IL-6 protects enterocytes from hypoxia-induced apoptosis by induction of bcl-2 mRNA and reduction of fas mRNA.

Interleukin-6 (IL-6) has been shown to rescue enterocytes from hypoxia-induced apoptosis when given orally following hemorrhagic shock. In vitro models using an intestinal epithelial cell line (IEC-6) cultured with lipopolysaccharide (LPS) under low O2 conditions, to mimic intestinal conditions, show that these cells also undergo apoptosis, which can be reduced by subsequent culture with IL-6. To examine further the mechanisms of rescue, we cultured normal rat intestinal epithelial cells (IEC-6) under both normoxic and hypoxic conditions and analyzed their responses to LPS and IL-6. We showed that IEC-6 expressed IL-6 receptor on its surface. Further, IEC-6 cells could be rescued from hypoxia-induced apoptosis by co-culture with IL-6. RNase protection assay (RPA) examination revealed that under hypoxic conditions, IEC-6 cells that were resistant to apoptosis showed reduced fas expression and increased bcl-2 expression after co-culture with LPS+IL-6.