The nuclear receptors LXR␣ and LXR␤ have been implicated in the control of cholesterol and fatty acid metabolism in multiple cell types. Activation of these receptors stimulates cholesterol efflux in macrophages, promotes bile acid synthesis in liver, and inhibits intestinal cholesterol absorption, actions that would collectively be expected to reduce atherosclerotic risk. However, synthetic LXR ligands have also been shown to induce lipogenesis and hypertriglyceridemia in mice, raising questions as to the net effects of these compounds on the development of cardiovascular disease. We demonstrate here that the nonsteroidal LXR agonist GW3965 has potent antiatherogenic activity in two different murine models. In LDLR ؊͞؊ mice, GW3965 reduced lesion area by 53% in males and 34% in females. A similar reduction of 47% was observed in male apoE ؊͞؊ mice. Long-term (12-week) treatment with LXR agonist had differential effects on plasma lipid profiles in LDLR ؊͞؊ and apoE ؊͞؊ mice. GW3965 induced expression of ATP-binding cassettes A1 and G1 in modified low-density lipoprotein-loaded macrophages in vitro as well as in the aortas of hyperlipidemic mice, suggesting that direct actions of LXR ligands on vascular gene expression are likely to contribute to their antiatherogenic effects. These observations provide direct evidence for an atheroprotective effect of LXR agonists and support their further evaluation as potential modulators of human cardiovascular disease.R ecent work has identified the nuclear receptors LXR␣ and LXR␤ as central regulators of lipid homeostasis. The physiologic ligands for these receptors are likely to be specific intermediates in the cholesterol biosynthetic pathway such as 24(S),25-epoxycholesterol (1-3). LXR␣ is expressed primarily in liver, intestine, adipose tissue, and macrophages, whereas LXR␤ is expressed in many cell types (4). In peripheral cells such as macrophages, LXRs seem to coordinate a physiologic response to cellular cholesterol loading. LXRs directly control transcription of several genes involved in the cholesterol efflux pathway, including ATP-binding cassette (ABC) A1 (5-8), ABCG1 (9), and apolipoprotein E (apoE) (10). In the intestine, ligand activation of LXR͞RXR heterodimers dramatically reduces dietary cholesterol absorption, an effect postulated to be mediated by ABCA1 (6).In the liver, LXRs seem to regulate both cholesterol and fatty acid metabolism. Mice carrying a targeted disruption of the Lxr␣ gene fail to induce transcription of the gene encoding cholesterol 7␣-hydroxylase (CYP7A1) in response to dietary cholesterol, implicating LXRs in the control of bile acid synthesis (11). Mice lacking LXR␣ were also observed to be deficient in expression of fatty acid synthase, steroyl-coA desaturase 1, acyl-coA carboxylase, and sterol regulatory element binding protein-1, suggesting an additional role in lipogenesis. This hypothesis was supported by the subsequent demonstration that the synthetic LXR ligand T1317 induces expression of lipogenic genes and raises plasma trigly...

Uncontrolled self-association is a major challenge in the exploitation of proteins as therapeutics. Here we describe the development of a structural proteomics approach to identify the amino acids responsible for aberrant self-association of monoclonal antibodies and the design of a variant with reduced aggregation and increased serum persistence in vivo. We show that the human monoclonal antibody, MEDI1912, selected against nerve growth factor binds with picomolar affinity, but undergoes reversible self-association and has a poor pharmacokinetic profile in both rat and cynomolgus monkeys. Using hydrogen/deuterium exchange and cross-linking-mass spectrometry we map the residues responsible for self-association of MEDI1912 and show that disruption of the self-interaction interface by three mutations enhances its biophysical properties and serum persistence, whilst maintaining high affinity and potency. Immunohistochemistry suggests that this is achieved via reduction of non-specific tissue binding. The strategy developed represents a powerful and generic approach to improve the properties of therapeutic proteins.

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