Modulation by interferons of the expression of monocyte complement genes

Abstract

Interferons-alpha, -beta and -gamma (IFNs-alpha, -beta and -gamma) stimulated the synthesis of the second complement component (C2), Factor B (B) and C1 inhibitor (C1-inh) by human monocytes in vitro. The degree of increase of the secretion rates of C2, B and C1-inh was dose-dependent and proportional to increases in the abundances of their respective mRNAs. IFN-gamma was the most effective at stimulating monocyte C1-inh synthesis, whereas IFN-alpha and IFN-beta were marginally more effective at stimulating monocyte C2 and B synthesis. Kinetic studies showed that the effect of the IFNs was rapid, with maximum stimulation occurring within 1-2 h for all three proteins. After the removal of IFNs from cultures the C1-inh mRNA abundance remained elevated for over 24 h in IFN-gamma-treated monocytes but returned to control levels within 8 h in IFN-alpha-treated and IFN-beta-treated monocytes. The abundances of C2 mRNA and B mRNA also returned to basal values within 8 h after removal of any of the three cytokines from the cultures. Both IFN-alpha and IFN-beta acted synergistically with IFN-gamma to stimulate synthesis of C1-inh and B. This synergistic effect only occurred when the cytokines were present in the cultures simultaneously. The effects of IFN-gamma plus IFN-alpha or IFN-beta on C2 synthesis appeared to be additive rather than synergistic. IFN-gamma inhibited synthesis of C3 by monocytes, but IFN-alpha and IFN-beta had no effect on the synthesis of this protein. Furthermore, none of the three cytokines had any effect on the expression of actin mRNA in monocytes.

Modulation of complement gene expression by glucocorticoids

“…Monocytes were cultured in the absence or the presence of dexamethasone (1 nM-1 gM) or indomethacin (0.1-10 ,M) for 24 h. Total cellular RNA was then prepared using RNAzol, and Northern blotting and double-dilution dot-blotting techniques were carried out as described previously (Lappin et al, 1990b). With the exception of blots probed with chick lysozyme cDNA, the Northern and double-dilution dot-blots were then hybridized to th-e a-32P-labelled cDNAs, washed to high stringency [0.1 x SSC containing 0.1 % (w/v) SDS at 65°C] (Lappin et al, 1990a). Blots probed with chick lysozyme cDNA were washed to a stringency of 0.5 x SSC containing 0.1 % (w/v) SDS at 65 'C.…”

“…Portions of nuclei (100 1l) were mixed with an equal volume of 10 mM-Tris (pH 8.3)/5 mM-MgCl2/300 mM-KCl/ 0.5 mm each of ATP, GTP and CTP/2 mM-dithiothreitol/ 100 fCi of [a-32PJUTP and incubated for 30 min at 30 'C. RNA was prepared from the nuclei using RNAzol (Lappin et al, 1990a). The [32P]RNA was dissolved in hybridization buffer (106 c.p.m./ml) and hybridization was carried out at 42 'C to cDNA immobilized on Hybond-N membranes.…”

“…The [32P]RNA was dissolved in hybridization buffer (106 c.p.m./ml) and hybridization was carried out at 42 'C to cDNA immobilized on Hybond-N membranes. After highstringency washes (Lappin et al, 1990a), filters were subjected to autoradiography (Fulton et al, 1985…”

Regulation of early complement components C3 and C4 in the synovium

“…In addition, the cytokine regulation of complement component expression depends not only on the individual component but also on the tissue type. Cytokine regulation of C3 expression appears to be very tissue specific (3,4,7,14,16,18,(28)(29)(30)(31). Cytokine regulation of C4 expression has been less extensively studied but has been found to be upregulated in monocytes and scleral fibroblasts in response to IFN-␥ (23,25).…”

Fat–Storing Cells of the Rat Liver Synthesize and Secrete C1–Esterase Inhibitor; Modulation by Cytokines

“…Up-regulation of C1-I synthesis induced by IFN-y was found in human skin fibroblasts (29), human monocytes (44,45) and human hepatoma cells (46,47). Lappin, Birnie and Whaley (48) found a stimulation of C1-I caused by each IFN-a, IFN-P and IFN-y in human monocytes in uitro. Heda et al (49) observed a twofold increase of C1-I-speciiic mRNA in human erythroleukemia cells treated with IFN-y but no alteration after incubation with IFN-a or IFN-P. Katz and Strunk (29) reported that IFN-P2 has, in contrast to IFN-y, no influence on C1-I synthesis in human skin fibroblasts.…”