Translocation of endotoxin and acute-phase proteins in malleolar fractures

The effects of direct hemoperfusion using a polymyxin B-immobilized column in a pig model of severe Pseudomonas aeruginosa pneumonia

Background

Hemoperfusion through a column containing polymyxin B-immobilized fiber (PMX-HP) is beneficial in abdominal sepsis. We assessed the effects of PMX-HP in a model of severe Pseudomonas aeruginosa pneumonia.

Methods

Eighteen pigs with severe P. aeruginosa pneumonia were mechanically ventilated for 76 h. Pigs were randomized to receive standard treatment with fluids and vasoactive drugs, or standard treatment with two 3-h PMX-HP sessions. Antibiotics against P. aeruginosa were never administered. We assessed endotoxemia through the endotoxin activity assay (EA). We measured the static lung elastance, ratio of arterial partial pressure per inspiratory fraction of oxygen (PaO₂/FIO₂), mean arterial pressure, cardiac output, systemic vascular resistance and inotropic score. Finally, every 24 h, we assessed complete blood count.

Results

In comparison with the control group, PMX-HP decreased percentage of circulating neutrophils from 47.4 ± 13.8 to 40.8 ± 11.5 % (p = 0.009). In a subgroup of animals with the worst hemodynamic impairment, EA in the control and PMX-HP groups was 0.50 ± 0.29 and 0.29 ± 0.14, respectively (p = 0.018). Additionally, in the control and PMX-HP groups, static lung elastance was 26.9 ± 8.7 and 25.3 ± 7.5 cm H₂O/L (p = 0.558), PaO₂/FIO₂ was 347.3 ± 61.9 and 356.4 ± 84.0 mmHg (p = 0.118), mean arterial pressure was 81.2 ± 10.3 and 81.6 ± 13.1 mmHg (p = 0.960), cardiac output was 3.30 ± 1.11 and 3.28 ± 1.19 L/min (p = 0.535), systemic vascular resistance was 1982.6 ± 608.4 and 2011.8 ± 750.0 dyne/s/cm^–5 (p = 0.939), and inotropic score was 0.25 ± 0.10 and 0.26 ± 0.18 (p = 0.864).

Conclusions

In mechanically ventilated pigs with severe P. aeruginosa pneumonia, PMX-HP does not have any valuable clinical benefit, and studies are warranted to fully evaluate a potential role of PMX-HP in septic shock associated with severe pulmonary infections.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-016-0155-3) contains supplementary material, which is available to authorized users.

The Effect of Different Types of Musculoskeletal Injuries on Blood Concentration of Serum Amyloid A in Thoroughbred Racehorses

BACKGROUND

Training-induced muscle, skeletal and joint trauma may result in acute phase response reflected by the changes in the blood concentration of serum amyloid A (SAA) in racehorses. It remains yet unclear if such systemic reaction could be triggered by sport injuries and what is the impact of different types of musculoskeletal trauma on SAA concentrations in racehorses. This study aimed to determine changes in the SAA blood concentration in racehorses with different types of injuries of musculoskeletal system.

MATERIALS AND METHODS

The study involved 28 racehorses diagnosed after the race with bone fractures (n = 7), dorsal metacarpal disease (n = 11), joint trauma (n = 4) or tendon and muscle trauma (n = 6) and 28 healthy control racehorses. Serum samples were collected twice, between 1 and 4 days of the injury or succesful completion of the race. SAA concentration was measured using the commercial ELISA kit. Differences between mean SAA concentration in respective groups were analyzed using ANOVA and Tukey post-hoc test.

RESULTS

Mean SAA concentration within the first 4 days of the injury of muscle and tendon was significantly higher than in bone fractures, dorsal metacarpal disease, joint trauma or in the healthy horses (p<0,001). There were no significant differences between the other groups.

CONCLUSIONS

Strain injuries of muscle and tendons can cause a moderate increase in SAA blood concentration in racehorses, reflecting the occurrence of the acute phase response. Similar reaction is not observed in the stress-related bone injuries.

Post-exercise dynamics of serum amyloid A blood concentration in thoroughbred horses classified as injured and non-injured after the race

The aim of this study was to evaluate serum amyloid A (SAA) concentration in horses with orthopedic injuries acquired during racing and in healthy ones after completing the race. Injuries of bone and tendon did not cause radical increase in SAA concentration observed in other inflammatory conditions. SAA concentration correlated positively with white blood cell count (WBC) on the 3rd-4th days after race being significantly higher in the injured horses than in the control group in that time. It was suggested that racing effort may cause increase in SAA level, more pronounced in horses manifesting clinical signs of orthopedic injury after the race.

Effect of major abdominal surgery on endotoxin release and expression of Toll-like receptors 2/4

BACKGROUND

Surgery can cause endotoxemia, and endotoxin aggregates to Toll-like receptors and acts proinflammatory; repetitive endotoxin application can cause tolerance. The objective of the study is to characterize early inflammatory response and expression of TLR2/4 during major abdominal surgery.

MATERIALS AND METHODS

A prospective controlled study of 20 patients with elective major abdominal surgery was performed. Blood samples were collected before and at a defined time after surgery. Endotoxemia, capability of plasma to inactivate endotoxin, cytokine release of LPS-stimulated mononuclear cells, quantitative TLR mRNA expression, and plasma concentrations of TNFalpha, IL-6, C-reactive protein (CRP), alpha(1)-acid glycoprotein, transferrin, and albumin were measured.

RESULTS

Surgery caused endotoxemia (p = 0.053), and the capability of plasma to inactivate endotoxin was reduced (p = 0.0002). Two hours postoperatively, the plasma concentrations of TNFalpha and IL-6 peaked significantly, but the liberation capacity of mononuclear cells for cytokines (TNFalpha, IL-1beta, IL-6) was significantly reduced. The concentration of CRP and alpha(1)-acid glycoprotein peaked 48 h postoperatively, but those of transferrin and albumin were significantly decreased (p < 0.001, respectively). Median mRNA expression of TLR2 and TLR4 of mononuclear cells was not altered, and there was no obvious trend over time.

CONCLUSION

Major abdominal surgery is associated with endotoxemia, reduced capability of plasma to inactivate endotoxin, cytokine kinetics resembling those of healthy man after experimentally given LPS, and substantial acute-phase reaction. The cytokine liberation of mononuclear cells suggests a state of postoperative endotoxin tolerance. Despite these substantial changes, trends in TLR2/4 expression are not obvious.

Endotoxemia and endotoxin tolerance in patients with ARDS

BACKGROUND

The significance of endotoxemia in man is controversial, induces cytokine release and stimulates the immune system. Exaggerated cytokine release of mononuclear cells was observed in acute lung injury/acute respiratory distress syndrome (ALI/ARDS). However, repetitive administration of endotoxin can cause tolerance.

OBJECTIVE

To investigate endotoxemia, plasma TNFalpha, IL-1beta, IL-6, the liberation capacity of those cytokines from mononuclear cells after LPS challenge (Delta values), and plasma antibodies to endotoxins and alpha-hemolysin of Staphylococcus aureus in ALI/ARDS.

DESIGN

A prospective clinical study was conducted.

SETTING

The study was carried out at the University Hospital Ulm, Ulm, Germany.

SUBJECTS

The respondents were 23 patients with ALI/ARDS.

INTERVENTIONS

ALI/ARDS was defined according to the American-European Consensus Conference on ARDS. Blood was collected periodically. Parameters were measured by LAL or ELISA.

RESULTS

ARDS (P(a)O(2)/F(i)O(2) < 200) revealed higher endotoxemia (0.22-0.46 [0.06-1.15] EU/mL vs 0.05-0.14 [0.02-0.63] EU/mL) than ALI (P(a)O(2)/F(i)O(2) > 200) but lower DeltaIL-6 (124-209 [10-1214] pg/mL vs 298-746 [5-1797] pg/mL), DeltaTNFalpha (50-100 [6-660] pg/mL vs 143-243 [12-2795] pg/mL), and DeltaIL-1 (2-3 [0-26] pg/mL vs 2-14 [0-99] pg/mL). Endotoxemia correlated negative with P(a)O(2)/F(i)O(2) (r, -0.44 to -0.50). All patients presented antibodies to lipopolysaccharides and alpha-hemolysin, but the level did not correlate with P(a)O(2)/F(i)O(2).

CONCLUSIONS

ALI/ARDS is associated with endotoxemia. The more severe the disease, the more intense is endotoxemia but the lower is the capacity of mononuclear cells to release cytokines (tolerance). Antibodies against Gram-positive and Gram-negative bacteria are detectable in the plasma but without relation to P(a)O(2)/F(i)O(2).

Acute trauma with multiple injuries

Trauma with multiple injuries is a leading cause of death. It presents a diversity of challenges and requires many healthcare workers to care for its victims. Advances continue in the organization of pre-hospital care, the techniques of trauma surgery and critical care, and understanding the pathophysiology of traumatic injuries.

C-reactive protein as a parameter of surgical trauma: CRP response after different types of surgery in 349 hip fractures

BACKGROUND

Postoperative C-reactive protein (CRP) levels in serum appear to reflect surgical trauma. We examined CRP levels after different types of surgery in hip fractures.

METHODS

We studied the CRP response after 349 operative procedures in proximal femur fractures with a normal postoperative course. 5 different operative techniques were used: 3-4 percutaneous cancellous screws, dynamic hip screw (DHS), proximal femur nail (PFN), hemiarthroplasty (HA), and total hip arthroplasty (THA).

RESULTS

Peak CRP levels were reached on the second postoperative day in each group (medians: screws 8.7, DHS 12, PFN 14, HA 16, THA 16 mg/dL). Significant differences were found between screws and all others, and between DHS and arthroplasties.

INTERPRETATION

CRP levels following surgical trauma can be used to quantify the degree of tissue damage and invasiveness of a procedure and reflect the perioperative stress experienced by the patient.

Lipopolysaccharide impairs fracture healing: an experimental study in rats

BACKGROUND

It has been shown that trauma causes translocation of lipopolysaccharide (LPS) endotoxins from the gut. LPS has been identified as a major bacterial bone resorbing factor. The effects of LPS on bone healing are therefore of clinical interest, as trauma involving fractures followed by sepsis is a clinical scenario. We investigated the effects of systemic and local administration of LPS on the healing of femoral fractures in rats.

ANIMALS AND METHODS

In 3 groups, each consisting of 9 rats, a mid-diaphyseal osteotomy/fracture of the femoral bone was performed and then nailed. In one group of animals, LPS was applied intraperitoneally (systemically), and in another group, LPS was applied locally at the fracture site. The third group served as a control. The animals were killed after 6 weeks, and the mechanical characteristics of the healing osteotomies were evaluated.

RESULTS

We found that LPS induced a hypertrophic and immature callus, as evaluated by bone mineral content and density. In the rats given LPS intraperitoneally, the mechanical strength characteristics were reduced, as evaluated by bending moment, rigidity, and energy absorption.

INTERPRETATION

The rats given LPS intraperitoneally reflect a clinical situation with fracture trauma and endotoxinemia. Our findings indicate that endotoxinemia may impair the fracture healing processes.

Lipopolysaccharide: An Endotoxin or an Exogenous Hormone?

Conventional models of the pathogenesis of sepsis assume that microorganisms or their products are necessarily injurious to the host. In contrast, an evolutionary perspective suggests that host-microbial interactions are a symbiotic model and that disease results from the disruption of a mutually beneficial homeostatic state. Lipopolysaccharide (LPS) from gram-negative bacteria is a prototypical trigger of sepsis and a target for the development of novel therapeutics. The biological mechanisms underlying the recognition of, and response to, LPS are more characteristic of a hormone than of a toxin. All mammals carry endogenous stores of LPS and express dedicated carrier proteins, a cellular receptor complex, and mechanisms that specifically antagonize the response to LPS. Disruption of any component of this complex recognition system jeopardizes host defenses against infection with exogenous microorganisms. Thus, LPS is not less an endotoxin than an exohormone, and its neutralization may potentially result in either benefit or harm.

Methodological studies on plasma endotoxin level and endotoxin inactivation capacity

To establish stable methods for detecting plasma endotoxin level and endotoxin inactivation capacity in a normal population and general surgical patients and evaluate their perioperative changes. 50 healthy people and 50 patients receiving gastrointestinal operation were enrolled, their plasma endotoxin levels and plasma endotoxin inactivation capacity were assayed. Our results showed that plasma endotoxin levels were 0.044 +/- 0.009 EU/ml in the normal population and 0.044 +/- 0.023 EU/ml in the preoperative patients. Endotoxin level peaked 3 h after the operation (0.223 +/- 0.041 EU/ml), and then decreased rapidly on the first day after the operation (0.134 +/- 0.164 EU/ml). Endotoxin inactivation capacity also had the same time course as endotoxin level. Systemic inflammatory response syndrome and infection induced another elevation in the time course. It is concluded that establishing the endotoxin standard curve by using pyrogenic free water is better than by using plasma. Plasma endotoxin inactivation capacity can be used as an indirect indicator of postoperative immune depression. Plasma endotoxin level and endotoxin inactivation capacity peaked shortly after operation, indicating surgical stress is closely related with the changes.

Influence of modest endotoxemia on postoperative antithrombin deficiency and circulating secretory immunoglobulin a levels

OBJECTIVE

To evaluate the influence of modest endotoxemia on postoperative antithrombin deficiency and cholestasis.

SUMMARY BACKGROUND DATA

It has not been determined whether endotoxin translocation in small amounts is a physiological phenomenon or whether it is a potential health hazard.

METHODS

Blood endotoxin, antithrombin III (ATIII), secretory immunoglobulin A (sIgA), which was selected as a marker of cholestasis, C-reactive protein (CRP), and alpha-1-antitrypsin (AAT) concentrations were measured from the 20 patients undergoing curative gastrectomy for gastric cancer preoperatively and postoperatively. Portal and systemic blood samples were taken for the analysis of endotoxin and interleukin-6 (IL-6) concentrations during surgery in these patients.

RESULTS

Although plasma endotoxin levels showed a significant increase during surgery, we did not find a correlation with ATIII, sIgA, CRP, and IL-6 levels. Systemic blood endotoxin levels during surgery correlated with a postoperative rise of serum AAT levels. Plasma ATIII levels transiently decreased on the first and third postoperative day, and sIgA levels were shown to increase on the seventh postoperative day. There was a weak relationship between the extent of postoperative endotoxemia and a reduction in ATIII concentrations.

CONCLUSIONS

The influence of modest endotoxemia on postoperative antithrombin deficiency and cholestasis was limited, and increased translocational endotoxemia during abdominal surgery may be a physiological phenomenon to trigger off an acute-phase protein response.

Low albumin level in the emergency department: a potential independent predictor of delayed mortality in blunt trauma

Albumin is an abundant plasma protein with multiple physiologic functions, and low serum albumin levels have been associated with increased mortality in hospitalized patients. In a retrospective matched-pair study, we investigated whether emergency department (ED) albumin levels predict delayed mortality for patients initially stabilized after blunt trauma. Fifty-one hospital non-survivors who died more than 24 h after admission to a trauma center ED were matched by Injury Severity Score, type and location of injury, age, and gender with 51 survivors. All patients had serum albumin levels determined upon arrival in the ED. The non-survivors had a significantly lower admission albumin of 3.1 g/dL compared to 3.5 g/dL for survivors. Patients with albumin levels < 3.4 g/dL were 2.5 times more likely to die compared to patients with normal albumin levels. These preliminary results indicate that initial hypoalbuminemia in blunt trauma patients is an independent predictor of delayed mortality, suggesting that these patients require continued clinical vigilance and an aggressive search for evolving complications.

Cellular mechanisms that cause suppressed gamma interferon secretion in endotoxin-tolerant mice

Endotoxin (lipopolysaccharide [LPS]) tolerance is a state of altered immunity characterized, in part, by suppression of LPS-induced gamma interferon (IFN-gamma) expression. However, the cellular mediators regulating LPS-induced production of IFN-gamma in normal mice and the effect of LPS tolerance on these mediators has not been well characterized. Our studies show that macrophage dysfunction is the primary factor causing suppressed IFN-gamma expression in LPS-tolerant mice. Specifically, LPS-tolerant macrophages have a markedly impaired ability to induce IFN-gamma secretion by T cells and NK cells obtained from either control or LPS-tolerant mice. However, T cells and NK cells isolated from LPS-tolerant mice produce normal levels of IFN-gamma when cocultured with control macrophages or exogenous IFN-gamma-inducing factors. Assessment of important IFN-gamma-regulating factors showed that interleukin-12 (IL-12) and costimulatory signals provided by IL-15, IL-18, and CD86 are largely responsible for LPS-induced IFN-gamma expression in control mice. IL-10 is an inhibitor of IFN-gamma production in both the control and LPS-tolerant groups. Expression of IL-12 and the IL-12 receptor beta1 (IL-12Rbeta1) and IL-12Rbeta2 subunits are suppressed in the spleens of LPS-tolerant mice. LPS-tolerant splenocytes also exhibit decreased production of IL-15 and IL-15Ralpha. However, expression of IL-18 and the B7 proteins CD80 and CD86 are unchanged or increased compared to controls after induction of LPS tolerance. CD28, a major receptor for B7 proteins, is also increased in the spleens of LPS-tolerant mice. Expression of the inhibitory cytokine IL-10 and the IL-10R are sustained after induction of LPS tolerance. These data show that suppression of IFN-gamma production in LPS-tolerant mice is largely due to macrophage dysfunction and provide insight into the cellular alterations that occur in LPS tolerance. This study also better defines the factors that mediate LPS-induced IFN-gamma production in normal mice.

Endotoxemia and acute-phase proteins in major abdominal surgery

BACKGROUND

Translocation of endotoxin is a controversial issue. The ability of plasma to inactivate endotoxin is an indirect measure of endotoxemia. Endotoxin is a potent stimulator of the inflammatory response and affects the innate immune system.

OBJECTIVE

To elucidate the kinetics of endotoxemia and the ability of plasma to inactivate endotoxin in patients with major abdominal operations. To demonstrate the early time course of the acute-phase proteins C-reactive protein (CRP), serum amyloid A (SAA), alpha(1)-antitrypsin, alpha(2)-macroglobulin, transferrin, and interleukin 6 (IL-6), and to correlate them with the amount of endotoxemia.

METHODS

Twenty patients with elective major abdominal operation and 10 healthy controls were investigated. Blood was collected preoperatively, during the operation and regularly up to 12 days after surgery. Endotoxin was measured by Limulus amebocyte lysate test (LAL), the ability of plasma to inactivate endotoxin by modified LAL, the acute-phase proteins nephelometrically, and IL-6 by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Preoperative endotoxin plasma level (0.026 +/- 0.004 EU/mL) did not differ from healthy volunteers but increased during operation (0.09 +/- 0.02 EU/mL, P = 0.02). Endotoxemia peaked 1 hour after the surgical procedure (0.16 +/- 0.03 EU/mL; P <0.0001 versus preoperative) and decreased to almost normal values after 48 hours. The capability of plasma to inactivate endotoxin was significantly reduced during (recovery, 0.16 +/- 0.03 EU/mL), 1 hour (0.25 +/- 0.04 EU/mL) and 24 hours (0.16 +/- 0.02 EU/mL) after the operation compared with preoperative (0.068 +/- 0.01 EU/mL) values. Plasma IL-6 was significantly increased for 48 hours with a peak 1 hour after surgery (470 +/- 108 pg/mL). CRP peaked at 210 +/- 19 mg/L (P <0.0001 versus preoperative) 48 hours after operation and was significantly elevated for the rest of the observation period. SAA was significantly increased 24 hours after surgery (249 +/- 45 mg/L) and peaked additional 48 hours later (456 +/- 86 mg/L). alpha(1)-Antitrypsin, although a positive acute-phase protein, decreased initially to 1.38 +/- 0.1 g/L (preoperative, 2.33 +/- 0.18 g/L; P <0.0001) and increased thereafter until day 12 (3.05 +/- 0.35 g/L, P = 0.11 versus preoperative). The same was true for alpha(2)-macroglobulin (preoperative, 2.2 +/- 0.16 g/L; intraoperative, 1.36 +/- 0.13 g/L; day 5, 2.8 +/- 0.4 g/L). Transferrin decreased already during surgery (1.6 +/- 0.1 g/L versus preoperative 2.8 +/- 0.17 g/L, P <0.0001) and remained on this level for 5 days. Correlation analysis revealed a relationship between endotoxemia and the ability of plasma to inactivate endotoxin (r = 0.67, P <0.0001) and also a relation between intraoperative endotoxemia on one hand and alpha(2)-macroglobulin (-0.53 > r > -0.6, P <0.05) as well as alpha(1)-antitrypsin (0.64 > r >0.55, P <0.05) on the other.

CONCLUSION

Major abdominal surgery is associated with transient endotoxemia and a transient reduced endotoxin inactivation capacity of the plasma. Endotoxemia correlates with the endotoxin inactivation capacity. The surgical procedure causes substantial changes in plasma concentrations of acute-phase proteins. alpha(2)-Macroglobulin and alpha(1)-antitrypsin correlate moderately with endotoxemia.