Relationship between energetic stress and pro-apoptotic/cytoprotective kinase mechanisms in intestinal preservation.

BACKGROUND: A recent study from our laboratory documented significant improvements in post-transplant viability in an experimental model of intestinal transplantation when a novel, nutrient-rich preservation solution was used during cold storage. The current study investigated the relationship between energetic/oxidative stress responses and fundamental kinase signaling events during the period of organ storage. This relationship may be a key factor contributing to improved graft viability after storage in a nutrient-rich preservation solution.

METHODS: Rat small intestine was harvested and flushed intraluminally with University of Wisconsin (UW) solution or an amino acid-rich (AA) solution as follows: Group 1, no luminal flush (clinical control); Group 2, luminal UW solution; Group 3, luminal AA solution. Energetics (ATP, total adenylates), oxidative stress (malondialdehyde), histology, and MAPK (P38, JNK, ERK)/AMPK/Caspase-3 were assessed throughout 12-hour cold storage.

RESULTS: P38 and JNK were upregulated strongly in Group 2 after 1- and 12-hour storage. Group 3 exhibited a delayed activation and subsequent downregulation of these pre-apoptotic signals. Between 6 to 12 hours, a strong upregulation of ERK was observed in Group 3. AMPK downregulation correlated with a reduction in AMP/ATP ratio, ERK upregulation, and P38/JNK downregulation in Group 3. After 12-hour storage, histology indicated superior preservation of mucosal architecture in Group 3 tissues.

CONCLUSIONS: A nutrient-rich preservation solution abrogates pre-apoptotic signaling (JNK and P38) and upregulates cytoprotective signals (ERK). Our data support the concept of a concerted effort facilitating cellular protection in response to ischemic stress.