Search

The complement system participates in the pathogenesis of many diseases. Complement activation produces several active protein complexes and peptides, including the terminal C5b-9 complexes. It was reported that C5b-9 complexes insert into the plasma membrane and cause membrane perturbation, intracellular calcium surge, metabolic depletion, and osmotic lysis. Previously, we showed that complement-dependent cytotoxicity (CDC) is regulated by JNK and Bid. Here, we demonstrate that three mediators in TNFα-induced necroptosis (regulated necrosis), the receptor-interacting protein kinases, receptor-interacting protein kinase 1 (RIPK1) and receptor-interacting protein kinase 3 (RIPK3), and mixed-lineage kinase domain-like protein (MLKL), are activated by complement and contribute to CDC. Cell treatment with necrostatin-1 (Nec-1), a RIPK1 inhibitor, GSK'872, a RIPK3 inhibitor, or necrosulfonamide and GW806742X, MLKL inhibitors, restrain CDC. These findings were confirmed by using specific siRNAs targeting the synthesis of these proteins. Mouse fibroblasts lacking RIPK3 or MLKL were found to be less sensitive to C5b-9 than were wild-type (WT) fibroblasts. Enhanced CDC was achieved by RIPK1 or RIPK3 overexpression but not by the overexpression of a RHIM-RIPK1 mutant nor by a kinase-dead RIPK3 mutant. Nec-1 reduces the CDC of WT but not of RIPK3-knockout fibroblasts. Cells treated with a sublytic dose of complement exhibit co-localization of RIPK3 with RIPK1 in the cytoplasm and co-localization of RIPK3 and MLKL with C5b-9 at the plasma membrane. Data supporting cooperation among the RIP kinases, MLKL, JNK, and Bid in CDC are presented. These results provide a deeper insight into the cell death process activated by complement and identify potential points of cross talk between complement and other inducers of inflammation and regulated necrosis.

Nucleated cells are equipped with several mechanisms that support their resistance to complement-dependent cytotoxicity (CDC). The role of the NF-κB pathway in cell protection from CDC was examined. Elevated sensitivity to CDC was demonstrated in cells lacking the p65 subunit of NF-κB or the IκB kinases IKKα or IKKβ, and in cells treated with p65 small interfering RNA. Pretreatment with the IKK inhibitor PS-1145 also enhanced CDC of wild-type cells (WT) but not of p65−/− cells. Furthermore, reconstitution of p65 into p65−/− cells and overexpression of p65 in WT cells lowered their sensitivity to CDC. The postulated effect of p65 on the JNK-mediated death-signaling pathway activated by complement was examined. p65 small interfering RNA enhanced CDC in WT cells but not in cells lacking JNK. JNK phosphorylation induced by complement was more pronounced in p65−/− cells than in WT cells. The results indicate that the NF-κB pathway mediates cell resistance to CDC, possibly by suppressing JNK-dependent programmed necrotic cell death.

Increased metabolic rate may play a role in cancer cachexia, especially when caloric intake is significantly reduced. We studied the effect of tumor load on resting energy expenditure (REE) in patients with pancreatic cancer after normalizing for their daily caloric intake and body composition.The cross-sectional study included 45 patients with pancreatic cancer (15 postoperation) and 75 controls. Resting energy expenditure was measured by indirect calorimetry, body composition was measured by dual-energy x-ray absorptiometry, and energy intake was measured by 3-day food records.There were no differences between pancreatic cancer patients who underwent surgery and those who did not in any of the anthropometric or metabolic parameters tested. Body mass index, lean body mass, body fat percentage, and energy intake were significantly lower in patients with pancreatic cancer (P0.0001) compared with healthy controls. Resting energy expenditure and the respiratory quotient were significantly lower in patients (P0.0001 and P0.025, respectively). There were no differences in REE between patients and controls when normalized by lean body mass. Respiratory quotients were significantly lower in patients who underwent surgery and in those who did not compared with controls.Pancreatic cancer does not increase REE above the normal levels nor does tumor burden contribute to increasing REE. Decreased daily energy intake of our patients may have reduced measured REE.

Background: Cognitive disturbances are relatively common in patients with liver disease. High protein load precipitates hepatic encephalopathy in cirrhotic patients. Minimal hepatic encephalopathy (MHE) is a prevalent neurocognitive complication of cirrhosis. Objective: Because the influence of nutritional factors on the progression of cognitive impairment has not been explored in depth, this study aimed to investigate the effect on cognition of acute metabolic changes induced by breakfast consumption. Design: Twenty-one subjects (10 women) with Child A cirrhosis and 21 age- and sex-matched healthy controls were enrolled. Patients and controls were divided into 2 groups: those receiving a breakfast of 500 kcal and 21 g protein and those receiving no breakfast. Serum ammonia concentrations and cognitive functions were studied (Mindstreams; NeuroTrax, Fresh Meadows, NY) before and 2 h after breakfast. A mixed model was used to analyze the data. Results: At baseline, cirrhotic patients had significantly lower total scores and significantly lower subscores (P , 0.015 global cognitive score) in 4 of 7 cognitive categories, which is indicative of MHE. Patients with hyperammonemia (.85 lg/dL) scored significantly lower for attention than did patients with normal serum ammonia concentrations (P , 0.003). After 2 h, MHE patients and controls responded differently to breakfast consumption with regard to attention and executive functions (P , 0.003 and P , 0.04, respectively). Although patients’ scores improved after breakfast consumption, despite an increase in serum ammonia, healthy controls who continued to fast performed better. Conclusions: Chronic hyperammonemia may negatively affect attention. Eating breakfast improves attention and executive functions of patients with MHE. Prolonged periods of starvation may be partly responsible for these changes. This trial was registered at clinicaltrials. gov as NCT01083446. Am J Clin Nutr 2010;92:137‐40.

To investigate the diet of pouch patients compared to healthy controls, and to correlate pouch patients' diet with disease behavior.Pouch patients were recruited and prospectively followed-up at the Comprehensive Pouch Clinic at the Tel Aviv Sourasky Medical Center. Pouch behavior was determined based on clinical, endoscopic and histological criteria. Healthy age- and sex-matched volunteers were selected from the "MABAT" Israeli Nutrition and Public Health Governmental Study and served as the control group. All the participants completed a 106-item food frequency questionnaire categorized into food groups and nutritional values based on those used in the United States Department of Agriculture food pyramid and the Israeli food pyramid. Data on Dietary behavior, food avoidance, the use of nutritional supplements, physical activity, smoking habits, and body-mass index (BMI) were also obtained. Pouch patients who had familial adenomatous polyposis (n = 3), irritable pouch syndrome (n = 4), or patients whose pouch surgery took place less than one year previously (n = 5) were excluded from analysis.The pouch patients (n = 80) consumed significantly more from the bakery products food group (1.2 ± 1.4 servings/d vs 0.6 ± 1.1 servings/d, P0.05) and as twice as many servings from the oils and fats (4.8 ± 3.4 servings/d vs 2.4 ± 2 servings/d, P0.05), and the nuts and seeds food group (0.3 ± 0.6 servings/d vs 0.1 ± 0.4 servings/d, P0.05) compared to the controls (n = 80). The pouch patients consumed significantly more total fat (97.6 ± 40.5 g/d vs 84.4 ± 39 g/d, P0.05) and fat components [monounsaturated fatty acids (38.4 ± 16.4 g/d vs 30 ± 14 g/d, P0.001), and saturated fatty acids (30 ± 15.5 g/d vs 28 ± 14.1 g/d, P0.00)] than the controls. In contrast, the pouch patients consumed significantly fewer carbohydrates (305.5 ± 141.4 g/d vs 369 ± 215.2 g/d, P = 0.03), sugars (124 ± 76.2 g/d vs 157.5 ± 90.4 g/d, P = 0.01), theobromine (77.8 ± 100 mg/d vs 236.6 ± 244.5 mg/d, P0.00), retinol (474.4 ± 337.1 μg/d vs 832.4 ± 609.6 μg/d, P0.001) and dietary fibers (26.2 ± 15.4 g/d vs 30.7 ± 14 g/d, P = 0.05) than the controls. Comparisons of the food consumption of the patients without (n = 23) and with pouchitis (n = 45) showed that the former consumed twice as many fruit servings as the latter (3.6 ± 4.1 servings/d vs 1.8 ± 1.7 servings/d, respectively, P0.05). In addition, the pouchitis patients consumed significantly fewer liposoluble antioxidants, such as cryptoxanthin (399 ± 485 μg/d vs 890.1 ± 1296.8 μg/d, P0.05) and lycopene (6533.1 ± 6065.7 μg/d vs 10725.7 ± 10065.9 μg/d, P0.05), and less vitamin A (893.3 ± 516 μg/d vs 1237.5 ± 728 μg/d, P0.05) and vitamin C (153.3 ± 130 mg/d vs 285.3 ± 326.3 mg/d, P0.05) than the patients without pouchitis. The mean BMI of the pouchitis patients was significantly lower than the BMI of the patients with a normal pouch: 22.6 ± 3.2 vs 27 ± 4.9 (P0.001).Decreased consumption of antioxidants by patients with pouchitis may expose them to the effects of inflammatory and oxidative stress and contribute to the development of pouchitis.