Dealing with diversity – immune responses to fungi

Fungi are everywhere. They’re present in the air, in our food, some even live inside our bodies. But most of us rarely think about diseases caused by fungi. This is because our defences do a really good job in keeping them in check.

However for millions of people whose immune system are defective fungi can cause serious infections that are hard to treat and can be life threatening.

A group of cells called phagocytes play a key role in keeping us safe from fungi. They normally patrol our body so when there’s a breach they are the first to respond. Their function is to seek eat and destroy microbial intruders.

But no all fungi are alike. My Ph.D. project aims to understand how phagocytes tackle such different targets. So far I have found there are huge differences in the rate at which various different fungi are engulfed by phagocytes.

The speed of these processes depends on the chemical composition of the fungi, whether they are alive or dead, and whether they are coated with human proteins that help to mark them as intruders.

Understanding the basic biology behind these processes is the first step towards developing new treatment strategies.

Maria Fernanda Alonso works in Professor Neil Gow's lab at the University of Aberdeen.

Human lung cells: a defence against fungal spores

Every day we inhale hundreds of fungal spores but these in healthy individuals are efficiently eliminated by specialist immune cells called phagocytes which engulf and kill them. However, some human illnesses interfere with this defence mechanism, increasing susceptibility to fungal diseases.

A specialist lung tissue called the epithelium is the first line of contact between the inhaled spores and us, the host. We are working to understand how the lung epithelium interacts with the spores of a common mould called Aspergillus fumigatus.

We have generated fluorescent Aspergillus and combined this with fungal and host specific dyes to directly visulaise this interaction. We have discovered that epithelial cells ingest fungal spores and kill them.

This might provide a critical defence mechanism which is acting while we breathe, and before even phagocytes arrive at the site of the infection.

We are now trying to work out how epithelial cells grab and ingest fungal spores, by using fluorescent fungal mutants and targeted elimination of host proteins.

Once we understand this process in detail we can design new therapies to assist a quicker elimination of the dangerous fungal spores we all inhale on a daily basis.

Dr Margherita Bertuzzi works in Dr Elaine Bignell's lab at the University of Manchester