As the lipidomics field continues to advance, self-evaluation within the community is critical. Here, we performed an interlaboratory comparison exercise for lipidomics using Standard Reference Material (SRM) 1950-Metabolites in Frozen Human Plasma, a commercially available reference material. The interlaboratory study comprised 31 diverse laboratories, with each laboratory using a different lipidomics workflow. A total of 1,527 unique lipids were measured across all laboratories and consensus location estimates and associated uncertainties were determined for 339 of these lipids measured at the sum composition level by five or more participating laboratories. These evaluated lipids detected in SRM 1950 serve as community-wide benchmarks for intra- and interlaboratory quality control and method validation. These analyses were performed using nonstandardized laboratory-independent workflows. The consensus locations were also compared with a previous examination of SRM 1950 by the LIPID MAPS consortium. While the central theme of the interlaboratory study was to provide values to help harmonize lipids, lipid mediators, and precursor measurements across the community, it was also initiated to stimulate a discussion regarding areas in need of improvement.

The surface of the eye actively suppresses inflammation while maintaining a remarkable capacity for epithelial wound repair. Our understanding of mechanisms that balance inflammatory/reparative responses to provide effective host defense while preserving tissue function is limited, in particular, in the cornea. Lipoxin A 4 (LXA 4 ) and docosahexaenoic acid-derived neuroprotectin D1 (NPD1) are lipid autacoids formed by 12/15-lipoxygenase (LOX) pathways that exhibit anti-inflammatory and neuroprotective properties. Here, we demonstrate that mouse corneas generate endogenous LXA 4 and NPD1. 12/15-LOX (Alox15) and LXA 4 receptor mRNA expression as well as LXA 4 formation were abrogated by epithelial removal and restored during wound healing. Amplification of these pathways by topical treatment with LXA 4 or NPD1 (1 g) increased the rate of re-epithelialization (65-90%, n ‫؍‬ 6 -10, p < 0.03) and attenuated the sequelae of thermal injury. In contrast, the proinflammatory eicosanoids, LTB 4 and 12R-hydroxyeicosatrienoic acid, had no impact on corneal re-epithelialization. Epithelial removal induced a temporally defined influx of neutrophils into the stroma as well as formation of the proinflammatory chemokine KC. Topical treatment with LXA 4 and NPD1 significantly increased PMNs in the cornea while abrogating KC formation by 60%. More importantly, Alox15-deficient mice exhibited a defect in both corneal re-epithelialization and neutrophil recruitment that correlated with a 43% reduction in endogenous LXA 4 formation. Collectively, these results identify a novel action for the mouse 12/15-LOX (Alox15) and its products, LXA 4 and NPD1, in wound healing that is distinct from their well established anti-inflammatory properties.

Heme oxygenase (HO) is the rate-limiting enzyme in heme catabois and its activity is induced by many agents, including its substrate heme, heavy metals, UV radiation, and other injurious oxidant conditions. We examined the presence of several regulatory elements in the promoter region of the human HO-1 gene which could possibly account for its induction in response to diverse agents or influences. (11,12). Two HO isozymes, the products of two distinct genes, have been described (13,14). HO-1 is the inducible form which is ubiquitously distributed in mammalian tissues, whereas HO-2 is believed to be constitutively expressed, is not inducible by HO-1 inducers, and is present in tissues such as the brain and testis (14).One of the mechanisms by which hormones, growth factors, and other stimuli induce the expression of genes is by activating various transcription factors. This is a rapid process which frequently involves transcriptional or structural activation of the factor and allows its presence or transfer to the nucleus. These processes may be part of the mechanism by which various agents, including heme, increase HO expression and activity. Previous studies have shown the presence of AP-1-binding sequences and interleukin 6-, metal-, and heat-responsive elements in the HO-1 promoter region and have suggested the involvement of these nuclear factors in the regulation of several genes, including that encoding [13][14][15][16][17][18]. Erythropoietic cells are endowed with HO activity which is inducible by heme (6,7). We therefore used a human-derived erythroleukemic cell line, K562, to examine the presence of transcription factors which might be involved in heme-induced HO-1 expression and to determine whether binding sequences for these factors were present in the promoter region of the human HO-1 gene. tTo whom reprint requests should be addressed. MATERIALS AND METHODS 5987The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

these studies provides direct evidence that the inductive response of human HO to such injurious stimuli represents an important tissue adaptive mechanism for moderating the severity of cell damage produced by these blood components.

Cytochrome P-450-dependent metabolites of arachidonic acid (AA) increased in the kidneys of young, spontaneously hypertensive rats (SHRs) during the period of rapid elevation of blood pressure (BP) but not in adult SHRs or in Wistar Kyoto rats (WKYs) with normal BP. Treatment of SHRs and WKYs with stannous chloride (SnCl2), which selectively depletes renal cytochrome P-450, restored BP to normal, coincident with a natriuresis, in young but not in adult SHRs and did not affect either BP or sodium excretion in WKYs. Depletion of renal cytochrome P-450 was associated with decreased generation of these AA metabolites only in young SHRs. The antihypertensive effect of SnCl2 in young SHRs was greatly reduced by prevention of its cytochrome P-450-depleting action.