The skin-gut axis – when the skin and gut talk to each other
There’s a lot of chatter going on between your skin and your gut. They both play an important role as barriers to bacteria, so keeping in touch is paramount to keeping you in good health.
Your skin and gut communicate along what is called the skin-gut axis. Cracking the code of communication between them is Dr Katherine Woods, a member of the translational immunology team at the Malaghan Institute of Medical Research.
By studying this skin-gut axis from an immunological perspective, Dr Woods hopes to find opportunities to intervene in key conversations to prevent the spread of allergies and intolerances. To do this, she’s looking at genes, the microbiome and the immune system.
Genetic makeup plays a big role in allergies. One key gene, filaggrin, is expressed in the skin and helps protect your body from the outside world.
“Filaggrin is vital for barrier function – keeping the outside elements out,” says Dr Woods. “A benchmark 2018 study published in the Journal of Allergy Clinical Immunology showed that an organism that lacks filaggrin develops a reaction to an allergen delivered on the skin.
“Afterwards, when that same allergen is delivered orally, the organism now has a severe (fatal) allergic reaction to it. Filaggrin is one example of the powerful connection between the skin and gut following a breach in barriers.”
In terms of the microbiome, Dr Woods explains that, for her research, it’s playing a supporting role rather than the primary one it usually takes in gut research.
“What I’m first focusing on is the immune cells – the human cells – in the gut and what happens to them when we induce different types of allergies.
“Microbiomes vary wildly between people based on our diet, our genetics, even how we were born. Because of this, it’s hard to find something that works for everyone.
“Conversely, we all have the same immune cells and so may be much more similar in immune responses. Because of that similarity, any advances in this field may apply to larger populations.”
Building on her immunology focus, Dr Woods is taking a closer look at TSLP, a molecule that influences immune cells, to find out how much influence it has on the immune system in the gut and how it may affect allergies.
“TSLP is an immunologic ‘alarmin’ that is secreted by many cells, including skin cells, signalling a barrier breach. This usually coincides with exposure to an allergen. TSLP then spreads around the body, including places like the gut where it goes on to influence immune cells in the area.”
“We’re looking at TSLP in detail to see whether it plays a role in the allergic march and cross-talk between different organs.”
In the allergic march, babies who present with eczema are much more likely to later develop more serious allergies such as food allergy or asthma.
“If you think about how a baby eats – jabbing food all around its mouth – there’s often a rash there. The baby is getting its first exposure to a potential allergen through the skin before it even eats anything. This has the potential to be a big component in things like the allergic march.
“The golden target with our research is that we might be able to manipulate the skin-gut axis in a way to slow down or halt the allergic march altogether.”