Eric Giannoni

Estradiol and Progesterone Strongly Inhibit the Innate Immune Response of Mononuclear Cells in Newborns

ABSTRACT Newborns are particularly susceptible to bacterial infections due to qualitative and quantitative deficiencies of the neonatal innate immune system. However, the mechanisms underlying these deficiencies are poorly understood. Given that fetuses are exposed to high concentrations of estradiol and progesterone during gestation and at time of delivery, we analyzed the effects of these hormones on the response of neonatal innate immune cells to endotoxin, bacterial lipopeptide, and Escherichia coli and group B Streptococcus, the two most common causes of early-onset neonatal sepsis. Here we show that at concentrations present in umbilical cord blood, estradiol and progesterone are as powerful as hydrocortisone for inhibition of cytokine production by cord blood mononuclear cells (CBMCs) and newborn monocytes. Interestingly, CBMCs and newborn monocytes are more sensitive to the effects of estradiol and progesterone than adult peripheral blood mononuclear cells and monocytes. This increased sensitivity is associated with higher expression levels of estrogen and membrane progesterone receptors but is independent of a downregulation of Toll-like receptor 2 (TLR2), TLR4, and myeloid differentiation primary response gene 88 in newborn cells. Estradiol and progesterone mediate their anti-inflammatory activity through inhibition of the NF-κB pathway but not the mitogen-activated protein kinase pathway in CBMCs. Altogether, these results suggest that elevated umbilical cord blood concentrations of estradiol and progesterone acting on mononuclear cells expressing high levels of steroid receptors contribute to impair innate immune responses in newborns. Therefore, intrauterine exposure to estradiol and progesterone may participate in increasing susceptibility to infection during the neonatal period.

Prospective monitoring of cefepime in intensive care unit adult patients

IntroductionCefepime has been associated with a greater risk of mortality than other beta-lactams in patients treated for severe sepsis. Hypotheses for this failure include possible hidden side-effects (for example, neurological) or inappropriate pharmacokinetic/pharmacodynamic (PK/PD) parameters for bacteria with cefepime minimal inhibitory concentrations (MIC) at the highest limits of susceptibility (8 mg/l) or intermediate-resistance (16 mg/l) for pathogens such as Enterobacteriaceae, Pseudomonas aeruginosa and Staphylococcus aureus. We examined these issues in a prospective non-interventional study of 21 consecutive intensive care unit (ICU) adult patients treated with cefepime for nosocomial pneumonia.MethodsPatients (median age 55.1 years, range 21.8 to 81.2) received intravenous cefepime at 2 g every 12 hours for creatinine clearance (CLCr) ≥ 50 ml/min, and 2 g every 24 hours or 36 hours for CLCr < 50 ml/minute. Cefepime plasma concentrations were determined at several time-points before and after drug administration by high-pressure liquid chromatography. PK/PD parameters were computed by standard non-compartmental analysis.ResultsSeventeen first-doses and 11 steady states (that is, four to six days after the first dose) were measured. Plasma levels varied greatly between individuals, from two- to three-fold at peak-concentrations to up to 40-fold at trough-concentrations. Nineteen out of 21 (90%) patients had PK/PD parameters comparable to literature values. Twenty-one of 21 (100%) patients had appropriate duration of cefepime concentrations above the MIC (T>MIC ≥ 50%) for the pathogens recovered in this study (MIC ≤ 4 mg/l), but only 45 to 65% of them had appropriate coverage for potential pathogens with cefepime MIC ≥ 8 mg/l. Moreover, 2/21 (10%) patients with renal impairment (CLCr < 30 ml/minute) demonstrated accumulation of cefepime in the plasma (trough concentrations of 20 to 30 mg/l) in spite of dosage adjustment. Both had symptoms compatible with non-convulsive epilepsy (confusion and muscle jerks) that were not attributed to cefepime-toxicity until plasma levels were disclosed to the caretakers and symptoms resolved promptly after drug arrest.ConclusionsThese empirical results confirm the suspected risks of hidden side-effects and inappropriate PK/PD parameters (for pathogens with upper-limit MICs) in a population of ICU adult patients. Moreover, it identifies a safety and efficacy window for cefepime doses of 2 g every 12 hours in patients with a CLCr ≥ 50 ml/minute infected by pathogens with cefepime MICs ≤ 4 mg/l. On the other hand, prompt monitoring of cefepime plasma levels should be considered in case of lower CLCr or greater MICs.

Novel FOXF1 Mutations in Sporadic and Familial Cases of Alveolar Capillary Dysplasia with Misaligned Pulmonary Veins Imply a Role for its DNA Binding Domain

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a rare and lethal developmental disorder of the lung defined by a constellation of characteristic histopathological features. Nonpulmonary anomalies involving organs of gastrointestinal, cardiovascular, and genitourinary systems have been identified in approximately 80% of patients with ACD/MPV. We have collected DNA and pathological samples from more than 90 infants with ACD/MPV and their family members. Since the publication of our initial report of four point mutations and 10 deletions, we have identified an additional 38 novel nonsynonymous mutations of FOXF1 (nine nonsense, seven frameshift, one inframe deletion, 20 missense, and one no stop). This report represents an up to date list of all known FOXF1 mutations to the best of our knowledge. Majority of the cases are sporadic. We report four familial cases of which three show maternal inheritance, consistent with paternal imprinting of the gene. Twenty five mutations (60%) are located within the putative DNA‐binding domain, indicating its plausible role in FOXF1 function. Five mutations map to the second exon. We identified two additional genic and eight genomic deletions upstream to FOXF1. These results corroborate and extend our previous observations and further establish involvement of FOXF1 in ACD/MPV and lung organogenesis.

Population pharmacokinetic study of gentamicin in a large cohort of premature and term neonates

AIM This study aims to investigate the clinical and demographic factors influencing gentamicin pharmacokinetics in a large cohort of unselected premature and term newborns and to evaluate optimal regimens in this population. METHODS All gentamicin concentration data, along with clinical and demographic characteristics, were retrieved from medical charts in a Neonatal Intensive Care Unit over 5 years within the frame of a routine therapeutic drug monitoring programme. Data were described using non-linear mixed-effects regression analysis ( nonmem®). RESULTS A total of 3039 gentamicin concentrations collected in 994 preterm and 455 term newborns were included in the analysis. A two compartment model best characterized gentamicin disposition. The average parameter estimates, for a median body weight of 2170 g, were clearance (CL) 0.089 l h(-1) (CV 28%), central volume of distribution (Vc ) 0.908 l (CV 18%), intercompartmental clearance (Q) 0.157 l h(-1) and peripheral volume of distribution (Vp ) 0.560 l. Body weight, gestational age and post-natal age positively influenced CL. Dopamine co-administration had a significant negative effect on CL, whereas the influence of indomethacin and furosemide was not significant. Both body weight and gestational age significantly influenced Vc . Model-based simulations confirmed that, compared with term neonates, preterm infants need higher doses, superior to 4 mg kg(-1) , at extended intervals to achieve adequate concentrations. CONCLUSIONS This observational study conducted in a large cohort of newborns confirms the importance of body weight and gestational age for dosage adjustment. The model will serve to set up dosing recommendations and elaborate a Bayesian tool for dosage individualization based on concentration monitoring.

High expression levels of macrophage migration inhibitory factor sustain the innate immune responses of neonates

Significance During pregnancy, high circulating levels of adenosine and prostaglandins reduce the ability of fetal immune cells to mount powerful proinflammatory responses. In contrast, newborns express 10-fold higher levels of the proinflammatory immune regulator migration inhibitory factor (MIF) compared with adults. MIF sustains cell activation and cytokine production and counterregulates adenosine and prostaglandin E2-mediated immunosuppression in newborn monocytes. Yet excessive MIF expression during an established infection worsens the outcome of newborn mice. Thus, we identify a unique role for MIF in regulating neonatal innate immune responses and propose that MIF has a protective role to reduce susceptibility to infection during the neonatal period but may favor uncontrolled inflammation during sepsis, leading to adverse outcomes. The vulnerability to infection of newborns is associated with a limited ability to mount efficient immune responses. High concentrations of adenosine and prostaglandins in the fetal and neonatal circulation hamper the antimicrobial responses of newborn immune cells. However, the existence of mechanisms counterbalancing neonatal immunosuppression has not been investigated. Remarkably, circulating levels of macrophage migration inhibitory factor (MIF), a proinflammatory immunoregulatory cytokine expressed constitutively, were 10-fold higher in newborns than in children and adults. Newborn monocytes expressed high levels of MIF and released MIF upon stimulation with Escherichia coli and group B Streptococcus, the leading pathogens of early-onset neonatal sepsis. Inhibition of MIF activity or MIF expression reduced microbial product-induced phosphorylation of p38 and ERK1/2 mitogen-activated protein kinases and secretion of cytokines. Recombinant MIF used at newborn, but not adult, concentrations counterregulated adenosine and prostaglandin E2-mediated inhibition of ERK1/2 activation and TNF production in newborn monocytes exposed to E. coli. In agreement with the concept that once infection is established high levels of MIF are detrimental to the host, treatment with a small molecule inhibitor of MIF reduced systemic inflammatory response, bacterial proliferation, and mortality of septic newborn mice. Altogether, these data provide a mechanistic explanation for how newborns may cope with an immunosuppressive environment to maintain a certain threshold of innate defenses. However, the same defense mechanisms may be at the expense of the host in conditions of severe infection, suggesting that MIF could represent a potential attractive target for immune-modulating adjunctive therapies for neonatal sepsis.

Prospective Determination of Plasma Imipenem Concentrations in Critically Ill Children

ABSTRACT Plasma imipenem concentrations were measured in 19 critically ill children (median age, 0.8 year; range, 0.02 to 12.9 years). Wide interindividual variations (2 to 4× at peak and >10× at trough concentrations) resulted in unpredictable plasma levels in several children. To avoid subtherapeutic drug levels, we recommend treatment with at least 100 mg/kg of body weight/day of imipenem-cilastatin for critically ill children requiring such therapy.

Pitfalls in Cefepime Titration from Human Plasma: Plasma- and Temperature-Related Drug Degradation In Vitro

ABSTRACT While developing a high-pressure liquid chromatography assay for cefepime in plasma, we observed significant drug degradation at 20 and 37°C but not at 4°C. This plasma-related degradation persisted after protein removal. This warrants caution regarding cefepime assays for pharmacokinetic and pharmacodynamic studies of cefepime in vitro and in vivo.

Epidemiology of blood culture-proven bacterial sepsis in children in Switzerland: a population-based cohort study

BACKGROUND Sepsis is a leading cause of childhood mortality worldwide. We assessed population-based incidence and outcomes of blood culture-proven bacterial sepsis in children in Switzerland. METHODS We did a multicentre, prospective, cohort study at ten paediatric hospitals in Switzerland. We included neonates and children younger than 17 years with blood culture-proven bacterial sepsis. Children were eligible if they met criteria for systemic inflammatory response syndrome-according to 2005 paediatric consensus definition- at the time of blood culture sampling. Incidence was calculated by dividing the number of annual sepsis episodes in the study for the years 2012-15 by the end-of-year resident paediatric population in Switzerland. The primary outcome was in-hospital mortality in the first 30 days after sepsis onset. FINDINGS Between Sept 1, 2011, and Dec 31, 2015, we enrolled 1096 children to our study. Of 1181 episodes of blood culture-proven bacterial sepsis, 382 (32%) occurred in 379 previously healthy children, 402 (34%) in 391 neonates, and 397 (34%) in 341 children with comorbidities. Incidence was 25·1 cases per 100 000 (95% CI 23·8-26·4) in children and 146·0 cases per 100 000 (133·2-159·6) in neonates. Central line-associated bloodstream infections and primary bloodstream infections accounted for 569 (48%) of 1181 episodes, and organ dysfunction was present in 455 (39%) of 1181 episodes. Escherichia coli (242 of 1181 [20%]), Staphylococcus aureus (177 of 1181 [15%]), coagulase-negative staphylococci (135 of 1181 [11%]), and Streptococcus pneumoniae (118 of 1181 [10%]) were the most prevalent pathogens in our study, accounting for 57% of episodes. The overall case-fatality ratio was 7% (82 of 1181 episodes; 95% CI 5·6-8·6), and it was higher in neonates (11%, 45 of 402 episodes; 8·4-14·8; adjusted odds ratio [OR] 4·41, 95% CI 1·75-11·1) and children with comorbidities (7%, 27 of 397 episodes; 4·6-9·9; OR 4·97, 1·84-13·4) compared with previously healthy children (3%, ten of 382 episodes; 1·3-4·9). The case-fatality ratio was 1% (five of 726 episodes [95% CI 0·3-1·7]) for children without organ dysfunction, which increased to 17% (77 of 455 episodes [13·7-20·8]) when organ dysfunction was present (adjusted OR 4·84, 95% CI 1·40-16·7). INTERPRETATION The burden of blood culture-proven bacterial sepsis on child health remains considerable. We recorded key differences in predominant organisms, severity, and outcome between neonates, previously healthy children, and children with comorbidities. Although for most episodes of blood culture-proven bacterial sepsis, no organ dysfunction was seen, presence of organ dysfunction was strongly associated with mortality. FUNDING Swiss National Science Foundation, Swiss Society of Intensive Care, Bangerter Foundation, Vinetum and Borer Foundation, and Foundation for the Health of Children and Adolescents.

Incidence and Outcome of Group B Streptococcal Sepsis in Infants in Switzerland

The incidence and outcome of group B streptococcal (GBS) sepsis were assessed prospectively between September 2011 and February 2015 in all tertiary care pediatric hospitals of Switzerland. We describe a low incidence of GBS early-onset sepsis (0.12/1000 livebirths) and a predominance of GBS late-onset sepsis (0.36/1000 livebirths), a pattern that has not been reported in other countries.

Variation in current management of term and late-preterm neonates at risk for early-onset sepsis: an international survey and review of guidelines

Background: Uncertainty about the presence of infection results in unnecessary and prolonged empiric antibiotic treatment of newborns at risk for early-onset sepsis (EOS). This study evaluates the impact of this uncertainty on the diversity in management. Methods: A web-based survey with questions addressing management of infection risk-adjusted scenarios was performed in Europe, North America, and Australia. Published national guidelines (n = 5) were reviewed and compared with the results of the survey. Results: 439 Clinicians (68% were neonatologists) from 16 countries completed the survey. In the low-risk scenario, 29% would start antibiotic therapy and 26% would not, both groups without laboratory investigations; 45% would start if laboratory markers were abnormal. In the high-risk scenario, 99% would start antibiotic therapy. In the low-risk scenario, 89% would discontinue antibiotic therapy before 72 hours. In the high-risk scenario, 35% would discontinue therapy before 72 hours, 56% would continue therapy for 5–7 days, and 9% for more than 7 days. Laboratory investigations were used in 31% of scenarios for the decision to start, and in 72% for the decision to discontinue antibiotic treatment. National guidelines differ considerably regarding the decision to start in low-risk and regarding the decision to continue therapy in higher risk situations. Conclusions: There is a broad diversity of clinical practice in management of EOS and a lack of agreement between current guidelines. The results of the survey reflect the diversity of national guidelines. Prospective studies regarding management of neonates at risk of EOS with safety endpoints are needed.