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Published on: June 17, 2020
Monocyte activation in patients with age-related macular degeneration: a biomarker of risk for choroidal
Scott W Cousins1, Diego G Espinosa-Heidmann, Karl G Csaky
1Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Fla. 33136, USA. scousins@med.miami.edu
Objective:
To evaluate the activation state of macrophage function in patients with age-related macular degeneration (AMD) by quantifying the production of the proinflammatory and angiogenic factor tumor necrosis factor alpha (TNF-alpha) and by correlating its expression with dry and wet AMD.
Methods:
Circulating monocytes were obtained from the blood of patients with AMD or age-matched control subjects by gradient centrifugation. The monocytes were then analyzed for either TNF-alpha release from cultured macrophages in response to retinal pigment epithelium-derived blebs and cytokines or TNF-alpha messenger RNA content by reverse transcriptase-polymerase chain reaction.
Results:
In human monocytes obtained from controls and AMD patients, TNF-alpha was expressed by freshly isolated monocytes and produced by macrophages in culture after stimulation with retinal pigment epithelium-derived blebs. However, wide variability in TNF-alpha expression was observed among different patients. Patients with monocytes that expressed the greatest amount of TNF-alpha demonstrated higher prevalence of choroidal neovascularization.
Conclusions:
Both controls and AMD patients vary in the activation state (defined as TNF-alpha expression) of circulating monocytes. Partially active monocytes, defined as high TNF-alpha expression, may be a biomarker to identify patients at risk for formation of choroidal neovascularization.
Clinical Relevance:
Early diagnostic testing may prove useful to detect those patients who will progress to the more severe complications of the disease.
Insights
High tumor necrosis factor alpha (TNF-alpha) expression in monocytes may indicate increased risk for choroidal neovascularization in age-related macular degeneration (AMD) patients. Early detection could identify those at risk for severe disease progression.
Area of Science:
- Ophthalmology
- Immunology
- Molecular Biology
Background:
- Age-related macular degeneration (AMD) is a leading cause of vision loss.
- Macrophage activation and inflammatory processes are implicated in AMD pathogenesis.
- Tumor necrosis factor alpha (TNF-alpha) is a key proinflammatory and angiogenic factor.
Purpose of the Study:
- To evaluate macrophage activation in AMD patients by measuring TNF-alpha production.
- To correlate TNF-alpha expression levels with the presence of dry and wet AMD.
- To investigate TNF-alpha as a potential biomarker for AMD progression.
Main Methods:
- Mononuclear cells were isolated from AMD patients and age-matched controls.
- TNF-alpha release from cultured macrophages was assessed.
- TNF-alpha messenger RNA (mRNA) levels were quantified using reverse transcriptase-polymerase chain reaction (RT-PCR).
Main Results:
- TNF-alpha was expressed in freshly isolated monocytes and produced by macrophages in both controls and AMD patients.
- Significant variability in TNF-alpha expression was observed among individuals.
- Elevated TNF-alpha expression in monocytes correlated with a higher prevalence of choroidal neovascularization.
Conclusions:
- Circulating monocyte activation, indicated by TNF-alpha expression, varies in both AMD patients and controls.
- High TNF-alpha expression in monocytes may serve as a biomarker for identifying patients at risk of developing choroidal neovascularization.
- Early diagnostic testing for TNF-alpha levels could help identify patients prone to severe AMD complications.
