Double-stranded RNA-induced Inducible Nitric-oxide Synthase Expression and Interleukin-1 Release by Murine Macrophages Requires NF-κB Activation

Abstract

The effects of double-stranded RNA (synthetic polyinosinic-polycytidylic acid; poly(I-C)) on macrophage expression of inducible nitric-oxide synthase (iNOS), production of nitric oxide, and release of interleukin-1 (IL-1) were investigated. Individually, poly(I-C), interferon-γ (IFN-γ), and lipopolysaccharide (LPS) stimulate nitrite production and iNOS expression by RAW 264.7 cells. In combination, the effects of poly(I-C) + IFN-γ are additive, while poly(I-C) does not further potentiate LPS-induced nitrite production. These results suggest that poly(I-C) and LPS may stimulate iNOS expression by similar signaling pathways, which may be independent of pathways activated by IFN-γ. LPS-induced iNOS expression is associated with the activation of NF-κB. We show that inhibition of NF-κB by pyrrolidinedithiocarbamate prevents poly(I-C) + IFN-γ-, poly(I-C) + LPS-, and LPS-induced iNOS expression, nitrite production and IκB degradation by RAW 264.7 cells. The effects of poly(I-C) on iNOS expression appear to be cell-type specific. Poly(I-C), alone or in combination with IFN-γ, does not stimulate, nor does poly(I-C) potentiate, IL-1-induced nitrite production by rat insulinoma RINm5F cells. In addition, we show that the combination of poly(I-C) + IFN-γ stimulates iNOS expression, nitrite production, IκB degradation, and the release of IL-1 by primary mouse macrophages, and these effects are prevented by pyrrolidinedithiocarbamate. These findings indicate that double-stranded RNA, in the presence of IFN-γ, is a potent activator of macrophages, stimulating iNOS expression, nitrite production, and IL-1 release by a mechanism which requires the activation of NF-κB. The effects of double-stranded RNA (synthetic polyinosinic-polycytidylic acid; poly(I-C)) on macrophage expression of inducible nitric-oxide synthase (iNOS), production of nitric oxide, and release of interleukin-1 (IL-1) were investigated. Individually, poly(I-C), interferon-γ (IFN-γ), and lipopolysaccharide (LPS) stimulate nitrite production and iNOS expression by RAW 264.7 cells. In combination, the effects of poly(I-C) + IFN-γ are additive, while poly(I-C) does not further potentiate LPS-induced nitrite production. These results suggest that poly(I-C) and LPS may stimulate iNOS expression by similar signaling pathways, which may be independent of pathways activated by IFN-γ. LPS-induced iNOS expression is associated with the activation of NF-κB. We show that inhibition of NF-κB by pyrrolidinedithiocarbamate prevents poly(I-C) + IFN-γ-, poly(I-C) + LPS-, and LPS-induced iNOS expression, nitrite production and IκB degradation by RAW 264.7 cells. The effects of poly(I-C) on iNOS expression appear to be cell-type specific. Poly(I-C), alone or in combination with IFN-γ, does not stimulate, nor does poly(I-C) potentiate, IL-1-induced nitrite production by rat insulinoma RINm5F cells. In addition, we show that the combination of poly(I-C) + IFN-γ stimulates iNOS expression, nitrite production, IκB degradation, and the release of IL-1 by primary mouse macrophages, and these effects are prevented by pyrrolidinedithiocarbamate. These findings indicate that double-stranded RNA, in the presence of IFN-γ, is a potent activator of macrophages, stimulating iNOS expression, nitrite production, and IL-1 release by a mechanism which requires the activation of NF-κB. Nitric oxide (NO) 1The abbreviations used are: NO, nitric oxide; NOS, nitric-oxide synthase; iNOS, inducible nitric oxide synthase; IL, interleukin; IFN, interferon; AG, aminoguanidine; poly(I-C), polyinosinic-polycytidylic acid; LPS, lipopolysaccharide; PEC, peritoneal exudate cell; PDTC, pyrrolidinedithiocarbamate; ds, double-stranded. 1The abbreviations used are: NO, nitric oxide; NOS, nitric-oxide synthase; iNOS, inducible nitric oxide synthase; IL, interleukin; IFN, interferon; AG, aminoguanidine; poly(I-C), polyinosinic-polycytidylic acid; LPS, lipopolysaccharide; PEC, peritoneal exudate cell; PDTC, pyrrolidinedithiocarbamate; ds, double-stranded. is the product of the five-electron oxidation of l-arginine tol-citrulline catalyzed by the enzyme nitric- oxide synthase (NOS) (1Griffith O.W. Stuehr D.J. Annu. Rev. Phys. 1995; 57: 707-736Crossref PubMed Google Scholar). Three isoforms of NOS have been cloned and characterized: endothelial NOS (eNOS or NOSIII), neuronal NOS (nNOS or NOSI), and inducible NOS (iNOS or NOSII) (2Nathan C. FASEB J. 1992; 6: 3051-3064Crossref PubMed Scopus (4129) Google Scholar, 3Nathan C. Xie Q-W. J. Biol. Chem. 1994; 269: 13725-13728Abstract Full Text PDF PubMed Google Scholar, 4Schmidt H.H.H. FEBS Lett. 1992; 307: 102-107Crossref PubMed Scopus (185) Google Scholar). Collectively, eNOS and nNOS are known as cNOS because their enzymatic activity is regulated by Ca2+ and because these isoforms are constitutively expressed. Nitric oxide, produced in low levels by cNOS isoforms, functions as a signaling molecule associated with diverse biological processes including the regulation of vascular tone and neuronal signaling (4Schmidt H.H.H. FEBS Lett. 1992; 307: 102-107Crossref PubMed Scopus (185) Google Scholar, 5Moncada S. Palmer R.M.J. Higgs E.A. Pharmacol. Rev. 1991; 43: 109-142PubMed Google Scholar, 6Snyder S.H. Bredt D.S. Sci. Am. 1992; 266: 68-77Crossref PubMed Scopus (549) Google Scholar). Nitric oxide, produced in large quantities following induction of iNOS by cytokines or endotoxin, can have cytotoxic or cytostatic effects on target cells (2Nathan C. FASEB J. 1992; 6: 3051-3064Crossref PubMed Scopus (4129) Google Scholar, 7Hibbs Jr., J.B. Taintor R.R. Vavrin Z. Granger D.L. Drapier J.-C. Amber I.J. Lancaster Jr., J.R. Moncada S. Higgs E.A. Nitric Oxide from l-Arginine: A Bioregulatory System. Elsevier Science Publishing Co., New York1990: 189-223Google Scholar) and has recently been implicated as an effector molecule that participates in antiviral responses (8Croen K.D. J. Clin. Invest. 1993; 91: 2446-2452Crossref PubMed Scopus (426) Google Scholar, 9Mannick J.B. Res. Immunol. 1995; 146: 693-697Crossref PubMed Scopus (57) Google Scholar). Viral infection has been shown to stimulate NO production by iNOS in several cell types including mixed glial cell cultures, lymphocytes and monocytes/macrophages (10Koprowski H. Zheng Y.M. Heber-Katz E. Fraser N. Rorke L. Fu Z.F. Hanlon C. Dietzschold B. Proc. Natl. Acad. Sci. U. S. A. 1993; 90: 3024-3027Crossref PubMed Scopus (470) Google Scholar, 11Kreil T.R. Eibl M.M. Virology. 1996; 219: 304-306Crossref PubMed Scopus (109) Google Scholar, 12Melkova Z. Esteban M. J. Immunol. 1995; 155: 5711-5718PubMed Google Scholar, 13Mannick J.B. Asano K. Izumi K. Kieff E. Stamler J.S. Cell. 1994; 79: 1137-1146Abstract Full Text PDF PubMed Scopus (458) Google Scholar). Karupiah et al. (14Karupiah G. Xie Q. Buller M.L. Nathan C. Duarte C. MacMicking J.D. Science. 1993; 261: 1445-1448Crossref PubMed Scopus (747) Google Scholar) have shown NO production is required for IFN-γ inhibition of ectromelia, vaccinia, and herpesvirus replication in mouse macrophages. Also, Bukrinsky et al. (15Burinsky M.I. Nottet H.S.L.M. Schmidtmayerova H. Dubrovshi L. Flanagan C.R. Mullins M.E. Lipton S.A. Gendelman H.E. J. Exp. Med. 1995; 181: 735-745Crossref PubMed Scopus (313) Google Scholar) have shown that infection of human monocytes with human immunodeficiency virus type 1 stimulates iNOS expression and nitric oxide production. Although viral infection stimulates iNOS expression and nitric oxide production, the mechanism by which viral infection stimulates iNOS expression is unknown. NF-κB appears to play a primary role in the transcriptional regulation of iNOS gene expression by macrophages (16Kim H. Lee H.S. Chang K.T. Ko T.H. Baek K.J. Kwon N.S. J. Immunol. 1995; 154: 4741-4748PubMed Google Scholar, 17Mulsch A. Schray-Utz B. Mordvintcez P.I. Hauschildt S. Busse R. FEBS Lett. 1993; 321: 215-218Crossref PubMed Scopus (131) Google Scholar). In unstimulated cells, NF-κB is found as an inactive heterodimer of p50/p65 subunits bound to the NF-κB inhibitor protein, IκB. Upon stimulation, IκB is phosphorylated on specific serine residues which targets IκB for degradation in a ubiquitin-dependent manner (18Baeuerle P.A. Henkel T. Annu. Rev. Immunol. 1994; 12: 141-179Crossref PubMed Scopus (4563) Google Scholar). The antioxidant inhibitors of NF-κB activation, pyrrolidinedithiocarbamate (PDTC) and diethyldithiocarbamic acid, prevent lipopolysaccharide (LPS)- and LPS + IFN-γ-induced iNOS expression and nitrite production by RAW 264.7 cells (17Mulsch A. Schray-Utz B. Mordvintcez P.I. Hauschildt S. Busse R. FEBS Lett. 1993; 321: 215-218Crossref PubMed Scopus (131) Google Scholar), indicating that NF-κB participates in LPS- and LPS + IFN-γ-induced iNOS expression. The active component of a viral infection that stimulates antiviral activities appears to be double-stranded RNA (dsRNA), which accumulates during the replication of many viruses. The purpose of this study was to determine if the activation of macrophages by dsRNA results in iNOS expression, nitric oxide production, and IL-1 release, and if these events are dependent on NF-κB activation. We show that dsRNA (in the form of poly(I-C)), in combination with IFN-γ, is a potent activator of murine macrophages, stimulating iNOS expression, nitric oxide production, and IL-1 release. Furthermore, we show that polyinosinic-polycytidylic acid (poly(I-C))-induced iNOS expression and IL-1 release are associated with the activation of NF-κB. These studies provide direct support for double-stranded RNA as one effector molecule that mediates macrophage activation in an NF-κB-dependent mechanism. Mouse macrophage RAW 264.7 and rat insulinoma RINm5F cells were obtained from Washington University Tissue Culture Support Center. RPMI medium 1640 containing 1×l-glutamine, CMRL-1066 tissue culture medium,l-glutamine, penicillin, streptomycin, and mouse and rat recombinant IFN-γ were from Life Technologies, Inc. Fetal calf serum was obtained from Hyclone (Logan, UT). Male CD-1 mice (20–24 g) were purchased from Harlan (Indianapolis, IN). Aminoguanidine (AG) hemisulfate, LPS (serotype 0111:B4), poly(I-C), and PDTC were from Sigma. [α-32P]dCTP and enhanced chemiluminescence (ECL) reagents were purchased from Amersham Corp. NF-κB consensus oligonucleotide and rabbit anti-IκB-α and IκB-β antiserum were purchased from Santa Cruz Biotechnology, Inc. (Santa Cruz, CA). Horseradish peroxidase-conjugated donkey anti-rabbit IgG was obtained from Jackson ImmunoResearch Laboratories, Inc. (West Grove, PA). Rabbit antiserum specific for the C-terminal 27 amino acids of mouse macrophage iNOS was a gift from Dr. Thomas Misko (G. D. Searle, St. Louis, MO). iNOS and cyclophilin cDNAs were gifts from Dr. Charles Rodi (Monsanto Corporate Research, St. Louis, MO) and Dr. Steve Carroll (Department of Pathology, University of Alabama-Birmingham, reagents were from macrophages exudate cells, were from CD-1 mice by as M.L. J. Immunol. 1993; Google Scholar). the cells were a of CMRL-1066 containing calf penicillin, and in and for an of and cells were by with by of the macrophages with poly(I-C), mouse IFN-γ, and LPS as in the RAW 264.7 and RINm5F cells were from by with were with a of of CMRL-1066 in and for to were by the of poly(I-C), mouse IFN-γ, LPS, and the cells were as In cells were for with PDTC to with poly(I-C), IFN-γ, or RAW 264.7 cells or CD-1 mouse of were for as J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). were by on PubMed Scopus Google Scholar), and to were in and containing and for in primary iNOS, rabbit rabbit containing The were with and for with peroxidase-conjugated donkey anti-rabbit a of The were in and in of iNOS and IκB was by to RAW 264.7 cells were for with the of poly(I-C), mouse IFN-γ, were with and RNA was the CA). RNA was and by a containing RNA was by in to and the were to specific for rat iNOS or cyclophilin J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, T. K. R. K. in New Scholar). The were with [α-32P]dCTP by the from The iNOS to of the rat iNOS The cyclophilin was used as an for RNA and were as J.R. S. M.E. J. Exp. Med. PubMed Scopus Google Scholar). RAW 264.7 cells were for with poly(I-C), LPS, and mouse IFN-γ as were as by al. J. 1994; PubMed Scopus Google Scholar). In cells were by with in of 1 1 and 1 of of the and and on for were by the of of and cell were by The were in of 1 1 and 1 of of the and and for on with was by and the was used for was by the to of was as J. 1994; PubMed Scopus Google Scholar, G. Rodi M.L. 1995; PubMed Google Scholar). The of a double-stranded oligonucleotide containing the consensus for NF-κB Santa with of of of in a containing 1 1 and and were for were on in a S. R. K. in New Scholar). The were to and to production was by of culture medium with of J. J.S. PubMed Scopus Google Scholar). The was and nitrite were from a nitrite IL-1 release from mouse was the RINm5F cell as by et al. J.R. M. 1996; Scopus Google Scholar). were a were of RAW 264.7 cell to cyclophilin was a and were and for the of LPS and IFN-γ alone mouse macrophage RAW 264.7 cells, to iNOS and nitric oxide; production of nitric oxide in to a combination of LPS + IFN-γ. determine if dsRNA stimulates macrophage activation, the effects of the dsRNA poly(I-C), alone or in combination with LPS and IFN-γ, on nitrite production by RAW 264.7 cells were shown in 1 a a of RAW 264.7 cells with poly(I-C) or IFN-γ stimulates a and in nitrite production, poly(I-C) does not appear to further the of nitrite produced in to LPS, in combination with IFN-γ, poly(I-C) stimulates an in nitrite production by RAW 264.7 cells. The levels of nitrite production in to poly(I-C) + IFN-γ are similar in to the effects of IFN-γ + LPS on RAW 264.7 cell nitrite production. AG, a inhibitor of iNOS Chang K. Lancaster Jr., J.R. J.R. M.L. 1991; Scopus Google Scholar), prevents not not poly(I-C) + IFN-γ-, poly(I-C) + LPS-, and LPS + IFN-γ-induced nitrite production by RAW 264.7 cells. The effects of poly(I-C) on nitrite production by RAW 264.7 cells are shown in 1 poly(I-C) stimulates the production of nitrite by RAW 264.7 cells from to The of poly(I-C) on nitrite production by RAW 264.7 cells is of IFN-γ alone stimulates nitrite production by RAW 264.7 cells, and this is in a manner by + IFN-γ stimulates an in nitrite production, which is poly(I-C) + IFN-γ. These findings indicate that poly(I-C) is of stimulating RAW 264.7 cell production of nitric oxide; the levels are enhanced in the presence of IFN-γ. In addition, these findings indicate that poly(I-C) does not further the levels of nitrite produced in to The effects of poly(I-C), in the presence or of IFN-γ and LPS, on iNOS in RAW 264.7 cells was by Individually, poly(I-C) and IFN-γ stimulate the expression of levels of iNOS following a and as by 1 the combination of poly(I-C) + IFN-γ stimulates a in iNOS to nitrite production shown in 1 a poly(I-C) does not further the levels of iNOS in to LPS for Also, iNOS in to poly(I-C) + IFN-γ is that in to LPS + IFN-γ. The effects of poly(I-C), alone or in combination with LPS and IFN-γ, on iNOS expression 1 are similar to the effects of these on iNOS RAW 264.7 cells low levels of iNOS in to poly(I-C) or iNOS expression is in to the combination of poly(I-C) + IFN-γ. appears to the of iNOS expression in to the in iNOS expression is by and appears to in of these not the results in 1 that poly(I-C) stimulates iNOS expression and nitrite production, and that IFN-γ the effects of poly(I-C) on RAW 264.7 cells. poly(I-C) does not further LPS-induced nitrite production by RAW cells and nitrite production in to poly(I-C) and IFN-γ are is that the signaling activated by and associated with iNOS expression may be similar or to the activated by of the signaling that participates in LPS-induced iNOS expression is the transcriptional NF-κB. studies have shown that the antioxidant PDTC, a potent inhibitor of NF-κB activation R. K. P.A. Res. 1992; PubMed Scopus Google Scholar), prevents LPS-induced iNOS expression by RAW 264.7 cells (17Mulsch A. Schray-Utz B. Mordvintcez P.I. Hauschildt S. Busse R. FEBS Lett. 1993; 321: 215-218Crossref PubMed Scopus (131) Google Scholar). determine if NF-κB participates in nitrite production and iNOS expression, RAW 264.7 cells were for with IFN-γ and LPS were and the cells were for shown in a PDTC prevents poly(I-C) + IFN-γ-, LPS-, and LPS + nitrite production by RAW 264.7 cells. with effects on nitrite production, PDTC not poly(I-C) + IFN-γ-, LPS-, and LPS + iNOS expression These findings provide that poly(I-C) (in the presence or of stimulates iNOS expression by a mechanism that is associated with the activation of NF-κB. determine if dsRNA we have the effects of poly(I-C) on NF-κB by shown in of RAW 264.7 cells for with poly(I-C) stimulates the of as by the of the containing the consensus for NF-κB The effects of poly(I-C) are similar to the effects of LPS on NF-κB activation by RAW 264.7 cells, and of RAW 264.7 cells with IFN-γ or LPS does not further potentiate NF-κB activation. for the and NF-κB oligonucleotide the of the and of antiserum specific for the and of NF-κB in the results in a further in the of the NF-κB not further the role of poly(I-C) in NF-κB activation, the effects of poly(I-C), alone and in combination with LPS and IFN-γ, on IκB degradation was shown in of RAW 264.7 cells for with poly(I-C) results in the degradation of of degradation is prevented by of RAW 264.7 cells for with PDTC to the of In combination, poly(I-C) + IFN-γ stimulate degradation to levels similar in to the effects of poly(I-C), LPS, and LPS + poly(I-C), and this is prevented by Also, PDTC LPS- and LPS + We have the effects of poly(I-C), LPS, and IFN-γ, alone and in combination, on IκB-β degradation and have obtained results to shown in for not These findings indicate that poly(I-C) stimulates NF-κB by a mechanism that is associated with the degradation of IκB. The insulinoma RINm5F cell a of that iNOS and nitric oxide in to IL-1 Lancaster Jr., J.R. M.L. J. Clin. Invest. 1992; 90: PubMed Scopus Google Scholar). In addition, IL-1-induced nitric oxide production by RINm5F cells appears to the activation of NF-κB as PDTC and diethyldithiocarbamic acid NF-κB activation and iNOS expression G. Rodi M.L. 1995; PubMed Google Scholar, M. D.L. Res. 1995; PubMed Scopus Google Scholar). we have shown that IFN-γ IL-1-induced iNOS expression and nitrite production by RINm5F cells of IL-1 that alone not stimulate iNOS expression J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). iNOS expression and nitrite production by RAW 264.7 cells appears to the activation of and IL-1-induced iNOS expression by RINm5F cells requires NF-κB activation, the effects of poly(I-C), alone and in combination with IL-1 and IFN-γ, on nitrite production by RINm5F cells were of RINm5F cells with IL-1 stimulates a in nitrite production following a poly(I-C) does not stimulate nitrite production, nor does further potentiate IL-1-induced nitrite production by RINm5F cells. Individually, IFN-γ nor IL-1 stimulate nitrite production by RINm5F in combination these cytokines stimulate the production of nitrite to levels to the levels by of IL-1 In combination with IFN-γ or of IL-1 poly(I-C) does not stimulate nitrite production by RINm5F cells. does not further potentiate IL-1 or + IFN-γ-induced nitrite production not These findings suggest that the of poly(I-C) on iNOS expression and nitrite production may be cell-type specific. In to RAW 264.7 cells, mouse macrophages a combination of IFN-γ + for iNOS expression and nitric oxide production. The effects of dsRNA on primary macrophage activation was by mouse with poly(I-C) in the presence or of IFN-γ and poly(I-C), IFN-γ, nor LPS stimulate nitrite production or iNOS expression by mouse a in combination, poly(I-C) + IFN-γ stimulate the expression of iNOS and the production of nitrite to levels to the effects of IFN-γ + The production of nitrite in to poly(I-C) + IFN-γ, or LPS + IFN-γ is prevented by the iNOS inhibitor the combination of poly(I-C) + LPS does not stimulate iNOS expression or nitrite production by is with the of poly(I-C) to potentiate LPS-induced nitrite production by RAW 264.7 cells. These findings indicate that a combination of poly(I-C) and IFN-γ primary macrophages stimulating iNOS expression and nitrite production. activation is by the release of levels of the the RINm5F cell J.R. M. 1996; Scopus Google Scholar) we have the effects of poly(I-C) on IL-1 release by PEC, and IL-1 release requires NF-κB activation. poly(I-C) IFN-γ or LPS not stimulate IL-1 release by following a a the of poly(I-C) + IFN-γ and LPS + IFN-γ stimulate the release of IL-1 to levels that are that of of mouse for with PDTC poly(I-C) + IFN-γ-induced IL-1 release, a role for NF-κB activation in IL-1 release by further the role of poly(I-C) on NF-κB activation in mouse PEC, the effects of poly(I-C), alone and in combination with LPS and IFN-γ, on degradation was to RAW 264.7 cells, poly(I-C), LPS, poly(I-C) + IFN-γ and LPS + poly(I-C) the degradation of of and these effects are prevented by PDTC PDTC prevents poly(I-C) + and LPS + IFN-γ-induced nitrite by CD-1 mouse not These findings IκB degradation and NF-κB activation in poly(I-C) + IFN-γ-induced nitrite production and IL-1 release by mouse macrophages. to viral infection is the expression of iNOS and the production of nitric oxide (8Croen K.D. J. Clin. Invest. 1993; 91: 2446-2452Crossref PubMed Scopus (426) Google Scholar, 9Mannick J.B. Res. Immunol. 1995; 146: 693-697Crossref PubMed Scopus (57) Google Scholar). The mechanism by which viral infection stimulates iNOS expression is unknown. The active component of viral infection appears to be which accumulates during replication of many Pharmacol. 1992; PubMed Scopus Google Scholar). was in that with dsRNA macrophages cytotoxic to target cells in a manner similar to the of and A R. New Biol. PubMed Scopus (313) Google Scholar). inhibition of and expression of type are associated with the antiviral activity in cells Pharmacol. 1992; PubMed Scopus Google Scholar, P.I. of and Elsevier Science New Scholar). In the the effects of dsRNA on macrophage activation and the mechanism by which dsRNA macrophages have been of RAW 264.7 cells with poly(I-C) stimulates iNOS expression and nitrite production. IFN-γ iNOS expression and nitrite production, while LPS does not further potentiate nitrite production by RAW 264.7 cells. poly(I-C) does not stimulate iNOS expression by primary macrophages in combination with IFN-γ, poly(I-C) stimulates iNOS expression and levels of nitrite production. In addition, poly(I-C) + IFN-γ stimulate IL-1 release by mouse to the of LPS to nitrite production by RAW 264.7 cells, poly(I-C), in combination with LPS, does not stimulate iNOS expression, nitrite production, or IL-1 release by mouse appears to stimulate iNOS expression by a mechanism similar to that by LPS because the effects of LPS and poly(I-C) are not additive, while RAW 264.7 cell expression of iNOS in to poly(I-C) and IFN-γ are LPS-induced iNOS expression by RAW 264.7 cells requires the activation of NF-κB (17Mulsch A. Schray-Utz B. Mordvintcez P.I. Hauschildt S. Busse R. FEBS Lett. 1993; 321: 215-218Crossref PubMed Scopus (131) Google Scholar). studies show that and poly(I-C) + IFN-γ-induced iNOS expression, nitrite production, and IκB degradation by RAW 264.7 cells is prevented by the NF-κB inhibitor In addition, PDTC poly(I-C) + IFN-γ-induced iNOS expression, nitrite production not IκB degradation and IL-1 release by These findings indicate that IκB degradation and NF-κB in and poly(I-C) + IFN-γ-induced iNOS expression by RAW 264.7 cells and mouse IκB is phosphorylated on specific serine and is this that appears to direct degradation of IκB (18Baeuerle P.A. Henkel T. Annu. Rev. Immunol. 1994; 12: 141-179Crossref PubMed Scopus (4563) Google Scholar). The is one that may IκB in to dsRNA and viral is known to by J. J. Biol. Chem. Full Text PDF PubMed Google Scholar), and in studies have shown that IκB is one for this A. J. J. J. Proc. Natl. Acad. Sci. U. S. A. 1994; 91: PubMed Scopus Google Scholar). We are the effects of poly(I-C) on in RAW 264.7 cells and The effects of poly(I-C) on iNOS expression appear to be cell-type specific. poly(I-C), alone and in combination with IFN-γ, stimulates iNOS expression by RAW 264.7 cells, poly(I-C), alone or in combination with IFN-γ, does not nor does IL-1-induced nitrite production by the cell studies have shown that IL-1 stimulates levels of iNOS expression and nitric oxide production by RINm5F cells, and the of IL-1 are by IFN-γ J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, Lancaster Jr., J.R. M.L. J. Clin. Invest. 1992; 90: PubMed Scopus Google Scholar). IL-1-induced iNOS expression by RINm5F cells is associated with IκB degradation A. and NF-κB G. Rodi M.L. 1995; PubMed Google Scholar, M. D.L. Res. 1995; PubMed Scopus Google Scholar). stimulates IκB degradation in RINm5F cells not poly(I-C) does not stimulate iNOS expression or nitrite production. These results indicate that transcriptional in to NF-κB are required for IL-1-induced iNOS expression by RINm5F cells. The antiviral in cells the expression of type 1 and the inhibition of to the of Pharmacol. 1992; PubMed Scopus Google P.I. of and Elsevier Science New Scholar). A of studies have implicated a dsRNA as the activator of the antiviral in cells R. New Biol. PubMed Scopus (313) Google Scholar, T. J. J. PubMed Google Scholar, Res. PubMed Scopus Google Scholar). Also, viral infection stimulates iNOS expression by target cells, and nitric oxide appears to in the inhibition of viral replication (8Croen K.D. J. Clin. Invest. 1993; 91: 2446-2452Crossref PubMed Scopus (426) Google Scholar, 9Mannick J.B. Res. Immunol. 1995; 146: 693-697Crossref PubMed Scopus (57) Google Scholar, H. Zheng Y.M. Heber-Katz E. Fraser N. Rorke L. Fu Z.F. Hanlon C. Dietzschold B. Proc. Natl. Acad. Sci. U. S. A. 1993; 90: 3024-3027Crossref PubMed Scopus (470) Google Scholar, 11Kreil T.R. Eibl M.M. Virology. 1996; 219: 304-306Crossref PubMed Scopus (109) Google Scholar, 12Melkova Z. Esteban M. J. Immunol. 1995; 155: 5711-5718PubMed Google Scholar, 13Mannick J.B. Asano K. Izumi K. Kieff E. Stamler J.S. Cell. 1994; 79: 1137-1146Abstract Full Text PDF PubMed Scopus (458) Google Scholar, G. Xie Q. Buller M.L. Nathan C. Duarte C. MacMicking J.D. Science. 1993; 261: 1445-1448Crossref PubMed Scopus (747) Google Scholar, M.I. Nottet H.S.L.M. Schmidtmayerova H. Dubrovshi L. Flanagan C.R. Mullins M.E. Lipton S.A. Gendelman H.E. J. Exp. Med. 1995; 181: 735-745Crossref PubMed Scopus (313) Google Scholar). In this is which NF-κB as one transcriptional that is activated and participates in the antiviral by of macrophages with In addition, following dsRNA (in the presence of may play a primary role in the antiviral activities of macrophages. We for