Soluble Uric Acid Activates the NLRP3 Inflammasome

Association between annual changes and visit-to-visit variability of serum uric acid and the kidney outcome in a general population

BACKGROUND

To determine whether variability of serum uric acid (UA) is associated with risk of chronic kidney disease (CKD) in a healthy population.

METHODS

Retrospective, longitudinal cohort study was conducted at a health examination center in China. The study enrolled subjects who had a minimum of three visits between 2011 and 2018. We assessed UA change and visit-to-visit UA variability including standard deviation (SD), coefficient of variation (CV), variability independent of the mean (VIM), and average real variability (ARV). Rapid estimated glomerular filtration rate (eGFR) decline was defined by annual eGFR change < -4 mL/min/1.73 m2/year. We conducted a multivariable-adjusted logistic regression analysis.

RESULTS

Ten thousand seven hundred and thirty-eight participants were included. During 4.43 ± 1.31 years follow-up, there were 535 cases with rapid eGFR decline and 240 cases developed CKD. Compared to the non-rapid eGFR decline group and non-CKD group, the UA annual changes and variability were higher in the rapid eGFR decline group and CKD group. The highest quartile of UA annual changes and variability showed a higher incident rate of rapid eGFR decline and that of CKD. After adjusting for covariates, OR for eGFR rapid decline in UA variability were 1.69 [1.53, 1.86] for annual changes of UA, 1.17 [1.08, 1.27] for SD of UA, 1.16 [1.06, 1.25] for CV of UA, 1.16 [1.07, 1.25] for VIM of UA, and 1.10 [1.02, 1.19] for ARV of UA. Consistent results were observed when CKD is used as the outcome.

CONCLUSIONS

Higher variability of serum UA was independently associated with the risk of kidney impairment.

A nonlinear correlation between the serum uric acid to creatinine ratio and the prevalence of hypertension: a large cross-sectional population-based study

OBJECTIVE

To explore the relationship between the serum uric acid to creatinine (UA/Cr) ratio and the prevalence of hypertension.

METHODS

In this cross-sectional study, we included 8571 individuals from the China Health and Nutrition Survey. Logistic regression analysis and restricted cubic spline (RCS) were used to analyze the relationship between the UA/Cr ratio and hypertension.

RESULTS

Compared with individuals without hypertension, individuals with hypertension had higher UA/Cr ratios. Multivariate logistic regression analysis showed that a higher UA/Cr ratio was closely related to a higher risk of hypertension (as a continuous variable, OR: 1.054, 95% CI: 1.014-1.095, p = 0.007; as a categorical variable, Q3 vs. Q1, OR: 1.183, 95% CI: 1.011-1.384, p = 0.035; Q4 vs. Q1, OR: 1.347, 95% CI: 1.146-1.582, p < 0.001). Subgroup analysis revealed that the correlation between the UA/Cr ratio and hypertension risk was stable in all subgroups except for the subgroup with diabetes and the subgroup with a BMI ≥ 28 kg/m2 (p < 0.05). Sensitivity analysis confirmed the robustness of the relationship between a higher UA/Cr ratio and a higher risk of hypertension (p < 0.05). The RCS showed that the UA/Cr ratio was nonlinearly related to hypertension risk. Further threshold effect showed that only a UA/Cr ratio less than 5.0 was related to hypertension risk (OR: 1.178, 95% CI: 1.086-1.278, p < 0.001), and the 2-piecewise linear regression model was superior to the 1-line linear regression model (p < 0.05).

CONCLUSION

The UA/Cr ratio was associated with the prevalence of hypertension.

Fucoidan from Laminaria japonica protects renal tubular epithelial cells from uric acid induced NLRP3-mediated pyroptosis through inhibition of NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Hyperuricemia is a common metabolic disease with prominent morbidity, it can lead to many adverse effects and complications, such as chronic nephrosis. Fucoidan has been used as natural drug for acute and chronic kidney disease for over 20 years in China, but the precise mechanisms underlying the renal protective function are still indefinable.

PURPOSE

This study is conducted to explore alleviation of fucoidan (FPS) from Laminaria japonica on urate-induced NOD-like receptor family, pyrin domain-containing 3 (NLRP3)-mediated pyroptosis in renal tubular epithelial cells HK-2, as well as the mechanism of nuclear factor κB (NF-κB) signaling pathway involved.

MATERIALS AND METHODS

HK-2 cells were treated with FPS, uric acid (UA), and inhibitor of NF-κB signaling pathway. Nitric oxide (NO) content and inducible nitric oxide synthase (iNOS) activity were determined with detection kits. Activation of intercellular NLRP3 inflammasome and NF-κB signaling pathway, gasdermin D (GSDMD) expression level were evaluated with western blot and quantitative reverse transcription-PCR (qRT-PCR), and immunofluorescent analysis.

RESULTS

Data showed that UA induced cellular inflammatory response demonstrated by elevated NO content, iNOS activity and expression level of NLRP3 inflammasome-mediated pyroptosis associated molecules including NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), Caspase-1, interleukin 18 (IL-18) and GSDMD, moreover the NF-κB signaling pathway was activated by UA. However, FPS exposure inhibited efficiently the UA induced adverse effect.

CONCLUSION

It can be concluded that FPS inhibited UA-induced NLRP3-mediated pyroptosis in HK-2 cells through repressing NF-κB signaling pathway.

Serum uric acid is associated with midbrain enlarged perivascular spaces: Results from Multi-modality Medical imaging sTudy bAsed on KaiLuan Study (META-KLS)

BACKGROUND

Serum uric acid (SUA) is a major cause of cardiovascular and cerebrovascular diseases. Whether and to what extent the excess risk of enlarged perivascular spaces (EPVS) conferred by SUA is unknown. The study was conducted to investigate the association between SUA and EPVS in different brain regions.

METHODS

Data are from Multi-modality medical imaging study based on Kailuan study (META-KLS) in this cross-sectional study. Participants were divided into five groups based on SUA levels, and EPVS in basal ganglia (BG), centrum semiovale (CSO) and midbrain (MB) was systematically assessed and divided into Low and High group. Odds ratio (OR) and 95% confidence intervals (95% CIs) for high EPVS outcomes were estimated using multivariable logistic regression analysis. Restricted cubic spline (RCS) was used to further investigate dose-response relationship.

RESULTS

A total of 1014 participants aged 25-83 years from 11 centers were enrolled in the study. In the multivariable-adjusted model, SUA, as an independent risk factor, correlated positively with high degree of MB-EPVS (OR, 1.002; 95% CI, 1.000 to 1.004; p = 0.023) in general population. In addition, RCS further demonstrated the linear association between SUA and MB-EPVS (p = 0.072). No association was found between SUA and BG-EPVS or CSO-EPVS.

CONCLUSION

SUA was an independent risk factor of MB-EPVS. High SUA levels were more predictive of increased risk occurrence of high degree of MB-EPVS, supporting a linear association between SUA and MB-EPVS and further indicating that SUA may play an important role in cerebral small vessel disease.

TRIAL REGISTRATION

The KaiLuan Study and META-KLS were registered online (ChiCTR2000029767 on chictr.org.cn and NCT05453877 on Clinicaltrials.gov, respectively).

John Yudkin's hypothesis: sugar is a major dietary culprit in the development of cardiovascular disease

To date, the risk of developing atherosclerosis has extended beyond Western countries and now affecting individuals from various ethnic backgrounds and age groups. Traditional risk factors of atherosclerosis, such as hypercholesterolemia, has been better controlled than before due to highly effective and inexpensive therapies at lowering plasma cholesterol levels. However, the role of reducing dietary cholesterol intake, as a public healthy strategy, in preventing the occurrence of cardiovascular mortalities has been recently challenged. Indeed, despite our continuous decline of dietary cholesterol intake within the last 50 years, the incidence of cardiovascular mortalities has continued to rise, thus raising the possibility that other dietary factors, such as fructose-containing sugars, are the major culprit. In the 1970s, John Yudkin first proposed that sugar was the predominant dietary factor that underlies the majority of cardiovascular mortalities, yet his hypothesis was dismissed. However, over the last 25 years substantial scientific evidence has been accumulated to support Yudkin's hypothesis. The objectives of this review are to highlight Yudkin's significant contribution to nutritional science by reviewing his hypothesis and summarizing the recent advances in our understanding of fructose metabolism. The metabolic consequences of fructose metabolism, such as fructose-induced uricemia, insulin resistance, lipoprotein hyperproduction and chronic inflammation, and how they are linked to atherosclerosis as risk factors will be discussed. Finally, the review will explore areas that warrant future research and raise important considerations that we need to evaluate when designing future studies.

A study on the antioxidant, anti-inflammatory, and xanthine oxidase inhibitory activity of the Artemisia vulgaris L. extract and its fractions

ETHNOPHARMACOLOGICAL RELEVANCE

Vietnamese people use mugwort (Artemisia vulgaris L.) to treat arthritis and gout. Our previous research shows that mugwort contains flavonoids, and its extract possesses antibacterial and anti-inflammatory activities. However, no publications have been on the xanthine oxidase inhibitory activity of mugwort and acute anti-inflammatory activity in vivo.

AIM OF THE STUDY

The study aimed to verify the antioxidant, xanthine oxidase inhibitory, and anti-inflammatory capabilities of mugwort extract in vitro and in vivo, isolate phyto-compounds from potential bioactive fractions, and then evaluate their potential in inhibiting xanthine oxidase.

METHODS

According to established methods, the extract and the active flavonoids were obtained using different chromatographic techniques. DPPH, ABTS, reducing power, and H2O2 elimination were used to evaluate antioxidant activity. The model of LPS-induced RAW264.7 cells was used to measure the inhibition of NO production. The carrageenan-induced paw oedema model was used to assess acute inflammation in mice. In vitro, xanthine oxidase inhibition assay was applied to investigate the effects of extract/compounds on uric acid production. Chemical structures were identified by spectral analysis.

RESULTS

The assessment of the acute inflammatory model in mice revealed that both the 96% ethanol and the 50% ethanol extracts significantly decreased oedema in the mice's feet following carrageenan-induced inflammation. 96% ethanol extract exhibited a better reduction in oedema at the low dose. The analysis revealed that the ethyl acetate fraction had the highest levels of total polyphenols and flavonoids. Additionally, this fraction demonstrated significant antioxidant activity in various assays, such as DPPH, ABTS, reducing power, and H2O2 removal. Furthermore, it displayed the most potent inhibition of xanthine oxidase, an anti-inflammatory activity. Five phytochemicals were isolated and determined from the active fraction such as luteolin (1), rutin (2), apigenin (3), myricetin (4), and quercetin (5). Except for rutin, the other compounds demonstrated the ability to inhibit effective xanthine oxidase compared to standard (allopurinol). Moreover, quercetin (5) inhibited NO production (IC50 21.87 μM).

CONCLUSION

The results indicate that extracts from A. vulgaris effectively suppressed the activity of xanthine oxidase and exhibited antioxidant and anti-inflammatory properties, potentially leading to a reduction in the production of uric acid in the body and eliminating ROS. The study identified mugwort extract and bioactive compounds derived from Artemisia vulgaris, specifically luteolin, apigenin, and quercetin, as promising xanthine oxidase inhibitors. These findings suggest that further development of these compounds is warranted. At the same time, the above results also strengthen the use of mugwort to treat gout disease in Vietnam.

Raising serum uric acid with a uricase inhibitor worsens PKD in rat and mouse models

Humans are predisposed to gout because they lack uricase that converts uric acid to allantoin. Rodents have uricase, resulting in low basal serum uric acid. A uricase inhibitor raises serum uric acid in rodents. There were two aims of the study in polycystic kidney disease (PKD): 1) to determine whether increasing serum uric acid with the uricase inhibitor, oxonic acid, resulted in faster cyst growth and 2) to determine whether treatment with the xanthine oxidase inhibitor, oxypurinol, reduced the cyst growth caused by oxonic acid. Orthologous models of human PKD were used: PCK rats, a polycystic kidney and hepatic disease 1 (Pkhd1) gene model of autosomal recessive PKD (ARPKD) and Pkd1RC/RC mice, a hypomorphic Pkd1 gene model. In PCK rats and Pkd1RC/RC mice, oxonic acid resulted in a significant increase in serum uric acid, kidney weight, and cyst index. Mechanisms of increased cyst growth that were investigated were proinflammatory cytokines, the inflammasome, and crystal deposition in the kidney. Oxonic acid resulted in an increase in proinflammatory cytokines in the serum and kidney in Pkd1RC/RC mice. Oxonic acid did not cause activation of the inflammasome or uric acid crystal deposition in the kidney. In Pkd1RC/RC male and female mice analyzed together, oxypurinol decreased the oxonic acid-induced increase in cyst index. In summary, increasing serum uric acid by inhibiting uricase with oxonic acid results in an increase in kidney weight and cyst index in PCK rats and Pkd1RC/RC mice. The effect is independent of inflammasome activation or crystal deposition in the kidney.NEW & NOTEWORTHY This is the first reported study of uric acid measurements and xanthine oxidase inhibition in polycystic kidney disease (PKD) rodents. Raising serum uric acid with a uricase inhibitor resulted in increased kidney weight and cyst index in Pkd1RC/RC mice and PCK rats, elevated levels of proinflammatory cytokines in the serum and kidney in Pkd1RC/RC mice, and no uric acid crystal deposition or activation of the caspase-1 inflammasome in the kidney.

Establishment and validation of prediction model for atherosclerotic cardiovascular disease in patients with hyperuricemia

OBJECTIVE

To construct a risk prediction model for atherosclerotic cardiovascular disease (ASCVD) in patients with hyperuricemia.

METHODS

Data in this study were obtained from the National Health and Nutrition Examination Survey (NHANES) (2007-2010). Participants from Huashan Hospital were included as an external validation. Logistic regression analysis was used to explore the relevant factors of ASCVD in patients with hyperuricemia. The discriminability of the model was evaluated using the area under the curve (AUC) statistic of the receiver operating characteristic curve. Hosmer-Lemeshow test, correction curve and decision curve analysis (DCA) were used to evaluate the model.

RESULTS

A total of 389 patients collected from the NHANES were included in the final analysis. Logistic regression analysis showed that age, creatinine (Cr), glucose (Glu), serum uric acid (SUA), and history of gout were predictive factors for ASCVD in hyperuricemia (HUA) patients. These predictive factors were used to construct a nomogram. And 157 patients from NHANES were in the internal validation group and 136 patients from Huashan Hospital were in the external validation group. The AUC values of the three groups were 0.943, 0.735, and 0.664. The p values of the Hosmer-Lemeshow test were .568, .600, and .763. The calibration curve showed consistency between the nomogram and the actual observed values. The DCA curve indicated that the model has good clinical practicality.

CONCLUSION

This study constructed the ASCVD risk prediction model for HUA patients, which is beneficial for medical staff to detect high-risk populations of ASCVD in the early stage.

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" [...].

Research advances in the anti-inflammatory effects of SGLT inhibitors in type 2 diabetes mellitus

Diabetes mellitus is one of the most significant global burden diseases. It is well established that a chronic, systemic, low-grade inflammatory condition is strongly correlated with type 2 diabetes mellitus (T2D) and the development of target-organ damage (TOD). Sodium-glucose cotransporter inhibitors (SGLTis), novel oral drugs for the treatment of diabetes, act mainly by reducing glucose reabsorption in proximal renal tubules and/or the intestine. Several high-quality clinical trials and large observational studies have revealed that SGLTis significantly improve cardiovascular and renal outcomes in T2D patients. Increasing evidence suggests that this is closely related to their anti-inflammatory properties, which are mainly manifested by a reduction in plasma concentrations of inflammatory biomarkers. This review analyses the potential mechanisms behind the anti-inflammatory effects of SGLTis in diabetes and presents recent evidence of their therapeutic efficacy in treating diabetes and related TOD.

Signaling pathways in uric acid homeostasis and gout: From pathogenesis to therapeutic interventions

Uric acid is a product of purine degradation, and uric acid may have multiple physiologic roles, including the beneficial effects as an antioxidant and neuroprotector, maintenance of blood pressure during low salt ingestion, and modulation of immunity. However, overproduction of metabolic uric acid, and/or imbalance of renal uric acid secretion and reabsorption, and/or underexcretion of extrarenal uric acid, e.g. gut, will contribute to hyperuricemia, which is a common metabolic disease. Long-lasting hyperuricemia can induce the formation and deposition of monosodium urate (MSU) crystals within the joints and periarticular structures. MSU crystals further induce an acute, intensely painful, and sterile inflammation conditions named as gout by NLRP3 inflammasome-mediated cleavage of pro-IL-1β to bioactive IL-1β. Moreover, hyperuricemia and gout are associated with multiple cardiovascular and renal disorders, e.g., hypertension, myocardial infarction, stroke, obesity, hyperlipidemia, type 2 diabetes mellitus and chronic kidney disease. Although great efforts have been made by scientists of modern medicine, however, modern therapeutic strategies with a single target are difficult to exert long-term positive effects, and even some of these agents have severe adverse effects. The Chinese have used the ancient classic prescriptions of traditional Chinese medicine (TCM) to treat metabolic diseases, including gout, by multiple targets, for more than 2200 years. In this review, we discuss the current understanding of urate homeostasis, the pathogenesis of hyperuricemia and gout, and both modern medicine and TCM strategies for this commonly metabolic disorder. We hope these will provide the good references for treating hyperuricemia and gout.

Large-scale cross-ancestry genome-wide meta-analysis of serum urate

Hyperuricemia is an essential causal risk factor for gout and is associated with cardiometabolic diseases. Given the limited contribution of East Asian ancestry to genome-wide association studies of serum urate, the genetic architecture of serum urate requires exploration. A large-scale cross-ancestry genome-wide association meta-analysis of 1,029,323 individuals and ancestry-specific meta-analysis identifies a total of 351 loci, including 17 previously unreported loci. The genetic architecture of serum urate control is similar between European and East Asian populations. A transcriptome-wide association study, enrichment analysis, and colocalization analysis in relevant tissues identify candidate serum urate-associated genes, including CTBP1, SKIV2L, and WWP2. A phenome-wide association study using polygenic risk scores identifies serum urate-correlated diseases including heart failure and hypertension. Mendelian randomization and mediation analyses show that serum urate-associated genes might have a causal relationship with serum urate-correlated diseases via mediation effects. This study elucidates our understanding of the genetic architecture of serum urate control.

NLRP inflammasomes in health and disease

NLRP inflammasomes are a group of cytosolic multiprotein oligomer pattern recognition receptors (PRRs) involved in the recognition of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) produced by infected cells. They regulate innate immunity by triggering a protective inflammatory response. However, despite their protective role, aberrant NLPR inflammasome activation and gain-of-function mutations in NLRP sensor proteins are involved in occurrence and enhancement of non-communicating autoimmune, auto-inflammatory, and neurodegenerative diseases. In the last few years, significant advances have been achieved in the understanding of the NLRP inflammasome physiological functions and their molecular mechanisms of activation, as well as therapeutics that target NLRP inflammasome activity in inflammatory diseases. Here, we provide the latest research progress on NLRP inflammasomes, including NLRP1, CARD8, NLRP3, NLRP6, NLRP7, NLRP2, NLRP9, NLRP10, and NLRP12 regarding their structural and assembling features, signaling transduction and molecular activation mechanisms. Importantly, we highlight the mechanisms associated with NLRP inflammasome dysregulation involved in numerous human auto-inflammatory, autoimmune, and neurodegenerative diseases. Overall, we summarize the latest discoveries in NLRP biology, their forming inflammasomes, and their role in health and diseases, and provide therapeutic strategies and perspectives for future studies about NLRP inflammasomes.

The Prevalence of Hyperuricemia and the Association Between Hyperuricemia and Age in Patients with Psychiatric Disorders to a General Hospital: A Cross-Section Study

Purpose

In clinical work, it has been found that the prevalence of hyperuricemia (HUA) is significantly higher in younger patients with psychiatric disorders, but there are few studies in this area. The present study aims to evaluate the prevalence of HUA and the relationship between the HUA and age in hospitalized patients with psychiatric disorders in the real world, and to provide a theoretical basis for clinical staff to pay attention to the metabolic indicators of younger patients and for future related studies.

Methods

This is a cross-sectional evaluation of a cohort of 1761 patients with psychiatric disorders of hospitalized. The categories of disorders designed for study included: Depression, Bipolar disorder, Schizophrenia, Anxiety, Obsessive-Compulsive disorder, Acute and transient psychotic disorder, Dissociative(conversion) disorders, Conduct disorders and Tic disorders. In addition, based on age, the participants are stratified into three groups. The authors used Kruskal-Wallis tests, chi-square tests, and multiple linear logistic regression to verify the relationship between HUA and age among hospitalized patients with psychiatric disorders.

Results

Overall, the estimated prevalence of HUA was 35.4%. The prevalence of HUA was significantly higher in individuals with 17 years and under compared to those with 45 years and above (P < 0.001). After adjusting for confounders, the prevalence of HUA remained higher at 17 years and under than at 45 years and above. Bipolar disorder can lead to an increased prevalence of HUA (P<0.05).

Conclusion

The prevalence of HUA was higher in hospitalized patients with psychiatric disorders, and the prevalence was inversely proportional to age.

DAMPs and DAMP-sensing receptors in inflammation and diseases

Damage-associated molecular patterns (DAMPs) are endogenous danger molecules produced in cellular damage or stress, and they can activate the innate immune system. DAMPs contain multiple types of molecules, including nucleic acids, proteins, ions, glycans, and metabolites. Although these endogenous molecules do not trigger immune response under steady-state condition, they may undergo changes in distribution, physical or chemical property, or concentration upon cellular damage or stress, and then they become DAMPs that can be sensed by innate immune receptors to induce inflammatory response. Thus, DAMPs play an important role in inflammation and inflammatory diseases. In this review, we summarize the conversion of homeostatic molecules into DAMPs; the diverse nature and classification, cellular origin, and sensing of DAMPs; and their role in inflammation and related diseases. Furthermore, we discuss the clinical strategies to treat DAMP-associated diseases via targeting DAMP-sensing receptors.

Uric acid in health and disease: From physiological functions to pathogenic mechanisms

Owing to renal reabsorption and the loss of uricase activity, uric acid (UA) is strictly maintained at a higher physiological level in humans than in other mammals, which provides a survival advantage during evolution but increases susceptibility to certain diseases such as gout. Although monosodium urate (MSU) crystal precipitation has been detected in different tissues of patients as a trigger for disease, the pathological role of soluble UA remains controversial due to the lack of causality in the clinical setting. Abnormal elevation or reduction of UA levels has been linked to some of pathological status, also known as U-shaped association, implying that the physiological levels of UA regulated by multiple enzymes and transporters are crucial for the maintenance of health. In addition, the protective potential of UA has also been proposed in aging and some diseases. Therefore, the role of UA as a double-edged sword in humans is determined by its physiological or non-physiological levels. In this review, we summarize biosynthesis, membrane transport, and physiological functions of UA. Then, we discuss the pathological involvement of hyperuricemia and hypouricemia as well as the underlying mechanisms by which UA at abnormal levels regulates the onset and progression of diseases. Finally, pharmacological strategies for urate-lowering therapy (ULT) are introduced, and current challenges in UA study and future perspectives are also described.

Robust positive association between serum urate and the risk of chronic obstructive pulmonary disease: hospital-based cohort and Mendelian randomisation study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and hyperuricaemia are both characterised by systemic inflammation. Preventing chronic diseases among the population with common metabolic abnormality is an effective strategy. However, the association of hyperuricaemia with the higher incidence and risk of COPD remains controversial. Therefore, replicated researches in populations with distinct characteristics or demographics are compellingly warranted.

METHODS

This cohort study adopted a design of ambispective hospital-based cohort. We used propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) to minimise the effects of potential confounding factors. A Cox regression model and restricted cubic spline (RCS) model were applied further to assess the effect of serum urate on the risk of developing COPD. Finally, we conducted a two-sample Mendelian randomisation (MR) analysis to explore evidence of causal association.

RESULTS

There is a higher incidence in the population with hyperuricaemia compared with the population with normal serum urate (22.29/1000 person-years vs 8.89/1000 person-years, p=0.009). This result is robust after performing PSM (p=0.013) and IPTW (p<0.001). The Cox model confirms that hyperuricaemia is associated with higher risk of developing COPD (adjusted HR=3.35 and 95% CI=1.61 to 6.96). Moreover, RCS shows that the risk of developing COPD rapidly increases with the concentration of serum urate when it is higher than the reference (420 µmol/L). Finally, in MR analysis, the inverse variance weighted method evidences that a significant causal effect of serum urate on COPD (OR=1.153, 95% CI=1.034 to 1.289) is likely to be true. The finding of MR is robust in the repeated analysis using different methods and sensitivity analysis.

CONCLUSIONS

Our study provides convincing evidence suggesting a robust positive association between serum urate and the risk of developing COPD, and indicates that the population with hyperuricaemia is at high risk of COPD in the Chinese population who seek medical advice or treatment in the hospital.

Natural antibodies drive type 2 immunity in response to damage-associated molecular patterns

Allergic airway disease (AAD) is an example of type 2 inflammation that leads to chronic airway eosinophilia controlled by CD4 Th2 cells. Inflammation is reinforced by mast cells and basophils armed with allergen-specific IgE made by allergen-specific B2 B cells of the adaptive immune system. Little is known about how AAD is affected by innate B1 cells, which produce natural antibodies (NAbs) that facilitate apoptotic cell clearance and detect damage- and pathogen-associated molecular patterns (DAMPS and PAMPS). We used transgenic mice lacking either B cells or NAbs in distinct mouse models of AAD that require either DAMPS or PAMPS as the initial trigger for type 2 immunity. In a DAMP-induced allergic model, driven by alum and uric acid, mouse strains lacking B cells (CD19DTA), NAbs (IgHEL MD4), or all secreted antibodies (sIgm-/-Aid-/-) displayed a significant reduction in both eosinophilia and Th2 priming compared with WT or Aid-/- mice lacking only germinal center-dependent high-affinity class-switched antibodies. Replenishing B cell-deficient mice with either unimmunized B1 B cells or NAbs during sensitization restored eosinophilia, suggesting that NAbs are required for licensing antigen-presenting cells to prime type 2 immunity. Conversely, PAMP-dependent type 2 priming to house dust mite or Aspergillus was not dependent on NAbs. This study reveals an underappreciated role of B1 B cell-generated NAbs in selectively driving DAMP-induced type 2 immunity.

Uric acid-driven NLRP3 inflammasome activation triggers lens epithelial cell senescence and cataract formation

Excessive uric acid (UA) is associated with age-related cataract. A previous study showed that a high UA level in the aqueous humor stimulated the senescence of lens epithelial cells (LECs), leading to cataract progression. To better understand the underlying mechanisms, we investigated UA-driven senescence in human lens tissue samples obtained during surgery, rat lens organ cultures, and in vivo experiments, using senescence-associated β-galactosidase (SA-β-gal) staining, electronic microscopy, Western blotting, and histological analyses. Initially, we identified markedly higher expressions of NLRP3 and caspase-1 in the lens capsules of hyper-uricemic patients compared to normo-uricemic patients. This increase was accompanied by a significant rise in the SA-β-gal positive rate. We next built a cataract model in which rat lenses in an organ culture system were treated with an increasing dosage of UA. Notably, opacification was apparent in the lenses treated with 800 μM of UA starting on the fifth day. Mechanistically, UA treatment not only significantly induced the expression of NLRP3, caspase-1, and IL-1β, but also upregulated the levels of SA-β-gal and the senescence regulators p53 and p21. These effects were fully reversed, and lens opacification was ameliorated by the addition of MCC950, a selective NLRP3 antagonist. Moreover, an in vivo model showed that intravitreal UA injection rapidly induced cataract phenotypes within 21 days, an effect significantly mitigated by co-injection with MCC950. Together, our findings suggest that targeting the UA-induced NLRP3 inflammasome with MCC950 could be a promising strategy for preventing cataract formation associated with inflammageing.

Association between urinary uric acid excretion and kidney outcome in patients with CKD

Inhibiting tubular urate reabsorption may protect the kidney from urate-induced tubular injury. However, this approach may promote intratubular uric acid crystallization, especially in acidified urine, which could be toxic to the kidney. To assess how tubular urate handling affects kidney outcomes, we conducted a retrospective cohort study including 1042 patients with estimated glomerular filtration rates (eGFR) of 15-60 mL/min/1.73 m2. The exposures were fractional excretion of uric acid (FEUA) and urinary uric acid-to-creatinine ratio (UUCR). The kidney outcome was defined as a halving of eGFR from baseline or initiating kidney replacement therapy. The median FEUA and UUCR were 7.2% and 0.33 g/gCre, respectively. During a median follow-up of 1.9 years, 314 kidney outcomes occurred. In a multivariate Cox model, the lowest FEUA quartile exhibited a 1.68-fold higher rate of kidney outcome than the highest FEUA quartile (95% confidence interval, 1.13-2.50; P = 0.01). Similarly, lower UUCR was associated with a higher rate of kidney outcome. Notably, patients in the highest quartile of FEUA and UUCR were at the lowest risk of kidney outcome even among those with aciduria. In conclusion, lower FEUA and UUCR were associated with a higher risk of kidney failure, suggesting that increased urate reabsorption is harmful to the kidney.

Zerumbone reduces TLR2 stimulation-induced M1 macrophage polarization pattern via upregulation of Nrf-2 expression in murine macrophages

Hyperuricemia contributes significantly to gout arthritis pathogenesis, which promotes urate crystal deposition in the joints and activates joint-resident macrophages and circulating monocytes to initiate a state of inflammatory arthritis. In the joint, macrophages have an immune defense role where the presence of urate crystals results in the inflammatory mediators secretion, inflammatory cells recruitment to the joint, and shift macrophage population toward M1 pro-inflammatory phenotypes. Current treatment modalities of gout arthritis have side effects that limit their use in the elderly. A novel treatment that targets macrophage polarization to re-establish homeostasis may initiate a drug discovery program of novel disease-modifying agents for gout. Zerumbone (Zer) is a sesquiterpenoid bioactive compound found in the rhizome of Zingiberaceae family and possesses anti-inflammatory, antioxidant, and anti-proliferative activity. Our study hypothesized that soluble uric acid (sUA) and Pam3CSK4 (TLR2 agonist) reduce the anti-inflammatory function of murine M2 bone marrow-derived macrophages and change the expression of M2 genetic markers toward M1 phenotypes. We observed that priming of M2 macrophages with sUA and Pam3CSK4 significantly decreased M2 specific markers expression, e.g., Arg-1, Ym-1, and Fizz-1, enhanced mRNA expression of IL-1β, TNF-α, CXCL2, and iNOS and increased oxidative stress in M2 macrophages, as exhibited by a reduction in Nrf2 expression. We also aimed to study the impact of Zer on reducing the pro-inflammatory effect of sUA in TLR2-stimulated M2 macrophages. We noticed that Zer treatment significantly reduced L-1β and TNF-α production following Pam3CSK4 + sUA treatment on M2 macrophages. Furthermore, Zer reduced the caspase-1 activity without altering cytosolic NLRP3 content in challenged M2 BMDMs. We also observed that Zer significantly enhanced M2-associated marker's expression, e.g., Arg-1, Ym-1, and Fizz-1, and augmented Nrf-2 and other antioxidant proteins, including HMOX1 and srxn1expression following Pam3CSK4 + sUA treatment. We draw the conclusion that Zer is a potentially effective anti-inflammatory treatment for gout arthritis linked to hyperuricemia.

Small molecule mediators of host-T. cruzi-environment interactions in Chagas disease

Small molecules (less than 1,500 Da) include major biological signals that mediate host-pathogen-microbiome communication. They also include key intermediates of metabolism and critical cellular building blocks. Pathogens present with unique nutritional needs that restrict pathogen colonization or promote tissue damage. In parallel, parts of host metabolism are responsive to immune signaling and regulated by immune cascades. These interactions can trigger both adaptive and maladaptive metabolic changes in the host, with microbiome-derived signals also contributing to disease progression. In turn, targeting pathogen metabolic needs or maladaptive host metabolic changes is an important strategy to develop new treatments for infectious diseases. Trypanosoma cruzi is a single-celled eukaryotic pathogen and the causative agent of Chagas disease, a neglected tropical disease associated with cardiac and intestinal dysfunction. Here, we discuss the role of small molecules during T. cruzi infection in its vector and in the mammalian host. We integrate these findings to build a theoretical interpretation of how maladaptive metabolic changes drive Chagas disease and extrapolate on how these findings can guide drug development.

The effect of danger-associated molecular patterns on survival in acute graft versus host disease

Danger-associated molecular patterns (DAMPs) are molecules that can initiate and maintain robust inflammatory responses and were investigated in the pathogenesis of graft versus host disease (GvHD). Uric acid (UA) and fibrinogen (Fib) are DAMPs released from damaged tissue during allogeneic hematopoietic stem cell transplantation (allo-HCT) and GvHD. We aimed to evaluate the effects of UA and Fib levels on survival in GvHD. One hundred seventy-four patients with grade 2-4 acute GvHD were included. UA and Fib levels were evaluated on allo-HCT day 0 and GvHD on days 0, 7, 14, and 28. Fib GvHD day 0 was the independent predictor for overall survival (OS), non-relapse mortality (NRM), and progression-free survival in multivariable models (HR 0.98, p < 0.001; HR 0.98, p = 0.001, HR 0.98, p = 0.006, respectively). Also UA GvHD day 28 was the independent predictor for OS and NRM (HR 0.77, p = 0.004; HR 0.76, p = 0.011, respectively). Our results indicated that hypouricemia and hypofibrinogenemia were associated with a significantly shorter OS and higher NRM. UA and Fib are remarkable molecules in GvHD because they are routinely utilized, readily available, can be therapeutic targets, and have DAMPs and antioxidant features.

SGLT2 Inhibition in Heart Failure: Clues to Cardiac Effects?

Following the publication of several landmark clinical trials such as dapagliflozin in patients with heart failure and reduced ejection fraction, dapagliflozin evaluation to improve the lives of patients with preserved ejection fraction heart failure, and empagliflozin outcome trial in patients with chronic heart failure with preserved ejection fraction, sodium-glucose cotransport 2 inhibitors have been rapidly incorporated as a guideline-directed therapy in the treatment of heart failure. Moreover, their benefits appear to extend across the spectrum of left ventricular dysfunction which in some respects, can be seen as the holy grail of heart failure pharmacotherapy. Despite its plethora of proven cardioprotective benefits, the mechanisms by which it exerts these effects remain poorly understood, however, it is clear that these extend beyond that of promotion of glycosuria and natriuresis. Several hypotheses have emerged over the years including modification of cardiovascular risk profile via weight reduction, improved glucose homeostasis, blood pressure control, and natriuretic effect; however, these mechanisms do not fully explain the potent effects of the drug demonstrated in large-scale randomized trials. Other mechanisms may be at play, specifically the down-regulation of inflammatory pathways, improved myocardial sodium homeostasis, modulation of profibrotic pathways, and activation of nutrient deprivation signaling pathways promoting autophagic flux. This review seeks to summarize the cardioprotective benefits demonstrated in major clinical trials and provide a succinct review of the current theories of mechanisms of action, based on the most recent evidence derived from both clinical and laboratory data.

Uric acid promotes interleukin-17 expression to cause kidney injury

Uric acid, an oxidation end-product of purine metabolism, is reportedly to be a risk factor for kidney injury. However, its underlying mechanism is still a mystery. This study aimed to reveal the detailed roles of uric acid in inducing kidney injury and the possible mechanisms. Injection of rats with uric acid significantly increased tubular injury score, and levels of blood urea nitrogen, serum creatinine, and urine kidney injury molecule-1. Uric acid increased the expression of collagen I, alpha-smooth muscle actin, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. Kyoto Encyclopedia of Genes and Genomes analysis result showed the IL-17 signaling pathway as the most significantly enriched pathway involved in hyperuricemia-related kidney injury. Long-term injection of uric acid induced significant production of IL-17 and recruitment of Th17 cells. Treating rats with the anti-IL-17 mAb attenuated uric acid-induced kidney injury, accompanied by the inactivation of nuclear factor-κB (NF-κB). In conclusion, uric acid was confirmed to be a risk factor for kidney injury via inducing IL-17 expression. Neutralization of IL-17 using the specific mAb relieved uric acid-induced kidney injury via inhibition of NF-κB signaling.

Study of hispidulin in the treatment of uric acid nephropathy based on NF-κB signaling pathway

Uric acid nephropathy (UAN) is caused by purine metabolism disorders. UAN rat models were established in SD rats. The modeling rats received different doses of hispidulin (10, 20, 50 mg/mL). Febuxostat was applied as the positive drug. Serum creatinine, uric acid (UA), and cystatin-C (cys-C), neutrophil gelatinase-associated lipocalin (NGAL), IL-1β, IL-8, TNF-α, and IL-6 in rats were detected. HE staining was done to assess kidney injury. UAN rats possessed prominent levels of serum creatinine, UA, cys-C, and NGAL, which all reduced after hispidulin treatment in a dose-dependent manner. HE staining determined the improvement of kidney injury after treatment, which was comparable to the efficacy of febuxostat. Hispidulin inhibited the release of IL-1β, IL-8, TNF-α, and IL-6 in UAN rats. Hispidulin enhanced autophagy in UAN rats, presenting as ascending LC3II/I ratio and downregulated P62. The increasing trend of inflammasome-related proteins of NLRP3 and Caspase-1 was changeovered by hispidulin. The activation of NF-kB signaling was intercepted by hispidulin in UAN rats. Hispidulin can effectively improve renal function injury caused by UAN in rats. The mechanism may be related to the inhibition of inflammatory response induced by autophagy and activation of NF-κB pathway.

Food-derived peptides as novel therapeutic strategies for NLRP3 inflammasome-related diseases: a systematic review

NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3), a member of the nucleotide-binding domain (NOD) and leucine-rich repeat sequence (LRR) protein (NLR) family, plays an essential role in the inflammation initiation and inflammatory mediator secretion, and thus is also associated with many disease progressions. Food-derived bioactive peptides (FDBP) exhibit excellent anti-inflammatory activity in both in vivo and in vitro models. They are encrypted in plant, meat, and milk proteins and can be released under enzymatic hydrolysis or fermentation conditions, thereby hindering the progression of hyperuricemia, inflammatory bowel disease, chronic liver disease, neurological disorders, lung injury and periodontitis by inactivating the NLRP3. However, there is a lack of systematic review around FDBP, NLRP3, and NLRP3-related diseases. Therefore, this review summarized FDBP that exert inhibiting effects on NLRP3 inflammasome from different protein sources and detailed their preparation and purification methods. Additionally, this paper also compiled the possible inhibitory mechanisms of FDBP on NLRP3 inflammasomes and its regulatory role in NLRP3 inflammasome-related diseases. Finally, the progress of cutting-edge technologies, including nanoparticle, computer-aided screening strategy and recombinant DNA technology, in the acquisition or encapsulation of NLRP3 inhibitory FDBP was discussed. This review provides a scientific basis for understanding the anti-inflammatory mechanism of FDBP through the regulation of the NLRP3 inflammasome and also provides guidance for the development of therapeutic adjuvants or functional foods enriched with these FDBP.

The Management of Diabetes with Hyperuricemia: Can We Hit Two Birds with One Stone?

Serum urate (SU) is an independent predictor for the incidence of diabetes. In current diabetes treatment regimens, there is insufficient appreciation of the importance of hyperuricemia (HU) in disease control and prevention. To summarize the updated knowledge on the effects of SU on β-cell function, insulin resistance and chronic diabetic complications, as well as to evaluate the management of patients with both HU and diabetes, we searched the MEDLINE PubMed database, and included 285 journal articles. An inverted U-shaped relationship between fasting plasma glucose and SU levels was established in this review. Elevated SU levels may enhance the development of chronic diabetic complications, including macrovascular and microvascular dysfunction. Diet and exercise are essential parts of the lifestyle changes necessary for HU and diabetes management. Glucose- and urate-lowering drug selection and combination should be made with the principle of ameliorating, and at least not deteriorating, diabetes and HU. Medical artificial intelligence technology and monitoring systems can help to improve the effectiveness of long-term management of HU and diabetes through digital healthcare. This study comprehensively reviews and provides a scientific and reliable basis for and viewpoints on the clinical management of diabetes and HU.

Serum uric acid was non-linearly associated with the risk of all-cause and cardiovascular death in individuals with coronary heart disease: a large prospective cohort study

Objective

To investigate the association of serum uric acid (SUA) with all-cause and cardiovascular death in individuals with coronary heart disease (CHD).

Methods

In this prospective cohort study, 1556 individuals from the National Health and Nutrition Examination Survey (1999-2015) were included in the analysis. Multivariate COX regression analysis, restricted cubic spline plot (RCS) and threshold effect were used to investigate the association between SUA and all-cause and cardiovascular death in individuals with CHD.

Results

In the fully adjusted model, when SUA was regarded as a continuous variable, it was closely associated with the risk of all-cause and cardiovascular death (P < 0.01). When all participants were divided into four groups according to the quartile of SUA, compared with Q1 group, only individuals in Q4 group had higher risk of all-cause and cardiovascular death (P = 0.002 and 0.034). The following subgroup analysis showed that the association between SUA and all-cause death risk was still statistically significant in individuals over 60 years old, male, with hypertension, without diabetes and with chronic kidney disease, while the association with cardiovascular death risk only persisted in individuals over 60 years old and male (P < 0.05). Further sensitivity analysis showed that SUA was still closely associated with all-cause and cardiovascular death, whether as a continuous variable or a classified variable (P = 0.007 and 0.044). RCS analysis revealed that SUA had a nonlinear association with all-cause and cardiovascular death risk (P for nonlinearity < 0.01). Threshold effect analysis showed that SUA below 345 umol/L was negatively associated with all-cause and cardiovascular death risk (P < 0.05), while SUA above 345 umol/L was positively associated with all-cause and cardiovascular death risk (P < 0.001), and the 2-piecewise regression model was better than the 1-line regression model (P for likelihood ratio test < 0.05).

Conclusion

SUA had a nonlinear association with all-cause and cardiovascular death risk in individuals with CHD.

Zinc improves sexual and erectile function in HAART-treated rats via the upregulation of erectogenic enzymes and maintenance of redox balance

PURPOSE

HAART has been shown to impair sexual function and penile erection via perturbation of penile redox balance, while zinc has been established to exert antioxidant activity. Therefore, this study focused on the role and associated molecular mechanism of zinc in HAART-induced sexual and erectile dysfunction.

MATERIALS AND METHODS

Twenty male Wistar rats were randomly grouped into four (n = 5 rats per group); the control, zinc-treated, HAART-treated, and HAART + zinc-treated groups. Treatments were per os daily for eight weeks.

RESULTS

Zinc co-administration significantly improved HAART-induced increase in the latencies of mount, intromission, and ejaculations. Zinc also attenuated HAART-induced reduction in the motivation to mate, penile reflex/erection, and frequencies of mount, intromission, and ejaculations. In addition, zinc co-treatment improved HAART-induced decline in penile NO and cGMP, dopamine, and serum testosterone. More so, zinc prevented HAART-induced rise in penile activities of monoamine oxidase, acetylcholinesterase, phosphodiesterase-5, and arginase. Furthermore, concomitant treatment with zinc ameliorated HAART-induced penile oxidative stress and inflammation.

CONCLUSION

In conclusion, our present findings show that zinc improves sexual and erectile function in HAART-treated rats by upregulating erectogenic enzymes via the maintenance of penile redox balance.

Lunasin ameliorates glucose utilization in C2C12 myotubes and metabolites profile in diet-induced obese mice benefiting metabolic disorders

AIMS

Obesity is the main cause of low-grade inflammation and oxidation, resulting in insulin resistance. This study aimed to investigate the effects of a seed peptide lunasin on glucose utilization in C2C12 myotubes and the metabolite profiles in obese mice.

MAIN METHODS

C2C12 myotubes were challenged by palmitic acid (PA) to mimic the obese microenvironment and inflammation, cell vitality, and glucose utilization were determined. C57BL6/j mice were divided into low-fat diet (LF), high-fat diet (HF), and HF with intraperitoneally injected lunasin (HFL) groups. Glucose intolerance and metabolite profiles of the tissues were analyzed.

KEY FINDINGS

In vitro, C2C12 myotubes treated with lunasin showed decreased proinflammatory cytokines and increased cell vitality under palmitic acid conditions. Lunasin improved glucose uptake and glucose transporter 4 expression by activating insulin receptor substrate-1 and AKT phosphorylation. Next-generation sequencing revealed that lunasin regulates genes expression by promoting insulin secretion and decreasing oxidative stress. In vivo, HF mice showed increased tricarboxylic acid cycle and uric acid metabolites but decreased bile acids metabolites and specific amino acids. Lunasin intervention improved glucose intolerance and modulated metabolites associated with increased insulin sensitivity and decreased metabolic disorders.

SIGNIFICANCE

This study is the first to reveal that lunasin is a promising regulator of anti-inflammation, anti-oxidation, and glucose utilization in myotubes and ameliorating glucose uptake and metabolite profiles in obese mice, contributing to glucose homeostasis and benefiting metabolic disorders.

Placentas from Women with Late-Onset Preeclampsia Exhibit Increased Expression of the NLRP3 Inflammasome Machinery

Pre-eclampsia is a harmful and potentially lethal medical condition during pregnancy clinically diagnosed by hypertension and commonly accompanied by proteinuria and multiorgan affections. According to the time of diagnosis, it is differentiated between early-onset (EO-PE) and late-onset preeclampsia (LO-PE). Despite being less dangerous and presenting distinct pathophysiological signatures, LO-PE has a greater prevalence than EO-PE, both having significant consequences on the placenta. Previous works have evidenced that exacerbated inflammation in this organ might play a potential pathogenic role in the development of pre-eclampsia, and there is some preliminary evidence that the hyperactivation of inflammasomes can be related to the altered immunoinflammatory responses observed in the placentas of these patients. However, the precise role of inflammasomes in the placentas of women with LO-PE remains to be fully understood. In this work, we have studied the gene and protein expression of the main components related to the canonical and non-canonical pathways of the inflammasome NLRP3 (NLRP3, ASC, caspase 1, caspase 5, caspase 8, interleukin 1β, and interleukin 18) in the placental tissue of women with LO-PE. Our results show a marked increase in all these components in the placentas of women who have undergone LO-PE, suggesting that NLRP3 inflammasome plays a potentially pathophysiological role in the development of this entity. Future works should aim to evaluate possible translational approaches to this dysregulation in these patients.

Integrative metabolomic and network pharmacological analysis reveals potential mechanisms of Cardamine circaeoides Hook.f. & Thomson in alleviating potassium oxonate-induced asymptomatic hyperuricemia in rats

Cardamine circaeoides Hook.f. & Thomson (CC), a herb of the genus Cardamine (family Brassicaceae), has a rich historical usage in China for both culinary and medicinal purposes. It is distinguished by its remarkable ability to hyperaccumulate selenium (Se). CC has demonstrated efficacy in the prevention of metabolic disorders. However, investigations into the effects of CC on asymptomatic hyperuricemia remain scarce. The objective of this study is to elucidate the mechanism by which CC aqueous extract (CCE) exerts its anti-hyperuricemic effects on asymptomatic hyperuricemic rats induced by potassium oxonate (PO) by integrating metabolomics and network pharmacological analysis. Asymptomatic hyperuricemia was induced by feeding rats with PO (1000 mg/kg) and CCE (0.75, 1.5, or 3 g/kg) once daily for 30 days. Various parameters, including body weight, uric acid (UA) levels, histopathology of renal tissue, and inflammatory factors (IL-1β, IL-6, IL-8, and TNF-α) were assessed. Subsequently, metabolomic analysis of kidney tissues was conducted to explore the effects of CCE on renal metabolites and the related pathways. Furthermore, network pharmacology was employed to explicate the mechanism of action of CCE components identified through UPLC-Q-TOF-MS analysis. Finally, metabolomic and network-pharmacology analyses were performed to predict crucial genes dysregulated in the disease model and rescued by CCE, which were then subjected to verification by RT-qPCR. The findings revealed that CCE significantly inhibited the UA levels from the 21st day to the 30th day. Moreover, CCE exhibited significant inhibition of IL-1β, IL-6, IL-8, and TNF-α levels in renal tissues. The dysregulation of 18 metabolites and the tyrosine, pyrimidine, cysteine, methionine, sphingolipid, and histidine metabolism pathways was prevented by CCE treatment. A joint analysis of targets predicted using the network pharmacology approach and the differential metabolites found in metabolics predicted 8 genes as potential targets of CCE, and 3 of them (PNP gene, JUN gene, and ADA gene) were verified at the mRNA level by RT-qPCR. We conclude that CCE has anti-hyperuricemia effects and alleviates renal inflammation in a rat model of hyperuricemia, and these efficacies are associated with the reversal of increased ADA, PNP, and JUN mRNA expression in renal tissues.

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.

Inhibitory Effect of Quercetin on Oxidative Endogen Enzymes: A Focus on Putative Binding Modes

Oxidative stress is defined as an imbalance between the production of free radicals and reactive oxygen species (ROS) and the ability of the body to neutralize them by anti-oxidant defense systems. Cells can produce ROS during physiological processes, but excessive ROS can lead to non-specific and irreversible damage to biological molecules, such as DNA, lipids, and proteins. Mitochondria mainly produce endogenous ROS during both physiological and pathological conditions. Enzymes like nicotinamide adenine dinucleotide phosphate oxidase (NOX), xanthine oxidase (XO), lipoxygenase (LOX), myeloperoxidase (MPO), and monoamine oxidase (MAO) contribute to this process. The body has enzymatic and non-enzymatic defense systems to neutralize ROS. The intake of bioactive phenols, like quercetin (Que), can protect against pro-oxidative damage by quenching ROS through a non-enzymatic system. In this study, we evaluate the ability of Que to target endogenous oxidant enzymes involved in ROS production and explore the mechanisms of action underlying its anti-oxidant properties. Que can act as a free radical scavenger by donating electrons through the negative charges in its phenolic and ketone groups. Additionally, it can effectively inhibit the activity of several endogenous oxidative enzymes by binding them with high affinity and specificity. Que had the best molecular docking results with XO, followed by MAO-A, 5-LOX, NOX, and MPO. Que's binding to these enzymes was confirmed by subsequent molecular dynamics, revealing different stability phases depending on the enzyme bound. The 500 ns simulation showed a net evolution of binding for NOX and MPO. These findings suggest that Que has potential as a natural therapy for diseases related to oxidative stress.

C-reactive Protein Levels and Cardiovascular Outcomes After Febuxostat Treatment in Patients with Asymptomatic Hyperuricemia: Post-hoc Analysis of a Randomized Controlled Study

PURPOSE

Inflammation plays an important role in the initiation and progression of atherosclerosis, leading to poor clinical outcomes. Hyperuricemia is associated with the activation of the Nod-like receptor protein 3 inflammasome. Here, we investigated whether inhibition of inflammation using febuxostat lowered the risk of cardiovascular events.

METHODS

This is a post-hoc analysis of the randomized trial, Febuxostat for Cerebral and CaRdiorenovascular Events PrEvEntion StuDy (FREED). In total, 1067 patients (736 men and 331 women) were included in the analysis. We compared the serial changes in high-sensitivity C-reactive protein (hs-CRP) levels between febuxostat and non-febuxostat groups and assessed the correlation between the changes in uric acid (UA) and hs-CRP levels after febuxostat treatment. We also determined whether febuxostat could reduce a hard endpoint, defined as a composite of cardiovascular events and all-cause mortality.

RESULTS

Serum UA levels in the febuxostat group were significantly lower than those in the non-febuxostat group after randomization (p < 0.05). However, hs-CRP levels were comparable between the two groups during the study. No significant correlation was observed between the changes in UA and hs-CRP levels after febuxostat treatment. The hard endpoints did not differ significantly between the two groups. In patients with baseline hs-CRP levels > 0.2 mg/dL or those administered 40 mg of febuxostat, the drug did not reduce hs-CRP levels or decrease the hard endpoint.

CONCLUSION

Febuxostat reduced the UA levels but did not affect the CRP levels, and therefore may fail to improve cardiovascular outcomes after treatment.

TRIAL REGISTRATION

ClinicalTrial.gov (NCT01984749). https://clinicaltrials.gov/ct2/show/NCT01984749.

Inhibition of the uric acid efflux transporter ABCG2 enhances stimulating effect of soluble uric acid on IL-1β production in murine macrophage-like J774.1 cells

Soluble uric acid (UA) absorbed by cells through UA transporters (UATs) accumulates intracellularly, activates the NLRP3 inflammasome and thereby increases IL-1β secretion. ABCG2 transporter excludes intracellular UA. However, it remains unknown whether ABCG2 inhibition leads to intracellular accumulation of UA and increases IL-1β production. In this study, we examined whether genetic and pharmacological inhibition of ABCG2 could increase IL-1β production in mouse macrophage-like J774.1 cells especially under hyperuricemic conditions. We determined mRNA and protein levels of pro-IL-1β, mature IL-1β, caspase-1 and several UATs in culture supernatants and lysates of J774.1 cells with or without soluble UA pretreatment. Knockdown experiments using an shRNA against ABCG2 and pharmacological experiments with an ABCG2 inhibitor were conducted. Extracellularly applied soluble UA increased protein levels of pro-IL-1β, mature IL-1β and caspase-1 in the culture supernatant from lipopolysaccharide (LPS)-primed and monosodium urate crystal (MSU)-stimulated J774.1 cells. J774.1 cells expressed UATs of ABCG2, GLUT9 and MRP4, and shRNA knockdown of ABCG2 increased protein levels of pro-IL-1β and mature IL-1β in the culture supernatant. Soluble UA increased mRNA and protein levels of ABCG2 in J774.1 cells without either LPS or MSU treatment. An ABCG2 inhibitor, febuxostat, but not a urate reabsorption inhibitor, dotinurad, enhanced IL-1β production in cells pretreated with soluble UA. In conclusion, genetic and pharmacological inhibition of ABCG2 enhanced IL-1β production especially under hyperuricemic conditions by increasing intracellularly accumulated soluble UA that activates the NLRP3 inflammasome and pro-IL-1β transcription in macrophage-like J774.1 cells.

Obstructive nephropathy and molecular pathophysiology of renal interstitial fibrosis

The kidneys play a key role in maintaining total body homeostasis. The complexity of this task is reflected in the unique architecture of the organ. Ureteral obstruction greatly affects renal physiology by altering hemodynamics, changing glomerular filtration and renal metabolism, and inducing architectural malformations of the kidney parenchyma, most importantly renal fibrosis. Persisting pathological changes lead to chronic kidney disease, which currently affects ∼10% of the global population and is one of the major causes of death worldwide. Studies on the consequences of ureteral obstruction date back to the 1800s. Even today, experimental unilateral ureteral obstruction (UUO) remains the standard model for tubulointerstitial fibrosis. However, the model has certain limitations when it comes to studying tubular injury and repair, as well as a limited potential for human translation. Nevertheless, ureteral obstruction has provided the scientific community with a wealth of knowledge on renal (patho)physiology. With the introduction of advanced omics techniques, the classical UUO model has remained relevant to this day and has been instrumental in understanding renal fibrosis at the molecular, genomic, and cellular levels. This review details key concepts and recent advances in the understanding of obstructive nephropathy, highlighting the pathophysiological hallmarks responsible for the functional and architectural changes induced by ureteral obstruction, with a special emphasis on renal fibrosis.

The fructose survival hypothesis for obesity

The fructose survival hypothesis proposes that obesity and metabolic disorders may have developed from over-stimulation of an evolutionary-based biologic response (survival switch) that aims to protect animals in advance of crisis. The response is characterized by hunger, thirst, foraging, weight gain, fat accumulation, insulin resistance, systemic inflammation and increased blood pressure. The process is initiated by the ingestion of fructose or by stimulating endogenous fructose production via the polyol pathway. Unlike other nutrients, fructose reduces the active energy (adenosine triphosphate) in the cell, while blocking its regeneration from fat stores. This is mediated by intracellular uric acid, mitochondrial oxidative stress, the inhibition of AMP kinase and stimulation of vasopressin. Mitochondrial oxidative phosphorylation is suppressed, and glycolysis stimulated. While this response is aimed to be modest and short-lived, the response in humans is exaggerated due to gain of 'thrifty genes' coupled with a western diet rich in foods that contain or generate fructose. We propose excessive fructose metabolism not only explains obesity but the epidemics of diabetes, hypertension, non-alcoholic fatty liver disease, obesity-associated cancers, vascular and Alzheimer's dementia, and even ageing. Moreover, the hypothesis unites current hypotheses on obesity. Reducing activation and/or blocking this pathway and stimulating mitochondrial regeneration may benefit health-span. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part I)'.

Concurrence of hyperinsulinemia and hyperuricemia significantly augmented all-cause mortality

BACKGROUND AND AIMS

Hyperinsulinemia and hyperuricemia are known to increase the risk of mortality due to certain complications, such as Type 2 Diabetes and cardiovascular disease. However, despite their common comorbidities, their combined effect has not been evaluated. The study's aim was to evaluate the combine effect of hyperinsulinemia and hyperuricemia on all-cause mortality.

METHODS AND RESULTS

NHANES datasets (cycles 2003-2018) were examined. Differences between groups were evaluated using Rao-Scott Chi-square and General Linear Model for categorical and continuous data, respectively. Hazard Ratios (HR) were calculated using Cox regression with 95% confidence intervals (95%CI). There was significant difference (p < 0.05) in the mortality rate between the control group (2.3 ± 0.2%), the hyperinsulinemia only group (3.1 ± 0.3%), the hyperuricemia only group (4.0 ± 0.8%), and both conditions (5.1 ± 0.8%). Individually, when compared to the control group, there was a significant increase in mortality risk for hyperinsulinemia (HR: 1.50, 95%CI: 1.12-2.01, p = 0.007) and hyperuricemia (HR: 1.80, 95%CI:1.18-2.75, p = 0.006). However, when both conditions were present, there appeared an additive effect in the mortality risk (HR: 2.32, 95%CI: 1.66-3.25, p < 0.001). When stratified by BMI class, only normal weight participants presented with a significant risk (HR: 7.00, 95%CI: 2.50-20.30, p < 0.001). Also, when stratified by age, only participants older than 40 years presented a risk (HR: 2.22, 95%CI: 1.56-3.16, p < 0.001).

CONCLUSION

Alone, hyperuricemia and hyperinsulinemia significantly increased the mortality rate; however, the combined presence of both pathologies was associated with a significantly augmented mortality rate. Normal weight participant or that were >40 years old had a greater risk for mortality.

An elevated likelihood of stroke, ischemic heart disease, or heart failure in individuals with gout: a longitudinal follow-up study utilizing the National Health Information database in Korea

Objective

Accumulating evidence from other countries indicates potential associations between gout and cardiovascular diseases; however, the associations of gout with cardiovascular diseases, particularly stroke, ischemic heart disease, and heart failure, remain ambiguous in the Korean population. We hypothesized that individuals with gout are at a higher likelihood of stroke, ischemic heart disease, or heart failure. This study expands upon previous research by ensuring a comparable baseline between patient and control groups and analyzing 16 years of data derived from an extensive healthcare database.

Methods

We selected 22,480 patients with gout and 22,480 control individuals from the Korean National Health Insurance Service-Health Screening Cohort database (2002-2019), and matched them at a 1:1 ratio according to sex, age, income, and residence. A Cox proportional hazard model with weighted overlap was employed to examine the relationship between gout and the risk of stroke, ischemic heart disease, or heart failure after adjustment for several covariates.

Results

The incidences of stroke, ischemic heart disease, or heart failure in participants with gout were slightly higher than those in controls (stroke: 9.84 vs. 8.41 per 1000 person-years; ischemic heart disease: 9.77 vs. 7.15 per 1000 person-years; heart failure: 2.47 vs. 1.46 per 1000 person-years). After adjustment, the gout group had an 11% (95% confidence interval [CI] = 1.04-1.19), 28% (95% CI = 1.19-1.37), or 64% (95% CI = 1.41-1.91) higher likelihood of experiencing stroke, ischemic heart disease, or heart failure, respectively, than the control group.

Conclusion

The present findings suggest that individuals with gout in the Korean population, particularly those aged ≥ 60 years, were more likely to have stroke, ischemic heart disease, or heart failure.

Altered insulin secretion dynamics relate to oxidative stress and inflammasome activation in children with obesity and insulin resistance

BACKGROUND

Insulin resistance (IR) is considered the main driver of obesity related metabolic complications, and is related to oxidative stress and inflammation, which in turn promote each other. There is currently no specific definition of IR in children, rather, that for adult population is used by pediatric endocrinologists instead. Altered insulin secretion dynamics are associated with worse metabolic profiles and type 2 diabetes mellitus development, thus we aimed to test whether insulin response relates to oxidative stress and inflammation in children.

METHODS

We conducted a case-control study, including 132 children classified as follows: 33 children without obesity (Lean); 42 with obesity but no IR according to the American Diabetes Association criteria for adults (OBIR-); 25 with obesity and IR and an early insulin response to an oral glucose tolerance test (OGTT) (EP-OBIR +); 32 with obesity, IR, and a late insulin peak (LP-OBIR +); and studied variables associated with lipid and carbohydrate metabolism, oxidative stress, inflammation and inflammasome activation.

RESULTS

The measured parameters of children with obesity, IR, and an early insulin response were similar to those of children with obesity but without IR. It was late responders who presented an impaired antioxidant system and elevated oxidative damage in erythrocytes and plasma, and inflammasome activation at their white blood cells, despite lower classical inflammation markers. Increased uric acid levels seems to be one of the underlying mechanisms for inflammasome activation.

CONCLUSIONS

It is insulin response to an OGTT that identifies children with obesity suffering oxidative stress and inflammasome activation more specifically. Uric acid could be mediating this pathological inflammatory response by activating NLRP3 in peripheral blood mononuclear cells.

Fucoidan from Saccharina japonica Alleviates Hyperuricemia-Induced Renal Fibrosis through Inhibiting the JAK2/STAT3 Signaling Pathway

Fucoidan is a native sulfated polysaccharide mainly isolated from brown seaweed, with diverse pharmacological activities, such as anti-inflammatory and antifibrosis. Hyperuricemia (HUA) is a common metabolic disease worldwide and mainly causes hyperuricemic nephropathy, including chronic kidney disease and end-stage renal fibrosis. The present study investigated the protective function of fucoidan in renal fibrosis and its pharmacological mechanism. The renal fibrotic model was established with the administration of potassium oxonate for 10 weeks. The protein levels of related factors were assessed in HUA mice by an enzyme-linked immunosorbent assay (ELISA) and western blotting. The results showed that fucoidan significantly reduced the levels of serum uric acid, blood urea nitrogen (BUN), α-smooth muscle actin (α-SMA), and collagen I, and improved kidney pathological changes. Furthermore, renal fibrosis had been remarkably elevated through the inhibition of the epithelial-to-mesenchymal transition (EMT) progression after fucoidan intervention, suppressing the Janus kinase 2 (JAK2) signal transducer and activator of transcription protein 3 (STAT3) signaling pathway activation. Together, this study provides experimental evidence that fucoidan may protect against hyperuricemia-induced renal fibrosis via downregulation of the JAK2/STAT3 signaling pathway.

Reframing the link between metabolism and NLRP3 inflammasome: therapeutic opportunities

Inflammasomes are multiprotein signaling platforms in the cytosol that senses exogenous and endogenous danger signals and respond with the maturation and secretion of IL-1β and IL-18 and pyroptosis to induce inflammation and protect the host. The inflammasome best studied is the Nucleotide-binding oligomerization domain, leucine-rich repeat-containing family pyrin domain containing 3 (NLRP3) inflammasome. It is activated in a two-step process: the priming and the activation, leading to sensor NLRP3 oligomerization and recruitment of both adaptor ASC and executioner pro-caspase 1, which is activated by cleavage. Moreover, NLRP3 inflammasome activation is regulated by posttranslational modifications, including ubiquitination/deubiquitination, phosphorylation/dephosphorylation, acetylation/deacetylation, SUMOylation and nitrosylation, and interaction with NLPR3 protein binding partners. Moreover, the connection between it and metabolism is receiving increasing attention in this field. In this review, we present the structure, functions, activation, and regulation of NLRP3, with special emphasis on regulation by mitochondrial dysfunction-mtROS production and metabolic signals, i.e., metabolites as well as enzymes. By understanding the regulation of NLRP3 inflammasome activation, specific inhibitors can be rationally designed for the treatment and prevention of various immune- or metabolic-based diseases. Lastly, we review current NLRP3 inflammasome inhibitors and their mechanism of action.

Protease-Activated Receptor-2 and Phospholipid Metabolism Analysis in Hyperuricemia-Induced Renal Injury

Interstitial inflammation is an important mechanism of pathological damage in renal injury caused by hyperuricemia. Protease-activated receptor-2 (PAR2) is a class of targets that act upstream of the PI3K/AKT/NF-κB pathway and is involved in various inflammatory diseases. We induced a hyperuricemia model in rats by adenine and ethambutol gavage in an in vivo experiment. We demonstrated that PAR2 and PI3K/AKT/NF-κB pathway expression were significantly upregulated in renal tissues, with massive inflammatory cell infiltration in the renal interstitium and renal tissue injury. Treating hyperuricemic rats with AZ3451, a selective metabotropic antagonist of PAR2, we demonstrated that PAR2 antagonism inhibited the PI3K/AKT/NF-κB pathway and attenuated tubular dilation and tubulointerstitial inflammatory cell infiltration. The phospholipid metabolism profiles provided a perfect separation between the normal and hyperuricemic rats. In addition, we also found that AZ3451 can affect phospholipid metabolism. Our work suggests that PAR2 may mediate hyperuricemia-mediated renal injury by activating the PI3K/AKT/NF-κB pathway. The PAR2 antagonist AZ3451 may be a promising therapeutic strategy for hyperuricemia-induced inflammatory responses.

Comparison of benzbromarone and allopurinol on the risk of chronic kidney disease in people with asymptomatic hyperuricemia

OBJECTIVE

The objective of the study was to compare the relative effects of benzbromarone and allopurinol on the risk of developing chronic kidney disease in persons with asymptomatic hyperuricemia.

METHODS

A retrospective cohort study was conducted to analyze a 2003-2015 national database including all claims data of 2 million beneficiaries in Taiwan. Asymptomatic hyperuricemia was defined as follows: persons using urate-lowering drugs who never developed gout flares. The benzbromarone group included persons ages 20-84 that had asymptomatic hyperuricemia and received benzbromarone alone. The allopurinol group included persons ages 20-84 that had asymptomatic hyperuricemia and received allopurinol alone. The maximum follow-up time was set as 5 years in this study. The main outcome was defined as follows: persons were newly diagnosed with chronic kidney disease. A Cox proportional hazards regression analysis was performed to test the association between variables and the risk of chronic kidney disease.

RESULTS

After propensity score matching, 9107 persons in the benzbromarone group and 4554 persons in the allopurinol group were eligible for the study. Approximately 71% of the study subjects were males. The mean age was 56 years old. The incidence rate of chronic kidney disease was lower in the benzbromarone group than in the allopurinol group (1.18 versus 1.99/per 100 person-years, incidence ratio = 0.60, and 95% confidence interval = 0.52-0.68).The Cox proportional hazards regression analysis disclosed that after adjusting for co-variables, there was a decreased risk of developing chronic kidney disease in the benzbromarone group as compared with the allopurinol group (hazard ratio = 0.59, 95% confidence interval = 0.52-0.67 and P<0.001).

CONCLUSIONS

The use of benzbromarone is associated with a lower hazard of developing chronic kidney disease as compared to allopurinol use among persons ages 20-84 with asymptomatic hyperuricemia. More studies are needed to confirm our findings.

Gut bacterial metabolism contributes to host global purine homeostasis

The microbes and microbial pathways that influence host inflammatory disease progression remain largely undefined. Here, we show that variation in atherosclerosis burden is partially driven by gut microbiota and is associated with circulating levels of uric acid (UA) in mice and humans. We identify gut bacterial taxa spanning multiple phyla, including Bacillota, Fusobacteriota, and Pseudomonadota, that use multiple purines, including UA as carbon and energy sources anaerobically. We identify a gene cluster that encodes key steps of anaerobic purine degradation and that is widely distributed among gut-dwelling bacteria. Furthermore, we show that colonization of gnotobiotic mice with purine-degrading bacteria modulates levels of UA and other purines in the gut and systemically. Thus, gut microbes are important drivers of host global purine homeostasis and serum UA levels, and gut bacterial catabolism of purines may represent a mechanism by which gut bacteria influence health.

Association of serum uric acid with anemia in U.S. adults: a cross-sectional study using secondary data

BACKGROUND

High serum uric acid (SUA) is a risk factor of cardiovascular disease (CVD). Abnormal SUA have been correlated with a significant increase in mortality. Anemia is an independent predictor of mortality and CVD. To date, no study has investigated the relationship between SUA and anemia. Here, we explored the correlation between SUA and anemia in the American population.

METHODS

The cross-sectional study involved 9205 US adults from NHANES (2011-2014). The relationship between SUA and anemia was explored using multivariate linear regression models. Two-piecewise linear regression model, generalized additive models (GAM) and smooth curve fitting were performed to explore the non-linear relationships between SUA and anemia.

RESULTS

We found a U-shaped non-linear relationship between SUA and anemia. The inflection point of the SUA concentration curve was 6.2 mg/dL. The ORs (95% CIs) for anemia on the left and right of the inflection point were 0.86 (0.78-0.95) and 1.33 (1.16-1.52), respectively. The 95% CI of inflection point was 5.9-6.5 mg/dL. The findings showed that both genders presented a U-shaped correlation. Safe ranges of SUA in men and women were 6-6.5 and 4.3-4.6 mg/dL, respectively.

CONCLUSIONS

Both high and low SUA levels were correlated with increased risk of anemia, and a U-shaped relationship was observed between SUA and anemia.

Chloroquine inhibits NLRP3 inflammasomes activation and alleviates renal fibrosis in mouse model of hyperuricemic nephropathy with aggravation by a high-fat-diet

Numerous epidemiological studies have demonstrated that hyperuricemia (HUA) is a risk factor for renal diseases and renal fibrosis. Dietary patterns can influence serum urate levels and hyperuricemic nephropathy (HN). NLRP3 inflammasomes play a crucial role in various inflammatory responses and contribute to HN progression. Chloroquine (CQ) is an anti-inflammatory and disease-modifying anti-rheumatic drug (DMARD) utilized in treating autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. In this study, we examined the effects and underlying mechanisms of CQ in a high-fat-diet (HFD) exacerbated mouse model of HN. C57BL/6 mice were randomized into either a control group or an HN group (induced by adenine/potassium oxonate treatment), followed by a normal diet or HFD, with or without CQ treatment. Our findings revealed that the HN group exhibited elevated serum levels of blood urea nitrogen (BUN) and creatinine compared to the control group. Additionally, the HN + HFD group displayed increased serum levels of uric acid, BUN, and creatinine relative to the control + HFD group. Moreover, the HFD exacerbated renal uric acid crystal deposition and fibrosis in HN mice compared to a normal diet. CQ ameliorated renal dysfunction, as evidenced by reduced serum creatinine levels, renal fibrosis, and renal tubular injury scores, and significantly decreased NLRP3, ASC, caspase-1, and IL-1β levels in HN mice. These findings suggest that CQ inhibits the activation of NLRP3 inflammasomes and may serve as a potential therapeutic strategy for HN treatment.

Role of inflammasome in severe, steroid-resistant asthma

Purpose of review

Asthma is a common heterogeneous group of chronic inflammatory diseases with different pathological phenotypes classified based on the various clinical, physiological and immunobiological profiles of patients. Despite similar clinical symptoms, asthmatic patients may respond differently to treatment. Hence, asthma research is becoming more focused on deciphering the molecular and cellular pathways driving the different asthma endotypes. This review focuses on the role of inflammasome activation as one important mechanism reported in the pathogenesis of severe steroid resistant asthma (SSRA), a Th2-low asthma endotype. Although SSRA represents around 5-10% of asthmatic patients, it is responsible for the majority of asthma morbidity and more than 50% of asthma associated healthcare costs with clear unmet need. Therefore, deciphering the role of the inflammasome in SSRA pathogenesis, particularly in relation to neutrophil chemotaxis to the lungs, provides a novel target for therapy.

Recent findings

The literature highlighted several activators of inflammasomes that are elevated during SSRA and result in the release of proinflammatory mediators, mainly IL-1β and IL-18, through different signaling pathways. Consequently, the expression of NLRP3 and IL-1β is shown to be positively correlated with neutrophil recruitment and negatively correlated with airflow obstruction. Furthermore, exaggerated NLRP3 inflammasome/IL-1β activation is reported to be associated with glucocorticoid resistance.

Summary

In this review, we summarized the reported literature on the activators of the inflammasome during SSRA, the role of IL-1β and IL-18 in SSRA pathogenesis, and the pathways by which inflammasome activation contributes to steroid resistance. Finally, our review shed light on the different levels to target inflammasome involvement in an attempt to ameliorate the serious outcomes of SSRA.