling complex, plays a central role in inflammation. It finely regulates the activation of caspase-1 and the production and secretion of the pro-inflammatory cytokine IL-1β, mediating and amplifying the inflammatory cascade response. Activation of TLR4 indirectly promotes the assembly of the NLRP3 inflammasome by regulating the nuclear factor kappa B (NF-κB) signaling pathway, thereby amplifying the inflammatory process and playing a significant pro-inflammatory role in hyperuricaemia nephropathy. TLR4 and NLRP3 inflammasome are anticipated to be novel markers and therapeutic targets for assessing treatment efficacy and prognosis in hyperuricaemia nephropathy. This paper provides a comprehensive overview of the structural composition and biological functions of TLR4 and NLRP3 inflammasome and systematically reviews their relevance in the pathogenesis of hyperuricaemia nephropathy.

Nrf2/HO-1 as a therapeutic target in renal fibrosis

Chronic kidney disease (CKD) is one of the most prevalent chronic diseases and affects between 10 and 14 % of the world's population. The World Health Organization estimates that by 2040, the disease will be fifth in prevalence. End-stage CKD is characterized by renal fibrosis, which can eventually lead to kidney failure and death. Renal fibrosis develops due to multiple injuries and involves oxidative stress and inflammation. In the human body, nuclear factor erythroid 2-related factor 2 (Nrf2) plays an important role in the expression of antioxidant, anti-inflammatory, and cytoprotective genes, which prevents oxidative stress and inflammation damage. Heme oxygenase (HO-1) is an inducible homolog influenced by heme products and after exposure to cellular stress inducers such as oxidants, inflammatory chemokines/cytokines, and tissue damage as an outcome or downstream of Nrf2 activation. HO-1 is known for its antioxidative properties, which play an important role in regulating oxidative stress. In renal diseases-induced tissue fibrosis and xenobiotics-induced renal fibrosis, Nrf2/HO-1 has been targeted with promising results. This review summarizes these studies and highlights the interesting bioactive compounds that may assist in attenuating renal fibrosis mediated by HO-1 activation. In conclusion, Nrf2/HO-1 signal activation could have a renoprotective effect strategy against CKD caused by oxidative stress, inflammation, and consequent renal fibrosis.

Leukocyte-endothelial interaction in CKD

Chronic kidney disease (CKD) represents an independent risk factor for cardiovascular diseases (CVD). Accordingly, CKD patients show a substantial increased risk of cardiovascular mortality. Inflammation represents an important link between CKD and CVD. The interaction between endothelial cells and effector cells of the innate immune system plays a central role in the development and progression of inflammation. Vascular injury causes endothelial dysfunction, leading to augmented oxidative stress, increased expression of leukocyte adhesion molecules and chronic inflammation. CKD induces numerous metabolic changes, creating a uremic milieu resulting in the accumulation of various uremic toxins. These toxins lead to vascular injury, endothelial dysfunction and activation of the innate immune system. Recent studies describe CKD-dependent changes in monocytes that promote endothelial dysfunction and thus CKD progression and CKD-associated CVD. The NLR family pyrin domain containing 3-interleukin-1β-interleukin-6 (NLRP3-IL-1β-IL-6) signaling pathway plays a pivotal role in the development and progression of CVD and CKD alike. Several clinical trials are investigating targeted inhibition of this pathway indicating that anti-inflammatory therapeutic strategies may emerge as novel approaches in patients at high cardiovascular risk and nonresolving inflammation. CKD patients in particular would benefit from targeted anti-inflammatory therapy, since conventional therapeutic regimens have limited efficacy in this population.

Eurycoma longifolia alkaloid components ameliorate hyperuricemic nephropathy via regulating serum uric acid level and relieving inflammatory reaction

Hyperuricemia is an independent risk factor for chronic kidney disease. We have previously showed the uric-acid-lowering effect of Eurycoma longifolia Jack, yet the renal protective effect and mechanism of E. longifolia remain obscure. The mouse model of hyperuricemic nephropathy was induced by adenine combined with potassium oxonate in male C57BL/6 J mice. E. Longifolia alkaloid components could reduce the level of serum uric acid by regulating the expression of hepatic phosphoribosyl pyrophosphate synthase (PRPS), hypoxanthine-guanine phosphoribosyl transferase (HPRT), and renal urate transporter organic anion transporter 1 (OAT1) and ATP-binding box subfamily G member 2 (ABCG2) in HN mice. Additionally, E. Longifolia alkaloid components alleviated renal injury and function caused by hyperuricemia, which was characterized by improving renal histopathology, reducing urea nitrogen and creatinine levels. E. Longifolia alkaloid components treatment could reduce the secretion of pro-inflammatory factors by inhibiting the activation of NF-κB and NLRP3 inflammatory signaling pathways, including tumor necrosis factor α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), interleukin-1 β (IL-1β), and regulated activated normal T cell expression and secretion proteins (RANTES). Meanwhile, E. longifolia alkaloid components improved renal fibrosis, inhibited the transformation of calcium-dependent cell adhesion molecule E (E-cadherin) to α-smooth muscle actin (α-SMA) transformation, and decreased collagen 1 expression in HN mice.

Role of pyroptosis in the pathogenesis and treatment of diseases

Programmed cell death (PCD) is regarded as a pathological form of cell death with an intracellular program mediated, which plays a pivotal role in maintaining homeostasis and embryonic development. Pyroptosis is a new paradigm of PCD, which has received increasing attention due to its close association with immunity and disease. Pyroptosis is a form of inflammatory cell death mediated by gasdermin that promotes the release of proinflammatory cytokines and contents induced by inflammasome activation. Recently, increasing evidence in studies shows that pyroptosis has a crucial role in inflammatory conditions like cardiovascular diseases (CVDs), cancer, neurological diseases (NDs), and metabolic diseases (MDs), suggesting that targeting cell death is a potential intervention for the treatment of these inflammatory diseases. Based on this, the review aims to identify the molecular mechanisms and signaling pathways related to pyroptosis activation and summarizes the current insights into the complicated relationship between pyroptosis and multiple human inflammatory diseases (CVDs, cancer, NDs, and MDs). We also discuss a promising novel strategy and method for treating these inflammatory diseases by targeting pyroptosis and focus on the pyroptosis pathway application in clinics.

Protective effect of dihydromyricetin on vascular smooth muscle cell apoptosis induced by hydrogen peroxide in rats

OBJECTIVE

Dihydromyricetin (DMY), also called Ampelopsin, which was extracted from Ampelopsis grossedentata, has been demonstrated to have a protective effect against cell oxidative injury and cell apoptosis in vitro. In the present study, we tried to study the role of DMY on apoptosis of vascular smooth muscle cells (VSMCs) induced by hydrogen peroxide (H₂O₂) and explore the underlying mechanisms.

METHODS

Apoptotic cells were detected by Hematoxylin and Eosin (H.E.) staining, Hoechst 33342 staining, and Annexin V-fluorescein isothiocyanate binding assay. The intracellular reactive oxygen species (ROS) level was estimated through fluorescence assay. The mRNA and protein expression of Caspase-3, Caspase-9, Bcl-2, and Bax were determined by reverse transcription-polymerase chain reaction (RT-PCR) and western blot.

RESULTS

The results showed that the pretreatment of VSMCs with DMY not only significantly increased cell viability, reduced intracellular ROS release, alleviated the morphological changes of apoptosis, and decreased the apoptosis rate, but also upregulated Bcl-2 expression and downregulated Caspase-3, Caspase-9, Bax expression, and ultimately attenuated the H₂O₂-stimulated apoptosis.

CONCLUSION

The inhibition of DMY on VSMC apoptosis may be mediated by ROS scavenging and the activation of the mitochondrial apoptotic signaling pathway.

Inflammation Related to Association of Low Uric Acid and Progression to Severe Disease in Patients Hospitalized for Non-Severe Coronavirus Disease 2019

Uric acid has antioxidant properties. To examine whether a low uric acid level is associated with severe coronavirus disease 2019 (COVID-19) progression via inflammation, alveolar damage, and/or coagulation abnormality, a retrospective observational study of 488 patients with non-severe COVID-19 and serum uric acid level ≤7 mg/dL at admission was conducted. Serum C-reactive protein (CRP), serum Krebs von den Lungen 6 (KL-6), and plasma D-dimer levels were also measured as markers of inflammation, alveolar damage, and coagulation abnormality, respectively. Median values for uric acid, CRP, KL-6, and D-dimer at admission were 4.4 mg/dL, 3.33 mg/dL, 252.0 U/mL, and 0.8 µg/mL, respectively. Among the total cohort, 95 (19.5%) progressed to severe COVID-19 with a median (interquartile range) time of 7 (4–14) days. Multivariable Cox proportional hazards regression analysis showed that low uric acid level was associated with a higher rate of severe COVID-19 progression. However, uric acid level was inversely associated with CRP level, and the association between the level of uric acid and severe COVID-19 progression was significantly different with and without CRP level inclusion. In contrast, no such association was found for KL-6 or D-dimer level. Low uric acid may contribute to severe COVID-19 progression via increased inflammation in subjects without hyperuricemia.

The Nephroprotective Effects of Hibiscus sabdariffa Leaf and Ellagic Acid in Vitro and in Vivo Models of Hyperuricemic Nephropathy

Hyperuricemic nephropathy (HN) is caused by urate crystals that get deposited in the kidney and contribute to renal fibrosis. Uric acid (UA) has been proven to directly cause renal mesangial cell oxidative stress and fibrosis in the pathogenesis of HN. Some antioxidants can be used as chemopreventive agents of HN. Hibiscus sabdariffa leaf extracts (HLE), rich in polyphenol, have been shown to possess hypoglycemic, antioxidant, hypolipidemic, antiatherosclerotic, and anticancer effects. The aim of the study is to examine the inhibitory effect of HLE and its main component ellagic acid (EA) on renal fibrosis. In vitro, mouse renal glomerular mesangial SV40MES13 cells pretreated with UA were demonstrated to trigger obvious morphological changes and viability loss, as well as affect matrix metalloproteinases (MMPs) activities. Noncytotoxic doses of HLE and EA abolished the UA-induced cell injury and MMP-2/9 secretion. In addition, HLE and EA exhibited antioxidant and anti-inflammatory effects on the UA-treated cells with a reduction in transforming growth factor-beta (TGF-β) production. Next, the UA-activated pro-fibrotic factors, extracellular matrix (ECM) deposition, and epithelial-mesenchymal-transition (EMT) were inhibited by HLE or EA. Mechanistic assays indicated that antifibrotic effects of HLE might be mediated via TGF-β/Smad signaling, as confirmed by the transfection of Smad7 siRNA. In vivo, HLE and EA supplementations significantly alleviated HN development, which may result from inhibiting adenine-induced TGF-β production accompanying oxidative stress and inflammation, as well as fibrogenesis. Our data imply that EA-enriched HLE regulates the TGF-β/Smad signaling, which in turn led to reduced renal mesangial cell injury and fibrosis in HN and provided a new mechanism for its nephroprotective activity.

Uric acid promotes myocardial infarction injury via activating pyrin domain-containing 3 inflammasome and reactive oxygen species/transient receptor potential melastatin 2/Ca2+pathway

Cardiomyocytes injury has been considered as a key contributor for myocardial infarction (MI). Uric acid (UA) can induce cardiomyocytes injury, which is closely related to NLRP3 activation and inflammatory factor generation. However, the mechanism how UA modulates cardiomyocytes remains elusive. Western blotting and qRT-PCR were applied for measuring protein and mRNA expression, respectively. ROS production and Ca²⁺ influx were measured by flow cytometry. Patch clamp technique was used for measuring transient receptor potential melastatin 2 (TRPM2) channel. Ligation of left anterior descending for 2 h was performed to induce MI animal model. The rats were treated by different concentration of uric acid. The artery tissues were stained by HE and collected for measurement of NLRP3 and inflammatory factors. Supplementation of UA significantly promoted apoptosis, and augmented the expression of intercellular adhesion molecule-1, chemoattractant protein-1, vascular cell adhesion molecule-1, and NLRP3 inflammasome. Knockdown of NLRP3 reversed the influence of UA on MI by decreasing collagen deposition, fibrotic area, apoptosis. The expression of NLRP3 inflammasome increased markedly after treatment of UA. UA activated ROS/TRPM2/Ca²⁺ pathway through targeting NLRP3. UA activated NLRP3 inflammasome and augments inflammatory factor production, which in turn exacerbates cardiomyocytes injury. Knockdown of NLRP3 reversed the influence of UA on apoptosis and cell cycle. UA may promote cardiomyocytes injury through activating NLRP3 inflammasome and ROS/TRPM2 channel/Ca²⁺ pathway.

Clinical and biochemical indices of people with high-altitude experience linked to acute mountain sickness

BACKGROUND

Acute mountain sickness (AMS) is a major health issue for people travelling to high altitudes. This study was designed to comprehensively evaluate the changes in clinical characteristics and biochemical indices of high-altitude travelers and determine whether these changes were associated with AMS.

METHODS

A total of 14 clinical indices and 52 biochemical indices were determined in 22 subjects before and during acute high-altitude exposure. Six hours after passive ascent to 3648 m (Lhasa, China), the Lake Louise Scoring (LLS) system 2018 was used to assess AMS, which was defined as headache with a total LLS ≥3.

RESULTS

Before travelling to high altitudes, uric acid (UA), platelet distribution width (PDW), mitral peak E velocity (MVE), and ejection fraction (EF) were significantly higher in AMS-resistant individuals than in AMS-susceptible ones (all p < 0.05). A good predictive value of UA (0.817, 95% CI: 0.607-1.000) and PDW (0.844, 95% CI: 0.646-1.000) for AMS-susceptible subjects was found. With high-altitude experience, 14 subjects were diagnosed as having AMS. Compared with non-AMS, the changes in UA and number of neutrophils in AMS presented a significant difference (all p < 0.05). The high-altitude-induced changes in UA, area under the curve, specificity, and sensitivity for identifying AMS were 0.883 (95% CI: 0.738-1.000), 83.30%, and 90.00%, respectively.

CONCLUSION

Human presents a compensatory physiological and biochemical response to high-altitude travel at early phase. The UA concentration before travel and its trend with high-altitude experience exhibited good performance for identifying AMS.

The relationship between leukocyte level and hypertension in elderly patients with hyperuricemia

To evaluate the change of leukocyte level caused by hyperuricemia, and to explore the relationship between leukocyte level and hypertension in elderly patients with hyperuricemia. A cross-sectional study of serum uric acid (UA) level was conducted in 1352 elderly people over 65 years old. The samples were divided into 3 categories according to the tertiles of leukocyte: Tertile 1, leukocyte ≤ 5.2 × 109/L; Tertile 2, leukocyte = 5.3-6.3 × 109/L; Tertile 3, leukocyte ≥ 6.4 × 109/L. Multiple logistic regression models were used for modeling relationships between leukocyte, hyperuricemia and hypertension. Human vascular endothelial cells were treated by different concentrations of UA. The levels of interleukin-1 beta, tumor necrosis factor-α, endothelial nitric oxide synthase, inducible nitric oxide synthase and reactive oxygen species were measured by Western Blot or fluorescence microscope. The levels of leukocyte were higher in elderly patients with hyperuricemia than without hyperuricemia. Hyperuricemia was an independent risk factor of leukocyte in Tertile 3 (odds ratio [OR] = 1.657, 95% confidence interval [CI]: 1.180-2.328). The prevalences of hypertension were higher in elderly patients with hyperuricemia than without hyperuricemia (77.0% vs 63.5%). In the Model 1, hyperuricemia was an independent risk factor of hypertension (OR = 1.536, 95% CI: 1.026-2.302). Leukocyte in Tertile 3 was an independent risk factor of hypertension (OR = 1.333, 95% CI: 1.031-1.724). Expression levels of interleukin-1 beta, inducible nitric oxide synthase and tumor necrosis factor-α were obviously higher in the UA group than the control group, along with the productions of reactive oxygen species. But the expression level of endothelial nitric oxide synthase was obviously lower in the UA group. Hyperuricemia was associated with an increased risk for hypertension. The chronic inflammation caused by hyperuricemia maybe one of important pathogenesis of incident hypertension in patients with hyperuricemia.

Endothelial Acid Sphingomyelinase Promotes NLRP3 Inflammasome and Neointima Formation During Hypercholesterolemia

The NOD-like receptor pyrin domain 3 (NLRP3) inflammasome is activated during atherogenesis, but how this occurs is unclear. Here, we explored the mechanisms activating and regulating NLRP3 inflammasomes via the acid sphingomyelinase (ASM)-ceramide signaling pathway. As a neointima formation model, partial left carotid ligations were performed on endothelial cell (EC)-specific ASM transgene mice (Smpd1trg/ECcre) and their control littermates (Smpd1trg/WT and WT/WT) fed on the Western diet (WD). We found neointima formation remarkably increased in Smpd1trg/ECcre mice over their control littermates. Next, we observed enhanced colocalization of NLRP3 versus adaptor protein ASC (the adaptor molecule apoptosis-associated speck-like protein containing a CARD) or caspase-1 in the carotid ECs of WD-treated Smpd1trg/ECcre mice but not in their control littermates. In addition, we used membrane raft (MR) marker flotillin-1 and found more aggregation of ASM and ceramide in the intima of Smpd1trg/ECcre mice than their control littermates. Moreover, we demonstrated by in situ dihydroethidium staining, carotid intimal superoxide levels were much higher in WD-treated Smpd1trg/ECcre mice than in their control littermates. Using ECs from Smpd1trg/ECcre and WT/WT mice, we showed ASM overexpression markedly enhanced 7-ketocholesterol (7-Ket)-induced increases in NLRP3 inflammasome formation, accompanied by enhanced caspase-1 activity and elevated interleukin-1β levels. These 7-Ket-induced increases were significantly attenuated by ASM inhibitor amitriptyline. Furthermore, we determined that increased MR clustering with NADPH oxidase subunits to produce superoxide contributes to 7-Ket-induced NLRP3 inflammasome activation via a thioredoxin-interacting protein-mediated controlling mechanism. We conclude that ceramide from ASM plays a critical role in NLRP3 inflammasome activation during hypercholesterolemia via MR redox signaling platforms to produce superoxide, which leads to TXNIP dissociation.

The role of Nod-like receptor protein 3 inflammasome activated by ion channels in multiple diseases

The inflammasome is a multimeric protein complex located in the cytoplasm that is activated by many factors and subsequently promotes the release of proinflammatory factors such as interleukin (IL)-1β and IL-18, resulting in a series of inflammatory responses that ultimately lead to the occurrence of various diseases. The Nod-like receptor protein 3 (NLRP3) inflammasome is the most characteristic type and the most widely studied among many inflammasomes. Activation of the NLRP3 inflammasome is closely related to the occurrence of many diseases, such as Alzheimer's disease. At present, a large number of studies have focused on the mechanisms underlying the activation of the NLRP3 inflammasome. Plenty of articles have reported the activation of the NLRP3 inflammasome by various ions, such as K+ and Na+ reflux and Ca2+ influx. However, few articles have reviewed the effects of various ion channels on the activation of the NLRP3 inflammasome and the relationship between the diseases caused by these proteins. This article mainly summarizes the relationship between intracellular and extracellular ion activities and ion channels and the activation of the NLRP3 inflammasome. We also provide a general summary of the diseases of each system caused by NLRP3 activation. We hope that more research will provide options for the treatment of diseases driven by the NLRP3 inflammasome.

Uric acid effects on glutathione metabolism estimated by induction of glutamate-cysteine ligase, glutathione reductase and glutathione synthetase in mouse J744A.1 macrophage cell line

INTRODUCTION

Elevated plasma levels of uric acid (UA) are considered an independent risk factor for hypertension, diabetes, cardiovascular disease, endothelial and vascular damage, obesity, and metabolic syndrome. Even physiological concentrations of soluble UA have been proved to induce gene expression of macrophage-secreted inflammatory cytokines and stimulate production of reactive oxygen species in mature adipocytes. UA is also described as a powerful endogenous plasma antioxidant, which reveals a paradox of duality for this parameter.

Negative Effects of Chronic High Intake of Fructose on Lung Diseases

In the modern diet, excessive fructose intake (>50 g/day) had been driven by the increase, in recent decades, of the consumption of sugar-sweetened beverages. This phenomenon has dramatically increased within the Caribbean and Latin American regions. Epidemiological studies show that chronic high intake of fructose related to sugar-sweetened beverages increases the risk of developing several non-communicable diseases, such as chronic obstructive pulmonary disease and asthma, and may also contribute to the exacerbation of lung diseases, such as COVID-19. Evidence supports several mechanisms—such as dysregulation of the renin−angiotensin system, increased uric acid production, induction of aldose reductase activity, production of advanced glycation end-products, and activation of the mTORC1 pathway—that can be implicated in lung damage. This review addresses how these pathophysiologic and molecular mechanisms may explain the lung damage resulting from high intake of fructose.

Cardiovascular protection by SGLT2 inhibitors - Do anti-inflammatory mechanisms play a role?

BACKGROUND

Metabolic syndrome and related metabolic disturbances represent a state of low-grade inflammation, which accelerates insulin resistance, type 2 diabetes (T2D) and cardiovascular disease (CVD) progression. Among antidiabetic medications, sodium glucose co-transporter (SGLT) 2 inhibitors are the only agents which showed remarkable reductions in heart failure (HF) hospitalizations and major cardiovascular endpoints (MACE) as well as renal endpoints regardless of diabetes status in large randomized clinical outcome trials (RCTs). Although the exact mechanisms underlying these benefits are yet to be established, growing evidence suggests that modulating inflammation by SGLT2 inhibitors may play a key role.

SCOPE OF REVIEW

In this manuscript, we summarize the current knowledge on anti-inflammatory effects of SGLT2 inhibitors as one of the mechanisms potentially mediating their cardiovascular (CV) benefits. We introduce the different metabolic and systemic actions mediated by these agents which could mitigate inflammation, and further present the signalling pathways potentially responsible for their proposed direct anti-inflammatory effects. We also discuss controversies surrounding some of these mechanisms.

MAJOR CONCLUSIONS

SGLT2 inhibitors are promising anti-inflammatory agents by acting either indirectly via improving metabolism and reducing stress conditions or via direct modulation of inflammatory signalling pathways. These effects were achieved, to a great extent, in a glucose-independent manner which established their clinical use in HF patients with and without diabetes.

Matrix metalloproteinase-7 promotes chronic kidney disease progression via the induction of inflammasomes and the suppression of autophagy

Deposition of extracellular matrix (ECM), epithelial-mesenchymal transition (EMT) and inflammation are crucial processes in chronic kidney disease (CKD) progression. The matrix metalloproteinases (MMPs) belong to a major enzyme group of proteinases that are involved in ECM degradation. MMP controls multiple biological processes, such as cell proliferation, EMT and apoptosis. The present study identified the roles of MMP7 in CKD progression. We demonstrated the transcriptional profiles of MMPs in kidney tissues of CKD patients in the Gene Expression Omnibus (GEO) data repository. MMP7 mRNA level was markedly upregulated in kidney tissues of CKD patients. MMP7 overexpression activated the NLRP3 and NLRP6 inflammasomes and increased fibrosis-related proteins in kidney cells. MMP7 inhibited oxidative stress-induced apoptosis and rapamycin-induced autophagy. We found that MMP7 expression in the kidney was increased in various CKD animal models. Knockdown of MMP7 affected renal function and renal fibrosis in a folic acid-induced CKD model. The inhibition of MMP7 decreased fibrosis and NLRP3 and NLRP6 inflammasomes and induced autophagy in kidney tissues. Taken together, these results provide insight into targeting MMP7 as a therapeutic strategy for CKD.

Effects of High Flux Hemodialysis Combined with L-Carnitine on Microinflammation and Arteriovenous Fistula in Maintenance Hemodialysis Patients

Objective

To explore the effects of high-flux hemodialysis combined with L-carnitine on microinflammation and arteriovenous fistulas in maintenance hemodialysis patients.

Methods

A total of 65 patients admitted to our hospital from May 2017 to May 2019 were selected and divided into a control group of 30 cases and an experimental group of 35 cases according to the selected treatment plan. Combined with L-carnitine, the cardiac function of the two groups of patients before and after the treatment was evaluated, the microinflammatory indexes of the two groups were compared, and the clinical efficacy of the combined treatment on MHD patients was analyzed.

Results

The two groups were not significantly different in general information such as age, gender, course of disease, and past medical history (P > 0.05). The experimental group generated a notably higher total effective rate of treatment in relation to the control group (P < 0.05). After treatment, lower heart function levels of LVST and LEVDD were observed in the experimental group as compared to the control group, but LVEF was higher than that in the control group (P < 0.05). The GQOLI-74 score of the experimental group was better than that of the control group (P < 0.05). The incidence of venous fistula complications in the experimental group was significantly lower than that in the control group (P < 0.05). The microinflammatory index hs-CRP in the experimental group was lower (P < 0.05) and the microinflammatory index TNF-α was significantly lower (P < 0.05). The HAD score after treatment of the experimental group was better than that of the control group (P < 0.05).

Conclusion

High-flux hemodialysis combined with L-carnitine therapy has achieved satisfactory results in patients with MHD in terms of alleviating the level of inflammatory factors, improving heart function, enhancing patients' living standards, reducing complications of intravenous fistula, and boosting the prognosis. It is worthy of promotion.

Research progress on related mechanisms of uric acid activating NLRP3 inflammasome in chronic kidney disease

Hyperuricemia is an independent risk factor for the progression of chronic kidney disease. High levels of uric acid can lead to a series of pathological conditions, such as gout, urinary stones, inflammation, and uric acid nephropathy. There is a close relationship between uric acid and the NLRP3 inflammasome. NLRP3 inflammasome activation can cause cell damage and even death through endoplasmic reticulum stress, lysosome destruction, mitochondrial dysfunction, and the interaction between the Golgi apparatus and extracellular vesicles. In addition, the NLRP3 inflammasome acts as a molecular platform, triggering the activation of caspase-1 and the lysis of IL-1β, IL-18 and Gasdermin D (GSDMD) through different molecular mechanisms. Cleaved NT-GSDMD forms pores in the cell membrane and triggers pyrophosphorylation, thereby inducing cell death and releasing many intracellular proinflammatory molecules. In recent years, studies have found that hyperuricemia or uric acid crystals can activate NLRP3 inflammasomes, and the activation of NLRP3 inflammasomes plays an important role in kidney disease. This article reviews the possible pathophysiological mechanisms by which uric acid activates inflammasomes and induces kidney damage at the cellular and molecular levels.

Increased risk of modality failure with higher serum uric acid level in continuous ambulatory peritoneal dialysis patients: a prospective cohort study

BACKGROUND

Peritoneal dialysis (PD) is one of the most important kidney replacement therapies for patients with end-stage kidney disease (ESKD). PD technique failure can lead to an escalated cost and increased infectious and cardiovascular risk, up and including to death. The accumulation of uric acid (UA) was associated with adverse outcomes in ESKD patients. However, the relationship between serum UA and technique failure is little explored.

METHODS

Here, a total of 266 continuous ambulatory peritoneal dialysis (CAPD) patients (age, 41.8 ± 12.6 years; 125 males) were enrolled and followed up for 31.7 months. Serum UA levels were examined at baseline and each visit. Subjects were divided into three groups according to their baseline serum UA concentrations. Multivariable Cox regression models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of PD technique failure.

RESULTS

The level of serum UA increased gradually as time prolonged. During the follow-up period, 77 (28.9%) patients occurred PD technique failure, of which 56 (21.1%) transferred to hemodialysis (HD) and 21 (7.9%) died. Compared to the lowest UA tertile, after adjusting for potential confounders, HRs of technique failure in tertile 2 and tertile 3 were 1.82 (95% CI: 0.95-3.49) and 2.03 (95% CI: 1.05-3.92), respectively, and p for trend was 0.043. Adjusted HRs of all-cause technique failure, transferring to HD and mortality with each 1 mg/dL increase in serum UA were 1.20 (95% CI: 1.03-1.40, p = 0.019), 1.22 (95% CI: 1.01-1.48, p = 0.039), and 1.25 (95% CI: 0.94-1.67, p = 0.128), respectively.

CONCLUSION

Higher serum UA level predicted higher risk of technique failure in CAPD patients.

Increased Lung Uric Acid Deteriorates Pulmonary Arterial Hypertension

Background

Recent studies have demonstrated that uric acid (UA) enhances arginase activity, resulting in decreased NO in endothelial cells. However, the role of lung UA in pulmonary arterial hypertension (PAH) remains uncertain. We hypothesized that increased lung UA level contributes to the progression of PAH.

Methods and Results

In cultured human pulmonary arterial endothelial cells, voltage‐driven urate transporter 1 (URATv1) gene expression was detected, and treatment with UA increased arginase activity. In perfused lung preparations of VEGF receptor blocker (SU5416)/hypoxia/normoxia‐induced PAH model rats, addition of UA induced a greater pressure response than that seen in the control and decreased lung cGMP level. UA‐induced pressor responses were abolished by benzbromarone, a UA transporter inhibitor, or L‐norvaline, an arginase inhibitor. In PAH model rats, induction of hyperuricemia by administering 2% oxonic acid significantly increased lung UA level and induced greater elevation of right ventricular systolic pressure with exacerbation of occlusive neointimal lesions in small pulmonary arteries, compared with nonhyperuricemic PAH rats. Administration of benzbromarone to hyperuricemic PAH rats significantly reduced lung UA levels without changing XOR (xanthine oxidoreductase) activity, and attenuated right ventricular systolic pressure increase and occlusive lesion development. Topiroxostat, a XOR inhibitor, significantly reduced lung XOR activity in PAH rats, with no effects on increase in right ventricular systolic pressure, arterial elastance, and occlusive lesions. XOR‐knockout had no effects on right ventricular systolic pressure increase and arteriolar muscularization in hypoxia‐exposed mice.

Conclusions

Increased lung UA per se deteriorated PAH, whereas XOR had little impact. The mechanism of increased lung UA may be a novel therapeutic target for PAH complicated with hyperuricemia.

The NLRP3 inhibitor dapansutrile attenuates folic acid induced nephrotoxicity via inhibiting inflammasome/caspase-1/IL axis and regulating autophagy/proliferation

AIMS

Chemical renal toxicity is common and has limited therapeutic interventions. The NLRP3 inhibitor dapansutrile (DAPA) undergoes clinical phase II trials and it shows promising beneficial effects in various inflammatory diseases. The current study aims at evaluating the effect of DAPA on folic acid (FA) induced acute kidney injury (AKI) and its possible transition to chronic injury.

MATERIALS AND METHODS

Two treatment protocols were studied depending on DAPA injection timing. A prophylactic protocol involving the injection of DAPA (0.2 mg/kg) daily for seven days before FA challenge and a therapeutic protocol where DAPA was injected after FA. Each protocol included four groups of rats: control group, DAPA group, FA group and DAPA+FA group. Serum creatinine, urea and uric acid were measured. Also, kidney injury, necrosis and fibrosis percentage in addition to infiltration of CD68 positive cells were evaluated. Activation markers of inflammasome and the expression of Ki-67 and LC-3 were measured.

KEY FINDINGS

Results showed an improvement in renal tissue integrity and a significant decrease in kidney function biomarkers, caspase-1, IL-1β and IL-18 by DAPA injection (p < 0.05). In addition, DAPA decreased the proliferation marker Ki-67 and the autophagic marker LC-3 (p < 0.01).

SIGNIFICANCE

DAPA potentially alleviates FA induced nephrotoxicity through targeting inflammasome/caspase-1/IL axis. Moreover, it shows a regulatory effect on renal regeneration and autophagy.

Sesamol supplementation alleviates nonalcoholic steatohepatitis and atherosclerosis in high-fat, high carbohydrate and high-cholesterol diet-fed rats

Sesamol, a major ingredient in sesame seeds (Sesamum indicum L.) and its oil, is considered a powerful functional food ingredient. However, few studies have investigated its effects on high-fat, high carbohydrate and high-cholesterol (HF-HCC) diet-induced nonalcoholic steatohepatitis (NASH) complicated with atherosclerosis. The present study elucidates the protective effects of sesamol against NASH and atherosclerosis in HF-HCC diet-fed rats. Sprague-Dawley rats were supplemented with or without sesamol in drinking water (0.05 mg mL^-1, 0.1 mg mL^-1 and 0.2 mg mL^-1) from the beginning to end. At the end of the experiment, sesamol supplementation suppressed HF-HCC diet-induced body weight gain and increased absolute liver and adipose tissue weights in rats. Serum biochemical analyses showed that sesamol supplementation improved HF-HCC diet-induced metabolism disorders and damaged vascular endothelial function. Histological examinations displayed that dietary sesamol not only alleviated hepatic balloon degeneration, steatosis, inflammation and fibrosis, but also mitigated lipid accumulation and fibrous elements in the aorta arch in HF-HCC diet-fed rats. In addition, sesamol supplementation inhibited hepatic NOD-like receptor protein 3 (NLRP3) expression and ERS-IRE1 signaling pathway activation. Moreover, sesamol treatment decreased uric acid levels both in serum and the liver by its effect on the inhibition of xanthine oxidase (XO) activity and/or its expression, which might be closely associated with the inhibitions of NLRP3 expression and ERS-IRE1 signaling pathway activation in HF-HCC diet-fed rats. These findings demonstrated that sesamol alleviated NASH and atherosclerosis in HF-HCC diet-fed rats, and may be a potent dietary supplement for protection against these diseases.

Reactive oxygen species induced by uric acid promote NRK‑52E cell apoptosis through the NEK7‑NLRP3 signaling pathway

Increasing uric acid (UA) could induce renal tubular epithelial cell (NRK-52E) injury. However, the specific mechanism by which UA induces renal tubular epithelial cell injury remains unknown. It was hypothesized that UA induces renal tubular epithelial cell injury through reactive oxygen species (ROS) and the Never in mitosis gene A (NIMA)-related kinase 7 (NEK7)/NLR family pyrin domain containing 3 (NLRP3) signaling pathway. TUNEL assay and flow cytometry were applied to measure apoptosis, and the results of the present study showed that UA treatment induced apoptosis of NRK-52E cells in a concentration-dependent manner. Western blotting was performed to determine the expression levels of cleaved caspase-3, Bax and Bcl-xl, it was found that levels were significantly increased after UA treatment in NRK-52E cells. ROS and apoptosis were predominantly induced in NRK-52E cells and there was an association between ROS and apoptosis. Enhanced expression of NEK7, NLRP3, apoptosis-associated speck-like and caspase-1 were observed in NRK-52E cells treated with UA. The ROS inhibitor, N-acetyl-l-cysteine, exerted a protective effect on the UA-induced apoptosis of tubular epithelial cells by reducing excess ROS production, which significantly inhibited NEK7 and NLRP3 inflammasome activation. These results indicated that UA activates ROS and induces apoptosis of NRK-52E cells. The mechanism might be related to the regulation of the NEK7/NLRP3 signaling pathway.

Xanthine Oxidase-Induced Inflammatory Responses in Respiratory Epithelial Cells: A Review in Immunopathology of COVID-19

Xanthine oxidase (XO) is an enzyme that catalyzes the production of uric acid and superoxide radicals from purine bases: hypoxanthine and xanthine and is also expressed in respiratory epithelial cells. Uric acid, which is also considered a danger associated molecule pattern (DAMP), could trigger a series of inflammatory responses by activating the inflammasome complex path and NF-κB within the endothelial cells and by inducing proinflammatory cytokine release. Concurrently, XO also converts the superoxide radicals into hydroxyl radicals that further induce inflammatory responses. These conditions will ultimately sum up a hyperinflammation condition commonly dubbed as cytokine storm syndrome (CSS). The expression of proinflammatory cytokines and neutrophil chemokines may be reduced by XO inhibitor, as observed in human respiratory syncytial virus (HRSV)-infected A549 cells. Our review emphasizes that XO may have an essential role as an anti-inflammation therapy for respiratory viral infection, including coronavirus disease 2019 (COVID-19).

Gout Augments the Risk of Cardiovascular Disease in Patients With Psoriasis: A Population-Based Cohort Study

Objective

Patients with psoriasis (PsO) have a high frequency of concomitant gout and increased risk of cardiovascular diseases (CVD). We aimed to estimate the synergistic impact of gout on the risk of CVD in patients with PsO.

Methods

A population-based cohort of patients registered in the National Health Insurance Research Database of Taiwan between 2000 and 2013 was stratified according to the presence of PsO and gout. Propensity score analysis was used to match age and gender at a ratio of 1:4. Cox proportional hazard models and subgroup analyses were used to estimate the hazard ratios (HRs) for CVD adjusted for traditional risk factors. The Kaplan–Meier method was used to plot the cumulative incidence curves.

Results

Patients with combined PsO and gout (n = 97), PsO alone (n = 388), gout alone (matched, n = 388) and matched controls (n = 388) were identified. Compared with the patients with PsO alone, the patients with combined PsO and gout had a significantly higher risk of CVD (relative risk 2.39, 95% CI 1.56 to 3.65). After adjustment for traditional risk factors, the risk of CVD was higher in patients with gout alone (HR 2.16, 95% CI 1.54 to 3.04) and in patients with combined PsO and gout (HR 2.72, 95% CI 1.73 to 4.28).

Conclusions

Gout augments the risk of CVD independently of traditional risk factors in patients with PsO.

Network pharmacology and molecular docking analysis on molecular targets: Mechanisms of baicalin and baicalein against hyperuricemic nephropathy

Oxidative stress and inflammation in kidney are the main causes for hyperuricemic nephropathy (HN). Baicalin and baicalein, two flavonoids, have anti-inflammatory and anti-oxidative effects and they are interconvertible in the body. In this study, both baicalin and baicalein were administered by intragastric administration (i.g.) or intraperitoneal injection (i.p.) at the dose of 50 mg kg^-1, once a day for 15 consecutive days to HN mice, a model established by i.g. of yeast extract combined with i.p. of potassium oxonate. In HN mice, baicalin and baicalein reduced serum uric acid (SUA) levels and protected kidneys by anti-inflammatory and anti-oxidative effects. Mechanistically, the effect of baicalin and baicalein on reducing SUA levels might due to their inhibitory effect on xanthine oxidase (XO) activity in vivo and in vitro. Furthermore, the mechanisms of baicalin and baicalein against HN were analyzed with network pharmacology and molecular docking technology. The network pharmacology indicated that the protective effects of baicalin and baicalein against HN were mainly related to their down-regulating effects on TLRs, NF-κB, MAPK, PI3K/AKT and NOD-like receptor signaling pathways. Molecular docking indicated high binding affinity of baicalin/baicalein to targets such as AKT1 and MAPK1. In summary, baicalin and baicalein are promising drug candidates for the treatment of HN by inhibiting XO activity, reducing inflammation and cell apoptosis through down-regulating TLRs/NLRP3/NF-κB, MAPK, PI3K/AKT/NF-κB pathways.

Dotinurad: a novel selective urate reabsorption inhibitor for the treatment of hyperuricemia and gout

INTRODUCTION

Gout is an inflammatory disease triggered by deposition of urate crystals secondary to longstanding hyperuricemia, and its management implies both the treatment of flares and management of hyperuricemia. Dotinurad is a selective urate reabsorption inhibitor (SURI), potently inhibits urate transporter 1 in the apical surface of renal proximal tubular cells, and has been approved for the treatment of gout and hyperuricemia in Japan.

AREAS COVERED

This overview of dotinurad covers nonclinical and clinical pharmacology studies in special populations and its efficacy and safety in Japanese hyperuricemic patients with and without gout.

EXPERT OPINION

Dotinurad, as an SURI, is expected to inhibit urate reabsorption more effectively than conventional urate-lowering agents. It is noninferior to benzbromarone or febuxostat in reducing serum urate levels in hyperuricemic patients with or without gout. Its efficacy is not attenuated in patients with mild to moderate renal impairment or with hepatic impairment. At a maintenance dose of 2 or 4 mg once daily, most patients achieved the target serum urate level of ≤6 mg/dL in a long-term study. No findings that raised safety concerns, including liver injury, were identified. Dotinurad is expected to be a new therapeutic option in hyperuricemic patients with and without gout.

The Efficacy and Mechanism of Chinese Herbal Medicines in Lowering Serum Uric Acid Levels: A Systematic Review

Background. Chinese herbal medicines are widely used to lower serum uric acid levels. However, no systemic review summarizes and evaluates their efficacies and the underlying mechanisms of action. Objectives. To evaluate the clinical and experimental evidences for the effectiveness and the potential mechanism of Chinese herbal medicines in lowering serum uric acid levels. Methods. Four electronic databases PubMed, Wed of Science, the Cochrane Library and Embase were used to search for Chinese herbal medicines for their effects in lowering serum uric acid levels, dated from 1 January 2009 to 19 August 2020. For clinical trials, randomized controlled trials (RCTs) were included; and for experimental studies, original articles were included. The methodological quality of RCTs was assessed according to the Cochrane criteria. For clinical trials, a meta-analysis of continuous variables was used to obtain pooled effects. For experimental studies, lists were used to summarize and integrate the mechanisms involved. Results. A total of 10 clinical trials and 184 experimental studies were included. Current data showed that Chinese herbal medicines have promising clinical efficacies in patients with elevated serum uric acid levels (SMD: −1.65, 95% CI: −3.09 to −0.22; p = 0.024). There was no significant difference in serum uric acid levels between Chinese herbal medicine treatments and Western medicine treatments (SMD: −0.13, 95% CI: −0.99 to 0.74; p = 0.772). Experimental studies revealed that the mechanistic signaling pathways involved in the serum uric acid lowering effects include uric acid synthesis, uric acid transport, inflammation, renal fibrosis and oxidative stress. Conclusions. The clinical studies indicate that Chinese herbal medicines lower serum uric acid levels. Further studies with sophisticated research design can further demonstrate the efficacy and safety of these Chinese herbal medicines in lowering serum uric acid levels and reveal a comprehensive picture of the underlying mechanisms of action.

The roles of NLRP3 inflammasome-mediated signaling pathways in hyperuricemic nephropathy

Hyperuricemic nephropathy (HN) is a common clinical complication of hyperuricemia. High-serum uric acid can trigger renal inflammation. The inflammasome family has several members and shows a significant effect on inflammatory responses. NLRP3 (NOD-, LRR-, and pyrin domain-containing 3) senses the stimuli signal of excessive uric acid and then it recruits apoptosis-related specular protein (ASC) as well as aspartic acid-specific cysteine protease (caspase)-1 precursor to form NLRP3 inflammasome. NLRP3 inflammasome is activated in acute kidney injury (AKI), chronic kidney diseases (CKD), diabetic nephropathy (DN), and HN. This review focuses on important role for the involvement of NLRP3 inflammasome and associated signaling pathways in the pathogenesis of hyperuricemia-induced renal injury and the potential therapeutic implications. Additionally, several inhibitors targeting NLRP3 inflammasome are under development, most of them for experiment. Therefore, researches into NLRP3 inflammasome modulators may provide novel therapies for HN.

Uric Acid and Cardiovascular Disease: An Update From Molecular Mechanism to Clinical Perspective

Uric acid (UA) is the end product of purine nucleotide metabolism in the human body. Hyperuricemia is an abnormally high level of UA in the blood and may result in arthritis and gout. The prevalence of hyperuricemia has been increasing globally. Epidemiological studies have shown that UA levels are positively correlated with cardiovascular diseases, including hypertension, atherosclerosis, atrial fibrillation (AF), and heart failure (HF). Hyperuricemia promotes the occurrence and development of cardiovascular diseases by regulating molecular signals, such as inflammatory response, oxidative stress, insulin resistance/diabetes, endoplasmic reticulum stress, and endothelial dysfunction. Despite extensive research, the underlying molecular mechanisms are still unclear. Allopurinol, a xanthine oxidase (XO) inhibitor, has been shown to improve cardiovascular outcomes in patients with HF, coronary heart disease (CHD), type 2 diabetes (T2D), and left ventricular hypertrophy (LVH). Whether febuxostat, another XO inhibitor, can improve cardiovascular outcomes as well as allopurinol remains controversial. Furthermore, it is also not clear whether UA-lowering treatment (ULT) can benefit patients with asymptomatic hyperuricemia. In this review, we focus on the latest cellular and molecular findings of cardiovascular disease associated with hyperuricemia and clinical data about the efficacy of ULT in patients with cardiovascular disease.

High Concentrations of Uric Acid and Angiotensin II Act Additively to Produce Endothelial Injury

Renin angiotensin (Ang) system (RAS) activation in metabolic syndrome (MS) patients is associated with elevated uric acid (UA) levels, resulting in endothelial system dysfunction. Our previous study demonstrated that excessive UA could cause endothelial injury through the aldose reductase (AR) pathway. This study is the first to show that a high concentration of Ang II in human umbilical vein endothelial cells (HUVECs) increases reactive oxygen species (ROS) components, including O₂^·- and H₂O₂, and further aggravates endothelial system injury induced by high UA (HUA). In a MS/hyperuricemia model, nitric oxide (NO) production was decreased, followed by a decrease in total antioxidant capacity (TAC), and the concentration of the endothelial injury marker von Willebrand factor (vWF) in the serum was increased. Treatment with catalase and polyethylene glycol covalently linked to superoxide dismutase (PEG-SOD) to individually remove H₂O₂ and O₂^·- or treatment with the AR inhibitor epalrestat decreased ROS and H₂O₂, increased NO levels and TAC, and reduced vWF release. Taken together, these data indicate that HUA and Ang II act additively to cause endothelial dysfunction via oxidative stress, and specific elimination of O₂^·- and H₂O₂ improves endothelial function. We provide theoretical evidence to prevent or delay endothelial injury caused by metabolic diseases.

Pyroptosis: The missing puzzle among innate and adaptive immunity crosstalk

Pyroptosis is a newly discovered programmed cell death with inflammasome formation. Pattern recognition receptors that identify repetitive motifs of prospective pathogens such as LPS of gram-negative bacteria are crucial to pyroptosis. Upon stimulation by pathogen-associated molecular patterns or damage-associated molecular patterns, proinflammatory cytokines, mainly IL-1 family members IL-1β and IL-18, are released through pyroptosis specific pore-forming protein, gasdermin D. Even though IL-1 family members are mainly involved in innate immunity, they can be factors in adaptive immunity. Given the importance of IL-1 family members in health and diseases, deciphering the role of pyroptosis in the regulation of innate and adaptive immunity is of great importance, especially with the recent progress in identifying the exact mechanism of such a pathway. In this review, we will focus on how the innate inflammatory mediators can regulate the adaptive immune system and vice versa via pyroptosis.

Emerging insights into molecular mechanisms underlying pyroptosis and functions of inflammasomes in diseases

Pyroptosis is a form of necrotic and inflammatory programmed cell death, which could be characterized by cell swelling, pore formation on plasma membranes, and release of proinflammatory cytokines (IL-1β and IL-18). The process of pyroptosis presents as dual effects: protecting multicellular organisms from microbial infection and endogenous dangers; leading to pathological inflammation if overactivated. Two pathways have been found to trigger pyroptosis: caspase-1 mediated inflammasome pathway with the involvement of NLRP1-, NLRP3-, NLRC4-, AIM2-, pyrin-inflammasome (canonical inflammasome pathway) and caspase-4/5/11-mediated inflammasome pathway (noncanonical inflammasome pathway). Gasdermin D (GSDMD) has been proved to be a substrate of inflammatory caspases (caspase-1/4/5/11), and the cleaved N-terminal domain of GSDMD oligomerizes to form cytotoxic pores on the plasma membrane. Here, we mainly reviewed the up to date mechanisms of pyroptosis, and began with the inflammasomes as the activator of caspase-1/caspase-11, 4, and 5. We further discussed these inflammasomes functions in diseases, including infectious diseases, sepsis, inflammatory autoimmune diseases, and neuroinflammatory diseases.

Parental Renovascular Hypertension-Induced Autonomic Dysfunction in Male Offspring Is Improved by Prenatal or Postnatal Treatment With Hydrogen Sulfide

Increasing evidence indicates there is a strong association between parental health during pregnancy and incidence of cardiovascular disease in adult offspring. Recently, hydrogen sulfide (H₂S) has been demonstrated to be a powerful vasodilator of the placental vasculature, improving intrauterine growth restriction. In this study, we investigated whether parental hypertension induces autonomic dysfunction in male adult offspring, and the H₂S mechanism underlying this autonomic dysfunction. 2-kidney-1-clip method was employed to induce parental hypertension during pregnancy and lactation in rats. Basal blood pressure (BP) and autonomic function of male offspring in adulthood was evaluated. Additionally, either maternal hypertensive dams or their male offspring after weaning were treated with H₂S to determine improving effects of H₂S on autonomic dysfunction. The BP was significantly increased in male offspring of renovascular hypertensive dams when compared to that in offspring of normotensive dams. The offspring of renovascular hypertensive dams also exhibited blunted baroreflex sensitivity, increased sympathetic effect and sympathetic tonus. Western blotting analysis revealed downregulation of endogenous H₂S catalyzed enzyme and upregulation of angiotensin Ang II type 1 receptor (AT1R) pathway in the nucleus tractus solitarius and rostral ventrolateral medulla, two hindbrain nuclei involved in BP and autonomic regulation, in these offspring. Either prenatal or postnatal treatment with H₂S improved the adverse effects. The results suggest that parental hypertension results in elevated BP and autonomic dysfunction in adult male offspring through activation of AT1R pathway and inhibition of endogenous H₂S production in the brain.