Urinary β-2-microglobulin as an alternative marker for fetal inflammatory response and development of bronchopulmonary dysplasia in premature infants

Improving early diagnosis of bronchopulmonary dysplasia

INTRODUCTION

Bronchopulmonary disease (BPD) is associated with long-term neurodevelopmental and cardiorespiratory complications, often requiring significant use of resources. To reduce this healthcare burden, it is essential that those at high risk of BPD are identified early so that strategies are introduced to prevent disease progression. Our aim was to discuss potential methods for improving early diagnosis in the first week after birth.

AREAS COVERED

A narrative review was undertaken. The search strategy involved searching PubMed, Embase and Cochrane databases from 1967 to 2024. The results of potential biomarkers and imaging modes are discussed. Furthermore, the value of scoring systems is explored.

EXPERT OPINION

BPD occurs as a result of disruption to pulmonary vascular and alveolar development, thus abnormal levels of factors regulating those processes are promising avenues to explore with regard to early detection of high-risk infants. Data from twin studies suggests genetic factors can be attributed to 82% of the observed difference in moderate to severe BPD, but large genome-wide studies have yielded conflicting results. Comparative studies are required to determine which biomarker or imaging mode may most accurately diagnose early BPD development. Models which include the most predictive factors should be evaluated going forward.

Lifting the Veil: Characteristics, Clinical Significance, and Application of β-2-Microglobulin as Biomarkers and Its Detection with Biosensors

Because β-2-microglobulin (β₂M) is a surface protein that is present on most nucleated cells, it plays a key role in the human immune system and the kidney glomeruli to regulate homeostasis. The primary clinical significance of β₂M is in dialysis-related amyloidosis, a complication of end-stage renal disease caused by a gradual accumulation of β₂M in the blood. Therefore, the function of β₂M in kidney-related diseases has been extensively studied to evaluate its glomerular and tubular functions. Because increased β₂M shedding due to rapid cell turnover may indicate other underlying medical conditions, the possibility to use β₂M as a versatile biomarker rose in prominence across multiple disciplines for various applications. Therefore, this work has reviewed the recent use of β₂M to detect various diseases and its progress as a biomarker. While the use of state-of-the-art β₂M detection requires sophisticated tools, high maintenance, and labor cost, this work also has reported the use of biosensor to quantify β₂M over the past decade. It is hoped that a portable and highly efficient β₂M biosensor device will soon be incorporated in point-of-care testing to provide safe, rapid, and reliable test results.

The Effect of Antenatal Steroid Therapy on Early Inflammation Markers and Leukocyte Counts in Premature Infants

ObjectiveWe investigated the effect of antenatal steroid therapy(AST) on white blood cell (WBC) and neutrophil counts and the inflammatory markers C-reactive protein(CRP), interleukin 6(IL-6), interleukin 10(IL-10), and beta-2 microglobulin(ß2M) in preterm infants.Materials MethodNeonates born at ≤34 weeks of gestation and admitted at hospital between May and November 2018 were included. The neonates were divided into three groups based on AST dose administered: 24 mg betamethasone (full course), 12 mg betamethasone (incomplete course), and no AST. 170 infants were analyzed.ResultsOf these, 45.2% (n = 77) received a full course of AST, 38.8% (n = 66) received an incomplete course of AST, and 15.8% (n = 27) did not receive AST. WBC, CRP, IL-6, IL-10, and ß2M levels were similar between the three groups, whereas neutrophil count was significantly lower in full course AST group.ConclusionConsistent with the literature data, AST was associated with reduced neutrophil count but did not affect the other inflammatory markers studied.

Association of Chorioamnionitis With Bronchopulmonary Dysplasia Among Preterm Infants: A Systematic Review, Meta-analysis, and Metaregression

Importance

Bronchopulmonary dysplasia (BPD), a chronic lung disease of prematurity, remains one of the major and most common complications of very preterm birth. Insight into factors associated with the pathogenesis of BPD is key to improving its prevention and treatment.

Objective

To perform a systematic review, meta-analysis, and metaregression of clinical studies exploring the association between chorioamnionitis (CA) and BPD in preterm infants.

Data Sources

PubMed and Embase were searched without language restriction (last search, October 1, 2018). Key search terms included bronchopulmonary dysplasia, chorioamnionitis, and risk factors.

Study Selection

Included studies were peer-reviewed studies examining preterm (<37 weeks' gestation) or very low-birth-weight (<1500 g) infants and reporting primary data that could be used to measure the association between exposure to CA and the development of BPD.

Data Extraction and Synthesis

The Meta-analysis of Observational Studies in Epidemiology (MOOSE) guideline was followed. Data were independently extracted by 2 researchers. A random-effects model was used to calculate odds ratios (ORs) and 95% CIs. Heterogeneity in effect size across studies was studied using multivariate, random-effects metaregression analysis.

Main Outcomes and Measures

The primary outcome was BPD, defined as supplemental oxygen requirement on postnatal day 28 (BPD28) or at the postmenstrual age of 36 weeks (BPD36). Covariates considered as potential confounders included differences between CA-exposed and CA-unexposed infants in gestational age, rates of respiratory distress syndrome (RDS), exposure to antenatal corticosteroids, and rates of early- and late-onset sepsis.

Results

A total of 3170 potentially relevant studies were found, of which 158 met the inclusion criteria (244 096 preterm infants, 20 971 CA cases, and 24 335 BPD cases). Meta-analysis showed that CA exposure was significantly associated with BPD28 (65 studies; OR, 2.32; 95% CI, 1.88-2.86; P < .001; heterogeneity: I2 = 84%; P < .001) and BPD36 (108 studies; OR, 1.29; 95% CI, 1.17-1.42; P < .001; heterogeneity: I2 = 63%; P < .001). The association between CA and BPD remained significant for both clinical and histologic CA. In addition, significant differences were found between CA-exposed and CA-unexposed infants in gestational age, birth weight, odds of being small for gestational age, exposure to antenatal corticosteroids, and early- and late-onset sepsis. Chorioamnionitis was not significantly associated with RDS (48 studies; OR, 1.10; 95% CI, 0.92-1.34; P = .24; heterogeneity: I2 = 90%; P < .001), but multivariate metaregression analysis with backward elimination revealed that a model combining the difference in gestational age and the odds of RDS was associated with 64% of the variance in the association between CA and BPD36 across studies.

Conclusions and Relevance

The results of this study confirm that among preterm infants, exposure to CA is associated with a higher risk of developing BPD, but this association may be modulated by gestational age and risk of RDS.

Urinary β2-microglobulin and bronchopulmonary dysplasia: Trends in preterm infants

BACKGROUND

The developmental process of bronchopulmonary dysplasia (BPD) is not identical between very preterm infants born small for gestational age (SGA) and those born appropriate for gestational age (AGA). In this study, we compared the pattern of the inflammatory response in infants of each group, by measuring urinary β2-microglobulin (Uβ2M) as an alternative, concise, and less-invasive biomarker.

METHODS

Uβ2M and clinical details were examined at birth and at 4 weeks of age in 146 very preterm infants.

RESULTS

Of the 57 infants diagnosed with BPD, 18 were SGA, and 39 were AGA. Uβ2M at birth was significantly lower in SGA BPD infants than in AGA BPD infants, but it increased with time. The prevalence of chorioamnionitis (CAM) was significantly lower in SGA BPD infants than in AGA BPD infants, while that of pregnancy-induced hypertension was the opposite.

CONCLUSIONS

Exposure to prenatal factors other than CAM may sensitize fetal lungs to become vulnerable to postnatal inflammation in very preterm SGA infants with BPD.

Bronchopulmonary Dysplasia and Perinatal Characteristics Predict 1-Year Respiratory Outcomes in Newborns Born at Extremely Low Gestational Age: A Prospective Cohort Study

OBJECTIVE

To assess the utility of clinical predictors of persistent respiratory morbidity in extremely low gestational age newborns (ELGANs).

STUDY DESIGN

We enrolled ELGANs (<29 weeks' gestation) at ≤7 postnatal days and collected antenatal and neonatal clinical data through 36 weeks' postmenstrual age. We surveyed caregivers at 3, 6, 9, and 12 months' corrected age to identify postdischarge respiratory morbidity, defined as hospitalization, home support (oxygen, tracheostomy, ventilation), medications, or symptoms (cough/wheeze). Infants were classified as having postprematurity respiratory disease (PRD, the primary study outcome) if respiratory morbidity persisted over ≥2 questionnaires. Infants were classified with severe respiratory morbidity if there were multiple hospitalizations, exposure to systemic steroids or pulmonary vasodilators, home oxygen after 3 months or mechanical ventilation, or symptoms despite inhaled corticosteroids. Mixed-effects models generated with data available at 1 day (perinatal) and 36 weeks' postmenstrual age were assessed for predictive accuracy.

RESULTS

Of 724 infants (918 ± 234 g, 26.7 ± 1.4 weeks' gestational age) classified for the primary outcome, 68.6% had PRD; 245 of 704 (34.8%) were classified as severe. Male sex, intrauterine growth restriction, maternal smoking, race/ethnicity, intubation at birth, and public insurance were retained in perinatal and 36-week models for both PRD and respiratory morbidity severity. The perinatal model accurately predicted PRD (c-statistic 0.858). Neither the 36-week model nor the addition of bronchopulmonary dysplasia to the perinatal model improved accuracy (0.856, 0.860); c-statistic for BPD alone was 0.907.

CONCLUSION

Both bronchopulmonary dysplasia and perinatal clinical data accurately identify ELGANs at risk for persistent and severe respiratory morbidity at 1 year.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01435187.

Biomarkers for Bronchopulmonary Dysplasia in the Preterm Infant

Bronchopulmonary dysplasia (BPD) is a chronic inflammatory lung disease of very-low-birth-weight (VLBW) preterm infants, associated with arrested lung development and a need for supplemental oxygen. Over the past few decades, the incidence of BPD has significantly raised as a result of improved survival of VLBW infants requiring mechanical ventilation. While early disease detection is critical to prevent chronic lung remodeling and complications later in life, BPD is often difficult to diagnose and prevent due to the lack of good biomarkers for identification of infants at risk, and overlapping symptoms with other diseases, such as pulmonary hypertension (PH). Due to the current lack of effective treatment available for BPD and PH, research is currently focused on primary prevention strategies, and identification of biomarkers for early diagnosis, that could also represent potential therapeutic targets. In addition, novel histopathological, biochemical, and molecular factors have been identified in the lung tissue and in biological fluids of BPD and PH patients that could associate with the disease phenotype. In this review, we provide an overview of biomarkers for pediatric BPD and PH that have been identified in clinical studies using various biological fluids. We also present a brief summary of the information available on current strategies and guidelines to prevent and diagnose BPD and PH, as well as their pathophysiology, risk factors, and experimental therapies currently available.

Lung Disease, Oxidative Stress, and Oxygen Requirements in Preterm Infants

BACKGROUND

The role of oxidative stress remains unclear in the multifactorial pathophysiologic mechanism of lung disease in preterm infants.

AIMS

The aim of this study was to examine the associations among chronic lung disease (CLD), oxidative stress, and oxygen requirements in preterm infants.

DESIGN

Prospective, longitudinal, and correlational design.

SUBJECTS

Preterm infants born at <32 weeks' gestation (N = 31), median gestation of 29.0 weeks (range 24.9-31.7).

MEASUREMENTS

The diagnosis of CLD was obtained from the medical record. Oxidative stress was measured using 8-hydroxydeoxyguanosine (8-OHdG) in the cord blood at birth and urine on Days 1 and 7. Oxygen requirements were measured using fraction of inspired oxygen (FIO2) recorded in the first hour after birth/admission and the average FIO2 during the first 12 hr and 7 days after birth. Descriptive statistics are presented. Comparison analyses were performed using Kruskal-Wallis and Fisher's exact tests.

RESULTS

Infants with CLD (n = 12) had lower gestational age (p = .04) and weight (p = .04) at birth, more days on the ventilator (p = .004), and longer neonatal intensive care unit stay (p = .04) compared to infants without CLD (n = 19). CLD was associated with lower oxidative stress levels (p = .03) and higher oxygen requirements during the first 12 hr (p = .025) and on Day 7 (p = .001). Lower oxidative stress levels on Day 7 were associated with higher oxygen requirements in the first 12 hr (p = .01) and on Day 7 (p = .03).

CONCLUSION

Our results linking CLD and higher oxygen requirements with low oxidative stress contradict previous reports. Findings identify a gap in knowledge for postresuscitation oxygen therapy in preterm infants and expose the role of oxidative stress from inflammation and intermittent hypoxia in the etiology of CLD.

Postnatal changes of cytokines in premature infants with or without funisitis

OBJECTIVE

Fetal inflammatory response syndrome (FIRS), which induces hypercytokinemia, is important for the outcomes of premature infants. It is necessary to focus on the fetal inflammatory environments.

METHODS

A total of 37 premature infants (gestational age ≤32 weeks) were divided into three groups: (1) 15 without chorioamnionitis (CAM) and funisitis; C(-)F(-) group, (2) 15 with CAM but without funisitis; C(+)F(-) group and (3) 7 with CAM and funisitis; C(+)F(+) group. Blood interleukin (IL)-1β, IL-6 and IL-8 levels were measured on day 0 (= in umbilical cord blood), 3, 7, 14, 21 and 28.

RESULTS

(1) day 0: Cord blood concentrations of IL-1β, IL-6 and IL-8 were significantly higher in the C(+)F(+) group than in the C(+)F(-) group and C(-)F(-) group. On the other hand, they were comparable between the C(+)F(-) group and C(-)F(-) group. (2) Days 3-28: elevated cytokines levels in the C(+)F(+) group with funisitis decreased on day 3 and later.

CONCLUSIONS

We suggested that hypercytokinemia in the cord blood in premature infants were greatly related with funisitis. Diagnosis of funisitis would be important to find the premature infants who need to be managed their risk of FIRS. In addition, hypercytokinemia disappeared in a few days after birth; therefore, cord blood data analysis of cytokines and/or inflammation-related proteins concentrations is necessary to evaluate the fetal inflammatory environments in premature infants after birth.

Increased volume of tracheal aspirate fluid predicts the development of bronchopulmonary dysplasia

BACKGROUND

Elevated cytokine concentrations were observed in tracheal aspirate fluid (TAF) of infants on mechanical ventilation who subsequently developed bronchopulmonary dysplasia (BPD). However, there are few reports that systematically evaluate the amount of TAF as an indicator of BPD development.

AIM

To clarify whether TAF volume during the first week of life predicts BPD development in extremely low gestational age newborns (ELGANs).

STUDY DESIGN

We analyzed 51 infants, born at gestational age of <28 weeks and ventilated for more than 7 days after birth, among whom, 26 were diagnosed with BPD based on the clinical definition of oxygen dependence at 36 weeks postmenstrual age (BPD group) and 25 were included in the non-BPD group. Sum of TAF scores (STS) was calculated by semi-quantification of TAF volume at each suctioning and the suctioning frequency during the first week of life.

RESULTS

STS was significantly higher in the BPD group than in the non-BPD group (median (interquartile range): 77 (29-126) vs. 28 (22-59), p<0.001). STS (cut-off, 60) with area under the curve in receiver operating analysis of 0.75 was significantly predictive of BPD development. Multivariate logistic regression analysis adjusted for perinatal characteristics showed that STS≥60 was a significant risk factor for BPD development (odds ratio, 7.50; confidence interval, 1.16-48.40, p=0.034).

CONCLUSION

Increased TAF volume during the first week of life was an independent predictor for BPD development in ventilated ELGANs, indicating that increased pulmonary capillary permeability may influence the pathogenesis of BPD.

A new way of thinking about complications of prematurity

The morbidity and mortality of preterm infants are impacted by their ability to maintain physiologic homeostasis using metabolic, endocrine, and immunologic mechanisms independent of the mother's placenta. Exploring McEwen's allostatic load model in preterm infants provides a new way to understand the altered physiologic processes associated with frequently occurring complications of prematurity such as bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, and retinopathy of prematurity. The purpose of this article is to present a new model to enhance understanding of the altered physiologic processes associated with complications of prematurity. The model of allostatic load and complications of prematurity was derived to explore the relationship between general stress of prematurity and complications of prematurity. The proposed model uses the concepts of general stress of prematurity, allostasis, physiologic response patterns (adaptive-maladaptive), allostatic load, and complications of prematurity. These concepts are defined and theoretical relationships in the proposed model are interpreted using the four maladaptive response patterns of repeated hits, lack of adaptation, prolonged response, and inadequate response. Empirical evidence for cortisol, inflammation, and oxidative stress responses are used to support the theoretical relationships. The proposed model provides a new way of thinking about physiologic dysregulation in preterm infants. The ability to describe and understand complex physiologic mechanisms involved in complications of prematurity is essential for research. Advancing the knowledge of complications of prematurity will advance clinical practice and research and lead to testing of interventions to reduce negative outcomes in preterm infants.

Urinary ß2-microglobulin in very preterm neonates with chorioamnionitis

It is important to identify premature infants with prenatal inflammation as it contributes to short- and long-term complications. Our object was to study how prenatal inflammation affects the urinary β(2)-microglobulin (β(2)-MG) level. Preterm neonates were divided based on the presence of chorioamnionitis (CAM) into the CAM (n = 100) and non-CAM groups (n = 117). These were further subdivided into five groups each: 30 preterm neonates of 23-26; 42 neonates of 27-28; 54 neonates of 29-30; 51 neonates of 31-32; and 40 neonates of 33-34 weeks' gestation. The urinary β(2)-MG level within 48 h of birth was significantly higher in the CAM group than in the non-CAM group among the neonates of 23-26 weeks' gestation (18.3 ± 6.9 vs 10.0 ± 5.6 × 10(4) μg/gCr, p = 0.0018) and the neonates of 27-28 weeks' gestation (16.2 ± 10.8 vs 8.8 ± 3.3 × 10(4) μg/gCr, p = 0.0101). However, there was no difference in urinary β(2)-MG level between the CAM and the non-CAM group among the neonates ≥ 29 weeks 'gestation. Moreover, the elevated urinary β(2)-MG level in the neonates ≤ 28 weeks ' gestation with CAM had disappeared by 1 week after birth. The reasons for the increase in urinary β(2)-MG level within 48 h of birth in very preterm neonates (≤ 28 weeks' gestation) with CAM are believed to be not only prematurity, but also prenatal inflammation. It is suggested that the urinary β(2)-MG level during the early postnatal period can identify prenatal inflammation.