Longitudinal Lower Airway Microbial Signatures of Acute Cellular Rejection in Lung Transplantation.

Rationale: Acute cellular rejection (ACR) after lung transplant is a leading risk factor for chronic lung allograft dysfunction. Prior studies have demonstrated dynamic microbial changes occurring within the allograft and gut that influence local adaptive and innate immune responses. However, the lung microbiome's overall impact on ACR risk remains poorly understood. Objectives: To evaluate whether temporal changes in microbial signatures were associated with the development of ACR. Methods: We performed cross-sectional and longitudinal analyses (joint modeling of longitudinal and time-to-event data and trajectory comparisons) of 16S rRNA gene sequencing results derived from lung transplant recipient lower airway samples collected at multiple time points. Measurements and Main Results: Among 103 lung transplant recipients, 25 (24.3%) developed ACR. In comparing samples acquired 1 month after transplant, subjects who never developed ACR demonstrated lower airway enrichment with several oral commensals (e.g., Prevotella and Veillonella spp.) than those with current or future (beyond 1 mo) ACR. However, a subgroup analysis of those who developed ACR beyond 1 month revealed delayed enrichment with oral commensals occurring at the time of ACR diagnosis compared with baseline, when enrichment with more traditionally pathogenic taxa was present. In longitudinal models, dynamic changes in α-diversity (characterized by an initial decrease and a subsequent increase) and in the taxonomic trajectories of numerous oral commensals were more commonly observed in subjects with ACR. Conclusions: Dynamic changes in the lower airway microbiota are associated with the development of ACR, supporting its potential role as a useful biomarker or in ACR pathogenesis.

Lung Transplantation for Pulmonary Fibrosis Associated With Hermansky-Pudlak Syndrome. A Single-center Experience.

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by oculocutaneous albinism, platelet storage defect with resultant bleeding diathesis, and pulmonary fibrosis. The bleeding diathesis associated with HPS had long been considered a contraindication to lung transplantation; consequently, few reports of successful lung transplantation for HPS exist. Methods: In the largest case series on lung transplant for HPS, we describe the characteristics of 11 lung transplant candidates with HPS-related pulmonary fibrosis, and the management and outcomes of 7 patients who underwent lung transplantation. Results: Of the 7 patients transplanted, 30-d survival was 85.7% (6/7). Six patients had at least 2 y of follow-up available with a 1-y survival of 83.3% and a 2-y survival of 83.3% (5/6). The median age at referral was 48 y (range 29-62 y). Eight patients (72.7%) were of Puerto Rican ancestry with confirmed type 1 HPS mutation. Six out of 7 patients received prophylaxis for bleeding diathesis, with a majority receiving desmopressin; 1 patient was administered aminocaproic acid infusion, and another received 2 units of platelets before surgery. Estimated blood loss and the amount of intraoperative blood product administered was highly variable with or without prophylaxis. Median blood loss was 400 mL (range 125-750) and estimated blood products administered was 700 mL (range 490-4043). Conclusions: HPS should not be considered a contraindication for lung transplantation. Although patients with HPS seem to have an increased risk of massive hemorrhage, the risk is unpredictable. Transplant teams should prepare a preoperative plan in consultation with hematology and consider the use of prophylactic platelet transfusion and desmopressin.