MSU Crystals

Inflammasome activation with MSU crystals

NLRP3 inflammasome Inducer - Monosodium Urate Crystals - 

Monosodium urate (MSU) or uric acid is the aetiological agent of the acute inflammatory condition gout [1]. Notably, research has demonstrated that MSU crystals induce the release of interleukin (IL)-1β in response to the activation of the NLRP3 (also known as NALP3 or cryopyrin) inflammasome [1, 2]. The NLRP3 inflammasome is an intracellular multi-protein complex that plays a central role in innate immunity.

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Mode of action:

MSU crystals can act as endogenous danger signals that stimulate the innate immune system to produce inflammatory cytokines such as IL-1β [1]. MSU crystals were shown to activate caspase-1, which is required for IL-1β maturation, through the NRLP3 (NALP3) inflammasome [2]. The NLRP3 inflammasome is a caspase-1-activating complex comprising the NLR protein NLRP3 and the adaptor ASC [2]. Involvement of the inflammasome is suggested by the finding that macrophages from mice deficient in various components of the inflammasome are defective in crystal-induced IL-1β induction [1].

Key features of MSU crystals:

• Potent inducer of the NLRP3 inflammasome
• Each lot is functionally tested

Read our review on the NLRP3 inflammasome.

Download our Practical guide on Inflammasomes.

References:

1. Martinon F. et al., 2006. Gout-associated uric acid crystals activate the NALP3 inflammasome. Nature. 440(7081):237-41.
2. Martinon F, & Tschopp J., 2004. Inflammatory caspases: linking an intracellular innate immune system to autoinflammatory diseases. Cell. 117(5):561-74.

Figures

IL-1β production in THP1-HMGB1-Lucia™ cells. Cells were primed with 1 μg/ml LPS‑EK for 3h and then incubated with inflammasome inducers; 8 μM Nigericin, 0.5 μg/ml complexed Poly(dA:dT), 200 μg/ml MSU Crystals, 100 μg/ml CPPD Crystals, or 1 mg/ml Zymosan. After 24h, supernatants were incubated with HEK-Blue™ IL-1β cells overnight and SEAP activity was assessed using QUANTI-Blue™ Solution. The optical density (OD) was read at 630 nm. Data are shown as a fold increase (mean ± SEM) over non-induced cells.

Specifications

Working concentration: 100 - 200 µg/ml

CAS number: 1198-77-2

Linear formula: C₅H₃N₄NaO₃

Molecular weight: 190.1 g/mol

Structure: Triclinic crystals characterized by X-ray diffraction

Solubility: Not soluble

Contents

Monosodium urate (MSU) crystals are available in two quantities:

• 5 mg: tlrl-msu
• 25 mg: tlrl-msu-25

MSU crystals are shipped at room temperature.

Store at 4 °C for 1 year.

Details

THP-1/HEK-Blue™ IL-1β Assay

MSU crystals can be used to induce the NLRP3 inflammasome in cellular assays, such as InvivoGen’s THP1/HEK-Blue™ IL-1β assay. This assay uses the secretion of IL-1β by THP1-Null2 cells as an indicator of NLRP3 inflammasome induction. The production of IL-1β by these cells is measured using HEK-Blue™ IL-1β cells.

1- Production of IL-1β by THP-1 cells: Typically, THP1-Null2 cells are primed with lipopolysaccharide (LPS). This treatment induces the production of NLRP3 and pro-IL-1β, the immature form of IL-1β. Subsequent stimulation with inflammasome inducers, such as MSU crystals, leads to NRLP3 and caspase-1 activation resulting in IL-1β maturation and secretion.

2- Detection of IL-1β by HEK-Blue™ IL-1β cells: THP1-Null2 cell supernatants containing IL-1β can be added to HEK-Blue™ IL-1β cells. This activates NF-κB and leads to the subsequent production of secreted embryonic alkaline phosphatase (SEAP). The presence of SEAP in HEK-Blue™ IL-1β supernatants is assessed using QUANTI-Blue™ Solution, a SEAP detection medium.