Regulatory B Cells in Systemic Sclerosis Isolated or Concomitant With Hashimoto Thyroiditis

Area of Science:

• Immunology
• Autoimmune Diseases
• Cell Biology

Background:

• Systemic sclerosis (SSc) frequently causes gastrointestinal issues and can co-occur with autoimmune thyroid disorders like Hashimoto's thyroiditis (HT).
• Th17 lymphocytes and regulatory B cells (Breg) are implicated in HT and other autoimmune conditions, but their combined behavior in coexisting SSc and HT is unknown.

Purpose of the Study:

• To investigate the distinct roles of Th17 lymphocytes and Breg cells in patients with isolated HT, isolated SSc, and coexisting SSc and HT.
• To analyze the functional capacity of Breg cells, specifically their IL-10 production, in these patient groups.

Main Methods:

• Flow cytometry was used to quantify Th17 lymphocytes and Breg cells (CD24hiCD38hi) in 50 subjects (18 healthy donors, 20 with HT, 12 with SSc).
• Breg cell function was assessed by measuring IL-10 production following stimulation with CpG activators.

Main Results:

• HT patients exhibited a higher percentage of Th17 lymphocytes compared to healthy donors and SSc patients.
• SSc patients, with or without HT, showed a higher percentage of unstimulated Breg cells than HT patients and healthy donors.
• While SSc patients had increased total Breg cells after stimulation, they displayed a significantly reduced percentage of IL-10 producing Breg cells, indicating impaired function, independent of HT.

Conclusions:

• Systemic sclerosis is associated with an increased number of regulatory B cells but a diminished functional capacity for IL-10 production, irrespective of Hashimoto's thyroiditis.
• The observed alterations in Breg cell function in SSc patients differ from those seen in HT patients and highlight a unique immune dysregulation in SSc.