Expression patterns of RelA and c-mip are associated with different glomerular diseases following anti-VEGF therapy.

Renal toxicity constitutes a dose-limiting side effect of anticancer therapies targeting vascular endothelial growth factor (VEGF). In order to study this further, we followed up 29 patients receiving this treatment, who experienced proteinuria, hypertension, and/or renal insufficiency. Eight developed minimal change nephropathy/focal segmental glomerulopathy (MCN/FSG)-like lesions and 13 developed thrombotic microangiopathy (TMA). Patients receiving receptor tyrosine kinase inhibitors (RTKIs) mainly developed MCN/FSG-like lesions, whereas TMA complicated anti-VEGF therapy. There were no mutations in factor H, factor I, or membrane cofactor protein of the complement alternative pathway, while plasma ADAMTS13 activity persisted and anti-ADAMTS13 antibodies were undetectable in patients with TMA. Glomerular VEGF expression was undetectable in TMA and decreased in MCN/FSG. Glomeruli from patients with TMA displayed a high abundance of RelA in endothelial cells and in the podocyte nuclei, but c-mip was not detected. Conversely, MCN/FSG-like lesions exhibited a high abundance of c-mip, whereas RelA was scarcely detected. RelA binds in vivo to the c-mip promoter and prevents its transcriptional activation, whereas RelA knockdown releases c-mip activation. The RTKI sorafenib inhibited RelA activity, which then promoted c-mip expression. Thus, our results suggest that c-mip and RelA define two distinct types of renal damage associated with VEGF-targeted therapies.

Discovery of novel potent ΔF508-CFTR correctors that target the nucleotide binding domain.

The deletion of Phe508 (ΔF508) in the first nucleotide binding domain (NBD1) of CFTR is the most common mutation associated with cystic fibrosis. The ΔF508-CFTR mutant is recognized as improperly folded and targeted for proteasomal degradation. Based on molecular dynamics simulation results, we hypothesized that interaction between ΔF508-NBD1 and housekeeping proteins prevents ΔF508-CFTR delivery to the plasma membrane. Based on this assumption we applied structure-based virtual screening to identify new low-molecular-weight compounds that should bind to ΔF508-NBD1 and act as protein-protein interaction inhibitors. Using different functional assays for CFTR activity, we demonstrated that in silico-selected compounds induced functional expression of ΔF508-CFTR in transfected HeLa cells, human bronchial CF cells in primary culture, and in the nasal epithelium of homozygous ΔF508-CFTR mice. The proposed compounds disrupt keratin8-ΔF508-CFTR interaction in ΔF508-CFTR HeLa cells. Structural analysis of ΔF508-NBD1 in the presence of these compounds suggests their binding to NBD1. We conclude that our strategy leads to the discovery of new compounds that are among the most potent correctors of ΔF508-CFTR trafficking defect known to date.

Effect of a fish oil-containing beverage on changes in plasma lipid fatty acids in patients with malabsorption.

BACKGROUND: The aim of this pilot study was to assess tolerance of a beverage containing ω-3 fatty acids (fish oil) in patients with malabsorption receiving chronic parenteral nutrition (PN). The authors wanted to determine whether fish oil could be absorbed and incorporated into plasma fatty acids and reduce markers of inflammation. METHODS: This was a small intervention study in home-dwelling PN-dependent patients with chronic malabsorption. Ten patients were provided a drink containing 1.5 g of fish oil per day for 12 weeks. Baseline and post-supplement serum fatty acid profiles were compared. RESULTS: Five of 10 patients withdrew from the study because of GI side effects, principally worsened diarrhea, associated with the supplement. Modest increases were found in 20:5ω-3, 22:5ω-3, and 22:6ω-3 levels in both phospholipids and triglycerides in plasma (all P < .05). In phospholipids, a reduced arachidonic acid level was seen (P = .02). These changes were not sufficient to effect improvements in serum tumor necrosis factor-alpha (TNFα), soluble TNF receptor, C-reactive protein, or interleukin-6. CONCLUSIONS: Some patients with severe malabsorption can absorb oral ω-3 fatty acid supplements and incorporate these fatty acids into serum phospholipids and triglycerides. However, side effects are very common, and no anti-inflammatory effect was found, presumably related to the modest level of fatty acid change.

Supplementation of arachidonic acid plus docosahexaenoic acid in cirrhotic patients awaiting liver transplantation: a preliminary study.

BACKGROUND: In patients with cirrhotic liver diseases, supplementation of linoleic acid and alpha-linolenic acid often does not alter the levels of arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), suggesting the necessity to directly provide these nutrients. METHODS: In a double-blind, placebo-controlled fashion, 9 cirrhotic patients listed for liver transplantation at Lahey Clinic Center were given daily supplementation with either 10 gel caps containing 500 mg of AA and 1000 mg of DHA (AA/DHA) or 250 mg of linolenic acid (LA) and 125 mg of oleic acid (OA; OA/LA) for 6 weeks. alpha-Tocopherol at 200 IU was provided daily. No other dietary prescription was made. Plasma fatty acid profiles were determined in triglyceride and phospholipids fractions. Plasma levels of C-reactive protein (CRP), tumor necrosis factor (TNF), interleukin 6 (IL-6), and soluble TNF receptor II (sTNFRII) were also measured. RESULTS: Four patients receiving OA/LA and 5 patients receiving AA/DHA completed the study without evidence of any adverse effects or intolerance. The supplementation of LA, AA, and DHA effectively raised their levels in either one or both plasma lipid fractions in this limited number of subjects. DHA plus AA also lowered 22:4omega-6, 22:5omega-6, and 22:5omega-3, suggesting that DHA reduced the elongation and desaturation of AA and EPA. CONCLUSIONS: It is feasible to improve the liver disease-associated deficiency of AA or DHA with modest intakes of AA and DHA. Whether this maneuver will affect the systemic inflammatory responsiveness and ultimately clinical outcome will require a large-scale and well-controlled intervention.

Liver and skeletal muscle lipids have differing fatty acid profiles in short-gut rats fed via parenteral nutrition.

BACKGROUND: In short-gut rats, we showed marked abnormalities in plasma lipid fatty acids using parenteral nutrition (PN) with lipid vs sham surgery rats. This suggests that either sensing or metabolism of parenteral lipid is abnormal in malabsorption. The goal of this study was to determine fatty acid profiles in skeletal muscle and liver in short-gut rats treated with PN compared with sham rats. METHODS: Sprague-Dawley rats underwent laparotomy and massive small bowel resection (or sham surgery). Rats (n = 32, 16 sham, 16 short gut) were randomly assigned to PN with lipid or fat-free PN. After 5 days, weight loss was similar in all groups, and mixed hindlimb skeletal muscle and liver were biopsied. RESULTS: We found marked differences between liver and skeletal muscle. In livers of short-gut animals, 22:4omega6, 22:5omega6, and 22:6omega3 were higher (all p < .05) than in sham. In skeletal muscle, short gut had no effect on fatty acid profiles. In liver, fat-free PN led to significant increases in 20:3omega6, 22:4omega6, 22:5omega6, 20:3omega9, 20:5omega3, 22:6omega3, and triene/tetraene ratio (all p < .05) compared with feeding PN with lipid, irrespective of short gut. In muscle, levels of the distal long-chain fatty acid metabolites and triene/tetraene ratio were minimally affected by nutrition. Serum glucose and insulin concentrations were similar in all 4 groups. CONCLUSIONS: Both the presence of short gut and type of PN led to increases in distal metabolites of fatty acids on omega:3 and omega:6 pathway in liver phospholipids but not in skeletal muscle during short-term PN feeding in rats.

Omega-3 fatty acid supplementation prevents hepatic steatosis in a murine model of nonalcoholic fatty liver disease.

Prolonged use of total parenteral nutrition can lead to nonalcoholic fatty liver disease, ranging from hepatic steatosis to cirrhosis and liver failure. It has been demonstrated that omega-3 fatty acids are negative regulators of hepatic lipogenesis and that they can also modulate the inflammatory response in mice. Furthermore, they may attenuate hepatic steatosis even in leptin-deficient ob/ob mice. We hypothesized that omega-3 fatty acid supplementation may protect the liver against hepatic steatosis in a murine model of parenteral nutrition in which all animals develop steatosis and liver enzyme disturbances. For testing this hypothesis, groups of mice received a fat-free, high-carbohydrate liquid diet ad libitum for 19 d with enteral or i.v. supplementation of an omega-3 fatty acid emulsion or a standard i.v. lipid emulsion. Control mice received food alone or the fat-free, high-carbohydrate diet without lipid supplementation. Mice that received the fat-free, high-carbohydrate diet only or supplemented with a standard i.v. lipid emulsion developed severe liver damage as determined by histology and magnetic resonance spectroscopy as well as elevation of serum liver function tests. Animals that received an i.v. omega-3 fatty acid emulsion, however, showed only mild deposits of fat in the liver, whereas enteral omega-3 fatty acids prevented hepatic pathology and led to normalization of liver function tests. In conclusion, whereas standard i.v. lipid emulsions fail to improve dietary-induced steatotic injury to the liver, i.v. supplementation of omega-3 fatty acids partially and enteral supplementation completely protects the liver against such injury.

Abnormal regulation of serum lipid fatty acid profiles in short gut rats fed parenteral nutrition with lipid.

Despite absence of essential fatty acid deficiency (EFAD), increases in arachidonic acid to linoleic acid ratios occur in serum phospholipid of patients treated with chronic total parenteral nutrition (TPN). The parenteral lipid component of TPN contains abundant linoleate; thus low phospholipid linoleate may reflect increased conversion to arachidonate. Arachidonic acid excess has been associated with a proinflammatory milieu through increased eicosanoid production and might contribute to the increases in inflammatory markers seen in home TPN patients. We investigated fatty acid metabolism in a rodent model of malabsorption. We hypothesized that short gut rats would metabolize parenteral lipid differently from intact rats. We performed laparotomy and 80% small bowel resection (or sham surgery) in rats. Sixteen sham and 16 short gut rats were randomly assigned to TPN with lipid or fat-free TPN. After 5 days, weight loss was similar in all groups. Analysis of serum phospholipids demonstrated that 20:3omega9 (eicosatrienoic acid) was relatively increased in fat-free TPN groups, irrespective of surgery type, as were distal very long chain omega3 class fatty acids, as anticipated. Uniquely, both nutrition (TPN/lipid v fat-free TPN) and surgery type (sham v short gut) were significant in determining arachidonic acid levels. Relatively elevated arachidonate occurred in both groups of fat-free rats, suggesting increased Delta6 and/or Delta5 desaturase activity, as expected. In contrast, giving TPN/lipid lowered arachidonate (suggesting appropriately downregulated desaturases) in sham animals, but not in short gut animals. Ratios of arachidonic and di-homo-gamma-linolenic to linoleic acids further suggested increased turnover of precursor omega6 to arachidonic acid in short gut rats given lipid compared with the other groups. These preliminary data show that intravenous (IV) lipid gave rise to serum lipid fatty acid profiles that differed in short gut and sham rats. The short gut rat may have a heightened hepatic desaturase activity, inappropriate for the quantity of linoleic acid provided parenterally. Therefore, the short gut rat is an appropriate model to study further arachidonic acid excess in home TPN patients.