Rabbit interleukin-1 receptor antagonist. Cloning, expression, functional characterization, and regulation during intestinal inflammation.
Genomic and cDNA clones for rabbit interleukin-1 receptor antagonist (IL-1ra) were isolate based on homology with the human, mouse, and rat IL-1ra gene. A partial genomic clone, obtained by screening a rabbit genomic library, contained coding sequences for the carboxyl-terminal 108 amino acids of rabbit IL-1ra. Two classes of cDNA for rabbit IL-1ra were obtained using RNA from inflamed rabbit colon tissue. One class of cDNA coded for a secreted form of IL-1ra, whereas the other coded for a putative intracellular form of rabbit IL-1ra. The latter form is similar to that isolated from human epithelial cells. A partially synthetic rabbit IL-1ra gene was constructed and expressed in Escherichia coli. The recombinant rabbit IL-1ra was purified to homogeneity by ion exchange chromatography. Its affinity was similar to that of human IL-1ra for the human and mouse type I IL-1 receptor. From the cDNA clone and the purified recombinant protein, specific probes were developed for measuring levels of rabbit IL-1ra mRNA and protein in normal and inflamed rabbit tissues. Unlike IL-1 alpha and IL-1 beta, IL-1RA mRNA and protein were present at detectable levels in normal rabbit colon. During the development of an experimental formalin-immune complex colitis, rabbit IL-1 alpha showed a dramatic increase in tissue levels, consistent with previous results; IL-1ra also increased 3-4-fold. Treatment of colitis rabbits with corticosteroids significantly suppressed neutrophil infiltration, corticosteroid treatment suppressed IL-1ra but not IL-1 alpha mRNA steady-state levels. Our observations demonstrate that IL-1 and IL-1ra synthesis is differentially regulated in healthy and inflamed intestinal tissue.
Cominelli
F
F
Department of Medicine, University of Southern California, School of Medicine, Los Angeles 90033.
Bortolami
M
M
Pizarro
T T
TT
Monsacchi
L
L
Ferretti
M
M
Brewer
M T
MT
Eisenberg
S P
SP
Ng
R K
RK
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D015152:Blotting, Northern; D002460:Cell Line; D003001:Cloning, Molecular; D003092:Colitis / Q000378:metabolism*; D017931:DNA Primers; D018076:DNA, Complementary / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D011817:Rabbits; D051381:Rats; D017472:Receptors, Interleukin-1 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012795:Sialoglycoproteins / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism
D017931:DNA Primers; D018076:DNA, Complementary; C507763:IL1RN protein, human; C507764:Il1rn protein, mouse; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D012795:Sialoglycoproteins; D012313:RNA