From the Guidelines
Elevated IL-8 is primarily caused by inflammatory processes in the body, particularly in response to cigarette smoke, as evidenced by increased quantities of IL-8 found in the sputum of smokers with chronic bronchitis 1.
Causes of Elevated IL-8
The causes of elevated IL-8 can be multifaceted, including:
- Bacterial and viral infections
- Tissue injury
- Chronic inflammatory conditions such as chronic bronchitis and COPD
- Inflammatory bowel diseases
- Autoimmune disorders
- Certain cancers
Mechanisms of IL-8 Elevation
IL-8 elevation can be triggered by various factors, including:
- Bacterial endotoxins
- Oxidative stress
- Pro-inflammatory cytokines like TNF-α and IL-1β
- Environmental factors such as air pollutants and UV radiation
- Cigarette smoke, which has been shown to increase IL-8 production in the airways of smokers with chronic bronchitis 1
Cellular Production of IL-8
IL-8 is produced by various cells, including:
- Macrophages
- Epithelial cells
- Endothelial cells In response to inflammatory stimuli, these cells produce IL-8, which functions to attract neutrophils to infection sites and promote angiogenesis.
Clinical Implications
Persistent elevation of IL-8 contributes to chronic inflammation and tissue damage in many pathological conditions, highlighting the importance of addressing the underlying causes of IL-8 elevation to prevent long-term consequences.
Key Findings
A study published in the journal Chest found that increased quantities of IL-8 were found in the sputum of smokers with chronic bronchitis, and even further increased quantities of these cytokines were found during acute exacerbations 1. Another study published in the Annals of the Rheumatic Diseases found that IL-8 levels were persistently raised in patients with adult-onset Still's disease, even in disease remission 1.
From the Research
Causes of Elevated IL-8
Elevated IL-8 levels have been associated with various conditions, including:
- Cancer: IL-8 is produced in large quantities by many solid tumors and can promote angiogenesis, recruit immunosuppressive cells, and stimulate epithelial-to-mesenchymal transition, which is a precursor to metastasis 2, 3, 4.
- Acute coronary syndrome: Elevated baseline plasma IL-8 levels are an independent predictor of long-term all-cause mortality in patients with acute coronary syndrome 5.
- Ataxia telangiectasia: Elevated serum IL-8 levels have been found in patients with ataxia telangiectasia, suggesting that systemic inflammation may contribute to the disease phenotype 6.
- Immunotherapy resistance: Elevated IL-8 levels have been associated with poor outcome in patients treated with immune-checkpoint inhibitors, revealing the importance of assessing serum IL-8 levels in identifying unfavorable tumor immunobiology 3.
Mechanisms of Elevated IL-8
The mechanisms underlying elevated IL-8 levels include:
- Tumor production: IL-8 is produced by many solid tumors and can act upon a variety of immune and nonimmune cells 2.
- Inflammation: Systemic inflammation may contribute to elevated IL-8 levels in conditions such as ataxia telangiectasia 6.
- Immune response: IL-8 can recruit immunosuppressive cells and stimulate epithelial-to-mesenchymal transition, which is a precursor to metastasis 2, 3.