Tumor necrosis factor-alpha allele lymphotoxin-alpha+250 is associated with the presence and severity of placental inflammation among preterm births

Genetics of bronchopulmonary dysplasia: An update

Bronchopulmonary dysplasia (BPD) is a multi-factorial disease that results from multiple clinical factors, including lung immaturity, mechanical ventilation, oxidative stress, pulmonary congestion due to increasing cardiac blood shunting, nutritional and immunological factors. Twin studies have indicated that susceptibility to BPD can be strongly inherited in some settings. Studies have reported associations between common genetic variants and BPD in preterm infants. Recent genomic studies have highlighted a potential role for molecular pathways involved in inflammation and lung development in affected infants. Rare mutations in genes encoding the lipid transporter ATP-binding cassette, sub-family A, member 3 (ABCA3 gene) which is involved in surfactant synthesis in alveolar type II cells, as well as surfactant protein B (SFTPB) and C (SFTPC) can also result in severe form of neonatal-onset interstitial lung diseases and may also potentially affect the course of BPD. This chapter summarizes the current state of knowledge on the genetics of BPD.

Mononuclear leukocyte infiltrate in extraplacental membranes and preterm delivery

Large numbers of polymorphonuclear leukocytes in the amnion and chorion define histological chorioamnionitis (HCA), a condition linked to spontaneous preterm delivery (PTD). Less is known about placental patterns of mononuclear leukocyte (MNL) density and PTD. In this prospective study (1998-2004), women were sampled from 52 clinics in 5 Michigan communities and enrolled at 16-27 weeks' gestation. HCA and MNL distributions in delivered placentas were evaluated microscopically in a subcohort (290 preterm, 823 term). Midpregnancy biomarkers from maternal blood (i.e., C-reactive protein (CRP), corticotropin-releasing hormone, and cytokines) were compared among term and PTD subjects grouped by presence/absence of HCA and high MNL density. A density of more than 10 MNLs per high-power field in the chorion of the membrane roll, referred to as MNL-CMR, was associated with medically indicated PTD (odds ratio = 2.2, 95% confidence interval: 1.3, 3.6) and spontaneous PTD (odds ratio = 2.5, 95% confidence interval: 1.7, 3.7). Associations persisted after removal of women with HCA-positive placentas, abruption, hypertensive disorders, or obesity. HCA-associated PTD showed higher CRP and cytokine levels. MNL-CMR-associated PTD showed higher CRP and corticotropin-releasing hormone levels. These data suggest that an MNL infiltrate in the chorion of the membrane roll marks PTD pathways that are distinct from HCA and not entirely explained by pregnancy complications.

Genetic factors that influence short-term neurodevelopmental outcome in term hypoxic-ischaemic encephalopathic neonates

It is difficult to predict outcome in neonates that experience perinatal hypoxic ischaemia. Morbidity and mortality may be affected by genetic factors that augment inflammatory and coagulative responses. This prospective study analysed the effects of proinflammatory cytokine gene polymorphisms (tumour necrosis factor-α [TNFA] 308G>A and interleukin-6 [IL6] 174G>C) and prothrombotic factor gene mutations (prothrombin G20210A, factor V Leiden G1691A and methylenetetra hydrofolate reductase [MTHFR] C677T) on the early neurological prognosis in 40 term hypoxic ischaemic encephalopathic neonates. There were significant relationships for Sarnat and Sarnat staging with electroencephalographic findings, transfontanelle ultrasound (US) results, early neonatal outcome and neurological morbidity. Genetic mutations in the prothrombotic proteins, the TNFA 308G>A polymorphism and the cerebrospinal fluid levels of TNF-α protein were not related to clinical stage, electroencephalography, transfontanelle US or neurological status at discharge or at postnatal months 6 and 12. The IL6 174GC genotype demonstrated a protective role, being significantly correlated with normal electroencephalography, transfontanelle US and normal neurological findings at discharge. In conclusion, the IL6 174GC gene polymorphism seems to play a role in determining the risk and/or severity of perinatal cerebral injury.

Inflammatory response in acute chorioamnionitis

Acute chorioamnionitis is the principal antecedent of premature birth and an important contributor to specific neonatal and other complications that may extend throughout subsequent life. A large number of studies have addressed surrogate markers of in-utero inflammation including cytokines, chemokines, pathogen-associated molecular patterns, and elicited host proteins. However, chorioamnionitis means inflammation occurring within the chorioamnion and the only practical direct measure available to assess this finding in most placentas is histopathology. The maternal and fetal inflammatory response to the presence of organisms within the placental membranes, so-called histologic chorioamnionitis, is the focus of this review. The issues addressed are the nature and origin of the eliciting antigen, mode of spread to the placenta, general characteristics of placental immunity, and a specific characterization of the spectrum of pathologic lesions observed in placentas with membrane infection.

Interplay of cytokine polymorphisms and bacterial vaginosis in the etiology of preterm delivery

Recent findings suggest that the association between inflammation-related genes and preterm delivery may be stronger in the presence of bacterial vaginosis (BV). Tumor necrosis factor-alpha (TNFα) and interleukin 1-beta (IL-1β) are pro-inflammatory cytokines capable of inducing preterm labor in non-human primates. In this study the authors tested associations among two TNFα promoter polymorphisms (-G308A and -G238A), a single IL-1β polymorphism (+C3954T), vaginal microbial findings, and risk of preterm delivery. Data were from the Pregnancy Outcomes and Community Health (POUCH) Study (n=777 term and n=230 preterm deliveries). Vaginal smears collected at mid-pregnancy (15-27 weeks gestation) were scored according to Nugent's criteria. A Nugent score of ≥ 4 was modeled as the cut-point for intermediate and positive BV. Logistic regression was used to estimate odds ratios for associations among independent covariates (vaginal flora, genotype) and preterm delivery. Results showed that women with a Nugent score of≥ 4 and the TNFα -238 A/G or A/A were at increased risk of delivering preterm (race/ethnicity adjusted OR 2.6, 95% CI 1.2, 5.8). The p-value for the genotype and Nugent score interaction=0.02. This study points to one more example of a potential gene-environment interaction in a preterm delivery pathway. Future tests of this finding will determine the robustness of these results.

Reduced mortality and increased BPD with histological chorioamnionitis and leukocytosis in very-low-birth-weight infants

OBJECTIVE

To investigate the association between leukocytosis, mortality and bronchopulmonary dysplasia (BPD) in very-low-birth-weight infants (VLBW) born to mothers with histological chorioamnionitis.

STUDY DESIGN

A retrospective cohort study from a single level 3 neonatal intensive care unit. The study sample included infants born to mothers with histological chorioamnionitis (n=252). Total white blood cells (WBCs) after birth were measured. Leukocytosis was defined as a total WBC count >30 000 per mm(3) in the first 2 days of life. Outcomes investigated included BPD and death. Both unadjusted and multivariable analyses were carried out.

RESULT

After controlling for potential confounding variables, infants who developed a leukocytosis after birth had increased odds of BPD (4.6, 95% confidence interval (95% CI): 2.0 to 10.3), but decreased odds of death (0.3, 95% CI: 0.1 to 0.90).

CONCLUSION

In our population of VLBW infants born to mothers with histological chorioamnionitis, leukocytosis after birth is associated with a decrease in mortality but an increase in BPD.

Chorioamnionitis--a complex pathophysiologic syndrome

Chorioamnionitis, inflammation of the amniochorionic membrane (fetal membranes) is a very common disease but a complex syndrome associated with pregnancy. It presents a clinical impasse due to lack of knowledge of specific etiologies associated with this condition making confident clinical interventions difficult. Recent reports provide insight into genetic, epigenetic, behavioral, psychosocial, molecular and pathophysiological factors that are associated with chorioamnionitis. However, a coordinated approach in understanding causality and lack of early indicators (clinical and biomarkers) has hampered gaining knowledge about the disease status preventing proper intervention. Several reviews have provided in-depth analysis of the histologic and clinical evidence associated with chorioamnionitis. In this review, we provide a novel perspective on chorioamnionitis based on recent evidences from scientific literature on inflammation, apoptosis and genetics.

Comparative gender differences in local and systemic concentrations of pro-inflammatory cytokines in rats with experimental periodontitis

BACKGROUND AND OBJECTIVE

There have been few studies of gender differences in response to periodontitis. Thus, we compared gender-specific differences in systemic cytokine concentrations in rats with and without ligature-induced periodontitis.

MATERIAL AND METHODS

Experimental periodontal disease was initiated in Sprague-Dawley rats by placing a ligature around the crowns of the second right maxillary molar tooth. Sham-operated control groups were also created. Two weeks later, the right and left maxillary quadrants of teeth, liver and serum were collected from all the rats, and uterine horns were collected from the female rats. Liver and uterine samples were ground in phosphate-buffered saline (10 mg of tissue/mL of phosphate-buffered saline + protease inhibitor) containing a protease inhibitor, and cytokine concentrations were determined by enzyme-linked immunosorbent assay. Digital radiographs were made of maxillary quadrants, and the distance from cemento-enamel junction to alveolar crest was measured using image analysis software. Data were compared by factorial analysis of variance and a post-hoc Tukey test.

RESULTS

Female rats with ligatures had greater, but not significantly different, alveolar bone loss than males with ligatures. However, they had higher serum concentrations of interleukin-6, tumor necrosis factor-alpha and C-reactive protein, and liver C-reactive protein (p < 0.05). These females also had higher interleukin-6, tumor necrosis factor-alpha and vascular endothelial growth factor concentrations within the uterine horn, compared to female controls (p < 0.05). Male animals with ligatures had lower serum concentrations of C-reactive protein and higher interleukin-6 and tumor necrosis factor-alpha concentrations within serum, compared to male controls (p < 0.05).

CONCLUSION

Our study suggests that females with periodontal disease have a greater risk for inflammatory-based systemic diseases than males.

Cord blood biomarkers of the fetal inflammatory response

OBJECTIVE

In current, neonatal practice, clinical signs of intrauterine infection (IUI) are often non-specific. From a large panel of immune biomarkers, we seek to identify cord blood markers that are most strongly associated with the fetal inflammatory response (FIR), a specific placental lesion associated with serious neonatal complications.

METHODS

We used multiplex immunoassay to measure 27 biomarkers, selected as part of an NIH-funded study of preterm birth, according to gestational age (GA) and extent of placental inflammation: involvement of chorion, amnion, decidua (maternal inflammatory response, MIR); extension to umbilical cord or chorionic plate (FIR). We used false-discovery rate (FDR < 5%, P < 0.001) to account for multiple comparisons.

RESULTS

Among 506 births (GA 23-42 weeks), IL-1 beta increased with FIR among preterm subgroups (P = 0.0001 for <32 weeks; P = 0.0009 for 33-36 weeks). IL-6 and IL-8 increased with FIR among preterm and full-term infants (P < 0.0001). P-trend for IL-6 and IL-8 with MIR versus FIR was <0.0001. Comparison with respect to clinical IUI yielded persistent elevation with FIR even when clinical signs were absent. The remaining 24 markers were not significantly associated.

CONCLUSION

We conclude that among 27 cord blood biomarkers, IL-1 beta, IL-6 and IL-8 are selectively associated with FIR. These markers may be clinically useful indicators of extensive IUI associated with poor neonatal outcome.

Polymorphisms of tumor-necrosis factor-alpha - 308 and lymphotoxin-alpha + 250: possible modulation of susceptibility to apoptosis in chronic lymphocytic leukemia and non-Hodgkin lymphoma mononuclear cells

Tumor necrosis factor alpha (TNF-alpha) and lymphotoxin alpha (LT-alpha) have been shown to play an important role in the pathogenesis of limphoproliferative disease. Both cytokines regulate cell-survival and cell-death in leukemic cells. TNF-alpha and LT-alpha are highly produced in chronic lymphotic leukemia (CLL) and non-Hodgkin lymphoma (NHL) patients. Genetic polymorphism within regulatory regions of these cytokine genes can alter their expression levels. This study investigates an influence of TNF-alpha - 308 and LT-alpha + 250 polymorphisms on the activity of alkaline DNase in mononuclear cells of both patient groups as a potent biochemical marker of DNA fragmentation in the terminal phase of apoptosis. Study was performed on mononuclear cells of CLL and NHL patients. SNP were obtained by PCR-RFLP method. The activity of alkaline DNase was measured by spectrophotometric method. The study provided evidence of the influence of TNFG/A genotype and A alleles in the susceptibility to NHL, since the association of LT-alphaG/G genotype with CLL was observed. High-producing TNF-alpha - 308/LT-alpha + 250 heterozygous haplotype is associated with high NHL incidence. The investigated SNP influence the activity of alkaline DNase in CLL and NHL patients. The observed polymorphisms may modulate susceptibility of leukemic cells to apoptosis by way of DNase activity.

Heritability of bronchopulmonary dysplasia, defined according to the consensus statement of the national institutes of health

OBJECTIVE

The goal was to determine the magnitude of genetic effects on susceptibility and risk factors for bronchopulmonary dysplasia by using the clinically validated National Institutes of Health consensus definition as a demonstrated proxy for long-term respiratory and neurodevelopmental outcomes in extremely low birth weight infants.

METHODS

We analyzed clinical data from twin pairs born at </=30 completed weeks of gestation in British Columbia, Canada, between 1993 and 2006. Differences in correlations between monozygotic and dizygotic twin pairs and model-fitting approaches were used to quantify the relative contributions of genetic, shared environmental, and nonshared environmental effects.

RESULTS

Among 318 twins of known zygosity, monozygotic twin pair similarities were greater than those observed for dizygotic pairs, which suggests significant heritability for bronchopulmonary dysplasia. Model-fitting analyses confirmed that genetic effects accounted for 82% and 79% of the observed variance in bronchopulmonary dysplasia susceptibility, defined on the basis of the need for supplemental oxygen at 36 weeks or the National Institutes of Health consensus definition, respectively. Variations in rates of hemodynamically significant patent ductus arteriosus were largely accounted for by genetic effects, whereas the observed variability in susceptibility to blood-borne bacterial infections was largely attributable to environmental factors, both common and unique to each infant.

CONCLUSIONS

Susceptibility to bronchopulmonary dysplasia and persistence of patent ductus arteriosus are both significantly heritable. Our study strengthens the case for investigating genetic risk stratification markers useful for predicting the most significant long-term respiratory and neurodevelopmental consequences of bronchopulmonary dysplasia in premature neonates.

Haplotypes of tumor necrosis factor gene and tracheal aspirate fluid levels of tumor necrosis factor-alpha in preterm infants

Individual variability in the production of tumor necrosis factor-alpha (TNF-alpha) has been attributed to genetic factors. We examined whether alleles of TNF gene (lymphotoxin-alpha+250, TNF-alpha-308, and TNF-alpha-238) affect tracheal aspirate fluid (TAF) levels of TNF-alpha among preterm infants at risk of bronchopulmonary dysplasia. TAF samples were collected within 48 h of birth and 7, 14, 21, and 28 d later. Haplotypes [designated using the nucleotide bases in the chromosome order (lymphotoxin-alpha+250, TNF-alpha-308, TNF-alpha-238)] of TNF were correlated with levels of TNF-alpha. Diplotypes of TNF (genotypes of haplotypes) classified as high, intermediate, or low based on their relation to TAF TNF-alpha levels were also correlated with TNF-alpha levels. The most frequent (and reference haplotype) was AGG. The GGG haplotype was associated with the lowest TAF TNF-alpha levels on day 7 among African American infants (p < 0.008). Sequential changes in levels of TNF-alpha correlated with infants' diplotype status [high (HH), intermediate (HL), low (LL)]. Fetal chorioamnionitis but not bronchopulmonary dysplasia was associated with infants' diplotypes (p < 0.005). Haplotypes of the TNF gene influence TAF levels of TNF-alpha. Diplotypes of TNF are associated with fetal chorioamnionitis.

Genetic association studies in VLBW infants exemplifying susceptibility to sepsis--recent findings and implications for future research

CONTEXT

In recent years, tremendous effort has been carried out to study the genetic basis of susceptibility to development, progression and severity of complex diseases and response to therapy. The ultimate goal of these investigations is to find new tools for prevention and treatment of these complex diseases, such as sepsis in very-low-birth-weight (VLBW) infants. VLBW cohorts have a restricted clinical risk profile for the development of sepsis including immaturity of immune functions and antenatal/perinatal risk factors but also a significant event rate of sepsis within a short period of observational time. Therefore, prospective VLBW cohorts are advantageous for the investigation of candidate genetic risk factors of sepsis compared to adult cohorts. Furthermore, environmental factors are much better documented and highly controlled for VLBW infants in a standardized NICU setting compared to adult cohorts which are influenced by a variety of environmental risk factors, e.g. habits and comorbidities.

OBJECTIVE

The aim of this review is to discuss the value and limitations of genetic association studies in VLBW infant cohorts exemplifying recent findings for genetic susceptibility to neonatal sepsis.

DATA SOURCE

Published Medline articles reporting on studies of associations between genetic polymorphisms, neonatal sepsis and septic shock in VLBW infants.

CONCLUSIONS

Up-to-date, the classical approach to investigate the genetic component of susceptibility to sepsis in VLBW infants by means of twin and concordance studies has not been implemented yet. Regarding the interpretation of data from current genetic association studies, one should be aware of significant differences in cohort size, study design and definition of cases, controls and clinical end points. Furthermore, the contribution of genetic variants to susceptibility to sepsis may be specifically influenced by the immaturity of the immune response in VLBW infants, the selectivity of responsiveness to certain pathogens and the genotopyic/phenotypic variability of pathogens. We provide implications for the conduct and evaluation of future association studies with particular reference to methodological quality standards.

Inflammatory responses in the placenta and umbilical cord

Histopathological examination of the placenta is the gold standard for evaluating antenatal inflammatory processes that might influence fetal development. Histological chorioamnionitis develops through a well-characterised stereotyped progression of maternal and fetal cellular stages that vary from patient to patient and are amenable to quantification. Increases in the intensity of these responses and their gradual transformation into a chronic phase are important variables that can adversely affect fetal physiology. Under recognised placental inflammatory lesions affecting the decidua, placental villi and fetal vessels are also potentially informative factors that should be taken into account in the studies of adverse pregnancy outcomes. This review summarises the relationships between aetiology, intensity, duration, characteristics and site of histological placental inflammation and suggests how these data may help to better understand the antenatal environment.

Cumulative index of exposure to hypocarbia and hyperoxia as risk factors for periventricular leukomalacia in low birth weight infants

BACKGROUND

Hypocarbia and hyperoxia are risk factors for periventricular leukomalacia in low birth weight infants. The association of a cumulative index of exposure to hypocarbia and hyperoxia and periventricular leukomalacia has not been evaluated.

OBJECTIVE

Our goal was to examine the relationship between cumulative index of exposure to hypocarbia and hyperoxia and periventricular leukomalacia during the first 7 days of life in low birth weight infants.

METHODS

Blood gas results were recorded in 6-hour intervals among low birth weight infants in a prospective data registry. Cumulative index of exposure to hypocarbia was calculated as the difference between arterial carbon dioxide level and 35 mmHg multiplied by the time interval in hours for each 6-hour block in a 24-hour day for the first 7 days of life. Cumulative index of exposure to hyperoxia was calculated in the same manner for arterial oxygen level >80 mm Hg. The relationship between exposure to hypocarbia, hyperoxia, and periventricular leukomalacia was examined in 778 infants with blood gas and cranial sonography data.

RESULTS

Twenty-one infants had periventricular leukomalacia. Hypocarbia occurred in 489 infants and hyperoxia in 502 infants. Infants with periventricular leukomalacia were more likely to have a lower gestational age and to require delivery room resuscitation than those without periventricular leukomalacia. More infants in the highest quartile of exposure to hypocarbia had periventricular leukomalacia compared to those with no hypocarbia. Risk of periventricular leukomalacia was increased in infants with the highest quartile of exposure to hypocarbia after adjusting for maternal and neonatal variables, none to be associated with periventricular leukomalacia. Cumulative index exposure to hyperoxia was not related to periventricular leukomalacia.

CONCLUSIONS

Cumulative exposure to hypocarbia and not hyperoxia was independently related to risk of periventricular leukomalacia in low birth weight infants.

Role of single nucleotide polymorphisms of cytokine genes in spontaneous preterm delivery

Intra-amniotic infections are implicated in spontaneous preterm delivery (PTD). Certain genetic polymorphisms are associated with increased production of proinflammatory and/or decreased production of anti-inflammatory cytokines, thereby possibly promoting PTD. We determined the relationship between maternal and fetal cytokine gene polymorphisms with occurrence and severity of spontaneous PTD (PTD after spontaneous-onset preterm labor and/or preterm prelabor rupture of membranes) and their association with intrauterine inflammation and infection. DNA from buccal brushings of 80 preterm (gestation < 35 weeks) and 80 matched term mother-infant pairs was assayed for tumor necrosis factor alpha (TNF-alpha [-308G/A]), interferon-gamma (IFN-gamma [+874A/T]), interleukin-6 (IL-6 [-174C/G]), interleukin-10 (IL-10 [-1082G/A, -819C/T, -592C/A]), and transforming growth factor beta1 (TGF-beta1 [T/Ccodon10,G/Ccodon25]) by using polymerase chain reaction (PCR) with sequence-specific primers. The presence of histologic chorioamnionitis was determined for PTDs. Conditioned on maternal IFN-gamma genotypes, fetal high IFN-gamma producing allele (IFN-gamma[+874T]) was associated with spontaneous PTD (odds ratio = 2.3 [1.2-4.4]). Among preterm deliveries, maternal low TGF-beta1 (TGF-beta1 [codon10C]) producing genotypes correlated negatively with gestation. Fetal TNF-alpha (-308G) was significantly associated with histologic chorioamnionitis. Underlying genitourinary infections and/or inflammation were significantly associated with maternal and fetal IL-6 (-174G), fetal TNF-alpha (-308GG), and fetal IL-10 (-1082A). We conclude that certain fetal and maternal cytokine gene polymorphisms may be associated with occurrence and/or severity of spontaneous PTD and with intrauterine inflammation and infection.

The impact of vaginal delivery in premature infants weighing less than 1,251 grams

OBJECTIVE

To evaluate whether mode of delivery is a predictor of poor short-term outcome at different birth weight categories in very low birth weight infants.

METHODS

This study examined a cohort of infants weighing less than 1,251 g born at 2 perinatal centers from January 1, 2000, to December 31, 2003. Outborn infants or those with major anomalies were excluded from the study. Outcome variables included death, severe intraventricular hemorrhage, periventricular leukomalacia (PVL), and combined poor short-term outcomes (death, severe intraventricular hemorrhage, and PVL).

RESULTS

Of the 397 infants who met enrollment criteria, 44% were born vaginally and 56% by cesarean delivery. The proportion of multiparous, breech presentation and prolonged rupture of membranes was significantly different between groups. For infants weighing less than 751 g, the risks of severe intraventricular hemorrhage (41% versus 22%; odds ratio [OR] 2.79, 95% confidence interval [CI] 1.08-7.72) and combined poor short-term outcome (67% versus 41%; OR 2.95, 95% CI 1.25-6.95) were significantly higher if delivered vaginally. Among survivors weighing less than 751 g, the risk of severe intraventricular hemorrhage was higher among those delivered vaginally (24% versus 9%; OR 8.18, 95% CI 1.58-42.20). In infants less 1,251 g who survived, vaginal delivery had a strong association with PVL (5% versus 1%; OR 11.53, 95% CI 1.66-125).

CONCLUSION

In infants less than 1,251 g who survived to discharge, vaginal delivery is associated with higher risk for PVL. Furthermore, in infants less than 751 g, vaginal delivery is a predictor for severe intraventricular hemorrhage and combined poor short-term outcome. The negative impact of vaginal delivery mode decreases as birth weight category increases.