Effect of nonviable tissue and abscesses on complement depletion and the development of bacteremia

Perioperative Enteral Immunonutrition Modulates Systemic and Mucosal Immunity and the Inflammatory Response in Patients With Periampullary Cancer Scheduled for Pancreaticoduodenectomy: A Randomized Clinical Trial

OBJECTIVES

Nutritional deficiencies and immune dysfunction in cancer patients may contribute to postoperative septic morbidity. This trial compared the effects of perioperative enteral immunonutrition (EIN) versus standard enteral nutrition (SEN) on systemic and mucosal immunity in patients undergoing pancreaticoduodenectomy for periampullary cancer.

METHODS

Thirty-seven patients were randomized (EIN, n = 17; SEN, n = 20) to receive feed for 14 days preoperatively and 7 days postoperatively. Mediators of systemic immunity (interleukin 1α, tumor necrosis factor α, lymphocytes subsets, and complement components) and of mucosal immunity in duodenal biopsies, nutritional markers and parameters were evaluated.

RESULTS

The groups were comparable for demographics, the concentrations of mediators of systemic and mucosal immunity at time of recruitment, and for the duration and amount of feed received. Preoperative EIN rather than SEN was associated with significant reductions in plasma tumor necrosis factor α and total hemolytic complement. Enteral immunonutrition-fed patients had significantly higher total lymphocyte count on the third postoperative day and significantly greater rise in CD4/CD8 ratio from day 3 to day 7 postoperatively compared with SEN-fed patients.

CONCLUSIONS

The perioperative administration of EIN rather than SEN is associated with a favorable modulation of the inflammatory response and enhancement of systemic immunity in patients undergoing pancreaticoduodenectomy for periampullary cancer.

Study of complement activation, C3 and interleukin-6 levels in burn patients and their role as prognostic markers

PURPOSE

The management of burn patients is always challenging for the clinician due to high risk of bacterial sepsis, multi-organ failure and death. Our objective was to study complement activation, C3 and interleukin-6 (IL-6) levels in burn patients and evaluate their role as prognostic markers.

MATERIALS AND METHODS

A total of 63 burn patients and 60 healthy controls were included in this study. Blood was collected from patients within 24 h and at 7 th day of injury. Complement activation was determined by crossed electrophoresis and counter-current immunoelectrophoresis. C3 levels were measured using a single radial immunodiffusion. IL-6 was detected by ELISA.

RESULTS

All patients showed initial complement activation. Mean C3 levels showed an inverse correlation with the severity of burn. Patients with ≥20% burns had lower C3 than the controls (P < 0.001) and those with <20% burns (P < 0.001). Patients with ≥40% burns had activated complement and low C3 in 2 nd week; they subsequently developed infection. Complement was inactive and C3 levels recovered in patients with <40% burns. The non-survivors showed significantly lower C3 than the survivors (P < 0.05) in 2 nd samples. Patients who developed infection had C3 significantly lower than those who remained free of infection (P < 0.05). All patients showed initial elevation in IL-6 levels. Patients with ≥60% burns had significantly higher IL-6 than controls (P < 0.001) and those with <60% burns (P < 0.001). Non-survivors had higher IL-6 than survivors in both samples (P < 0.001). Patients who developed infection showed significantly higher IL-6 in 2 nd samples than those without infection (P < 0.001).

CONCLUSIONS

Complement activation, C3 and IL-6 levels correlated well with the severity of injury and development of infection in burn patients. These parameters can be used to predict the onset of infection, septicaemia and mortality in burn patients.

Change of complement system predicts the outcome of patients with severe thermal injury

To establish the clinical relevance of the changes in the complement system in patients with thermal injury, we studied 20 patients who had third-degree burns on more than 60% of total body surface area. Their levels of the C3, C4, soluble C5b-9, and functional hemolytic activities of total (CH50) and alternative (AH50) complement pathways were sequentially measured for 2 weeks after thermal injury. All patients showed low C3 levels initially but increased C3 levels in the following days. The increasing trend of C3 levels was prominent in survivors but transient and diminished in nonsurvivors. The change of levels of C3, CH50, and AH50 was closely associated with one another, and their chronological trends related to the survival of patients (P =.0060,.0064 and.0066, respectively). The recovery of C3, AH50, and CH50 to normal or supranormal level during the early treatment period relates to the survival of patients with thermal injury. The failure of recovery of the complement system indicates a poor prognosis for patients and the monitoring of complement system might be beneficial in the care of patients with thermal injury.

Systemic and lung physiological changes in rats after intravascular activation of complement

Systemic complement activation has been noted in a variety of shock states, and there is growing evidence that, in addition to being proinflammatory effectors, products of complement activation contribute directly to generalized manifestations of shock, such as hypotension and acidosis. To study the effects of complement activation, we examined responses in rats to systemic activation of complement with cobra venom factor (CVF), including blood pressure, metabolic acidosis, changes in vascular permeability, and lung function. High doses of CVF produced circulatory collapse (mean arterial pressure = 110 ± 16 and 35 ± 9 mmHg in control and with CVF, respectively, P < 0.05), metabolic acidosis (HCO[Formula: see text] concentration = 27.8 ± 1.7 and 9.6 ± 3.4 meq/l in control and with CVF, respectively, P < 0.05), extravasation of albumin into the lung and gut, and modest arterial hypoxemia (Po 2 = 486 ± 51 and 201 ± 36 Torr in control and during 100% O2 breathing, respectively, P < 0.05). Prior depletion of complement protected against these abnormalities. Other interventions, including neutrophil depletion and cyclooxygenase inhibition, prevented lung injury but had much less effect on systemic hemodynamics or gut permeability, suggesting that complement activation products induce injury by neutrophil- and cyclooxygenase-dependent pathways in the lung but not in the gut. These studies underscore the significant systemic abnormalities developing after systemic activation of complement.

Protective effects of anti-C5a peptide antibodies in experimental sepsis

We evaluated antibodies to different peptide regions of rat C5a in the sepsis model of cecal ligation and puncture (CLP) for their protective effects in rats. Rabbit polyclonal antibodies were developed to the following peptide regions of rat C5a: amino-terminal region (A), residues 1-16; middle region (M), residues 17-36; and the carboxyl-terminal region (C), residues 58-77. With rat neutrophils, the chemotactic activity of rat C5a was significantly inhibited by antibodies with the following rank order: anti-C > anti-M >> anti-A. In vivo, antibodies to the M and C (but not A) regions of C5a were protective in experimental sepsis, as determined by survival over a 10-day period, in a dose-dependent manner. The relative protective efficacies of anti-C5a preparations (in descending order of efficacy) were anti-C > anti-M >> anti-A. In CLP rats, a delay in infusion of antibodies, which were injected at 6 or 12 h after CLP, still resulted in significant improvement in survival rates. These in vivo and in vitro data suggest that there are optimal targets on C5a for blockade during sepsis and that delayed infusion of anti-C5a antibody until after onset of clinical evidence of sepsis still provides protective effects.

Detrimental effects of complement activation in hemorrhagic shock

The complement system has been implicated in early inflammatory events and a variety of shock states. In rats, we measured complement activation after hemorrhage and examined the hemodynamic and metabolic effects of complement depletion before injury and worsening of complement activation after hemorrhage and resuscitation [with a carboxypeptidase N inhibitor (CPNI), which blocks the clearance of C5a]. Rats were bled to a mean arterial pressure of 30 mmHg for 50 min and were then resuscitated for 2 h. Shock resulted in significant evidence of complement consumption, with serum hemolytic activity being reduced by 33% (P < 0.05). Complement depletion before injury did not affect hemorrhage volume (complement depleted = 28 +/- 1 ml/kg, complement intact = 29 +/- 1 ml/kg, P = 0.74) but improved postresuscitation mean arterial pressure by 37 mmHg (P < 0.05) and serum bicarbonate levels (complement depleted = 22 +/- 3 meq/ml, complement intact = 13 +/- 8 meq/ml, P < 0.05). Pretreatment with CPNI was lethal in 80% of treated animals vs. the untreated hemorrhaged group in which no deaths occurred (P < 0.05). In this model of hemorrhagic shock, complement activation appeared to contribute to progressive hypotension and metabolic acidosis seen after resuscitation. The lethality of CPNI during acute blood loss suggests that the anaphylatoxins are important in the pathophysiological events involved in hemorrhagic shock.

Management of infections in the trauma patient

Infections play a leading role in the morbidity and mortality of injured patients. This article discusses risk factors that can increase the chances of a nosocomial infection. It also discusses common types of infection, causative organisms, and the approach to the febrile trauma patient.

A biologic basis for altered host defenses in surgically infected abscesses

OBJECTIVE

This study determines whether there are any differences in several immunologic parameters in circulating peripheral blood leukocytes, serum, and plasma compared with pus leukocytes, and supernatant of various types of abscess.

SUMMARY BACKGROUND DATA

Although there have been reports of high lysozyme levels and low complement levels within pus, there has been no systemic comparison of concentrations of these substances and others within pus compared with those within peripheral blood.

METHODS

Peripheral blood and abscess pus were collected from 31 patients with abscesses and percent and mean channel of monocytes expressing complement receptor and major histocompatibility antigen HLA-DR, the percent and mean channel of polymorphonuclear leukocytes (PMN) expressing complement receptor, lysozyme level, and levels of total hemolytic complement, iC3b, C5b-9, and immunoglobulins were measured within both pus and peripheral blood.

RESULTS

Percent of monocytes expressing HLA-DR and percent of monocytes and PMN expressing complement receptor, total hemolytic complement, and IgM were reduced within pus compared with peripheral blood, whereas the mean channel of monocytes expressing HLA-DR and the mean channel of PMNs expressing CR3, C5b-9, and lysozyme were increased in pus.

CONCLUSIONS

There are marked differences in immunologic parameters measured within pus of abscesses versus that seen in peripheral blood.

Surgical trauma, Candida infection, and serum proteolytic activity

Both surgical trauma and infection can disturb the proteinase to proteinase inhibitor balance in the circulation. We sought to assess the effect of Candida albicans infection (INFX) on postoperative mortality, to correlate mortality with total serum proteolytic activity (PA), and to assess the impact of exogenous proteinase inhibitors (PI) on this mortality. Mice underwent midline laparotomy (LAP) and immediate postoperative intravenous C. albicans infection. LAP + INFX shortened mean survival compared to INFX or LAP alone. Quantitative renal cultures confirmed that death in the LAP + INFX and INFX groups was due to Candida sepsis. PA was measured using an 125I-labeled protein assay, yielding micrograms of acid-soluble peptides/100 microliters of serum. In control, sham-operated, and LAP groups, PA averaged less than 9.0, and mortality was 0. In INFX and LAP + INFX groups, PA averaged greater than 14.5 and mortality was high. To determine if high PA was related to high mortality, LAP + INFX mice were treated immediately preoperatively with a single dose of PI (1 mg alpha 1-proteinase inhibitor, 1 mg antithrombin, and 1000 KIU aprotinin). Mean survival increased with PI treatment. In conclusion, the addition of Candida infection to surgical trauma hastened mean time to death. More rapid death correlated with elevated PA and may reflect systemic imbalance in the proteinase to proteinase inhibitor ratio in the circulation. PI improved survival, suggesting that proteinase inhibition may prove useful in the future in the treatment of fungal sepsis in surgical patients.

Effects of anaesthesia and surgery on the immune response

Alterations have been found to occur in every component of immune response during anaesthesia and surgery. These alterations represent the body's general physiological responses and are mainly dependent on the extent of surgery, as well as other factors such as the patient's age and health status, medication and blood transfusion. Anaesthetic and operative complications have profound effects on these responses. Basically, the immune response to anaesthesia and surgery is a beneficial reaction, needed in local host defences and wound healing and in preventing the body from making autoantibodies against its own tissues. The responses may, however, contribute to the development of postoperative infections and spread of malignant disease. During uncomplicated conventional surgery, the immune response usually passes clinically unnoticed without any harmful effects. Absent responses and excessively high responses, on the other hand, harm the patient. Our understanding of immunological phenomena and our possibilities of controlling mediator activation are now lagging behind the technical advances made in operative treatment. If we want to decrease operative morbidity and mortality to below their present levels, more attention should be directed to immune responses to major surgery, injuries and operative complications with massive mediator release which place the surgical patient at risk. Experimental evidence suggests that results of treatment in injured and operated patients can in the future be improved by controlling immune responses and their mediator systems. Our current level of knowledge of immune responses is already helping us to avoid many immune-mediated complications. However, routine interference with these responses is not indicated.

The cell in shock: the origin of multiple organ failure

The immediate organ damage seen after multiple trauma and in shock is a typical example of non-bacterial inflammation triggered by activation of various mediators of both the humoral and cellular systems. Anaphylatoxins and the low-flow syndrome during the shock phase account for increased PMN* margination, which in turn causes pulmonary leukostasis and may provoke massive mediator release by PMN (oxygen radicals, proteinases, eicosanoids, PAF etc). This probably leads to severe endothelial cell damage, especially in the lung. Adherence of PMN to the endothelium appears to create the micro-environment where high concentrations of proteolytic enzymes and reactive oxygen radicals exert a deleterious effect on the cell membrane. Endothelial cell membrane injury leads to increased vascular permeability and cell edema. The development of the 'organ in shock' may require a few hours and initially cause minor or no functional impairment at all. Only when shock is severe is there early organ failure, which in this stage may still be an expression of non-bacterial inflammation. Numerous studies have reported the existence of shock-induced cardiodepressant substances in association with various forms of circulatory shock. We have determined a net negative inotropic effect of the low-molecular-weight plasma fraction in severe hypovolemic-traumatic shock and have isolated a cardiodepressant factor (CDF), which by blockade of the calcium inward current has a negative inotropic a chronotropic effect. The intestine as a shock organ appears to range first among the organs involved. The translocation of bacteria from the intestinal tract, the 'intestine in shock' represents the trigger reaction that eventually leads from the 'organ in shock', early organ failure to late (septic) organ failure. Here the most prominent factor is endotoxin (LPS) as a basic mediator of gram-negative bacteria, which also triggers the activation of humoral and cellular systems. The posttraumatic hyperdynamic phase commonly starts on days 3-5 and is mainly caused by bacteremia and/or endotoxemia. Macrophages have a major impact on the late phase of organ failure. At present, the most prominent cellular mediator of the lethal effect of endotoxin is thought to be cachectin, which is identical with the tumor necrotising factor (TNF). TNF is secreted by monocytes/macrophages (MO/MA) in response to LPS. Via macrophage derived cytokines and by LPS there is activation of endothelial cells, with increased adhesiveness for PMN. Both due to this increased adhesiveness and the presence of LPS and cytokines, PMN undergo massive activation, which causes mediator release and tissue damage.(ABSTRACT TRUNCATED AT 400 WORDS)

Anaphylatoxin and terminal complement complexes in red cell salvage

Thirteen patients undergoing elective orthopedic surgery were studied regarding anaphylatoxin (C3a and C5a) and terminal complement complex (TCC) formation in association with red cell salvage. The auto-transfusion equipment gave a centrifuged and washed erythrocyte fraction. The concentrations of C5a and TCC were not increased but elevated C3a levels were found in the suspension. After infusion of the erythrocyte fraction to the patient, no signs of systemic complement activation were observed. Thus, plasma levels of C3a, C5a and TCC were within the normal range in all the patients before and after autotransfusion. This study indicates that the complement system is activated in the cellsaver equipment. The washing procedure, however, seems to eliminate most of the anaphylatoxins and terminal complement complexes. No extensive systemic activation of complement seems to occur in association with autotransfusion to patients undergoing elective surgery.

Mediators of multiple organ failure

Multiple Organ Failure (MOF) has largely been attributed to bacterial sepsis, though conclusive evidence of an essential role for bacteria and/or their endotoxins is still lacking. On the other hand, MOF and the clinical syndrome of sepsis may be aseptically induced in germ-free animals. This paper reviews the evidence that excessive activation of endogenous humoral mediators and inflammatory cells may cause this highly lethal syndrome.

Complement activation and neutrophil dysfunction in burned patients with sepsis--a study of two cases

The changes in complement components and neutrophil functions were investigated in two cases of flame burn patients who died of multiple organ failure following septic shock. In the period of bacteremia, complement activation was observed in the plasma of both patients, using an immunoblotting method demonstrating C3a-related antigens. Coincidently, reduced neutrophil function and a decrease in the superoxide and leukotriene producing capacity, were also observed. An in vitro study showed that the capacity to produce superoxide and leukotriene became reduced in normal neutrophils after exposure to complement activated serum. These observations suggested that complement activation, probably brought about by massive bacterial infection, induced the impairment of neutrophil functions and resulted in a further breakdown of the host defence system, thereby leading to sepsis.

The gut origin septic states in blunt multiple trauma (ISS = 40) in the ICU

The association between support elements (ventilator days = Vd, enteral protein = EnP, number of antibiotics per day = AB/d) and the magnitude of the septic state (SSS) and its bacteriologic manifestations (bacti. log) in 66 patients with blunt multiple trauma (mean HTI-ISS = 40) over 1649 days have been studied retrospectively. SSS is measured by summing the standard deviation units of change in the septic direction for the 16 measurements taken every day in the intensive care unit. Increasing Vd is tightly associated with an increasing SSS (r = +0.52), after day 10 an increasing bacti. log (r = +0.21 to +0.32), and an increasing AB/d (r = +0.26) (all p less than 0.001, N = 1615 - 1626). The independent variables that best predicted Vd were delayed operations (DORS), day of rising EnP, and total positive blood cultures (TPC) (adj. R sq. = 0.84, F = 104, dF = 3/59). An increasing AB/d was associated with an increasing SSS (r = +0.38), increasing Vd (r = +0.26), and an increased bacti. log (r = +0.14 to +0.18) (all p less than 0.001, N = 1615). Only an increased EnP was consistently associated with a reduced SSS (r = -0.38) and a reduction in bacti. log (r = -0.10 to -0.21) (all p less than 0.001, N = 1626-1636). The independent variables Vd, EnP, AB/d, and TPC best predicted SSS for all surviving patients (adj. R sq. = 0.42, F = 268, dF = 4/1496). The patients who died of sepsis were not different in terms of bacti. log from those with equal Vd but were distinguished by zero EnP, high AB/d, and persistent ventilatory support. In conclusion, DORS is tightly associated with increased Vd, SSS, AB/d, and zero EnP. If Vd exceeds 10, there is an increasing bacti. log and evidence of infection probably from the gut. This responds only to increased EnP and not to AB/d. Death due to sepsis is not associated with increased bacti. log but with zero EnP and high AB/d and their consequences.

The ischaemic leg as a source of complement activation

Complement activation before and after surgical resection was studied in 40 patients with ischaemic legs (17 with acute and 23 with chronic ischaemia). Plasma anaphylatoxin concentrations (C3a and C5a) and anaphylatoxin inhibitor (AI) activity were studied pre-operatively, and 1 h, 24 h and 1 week postoperatively. Increased plasma anaphylatoxin concentrations were found pre-operatively. Anaphylatoxin levels in plasma had returned to normal one week postoperatively. Patients with acute ischaemia had higher plasma C3a and C5a pre-operatively and during the first 24 h postoperatively than patients with chronic ischaemia. Anaphylatoxins increase vascular permeability, smooth muscle contraction and histamine release from mast cells. Their enhanced activity might be one of the explanations for respiratory, hepatic and renal insufficiency before surgical resection in patients with extensive ischaemia.

A policy of early excision and grafting in elderly burn patients shortens the hospital stay and improves survival

Early excision and grafting of the burn wound appears to shorten the hospital stay and decrease mortality in children and adults. However, whether an early surgical approach is safe in elderly burn patients has not been resolved. To answer this question we carried out a prospective study of early surgery in 114 consecutive patients over the age of 50 years. Patients were generally operated on between post-burn days 2 and 5. The mean age of the patients was 68 years, with a burn size of 22 per cent, of which 13 per cent was full thickness skin loss. The mean hospital stay of the surviving patients was reduced by 40 per cent compared to national averages (P less than 0.001). The mortality rate for the entire group of patients was 17 per cent, with 2 deaths in the 65 patients with burns less than 20 per cent total body surface area (TBSA). Although the mortality rate for patients with burns greater than 20 per cent TBSA was 35 per cent, this was less than predicted (P less than 0.05). The improvement in survival appeared to be due to a decrease in the incidence of lethal burn wound infections.

Infections in burn patients: a paradigm for cutaneous infection in the patient at risk

The burn patient is in many ways the archetypical immunosuppressed host: the anatomic barriers have been breached and the host's defenses suppressed. Infection is the leading cause of death in hospitalized burn patients not having inhalation injury, being responsible for between 50 and 75 percent of the hospital deaths. Burn injury produces profound abnormalities in immunologic function. These changes are generally proportional to the degree of burn injury (surface area and depth). Cell-mediated immune function is suppressed. Anergy and depressed allograft rejection occur. Acute burn serum samples contain several factors that suppress cell-mediated immune functions. Antibody levels are usually mildly to moderately reduced. Complement, particularly the alternative complement pathway, may be massively activated and depleted, removing a critical defense mechanism against gram-negative rod infections for which preformed antibodies are absent. This depression is further exacerbated by malnutrition and infection. Fibronectin levels are also reduced. Phagocytic cell function is abnormal with burns. Neutrophil numbers may be depressed, and function is abnormal. Chemotactic responsiveness, cytoplasmic granule enzyme content, and oxygen radical generation are abnormal. Monocyte/macrophage dysfunction has similarly been demonstrated. Burn infections reflect abnormal host functions as well as changes in the hospital environment and microbial selection pressures. The burn patient is a model of cutaneous infection in the patient at risk.

Muscle proteolysis induced by a circulating peptide in patients with sepsis or trauma

Accelerated proteolysis of muscle is characteristic in patients with trauma or sepsis, but its cause is not well understood. Using rat muscle in vitro, we developed a bioassay to compare the proteolytic activity of plasma from 50 patients with trauma or sepsis with that of plasma from 14 normal volunteers and from 15 patients who had undergone "clean" elective surgical procedures. The mean proteolytic activity in the plasma of patients with trauma or sepsis was found to be 190 +/- 8.0 per cent of the control value (rat muscle incubated in medium alone), whereas the activity in normal plasma was 124 +/- 4.5 per cent (P less than 0.001). The activity in the plasma of patients who had undergone elective surgery was slightly elevated at 142 +/- 2.5 per cent (P less than 0.005). In 25 of the patients with trauma or sepsis the rate of amino acid release from one leg was measured by subtracting the concentration of tyrosine plus phenylalanine in the femoral artery plasma from that in the femoral vein; this rate correlated well with the bioactivity of the plasma in the bioassay system (r = 0.67, P less than 0.001). By means of ultrafiltration and chromatography, the plasma factor inducing proteolysis was isolated and found to be a peptide, probably containing sialic acid, with a chain of 33 amino acids and a molecular weight of approximately 4274 daltons.