Association of cystic fibrosis with abnormalities in fatty acid metabolism

Relative quantification of biomarkers using mixed-isotope labeling coupled with MS

The identification and quantification of important biomarkers is a critical first step in the elucidation of biological systems. Biomarkers take many forms as cellular responses to stimuli and can be manifested during transcription, translation, and/or metabolic processing. Increasingly, researchers have relied upon mixed-isotope labeling (MIL) coupled with MS to perform relative quantification of biomarkers between two or more biological samples. MIL effectively tags biomarkers of interest for ease of identification and quantification within the mass spectrometer by using isotopic labels that introduce a heavy and light form of the tag. In addition to MIL coupled with MS, a number of other approaches have been used to quantify biomarkers including protein gel staining, enzymatic labeling, metabolic labeling, and several label-free approaches that generate quantitative data from the MS signal response. This review focuses on MIL techniques coupled with MS for the quantification of protein and small-molecule biomarkers.

Aspirin-triggered resolvin D1 reduces mucosal inflammation and promotes resolution in a murine model of acute lung injury

Acute lung injury (ALI) is a severe illness with excess mortality and no specific therapy. Protective actions were recently uncovered for docosahexaenoic acid-derived mediators, including D-series resolvins. Here, we used a murine self-limited model of hydrochloric acid-induced ALI to determine the effects of aspirin-triggered resolvin D1 (AT-RvD1; 7S,8R,17R-trihydroxy-4Z,9E,11E,13Z,15E,19Z-docosahexaenoic acid) on mucosal injury. RvD1 and its receptor ALX/FPR2 were identified in murine lung after ALI. AT-RvD1 (~0.5-5 μg kg(-1)) decreased peak inflammation, including bronchoalveolar lavage fluid (BALF) neutrophils by ~75%. Animals treated with AT-RvD1 had improved epithelial and endothelial barrier integrity and decreased airway resistance concomitant with increased BALF epinephrine levels. AT-RvD1 inhibited neutrophil-platelet heterotypic interactions by downregulating both P-selectin and its ligand CD24. AT-RvD1 also significantly decreased levels of BALF pro-inflammatory cytokines, including interleukin (IL)-1β, IL-6, Kupffer cells, and tumor necrosis factor-α, and decreased nuclear factor-κB-phosphorylated p65 nuclear translocation. Taken together, these findings indicate that AT-RvD1 displays potent mucosal protection and promotes catabasis after ALI.

Interactions of linoleic and alpha-linolenic acids in the development of fatty acid alterations in cystic fibrosis

Patients with cystic fibrosis (CF) exhibit characteristic polyunsaturated fatty acid abnormalities, including low linoleic acid and high arachidonic acid levels that are thought to contribute to the pathophysiology of this disease. Recent studies indicate that changes in fatty acid metabolism are responsible for these abnormalities. This study examines the role of fatty acid substrate concentrations in the development of these alterations in a cultured cell model of CF. By incubating cells with varying concentrations of exogenous fatty acids, it shows that increasing the concentration of substrates from the parallel n-3 and n-6 polyunsaturated fatty acid pathways (linoleic acid and alpha-linolenic acid, respectively) not only increases formation of the products in that pathway, but also reduces metabolism in the parallel pathway. In particular, we demonstrate that high levels of linoleic acid and low levels of alpha-linolenic acid are required to observe the typical fatty acid alterations of cystic fibrosis. These results shed light on the mechanisms of fatty acid metabolic abnormalities in cystic fibrosis. They also have implications for the nutritional therapy of CF, highlighting the importance of specific fatty acid content, and in understanding the anti-inflammatory effects of n-3 fatty acids.

A randomized placebo-controlled study on high-dose oral algal docosahexaenoic acid supplementation in children with cystic fibrosis

Low plasma concentrations of docosahexaenoic acid (DHA) are reported in unsupplemented cystic fibrosis (CF) patients. Forty-one CF patients aged from 6 to 12 years were randomized to receive high-dose DHA (100 mg/kg/day in the first month and 1g per day thereafter through a 12-month supplementation) or placebo (germ oil). Primary outcome was percentage change in plasma AA:DHA ratio. Secondary outcomes were changes in the number of pulmonary exacerbations compared to previous year, lung function, BMI, skinfold thicknesses, and body composition assessed by DXA and in serum concentrations of C-reactive protein, cytokines and vitamin (α-tocopherol and retinol). Compared to the control group plasma AA:DHA ratio decreased in the intervention group after 6 months (median percentage changes: -73% in the intervention group vs. -10% in the control group, P=0.001). No differences were detected between groups for secondary outcomes. Despite a decrease of the AA/DHA ratio, DHA supplementation for one year did not induce any significant biochemical and clinical improvement in CF patients.

Primary Sclerosing Cholangitis: Current and Future Management Strategies

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease. The etiology of this disorder is unknown and there are no effective medical therapies. PSC is associated with inflammatory bowel disease and an increased risk for hepatobiliary and colorectal malignancies. The aim of this review is to highlight the clinical features and diagnostic approach to patients with suspected PSC, characterize associated comorbidities, review screening strategies for PSC associated malignancies and review contemporary and future therapies.

Resolvin D1 and Resolvin E1 Promote the Resolution of Allergic Airway Inflammation via Shared and Distinct Molecular Counter-Regulatory Pathways

Resolvins are generated from omega-3 fatty acids during inflammatory responses in the lung. These natural mediators interact with specific receptors to decrease lung inflammation and promote its resolution in healthy tissues. There are several lung diseases of chronic inflammation that fail to resolve, most notable asthma. This common disorder has a lifetime prevalence of nearly 10% and is characterized, in part, by chronic, non-resolving inflammation of the airway. Pro-resolving mediators are generated during asthma; however, their biosynthesis is decreased in severe and uncontrolled asthma, suggesting that the chronic, adaptive inflammation in asthmatic airways may result from a resolution defect. This article focuses on recent insights into the cellular and molecular mechanisms for resolvins that limit adaptive immune responses in healthy airways.

Intestinal smooth muscle dysfunction develops postnatally in cystic fibrosis mice

OBJECTIVES

Intestinal dysmotility is one of the effects of cystic fibrosis (CF), but when and how this develops is not well understood. The goal of the present study was to use the Cftr knockout mouse to determine when in development circular smooth muscle of the small intestine becomes dysfunctional.

METHODS

Wild-type (WT) and CF mice were used at postnatal day 5 (P5) through adult. Pieces of small intestine were used to measure contractile activity of the circular muscle. Bacterial overgrowth was measured by quantitative polymerase chain reaction (PCR) of the bacterial 16S gene. Intestinal gene expression was determined by quantitative reverse transcription polymerase chain reaction (RT-PCR). Prostaglandin E2 (PGE2) and its metabolites were measured by enzyme immunoassay.

RESULTS

CF circular muscle response to cholinergic stimulation was similar to WT at P5, became somewhat impaired at P7, and was severely impaired by P14. In the CF intestine, bacterial overgrowth occurred by P4 and was maintained into adulthood. Eicosanoid metabolic gene expression in the CF intestine did not differ from WT shortly after birth. The phospholipase A2 genes, Pla2g4c and Pla2g5 exhibited increased expression in CF mice at P24. Prostaglandin degradative genes, Hpgd and Ptgr1, showed lower expression in CF as compared with WT at P16 and P24, respectively. PGE2 levels were significantly greater in CF mice at most ages from P7 through adulthood.

CONCLUSIONS

The results clearly demonstrate that lack of CFTR itself does not cause smooth muscle dysfunction, because the circular muscle from P5 CF mice had normal activity and dysfunction developed between P7 and P14.

Relation between dietary fat intake type and serum fatty acid status in children with cystic fibrosis

BACKGROUND AND OBJECTIVE

Children with cystic fibrosis (CF) and pancreatic insufficiency (PI) are at risk for fatty acid (FA) abnormalities and essential FA deficiency, with low linoleic acid (LA) and docosahexaenoic acid (DHA) concentrations and abnormal triene:tetraene (T:T) and arachidonic acid (AA):DHA ratios. The aim of the article was to determine whether type of dietary fat predicted serum LA, DHA, T:T, and AA:DHA ratios in subjects with CF and PI as compared to an unaffected comparison group.

METHODS

Serum FA concentrations were assessed by capillary gas-liquid chromatography (mol%) and dietary intake by 7-day weighed food records; the 3-day coefficient of fat absorption was calculated. Total energy intake was expressed in kilocalories.

RESULTS

A total of 65 subjects with CF and PI (8.4 ± 1.0 years, 32 girls) and 22 controls (8.5 ± 1.1 years, 13 girls) were included. Despite greater energy, saturated fat, and LA intake, the subjects with CF had lower serum LA and DHA and higher T:T and AA:DHA than those in the comparison group. Dietary total fat, monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA), LA, total ω 6 polyunsaturated fatty acid (Tω6PUFA), and α-linolenic acid (ALA) intake positively predicted serum LA concentration. MUFA, total ω 3 polyunsaturated fatty acid (Tω3PUFA), and ALA intake positively predicted serum DHA concentration. Total dietary fat, MUFA, PUFA, Tω3PUFA, LA, and ALA intake negatively predicted serum T:T. ALA and Tω3PUFA intake negatively predicted serum AA:DHA.

CONCLUSIONS

Dietary fat patterns influenced serum LA, DHA, T:T, and AA:DHA in children with CF and PI. These data suggest that changes in dietary practices may result in FA profiles associated with improved clinical outcomes.

Lung transplantation in cystic fibrosis normalizes essential fatty acid profiles

BACKGROUND

Cystic fibrosis (CF) can be a devastating disease. Disorders in essential fatty acid state are increasingly reported and various supplementation trials have been performed in an attempt to improve outcomes. However, the mechanisms leading to these disturbances remain elusive. We wanted to investigate the role of the diseased CF lung on fatty acid profiles.

METHODS

We compared fatty acid profiles in patients with CF after lung transplantation (n=11) to age-matched healthy controls and homozygous F508del patients (n=22 each).

RESULTS

Compared to healthy controls, in patients with CF, there are decreased levels of docosahexaenoic, linoleic and arachidonic acid and increased levels of mead acid. In patients that underwent a lung transplantation, levels of docosahexaenoic, linoleic and arachidonic acid were normal. Mead acid did not decrease significantly.

CONCLUSIONS

The diseased CFTR deficient lung is a major determinant in the disturbed fatty acid profile in CF.

Omics approaches in cystic fibrosis research: a focus on oxylipin profiling in airway secretions

Cystic fibrosis (CF) is associated with abnormal lipid metabolism, intense respiratory tract (RT) infection, and inflammation, eventually resulting in lung tissue destruction and respiratory failure. The CF RT inflammatory milieu, as reflected by airway secretions, includes a complex array of inflammatory mediators, bacterial products, and host secretions. It is dominated by neutrophils and their proteolytic and oxidative products and includes a wide spectrum of bioactive lipids produced by both host and presumably microbial metabolic pathways. The fairly recent advent of "omics" technologies has greatly increased capabilities of further interrogating this easily obtainable RT compartment that represents the apical culture media of the underlying RT epithelial cells. This paper discusses issues related to the study of CF omics with a focus on the profiling of CF RT oxylipins. Challenges in their identification/quantitation in RT fluids, their pathways of origin, and their potential utility for understanding CF RT inflammatory and oxidative processes are highlighted. Finally, the utility of oxylipin metabolic profiling in directing optimal therapeutic approaches and determining the efficacy of various interventions is discussed.

Effect of allergy and inflammation on eicosanoid gene expression in CFTR deficiency

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) is a complicating factor in cystic fibrosis (CF), affecting 2-15% of patients. We hypothesized that sensitization/challenge of CFTR(-/-) mice with an Aspergillus fumigatus (Af) extract will affect eicosanoid pathway gene expression, impacting ABPA and CF.

METHODS

FABP-hCFTR(+/-)-CFTR(-/-) mice were sensitized/challenged with an Af extract and gene expression of lung mRNA was evaluated for >40 genes, with correlative data in human CF (IB3.1) and CFTR-corrected (S9) bronchoepithelial cell lines.

RESULTS

Pla2g4c, Pla2g2c, Pla2g2d and Pla2g5 were induced in response to Af in CFTR(-/-) mice. Interestingly, PLA2G2D was induced by LPS, IL-2, IL-6, IL-13, and Af only in CFTR-deficient human IB3.1 cells. Prostanoid gene expression was relatively constant, however, several 12/15-lipoxygenase genes were induced in response to Af. Numerous cytokines also caused differential expression of ALOX15 only in IB3.1 cells.

CONCLUSIONS

The distinct regulation of PLA2G4C, PLA2G2D and ALOX15 genes in Aspergillus sensitization and/or cystic fibrosis could provide new insights into diagnosis and treatment of ABPA and CF.

Resolution of inflammation in asthma

The resolution of inflammation in healthy airways is an active process, with specialized mediators and cellular mechanisms enlisted to restore tissue homeostasis. This article focuses on recent discoveries of natural mediators derived from essential fatty acids, including ω-3 fatty acids, with anti-inflammatory and pro-resolving. These pro-resolving mediators serve as agonists at specific receptors. Asthma is an incurable disease of chronic, nonresolving inflammation of the airways. While the biosynthesis of pro-resolving mediators occurs during asthma, defects in their production are associated with disease severity, suggesting that the pathobiology of asthma may result in part from impaired resolution of airway inflammation.

Resolvin D1 and aspirin-triggered resolvin D1 promote resolution of allergic airways responses

Asthma is a disease of airway inflammation that in most cases fails to resolve. The resolution of inflammation is an active process governed by specific chemical mediators, including D-series resolvins. In this study, we determined the impact of resolvin D1 (RvD1) and aspirin-triggered RvD1 (AT-RvD1) on the development of allergic airway responses and their resolution. Mice were allergen sensitized, and RvD1, AT-RvD1 (1, 10, or 100 ng), or vehicle was administered at select intervals before or after aerosol allergen challenge. RvD1 markedly decreased airway eosinophilia and mucus metaplasia, in part by decreasing IL-5 and IκBα degradation. For the resolution of established allergic airway responses, AT-RvD1 was even more efficacious than RvD1, leading to a marked decrease in the resolution interval for lung eosinophilia, decrements in select inflammatory peptide and lipid mediators, and more rapid resolution of airway hyperreactivity to methacholine. Relative to RvD1, AT-RvD1 resisted metabolic inactivation by macrophages, and AT-RvD1 significantly enhanced macrophage phagocytosis of IgG-OVA-coated beads in vitro and in vivo, a new proresolving mechanism for the clearance of allergen from the airways. In conclusion, RvD1 and AT-RvD1 can serve as important modulators of allergic airway responses by decreasing eosinophils and proinflammatory mediators and promoting macrophage clearance of allergen. Together, these findings identify D-series resolvins as potential proresolving therapeutic agents for allergic responses.

Metabolomic profiling of regulatory lipid mediators in sputum from adult cystic fibrosis patients

Retained respiratory tract (RT) secretions, infection, and exuberant inflammatory responses are core abnormalities in cystic fibrosis (CF) lung disease. Factors contributing to the destructive CF airway inflammatory processes remain incompletely characterized. The pro-oxidative inflammatory CF RT milieu is known to contain enzymatically and nonenzymatically produced regulatory lipid mediators, a panel of structurally defined oxidized metabolites of polyunsaturated fatty acids known to play a role in pathology related to inflammation. Using an extraction protocol that maximizes recoveries of sputum-spiked deuterated standards, coupled with an LC/MS/MS detection system, this study presents a metabolomic method to assess a broad spectrum of regulatory lipid mediators in freshly obtained sputum from CF patients. A broad range of both proinflammatory and anti-inflammatory lipid mediators was detected, including PGE2, PGD2, TXB2, LTB4, 6-trans-LTB4, 20-OH-LTB4, 20-COOH-LTB4, 20-HETE, 15-HETE, 11-HETE, 12-HETE, 8-HETE, 9-HETE, 5-HETE, EpETrEs, diols, resolvin E1, 15-deoxy-PGJ2, and LXA4. The vast majority of these oxylipins have not been reported previously in CF RT secretions. Whereas direct associations of individual proinflammatory lipid mediators with compromised lung function (FEV-1) were observed, the relationships were not robust. However, multiple statistical analyses revealed that the regulatory lipid mediators profile taken in aggregate proved to have a stronger association with lung function in relatively stable outpatient adult CF patients. Our data reveal a relative paucity of the anti-inflammatory lipid mediator lipoxin A4 in CF sputum. Patients displaying detectable levels of the anti-inflammatory lipid mediator resolvin E1 demonstrated a better lung function compared to those patients with undetectable levels. Our data suggest that comprehensive metabolomic profiling of regulatory lipid mediators in CF sputum should contribute to a better understanding of the molecular mechanisms underlying CF RT inflammatory pathobiology. Further studies are required to determine the extent to which nutritional or pharmacological interventions alter the regulatory lipid mediators profile of the CF RT and the impact of potential modulations of RT regulatory lipid mediators on the clinical progression of CF lung disease.

Long-chain PUFA in granulocytes, mononuclear cells, and RBC in patients with cystic fibrosis: relation to liver disease

BACKGROUND AND AIM

Patients with cystic fibrosis (CF) have low levels of n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) in plasma or red blood cells (RBC), as also seen in other chronic and acute liver diseases. The differences may be more pronounced in CF transmembrane conductance regulator protein (CFTR)-regulated tissues such as granulocytes, monocytes, and lymphocytes. The aim of the present study was to investigate whether patients with CF-related liver disease have lower n-3 LCPUFA level than patients with CF without liver disease.

METHODS

Twenty patients with known CF-related liver disease were matched with 20 CF patients without. Blood samples were analysed for liver biochemistry and haematology. Granulocytes, mononuclear cells, and RBC were separated by density gradient centrifugation, and fatty acid composition was measured by gas chromatography. Hepatic ultrasound was scored according to Williams et al. Hepatic transit time (HTT) was measured with the ultrasound contrast agent SonoVue.

RESULTS

No significant differences were seen in either n-6 or n-3 LCPUFAs in any cell line when the 2 groups were compared. In a multiple regression analysis including HTT, age, Pseudomonas aeruginosa infection, diabetes mellitus, treatment with ursodeoxycholic acid, forced expiratory volume in 1 second (% of predicted value), and Williams' ultrasound scoring scale, only n-3 LCPUFA docosahexaenoic acid in mononuclear cell membranes was positively associated with HTT (P = 0.02). The arachidonic acid/docosahexaenoic acid ratio within the mononuclear cells was negatively associated with both HTT (P = 0.003) and Williams' ultrasound scoring scale (P = 0.03). For RBC-LCPUFAs, no significant associations were seen.

CONCLUSIONS

These findings indicate that in patients with CF, the degree of liver disease was negatively associated with LCPUFA n-3 levels in CFTR-expressing white blood cells but unrelated to those levels in CFTR-negative RBC.

Do annexins participate in lipid messenger mediated intracellular signaling? A question revisited

Annexins are physiologically important proteins that play a role in calcium buffering but also influence membrane structure, participate in Ca²⁺-dependent membrane repair events and in remodelling of the cytoskeleton. Thirty years ago several peptides isolated from lung perfusates, peritoneal leukocytes, neutrophiles and renal cells were proven inhibitory to the activity of phospholipase A₂. Those peptides were found to derive from structurally related proteins: annexins AnxA1 and AnxA2. These findings raised the question whether annexins may participate in regulation of the production of lipid second messengers and, therefore, modulate numerous lipid mediated signaling pathways in the cell. Recent advances in the field of annexins made also with the use of knock-out animal models revealed that these proteins are indeed important constituents of specific signaling pathways. In this review we provide evidence supporting the hypothesis that annexins, as membrane-binding proteins and organizers of the membrane lateral heterogeneity, may participate in lipid mediated signaling pathways by affecting the distribution and activity of lipid metabolizing enzymes (most of the reports point to phospholipase A₂) and of protein kinases regulating activity of these enzymes. Moreover, some experimental data suggest that annexins may directly interact with lipid metabolizing enzymes and, in a calcium-dependent or independent manner, with some of their substrates and products. On the basis of these observations, many investigators suggest that annexins are capable of linking Ca²⁺, redox and lipid signaling to coordinate vital cellular responses to the environmental stimuli.

PPARγ as a therapeutic target in cystic fibrosis

Cystic fibrosis (CF) is characterized by a proinflammatory pulmonary condition that may result from increased infections and altered intracellular metabolism in CFTR-deficient cells. The lipid-activated transcription factor peroxisome proliferator-activated receptor-γ (PPARγ) has well-established roles in immune cell function and inflammatory modulation and has been demonstrated to play an important role in the heightened inflammatory response in CF cells. Here, we summarize current literature describing PPARγ-dependent alterations of CF cells and discuss the potential of PPARγ ligands for treating CF.

Macrophage proresolving mediator maresin 1 stimulates tissue regeneration and controls pain

Self-resolving inflammatory exudates and lipid mediator metabolomics recently uncovered a new family of potent anti-inflammatory and proresolving mediators biosynthesized by macrophages (MΦs), denoted maresins. Here we determined that maresin 1 (MaR1) produced by human MΦs from endogenous docosahexaenoic acid (DHA) matched synthetic 7R,14S-dihydroxydocosa-4Z,8E,10E,12Z,16Z,19Z-hexaenoic acid. The MaR1 alcohol groups and Z/E geometry of conjugated double bonds were matched using isomers prepared by total organic synthesis. MaR1's potent defining actions were confirmed with synthetic MaR1, i.e., limiting polymorphonuclear neutrophil (PMN) infiltration in murine peritonitis (ng/mouse range) as well as enhancing human macrophage uptake of apoptotic PMNs. At 1 nM, MaR1 was slightly more potent than resolvin D1 in stimulating human MΦ efferocytosis, an action not shared by leukotriene B(4). MaR1 also accelerated surgical regeneration in planaria, increasing the rate of head reappearance. On injury of planaria, MaR1 was biosynthesized from deuterium-labeled (d(5))-DHA that was blocked with lipoxygenase (LOX) inhibitor. MaR1 dose-dependently inhibited TRPV1 currents in neurons, blocked capsaicin (100 nM)-induced inward currents (IC(50) 0.49±0.02 nM), and reduced both inflammation- and chemotherapy-induced neuropathic pain in mice. These results demonstrate the potent actions of MaR1 in regulating inflammation resolution, tissue regeneration, and pain resolution. These findings suggest that chemical signals are shared in resolution cellular trafficking, a key process in tissue regeneration. Moreover, immunoresolvents of the innate immune response, such as MaR1, offer new opportunities for assessing MΦs and their local DHA metabolome in the return to tissue homeostasis.

Avaliação e recomendações nutricionais para crianças e adolescentes com fibrose cística

OBJETIVO: Revisar e discutir evidências sobre a avaliação do estado nutricional e as recomendações para o tratamento nutricional de crianças e adolescentes com fibrose cística. FONTES DE DADOS: Bancos de dados MEDLINE (versão PubMed) e Latin American and Caribbean Center on Health Sciences Information (LILACS), entre 1984 a 2009. Aplicou-se a combinação dos seguintes descritores: fibrose cística, estado nutricional, criança e adolescente - em inglês e português. SÍNTESE DOS DADOS: A fibrose cística é uma doença genética, de evolução crônica, progressiva e fatal. Resulta do defeito na proteína reguladora transmembrana que regula a condução de cloro e, consequentemente, o fluxo de sódio e água através da membrana apical das células epiteliais. Pacientes fibrocísticos são vulneráveis à desnutrição, que resulta do desequilíbrio entre ingestão alimentar, gasto e perdas energéticas. Novos conhecimentos sobre a fisiopatologia da doença, adquiridos nas últimas décadas, resultaram em mudanças significativas nas atuais recomendações energéticas e principalmente de lipídeos. A importância da nutrição no bem-estar e sobrevida dos fibrocísticos está bem estabelecida, assim como a associação entre a desnutrição e a deterioração da função pulmonar. Existem múltiplos fatores inter-relacionados que afetam o estado nutricional, tais como, mutação genética, insuficiência pancreática, ressecção intestinal, perda de sais e ácidos biliares, refluxo gastroesofágico, inflamação e infecções pulmonares, diabetes e condições emocionais. CONCLUSÕES: O monitoramento nutricional e o aconselhamento dietético são elementos chave no manejo de crianças e adolescentes com fibrose cística com o intuito de controlar a sintomatologia e a progressão da doença, proporcionando melhor qualidade de vida.

The safety and efficacy of oral docosahexaenoic acid supplementation for the treatment of primary sclerosing cholangitis - a pilot study

BACKGROUND

Primary sclerosing cholangitis (PSC) is characterised by progressive inflammatory and fibrotic destruction of the biliary ducts. There are no effective medical therapies and presently high dose ursodeoxycholic acid is no longer recommended due to significant adverse events in a recent clinical trial. Cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction is associated with PSC in both children and adults. Since CFTR dysfunction leads to altered fatty acid metabolism, specifically reduced docosahexaenoic acid (DHA), we hypothesised that DHA supplementation might be an effective therapy for patients with PSC.

AIM

To determine the safety and efficacy of oral DHA supplementation for the treatment of PSC.

METHODS

We conducted a 12 month open-label pilot study to evaluate safety of oral DHA and its effects on serum alkaline phosphatase as a primary outcome measure in 23 patients with PSC. DHA was administered orally at 800 mg twice per day. Secondary outcomes included changes in other liver function tests and fibrosis biomarkers.

RESULTS

A 1.7-fold increase in serum DHA levels was observed with supplementation. The mean alkaline phosphatase level (±S.E.) at baseline was 357.8 ± 37.1 IU compared to 297.1 ± 23.7 IU (P < 0.05) after 12 months of treatment. There were no changes in other liver function tests and fibrosis biomarkers. No adverse events were reported.

CONCLUSIONS

Oral DHA supplementation is associated with an increase in serum DHA levels and a significant decline in alkaline phosphatase levels in patients with PSC. These data support the need for a rigorous trial of DHA therapy in PSC.

Decreased postnatal docosahexaenoic and arachidonic acid blood levels in premature infants are associated with neonatal morbidities

OBJECTIVE

To measure the changes in whole blood fatty acid levels in premature infants and evaluate associations between these changes and neonatal morbidities.

STUDY DESIGN

This was a retrospective cohort study of 88 infants born at <30 weeks' gestation. Serial fatty acid profiles during the first postnatal month and infant outcomes, including chronic lung disease (CLD), retinopathy of prematurity, and late-onset sepsis, were analyzed. Regression modeling was applied to determine the association between fatty acid levels and neonatal morbidities.

RESULTS

Docosahexaenoic acid (DHA) and arachidonic acid levels declined rapidly in the first postnatal week, with a concomitant increase in linoleic acid levels. Decreased DHA level was associated with an increased risk of CLD (OR, 2.5; 95% CI, 1.3-5.0). Decreased arachidonic acid level was associated with an increased risk of late-onset sepsis (hazard ratio, 1.4; 95% CI, 1.1-1.7). The balance of fatty acids was also a predictor of CLD and late-onset sepsis. An increased linoleic acid:DHA ratio was associated with an increased risk of CLD (OR, 8.6; 95% CI, 1.4-53.1) and late-onset sepsis (hazard ratio, 4.6; 95% CI, 1.5-14.1).

CONCLUSION

Altered postnatal fatty acid levels in premature infants are associated with an increased risk of CLD and late-onset sepsis.

Supplementation of N-3 LCPUFA to the diet of children older than 2 years: a commentary by the ESPGHAN Committee on Nutrition

The aim of this commentary is to review data on the effect of supplementation of paediatric patients ages 2 years or older with n-3 long-chain polyunsaturated fatty acids (LCPUFA). Some evidence for a positive effect on functional outcome in children with attention-deficit/hyperactivity disorder (ADHD) was found; however, benefit was seen in only about half of the randomised controlled trials (RCT), and studies varied widely not only in dose and form of supplementation but also in the functional outcome parameter tested. The committee concludes that there are insufficient data to recommend n-3 LCPUFA supplementation in the treatment of children with ADHD, but further research on n-3 LCPUFA supplementation in ADHD may be worthwhile. The committee was unable to find evidence of a favourable effect of n-3 LCPUFA supplementation on cognitive function in children. Although no benefit of n-3 LCPUFA supplementation was seen for major clinical outcome parameters in children with cystic fibrosis, a potentially beneficial shift towards less-inflammatory eicosanoid profiles seen in 2 studies provides grounds for further investigation; it is possible that earlier and longer supplementation periods may be needed to demonstrate clinical effect. For children with phenylketonuria, the limited data available suggest that supplementation of n-3 LCPUFA to the diet is both feasible and safe, but offers only transient benefit in visual function. For children with bronchial asthma there are insufficient data to suggest that LCPUFA supplementation has a beneficial effect. The committee advises paediatricians that most health claims about supplementation of n-3 LCPUFA in various diseases in children and adolescents are not supported by convincing scientific data.

Fish oil enhances recovery of intestinal microbiota and epithelial integrity in chronic rejection of intestinal transplant

Background

The intestinal chronic rejection (CR) is the major limitation to long-term survival of transplanted organs. This study aimed to investigate the interaction between intestinal microbiota and epithelial integrity in chronic rejection of intestinal transplantation, and to find out whether fish oil enhances recovery of intestinal microbiota and epithelial integrity.

Methods/Principal Findings

The luminal and mucosal microbiota composition of CR rats were characterized by DGGE analysis at 190 days after intestinal transplant. The specific bacterial species were determined by sequence analysis. Furthermore, changes in the localization of intestinal TJ proteins were examined by immunofluorescent staining. PCR-DGGE analysis revealed that gut microbiota in CR rats had a shift towards Escherichia coli, Bacteroides spp and Clostridium spp and a decrease in the abundance of Lactobacillales bacteria in the intestines. Fish oil supplementation could enhance the recovery of gut microbiota, showing a significant decrease of gut bacterial proportions of E. coli and Bacteroides spp and an increase of Lactobacillales spp. In addition, CR rats showed pronounced alteration of tight junction, depicted by marked changes in epithelial cell ultrastructure and redistribution of occuldin and claudins as well as disruption in TJ barrier function. Fish oil administration ameliorated disruption of epithelial integrity in CR, which was associated with an improvement of the mucosal structure leading to improved tight junctions.

Conclusions/Significance

Our study have presented novel evidence that fish oil is involved in the maintenance of epithelial TJ integrity and recovery of gut microbiota, which may have therapeutic potential against CR in intestinal transplantation.

(n-3) long-chain PUFA differentially affect resistance to Pseudomonas aeruginosa infection of male and female cftr-/- mice

The aim of this study was to determine whether oral supplementation with EPA/DHA (10.5 and 5.1% of fat, respectively) could improve the outcome of pulmonary P. aeruginosa infection in cftr(-/-) mice compared with wild-type (Wt) mice similarly treated. Because gender could influence the susceptibility of cftr-deficient mice, results were analyzed by gender. Wt and (-/-) mice were randomized for 6 wk to consume a control or EPA/DHA diet, infected with endotracheal injection of 5 × 10(7) CFU/mouse of P. aeruginosa, and killed 24 h later. Cftr(-/-) mice were more susceptible to infection than were Wt mice; (-/-) males had more neutrophils (P < 0.01) and a higher keratinocyte-derived chemokine (KC) level (P < 0.05), and (-/-) females had greater lung injury and mortality (P < 0.05). Female (-/-) mice were more susceptible than (-/-) males with a higher mortality and lung injury (P < 0.05). The EPA/DHA diet reduced neutrophil numbers and KC and IL-6 levels (P < 0.05) in (-/-) males and reduced mortality rate (P < 0.001), lung permeability, and IL-6 level (P < 0.05) in (-/-) females compared with (-/-) mice fed the control diet. These results were associated with a reduction in the pulmonary bacterial load (P < 0.05), an increase in the EPA/DHA concentration in cell membranes of (-/-) males and females (P < 0.01), and an increased weight gain only in males compared with (-/-) mice fed the control diet (P < 0.01). In conclusion, EPA/DHA improves the host resistance of (-/-) mice, although the beneficial effect differed in males and females.

Fat-1 transgenic mice with elevated omega-3 fatty acids are protected from allergic airway responses

Omega-3 polyunsaturated fatty acids (n-3 PUFA) have been implicated in the alleviation of asthma. Recent studies have demonstrated that the n-3 PUFA derived lipid mediators, protectin D1 and resolvin E1, may act as potent resolution agonists in airway inflammation. The effects of the n-3 PUFA tissue status itself on asthma pathogenesis remains to be further investigated. In this study allergic airway inflammation induced by allergen sensitization and aerosol challenge in Fat-1 and wild-type mice was investigated. Fat-1 transgenic mice displayed increased endogenous lung n-3 PUFA. When allergen-sensitized and aerosol-challenged, these animals had decreased airway inflammation with decreased leukocyte accumulation in bronchoalveolar lavage fluid and lung parenchyma. The Fat-1 mice had a shift to the right in the dose-response relationship for methacholine induced bronchoconstriction with a significant increase in the log ED200. The Fat-1 mice had lower BALF concentrations of the pro-inflammatory cytokines IL-1α, IL-2, IL-5, IL-9, IL-13, G-CSF, KC and RANTES. Furthermore, increased lung tissue amounts of the counter-regulatory mediators protectin D1 and resolvin E1 were found in Fat-1 mice after bronchoprovocative challenge. These results therefore demonstrate a direct protective role for lung n-3 PUFA in allergic airway responses and an increased generation of protectin D1 and resolvin E1 in this context.

MicroRNA profiling of cystic fibrosis intestinal disease in mice

Cystic fibrosis (CF) intestinal disease is characterized by alterations in processes such as proliferation and apoptosis which are known to be regulated in part by microRNAs. Herein, we completed microRNA expression profiling of the intestinal tissue from the cystic fibrosis mouse model of cystic fibrosis transmembrane conductance regulator (Cftr) deficient mice (BALBc/J Cftr(tm1UNC)), relative to that of wildtype littermates, to determine whether changes in microRNA expression level are part of this phenotype. We identified 24 microRNAs to be significantly differentially expressed in tissue from CF mice compared to wildtype, with the higher expression in tissue from CF mice. These data were confirmed with real time PCR measurements. A comparison of the list of genes previously reported to have decreased expression in the BALB×C57BL/6J F2 CF intestine to that of genes putatively targeted by the 24 microRNAs, determined from target prediction software, revealed 155 of the 759 genes of the expression profile (20.4%) to overlap with predicted targets, which is significantly more than the 100 genes expected by chance (p=1×10(-8)). Pathway analysis identified these common genes to function in phosphatase and tensin homolog-, protein kinase A-, phosphoinositide-3 kinase/Akt- and peroxisome proliferator-activated receptor alpha/retinoid X receptor alpha signaling pathways, among others, and through real time PCR experiments genes of these pathways were demonstrated to have lower expression in the BALB CF intestine. We conclude that altered microRNA expression is a feature which putatively influences both metabolic abnormalities and the altered tissue homeostasis component of CF intestinal disease.

Persistent fat malabsorption in cystic fibrosis; lessons from patients and mice

Fat malabsorption in pancreatic insufficient cystic fibrosis (CF) patients is classically treated with pancreatic enzyme replacement therapy (PERT). Despite PERT, intestinal fat absorption remains insufficient in most CF patients. Several factors have been suggested to contribute to the persistent fat malabsorption in CF (CFPFM). We reviewed the current insights concerning the proposed causes of CFPFM and the corresponding intervention studies. Most data are obtained from studies in CF patients and CF mice. Based on the reviewed literature, we conclude that alterations in intestinal pH and intestinal mucosal abnormalities are most likely to contribute to CFPFM. The presently available data indicate that acid suppressive drugs and broad spectrum antibiotics could be helpful in individual CF patients for optimizing fat absorption and/or nutritional status.

Renal function in pediatric cystic fibrosis patients in the first decade of life

With increasing life expectancy and the need for lung transplantation in the cystic fibrosis (CF) population, there are increasing reports of chronic kidney disease (CKD). However, values for baseline or longitudinal glomerular filtration rate (GFR) as measured by exogenous clearance markers are lacking in this population. Retrospective cross-sectional study in 2 to 18-year-olds cared for at a single CF center who had a GFR measured by plasma disappearance of Technetium-99 m diethylenetriaminepentaacetic acid (mGFR). The primary outcome was evidence of renal dysfunction as defined by CKD stage II or below (mGFR <90 ml/min/1.73 m(2), persistent abnormalities in urinary sediment, abnormal renal imaging). Of 63 patients evaluated, four had apparent renal dysfunction, one demonstrated decreased mGFR, and three others had persistent microscopic hematuria. The mean mGFR was substantially higher (140 ± 24 ml/min/1.73 m(2)) than expected or previously reported for healthy children. We did not demonstrate the presence of significant renal impairment after limited aminoglycoside exposure in the first decade following diagnosis with CF. However, we did document the presence of glomerular hyperfiltration in a significant proportion of our CF patients.

Docosahexaenoic acid modulates in vitro the inflammation of celiac disease in intestinal epithelial cells via the inhibition of cPLA2

BACKGROUND & AIMS

The cytosolic phospolypase A(2) (cPLA(2)) - dependent release of arachidonic acid (AA) from the intra-epithelial lymphocytes plays a pivotal role in arming lymphocytes to cytolysis in the immune response of celiac disease. However, little is known about the role of enterocytes in releasing AA. Docosahexaenoic acid (DHA) is a long chain polyunsaturated fatty acid that counteracts many of the proinflammatory effect of AA. The aims of the present work were to evaluate if: 1) intestinal epithelial cells have a role in the celiac inflammation, releasing AA, and 2) if DHA is able to modulate the celiac inflammation, down-regulating the release of AA.

METHODS

A human intestinal epithelial cell line (Caco-2) was exposed to gliadin peptides (PT-gl) (500 μg/ml) and DHA (2 μg/ml), both alone and simultaneously up to 24 h.

RESULTS

The exposure of those cells to PT-gl alone resulted in an increased AA release, cycloxygenase-2 expression, cPLA(2) activity and prostaglandin E(2) and interleukin-8 release in culture medium, whereas the simultaneous exposure of the cells to DHA and PT-gl prevented the above-mentioned increases.

CONCLUSIONS

These results suggest that intestinal epithelial cells sustain the celiac inflammation, releasing AA when stimulated with gliadin and that DHA inhibits the AA release by these cells.

Plasma lipidomics reveals potential prognostic signatures within a cohort of cystic fibrosis patients

Cystic fibrosis (CF) is associated with abnormal lipid metabolism. We have recently shown variations in plasma levels of several phosphatidylcholine (PC) and lysophopshatidylcholine (LPC) species related to disease severity in CF patients. Here our goal was to search for blood plasma lipid signatures characteristic of CF patients bearing the same mutation (F508del) and different phenotypes, and to study their correlation with forced expiratory volume in 1 s (FEV1) and Pseudomonas aeruginosa chronic infection, evaluated at the time of testing (t = 0) and three years later (t = 3). Samples from 44 F508del homozygotes were subjected to a lipidomic approach based on LC-ESI-MS. Twelve free fatty acids were positively correlated with FEV1 at t = 0 (n = 29). Four of them (C20:3n-9, C20:5n-3, C22:5n-3, and C22:6n-3) were also positively correlated with FEV1 three years later, along with PC(32:2) and PC(36:4) (n = 31). Oleoylethanolamide (OEA) was negatively correlated with FEV1 progression (n = 17). Chronically infected patients at t = 0 showed lower PC(32:2), PC(38:5), and C18:3n-3 and higher cholesterol, cholesterol esters, and triacylglycerols (TAG). Chronically infected patients at t = 3 showed significantly lower levels of LPC(18:0). These results suggest a potential prognostic value for some lipid signatures in, to our knowledge, the first longitudinal study aimed at identifying lipid biomarkers for CF.

Resolvins: natural agonists for resolution of pulmonary inflammation

Inappropriate or excessive pulmonary inflammation can contribute to chronic lung diseases. In health, the resolution of inflammation is an active process that terminates inflammatory responses. The recent identification of endogenous lipid-derived mediators of resolution has provided a window to explore the pathobiology of inflammatory disease and structural templates for the design of novel pro-resolving therapeutics. Resolvins (resolution-phase interaction products) are a family of pro-resolving mediators that are enzymatically generated from essential omega-3 polyunsaturated fatty acids. Two molecular series of resolvins have been characterised, namely E- and D-series resolvins which possess distinct structural, biochemical and pharmacological properties. Acting as agonists at specific receptors (CMKLR1, BLT1, ALX/FPR2 and GPR32), resolvins can signal for potent counter-regulatory effects on leukocyte functions, including preventing uncontrolled neutrophil swarming, decreasing the generation of cytokines, chemokines and reactive oxygen species and promoting clearance of apoptotic neutrophils from inflamed tissues. Hence, resolvins provide mechanisms for cytoprotection of host tissues to the potentially detrimental effects of unresolved inflammation. This review highlights recent experimental findings in resolvin research, and the impact of these stereospecific molecules on the resolution of pulmonary inflammation and tissue catabasis.

Neutrophil unsaturated fatty acid release by GM-CSF is impaired in cystic fibrosis

Dysregulated inflammation in cystic fibrosis (CF) is attributed to an altered production of inflammatory mediators derived from polyunsaturated lipids. In comparison to the arachidonic acid (AA) cascade, little is known about the modulation of docosahexaenoic acid (DHA) membrane release. We compared data on neutrophil DHA- and AA- release from both control (CT) and patients with CF using [³H]AA or [¹⁴C]DHA as a markers for, respectively, AA and DHA- release. Granulocyte-macrophage-colony stimulating factor stimulated DHA release from CT, but not CF, neutrophils. Comparison showed that both [¹⁴C]DHA and [³H]AA liberated after stimulation was higher in CT than in CF neutrophils. Since bioactive mediators derived from DHA are resolving factors and those derived from AA are both pro- and anti- inflammatory, these results suggest that CF is associated with a reduction of the release of PUFA-precursors of lipooxygenated resolving mediators. This leads to the hypothesis that defects in the resolving factors production could contribute to the inflammatory dysregulated processes in CF. Furthermore, the methodology used may help to improve knowledge on the regulation and resolution of inflammation.

Fatty acid composition of serum phospholipids in cystic fibrosis (CF) patients with or without CF related liver disease

BACKGROUND

In cystic fibrosis (CF), changes in fatty acid (FA) composition of serum phospholipids (PL) and cell membranes can account, in part, for the inflammatory state of the disease. The severity of the genotype is known to correlate with the degree of FA changes. Liver diseases, such as cholestasis and cirrhosis are also known to influence FA status. Until now, there is no data on the influence of CF related liver disease (CFRLD) on the FA status of CF patients. The aim of this study was to evaluate, whether the presence of CFRLD influences FA status.

METHODS

A fasting blood sample for the determination of serum vitamin E and PL-FA composition was collected from 79 CF patients with stable pulmonary disease and under good control in our CF centre. Patients with CFRLD (n=13) were compared to CF patients with the same severity of genotype (n=66) but without CFRLD.

RESULTS

The CF patients with CFRLD had lower docosahexaenoic acid (DHA, 22:6n-3) and increased docosatetraenoic acid (22:4n-6). There were no significant differences in the precursors of these FAs.

CONCLUSIONS

DHA concentration in patients with CFRLD is decreased more substantially compared with their genotype controls. The presence of CFRLD should be taken into account in future FA studies in CF patients.

Antimicrobial lipids: novel innate defense molecules are elevated in sinus secretions of patients with chronic rhinosinusitis

BACKGROUND

Airway secretions possess intrinsic antimicrobial properties that contribute to the innate host defense of the respiratory tract. These microbicidal capabilities have largely been attributed to the presence of antibacterial polypeptides. However, recent investigation has indicated that host-derived lipids including cholesteryl esters also exhibit antimicrobial properties. The purpose of this study was to determine whether sinus secretions contain such antimicrobial lipids and to compare the lipid composition in patients with and without chronic rhinosinusitis (CRS).

METHODS

Maxillary sinus fluid was obtained via antral lavage from subjects with (seven patients) and without (nine patients) a history of CRS. After specimen collection, total lipid was extracted according to Bligh and Dyer (Bligh EG and Dyer WJ, A rapid method of total lipid extraction and purification, Can J Biochem Physiol 37:911-918, 1959) and lipid profiles were obtained by reverse phase high-performance liquid chromatography on an amide-embedded C18 column. In addition, the neutrophil-specific antimicrobial peptides human neutrophil peptides 1-3 (HNP1-3) were quantified by Western immunoblotting.

RESULTS

Lipids, including cholesteryl esters, were identified in the maxillary sinus secretions of patients with and without CRS. However, levels of lipid composition differed between the two groups with CRS patients exhibiting greater amounts of all classes of lipids, reaching over 10-fold higher concentration when compared with non-CRS patients. This increase was independent of HNP1-3 content.

CONCLUSION

Sinus secretions of patients with CRS appear to show elevated levels of antimicrobial lipids compared with controls independent from neutrophil influx. This up-regulation suggests that host-derived lipids act as mediators of mucosal immunity in CRS. Further study is necessary to determine if such antimicrobial lipids function alone or synergistically with antibacterial peptides in conferring such inherent microbicidal properties.

Fatty acid metabolism in cystic fibrosis

Despite identification twenty years ago of the gene responsible for cystic fibrosis transmembrane conductance regulator (CFTR), the protein defective in cystic fibrosis (CF), research of this monogenetic disease has not provided an explanation for the divergent symptoms, and a treatment breakthrough is still awaited. This review discusses different aspects of disturbances in lipid metabolism seen in CF. These include increased release of arachidonic acid (AA) from cell membrane phospholipids and a low status of linoleic and docosahexaenoic acids. Recent research has explored more complicated lipid associations. Disturbances in annexins and ceramides might act in concert to explain the impact on inflammation and AA release. The connections to CFTR and between the disturbances in essential fatty acid metabolism are reviewed. The metabolic interactions, some of which might be compensating, possibly explain the difficulties in understanding the fatty acid disturbances in relation to different symptoms and their relation to the defective CFTR.

Overcoming reduced glucocorticoid sensitivity in airway disease: molecular mechanisms and therapeutic approaches

There is a considerable and growing unmet medical need in respiratory disease concerning effective anti-inflammatory therapies for conditions such as severe asthma, chronic obstructive pulmonary disease and cystic fibrosis. These diseases share a predominant characteristic of an enhanced and uncontrolled inflammatory response in the lungs, which contributes to disease progression, hospitalization and mortality. These diseases are poorly controlled by current anti-inflammatory therapies including glucocorticoids, which are otherwise effective in many other inflammatory conditions or in milder disease such as asthma. The exact cause of this apparent impairment of glucocorticoid function remains largely unclear; however, recent studies have now implicated a number of possible mechanisms. Central among these is an elevation of the oxidant burden in the lungs and the resulting reduction in the activity of histone deacetylase (HDAC)-2. This contributes to both the enhancement of proinflammatory mediator expression and the impaired ability of the glucocorticoid receptor (GR)-alpha to repress proinflammatory gene expression. The oxidant-mediated reduction in HDAC-2 activity is, in part, a result of an elevation in the phosphoinositol 3-kinase (PI3K) delta/Akt signalling pathway. Blockade of the PI3Kdelta pathway restores glucocortiocoid function in both in vitro and in vivo models, and in primary cells from disease. In addition, inhibition of the PI3Kdelta and PI3Kgamma isoforms is anti-inflammatory in both innate and adaptive immune responses. Consequently, selective inhibition of this pathway may provide a therapeutic strategy both as a novel anti-inflammatory and in combination therapy with glucocorticoids to restore their function. However, a number of other oxidant-related and -unrelated mechanisms, including altered kinase signalling and expression of the dominant negative GRbeta, may also play a role in the development of glucocorticoid insensitivity. Further elucidation of these mechanisms and pathways will enable novel therapeutic targeting for alternative anti-inflammatory drugs or combination therapies providing restoration for the anti-inflammatory action of glucocorticoids.

Linoleic acid supplementation results in increased arachidonic acid and eicosanoid production in CF airway cells and in cftr-/- transgenic mice

Cystic fibrosis (CF) patients display a fatty acid imbalance characterized by low linoleic acid levels and variable changes in arachidonic acid. This led to the recommendation that CF patients consume a high-fat diet containing >6% linoleic acid. We hypothesized that increased conversion of linoleic acid to arachidonic acid in CF leads to increased levels of arachidonate-derived proinflammatory metabolites and that this process is exacerbated by increasing linoleic acid levels in the diet. To test this hypothesis, we determined the effect of linoleic acid supplementation on downstream proinflammatory biomarkers in two CF models: 1) in vitro cell culture model using 16HBE14o(-) sense [wild-type (WT)] and antisense (CF) human airway epithelial cells; and 2) in an in vivo model using cftr(-/-) transgenic mice. Fatty acids were analyzed by gas chromatography-mass spectrometry (GC/MS), and IL-8 and eicosanoids were measured by ELISA. Neutrophils were quantified in bronchoalveolar lavage fluid from knockout mice following linoleic acid supplementation and exposure to aerosolized Pseudomonas LPS. Linoleic acid supplementation increased arachidonic acid levels in CF but not WT cells. IL-8, PGE(2), and PGF(2α) secretion were increased in CF compared with WT cells, with a further increase following linoleic acid supplementation. cftr(-/-) Mice supplemented with 100 mg of linoleic acid had increased arachidonic acid levels in lung tissue associated with increased neutrophil infiltration into the airway compared with control mice. These findings support the hypothesis that increasing linoleic acid levels in the setting of loss of cystic fibrosis transmembrane conductance regulator (CFTR) function leads to increased arachidonic acid levels and proinflammatory mediators.

Lipid mapping of colonic mucosa by cluster TOF-SIMS imaging and multivariate analysis in cftr knockout mice

The cftr knockout mouse model of cystic fibrosis (CF) shows intestinal obstruction; malabsorption and inflammation; and a fatty acid imbalance in intestinal mucosa. We performed a lipid mapping of colon sections from CF and control (WT) mice by cluster time of flight secondary-ion mass spectrometry (TOF-SIMS) imaging to localize lipid alterations. Data were processed either manually or by multivariate statistical methods. TOF-SIMS analysis showed a particular localization for cholesteryl sulfate at the epithelial border, C16:1 fatty acid in Lieberkühn glands, and C18:0 fatty acid in lamina propria and submucosa. Significant increases in vitamin E (vE) and C16:0 fatty acid in the epithelial border of CF colon were detected. Principal component analysis (PCA) and partitioning clustering allowed us to characterize different structural regions of colonic mucosa according to variations in C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C20:3, C20:4, and C22:6 fatty acids; phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol glycerolipids; cholesterol; vitamin E; and cholesteryl sulfate. PCA on spectra from Lieberkühn glands led to separation of CF and WT individuals. This study shows for the first time the spatial distribution of lipids in colonic mucosa and suggests TOF-SIMS plus multivariate analyses as a powerful tool to investigate disease-related tissue spatial lipid signatures.

Molecular circuits of resolution in airway inflammation

Inflammatory diseases of the lung are common, cause significant morbidity, and can be refractory to therapy. Airway responses to injury, noxious stimuli, or microbes lead to leukocyte recruitment for host defense. As leukocytes respond, they interact with lung resident cells and can elaborate specific mediators that are enzymatically generated from polyunsaturated fatty acids via transcellular biosynthesis. These bioactive, lipid-derived, small molecules serve as agonists at specific receptors and are rapidly inactivated in the local environment. This review will focus on the biosynthesis, receptors, cellular responses, and in vivo actions of lipoxins, resolvins, and protectins as exemplary molecular signaling circuits in the airway that are anti-inflammatory and proresolving.

CFTR depletion results in changes in fatty acid composition and promotes lipogenesis in intestinal Caco 2/15 cells

Background

Abnormal fatty acid composition (FA) in plasma and tissue lipids frequently occurs in homozygous and even in heterozygous carriers of cystic fibrosis transmembrane conductance regulator (CFTR) mutations. The mechanism(s) underlying these abnormalities remained, however, poorly understood despite the potentially CFTR contributing role.

Methodology/Principal Findings

The aim of the present study was to investigate the impact of CFTR depletion on FA uptake, composition and metabolism using the intestinal Caco-2/15 cell line. shRNA-mediated cftr gene silencing induced qualitative and quantitative modifications in FA composition in differentiated enterocytes as determined by gas-liquid chromatography. With the cftr gene disruption, there was a 1,5 fold increase in the total FA amount, largely attributable to monounsaturated and saturated FA compared to controls. The activity of delta-7 desaturase, estimated by the 16:1(n-7)/16:0, was significantly higher in knockdown cells and consistent with the striking elevation of the n-7 FA family. When incubated with [¹⁴C]-oleic acid, CFTR-depleted cells were capable of quick incorporation and export to the medium concomitantly with the high protein expression of L-FABP known to promote intracellular FA trafficking. Accordingly, lipoprotein vehicles (CM, VLDL, LDL and HDL), isolated from CFTR knockdown cells, exhibited higher levels of radiolabeled FA. Moreover, in the presence of [¹⁴C]-acetate, knockdown cells exhibited enhanced secretion of newly synthesized phospholipids, triglycerides, cholesteryl esters and free FA, thereby suggesting a stimulation of the lipogenic pathway. Conformably, gene expression of SREBP-1c, a key lipogenic transcription factor, was increased while protein expression of the phosphorylated and inactive form of acetylCoA carboxylase was reduced, confirming lipogenesis induction. Finally, CFTR-depleted cells exhibited lower gene expression of transcription factors (PPARα, LXRα, LXRβ and RXRα).

Conclusions/Significance

Collectively, our results indicate that CFTR depletion may disrupt FA homeostasis in intestinal cells through alterations in FA uptake and transport combined with stimulation of lipogenesis that occurs by an LXR/RXR-independent mechanism. These findings exclude a contributing role of CFTR in CF-associated fat malabsorption.

Supplementation with fatty acids influences the airway nitric oxide and inflammatory markers in patients with cystic fibrosis

OBJECTIVES

To obtain a balance in the fatty acid (FA) metabolism is important for the inflammatory response and of special importance in cystic fibrosis (CF), which is characterized by impaired FA metabolism, chronic inflammation, and infection in the airways. Nitric oxide (NO) has antimicrobial properties and low nasal (nNO) and exhaled NO (FENO), commonly reported in CF that may affect bacterial status. The present study investigates the effect of different FA blends on nNO and FENO and immunological markers in patients with CF.

PATIENTS AND METHODS

Forty-three patients with CF and "severe" mutations were consecutively enrolled in a randomized double-blind placebo-controlled study with 3 FA blends containing mainly n-3 or n-6 FA or saturated FA acting as placebo. FENO, nNO, serum phospholipid concentrations of FA, and biomarkers of inflammation were measured before and after 3 months of supplementation.

RESULTS

Thirty-five patients in clinically stable condition completed the study. The serum phospholipid FA pattern changed significantly in all 3 groups. An increase of the n-6 FA, arachidonic acid, was associated with a decrease of FENO and nNO. The inflammatory biomarkers, erythrocyte sedimentation rate, and interleukin-8 decreased after supplementation with n-3 FA and erythrocyte sedimentation rate increased after supplementation with n-6 FA.

CONCLUSIONS

This small pilot study indicated that the composition of dietary n-3 and n-6 FA influenced the inflammatory markers in CF. FENO and nNO were influenced by changes in the arachidonic acid concentration, supporting previous studies suggesting that both the lipid abnormality and the colonization with Pseudomonas influenced NO in the airways.

Pharmacological correction of a defect in PPAR-gamma signaling ameliorates disease severity in Cftr-deficient mice

Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (encoded by Cftr) that impair its role as an apical chloride channel that supports bicarbonate transport. Individuals with cystic fibrosis show retained, thickened mucus that plugs airways and obstructs luminal organs as well as numerous other abnormalities that include inflammation of affected organs, alterations in lipid metabolism and insulin resistance. Here we show that colonic epithelial cells and whole lung tissue from Cftr-deficient mice show a defect in peroxisome proliferator-activated receptor-gamma (PPAR-gamma, encoded by Pparg) function that contributes to a pathological program of gene expression. Lipidomic analysis of colonic epithelial cells suggests that this defect results in part from reduced amounts of the endogenous PPAR-gamma ligand 15-keto-prostaglandin E(2) (15-keto-PGE(2)). Treatment of Cftr-deficient mice with the synthetic PPAR-gamma ligand rosiglitazone partially normalizes the altered gene expression pattern associated with Cftr deficiency and reduces disease severity. Rosiglitazone has no effect on chloride secretion in the colon, but it increases expression of the genes encoding carbonic anhydrases 4 and 2 (Car4 and Car2), increases bicarbonate secretion and reduces mucus retention. These studies reveal a reversible defect in PPAR-gamma signaling in Cftr-deficient cells that can be pharmacologically corrected to ameliorate the severity of the cystic fibrosis phenotype in mice.