Hans-Joachim Krämer

ω-3 vs. ω-6 lipid emulsions exert differential influence on neutrophils in septic shock patients: impact on plasma fatty acids and lipid mediator generation

ObjectiveTo compare the effects of a conventional ω-6 lipid infusion and a fish oil based (ω-3) lipid infusion for parenteral nutrition on neutrophil function, lipid mediators, and plasma free fatty acids.Design and settingOpen-label, randomized, pilot study in a university hospital medical intensive care unit and experimental laboratory.Patients and participantsTen patients with septic shock and eight healthy controls.InterventionsPatients (five per group) requiring parenteral nutrition received intravenously either a ω-3 or a ω-6 lipid emulsion for a 10-day period.Measurements and resultsAt baseline levels of plasma free fatty acids were elevated several-fold, including high concentrations of the ω-6 lipid precursor arachidonic acid (AA). Neutrophils isolated from septic patients displayed markedly reduced responsiveness to ex vivo stimulation, including lipid mediator generation [leukotrienes (LT), PAF], respiratory burst, and phosphoinositide hydrolysis signaling. Under the ω-6 lipid infusion regimen abnormalities in plasma free fatty acids and impairment of neutrophil functions persisted or worsened. In contrast, a rapid switch in the plasma free fatty acid fraction to predominance of the ω-3 acids eicosapentaenoic acid and docosahexaenoic acid over AA occurred in response to ω-3 lipid infusion. LTB5, in addition to LTB4, appeared upon neutrophil stimulation originating from these patients, and neutrophil function was significantly improved in the ω-3 lipid group.Conclusionsω-3 vs. ω-6 lipid emulsions differentially influence the plasma free fatty acid profile with impact on neutrophil functions. Lipid-based parenteral nutrition in septic patients may thus exert profound influence on sequelae and status of immunocompetence and inflammation.

ω-3 Fatty acid–based lipid infusion in patients with chronic plaque psoriasis: Results of a double-blind, randomized, placebo-controlled, multicenter trial

Abstract Background: Profound changes in the metabolism of eicosanoids with increased concentrations of free arachidonic acid (AA) and its proinflammatory metabolites have been observed in psoriatic lesions. Free eicosapentaenoic acid (EPA) may compete with liberated AA and result in an antiinflammatory effect. Objective: Our purpose was to assess the efficacy and safety of intravenously administered fish-oil–derived lipid emulsion on chronic plaque-type psoriasis. Methods: A double-blind, randomized, parallel group study was performed in eight European centers. Eighty-three patients hospitalized for chronic plaque-type psoriasis with a severity score of at least 15 according to the Psoriasis Area and Severity Index (PASI) participated in a 14-day trial. They were randomly allocated to receive daily infusions with either a ω-3 fatty acid–based lipid emulsion (Omegavenous; 200 ml/day with 4.2 gm of both EPA and docosahexaenoic acid (DHA); 43 patients) or a conventional ω-6-lipid emulsion (Lipovenous; EPA+DHA Results: The total PASI score decreased by 11.2 ± 9.8 in the ω-3 group and by 7.5 ± 8.8 in the ω-6 group ( p = 0.048). In addition, the ω-3 group was superior to the ω-6 group with respect to change in severity of psoriasis per body area, change in overall erythema, overall scaling and overall infiltration, as well as change in overall assessment by the investigator and self-assessment by the patient. Response (defined as decrease in total PASI of at least 50% between admission and last value) was seen in 16 of 43 patients (37%) receiving the ω-3 emulsion and 9 of 40 patients (23%) receiving ω-6 fatty acid–based lipid emulsion. No serious side effects were observed. Within the first few days of ω-3 lipid administration, but not in the ω-6 supplemented patients, a manifold increase in plasma-free EPA concentration, neutrophil leukotriene B 5 and platelet thromboxane B 3 generation occurred. Conclusion: Intravenous ω-3-fatty acid administration is effective in the treatment of chronic plaque-type psoriasis. This effect may be related to changes in inflammatory eicosanoid generation. (J Am Acad Dermatol 1998;38:539-47.)

Adult respiratory distress syndrome: model systems using isolated perfused rabbit lungs.

Publisher Summary The adult respiratory distress syndrome (ARDS) is a persisting problem in modern intensive care medicine, still resulting in a high fatality rate. This chapter presents several studies that have demonstrated that, among the different initial events involved, sepsis and polytrauma represent the major risk factors for the development of this condition. Lung injury is triggered via mechanisms still not fully elucidated. Severe disturbances in pulmonary physiology occur, including a rise of pulmonary vascular resistance and an increase in the permeability of the capillary-endothelial and the alveoloepithelial barrier. These two key alterations result in the formation of protein-rich interstitial and subsequently intraalveolar edema, followed by deterioration of alveolar surfactant function. Mismatch in the adaptation of perfusion and ventilation because of “anarchic” vasoconstriction and vascular occlusion increase in shunt flow because of loss of alveolar spaces (edema, atelectasis), and hindrance of diffusion of gases results in severe deterioration of gas exchange with arterial hypoxemia. This early “exudative” phase of ARDS may then be followed by a protracted “proliferative” phase, with remodeling of lung structure and development of widespread lung fibrosis within a few weeks. Isolated, perfused lungs have long been used by investigators interested in the physiological, biochemical, and metabolic aspects of this complex organ. This technique has also been adopted to study pathogenetic events underlying the exudative phase of ARDS.

Fish oil fatty acids and human platelets: Dose-dependent decrease in dienoic and increase in trienoic thromboxane generation☆

Dietary enrichment of membrane phospholipids with n-3 (fish-oil-derived) fatty acids has attracted attention as a putative therapeutic regimen for suppression of inflammatory and coagulatory events. Use of n-3 fatty-acid-enriched lipid infusions for parenteral nutrition results in micromolar concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DCHA) in the plasma-free fatty acid fraction. We investigated the influence of free EPA and DCHA on platelet thromboxane (Tx) A2 and A3 formation by using a recently developed high performance liquid chromatography-ELISA technique for separate quantification of the stable hydrolysis products TxB2 and TxB3. Washed human thrombocytes were incubated with free arachidonic acid (AA; 1 microM), A23187 (0.1 microM) or thrombin (5 U/mL) for stimulation; all regimens provoked large quantities of TxA2 in the absence of TxA3. Simultaneous admixture of free EPA or free DCHA to the incubation medium (concentration range, 0.01-50 microM) largely suppressed platelet TxA2 generation in response to all stimuli used in a dose-dependent manner. The effective concentration with 50% influence of arachidonic acid was 4.2 microM, whereas the inhibitory concentration with 50% effect of EPA and DCHA were both in the same order of magnitude but differed with the nature of the agonist (0.2-7 microM). Platelet (co-)incubation with EPA, but not DCHA, provoked dose-dependent synthesis of n-3-lipid-derived thromboxane: kinetics of formation and absolute quantities of TxA3 approximated 20% of the respective TxA2 data upon stimulation with AA. Both EPA and DCHA dose-dependently suppressed U46619-provoked platelet aggregation. We conclude that EPA and DCHA are potent competitive inhibitors of TxA2 generation by intact platelets, with EPA acting as poor substrate and DCHA being no substrate for the cyclooxygenase/thromboxane synthase complex. Enrichment of the plasma-free fatty acid fraction with n-3 lipids may offer a therapeutic regimen to suppress the synthesis of the potent proaggregatory and vasoconstrictory agent TxA2.

A double-blind, randomized, placebo-controlled trial of n-3 versus n-6 fatty acid-based lipid infusion in atopic dermatitis.

BACKGROUND In the involved epidermis of patients with atopic dermatitis, changes in the metabolism of eicosanoids with increased quantities of the arachidonic acid (AA)-derived lipoxygenase products have been observed. Free eicosapentaenoic acid (EPA), a fish oil-derived alternative (n-3) fatty acid, may compete with AA, resulting in an anti-inflammatory effect. METHODS In a 10-day double-blind, randomized, placebo-controlled trial, 22 patients hospitalized for moderate-to-severe atopic dermatitis were randomly assigned to receive daily infusions of either a n-3 fatty acid-based lipid emulsion (fish oil, 10%; 200 mL/d) or a conventional n-6-lipid emulsion (soybean oil, 10%; 200 mL/d). Topical treatment was restricted to emollients. The severity of disease was evaluated daily with scoring of erythema, infiltration, and desquamation and by subjective patient scoring of clinical manifestations. In addition, plasma-free and total-bound fatty acids and the composition of membrane fatty acids in blood cells (thrombocytes, granulocytes, and erythrocytes), lipid mediators from isolated neutrophils and platelets, and lymphocyte-activation parameters were determined. RESULTS Twenty patients completed the trial. Marked improvement from baseline was seen in both groups. On days 6, 7, 8, and 10, disease severity score-defined as the sum of all scores-was more pronounced (p < .05) in the n-3 group compared with the n-6 group. Free arachidonic acid in plasma did not change substantially in both groups, whereas plasma-free EPA, total-bound EPA, and the membrane EPA/AA ratio markedly increased in response to n-3-lipid infusion. In parallel, EPA-derived lipid mediators appeared, whereas lymphocyte functions were unaffected. In the post-treatment period (2/4 weeks), relapse was observed in some patients after n-3 psoralene-ultraviolet A (PUVA) infusion, whereas there was a marked long-term improvement in the n-6 group. CONCLUSIONS IV n-3-fatty acid administration is effective in acutely improving the severity of atopic dermatitis, paralleled by changes in plasma and membrane fatty acid composition and lipid mediator synthesis. The long-term beneficial effects of IV n-6 fatty acids should be evaluated further.

Influence of intravenous n‐3 lipid supplementation on fatty acid profiles and lipid mediator generation in a patient with severe ulcerative colitis

Abstract. N‐3 fatty acids were supplied to a 36‐year‐old female patient suffering from ulcerative colitis and severe steroid side‐effects, in a sequence of parenteral and enteral administration. During a moderately active period of disease, 200 ml d‐1 fish oil‐derived lipid emulsion (eicosapentaenoic acid [EPA], 4–2 g; docosahexaenoic acid [DHA], 4.2 g) was infused for 9 days, in parallel with rapid tapering of the steroid dose. Disease activity declined rapidly, and the patient was subsequently provided with 16 fish oil capsules per day (EPA, 2.9 g; DHA, 1.9 g) for 2 months. At the end of this period of therapy, severe colitis recurred with intestinal and extraintestinal manifestations. The n‐3 lipid emulsion was then used for intravenous alimentation (29 days, maximum dose 300 ml per day); during this time, marked improvement of the inflammatory bowel disease was noted. During both periods of parenteral n‐3 lipid administration, total plasma EPA and DHA contents increased several‐fold, surpassing that of arachidonic acid; this plasma n‐3 fatty acid enrichment was only maintained to a minor extent during the intermediate period of dietary fish oil supplementation. The intravenously administered EPA‐containing triglycerides were rapidly hydrolyzed, as evidenced by the appearance of substantial quantities of EPA in the plasma free fatty acid fraction. Platelet and neutrophil total membrane content of EPA and DHA as well as n‐3 fatty acid/AA membrane ratios similarly increased during the periods of intravenous n‐3 lipid administration and declined during oral fish oil uptake. In contrast, erythrocyte membrane enrichment in EPA and DHA occurred only after the prolonged (2 month) period of dietary n‐3 lipid supplementation. Ex vivo stimulation of neutrophils with A23187 showed progressive increase in 5‐series leukotriene‐ and 5‐HEPE‐generation during both periods of n‐3 lipid infusion, in parallel with the rise of plasma EPA contents. Maximum 5‐series/4‐series leukotriene ratios surpassed 0.25. Similarly, ratios of thromboxane B3/B2 liberated from ex vivo stimulated platelets surpassed 0.4 during ongoing n‐3 lipid infusion. The profound changes in fatty acid profiles and lipid mediator generation may be related to the reduction in colitis activity observed during the periods of intravenous n‐3 lipid supplementation.

Malassezin, a Novel Agonist of the Aryl Hydrocarbon Receptor from the Yeast Malassezia furfur, Induces Apoptosis in Primary Human Melanocytes

Pityriasis versicolor is the most common skin mycosis in humans worldwide. Yeasts of the genus Malassezia, particularly M. furfur, a saprophyte occurring widely on human skin, are generally regarded as the causative agents. Pityriasis versicolor is often accompanied by a long‐lasting depigmentation that persists even after successful antimycotic therapy. M. furfur is able to convert tryptophan into a variety of indole alkaloids, some of them showing biological properties that correlate well with certain clinical features of pityriasis versicolor. This suggests a possible role for these compounds in the depigmentation process. We now report that human melanocytes undergo apoptosis when exposed to the crude mixture of tryptophan metabolites from M. furfur. The active compound was identified as malassezin, previously isolated by us from the same source and characterized as an agonist of the aryl hydrocarbon (Ah) receptor. The compound could, therefore, contribute to the marked depigmentation observed during the course of pityriasis versicolor.

ω-3 Lipid Infusion in a Heart Allotransplant Model Shift in Fatty Acid and Lipid Mediator Profiles and Prolongation of Transplant Survival

BACKGROUND omega-3 Fatty acids may have a major impact on immune responses involved in heart transplant rejection. We compared the effects of posttransplant intravenous supplementation with omega-3-rich versus omega-6-rich lipid emulsions on graft survival, plasma fatty acid profiles, and levels of arachidonic acid versus eicosapentaenoic acid-derived lipid mediators. METHODS AND RESULTS Inbred PVG and Wistar-Kyoto rats were used as donors and recipients, respectively, in a model of heterotopic heart transplantation. Animals received 9 g/kg body wt per day of either fish oil-derived (n = 8) or soybean oil-derived fat (n = 7) in the form of a continuously infused lipid emulsion; controls were sham-infused with saline (n = 8). Graft rejection was assessed by loss of activity of the transplant. The fish oil-derived preparation but not that originating from soybean oil caused an increase in total and free plasma fatty acids. Substantial quantities of eicosapentaenoic acid and docosahexaenoic acid appeared in the free fatty acid fraction, surpassing those of arachidonic acid. Ex vivo stimulation of neutrophils with the Ca2+ ionophore A23187 demonstrated an increase in 5-series leukotriene (LT) generation in animals undergoing omega-3 lipid infusion (LTB5, omega-oxidation products of LTB5, LTA5 secretion), with 5-series/4-series LT ratios ranging between 0.08 and 0.36. Ratios of TX B3/B2 liberated from ex vivo stimulated platelets even approached 1:1 in omega-3 supplemented rats. Graft survival was 7.6 +/- 0.3 (mean +/- SEM) days in saline-infused, 10.4 +/- 0.7 in omega-6 lipid-infused, and 12.9 +/- 0.4 in omega-3 lipid-infused animals. CONCLUSIONS Posttransplant intravenous alimentation with fish oil-derived lipid emulsions prolongs heart transplant survival in excess to omega-6 lipids. Profound changes in fatty acid profiles and lipid mediator generation may underlie this finding.

Pityriarubins, Novel Highly Selective Inhibitors of Respiratory Burst from Cultures of the Yeast Malassezia furfur: Comparison with the Bisindolylmaleimide Arcyriarubin A

Pityriasis versicolor is the most common skin mycosis in humans worldwide. Yeasts of the genus Malassezia, particularly M. furfur, a saprophyte occurring widely on human skin, are generally regarded as the causative agents. M. furfur is able to convert tryptophan into a variety of indole alkaloids, some of them showing biological properties that correlate well with certain clinical features of pityriasis versicolor. This suggests a possible role for these compounds in the pathophysiology of the disease. We here report that the novel pityriarubins A, B and C, isolated from cultures of the yeast, inhibit respiratory burst in human neutrophils, activated by various agents, in a highly selective, unexpected manner. The release of 5‐lipoxygenase products after challenge of neutrophils with the calcium ionophore A23187 is also inhibited in a dose‐dependent manner. These activities reflect the close structural relationship of pityriarubins to bisindolylmaleimides, which have recently gained great interest as protein kinase inhibitors.

Pityrialactone- a new fluorochrome from the tryptophan metabolism of M. alassezia furfur

As the main nitrogen source in Malassezia (M.) furfur, tryptophan induces the formation of fluorochromes and pigments, which makes the yeast less sensitive towards UV light. For the investigation of the fluorochromes, M. furfur (CBS1878) was incubated at 32 °C for 14 days on a pigment-inducing medium, and the agar extract was purified by column chromatography, preparative TLC and HPLC. The structures of the pure metabolites were determined by mass spectrometry and NMR spectroscopy. A pale yellow compound eluting from the column with 22% acetonitrile was found to exhibit a strong green-yellow fluorescence. The fluorochrome is a new bisindolyl compound (C20H12N2O3, MW 328.33) named pityrialactone because of its furan-2,3-dione structure. The UV protective properties (λmax 352, 292, 276, 224 nm) of this metabolite were confirmed in a yeast model. As shown by the fluorescence spectrum, pityrialactone appears to be responsible for the green-yellow fluorescence of pityriasis versicolor lesions under Wood light. Pityrialactone is accompanied by the isomeric bisindolylmaleic anhydride (pityriaanhydride), which has not yet been described as a natural product but is a known intermediate in the total synthesis of bisindolylmaleimides.