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Differentiation potential of CD14+ monocytes into myofibroblasts in patients with systemic sclerosis
Nadine Binai1, Steven O'Reilly, Bridget Griffiths
1Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
Background:
Circulating monocytes are a highly plastic and functionally heterogeneic cell type with an activated phenotype in patients with systemic sclerosis (SSc). CD14(+) monocytes have the potential to differentiate into extra-cellular matrix (ECM) producing cells, possibly participating in fibrogenesis.
Aim:
To study the effect of GM-CSF, IL-4 and endothelin -1 (ET-1) alone or in combination on monocyte differentiation into myofibroblasts.
Methods:
CD14(+) cells were isolated from peripheral blood from 14 SSc patients and healthy controls by positive selection and incubated with different combinations of GM-CSF, IL-4 and ET-1 for 14 days. Type-1 collagen and α-SMA were detected by Western blot, qPCR and confocal microscopy. HLA-DR, CD11c and CD14 expression was analysed by flow cytometry. A collagen gel contraction assay was performed for functional myofibroblast assessment.
Results:
GM-CSF both induced collagen and α-SMA expression after 14 days. ET-1 further increased GM-CSF-induced collagen expression in a dose dependent manner up to 30-fold. IL-4/GM-CSF combination leads to a more DC-like phenotype of monocytes associated with reduced collagen and α-SMA expression compared to GM-CSF alone. Collagen and α-SMA expression was higher in monocytes from SSc patients and monocytes were more prone to obtain a spindle form. In contrast to controls, ET-1 and IL-4 alone were sufficient to induce α-SMA expression in monocytes from SSc patients. Despite the induction of α-SMA expression, monocyte-derived myofibroblasts only had a moderate capability of contraction in functional analyses.
Conclusion:
SSc monocytes display increased maturation towards myofibroblasts demonstrated by their phenotype and α-SMA expression when compared to monocytes from healthy controls, however only with minor functional contraction properties.
Insights
Systemic sclerosis (SSc) patients
Area of Science:
- Immunology
- Cell Biology
- Rheumatology
Background:
- Circulating monocytes in systemic sclerosis (SSc) patients exhibit an activated phenotype.
- CD14(+) monocytes have the potential to differentiate into extracellular matrix (ECM)-producing cells, contributing to fibrogenesis.
Purpose of the Study:
- To investigate the impact of GM-CSF, IL-4, and endothelin-1 (ET-1) on monocyte differentiation into myofibroblasts.
- To compare these effects in patients with SSc versus healthy controls.
Main Methods:
- Isolation of CD14(+) monocytes from SSc patients and controls.
- Incubation with GM-CSF, IL-4, and ET-1, alone or in combination, for 14 days.
- Assessment of collagen, α-SMA, HLA-DR, CD11c, CD14 expression, and collagen gel contraction.
Main Results:
- GM-CSF induced collagen and α-SMA expression; ET-1 dose-dependently enhanced this effect.
- IL-4/GM-CSF promoted a dendritic cell (DC)-like phenotype with reduced collagen/α-SMA.
- SSc monocytes showed higher collagen/α-SMA expression, increased propensity for spindle morphology, and ET-1/IL-4 induced α-SMA independently of GM-CSF.
Conclusions:
- Monocytes from SSc patients demonstrate enhanced myofibroblast differentiation compared to controls.
- This increased differentiation is characterized by specific phenotypic changes and α-SMA expression.
- Despite enhanced differentiation markers, monocyte-derived myofibroblasts exhibit limited functional contraction capacity.
