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.

The dysregulation of immune cells induced by uric acid: mechanisms of inflammation associated with hyperuricemia and its complications

Changes in lifestyle induce an increase in patients with hyperuricemia (HUA), leading to gout, gouty arthritis, renal damage, and cardiovascular injury. There is a strong inflammatory response in the process of HUA, while dysregulation of immune cells, including monocytes, macrophages, and T cells, plays a crucial role in the inflammatory response. Recent studies have indicated that urate has a direct impact on immune cell populations, changes in cytokine expression, modifications in chemotaxis and differentiation, and the provocation of immune cells by intrinsic cells to cause the aforementioned conditions. Here we conducted a detailed review of the relationship among uric acid, immune response, and inflammatory status in hyperuricemia and its complications, providing new therapeutic targets and strategies.

Efficacy and safety of a selective URAT1 inhibitor SHR4640 in Chinese subjects with hyperuricemia: a randomized controlled phase II study

OBJECTIVES

To evaluate the efficacy and safety of SHR4640, a highly selective urate transporter 1 inhibitor in Chinese subjects with hyperuricemia.

METHODS

This was a randomized double-blind dose-ranging phase II study. Subjects whose serum uric acid levels ≥480 µmol/l with gout, or sUA levels ≥480 µmol/l without gout but with comorbidities, or sUA levels ≥540 µmol/l were enrolled. Subjects were randomly assigned (1:1:1:1:1) to receive once daily 2.5 mg/5 mg/10 mg of SHR4640, 50 mg of benzbromarone, and placebo, respectively. The primary end point was the proportion of subjects achieved target sUA level of ≤ 360 µmol/l at week 5.

RESULTS

About 99.5% of subjects (n = 197) were male and 95.9% of subjects had gout history. The proportions of subjects achieved target sUA at week 5 were 32.5%, 72.5% and 61.5% in 5 mg, 10 mg of SHR4640 and benzbromarone groups, respectively, significantly higher than placebo group (0%; p< 0.05 for 5 mg and 10 mg of SHR4640 group). The sUA was reduced by 32.7%, 46.8% and 41.8% at week 5 with 5 mg, 10 mg of SHR4640 and benzbromarone, respectively, vs placebo (5.9%; p< 0.001 for each comparison). The incidences of gout flares requiring intervention were similar among all groups. Occurrences of treatment-emergent adverse events (TEAEs) were comparable across all groups, and serious TEAEs were not reported.

CONCLUSIONS

The present study indicated a superior sUA-lowering effect, and well tolerated safety profile after 5-week treatment with once-daily 5 mg/10 mg of SHR4640 as comparing with placebo in Chinese subjects with hyperuricemia.

TRIAL REGISTRATION

ClinicalTrials.gov number, NCT03185793.

Predictors of reaching a serum uric acid goal in patients with gout and treated with febuxostat

Purpose

Clinical guidelines recommend febuxostat as first-line pharmacologic urate-lowering therapy for patients with gout to achieve a goal serum uric acid (sUA) <6 mg/dL; however, little is known about other contributing factors. This study identified clinical characteristics of patients treated with febuxostat to develop and validate a predictive model for achieving a goal sUA.

Patients and methods

Patients with Humana Medicare or commercial insurance, diagnosed with gout and newly initiated on febuxostat (index date February 1, 2009 – December 31, 2013), were identified for a retrospective cohort study. Patients were followed for 365 days and the first valid sUA test result ≥120 days after index was retained. A stepwise logistic regression with backward elimination was estimated to model sUA goal attainment, and a linear model was estimated to model the impact of predictor variables on sUA level.

Results

The study sample (n=678) was divided into a development (training) dataset (n=453) and a validation (holdout) dataset (n=225). In the training sample, patients in the sUA <6 mg/dL group were on febuxostat for a longer time, were more adherent, and had a lower average base-line sUA level (all p<0.0001) vs patients in the sUA ≥6 mg/dL group. In the logistic model, febuxostat adherence (odds ratio [OR]=1.03, p<0.0001) and baseline sUA level (OR=0.84, p<0.0001) increased the odds of attaining sUA <6 mg/dL. In the linear regression model, increase in febuxostat adherence (p<0.0001), baseline sUA level (p<0.0001), advanced age (p=0.0021), and not having congestive heart failure (p<0.05) were associated with a reduction of sUA level. Pre-index allopurinol use was a marginally significant predictor of sUA level reduction (p=0.06).

Conclusions

Among febuxostat users diagnosed with gout in a real-world setting, adherence to febuxostat and lower baseline sUA level were the strongest predictors of attaining sUA goal. These findings may help clinicians to identify appropriate patients most likely to benefit from febuxostat treatment, and underscore the importance of medication adherence in this challenging patient population.

Bariatric surgery in severely obese adolescents improves major comorbidities including hyperuricemia

OBJECTIVE

Serum uric acid (sUA) is believed to contribute to the pathogenesis of metabolic comorbidities like hypertension, insulin-resistance (IR) and endothelial dysfunction (EDF) in obese children. The present pilot study investigated the association between sUA concentrations and loss of body weight following laparoscopic sleeve gastrectomy (LSG) or laparoscopic Roux-en-Y-gastric bypass (RYGB) in severely obese adolescents.

MATERIALS/METHODS

10 severely obese adolescents underwent either LSG (n=5) or RYGB (n=5). 17 normal weight, healthy, age- and gender-matched adolescents served as a normal weight peer group (NWPG). Pre- and 12 months postoperatively, sUA and relevant metabolic parameters (glucose homeostasis, transaminases, lipids) were compared.

RESULTS

Preoperatively, sUA was significantly elevated in patients with severe obesity compared to NWPG. Twelve months after LSG and RYGB, a significant decrease in sUA, BMI, CVD risk factors, hepatic transaminases, and HOMA-IR was observed. Reduction in SDS-BMI significantly correlated with changes in sUA.

CONCLUSIONS

sUA levels and metabolic comorbidities improved following bariatric surgery in severely obese adolescents. The impact of changes in sUA on long-term clinical complications of childhood obesity deserves further study.