Monosodium urate-crystal-stimulated phospholipase D in human neutrophils

Protein kinase Cα (PKCα) and small GTPases of the Rho and ADP-ribosylation factor (Arf) family are implicated in the regulation of phospholipase D1 (PLD1) activity. Although they are involved in fMet-Leu-Phe (fMLP)-mediated PLD activation, their role in monosodium urate (MSU)-stimulated PLD1 activity in human neutrophils is not clear. The translocation of PKCα, RhoA and Arf from the cytosol to the membranes was monitored. fMLP induced a cytochalasin B (CB)-dependent recruitment of Arf, RhoA and PKCα to neutrophil membranes. CB also increased the activation of PLD 10-fold. In contrast with fMLP, MSU stimulated a sustained and time-dependent relocalization of Arf and PKCα, but not of RhoA, to the membrane fraction. MSU-stimulated PLD was activated with a time course preceding membrane recruitment of Arf and PKCα in the absence of CB. Furthermore, MSU-induced PLD activation and the membrane recruitment of PKCα, but not that of Arf, were inhibited by CB. An anti-FcγRIIIB antibody, VIFcRIII, prevented the membrane relocalization of Arf and PKCα and the stimulation of the levels of tyrosine phosphorylation and of PLD activity induced by MSU. Erbstatin and ST-638, two inhibitors of tyrosine kinases, inhibited the MSU-induced translocation of Arf and PKCα but not MSU-induced tyrosine phosphorylation and PLD activation. Furthermore MSU crystals did not cause the tyrosine phosphorylation of PLD1. The present study indicates that soluble and particulate agonists show selectivity in inducing the translocation of RhoA in neutrophils and that the ability of MSU to increase PLD activation was independent of the membrane relocalization of Arf and PKCα.

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Faculty Opinions recommendation of Interleukin 37 limits monosodium urate crystal-induced innate immune responses in human and murine models of gout.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.726996092.793525670 ◽

2016 ◽

Author(s):

Frédéric Lioté

Keyword(s):

Immune Responses ◽

Innate Immune ◽

Murine Models ◽

Innate Immune Responses ◽

Monosodium Urate ◽

Urate Crystal

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POS0132 IS THE INTERCRITICAL GOUT REALLY ASYMPTOMATIC? THE INFLAMMATORY ROLE OF THE SILENT URATE CRYSTAL DEPOSITION

Annals of the Rheumatic Diseases ◽

10.1136/annrheumdis-2021-eular.1478 ◽

2021 ◽

Vol 80 (Suppl 1) ◽

pp. 277.1-278

Author(s):

C. Diaz-Torne ◽

M. A. Ortiz ◽

S. Jeria Navarro ◽

A. Garcia-Gullien ◽

L. Sainz ◽

...

Keyword(s):

Risk Factors ◽

Whole Body ◽

Subclinical Inflammation ◽

Monosodium Urate ◽

Crystal Deposition ◽

Secretome Analysis ◽

Healthy Donors ◽

Cytokine Levels ◽

Urate Crystal ◽

Crystal Deposit

Background:Gout is the most prevalent inflammatory arthritis. Gout is chronic inflammatory deposition disease related to an increase of cardiovascular (CV) events and mortality. Subclinical chronic inflammation has been demonstrated in this patients but not its relation with the monosodium urate (MSU) crystal deposit size and the number of CV risk factors.Objectives:To study the subclinical inflammation in intercritical gout patients and its possible relation to the estimated size of the crystal deposition and the number of CV risk factors.Methods:To analyze subclinical inflammation we performed a secretome analysis and a cytokine and adiponektine plasma levels quantification (IL-1β, IL-18, IL-6, sIL-6R, TNFα, CXCL-5, RANTES, leptin, resistin and adiponectin) in a cohort of gout patients. As nowadays it is not feasible to determinate the whole body deposit of MSU crystals we created three different MSU crystal deposit size patient groups using an indirect clinical and analytical classification to estimate it. Then we compared cytokine levels between healthy donors and gout patients. We also compared cytokine levels between the different crystal size deposition groups and studied its association to the number of CV risk factors.Results:Ninety consecutive patients attending a Crystal Arthritis Unit were studied. Mean age was 68.27 (28-101) years. 81.1% were male. Clinical gout evolution was of 10.1±9.8 years. 77.5% were on urate lowering treatment. 24% had tophaceous gout. Mean uric acid was 6.3±2.1 mg/dl with 47.1% of them being on target. Hypertension was present in 68.9%, diabetes mellitus in 18.9%, dislipemia in 48.9%, BMI>30 in 32.9%, abdominal obesity in 50% and 16.1% suffered from ischemic heart disease. From the 102 molecules studied in the secretome analysis in 56 there was at least a 20% difference between donors group and any of the deposition groups. In 74% of them gout patients secreted lower levels. IL-18, sIL-6R, RANTES, leptin and adiponectin were higher in patients than in healthy donors. IL-18, sIL6-R, RANTES and CXCL5 levels were associated to the size of the crystal deposits. IL-18, sIL-6R, RANTES and leptin were higher in gout groups with CV risk factors. IL-18, sIL6-R, RANTES and leptin were higher in gout patients with no risk factors when compared to healthy donors with no risk factors. We found no differences when comparing urate lowering treated and non-treated patients.Conclusion:Our results demonstrate that some proinflammatory cytokines and metabolic proteins are raised in intercritical gout patients. Some of them are different from the flare/inflammasome expected ones. In some cytokines this elevation is related to the size of the monosodium urate crystal deposit and/or to the number of cardiovascular risk factors. This cytokine changes could help to explain the increase of the cardiovascular events in gout patients.Disclosure of Interests:Cesar Diaz-Torne Grant/research support from: Received a grant from Grünenthal, Maria Angels Ortiz: None declared, Sicylle Jeria Navarro: None declared, Andrea Garcia-Gullien: None declared, Lluis Sainz: None declared, Hector Corominas: None declared, Silvia Vidal: None declared

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