Impact of anti-inflammatory therapies, xanthine oxidase inhibitors and other urate-lowering therapies on cardiovascular diseases in gout

Integrated in silico - in vitro strategy for the discovery of potential xanthine oxidase inhibitors from Egyptian propolis and their synergistic effect with allopurinol and febuxostat

Xanthine oxidase (XO) has been well-recognized as a validated target for the treatment of hyperuricemia and gout. Currently, there are two drugs in clinical use that shut down XO overactivity, allopurinol and febuxostat; however, detrimental side effects restrict their applications. Propolis is a unique natural adhesive biomass of structurally variable and biologically active metabolites that exert remarkable health benefits. Moreover, combination drug therapy has become a promising pharmacotherapeutic strategy directed for reformulating existing drugs into new combination entities with potentiating therapeutic impacts. In this study, computer-aided molecular docking and MD simulations accompanied by biochemical testing were used for mining novel pharmacologically active chemical entities from Egyptian propolis to combat hyperuricemia. Further, with a view to decrease the potential toxicity of synthetic drugs and enhance efficacy, propolis hits were subjected to combination analysis with each of allopurinol and febuxostat. More specifically, Glide docking was utilized for a structure-based virtual screening of in-house datasets comprising various Egyptian propolis metabolites. Rosmarinic acid, luteolin, techtochrysin and isoferulic acid were the most promising virtual hits. In vitro XO inhibitory assays demonstrated the ability of these hits to significantly inhibit XO in a dose-dependent manner. Molecular docking and MD simulations revealed a cooperative binding mode between the discovered hits and standard XO inhibitors within the active site. Subsequently, the most promising hits were tested in a fixed-ratio combination setting with allopurinol and febuxostat separately to assess their combined effects on XO catalytic inhibition. The binary combination of each techtochrysin and rosmarinic acid with febuxostat displayed maximal synergy at lower effect levels. In contrast, individually, techtochrysin and rosmarinic acid with allopurinol cooperated synergistically at high dose levels. Taken together, the suggested strategy seems imperative to ensure a steady supply of new therapeutic options sourced from Egyptian propolis to regress the development of hyperuricemia.

Electrochemical strategy with zeolitic imidazolate framework-8 and ordered mesoporous carbon for detection of xanthine

An accurate, safe, environmentally friendly, fast and sensitive electrochemical biosensors were developed to detect xanthine in serum. The metal-organic framework ZIF-8 was synthesised and elemental gold was supported on the surface of ZIF-8 by reduction method to synthesise Ag-ZIF-8. The mesoporous carbon material and the synthesised Ag-ZIF-8 were, respectively, applied to a glassy carbon electrode to construct biosensors. The constructed biosensor has a good linear relation in the range of 1-280 μmol l^-1 of xanthine and the detection limit is 0.167 μmol l^-1. The relative standard deviation value in serum samples was <5%, and the recoveries were 96-106%, indicating the good selectivity, stability and reproducibility of this electrochemical biosensor.

Monosodium urate crystal interleukin-1β release is dependent on Toll-like receptor 4 and transient receptor potential V1 activation

OBJECTIVE

The present study aimed to elucidate the mechanisms involved in MSU-induced IL-1β release in a rodent animal model of acute gout arthritis.

METHODS

Painful (mechanical and thermal hypersensitivity, ongoing pain and arthritis score) and inflammatory (oedema, plasma extravasation, cell infiltration and IL-1β release) parameters were assessed several hours after intra-articular injection of MSU (100 µg/articulation) in wild-type or knockout mice for Toll-like receptor 4 (TLR4), inducible nitric oxide synthase (iNOS), transient receptor potential (TRP) V1 and the IL-1 receptor (IL-1R). Also, wild-type animals were treated with clodronate, lipopolysaccharide from Rhodobacter sphaeroides (LPS-RS) (TLR4 antagonist), spleen tyrosine kinase (SYK) inhibitor (iSYK), aminoguanidine (AMG, an iNOS inhibitor) or SB366791 (TRPV1 antagonist). Nitrite/nitrate and IL-1β levels were measured on the synovial fluid of wild-type mice, 2 h after intra-articular MSU injections, or medium from macrophages stimulated for MSU (1000 μg) for 2 h.

RESULTS

Intra-articular MSU injection caused robust nociception and severe inflammation from 2 up to 6 h after injection, which were prevented by the pre-treatment with clodronate, LPS-RS, iSYK, AMG and SB366791, or the genetic ablation of TLR4, iNOS, TRPV1 or IL-1R. MSU also increased nitrite/nitrate and IL-1β levels in the synovial fluid, which was prevented by clodronate, LPS-RS, iSYK and AMG, but not by SB366791. Similarly, MSU-stimulated peritoneal macrophages released nitric oxide, which was prevented by LPS-RS, iSYK and AMG, but not by SB366791, and released IL-1β, which was prevented by LPS-RS, iSYK, AMG and SB366791.

CONCLUSION

Our data indicate that MSU may activate TLR4, SYK, iNOS and TRPV1 to induce the release of IL-1β by macrophages, triggering nociception and inflammation during acute gout attack.

Association of Gout With Long-Term Cardiovascular Outcomes Among Patients With Obstructive Coronary Artery Disease

Background Epidemiological studies demonstrating a relationship between gout and cardiovascular disease are older and predate modern cardiovascular preventive therapy. We assessed the contemporary association between gout and cardiovascular disease in patients with obstructive coronary artery disease. Methods and Results Data were from the Duke Databank for Cardiovascular Diseases, which followed up patients undergoing cardiac catheterization with obstructive coronary artery disease at Duke University Medical Center (1998-2013). We assessed the relationship between gout diagnosis at baseline or during follow-up and the primary composite outcome of cardiovascular death, myocardial infarction, or stroke, adjusting for differences in baseline clinical factors. Secondary end points included cardiovascular death and all-cause mortality. New, postbaseline, gout diagnosis was included as a time-dependent covariate. Among 17 201 patients, 1406 (8.2%) had baseline gout and a high burden of cardiovascular risk factors, but high rates of optimal medical therapy. Over a median follow-up of 6.4 years, gout diagnosis at time of catheterization was not associated with the primary outcome (hazard ratio [95% confidence interval], 1.05 [0.96-1.15]; P=0.31) or cardiovascular death (hazard ratio [95% confidence interval], 1.10 [0.99-1.22]; P=0.08), but was associated with increased all-cause mortality (hazard ratio [95% confidence interval], 1.13 [1.05-1.23]; P=0.002). After including new, postbaseline, gout diagnosis, the instantaneous risk of the primary outcome was significantly associated with prior gout diagnosis (hazard ratio [95% confidence interval], 1.15 [1.07-1.25]; P=0.0004). Conclusions A clinical history of gout is associated with worse outcomes in a contemporary population of patients with obstructive coronary artery disease. This increased risk exists despite high levels of optimal baseline cardiovascular disease medical therapy, suggesting that residual cardiovascular risk is not addressed by standard medical therapy.

Ozonated autohemotherapy modulates the serum levels of inflammatory cytokines in gouty patients

Objectives

Ozonated autohemotherapy (O3-AHT) has been used to effectively treat gout, but the underlying therapeutic mechanisms remain unknown. In this study, as an initial effort to understand the therapeutic mechanisms of O3-AHT, we aim to examine the effect of O3-AHT on serum inflammatory cytokine levels in gouty patients.

Patients and methods

Three groups of patients and healthy subjects were recruited, including the gouty (n=10), hyperuricemia (n=10), and healthy control (n=11) groups. Cytometric bead array was applied to examine 12 cytokines before (T0), during (T1), and after (T2) therapies.

Results

Three cytokines, IL-8, IL-12, and MCP-1, were detectable in all participants. Before O3-AHT, the average serum levels of IL-8 and MCP-1 were higher in the gout group than in the hyperuricemia and healthy control groups, confirming the inflammation status in gouty patients. After the 5th course of O3-AHT (T1), IL-8 level was significantly increased compared to that at T0. IL-12 level was also raised at T1, although the difference did not reach statistical significance. After completing the therapy, both IL-8 and IL-12 levels decreased to levels lower than those at T0. MCP-1 level remained essentially unchanged during and after treatment.

Conclusion

Our results indicate that O3-AHT induces a significant change in serum cytokine levels, suggesting that modulating the inflammatory process is one of the therapeutic mechanisms underlying O3-AHT. In addition, the sensitive response of serum IL-8 and IL-12 levels to O3-AHT suggests that these cytokines may be developed as biomarkers to evaluate the therapeutic effect of O3-AHT in gouty patients.