Matricellular Protein CCN1 Activates a Proinflammatory Genetic Program in Murine Macrophages

Abstract

CCN1 (CYR61) is a matricellular protein that is highly expressed at sites of inflammation and wound repair. In these contexts, CCN1 can modify the activities of specific cytokines, enabling TNF-α to be cytotoxic without blocking NF-κB activity and enhancing the apoptotic activity of Fas ligand and TRAIL. In this paper, we show that CCN1 supports the adhesion of macrophages through integrin αMβ2 and syndecan-4, activates NFκB-mediated transcription, and induces a proinflammatory genetic program characteristic of classically activated M1 macrophages that participates in Th1 responses. The effects of CCN1 include upregulation of cytokines (TNF-α, IL-1α, IL-1β, IL-6, and IL-12b), chemokines (MIP-1α; MCP-3; growth-related oncogenes 1 and 2; and inflammatory protein 10), and regulators of oxidative stress and complement (inducible NO synthase and C3) and downregulation of specific receptors (TLR4 and IL-10Rβ) and anti-inflammatory factors (TGF-β1). CCN1 regulates this genetic program through at least two distinct mechanisms: an immediate-early response resulting from direct activation of NF-κB by CCN1, leading to the synthesis of cytokines including TNF-α and inflammatory protein 10; and a delayed response resulting from CCN1-induced TNF-α, which acts as an autocrine/paracrine mediator to activate the expression of other cytokines including IL-1β and IL-6. These results identify CCN1 as a novel component of the extracellular matrix that activates proinflammatory genes in macrophages, implicating its role in regulating macrophage function during inflammation.

Postoperative Accumulation of Cyr61/CCN1 in Surgical Wound Fluid Precedes Cytokine Activation and is Disparate from Systemic Alterations

“…Studies have connected deregulations of CCN1 to a variety of diseases associated with chronic inflammation, such as rheumatoid arthritis [27], atherosclerosis [28], infectious myocarditis [29], inflammatory bowel disease [30], chronic obstructive pulmonary disorder [31] and several cancers [7]. However, experimental studies have also suggested a role for CCN1 in acute inflammation by demonstrating its ability to promote cytokine secretion [21,32] and support the adhesion of platelets [33], and monocytes/macrophages [21,34]. Acute tissue injury elicits a remarkably conserved response consisting of an instant hemostatic reaction followed by acute inflammation, which is essential for successful tissue recovery [35].…”

“…All of these factors, which stimulate the aforementioned cell types, may have contributed cumulatively to the increased CCN1 levels in the drained fluid. Immune cells are especially interesting candidates because of their potential roles as both producers and target cells of CCN1 [21,36].…”

“…Attempting to identify the potential mechanisms behind these regulations, we demonstrated that CCN1 expression in parenchymal cells is sensitive to cytokine exposure in vitro. However, accumulating evidence now suggests that CCN1 may also possess pro-inflammatory capabilities [19][20][21], indicating that this immediate early gene may be involved in the initial promotion of the inflammatory response. The present study was undertaken to investigate whether CCN1 is activated at local sites of acute tissue injury in humans and to assess its temporal relationship with the activation of the inflammatory response.…”

CCN4 Regulates Vascular Smooth Muscle Cell Migration and Proliferation

“…These authors show that CCN1 stimulates reactive oxygen species (ROS) generation and suggest that the high and sustained levels of ROS induced by CCN1/TNF-α result in the oxidative inactivation of JNK phosphatases, leading to the persistent activation of JNK and subsequent cell death (Bai et al, 2010). Although the induction of CCN family members by pro-inflammatory cytokines has already been reported, the novel result of this study is that a combination of TNF-α and CCN4 induce VSMCs proliferation; that is to say, CCN4 expression was induced by TNF-α stimulation in primary VSMCs.…”

CCN1 Promotes VEGF Production in Osteoblasts and Induces Endothelial Progenitor Cell Angiogenesis by Inhibiting miR-126 Expression in Rheumatoid Arthritis

“…The CIA mouse model protocol followed that as detailed in previously published work. (31,32) First, 0.1 mL of an emulsion containing 100 mg of bovine type II collagen (CII) dissolved at a concentration of 2 mg/mL in 0.1 M acetic acid and complete Freund's adjuvant was injected intradermally into the base of the tail. Second, 2 weeks after the primary immunization, a booster injection of 100 mg CII dissolved and emulsified 1:1 with incomplete Freund's adjuvant was administered into the hind paw.…”