Project description:Hematopoietic stem cell transplantation (HSCT) induces significant alterations in the gut microbiome and metabolome, which influence transplant-related complications and surviv-al. This study longitudinally analyzed gut microbiota and metabolites at pre- (T1), peri- (T2), and post-transplant (T3) stages to identify key determinants of clinical outcomes. Lower microbiome diversity at T1 and T3 correlated with graft-versus-host disease (GVHD), progressive disease (PD), and reduced overall survival (OS). Short-chain fatty acids (SCFAs), particularly acetate, declined over time, with reductions at T2-T1 linked to GVHD, diarrhea, PD, and lower OS. Specific perspective metabolites (SPMs) such as elevated uric acid at T2 were associated with GVHD, while reduced 1-phenylethylamine correlated with diarrhea. Patients with enriched beneficial taxa (e.g., Lachnospiraceae, Ruminococcaceae) exhibited improved OS. These findings highlight the gut microbiome-metabolome axis as a predictive marker for HSCT outcomes. Identifying microbial and metabolic signatures may provide novel diagnostic and therapeutic targets for mitigating HSCT-related complications, enhancing patient prognosis.
Project description:Transplant-associated thrombotic microangiopathy (TA-TMA) is a life-threatening complication of allogeneic hematopoietic cell transplantation (HCT). We hypothesized that pre-transplant genetic susceptibility is evident in adult TA-TMA patients at the level of TMA-associated variants and further investigated the association of genetic variants with clinical outcomes. We studied 30 patients with TA-TMA at a median of 73 (9-540) post-transplant days, donors of 18/30 patients and 30 control non-TMA HCT recipients, without significant differences in transplant characteristics. Genomic DNA from pre-transplant peripheral blood was analyzed by targeted next generation sequencing for complement regulatory genes and ADAMTS13. Donors presented significantly lower frequency of rare variants (p=0.049) and variants in exonic/splicing/UTR regions (p=0.025), compared to TA-TMA patients. Controls also showed a significantly lower frequency of rare variants in ADAMTS13 (p=0.001), CD46 (p=0.002), CFH (p=0.010) and CFI (p=0.031). Pathogenic variants were found in ADAMTS13, CFH, CFI and CFB, while homozygous pathogenic variants in ADAMTS13 and CFB were evident in only 4 TA-TMA patients (p=0.038). Patients refractory to conventional treatment (70%) were significantly (p=0.045) enriched for variants in exonic/splicing/UTR regions compared to responders. Nineteen of 30 patients (63%) succumbed to transplant-related mortality, which was also associated with significantly (p=0.012) increased frequency of variants in exonic/splicing/UTR regions. In conclusion, increased incidence of pathogenic, rare and variants in exonic/splicing/UTR regions of TA-TMA patients suggests genetic susceptibility not evident in controls or donors. Notably, variants in exonic/splicing/UTR regions were associated with poor response and survival. Therefore, pre-transplant genomic screening may be useful to intensify monitoring and early intervention in high-risk patients.
Project description:The purpose of this study is to determine the clinical benefit and characterize the safety profile of tabelecleucel for the treatment of Epstein-Barr virus-associated post-transplant lymphoproliferative disease (EBV+ PTLD) in the setting of (1) solid organ transplant (SOT) after failure of rituximab and rituximab plus chemotherapy or (2) allogeneic hematopoietic cell transplant (HCT) after failure of rituximab.
Project description:<p><strong>BACKGROUND:</strong> 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.</p><p><strong>RESULTS:</strong> 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 <em>Clostridium XIVa</em>, <em>Bacteroides</em> and <em>Lachnospiraceae</em>; cluster 2 and cluster 3 were more common post-transplantation with higher abundance of <em>Streptococcus</em> and <em>Staphylococcus</em> in the former whilst <em>Enterococcus</em>, <em>Enterobacteriaceae</em> and <em>Escherichia</em> predominated in the latter. Cluster 3 was also associated with a higher risk of viraemia. Likewise, further multivariate analysis reveals <em>Enterobacteriaceae</em>, viraemia, use of total parenteral nutrition and various antimicrobials contributing towards cluster 3, <em>Streptococcaceae</em>, <em>Staphylococcaceae</em>, <em>Neisseriaceae</em>, vancomycin and metronidazole contributing towards cluster 2. <em>Lachnospiraceae</em>, <em>Ruminococcaceae</em>, <em>Bifidobacteriaceae</em> 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.</p><p><strong>CONCLUSIONS:</strong> 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.</p>