Bonzo/CXCR6 expression defines type 1-polarized T-cell subsets with extralymphoid tissue homing potential

Area of Science:

• Immunology
• Cell Biology

Background:

• T-cell differentiation involves precise control of chemokine receptor expression.
• Bonzo (CXCR6) is a newly identified chemokine receptor with an unknown role in T-cell subsets.

Purpose of the Study:

• To investigate the expression and function of Bonzo (CXCR6) in different T-cell populations.
• To determine if Bonzo (CXCR6) can serve as a marker for polarized type 1 T cells.
• To explore the potential role of Bonzo (CXCR6) in T-cell trafficking to inflammatory sites.

Main Methods:

• Flow cytometry analysis of Bonzo (CXCR6) expression on T cells.
• In vitro T-cell priming assays with dendritic cells.
• Cytokine stimulation (IL-12, IL-4) to modulate Bonzo (CXCR6) expression.
• Analysis of T-cell homing receptor expression (L-selectin, CCR7).
• Examination of T cells in inflammatory tissues (rheumatoid joints, inflamed livers).

Main Results:

• Bonzo (CXCR6) is selectively expressed on Th1 and T-cytotoxic 1 (Tc1) cells, but not on Th2 or Tc2 cells.
• Dendritic cell priming induces Bonzo (CXCR6) expression, enhanced by IL-12 and inhibited by IL-4.
• Bonzo+ T cells, particularly Tc1 cells, exhibit cytotoxic effector phenotypes.
• Bonzo+ T cells often lack lymphoid homing receptors (L-selectin, CCR7) but are enriched in inflammatory sites.
• Significant percentages of Bonzo+ CD4 T cells are Th1 (35-56%) and Bonzo+ CD8 T cells are Tc1 (60-65%).

Conclusions:

• Bonzo (CXCR6) is a reliable differential marker for polarized type 1 T cells.
• Bonzo (CXCR6) expression is regulated by dendritic cells and cytokines during T-cell activation.
• Bonzo (CXCR6) expression correlates with cytotoxic effector function in Tc1 cells.
• Bonzo+ T cells are likely involved in trafficking to inflammatory sites, mediating type 1 inflammation.
• Bonzo (CXCR6) represents a potential therapeutic target for inflammatory diseases.