Inflammatory Host Responses in Sepsis

Peripheral innate and adaptive immune cells during COVID-19: Functional neutrophils, pro-inflammatory monocytes, and half-dead lymphocytes

BACKGROUND

A better understanding of innate and adaptive cells in COVID-19 is necessary for the development of effective treatment methods and vaccines.

METHODS

We studied phenotypic features of innate and adaptive immune cells, oxidative burst, phagocytosis, and apoptosis. One hundred and three patients with COVID-19 were grouped according to their clinical features into the categories of mild (35%), moderate (40.8%), and severe (24.3%).

RESULTS

Monocytes were CD16⁺ pro-inflammatory monocytes and tended to shed their HLA-DR, especially in severe cases (p < 0.01). Neutrophils were mature and functional, although a decline of their CD10 and CD16 was observed (p < 0.01). No defect was found in the reactive oxygen species production and their apoptosis. The percentage of natural killer cells was in the normal range, whereas the percentages of CD8⁺ NK and CD56⁺ T lymphocytes were found to be high (p < 0.01). Although the absolute numbers of all lymphocyte subsets were low and showed a tendency for a gradual decrease in accordance with the disease progression, the most decreased absolute number was that of B lymphocytes, followed by CD4⁺ T cells in the severe cases. The percentages of double-negative T cells; HLA-DR⁺ CD3⁺ and CD28^- CD8⁺ subsets were found to be significantly increased. Importantly, we demonstrated the increased baseline activation of caspase-3 and increased lymphocyte apoptosis.

CONCLUSION

We suggest that SARS-CoV-2 primarily affects the lymphocytes and not the innate cells. The increased baseline activation of Caspase-3 could make the COVID-19 lymphocytes more vulnerable to cell death. Therefore, this may interrupt the crosstalk between the adaptive and innate immune systems.

Alpha-Ketoglutarate: Physiological Functions and Applications

Alpha-ketoglutarate (AKG) is a key molecule in the Krebs cycle determining the overall rate of the citric acid cycle of the organism. It is a nitrogen scavenger and a source of glutamate and glutamine that stimulates protein synthesis and inhibits protein degradation in muscles. AKG as a precursor of glutamate and glutamine is a central metabolic fuel for cells of the gastrointestinal tract as well. AKG can decrease protein catabolism and increase protein synthesis to enhance bone tissue formation in the skeletal muscles and can be used in clinical applications. In addition to these health benefits, a recent study has shown that AKG can extend the lifespan of adult Caenorhabditis elegans by inhibiting ATP synthase and TOR. AKG not only extends lifespan, but also delays age-related disease. In this review, we will summarize the advances in AKG research field, in the content of its physiological functions and applications.

Surfactant dysfunction and lung injury due to the E. coli virulence factor hemolysin in a rat pneumonia model

This study tests the hypothesis that the virulence factor hemolysin (Hly) expressed by extraintestinal pathogenic Escherichia coli contributes to surfactant dysfunction and lung injury in a rat model of gram-negative pneumonia. Rats were instilled intratracheally with CP9 (wild type, Hly-positive), CP9hlyA (Hly-minus), CP9/pEK50 (supraphysiological Hly), or purified LPS. At 6 h postinfection, rats given CP9 had a decreased percentage content of large surfactant aggregates in cell-free bronchoalveolar lavage (BAL), decreased large aggregate surface activity, decreased Pa(O2)/FiO2) ratio, increased BAL albumin/protein levels, and increased histological evidence of lung injury compared with rats given CP9hlyA or LPS. In addition, rats given CP9/pEK50 or CP9 had decreased large aggregate surface activity, decreased Pa(O2)/FiO2) ratios, and increased BAL albumin/protein levels at 2 h postinfection compared with rats given CP9hlyA. The severity of permeability lung injury based on albumin/protein levels in BAL at 2 h was ordered as CP9/pEK50 > CP9 > CP9hlyA > normal saline controls. Total lung titers of bacteria were increased at 6 h in rats given CP9 vs. CP9hlyA, but bacterial titers were not significantly different at 2 h, indicating that increased surfactant dysfunction and lung injury were associated with Hly as opposed to bacterial numbers per se. Further studies in vitro showed that CP9 could directly lyse transformed pulmonary epithelial cells (H441 cells) but that indirect lysis of H441 cells secondary to Hly-induced neutrophil lysis did not occur. Together, these data demonstrate that Hly is an important direct mediator of surfactant dysfunction and lung injury in gram-negative pneumonia.

Effects of glutamine supplementation on innate immune response in rats with gut-derived sepsis

The present study examined the effect of glutamine (Gln)-enriched diets before sepsis or Gln-containing total parenteral nutrition (TPN) after sepsis, or both, on the phagocytic activity and blood lymphocyte subpopulation in rats with gut-derived sepsis. Rats were assigned to a control group or one of four experimental groups. The control group and groups 1 and 2 were fed a semipurified diet; groups 3 and 4 had part of casein replaced by Gln. After feeding the diets for 10d, sepsis was induced by caecal ligation and puncture (CLP); TPN was maintained for 3d after CLP. The control group and groups 1 and 3 were infused with conventional TPN and groups 2 and 4 were supplemented with Gln in the TPN solution. All rats were killed 3d after CLP or sham operation to examine their immune responses. The results showed that compared with the control group, the phagocytic activities of peritoneal macrophages were enhanced in groups 3 and 4, but not in groups 1 and 2. The proportion of CD3+ cells in group 1 was significantly lower (P<0·05) than that of the control group, whereas no differences were observed among the control and Gln-supplemented groups. The CD4+ cell proportion was significantly lower (P<0·05) in group 1 compared with the control group and groups 3 and 4. These findings suggest that Gln-enriched diets before CLP significantly enhanced peritoneal macrophage phagocytic activity, preserved CD4+ cells and maintained blood total T lymphocytes in gut-derived sepsis. However, parenteral Gln administration after caecal ligation and puncture had no favourable effects on modulating immune response in septic rats.

Effects of arginine-containing total parenteral nutrition on N balance and phagocytic activity in rats undergoing a partial gastrectomy

The present study investigated the effect of arginine (Arg)-containing parenteral nutrition on phagocytic activity to elucidate the possible roles of Arg in the secretion of anabolic hormones and N balance in rats undergoing gastrectomy. Rats were divided into two experimental groups and received total parenteral nutrition (TPN). The TPN solutions were isonitrogenous and identical in nutrient compositions except for differences in amino acid content. One group received conventional TPN, the other group replaced 2 % of the total energy as Arg. After receiving TPN for 3 d, one-third of the rats in each experimental group were killed as the baseline group. The remaining rats underwent a partial gastrectomy and were killed 1 or 3 d after surgery. The results showed that there were no differences in N balance, plasma growth hormone and insulin-like growth factor-1 levels between the two groups before or after surgery. The phagocytic activity of peritoneal macrophages was higher in the Arg group than in the control group 1 d after surgery. There were no differences in the phagocytic activities of blood polymorphonuclear neutrophils between the two groups at various time points. TNF-α levels in peritoneal lavage fluid were lower in the Arg group than in the control group on post-operative day 3. These results suggest that parenterally infused Arg enhances phagocytic activity and reduces the production of inflammatory mediators at the site of injury. However, Arg supplementation did not influence the secretion of anabolic hormones nor N balance in rats with a partial gastrectomy.

PARENTERAL N-3 FATTY ACIDS MODULATE INFLAMMATORY AND IMMUNE RESPONSE IN RATS UNDERGOING TOTAL GASTRECTOMY

This study investigated the effect of n-3 fatty acid (FA)-containing parenteral nutrition on the circulatory lymphocyte subpopulation, intracellular cytokine and leukocyte adhesion molecule expression, and phagocytic activity in rats undergoing total gastrectomy. Normal rats with internal jugular catheters were assigned to normal control (NC) and two experimental groups and received total parenteral nutrition (TPN). At the same time, a total gastrectomy was performed in the experimental groups, whereas the NC group underwent a sham operation. The TPN solutions were isonitrogenous and identical in nutrient compositions except for differences in fat emulsion contents. The NC and one of the experimental groups received a soybean oil emulsion (SO), and the other experimental group received 50% soybean oil and 50% fish oil emulsion (FO). Half of the rats in each respective group were sacrificed 1 or 3 days after surgery or the sham operation to examine their immune response. The results showed that the FO group had a higher CD4 proportion and CD4/CD8 ratio than those of the SO and NC groups postoperatively. The phagocytic activity of peritoneal macrophages was higher in the FO group than in the NC group, but no difference was found between the SO and NC groups 3 days after surgery. The intracellular interferon (IFN)-gamma distribution in the FO group was higher than that of the SO group on postoperative days. Leukocyte adhesion molecule expressions and peritoneal monocyte chemotactic protein-1 levels were lower in the FO group than in the SO group on postoperative day 3. These results suggest that parenterally infused FO did not result in immunosuppression. In addition, FO administration promotes lymphocyte Th1 cytokine production, enhances peritoneal macrophage phagocytic activity, and reduces leukocyte adhesion molecule expression in rats with total gastrectomy.

Endotoxin-induced mortality is related to increased oxidative stress and end-organ dysfunction, not refractory hypotension, in heme oxygenase-1-deficient mice

BACKGROUND

Heme oxygenase (HO)-1 is an enzyme that degrades heme to generate CO (a vasodilatory gas), iron, and the potent antioxidant bilirubin. A disease process characterized by decreases in vascular tone and increases in oxidative stress is endotoxic shock. Moreover, HO-1 is markedly induced in multiple organs after the administration of endotoxin (lipopolysaccharide [LPS]) to mice.

METHODS AND RESULTS

To determine the role of HO-1 in endotoxemia, we administered LPS to mice that were wild-type (+/+), heterozygous (+/-), or homozygous null (-/-) for targeted disruption of HO-1. LPS produced a similar induction of HO-1 mRNA and protein in HO-1(+/+) and HO-1(+/-) mice, whereas HO-1(-/-) mice showed no HO-1 expression. Four hours after LPS, systolic blood pressure (SBP) decreased in all the groups. However, SBP was significantly higher in HO-1(-/-) mice (121+/-5 mm Hg) after 24 hours, compared with HO-1(+/+) (96+/-7 mm Hg) and HO-1(+/-) (89+/-13 mm Hg) mice. A sustained increase in endothelin-1 contributed to this SBP response. Even though SBP was higher, mortality was increased in HO-1(-/-) mice, and they exhibited hepatic and renal dysfunction that was not present in HO-1(+/+) and HO-1(+/-) mice. The end-organ damage and death in HO-1(-/-) mice was related to increased oxidative stress.

CONCLUSIONS

These data suggest that the increased mortality during endotoxemia in HO-1(-/-) mice is related to increased oxidative stress and end-organ (renal and hepatic) damage, not to refractory hypotension.

Gram-negative bacterial sepsis and the sepsis syndrome

Gram-negative sepsis syndrome is an increasingly common complication in medical and surgical patients. The molecular and cellular mechanisms underlying this dreaded complication are yielding to investigation. These studies have led to a multiplicity of targets for novel therapies. Despite highly promising results in many animal studies, clinical studies have been disappointing.

G-CSF during Escherichia coli versus Staphylococcus aureus pneumonia in rats has fundamentally different and opposite effects

We investigated if bacteria type alters outcome with prophylactic granulocyte colony stimulating factor (G-CSF) therapy during pneumonia. Rats received G-CSF or placebo daily for 6 d and after the third dose were intrabronchially inoculated with either Escherichia coli or Staphylococcus aureus. Without G-CSF, E. coli and S. aureus produced similar (p = NS) mortality rates (36 versus 38%) and serial changes in mean circulating neutrophil counts (CNC), but differing mean (+/- SE) tumor necrosis factor (TNF) levels (E. coli, 259 +/- 104 versus S. aureus, 51 +/- 17 pg/ml, p = 0.01). G-CSF prior to bacteria increased mean CNC more than six times compared with placebo (p = 0.001). However, with G-CSF in the first 6 h after E. coli, there was a greater than 20-fold decrease in mean (+/- SE) CNC (x 10(3)/ mm3) to below placebo (0.5 +/- 0.1 versus 0.8 +/- 0.1), whereas with G-CSF after S. aureus, there was only a fivefold decrease in mean CNC and CNC were greater than placebo (1.8 +/- 0.2 versus 0.8 +/- 0.1) (E. coli versus S. aureus decrease in CNC with G-CSF, p = 0.001). With E. coli, G-CSF worsened oxygenation and increased bacteremia and mortality, whereas with S. aureus, G-CSF improved oxygenation and decreased bacteremia and mortality (G-CSF therapy, E. coli versus S. aureus, p = 0.03, 0.05, and 0.001, respectively). Thus, during S. aureus pneumonia with low TNF levels, G-CSF increased CNC and bacterial clearance, resulting in less pulmonary injury and decreased death. During E. coli pneumonia with high TNF levels, G-CSF paradoxically decreased CNC, resulting in impaired bacterial clearance and worsened pulmonary injury and death. Bacterial species and the associated inflammatory mediator response can alter outcome with prophylactic G-CSF therapy during pneumonia.

Resistance to endotoxin shock in spontaneously hypertensive rats

Septic shock involves systemic vasodilation mediated by proinflammatory cytokines. In essential hypertension, vascular and immune dysfunctions are closely associated. The response of hypertensive animals compared with normotensive controls to endotoxin (lipopolysaccharide; LPS) challenge is not known. Age-matched (12 weeks) normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were exposed to intravenous injection of 10 mg/kg LPS. Survival rate at 24 hours was markedly higher in SHR than in WKY (12 of 15 and 3 of 15, respectively; P<0.01). Survival of LPS-injected SHR was not related to their hypertension because hydralazine-treated SHR with normalized pressure had similar survival rates, and WKY made hypertensive by clipping of one renal artery showed fatality similar to that of normotensive WKY. Continuous arterial pressure and sequential plasma levels of interleukin-6 (IL-6) and tumor necrosis factor (TNF) were measured in LPS-treated SHR and WKY. Both the duration of the delayed hypotensive phase and the systemic release of IL-6 were much lower in SHR than WKY, whereas both acute hypotension and plasma TNF peak were equivalent. We further explored in vitro the inflammatory response and showed that LPS-activated whole blood from SHR produced less TNF and IL-6 than WKY LPS-activated whole blood. Our results indicate that SHR have a greater ability to resist endotoxic shock than WKY. This is not related to their hypertension but is associated with an attenuated inflammatory response to LPS.

Effects of insulin-like growth factor 1 on neutrophil and monocyte functions in normal and septic states

BACKGROUND

Insulin-like growth factor 1 (IGF-1) mediates anabolic actions in catabolic states and also influences the immune system. Endogenous IGF-1 production is suppressed in sepsis; replacement therapy is therefore a natural approach to obtain the protein anabolic and potentially immune-stimulating effects of IGF-1.

METHODS

Twenty-two piglets were randomized to three groups: an IGF-1 group (n = 8) receiving a continuous infusion of 1.3 mg/h of IGF-1, a nontreated septic control group (n = 8), and a nonseptic control group (n = 6) receiving saline. Phagocytosis and respiratory burst in porcine neutrophils were evaluated by flow cytometry (FCM); tumor necrosis factor (TNF) levels were measured in serum during the septic period. In addition, human neutrophils and monocytes were primed in vitro with IGF-1 and subsequently were stimulated with phorbol myristate acetate (PMA) or Escherichia coli; phagocytosis and respiratory burst were evaluated by FCM.

RESULTS

Under nonseptic conditions, pretreatment with IGF-1 suppressed the ability of neutrophils to ingest bacteria (ie, the level of phagocytosis) 43.4% +/- 2.7% (IGF-1-treated) vs 55.8% +/- 3.4% (nontreated septic controls) and 57.3% +/- 3.34% (nonseptic controls) (p = .01). When challenged by live E. coli infusion, phagocytosis increased in the IGF-1 group to the levels of the nontreated group. The respiratory burst showed a convincing priming effect of IGF-1. After 4 hours of sepsis, the mean fluorescence intensity was 63.1 +/- 6.9 in the IGF-1 group and 40.7 +/- 3.0 in nontreated septic controls. The serum levels of TNF-alpha in the nontreated septic control group were twice those in the IGF-1-treated group, ie, 65.7 +/- 13.1 pg/mL in the nontreated septic controls and 31.5 +/- 7.5 pg/mL in the IGF-1 group (p = .03). In vitro priming of human neutrophils and monocytes with IGF-1 and subsequent stimulation with PMA or E. coli demonstrated that IGF-1 enhanced both phagocytosis and respiratory burst.

CONCLUSIONS

IGF-1 serves as a priming agent for biologic functions of leukocytes.

The influence of growth hormone on tumour necrosis factor and neutrophil leukocyte function in sepsis

The aim of this study was to assess the influence of growth hormone (GH) in sepsis on the immune system represented by the circulating TNF-levels and the neutrophil leukocytes phagocytic capacity and respiratory burst, 22 piglets were randomized to 3 groups; pretreatment with GH (16 i.u.) before sepsis (n = 8), non-treated septic controls (n = 8), and non-septic controls (n = 6). Sepsis was induced by a standardized infusion of live E. coli. TNF was measured by a cytotoxic bioassay, while neutrophil function tests were carried out by flowcytometric assays. In brief, phagocytosis was evaluated by the neutrophils' ability to ingest FITC-labelled (fluorescein isothiocyanate) E. coli and intracellular release of oxygen metabolites was detected by the oxidation of 2',7'-dichlorofluorescin (DCFH) to the fluorescent 2',7'-dichlorofluorescein (DCF). Our data show a suppression of phagocytosis in the GH-treated group before sepsis; however, when challenged with Gram-negative bacteria, the phagocytic capacity was similar to that of the non-treated animals. The serum levels of TNF in the non-treated septic control group were twice the levels of those in the GH-treated group, 65.7 pg/ml (septic controls) vs 32.8 pg/ml (GH). Pretreatment with a single dose of GH few hours prior to sepsis does not seem to entail any further imbalance of the neutrophil function in sepsis. Lowering of the circulating TNF-levels is a presumptive favourable effect of GH in sepsis.

Glutamine supplementation maintains intramuscular glutamine concentrations and normalizes lymphocyte function in infected early weaned pigs

Numerous studies in humans and rats have shown that glutamine supplementation during stressful conditions has favorable outcomes. However, the requirements for glutamine during weaning are unknown. Thus, the effects of glutamine supplementation in healthy and infected weaned pigs were investigated. At 21 d of age, pigs were weaned to an elemental diet supplemented with glutamine (+Gln) or an isonitrogenous diet containing nonessential amino acids (-Gln). At 26 d of age, pigs were intraperitoneally injected with Escherichia coli (+Ecoli) or buffered saline (-Ecoli) and killed at 28 d of age. Infection decreased (P < 0.05) plasma and intramuscular glutamine concentrations, but infected pigs that received +Gln diets had higher intramuscular glutamine levels than those that received -Gln diets. Infected pigs had elevated (P < 0.05) total leukocyte counts, and blood lymphocyte responses ([3H]-thymidine incorporation) to a mixture of phorbol myristate acetate and ionomycin were reduced. White blood cell counts were greater (P < 0.05) in +Gln than -Gln pigs. The peak responses to concanavalin A (Con A) by lymphocytes of +Ecoli+Gln pigs were greater (P < 0.05) than those of +Ecoli-Gln pigs and not different than those of noninfected pigs. Hence, glutamine supplementation maintained muscular glutamine concentrations and normalized lymphocyte function in infected pigs.

Cytokines in stored red blood cell concentrates: promoters of systemic inflammation and simulators of acute transfusion reactions?

BACKGROUND

The cytokine network has important implications for the systemic inflammatory and metabolic response in trauma and infection. Cytokines exogenously administered to traumatized and infected patients may have implications for the trauma response in these patients. The main objective of this study was to characterize red blood cell concentrates (RBCs) with regard to cytokine content.

METHODS

We investigated the concentrations of tumor necrosis factor alpha (TNF), interleukin-1 beta (IL-1), interleukin-6 (IL-6) and interleukin-8 (IL-8) in sixteen units of RBCs stored at +4 degrees C during 40 days. Samples from RBCs were taken every tenth day. Healthy volunteers were used as controls.

RESULTS

IL-1 and IL-8 in RBCs were increased compared to controls, P < 0.01 - P < 0.001 and TNF in RBCs were increased on days 1 and 40 compared to controls, P < 0.05. During storage TNF was highest on day 1, 69 (< 3-1060) pg/ml, median (range). IL-1 concentrations increased during the period of storage from 5 (< 2 - 205) pg/ml to 174 (< 2 - 2180) pg/ml, P < 0.01. IL-6 was 6 (< 2 - 210) pg/ml on day 1 and did not change over the period of storage. IL-8 was highest on day 40, 164 (15 - 790) pg/ml and compared to day 1 the concentrations were increased on day 10 and day 40, P < 0.05 for both comparisons.

CONCLUSIONS

The results indicate the presence of TNF, IL-1, IL-6 and IL-8 in stored RBCs, though there was a great variability over the period of storage and between units of RBCs. In some samples of RBCs the content of cytokines reached levels that may be anticipated to contribute to systemic inflammation and the symptomatology of acute transfusion reactions.

Prestorage versus bedside white blood cell filtration of red blood cell concentrates: effects on the content of cytokines and soluble tumor necrosis factor receptors

BACKGROUND

The cytokine network has important implications for the systemic inflammatory and metabolic response in trauma and infection. The objective of this study was to investigate the influence of white blood cell (WBC) filtration on the cytokine content in red blood cell concentrates (RBCs).

STUDY DESIGN AND METHODS

Tumor necrosis factor-alpha (TNF), interleukin-1-beta (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), and soluble TNF receptors I and II (sTNF-RI, sTNF-RII) were investigated in filtered and nonfiltered RBCs during storage. After 40 days of storage the originally nonfiltered units were filtered.

RESULTS

On day 1 prestorage filtered RBCs had lower concentrations of WBCs (p < 0.001), TNF (p < 0.01), sTNF-RI (p < 0.01) and sTNF-RII (p < 0.05) compared to nonfiltered units. IL-1 concentrations increased from day 1 to day 40 (p < 0.05) in nonfiltered RBCs and were higher in nonfiltered units compared to prestorage filtered ones on day 40 (p < 0.05). An increase of IL-8 was found in nonfiltered RBCs as well as prestorage filtered units from day 1 to day 40 (p < 0.05) but the concentrations of IL-8 were higher in nonfiltered units on day 40 compared to prestorage filtered units (p < 0.05). Filtration at the end of the 40-day storage period had no influence on the concentrations of cytokines and soluble TNF receptors.

CONCLUSION

The present results suggest that prestorage WBC filtration may be more efficient in reducing the cytokine content of RBCs compared to filtration at the the end of the storage period. The clinical impact of passive transfer of components of the cytokine network via RBCs, e.g., in critically ill patients, is however unclear and needs further investigations.

Toward a theory regarding the pathogenesis of the systemic inflammatory response syndrome: what we do and do not know about cytokine regulation

OBJECTIVES

The systemic inflammatory response syndrome (SIRS) is the massive inflammatory reaction resulting from systemic mediator release that may lead to multiple organ dysfunction. The objective of this review article is to analyze the roles of cytokines, cytokine production, and the relationship of cytokine production to the development of SIRS.

DATA SOURCES

Previous research and clinical studies related to cytokines and their relationship to SIRS.

STUDY SELECTION

From the studies reviewed, three critical questions are addressed. First, what is the definition of increased cytokine concentrations? Second, what other systemic illnesses besides sepsis can alter cytokine concentrations? Third, what are the right cytokines to measure?

DATA SYNTHESIS

This article postulates a three-stage development of SIRS, in which stage 1 is a local production of cytokines in response to an injury or infection. Stage 2 is the protective release of a small amount of cytokines into the body's circulation. Stage 3 is the massive systemic reaction where cytokines turn destructive by compromising the integrity of the capillary walls and flooding end organs.

CONCLUSIONS

While cytokines are generally viewed as a destructive development in the patient that generally leads to multiple organ dysfunction, cytokines also protect the body when localized. It will be necessary to study the positive effects of cytokines while also studying their role in causing SIRS. It will also be important to investigate the relationship between cytokines and their blockers in SIRS.

Differential alterations in plasma colony-stimulating factor concentrations in meningococcaemia

To determine whether circulating levels of any of the colony-stimulating factors (CSF) might contribute to the host response in severe sepsis, plasma concentrations of granulocyte CSF (G-CSF), granulocyte-macrophage CSF (GM-CSF), and macrophage CSF (M-CSF) were measured by immunoassays in 20 subjects with meningococcaemia, a bloodstream infection caused by Neisseria meningitidis, that has proven to be a valuable model to study the responses of other inflammatory mediators during sepsis and septic shock in humans. Plasma G-CSF concentrations were transiently elevated in most subjects during the early phase of meningococcaemia, and were higher in subjects with septic shock (mean +/- s.d. = 165 +/- 142 ng/ml, n = 9) compared with those who remained normotensive (mean +/- s.d. = 7 +/- 2 ng/ml, n = 10) (P < 0.05). Peak plasma G-CSF concentrations > 10 ng/ml were associated with the development of septic shock (P < 0.01), disseminated intravascular coagulation (P < 0.01), fulminant infection (P < 0.05), and a fatal outcome (P < 0.01). Plasma GM-CSF concentrations > 1 ng/ml were briefly present in subjects with life-threatening septic shock (1-15 ng/ml, n = 5), and were strongly associated with fulminant meningococcaemia (P < 0.01). Plasma M-CSF concentrations were marginally elevated in all subjects, but were not associated with complications related to or arising from sepsis-induced organ injury. This study demonstrates that plasma levels of G-CSF, GM-CSF and M-CSF show very different responses during meningococcaemia, changes which presumably reflect the different roles played by these mediators in sepsis and, potentially, in septic shock.

Cytokine and coagulation characteristics of retrieved blood after arthroplasty

OBJECTIVES

To investigate cytokine and coagulation/fibrinolysis characteristics in blood retrieved from wounds using an autotransfusion system, and to compare the cytokine pattern in the retrieved blood with those in the systemic circulation and in the initial portion of drainage blood from the wound.

DESIGN

Prospective controlled clinical study.

SETTING

The postoperative ward of a University hospital.

PATIENTS AND PARTICIPANTS

Blood retrieval was performed over a period of 4-6 h on patients who had just undergone arthroplasty (nine hips, one knee). In five other cases involving hip arthroplasties, the initial portion of drainage blood was studied.

MEASUREMENTS AND RESULTS

Coagulation/fibrinolysis parameters were analyzed in blood retrieved using the Stryker Consta Vac system. Concentrations of tumor necrosis factor alpha (TNF), interleukin-1 beta (IL-1) and interleukin-6 (IL-6) were analyzed in the retrieved blood, in the systemic circulation of the patients at the beginning and at the end of blood retrieval and in the initial portion of drainage blood from the surgical area. In the retrieved blood, the activities of thrombin, kallikrein and plasmin were increased, antithrombin and free protein S were decreased, and in all samples IL-6 was >1000 pg/ml. Postoperative plasma concentrations of IL-6 rose from a median value of 0 to 116 pg/ml (p <0.01). Four patients had circulating TNF concentrations (range: <15-50 pg/ml). Plasma IL-1 was not detected. TNF and IL-1 were detected in all samples of initial blood from the surgical area and IL-6 in one sample.

CONCLUSION

Hypercoagulability and high concentrations of IL-6 were present in the retrieved blood. The cytokine pattern in the initial portion of blood from the surgical area differed from those in the retrieved blood and in the systemic circulation.

Polymorphonuclear leucocyte dysregulation in patients with gram-negative septicaemia assessed by flow cytometry

Flow cytometry was used to study phagocytic function and release of reactive oxygen intermediates (ROI) following phagocytosis by granulocytes in 14 patients (six female, eight male) with gram-negative septicaemia prior to, during, and after therapy compared with a group of healthy controls. Phagocytic capacity was assessed by measuring uptake of fluorescein isothiocyanate (FITC)-labelled bacteria. Reactive oxygen generation after phagocytosis was measured by the quantification of dihydrorhodamine 123 converted to rhodamine 123 intracellulary. Compared with results in healthy controls granulocytes of septicaemic patients exhibited a decreased capacity to phagocytize Escherichia coli and to generate reactive oxygen products. Both phagocytosis and ROI production increased after initiation of therapy and normalized within 7 days of treatment. The results suggest that granulocytes do not only participate in, but are also a target of, the septic host inflammatory response.

Septic shock: pathogenesis and treatment

Septic shock is the host's inflammatory response to infection. There are multiple endogenous mediators responsible for the pathogenesis of septic shock. Cytokines, nitric oxide and prostaglandins are some of the major mediators. The term sepsis syndrome allows for an earlier diagnosis and treatment. Management of septic shock is focused in maintaining hemodynamic stability and an adequate oxygen delivery and utilization. Careful attention to each organ-system is of paramount importance to prevent complications and improve outcome. Experimental therapies to modulate the inflammatory response are promising.