A Russian team of scientists has studied the role of the interleukin-6 molecule for allergic asthma. This newly studied molecular switch may help to treat allergic asthma. These study findings are published in Frontiers in Immunology and are available online to view.
Nearly 300 million people around the globe are a patient of asthma. It is one of the most common and chronic lung diseases, particularly in developed countries.
Asthma is a condition initiated by an inadequate response of the immune system to allergens. These allergens could be anything such as pollen of trees, herbs, mold fungi, the fur of cats and dogs or even the dust mites.
This exposure to allergens leads to chronic inflammation, making bronchi narrow and sometimes a complete respiratory failure. The aim of this study was to find out which internal signals and cell types are responsible for initiating this immune response in asthma.
The cells use molecular language for communication. The cytokines may help to control every immune response by blocking insufficient signals and changing the intensity of the disease i.e. from severe to lighter or vice a versa.
For studying this, the clinical samples of sputum were obtained from patients with bronchial asthma. All of these showed a high content of interleukin-6, responsible for indicating an inflammation inside the body. The team aimed to study which immune cells produce interleukin-6 and how its blockage affects the intensity of asthma.
The research team was trying to study the language of cytokines to understand their signals with specific types of producer cells. This is an old paradigm that was used to study tumor necrosis factor. For interleukin-6, a similar pattern was thought to occur.
All the experiments were carried out on unique genetically modified mice. In these mice, the interleukin-6 production was turned off in dendritic cells ( a specific type of immune cells that represent alien objects to T-lymphocytes or macrophages).
For asthma induction in mice, they were injected with an allergen i.e. dust mite extract. This allergen is also one of the most common causative agents in human asthma cases.
Like humans, the mice also feel the irritation of the mucous membranes in the respiratory tract when exposed to the allergen. This activates some specialized cells of the immune system, T-helper cells of the second type.
“These T cells help the body by fighting against the allergies and attract inflammatory immune cells to the affected tissues: eosinophils, B cells, and basophils”, as Ekaterina Gubernatorova, the first author of the article explains.
But it’s not just the epithelium but also, there are more readable sensors of foreign molecules present inside the lung tissues. These are macrophages and dendritic cells.
While submitting many cytokine signals these cells control the strength and quality of the immune response for which interleukin-6 is undoubtedly an instruction giver for them.
For this study, the scientists proved that interleukin-6 from macrophages is helpful to create a common response of T-helper cells of the second type. Eosinophil cells also play a lead role here. Interleukin-6 is produced by dendritic cells which are involved in extreme asthma subtype (that are mediated by T-helper cells).
The most abundant type of white blood cells are neutrophils and in asthma, they are a supporter of long-term, non-healing inflammation inside the lungs. This is the reason why there is no effective treatment so far.
Thus, for future, interleukin-6 may be a new target that treats asthma. It is particularly true for a subtype associated with the neutrophils accumulation in the respiratory airways.