Interferon lambda

Interferon (short: IFN) is a group of signaling proteins(cytokines) that are part of the immune response to viral infections as well as to some other diseases, including certain cancers and autoimmune diseases. Interferons are produced by various cells in the body, particularly in response to the presence of pathogens such as viruses.

Interferon lambda (short form: IFN-λ) is a cytokine that belongs to the type III interferon family (see also under interferons)It plays an important role in the immune response, especially against viral infections. IFN-λ is produced by various cells in response to viral pathogens and has different properties to other interferons, such as type I (e.g. IFN-α and IFN-β) and type II (e.g. IFN-γ) interferons.

Types: There are several subtypes of interferon lambda:

IFN-λ1 (also known as IL-29 )

IFN-λ2(IL-28A) and

IFN-λ3(IL-28B).

These subtypes show structural similarities and have overlapping but different biological activities.

Mechanisms of action: IFN-λ binds to a specific receptor complex (consisting of the IFN-λ receptor 1 and the IL-10 receptor 2). This binding activates signaling pathways that lead to the expression of antiviral genes, improve the antiviral state of the cells and promote the immune response against viral infections.

Role in viral infections: IFN-λ is particularly important in the defense against viral infections, such as hepatitis C virus(HCV), influenza and various other RNA and DNA viruses. It helps to limit the replication and spread of viruses. Thus, extensive functions of IFN-λ in anti-enteric SARS-CoV-2 infection have also been described, implying possible application of IFN-λ as a therapeutic agent for COVID-19 with intestinal symptoms (Pan YY et al. 2023).

Tissue specificity: One of the characteristic features of IFN-λ is its tissue-specific action. It is particularly effective on epithelial cells, which are the primary site of viral infection for many pathogens. This makes it an important player in mucosal immunity. Thus, interferon λ (IFN-λ) stimulates immunomodulatory signals that act on epithelial cells and few other cell types due to restricted IFN-λ receptor expression (Wallace JW et al. 2021). IFN-λ has been shown to act via non-epithelial cell types, such as neutrophil granulocytes, to protect against excessive inflammation. In most cases, IFN-λ shows the ability to coordinate the host antiviral response without triggering collateral hyperinflammation, suggesting that IFN-λ signaling pathways may be a therapeutic target in IBD (Wallace JW et al. 2021).

Therapeutic applications: Due to its antiviral properties, IFN-λ has been investigated as a therapeutic agent for various viral infections. For example, antiviral drugs containing IFN-λ have been investigated for the treatment of hepatitis C and other viral diseases.

Side effects: Compared to type I interferons, IFN-λ is associated with fewer side effects. This is partly because it has a more limited spectrum of target cells and a more specific effect.

Research and development: IFN-λ is an active area of research exploring new formulations and therapeutic applications, particularly in the context of viral hepatitis, respiratory viruses and other infectious diseases.

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