The effect of soluble tumor necrosis factor receptor-II on endotoxin-mediated hemodynamic instability

Altered release of tumor necrosis factor and its soluble receptor in non-Hodgkin's lymphoma patients

Increased expression and elevated serum levels of tumor necrosis factor-alpha (TNF-alpha) have been shown to be associated with the presence of constitutional B symptoms and poor prognosis in non-Hodgkin's lymphoma (NHL) patients. Soluble TNF receptors (sTNF-R) are suggested to act as biological buffers in inflammatory conditions by binding and inactivating increased circulating TNF. Whereas studies have shown elevated TNF to be correlated with B symptoms, similar studies showing the status of soluble receptor release in these patients have not been conducted. Here, we show that there is increased soluble p75 TNF receptor release from peripheral blood mononuclear cells (PBMNC) in NHL patients in the early stages of the disease but it is severely depressed in patients with advanced disease. Decreased release is associated with presence of B symptoms in these patients. All NHL patients also show increased TNF secretion and a decreased rate of receptor release with time compared with healthy controls. These findings imply that decreased sTNF-R receptor release, in addition to increased TNF secretion, is also important in predisposing the patients to B symptoms. This opens up the possibility of the use of sTNF-Rs as a therapeutic tool to counter increased TNF and alleviate systemic symptoms in these patients and also as a marker for the progression of the disease.

The locus of tumor necrosis factor-alpha action in lung inflammation

The pulmonary host response to infection and inflammation appears, at least in part, to be compartmentalized from the systemic host response. Tumor necrosis factor-alpha (TNF-alpha) has been implicated in lung inflammation and injury, but its site(s) of action has not been clearly defined. To investigate this, transgenic mice (surfactant apoprotein C promotor/soluble TNF receptor type II-Fc fusion protein ([SPCTNFRIIFc] mice) were generated in which TNF-alpha was selectively antagonized in the distal lung through tissue-specific expression of sTNFRIIFc, a soluble TNF inhibitor. The lung inflammatory response in these mice to pulmonary challenge with Micropolyspora faeni antigen or lipopolysaccharide (LPS) was compared with the response of wild-type mice, wild-type mice treated with recombinant sTNFRIIFc intravenously, and type I TNF-receptor knockout mice. Recruitment of polymorphonuclear leukocytes (PMN) to the lung after challenge with M. faeni antigen was essentially abolished in the TNFRI knockout mice and markedly reduced in the SPCTNFRIIFc mice. Wild-type mice given sTNFRIIFc intravenously in amounts resulting in lung concentrations similar to those in SPCTNFRIIFc mice also showed significantly reduced lung PMN recruitment, whereas those given doses that achieved such concentrations in the blood but low levels in the lung did not. In contrast, PMN recruitment to the lung following aerosol challenge with LPS was reduced significantly in the TNFRI knockout mice and in mice given high-dose sTNFRIIFc intravenously, but was not reduced significantly in SPCTNFRIIFc mice. Thus, inhibition of PMN recruitment in response to M. faeni antigen correlated largely with the extent of intrapulmonary inhibition of TNF-alpha, whereas the response to LPS correlated best with the extent of extrapulmonary inhibition of TNF-alpha. These studies indicate that TNF-alpha may act at different loci to mediate lung inflammation, with the site of action depending in part on the nature of the inflammatory stimulus, and that SPCTNFRIIFc mice provide a tool by which the locus of TNF action can be addressed.

Fluid resuscitation attenuates early cytokine mRNA expression after peritonitis

OBJECTIVE

To study the hypothesis that fluid resuscitation alters cytokine gene expression after experimental murine peritonitis.

MATERIALS AND METHODS

Mice underwent cecal ligation and puncture (CLP) to induce peritonitis and were randomized to receive variable amounts of normal saline (0, 0.25, 1.0 ml. subcutaneously) and serum (0 or 0.1 mL) after operation. Hepatic and small intestinal (ileal) tissue were harvested at 3 or 6 hours after CLP, and total tissue RNA was extracted. Reverse transcriptase polymerase chain reaction was used to provide relative quantitation of tumor necrosis factor-alpha and interleukin (IL)-1 beta messenger RNA (mRNA) compared with beta-actin.

RESULTS

CLP without resuscitation resulted in significant increases in hepatic tumor necrosis factor-alpha mRNA (1190% at 6 hours compared with normal animals), and IL-1 beta mRNA (1475%), and intestinal IL-1 beta mRNA (1243%). Volume administration attenuated cytokine expression at both 3 and 6 hours, and saline seemed to have more potent effects than serum. The volume of resuscitation correlated with survival at 18 hours. Survival in the saline (1 mL) + serum group was 90% at 18 hours compared with 20 to 40% in the groups with little or no resuscitation. Overall, there were no survivors at 30 hours.

CONCLUSIONS

Fluid resuscitation (amount, composition, timing) should be an important consideration in the utilization of experimental infection models. Furthermore, optimization of the patient's intravascular volume status during sepsis may have important effects on immune responses, in addition to improving hemodynamic variables.