Innate immunity in triggering and resolution of acute gouty inflammation

New Inflammatory Marker Associated with Disease Activity in Gouty Arthritis: The Systemic Inflammatory Response Index

Background

The systemic immune-inflammatory index (SII) and systemic inflammatory response index (SIRI), as novel non-specific inflammatory markers, have recently drawn attention. At present, no studies have been conducted to investigate the value of SII and SIRI in gouty arthritis (GA), so we explored their possible association with GA disease activity.

Methods

The study enrolled 474 patients with acute gouty arthritis (AG), 399 patients with intercritical gouty arthritis (IG) and 194 healthy controls (HC). The differences in Monocyte-to-lymphocyte ratio (MLR), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), SII, and SIRI levels among different groups were assessed. The changes in the above indicators before and after treatment in the AG and IG groups were evaluated. Multivariate logistic regression analysis was assessed influencing factors for the acute gout attack. ROC curves were plotted to evaluate their diagnostic value for AG.

Results

Compared with the IG group, the erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), PLR, and incidence of hyperlipidemia in the AG group were significantly higher, and the duration of disease was significantly shorter (P < 0.05). The MLR, NLR, SII and SIRI in the AG group were significantly higher than those in the IG and HC groups (P < 0.05). Compared with baseline, decreased MLR, NLR, PLR, SII and SIRI were observed in the AG group after treatment (P < 0.05), while there was no significant difference in the IG group before and after treatment (P > 0.05). SIRI was positively correlated with ESR and CRP (P < 0.05). Multivariate logistic regression analysis result showed that duration of disease, hyperlipidemia, ESR, CRP, and SIRI were influencing factors of acute gout attack (P < 0.05). The AUC of ESR, CRP and SIRI on the diagnosis in AG were 0.664, 0.755, and 0.674, respectively.

Conclusion

SIRI may be used as a new inflammatory marker of disease activity with gouty arthritis.

Clinical and immunologic differences in cellulitis vs. pseudocellulitis

Introduction: The immunologic mechanisms between cellulitis and pseudocellulitis differ greatly, even though their clinical presentations may overlap.Areas covered: This article discusses cellulitis and common entities within the pseudocellulitis spectrum including acute lymphedema, superficial venous thrombosis, allergic contact dermatitis, lipodermatosclerosis, stasis dermatitis, erythema nodosum, cutaneous gout, and bursitis. The literature search was conducted from PubMed search engine between March and May 2021.Expert commentary: While immunologic differences in cellulitis and the various entities of pseudocellulitis are clear, there is a practice gap in applying these differences to the clinic and hospital setting. Further, existing studies are weakened by the lack of a gold-standard diagnosis in this disease category. Additional work is necessary in developing a gold-standard for the diagnosis and secondly, to project these immunologic differences as biomarkers to differentiate sterile inflammation from a potential life threatening bacterial or fungal infection.

Simiao Wan attenuates monosodium urate crystal-induced arthritis in rats through contributing to macrophage M2 polarization

ETHNOPHARMACOLOGICAL RELEVANCE

Simiao Wan (SMW) is a classical traditional Chinese medicine (TCM) prescription to empirically treat gouty arthritis (GA) in TCM clinical practice. However, the potential mechanisms of SMW on GA are not fully evaluated.

AIM OF STUDY

The aim of this study is to investigate the role of macrophage polarization in the anti-GA activity of SMW.

MATERIALS AND METHODS

Rats were intragastricly treated with SMW for consecutive 7 days. On day 6, monosodium urate (MSU) crystal-induced arthritis (MIA) in the ankle joint was prepared. Paw volume, gait score and histological score were measured. Levels of interleukin (IL)-1β and IL-10 in serum were detected by enzyme-linked immunosorbent assay. Expressions of inducible nitric oxide synthase (iNOS), arginase (Arg)-1, phosphorylated (p)-p65, inhibitor of nuclear factor (NF)-κB (IκB)α, p-signal transducer and transcription activator (STAT)3 and p-Janus kinase (JAK)2 in synovial tissues were determined by Western blot.

RESULTS

The elevated paw volume, gait score and histological score in MIA rats were significantly decreased by SMW treatment. Meanwhile, SMW significantly decreased the IL-1β level and increased the IL-10 level in serum of MIA rats. Furthermore, SMW reduced the expressions of iNOS, p-p65 and enhanced the expressions of Arg-1, IκBα, p-STAT3 and p-JAK2 in synovial tissues of MIA rats.

CONCLUSIONS

The results suggest that SMW attenuates the inflammation in MIA rats through promoting macrophage M2 polarization.

Annexin A1 promotes timely resolution of inflammation in murine gout

Gout is a self-limited inflammatory disease caused by deposition of monosodium urate (MSU) crystals in the joints. Resolution of inflammation is an active process leading to restoration of tissue homeostasis. Here, we studied the role of Annexin A1 (AnxA1), a glucocorticoid-regulated protein that has anti-inflammatory and proresolving actions, in resolution of acute gouty inflammation. Injection of MSU crystals in the knee joint of mice induced inflammation that was associated with expression of AnxA1 during the resolving phase of inflammation. Neutralization of AnxA1 with antiserum or blockade of its receptor with BOC-1 (nonselective) or WRW₄ (selective) prevented the spontaneous resolution of gout. There was greater neutrophil infiltration after challenge with MSU crystals in AnxA1 knockout mice (AnxA1^-/- ) and delayed resolution associated to decreased neutrophil apoptosis and efferocytosis. Pretreatment of mice with AnxA1-active N-terminal peptide (Ac_2-26 ) decreased neutrophil influx, IL-1β, and CXCL1 production in periarticular joint. Posttreatment with Ac_2-26 decreased neutrophil accumulation, IL-1β, and hypernociception, and improved the articular histopathological score. Importantly, the therapeutic effects of Ac_2-26 were associated with increased neutrophils apoptosis and shortened resolution intervals. In conclusion, AnxA1 plays a crucial role in the context of acute gouty inflammation by promoting timely resolution of inflammation.

Effects of Berberine on NLRP3 and IL-1β Expressions in Monocytic THP-1 Cells with Monosodium Urate Crystals-Induced Inflammation

Background. Urate crystals-induced inflammation is a critical factor during the initiation of gouty arthritis. Berberine is well known for its anti-inflammatory activity. However, the underlying effects of berberine on monosodium urate crystals-induced inflammation remain obscure. Objectives. This study is set to explore the protective effect and mechanism of berberine on monosodium urate crystals-induced inflammation in human monocytic THP-1 cells. Methods. The mRNA levels of NLRP3 and IL-1β were measured by Real-Time PCR, and the protein levels of NLRP3 and IL-1β were determined by ELISA, Western blot, and immunofluorescence. Results. The NLRP3 and IL-1β expressions were significantly increased in model group compared to that in normal group (P < 0.05). Meanwhile, there was significant reduction in the expressions of NLRP3 and IL-1β mRNA in groups 6.25 μM berberine and 25 μM berberine when compared with model group (P < 0.05). Conclusions. Therefore, berberine alleviates monosodium urate crystals-induced inflammation by downregulating NLRP3 and IL-1β expressions. The regulatory effects of berberine may be related to the inactivation of NLRP3 inflammasome.

New and improved strategies for the treatment of gout

The Western world appears to be in the midst of the third great gout epidemic of all time. In this century, gout is increasing in prevalence despite an increased understanding of its risk factors and pathophysiology, and the availability of reasonably effective treatment. The main cultural factors responsible for this appear to be diet, obesity, ethanol use and medications. Excess fructose consumption is a newly recognized modifiable risk factor. The debate has been renewed concerning hyperuricemia as an independent risk factor for renal insufficiency and cardiovascular disease. Prevention is still rooted in lifestyle choices. Existing treatments have proven to be unsatisfactory in many patients with comorbidities. New treatments are available today and on the horizon for tomorrow, which offer a better quality of life for gout sufferers. These include febuxostat, a nonpurine inhibitor of xanthine oxidase with a potentially better combination of efficacy and safety than allopurinol, and investigational inhibitors of URAT-1, an anion exchanger in the proximal tubule that is critical for uric acid homeostasis. New abortive treatments include interleukin-1 antagonists that can cut short the acute attack in 1 to 2 days in persons who cannot take nonsteroidal anti-inflammatory drugs, colchicine or corticosteroids. Lastly, newer formulations of uricase have the ability to dissolve destructive tophi over weeks or months in patients who cannot use currently available hypouricemic agents. Diagnostically, ultrasound and magnetic resonance imaging offer advanced ways to diagnose gout noninvasively, and just as importantly, a way to follow the progress of tophus dissolution. The close association of hyperuricemia with metabolic syndrome, hypertension and renal insufficiency ensures that nephrologists will see increasing numbers of gout-afflicted patients.

Intracellular innate immunity in gouty arthritis: role of NALP3 inflammasome

Gout is an inflammatory disease caused by the deposition of monosodium urate (MSU) crystals in the joint. Recent studies have significantly advanced our knowledge on the understanding of mechanisms underlying MSU crystal-induced inflammation. MSU crystals act as a 'danger signal' that can be recognized by pattern recognition receptors both at cell surface and cytoplasm, indicating the importance of innate immunity in gout. This review focuses on the critical role of intracellular NALP3 inflammasome in MSU crystal-induced inflammation.

Gout--current diagnosis and treatment

BACKGROUND

Because of the changing dietary habits of an aging population, hyperuricemia is frequently found in combination with other metabolic disorders. Longstanding elevation of the serum uric acid level can lead to the deposition of monosodium urate crystals, causing gout (arthritis, urate nephropathy, tophi). In Germany, the prevalence of gouty arthritis is estimated at 1.4%, higher than that of rheumatoid arthritis. There are no German guidelines to date for the treatment of gout. Its current treatment is based largely on expert opinion.

METHODS

Selective literature review on the diagnosis and treatment of gout.

RESULTS AND CONCLUSIONS

Asymptomatic hyperuricemia is generally not an indication for pharmacological intervention to lower the uric acid level. When gout is clinically manifest, however, acute treatment of gouty arthritis should be followed by determination of the cause of hyperuricemia, and long-term treatment to lower the uric acid level is usually necessary. The goal of treatment is to diminish the body's stores of uric acid crystal deposits (the intrinsic uric acid pool) and thereby to prevent the inflammatory processes that they cause, which lead to structural alterations. In the long term, serum uric acid levels should be kept below 360 micromol/L (6 mg/dL). The available medications for this purpose are allopurinol and various uricosuric agents, e.g., benzbromarone. There is good evidence to support the treatment of gouty attacks by the timely, short-term use of non-steroidal anti-inflammatory drugs (NSAID), colchicine, and glucocorticosteroids.

Recent developments in crystal-induced inflammation pathogenesis and management

Crystal-induced inflammation pathogenesis is undergoing a transition with respect to monosodium urate, calcium pyrophosphate dihydrate, and even basic calcium phosphate crystals. It is now recognized that innate immunity could be involved in the earlier pathogenic events and that the inflammasome, along with other signaling pathways, is activated and results in interleukin-1 processing and secretion, ultimately activating cells as a paracrine or autocrine cytokine. Management of acute and chronic monosodium urate crystal-induced inflammation, namely gout, has been critically reviewed by a dedicated European working group, and on the behalf of the European League against Rheumatism, 12 evidence-based recommendations have been reported. Calcium pyrophosphate dihydrate chronic inflammation could benefit from colchicine and from methotrexate as an anti-inflammatory agent.