Dapagliflozin Interrupts Pro-Fibroinflammatory Interleukin 11-Tenascin C Mutual Reinforcement in Fibroblasts by...

Sodium/glucose cotransporter 2 inhibitors (SGLT2i) protect against heart failure and fibroinflammation with an unclear mechanistic. Recombinant interleukin-11 (IL11) therapy for thrombocytopenia induces heart failure symptoms and signs. Profibrotic IL11 upregulates extracellular matrix (ECM) proteins, whereas pro-inflammatory tenascin-C (TNC) is an ECM-derived alarmin. We hypothesized IL11 upregulated TNC to induce fibroinflammation via Toll-like receptor 4 (TLR4) and prototype SGLT2i dapagliflozin counteracted the effects. We stimulated fibroblasts with IL11 and confirmed TNC upregulation. NADPH oxidase 2 (NOX2) is known to participate in TNC-TLR4 signaling. We treated IL11-stimulated fibroblasts with inhibitors of TLR4 (TLR4i) and NOX2 (NOX2i) and found IL11 induced an imperative profibrotic TNC-TLR4-NOX2 auto-amplification loop. IL11 is known to induce ERK-dependent positive autofeedback. By finding TLR4i and NOX2i inhibited IL11-induced ERK phosphorylation, we suspected IL11-ERK joined TNC-TLR4-NOX2 auto-amplification fibroinflammatory pathway. We stimulated fibroblasts with TNC and found IL11 upregulation. We treated TNC-stimulated fibroblasts with TLR4i, NOX2i, or neutralizing IL11 antibody and confirmed TLR4-NOX2 and IL11 were indispensable for TNC-induced fibrosis. We concluded that IL11-ERK, TNC-TLR4, and NOX2 are interdependent in fibroblasts and together make a positive-feedback loop to sustain fibroinflammation. We checked mRNA expression of relevant proteins from proteinatlas.org and found fibroblasts are overwhelming producers of IL11 and TNC in the heart. IL11 receptor subunit alpha (IL11RA) and TLR4 are highly differentially expressed with the former on cardiomyocytes and the latter on macrophages. We therefore proposed a model of differentially activated IL11RA and TLR4 signaling in response to mutually reinforcing IL11-TNC alarmins, to explain how activated fibroblasts pivotally support fibroinflammatory microenvironment and how danger signals induce cell-type-specific responses. Next, we showed dapagliflozin prevented fibroinflammation induced by IL11 or TNC. Mechanistically, we showed dapagliflozin antagonized IL11RA by molecular docking, fluorescence quenching, and grading-dose IL11-signaling inhibitor cocktails studies. In conclusion, dapagliflozin interrupts pro-fibroinflammatory IL11-TNC bi-alarmin mutual reinforcement in human cardiac fibroblasts by antagonizing IL11RA.