No abstract

The mechanism by which SK&F 86002 and other pyridinyl imidazoles inhibit the production of IL-1 and TNF from LPS-stimulated human monocytes was examined. Inhibition of IL-1 and TNF production was found to depend on the time of addition of SK&F 86002, with diminishing effect when added more than 2 h after LPS stimulation. Analysis of Western blots confirmed that both intracellular IL-1 beta and extracellular TNF were significantly reduced in response to SK&F 86002, but these reductions were not paralleled by changes in IL-1 and TNF mRNA. 35S methionine pulse and pulse-chase studies on IL-1 biosynthesis suggest that significant inhibition by SK&F 86002 and related compounds occurs at the translational level.

No abstract

These data suggest that FrzB-2 may play a role in apoptosis and that the expression of this protein may be important in the pathogenesis of human OA.

One of the responses of the human macrophage to lipopolysaccharide (LPS) is the production of a number of cytokines. The regulation of these cytokines is still not clearly understood. To study this regulation, mRNA levels of interleukin 1 alpha (IL-1 alpha), IL-1 beta, tumor necrosis factor alpha (TNF-alpha), IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-8/neutrophil chemotactic factor were determined in 10-day-old differentiated macrophages following stimulation with a low dose of LPS (0.001 to 10 ng/mL) with use of the polymerase chain reaction. Increased levels of mRNA for IL-8 were detectable after exposure to a very low dose of LPS (0.001 ng/mL) and levels of IL-1 beta and TNF-alpha were detectable only after stimulation with doses of 0.01 ng/mL. The mRNA for IL-8 was detected 30 minutes after the addition of LPS, while those for IL-1 beta and TNF-alpha were only measurable at 1 hour. The mRNAs for IL-1 alpha, IL-6, and GM-CSF were detectable only with a higher dose of lipopolysaccharide and only after a longer exposure time. In addition, the messages for IL-6 and GM-CSF were measurable for a short time, while those of IL-8 and of IL-1 beta were detectable for a longer time. The secretion of TNF-alpha and GM-CSF tightly followed gene activation, and that of IL-6 and IL-8 steadily increased even after the mRNA level of these cytokines returned to baseline. Secretion of IL-1 alpha and IL-1 beta was hardly detected, although their gene activation was obvious. These data indicate that cytokine mRNA levels following lipopolysaccharide stimulation are highly regulated. Individual cytokines show variable patterns of response. These responses are both dose and time dependent and are not necessarily associated with the secretion of protein.