Researchers are also exploring the role of the microbiome — the trillions of bacteria, fungi, and viruses that live on and in the human body. Imbalances in this delicate microorganism ecosystem can contribute to numerous diseases and disorders affecting everything from the gut to the brain to the skin. Scientists interested in the microbiome have found that people with eczema have unusually high amounts of harmful bacteria on their skin and lower than normal levels of “good” bacteria. This discovery led to an idea: Could adding beneficial bacteria to the skin through topical medications correct this imbalance and improve eczema symptoms? Dr. Myles and his team focused on Roseomonas mucosa, a type of bacteria found in healthy skin, using it to treat 10 adults and 5 children with atopic dermatitis. The adults applied a Roseomonas mucosa spray to the insides of their forearms two times a week for 6 weeks; for the children, affected skin areas were sprayed twice weekly for 12 weeks, then every other day for an additional 4 weeks. All the subjects in the study were allowed to continue their regular eczema treatments as needed. The researchers found that 6 of the 10 adults and 4 of the 5 children experienced more than a 50 percent improvement in their eczema, with some subjects reporting that they needed less steroid cream than usual to manage their symptoms. “In our research, [the therapy] worked better in younger individuals, which makes sense. If you are an adult and have had 40 years of skin inflammation, that’s probably going to be harder to reverse compared to, say, a 3-year-old,” says Myles. This bacterial therapy is extremely safe, Myles notes. Before trying the spray on human subjects, he says, “We concentrated it down and injected a huge amount into a mouse — more than what a human would use if they used it every day for a year — and it didn’t cause harm,” he says. There were also no adverse events during the human trial, he adds.
Good Bacteria Might Help Restore the Skin’s Natural Oils
“If you examine the skin of someone with eczema when everything is going great for them — when they still may need medicine, but their disease is well controlled — the main thing that is still abnormal compared to healthy people is the lipid profile of their skin,” says Myles. In the context of eczema, the term “lipid” refers to the skin’s natural oils (fats), Myles explains. “Your skin needs specific kinds of the right oils in the right amounts to have it function the way it’s supposed to,” he says. According to Myles, there’s no evidence that for people with eczema, the skin itself is unable to produce the right lipids. “That led us to suspect that maybe it’s the bacteria on their skin that are failing to make the correct lipids,” he says.
A Bacterial Battle on the Skin: Good Versus Bad
More recently, a team of researchers from the University of California San Diego School of Medicine and the National Jewish Health Center in Denver began looking at a similar concept: applying bacteria to the skin to treat eczema — but a different type of bacteria and a different mechanism of action. Instead of using a strain of bacteria to help change the lipid profile of the skin, this therapy works by introducing a “good” bacteria, known as Staphylococcus hominis, to kill a “bad” bacteria, Staphylococcus aureus. Roughly half of people with eczema have a significant problem with bacterial infections, particularly from S. aureus, according to Donald Leung, MD, PhD, one of the researchers and an allergist and immunologist at National Jewish Health. “This bacteria is a problem because it produces proteins and enzymes that trigger eczema and can make it worse,” he says. “The inflammation in the skin of a person with eczema causes the skin to be much ‘stickier’ for the Staph aureus that may be in the environment, so it binds to the skin,” says Dr. Leung. The bacteria makes the skin even more inflamed and itchy, which can trigger scratching that allows the staph bacteria to penetrate, Leung says. People with atopic dermatitis have a defect in their skin that makes them particularly vulnerable to Staph aureus, Leung explains. “When it binds to skin in normal people, they usually should be able to fight that infection pretty well,” he says. But when there’s eczema, “Staph aureus can proliferate and grow and causes more and more inflammation.” He adds, “You can treat this infection with antibiotics, but doing that kills both the good and bad bacteria — that’s a problem because the good bacteria can help protect the skin.” The scientists reasoned that if there was a type of bacteria found on healthy skin that could inhibit the growth of Staph aureus, it could prevent infection and bring the microbiome into better balance. After screening thousands of different strains, researchers identified a single strain, Staphylococcus hominis A9, that fit the bill. In a clinical trial of 54 people with atopic dermatitis, the application of Staphylococcus hominis A9 led to symptom improvement in two-thirds of the subjects, including fewer complaints of itchiness and irritation, according to results published in February 2021 in Nature Medicine. “We were able to safely transplant the bacteria onto the skin of people with eczema, and it got better,” says Leung. Now Leung and his team are working on a way to give the good bacteria staying power. “The skin is a hostile environment — it’s constantly trying to recognize what’s good and bad — so if something that the skin is not used to gets put on the skin, the skin tries to get rid of it,” he says.
Will Bacterial Therapy Ever Be Available to Patients Outside Clinical Trials?
Although the initial findings on bacterial therapy for eczema have been promising, it’s likely that these treatments are years away from widespread patient use. Myles explains that the NIH licensed its Roseomonas mucosa to the pharmaceutical company Forte, which conducted a placebo-controlled trial. “Although the specifics of that study aren’t available to the public, the findings weren’t statistically significant and so they are walking away,” he says. The failure of the trial doesn’t mean this bacterial therapy wouldn’t be effective for some people or that it won’t ever be available. “It may be that eventually this product — in part because it does appear to be so safe — may be sold over the counter as a topical probiotic rather than by prescription,” says Myles. As for the research on Staph hominis, clinical trials in humans are just beginning. “Each step that’s necessary to get a drug approved by the FDA can take a year, and last year we published phase 1 results,” Leung says. He emphasizes that treatments that focus on the power of good bacteria over bad may play a crucial role in the future. “The goal is to have more natural therapies for eczema, which is important as there are a growing number of bacteria that are resistant to antibiotics,” he says.
