Anna Taparkou

Interactions between Human Phagocytes and Candida albicans Biofilms Alone and in Combination with Antifungal Agents

BACKGROUND Biofilm formation is an important component of vascular catheter infections caused by Candida albicans. Little is known about the interactions between human phagocytes, antifungal agents, and Candida biofilms. METHODS The interactions between C. albicans biofilms and human phagocytes alone and in combination with anidulafungin or voriconazole were investigated and compared with their corresponding planktonic counterparts by means of an in vitro biofilm model with clinical intravascular and green fluorescent protein (GFP)-expressing strains. Phagocyte-mediated and antifungal agent-mediated damages were determined by 2,3-bis[ 2- methoxy-4-nitro-5-sulfophenyl]2H-tetrazolium-5-carboxanilide assay, and structural effects were visualized by confocal microscopy. Oxidative burst was evaluated by flow cytometric measurement of dihydrorhodamine 123 oxidation, and cytokine release was measured by enzyme-linked immunosorbent assay. RESULTS Phagocytes alone and in combination with antifungal agents induced less damage against biofilms compared with planktonic cells. However, additive effects occurred between phagocytes and anidulafungin against Candida biofilms. Confocal microscopy demonstrated the absence of phagocytosis within biofilms but marked destruction caused by anidulafungin and phagocytes. Anidulafungin but not voriconazole elicited tumor necrosis factor alpha release from phagocytes compared with that from untreated biofilms. CONCLUSIONS C. albicans within biofilms are more resistant to phagocytic host defenses but are susceptible to additive effects between phagocytes and an echinocandin.

Impact of prematurity, stress and sepsis on the neutrophil respiratory burst activity of neonates

The aim of this study was to evaluate the impact of prematurity, sepsis and stress on the neutrophil respiratory burst activity (NRBA) of neonates. For this purpose 122 healthy neonates (89 term and 33 preterm), 33 preterm stressed neonates, 59 septic neonates (12 term and 47 preterm) and 26 healthy adults were studied. The NRBA was assessed after in vitro stimulation by PMA using a whole blood flow cytometric microassay with dihydrorhodamine 123 (DHR 123). It was found that the percentage of responding neutrophils in term neonates was comparable to that found in adults (medians 83.5 and 89.8%, respectively), whereas it was significantly lower in the healthy preterm neonates (median 70.6%, p < 0.05). The NRBA was further depressed in the stressed (median = 63%) and septic neonates, both term and preterm (medians 60.5 and 54.3%, respectively). No correlation with the levels of G-CSF, TNF-alpha and IL-1 beta, which were found to be higher in the stressed and septic neonates, was observed. These findings indicate that prematurity, sepsis and stress significantly depress the respiratory burst activity of neonatal neutrophils.

Administration of recombinant human granulocyte-colony stimulating factor to septic neonates induces neutrophilia and enhances the neutrophil respiratory burst and β2 integrin expression Results of a randomized controlled trial

Abstract The objective of this study was to investigate the effect of treatment with recombinant human granulocyte-colony stimulating factor (rhG-CSF) on the neutrophil count and function of preterm neonates with documented sepsis. For this purpose 62 preterm neonates with proven sepsis and 19 healthy preterm ones were studied. Of the 62 patients, 27 septic neonates had an absolute neutrophil count (ANC) >5000/mm3 (group A) and were scheduled not to receive rhG-CSF and 35/62 had an ANC <5000/mm3 (n= 35) and were randomly assigned either to receive rhG-CSF (group B) or not to receive it (group C). rhG-CSF (10 μg/kg) was administered for 3 consecutive days (0, 1, 2). The ANC, plasma levels of G-CSF (ELISA), neutrophil respiratory burst activity (NRBA) and neutrophil expression of CD11a, CD11b and CD11c (flow cytometry) were measured in all septic neonates on days 0 (onset of sepsis), 1, 3 and 5 and in the healthy neonates once within the first 2 days of life. We found that on day 0, G-CSF levels of all groups of septic neonates were significantly higher than those of the healthy ones. The highest levels were observed in group A. NRBA was diminished only in groups B and C and the expression of CD11a and CD11c was reduced in all groups of septic neonates. Administration of rhG-CSF resulted in a rapid and significant increase in ANC, NRBA and CD11a, CD11b and CD11c expression that persisted throughout the follow up. Conclusion The administration of granulocyte colony stimulating factor to septic neonates significantly increases the absolute granulocyte count and enhances the neutrophil respiratory burst and β2 integrin expression.

Flow cytometric measurement of HLA-DR expression on circulating monocytes in healthy and sick neonates using monocyte negative selection

The aim of this study was to investigate the effect of prematurity, neonatal sepsis, respiratory distress syndrome (RDS) and perinatal asphyxia on monocyte HLA‐DR expression of neonates using a flow cytometric method based on monocyte negative selection. The subjects were one hundred and thirty‐one neonates (59 healthy, 44 septicaemic, 20 with RDS and eight with perinatal asphyxia) and 20 healthy adults. Monocyte HLA‐DR expression was measured using one‐colour HLA‐DR labelling in a gate for monocytes obtained using the combination of CD3‐CD19–PE/CD15–FITC MoAbs. In addition, the common dual staining method using MoAbs against two CD14 epitopes (TUK4, MO2) was evaluated. With the one‐colour HLA‐DR labelling higher purity and recovery values of monocytes were achieved than with the dual labelling method. Healthy neonates had significantly lower percentages of HLA‐DR+ monocytes than adults (69 ± 13% versus 91·5 ± 2·5%) and comparable mean fluorescence intensity (MFI) (119 ± 25 versus 131 ± 26). Values did not differ significantly between healthy term and preterm neonates. Preterm neonates with RDS had a significantly lower percentage of HLA‐DR+ monocytes than the healthy preterm neonates. In neonates with asphyxia both parameters were comparable to those of the healthy ones. Septicaemic neonates presented significantly lower values of both parameters than the healthy, RDS and asphyxiated neonates. Monocyte negative selection provides a reliable estimation of HLA‐DR expression on monocytes. Expression of monocyte HLA‐DR is lower in healthy neonates in comparison with adults and is further decreased in neonates with sepsis and RDS, but it is not influenced by prematurity and perinatal asphyxia.

Thrombomodulin and von Willebrand factor: relation to endothelial dysfunction and disease outcome in children with acute lymphoblastic leukemia.

The severe endothelial dysfunction in children with acute lymphoblastic leukemia (ALL) can result from the disease itself, from treatment, or from other conditions (e.g. sepsis). The aim of this study was to determine the levels of markers of endothelial activation in children with ALL and to assess their potential prognostic value. Fifty-two children with ALL, 19 children with ALL 1–10 years after the completion of therapy, and 28 healthy children were studied. In children with ALL, there was a significant increase in thrombomodulin (TM) and von Willebrand factor (vWF) levels during the acute phase of the disease and during treatment. Children with an unfavorable outcome had higher levels of TM. In conclusion, severe endothelial dysfunction is present during the acute phase of ALL and during treatment and appears to result from the disease itself. Serum TM and vWF levels might represent additional, but not independent, prognostic markers in childhood ALL.

Simultaneous changes in serum HMGB1 and IFN-α levels and in LAIR-1 expression on plasmatoid dendritic cells of patients with juvenile SLE.. New therapeutic options?

We investigated the simultaneous changes in serum levels of HMGB1 and IFN-α as well as in LAIR-1 expression on plasmatoid dendritic cells (pDCs) of juvenile systemic lupus erythematosus (jSLE) patients in order to explore their involvement in the disease pathogenesis and their correlation with disease activity and other characteristics. In total, 62 blood samples were studied from 26 jSLE patients (18 girls), aged 8–16 years. Twenty healthy subjects (16 girls) of comparable age were included as healthy controls (HCs). Concentrations of serum HMGB1 and IFN-α were assessed by ELISA and LAIR-1 expression on pDCs by five-color flow cytometry. The disease activity index was assessed by SLEDAI and ECLAM scores. It was found that mean serum levels both of HMGB1 and IFN-α were significantly increased in jSLE patients compared to HCs and in jSLE patients with active disease with or without active nephritis compared to those with inactive disease. Mean serum levels of HMGB1 were positively correlated with levels of IFN-α and both were positively correlated with the SLEDAI and ECLAM scores. The expression of LAIR -1 on pDCs of jSLE patients was significantly lower than that of HCs. In conclusion, our findings indicate that serum HMGB1 not only represents a potential marker of disease activity but together with the lack of LAIR-1 inhibitory function may contribute to the sustained inflammatory action of IFN-α in jSLE. In this regard, blocking the action of HMGB1 and its receptors or enhancing the expression/inhibitory function of LAIR-1 on pDCs should be included in future immune interventions for controlling jSLE.

Ghrelin levels in patients with juvenile idiopathic arthritis: relation to anti-tumor necrosis factor treatment and disease activity

Studies in adults with rheumatoid arthritis reported low serum ghrelin that increased following anti-tumor necrosis factor (TNF) infusion. Data on juvenile idiopathic arthritis (JIA) are lacking. The aim of this pilot study was to explore serum ghrelin levels in patients with JIA and the possible association with anti-TNF treatment, disease activity, and nutritional status. Fifty-two patients with JIA (14/52 on anti-TNF treatment) were studied. Juvenile idiopathic arthritis was inactive in 3 of 14 anti-TNF-treated patients and in 11 of 38 non-anti-TNF-treated patients. The nutritional status, energy intake/requirements, appetite, and fasting serum ghrelin levels were assessed. Ghrelin control values were obtained from 50 individuals with minor illness matched for age, sex, and body mass index. Ghrelin levels in patients with JIA were significantly lower than in controls (P < .001, confidence interval [CI] = -101 to -331). Analysis according to anti-TNF treatment and disease activity showed that ghrelin levels were comparable to control values only in 3 patients with anti-TNF-induced remission. Ghrelin in non-anti-TNF-treated patients in remission was low. Multiple regression analysis showed that disease activity (P = .002, CI = -84.16 to -20.01) and anti-TNF treatment (P = .003, CI = -82.51 to -18.33) were significant independent predictors of ghrelin after adjusting for other potential confounders. Ghrelin did not correlate with nutritional status, energy balance, and appetite. Serum ghrelin is low in patients with JIA and is restored to values similar to those in controls following anti-TNF-induced remission. Our study provides evidence that TNF blockade is independently associated with serum ghrelin, which possibly contributes to anti-TNF-induced remission. These preliminary results could form the basis for future research.

IL-18 is correlated with type-2 immune response in children with steroid sensitive nephrotic syndrome

Children with steroid sensitive nephrotic syndrome (SSNS) is thought to have dysregulated type-1/type-2 cytokine network. Interleukin (IL)-18 is a cytokine, which may enhance both type-1 and type-2 responses, depending on the cytokines milieu. This prospective study aimed to assess type-1/type-2 cytokine synthesis and production profile in different stages of SSNS and define the potent involvement of IL-18. Twenty-three children with SSNS, aged 2.5-14 years, were studied; 23/23 both in active stage before treatment initiation and in remission still on steroids; 15/23 in remission off steroids as well. Data were compared with those obtained from 25 age-matched controls. The following parameters were assessed: Basic T cell populations, percentages of CD3+/CD69+/IFN-gamma+ and CD3+/CD69+/IL-4+ T cells as well as serum levels of IFN-gamma, IL-2, IL-4, IL-13 and IL-18. No difference in IL-2 levels was found between nephrotic children of all disease stages and controls (p>0.05). Percentage of CD3+/CD69+/IL-4+ T cells and serum levels of IL-4, IL-13 and IL-18 were significantly higher in the active stage of SSNS compared with the remission stages and controls (p<0.05). On the contrary, percentage of CD3+/CD69+/IFN-gamma+ T cells as well as serum IFN-gamma were significantly lower during active disease stage compared with remission stages and controls (p<0.05). In children with SSNS, of all disease stages, serum levels of IL-18 were significantly correlated with both IL-4 and IL-13 (r=0.628 and p<0.0001, r=0.71 and p<0.0001, respectively). It seems that a type-2 cytokine synthesis and production pattern prevails in children with active SSNS and IL-18 expression is significantly correlated with this type-2 immune response.

Comparable effect of conventional ventilation versus early high-frequency oscillation on serum CC16 and IL-6 levels in preterm neonates

Objective:Clara cell 16 kD protein (CC16) and interleukin (IL)-6 have been used as peripheral blood biomarkers of alveolar leakage and inflammation, respectively. Thus, their measurement in the bloodstream could be used to assess ventilator-induced lung injury. The objective of this study was to evaluate the effect of optimized synchronized intermittent mandatory ventilation (SIMV) and high-frequency oscillatory ventilation (HFOV) on circulating CC16 and IL-6 levels when used as the initial ventilation modes in preterm neonates.Study Design:Single center, prospective, randomized clinical study in preterm neonates (gestational age ⩽30 weeks) requiring mechanical ventilation within the first 2 h of life. Serum CC16 and IL-6 were measured on establishment of the assigned ventilation mode after admission, at days 3 and 14 of life as well as at 36 weeks postmenstrual age. Demographic-perinatal data and clinical parameters were also recorded.Result:Of the 30 neonates studied, 24 (gestational age 27.1±1.7 weeks, birth weight 942±214 g) were finally analyzed, equally assigned into the SIMV and HFOV groups. Both groups had comparable demographic-perinatal characteristics and clinical parameters. Serum CC16 and IL-6 altered significantly over time (repeated-measures analysis of variance, both P<0.001). However, changes were not affected by the ventilation mode. Post hoc analysis showed a significant decrease in CC16 and IL-6 from birth up to 36 weeks postmenstrual age in both groups.Conclusion:In preterm neonates, SIMV and HFOV are associated with comparable circulating CC16 and IL-6 levels. These findings suggest a similar alveolar leakage and systemic inflammation with any of the ventilation modes evaluated when their usage is optimized.

Antenatal Betamethasone Does Not Influence Lymphocyte Apoptosis in Preterm Neonates

Despite the widespread use of antenatal glucocorticosteroids (GCs), the possibility of adverse effects on the immune response in preterm neonates remains a major concern. GCs stimulate lymphocyte apoptosis, resulting in lymphopenia and functional disorders, which have been associated with sepsis-related death in critically ill neonates. We sought to assess the effect of antenatal betamethasone (BM) on lymphocyte apoptosis in preterm neonates. Fifty preterm neonates exposed to antenatal BM and 50 controls were studied prospectively. Lymphocyte apoptosis was assessed using the annexin-V/propidium iodide (PI) assay, analysis of cell cycle after staining with PI, and intracellular caspase-3 activity. The two groups did not differ significantly as regards absolute lymphocyte counts and the percentage of lymphocytes being annexin-V (+)/PI (-) (early apoptotic) or lymphocytes in the subG1 peak after staining with PI and those with intracellular caspase-3 activation. The lymphocyte number and apoptosis were not associated with the time elapsed between antenatal BM administration and delivery. A single course of antenatal BM does not influence apoptosis of neonatal lymphocytes. This is of significant importance with respect to the preservation of lymphocyte-associated immune response in preterm neonates.