The in vivo effect of recombinant human granulocyte-colony stimulating factor in neutropenic neonates with sepsis

Effectiveness of Granulocyte Colony-Stimulating Factor in Hospitalized Infants with Neutropenia

Objective The objective of this study was to determine the time to hematologic recovery and the incidence of secondary sepsis and mortality among neutropenic infants treated or not treated with granulocyte colony-stimulating factor (G-CSF). Study Design We identified all neutropenic infants discharged from 348 neonatal intensive care units from 1997 to 2012. Neutropenia was defined as an absolute neutrophil count ≤ 1,500/µL for ≥ 1 day during the first 120 days of life. Incidence of secondary sepsis and mortality and number of days required to reach an absolute neutrophil count > 1,500/µL for infants exposed to G-CSF were compared with those of unexposed infants. Results We identified 30,705 neutropenic infants, including 2,142 infants (7%) treated with G-CSF. Treated infants had a shorter adjusted time to hematologic recovery (hazard ratio: 1.36, 95% confidence interval [CI]: 1.30-1.44) and higher adjusted odds of secondary sepsis (odds ratio [OR]: 1.50, 95% CI: 1.20-1.87), death (OR: 1.33, 95% CI: 1.05-1.68), and the combined outcome of sepsis or death (OR: 1.41, 95% CI: 1.19-1.67) at day 14 compared with untreated infants. These differences persisted at day 28. Conclusion G-CSF treatment decreased the time to hematologic recovery but was associated with increased odds of secondary sepsis and mortality in neutropenic infants. G-CSF should not routinely be used for infants with neutropenia.

Neutropenia in the newborn

PURPOSE OF REVIEW

The aim is to review normal blood neutrophil concentrations and the clinical approach to neutropenia in the neonatal period. A literature search on neonatal neutropenia was performed using the databases PubMed, EMBASE, and Scopus, and the electronic archive of abstracts presented at the annual meetings of the Pediatric Academic Societies.

RECENT FINDINGS

The review summarizes current knowledge on the causes of neutropenia in premature and critically ill neonates, focusing on common causes such as maternal hypertension, neonatal sepsis, twin-twin transfusion, alloimmunization, and hemolytic disease. The article provides a rational approach to diagnosis and treatment of neonatal neutropenia, including current evidence on the role of recombinant hematopoietic growth factors.

SUMMARY

Neutrophil counts should be carefully evaluated in premature and critically ill neonates. Although neutropenia is usually benign and runs a self-limited course in most neonates, it can be prolonged, and it constitutes a serious deficiency in antimicrobial defense in some infants.

Neonatal neutropenia: what diagnostic evaluation is needed and when is treatment recommended?

Neutropenia is a relatively frequent finding in the neonatal intensive care unit, particularly in very low birth weight neonates during the first week of life. Healthy term and preterm neonates have blood neutrophil counts within the same basic range as adults, but their neutrophil function, and their neutrophil kinetics during infection, differ considerably from those of adults. Neutrophil function of neonates, particularly preterm neonates, is less robust than that of adults and might also contribute to the increase in propensity to infection. In premature infants, early-onset neutropenia is correlated with sepsis, maternal hypertension, intrauterine growth restriction, severe asphyxia, and periventricular haemorrhage, and might be associated with an increase in the incidence of early-onset sepsis, nosocomial infection, and Candida colonisation. Some varieties of neutropenia in the NICU are very common and others are extremely rare. The most common causes of neutropenia in the NICU have an underlying cause that is often evident, and require little diagnostic evaluation. Unlike, persistent neutropenia should prompt evaluation even if it is of moderate severity. The laboratory tests to consider are those that provide a specific diagnosis. The first tests that should be ordered are a blood film, a complete blood count on the mother, and, if her blood neutrophil concentration is normal, maternal neutrophil antigen typing and an anti-neutrophil antibody screen. A bone marrow biopsy can be useful in cases with prolonged, unusual, or refractory neutropenia. Various treatments have been proposed as means of enhancing neutrophil production and function in preterm infants. Both recombinant granulocyte stimulating factor and recombinant granulocyte macrophage-colony-stimulating factor have been tried with variable success. Intravenous immunoglobulin, corticosteroids, granulocyte transfusions, and gamma interferon did not show a clear adequate beneficial role for the therapy of neonatal neutropenia.

A multicenter, randomized, placebo-controlled trial of prophylactic recombinant granulocyte-colony stimulating factor in preterm neonates with neutropenia

OBJECTIVE

To test the hypothesis that prophylactic treatment of neutropenic premature neonates with recombinant granulocyte-colony stimulating factor (rG-CSF) would reduce the incidence of nosocomial infections (NIs).

STUDY DESIGN

A total of 25 neonatal intensive care units participated in this multicenter, randomized, double-blind, placebo-controlled trial. Premature infants of gestational age (GA) <or= 32 weeks were included if they had a peripheral blood count showing < 1500 neutrophils/mm(3) for at least 24 hours during the first 3 weeks of life. A total of 200 infants received either rG-CSF (10 microg/kg/day) or placebo for 3 days. Primary outcome was survival free of infection for 4 weeks after treatment, assessed in an intention-to-treat analysis.

RESULTS

A total of 102 infants received rG-CSF (mean GA, 29.2 weeks), and 98 received placebo (mean GA, 29.1 weeks). Survival free of confirmed infection for 4 weeks after treatment was 74/102 in the rG-CSF group and 66/98 in the placebo group (P = .42). However, during 2 weeks, there was a significant difference between groups (86/102 vs 70/98; P = .028).

CONCLUSIONS

In this population, prophylactic rG-CSF did not significantly increase survival free of infection at 4 weeks after treatment. The transient effect observed at 2 weeks in the most immature infants should be evaluated further.

Toward improving mucosal barrier defenses: rhG-CSF plus IgG antibody

Epithelial cell functions ultimately define the ability of the extremely low birth weight human fetus to survive outside of the uterus. These specialized epithelial cell capacities manage all human interactions with the ex utero world including: (i) lung mechanics, surface chemistry and gas exchange, (ii) renal tubular balance of fluid and electrolytes, (iii) barrier functions of the intestine and skin for keeping bacteria out and water in, plus enabling intestinal digestion, as well as (iv) maintaining an intact neuroepithelium lining of the ventricles of the brain and retina. In Part I of this two part review, the authors describe why the gut barrier is a clinically relevant model system for studying the complex interplay between innate and adaptive immunity, dendritic &epithelial cell interactions, intraepithelial lymphocytes, M-cells, as well as the gut associated lymphoid tissues where colonization after birth, clinician feeding practices, use of antibiotics as well as exposure to prebiotics, probiotics and maternal vaginal flora all program the neonate for a life-time of immune competence distinguishing "self" from foreign antigens. These barrier defense capacities become destructive during disease processes like necrotizing enterocolitis (NEC) when an otherwise maturationally normal, yet dysregulated and immature, immune defense system is associated with high levels of certain inflammatory mediators like TNFa. In Part II the authors discuss the rationale for why rhG-CSF has theoretical advantages in managing NEC or sepsis by augmenting neonatal neutrophil number, neutrophil expression of Fcg and complement receptors, as well as phagocytic function and oxidative burst. rhG-CSF also has potent anti-TNFa functions that may serve to limit extension of tissue destruction while not impairing bacterial killing capacity. Healthy, non-infected neutropenic and septic neonates differ in their ability to respond to rhG-CSF; however, no neonatal clinical trials to date have identified a clear clinical benefit of rhG-CSF therapy. This manuscript will review the literature and evidence available for identifying the ideal subject for cytokine treatment using NEC as the model disease target.

Effects of enterally administering granulocyte colony-stimulating factor to suckling mice

Gastrointestinal (GI) tract development is influenced by multiple growth factors, some of which are delivered directly to the GI lumen, as they are swallowed constituents of amniotic fluid, colostrum, and milk. Granulocyte colony-stimulating factor (G-CSF), traditionally known as a granulocytopoietic growth factor, is an example of one such factor. However, it is not clear whether the large amounts of G-CSF that are normally swallowed by the fetus and neonate have systemic effects on circulating neutrophils or local effects in the developing intestine. To assess this, we administered either active or heat-denatured (control) recombinant human G-CSF to 5- to 7-d-old C57BL/6 x 129SvJ mice. Pups received either a low dose (3 ng) that was calculated to approximate the amount of G-CSF swallowed in utero from amniotic fluid or an isovolemic high dose 100 times larger (300 ng). Oral dosing was performed daily for either 3 or 7 d, after which pups were killed and measurements were made on the blood and the GI tract. Absolute blood neutrophil counts and immature to total neutrophil ratios did not differ from controls in any of the test groups. However, intestinal villus area, perimeter, length, crypt depth, and proliferating cell nuclear antigen index increased significantly among those that were treated with active G-CSF. Thus, in suckling mice, enterally administered G-CSF had no effect on the concentration of circulating neutrophils but had trophic effects on the intestine. We speculate that the G-CSF present in amniotic fluid, colostrum, and milk acts as a topical intestinal growth factor and has little or no granulocytopoietic action.

What is the rationale for the use of granulocyte and granulocyte-macrophage colony-stimulating factors in the neonatal intensive care unit?

Neonatal sepsis remains an unsolved major contributor to morbidity and mortality. In the 1980s the promise of augmenting immune function using pooled intravenous gammaglobulin to supplement the exceedingly low levels of immunoglobulin G in premature infants failed to demonstrate a clear advantage. Similarly, cytokine augmentation of cellular function in the 1990s largely appeared to be suffering the same fate. However, both results may arise from a problem in experimental design where the combination of both treatments may be necessary along with specific antibody. For example, in vitro, independently of an array of other humoral and cellular immature immune system issues, opsonization of bacteria is improved in the presence of antibody. The question is whether the same result can be achieved in vivo. No experiments have been reported that directly test this hypothesis.

CONCLUSION

More investigation is needed in this challenging area of neonatal research.

Comparison of recombinant granulocyte colony-stimulating factor, recombinant human granulocyte-macrophage colony-stimulating factor and placebo for treatment of septic preterm infants

BACKGROUND

To reduce morbidity and mortality adjuvant cytokine therapy was administered to septic neonates with variable results. The objective of this case series was to compare the effectiveness of recombinant human granulocyte-macrophage colony-stimulating factor (rhuGM-CSF) and recombinant granulocyte colony-stimulating factor (rG-CSF) with that of placebo in correcting neutropenia induced by sepsis.

METHODS

Symptomatic, septic premature neonates with or without a positive blood culture were eligible. Twenty-eight patients were randomized: 10 received rG-CSF (5 microg/kg/dose i.v. twice a day); 10 received rhuGM-CSF (4 microg/kg/dose i.v. twice a day) and 8 received placebo for a maximum of 7 days, or until an absolute neutrophil count (ANC) of 10,000 cells/mm was reached.

RESULTS

A significant increase in the ANC above the baseline was present on Day 2 in the rG-CSF group (P = 0.015) and on Day 5 in the rhuGM-CSF (P = 0.002) and placebo (P = 0.027) groups. The ANC of the rG-CSF group was significantly above that in the rhuGM-CSF and placebo groups on Day 7 (P = 0.03). Mortality and neonatal intensive care unit morbidity was not significantly different between the groups.

CONCLUSION

The neutrophil count in the rG-CSF-treated group increased significantly faster than that in the placebo or rhuGM-CSF group.

A practical approach to neutrophil disorders

This review discusses disorders of altered neutrophil number and function and provide a basic framework for patient evaluation and management. The sections begin with neutropenia, neutrophilia and neutrophil dysfunction with a general screening approach to differentiate common, more benign syndromes from rare, often more serious disorders. Also included is a detailed discussion of some specific primary neutrophil syndromes at the end of each section. Focus is placed on specific disorders that are clinically common or particularly instructive.

Perinatal immunomodulation

The fetus and the neonate are particularly vulnerable to injury caused directly by immunologic mechanisms or inflicted by infectious agents that take advantage of their relatively immature and inexperienced immune system. With increasing survival of high-risk neonates in the surfactant era, prevention/treatment of sepsis and chronic lung disease (CLD) has emerged as an area of priority in neonatal research. Considering the role of inflammatory mediators in the pathogenesis of sepsis and CLD, the clinical application of immunomodulator therapy to neonatology is perhaps more important at present than ever. Advances in molecular biology and immunology have led to development of newer immune modulator therapies that are directed towards specific cells or cytokines rather than resulting in a general suppression of the immune response. Failure of promising, newer immunomodulator therapies in sepsis trials in adults has, however, clearly documented the difficulties in diagnosing/correcting the imbalance between pro- and anti-inflammatory responses. As in the case of sepsis, development of a single magic bullet for prevention/management of a multi-factorial illness like CLD may be difficult, as prevention of prematurity - the single most important high-risk factor for CLD - is an unachievable goal at present. As new frontiers are being explored, older, well-established therapies like antenatal anti-D immunoglobulin prophylaxis continue to emphasize the tremendous potential of immunomodulator therapy in neonatology/perinatology. The current immunomodulators/immunotherapeutic agents with established/potential clinical applications in the perinatal period are reviewed.

Use of myeloid colony-stimulating factors in neonates with septicemia

Bacterial sepsis is a major cause of neonatal morbidity and mortality. Successful management of neonatal sepsis requires early diagnosis, appropriate antimicrobial treatment, and aggressive intensive care. However, even when steps are taken appropriately, mortality rates can be high, particularly among certain subgroups, such as extremely preterm neonates and neonates with neutropenia. Multiple factors contribute to the increased susceptibility of neonates to infection, including developmental quantitative and qualitative neutrophil defects. Studies of infected animal and human neonates suggest that the use of recombinant human granulocyte colony stimulating factor (rhG-CSF) or recombinant human granulocyte macrophage colony stimulating factor (rhGM-CSF) can partially counterbalance these defects and thereby reduce morbidity and mortality. However, the body of clinical evidence is currently not sufficient to recommend rhG-CSF or rhGM-CSF administration confidently as routine adjunctive treatment for neonates with sepsis.

Administration of recombinant granulocyte colony-stimulating factor to neonates with septicemia: A meta-analysis

A meta-analysis was used to determine whether administering recombinant granulocyte colony-stimulating factor (rG-CSF) to neonates with bacterial septicemia reduces mortality. Five studies were identified, involving 73 rG-CSF recipients and 82 control subjects. Mortality was lower among the rG-CSF recipients (odds ratio, 0.17; CI, 0.03-0.70; P <.05). However, when the non-randomized studies were excluded, the P value was.13. For the subgroups "<2000 g" or "neutropenia," the P value was <.02. Thus the routine use of rG-CSF cannot be recommended for all neonates with sepsis.

A randomized, double-masked, placebo-controlled trial of recombinant granulocyte colony-stimulating factor administration to preterm infants with the clinical diagnosis of early-onset sepsis

OBJECTIVE

We performed a randomized, double-masked, parallel-groups, placebo-controlled trial of recombinant granulocyte colony-stimulating factor (rG-CSF) administration to 44 preterm neonates who had blood cultures obtained and antibiotics begun because of the clinical diagnosis of early-onset sepsis. Two primary outcome variables were tested 1) mortality and 2) development of nosocomial infections over the 2-week period after dosing.

DESIGN AND METHODS

The treatment group (n = 22) received 10 microgram/kg/day of intravenous rG-CSF once daily for 3 days and the placebo group (n = 22) received the same volume of a visually indistinguishable vehicle. Mortality and culture-proven nosocomial infections were recorded. Immediately before the first, second, and third doses, and again 10 days after the first dose, serum concentrations were determined for tumor necrosis factor-alpha, interleukin 6, granulocyte-macrophage colony stimulating factor, and G-CSF, and blood leukocyte counts, absolute neutrophil counts, immature/total neutrophil ratios, platelet counts, and hemoglobin concentrations were measured.

RESULTS

The treatment and placebo groups were of similar gestational age (29 +/- 3 vs 31 +/- 3 weeks) and birth weight (1376 +/- 491 vs 1404 +/- 508 g), and had similar Apgar scores and 24-hour Score for Neonatal Acute Physiology scores. The mortality rate was not different between treatment and placebo groups. However, the occurrence of a subsequent nosocomial infection was lower in the rG-CSF recipients (relative risk:.19; 95% confidence interval:.05-.78). rG-CSF treatment did not alter the serum concentrations of the cytokines measured (except for G-CSF). Serum G-CSF levels and blood neutrophil counts were higher in the treatment than in the placebo group 24 hours and 48 hours after dosing.

CONCLUSIONS

Administration of 3 daily doses of rG-CSF (10 microgram/kg/day) to premature neonates with the clinical diagnosis of early-onset sepsis did not improve mortality but was associated with acquiring fewer nosocomial infections over the subsequent 2 weeks.

A practical approach to evaluating and treating neutropenia in the neonatal intensive care unit

Neutropenia is a relatively common problem in the NICU, recognized in as many as 8% of patients at some time during their hospital stay. In most instances, neutropenia among NICU patients is of short duration and has little influence on outcome. In other cases it is prolonged and severe, and constitutes a serious antimicrobial defense deficiency. When a neonatologist discovers a low blood neutrophil count, choices must be made regarding further evaluation and treatment. The authors hope that the information provided in this article is useful in making these choices.

Effect of granulocyte and granulocyte macrophage colony stimulating factors (G-CSF and GM-CSF) on neonatal neutrophil functions

Although there are many studies on the effect of granulocyte and granulocyte-macrophage colony stimulating factors (G/GM-CSF) on adult neutrophil functions, there is little information regarding their influence on neonatal cells. We studied the in vitro effect of G/GM-CSF on neutrophil chemotaxis, polarization, and superoxide anion generation in 47 neonates compared with 35 adults. We found that G-CSF and GM-CSF significantly enhanced the chemotaxis of newborn infants' neutrophils, normalizing their chemotactic defect [from 35 +/- 7 cells/field (mean +/- SE) to 49 +/- 5 cells/field with G-CSF, p < 0.05 and to 55 +/- 4 cells/field with GM-CSF, p < 0.001]. It is notable that the maximal neutrophil response to the cytokines was observed particularly in the newborn infants with severe impairment in their chemotactic activity. Statistical analysis of the data showed a significant inverse correlation, which supported this observation (r = -0.6, p < 0.02 for G-CSF; r = -0.76, p < 0.001 for GM-CSF). The reduced polarization of neonatal compared with adult cells [71 +/- 5% versus 86 +/- 2% (mean +/- SE), p < 0.05], was corrected by CSF-priming (to 87 +/- 4% with G-CSF and to 92 +/- 2% with GM-CSF, p < 0.05). In addition, the neutrophil superoxide generation was significantly improved in both groups following the CSF-priming. GM-CSF and G-CSF gave comparable results in all functions studied except that GM-CSF improved superoxide release to a greater extent. This study shows a significant improvement of the neonatal neutrophil functions following in vitro CSF-priming and contributes to a better understanding of the neonatal neutrophil behavior when treated with G/GM-CSF.

Frequency, natural course, and outcome of neonatal neutropenia

OBJECTIVE

We studied the frequency, onset, duration, and prognosis of neutropenia in a neonatal hospital population to define subgroups of neonates who might benefit from cytokine therapy.

STUDY DESIGN

The study comprised of 2 parts: in a first retrospective study (I), clinical data of neonates with sepsis (n = 168) were analyzed; in a second retrospective and prospective study (II), clinical data of neonates with neutropenia (n = 131) were studied. In study I, the analysis focused on septic neonates with and without neutropenia, and in study II, on neutropenic neonates with and without primary infection. In the prospective part of study II, granulocyte colony-stimulating factor (G-CSF) plasma concentrations were analyzed in neutropenic neonates (n = 32).

RESULTS

Thirty-eight percent of septic neonates were neutropenic. Neutropenia lasted <24 hours in 75% of these patients. It was recorded before or on the day of the clinical onset of sepsis in 87% of patients. The overall incidence of neutropenia was 8.1%. Seventy-two percent of these neutropenic episodes occurred in patients without infection at the time of diagnosis of neutropenia. In the latter patients, the risk of infection secondary to neutropenia was 9%, affecting only premature neonates. Neutropenic episodes without infection were of longer duration and were accompanied by lower G-CSF plasma concentrations than were episodes associated with infection. The percentage of neutropenic episodes primarily associated with infection was higher in VLBW neonates than in term neonates. Likewise, the risk of infection secondary to neutropenia (27%) and the mortality attributable to infection and neutropenia (28%) were significantly higher than in term newborns.

CONCLUSION

Considering the priming time for induction of neutrophilia, G-CSF therapy in neonates presenting with severe bacterial infection and neutropenia may be too late. In contrast, neutropenic very low birth weight neonates without primary infection might benefit from prophylactic G-CSF treatment.neonatal sepsis, neutropenia, granulocyte colony-stimulating factor.

Hematopoietic growth factor levels in term and preterm infants

The problems of immunologic adaptation during the transitional period from intra- to extrauterine life are responsible for the physiologic immaturity of the immune function in newborn infants. In preterm neonates the immunodeficiency is more severe and prolonged and is associated with a higher incidence of infections and sepsis. Furthermore, due to immaturity of the hematologic system, anemia, thrombocytopenia, and neutropenia are frequently observed in very low birth weight infants. The dysregulation of cytokine and hematopoietic growth factor synthesis is an important contributory factor to the complex deficiency of immunologic and hematologic function in the neonate and may explain the reduced incidence of acute graft-versus-host disease observed after cord blood transplantation in children. Human milk is a rich source of most of the cytokines that are reduced in the neonate. Granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and erythropoietin are currently under evaluation in newborn infants with septic neutropenia or anemia of prematurity.

Is there an effect of immunoglobulins and G-CSF on neutrophil phagocytic activity in preterm infants?

The percentage of neutrophils phagocytosing group B streptococci (GBS) in vitro was determined in ten healthy preterm infants (< 32 weeks of gestation) and adult controls by using an acridine orange fluorescence whole blood assay. When GBS were opsonized with adult serum, no difference in phagocytic activity was found between both groups after 10 and 30 min (preterms: 40% and 68%, adults: 32% and 56%, respectively). Phagocytosis rates in preterm infants decreased significantly to 6% and 18% (at 10 and 30 min) when pool serum of preterm infants was used instead. Supplementation of the preterm serum with either intravenous immunoglobulin or IgM-enriched immunoglobulin did not change the results significantly. The addition of granulocyte colony-stimulating factor (G-CSF) accelerated phagocytosis significantly after 10 min, but did not increase the overall phagocytic activity after 30 min in either group. Hence the potential benefits of intravenous immunoglobulins and G-CSF in neonatal sepsis may not be attributable to an immediate increase in and direct effect on neutrophil phagocytic activity.

Neutropenia complicating Rh-hydrops fetalis: the effect of treatment with recombinant human granulocyte colony-stimulating factor (rhG-CSF)

Neutropenia is a less commonly encountered feature of Rh hemolytic disease of the newborn, and its management may be problematic. Two newborn infants with neutropenia complicating Rh incompatibility-induced hydrops fetalis were treated with intravenous recombinant human granulocyte colony-stimulating factor (rhG-CSF), 5 micrograms/kg/day for 5 days. Both patients responded to therapy with a rapid and persistent increase of their neutrophil counts to normal values. The treatment was well tolerated and no adverse clinical events were observed. rhG-CSF induces a significant increase in peripheral absolute neutrophil counts of neutropenic neonates with Rh hydrops fetalis and was well tolerated. The contribution of rhG-CSF to clinical recovery warrants further investigation.