Activation of Sig-1R by afobazole attenuates Tollip/HMGB1-mediaded CCN2 autophagic degradation and NETs formation in sunitinib-induced cardiotoxicity in mice: Involvement of IRE 1α/ASK1/JNK/ AP-1 trajectory.

Although the contribution of sigma1 receptor (Sig-1R) to afobazole's cardioprotection has been meticulously investigated, Sig-1R-mediated cardioprotective effect of afobazole against sunitinib cardiotoxicity has not been studied yet. Hence, we aimed at studying the potential modulatory impact of afobazole on Sig-1R to combat sunitinib-induced endoplasmic reticulum (ER) stress, maladaptive autophagy, and hyperactivation of neutrophils that ends up with neutrophil extracellular traps (NETs) formation. Pre-treatment with afobazole attenuated sunitinib-induced cardiotoxicity and enhanced cardiac function via significant reduction of TNNT2 and CK-MB, and restoration of nearly normal hemodynamic measurements. Afobazole-mediated Sig-1R activation mitigated the ER stress sensor, IRE1α activation and its downstream (ASK/JNK/AP-1) pathways along with caspase-3 and FK18. Subsequently, afobazole hindered NETs formation by prohibiting ER stress-induced activation of caspase-2 and pro-inflammatory cytokines; IL-1β and TNFα, as indicated by the significant reduction of NETs' specific components, namely, PAD4, NE, and MPO, along with the NETs' specific marker Cit H3. Afobazole also downregulated sunitinib-induced maladaptive autophagy, as reflected by reducing the expressions of autophagy-regulating proteins (ATG5 and ATG7) and microtubule-associated protein light chain 3 (LC3-II/I) ratio as well p62 upregulation. Furthermore, afobazole exhibited a cardioprotective effect by restoring nearly normal CCN2 level that was degraded by Tollip and HMGB1. The above-mentioned outcomes triggered by afobazole were clearly negated upon administration of the Sig-1R antagonist (BD1047), confirming that Sig-1R activation predominantly mediates the observed cardioprotective effects. Afobazole demonstrated efficacy in mitigating sunitinib-induced cardiotoxicity, as evidenced through the enhancements in hemodynamic stability, reduction of ER stress, amelioration of maladaptive autophagy, and inhibition of NETs formation.