The study may help in the search for future therapeutic strategies to fight a growing medical problem that currently lacks effective treatments, researchers from Cincinnati Children's Hospital Medical Center report in the Aug. 29 Nature Immunology.
The prevalence of asthma has been increasing in recent years, according to Marsha Wills-Karp, Ph.D., director of the division of Immunobiology at Cincinnati Children's and the study's senior investigator. The disease can be triggered in susceptible people by a variety of environmental contaminants – such as cigarette smoke, allergens and airborne pollution.
Dr. Wills-Karp's research team has found a molecular tipping point that upsets a delicate balance between underlying mild disease and more severe asthma. They identify the pro-inflammatory protein, interleukin-17 (IL-17A), as the chief culprit behind severe asthma-like symptoms in mice.
"This study suggests that at some point it may be possible to treat or prevent severe forms of asthma by inhibiting pathways that drive the production of IL-17A," Dr. Wills-Karp said.
The disease process appears to begin when airway exposure to environmental allergens causes dysfunctional regulation of a gene called complement factor 3 (C3), which works through a part of the immune system called the complement activation cascade. This leads to overzealous production of IL-17A by airway cells and sets off what the scientists describe as an "amplification loop," when IL-17A in turn induces more C3 production at the airway surface.
The amplification loop perpetuates increasing inflammatory responses involving irregular T helper cells, other interleukin proteins (IL-13 and IL-23), as well as airway hyper-responsiveness and airflow obstruction.
Previous studies have shown the presence of IL-17A proteins in human asthma but no apparent role. Earlier research involving mouse models of the disease has suggested possible roles for IL-17A in asthma, and this study expands on those findings.
The current study involved mice bred genetically to closely resemble people susceptible to severe asthma. Mouse airways were exposed to house dust mite allergen extract to gauge the severity of disease and analyze biochemical responses in airway tissues.
One group of mice was deficient in the immune system gene C5, which normally prevents harmful airway immune responses to inhaled environmental allergens. These mice generated high numbers of T helper cells (known specifically in this instance as TH17 cells) that produced significant IL-17A and caused airway hyper-responsiveness. When researchers blocked IL-17A production in this group, the mice had less airway hyper-responsiveness.
A second group of mice was deficient in the C3aR gene (a receptor for C3), which regulates the dysfunctional response to airway allergens that lead to asthma. These mice had fewer IL-17A producing TH17 cells and less airway hyper-responsiveness. When researchers increased the amount of IL-17A in the airways of this group, the mice experienced greater airway hyper-responsiveness.
As Dr. Wills-Karp and her colleagues continue their research, they will study the relationship between C3 and IL-17A in severe asthmatics, and explore the effectiveness of targeting either the C3 or IL-17A pathways for the treatment of severe asthma. A drug that blocks the function of C3 is currently under development and testing outside of Cincinnati Children's for treatment of the eye disease macular degeneration.
Funding support for the study came from the National Institutes of Health and the Parker B. Francis Fellowship Program.
Also collaborating on the study were co-first authors Stephane Lajoie, Ph.D., and Ian Lewkowich, Ph.D., research fellows in Dr. Wills-Karp's laboratory.
About Cincinnati Children's
Cincinnati Children's Hospital Medical Center is one of just eight children's hospitals named to the Honor Roll in U.S. News and World Report's 2010-11 Best Children's Hospitals. It is ranked #1 for digestive disorders and highly ranked for its expertise in pulmonology, cancer, neonatology, heart and heart surgery, neurology and neurosurgery, diabetes and endocrinology, orthopedics, kidney disorders and urology. Cincinnati Children's is one of the top two recipients of pediatric research grants from the National Institutes of Health. It is internationally recognized for quality and transformation work by Leapfrog, The Joint Commission, the Institute for Healthcare Improvement, the federal Agency for Healthcare Research and Quality, and by hospitals and health organizations it works with globally. Additional information can be found at www.cincinnatichildrens.org.
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences