The bacteria living in and on our bodies don鈥檛 always work in our favour 鈥� some seem to provoke the autoimmune disease lupus. The finding suggests that targeted antibiotics might one day help treat the disorder.
Disturbances in the body鈥檚 microbiome have already been linked to plenty of disorders, including autoimmune diseases, which occur when a person鈥檚 immune system starts to attack their own body. In people with lupus, this kind of attack often causes skin rashes, but can also damage other organs, such as the lungs, heart, brain and kidneys.
鈥淲e don鈥檛 really know what causes lupus, but it is thought to be a combination of genetics, environment and hormones,鈥� says at the Yale School of Medicine.
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Kriegel and his colleagues suspected the microbiome might play a role. Past research has found that, in the earliest stages of lupus, the immune system starts targeting a protein in the body called Ro60, which normally protects body tissues. Some strains of soil bacteria are known to make proteins very similar to Ro60.
Microbial trigger
When Kriegel鈥檚 team looked at bacteria from the skin, nose and guts of people with and without lupus, they found that the body鈥檚 own microbiome also makes proteins similar to Ro60. In people with lupus, these proteins seemed to be triggering an immune response 鈥� but there was no such reaction in healthy people.
In another experiment, the team took one of the types of bacteria that makes Ro60-like proteins and gave it to mice lacking their own microbiome. The animals showed a similar immune response, and started to show the early signs of kidney failure that some people with lupus get.
Kriegel thinks that people with lupus might have a genetic vulnerability to the disorder, but it is their microbiomes that trigger and sustain the disorder itself. The finding could aid the development of new lupus treatments. 鈥淕enes are fixed, but microbes are really malleable 鈥� we can remove them or replace them,鈥� he says.
But people with lupus shouldn鈥檛 start taking antibiotics yet. 鈥淭he current antibiotics we have are like an atomic bomb 鈥� they wipe out good as well as bad bacteria,鈥� says Kriegel. Instead, he hopes to develop treatments that specifically target the bacteria that make proteins like Ro60.
Read more: Autoimmune diseases may be side-effect of a strong immune system
