MCC950 Sodium: Selective NLRP3 Inflammasome Inhibition in Macrophages & Disease Models

Executive Summary: MCC950 sodium (CAS 256373-96-3) is a highly selective small-molecule inhibitor of the NLRP3 inflammasome, with an IC50 of 7.5 nM in murine bone marrow-derived macrophages under standard culture conditions (Yuan et al., 2022). It blocks both canonical and noncanonical NLRP3 activation pathways, sparing other inflammasomes such as AIM2, NLRC4, and NLRP1 (APExBIO). MCC950 sodium demonstrates high aqueous and organic solubility (≥124 mg/mL water, ≥21.45 mg/mL DMSO, ≥43 mg/mL ethanol), facilitating experimental integration. It dose-dependently inhibits IL-1β release in macrophage and mononuclear cell assays without affecting TNF-α secretion, confirming pathway specificity. In vivo, MCC950 sodium reduces serum IL-1β and IL-6 after LPS challenge and attenuates experimental autoimmune encephalomyelitis, modeling multiple sclerosis pathogenesis (Mouse IFN-α).

Biological Rationale

The NLRP3 inflammasome is a cytosolic multiprotein complex that senses cellular danger signals and triggers caspase-1 activation, leading to pyroptosis and IL-1β/IL-18 secretion. Dysregulation of NLRP3 is implicated in a spectrum of inflammatory and autoimmune diseases, including atherosclerosis, multiple sclerosis, and type 2 diabetes (Yuan et al., 2022). Macrophages and mononuclear cells are principal effectors in this pathway, mediating tissue inflammation and injury. Targeted inhibition of NLRP3 allows researchers to dissect disease mechanisms and evaluate therapeutic strategies. MCC950 sodium, also known as CRID3 sodium salt, offers nanomolar potency and high selectivity for NLRP3, making it an essential reagent for dissecting inflammasome biology (Mouse IFN-α article). This article extends previous coverage by offering a granular, citation-backed analysis of MCC950 sodium's mechanism and experimental benchmarks.

Mechanism of Action of MCC950 sodium

MCC950 sodium directly inhibits NLRP3 ATPase activity, preventing conformational changes required for inflammasome assembly (APExBIO). It interrupts both canonical activation (triggered by ATP, nigericin, or microbial toxins) and noncanonical pathways (caspase-11 mediated in mice, caspase-4/5 in humans). In cell-based assays, MCC950 sodium blocks NLRP3-mediated caspase-1 cleavage and downstream IL-1β/IL-18 maturation, but does not interfere with AIM2, NLRC4, or NLRP1 inflammasome function. The compound achieves this selectivity without impacting TNF-α secretion, indicating minimal off-target immunosuppression (Interleukin-II article). Compared to broad-spectrum inflammasome inhibitors or genetic knockouts, MCC950 sodium offers rapid, reversible pathway modulation and superior translational potential. This mechanistic specificity is further clarified in recent analytical reviews.

Evidence & Benchmarks

• MCC950 sodium inhibits NLRP3 activation in murine bone marrow-derived macrophages with IC50 = 7.5 nM (RPMI-1640, 10% FBS, 37 °C, 5% CO2) (Yuan et al., 2022).
• Comparable inhibitory potency is observed in human monocyte-derived macrophages (IC50 in low nanomolar range; same culture conditions) (APExBIO).
• MCC950 sodium blocks both canonical (e.g., ATP/nigericin) and noncanonical (e.g., caspase-11) NLRP3 activation, but not AIM2/NLRC4/NLRP1 inflammasomes (Yuan et al., 2022).
• Dose-dependent suppression of IL-1β secretion is confirmed in BMDMs, HMDMs, and human PBMCs, without significant effect on TNF-α release (LPS, 1 μg/mL, 3 h) (APExBIO).
• In vivo, intraperitoneal administration reduces serum IL-1β and IL-6 after LPS challenge (mice, 10 mg/kg, 2 h post-LPS) and mitigates EAE disease severity (autoimmune model) (AVL-301 article).
• Highly soluble in water (≥124 mg/mL), DMSO (≥21.45 mg/mL), and ethanol (≥43 mg/mL), with recommended storage at -20°C for powder and short-term use for solutions (APExBIO).

Applications, Limits & Misconceptions

MCC950 sodium is widely used in preclinical models of atherosclerosis, experimental autoimmune encephalomyelitis, and sterile inflammation. It facilitates the dissection of NLRP3's role in macrophage and endothelial cell pyroptosis, as demonstrated in recent endothelial dysfunction studies (Yuan et al., 2022). The B7946 kit from APExBIO is routinely employed in cell-based assays and animal models to evaluate NLRP3-targeted interventions. This review updates and extends the mechanistic focus of earlier resources such as 'MCC950 Sodium: Advancing Precision...' by providing new quantitative and translational benchmarks.

Common Pitfalls or Misconceptions

• MCC950 sodium is not active against non-NLRP3 inflammasomes (e.g., AIM2, NLRC4, NLRP1); lack of effect in these pathways does not indicate compound failure (Yuan et al., 2022).
• Not suitable for chronic solution storage or repeated freeze-thaw cycles; activity loss may result from improper handling (APExBIO).
• Does not inhibit TNF-α secretion or general cytokine responses—specificity is limited to NLRP3 inflammasome-dependent signaling (APExBIO).
• In vivo dosing and pharmacokinetics may differ between rodent strains and must be optimized for each experimental system (AVL-301 article).
• Not a clinically approved drug; for research use only (APExBIO).

Workflow Integration & Parameters

MCC950 sodium is compatible with a wide range of cell-based and animal models. For in vitro assays, it is typically administered at concentrations from 1 to 10 μM, with pre-incubation periods of 1–2 h prior to NLRP3 activation stimuli (RPMI-1640, 10% FBS, 37 °C, 5% CO₂). For in vivo rodent models, intraperitoneal doses of 10–20 mg/kg are reported, with adjustment based on pharmacokinetic and disease model requirements (Yuan et al., 2022). Solutions should be freshly prepared and protected from light. MCC950 sodium's high solubility supports its use in aqueous and organic media, enhancing experimental flexibility (Interleukin-II). For advanced workflow tips and comparative strategies, see 'Selective NLRP3 Inflammasome Inhibitor for...', which this article complements with updated pharmacological and disease-modeling data.

Conclusion & Outlook

MCC950 sodium is a benchmark tool for selective NLRP3 inflammasome inhibition in macrophage, monocyte, and endothelial models. Its nanomolar potency, pathway specificity, and solubility profile make it indispensable for dissecting inflammatory signaling and validating therapeutic hypotheses in autoimmunity and chronic inflammation. As supplied by APExBIO, MCC950 sodium (B7946) is supported by robust peer-reviewed evidence and is integral to translational research workflows. Ongoing studies continue to expand its translational relevance, particularly in vascular and neuroinflammatory disease modeling. For further technical and application details, consult the MCC950 sodium product page.