Induction of endotoxin tolerance in transgenic mouse liver expressing creatine kinase

Abstract

The liver plays an important role in maintaining homeostasis during endotoxin-triggered systemic inflammatory response. To study the effects of phosphocreatine on hepatic energy metabolism after endotoxin administration, we used transgenic mice whose livers express creatine kinase (CK). CK catalyzes a phosphocreatine/creatine reaction, that is, an adenosine triphosphate (ATP) reservoir system. Because dietary supplementation with creatine leads to an accumulation of creatine and phosphocreatine in transgenic livers, we compared the CK transgenic mice fed with creatine with the normally fed CK transgenic mice. In the creatine-fed mice, hepatic ATP, energy charge ([ATP + 0.5 adenosine diphosphate (ADP)]/[ATP + ADP + adenosine monophosphate (AMP)]), and mitochondrial oxidative phosphorylation activities remained at high levels after injection of 10 mg/kg of lipopolysaccharide (LPS) as compared with those in normally fed mice. Furthermore, there were beneficial effects on the functional reserve for ATP synthesis and work-cost performance, as calculated by free cytoplasmic ADP and the Michaelis constant (Km). Interestingly, a reduction of tissue necrosis factor alpha and interleukin-lalpha (IL-lalpha), and suppression of the decrease in glucose levels after LPS injection were observed in the creatine fed mice. Survival rates at 72 hours after injection of 10 mg/kg of LPS significantly increased in the creatine fed mice compared with the normally fed mice (80% vs. 24%, P < .001). Therefore, we concluded that the presence of phosphocreatine in the liver maintains energy metabolism and attenuates cytokine response, resulting in endotoxin tolerance.

The Beneficial Effect of Phosphocreatine Accumulation in the Creatine Kinase Transgenic Mouse Liver in Endotoxin-Induced Hepatic Cell Death

“…D-galactosamine-induced alterations increase the susceptibility of liver to the lethal effects of LPS several thousandfold [13]. At a dose of 0.2 mg/kg, LPS had no lethal effect on the transgenic mice because the sublethal dose of LPS we gave to our transgenic mice was 10 mg/kg [10]. A combination of D-galactosamine and LPS at the nonlethal dose was given to the transgenic mice that expressed creatine kinase in their livers.…”

“…Tissue extracts were made from mice livers which were frozen with liquid nitrogen. Using HPLC, ATP and phosphocreatine levels were measured simultaneously [10,11,15].…”

“…In addition, the presence of phosphocreatine reinforced mitochondrial ATP synthesis and work-cost performance by the accumulation of intramitochondrial adenine nucleotides [10,11]. However, the effects of liver-specific accumulation of phosphocreatine on endotoxin-induced hepatic injury remained unclear.…”

Hodgkin disease‐derived cell lines expressing ubiquitous mitochondrial creatine kinase show growth inhibition by cyclocreatine treatment independent of apoptosis

“…This is probably due to an increased permeability of the outer mitochondrial membrane for ADP and PCr. 40 With transgenic liver expressing B-CK, it was also shown that this tissue becomes tolerant against endotoxins, hypoxia and anoxia, 41,19 indicating that CK, together with its substrate Cr, can confer cell protection.…”

Functional Expression of Phosphagen Kinase Systems Confers Resistance to Transient Stresses in Saccharomyces cerevisiae by Buffering the ATP Pool

“…This complex functionality is also reflected by oligomeric composition and compartmentalization of the CK isoforms, with cytosolic isoenzymes (B-CK, M-CK) forming dimers and mitochondrial isoenzymes (sMtCK, uMtCK) forming dimers and octamers (8). In mice, expression of CK in the naturally CK-deficient liver led to multiple, beneficial effects for this organ, including tolerance to hypoxia and endotoxins (9,10). Although microorganisms are often exposed to rapidly changing environmental conditions and fluctuating availability of energy, phosphagen kinase systems occur only in few unicellular organisms, e.g.…”