A predominantly anti-inflammatory cytokine profile is associated with disease severity in meningococcal sepsis

Differences in IgG Fc Glycosylation Are Associated with Outcome of Pediatric Meningococcal Sepsis

Pediatric meningococcal sepsis often results in morbidity and/or death, especially in young children. Our understanding of the reasons why young children are more susceptible to both the meningococcal infection itself and a more fulminant course of the disease is limited. Immunoglobulin G (IgG) is involved in the adaptive immune response against meningococcal infections, and its effector functions are highly influenced by the glycan structure attached to the fragment crystallizable (Fc) region. It was hypothesized that IgG Fc glycosylation might be related to the susceptibility and severity of meningococcal sepsis. Because of this, the differences in IgG Fc glycosylation between 60 pediatric meningococcal sepsis patients admitted to the pediatric intensive care unit and 46 age-matched healthy controls were investigated, employing liquid chromatography with mass spectrometric detection of tryptic IgG glycopeptides. In addition, Fc glycosylation profiles were compared between patients with a severe outcome (death or the need for amputation) and a nonsevere outcome. Meningococcal sepsis patients under the age of 4 years showed lower IgG1 fucosylation and higher IgG1 bisection than age-matched healthy controls. This might be a direct effect of the disease; however, it can also be a reflection of previous immunologic challenges and/or a higher susceptibility of these children to develop meningococcal sepsis. Within the young patient group, levels of IgG1 hybrid-type glycans and IgG2/3 sialylation per galactose were associated with illness severity and severe outcome. Future studies in larger groups should explore whether IgG Fc glycosylation could be a reliable predictor for meningococcal sepsis outcome.

Meningococcal sepsis causes significant mortality and morbidity worldwide, especially in young children. Identification of risk factors for a more fulminant infection would help to decide on appropriate treatment strategies for the individual patients. Immunoglobulin G (IgG) plays an essential role in humoral immune responses and is involved in the adaptive immune response against meningococcal infections. Of great influence on the receptor affinity of IgG is the N-glycan on its fragment crystallizable (Fc) portion. In the present study, we analyzed IgG glycosylation during the fast development of meningococcal sepsis in children, and we were able to identify glycosylation features that are different between meningococcal sepsis patients and healthy controls. These features might be indicative of a higher susceptibility to meningococcal sepsis. In addition, we found glycosylation features in the patients that were associated with illness severity and severe disease outcome, having the potential to serve as a disease outcome predictor.

Innate immune recognition and inflammation in Neisseria meningitidis infection

Neisseria meningitidis (Nme) can cause meningitis and sepsis, diseases which are characterised by an overwhelming inflammatory response. Inflammation is triggered by host pattern recognition receptors (PRRs) which are activated by pathogen-associated molecular patterns (PAMPs). Nme contains multiple PAMPs including lipooligosaccharide, peptidoglycan, proteins and metabolites. Various classes of PRRs including Toll-like receptors, NOD-like receptors, C-type lectins, scavenger receptors, pentraxins and others are expressed by the host to respond to any given microbe. While Toll-like receptors and NOD-like receptors are pivotal in triggering inflammation, other PRRs act as modulators of inflammation or aid in functional antimicrobial responses such as phagocytosis or complement activation. This review aims to give an overview of the various Nme PAMPs reported to date, the PRRs they activate and their implications during the inflammatory response to infection.

Neisseriae internalization by epithelial cells is enhanced by TLR2 stimulation

Neisseria meningitidis (NM) is an opportunistic gram-negative human pathogen that colonizes the human nasopharyngeal epithelium. Asymptomatic carriage is common, but some meningococcal strains can invade nasopharyngeal epithelial cells and proceed to cause severe and often fatal infections. Invasion is predominantly driven by expression of bacterial virulence factors and host cell cognate receptors for bacterial recognition. Porins are among the Neisserial components involved in host cell activation and bacterial internalization processes. Similar to other virulence factors, porins present antigenic and structure variability among strains. Such sequence variability in the surface-exposed loop regions has been correlated to bacterial invasiveness and to variability in host cell responses via Toll-like receptor 2 (TLR2). Here, we examined whether TLR2 signaling by porins influences recovery of intracellular Neisseriae from epithelial cells in vitro. Our results show that TLR2 stimulation, either by the organism or exogenously, generally enhances Neisseriae internalization by epithelial cells. TLR2-driven intracellular signaling via ERK1/2, JNK and particularly NF-κB plays a role in this process. Based on these results, it is possible that expression of porin sequence variants that strongly induce TLR2 activation may be a mechanism to enhance the invasive features of pathogenic Neisseriae strains.

[Invasive meningococcal disease in Navarra in the era of a meningococcal C vaccine]

INTRODUCTION

Systematic childhood vaccination against meningococcus C has had a considerable impact on meningococcal invasive disease (MID). The aim of this study is to perform an analysis on the epidemiology, the clinical features, and the factors associated with a worse prognosis of MID, in the era of a meningococcal C vaccine.

MATERIAL AND METHODS

The study included confirmed cases of MID in children less than 15 years of age in Navarra, Spain, between 2008 and 2014. The risk of death or permanent sequelae was evaluated according to the presence of clinical features and analytical parameters at diagnosis.

RESULTS

The average annual incidence was 7.9 cases per 100,000 children, with the highest attack rate in children < 1 year. Of 53 cases analysed, 87% were due to meningococcus B. Fever (100%), rash (91%), and elevation of procalcitonin (94%) were the most frequent findings at diagnosis. Some sign of shock was observed in 70% upon arrival at the hospital. The case-fatality rate was 3.8% and 10 % survived with permanent sequelae. Glasgow coma scale < 15 (odds ratio [OR]= 9.2), seizure (OR=8.3), sepsis without meningitis (OR=9.1), thrombocytopenia (OR=30.5), and disseminated intravascular coagulation (OR= 10.9) showed a greater association with a worse prognosis.

CONCLUSION

The MID continues to be a significant cause of morbidity and mortality in children. Therefore, new advances are needed in the prevention, early diagnosis, and detection of the factors associated with poor prognosis.

Prognostic markers of meningococcal disease in children: recent advances and future challenges

Meningococcal disease is a life-threatening condition and a major cause of bacterial meningitis and sepsis worldwide. In many fatal cases, meningococcal disease is rapidly progressive and death occurs within hours of the initial symptoms. The early identification of patients at high risk of death would be useful in order to provide aggressive and more personalized clinical management with the proper level of supportive therapy required, contributing to an improvement in the survival rate and reduction in sequelae. The current study aims to review the current published literature about prognostic markers of meningococcal sepsis in children in order to elaborate conclusions and recommendations that could guide clinical practice and further research.

Crystallographic analysis of Neisseria meningitidis PorB extracellular loops potentially implicated in TLR2 recognition

Among all Neisseriae species, Neisseria meningitidis and Neisseria gonorrhoeae are the only human pathogens, causative agents of bacterial meningitis and gonorrhoea, respectively. PorB, a pan-Neisseriae trimeric porin that mediates diffusive transport of essential molecules across the bacterial outer membrane, is also known to activate host innate immunity via Toll-like receptor 2 (TLR2)-mediated signaling. The molecular mechanism of PorB binding to TLR2 is not known, but it has been hypothesized that electrostatic interactions contribute to ligand/receptor binding. Strain-specific sequence variability in the surface-exposed loops of PorB which are potentially implicated in TLR2 binding, may explain the difference in TLR2-mediated cell activation in vitro by PorB homologs from the commensal Neisseriae lactamica and the pathogen N. meningitidis. Here, we report a comparative structural analysis of PorB from N. meningitidis serogroup B strain 8765 (63% sequence homology with PorB from N. meningitidis serogroup W135) and a mutant in which amino acid substitutions in the extracellular loop 7 lead to significantly reduced TLR2-dependent activity in vitro. We observe that this mutation both alters the loop conformation and causes dramatic changes of electrostatic surface charge, both of which may affect TLR2 recognition and signaling.

Cytokine and chemokine profiles in lung tissues from fatal cases of 2009 pandemic influenza A (H1N1): role of the host immune response in pathogenesis

Pathological studies on fatal cases caused by 2009 pandemic influenza H1N1 virus (2009 pH1N1) reported extensive diffuse alveolar damage and virus infection predominantly in the lung parenchyma. However, the host immune response after severe 2009 pH1N1 infection is poorly understood. Herein, we investigated viral load, the immune response, and apoptosis in lung tissues from 50 fatal cases with 2009 pH1N1 virus infection. The results suggested that 7 of the 27 cytokines/chemokines showed remarkably high expression, including IL-1 receptor antagonist protein, IL-6, tumor necrosis factor-α, IL-8, monocyte chemoattractant protein-1, macrophage inflammatory protein 1-β, and interferon-inducible protein-10 in lung tissues of 2009 pH1N1 fatal cases. Viral load, which showed the highest level on day 7 of illness onset and persisted until day 17 of illness, was positively correlated with mRNA levels of IL-1 receptor antagonist protein, monocyte chemoattractant protein-1, macrophage inflammatory protein 1-β, interferon-inducible protein-10, and regulated on activation normal T-cell expressed and secreted. Apoptosis was evident in lung tissues stained by the TUNEL assay. Decreased Fas and elevated FasL mRNA levels were present in lung tissues, and cleaved caspase-3 was frequently seen in pneumocytes, submucosal glands, and lymphoid tissues. The pathogenesis of the 2009 pH1N1 virus infection is associated with viral replication and production of proinflammatory mediators. FasL and caspase-3 are involved in the pathway of 2009 pH1N1 virus-induced apoptosis in lung tissues, and the disequilibrium between the Fas and FasL level in lung tissues could contribute to delayed clearance of the virus and subsequent pathological damages.

Inflammatory cytokine measurement quickly discriminates gram-negative from gram-positive bacteremia in pediatric hematology/oncology patients with septic shock

PURPOSE

We performed a prospective study to evaluate the ability of inflammatory cytokines in discriminating gram-negative from gram-positive bacteremia in septic shock.

METHODS

During the study period, the serum inflammatory cytokine levels were measured at the onset of septic shock by flow cytometry in pediatric hematology/oncology patients with septic shock.

RESULTS

One hundred episodes of septic shock were enrolled. Of 97 episodes of monomicrobial infection, 73.2 % were caused by gram-negative bacteremia and 26.8 % by gram-positive bacteremia. Interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α were closely related to the pediatric index of mortality 2 (PIM2) score and mortality. However, although the PIM2 score and mortality were comparable, the IL-6, IL-10, and TNF-α levels were significantly higher in patients with gram-negative bacteremia (GNB) than those with gram-positive bacteremia (median levels, pg/mL: IL-6: 784.1 vs. 254.4, P = 0.001; IL-10: 192.2 vs. 19.7, P < 0.001; TNF-α: 4.2 vs. 2.0, P < 0.001). Of the three cytokines, IL-10 was the most useful biomarker for GNB prediction in the derivation cohort and a cutoff value of 50 pg/mL showed a sensitivity of 70.8 % and a specificity of 80.0 %, with a positive predictive value of 89.5 %. When this cutoff value was applied to the validation cohort, the sensitivity, specificity, and positive predictive value were 80.9, 75.0, and 90.5 %, respectively.

CONCLUSIONS

Flow cytometry-based inflammatory cytokine measurement is a helpful adjuvant approach for early and quick discrimination of gram-negative from gram-positive bacteremia in pediatric hematology/oncology patients with septic shock which might be useful for evaluating the severity of shock and the selection and/or timely withdrawal or switch of antibiotics.

The amino acid sequence of Neisseria lactamica PorB surface-exposed loops influences Toll-like receptor 2-dependent cell activation

Toll-like receptors (TLRs) play a major role in host mucosal and systemic defense mechanisms by recognizing a diverse array of conserved pathogen-associated molecular patterns (PAMPs). TLR2, with TLR1 and TLR6, recognizes structurally diverse bacterial products such as lipidated factors (lipoproteins and peptidoglycans) and nonlipidated proteins, i.e., bacterial porins. PorB is a pan-neisserial porin expressed regardless of organisms' pathogenicity. However, commensal Neisseria lactamica organisms and purified N. lactamica PorB (published elsewhere as Nlac PorB) induce TLR2-dependent proinflammatory responses of lower magnitude than N. meningitidis organisms and N. meningitidis PorB (published elsewhere as Nme PorB). Both PorB types bind to TLR2 in vitro but with different apparent specificities. The structural and molecular details of PorB-TLR2 interaction are only beginning to be unraveled and may be due to electrostatic attraction. PorB molecules have significant strain-specific sequence variability within surface-exposed regions (loops) putatively involved in TLR2 interaction. By constructing chimeric recombinant PorB loop mutants in which surface-exposed loop residues have been switched between N. lactamica PorB and N. meningitidis PorB, we identified residues in loop 5 and loop 7 that influence TLR2-dependent cell activation using HEK cells and BEAS-2B cells. These loops are not uniquely responsible for PorB interaction with TLR2, but NF-κB and MAP kinases signaling downstream of TLR2 recognition are likely influenced by a hypothetical "TLR2-binding signature" within the sequence of PorB surface-exposed loops. Consistent with the effect of purified PorB in vitro, a chimeric N. meningitidis strain expressing N. lactamica PorB induces lower levels of interleukin 8 (IL-8) secretion than wild-type N. meningitidis, suggesting a role for PorB in induction of host cell activation by whole bacteria.

Treatment with TNF-alpha and IFN-gamma alters the activation of SER/THR protein kinases and the metabolic response to IGF-I in mouse c2c12 myogenic cells

The aim of this study was to compare the effects of TNF-alpha, IL-1beta and IFN-gamma on the activation of protein kinase B (PKB), p70(S6k), mitogen-activated protein kinase (MAPK) and p90( rsk ), and on IGF-I-stimulated glucose uptake and protein synthesis in mouse C2C12 myotubes. 100 nmol/l IGF-I stimulated glucose uptake in C2C12 myotubes by 198.1% and 10 ng/ml TNF-alpha abolished this effect. Glucose uptake in cells differentiated in the presence of 10 ng/ml IFN-gamma increased by 167.2% but did not undergo significant further modification upon the addition of IGF-I. IGF-I increased the rate of protein synthesis by 249.8%. Neither TNF-alpha nor IFN-gamma influenced basal protein synthesis, but both cytokines prevented the IGF-I effect. 10 ng/ml IL-1beta did not modify either the basal or IGF-I-dependent glucose uptake and protein synthesis. With the exception of TNF-alpha causing an 18% decrease in the level of PKB protein, the cellular levels of PKB, p70(S6k), p42(MAPK), p44(MAPK) and p90( rsk ) were not affected by the cytokines. IGF-I caused the phosphorylation of PKB (an approximate 8-fold increase above the basal value after 40 min of IGF-I treatment), p42(MAPK) (a 2.81-fold increase after 50 min), and the activation of p70(S6k) and p90( rsk ), manifesting as gel mobility retardation. In cells differentiated in the presence of TNF-alpha or IFN-gamma, this IGF-I-mediated PKB and p70(S6k) phosphorylation was significantly diminished, and the increase in p42(MAPK) and p90( rsk ) phosphorylation was prevented. The basal p42(MAPK) phosphorylation in C2C12 cells treated with IFN-gamma was high and comparable with the activation of this kinase by IGF-I. Pretreatment of myogenic cells with IL-1beta did not modify the IGF-I-stimulated phosphorylation of PKB, p70(S6k), p42(MAPK) and p90( rsk ).

IN CONCLUSION

i) TNF-alpha and IFN-gamma, but not IL-1beta, if present in the extracellular environment during C2C12 myoblast differentiation, prevent the stimulatory action of IGF-I on protein synthesis. ii) TNF-alpha- and IFN-gamma-induced IGF-I resistance of protein synthesis could be associated with the decreased phosphorylation of PKB and p70(S6k). iii) The activation of glucose uptake in C2C12 myogenic cells treated with IFN-gamma is PKB independent. iv) The similar effects of TNF-alpha and IFN-gamma on the signalling and action of IGF-I on protein synthesis in myogenic cells could suggest the involvement of both of these cytokines in protein loss in skeletal muscle.

Serial cytokine levels in patients with severe sepsis

OBJECTIVE AND DESIGN

The serial or dynamic changes of cytokine levels in severely septic patients, between shock and no shock, survivors and non-survivors are still unclear.

METHODS

Seventy-six patients with severe sepsis were enrolled to our study. Plasma levels of interferon-gamma, interleukin (IL)-6, IL-10, IL-12 and transforming growth factor-beta1 from day 1 to day 7 were determined.

RESULTS

IL-6 level in non-survivors was higher than that in survivors on day 1. IL-10 level in non-survivors was higher than that in survivors on day 1, 2, and 3. IL-6 level in shock patients was higher than that in non-shock patients on day 1, 2, 6 and 7. IL-10 level in shock patients was higher than that in non-shock patients from day 1 to day 7. Plasma time-course curves of IL-6 and IL-10 were different between survivors and non-survivors. Plasma time-course curve of IL-6 was different between patients with shock and without shock. Regression analysis found that IL-6 was correlated with IL-10 and shock. IL-10 was correlated with IL-6 and mortality.

CONCLUSION

IL-6 and IL-10 were the key cytokines in the pathogenesis of severe sepsis. IL-6 was comparatively more associated with septic shock and IL-10 was comparatively more associated with mortality.

Acute moderate elevation of TNF-alpha does not affect systemic and skeletal muscle protein turnover in healthy humans

CONTEXT

Skeletal muscle wasting has been associated with elevations in circulating inflammatory cytokines, in particular TNF-alpha.

OBJECTIVE

In this study, we investigated whether TNF-alpha affects human systemic and skeletal muscle protein turnover via a 4-h recombinant human (rh) TNF-alpha infusion. We hypothesize that TNF-alpha increases human muscle protein breakdown and/or inhibits synthesis.

SUBJECTS AND METHODS

Using a randomized, controlled, crossover design, postabsorptive healthy young males (n = 8) were studied 2 h under basal conditions followed by a 4-h infusion of either rhTNF-alpha (700 ng . m(-2) . h(-1)) or 20% human albumin (control), which was the vehicle of rhTNF-alpha. Systemic and skeletal muscle protein turnover was estimated by a combination of tracer dilution methodology (primed continuous infusion of l-[ring-(2)H(5)]phenylalanine and l-[(15)N-leucine], with prime of l-[ring-(2)H(4)]tyrosine) and femoral arterial-venous differences over the leg and muscle biopsies.

RESULTS

Plasma TNF-alpha concentration rapidly increased from basal levels of approximately 0.7 to 17 pg . ml(-1) with rhTNF-alpha infusion. Whole body protein synthesis, breakdown, and net degradation were similar after the basal and infusion period of the control and rhTNF-alpha trials. Skeletal muscle, musculus vastus lateralis, protein fractional synthetic rate was not different over 4 h of control or rhTNF-alpha (rate of incorporation of (15)N-leucine). Muscle protein turnover determined with the phenylalanine three-compartment model showed similar muscle synthesis, breakdown, and net muscle degradation after 2-h basal and after 4-h control or rhTNF-alpha infusion.

CONCLUSION

This study is the first to show in humans that TNF-alpha does not affect systemic and skeletal muscle protein turnover, when acutely elevated for 4 h to moderate levels not causing adverse effects.

An evaluation of commercial fluorescent bead-based luminex cytokine assays

The recent introduction of fluorescent bead-based technology, allowing the measurement of multiples analytes in a single 25-50 microl sample has revolutionized the study of cytokine responses. However, such multiplex approaches may compromise the ability of these assays to accurately measure actual cytokine levels. This study evaluates the performance of three commercially available multiplex cytokine fluorescent bead-based immunoassays (Bio-Rad's Cytokine 17-plex kit; LINCO Inc's 29-plex kit; and RnD System's Fluorokine-Multi Analyte Profiling (MAP) base kit A and B). The LINCO Inc kit was found to be the most sensitive assay for measuring concentrations of multiple recombinant cytokines in samples that had been spiked with serial dilutions of the standard provided by the manufacturer, followed respectively by the RnD Fluorokine-(MAP) and Bio-Rad 17-plex kits. A positive correlation was found in the levels of IFN-gamma measured in antigen stimulated whole blood culture supernatants by the LINCO Inc 29-plex, RnD Fluorokine-(MAP) and RnD system IFN-gamma Quantikine ELISA kits across a panel of controls and stimulated samples. Researchers should take the limitation of such multiplexed assays into account when planning experiments and the most appropriate use for these tests may currently be as screening tools for the selection of promising markers for analysis by more sensitive techniques.

Elevated serum levels of IL-1ra in children with Plasmodium falciparum malaria are associated with increased severity of disease

Animal models suggest that cytokines and chemokines play a role in cerebral malaria (CM) pathogenesis, but levels of a number of cytokines and chemokines thought to be important in the pathogenesis of other infectious diseases are not well characterized in children with CM. Serum levels of granulocyte-colony stimulating factor (G-CSF), interleukin-1 receptor antagonist (IL-1ra), interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) were measured in 77 children with CM, 70 children with uncomplicated malaria (UM) and 63 healthy community children (CC) in Uganda. Children with CM had elevated serum levels of IL-1ra and IL-8 as compared to children with UM (median levels in pg/ml, 11,891 vs. 6510, P=0.05, and 63 vs. 41, P=0.01, respectively). Children with CM who died (n=4) had higher serum levels than survivors of IL-1ra (median levels in pg/ml, 65,757 vs. 10,355, P=0.02), G-CSF (709 vs. 117, P=0.02), and MCP-1 (1275 vs. 216, P=0.03) but not IL-8 (76 vs. 62, P=NS). Elevated IL-1ra levels are associated with increased disease severity in children with malaria, and very elevated levels of IL-1ra, G-CSF and MCP-1 are seen in children who die of CM.

Targets of anticytokine therapy and the risk of infections in humans and mice

PURPOSE OF REVIEW

To examine the type and risk of infections in humans and mice deficient in proinflammatory cytokines. Naturally occurring or manipulated genetic defects of tumor necrosis factor, interleukins-1, -6, -12, and -15, and interferon-gamma are examined for their increased susceptibility to, or protection from, infection.

RECENT FINDINGS

Interleukin-12p40 and interferon-gamma-blockers may lead to increased incidence of infections with intracellular bacteria, parasites, and fungi. In addition, we may see viral infections with interferon-gamma-blockers. Increased risk of infections is unlikely with either interleukin-1- or interleukin-15-blockers. Interleukin-6-blockers may lead to increased risk of infection with extracellular bacteria, viruses, parasites and fungi.

SUMMARY

In tumor necrosis factor knockout mice, increased susceptibility to pathogens are reported that are normally controlled by granuloma formation. In patients treated with tumor necrosis factor-blockers, a two-fold increase of granulomatous infections, predominantly reactivation of latent tuberculosis, is found. The infections detected in tumor necrosis factor knockout mice were accurate for predicting the infections observed when using tumor necrosis factor-blockers. If a similar correlation exists for other cytokines, the use of interferon-gamma and interleukin-12p40 blockers, and possibly interleukin-6 blockers, will lead to an increased risk for severe infections. Care should be taken when new cytokine blockers/antagonists are introduced.

Monitoring immune dysfunctions in the septic patient: a new skin for the old ceremony

Septic syndromes represent a major although largely underrecognized healthcare problem worldwide, accounting for thousands of deaths every year. It is now agreed that sepsis deeply perturbs immune homeostasis by inducing an initial tremendous systemic inflammatory response which is accompanied by an antiinflammatory process, acting as negative feedback. This compensatory inhibitory response secondly becomes deleterious as nearly all immune functions are compromised. These alterations might be directly responsible for worsening outcome, as they may play a major role in the decreased resistance to nosocomial infections in patients who survived initial resuscitation. Consequently, immunostimulatory therapies may now be assessed for the treatment of sepsis. This review focuses on immune dysfunctions described in septic patients and on their potential use as markers on a routine standardized basis for prediction of adverse outcome or of occurrence of secondary nosocomial infections. This constitutes a prerequisite to a staging system for individualized treatment for these hitherto deadly syndromes.