Type 2 inflammation
# Type 2 inflammation

Type 2 inflammation is a pattern of immune response. Its physiological function is to defend the body against helminths, but a dysregulation of the type 2 inflammatory response has been implicated in the pathophysiology of several diseases.

## Molecular biology

IL-25, IL-33, and TSLP are alarmins released from damaged epithelial cells. These cytokines mediate the activation of type 2 T helper cells $(T_h2$ cells), type 2 innate lymphoid cells (ILC2 cells), and dendritic cells. $T_h2$ cells and ILC2 cells secrete IL-4, IL-5 and IL-13.

IL-4 further drives CD4+ T cell differentiation towards the $T_h2$ subtype and induces isotype switching to IgE in B cells. IL-4 and IL-13 stimulate trafficking of eosinophils to the site of inflammation, while IL-5 promotes both eosinophil trafficking and production.

## Dysregulation in human disease

Type 2 inflammation has been implicated in several chronic diseases:

* Asthma
* Atopic dermatitis
* Chronic sinusitis with nasal polyps
* Eosinophilic esophagitis

Persons with one type 2 inflammatory disease are more likely to have other type 2 inflammatory diseases.

## Pharmacological targets

Several medicines have been developed that target mediators of type 2 inflammation:

* IL-4-specific blockers:
   * Altrakincept
   * Pascolizumab
* IL-5-specific blockers:
   * Benralizumab
   * Mepolizumab
   * Reslizumab
* IL-13-specific blockers:
   * Lebrikizumab
   * Tralokinumab
* Dual IL-4 and IL-13 blockers:
   * Dupilumab
* IgE-blockers:
   * Ligelizumab
   * Omalizumab
