Local IL-17 production and a decrease in peripheral blood regulatory T cells in an animal model of bronchiolitis...

Area of Science:

• Immunology
• Transplantation Biology
• Respiratory Medicine

Background:

• T helper 17 (Th17) cells are implicated in allograft rejection.
• Investigated Th17 and regulatory T cell (Treg) dynamics in a mouse bronchiolitis obliterans model post-tracheal transplantation.

Purpose of the Study:

• To analyze alterations in Th17 and Treg cell distribution after tracheal allograft.
• To determine the role of IL-6 and IL-17 in the development of bronchiolitis obliterans.

Main Methods:

• Tracheal allografts were transplanted from B6 to C3H mice.
• Flow cytometry analyzed immune cell populations and intracellular cytokines.
• Quantitative RT-PCR assessed IL-6 and IL-17 mRNA levels in grafts.
• IL-6 neutralization was employed to evaluate its effect on allograft rejection.

Main Results:

• Peripheral Tregs were significantly reduced in allogenic recipients.
• Local IL-6 and IL-17 mRNA levels were elevated in allografts, correlating with graft obliteration.
• IL-6 neutralization suppressed IL-17 mRNA levels and reduced tracheal obliteration severity.

Conclusions:

• Local IL-17 production increases in tracheal allografts, independent of peripheral Th17 cell changes.
• Decreased peripheral Tregs and increased local IL-17, potentially IL-6-mediated, contribute to post-transplantation bronchiolitis obliterans.