Depending on where we are - or who we are with – we all tend to show different sides of our personality. People are complex, layered individuals with behaviors that we often adjust whether we are with friends, family, or at work. Our location often influences how we act. For humans, we call this phenomenon environmental psychology – or the study of how the natural world impacts our behavior. But the idea that our behavior towards others varies based on our environment isn’t limited to humans, or even animals. It can affect many other living organisms, including the microorganisms that make their home inside us. And it might have a little to do with their relationship with our own immune cells.
Location, Location, Location
Microbiologists have learned a lot about how and why microorganisms thrive so well in the various microbiomes within us. Although many microbes may find our mouth a very comfortable environment, the types of microbes inside our digestive system may not. Different environmental traits dictate who survives well – so although the oxygen levels in our mouth promote bacteria that work well with an oxygen-rich atmosphere, our gut microbes prefer limited oxygen, mostly because they have evolved and adapted to survive that harsher environment. To them, our digestive system feels like a warm, comfortable environment. To other microbes, it might be like trying to live inside a volcano (although some microbes like that, too!).
Understanding how these microbes have adapted to their various microbiomes and evolved in a symbiotic relationship with their hosts – us – has been a field of research for some time. Their role with our immune system more so, as a significant amount of our immune cells reside within our gut. Scientists have believed that our gut microbes may be interacting and communicating with our immune system, along with many other systems like digestion and hormones - but how and to what extent has still yet to be ascertained.
Though, rather recently, something very new was discovered. Something that changed how many researchers viewed the microbes living in our gut. It appeared that the gut ecosystem wasn’t as consistent as previously thought. What was originally considered a rolling, steady landscape turned out to be full of forests and hills, mountains and rivers. Our digestive system may instead be broken down into regions or “niches” with local similarities that actually change significantly from different parts of the colon. So, although they may share the same “country,” their “accents” vary based on the region of the intestines – and so do their relationships.
Mapping the Cell Atlas
These details were recently discovered through a study from the Wellcome Sanger Institute focusing on a bold and exciting new project called the Human Cell Atlas – a worldwide initiative to begin mapping every type of human cell. The goal of this initiative is to be a fundamental resource for all scientists around the globe to better understand how healthy cells work and what happens when disease occurs. When complete, this information can help many specialists in the field better understand how human intestinal cells function in digestive disorders like ulcerative colitis and colorectal cancer.
This recent study, published in Nature Immunology, was one of the contributing investigations examining this connection that discovered something novel: depending on the section of the colon, there seemed to be different populations of microbes reliant on the type of human immune cells present. These groupings had their own unique relationship, shedding light on the complex nature of our gut microbiome’s link with our immune system. These subtle changes were reflected by variations in diversity of the gut flora and changes in activity at different parts of the colon.
What does this mean?
Different immune cells in different locations of our gut are having conversations with very specific microbes. These microbes, then, appear to alter their behavior depending on the location and who they seem to be interacting with. The further up the colon, the more diverse the ecosystem, showing regions of the digestive tract appear more like urban cities with other sections mirroring more rural farmland. This study was also the first to show that some immune cells naturally move through the lymphatic system to the colon after responding to an initial immune response, suggesting the intestines might more than tolerate the microbiome – they may very well appreciate them.
Addressing the New Zones of Disease
In this study, senior scientist Dr. Sarah Teichmann believes that this may be the new landscape of disease research. By understanding the relationship dynamic between immune cells and gut microbes, based on location of the gut, scientists may be able to better hone in on the health of human cells in particular areas. For diseases that afflict the colon, it could be a critical reference point that breaks the current paradigm of treatment. It might also lead to research on how variations in site-specific gut microbes could impact gut health.
Much like the Human Genome Project, and the ongoing Human Microbiome Project – the Human Cell Atlas continues to unveil how intricate and complex our biological systems are, especially with our surroundings. Even at a microscopic level, every organism truly is a comprehensive collection of its environment, and the other organisms they associate with. Sharing complex lives and interactions, each action isn’t dependent on a single thing, but an accumulation of interactions. When it comes to our health, the lesson remains the same: no one thing can make or break us. It takes a thousand assaults – or more – to cause injury. When it comes to our diet, you never know if yesterday, today, or tomorrow might be your last day of good health. We are all different. But what we can do is begin to enact equally small changes now and change the direction of our health. Today it may be one small thing, but over time it adds up. You can start to bring about real change by shifting to a healthier diet today, one that can help you make personalized changes right for you – one that can get your gut ecosystem back on track, step by step.