C-peptide ameliorates kidney injury following hemorrhagic shock

Reperfusion injury following hemorrhagic shock is accompanied by the development of a systemic inflammatory state that may lead to organ failure. C-peptide has been shown to exert anti-inflammatory effects in sepsis and myocardial ischemia-reperfusion injury, and to ameliorate renal dysfunction in diabetic animals. Hence, we investigated the effect of C-peptide on kidney injury following hemorrhagic shock. We hypothesized that C-peptide would exert reno-protective effects by blunting inflammation. Hemorrhagic shock was induced in male rats (3–4 months old) by withdrawing blood from the femoral artery to a mean arterial pressure of 50 mmHg. Animals were kept in shock for 3h at which time they were rapidly resuscitated by returning their shed blood. At the time of resuscitation and every hour thereafter, one group of animals received C-peptide (280 nmol/kg intravenously) while another group received vehicle. Hemorrhagic shock resulted in significant rise in plasma levels of creatinine and elevated kidney neutrophil infiltration as evaluated by myeloperoxidase (MPO) activity in vehicle-treated rats in comparison with sham rats, thus suggesting kidney injury. Treatment with C-peptide significantly attenuated the rise in creatinine and kidney MPO activity when compared to vehicle group. At a molecular level these effects of C-peptide were associated with reduced expression of the c-Fos subunit and reduced activation of the pro-inflammatory kinases, extracellular signal-regulated kinase (ERK 1/2) and c-Jun N-terminal kinase (JNK) and subsequently, reduced DNA binding of activator protein-1 (AP-1) in the kidney. Thus, our data suggest that C-peptide may exert reno-protective effects following hemorrhagic shock by modulating AP-1 signaling

C-peptide, a novel inhibitor of lung inflammation following hemorrhagic shock

C-peptide is a 31-amino acid peptide cleaved from proinsulin during insulin synthesis. Initially thought to be inert, C-peptide may modulate the inflammatory response in the setting of endotoxemia and ischemia reperfusion. However, the spectrum of its biological effects is unclear. We hypothesized that exogenous administration of C-peptide would modulate pro- and anti-inflammatory signaling pathways and thereby attenuate lung inflammation in an in vivo model of hemorrhagic shock. Hemorrhagic shock was induced in male Wistar rats (aged 3–4 mo) by withdrawing blood to a mean arterial pressure of 50 mmHg. At 3 h after hemorrhage, rats were rapidly resuscitated by returning their shed blood. At the time of resuscitation and every hour thereafter, animals received C-peptide (280 nmol/kg) or vehicle parenterally. Animals were euthanized at 1 and 3 h after resuscitation. C-peptide administration at resuscitation following hemorrhagic shock ameliorated hypotension and blunted the systemic inflammatory response by reducing plasma levels of IL-1, IL-6, macrophage inflammatory protein-1α, and cytokine-induced neutrophil chemoattractant-1. This was associated with a reduction in lung neutrophil infiltration and plasma levels of receptor for advanced glycation end products. Mechanistically, C-peptide treatment was associated with reduced expression of proinflammatory transcription factors activator protein-1 and NF-κB and activation of the anti-inflammatory transcription factor peroxisome proliferator-activated receptor-γ. Our data suggest that C-peptide ameliorates the inflammatory response and lung inflammation following hemorrhagic shock. These effects may be modulated by altering the balance between pro- and anti-inflammatory signaling in the lung

The Immunomodulatory Effects of Albumin In Vitro and In Vivo

Albumin appears to have proinflammatory effects in vitro. We hypothesized that albumin would induce a state of tolerance to subsequent administration of lipopolysaccharide (LPS) in vitro and in vivo. RAW264.7 and primary peritoneal macrophages were treated with increasing doses of bovine serum albumin (BSA) and harvested for NF-κB luciferase reporter assay or TNF-α ELISA. In separate experiments, RAW264.7 cells were preconditioned with 1 mg/mL BSA for 18 h prior to LPS (10 μg/mL) treatment and harvested for NF-κB luciferase reporter assay or TNF-α ELISA. Finally, C57Bl/6 mice were preconditioned with albumin via intraperitoneal administration 18 h prior to a lethal dose of LPS (60 mg/kg body wt). Blood was collected at 6 h after LPS administration for TNF-α ELISA. Albumin produced a dose-dependent and TLR-4-dependent increase in NF-κB activation and TNF-α gene expression in vitro. Albumin preconditioning abrogated the LPS-mediated increase in NF-κB activation and TNF-α gene expression in vitro and in vivo. The clinical significance of these findings remains to be elucidated