The nature of chronic rejection after lung transplantation: a murine orthotopic lung transplant study.

Introduction: Chronic rejection is a major complication post-transplantation. Within lung transplantation, chronic rejection was considered as airway centred. Chronic Lung Allograft Dysfunction (CLAD), defined to cover all late chronic complications, makes it more difficult to understand chronic rejection from an immunological perspective. This study investigated the true nature, timing and location of chronic rejection as a whole, within mouse lung transplantation. Methods: 40 mice underwent an orthotopic left lung transplantation, were sacrificed at day 70 and evaluated by histology and in vivo µCT. For timing and location of rejection, extra grafts were sacrificed at day 7, 35, 56 and investigated by ex vivo µCT or single cell RNA (scRNA) profiling. Results: Chronic rejection originated as innate inflammation around small arteries evolving toward adaptive organization with subsequent end-arterial fibrosis and obliterans. Subsequently, venous and pleural infiltration appeared, followed by airway related bronchiolar folding and rarely bronchiolitis obliterans was observed. Ex vivo µCT and scRNA profiling validated the time, location and sequence of events with endothelial destruction and activation as primary onset. Conclusion: Against the current belief, chronic rejection in lung transplantation may start as an arterial response, followed by responses in venules, pleura, and, only in the late stage, bronchioles, as may be seen in some but not all patients with CLAD.

Association Between FEV1 Decline Rate and Mortality in Long-Term Follow-Up of a 21-Patient Pilot Clinical Trial of Inhaled Liposomal Cyclosporine Plus Standard-of-Care Versus Standard-of-Care Alone for Bronchiolitis Obliterans Syndrome After Lung Transplantation.

BACKGROUND The association between forced expiratory volume in 1 second (FEV1) trajectory and mortality in bronchiolitis obliterans syndrome (BOS) is not well defined. Using long-term data from a prior clinical trial of inhaled liposomal cyclosporine A (L-CsA-I) for lung transplant patients with BOS, this study examined the association between longitudinal FEV1 change and mortality. MATERIAL AND METHODS We analyzed long-term data from a clinical trial which randomized 21 patients with BOS (³20% decrease in FEV1 from personal maximum) to receive L-CsA-I plus standard-of-care (n=11) or standard-of-care (SOC) alone (n=10) for 24 weeks. A joint statistical model, combining a linear mixed model for FEV1 change and Cox regression for mortality, was utilized to examine the overall association between FEV1 trajectory and mortality during follow-up. RESULTS The 21 trial participants (10 single, 11 double lung recipients) had a mean FEV1 of 1.7±0.6 Liters at randomization. Median follow-up post-randomization was 35 months. In joint model analysis, 1 percent FEV1 decline predicted 1.076-fold increased mortality risk (95% confidence interval: -0.998 to 1.160, p=0.058). FEV1 decline was reduced by 2.6% per year in L-CsA-I patients compared to SOC (p=0.210), and overall survival at 1/3/5 years was 91%/64%/27% vs 90%/20%/0% for L-CsA-I versus SOC, respectively (p=0.164). CONCLUSIONS In BOS patients, greater longitudinal FEV1 decline predicts increased mortality. Trends towards prolonged stabilization of FEV1 and improved survival were observed with L-CsA-I receipt. Further analyses will aid in evaluating the utility of FEV1 change as a survival predictor, having implications in BOS management and future trial design.

Bronquiolitis obliterante posinfecciosa secundaria a adenovirus / Post-infectious bronchiolitis obliterans secondary to adenovirus

La bronquiolitis obliterante es una rara enfermedad respiratoria obstructiva crónica, secundaria a una agresión de las vías respiratorias inferiores que provoca inflamación y obliteración, parcial o total, de las mismas. Existen diferentes causas que la provocan, siendo la infecciosa la más frecuente en Pediatría, principalmente, por adenovirus. Se presenta el caso de un lactante varón de 18 meses de edad, con el antecedente de ingreso a los 8 meses en la unidad de cuidados intensivos pediátricos por bronquitis secundaria a virus respiratorio sincitial y adenovirus. Posteriormente a este episodio, presenta de forma persistente dificultad respiratoria y auscultación pulmonar patológica. La tomografía computarizada pulmonar de alta resolución muestra patrón en mosaico con áreas de atrapamiento aéreo y disminución del calibre vascular en las zonas afectas, hallazgos sugestivos de bronquiolitis obliterante. (AU)

Bronchiolitis obliterans is a rare chronic obstructive respiratory disease secondary to damage of the lower respiratory tract causing inflammation and partial or total obliteration of it. There are different causes, being infectious the most frequent in pediatrics, mainly due to adenovirus. We present the case of an 18-month-old male infant with a history of admission to the Pediatric Intensive Care Unit at 8 months of age due to bronchitis secondary to respiratory syncytial virus and adenovirus. After this episode, he presented persistent respiratory distress and pathological pulmonary auscultation. High resolution pulmonary computed tomography showed a mosaic pattern with areas of air trapping and decreased vascular caliber in the affected areas, findings suggestive of bronchiolitis obliterans. (AU)

A review of the therapeutic potential of the cysteinyl leukotriene antagonist Montelukast in the treatment of bronchiolitis obliterans syndrome following lung and hematopoietic-stem cell transplantation and its possible mechanisms.

Lung and hematopoietic stem cell transplantation are therapeutic modalities in chronic pulmonary and hematological diseases, respectively. One of the complications in these patients is the development of bronchiolitis obliterans syndrome (BOS). The efficacy and safety of available treatment strategies in BOS remain a challenge. A few mechanisms have been recognized for BOS in lung transplant and graft-versus-host disease (GVHD) patients involving the TH-1 and TH-2 cells, NF-kappa B, TGF-b, several cytokines and chemokines, and cysteinyl leukotrienes (CysLT). Montelukast is a highly selective CysLT receptor antagonist that has been demonstrated to exert anti-inflammatory and anti-fibrotic effects in abundant experiments. One area of interest for the use of montelukast is lung transplants or GVHD-associated BOS. Herein, we briefly review data regarding the mechanisms involved in BOS development and montelukast administration as a treatment modality for BOS, and finally, the possible relationship between CysLTs antagonism and BOS improvement will be discussed.

A review of the therapeutic potential and possible mechanism of Montelukast in the treatment of bronchiolitis obliterans syndrome following lung and hematopoietic stem cell transplantationLung and bone marrow transplantation are therapeutic modalities in chronic diseases of the lungs and the blood, respectively. One of the complications in these patients is the development of Bronchiolitis obliterans syndrome (BOS). The efficacy and safety of available treatment strategies in BOS remain a challenge. A few mechanisms for BOS in lung transplant and graft-versus-host disease (GVHD) patients involving many immune components have been recognized. Cysteinyl leukotrienes are products of plasma membrane phospholipids that increase smooth muscle contraction, microvascular permeability, and airway mucus secretion. Montelukast is a highly selective cysteinyl leukotriene receptor blocker demonstrated to exert anti-inflammatory and anti-fibrotic effects. One area of interest for the use of montelukast is in lung transplant- or GVHD-associated BOS. In this article, we briefly review data regarding the mechanisms involved in BOS development and montelukast administration as a treatment modality for BOS. Finally, the possible relationship between cysteinyl leukotriene inhibition and BOS improvement will be discussed.

Application of metagenomic next-generation sequencing in the clinical diagnosis of infectious diseases after allo-HSCT: a single-center analysis.

BACKGROUND: We investigated the value of metagenomic next-generation sequencing (mNGS) in diagnosing infectious diseases in patients receiving allogeneic hematopoietic stem cell transplantation (allo-HSCT). METHODS: Fifty-four patients who had fever following allo-HSCT from October 2019 to February 2022 were enrolled. Conventional microbiological tests (CMTs) and mNGS, along with imaging and clinical manifestations, were used to diagnose infection following allo-HSCT. The clinical diagnostic value of mNGS was evaluated. RESULTS: A total of 61 mNGS tests were performed, resulting in the diagnosis of 46 cases of infectious diseases. Among these cases, there were 22 cases of viral infection, 13 cases of fungal infection, and 11 cases of bacterial infection. Moreover, 27 cases (58.7%) were classified as bloodstream infections, 15 (32.6%) as respiratory infections, 2 (4.3%) as digestive system infections, and 2 (4.3%) as central nervous system infections. Additionally, there were 8 cases with non-infectious diseases (8/54, 14.81%), including 2 cases of interstitial pneumonia, 2 cases of bronchiolitis obliterans, 2 cases of engraftment syndrome, and 2 cases of acute graft-versus-host disease. The positive detection rates of mNGS and CMT were 88.9% and 33.3%, respectively, with significant differences (P < 0.001). The sensitivity of mNGS was 97.82%, the specificity was 25%, the positive predictive value was 93.75%, and the negative predictive value was 50%. Following treatment, 51 patients showed improvement, and 3 cases succumbed to multidrug-resistant bacterial infections. CONCLUSIONS: mNGS plays an important role in the early clinical diagnosis of infectious diseases after allo-HSCT, which is not affected by immunosuppression status, empiric antibiotic therapy, and multi-microbial mixed infection.

Detection of Bronchiolitis Obliterans Syndrome Using Nitrogen Multiple Breath Washout in Children Posthemopoietic Stem Cell Transplant.

Bronchiolitis obliterans syndrome (BOS) is a severe complication following hemopoietic stem cell transplantation (HSCT) and is often undetected until there is significant deterioration in pulmonary function. Lung clearance index (LCI2.5) derived from the nitrogen multiple breath washout (N2MBW) test may be more feasible and sensitive than spirometry, which is currently used for surveillance and detection of BOS. We aimed to examine the feasibility of performing surveillance N2MBW in children post-HSCT, and in an exploratory analysis, determine if LCI2.5 led to earlier detection of BOS when compared to spirometric indices. Participants aged 5 to 17 years were recruited prior to receiving HSCT into a prospective, single-center, feasibility study at the Royal Children's Hospital, Melbourne. N2MBW and spirometry were performed within the month prior to transplant and repeated at 3, 6, 9, and 12 months post-transplant. Data were also collected on the presence of graft-versus-host (GVHD) disease in any organ, including the lungs. Twenty-one (12 male) children with a mean age of 13.4 (range 9.2 to 17.1) years at recruitment participated in this study. Prior to HSCT, all participants had normal LCI2.5, while 16 (76%) demonstrated normal forced expiratory volume in 1 second (FEV1). Ninety-nine percent of N2MBW tests were technically acceptable, compared with 66% of spirometry tests. Three participants developed BOS, while 2 participants died of other respiratory complications. At 6 and 12 months post-transplant, the BOS group had increases in LCI2.5 ranging from 3 to 5 units and mean reductions in FEV1 % predicted of 40% to 53% relative to pre HSCT values, respectively. In those who developed BOS, post-HSCT LCI2.5 values were significantly worse when compared with the no BOS group (P < .001). Relative changes in LCI2.5 and FEV1 were both predictive of BOS at 6 months post HSCT. This study demonstrates that N2MBW is a more feasible test compared with spirometry in children post HSCT. However, in an exploratory analysis, LCI2.5 did not lead to earlier detection of BOS, when compared to spirometry.

IL-27 Levels in Bronchoalveolar Lavage Fluid in Children with Post-infectious Bronchiolitis Obliterans.

Background: Pulmonary neutrophils may play a crucial role in the development of bronchiolitis obliterans (BO) following measles virus infection. IL-27 could potentially have a negative regulatory effect on the release of reactive oxygen species and cytotoxic granules in neutrophils. Objective: To investigate the levels of IL-27 in the bronchoalveolar lavage fluid (BALF) of children with post-infectious bronchiolitis obliterans (PIBO) and analyze the relationship between IL-27 levels and neutrophil proportions. Methods: A total of 24 children with PIBO were recruited for the experimental group, while 23 children with bronchial foreign bodies were included in the control group. Bronchoscopic alveolar lavage was performed in both groups. The levels of IL-27 in BALF were measured using enzyme-linked immunosorbent assay (ELISA). The proportions of neutrophils in BALF were determined by smear staining. The relationship between the levels of IL-27 in BALF and the neutrophil proportions was analyzed by the Pearson test. Results: The levels of IL-27 in BALF were significantly lower in children with PIBO compared to children with bronchial foreign bodies (p<0.05). Additionally, the proportions of neutrophils in BALF were significantly higher in children with PIBO compared to children with bronchial foreign bodies (p<0.05). The levels of IL-27 were negatively correlated with the neutrophil proportions in BALF in children with PIBO (p<0.05), but not in children with bronchial foreign bodies (p>0.05). Conclusion: The present study suggests that a decrease in IL-27 may be associated with an increase in neutrophils in BALF and may contribute to the pathogenesis of PIBO.

Ventilatory capacity in CLAD is driven by dysfunctional airway structure.

BACKGROUND: Chronic lung allograft dysfunction (CLAD) encompasses three main phenotypes: bronchiolitis obliterans syndrome (BOS), restrictive allograft syndrome (RAS) and a Mixed phenotype combining both pathologies. How the airway structure in its entirety is affected in these phenotypes is still poorly understood. METHODS: A detailed analysis of airway morphometry was applied to gain insights on the effects of airway remodelling on the distribution of alveolar ventilation in end-stage CLAD. Ex vivo whole lung µCT and tissue-core µCT scanning of six control, six BOS, three RAS and three Mixed explant lung grafts (9 male, 9 female, 2014-2021, Leuven, Belgium) were used for digital airway reconstruction and calculation of airway dimensions in relation to luminal obstructions. FINDINGS: BOS and Mixed explants demonstrated airway obstructions of proximal bronchioles (starting at generation five), while RAS explants particularly had airway obstructions in the most distal bronchioles (generation >12). In BOS and Mixed explants 76% and 84% of bronchioles were obstructed, respectively, while this was 22% in RAS. Bronchiolar obstructions were mainly caused by lymphocytic inflammation of the airway wall or fibrotic remodelling, i.e. constrictive bronchiolitis. Proximal bronchiolectasis and imbalance in distal lung ventilation were present in all CLAD phenotypes and explain poor lung function and deterioration of specific lung function parameters. INTERPRETATION: Alterations in the structure of conducting bronchioles revealed CLAD to affect alveolar ventilatory distribution in a regional fashion. The significance of various obstructions, particularly those associated with mucus, is highlighted. FUNDING: This research was funded with the National research fund Flanders (G060322N), received by R.V.

Neuronal ceroid lipofuscinosis type 11 diagnosed patient with bi-allelic variants in GRN gene: case report and review of literature.

OBJECTIVES: Neuronal ceroid lipofuscinosis type 11 (NCL11) is a rare disease that presents with progressive cognitive decline, epilepsy, visual impairment, retinal atrophy, cerebellar ataxia and cerebellar atrophy. We present herein a case of NCL11 in a patient diagnosed with neuromotor developmental delay, epilepsy, bronchiolitis obliterans and hypothyroidism. CASE PRESENTATION: A 4-year-old male patient was admitted to our clinic with global developmental delay and a medical history that included recurrent hospitalizations for pneumonia at the age of 17 days, and in months 4, 5 and 7. Family history revealed a brother with similar clinical findings (recurrent pneumonia, hypothyroidism, hypotonicity, swallowing dysfunction and neuromotor delay) who died from pneumonia at the age of 22 months. Computed tomography of the thorax was consistent with bronchiolitis obliterans, while epileptic discharges were identified on electroencephalogram with a high incidence of bilateral fronto-centro-temporal and generalized spike-wave activity but no photoparoxysmal response. Cranial MRI revealed T2 hyperintense areas in the occipital periventricular white matter and volume loss in the white matter, a thin corpus callosum and vermis atrophy. A whole-exome sequencing molecular analysis revealed compound heterozygous c.430G>A (p.Asp144Asn) and c.415T>C (p.Cys139Arg) variants in the GRN gene. CONCLUSIONS: The presented case indicates that NCL11 should be taken into account in patients with epilepsy and neurodegenerative diseases.

Clinical risk factors and prognostic model for patients with bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation.

Bronchiolitis obliterans syndrome (BOS) is a common and potentially devastating noninfectious pulmonary complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Currently, predictive tools for BOS are not available. We aimed to identify the clinical risk factors and establish a prognostic model for BOS in patients who undergo allo-HSCT. We retrospectively identified a cohort comprising 195 BOS patients from 6100 consecutive patients who were allografted between 2008 and 2022. The entire cohort was divided into a derivation cohort and a validation cohort based on the time of transplantation. Via multivariable Cox regression methods, declining forced expiratory volume at 1 s (FEV1) to <40%, pneumonia, cGVHD except lung, and respiratory failure were found to be independent risk factors for the 3-year mortality of BOS. A risk score called FACT was constructed based on the regression coefficients. The FACT model had an AUC of 0.863 (95% CI: 0.797-0.928) in internal validation and 0.749 (95% CI: 0.621-0.876) in external validation. The calibration curves showed good agreement between the FACT-predicted probabilities and actual observations. The FACT risk score will help to identify patients at high risk and facilitate future research on developing novel, effective interventions to personalize treatment.

Single-cell resolution of human airway epithelial cells exposed to bronchiolitis obliterans-associated chemicals.

Bronchiolitis obliterans (BO) is a fibrotic lung disease characterized by progressive luminal narrowing and obliteration of the small airways. In the nontransplant population, inhalation exposure to certain chemicals is associated with BO; however, the mechanisms contributing to disease induction remain poorly understood. This study's objective was to use single-cell RNA sequencing for the identification of transcriptomic signatures common to primary human airway epithelial cells after chemical exposure to BO-associated chemicals-diacetyl or nitrogen mustard-to help explain BO induction. Primary airway epithelial cells were cultured at air-liquid interface and exposed to diacetyl, nitrogen mustard, or control vapors. Cultures were dissociated and sequenced for single-cell RNA. Differential gene expression and functional pathway analyses were compared across exposures. In total, 75,663 single cells were captured and sequenced from all exposure conditions. Unbiased clustering identified 11 discrete phenotypes, including 5 basal, 2 ciliated, and 2 secretory cell clusters. With chemical exposure, the proportion of cells assigned to keratin 5+ basal cells decreased, whereas the proportion of cells aligned to secretory cell clusters increased compared with control exposures. Functional pathway analysis identified interferon signaling and antigen processing/presentation as pathways commonly upregulated after diacetyl or nitrogen mustard exposure in a ciliated cell cluster. Conversely, the response of airway basal cells differed significantly with upregulation of the unfolded protein response in diacetyl-exposed basal cells, not seen in nitrogen mustard-exposed cultures. These new insights provide early identification of airway epithelial signatures common to BO-associated chemical exposures.NEW & NOTEWORTHY Bronchiolitis obliterans (BO) is a devastating fibrotic lung disease of the small airways, or bronchioles. This original manuscript uses single-cell RNA sequencing for identifying common signatures of chemically exposed airway epithelial cells in BO induction. Chemical exposure reduced the proportion of keratin 5+ basal cells while increasing the proportion of keratin 4+ suprabasal cells. Functional pathways contributory to these shifts differed significantly across exposures. These new results highlight similarities and differences in BO induction across exposures.

Restrictive allograft dysfunction rather than bronchiolitis obliterans syndrome had a major impact on the overall survival after living-donor lobar lung transplantation.

PURPOSE: Chronic lung allograft dysfunction (CLAD) is a known long-term fatal disorder after lung transplantation. In this study, we evaluated the CLAD classification of the International Society for Heart and Lung Transplantation (ISHLT) for living-donor lobar lung transplantation (LDLLT). METHODS: We conducted a single-center retrospective review of data from 73 patients who underwent bilateral LDLLT between 1998 and 2019. Factors related to opacity on computed tomography (CT) and restriction on pulmonary function tests (PFTs) were also analyzed. RESULTS: Overall, 26 (36%) patients were diagnosed with CLAD, including restrictive allograft syndrome (RAS), n = 10 (38.5%); bronchiolitis obliterans syndrome (BOS), n = 8 (30.8%); mixed, n = 1 (3.8%); undefined, n = 2 (7.7%); and unclassified, n = 5 (19.2%). The 5-year survival rate after the CLAD onset was 60.7%. The survival of patients with BOS was significantly better than that of patients with RAS (p = 0.012). In particular, patients with restriction on PFT had a significantly worse survival than those without restriction (p = 0.001). CONCLUSIONS: CLAD after bilateral LDLLT does not have a major impact on the recipient survival, especially in patients with BOS. Restriction on PFT may predict a particularly poor prognosis in patients with CLAD after bilateral LDLLT.

Chest imaging classification in Mycoplasma pneumoniae pneumonia is associated with its clinical features and outcomes.

BACKGROUND: The imaging findings of Mycoplasma pneumoniae pneumonia (MPP) vary; however, few studies have focused on the relationship of imaging classification with clinical manifestations and outcomes. OBJECTIVE: To prospectively investigate whether chest imaging classification in Mycoplasma pneumoniae pneumonia (MPP) is associated with its clinical features and outcomes. METHODS: A total of 1,401 hospitalized children with MPP were enrolled from January 2019 to December 2021. Imaging findings were categorized as bronchopneumonia and consolidation/atelectasis according to X-ray, and bronchopneumonia, consolidation/atelectasis, bronchiolitis, and mosaic pattern according to computed tomography (CT). Clinical characteristics and outcomes of patients with different imaging classifications were prospectively analyzed based on electronic medical records. RESULTS: Bronchopneumonia was the most common finding (59.6%), while consolidation/atelectasis was the most severe group. Clinical manifestations and laboratory indicators for the consolidation/atelectasis group included serious abnormalities. Further, outcomes of the patients were worse, including having longer total durations of fever and hospitalization, greater hospitalization expenses, and a higher likelihood of developing refractory MPP, necrotizing pneumonia, and bronchiolitis obliterans (BO) in this group. The incidence of bronchiolitis, a disease characterized by a high prevalence of fever, moist rales, and an atopic constitution, tended to increase after the coronavirus disease pandemic and predisposed patients to BO. A mosaic pattern occurred in allergic and young individuals, with wheezing as the main manifestation, with patients having relatively mild symptoms and good outcomes. CONCLUSION: Different imaging classifications have different clinical features and clinical outcomes; thus, formulating an imaging-based classification system is of great clinical value.

Impulse Oscillometry Versus Spirometry to Detect Bronchiolitis Obliterans Syndrome in Bilateral Lung Transplant Recipients: A Prospective Diagnostic Study.

BACKGROUND: Chronic lung allograft dysfunction (CLAD), and especially bronchiolitis obliterans syndrome (BOS), remain dominant causes of morbidity and mortality after lung transplantation. Interest is growing in the forced oscillation technique, of which impulse oscillometry (IOS) is a form, as a tool to improve our understanding of these disorders. However, data remain limited and no longitudinal studies have been published, meaning there is no information regarding any capacity IOS may have for the early detection of CLAD. METHODS: We conducted a prospective longitudinal study enrolling a consecutive sample of adult bilateral lung transplant recipients with healthy lung allografts or CLAD and performed ongoing paired IOS and spirometry tests on a clinically determined basis. We assessed for correlations between IOS and spirometry and examined any predictive value either modality may hold for the early detection of BOS. RESULTS: We enrolled 91 patients and conducted testing for 43 mo, collecting 558 analyzable paired IOS and spirometry tests, with a median of 9 tests per subject (interquartile range, 5-12) and a median testing interval of 92 d (interquartile range, 62-161). Statistically significant moderate-to-strong correlations were demonstrated between all IOS parameters and spirometry, except resistance at 20 Hz, which is a proximal airway measure. No predictive value for the early detection of BOS was found for IOS or spirometry. CONCLUSIONS: This study presents the first longitudinal data from IOS after lung transplantation and adds considerably to the growing literature, showing unequivocal correlations with spirometry but failing to demonstrate a predictive value for BOS.

Doença enxerto contra hospedeiro crônica e seu acometimento pulmonar: uma revisão de literatura / Chronic graft-versus-host disease and its pulmonary involvement: a literature review

A doença enxerto contra hospedeiro crônica é a principal complicação pós transplante alogênico não relacionada à recaída, impactando na morbimortalidade dos pacientes. Nesse contexto, o acometimento pulmonar leva a um dos piores prognósticos não só em relação a alta mortalidade como em piora da qualidade de vida. Sendo assim, o estudo da doença pulmonar pós-transplante é de suma importância, visto que o diagnóstico atual parece não englobar todo espectro da doença e o manejo depende do reconhecimento precoce e carece de melhores opções que ainda estão em estudo. O objetivo do trabalho é revisar os pontos principais do tema, elucidar questões relativas ao diagnóstico e proporcionar aos profissionais da área maior entendimento sobre o tema

Chronic graft-versus-host disease is the leading non-relapse-related complication after allogeneic transplantation, impacting patient morbidity and mortality. In this context, pulmonary involvement leads to one of the worst prognoses, not only in terms of high mortality but also in terms of reduced quality of life. Therefore, the study of posttransplant pulmonary disease is of utmost importance, given that the current diagnostic approach does not seem to cover the entire spectrum of the disease, and its management relies on early recognition, lacking better options that are still under study. The objective of this work is to review the key points of the topic, elucidate issues related to diagnosis, and provide healthcare professionals with a better understanding of the subject

Risk factors and prediction models for bronchiolitis obliterans after severe adenoviral pneumonia.

Severe adenoviral pneumonia (SAP) can cause post-infectious bronchiolitis obliterans (PIBO) in children. We aimed to investigate the relevant risk factors for PIBO and develop a predictive nomogram for PIBO in children with SAP. This prospective study analysed the clinical data of hospitalised children with SAP and categorised them into the PIBO and non-PIBO groups. Least absolute shrinkage and selection operator (LASSO) regressions were applied to variables that exhibited significant intergroup differences. Logistic regression was adopted to analyse the risk factors for PIBO. Additionally, a nomogram was constructed, and its effectiveness was assessed using calibration curves, C-index, and decision curve analysis. A total of 148 hospitalised children with SAP were collected in this study. Among them, 112 achieved favourable recovery, whereas 36 developed PIBO. Multivariable regression after variable selection via LASSO revealed that aged < 1 year (OR, 2.38, 95% CI, 0.82-6.77), admission to PICU (OR, 24.40, 95% CI, 7.16-105.00), long duration of fever (OR, 1.16, 95% CI, 1.04-1.31), and bilateral lung infection (OR, 8.78, 95% CI, 1.32-195.00) were major risk factors for PIBO. The nomogram model included the four risk factors: The C-index of the model was 0.85 (95% CI, 0.71-0.99), and the area under the curve was 0.85 (95% CI, 0.78-0.92). The model showed good calibration with the Hosmer-Lemeshow test (χ2 = 8.52, P = 0.38) and was useful in clinical settings with decision curve analysis. CONCLUSION: Age < 1 year, PICU admission, long fever duration, and bilateral lung infection are independent risk factors for PIBO in children with SAP. The nomogram model may aid clinicians in the early diagnosis and intervention of PIBO. WHAT IS KNOWN: • Adenoviruses are the most common pathogens associated with PIBO. • Wheezing, tachypnoea, hypoxemia, and mechanical ventilation are the risk factors for PIBO. WHAT IS NEW: • Age < 1 year, admission to PICU, long duration of fever days, and bilateral lung infection are independent risk factors for PIBO in children with SAP. • A prediction model presented as a nomogram may help clinicians in the early diagnosis and intervention of PIBO.