Post-infectious bronchiolitis obliterans and mannose-binding lectin insufficiency in Argentinean children

DNAH9 variants in children with post-infectious bronchiolitis/bronchitis obliterans

Post-infectious bronchiolitis/bronchitis obliterans (PIBO) is a chronic irreversible obstructive lung disease that results in obstruction and/or obliteration of small airways. Previous reports have indicated that PCD-related gene mutations contribute to PIBO incidence. However, the relationship between DNAH9 variants and PIBO remains unclear. This study aimed to evaluate the association between DNAH9 mutations and the incidence of PIBO. In our cohort, 126 PIBO patients conducted Whole Exome Sequence (WES) test and twelve variants of DNAH9 gene were identified. Detailed clinical information, high-resolution computerized tomography and/or electronic bronchoscopy findings of the six pediatric children carried DNAH9 variants were systematically collected, meticulously reviewed, and rigorously analyzed. Clinical evaluation revealed three patients with bronchiolitis obliterans, two patients with bronchitis obliterans and one with both conditions. All patients had at least one previous bout of pneumonia, which in three cases was linked to Mycoplasma pneumoniae, in two cases to adenovirus infection, and in one case to co-infection with both pathogens. Genetic analysis of all cases identified six compound heterozygous DNAH9 mutations encompassing twelve variants: c.12,925 C > T (p.Arg4309*), c.5152-10G > T (-), c.4604 A > G (p.Gln1535Arg), c.12844-14T > C (-), c.4816T > C (p.Phe1606Leu), c.8831G > A (p.Arg2944Gln), c.9479 C > T (p.Ala3160Val), c.7415G > A (p.Arg2472Gln), c.5692G > T (p.Glu1898*), c.11,572 C > T (p.Arg3858Trp), c.11,176 C > T (p.Arg3726Trp), c.1010 C > T (p.Pro337Leu). These variants included two nonsense mutations, two mutations near splice sites, and eight missense mutations. All variants exhibited negligible or low minor allele frequencies based on the gnomAD database and were predicted to be variants of uncertain significance (VUS) or deleterious based on comprehensive bioinformatics analysis. Our findings suggest that DNAH9 compound complex variants may contribute to development of PIBO following severe M. pneumoniae and/or adenoviral infectious pneumonia in pediatric patients.

[Post-infectious bronchiolitis obliterans in children: A rare and potentially devastating disease]

Post-infectious bronchiolitis obliterans (PIBO) is a rare but severe pulmonary disease in children, often associated with adenovirus infection. Risk factors include male sex, hypoxemia, and mechanical ventilation. Diagnosis is based on clinical history, bronchial obstruction, and radiological abnormalities. PIBO is characterized by chronic inflammation leading to tissue remodeling and bronchiolar fibrosis. Airway epithelial lesions, potentially linked to viral infection, are considered key mechanisms of PIBO. In the absence of specific treatments, research efforts aim to better understand mechanisms of PIBO, identify biomarkers, and improve management strategies.

Post viral bronchiolitis obliterans in children: A rare and potentially devastating disease

Post infectious bronchiolitis obliterans (PIBO) is a rare but severe disease in children. Several respiratory pathogens are incriminated but adenovirus is still the most represented. Risk factors are well described: the male gender, hypoxemia at diagnosis and required mechanical ventilation. No risk factor is linked to the newborn period. The clinical spectrum of PIBO is broad, ranging from asymptomatic patients with fixed airflow obstruction to severe respiratory insufficiency requiring continuous oxygen supplementation. Diagnosis includes a combination of a clinical history, absence of reversible airflow obstructions and ground glass and gas trapping on high resolution computed tomography. PIBO is primarily a neutrophilic pathology of small bronchioles characterized by high levels of pro-inflammatory cytokines leading to tissue remodeling and fibrosis of the small airways. The difficulty is to discriminate between the host's normal response, an exaggerated inflammatory response and the potential iatrogenic consequences of the initial infection treatment, particularly prolonged mechanical ventilation. Damage to the respiratory epithelium with a possible link to viral infections are considered as potential mechanisms of PIBO. No specific management exists. Much remains to be done in this field to clarify the underlying mechanisms, identify biomarkers, and develop clear monitoring pathways and treatment protocols.

The association of HLA-DRB1 alleles and MBL2 gene variant in pediatric acute lymphoblastic leukemia patients

INTRODUCTION

Epidemiologic studies on pediatric acute lymphoblastic leukemias (ALL) have been conducted to evaluate the possible risk factors including genetic, infectious and environmental factors with the objective of idenfying the etiology. Mannose-binding lectin 2 (MBL2) plays an important role in first-line immune defense. HLA DRB1 alleles play a role in presentation of peptides to T cells and in activation of the adaptive immune response.

OBJECTIVE

In our study, we aimed to investigate both the MBL2 gene variant and HLA-DRB1 alleles in pediatric ALL patients.

MATERIALS

In this study, 86 high-risk ALL patients and 100 controls were included. Polymerase Chain Reaction (PCR)-Restriction Fragment Length Polymorphism (PCR-RFLP) and PCR-sequence specific primer (SSP) methods were used for detection of polymorphism of the MBL2 and HLA-DRB1 alleles, respectively.

RESULTS

The frequency of the MBL2 AB genotype was lower in female ALL patients, compared to male ALL patients (p = 0.034). An association was found between the MBL2 BB genotype and DRB1*07 and among patients with the MBL2 BB genotype; those who also carried the DRB1*07 and *04 alleles were significantly higher than those without the DRB1*07 and *04 alleles. (p = 0.048, p = 0.022, respectively).

CONCLUSION

This is the first study suggesting that the MBL2 BB genotype in association with the DRB1*07 or co-inheritance of the HLA-DRB1*04 and HLA DRB1*07 may have an impact on the etiopathogenesis of the disease.

Risk factors for bronchiolitis obliterans complicating adenovirus pneumonia in children: a meta-analysis

Objective

To preliminarily explore the risk factors for post-infectious bronchiolitis obliterans (PIBO) complicating adenovirus pneumonia (ADVP) in children through a meta-analysis.

Methods

A systematic search was conducted on three English-language databases (PubMed, Web of Science and The National Library of Medicine) and two Chinese-language databases (China National Knowledge Infrastructure and the Wanfang Database) between database inception and 1 January 2023. Data analysis was conducted using Stata 15.1 software.

Results

A total of 10 articles, reporting 14 risk factors, were included in the analysis, with 8 risk factors taken into consideration. Through the meta-analysis, 5 risk factors were identified for PIBO complicating ADVP in paediatric patients: hypoxaemia [odds ratio (OR) = 9.37, 95% CI: 4.22, 20.77, p < 0.001], persistent wheezing (OR = 4.65, 95% CI: 2.20, 9.82, p < 0.001), mechanical ventilation (OR = 3.87, 95% CI: 2.37, 6.33, p < 0.001), length of hospital stay (LoHS) (OR = 1.25, 95% CI: 1.09, 1.43, p < 0.001) and fever duration (OR = 1.08, 95% CI: 1.02, 1.14, p = 0.009).

Conclusion

Existing evidence suggests that hypoxaemia, persistent wheezing, mechanical ventilation, LoHS and fever duration are risk factors for PIBO complicating ADVP in children. These findings underscore the need for enhanced assessment and management in clinical practice. This study may provide such a clinical prediction model from the identified 5 risk factors for PIBO and offer valuable insights for preventing bronchiolitis obliterans in children with ADVP.

Exploring association between MBL2 gene polymorphisms and the occurrence of clinical blackwater fever through a case-control study in Congolese children

Background

Blackwater fever (BWF), one of the most severe and life-threatening forms of falciparum malaria, is characterized by acute massive intravascular haemolysis, often leading to acute renal failure. Thus far, the genetics of the underlying susceptibility to develop BWF is not fully elucidated. Deficiency in the MBL protein, an important component of the innate immune system, has previously been suggested to be a susceptibility factor for the development of severe malaria. This study aimed to evaluate the association between MBL2 gene polymorphisms, known to affect the MBL protein level/activity, and the occurrence of BWF among Congolese children.

Methods

This is a case–control study. Cases were patients with BWF, whereas controls, matched for gender and age, had uncomplicated malaria (UM). Dried blood spot was collected for genotyping.

Results

A total of 129 children were screened, including 43 BWF and 86 UM. The common allele in BWF and UM was A, with a frequency of 76.7 and 61.0%, respectively (OR: 2.67 (0.87–829) and p = 0.079). The frequency of the C allele was 18.6 and 29.1% in BWF and UM groups, respectively, with p = 0.858. Not a single D allele was encountered. Genotype AA was at higher risk for BWF whereas genotypes A0 (AB and AC) were over-represented in UM group (OR: 0.21 (0.06–0.78)) with p = 0.019. Nine haplotypes were observed in this study: 3 high MBL expression haplotypes and 6 low MBL expression haplotype. One new haplotype HYPC was observed in this study. None of these haplotypes was significantly associated with BWF.

Conclusion

This pilot study is a preliminary research on MBL2 gene and infectious diseases in DRC. The study results show a higher risk for BWF in AA. This suggests that future studies on BWF should further investigate the contribution of a strong immune response to the occurrence of BWF.

The impact of mannose-binding lectin polymorphisms on lung function in primary ciliary dyskinesia

OBJECTIVE

Primary ciliary dyskinesia (PCD) is a congenital lung disease that leads to recurrent and chronic lung infection. The resulting inflammation causes lung damage and declines in lung function. Mannose-binding lectin (MBL) is a first line host defense protein of importance for the innate immunity. Polymorphisms in the MBL gene named MBL2 result in unstable and low functional levels MBL proteins. MBL insufficiency is linked to an increased risk of lung infection and to declines in lung function in patients with cystic fibrosis. We investigated whether there is a similar link in patients with PCD.

METHODS

This retrospective longitudinal study included 85 patients with PCD. Diagnostics and age at diagnosis were recorded, complete spirometry data starting at diagnosis, and Pseudomonas aeruginosa infection status over the last 2 years were collected, and the patients were grouped according to MBL2 genotype status (MBL2-sufficient or MBL2-deficient).

RESULTS

MBL-deficient patients were diagnosed almost 3 years earlier than MBL-sufficient patients (median 6.1 vs 8.9 years, P  < 0.05). There were no differences in the first measured spirometry values, but MBL-deficient patients showed greater declines in forced expiratory volume in one sec (FEV₁ ) than patients with MBL sufficiency (z-score: -0.049 per year [95% CI, -0.075; -0.021] vs -0.009 per year [95% CI, -0.033; 0.015]; P = 0.023). No differences were found in forced vital capacity (FVC), FEV₁ /FVC, or infection status.

CONCLUSION

MBL-deficiency, which is associated with MBL2 mutations, was associated with a lower age at diagnosis and with steeper declines in FEV₁ in patients with PCD. This suggests that the MBL genotype might be a disease modifier in PCD.

Hypoxemia is an independent predictor of bronchiolitis obliterans following respiratory adenoviral infection in children

Bronchiolitis obliterans (BO) is an uncommon and severe sequela of chronic obstructive lung disease in children that results from an insult to the lower respiratory tract. Few prognostic factors achieved worldwide acknowledgment. In the present study, we retrospectively collected the children with respiratory adenoviral infection and identified the predictive factors of BO. In the period between Jan 2011 and December 2014, the consecutive in-hospital acute respiratory infection children with positive result for adenovirus were enrolled into the present study. High resolution computerized tomography and clinical symptoms were utilized as the diagnostic technique for BO. Multivariate analysis using a Logistic proportional hazards model was used to test for independent predictors of BO. A total of 544 children were included with 14 (2.57 %) patients developed BO. Compared with children without BO, BO children presented higher LDH (523.5 vs. 348 IU/ml, p = 0.033), lower blood lymphocyte count (2.23 × 109/L vs. 3.24 × 109/L, p = 0.025) and higher incidence of hypoxemia (78.6 vs. 20.8 %, p = 0.000). They presented relatively persistent fever (15.5 vs. 7 days, p = 0.000) and needed longer treatment in hospital (19.5 vs. 7 days, p = 0.000). Concerning treatment, they were given more intravenous γ-globulin (85.7 vs. 36.8 %, p = 0.000), glucocorticoids (78.6 vs. 24.3 %, p = 0.000) and mechanical ventilation (35.7 vs. 5.5 %, p = 0.001). Multiple analyses determined that hypoxemia was the only independent predictor for BO. The present study identified hypoxemia as the independent predictive factor of BO in adenoviral infected children, which was a novel and sensitive predictor for BO.