Abnormal gut microbiome is associated with increased mortality risk after transplantation 

The gut microbiome of patients who have received a kidney or liver transplantation is less diverse compared to the general population. This change in the gut microbiome leads to poorer health and a higher mortality risk for these groups of patients. The composition of the gut microbiome is also very different from the gut microbiome of the general population.

This has been shown in a large, long-term study by researchers of the University Medical Center Groningen. In this study they used health data from large biobanks TransplantLines and Lifelines. The results were published today in Science Translational Medicine (read here) and offer prospects for the development of potential treatments that could protect the gut microbiome of transplant patients and thus improve their quality of life and overall health.  

Role of the gut microbiome in organ transplantation still unknown  

Organ transplantation is a life-saving treatment for many patients with end-stage organ disease. Thanks to progressive insights and techniques, the survival rate after transplantation is still increasing. As a result, more attention is paid to the quality of life of patients after transplantation because this can be improved. However, survival rates of transplant patients still vary widely due to rejection and infection after organ transplantation. It is known that the gut microbiome has an important relationship with the immune system, but until now little was known about the role of the gut microbiome in organ transplants recipients and the relationship with immunosuppressive drugs. Thanks to a cooperation between the Transplantation Center and the microbiome researchers of the UMCG, for the first time more is known about the influence of the microbiome on two groups of transplant patients.  

Long-term research in kidney and liver transplant patients  

The researchers analyzed a total of 1370 stool samples from 415 liver transplant recipients and 672 kidney transplant recipients. They did the same with 1183 samples from participants from the general population from LifeLines who were similar in age, sex and weight to the transplant patients. In addition, they followed 78 kidney transplant recipients before transplantation until 24 months after transplantation. They obtained these data from the TransplantLines biobank, in which data from all transplant patients in the UMCG is collected and used for research to improve the quality of life of these patients.  

Difference in composition of the gut microbiome and after transplantation  

The study shows that the composition of the gut microbiome of both kidney and liver transplant patients is clearly different after transplantation than before. The composition also differs from that of the general population, which the researchers could compare thanks to Lifelines data. There are more bacteria present that have previously been observed in different diseases. These changes were found to persist for up to 20 years after transplantation.    

Difference in composition of the gut microbiome partly explained by immunosuppressive drugs  

After transplantation, the composition of the patient’s gut microbiome appears to be less diverse. The study also shows that transplant patients have an unhealthier gut microbiome and that important aspects of their microbial metabolism function less well. All these factors can partly be explained by the use of the immunosuppressive drugs that all transplant patients must take to prevent rejection of the donor organ. Because of this they also need antibiotics more frequently due to the higher infection risk which is also known to impact the gut microbiome.   

Difference in gut microbiome associated with mortality risk   

Finally, the study shows that the less diverse gut microbiome after transplantation is associated with poorer health and a higher risk of death for these groups of patients. The researchers concluded that the difference in microbiome between transplant patients and healthy people is associated with a mortality risk. The more the gut microbiome of transplant patients differs from the gut microbiome of individuals from the general population, the higher the mortality risk.  

Potential gut microbiome-targeted interventions in transplant patients  

According to the researchers, this study is a first step towards potential gut microbiome-targeted interventions in transplant patients. These interventions should lead to a positive change in the composition of the gut microbiome in liver or kidney transplant recipients or protect the gut microbiome against the drugs that they must use. This is expected to potentially improve their overall health and quality of life. In addition, this study contributes to understanding the relationship between the gut microbiome and the immune system.   

First publication from important collaboration  

This publication in Science Translational Medicine is the first to result from the collaboration between the TransplantLines Biobank and the Groningen Microbiome Hub of the UMCG. They are also currently conducting research into the importance of the microbiome on the health of other groups of transplant patients.   

This research was made possible by a grant from the NWO/TTW/DSM partnership program Animal Nutrition and Health.