### IFNL1 Gene Overview

**Gene Symbol:** IFNL1  
**Location:** Chromosome 19q13  
**Aliases:** IL28A

**Description:**  
The IFNL1 gene encodes a cytokine known as Interferon lambda 1 (IFN-λ1), which plays a significant role in the immune response, particularly with antiviral, antitumor, and immunomodulatory activities. It is part of the type III interferon family, closely related to IL28A and IL28B. IFN-λ1 acts as a ligand for a heterodimeric receptor consisting of IL10RB and IFNLR1, activating the JAK/STAT signaling pathway that leads to the expression of various interferon-stimulated genes (ISGs).

### 1. Associated Genes

While the summaries provided mention IL28A and IL28B, several other genes have been linked through various biological processes and immune responses, including:

- **IFNLR1** (Interferon lambda receptor 1): The primary receptor for IFN-λ1.
- **IL10RB** (Interleukin 10 receptor beta): A component of the heterodimeric receptor complex for IFN-λ1 and other cytokines.
- **ISGs** (Interferon-stimulated genes): A broad range of genes induced by interferon signaling that contribute to the antiviral state.
- **JAK1** and **TYK2**: Janus kinases involved in the signaling cascade initiated by the binding of IFN-λ1 to its receptor.

### 2. Aging and Age-related Diseases

Although there isn't a direct link between IFNL1 and aging mentioned in the literature, studies suggest that cytokines, including type III interferons, may have implications in age-related diseases due to their roles in inflammation and immune response. Dysregulation of IFN-λ signaling has been associated with chronic inflammatory conditions, which often increase with age. Furthermore, its role in antiviral responses is crucial as older adults generally exhibit weakened immune responses, making the study of this cytokine particularly relevant for age-related viral infections and disease susceptibility.

### 3. Drug Interactions

Drugs or drug classes that have been known to interact with IFNL1 include:

- **Antiviral Therapies:** Particularly those targeting hepatitis C virus, where IFNL1 plays a role in the immune response. Some pegylated interferon therapies may influence IFNL1 expression.
- **Immunomodulators:** Certain immunotherapeutic drugs may modulate the activity or expression levels of IFNL1 as part of broader immune response modulation.

While there are no specific drugs that target IFNL1 directly in clinical use at this moment, research continues in terms of using IFN-λ in therapeutic contexts.

### 4. Pathways and Biological Processes

IFNL1 is involved in several key biological processes and pathways, including:

- **Antiviral Defense:** Induces the expression of ISGs that provide an antiviral state in cells.
- **JAK/STAT Signaling Pathway:** Activates this pathway upon engagement with its receptor leading to downstream effects on gene expression.
- **Immune System Regulation:** Modulates immune responses, particularly in epithelial tissues, and enhances major histocompatibility complex (MHC) class I antigen expression, which is critical for cellular immune responses.
- **Cellular Responses to Viral Infection:** Plays a significant role in the host response to viral pathogens.

### Conclusion

The IFNL1 gene is critical in antiviral immunity with specific receptor interactions that limit its effects to certain cell types, particularly epithelial cells. Ongoing research into its role in aging and potential therapeutic interventions continues to reveal its significance in health and disease.