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  • Title: Differential expression of inducible nitric oxide synthase and IL-12 between peritoneal and splenic macrophages stimulated with LPS plus IFN-gamma is associated with the activation of extracellular signal-related kinase.
    Author: Zhu YN, Yang YF, Ono S, Zhong XG, Feng YH, Ren YX, Ni J, Fu YF, Tang W, Zuo JP.
    Journal: Int Immunol; 2006 Jun; 18(6):981-90. PubMed ID: 16636012.
    Abstract:
    Resident peritoneal macrophages (pMphi) are found deficient in T cell-stimulating capacity compared with the competent splenic macrophages (sMphi). Macrophages (Mphi)-derived nitric oxide (NO) and IL-12 have been shown to play crucial roles in the interaction between Mphi and T cells. To further understand differential functions between pMphi and sMphi, we focused on the production of NO and IL-12 from LPS plus IFN-gamma-activated Mphi. We demonstrated the differential expression of inducible nitric oxide synthase (iNOS) and IL-12 in pMphi and sMphi with LPS plus IFN-gamma stimulation. pMphi produced high level of NO but low level of IL-12, whereas sMphi produced high level of IL-12 but no NO. Furthermore, we demonstrated that there were no differences in IFN-gamma-induced signal transducer and activator of transcription-1 activation and consequent interferon regulatory factor-1 and interferon consensus sequence-binding protein up-regulation between pMphi and sMphi. Likewise, p38 mitogen-activated protein kinase was activated by LPS with identical kinetics in both pMphi and sMphi. However, LPS-induced extracellular signal-regulated kinase (ERK) activation was prolonged in pMphi comparing with sMphi. Moreover, we demonstrated, using inhibitor selective for ERK cascade (PD98059), that the prolonged ERK activation contributed a positive signal for iNOS expression and a negative signal for IL-12p40 expression in resident pMphi. In addition, anti-IL-10-neutralizing antibody plus indomethacin could abrogate the inhibitory effects of endogenous IL-10 and prostaglandin E2 on the production of IL-12 by resident pMphi possibly through suppressing ERK activation. Taken together, profound difference in ERK activation may account for differential LPS plus IFN-gamma responsiveness between pMphi and sMphi. High production of NO and low production of IL-12 by pMphi may contribute to its deficiency in T cell-stimulating capacity.
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