Project description:BACKGROUND: Hematopoietic stem cell transplantation is a curative procedure for a variety of conditions. Despite major advances, a plethora of adverse clinical outcomes can develop post-transplantation including graft-versus-host disease and infections, which remain the major causes of morbidity and mortality. There is increasing evidence that the gastrointestinal microbiota is associated with clinical outcomes post-hematopoietic stem cell transplantation. Herein, we investigated the longitudinal dynamics of the gut microbiota and metabolome and potential associations to clinical outcomes in pediatric hematopoietic stem cell transplantation at a single centre.RESULTS: On admission (baseline), the majority of patients presented with a different gut microbial composition in comparison to healthy control children with a significantly lower alpha diversity. A further, marked decrease in alpha diversity was observed immediately post-transplantation and in most microbial diversity, and composition did not return to baseline status while hospitalized. Longitudinal trajectories identified continuous fluctuations in microbial composition, with the dominance of a single taxon in a significant proportion of patients. Using pam clustering, three clusters were observed in the dataset. Cluster 1 was common pre-transplantation, characterized by a higher abundance of Clostridium XIVa, Bacteroides and Lachnospiraceae; cluster 2 and cluster 3 were more common post-transplantation with higher abundance of Streptococcus and Staphylococcus in the former whilst Enterococcus, Enterobacteriaceae and Escherichia predominated in the latter. Cluster 3 was also associated with a higher risk of viraemia. Likewise, further multivariate analysis reveals Enterobacteriaceae, viraemia, use of total parenteral nutrition and various antimicrobials contributing towards cluster 3, Streptococcaceae, Staphylococcaceae, Neisseriaceae, vancomycin and metronidazole contributing towards cluster 2. Lachnospiraceae, Ruminococcaceae, Bifidobacteriaceae and not being on total parenteral nutrition contributed to cluster 1. Untargeted metabolomic analyses revealed changes that paralleled fluctuations in microbiota composition; importantly, low fecal butyrate was associated with higher risk of viraemia.CONCLUSIONS: These findings highlight the frequent shifts and dominations in the gut microbiota of pediatric patients undergoing hematopoietic stem cell transplantation. The study reveals associations between the fecal microbiota, metabolome and viraemia. To identify and explore the potential of microbial biomarkers that may predict risk of complications post-HSCT, larger multi-centre studies investigating longitudinal microbial profiling in pediatric hematopoietic stem cell transplantation are warranted.

Project description:BackgroundHaematopoietic stem cell transplantation is a curative procedure for a variety of conditions. Despite major advances, a plethora of adverse clinical outcomes can develop post-transplantation including graft-versus-host disease and infections, which remain the major causes of morbidity and mortality. There is increasing evidence that the gastrointestinal microbiota is associated with clinical outcomes post-haematopoietic stem cell transplantation. Herein, we investigated the longitudinal dynamics of the gut microbiota and metabolome and potential associations to clinical outcomes in paediatric haematopoietic stem cell transplantation at a single centre.ResultsOn admission (baseline), the majority of patients presented with a different gut microbial composition in comparison with healthy control children with a significantly lower alpha diversity. A further, marked decrease in alpha diversity was observed immediately post-transplantation and in most microbial diversity, and composition did not return to baseline status whilst hospitalised. Longitudinal trajectories identified continuous fluctuations in microbial composition, with the dominance of a single taxon in a significant proportion of patients. Using pam clustering, three clusters were observed in the dataset. Cluster 1 was common pre-transplantation, characterised by a higher abundance of Clostridium XIVa, Bacteroides and Lachnospiraceae; cluster 2 and cluster 3 were more common post-transplantation with a higher abundance of Streptococcus and Staphylococcus in the former whilst Enterococcus, Enterobacteriaceae and Escherichia predominated in the latter. Cluster 3 was also associated with a higher risk of viraemia. Likewise, further multivariate analysis reveals Enterobacteriaceae, viraemia, use of total parenteral nutrition and various antimicrobials contributing towards cluster 3, Streptococcaceae, Staphylococcaceae, Neisseriaceae, vancomycin and metronidazole contributing towards cluster 2. Lachnospiraceae, Ruminococcaceae, Bifidobacteriaceae and not being on total parenteral nutrition contributed to cluster 1. Untargeted metabolomic analyses revealed changes that paralleled fluctuations in microbiota composition; importantly, low faecal butyrate was associated with a higher risk of viraemia.ConclusionsThese findings highlight the frequent shifts and dominations in the gut microbiota of paediatric patients undergoing haematopoietic stem cell transplantation. The study reveals associations between the faecal microbiota, metabolome and viraemia. To identify and explore the potential of microbial biomarkers that may predict the risk of complications post-HSCT, larger multi-centre studies investigating the longitudinal microbial profiling in paediatric haematopoietic stem cell transplantation are warranted. Video abstract.

Project description:The ability to identify a robust means for both pediatric and adult liver transplant recipients for minimization and weaning of immunosuppression is greatly needed. We analyzed 298 samples from pediatric (n=83) and published adult (n=57) liver transplant recipients, and the public available cell or tissue specific samples (n=158). Biomarkers were first identified from the integration of the cross-platform analysis of Stanford pediatric and adult studies and validated in independent samples from UCLA on microarray. Furthermore, Q-PCR was performed for targets validation and delivers a robust diagnostic assay of predicting potential liver tolerance after liver transplantation. Thirteen unique genes were identified (FDR<5%) using nearest shrunken centroid classification methods as a minimum gene set to cross-validate and predict Stanford pediatric tolerance samples with 1misclassification, 5 misclassification for adult samples, and 100% sensitivity and 83% specificity for an independent UCLA pediatric samples in microarray platform. These subset of tolerant specific genes are highly expressed CD56+ natural killer cells (p=0.03). Furthermore, the subset can be narrowed down to 3 key genes with combined ROC=0.988 for the liver tolerance prediction from Q-PCR verification and 64% MIS and STA were predicted as tolerance with the >90% prediction probability. Specific peripheral transcriptional programs can be identified in operational tolerance in pediatric recipients of liver allografts, distinct from those previously identified in adult operationally tolerant liver recipients, and may provide a means to non-invasively monitor patients in a serial manner for immunosuppression minimization. These genes are highly expressed in specific peripheral blood lymphocyte subsets, and their coordinated may support the maintenance of operational tolerance in children, following liver transplantation. Two centers data was included, which are 41 samples from Stanford as the training set and 44 samples from UCLA as the test set. 26 samples from Stanford and 15 samples from UCLA were used in microarray Agilent whole human genome microarray

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Linking gastrointestinal microbiota and metabolome dynamics to clinical outcomes in pediatric hematopoietic stem cell transplantation

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