MCC950 Sodium: Selective NLRP3 Inflammasome Inhibitor for Inflammatory Disease Research

Executive Summary: MCC950 sodium (CAS 256373-96-3) is a potent, selective small-molecule inhibitor of the NLRP3 inflammasome, exhibiting nanomolar efficacy in both murine and human macrophage models (APExBIO). It demonstrates remarkable specificity, inhibiting NLRP3-driven interleukin-1β (IL-1β) release without affecting other inflammasome complexes or TNF-α secretion (Yuan et al., 2022). MCC950 sodium is highly soluble in aqueous and organic solvents, facilitating its use in diverse cell assay and animal model workflows. In vivo, it attenuates disease severity and systemic inflammation in experimental autoimmune encephalomyelitis models. These features make MCC950 sodium a critical tool for mechanistic studies and therapeutic discovery in NLRP3-associated inflammation and autoimmunity.

Biological Rationale

The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a cytosolic multiprotein complex that regulates caspase-1 activation and the maturation of pro-inflammatory cytokines IL-1β and IL-18 in response to cellular stress signals (Yuan et al., 2022). Aberrant activation of the NLRP3 inflammasome is implicated in the pathogenesis of a range of inflammatory and autoimmune diseases, including atherosclerosis, multiple sclerosis, and type 2 diabetes. Pyroptosis, an inflammatory form of programmed cell death, is closely linked to NLRP3 inflammasome activation and drives tissue injury and chronic inflammation (Yuan et al., 2022). Targeting NLRP3 selectively is thus a validated approach for dissecting inflammatory signaling and developing new therapies for NLRP3-driven disorders.

Mechanism of Action of MCC950 sodium

MCC950 sodium (also known as CRID3 sodium salt) is a small-molecule inhibitor that binds directly to the NACHT domain of NLRP3, preventing its ATPase activity and oligomerization, which are required for inflammasome assembly (see mechanistic review). This inhibition is highly selective: MCC950 sodium blocks both canonical (e.g., LPS + ATP) and noncanonical (e.g., LPS + nigericin) NLRP3 activation pathways in macrophages with an IC₅₀ of 7.5 nM in murine BMDMs and comparable potency in human monocyte-derived macrophages (APExBIO). Importantly, MCC950 sodium does not inhibit other inflammasome sensors, such as AIM2, NLRC4, or NLRP1, nor does it impair TNF-α secretion, supporting its use as a highly specific probe (mechanistic specificity update).

Evidence & Benchmarks

• MCC950 sodium inhibits NLRP3-mediated IL-1β release in murine bone marrow-derived macrophages (BMDMs) with an IC₅₀ of 7.5 nM under standard cell culture conditions (37°C, 5% CO₂) (APExBIO).
• In human monocyte-derived macrophages (HMDMs), MCC950 sodium shows comparable nanomolar potency and selectivity for NLRP3 inflammasome inhibition (Yuan et al., 2022).
• In cell-based assays, MCC950 sodium dose-dependently inhibits IL-1β secretion in BMDMs, HMDMs, and human peripheral blood mononuclear cells (PBMCs) without affecting TNF-α secretion, confirming functional specificity (Yuan et al., 2022).
• In vivo, intraperitoneal administration of MCC950 sodium reduces serum IL-1β and IL-6 levels in LPS-challenged mice (8 mg/kg, i.p., 2 h) and attenuates disease severity in experimental autoimmune encephalomyelitis models (APExBIO).
• MCC950 sodium demonstrates high solubility: ≥124 mg/mL in water, ≥21.45 mg/mL in DMSO, and ≥43 mg/mL in ethanol at room temperature, facilitating diverse experimental workflows (APExBIO).

Applications, Limits & Misconceptions

MCC950 sodium is used extensively in basic and translational research to dissect NLRP3 inflammasome signaling, validate disease models, and screen drug candidates. Its high selectivity and potency make it suitable for in vitro studies in macrophages, monocytes, and endothelial cells, as well as in vivo models of autoimmune and inflammatory diseases.

For a broader view of MCC950 sodium's role in NLRP3 inflammasome research, see this overview, which surveys its transformative impact on the field. This current article provides updated quantitative data and clarifies workflow-specific guidance not covered in previous reviews.

Common Pitfalls or Misconceptions

• MCC950 sodium does not inhibit non-NLRP3 inflammasomes: It is ineffective against AIM2, NLRC4, and NLRP1 inflammasomes (Yuan et al., 2022).
• Not a pan-cytokine inhibitor: MCC950 sodium specifically blocks IL-1β (and IL-18) release; TNF-α and other cytokines are unaffected at standard concentrations (Yuan et al., 2022).
• Solubility and stability: Although highly soluble, MCC950 sodium solutions should not be stored long-term; fresh preparation is recommended for reproducibility (APExBIO).
• Species and cell-type context: Activity and optimal dosing may vary between murine and human cells; benchmarking is required for each system (see comparative analysis).
• Not a therapeutic drug (as of 2024): MCC950 sodium is for research use only and not approved for clinical therapy (APExBIO).

Workflow Integration & Parameters

MCC950 sodium is supplied as a sodium salt for improved solubility. It can be dissolved in water, DMSO, or ethanol at room temperature. Recommended storage is at -20°C; avoid freeze-thaw cycles and long-term solution storage. In cell-based assays, concentrations of 0.01–10 μM are typical, with 2 h preincubation sufficient for robust NLRP3 inhibition (Yuan et al., 2022). For in vivo studies, reported doses range from 5–20 mg/kg, administered intraperitoneally. Dosing must be empirically optimized for each model system.

To see how MCC950 sodium is used in advanced inflammasome models, consult this article, which focuses on its application in autoimmune disease research and provides complementary use-case data to the present review.

Conclusion & Outlook

MCC950 sodium (APExBIO B7946) is the gold-standard selective NLRP3 inflammasome inhibitor for research workflows requiring high specificity and reproducibility. Its atomic mechanism, nanomolar potency, and broad applicability in cell and animal models make it indispensable for dissecting NLRP3-driven inflammatory pathways. As NLRP3's role in human disease expands, MCC950 sodium will remain central to both mechanistic discovery and therapeutic innovation. For product details and ordering, visit the official APExBIO MCC950 sodium page.