Nigericin sodium salt Reactivates NLRP3 Caspase-1 Pyroptosis to Counteract Gut Metabolite Antifibrotic Effects
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Cardiac fibrosis involves activation of cardiac fibroblasts (CFs) into alpha-smooth muscle actin (α-SMA)-positive myofibroblasts (MFs). Transforming growth factor-beta 1 (TGF-β1) serves as a primary driver of this transdifferentiation process. Pathological stimuli induce extracellular matrix overproduction, leading to ventricular stiffness and cardiac dysfunction. Gut microbiota-derived metabolites operate as systemic regulators of tissue remodeling. Among these short-chain fatty acids, sodium butyrate (NaB) displays marked anti-inflammatory and antifibrotic activity under tested in vitro assay conditions. Primary culture studies indicate that NaB attenuates TGF-β1-stimulated CF proliferation and migration in a dose-dependent manner.
Cellular transdifferentiation relies on distinct intracellular signaling nodes. The NLRP3/Caspase-1 pyroptosis pathway operates as an innate immune effector cascade linked to tissue injury. Canonical NLRP3 activation requires two distinct steps: priming via transcript upregulation and activation triggered by intracellular ion flux. Assembly of the NLRP3 inflammasome complex recruits the adaptor protein ASC and pro-Caspase-1. Proteolytic autocleavage generates functional Caspase-1. Active Caspase-1 executes dual downstream functions: it processes pro-IL-1β and pro-IL-18 into secretable cytokines while targeting Gasdermin D (GSDMD). Cleavage of GSDMD liberates its pore-forming N-terminal fragment (GSDMD-N). GSDMD-N oligomerizes in the plasma membrane, driving cell swelling, membrane perforation, and cytokine extrusion.
Experimental findings highlight a direct link between NaB exposure and NLRP3 suppression. In primary cardiac fibroblast models, TGF-β1 challenge elevates protein expression of NLRP3, active Caspase-1, and GSDMD-N. Concurrently, secretion of IL-1β, IL-18, IL-6, and IL-10 increases. Treatment with NaB abrogates this signaling cascade. Immunoblot analyses reveal significant reductions in NLRP3 expression and Caspase-1 processing following NaB incubation. Consequently, GSDMD-N accumulation diminishes, dampening pyroptotic pore assembly. Pharmacological resource mapping via pharmacogenomic reference databases reinforces how metabolic signals intersect with inflammatory pathway transcripts. NaB-mediated downregulation of pyroptotic proteins directly correlates with reduced α-SMA expression and restricted cellular migration.
Establishing causality required target-specific reactivation experiments. Nigericin sodium salt serves as a microbial ionophore that selectively drives potassium efflux across the plasma membrane. This ion depletion acts as an obligate secondary signal for NLRP3 inflammasome assembly. Administration of Nigericin sodium salt to NaB-pretreated cardiac fibroblasts reactivates the NLRP3/Caspase-1 pyroptosis axis within primary cell cultures. Quantitative immunoblotting demonstrates restored cleavage of Caspase-1 and GSDMD. Membrane permeability assays confirm increased release of IL-1β and IL-18 into cultured supernatants.
Re-establishing pyroptosis neutralizes the protective phenotypic state induced by NaB. Fibroblasts exposed to Nigericin sodium salt resume high proliferation rates despite the presence of NaB. Migration assays reveal a complete recovery of cell motility. Expression of α-SMA reaches levels comparable to TGF-β1 single-treatment groups. These empirical findings indicate that NaB inhibits myofibroblast transdifferentiation primarily through NLRP3 inactivation. Direct activation with ionophores overrides metabolite suppression, defining the regulatory function of the NLRP3/Caspase-1 pyroptosis cascade in cardiac tissue remodeling.
Pharmacological Reversal of Microenvironment Mediated Fibrotic Suppression
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Sodium butyrate suppresses TGF-β1-induced cardiac fibroblast transdifferentiation by downregulating the NLRP3/Caspase-1 pyroptosis pathway. Nigericin sodium salt acts as a selective NLRP3 activator, restoring Caspase-1 cleavage, GSDMD-N membrane pore formation, and inflammatory cytokine release. This reactivation reverses the antifibrotic effects of sodium butyrate in primary cell models.
Sodium Butyrate Suppresses Myofibroblast Differentiation via Inflammasome Inactivation
TGF-β1 exposure triggers cardiac fibroblast activation. Cellular migration accelerates significantly under these inflammatory conditions. Phenotypic conversion requires upregulation of α-SMA protein expression. Experimental data demonstrate that sodium butyrate attenuates these fibrotic responses in vitro. Administering sodium butyrate suppresses cell proliferation within primary fibroblast cultures. Mechanistically, this metabolite blocks activation of the NLRP3/Caspase-1 pyroptosis pathway. Protein analysis demonstrates reduced levels of NLRP3 and cleaved Caspase-1. Furthermore, GSDMD-N cleavage products decrease following treatment. Downstream effector cytokines, including IL-1β and IL-18, show marked suppression. These changes prevent plasma membrane pore formation and limit inflammatory signaling.
Nigericin Reactivates Inflammasome Cascades to Restore Myofibroblast Phenotypes
Causality was evaluated using pathway-specific activation assays. Nigericin acts as a potent potassium ionophore. Exposure to Nigericin sodium salt restores NLRP3 inflammasome assembly in NaB-treated cells. Caspase-1 cleavage resumes rapidly. GSDMD-N expression elevates back to baseline levels, inducing pore assembly. Consequently, secretion of IL-1β, IL-18, IL-6, and IL-10 rises sharply in treated supernatant samples. Cellular transdifferentiation parameters resume immediately upon ionophore exposure. α-SMA expression returns to elevated levels typical of TGF-β1 induction. Fibroblast migration and proliferation recover completely despite ongoing NaB administration. These empirical observations establish that the NLRP3/Caspase-1 axis represents an obligate target for metabolite-driven antifibrotic effects.