### CD163 Gene Overview

**Gene Symbol:** CD163

**Protein Family:** Member of the scavenger receptor cysteine-rich (SRCR) superfamily.

**Expression:** Exclusively expressed in monocytes and macrophages.

#### Functions:
- Acts as an acute phase-regulated receptor involved in the clearance and endocytosis of hemoglobin/haptoglobin complexes.
- Protects tissues from oxidative damage associated with free hemoglobin.
- Serves as an innate immune sensor for bacteria and can induce local inflammation.
- Plays a role in iron uptake and recycling through the breakdown of heme derived from the endocytosis of hemoglobin/haptoglobin complexes.
- Binds hemoglobin/haptoglobin complexes in a calcium- and pH-dependent manner, exhibiting high affinity for HP*1F phenotype complexes.

**Alternate Splicing:** Multiple isoforms due to alternative splicing.

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### Additional Information

1. **Associated Genes:**
   - **Haptoglobin (HP):** The protein encoded by this gene forms complexes with hemoglobin which CD163 targets for uptake.
   - **IL6 (Interleukin 6):** Involved in the signaling cascade induced by CD163 engagement.
   - **CSF1 (Colony Stimulating Factor 1):** Also involved in the signaling cascade related to CD163 function.
   - **Various immune receptor genes:** As a scavenger receptor, CD163 interacts with other receptors involved in macrophage functions.

2. **Aging and Age-Related Diseases:**
   - **Inflammation and Immune Response:** Enhanced CD163 expression in macrophages has been observed in older adults, which may indicate a role in aging-related chronic inflammation, often referred to as ‘inflammaging.’
   - **Neurodegenerative Diseases:** Increased levels of CD163 have been reported in conditions associated with neurodegeneration, suggesting its involvement in the modulation of neuroinflammatory processes.
   - **Cardiovascular Diseases:** Elevated CD163 levels are associated with atherosclerosis and other cardiovascular diseases, which often have age as a risk factor.

3. **Drug Interactions:**
   - **No specific drugs exclusively targeting CD163 are known; however:**
   - **Anti-inflammatory drugs (e.g., corticosteroids)** might impact the CD163 pathway, as they modulate macrophage activity and phenotype.
   - Research may lead to identifying potential therapeutic agents targeting CD163 as a means of regulating macrophage functionality in various diseases.

4. **Pathways and Biological Processes:**
   - **Innate Immune Response:** CD163 plays a role in the immune system's initial response to pathogens.
   - **Heme Metabolism:** Involvement in heme catabolism and iron homeostasis through the uptake of hemoglobin-haptoglobin complexes.
   - **Inflammatory Response:** Induces signaling pathways upon binding hemoglobin/haptoglobin that result in cytokine production, particularly IL-6 and CSF1, which are key mediators of inflammation.
   - **Endocytosis and Phagocytosis:** Participates in the cellular processes related to the uptake of molecules and pathogens.
   - **Calcium Signaling Pathway:** Involved in intracellular signaling cascades that trigger calcium mobilization and changes in cellular functions.

### Conclusion
The CD163 gene is integral to macrophage function, influencing processes such as hemoglobin clearance, inflammatory responses, and iron metabolism. Its roles in aging, immune response modulation, and potential as a therapeutic target continue to be areas of active research, particularly in relation to age-related diseases and chronic inflammation.