Differential regulation of protein tyrosine kinase on free radical production, granule enzyme release, and cytokine synthesis by activated murine peritoneal macrophages

The present study examined the regulatory effect of tyrosine kinase inhibit ors (genistein, tyrphostin, and 2,5-dihydroxycinnamate) on the free radical production, granule enzyme release, and synthesis of interleukin (IL)-8 an d granulocyte macrophage-colony stimulating factor (GM-CSF) in murine perit oneal macrophages exposed to different stimulators [10 ng/mL of IL-1, 1 mug /mL of lipopolysaccharide (LPS), and 1 muM N-formyl-methionyl-leucyl-phenyl alanine (fMLP)]. Protein tyrosine kinase (PTK) inhibitors attenuated the st imulated superoxide, hydrogen peroxide, and nitric oxide production in macr ophages stimulated with IL-1, LPS, or fMLP. N,N-Dimethylsphingosine (DMS) a lone stimulated superoxide and hydrogen peroxide production by intact macro phages, but at 45 muM the stimulatory effect on superoxide production was n ot found. In contrast, DMS attenuated nitric oxide production by macrophage s. High concentrations of DMS, tyrphostin, and 2,5-dihydroxycinnamate showe d cytotoxic effects. PTK inhibitors did not exhibit a significant effect on granule enzyme release induced by IL-1, whereas they attenuated the effect of LPS and fMLP on degranulation. Genistein and tyrphostin decreased the p roduction of IL-8 and GM-CSF in macrophages activated by IL-1, whereas 2,5- dihydroxycinnamate did not affect it. The results suggest that tyrosine kin ases exposed to IL-1, LPS, and fMLP may exert different modulatory actions on macrophage responses. The IL-1-activated macrophage responses, particula rly degranulation, appear to be differently regulated by tyrosine kinases c ompared with the responses activated by LPS and fMLP. (C) 2000 Elsevier Sci ence Inc. All rights reserved.