Objective:To investigate the effect and underlying mechanism of sonodynamic therapy (SDT) on inflammation-related atrial fibrillation (AF) susceptibility.Methods:Lipopolysaccharide (LPS)-stimulated mouse and HL-1 mouse atrial myocyte models were used. (1) In vivo study: experimental groups included control, LPS, LPS+SDT, and SDT groups, with 20 mice in each group. Atrial fibrillation inducibility and duration were assessed by electrical stimulation. Western blot was used to analyze atrial expression of NOD-like receptor family pyrin domain-containing protein 3 (NLRP3), interleukin (IL)-1β, and IL-18. Immunohistochemistry was used to detect calcium voltage-gated channel subunit alpha1 C (CACNA1C) expression. (2) In vitro study: cell counting kit-8 (CCK-8) and Western blot were used to determine the optimal and safe LPS concentration. The safe incubation condition for the sonosensitizer sinoporphyrin sodium was determined by CCK-8 and fluorometry. An LPS-induced inflammatory model in HL-1 atrial myocytes was used, with experimental groups including control, LPS, LPS+SDT, LPS+sinoporphyrin sodium, and LPS+ultrasound groups. NLRP3 was overexpressed using plasmid transfection, with experimental groups including control, NLRP3 plasmid, negative control plasmid, and NLRP3 plasmid+SDT groups. SDT was applied to LPS-stimulated or NLRP3-overexpressing HL-1 cells. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were used to measure mRNA and protein levels of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), Cleaved Caspase-1, IL-1β, IL-18, and CACNA1C. The NLRP3 inhibitor MCC950 was used to validate the relationship of NLRP3 and CACNA1C. The experimental groups included control, LPS, LPS+MCC950, and MCC950 groups. Intracellular reactive oxygen species (ROS) levels were detected using the probe DCFH-DA, and the ROS scavenger N-acetyl-L-cysteine (NAC) was used to test if the effects of SDT was ROS-dependent.Results:(1) In vivo: The LPS+SDT group exhibited a lower incidence of atrial fibrillation induction and a shorter duration of atrial fibrillation compared to the LPS group(both P<0.05). Protein expression levels of NLRP3 and IL-1β were lower than those in the LPS group (all P<0.05), while the expression of CACNA1C subunit tended to increase relative to the LPS group ( P>0.05). (2) In vitro: The safe concentration of LPS for administration was ≤20 μg/ml, with an optimal pro-inflammatory concentration of 4 μg/ml. The safe concentration of sinoporphyrin sodium for administration was 0.4 μmol/L, with an optimal incubation time of 4 hours. Compared to the LPS group or NLRP3 plasmid group, the LPS+SDT group or NLRP3 plasmid+SDT group exhibited lower expression levels of NLRP3, ASC, Cleaved Caspase-1, IL-1β, and IL-18, and higher mRNA and protein levels of CACNA1C (all P<0.05). The LPS+MCC950 group had higher CACNA1C protein expression than the LPS group ( P<0.05). SDT increased intracellular ROS levels, and NAC blocked the regulatory effects of SDT on NLRP3 and CACNA1C. Conclusion:SDT reduces atrial fibrillation susceptibility in mice by inhibiting NLRP3 inflammasome activation in atrial cardiomyocytes, thereby upregulating the L-type calcium channel subunit CACNA1C.

Objective:To investigate the effect and underlying mechanism of sonodynamic therapy (SDT) on inflammation-related atrial fibrillation (AF) susceptibility.Methods:Lipopolysaccharide (LPS)-stimulated mouse and HL-1 mouse atrial myocyte models were used. (1) In vivo study: experimental groups included control, LPS, LPS+SDT, and SDT groups, with 20 mice in each group. Atrial fibrillation inducibility and duration were assessed by electrical stimulation. Western blot was used to analyze atrial expression of NOD-like receptor family pyrin domain-containing protein 3 (NLRP3), interleukin (IL)-1β, and IL-18. Immunohistochemistry was used to detect calcium voltage-gated channel subunit alpha1 C (CACNA1C) expression. (2) In vitro study: cell counting kit-8 (CCK-8) and Western blot were used to determine the optimal and safe LPS concentration. The safe incubation condition for the sonosensitizer sinoporphyrin sodium was determined by CCK-8 and fluorometry. An LPS-induced inflammatory model in HL-1 atrial myocytes was used, with experimental groups including control, LPS, LPS+SDT, LPS+sinoporphyrin sodium, and LPS+ultrasound groups. NLRP3 was overexpressed using plasmid transfection, with experimental groups including control, NLRP3 plasmid, negative control plasmid, and NLRP3 plasmid+SDT groups. SDT was applied to LPS-stimulated or NLRP3-overexpressing HL-1 cells. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were used to measure mRNA and protein levels of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), Cleaved Caspase-1, IL-1β, IL-18, and CACNA1C. The NLRP3 inhibitor MCC950 was used to validate the relationship of NLRP3 and CACNA1C. The experimental groups included control, LPS, LPS+MCC950, and MCC950 groups. Intracellular reactive oxygen species (ROS) levels were detected using the probe DCFH-DA, and the ROS scavenger N-acetyl-L-cysteine (NAC) was used to test if the effects of SDT was ROS-dependent.Results:(1) In vivo: The LPS+SDT group exhibited a lower incidence of atrial fibrillation induction and a shorter duration of atrial fibrillation compared to the LPS group(both P<0.05). Protein expression levels of NLRP3 and IL-1β were lower than those in the LPS group (all P<0.05), while the expression of CACNA1C subunit tended to increase relative to the LPS group ( P>0.05). (2) In vitro: The safe concentration of LPS for administration was ≤20 μg/ml, with an optimal pro-inflammatory concentration of 4 μg/ml. The safe concentration of sinoporphyrin sodium for administration was 0.4 μmol/L, with an optimal incubation time of 4 hours. Compared to the LPS group or NLRP3 plasmid group, the LPS+SDT group or NLRP3 plasmid+SDT group exhibited lower expression levels of NLRP3, ASC, Cleaved Caspase-1, IL-1β, and IL-18, and higher mRNA and protein levels of CACNA1C (all P<0.05). The LPS+MCC950 group had higher CACNA1C protein expression than the LPS group ( P<0.05). SDT increased intracellular ROS levels, and NAC blocked the regulatory effects of SDT on NLRP3 and CACNA1C. Conclusion:SDT reduces atrial fibrillation susceptibility in mice by inhibiting NLRP3 inflammasome activation in atrial cardiomyocytes, thereby upregulating the L-type calcium channel subunit CACNA1C.