MULTIFUNCTIONAL REGULATION OF THE BIOLOGICAL EFFECTS OF TNF-ALPHA BY THE SOLUBLE TYPE-I AND TYPE-II TNF RECEPTORS

Two soluble receptors of tumour necrosis factor were evaluated for dev elopment as potential therapeutic agents for inflammatory disease, The recombinant human soluble Type I and Type II TNF receptors, rsTNF-RI and rsTNF-RII, were expressed at high levels in E. coli, refolded, and chromatographically purified to homogeneity. The potencies of both re combinant soluble receptors were similar to their naturally occurring soluble receptors, In in vitro cytotoxicity and competitive binding as says, both recombinant soluble receptors functioned to inhibit the bio logical effects of rhTNF-alpha although rsTNF-RI was a 5 to 30 fold mo re potent inhibitor of rhTNF-alpha than was rsTNF-RII or a truncated f orm of the soluble receptor, TNF-RII Delta. In in vivo experiments in mice, rsTNF-RI was a better inhibitor than rsTNF-RII Delta of rhTNF-al pha-stimulated changes in the percentages of circulating lymphocytes a nd neutrophils, influx of neutrophils into the peritoneal cavity, and serum IL-6 induction, At molar ratios of 0.1:1 and 0.01:1 (rsTNF-R:rhT NF-alpha), using the rsTNF-I or rsTNF-II Delta, there was a trend towa rds enhancement of the induction of IL-6, However, higher ratios of ei ther rsTNF-RI or rsTNF-RII Delta significantly inhibited the rhTNF-alp ha-stimulated increase in serum IL-6 levels. In a murine model of cyto kine-induced shock, either rsTNF-RI or rsTNF-RII Delta provided protec tion against the lethality of shock induced by a synergistic combinati on of rhTNF-alpha and rhIL-1 beta. Based on the results of these exper iments, the rsTNF-RI was chosen as the better candidate for developmen t as an anti-inflammatory agent.