The combination of CRP isoforms with oxLDL decreases TNF-α and IL-6 release by U937-derived macrophages

Krayem, Imtissal; Bazzi, Samer; Karam, Marc

doi:10.3892/br.2017.949

Cited by 14 publications

(14 citation statements)

References 34 publications

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“…Such effects might be mediated by the downregulation of cytokines known to induce IFN-γ production, including IL-12 and IL-18 (27,28). This was further supported by the increased levels of IL-4, which has been previously demonstrated to suppress IL-12/IL-18 secretion (25,26), under most single and combined treatments, the least effect being observed following treatment with oxLDL.…”

Section: Discussionmentioning

confidence: 64%

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<em>In vitro</em> effects of azide‑containing human CRP isoforms and oxLDL on U937‑derived macrophage production of atherosclerosis‑related cytokines

et al. 2020

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Atherosclerosis is an inflammatory chronic disease of the arterial wall. Monomeric (m) and pentameric (p) C-reactive protein (CRP) and oxidized low density lipoproteins (oxLDL) seem to affect the pattern of cytokine production by macrophages, thus playing an important role in atherogenesis. Azide, the commercial preservative of CRP, may influence its action in vitro. The present study aimed to determine the effects of both isoforms of azide-containing CRP (mCRP and pCRP) with and without oxLDL on cytokine production by U937-derived macrophages. U937 monocytes were cultured and differentiated into macrophages and treated with mCRP, pCRP, oxLDL and azide individually and in combination. ELISA were performed to measure the levels of interferon-γ (IFN-γ), interleukin (IL)-4, IL-6, IL-10 and tumor necrosis factor (TNF)-α in culture supernatants collected from U937-derived macrophages following their respective treatments. Most single and combined treatments, especially in triple combination, were able to downregulate the levels of IFN-γ and IL-6 compared with control untreated cells, whilst the combination of mCRP and pCRP increased IL-4 levels. Regarding IL-10, except for an increase induced by mCRP, no significant effect was caused by any treatment compared with the control. On the other hand, the levels of TNF-α were not significantly affected by any treatment except for a decreasing trend that was observed with mCRP/oxLDL treatment compared with control. By contrast, double azide caused a significant decrease in the levels of IFN-γ and IL-6. The results of the present study indicated that mCRP, pCRP, oxLD and possibly azide, individually or in different combinations, had the tendency to upregulate the expression of IL-4 and to downregulate that of the pro-atherogenic cytokines, IFN-γ and IL-6, suggesting that the intima microenvironment serves a crucial role in atherogenesis.

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Section: Discussionmentioning

confidence: 64%

“…SA1x and SA2x served as single and double concentration controls for sodium azide present in mCRP and mCRP/pCRP, respectively. The adopted concentrations were chosen based on previous literature (26).…”

Section: Differentiation Of U937 Cells Into Macrophages Human Monocymentioning

confidence: 99%

<em>In vitro</em> effects of azide‑containing human CRP isoforms and oxLDL on U937‑derived macrophage production of atherosclerosis‑related cytokines

et al. 2020

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“…The induction of inflammation in U937-derived macrophages in vitro is a reliable indication of the activity of mCRP, and increases in IL-6 and TNF-α are attributed to detrimental tissue-related complications ( 20 ). Here we showed that both acetylcholine and nicotine were able to attenuate, significantly, both TNF-α and IL-6 activity, whilst neither tacrine nor the targeting antibodies were effective.…”

Section: Discussionmentioning

confidence: 99%

Acetylcholine Inhibits Monomeric C-Reactive Protein Induced Inflammation, Endothelial Cell Adhesion, and Platelet Aggregation; A Potential Therapeutic?

et al. 2018

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Objectives: In this study, we examined the possibility of using targeted antibodies and the potential of small molecular therapeutics (acetylcholine, nicotine and tacrine) to block the pro-inflammatory and adhesion-related properties of monomeric C-reactive protein (mCRP).Methods: We used three established models (platelet aggregation assay, endothelial leucocyte binding assay and monocyte inflammation via ELISA and Western blotting) to assess the potential of these therapeutics.Results: The results of this study showed that monocyte induced inflammation (raised tumor necrosis factor-alpha-TNF-α) induced by mCRP was significantly blocked in the presence of acetylcholine and nicotine, whilst tacrine and targeted antibodies (clones 8C10 and 3H12) had less of or no significant effects. Western blotting confirmed the ability of acetylcholine to inhibit mCRP-induced cell signaling phosphorylation of extracellular signal regulated kinase 1/2 (ERK1/2), p38 and nuclear factor-kappa B (NF-κB). There was no evidence of direct binding between small molecules and mCRP. mCRP also induced endothelial cell-monocyte adhesion in a dose dependent fashion, however, both acetylcholine and nicotine as well as targeting antibodies notably inhibited adhesion. Finally, we investigated their effects on mCRP-induced platelet aggregation. All three small molecules significantly attenuated platelet aggregation as did the antibody 8C10, although 3H12 had a weaker effect.Discussion: Acetylcholine and to a lesser extent nicotine show potential for therapeutic inhibition of mCRP-induced inflammation and cell and platelet adhesion. These results highlight the potential of targeted antibodies and small molecule therapeutics to inhibit the binding of mCRP by prevention of membrane interaction and subsequent activation of cellular cascade systems, which produce the pro-inflammatory effects associated with mCRP.

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“…When CRP levels become elevated in atheroma, this leads to the induction of IL-6 by macrophages indicating that CRP may have a direct effect on IL-6 release ( 99 ). Krayem et al ( 100 ) found that a combination of mCRP, nCRP, and oxLDL decreases IL-6 production in a model of atherosclerosis. This triple combination suggests that nCRP might downregulate the IL-6 release by macrophages that have been stimulated by both mCRP and oxLDL.…”

Section: Crp Isoforms and Inflammatory Cytokinesmentioning

confidence: 99%

“…However, there is some contradictory evidence showing a potential inhibitory effect of CRP on TNF-α production, suggesting that there could be a negative feedback mechanism whereby elevated levels of CRP inhibit further stimulation of CRP by reducing the TNF-α production ( 114 ). A combination of mCRP, nCRP, and oxLDL also causes a decrease in both TNF-α and IL-6 production in a macrophage model of atherosclerosis ( 100 ). This triple combination suggests that nCRP might downregulate TNF-α and IL-6 production by macrophages stimulated by both mCRP and oxLDL.…”

Section: Crp Isoforms and Inflammatory Cytokinesmentioning

confidence: 99%

Role of C-Reactive Protein at Sites of Inflammation and Infection

2018

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C-reactive protein (CRP) is an acute inflammatory protein that increases up to 1,000-fold at sites of infection or inflammation. CRP is produced as a homopentameric protein, termed native CRP (nCRP), which can irreversibly dissociate at sites of inflammation and infection into five separate monomers, termed monomeric CRP (mCRP). CRP is synthesized primarily in liver hepatocytes but also by smooth muscle cells, macrophages, endothelial cells, lymphocytes, and adipocytes. Evidence suggests that estrogen in the form of hormone replacement therapy influences CRP levels in the elderly. Having been traditionally utilized as a marker of infection and cardiovascular events, there is now growing evidence that CRP plays important roles in inflammatory processes and host responses to infection including the complement pathway, apoptosis, phagocytosis, nitric oxide (NO) release, and the production of cytokines, particularly interleukin-6 and tumor necrosis factor-α. Unlike more recent publications, the findings of early work on CRP can seem somewhat unclear and at times conflicting since it was often not specified which particular CRP isoform was measured or utilized in experiments and whether responses attributed to nCRP were in fact possibly due to dissociation into mCRP or lipopolysaccharide contamination. In addition, since antibodies for mCRP are not commercially available, few laboratories are able to conduct studies investigating the mCRP isoform. Despite these issues and the fact that most CRP research to date has focused on vascular disorders, there is mounting evidence that CRP isoforms have distinct biological properties, with nCRP often exhibiting more anti-inflammatory activities compared to mCRP. The nCRP isoform activates the classical complement pathway, induces phagocytosis, and promotes apoptosis. On the other hand, mCRP promotes the chemotaxis and recruitment of circulating leukocytes to areas of inflammation and can delay apoptosis. The nCRP and mCRP isoforms work in opposing directions to inhibit and induce NO production, respectively. In terms of pro-inflammatory cytokine production, mCRP increases interleukin-8 and monocyte chemoattractant protein-1 production, whereas nCRP has no detectable effect on their levels. Further studies are needed to expand on these emerging findings and to fully characterize the differential roles that each CRP isoform plays at sites of local inflammation and infection.

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The combination of CRP isoforms with oxLDL decreases TNF-α and IL-6 release by U937-derived macrophages

Cited by 14 publications

References 34 publications

<em>In vitro</em> effects of azide‑containing human CRP isoforms and oxLDL on U937‑derived macrophage production of atherosclerosis‑related cytokines

<em>In vitro</em> effects of azide‑containing human CRP isoforms and oxLDL on U937‑derived macrophage production of atherosclerosis‑related cytokines

Acetylcholine Inhibits Monomeric C-Reactive Protein Induced Inflammation, Endothelial Cell Adhesion, and Platelet Aggregation; A Potential Therapeutic?

Role of C-Reactive Protein at Sites of Inflammation and Infection

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The combination of CRP isoforms with oxLDL decreases TNF-α and IL-6 release by U937-derived macrophages

Cited by 14 publications

References 34 publications

<em>In&nbsp;vitro</em> effects of azide‑containing human CRP isoforms and oxLDL on U937‑derived macrophage production of atherosclerosis‑related cytokines

<em>In&nbsp;vitro</em> effects of azide‑containing human CRP isoforms and oxLDL on U937‑derived macrophage production of atherosclerosis‑related cytokines

Acetylcholine Inhibits Monomeric C-Reactive Protein Induced Inflammation, Endothelial Cell Adhesion, and Platelet Aggregation; A Potential Therapeutic?

Role of C-Reactive Protein at Sites of Inflammation and Infection

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<em>In vitro</em> effects of azide‑containing human CRP isoforms and oxLDL on U937‑derived macrophage production of atherosclerosis‑related cytokines

<em>In vitro</em> effects of azide‑containing human CRP isoforms and oxLDL on U937‑derived macrophage production of atherosclerosis‑related cytokines