Th17 cells as new players in asthma pathogenesis

CD4+ T effector lymphocytes are classified in different subsets on the basis of cytokine secretion:

- Th1 cells, thank to IFN-γ production, are responsible for cell-mediated immunity against intracellular pathogens

- Th2 cells, through the production of IL-4, provide protection against helminthes

- Th17 cells, via IL-17, promote neutrophils recruitment for the clearance of bacteria and fungi


T helper cells (click to enlarge the image).

However, beyond their protective role, T-helpers can also be involved in inflammatory diseases such as asthma.

Allergic asthma is the result of an inflammatory process driven by allergen-specific Th2 lymphocytes.

On the other hand, Th17 cells are mainly involved in those forms of asthma, where neutrophils more than eosinophils, contribute to the inflammation.

The identification of Th17/Th2 cells, able to produce both IL-4 and IL-17, fits the observation that different clinical phenotypes can coexist in the same patient.

References:

Cosmi L, Liotta F, Maggi E, Romagnani S, Annunziato F. Th17 cells: new players in asthma pathogenesis. Allergy 2011; DOI: 10.1111/j.1398-9995.2011.02576.x.

Anti-IL-17 Receptor Antibody Brodalumab Helps Patients with Psoriasis - NEJM, 2012.

Anti–Interleukin-17 Monoclonal Antibody Ixekizumab Improves Chronic Plaque Psoriasis - NEJM, 2012.

Interleukin-17 (IL-17)

T Helper Cells

IL-17A inhibition by secukinumab induces resolution of psoriasis https://buff.ly/2ZAnSRR