Alterations in Circulating Progenitor Cell Composition in Rheumatoid Arthritis.

Area of Science:

• Immunology
• Hematology
• Rheumatology

Background:

• Rheumatoid arthritis (RA) is a chronic autoimmune disease causing joint inflammation and systemic immune imbalance.
• Bone marrow activation is implicated in RA, but direct tissue analysis is challenging.
• Peripheral blood progenitor cell analysis offers a surrogate for bone marrow status.

Purpose of the Study:

• To investigate alterations in peripheral blood progenitor cells and immune cells in RA patients.
• To explore the role of CD31 expression in RA pathogenesis.
• To identify potential biomarkers reflecting systemic immune dysregulation in RA.

Main Methods:

• High-dimensional spectral flow cytometry and FlowSOM clustering analyzed peripheral blood cells from RA patients and healthy controls.
• A nine-marker panel (CD45, CD31, CD235, CD133, CD34, CD105, CD271, CD90, PDPN) was used.
• CD31 expression on immune subsets in peripheral mononuclear cells (PBMCs) was assessed.

Main Results:

• RA patients exhibited increased CD45+CD31- immune cells and elevated CD235a+ erythroid precursors.
• Putative CD45+CD31int progenitors and mature cells were reduced in RA.
• CD31 expression was decreased on T cells in RA patients.
• Three putative circulating stromal cell populations were identified.

Conclusions:

• RA is associated with expanded erythroid precursor populations and reduced CD31 expression on T cells.
• These findings indicate broad systemic alterations in cellular homeostasis in RA.
• Loss of CD31 on immune cell precursors may contribute to immune remodelling and activation in RA.