PERITONEAL-MACROPHAGES SHOW INCREASED CYTOKINE GENE-EXPRESSION FOLLOWING HEMORRHAGIC-SHOCK

Tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), IL-1 a nd transforming growth factor-beta (TGF-beta) have been recognized as important mediators of pathophysiological and immunological events ass ociated with shock. Previous studies have indicated that although peri toneal macrophage (PM phi) antigen presentation was depressed followin g haemorrhage, the cytokine release capacity in response to lipopolysa ccharide (LPS) was not affected in vitro. To determine the effect of h aemorrhagic shock on PM phi cytokine mRNA transcription, C3H/HeN male mice were bled to and maintained at a mean arterial blood pressure of 35 mmHg for 60 min, and then adequately resuscitated. PM phi were isol ated at 1 or 24 hr after haemorrhage and were incubated without or wit h 10 mu g LPS/ml for 1 hr. Total RNA was then extracted followed by No rthern blot analysis, as well as semi-quantitative reverse transcripti on and polymerase chain reaction (RT-PCR). The results of Northern blo t analysis indicated that haemorrhage markedly increased LPS-induced I L-1 beta, IL-6, and TNF-alpha mRNA accumulation in PM phi at both 1 an d 24 hr after haemorrhage and resuscitation. Furthermore, competitive RT-PCR demonstrated that mRNA of IL-1 beta, IL-6, TNF-alpha, as well a s TGF-beta, was increased in PM phi obtained 1 hr after haemorrhage ei ther with or without LPS stimulation. The data from Northern blot anal ysis and semiquantitative RT-PCR also revealed that LPS enhanced the e ffect of haemorrhage on PM phi cytokine gene expression. Thus, followi ng haemorrhage, PM phi showed elevated cytokine mRNA accumulation whic h was not followed by an increased ability to release cytokines in res ponse to LPS in vitro. These results, therefore, suggest that differen t mechanisms regulate gene expression and subsequent cytokine secretio n by PM phi following haemorrhage.