Responses of hepatic TNF-alpha mRNA to repeated hemorrhage in the conscious rat

Endoscopic finding of spontaneous hemorrhage correlates with tumor necrosis factor alpha expression in colonic mucosa of patients with ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is an intractable colonic disease, and it shows several endoscopic findings. Recently, it was reported that the expression level of mucosal tumor necrosis factor alpha (TNF-α) was useful for predicting patient response to infliximab. However, no data regarding the value of endoscopic findings to predict treatment efficacy or cytokine expression level exist.

OBJECTIVE

We investigated the expression of leukocyte adhesion-related molecules and cytokines in colonic mucosa and compared it to endoscopic findings.

METHODS

One hundred and fifty-nine patients were enrolled. Tissue samples were obtained by colonic biopsy from patients with UC. Colitis activity was determined by Matts' criteria. The degree of mRNA expression of TNF-α, interferon gamma (IFN-γ), interleukin (IL)-8, IL-17A, and mucosal vascular addressin adhesion molecule-1 (MAdCAM-1) in mucosal samples was determined by real-time quantitative polymerase chain reaction. These expression levels were compared with the degree of Matts' grade and individual endoscopic findings.

RESULTS

The expression of TNF-α, IFN-γ, IL-8, IL-17A, and MAdCAM-1 mRNA significantly increased as Matts' endoscopic grade elevated. Actively inflamed mucosa with spontaneous hemorrhage revealed a significantly increased expression level of TNF-α mRNA than that without spontaneous hemorrhage. No other individual endoscopic parameter was significantly correlated with the expression level of TNF-α mRNA.

CONCLUSIONS

Inflamed mucosa with spontaneous hemorrhage may suggest increased expression of TNF-α mRNA levels in colonic mucosa of UC patients, which could predict a lower response to infliximab treatment and more aggressive induction regime or change to other therapy should be taken into account.

Adrenalectomy enhances response of tumour necrosis factor-alpha (TNF-alpha) to haemorrhage in the conscious rat

Several factors have been implicated in TNF-alpha induction after haemorrhage, but the precise mechanism is unknown. To assess a possible role of adrenal glands on TNF-alpha induction after haemorrhage, adrenalectomized (ADX) and sham-adrenalectomized (Sham) rats were subjected to 20 ml/kg haemorrhage (approximately 30% of the total blood volume) over 5 min in the conscious state, and changes in serum TNF and hepatic TNF-alpha mRNA were analysed by cytotoxicity against L929 cells and by semiquantitative reverse transcription-polymerase chain reaction, respectively. Changes in plasma corticosterone (CS) and mean arterial blood pressure (MABP) were also detected. Plasma CS levels showed a rapid increase after haemorrhage in Sham rats, whereas there was no response in ADX rats. Responses of MABP were comparable in the two groups. Both serum TNF and hepatic TNF-alpha mRNA showed rapid increases after haemorrhage in the Sham group, and these increases were significantly augmented in the ADX group. Pretreatment with CS (100 microg/h) negated these augmentations in ADX rats. These results show that adrenalectomy enhances the response of TNF-alpha to 20 ml/kg haemorrhage in the conscious rat, and suggest that endogenous glucocorticoids may play an inhibitory role in the induction of TNF-alpha after haemorrhage.

Hyperbaric oxygen treatment attenuates cytokine induction after massive hemorrhage

We investigated the effect of hyperbaric oxygen treatment (HBO) on cytokine induction after hemorrhage, because hypoxia induces cytokines in vitro. Chronically cannulated conscious rats were subjected to 40 ml/kg of hemorrhage and resuscitated with the shed blood and twice the volume of saline either under room air (room air group) or under 100% oxygen at 3 atmospheres absolute (hyperbaric group). Rats exposed to HBO with no hemorrhage served as controls. Time course changes in plasma endotoxin level, arterial ketone body ratio (AKBR), serum tumor necrosis factor (TNF), interleukin-6 (IL-6), and their hepatic mRNA were detected in the three groups. Plasma endotoxin levels increased significantly after hemorrhage, and there were no significant differences between the room air group and the hyperbaric group. In the room air group, AKBR dropped rapidly after hemorrhage and became minimal at hour 1, which was associated with significant increases in TNF-alpha and IL-6 at both mRNA and circulating levels. HBO significantly attenuated decreases in AKBR after hemorrhage with a significant reduction of mortality and cytokine induction. These results indicate that HBO attenuated the cytokine induction after hemorrhage by improving liver ischemia, and they suggest that tissue hypoxia may be responsible, at least in part, for cytokine induction after massive hemorrhage.