Human dermal fibroblast-derived exosomes induce macrophage activation in systemic sclerosis
Rajan Bhandari1, Heetaek Yang1,2, Noelle N Kosarek1,2
1Department of Microbiology and Immunology.
Objectives:
Prior work demonstrates that co-cultured macrophages and fibroblasts from patients with SSc engage in reciprocal activation. However, the mechanism by which these cell types communicate and contribute to fibrosis and inflammation in SSc is unknown.
Methods:
Fibroblasts were isolated from skin biopsies obtained from 7 SSc patients or 6 healthy age and gender-matched control subjects following written informed consent. Human donor-derived macrophages were cultured with exosomes isolated from control or SSc fibroblasts for an additional 48 h. Macrophages were immunophenotyped using flow cytometry, qRT-PCR and multiplex. For mutual activation studies, exosome-activated macrophages were co-cultured with SSc or healthy fibroblasts using Transwells.
Results:
Macrophages activated with dermal fibroblast-derived exosomes from SSc patients upregulated surface expression of CD163, CD206, MHC Class II and CD16 and secreted increased levels of IL-6, IL-10, IL-12p40 and TNF compared with macrophages incubated with healthy control fibroblasts (n = 7, P < 0.05). Exosome-stimulated macrophages and SSc fibroblasts engaged in reciprocal activation, as production of collagen and fibronectin was significantly increased in SSc fibroblasts receiving signals from SSc exosome-stimulated macrophages (n = 7, P < 0.05).
Conclusion:
In this work, we demonstrate for the first time that human SSc dermal fibroblasts mediate macrophage activation through exosomes. Our findings suggest that macrophages and fibroblasts engage in cross-talk in SSc skin, resulting in mutual activation, inflammation, and extracellular matrix (ECM) deposition. Collectively, these studies implicate macrophages and fibroblasts as cooperative mediators of fibrosis in SSc and suggest therapeutic targeting of both cell types may provide maximal benefit in ameliorating disease in SSc patients.
Insights
Fibroblasts from scleroderma (SSc) patients release exosomes that activate macrophages. This fibroblast-macrophage communication drives inflammation and fibrosis in SSc skin, suggesting dual therapeutic targets.
Area of Science:
- Immunology
- Cell Biology
- Dermatology
Background:
- Scleroderma (SSc) is characterized by fibrosis and inflammation in the skin.
- Reciprocal activation between macrophages and fibroblasts is observed in SSc.
- The precise communication mechanisms driving SSc pathogenesis remain unclear.
Purpose of the Study:
- To investigate the role of fibroblast-derived exosomes in macrophage activation in SSc.
- To elucidate the cellular crosstalk between macrophages and fibroblasts in SSc.
- To identify potential therapeutic targets for SSc.
Main Methods:
- Fibroblasts were isolated from SSc patients and healthy controls.
- Macrophages were cultured with fibroblast-derived exosomes and analyzed via flow cytometry and qRT-PCR.
- Co-culture experiments using Transwells assessed reciprocal activation between exosome-stimulated macrophages and fibroblasts.
Main Results:
- SSc fibroblast exosomes upregulated pro-inflammatory markers (CD163, CD206, MHC Class II, CD16) and cytokines (IL-6, IL-10, IL-12p40, TNF) in macrophages.
- Exosome-activated macrophages induced increased collagen and fibronectin production in SSc fibroblasts.
- Demonstrated reciprocal activation between SSc macrophages and fibroblasts mediated by exosomes.
Conclusions:
- Human SSc dermal fibroblasts activate macrophages via exosomes, establishing a novel communication pathway.
- This fibroblast-macrophage crosstalk contributes to inflammation and extracellular matrix deposition in SSc.
- Targeting both macrophages and fibroblasts may offer a synergistic therapeutic strategy for SSc.
