Update in postinfectious bronchiolitis obliterans

Immune dysregulation as a driver of bronchiolitis obliterans

Bronchiolitis obliterans (BO) is a disease characterized by airway obstruction and fibrosis that can occur in all age groups. Bronchiolitis obliterans syndrome (BOS) is a clinical manifestation of BO in patients who have undergone lung transplantation or hematopoietic stem cell transplantation. Persistent inflammation and fibrosis of small airways make the disease irreversible, eventually leading to lung failure. The pathogenesis of BO is not entirely clear, but immune disorders are commonly involved, with various immune cells playing complex roles in different BO subtypes. Accordingly, the US Food and Drug Administration (FDA) has recently approved several new drugs that can alleviate chronic graft-versus-host disease (cGVHD) by regulating the function of immune cells, some of which have efficacy specifically with cGVHD-BOS. In this review, we will discuss the roles of different immune cells in BO/BOS, and introduce the latest drugs targeting various immune cells as the main target. This study emphasizes that immune dysfunction is an important driving factor in its pathophysiology. A better understanding of the role of the immune system in BO will enable the development of targeted immunotherapies to effectively delay or even reverse this condition.

Serum IL-17A and IL-6 in paediatric Mycoplasma pneumoniae pneumonia: implications for different endotypes

Paediatric Mycoplasma pneumoniae pneumonia (MPP) is a heterogeneous disease with a diverse spectrum of clinical phenotypes. No studies have demonstrated the relationship between underlying endotypes and clinical phenotypes as well as prognosis about this disease. Thus, we conducted a multicentre prospective longitudinal study on children hospitalized for MPP between June 2021 and March 2023, with the end of follow-up in August 2023. Blood samples were collected and processed at multiple time points. Multiplex cytokine assay was performed to characterize serum cytokine profiles and their dynamic changes after admission. Cluster analysis based on different clinical phenotypes was conducted. Among the included 196 patients, the levels of serum IL-17A and IL-6 showed remarkable variabilities. Four cytokine clusters based on the two cytokines and four clinical groups were identified. Significant elevation of IL-17A mainly correlated with diffuse bronchiolitis and lobar lesion by airway mucus hypersecretions, while that of IL-6 was largely associated with lobar lesion which later developed into lung necrosis. Besides, glucocorticoid therapy failed to inhibit IL-17A, and markedly elevated IL-17A and IL-6 levels may correlate with lower airway obliterans. Our study provides critical relationship between molecular signatures (endotypes) and clustered clinical phenotypes in paediatric patients with MPP.

Risk Factors for Developing Adenovirus-Associated Post-Infectious Bronchiolitis Obliterans

BACKGROUND

Risk factors for progression of adenovirus (AdV)-associated bronchiolitis (AdV-B) to post-infectious bronchiolitis obliterans (PIBO) are poorly defined. We aimed to investigate this in a multicenter cohort.

METHODS

A multicenter hospital-based analysis included children admitted with AdV-B in Jerusalem during 2016-2022. A case-control analysis included AdV-PIBO patients in Jerusalem during 2005-2023. Cases were compared to randomly assigned controls admitted with AdV-B without progression to AdV-PIBO. Multivariate analysis with logistic regression was used.

RESULTS

The annual incidence of AdV-B admissions and AdV-PIBO increased during 2016-2022, during which 1522 children were admitted with AdV-B and 8 developed AdV-PIBO (0.5%). Of 30 AdV-PIBO cases identified during 2005-2023, available data were compared for 25 of them (72% boys; mean age ± standard deviation 1.2 ± 0.8 years) and 139 controls (66% boys; mean age 1.0 ± 0.6 years, p = 0.5 for age). Jewish ethnicity was more common in the AdV-PIBO versus control group (92% vs. 66%, p = 0.009), as were oxygen supplementation (84% vs. 45%, p < 0.001), noninvasive ventilation (20% vs. 4%, p = 0.004), consolidations on chest X-ray (44% vs. 19%, p = 0.011), and lymphopenia (92% vs. 46%, p < 0.001). Combining Jewish ethnicity, lymphopenia, consolidations, and prolonged admission as independent risk factors yielded positive and negative predictive values of 68.8% and 90.5%, respectively.

CONCLUSION

These findings emphasize the urgent need for targeted preventive and management strategies. The identification of Jewish ethnicity as a risk factor may imply a genetic contribution to Adv-PIBO risk.

Determining the aetiology of lower respiratory tract illness in children

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Respiratory virus infections and adenovirus characteristics during acute exacerbation of chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease globally, characterized by obstructive ventilatory disorder under pulmonary function tests. Recent years have witnessed a yearly increase in the prevalence of COPD.

OBJECTIVE

To investigate the impact of respiratory virus infections on patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD), and to perform sequencing typing and mutation analysis of viruses with high detection rate.

METHODS

A total of 1523 inpatients with AECOPD admitted to our hospital from April 1,2020 to March 30,2022 were collected and divided into two groups: the infected group (n= 532) and the non-infected group (n= 991). The related indexes between the two groups were collected and compared (including clinical characteristics and laboratory tests that blood cell count, PCT, CRP, adenovirus, respiratory syncytial virus, rhinovirus, influenza A virus, influenza B virus, etc.).

RESULTS

In the infected group, the proportion of patients with palpitations (49.44% VS 8.07%, P< 0.001), lipid metabolism abnormalities (18.42% VS 39.96%, P< 0.001), heart failure (39.85% VS 29.87%, P< 0.001), disease duration (17.48 ± 7.47 VS 12.45 ± 11.43 d, P< 0.001), and poor prognosis (69.55% VS 17.15%, P< 0.001) were higher than those in the non-infected group; Adenovirus (ADV) accounted for 75.94% (404/532) of all infected viruses. 31 virus strains could be categorized into 16 ADV-C1, one ADV-C5, two ADV-B3, three ADV-B7, two ADV-D17, two ADV-D19, and five ADV-D27, which were similar to the serotypes reported in severe pneumonia. Furthermore, three strains of C1 adenovirus were found to be highly homologous to the original strain AF534906 by sequencing, and the phylogenetic trees of the three main structural genes were all on the same branch as the original strain. Base mutations and amino acid variants were found in each structural gene segment. In clinical data, it's found that patients with mutations are worse than those without mutations.

CONCLUSION

Respiratory viruses are common in patients with poor prognosis of AECOPD, especially adenovirus, respiratory syncytial virus. Respiratory virus infections will lead to the deterioration of patients with AECOPD, accompanied by longer treatment cycles and poor prognosis.