Hydrogen Sulfide Attenuated Sepsis-Induced Myocardial Dysfunction Through TLR4 Pathway and Endoplasmic Reticulum Stress

Abstract

Aims: We examined the change in endogenous hydrogen sulfide (H₂S) production and its role in sepsis-induced myocardial dysfunction (SIMD). Results: Significant elevations in plasma cardiac troponin I (cTnI), creatine kinase (CK), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were noted in SIMD patients, whereas left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), and plasma H₂S were significantly decreased relative to those in the controls. Plasma H₂S was linearly related to LVEF and LVFS. Subsequently, an SIMD model was developed in mice by injecting lipopolysaccharide (LPS), and NaHS, an H₂S donor, was used to elucidate the pathophysiological role of H₂S. The mice showed decreased ventricular function and increased levels of TNF-α, IL-1β, cTnI, and CK after LPS injections. Toll-like receptor (TLR) 4 protein and endoplasmic reticulum stress (ERS) proteins were over expressed in the SIMD mice. All of the parameters above showed more noticeable variations in cystathionine γ-lyase knockout mice relative to those in wild type mice. The administration of NaHS could improve ventricular function and attenuate inflammation and ERS in the heart. Conclusion: Overall, these findings indicated that endogenous H₂S deficiency contributed to SIMD and exogenous H₂S ameliorated sepsis-induced myocardial dysfunction by suppressing inflammation and ERS via inhibition of the TLR4 pathway.

Keywords: Toll-like receptor 4; endoplasmic reticulum stress; hydrogen sulfide; myocardial dysfunction; sepsis.

FIGURE 1

Plasma H₂S level decreased in SIMD patients: (A) Representative echocardiogram images from the Control group and the SIMD group. (B) The changes of left ventricular ejection fraction (LVEF). (C) The changes of left ventricular fractional shortening (LVFS). (D) cTnI levels in the plasma. (E) CK levels in the plasma. (F) TNF-α levels in the plasma. (G) IL-1β levelsin the plasma. (H) H₂S levels in the plasma. (I,J) Plasma H₂S level is positively correlated with LVEF and LVFS. n = 10 in every group. Results are means ± SD. p < 0.05 was considered significant.

FIGURE 2

LPS decreased plasma and heart tissues levels of H₂S in LPS-induced myocardial dysfunction mice: (A) H₂S levels in the plasma. (B) H₂S levels in the heart tissues. (C–F) Representative Western blots and quantification of CBS, CSE, and 3-MST protein expression in heart tissues. β-actin was used as the internal control. n = 8 in every group. Results are means ± SEM. p < 0.05 was considered significant.

FIGURE 3

Loss of endogenous H₂S aggravated LPS-induced myocardial dysfunction: (A) Representative M-mode images from WT Control, WT + LPS, CSE KO Control, and CSE KO + LPS groups. (B) The changes of left ventricular ejection fraction (LVEF). (C) The changes of left ventricular fractional shortening (LVFS). (D) cTnI levels in the plasma. (E) CK levels in the plasma. (F) Representative HE-stained left ventricular sections (scale bar = 50μm). (G) Pathological score of the HE-stained left ventricular sections. n = 8 in every group. Results are means ± SEM. p < 0.05 was considered significant.

FIGURE 4

Exogenous H₂S ameliorated LPS-induced myocardial dysfunction: (A) Representative M-mode images from the Control, LPS, and LPS + NaHS groups. (B) The changes of left ventricular ejection fraction (LVEF). (C) The changes of left ventricular fractional shortening (LVFS). (D) cTnI levels in the plasma. (E) CK levels in the plasma. (F) Representative HE-stained left ventricular sections (scale bar = 50 μm). (G) Pathological score of the HE-stained left ventricular sections. (H) Representative M-mode images from the WT + LPS, CSE KO + LPS, and CSE KO + LPS + NaHS groups. (I) The changes of left ventricular ejection fraction (LVEF). (J) The changes of left ventricular fractional shortening (LVFS). (K) cTnI levels in the plasma. (L) CK levels in the plasma. (M) Representative HE-stained left ventricular sections (scale bar = 50 μm). (N) Pathological score of the HE-stained left ventricular sections. n = 8 in every group. Results are means ± SEM. p < 0.05 was considered significant.

FIGURE 5

H₂S inhibited inflammation and ERS in LPS-induced myocardial dysfunction: (A) TNF-α levels in the plasma. (B) IL-1β levels in the plasma. (C–K) Representative Western blots and quantitative analysis for TLR4, CHOP, Caspase-12, GRP78, p-PERK/PERK, p-IRE1/IRE1, p90 ATF6, and p50 ATF6 protein expression in heart tissues. β-actin was used as the internal control. n = 8 in every group. Results are means ± SEM. p < 0.05 was considered significant.

FIGURE 6

H₂S inhibited inflammation and ERS in CSE KO mice: (A) TNF-α levels in the plasma. (B) IL-1β levels in the plasma. (C–K) Representative Western blots and quantitative analysis for TLR4, CHOP, Caspase-12, GRP78, p-PERK/PERK, p-IRE1/IRE1, p90 ATF6, and p50 ATF6 protein expression in heart tissues. β-actin was used as the internal control. n = 8 in every group. Results are means ± SEM. p < 0.05 was considered significant.