Rose M. Viscardi

Inflammatory markers in intrauterine and fetal blood and cerebrospinal fluid compartments are associated with adverse pulmonary and neurologic outcomes in preterm infants.

Recent evidence strongly implicates the inflammatory response to intrauterine infection in the pathogenesis of neonatal brain and lung injury. We hypothesized that lung and brain injury in preterm infants occurs during a common developmental window of vulnerability as the result of an inflammatory response in different compartments. To determine whether inflammatory markers in these compartments are associated with bronchopulmonary dysplasia (BPD) or cranial ultrasound (CUS) abnormalities in infants <33 wk gestation age (GA) and <1501 g birth weight, we analyzed placental pathology and serum and cerebrospinal fluid (CSF) IL-6, IL-1β, and tumor necrosis factor-α (TNF-α) concentrations in 276 infants. Logistic regressions were performed stratified by GA. Histologic chorioamnionitis was significantly associated with BPD in infants ≤28 wk GA (OR 3.6, p = 0.027). Maternal stage of chorioamnionitis significantly correlated with severity of BPD. Presence of a fetal inflammatory response indicated by fetal vasculitis or elevated cytokines was not associated with the development of BPD. Serum IL-6 ≥17 pg/mL was associated with an abnormal CUS in infants >28 wk GA (OR 3.36, p = 0.023) but not ≤28 wk GA. CSF concentrations of IL-6 ≥6.5 pg/mL and TNF-α ≥3 pg/mL were associated with abnormal CUS in infants ≤28 wk GA (IL-6 OR 3.0; TNF-α OR 3.5; p < 0.05 each case) but not ≥28 wk GA. These data suggest that in infants ≤28 wks GA, BPD may be initiated by inflammatory mediators in amniotic fluid, but brain injury may involve variations in the systemic inflammatory response.

Febrile Core Temperature Is Essential for Optimal Host Defense in Bacterial Peritonitis

ABSTRACT Fever, a nonspecific acute-phase response, has been associated with improved survival and shortened disease duration in infections, but the mechanisms of these beneficial responses are poorly understood. We previously reported that increasing core temperature of bacterial endotoxin (LPS)-challenged mice to the normal febrile range modified expression of tumor necrosis factor alpha (TNF-α), interleukin 1β (IL-1β), and IL-6, three cytokines critical to mounting an initial defense against microbial pathogens, but survival was not improved in the warmer animals. We speculated that our inability to show a survival benefit of optimized cytokine expression in the warmer animals reflected our use of LPS, a nonreplicating agonist, rather than an infection with viable pathogens. The objective of this study was to determine if increasing murine core temperature altered cytokine expression and improved survival in an experimental bacterial peritonitis model. We showed that housing mice at 35.5°C rather than 23°C increased core temperature from 36.5 to 37.5°C to 39.2 to 39.7°C, suppressed plasma TNF-α expression for the initial 48 h, delayed gamma interferon expression, improved survival, and reduced the bacterial load in mice infected with Klebsiella pneumoniae peritonitis. We showed that the reduced bacterial load was not caused by a direct effect on bacterial proliferation and probably reflected enhanced host defense. These data suggest that the increase in core temperature that occurs during bacterial infections is essential for optimal antimicrobial host defense.

Increased Activity of Interleukin-6 but not Tumor Necrosis Factor-α in Lung Lavage of Premature Infants is Associated with the Development of Bronchopulmonaiy Dysplasia

ABSTRACT: Although considerable evidence suggests that bronchopulmonary dysplasia (BPD) is the result of prolonged inflammation and impaired healing of the immature lung, the mediators that regulate inflammation in neonatal lung injury have not been completely elucidated. We examined whether the cytokines IL-6 and tumor necrosis factor-α (TNF) interact to modulate a cascade of cell-cell signaling events involved in inflammation contributing to the development of BPD. To determine the relative activities of these cytokines in neonatal lung injury, lung lavage samples were serially obtained from 1 to 28 d from 11 infants with self-limited respiratory distress syndrome (RDS), 19 infants with evolving BPD, and 10 control infants ventilated for nonpulmonary reasons. On the first day of life, there were no differences in antigenic IL-6 concentrations in lavage fluids among the BPD, RDS, and control groups, but IL-6 activity determined by the 7TD1 proliferation assay was 15-fold and 6.6-fold higher in lung lavage of infants who developed BPD compared with activities in lavage from control and RDS infants, respectively (control, 49.4 ± 17.6; RDS, 117.3 ± 59.6; BPD, 779.5 ± 212.6 ± 103 hybridoma units/L, mean ± SEM, p = 0.02). This suggests that pathways for inactivating or inhibiting IL-6 that may be present in the lungs of RDS and control infants may be deficient in BPD infants. IL-6 activity remained elevated in lavage of BPD infants for the first 2 wk and declined to low levels by d 28. There were no differences among groups on the first day of life for TNF antigen concentration or TNF activity determined by the L929 bioassay. Detectable but low TNF activity was found in BPD samples, with peak activity found in d-14 samples. Differences in complex interactions among these and other cytokines with their receptors and inhibitors may predispose some infants with RDS to develop BPD.

Mycoplasma and Ureaplasma.

Several species of mycoplasmas and ureaplasmas are now well-known human pathogens responsible for a broad array of conditions involving the respiratory and urogenital tracts of adults and infants and they may cause severe systemic disease in susceptible hosts. Greater attention is now being given to these organisms in diagnostic microbiology largely as a result of improved methods for their laboratory detection made possible by powerful molecular-based techniques. PCR-based technology can be employed for primary detection in clinical specimens as well as to characterize the organisms genetically for epidemiological purposes. For slow-growing species such as Mycoplasma pneumoniae and Mycoplasma genitalium, molecular-based detection is the only practical means for microbiological diagnosis. Most molecular-based methods used for detection and characterization of conventional bacteria have now been applied to these organisms and some methods seem to work better than others. A complete genome sequence is now available for at least one strain of all of the important human pathogens in the Mycoplasma and Ureaplasma genera. Information gained from genome analyses and improvements in efficiency of DNA sequencing are expected to advance the field of molecular detection and genotyping significantly over the next few years. This chapter provides a summary and critical review of methods suitable for detection and characterization of mycoplasmas and ureaplasmas of humans with emphasis on molecular genotypic techniques.

Inflammatory Cytokine mRNAs in Surgical Specimens of Necrotizing Enterocolitis and Normal Newborn Intestine

Coagulation necrosis, inflammation, and hemorrhage are pathologic hallmarks of necrotizing enterocolitis (NEC). Because cytokines are peptides that mediate inflammatory cell recruitment and amplify the immune response, several of the inflammatory cytokines have been implicated in NEC. We hypothesized that mRNA levels for the interrelated cytokines interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), IL-6, and the neutrophil chemotactic factor IL-8 would be increased in NEC and would be associated with the presence of inflammation. In this study, we determined the relative levels and localization of mRNA for these cytokines in surgical pathology archival intestinal tissue from 29 premature infants with acute NEC and 15 control infants with congenital intestinal malformations using a novel quantitative in situ hybridization technique. Compared with controls, there were higher IL-1 beta mRNA levels in full-thickness sections and higher TNF-alpha mRNA levels in full-thickness and mucosa sections of acute NEC samples, suggesting a potential role for these cytokines in the pathogenesis of local inflammation in NEC. IL-6 and IL-8 mRNA levels were similar in samples of control and acute NEC cases. Analysis of covariance including all subjects showed that the presence of acute inflammation was associated with increased IL-1 beta mRNA levels in mucosa (P = .035) and increased IL-8 in full-thickness sections (P = .005) and mucosa (P = .01). In four of five NEC cases in which intestinal specimens were available from reanastomosis surgery, cytokine mRNA levels decreased to low or undetectable levels. These data suggest that the inflammatory cytokines are involved in neutrophil recruitment and augmentation of the inflammatory response in neonatal intestine.

Effects of hypothermia and hyperthermia on cytokine production by cultured human mononuclear phagocytes from adults and newborns.

We have shown previously that febrile range temperatures modify cytokine production by adult macrophages. In this study, we compared the effects of moderate hyperthermia and hypothermia on the kinetics of lipopolysaccharide (LPS)-induced cytokine expression in monocytes and macrophages of newborns and adults. During culture at 40 degrees C, the initial rates of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) secretion were preserved, but the duration of secretion was shorter than the duration at 37 degrees C. TNF-alpha and IL1-beta concentrations in 24-h 40 degrees C culture supernatants were reduced 18%-50%. IL-6 concentration in 24-h 40 degrees C cultures was reduced 26%-29% in all cells except adult macrophages. At 32 degrees C, changes in early (2 h) and sustained (24 h) cytokine expression were reversed compared with those caused by hyperthermia. Culturing adult macrophages at 32 degrees C blunted early secretion of TNF-alpha and IL-6 by 69% and 65%, respectively, and increased TNF-alpha concentration at 24 h by 48% compared with levels at 37 degrees C. In adult monocytes cultured at 32 degrees C, early IL-6 and IL-1 beta secretion was decreased 64% and 51%, respectively. We speculate that the burst/suppression cytokine profile at febrile temperatures might enhance early activation of host defenses and prevent prolonged exposure to potentially cytotoxic cytokines. Hypothermia, on the other hand, may worsen outcome in infections by delaying and prolonging cytokine production.

Ureaplasma Species: Role in Diseases of Prematurity

There is accumulating epidemiologic and experimental evidence that intrauterine or postnatal infection with Ureaplasma species is a significant risk factor for adverse pregnancy outcomes and complications of extreme preterm birth such as bronchopulmonary dysplasia and intraventricular hemorrhage. In a cohort of very low birth weight infants, Ureaplasma spp were detected by culture or polymerase chain reaction in respiratory secretions, blood, or cerebrospinal fluid of almost half of the subjects, suggesting that this organism is the most common pathogen affecting this population. This review summarizes the evidence supporting the hypothesis that Ureaplasma-mediated inflammation in different compartments (intrauterine, lung, blood, or brain) during a common developmental window of vulnerability contributes to preterm labor and lung and brain injury. Appropriate methods for detecting these fastidious organisms and potential strategies to prevent or ameliorate the effects of Ureaplasma infection are discussed.

Ureaplasma urealyticum respiratory tract colonization is associated with an increase in interleukin 1-beta and tumor necrosis factor alpha relative to interleukin 6 in tracheal aspirates of preterm infants

OBJECTIVE To determine whether Ureaplasma urealyticum respiratory tract colonization in very low birth weight infants during the first week of life is associated with changes in tracheal aspirate concentrations of the cytokines interleukin 1-beta (IL-1-beta), tumor necrosis factor alpha (TNF-alpha) and IL-6. METHODS Infants with birth weights < or =1250 g were prospectively enrolled. Samples were obtained from the endotracheal tube or nasopharynx on Day 1 and again between Days 7 and 10 for U. urealyticum culture. The concentrations of IL-1-beta, TNF-alpha and IL-6 were measured in tracheal aspirate samples by enzyme-linked immunosorbent assay. RESULTS There were 18 positive cultures for U. urealyticum from 15 of 96 infants (15.6%). IL-1-beta in tracheal aspirates expressed as concentration per volume or as a ratio of IL-1-beta to IL-6 were 7- and 14.9-fold higher, respectively, in Ureaplasma-positive infants than in Ureaplasma-negative infants (P < 0.05). The TNF-alpha/IL-6 ratio was 18.9 and 15.5 times higher in the Ureaplasma-positive aspirates than in the Ure aplasma-negative aspirates on Day 1 and Days 7 to 10 (P < 0.05). Concentrations of IL-1-beta and TNF-alpha were significantly correlated on Day 1 and Days 7 to 10. Although there was no clinical association demonstrated between U. urealyticum colonization and the development of bronchopulmonary dysplasia (BPD) in this study, infants who developed BPD had significantly higher IL-1-beta concentrations and ratios of IL-1-beta to IL-6 in Day 1 aspirates than infants who did not develop BPD. Conclusions. Isolation of U. urealyticum from the respiratory tract is associated with increased IL-1-beta concentrations and IL-1-beta-IL-6 ratios on Day 1 and increased TNF-alpha-IL-6 ratios on Days 1 and 7 to 10 in tracheal aspirates of colonized infants. Infants who developed BPD had higher IL-1-beta concentrations and IL-1-beta-IL-6 ratios, suggesting that these may be early markers of lung inflammation.

Infant neurodevelopment following fetal growth restriction: Relationship with antepartum surveillance parameters

To evaluate the relationship between fetal Doppler parameters, biophysical profile score (BPP) and neurodevelopmental delay at 2 years of corrected age in infants who had been growth‐restricted in utero.

Ureaplasma species: role in neonatal morbidities and outcomes

The genital mycoplasma species, Ureaplasma parvum and Ureaplasma urealyticum are the most common organisms isolated from infected amniotic fluid and placentas, and they contribute to adverse pregnancy outcomes including preterm birth and neonatal morbidities. In our institution, almost half of the preterm infants of less than 32 weeks gestation are Ureaplasma-positive in one or more compartment (respiratory, blood and/or cerebrospinal fluid), indicating that these organisms are the most common pathogens affecting this population. This review will focus on the compelling epidemiological and experimental evidence linking perinatal Ureaplasma species exposure to important morbidities of prematurity, such as bronchopulmonary dysplasia, intraventricular haemorrhage and necrotising enterocolitis.