This information may help in furthering our knowledge on how to develop better therapeutic interventions, and perhaps manage possible side effects when treating impaired wounds. METHODS Dermal excisional wound model Animals were housed at the University of California, Riverside (UCR) vivarium. significant Vc-MMAD increase in the eicosanoids 11-, 12-, and 15-hydroxyeicosa-tetranoic acid, and the proinflammatory leukotrienes (LTD4 and LTE) and prostaglandins (PGE2 and PGF2are elevated shortly after wounding and in some cases during healing. To determine whether they have an impact in platelet aggregation and hemostasis, we tested LIGHT?/? mouse wounds for these two parameters and found that, indeed, platelet aggregation and hemostasis are enhanced in these mice when compared with the control C57BL/6 mice. Understanding lipid signaling in impaired wounds can potentially lead to development of new therapeutics or in using existing nonsteroidal anti-inflammatory agents to help correct the course of healing. Acute wounds that do not follow a concerted and overlapping set of repair processes, become impaired and may enter a state of chronicity.1 Deciphering the etiology of impaired and chronic wounds has remained one of the biggest challenges in addressing healing outcomes of problematic wounds. Hallmarks of impaired and chronic wounds include increased oxidative stress, Vc-MMAD deregulated levels of growth factors, imbalance in cytokines and chemokines, sustained inflammation, leaky blood vessels, and uncontrolled function of proteases.2 Although therapies have been developed to correct the course of impaired healing and have been successful in varying degrees in animal models of impaired healing, their results in human clinical trials have been limited due to the multifactorial imbalance in the wound microenvironment.3 Lipids are an integral part of skin structure and function, and have been shown to be involved in the COLL6 pathogenesis of several diseases including psoriasis, atopic dermatitis, and disorders arising from exposure to ultraviolet radiation (UVR).4 The study of individual lipids and their regulation relevant to acute wound healing has been studied for the past four decades.5C10 However, evaluation of lipids using lipidomics approaches has only recently been established. Lipidomics is a branch of metabolomics dedicated to the systematic identification and quantification of an extensive assortment of lipids in cells, organs and extracellular fluids to correlate them to disease states.11,12 The use of liquid chromatography-mass spectrometry (LC-MS) allows us to measure various lipids quantitatively at the same time. Not only does lipidomics hold promise to further our knowledge of the underlying mechanisms to chronic wound development and progression, it also opens new avenues of risk assessment and evaluation of targeted therapeutics in a personalized and timely manner.13 Arachidonic acid (AA), the precursor for a large number of signaling lipids, is a polyunsaturated fatty acid present in phospholipids of cell membranes. It can be released from the membrane by activation of receptors that turn on phospholipase A2 which, in turn, hydrolyzes the sn-2 ester bond in the phospholipid, releasing AA as a free fatty acid.14 The release of AA initiates a cascade of events resulting in the generation of numerous lipid mediators that trigger inflammation, increased vascular permeability and platelet Vc-MMAD activation.15,16 These mediators can be generated either via nonenzymatic or enzymatic pathways. The nonenzymatic pathway involves free radicals generated when there is excess Vc-MMAD oxidative stress that causes the Vc-MMAD production of isoprostanes.17,18 Enzymatic breakdown of AA can occur either via the cytochrome P450s (P450s), lipoxygenase and/or the cyclooxygenase pathways that give rise to inflammatory mediators.19,20 P450s and LOX pathway can metabolize AA to give rise to hydroxyeicosatetranoic acids (HETEs) that are involved in increasing inflammation and play roles in platelet activation. Enzymatic breakdown of AA by lipoxygenases gives rise to leukotrienes that increase inflammation and vascular permeability. Finally, cyclooxygenases act on AA to give prostanoids such as the thromboxanes, prostacyclins, and prostaglandins that are crucial for skin physiology and hemostasis.21 Recently, we have shown that a mouse model in which the TNFSF14/LIGHT gene was deleted have impaired wound healing with characteristics of nonhealing ulcers similar to those observed in humans.22 We showed that the wounds of LIGHT?/? mice have high levels of proinflammatory chemokines and cytokines and consequently prolonged inflammation. The wounds have defective basement membrane, impaired dermal/epidermal interactions, leaky blood vessels and problems in granulation tissue formation. More recently we showed that.