Generation of leukotrienes from human polymorphonuclear granulocytes of severely burned patients

Diverse characters of Brennan's paw incision model regarding certain parameters in the rat

Background

Brennan’s rodent paw incision model has been extensively used for understanding mechanisms underlying postoperative pain in humans. However, alterations of physiological parameters like blood pressure and heart rate, or even feeding and drinking patterns after the incision have not been documented as yet. Moreover, though eicosanoids like prostaglandins and leukotrienes contribute to inflammation, tissue levels of these inflammatory mediators have never been studied. This work further investigates the antinociceptive effect of protein C after intra-wound administration.

Methods

Separate groups of Sprague–Dawley rats were used for quantitation of cyclooxygenase (COX) activity and leukotriene B4 level by enzyme-linked immunosorbent assay, as well as estimation of cardiovascular parameters and feeding and drinking behavior after paw incision. In the next part, rats were subjected to incision and 10 μg of protein C was locally administered by a micropipette. Both evoked and non-evoked pain parameters were then estimated.

Results

COX, particularly COX-2 activity and leukotriene B4 levels increased after incision. Hemodynamic parameters were normal. Feeding and drinking were affected on days 1 and 3, and on day 1, respectively. Protein C attenuated non-evoked pain behavior alone up to day 2.

Conclusions

Based upon current observations, Brennan’s rodent paw incision model appears to exhibit a prolonged period of nociception similar to that after surgery, with minimal interference of physiological parameters. Protein C, which is likely converted to activated protein C in the wound, attenuated the guarding score, which probably represents pain at rest after surgery in humans.

Decreased leukotriene release from neutrophils after severe trauma: role of immature cells

Polymorphonuclear granulocytes (PMN) play a key role in host defense against microbial infections. After severe trauma PMN show cellular dysfunctions including chemotactic migration, phagocytosis, and bacterial killing. In these settings the contribution of the cellular maturation stage compared to functional activities has not been investigated. Polymorphonuclear granulocytes are potent producers of lipid mediators via the 5-lipoxygenase (5-LO) pathway (leukotrienes, LTs) which exert important proinflammatory and immunoregulatory activities. We analyzed leukotriene generation from PMN-fractions (N = 23) of 15 polytrauma patients in comparison to 17 healthy donor cell fractions and correlated this lipid mediator release to the hematopoietic maturation stage of respective PMN. Polymorphonuclear granulocytes were isolated from EDTA-anticoagulated peripheral blood employing a one step procedure based on a discontinuous double Ficoll-gradient. Cells (5 x 10(6)/500 microl phosphate-buffered saline) were stimulated for 20 min at 37 degrees C with 1 microM Ca-ionophor A23187 in the presence of 1 mM Ca++ and 0.5 mM Mg++. Leukotrienes were analyzed by reversed-phase HPLC. Expression of 5-lipoxygenase (5-LO) was additionally determined by Western blot. Maturation stage of PMN was quantitated by Pappenheim-staining of cell smears. After polytrauma the generation of leukotrienes from PMN was individually diminished. Synthesis of enzymatically formed metabolites (LTB4, OH-LTB4 and COOH-LTB4) was concomitantly reduced. The decresaed leukotriene synthesis strongly correlated (r2 = 0.907, P < 0.0001) to the occurrence of immature PMN (mostly band cells). The expression of 5-lipoxygenase in PMN fractions consisting mainly of band cells was decreased. Our results provide evidence that posttraumatic granulocyte dysfunction is partly due to immature functional cell capacities.

Total parenteral nutrition with glutamine dipeptide after major abdominal surgery: a randomized, double-blind, controlled study

OBJECTIVE

To assess the efficacy of glutamine (Gln) dipeptide-enriched total parenteral nutrition (TPN) on selected metabolic, immunologic, and clinical variables in surgical patients.

SUMMARY BACKGROUND DATA

Depletion of Gln stores might lead to severe clinical complications. Recent studies indicate that the parenteral provision of Gln or Gln-containing dipeptides improves nitrogen balance, maintains the intracellular Gln pool, preserves intestinal permeability and absorption, and shortens hospital stay.

METHODS

Twenty-eight patients (age range, 42-86 years, mean 68 years) undergoing elective abdominal surgery were allocated, after randomization, to two groups to receive isonitrogenous (0.24 g nitrogen kg(-1) day(-1)) and isoenergetic (29 kcal/122 kJ kg(-1) day(-1)) TPN over 5 days. Controls received 1.5 g of amino acids kg(-1) day(-1), and the test group received 1.2 g of amino acids and 0.3 g of L-alanyl-L-glutamine (Ala-Gln) kg(-1) day(-1). Venous heparinized blood samples were obtained before surgery and on days 1, 3, and 6 after surgery for routine clinical chemistry and for the measurement of plasma free amino acids. Lymphocytes were counted and the generation of cysteinyl-leukotrienes from polymorphonuclear neutrophil granulocytes was analyzed before surgery and on days 1 and 6 after surgery. Nitrogen balances were calculated postoperatively on days 2, 3, 4, and 5.

RESULTS

No side effects or complaints were noted. Patients receiving Gln dipeptide revealed improved nitrogen balances (cumulative balance over 5 days: -7.9 +/- 3.6 vs. -23.0 +/- 2.6 g nitrogen), improved lymphocyte recovery on day 6 (2.41 +/- 0.27 vs. 1.52 +/- 0.17 lymphocytes/nL) and improved generation of cysteinyl-leukotrienes from polymorphonuclear neutrophil granulocytes (25.7 +/- 4.89 vs. 5.03 +/- 3.11 ng/mL). Postoperative hospital stay was 6.2 days shorter in the dipeptide-supplemented group.

CONCLUSION

We confirm the beneficial effects of Gln dipeptide-supplemented TPN on nitrogen economy, maintenance of plasma Gln concentration, lymphocyte recovery, cysteinyl-leukotriene generation, and shortened hospital stay in surgical patients.

Glutamine dipeptides in clinical nutrition

Glutamine is a conditional indispensable amino acid during stress. However, limited solubility and instability of glutamine prevent its addition to presently available nutritional preparations. To overcome these drawbacks, we propose the dipeptide concept by which stable and highly soluble synthetic glutamine containing dipeptides are used. The synthetic dipeptides fulfill all chemical/physical properties to be considered as parenteral substrates. Numerous experimental studies show rapid clearance of parenteral supplied glutamine containing dipeptides without accumulation in tissues; the loss via the urine being inconsequential. Differences related to the dipeptide structure are not observed. There is overwhelming evidence existent that a nutritional support with supplemental glutamine dipeptide positively influences nitrogen excretion, immune status, gut integrity, morbidity, rehabilitation and outcome. Consequently, omission of glutamine from conventional TPN and its subsequent administration should be considered as a replacement of a deficiency rather than a supplementation. It might thus be conceivable that the beneficial effects observed with glutamine nutrition are simply a correction of disadvantages produced by an inadequacy of conventional amino acid solutions. The availability of stable glutamine containing preparations will certainly facilitate an adequate amino acid nutrition in routine clinical setting during episodes of stress and malnutrition.

Influence of a total parenteral nutrition enriched with omega-3 fatty acids on leukotriene synthesis of peripheral leukocytes and systemic cytokine levels in patients with major surgery

OBJECTIVE

Nutritive immunomodulation of patients after major surgery.

DESIGN

Prospective, randomized controlled double-blind study.

PATIENTS

Forty patients undergoing major intestinal surgery. Patients were divided into two groups: one received a total parenteral nutrition enriched with omega-3 fatty acids for 5 days postoperatively, the other an isocaloric, control nutrition.

MATERIALS AND METHODS

We analyzed the leukocyte ability to release leukotrienes from whole blood leukocytes stimulated with the calcium ionophore A23187 (5 micromol/L) by reverse phase high-performance liquid chromatography and circulating cytokines by enzyme-linked immunosorbent assay.

RESULTS

Leukocytes from patients of the omega-3 fatty acids group generated significantly higher amounts of less biologically active leukotriene B5 as compared to the control group (p < or = 0.001). This was accompanied by a significant decrease in the generation of proinflammatory leukotriene B4 (p < or = 0.006) in the study group. In contrast to interleukin-1beta, interleukin-6, and interleukin-10 systemic levels of tumor necrosis factor-alpha (p < or = 0.05) were postoperatively decreased in the study group.

CONCLUSION

Our data provide evidence that a total parenteral nutrition enriched with omega-3 fatty acids modulates the lipid mediator pattern and systemic tumor necrosis factor-alpha levels.

Pathophysiology of the burn wound and pharmacological treatment. The Rudi Hermans Lecture, 1995

The body's reaction to thermal injury is much more than an initial, local inflammatory response. The burn wound is a continuous, severe threat against the rest of the body due to invasion of infectious agents, antigen challenge and repeated additional trauma caused by wound cleaning and excision. The inflammatory mediators which control blood supply and microvascular permeability in the wound have been extensively studied and are largely understood. Attempts to suppress the inflammatory reaction by different drugs, have, however, been less successful. Extensive thermal injury and sepsis also results in immunosuppression. The defects causing immunosuppression are still very much under consideration. An understanding of these defects is essential for the development of therapies. The increasing interest in the control of the inflammatory reactions by cytokines may, in the near future, be of great importance.

[Is albumin administration useful in critical care for burnt patients?]

The most typical reaction of the organism after a major burn consists in transcapillary shift from plasma into interstitial space. Capillary hyperpermeability, but also changes in colloid osmotic gradient and decrease in interstitial hydrostatic pressure, explain the fluid shift to burned and, at minor importance, non burned areas during the first post-burn day. The extent of capillary hyperpermeability results in inefficiency of colloid infusions in reducing fluid shift to burned areas. Some groups advocate colloid supply from the eighth post-burn hour, on when hyperpermeability decreases, in non burned sites. However, for most groups, restoration of a functional interstitial space has priority during the 24 first post-burn hours, justifying crystalloid supply without colloids. Furthermore, colloid infusion could be responsible for delayed pulmonary oedema, in the first days following initial fluid replacement. After 24 post-burn hours, in patients experiencing severe albumin depletion, infusion of human albumin is justified, in order to favour oedema resorption.

[Role of albumins in burnt patients: its efficacy during intensive care. Addendum to the expert guidelines of the Consensus Conference, Paris December 15th 1995]

In the burned patient, the critical threshold over which a correction of hypoalbuminemia is required has not yet been clearly defined. The level of 30 g.L-1 of albumin is usually admitted. According to the extent of the burn, albumin is not indicated in patients with a burn size below 15% of the total body surface. It is essential, from the very beginning of management in patients with a burn size over 50%. Its administration can be postponed to the 8th, 12th or even 24th hour in case of a burn size between 15 and 50%.

Recombinant human-type SOD attenuates circulatory disorders after reperfusion of splanchnic organs in rats

Oxygen free radicals (OFRs) have been reported to play pivotal roles in the pathogenesis of cell damage induced by ischemia and reperfusion. The efficacy of recombinant human superoxide dismutase (rh-SOD) in the treatment of circulatory disorders after reperfusion of the splanchnic area was investigated in rats. All rats died within 3 hours after release of 60-min superior mesenteric artery occlusion (SMAO) when no treatment was given. Animals which received rh-SOD, 2 mg.100 g(-1)BW, at reperfusion followed by a continuous infusion of rh-SOD 0.67 mg.100 g(-1)BW.hr(-1), exhibited prolonged survival times compared with no treatment rats (231 +/- 35 min and 149 +/- 43 min, respectively). Mean blood pressure in rats treated with rh-SOD was higher than in controls after reperfusion, and was concomitant with improvement in splanchnic perfusion. The results suggest excessive activity of OFRs in reperfused organs and a possible scavenging effect of rh-SOD as a means of eliminating them.

The role of mediators in the response to thermal injury

Inflammatory mediators play a major role in both the local burn wound and the systemic response to burn injury. Oxidant and arachidonic acid metabolites are involved in the initial burn edema process. The mediators as well as the cytokines released from activated macrophages also result in an early generalized inflammatory response. The later postburn hyper-metabolism is initiated and perpetuated by these same mediators, especially the cytokines, tumor necrosis factor, interleukin-1, and interleukin-2. Circulating endotoxin from the wound or the gut also appears to be involved. The postburn septic response is now recognized to be the result of inflammation; infection is not necessary. Mediator induced priming of the inflammatory cells by the burn itself results in an exaggerated response to infection in the postburn period. Defining the specific mechanism of injury and mediators involved can result in a major improvement in burn care, especially since many mediator inhibitors are already available for clinical use. It is essential that the clinician understand this pharmacologic manipulation in order to be able to optimally utilize these future advances.

Heat shock induces alterations of the lipoxygenase pathway in human polymorphonuclear granulocytes

We have investigated the effect of the heat shock response on the leukotriene generation, chemotaxis, and generation of oxygen radicals of human polymorphonuclear granulocytes (PMNs) by preincubating the PMNs at 42 degrees C. Subsequently, the different test systems were performed at 37 degrees C. As we confirmed by the release of lactate dehydrogenase and beta-glucuronidase the elevated temperatures did not result in cytotoxic or degranulating processes. After heat shock treatment the generation of leukotrienes induced by the Ca(++)-ionophore A23187, fMLP or opsonized zymosan was inhibited in a time and temperature dependent manner (preincubation phase) as was measured by HPLC-analysis. In contrast, the conversion of 14C-arachidonic acid revealed the generation of LTB4, 5-HPETE and 5-HETE solely as a result of the preincubation at 42 degrees C without any further stimulation. In addition, the chemiluminescence response induced by opsonized zymosan and the chemotaxis against C5a and LTB4 was clearly inhibited after heat shock treatment. With regard to enzyme activities of the heat treated PMNs the protein kinase C activities were enhanced whereas the LTD4-dipeptidase and the LTB4-omega-hydroxylase were not affected.