High Diagnostic Yield of Dedicated Pulmonary Screening before Hematopoietic Cell Transplantation in Children

Respiratory viruses in hematopoietic cell transplant candidates: impact of preexisting lower tract disease on outcomes

In myeloablative allogeneic HCT recipients, pretransplant LRD by any virus was associated with increased mortality.

Pretransplant respiratory virus infections (RVIs) have been shown to negatively affect hematopoietic cell transplantation (HCT) outcomes. The impact of and need for delay of HCT for pretransplant infection with human rhinovirus (HRV) or endemic human coronavirus (HCoV; 229E, OC43, NL63, and HKU1) remain controversial. We analyzed the impact of symptomatic RVI within ≤90 days before HCT on overall mortality, posttransplant lower respiratory tract disease (LRD), and days alive and out of hospital (DAOH) by day 100 post-HCT in multivariable models. Among 1,643 adult HCT recipients (58% allogeneic recipients), 704 (43%) were tested for RVI before HCT, and 307 (44%) tested positive. HRV was most commonly detected (56%). Forty-five (15%) of 307 HCT recipients had LRD with the same virus early after HCT. Pretransplant upper respiratory tract infection (URI) with influenza, respiratory syncytial virus, adenovirus, human metapneumovirus, parainfluenza virus, HRV, or endemic HCoV was not associated with increased overall mortality or fewer DAOH. However, in allogeneic recipients who received myeloablative conditioning, LRD due to any respiratory virus, including HRV alone, was associated with increased overall mortality (adjusted hazard ratio, 10.8 [95% confidence interval, 3.29-35.1] for HRV and 3.21 [95% confidence interval, 1.15-9.01] for all other viruses). HRV LRD was also associated with fewer DAOH. Thus, the presence of LRD due to common respiratory viruses, including HRV, before myeloablative allogeneic HCT was associated with increased mortality and hospitalization. Pretransplant URI due to HRV and endemic HCoV was not associated with these outcomes. Improved management strategies for pretransplant LRD are warranted.

Pulmonary microbiome and gene expression signatures differentiate lung function in pediatric hematopoietic cell transplant candidates

Impaired baseline lung function is associated with mortality after pediatric allogeneic hematopoietic cell transplantation (HCT), yet limited knowledge of the molecular pathways that characterize pretransplant lung function has hindered the development of lung-targeted interventions. In this study, we quantified the association between bronchoalveolar lavage (BAL) metatranscriptomes and paired pulmonary function tests performed a median of 1 to 2 weeks before allogeneic HCT in 104 children in The Netherlands. Abnormal pulmonary function was recorded in more than half the cohort, consisted most commonly of restriction and impaired diffusion, and was associated with both all-cause and lung injury-related mortality after HCT. Depletion of commensal supraglottic taxa, such as Haemophilus, and enrichment of nasal and skin taxa, such as Staphylococcus, in the BAL microbiome were associated with worse measures of lung capacity and gas diffusion. In addition, BAL gene expression signatures of alveolar epithelial activation, epithelial-mesenchymal transition, and down-regulated immunity were associated with impaired lung capacity and diffusion, suggesting a postinjury profibrotic response. Detection of microbial depletion and abnormal epithelial gene expression in BAL enhanced the prognostic utility of pre-HCT pulmonary function tests for the outcome of post-HCT mortality. These findings suggest a potentially actionable connection between microbiome depletion, alveolar injury, and pulmonary fibrosis in the pathogenesis of pre-HCT lung dysfunction.

Role of pre-transplant chest high-resolution computed tomography and serum galactomannan index in predicting post-transplant invasive pulmonary aspergillosis in allogeneic hematopoietic cell transplant recipients

INTRODUCTION

The role of pre-HCT chest high-resolution computed tomography (HRCT) and serum galactomannan index (GMI) in predicting the post-allogeneic hematopoietic cell transplant (HCT) invasive pulmonary aspergillosis (IPA) is debatable.

METHODS

This was a single-center, prospective study from 2014 to 2019. The primary objective was to study if pre-HCT chest HRCT and serum GMI predicted IPA post-HCT. The secondary objective was day +100 mortality. All consecutive, consenting patients of ≥12 years of age undergoing allo-HCT were included and had pre-HCT chest HRCT and serum GMI. All patients received mold active antifungal prophylaxis. The EORTC/MSG criteria were used for the diagnosis of IPA.

RESULTS

A total of 82 patients with median age 27 years (12-59 years) were included. The underlying diagnoses included hematological malignancies (79%) and aplastic anemia (21%). Fifteen percent of patients was treated for prior history of probable IPA (>6 weeks before HCT). Pre-HCT chest HRCT satisfied EORTC clinical criteria in 24% patients. Serum GMI ≥0.5 was seen in 27% of patients. Post-HCT probable IPA was seen in 24% of patients. There were more patients with pre-HCT chest HRCT findings satisfying EORTC clinical criteria (45% vs. 18%, P = .014) and GMI ≥0.5 (45% vs. 21%, P = .03) in the group with post-HCT IPA compared to those without IPA. There was higher day+100 mortality in patients with post-HCT IPA (55% vs. 18%, P = .001).

CONCLUSIONS

The presence of EORTC clinical criteria on pre-HCT chest HRCT, serum GMI ≥0.5, and prior history of IPA predicted post-HCT IPA.

The pulmonary metatranscriptome prior to pediatric HCT identifies post-HCT lung injury

Lung injury after pediatric allogeneic hematopoietic cell transplantation (HCT) is a common and disastrous complication that threatens long-term survival. To develop strategies to prevent lung injury, novel tools are needed to comprehensively assess lung health in HCT candidates. Therefore, this study analyzed biospecimens from 181 pediatric HCT candidates who underwent routine pre-HCT bronchoalveolar lavage (BAL) at the University Medical Center Utrecht between 2005 and 2016. BAL fluid underwent metatranscriptomic sequencing of microbial and human RNA, and unsupervised clustering and generalized linear models were used to associate microbiome gene expression data with the development of post-HCT lung injury. Microbe-gene correlations were validated using a geographically distinct cohort of 18 pediatric HCT candidates. The cumulative incidence of post-HCT lung injury varied significantly according to 4 pre-HCT pulmonary metatranscriptome clusters, with the highest incidence observed in children with pre-HCT viral enrichment and innate immune activation, as well as in children with profound microbial depletion and concomitant natural killer/T-cell activation (P < .001). In contrast, children with pre-HCT pulmonary metatranscriptomes containing diverse oropharyngeal taxa and lacking inflammation rarely developed post-HCT lung injury. In addition, activation of epithelial-epidermal differentiation, mucus production, and cellular adhesion were associated with fatal post-HCT lung injury. In a separate validation cohort, associations among pulmonary respiratory viral load, oropharyngeal taxa, and pulmonary gene expression were recapitulated; the association with post-HCT lung injury needs to be validated in an independent cohort. This analysis suggests that assessment of the pre-HCT BAL fluid may identify high-risk pediatric HCT candidates who may benefit from pathobiology-targeted interventions.

Possible role of highly activated mucosal NK cells against viral respiratory infections in children undergoing haematopoietic stem cell transplantation

Infection is the leading cause of non-relapse-related mortality after allogeneic haematopoietic stem cell transplantation (HSCT). Altered functions of immune cells in nasal secretions may influence post HSCT susceptibility to viral respiratory infections. In this prospective study, we determined T and NK cell numbers together with NK activation status in nasopharyngeal aspirates (NPA) in HSCT recipients and healthy controls using multiparametric flow cytometry. We also determined by polymerase chain reaction (PCR) the presence of 16 respiratory viruses. Samples were collected pre-HSCT, at day 0, +10, +20 and +30 after HSCT. Peripheral blood (PB) was also analyzed to determine T and NK cell numbers. A total of 27 pediatric HSCT recipients were enrolled and 16 of them had at least one viral detection (60%). Rhinovirus was the most frequent pathogen (84% of positive NPAs). NPAs of patients contained fewer T and NK cells compared to healthy controls (p = 0.0132 and p = 0.120, respectively). Viral PCR + patients showed higher NK cell number in their NPAs. The activating receptors repertoire expressed by NK cells was also higher in NPA samples, especially NKp44 and NKp46. Our study supports NK cells relevance for the immune defense against respiratory viruses in HSCT recipients.

Infection with a respiratory virus before hematopoietic cell transplantation is associated with alloimmune-mediated lung syndromes

BACKGROUND

Alloimmune-mediated lung syndromes (allo-LSs) are life-threatening complications after hematopoietic cell transplantation (HCT). Respiratory virus (RV) has been suggested to play a role in the pathogenesis.

OBJECTIVE

We studied the relation between RV DNA/RNA detection in the upper/lower airways before HCT and the occurrence of allo-LSs.

METHODS

We retrospectively analyzed all HCT recipients between 2004 and 2014, in whom real-time PCR for RV was performed in nasopharyngeal aspirates (NPAs) and bronchoalveolar lavage (BAL) fluid before HCT. The main outcome of interest was the presence of an allo-LS, which was defined as idiopathic pneumonia syndrome or bronchiolitis obliterans syndrome. Other outcomes were overall survival and treatment-related mortality. We used Cox proportional hazard models, logistic regression models, and Fine-Gray competing risk regression for analyses.

RESULTS

One hundred seventy-nine children (median age, 6.8 years) were included. RVs were found in 61% (41% in BAL fluid/NPAs and 20% in NPAs only). Rhinovirus was the most frequently detected RV (42%). Allo-LSs occurred in 13%. RV positivity in BAL fluid was a predictor for allo-LSs (hazard ratio, 3.8; 95% CI, 1.4-10.7; P = .01), whereas RV positivity in NPAs only was not. No other predictors were found. Grade II to IV acute graft-versus-host disease related to steroid treatment shows a trend toward a protective effect (odds ratio, 0.16; 95% CI, 0.0-1.3; P = .08). Allo-LSs significantly increased treatment-related mortality (52% ± 10% in allo-LSs and 20% ± 4% in non-allo-LSs, P = .007).

CONCLUSIONS

These results show that pre-HCT BAL fluid RV positivity was a predictor for allo-LSs. Screening for RVs before HCT might identify patients at risk for allo-LSs. This could have implications for prevention and treatment and might subsequently influence the outcomes of HCT.