TGF-β Pathway Inhibition Protects the Diaphragm From Sepsis-Induced Wasting and Weakness in Rat

Abstract

Sepsis is a frequent complication in patients in intensive care units (ICU). Diaphragm weakness, one of the most common symptoms observed, can lead to weaning problems during mechanical ventilation. Over the last couple of years, members of the transforming growth factor (TGF) β family, such as myostatin, activin A, and TGF-β1, have been reported to strongly trigger the activation of protein breakdown involved in muscle wasting. The aim of this study was to investigate the effect of TGF-β inhibitor LY364947 on the diaphragm during chronic sepsis. Rats were separated into four groups exposed to different experimental conditions: Control group, Septic group, Septic group with inhibitor from day 0 (LY D0), and Septic group with inhibitor from day 1 (LY D1). Sepsis was induced in rats by cecal ligation and puncture, and carried out for 7 days. Chronic sepsis was responsible for a decrease in body weight, food intake and diaphragm's mass. The inhibitor was able to abolish diaphragm wasting only in the LY D1 group. Similarly, LY364947 had a beneficial effect on the diaphragm contraction only for the LY D1 group. SMAD3 was over-expressed and phosphorylated within rats in the Septic group; however, this effect was reversed by LY364947. Calpain-1 and -2 as well as MAFbx were over-expressed within individuals in the Septic group. Yet, calpain-1 and MAFbx expressions were decreased by LY364947. With this work, we demonstrate for the first time that the inhibition of TGF-β pathway during chronic sepsis protects the diaphragm from wasting and weakness as early as one day post infection. This could lead to more efficient treatment and care for septic patients in ICU.

Role of Glucocorticoid Signaling and HDAC4 Activation in Diaphragm and Gastrocnemius Proteolytic Activity in Septic Rats

“…In contrast, a progressive decrease in both muscle mass and the fiber cross-sectional area during seven days after sepsis induction has been observed in limb muscles [ 4 , 6 , 7 ]. There are several factors that can mediate sepsis-induced muscle wasting, muscle inflammation, increased autophagy, upregulation of the ubiquitin-proteasome system, and increased calpain activity and mitochondria dysfunction [ 6 , 7 , 12 , 13 ]. All these factors are induced by sepsis in both the diaphragm and limb muscles, but these responses in the diaphragm are smaller and transient in comparison with those of limb muscles, which are stronger and prolonged [ 6 , 7 ].…”

A new approach to sepsis treatment by rasagiline: a molecular, biochemical and histopathological study

“…[49]Due to sepsis, many pathological events such as hemorrhage, edema, increase in the number of immune cells and pulmonary obstruction accompany the lungs. [50] When we examined our study, it was observed that edema, hemorrhage and in ammation focuses were moderate in sepsis groups, while edema, in ammation and hemorrhagic areas almost completely disappeared in the groups to which rasagiline was applied.…”

A New Approach to Sepsis Treatment by Rasagiline: A Molecular, Biochemical and Histopathological Study

“…[49]Due to sepsis, many pathological events such as hemorrhage, edema, increase in the number of immune cells and pulmonary obstruction accompany the lungs. [50] When we examined our study, it was observed that edema, hemorrhage and in ammation focuses were moderate in sepsis groups, while edema, in ammation and hemorrhagic areas almost completely disappeared in the groups to which rasagiline was applied.…”