A model to study antioxidant regulation of endotoxemia-modulated neonatal granulopoiesis and granulocyte apoptosis

Evaluation of Haematological Parameters and Uric Acid in the Diagnosis of Late Onset Neonatal Sepsis

Introduction A number of parameters studied in a whole blood count can be helpful in the diagnosis of neonatal sepsis. The platelet/lymphocyte ratio (PLR) is a systemic inflammatory marker in early sepsis and has been used as a diagnostic indicator in cardiovascular events and cancer. Being one of the major antioxidants in human biological fluids, serum uric acid is responsible for neutralising free radicals. The red cell distribution width/platelet ratio (RPR) is a diagnostic marker in adult inflammatory diseases. The objective of our study is to investigate the relationship of late neonatal sepsis with whole blood count parameters and serum uric acid levels. Materials and methods Newborns older than postnatal three days who had clinical and laboratory findings of sepsis were included in the study. The study included 140 newborns who were divided into three groups, 53 in the culture-proven late sepsis group, 47 in the clinical sepsis group, and 40 in the healthy control group. The whole blood count parameters and serum uric acid levels were examined in both the clinical sepsis and proven sepsis patients at the time when they were diagnosed with sepsis. Results The birth week was significantly lower in the evidenced and clinical sepsis patients compared to the healthy control group. Development of late sepsis was significantly higher in the male gender than in healthy controls. Serum uric acid levels were significantly higher in proven or clinical sepsis than in healthy controls. The level of serum uric acid (3.77±1.6) in proven sepsis was significantly higher than the control group (2.83±1.1). The uric acid level had an area under the curve (AUC) 0.552-0.717, 35% sensitivity, 95% specificity, 94.6% positive predictive value (PPV), and 36.9% negative predictive value (NPV) in the diagnosis of proven and clinical late sepsis. Neutrophil/lymphocyte ratio (NLR) was significantly higher in proven sepsis than in healthy newborns and was higher in the clinical sepsis group than in the proven sepsis group (p: 0.002). While the mean eosinophil value was 618.5±472.1 in proven sepsis, it was 549.3±294.9 in the control group and there was a statistically significant difference between the two groups (p: 0.036). Conclusion In late-onset neonatal sepsis, the NLR level was higher, and the eosinophil level was lower in the clinical sepsis patients than in healthy newborns. We believe that a higher level of serum uric acid in sepsis is effective in the early diagnosis of patients who also had other clinical findings of sepsis.

Vitamin D enhances reactive oxygen intermediates production in phagocytic cells in term and preterm infants

BACKGROUND

Newborn infants are endotoxin tolerant which may be responsible for their increased susceptibility to bacterial sepsis. Vitamin D has an immunomodulatory effect and newborn infants are at risk of vitamin D deficiency. We examined the in vitro effect of 1, 25-dihydroxyvitamin D (1,25OHD) on whole blood phagocytic toll-like receptor 4 (TLR4), CD11b, and reactive oxygen intermediates (ROIs) in newborn infants during sepsis.

METHODS

Whole blood from preterm infants <32-wk gestation, control term neonates, and adults were sampled for phagocytic expression of ROI, TLR4, CD11b in response to lipopolysaccharide (LPS), and 1,25OHD using flow cytometer.

RESULTS

ROI production from newborn phagocytes incubated with LPS alone was decreased. Pretreatment with 1,25OHD demonstrated increased (P = 0.001) phagocytic ROI production in newborns but not in adults. 1,25OHD did not have any effect on TLR4 and CD11b in both newborns and adults. Pretreatment with ROI inhibitors (apocynin (APO) and diphenyleneiodonium), phosphoinositide 3-kinase (PI3K) inhibitor, and p38 inhibitor blocked neutrophil ROI production.

CONCLUSION

Neonatal phagocytic cells had diminished ROI production in the presence of LPS, however, pretreatment with 1,25OHD reversed this hyporesponsiveness. This action by 1,25OHD was mediated by activation of nicotinamide adenine dinucleotide phosphate oxidase system through PI3K signaling enzymes.

Efficacy of recombinant human granulocyte colony stimulating factor in very-low-birth-weight infants with early neutropenia

BACKGROUND/PURPOSE

Neutropenia is a risk factor for nosocomial infections (NI) in very-low-birth-weight (VLBW) infants. Although recombinant human granulocyte colony stimulating factor (rhG-CSF) increases the neutrophil counts in neutropenic VLBW infants, its long-term efficacy for early neutropenia (EN) remains unknown.

METHODS

In this case-controlled study, charts of VLBW recipients of rhG-CSF for EN (total neutrophil count <1.5 × 10(9)/L during first 7 days) were reviewed and compared to gestational age, total neutrophil count, and birth weight matched infants unexposed to rhG-CSF.

RESULTS

Twenty-seven infants were identified in each group. Mortality and morbidity did not differ between the two groups. Rate of NI (16/27 vs. 4/27, p = 0.002, odds ratio = 8.36) as well as the total number of episodes of NI (22 vs. 4, p = 0.007) were higher in rhG-CSF (+) group than in the rhG-CSF (-) group.

CONCLUSION

Our experience does not show benefit in empirical use of rhG-CSF in preventing NI in VLBW infants with EN.

Mean platelet volume and uric acid levels in neonatal sepsis

OBJECTIVES

To determine the role of mean platelet volume (MPV) and uric acid levels in the diagnosis of neonatal sepsis (NS).

METHODS

A total of 146 newborns with suspected NS were prospectively included in the study and infants without NS (n = 142) were assigned as controls. The patients were divided into three groups: Group I (n = 64): clinical NS, Group II (n = 82): culture-proven NS, and Group III (n = 142): healthy controls.

RESULTS

The patients in Group II had the highest C-reactive protein (CRP) levels (54.6 ± 5.4 mg/L), lowest platelet counts (199,329 ± 135,952/mm(3)) and lowest uric acid levels (2.6 ± 1.8 mg/dL) when compared to Groups I and III (p < 0.05, for all comparisons). MPV values were higher in Group I (10.6 ± 1.1 fL) and Group II (10.4 ± 0.9 fL) when compared to Group III (9.2 ± 1.2 fL) (p = 0.001), although there was no difference between Groups I and II. Area under curve (AUC) values for CRP, MPV, and uric acid were 0.92 (p = 0.001), 0.76 (p = 0.001) and 0.28 (p = 0.001), respectively. The diagnostic cut-off values for CRP and MPV were 9.5 mg/dL and 10.4 fL. Sensitivity and specificity of MPV in NS were 54 % and 82 % respectively. When combined with CRP its sensitivity and specificity increased to 89 % and 79 % respectively.

CONCLUSIONS

The combined use of CRP and MPV should be considered in the early diagnosis of NS, but uric acid levels may only be utilized as an additional tool to support diagnosis. CRP is shown to be more sensitive and specific than MPV and uric acid in diagnosing neonatal sepsis.

Early neutropenia is not associated with an increased rate of nosocomial infection in very low-birth-weight infants

BACKGROUND

Evidence is contradictory whether very low-birth-weight (VLBW, birth weight <1500 g) infants with early neutropenia (NP), especially those born to mothers with preeclampsia experience a greater incidence of nosocomial infection (NI).

OBJECTIVE

To investigate whether NP within the first 7 days of life is a risk factor for NI in VLBW infants.

METHODS

Over a 42-month period, we identified all VLBW infants born at <or=34 weeks gestation who survived for more than 72 h. Infants who had no evidence of early infection, who had at least one complete blood count performed in the first week of life, and who were not given prophylactic recombinant human granulocyte colony-stimulating factor (rhG-CSF) were included in this retrospective study. Early NP was defined as an absolute neutrophil count less than 1500 per microl at any time during the first week of life. NI was defined as the culture of a bacterial or fungal pathogen from a sterile body fluid that was obtained after 72 h of life in an infant with one or more clinical signs of infection.

RESULTS

A total of 338 VLBW infants were reviewed. Of those, 51 infants were excluded because of death or onset of an infection before 72 h of age, lack of a complete blood count in the first week of life or treatment with rhG-CSF. Of the remaining 287 infants, NI occurred in 11 of 77 (14.3%) infants with early NP compared to 42 of 210 (20.0%) infants without early NP (P=0.31). Infants who developed NI were smaller and less mature, had lower Apgar scores, were more frequently instrumented with central lines and required a longer duration of parenteral nutrition compared to infants without NI. Infants with NI also had a higher mortality and a greater incidence of necrotizing enterocolitis, severe intraventricular hemorrhage and threshold retinopathy of prematurity. However, using stepwise multivariate logistic regression analysis, only the duration of parenteral nutrition and gestational age were significant risk factors for NI.

CONCLUSION

Our data do not support the hypothesis that early NP increases the risk for NI in VLBW infants.

Neonatal gut barrier and multiple organ failure: role of endotoxin and proinflammatory cytokines in sepsis and necrotizing enterocolitis

BACKGROUND/PURPOSE

Failure of the gut barrier and endotoxemia have been implicated in sepsis and multiple organ failure (MOF) syndromes in adults. The contributions of endotoxin (ETX) and proinflammatory cytokines (CKs) to the pathophysiology of disease and the outcomes of infants in the neonatal intensive care unit (NICU) are not clear. We measured ETX and CK concentrations in infants who presented with clinical signs of sepsis and/or necrotizing enterocolitis (NEC) to study their impact on MOF and outcomes.

METHODS

Blood samples from infants with signs of NEC and/or sepsis were collected for culture and determination of complete blood cell counts and concentrations of CKs (interleukin [IL]-1beta, tumor necrosis factor [TNF] alpha, and IL-6) and ETX at the onset of illness. Infants with signs of sepsis but without those of NEC were classified by blood culture results into a confirmed sepsis group (ie, positive culture) or a control group (ie, negative culture). Endotoxin concentrations were determined by chromogenic Limulus amebocyte lysate assay, and CK levels were quantitated by enzyme-linked immunoassay. Data are expressed as mean +/- SD and as odds ratios (ORs) with 95% confidence intervals (CIs). P values lower than .05 were considered to be significant.

RESULTS

There was no demographic or clinical difference among the NEC (n = 27), sepsis (n = 44), and control (n = 56) groups, except that fewer (P = .02) infants in the NEC group (11%) had received maternal milk feedings as compared with infants in the sepsis group (23%) and those in the control group (39%). Endotoxin concentrations were higher (P < .0001) in the NEC group (3.30 +/- 2.11) as compared with the sepsis group (0.67 +/- .86) and the control group (0.09 +/- 0.24). Generalized linear regression analysis using formula feeding, mechanical ventilation, and gram-negative bacteremia as covariates demonstrated that NEC increased ETX concentrations independently (r = .80; P < .0001). Endotoxemia correlated with higher concentrations of all 3 CKs (P < .0001). There was an inverse association between ETX and both platelet count (r = -0.30; P = .0003) and absolute neutrophil count (r = -0.29; P = .0009). Infants who died of MOF had higher concentrations of ETX (2.83 +/- 3.04 vs 0.67 +/- 1.04 EU/mL; P < .0001), IL-1beta (509 +/- 493 vs 106 +/- 223 pg/mL; P < .0001), IL-6 (416 +/- 308 vs 99 +/- 165 pg/mL; P < .0001), and TNF-alpha (503 +/- 449 vs 126 +/- 237 pg/mL; P < .0001) as compared with those without MOF. Eighty-six percent of the infants with MOF died. Multivariate logistic regression analysis demonstrated that higher ETX concentrations (OR = 2.47; 95% CI = 1.39-4.40; P = .002) and lower gestational age (OR = 1.41; 95% CI = 1.12-1.77; P = .003) predicted mortality.

CONCLUSIONS

Neonatal endotoxemia and release of proinflammatory CKs are important contributors to MOF and mortality in the NICU. Endotoxemia was most severe at the onset of illness among the infants with NEC, suggesting that gut barrier failure plays an important role in adverse outcomes in the NICU.

Higher spontaneous and TNFalpha-induced apoptosis of neonatal blood granulocytes

Granulocytes play an important role in inflammatory diseases. Neonates tend to develop granulocytopenia under sepsis and stress. It remains unclear whether apoptosis of neonatal granulocytes is different from that of adult granulocytes. In this study, we analyzed the discrepancy of granulocyte apoptosis between cord blood (CB) and adult blood (AB). We found that spontaneous and tumor necrosis factor-alpha (TNFalpha)-induced granulocyte apoptosis as determined by phosphatidylserine expression and DNA fragmentation were more prominent in CB granulocytes than AB granulocytes. CD95 ligand and TNFalpha levels were significantly higher in CB than in AB (p = 0.001 and p < 0.001, respectively). TNF receptor-2 and CD95 expression on CB granulocytes were not different from those on AB granulocytes. However, the TNF receptor-1 (TNFR1) expression was lower on CB granulocytes than that on AB granulocytes (69.98 +/- 7.32 versus 89.04 +/- 3.73%, p = 0.029). This decrease of TNFR1 expression on neonatal granulocytes might be related to a higher plasma TNFalpha level associated with an intrinsic defect on the dynamic change of membrane TNFR1 expression in neonatal granulocytes. The expression of anti-apoptotic molecule Bcl-2 in neonatal granulocytes was also lower than that in adult granulocytes (4.64 +/- 0.51 versus 7.24 +/- 1.17 unit/mg protein, p = 0.032). Moreover, another anti-apoptotic signal, nuclear factor-kappaB nuclear translocation, was also lower in CB than AB granulocytes. Results from this study suggest that higher plasma death ligands associated with lower anti-apoptotic molecules in granulocytes may act an important role in triggering neonatal granulocyte apoptosis.

Labor promotes neonatal neutrophil survival and lipopolysaccharide responsiveness

Labor is a mild proinflammatory state that is associated with fetal leukocytosis. Elective cesarean section has been linked with increased neonatal morbidity, which may be partially immune mediated. We hypothesized that labor may alter neutrophil phenotype and thereby decrease neonatal complications. We characterized neutrophil function and survival in normal neonates after either uncomplicated vaginal delivery (VD) or elective cesarean section (CS) without labor. Spontaneous neutrophil apoptosis is delayed in cord blood neutrophils of neonates after normal labor (VD) compared with CS, as assessed by propidium iodide DNA incorporation using flow cytometry. This demonstrates their ability to maintain an inflammatory response. CD11b expression on neonatal neutrophils after CS is decreased, providing further evidence of altered activation or priming. Lipopolysaccharide responsiveness, characterized by CD11b and apoptosis, is similar in VD and adults, but CS-derived neutrophils are unresponsive. Baseline TLR-4 levels are elevated in CS in contrast to the other groups, although expression is not up-regulated by lipopolysaccharide co-incubation. Neonatal neutrophil survival and function are altered by labor and may increase antibacterial function and neutrophilia. This suggests that labor of any duration may be immunologically beneficial to the normal term neonate.

Shockwave stimulates oxygen radical-mediated osteogenesis of the mesenchymal cells from human umbilical cord blood

Human umbilical cord blood (HUCB) mesenchymal progenitor cells expressed stro-1 or CD44 or CD29, and subsequently, differentiated toward osteogenic lineage. Physical shockwave treatment increased osteogenic activity of HUCB mesenchymal progenitor cells through superoxide-mediated TGF-beta1 induction. Transplantation of shockwave-treated HUCB mesenchymal progenitor cells enhanced healing of segmental femoral defect in severe combined immunodeficiency disease (SCID) mice.

INTRODUCTION

Mesenchymal progenitor cells (MPCs) in the bone marrow are precursors to bone development. It remains uncertain whether MPCs are present in human umbilical cord blood (HUCB) and are capable of differentiating into osteogenic cell lineage. Extending from a model of shockwave (SW) promotion of bone marrow stromal cell differentiation toward osteoprogenitors in rats, we further investigated how physical SW mediated biological responses in regulating osteogenic differentiation of HUCB MPCs.

MATERIALS AND METHODS

HUCB was subjected to SW treatment at different energy flux densities and impulses. Colony-forming units-stroma (CFU-Stroma), osteogenic activities (Cbfa1/Runx2 expression, bone alkaline phosphatase activity, and bone nodule formation), and bone formation by heterologous transplantation into SCID mice were assessed.

RESULTS

Few CD34+ stem cells (1.3%) and stro-1+ cells (1.0%) were present in the freshly prepared mononuclear cells (MNCs) from HUCB. The number of stro-1+ cells, but not CD34+, increased to 72.4% in the adherent cell culture over 6 days. Stro-1+ cells co-expressed CD44 and CD29 markers and grew into CFU-Stroma that matured into bone nodules. We found that the SW treatment (0.16 mJ/mm2 energy flux density, 200 impulses) elicited superoxide production and promoted formation of CFU-Stroma, but not of hematopoietic CFU-Mix. SW also enhanced the production of transforming growth factor (TGF)-beta1, but not of interleukin (IL)-3 or granulocyte monocyte-colony stimulating factor (GM-CSF). Neutralization of TGF-beta1 significantly reduced SW-promoted CFU-Stroma formation. Superoxide scavenging by superoxide dismutase blocked SW enhancement of TGF-beta1 production and formation of CFU-Stroma. Administration of SW-treated HUCB MPCs to SCID mice with femoral segmental defects facilitated dense, bridging callus and gap closure.

CONCLUSION

HUCB MPCs subjected to SW treatment is a potential source for stem cells useful in the treatment of orthopedic disorders. An optimal physical SW treatment enhanced osteogenesis through superoxide-mediated TGF-beta1 production. Physical stimulation is an alternative method for extending mesenchymal stem cells of HUCB.

Different antigens trigger different Th1/Th2 reactions in neonatal mononuclear cells (MNCs) relating to T-bet/GATA-3 expression

Neonates are known to have poor cellular immunity, especially poor Th1 response. We investigated how neonatal mononuclear cells raised different Th1/Th2 reactions in response to different antigens. Employing Dermatophagoides pteronyssinus (Der p) extract and varicella zoster virus (VZV) as antigens, we assessed Th1/Th2 reactions as demonstrated by IL-4/IFNgamma production and mRNA expression, and transcriptional factors T-bet/GATA-3 mRNA expression in mononuclear cells from human umbilical cord blood (CBMC). Results showed that VZV induced a dramatic increase of IFNgamma production by adult peripheral blood mononuclear cells (PBMC), whereas VZV did not drive CBMC to release significant IFNgamma production (1614.7+/-362.0 vs. 49.0+/-29.3,p<0.005). However, Der p induced higher IFNgamma production by CBMC than VZV (298.1+/-171.8 vs. 49.0+/-29.3, P=0.047). In contrast, VZV did not induce significant IL-4 production either by CBMC or by PBMC. Der p induced a comparative IL-4 production by CBMC and PBMC (2.58+/-0.84 vs. 2.04+/-0.37, p>0.05). A real-time RT-PCR analysis of IL-4 and IFNgamma mRNA expression showed that VZV induced a significantly higher IFNgamma, but not IL-4, mRNA expression in PBMC than CBMC. Der p did not induce significant difference of IFNgamma or IL-4 mRNA expression in PBMC and CBMC. VZV enhanced Th1-related transcription factor T-bet mRNA expression, in association with later down-regulation of Th2-related GATA-3 mRNA expression in PBMC. However, VZV did not up-regulate T-bet or down-regulate GATA-3 expression significantly in CBMC. In contrast, Der p induced an early GATA-3 expression and later T-bet expression in CBMC. These results suggest that different antigens trigger various Th1/Th2 reactions in PBMC and CBMC resulting from kinetic changes of T-bet/GATA-3 expression.

Superoxide mediates shock wave induction of ERK-dependent osteogenic transcription factor (CBFA1) and mesenchymal cell differentiation toward osteoprogenitors

Extracorporeal shock wave (ESW) is an alternative non-invasive method for the promotion of bone growth and tendon repair. In an animal model, we have reported that ESW promoted bone marrow osteoprogenitor growth through transforming growth factor-beta1 induction. We have further explored the mechanism for the ESW promotion of osteogenesis. Results showed that an optimal ESW treatment at 0.16 mJ/mm(2) for 500 impulses rapidly induced a higher O(2)(-) and ONOO(-) production associated with a decrease of nitric oxide level in 1 h, and induced a higher transforming growth factor-beta1 production in 24 h, and a higher colony-forming units-osteoprogenitor formation in 12 days. The colony-forming units-osteoprogenitor colonies revealed positive staining of bone alkaline phosphatase and turned into bone nodules in 21 days. Early scavenging of O(2)(-) but not Ca(2+), H(2)O(2), or prostaglandin E(2) suppressed osteoprogenitor cell growth and maturation. Scavenging of O(2)(-) by superoxide dismutase raised the nitric oxide level back to the basal level and suppressed ESW-promoted osteoprogenitor cell growth, whereas inhibition of ONOO(-) by urate or NO by N-nitro-l-arginine methyl ester did not affect ESW promotion of osteogenesis, indicating that O(2)(-) acted as an early signal for ESW-induced cell growth. Further studies demonstrated that ESW induced ERK activation, and blockage of O(2)(-) production or inhibition of tyrosine kinase, but not protein kinase A and C inhibitors, suppressed ESW-induced ERK activation. In support that O(2)(-) mediated the ESW-induced ERK activation and osteogenic differentiation, we further demonstrated that scavenging of O(2)(-) by superoxide dismutase and inhibition of ERK activation by PD98059 decreased specific osteogenic transcription factor, core binding factor A1 activation, and decreased osteocalcin expression. Taken together, we showed that ESW-induced O(2)(-) production followed by tyrosine kinase-mediated ERK activation and core binding factor A1 activation resulted in osteogenic cell growth and maturation. Thus, an appropriate modulation of redox reaction by ESW may have some positive effect on the bone regeneration.