We have previously shown that apoptotic and myocardial mitochondrial respiratory abnormalities,
occurring during severe sepsis in a murine model, can be prevented by overexpression
of Bcl-2, a regulatory protein of mitochondrial function. So, we sought to evaluate,
in this model, a pharmacological modulation by cyclosporin A (CsA), a mitochondrial
permeability transition pore (MPTP) inhibitor, and by its non-immunosuppressive derivative
N-methyl-4-isoleucin CsA (NIM 811).
Materials and methods
Using a model of severe sepsis cecal ligation and puncture (CLP) induced (21-gauge
needle) in female mice aged from 6 to 10 weeks, we studied the effects on 48-hour
survival, echocardiographic data, myocardial apoptosis (nuclear apoptosis and caspase-3
and caspase-9 activation), and myocardial mitochondrial respiration, of MPTP inhibitors:
CsA and NIM 811. A dose–response study was carried out with CsA in the following groups:
CLP mice (n = 15), CLP + CsA 2 mg/kg (n = 8), CLP + CsA 10 mg/kg (n = 20), and CLP
+ CsA 100 mg/kg (n = 5). CsA was administered postoperatively, during the 1 ml subcutaneous
injection for vascular filling. NIM 811 (dose of 2 mg/kg) was administered identically.
Compared with sham, CLP mice present a low 48-hour survival (32% vs 90%; P < 0.05),
an increased shortening fraction at H24, and a greater myocardial apoptotic activity.
Forty-eight-hour survival in septic mice is significantly improved with use of CsA
or NIM 811 (100% vs 32%; P < 0.05). Low (2 mg/kg) or moderate (10 mg/kg) doses of
CsA improve 48-hour survival. Shortening fraction increases early at H6 in the CLP
+ CsA group, and is normalized at H24. Myocardial nuclear apoptosis and caspase-3
and caspase-9 activation are prevented by CsA and NIM 811. We also observed, in the
CLP group, an early increase of oxygen consumption, at the complex IV level of the
mitochondrial respiratory chain. This was also prevented by MPTP inhibitors in the
CLP + CsA and CLP + NIM 811 groups.
These results suggest that mitochondrial respiration disruption could be responsible
for myocardial dysfunction occurring during severe sepsis. To our knowledge, this
is the first study addressing effects of NIM 811 in a severely septic animal model.
Thus, the mitochondrial permeability transition pore constitutes a major target, and
NIM 811 should be considered a therapeutic agent of potential great interest.