To investigate the role of lactylation modification in sepsis-induced cardiomyopathy, and to further explore the impact of regulating lactylation modification on cardiac function and prognosis in sepsis-induced cardiomyopathy.

Eighty C57BL/6 mice were divided into a isotonic NaCl solution control group (Ctrl group), a shikonin control group (Shik group), a model group [lipopolysaccharide (LPS) group], a LPS + shikonin group (LPS + Shik group), and a LPS + shikonin + lactate group (LPS + Shik + Lac group), with 16 mice in each group. The LPS group, LPS + Shik group, and LPS + Shik + Lac group were injected LPS (5 mg/kg) intraperitoneally to induce septic cardiomyopathy; the Ctrl group and Shik group were injected with isotonic NaCl solution (5 mg/kg) and shikonin (8 mg/kg). The LPS + Shik group was administered shikonin (8 mg/kg) intraperitoneally 1 h before LPS treatment; the LPS + Shik + Lac group was administered shikonin (8 mg/kg) intraperitoneally 1 h before LPS treatment and then given lactate (pH 6.8, 0.5 g/kg) 6 h after LPS administration. At 16 h after LPS injection, cardiac function was assessed by echocardiography in all groups (five mice/group), and cardiac tissue was collected for immunoblot analysis of lactylation-modified proteins, as well as for the detection of nicotinamide adenine dinucleotide-oxidation state (NAD⁺), nicotinamide adenine dinucleotide-reduction state (NADH), and adenosine triphosphate (ATP) levels in the mice. Their survival was closely observed and recorded for seven days after LPS administration (11 mice in each group). Furthermore, six C57BL/6 mice were divided into a Ctrl group and a LPS group, with three mice in each group. Cardiac samples were collected at 16 h after LPS injection to analyze myocardial lactylation-modified proteins and sites by mass spectrometry.

The lysine lactylation (Kla), left ventricular ejection fraction (LVEF), fractional shortening (FS), NAD⁺, NAD⁺/NADH, and ATP among the five groups showed statistically significant differences (F = 58.745, 10.560, 12.372, 21.347, 16.407, 32.163; all P < 0.001). Compared with the LPS group, the LPS + Shik group exhibited significantly lower Kla levels and significantly higher LVEF, FS, NAD⁺, NAD⁺/NADH, and ATP levels; compared with the LPS + Shik group, the LPS + Shik + Lac group had significantly increased Kla levels and significantly decreased LVEF, FS, NAD⁺, NAD⁺/NADH, and ATP levels (all P < 0.05). Within seven days after LPS administration, 0, 0, 9, 3, and 10 mice died in the five groups. The survival rate of the LPS, LPS + Shik, and LPS + Shik + Lac groups was statistically significantly different (χ² = 11.717, P = 0.003). The 7-day death of the LPS + Shik group was significantly lower than that of the LPS group, and the 7-day death of the LPS + Shik + Lac group was significantly higher than that of the LPS + Shik group (both P < 0.017). Compared with the Ctrl group, 105 differential lactylation proteins (DLPs) and 191 modification sites upregulated, and 10 DLPs and 10 modification sites downregulated in cardiac tissue of mice in the LPS group; 68.70% of DLPs were localized in the mitochondria and mainly involved in metabolism.

Lactylation modification plays a significant role in sepsis-induced cardiomyopathy, and the mechanism possibly involves the dysregulation of mitochondrial energy metabolism. Lactylation modification may be a potential therapeutic target for sepsis-induced cardiomyopathy.