In a new study, researchers have found that the gut microbiome appears to play a key role in how well the body accepts a transplanted heart. The scientists found a causal relationship between the presence of certain microbes and transplant outcome.
The results have the potential to significantly change how researchers and doctors deal with the problem of rejection and transplantation. This is the first study to identify specific bacterial species that can affect whether a heart transplant is rejected, and how quickly. The new study was published in the Journal of Clinical Investigation Insight.
One of the study's two lead authors said the research had the potential to transform transplantation. "From our previous work we suspected that the microbiome might have an effect on how transplanted organs are accepted," says the author. "This work clearly shows that there is a connection between these gut microbes and the body's response to the new organ. It's very exciting."
The link between the transplanted heart and the microbiome is the immune system. Many researchers have noted that the microbiome plays a key role in the immune system, either activating it or turning it down, depending on the bacterial species. Certain bacteria in the microbiome can trigger pro- or anti-inflammatory signals, and that these signals can in turn affect how the immune system responds to the transplanted organ.
Organ rejection remains an urgent problem in transplantation. Despite intense research, over the past 20 years researchers and doctors have not been able to improve the long-term organ rejection rate - the rejection of organs that occurs between five and eight years after transplantation.
In an animal model, the scientists showed that by adjusting the microbiome, they could improve the outcome of the heart transplant. They identified specific species that seem to have a beneficial or harmful effect on the transplant. For example, particular strains of bifidobacterium seem to have an anti-inflammatory, beneficial effect on transplant outcomes. They suspect that this process may be similar for other organs, such as kidneys. The next step, they say, will be to focus on the mechanisms behind these effects. With a better understanding of the molecular pathways, it may be possible to mimic the effect with drugs.
Certain gut microbes may delay or prevent organ rejection
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