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Driving Role of Interleukin-2-Related Regulatory CD4+ T Cell Deficiency in the Development of Lung Fibrosis and
Camelia Frantz1, Anne Cauvet2, Aurélie Durand2
1Université de Paris, Inserm U1016, CNRS UMR 8104, and Cochin Hospital, Paris, France.
Objective:
Systemic sclerosis (SSc) is a debilitating autoimmune disease characterized by severe lung outcomes resulting in reduced life expectancy. Fra-2-transgenic mice offer the opportunity to decipher the relationships between the immune system and lung fibrosis. This study was undertaken to investigate whether the Fra-2-transgenic mouse lung phenotype may result from an imbalance between the effector and regulatory arms in the CD4+ T cell compartment.
Methods:
We first used multicolor flow cytometry to extensively characterize homeostasis and the phenotype of peripheral CD4+ T cells from Fra-2-transgenic mice and control mice. We then tested different treatments for their effectiveness in restoring CD4+ Treg cell homeostasis, including adoptive transfer of Treg cells and treatment with low-dose interleukin-2 (IL-2).
Results:
Fra-2-transgenic mice demonstrated a marked decrease in the proportion and absolute number of peripheral Treg cells that preceded accumulation of activated, T helper cell type 2-polarized, CD4+ T cells. This defect in Treg cell homeostasis was derived from a combination of mechanisms including impaired generation of these cells in both the thymus and the periphery. The impaired ability of peripheral conventional CD4+ T cells to produce IL-2 may greatly contribute to Treg cell deficiency in Fra-2-transgenic mice. Notably, adoptive transfer of Treg cells, low-dose IL-2 therapy, or combination therapy changed the phenotype of Fra-2-transgenic mice, resulting in a significant reduction in pulmonary parenchymal fibrosis and vascular remodeling in the lungs.
Conclusion:
Immunotherapies for restoring Treg cell homeostasis could be relevant in SSc. An intervention based on low-dose IL-2 injections, as is already proposed in other autoimmune diseases, could be the most suitable treatment modality for restoring Treg cell homeostasis for future research.
Insights
Systemic sclerosis lung fibrosis may stem from regulatory T cell (Treg) deficiency. Restoring Treg balance with therapies like low-dose interleukin-2 (IL-2) significantly reduced lung fibrosis in Fra-2-transgenic mice.
Area of Science:
- Immunology
- Pulmonary Medicine
- Autoimmune Diseases
Background:
- Systemic sclerosis (SSc) is a severe autoimmune disease with poor prognosis, often involving lung complications.
- Fra-2-transgenic mice serve as a model to study immune system interactions and lung fibrosis.
- Investigating CD4+ T cell imbalances is crucial for understanding SSc pathogenesis.
Purpose of the Study:
- To investigate the role of CD4+ T cell imbalance in the lung phenotype of Fra-2-transgenic mice.
- To determine if restoring regulatory T cell (Treg) homeostasis can ameliorate lung fibrosis in this model.
Main Methods:
- Characterization of peripheral CD4+ T cell populations in Fra-2-transgenic and control mice using multicolor flow cytometry.
- Assessment of Treg cell homeostasis and function.
- Evaluation of therapeutic interventions including Treg cell adoptive transfer and low-dose interleukin-2 (IL-2) therapy.
Main Results:
- Fra-2-transgenic mice showed a significant decrease in Treg cells preceding an increase in activated T helper type 2 cells.
- Impaired Treg generation in thymus and periphery, and reduced IL-2 production by conventional CD4+ T cells contributed to Treg deficiency.
- Adoptive transfer of Treg cells, low-dose IL-2, or combination therapy reduced pulmonary fibrosis and vascular remodeling.
Conclusions:
- Restoring Treg cell homeostasis is a potential therapeutic strategy for SSc-related lung disease.
- Low-dose IL-2 therapy shows promise for restoring Treg homeostasis and warrants further investigation in SSc.
