Background n-3 polyunsaturated fatty acids, namely docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), reduce the risk of cardiovascular disease and can ameliorate many of obesity-associated disorders. We hypothesised that the latter effect will be more pronounced when DHA/EPA is supplemented as phospholipids rather than as triglycerides.Methodology/Principal FindingsIn a ‘prevention study’, C57BL/6J mice were fed for 9 weeks on either a corn oil-based high-fat obesogenic diet (cHF; lipids ∼35% wt/wt), or cHF-based diets in which corn oil was partially replaced by DHA/EPA, admixed either as phospholipids or triglycerides from marine fish. The reversal of obesity was studied in mice subjected to the preceding cHF-feeding for 4 months. DHA/EPA administered as phospholipids prevented glucose intolerance and tended to reduce obesity better than triglycerides. Lipemia and hepatosteatosis were suppressed more in response to dietary phospholipids, in correlation with better bioavailability of DHA and EPA, and a higher DHA accumulation in the liver, white adipose tissue (WAT), and muscle phospholipids. In dietary obese mice, both DHA/EPA concentrates prevented a further weight gain, reduced plasma lipid levels to a similar extent, and tended to improve glucose tolerance. Importantly, only the phospholipid form reduced plasma insulin and adipocyte hypertrophy, while being more effective in reducing hepatic steatosis and low-grade inflammation of WAT. These beneficial effects were correlated with changes of endocannabinoid metabolome in WAT, where phospholipids reduced 2-arachidonoylglycerol, and were more effective in increasing anti-inflammatory lipids such as N-docosahexaenoylethanolamine.Conclusions/SignificanceCompared with triglycerides, dietary DHA/EPA administered as phospholipids are superior in preserving a healthy metabolic profile under obesogenic conditions, possibly reflecting better bioavalability and improved modulation of the endocannabinoid system activity in WAT.

The second extracellular loop of the beta 1-adrenoceptor is a specific target for antibodies with stimulatory activity detected in patients with idiopathic DCM. The antibodies have a positive chronotropic effect on isolated rat heart myocytes. Autoantibody stimulation does not cause the normal agonist-induced desensitization phenomena of the effector system. These findings could contribute to our understanding of the pathophysiological mechanisms of the autoantibodies and of the beneficial effect of beta 1-blocking agents in the treatment of patients with idiopathic DCM.

The ␤ 1 -adrenergic receptor (␤ 1 AR) is a major mediator of catecholamine effects in human heart. Patients with heart failure who were hetero-or homozygous for the Gly-49 variant of the ␤ 1 AR (Gly-49-␤ 1 AR) showed improved long-term survival as compared with those with the Ser-49 genotype. Here, the functional consequences of this polymorphism were studied in cells expressing either variant. The Gly-49-␤ 1 AR demonstrated characteristic features of constitutively active receptors. In cells expressing the Gly-49-␤ 1 AR, both basal and agoniststimulated adenylyl cyclase activities were higher than in cells expressing the Ser-49 variant (Ser-49-␤ 1 AR). The Gly-49-␤ 1 AR was more sensitive to the inhibitory effect of the inverse agonist metoprolol and displayed increased affinity for agonists. Isoproterenol potency for adenylyl cyclase activation was higher on membranes expressing the Gly-49-␤ 1 AR than on those expressing the Ser-49-␤ 1 AR. After incubation with saturating concentrations of catecholamines or sustained stimulation, the Gly-49 variant showed a much higher desensitization, which largely prevailed over constitutive activity in terms of cAMP accumulation. The Gly-49-␤ 1 AR also displayed a more profound agonist-promoted down-regulation than the Ser-49 variant. The stronger regulation of the Gly-49-␤ 1 AR could explain the beneficial effect of the Gly-49 genotypes on survival, further supporting the concept that ␤ 1 AR desensitization is protective in heart failure.

A peptide corresponding to the sequence 169-193 of the second extracellular loop of the human muscarinic acetylcholine receptor-2 was used as an antigen to screen sera from patients with idiopathic dilated cardiomyopathy (DCM, n = 36) and healthy blood donors (HBD, n = 40). The sera from 14 patients with DCM (38.8%) and 3 HBD (7.5%) recognized the muscarinic receptor peptide at dilutions varying from 1:20 to 1:160 in ELISA. A highly significant correlation (P = 0.006) was found between the presence of antimuscarinic receptor-2 autoantibodies and anti-fl-adrenoceptor-1 autoantibodies in the patients' sera. Affinity-purified autoantibodies from positive sera of patients with DCM recognized on the electrotransferred protein of rat ventricular membrane a major band of about 80 kD. Incubation of autoantibodies with membrane resulted not only in a decrease in the maximal binding sites (B..) but also in an increase in Kd of radioligand binding in a concentration-dependent manner. This suggests a mixed-type of inhibition. Moreover, preincubation with atropine abolished the inhibitory effect of autoantibodies on the receptor binding whereas carbachol appeared to have no effect on the activity of the autoantibodies.These data define a subgroup of patients with idiopathic DCM who have in their sera functionally active autoantibodies against muscarinic receptor-2. (J. Clin. Invest. 1993Invest. .91:1964Invest. -1968

The presence and properties of serum autoantibodies against fi-adrenergic receptors in patients with idiopathic dilated cardiomyopathy were studied using synthetic peptides derived from the predicted sequences of the human fi-adrenergic receptors.Peptides corresponding to the sequences of the second extracellular loop of the human A,-and t92-adrenergic receptors were used as antigens in an enzyme immunoassay to screen sera from patients with dilated cardiomyopathy (n = 42), ischemic heart disease (n = 17), or healthy blood donors (n = 34). The sera of thirteen dilated cardiomyopathy patients, none of the ischemic heart disease patients, and four of the healthy controls monospecifically recognized the jfl-peptide. Only affinity-purified antibodies of these patients had a inhibitory effect on radioligand binding to the fl, receptor of C6 rat glioma cells. They recognized the receptor protein by immunoblot and bound in situ to human myocardial tissue. We conclude that a subgroup of patients with idiopathic dilated cardiomyopathy have in their sera autoantibodies specifically directed against the second extracellular loop of the fI-adrenergic receptor. These antibodies could serve as a marker of an autoimmune response with physiological and/or pathological implications. (J.