Deep Ocean Reveals Surprising Discovery about Immunity

In the largest and deepest marine protected area in the world, a team of ocean experts peered over 3,000 meters below the surface to find new types of microbial organisms that people would have never encountered before. These microbes-types of bacteria-could now open up doors to new ways of understanding how the immune system responds to completely foreign invaders.

A collaborative study between the Rotjan Marine Ecology Lab at Boston University, the Kagan Lab at the Harvard Medical School, Boston Children’s Hospital, the government of Kiribati, and others has found that there are some bacteria so foreign to humans that our immune cells can’t register that they exist, overriding the long-held belief of universal immunity, or that our cells can recognize any bacteria they interact with. Rather, the study found, some bacteria are solely defined by their local habitat or surroundings. Their findings were published Friday, March 12, in Science Immunology.

“Our team discovered and cultured novel microbes that are completely immunosilent to human immune systems,” says Randi Rotjan, meaning that the bacteria triggered no reaction or response from our innate immune system. Rotjan, a BU College of Arts & Sciences research assistant professor of biology and a co-lead author of the paper, says this discovery was completely unexpected.

Anna Gauthier and Aranteiti Tekiau talk next to the deep sea submersible ROV SuBastian on the deck of the R/V Falkor sailing in the Phoenix Islands Protected Area.
Anna Gauthier (lead author) and Aranteiti Tekiau (Kiribati) enjoy the sun and waves on the deck of the R/V Falkor, examining ROV SuBastian close up before it plunges to the depths. Photo by Schmidt Ocean Institute

The research is the culmination of five years of study, across 2,000 nautical miles of central Pacific Ocean waters, with thousands of genes sequenced, and with much of the work at sea being done on a floating laboratory.

Rotjan, whose research focuses on live coral reefs, says that the interdisciplinary nature of their team was also a major strength-with co-lead authors Anna Gauthier, a visiting student at BU in the Rotjan Lab whose research focuses on the immune systems of marine organisms, and Jonathan Kagan, who studies the ways cells interact with each other and with the microbes they encounter. In addition to being faculty in BU’s biology department, Rotjan is co-chief scientist of the Phoenix Islands Protected Area, an expanse of marine and terrestrial habitats in Kiribati-and the largest and deepest UNESCO World Heritage Site-where the work took place. The Brink caught up with Rotjan, and this Q&A, which also reflects the findings and research of Gauthier and Kagan, has been condensed and edited.

Detail photo of orange and green deep sea hard corals in the Phoenix Islands Protected Area
Hard corals in the deep sea are biodiversity multipliers, hosting a diversity of seastars, crinoids, urchins, and other taxa along the vertical cliffs of an ancient volcano in the equatorial Pacific waters of the Phoenix Islands Protected Area. Photo by Schmidt Ocean Institute
The arm of ROV SuBastian about to take a sample of bamboo coral
ROV SuBastian setting up to sample a bamboo coral, 2000 m below the surface, with its robotic arm. Photo by Schmidt Ocean Institute
ROV pilot Adam Whetmore flies the submersible SuBastian in front of a wall of screens in a cockpit onboard the R/V Falkor .
ROV pilot Adam Whetmore flies the submersible SuBastian onboard the R/V Falkor to collect a coral sample with its robotic arm, at the direction of the science team. Photo by Schmidt Ocean Institute
View of ROV submersible SuBastian on the deck of R/V Falkor at sunset, Phoenix Islands Protected Area
Anna Gauthier (lead author) and Aranteiti Tekiau (Kiribati) enjoy the sun and waves on the deck of the R/V Falkor, examining ROV SuBastian close up before it plunges to the depths. Photo by Schmidt Ocean Institute

This research was supported by the National Institutes of Health, National Oceanic and Atmospheric Administration, and the International Centre for Cancer Vaccine Science project of the International Research Agendas program of the Foundation for Polish Science, co-financed by the European Union under the European Regional Development Fund.

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