Macrophages and Tissue Injury: Agents of Defense or Destruction?

Department of Pharmacology and Toxicology, Rutgers University, Piscataway, New Jersey 08854, USA.
Annual Review of Pharmacology (Impact Factor: 18.37). 11/2010; 51(1):267-88. DOI: 10.1146/annurev.pharmtox.010909.105812
Source: PubMed


The past several years have seen the accumulation of evidence demonstrating that tissue injury induced by diverse toxicants is due not only to their direct effects on target tissues but also indirectly to the actions of resident and infiltrating macrophages. These cells release an array of mediators with cytotoxic, pro- and anti-inflammatory, angiogenic, fibrogenic, and mitogenic activity, which function to fight infections, limit tissue injury, and promote wound healing. However, following exposure to toxicants, macrophages can become hyperresponsive, resulting in uncontrolled or dysregulated release of mediators that exacerbate acute tissue injury and/or promote the development of chronic diseases such as fibrosis and cancer. Evidence suggests that the diverse activity of macrophages is mediated by distinct subpopulations that develop in response to signals within their microenvironment. Understanding the precise roles of these different macrophage populations in the pathogenic response to toxicants is key to designing effective treatments for minimizing tissue damage and chronic disease and for facilitating wound repair.

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    • "Host-defense cells generate a diversity of lipid-derived mediators that are involved in the response to tissue damage and inflammation: for example, they are a major source of eicosanoids such as prostaglandin E 2 , which cause local vasodilation and nociceptor sensitization, and act as signals to recruit blood-borne immune cells to injury sites (Laskin et al., 2011). However, a growing body of evidence indicates that host-defense cells can also release bioactive lipids that attenuate rather than instigate pain and inflammation. "
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    ABSTRACT: Macrophages are multi-faceted phagocytic effector cells that derive from circulating monocytes and undergo differentiation in target tissues to regulate key aspects of the inflammatory process. Macrophages produce and degrade a variety of lipid mediators that stimulate or suppress pain and inflammation. Among the analgesic and anti-inflammatory lipids released from these cells are the fatty acid ethanolamides (FAEs), which produce their effects by engaging nuclear peroxisome proliferator activated receptor-α (PPAR-α). Two members of this lipid family, palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), have recently emerged as important intrinsic regulators of nociception and inflammation. These substances are released from the membrane precursor, N-acylphosphatidylethanolamine (NAPE), by the action of a NAPE-specific phospholipase D (NAPE-PLD), and in macrophage are primarily deactivated by the lysosomal cysteine amidase, N-acylethanolamine acid amidase (NAAA). NAPE-PLD and NAAA regulate FAE levels, exerting a tight control over the ability of these lipid mediators to recruit PPAR-α and attenuate the inflammatory response. This review summarizes recent findings on the contribution of the FAE-PPAR-α signaling complex in inflammation, and on NAAA inhibition as a novel mechanistic approach to treat chronic inflammatory disorders.
    Critical Reviews in Biochemistry and Molecular Biology 11/2015; DOI:10.3109/10409238.2015.1092944 · 7.71 Impact Factor
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    • "Findings that MMP inhibitors such as doxycyline and illomastat attenuate SM-induced respiratory lesions in rats, demonstrate the importance of proteases in vesicant-induced lung injury (Anderson et al., 2009). Alternatively activated antiinflammatory/wound repair M2 macrophages play a role in the resolution of lung injury [reviewed in Laskin et al., 2011]. Exaggerated responses of M2 macrophages are thought to contribute to the development of fibrosis. "
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    ABSTRACT: Exposure of humans and animals to vesicants, including sulfur mustard (SM) and nitrogen mustard (NM), causes severe and debilitating damage to the respiratory tract. Both acute and long term pathological consequences are observed in the lung following a single exposure to these vesicants. Evidence from our laboratories and others suggest that macrophages and inflammatory mediators they release play an important role in mustard-induced lung injury. In this paper, the pathogenic effects of SM and NM on the lung are reviewed, along with the potential role of inflammatory macrophages and mediators they release in mustard-induced pulmonary toxicity.
    Toxicology Letters 10/2015; DOI:10.1016/j.toxlet.2015.10.011 · 3.26 Impact Factor
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    • "However, NK cells seem to play a role in pancreas resistance to CVB infection [43] but do not alter the cardiac viral clearance after its depletion [44], or inhibition [45]. Taken together , it seems that in CVB3-induced myocarditis, cardiac infiltrating macrophages have a major role in the early clearance of infected cardiomyocytes in accordance with the assigned dual role of macrophages not only limiting tissue injury but also increasing tissue damage [46]. The fact that macrophage-depleted mice also presented lower body weight suggests that besides their role in chronic myocarditis, macrophages might have additional roles, controlling viral replication and/or tissue damage in other organs. "

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