Cinzia Auriti

CpG Drives Human Transitional B Cells to Terminal Differentiation and Production of Natural Antibodies

The receptor TLR9, recognizing unmethylated bacterial DNA (CpG), is expressed by B cells and plays a role in the maintenance of serological memory. Little is known about the response of B cells stimulated with CpG alone, without additional cytokines. In this study, we show for the first time the phenotypic modification, changes in gene expression, and functional events downstream to TLR9 stimulation in human B cell subsets. In addition, we demonstrate that upon CpG stimulation, IgM memory B cells differentiate into plasma cells producing IgM Abs directed against the capsular polysaccharides of Streptococcus pneumoniae. This novel finding proves that IgM memory is the B cell compartment responsible for the defense against encapsulated bacteria. We also show that cord blood transitional B cells, corresponding to new bone marrow emigrants, respond to CpG. Upon TLR9 engagement, they de novo express AID and Blimp-1, genes necessary for hypersomatic mutation, class-switch recombination, and plasma cell differentiation and produce Abs with anti-pneumococcal specificity. Transitional B cells, isolated from cord blood, have not been exposed to pneumococcus in vivo. In addition, it is known that Ag binding through the BCR causes apoptotic cell death at this stage of development. Therefore, the ability of transitional B cells to sense bacterial DNA through TLR9 represents a tool to rapidly build up the repertoire of natural Abs necessary for our first-line defense at birth.

Low Serum Levels of Mannose Binding Lectin Are a Risk Factor for Neonatal Sepsis

Mannose binding lectin (MBL) is a soluble pattern recognition receptor of innate immunity that binds a wide range of pathogens and exerts opsonic effects. We investigated the association between serum MBL levels and development of sepsis in infants admitted to neonatal intensive care units (NICUs). Serum MBL levels on admission were measured by enzyme-linked immunosorbent assay (ELISA) in 206 neonates consecutively admitted to an NICU of whom 138 did not develop hospital-acquired sepsis and 68 did. Of these 68, 40 had confirmed sepsis with positive blood cultures, 19 clinically suspected sepsis, with negative blood cultures, and nine had clinically suspected sepsis with blood culture yielding coagulase-negative staphylococci (CoNS). Serum MBL levels on admission were significantly lower in infants with sepsis [0.45 μg/mL; interquartile range (IQR) 0.09–1.68], particularly in those with confirmed sepsis (0.17 μg/mL; IQR 0.05–0.96), compared with infants without sepsis (1.45 μg/mL; IQR 0.43–3.52), and infants with CoNS-positive blood culture (1.70 μg/mL: IQR 0.85–3.60). After adjusting for duration of exposure gestational age (GA) and birth weight (BW), the association of low MBL levels with development of sepsis was maintained [odds ratio (OR) = 0.52; 95% confidence interval (CI): 0.36–0.75]. The measurement of serum MBL levels on admission in NICU may help to identify neonates at higher risk of developing sepsis.

Procalcitonin in detecting neonatal nosocomial sepsis

Objective To investigate the accuracy of procalcitonin (PCT) as a diagnostic marker of nosocomial sepsis (NS) and define the most accurate cut-off to distinguish infected from uninfected neonates. Setting Six neonatal intensive care units (NICUs). Patients 762 neonates admitted to six NICUs during a 28-month observational study for whom at least one serum sample was taken on admission. Main outcome measures Positive and negative predictive values at different PCT cut-off levels. Results The overall probability of an NS was doubled or more if PCT was >0.5 ng/ml. In very-low-birth-weight (VLBW) infants, a cut-off of >2.4 ng/ml gave a positive predictive value of NS near to 50% with a probability of a false-positive diagnosis of NS in about 10% of the patients. Conclusions In VLBW neonates, a serum PCT value >2.4 ng/ml prompts early empirical antibiotic therapy, while in normal-birth-weight infants, a PCT value ≤2.4 ng/ml carries a low risk of missing an NS.

Determinants of Nosocomial Infection in 6 Neonatal Intensive Care Units: An Italian Multicenter Prospective Cohort Study

BACKGROUND Nosocomial infections are still a major cause of morbidity and mortality among neonates admitted to neonatal intensive care units (NICUs). OBJECTIVE To describe the epidemiology of nosocomial infections in NICUs and to assess the risk of nosocomial infection related to the therapeutic procedures performed and to the clinical characteristics of the neonates at birth and at admission to the NICU, taking into account the time between the exposure and the onset of infection. DESIGN A multicenter, prospective cohort study. PATIENTS AND SETTING A total of 1,692 neonates admitted to 6 NICUs in Italy were observed and monitored for the development of nosocomial infection during their hospital stay. METHODS Data were collected on the clinical characteristics of the neonates admitted to the NICUs, their therapeutic interventions and treatments, their infections, and their mortality rate. The cumulative probability of having at least 1 infection and the cumulative probability of having at least 1 infection or dying were estimated. The hazard ratio (HR) for the first infection and the HR for the first infection or death were also estimated. RESULTS A total of 255 episodes of nosocomial infection were diagnosed in 217 neonates, yielding an incidence density of 6.9 episodes per 1,000 patient-days. The risk factors related to nosocomial infection in very-low-birth-weight neonates were receipt of continuous positive airway pressure (HR, 3.8 [95% confidence interval {CI}, 1.7-8.1]), a Clinical Risk Index for Babies score of 4 or greater (HR, 2.2 [95% CI, 1.4-3.4]), and a gestational age of less than 28 weeks (HR, 2.1 [95% CI, 1.2-3.8]). Among heavier neonates, the risk factors for nosocomial infection were receipt of parenteral nutrition (HR, 8.1 [95% CI, 3.2-20.5]) and presence of malformations (HR, 2.3 [95% CI, 1.5-3.5]). CONCLUSIONS Patterns of risk factors for nosocomial infection differ between very-low-birth-weight neonates and heavier neonates. Therapeutic procedures appear to be strong determinants of nosocomial infection in both groups of neonates, after controlling for clinical characteristics.

Role of mannose-binding lectin in nosocomial sepsis in critically ill neonates.

We investigated the association of mannose-binding lectin (MBL) serum levels with nosocomial sepsis (NS), their changes overtime during infection, their relation with pathogens, with the MBL2 genotype and their relationship with mortality. In a prospective observational study, we included 365 critically ill neonates: 261 had no infection and 104 had at least 1 septic event. The median MBL serum concentration was significantly lower in infected than in noninfected neonates (p < 0.001). Low MBL levels on admission increased the risk of infection, independently from gestational age and invasive procedures. The median peak MBL level during infection was higher than the median level on admission (p < 0.001) and was correlated with it (r(2) = 0.83, p < 0.001). Moreover, MBL levels on admission were not associated with death (OR = 0.80, 95% CI = 0.56-1.14, p = 0.21). Similarly, no association was found between MBL peak levels during infection and death among infected neonates (OR = 1.10, 95% CI = 0.78-1.57, p = 0.57). In 127 neonates (42 infected) genotyped for exon-1 and -221 promoter MBL2 variants, we did not find significant difference in the frequencies of MBL2 genotypes between infected and noninfected neonates. Moreover, no association was found between MBL2 genotypes and death.

Kabuki syndrome: clinical and molecular diagnosis in the first year of life

Objective To review the clinical and molecular genetic characteristics of 16 patients presenting a suspected diagnosis of Kabuki syndrome (KS) in the first year of life, to evaluate the clinical handles leading to a prompt diagnosis of KS in newborns. Clinical diagnosis of KS can be challenging during the first year of life, as many diagnostic features become evident only in subsequent years. Methods All patients were clinically investigated by trained clinical geneticists. A literature review was performed using the Pubmed online database and diagnostic criteria suggested by DYSCERNE–Kabuki Syndrome Guidelines (2010) were used (a European Network of Centres of Expertise for Dysmorphology, funded by the European Commission Executive Agency for Health and Consumers (DG Sanco), Project 2006122). Molecular analysis of the known causative genes of KS, KMT2D/MLL2 and KDM6A, was performed through MiSeq-targeted sequencing platform. All mutations identified were validated by Sanger sequencing protocols. Results Mutations in KMT2D gene were identified in 10/16 (62%) of the patients, whereas none of the patients had KDM6A mutations. Facial dysmorphisms (94%), feeding difficulties (100%) and hypotonia (100%) suggested the clinical diagnosis of KS. No significative differences in terms of facial features were noticed between mutation positive and negative patients of the cohort. Brachydactyly, joint laxity and nail dysplasia were present in about 80% of the patients. Other congenital anomalies were most commonly present in the mutated group of patients, including left-sided cardiac abnormalities, skeletal, renal and anorectal malformations and hypertricosis. Conclusions We present an overview of patients with KS diagnosed during the first year of life. Early diagnosis is serviceable in terms of clinical management and for targeted genetic counselling.

A polymorphism in the macrophage migration inhibitory factor promoter is associated with bronchopulmonary dysplasia.

Bronchopulmonary dysplasia (BPD) is a common adverse outcome of prematurity, causing severe morbidity and mortality. The cytokine macrophage migration inhibitory factor (MIF) has been recently shown to favor murine fetal lung development. In this prospective study, we evaluate the expression of MIF in the lung and in the serum of preterm infants (n = 50) and investigate whether the −173 G/C MIF promoter polymorphism is associated with the risk of BPD (n = 103). MIF was highly expressed in lung tissue from preterm infants. Serum MIF levels were measured by ELISA at d 1 after birth. MIF levels were increased [median (interquartile range), 71.01 (44.9–162.3) ng/mL], particularly in those infants with RDS [110.4 (59.4–239.2) ng/mL] compared with healthy adults [2.4 (1.2–5.0) ng/mL], (p < 0.001). The MIF −173*C allele, which predisposes to higher MIF production, was associated with a lower incidence of BPD (OR, 0.2; 95% CI, 0.04–0.93), independently from mechanical ventilation and oxygen exposure (p = 0.03). In conclusion, these data show that MIF expression is increased in lung and serum of preterm infants and suggest that the high producing MIF −173*C allele may be a protective factor for BPD.

Congenital Varicella Syndrome: Still a Problem?

A woman contracted chickenpox in the 12th week of gestation. Her general practitioner and later the consultant obstetrician warned her about the small risk of giving birth to a disabled child. She decided to continue the pregnancy without undergoing invasive tests to diagnose fetal intrauterine infection. Symptoms of congenital varicella syndrome (CVS) were detected by ultrasound in the 29th and 34th weeks of gestation. On admission to hospital, the baby was not considered infectious and was not isolated because polymerase chain reaction analysis to detect varicella zoster virus (VZV) DNA in the blood, cerebrospinal fluid, saliva, skin scrapings and feces gave negative results. He was also not separated from his mother. The mother was without clinical complications. Varicella during pregnancy may result in VZV transmission to the fetus or newborn. Intrauterine VZV infection in the first 28 weeks of gestation may result in CVS with limb deformities, brain abnormalities and mental retardation. Usually the newborn is not infectious, and therapy and isolation are unnecessary. When the mother catches the infection in the second trimester, the newborn may manifest shingles in the first 2 years of life. A maternal rash erupting 5 days before to 2 days after delivery is frequently associated with clinically severe varicella in the newborn, leading to high mortality if untreated. Then the newborn is infectious and must be isolated. This case report underlines the need for expert medical counseling for women who contract chickenpox at any time during pregnancy. It also underlines the importance of immunizing susceptible women of childbearing age before they become pregnant.

Association between mannose-binding lectin gene polymorphisms and necrotizing enterocolitis in preterm infants.

Objectives: The aim of the present study was to evaluate whether polymorphisms of the mannose-binding lectin (MBL-2) gene and MBL serum levels on admission to neonatal intensive care unit are associated with necrotizing enterocolitis (NEC) in preterm infants and to verify MBL expression in NEC bowels. Methods: In this retrospective cohort study, 107 neonates (41 with NEC and 66 controls) were included. MBL-2 genotyping for the promoter polymorphism −221 and for the exon 1 variant alleles at codons 52, 54, and 57 was performed. MBL levels were determined by enzyme-linked immunosorbent assay in 55 infants. Immunohistochemical staining for MBL expression was performed on bowel specimens. The main study outcome was severe NEC (Bell stages II/III). Results: The −221 Y allele and the MBL-2 YY genotype were more frequent in neonates with severe NEC than in controls (P = 0.04 and P = 0.004, respectively). In the multivariate analysis, the MBL-2 YA/YA genotype was associated with NEC (odds ratio = 3.03, 95% confidence interval 1.13%–8.13%, P = 0.024). Neonates with NEC had MBL level on admission >400 ng/mL more frequently than controls (P = 0.043). Among neonates with severe NEC, the deceased neonates were carriers of high or intermediate producing MBL-2 genotypes (P = 0.035). Finally, MBL was highly expressed in intestinal tissue from infants with NEC. Conclusions: MBL-2 genotypes associated with high MBL serum levels represent a risk factor for NEC. This finding, together with the MBL expression in bowel tissue, supports a role for MBL in the pathogenesis of NEC.

Remission of infantile generalized myofibromatosis after interferon alpha therapy.

Infantile myofibromatosis is the most common fibrous tumor of infancy. Solitary or generalized myofibromas without visceral involvement usually regress within a few months. The multifocal disease infantile generalized myofibromatosis, with visceral involvement, is associated with a significant mortality due to the effect of tumors on vital organs. We report a case of infantile generalized myofibromatosis with visceral involvement, including 2 right atrium tumors. The infant expressed high circulating vascular endothelial growth factor and fibroblast growth factor-2 levels, and interferon alpha-2b was started as antiangiogenic treatment, aimed at triggering regression of the life-threatening cardiac lesions. The tumors regressed and vascular endothelial growth factor and fibroblast growth factor-2 levels were reduced after treatment discontinuation.