Absolute decrease in regulatory T cells and low-dose interleukin-2 therapy: restoring and expanding regulatory T...

Area of Science:

• Immunology
• Autoimmune Diseases
• Rheumatology

Background:

• Systemic sclerosis (SSc) is an autoimmune disease characterized by vascular, immunological, and fibrotic changes.
• Evidence suggests an imbalance in T-cell subsets in SSc patients.
• Interleukin-2 (IL-2) is a cytokine that regulates immune cell activity, with low-dose therapy showing potential for autoimmune diseases.

Purpose of the Study:

• To investigate peripheral lymphocyte subset changes, particularly T helper 17 (Th17) and regulatory T (Treg) cells, in SSc.
• To evaluate the effects of low-dose IL-2 therapy on these subsets and disease activity in SSc patients.

Main Methods:

• Flow cytometry was used to determine peripheral lymphocyte subset numbers in 66 SSc patients and 49 healthy controls (HCs).
• SSc patients were divided into an IL-2 group (low-dose IL-2 plus conventional therapy) and a non-IL-2 group (conventional therapy only).

Main Results:

• SSc patients exhibited significantly lower numbers of peripheral T cells, CD4+ T cells, CD8+ T cells, natural killer (NK) cells, and Treg cells compared to HCs.
• A marked decrease in Treg cells led to an elevated Th17 to Treg cell ratio in SSc patients.
• Low-dose IL-2 treatment increased Treg cells, tending to restore the Th17/Treg balance and significantly improving disease markers (ESR, CRP, Rodnan Skin Score, VAS) more than conventional therapy alone.

Conclusions:

• Patients with SSc show decreased peripheral Treg cells, resulting in an imbalanced Th17/Treg ratio.
• Low-dose IL-2 therapy effectively restores the balance of Th17 and Treg cells.
• Low-dose IL-2 treatment reduces SSc disease activity without significant adverse effects.