Supplemental immune globulins in sepsis

Intravenous immunoglobulin-induced neutrophil apoptosis in the lung during murine endotoxemia

BACKGROUND

The pathophysiologic features of acute respiratory distress syndrome (ARDS) are attributed to neutrophil accumulation and over-activation. Low blood immunoglobulin G concentrations in septic shock patients are associated with higher risk of developing ARDS. This study showed the effects of intravenous immunoglobulin (IVIg) on neutrophil apoptosis and accumulation in the lung during murine endotoxemia.

METHODS

Male C57BL/6J mice were injected with saline or 7 mg/kg of lipopolysaccharide (LPS), and 3 h later also were injected with saline, IVIg 300 mg/kg, or IVIg 1000 mg/kg intraperitoneally. At 12 h after LPS injection, mice were sacrificed and peripheral blood and lungs were collected. The lung messenger ribonucleic acid expression (tumor necrosis factor-α [TNF-α], inducible nitric oxide synthase [iNOS], and intercellular adhesion molecule-1 [ICAM-1]) was determined using quantitative realtime reverse transcriptase-polymerase chain reaction. Lungs were immersed in 4% paraformaldehyde and then embedded in paraffin. Tissue slices were prepared and stained with naphthol AS-D chloroacetate esterase to detect neutrophils. The numbers of neutrophils (characterized by the segment number of their nuclei) were counted. Peripheral neutrophil apoptosis was detected by annexin V using flow cytometry and lung neutrophil apoptosis was detected by cleaved caspase-3 using immunohistochemistry.

RESULTS

The survival rates of the saline group, LPS group, and IVIg group were all 100%. Apoptosis of peripheral blood neutrophils was inhibited by LPS. Neutrophil accumulation in the lung was decreased by both IVIg 300 mg/kg and 1000 mg/kg. Segmented neutrophils were reduced by IVIg during endotoxemia. However, IVIg 300 mg/kg and 1000 mg/kg had no influence on the lung messenger ribonucleic acid expression of TNF-α, iNOS, or ICAM-1. Cleaved-caspase-3-positive neutrophils were increased in the IVIg 300 mg/kg group during endotoxemia. The 1000 mg/kg IVIG dose reduced the number of segmented neutrophils, but did not induce cleaved-caspase 3-positive neutrophils.

CONCLUSION

A therapeutic IVIg dose can attenuate neutrophil accumulation and regulate neutrophil apoptosis in the lung during endotoxemia. It is possible that the pathways by which IVIG induces neutrophil apoptosis may differ depending on the IVIg concentration.

Differential modulation of cord blood and peripheral blood monocytes by intravenous immunoglobulin

BACKGROUND

Immunoglobulins (IVIG) have been shown to be useful in adults suffering from sepsis. In contrast, prophylactic and curative IVIG trials failed to show beneficial effects in neonates. We tested the hypothesis that IVIG, have different effects on monocytes from cord blood (CBMO) and peripheral blood monocytes from adults (PBMO) with respect to survival, phenotype, and function.

METHODS

Mononuclear cells, or purified monocytes, were cultured in 5% human serum, incubated with polyvalent IVIG (1 mg/ml), stimulated with green fluorescent protein (GFP)-labeled Escherichia coli (E. Coli-GFP), Interferon-γ (IFN-γ, 50 U/ml), or the T cell mitogen anti-CD3 monoclonal antibody, αCD3-mAb, (5 μg/ml). Phagocytosis, phenotype, T cell proliferation, and apoptosis were assessed by flow cytometry.

RESULTS

IVIG enhanced phagocytosis in PBMO or CBMO when infected directly after isolation, while IVIG had no effect on monocytes cultured 48 h prior to infection. In contrast to PBMO, IVIG inhibited the IFN-γ mediated up-regulation of CD80, CD86, and HLA-DR on CBMO. In the presence of IVIG, stimulation with αCD3 in cord blood enhanced deletion, inhibited blast formation and CD28 up-regulation of T cells (P < 0.05 vs. T cells from adults). IVIG induced monocyte apoptosis, associated with up-regulation of Annexin V and loss of nuclear DNA, which was more pronounced in CBMO. Although phagocytosis induced cell death (PICD) was lower in CBMO (P < 0.05 vs. PBMO), the addition of IVIG enhanced PICD levels of CBMO to the extent of PBMO.

CONCLUSIONS

IVIG inhibits co-stimulatory receptors and functions of CBMO and induces apoptosis. These findings may be of clinical relevance for the failure of IVIG benefit in neonatal sepsis.

Polyclonal intravenous immunoglobulin for the prophylaxis and treatment of infection in critically ill adults

Infection is a major cause of morbidity and mortality in critically ill patients. Despite advances in technology, its mortality rate has changed minimally over the past two decades, and new therapies are needed. Polyclonal intravenous immunoglobulin (IVIG) has been investigated both as a preventive and a treatment modality for sepsis and septic shock in critically ill adult patients. Prophylaxis with IVIG has been shown to reduce significantly the incidence of infection, particularly pneumonia, in selected postsurgical intensive care patients. However, it does not reduce mortality. The risk-benefit and cost effectiveness of this therapeutic intervention have not been determined, and its routine use is therefore not recommended. Treatment with IVIG has been shown in a number of small trials and a meta-analysis to reduce dramatically sepsis and septic shock mortality. However, a large, unpublished randomized trial has apparently shown no mortality benefit with this therapy. Despite limited evidence, IVIG has become the standard of care for the management of group A streptococcal toxic shock syndrome. At present, clinical equipoise exists for the use of IVIG in the treatment of sepsis and septic shock, and further study is needed.

Relationship between the timing of administration of IgM and IgA enriched immunoglobulins in patients with severe sepsis and septic shock and the outcome: a retrospective analysis

PURPOSE

Because the use of IgM and IgA enriched polyclonal intravenous immunoglobulins (eIg) is a standard of care in critically ill patients admitted to our intensive care unit (ICU) with the diagnosis of severe sepsis or septic shock, we investigated if the delay from the onset of severe sepsis and septic shock and their administration could influence the outcome.

MATERIALS AND METHODS

The medical records of all patients with severe sepsis or septic shock admitted to our ICU from July 2004 through October 2009 and treated with eIg (Pentaglobin®; Biotest, Dreieich, Germany) were retrospectively examined.

RESULTS

A total of 129 adult patients with severe sepsis or septic shock were considered eligible. Thirty-two percent of patients died during the ICU stay. Survivors were given eIg significantly earlier than nonsurvivors (23 vs 63 hours, P < .05). The delay in the administration of eIg and the Simplified Acute Physiology Score II were the only variables that entered stepwise a propensity score-adjusted logistic model. The delay in the administration of eIg was a significant predictor of the odds of dying during the ICU stay (odds ratio for 1 hour of delay, 1.007; P < .01; 99% confidence interval from 1.001 to 1.010) and proved to be independent from the Simplified Acute Physiology Score II and other variables.

CONCLUSIONS

The efficacy of eIg, being maximal in early phases of severe sepsis and/or septic shock, is probably time dependent.

High-dose intravenous immunoglobulin G improves systemic inflammation in a rat model of CLP-induced sepsis

OBJECTIVE

Intravenous immunoglobulin therapy has been proposed as an advanced treatment for sepsis. Yet, its benefit remains unclear and the mechanism of action is poorly understood. One key mediator in the development of sepsis is high mobility group box 1 (HMGB1). Therefore, we examined the serum and lung tissue levels of HMGB1 in a rat model of sepsis.

DESIGN AND SETTING

Prospective controlled animal study in a university laboratory.

MATERIALS

Rats received either cecal ligation and puncture-induced sepsis or had additional intravenous immunoglobulin treatment in boluses of 100, 300, or 1,000 mg/kg.

MEASUREMENTS AND RESULTS

After induction of sepsis and respective treatment conditions, histopathology, wet/dry weight ratios, and signaling molecules were examined in pulmonary tissue. Serum and pulmonary levels of cytokine and HMGB1 were measured. High dose intravenous immunoglobulin (1,000 mg/kg)-treated animals demonstrated significantly improved survival and pulmonary histopathology compared to the control rats. Serum and pulmonary HMGB1 levels were lower over time among intravenous immunoglobulin-treated animals. Furthermore, administration of intravenous immunoglobulin resulted in inhibition of NF-kappaB activity.

CONCLUSIONS

High-dose intravenous immunoglobulin decreased the mortality and pulmonary pathology in a rat model of sepsis. A significant reduction in HMGB1 levels was also observed, which may be mediated by inhibition of inflammation and NF-kappaB.

DESCRIPTOR

23. Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI): experimental models.

Immunoglobulin M-enriched human intravenous immunoglobulins reduce leukocyte-endothelial cell interactions and attenuate microvascular perfusion failure in normotensive endotoxemia

Clinical studies indicate potential differences in the efficacy of immunoglobulin (Ig) preparations in patients with sepsis. A recent meta-analysis showed improved survival rates with IgM-enriched Igs. It was the objective of the present study to characterize microcirculatory actions of different clinically used Ig preparations in a rodent endotoxin model by intravital microscopy. Male Syrian golden hamsters 6 to 8 weeks old with a body weight of 60 to 80 g were investigated by intravital fluorescence microscopy. Endotoxemia was induced by administration of 2 mg/kg (i.v.) endotoxin (LPS, Escherichia coli). Two different Ig preparations containing IgM, IgA, and IgG (intravenous IgM group; n = 6; 5 mL Pentaglobin/kg body weight, i.v.) or exclusively IgG (intravenous IgG group; n = 5; 5 mL Flebogamma/kg body weight, i.v.) were applied 5 min before LPS. Saline-treated endotoxemic animals served as controls (control; n = 8). In controls, LPS induced massive leukocyte-endothelial cell interactions, pronounced microvascular leakage, a decrease of systemic platelet count, and distinct capillary perfusion failure (P < 0.05). Both intravenous IgM and IgG reduced venular leakage (P< 0.05) and ameliorated the decrease in platelet count (P < 0.05). Of interest, intravenous IgM was capable of significantly (P< 0.05) reducing leukocyte adhesion in venules. This was associated with normalization of capillary perfusion at 24 h of endotoxemia, whereas intravenous IgG could not prevent LPS-mediated microvascular perfusion failure. We demonstrate that IgM-enriched Igs are superior to IgG alone in attenuating LPS-induced leukocytic inflammation and microcirculatory dysfunction. Our findings can explain better efficacy of IgM-enriched Igs in patients with severe sepsis.

Restoration of Natural IgM Production from Liver B Cells by Exogenous IL-18 Improves the Survival of Burn-Injured Mice Infected withPseudomonas aeruginosa

Pseudomonas aeruginosa is the most common bacterium of postburn infection. In the present study we investigated the immune mechanism of susceptibility to this type of postburn infection and also examined the efficacy of IL-18 treatment. C57BL/6 mice were challenged with P. aeruginosa on day 7 after burn injury. Although the burn-injured mice showed a poor survival rate after bacterial challenge, they retained their IFN-gamma production. The burned mice showed lower serum IgM levels and a poor IgM response following P. aeruginosa challenge in comparison with the sham mice, whereas IL-18 treatment after burn injury (alternate day injections for 1 wk) greatly improved the serum IgM levels, which are P. aeruginosa-independent natural IgM before bacterial challenge, thereby increasing the survival rate after the challenge. IL-18 treatment also induced specific IgM to P. aeruginosa in the sera 5 days after bacterial challenge in the burned mice. Interestingly, CD43(+)CD5(-)CD23(-)B220(dim) cells, namely B-1b cells, increased in the liver after the IL-18 treatment and were found to actively produce IgM in vitro without any additional stimulation. Furthermore, the IL-18 treatment up-regulated the neutrophil count and the C3a levels in the blood as a result of the increased IgM level, which may thus play a critical role in the opsonization and elimination of any invading bacteria. IL-18 treatment for the burned mice and their resultant natural IgM production were thus found to strengthen the host defense against P. aeruginosa infection.

Anti-clumping factor A immunoglobulin reduces the duration of methicillin-resistant Staphylococcus aureus bacteremia in an experimental model of infective endocarditis

SA-IGIV is a human polyclonal immunoglobulin containing elevated levels of antibodies specific for the fibrinogen-binding MSCRAMM protein clumping factor A (ClfA). In vitro, SA-IGIV specifically recognized ClfA that was expressed on the surface of Staphylococcus aureus and inhibited bacterial adherence to immobilized human fibrinogen by >95%. Moreover, SA-IGIV efficiently opsonized ClfA-coated fluorescent beads and facilitated phagocytosis by human polymorphonuclear leukocytes. To determine its potential therapeutic efficacy, SA-IGIV was evaluated in combination with vancomycin in a rabbit model of catheter-induced aortic valve infective endocarditis (IE) caused by methicillin-resistant S. aureus (MRSA). The combination therapy was more effective than vancomycin alone in sterilizing all valvular vegetations when used therapeutically during early (12-h) IE. The combination therapy resulted in clearance of bacteremia that was significantly faster than that of vancomycin alone in animals with well-established (24-h) IE. Therefore, in both early and well-established MRSA IE, the addition of SA-IGIV to a standard antibiotic regimen (vancomycin) increased bacterial clearance from the bloodstream and/or vegetations.

Plasma exchange as rescue therapy in multiple organ failure including acute renal failure

OBJECTIVE

To describe the outcome of using a rescue therapy including plasma exchange given to patients with a progressive acute disseminated intravascular coagulation and multiple organ dysfunction syndrome.

STUDY DESIGN

Retrospective study.

SETTING

University and county hospital.

PATIENTS

Included were 76 consecutive patients (41 men and 35 women) treated with plasma exchange as rescue therapy besides optimal conventional therapy during a progressive course of disseminated intravascular coagulation and multiple organ dysfunction syndrome, including acute renal failure. Of the 76 patients, 66% needed dialysis. The distribution was hemodialysis in 76%, continuous arteriovenous hemofiltration in 36%, continuous venovenous hemodialysis in 12%, and peritoneal dialysis in 24%. The median organ-failure score was 5 (range, 1-6). Seventy-two percent required mechanical ventilation; septic shock was present in 88%. The median septic shock score was 4 (range, 2-4). Nine patients had another reason than sepsis for the multiple organ dysfunction syndrome.

INTERVENTION

Plasma exchange (centrifugation technique) was performed until disseminated intravascular coagulation was reversed (median, two times; range, 1-14). Besides antibiotics and fluid administration, most patients received heparin or low molecular weight heparin (77%), steroids (87%), and inotropes (88%). More than one vasoactive drug was used in 57% of the patients.

MEASUREMENTS AND MAIN RESULTS

Eighty-two percent of the patients survived and could leave the hospital. The previously observed survival rates by others for this category of patients would be <20%, and thus, the outcome in this study is significantly better.

CONCLUSION

Plasma exchange using plasma as replacement may, in addition to conventional intensive care, help to reverse severe progressive disseminated intravascular coagulation and multiple organ dysfunction syndrome and improve survival.

Innovative therapies for sepsis

Sepsis and septic shock continue to be a major cause of morbidity and mortality. Despite numerous advances in the supportive care of patients with sepsis, the overall mortality has changed little in the past 20 years. Many innovative therapies have been attempted in the field of sepsis, primarily aimed at stopping the cycle of cytokine activation which is part of the systemic inflammatory response. Therapies have also targeted other molecular mediators of inflammation and coagulation. Despite encouraging preliminary preclinical results, most of the early trials in sepsis research have failed to offer hope of improving survival with the use of these innovative therapies. Postulated reasons for the failure of clinical trials include the disparity between animal models and clinical reality, the heterogeneous nature of patient populations and sepsis, and the complexity of the inflammatory cascade. On a more hopeful note, three recent trials assessing corticosteroids, anti-tumour necrosis factor strategy and drotrecogin alfa (rhAPC), respectively, have proclaimed positive results. However, only the drotrecogin alfa trial has been peer reviewed and published.

Pathophysiology of septic shock and multiple organ dysfunction syndrome and various therapeutic approaches with special emphasis on immunoglobulins

The pathophysiology of sepsis and septic shock is dominated by an imbalance of pro- and antiinflammatory mediators produced by toxin-activated inflammatory cells. Both the overshooting of proinflammatory mediators as well as the development of immune paralysis are deleterious to the patient. Available therapeutic approaches with monoclonal antibodies and antagonists targeted against toxins and mediators have focused mainly on inhibition of overshooting proinflammation: the results, however, have been disappointing. Due to these disappointing results of specific antiinflammatory regimens, adjuvant treatment of sepsis and septic shock with intravenous immunoglobulins (IVIgs) has regained interest although this indication has at best been validated in part. Likely beneficial mechanisms of action may include the improvement of serum bactericidal activity due to neutralizing and opsonizing IgG and IgM antibodies as well as stimulation of phagocytosis and neutralization of bacterial endo- and exotoxins; another attractive mode of action may represent Ig-mediated modification and specific suppression of proinflammatory cytokine release from endotoxin- and superantigen-activated blood cells. For the total group of patients with sepsis and septic shock, a reduction in mortality by IVIg could not be documented; however, in the SBITS study with 653 patients included, a moderate improvement in sepsis morbidity and multiple organ dysfunction syndrome was demonstrated. In defined sepsis sub-groups, a reduction in mortality by IVIg has been seen in each small, not yet confirmed trial. Thus, IVIg is not a magic bullet of sepsis treatment, but it may reduce morbidity and thereby may be useful in the therapeutic mosaic of sepsis treatment.

Intravenous immunoglobulin for prophylaxis and therapy of sepsis

Intravenous immunoglobulins (IVIg) are widely used as prophylaxis against and as supplemental treatment of sepsis and septic shock, although this concept does not belong to the currently approved medical indications for IVIg products. A reduction in mortality by pooled IVIgGMA more than by IVIgG alone was reported in the recent Cochrane database (eight trials, 492 patients). However, the failure to reduce mortality by IVIgG in the score-based immunoglobulin treatment in sepsis study (653 patients) seriously questions whether IVIgG may reduce mortality. Patients with streptococcal toxic shock syndrome might benefit from IVIg, although it remains questionable whether large controlled trials will ever be available. Intravenous immunoglobulin prophylaxis can undoubtedly reduce the occurrence of infections-especially pneumonias-in at-risk patients. More data are necessary to ascertain whether this beneficial effect is linked with a reduction of infection-related morbidity and mortality. Ongoing studies will document whether cardiac surgery patients with escalating systemic inflammatory response syndrome or mediastinitis will benefit from IVIg. IgM-specific complement inactivation may further stimulate the discussion of IVIgGMA superiority over IVIgG.

The Presence of Superantigens and Complex Host Responses in Severe Sepsis May Need a Broad Therapeutic Approach

Patients with sepsis can progress into septic shock, disseminated intravascular coagulation, and multiorgan dysfunction syndrome. Various materials secreted by or released from microorganisms such as bacteria initiate these processes. In some bacteria, certain antigens and toxins may cause a 100-fold greater or supernormal activation of monocytes and T lymphocytes, leading to activation of the cascade systems in the host. This can explain the extremely rapid progress of the sepsis into septic shock seen in some patients. In Group A streptococci, more than 100 different toxins have been identified, about 5 of which (superantigens) cause an extremely fast immunological response. Because the toxins and antigens can activate so many different cascade systems in the host, the clinical picture is extremely complex, and little benefit is derived from therapy, which interferes with only 1 or 2 of the parameters in the patient with sepsis. Instead, reversal of the septic shock requires the removal or inhibition of several toxins or substances activating the cascade systems. A broader therapeutic approach may be the use of apheresis (plasma exchange).

Treatment of sepsis in cardiac surgery: role of immunoglobulins

Cardiopulmonary bypass (CPB) is associated with an injury that may cause pathophysiological changes such as systemic inflammatory response syndrome, multiple organ dysfunction syndrome, and mediator-induced multiorgan failure. Systemic endotoxinaemia, release of proinflammatory cytokines, and interactions between neutrophils and endothelium have been reported to correlate with a high incidence of organ dysfunction, infection and sepsis following cardiac surgery. This review discusses the dysregulation of the immune response as a major reason for the higher susceptibility to infections following cardiac surgery, various treatment strategies to reduce CPB-induced inflammation, and especially the prophylactic use of immunoglobulins in cardiac surgery.

Critical Illness Polyneuropathy

Critical illness polyneuropathy (CIP) is common among patients in intensive care units (ICUs). However, it is rarely diagnosed in patients in most ICUs, because of the lack of knowledge, difficulties in clinical assessment, and failure to perform electrophysiologic studies. Nonetheless, CIP is a significant cause of difficulty in weaning patients from the ventilator and of long-term morbidity in survivors. Although no specific treatment is available, diagnosis is important for the institution of various nonspecific treatments and for prognosis. Moreover, research is important in arriving at a better understanding of the pathophysiologic mechanisms and, hence, possible avenues of specific treatment. Thus, this chapter emphasizes the nature of critical illness and the possible pathophysiology, the clinical and electrophysiologic features, and the differential diagnosis of CIP. Nonspecific and potential specific treatments are also discussed.