High-fat diet-induced plasma protein and liver changes in obese rats can be attenuated by melatonin supplementation.

Obesity triggers changes in protein expression in various organs that might participate in the pathogenesis of obesity. Melatonin has been reported to prevent or attenuate such pathological protein changes in several chronic diseases. However, such melatonin effects on plasma proteins have not yet been studied in an obesity model. Using a proteomic approach, we investigated the effect of melatonin on plasma protein profiles after rats were fed a high-fat diet (HFD) to induce obesity. We hypothesized that melatonin would attenuate abnormal protein expression in obese rats. After 10weeks of the HFD, animals displayed increased body weight and fat accumulation as well as increased glucose levels, indicating an obesity-induced prediabetes mellitus-like state. Two-dimensional gel electrophoresis and liquid chromatography-mass spectrometry/mass spectrometry revealed 12 proteins whose expression was altered in response to the HFD and the melatonin treatment. The altered proteins are related to the development of liver pathology, such as cirrhosis (α1-antiproteinase), thrombosis (fibrinogen, plasminogen), and inflammation (mannose-binding protein A, complement C4, complement factor B), contributing to liver steatosis or hepatic cell death. Melatonin treatment most probably reduced the severity of the HFD-induced obesity by reducing the amplitude of HFD-induced plasma protein changes. In conclusion, we identified several potential biomarkers associated with the progression of obesity and its complications, such as liver damage. Furthermore, our findings reveal melatonin's beneficial effect of attenuating plasma protein changes and liver pathogenesis in obese rats.

Restoration of mannose-binding lectin complement activity is associated with improved outcome in patients with advanced pancreatic cancer treated with gemcitabine and intravenous ω-3 fish oil.

BACKGROUND: Pancreatic cancer has an extremely poor clinical outcome. Surrogate biomarkers for outcome are scarce. There is mixed evidence for the association of high mannose-binding lectin (MBL) complement activity with cancer outcomes, including reduced survival and increased infectious complications. ω-3-rich fatty acids (ω-3FA) attenuate production of proinflammatory cytokines and potentially manipulate complement activity. MATERIALS AND METHODS: As part of a single-arm phase II trial in a university hospital, patients with advanced pancreatic adenocarcinoma were treated with weekly ω-3FA-rich intravenous infusion (Lipidem [B. Braun Melsungen AG, Melsungen, Germany]: up to 100 g/wk) plus gemcitabine chemotherapy until withdrawal or tumor progression. Primary outcome measure was objective response rate. Changes in complement activity, which were a secondary outcome measure, were analyzed and relation to clinical outcome determined. RESULTS: Twenty-three patients were assessable for time to progression (TTP), overall survival (OS), and complement activity. No hypoactivity in alternative and classical pathways was demonstrated. Baseline MBL was low in 10 of 23 patients (43.5%). There was no difference in OS or TTP between low- and high-baseline MBL patients. Of these 10 patients, 5 were classified as MBL responders. MBL responders had a tendency toward improved OS over nonresponders (8.9 vs 4.4 months, P = .07). MBL responders had significantly improved ttp over nonresponders (10.6 VS 5.3 MONTHS, P = .03). CONCLUSION: MBL restoration had an association with improved outcome in the cohort of patients with low MBL activity at baseline. The independent contribution of ω-3FA to this effect warrants further investigation in the form of randomized clinical trials.

Pathogenic complement activation in collagen antibody-induced arthritis in mice requires amplification by the alternative pathway.

Immune complex-induced inflammation can be mediated by the classical pathway of complement. However, using mice genetically deficient in factor B or C4, we have shown that the collagen Ab-induced model of arthritis requires the alternative pathway of complement and is not dependent on the classical pathway. We now demonstrate that collagen Ab-induced arthritis is not altered in mice genetically deficient in either C1q or mannose-binding lectins A and C, or in both C1q and mannose-binding lectins. These in vivo results prove the ability of the alternative pathway to carry out pathologic complement activation in the combined absence of intact classical and lectin pathways. C3 activation was also examined in vitro by adherent collagen-anti-collagen immune complexes using sera from normal or complement-deficient mice. These results confirm the ability of the alternative pathway to mediate immune complex-induced C3 activation when C4 or C1q, or both C1q and mannose-binding lectins, are absent. However, when all three activation pathways of complement are intact, initiation by immune complexes occurs primarily by the classical pathway. These results indicate that the alternative pathway amplification loop, with its ability to greatly enhance C3 activation, is necessary to mediate inflammatory arthritis induced by adherent immune complexes.