In recent years,
the microbiota -- the community of bacteria and other microorganisms that live
on and in the human body -- has captured the attention of scientists and the
public, in part because it's become easier to study. It has been linked to many
aspects of human health.
A
multidisciplinary team from Memorial Sloan Kettering has shown for the first
time that the gut microbiota directly shapes the makeup of the human immune
system. Specifically, their research demonstrated that the concentration of
different types of immune cells in the blood changed in relation to the
presence of different bacterial strains in the gut. The results of their study,
which used more than ten years of data collected from more than 2,000 patients.
The data that were
used
in the study came from people receiving allogeneic stem cell and bone marrow
transplants (BMTs). After strong chemotherapy or radiation therapy is used to
destroy cancerous blood cells, the patient's blood-forming system is replaced
with stem cells from a donor. For the first few weeks until the donor's blood
cells -- including the white blood cells that make up the immune system -- have
established themselves, the patients are extremely vulnerable to infections. To
protect them during this time, patients are given antibiotics.
But many of these
antibiotics have the unwanted side effect of destroying healthy microbiota that
live in the gut, allowing dangerous strains to take over. When the patient's
immune system has reconstituted, the antibiotics are discontinued, and the gut
microbiota slowly starts to grow back.
For more than ten
years, members of MSK's BMT service have regularly collected and analyzed blood
and fecal samples from patients throughout the BMT process. The bacterial DNA
were processed by the staff at MSK's Lucille Castori Center for Microbes,
Inflammation, and Cancer, which played a key role in creating the massive
microbiota dataset.
This wider effort
has been led by Marcel van den Brink, Head of the Division of Hematologic
Malignancies, and a team of infectious disease specialists, BMT doctors, and
scientists.
Previous research
using samples collected from this work has looked at how the gut microbiota
affects patients' health during the BMT process. A study published in February
2020 reported that having a greater diversity of species in the intestinal
microbiota is associated with a lower risk of death after a BMT. It also found
that having a lower diversity of microbiota before transplant resulted in a
higher incidence of graft-versus-host disease, a potentially fatal complication
in which the donor immune cells attack healthy tissue.
See:
Jonas Schluter,
Jonathan U. Peled, Bradford P. Taylor, Kate A. Markey, Melody Smith, Ying Taur,
Rene Niehus, Anna Staffas, Anqi Dai, Emily Fontana, Luigi A. Amoretti, Roberta
J. Wright, Sejal Morjaria, Maly Fenelus, Melissa S. Pessin, Nelson J. Chao,
Meagan Lew, Lauren Bohannon, Amy Bush, Anthony D. Sung, Tobias M. Hohl,
Miguel-Angel Perales, Marcel R. M. van den Brink, Joao B. Xavier. The gut
microbiota is associated with immune cell dynamics in humans. Nature, 2020;
DOI: 10.1038/s41586-020-2971-8
Posted by Dr. Tim Sandle,
Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)
