Circulating microbiota in patients with acute graft-versus- host disease (GVHD) following hematopoietic stem cell transplantation

HASSAN, ROCIO; REZENDE MAYARA; EMMEL VANESSA; ABDELHAY ELIANA; MURILLO JAVIER; TAPIA ELIZABETH; GAMA BIANCA; KRSTICEVIC, FLAVIA

Sao Paublo

Congreso; XXI Congress of SBTMO; 2017

Acute GVHD involves immune reactions betweenallogenic lymphocytes and host tissues. Translocated gut bacteriahave been proposed as GVHD triggers but no role for the circulatingmicrobiota in GVHD has been proposed by now. The goal of this studyis to provide a plasma metagenome characterization of patientsdiagnosed with GVHD. Experimentaldesign: 12 patients with acute leukemia(8 AML and 4 ALL) submitted to matched allo-HSCT were included. Theindex patient was identified as having grade III/IV aGVHD and thecontrol was paired by disease, age and whenever possible, sex.Free-circulating DNA from samples at D-8 and a date close to aGVHDdiagnosis (or equivalent in non-GVHD patients) were sequenced with anIllumina HiSeq2500. Multiplexed libraries were constructed usingNexteraXT kits. Bioinformatic pipelines were designed to classifypaired end reads; unmapped reads were subtracted from the human 1000genomes and analyzed for potential viral and bacterial hits againstNCBI databases, using the Centrifuge program. Results:Frequency of non-human sequences represented 6%-13%. The viralcomponent was dominated by bacterial phages and remained stable. Thebacterial microbiota was dominated by Cutibacteriumacnes, a member of the skin microbiota.Plasma bacterial microbiota was composed mainly by members of theskin, the oral and gut microbiota. Alpha-Diversity as measured byH-Shannon, inverse-Simpson and Fisher.alpha indexes decreased fromD-8 to the time of GVHD in 4 patients, as compared with the non-DECHpts., in which increased. In two cases, in which GVHD was diagnosedearly (D+14), the diversity indexes did not follow this trend. Inthese cases, an increase in diversity of Proteobacteria(Enterobacteriaceae) and Actinobacteria (Propionibacteriaceae) anddecrease of Firmicutes was observed. Pathogens were readily detected.In one case of empirically treatedfebrile neutropenia of obscure cause, A.baumannii,Klebsiellapneumoniae,as well as S.epidermidis wereidentified. Species of Mycobacteriumleprae,as well as the M.tuberculosisand non-tuberculosis complexes were identified. Leishmaniainfection was detected in one case. Conclusion:The increasing access to high-throughput technology may change theway to approach infections, as well as immune complications in theimmunocompromised patient.