Female hormones prevent sepsis-induced cardiac dysfunction: an experimental randomized study

Abstract

Although epidemiologic research has demonstrated significant differences in incidence and outcomes of sepsis according to sex, their underlying biological mechanisms are poorly understood. Here, we studied the influence of hormonal status by comparing in vivo cardiac performances measured by MRI in non-ovariectomized and ovariectomized septic female rats. Control and ovariectomized rats were randomly allocated to the following groups: sham, sepsis and sepsis plus landiolol. Sepsis was induced by caecum ligation and punction (CLP). Landiolol, a short-acting selective β1-adrenergic blocker improving the in vivo cardiac performance of septic male rats was perfused continuously after sepsis induction. Cardiac MRI was carried out 18 h after induction of sepsis to assess in vivo cardiac function. Capillary permeability was evaluated by Evans Blue administration and measurement of its tissue extravasation. Variation in myocardial gene and protein expression was also assessed by qPCR and western-blot in the left ventricular tissue. Sepsis reduced indexed stroke volume, cardiac index and indexed end-diastolic volume compared to sham group in ovariectomized females whereas it had no effect in control females. This was associated with an overexpression of JAK2 expression and STAT3 phosphorylation on Ser727 site, and an inhibition of the adrenergic pathways in OVR females. Landiolol increased the indexed stroke volume by reversing the indexed end-diastolic volume reduction after sepsis in ovariectomized females, while it decreased indexed stroke volume and cardiac index in control. This was supported by an overexpression of genes involved in calcium influx in OVR females while an inactivation of the β-adrenergic and a calcium efflux pathway was observed in control females. Sepsis decreased in vivo cardiac performances in ovariectomized females but not in control females, presumably associated with a more pronounced inflammation, inhibition of the adrenergic pathway and calcium efflux defects. Administration of landiolol prevents this cardiac dysfunction in ovariectomized females with a probable activation of calcium influx, while it has deleterious effects in control females in which calcium efflux pathways were down-regulated.

Figure 1

Experimental protocol. OVR Bilateral ovariectomy, CLP Caecum ligation and punction, Bolus NaCl 0.9% 1 mL/100 g/h in 30 min, MRI magnetic resonance imaging, EB injection of 80 mg/kg of Evans Blue.

Figure 2

Left ventricular cardiac parameters assessed by MRI of sham (n = 6), sepsis (n = 5), sepsis plus landiolol (n = 5), OVR-sham (n = 6), OVR-sepsis (n = 6) and OVR-sepsis plus landiolol (n = 6). (A) Indexed stroke volume (SVi). (B) Cardiac index (CI). (C) Indexed end-diastolic volume (EDVi). Data are expressed as means ± SEM. ****p < 0.0001 vs sham and vs OVR-sham, respectively. ^§p < 0.05; ^§§p < 0.01; ^§§§§p < 0.0001 vs sepsis and OVR-sepsis, respectively. ^†††p < 0.001; ^††††p < 0.0001 vs control of corresponding group.

Figure 3

Left ventricular JAK2 expression and STAT3 phosphorylation assessed by western-blot in sham (n = 5), sepsis (n = 4), sepsis plus landiolol (n = 4), OVR-sham (n = 5), OVR-sepsis (n = 5) and OVR-sepsis plus landiolol (n = 4). (A) JAK2 expression. (B) STAT3-Tyr705 phosphorylation. (C) The phosphorylation of STAT3 and the expression of JAK2 were normalized to actin on stripped blot. (D) STAT3-Ser727 phosphorylation. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001 vs sham and vs OVR-sham, respectively. ^§p < 0.05 vs OVR-sepsis. ^††p < 0.01; ^††††p < 0.0001 vs control of corresponding group.

Figure 4

Transcripts regulation by sepsis and landiolol of the adrenergic and excitation/contraction coupling pathways. (A) In control females. (B) In OVR females. In red: up-regulated, green: down-regulated and grey: not regulated transcripts in sepsis vs sham: left part of symbol, in sepsis + landiolol vs sepsis: right part of symbol; *in sepsis + landiolol vs sham.