Serum YKL-40 levels may help distinguish exacerbation of post-infectious bronchiolitis obliterans from acute bronchiolitis in young children

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.

TGFβ1 and POSTN as biomarkers of postinfectious bronchiolitis obliterans and asthma in children

RATIONALE

Asthma and postinfectious bronchiolitis obliterans (PIBO) are common chronic lung diseases in company with wheezing in children. However, it is not clear what is common and unique mechanisms between the two diseases. Thus, we used proteomic analysis to compare differences in biomarkers between children with asthma and PIBO.

METHODS

Overall, 30 healthy children without respiratory underlying diseases, 18 children with asthma and 15 with PIBO were included for this study. Sequential window acquisition of all theoretical mass spectra (SWATH)-mass spectrometry (MS) was used to measure proteins in plasma samples. To identify specific pathways of each groups, we used the ingenuity pathway analysis (IPA) software.

RESULTS

We identified and quantified 354 proteins across all 63 samples in the SWATH-MS analysis. Forty eight proteins were significantly different among 3 groups. The upstream analysis of IPA suggested that inhibitor of nuclear factor kappa B kinase subunit beta (IKBKB) was the upstream inhibitor of 4 differentially expressed proteins (DEPs) in asthma, while the upstream activator in PIBO subjects. Among 4 DEPs, TGF-β1 in PIBO and periostin in asthma were negatively correlated with forced expiratory volume in 1 s (FEV1), FEV1/forced vital capacity, maximal med-expiratory flow, and PC20, respectively.

CONCLUSION

These findings demonstrate that transforming growth factor β1 and periostin were unique biomarkers of PIBO and asthma in children, respectively. The mechanism regulated by IKBKB may be therapeutically relevant for PIBO and asthma.

Post-infectious bronchiolitis obliterans in children: Clinical and radiological evaluation and long-term results

BACKGROUND AND OBJECTIVE

This study aims to evaluate clinical and radiological findings and treatment outcomes of the patients with PIBO.

METHODS

One hundred fourteen children were enrolled. Initial demographic and clinical findings were evaluated. Pre- and post-treatment clinical and radiological findings were compared.

RESULTS

The median age of the patients at initial pulmonary injury was 7,2 months, the median age at diagnosis was 17.5 months. Persistent wheezing was the most common complaint. Thirty-five patients had mechanical ventilation history. 82,5% of patients had clinical improvement. Bronchiectasis, atelectasis, hyperinflation and air trapping in HRCT improved significantly with treatment. Post-treatment Bhalla scores decreased from 8.3 to 6.5 (p= 0,001). Improvement was observed in radiological and clinical findings after treatment.

CONCLUSIONS

This study is one of the largest studies in the literature and one of the few studies that evaluate clinical and radiological outcomes of patients with PIBO.

Relevance of Plasma Matrix Metalloproteinase-9 for Bronchiolitis Obliterans Syndrome after Allogeneic Hematopoietic Cell Transplantation

Bronchiolitis obliterans syndrome (BOS) is a highly morbid form of chronic graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (HCT). Several plasma proteins have been identified as biomarkers for BOS after lung transplantation. The relevance of these biomarkers in BOS patients after allogeneic HCT has not been examined. We hypothesized that biomarkers associated with BOS after lung transplantation are also associated with BOS after allogeneic HCT. We tested plasma samples from 33 adult HCT patients who participated in a phase II multicenter study of fluticasone, azithromycin, and montelukast (FAM) treatment for new-onset BOS (NCT01307462), and matched control samples of HCT patients who had non-BOS chronic GVHD (n = 31) and those who never experienced chronic GVHD (n = 29) (NCT00637689 and NCT01902576). Candidate biomarkers included matrix metalloproteinase-9 (MMP-9), MMP-3, and chitinase-3-like-1 glycoprotein (YKL-40). MMP-9 concentrations were higher in the patients with BOS compared with those with non-BOS chronic GVHD (P = .04) or no chronic GVHD (P < .001). MMP-3 concentrations were higher in patients with BOS (P < .001) or non-BOS chronic GVHD (P < .001) compared with those with no chronic GVHD. YKL-40 concentrations did not differ statistically among the 3 groups. MMP-9 concentrations before starting FAM therapy were higher in patients who experienced treatment failure within 6 months compared with those with treatment success (P = .006), whereas MMP-3 or YKL-40 concentrations did not differ statistically between these 2 groups. Patients with an MMP-9 concentration ≥200,000 pg/mL before starting FAM therapy had worse overall survival compared with those with lower MMP-9 concentrations. Our data suggest that plasma MMP-9 concentration could serve as a relevant biomarker at diagnosis of BOS after allogeneic HCT for prognostication of survival and for prediction of treatment response. Further validation is needed to confirm our findings.

Postinfectious Bronchiolitis Obliterans in Children: Diagnostic Workup and Therapeutic Options: A Workshop Report

Bronchiolitis obliterans (BO) is a rare, chronic form of obstructive lung disease, often initiated with injury of the bronchiolar epithelium followed by an inflammatory response and progressive fibrosis of small airways resulting in nonuniform luminal obliteration or narrowing. The term BO comprises a group of diseases with different underlying etiologies, courses, and characteristics. Among the better recognized inciting stimuli leading to BO are airway pathogens such as adenovirus and mycoplasma, which, in a small percentage of infected children, will result in progressive fixed airflow obstruction, an entity referred to as postinfectious bronchiolitis obliterans (PIBO). The present knowledge on BO in general is reasonably well developed, in part because of the relatively high incidence in patients who have undergone lung transplantation or bone marrow transplant recipients who have had graft-versus-host disease in the posttransplant period. The cellular and molecular pathways involved in PIBO, while assumed to be similar, have not been adequately elucidated. Since 2016, an international consortium of experts with an interest in PIBO assembles on a regular basis in Geisenheim, Germany, to discuss key areas in PIBO which include diagnostic workup, treatment strategies, and research fields.