The human gastrointestinal tract harbours \~40 trillion microbial cells, far outnumbering the cell number, and therefore the genetic content of its host. How this genetically diverse bacterial (collectively referred as 'microbiota') co-resident modulates host homeostasis is largely unknown. We are increasing gaining a better understanding how the microbes modulate mucosal and systemic metabolic/immune and organ systems including the kidney, heart and the brain. Therapeutic targeting of the gastrointestinal (GI) microbiota may help improve clinical outcomes in conditions as diverse as arthritis, cardiovascular disease, and cancer. In contrast to other organ systems, studies investigating the role of the microbiota in modulating clinical outcomes in renal transplantation lags behind. The aim of the study is to examine (a) how alterations in the urinary and GI microbiota and associated metabolites impact on host immunity after renal transplantation, and (b) whether such changes are correlated with post-transplant complications, such as rejection, development of de novo donor specific antibodies, metabolic complications (e.g post-transplant diabetes) and infections. Participants will be followed before and up to twelve months post-transplantation, and, longitudinal microbial data will be correlated with in-depth immune phenotyping and clinical end-points to define the impact that changes in urinary and GI microbial ecology have on kidney transplant outcomes.
Study Type
OBSERVATIONAL
Enrollment
130
Blood sample for multi-parametric flow cytometry. Blood and urine samples for identifying microbial-associated metabolite signature. Urine and faecal samples for 16S rRNA gene sequencing
Blood sample for multi-parametric flow cytometry. Blood and urine samples for identifying microbial-associated metabolite signature. Urine and faecal samples for 16S rRNA gene sequencing.
Blood sample for multi-parametric flow cytometry. Blood and urine samples for identifying microbial-associated metabolite signature. Urine and faecal samples for 16S rRNA gene sequencing.
Blood sample for multi-parametric flow cytometry. Blood and urine samples for identifying microbial-associated metabolite signature. Urine and faecal samples for 16S rRNA gene sequencing.
Blood sample for multi-parametric flow cytometry. Blood and urine samples for identifying microbial-associated metabolite signature. Urine and faecal samples for 16S rRNA gene sequencing.
Blood sample for multi-parametric flow cytometry. Blood and urine samples for identifying microbial-associated metabolite signature. Urine and faecal samples for 16S rRNA gene sequencing.
Royal Free London NHS Trust
London, United Kingdom
RECRUITINGChange in gastrointestinal and urinary microbiota composition and diversity
To understand the overall impact of transplantation on changes to the urinary and GI microbiota, the relative abundance of bacterial taxa will be evaluated using 16S rRNA gene sequencing methodologies. Alpha and Beta diversity indices will be determined from urine samples and faecal samples before and after live-donation and transplantation.
Time frame: 1 year
Correlation of change in gastrointestinal and urinary microbiota diversity with post-transplantation outcomes.
Incidence of renal graft dysfunction will be determined by the Modification of Diet in Renal Disease (MDRD)-derived estimated Glomerular Filtration Rate (eGFR) at 12 months. Graft survival time - date of transplantation to date of irreversible graft failure signified by return to dialysis (or re-transplantation, whichever is earlier) or the date of last follow-up during the period when the transplant was still functioning. In the event of death with a functioning graft, the follow-up period will be censored at the date of death.
Time frame: 1 year
Change in frequency of conventional and regulatory immune phenotypes and correlation with clinical outcome and microbial diversity changes
A panel of validated immune monitoring assays (including multi-colour flow cytometry, intracellular cytokine staining, enzyme-linked immune absorbent spot \[ELISpot\], enzyme-linked immunosorbent assay \[ELISA\] and transcriptional analysis) will be used to analyse immunological parameters in patient samples.
Time frame: 1 year
Change in microbial-associated metabolite profile and correlation with clinical outcomes and/or microbial diversity changes
A combination of 1H nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography-mass spectrometry will be used to measure the metabolic phenotype of urine and faecal samples from transplant donors and recipients (pre-operatively and up to 12 months after surgery).
Time frame: 1 year
Incidence of renal graft dysfunction as determined by the MDRD-derived estimated Glomerular Filtration Rate (eGFR).
A significant deterioration in graft dysfunction is defined as the percent of patients exhibiting an eGFR \<45 mL/min/1.73m2 at month 12 or a decrease in eGFR ≥10 mL/min/1.73m2 from month 3 to month 12 after transplantation.
Time frame: 1 year
The proportion of patients reaching a defined CKD stage at up to 5 years after transplantation.
Defined by the kidney disease outcomes quality initiative for CKD stages, with eGFR \<30 mL/min/1.73m2 considered to be advanced renal dysfunction.
Time frame: 5 years
Incidence of biopsy proven acute or chronic cellular or humoral rejection up to 5 years after transplantation as per Banff classification
Revised Banff 2017 classification of antibody-mediated rejection and T cell-mediated rejection in renal allografts.
Time frame: 5 years
Incidence of post-donation and post-transplant bacterial or viral infections up to 5 years after surgery
Infectious complications will include, but not be limited to, urinary tract infections (defined as a positive urine culture \[\>50,000 CFUs/ml\] from mid-stream urine, and categorised as asymptomatic bacteriuria \[no symptoms\], cystitis \[lower urinary tract symptoms without systemic features\] or pyelonephritis \[systemic features, graft dysfunction, CRP\>50\]), BK viraemia, cytomegalovirus (CMV) viraemia, and respiratory tract (RV) infections.
Time frame: 5 years
Patient and graft survival rates up to 5 years after transplantation.
Graft survival time will be calculated from the date of transplantation to the date of irreversible graft failure signified by return to dialysis (or re-transplantation, whichever is earlier) or the date of last follow-up during the period when the transplant was still functioning. In the event of death with a functioning graft, the follow-up period will be censored at the date of death.
Time frame: 5 years
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