Dysregulated lymphocyte localization in idiopathic multicentric Castleman disease

Area of Science:

• Hematology
• Immunology
• Pathophysiology

Background:

• Idiopathic multicentric Castleman disease (iMCD) is a rare, life-threatening hematologic disorder characterized by systemic inflammation and lymphadenopathy.
• The underlying causes and pathophysiological mechanisms of iMCD remain poorly understood, with limited effective treatment options.

Purpose of the Study:

• To investigate the role of chemokines, specifically CXCL13, in the lymphadenopathy associated with iMCD.
• To elucidate the mechanisms by which lymphocyte trafficking is disrupted in iMCD.

Main Methods:

• Analysis of chemokine levels (CXCL13) and lymphocyte (T and B cells, T follicular helper cells) expression of CXCR5 in iMCD lymph nodes during active disease.
• Assessment of lymphocyte localization within germinal centers (GCs) and their response to chemokine cues.

Main Results:

• Elevated CXCL13 levels correlate with lymph node size in iMCD patients.
• Lymphocytes in active iMCD downregulated CXCR5, impairing their response to CXCL13.
• T and B cells were scarce in CXCL13-expressing GCs, and T follicular helper cell function was restricted.

Conclusions:

• Dysregulated CXCL13 production by lymph node stromal cells contributes to abnormal germinal center lymphocyte trafficking in iMCD.
• Impaired lymphocyte chemotaxis and GC responses represent a potential mechanism underlying iMCD lymphadenopathy.
• Targeting chemokine pathways may offer a novel therapeutic strategy for iMCD.