A new needle-free flu vaccine patch revved up the immune system much like a traditional flu shot without any negative side effects, according to a study published in the Journal of Investigative Dermatology. Though the research is in the early stages (the patch hasn’t been tested in humans), it’s an important step toward a technology that could replace needle-based vaccination methods that require administration by health care workers and biohazard waste removal.
“Scientists have been studying needle-free vaccine approaches for nearly two decades, but none of the technologies have lived up to the hype,” said Benjamin L. Miller, Ph.D., corresponding author and Dean’s Professor of Dermatology at the University of Rochester Medical Center. “Our patch overcomes a lot of the challenges faced by microneedle patches for vaccine delivery, the main method that’s been tested over the years, and our efficacy and lack of toxicity make me excited about the prospect of a product that could have huge implications for global health.”
Common skin disease paves the way for needleless flu shot
Transporting big molecules like flu vaccine proteins across the skin is difficult to do, as the skin is intended to keep things out of the body, not to let them in. The study team took lessons learned from the research and treatment of a common inflammatory skin disease to overcome this hurdle and inform their flu vaccine patch strategy.
In patients with eczema, or atopic dermatitis, the skin barrier is leaky, allowing pollens, molds and a host of other allergens to enter through the skin and be sensed by the immune system. Lisa A. Beck, M.D., corresponding author and Dean’s Professor of Dermatology at the University of Rochester Medical Center discovered that the expression of a protein called claudin-1 helps maintain barrier strength and lessen the permeability of the skin. Claudin-1 is significantly reduced in eczema patients (hence the leaky skin barrier) compared to individuals without the disease.
In past research, Beck found that decreasing claudin-1 expression in skin cells from healthy donors made the skin more permeable. Beck, Miller, and first author Matthew Brewer, Ph.D., wondered if they could use this induced permeability to get a flu vaccine virus through the skin. The key would be to disrupt the skin barrier long enough to deliver the virus, but not so long to let unwanted things in.
How it works: Dermatology, chemistry and vaccine biology collide
Miller, a chemist, worked with Brewer, who was trained in vaccine biology and immunology, to develop synthetic peptides that bind to and inhibit claudin-1 in an effort to open up the skin barrier. They tested their formulations in human skin cells and identified a peptide that disrupted the barrier without any toxic effects.
Next, they designed a patch containing the synthetic peptide and a recombinant flu vaccine and tested two scenarios. In the first, they placed the patch on mice to prime the immune system and subsequently administrated an intramuscular flu shot to boost immunity. In the second they did the opposite, delivering an intramuscular flu shot first to prime the immune system followed by the patch to boost immunity.
In both scenarios they placed the flu vaccine patch, which looks like a tiny piece of tape, on the backs of mice and left if there for as little as 18 and as long as 36 hours. The patch effectively opened up the skin barrier, as measured by water loss through the skin.