Regulatory roles of adenylate cyclase and cyclic nucleotide phosphodiesterases 1 and 4 in interleukin-13 production by activated human T cells

We studied the activities of 3 ' ,5 ' -adenosine-cyclic monophosphate (cAMP )- synthesizing adenylate cyclase (AC) and cAMP-hydrolyzing cyclic nucleoti de phosphodiesterase (PDE) in phytohemagglutinin (PHA)- or anti-CD3 plus an ti-CD28-stimulated human T cells, and examined their roles in interleukin-1 3 (IL-13) production. The AC inhibitor MDL 12,330A [cis-N-(2-phenylcyclopen tyl)azacyclotridec-1-en-2-amine hydrochloride] completely blocked PHA or an ti-CD3/CD28-induced IL-13 production. The PDE 1 inhibitor 8-methoxymethyl-3 -isobutyl-1-methylxanthine or the PDE4 inhibitor rolipram partially inhibit ed IL-13 production, and the addition of both resulted in 100 or 85% inhibi tion in PHA- or anti-CD3/CD28-stimulated T cells, respectively. AC in T cel ls was transiently activated 5 min after stimuli, followed by the transient activation of PDE4 at 30 min. PDE1 activity, undetectable in resting T cel ls, was detected 3 hr after stimuli, and then increased gradually. Although PDE1-, 2-, 3-, and 4-independent PDE activity was low (less than or equal to 15% of total), it began to increase 3 hr after anti-CD3/CD28; the increa se was blocked by PDE7 antisense oligonucleotide, and such an increase was not induced by PHA. PHA or anti-CD3/CD28 induced PDE IB mRNA expression, un detectable in resting T cells. PDE4 mRNA level in T cells was not altered b y either stimulus. PDE7 mRNA expression was detected in resting T cells, an d was enhanced by anti-CD3/CD28, but not by PHA. The cAMP level of T cells increased 5 min after stimuli, returned to the basal level at 2 hr, and the n continued to decrease. These results suggest that PHA or anti-CD3/CD28 in itially (less than or equal to5 min) increases cAMP in T cells via AC, then reverses the increase via PDE4 (less than or equal to2 hr), and in the lat er phase (>2 hr) further decreases cAMP via PDEI. Both the time-dependent i ncrease and decrease of cAMP may be required for IL-13 production. (C) 2001 Elsevier Science Inc. All rights reserved.