Circulating polymorphonuclear leukocytes from patients with gram-negative bacteremia are not primed for enhanced production of leukotriene B4 or 5-hydroxyeicosatetraenoic acid

Fish oil-supplemented parenteral nutrition in severe acute pancreatitis patients and effects on immune function and infectious risk: a randomized controlled trial

The human leukocyte antigen (HLA)-DR expression on monocytes and plasma Interleukin (IL)-10 levels are key indicators of immune response during the acute phase of severe acute pancreatitis (SAP). We designed a pilot study to investigate whether omega-3 fatty acids (FAs) supplemented parenteral nutrition (PN) could improve immune response in SAP patients. Fifty-six SAP patients were enrolled (28 patients in each group) and received isocaloric and isonitrogenous parenteral nutrition, providing 1.0 g/kg/day standard soybean-oil based fat (omega-6 FAs group) or 0.8 g/kg/day soybean oil +0.2 g/kg/day omega-3 FAs based fat (omega-3 FAs group). IL-10, HLA-DR and the ratio of CD4(+) to CD8(+) were determined before PN treatment and on day 6 after starting PN. The infection and surgery rates were recorded until hospital discharge. A significant IL-10 increase was associated with the administration of omega-3 FAs (p = 0.04, vs omega-6 FAs group). Monocyte HLA-DR expression improved in both groups after 5 days of PN treatment. This increase was significantly higher in the omega-3 FAs group compared to omega-6 FAs (p = 0.01). There was no significant difference of CD4(+)/CD8(+), infection and surgery rates between the two groups. In conclusion, omega-3 FAs supplemented PN can elevate the IL-10 level and HLA-DR expression in SAP patients. A larger trial is required to see whether omega-3 FAs supplemented PN treatment in SAP patients would result in better clinical outcomes than omega-6 FAs.

Dysregulation of the immune response in severe sepsis

Sepsis is systemic expression of a generalized activation of the host's innate immunity as a result of varied types of insults. This expression involves a cellular inflammatory response that has both proinflammatory and antiinflammatory components, the primary trigger for which is an intracellular oxidative stress, induced by receptor-mediated transmembrane signal transduction or direct noxious injury. Sepsis reflects the interaction between pro- and anti-inflammatory intracellular mechanisms, the uncontrolled activation of which leads to cell exhaustion, organ dysfunction, and death. Successful clinical trials of novel treatments for the management of severe sepsis share a common ability to down-regulate this overall response, restoring normal proinflammatory responsiveness and mitochondrial energetic function.

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

OBJECTIVE

To compare the effects of a conventional omega-6 lipid infusion and a fish oil based (omega-3) lipid infusion for parenteral nutrition on neutrophil function, lipid mediators, and plasma free fatty acids.

DESIGN AND SETTING

Open-label, randomized, pilot study in a university hospital medical intensive care unit and experimental laboratory.

PATIENTS AND PARTICIPANTS

Ten patients with septic shock and eight healthy controls.

INTERVENTIONS

Patients (five per group) requiring parenteral nutrition received intravenously either a omega-3 or a omega-6 lipid emulsion for a 10-day period.

MEASUREMENTS AND RESULTS

At baseline levels of plasma free fatty acids were elevated several-fold, including high concentrations of the omega-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 omega-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 omega-3 acids eicosapentaenoic acid and docosahexaenoic acid over AA occurred in response to omega-3 lipid infusion. LTB(5), in addition to LTB(4), appeared upon neutrophil stimulation originating from these patients, and neutrophil function was significantly improved in the omega-3 lipid group.

CONCLUSIONS

omega-3 vs. omega-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.