IL-10-mediated suppression of TNF-α production is independent of its ability to inhibit NFκB activity

Abstract

IL-10 has a well-characterized anti-inflammatory role that includes the suppression of inflammatory cytokine (e.g. TNF-alpha) production by monocytic/macrophage cells. Both transcriptional and post-transcriptional/translational mechanisms have been proposed to explain this process. In this study we observed that IL-10 inhibited nuclear NF kappa B DNA binding activity without affecting I kappa B degradation or translocation of NF kappa B subunits to the nucleus. While the suppression of NF kappa B in 70Z/3 pre-B cells correlated with suppression of NF kappa B transcriptional activity and expression of surface IgM, it did not correlate with the production of TNF-alpha mRNA or protein in RAW 264.7 macrophages. Similar observations in the macrophages were made with a second anti-inflammatory cytokine, IL-4. Therefore we conclude that although IL-10 or IL-4 can suppress NF kappa B activity, this appears to have little effect on the expression of the TNF-alpha gene and is unlikely to be the basis of the anti-inflammatory effects of these cytokines.

Evidence for a Dual Mechanism for IL-10 Suppression of TNF-α Production That Does Not Involve Inhibition of p38 Mitogen-Activated Protein Kinase or NF-κB in Primary Human Macrophages

“…Previously, we have also observed IL-10-mediated inhibition of LPS-induced NF-B activity in the murine cell lines RAW 264.7 and the pre-B cell line 70Z/3. However, the concentrations required to achieve this effect were high (an IC 50 of ϳ100 ng/ml), far in excess of that required to inhibit TNF-␣ expression (an IC 50 of ϳ0.3 ng/ml) (28). However, our studies in human macrophages have failed to show any effect of IL-10 (10 ng/ml) on NF-B activation, as judged by EMSA.…”

Critical Paracrine Interactions Between TNF-α and IL-10 Regulate Lipopolysaccharide-Stimulated Human Choriodecidual Cytokine and Prostaglandin E2 Production

“…In the present study, we observed that IL-10 was produced at the time when TNF-␣ levels were beginning to decrease, and one interpretation of these data is that the effects of IL-10 on PGE 2 production are mediated by its inhibition of TNF-␣ production. It has been reported that the inhibitory effects of IL-10 on TNF-␣ production are independent of its ability to suppress the effects of NF-B activation (54,55). Studies conducted on human monocytes demonstrated that IL-10 can down-regulate surface expression of the TNF receptor while increasing production of the soluble TNF-␣ receptor, in addition to inhibiting the release of TNF-␣ itself (56,57).…”

Viral IL-10 down-regulates the “MHC-I antigen processing operon” through the NF-κB signaling pathway in nasopharyngeal carcinoma cells

“…Furthermore, the expression of the NF-jB transcription factor p65 was not affected by IL-10, nor did IL-10 impact IKB mRNA expression (Dokter et al 1996). Clarke et al (1998) found that IL-10 could not accelerate IKBa/IKBb degradation or inhibit NF-jB nuclear translocation. Clarke et al (1998) speculated that there must be some other mechanism besides IKB degradation and DNA combination.…”

“…The degradation of IjB is necessary for the translocation of NF-jB to the nucleus and subsequent binding to DNA. IKK plays a role in the phosphorylation and degradation of IjB (Clarke et al 1998;Hovsepian et al 2013). We next examined IjB and the phosphorylation of IKKa/b in these cells by Western blot analysis.…”

“…Clarke et al (1998) found that IL-10 could not accelerate IKBa/IKBb degradation or inhibit NF-jB nuclear translocation. Clarke et al (1998) speculated that there must be some other mechanism besides IKB degradation and DNA combination. A comparison of the activity of vIL-10 and results from other groups focused on human IL-10 suggests that vIL-10 may be similar to human IL-10, but there are many differences.…”