Integrin antagonists prevent costimulatory blockade-resistant transplant rejection by CD8(+) memory T cells

Area of Science:

• Immunology
• Transplantation immunology
• T-cell activation

Background:

• Belatacept, a costimulatory blockade immunosuppressant, shows promise in kidney transplantation but is associated with increased acute rejection rates.
• This highlights the challenge of costimulatory blockade-resistant rejection, particularly mediated by memory T cells.

Purpose of the Study:

• To investigate the mechanisms underlying costimulatory blockade-resistant rejection mediated by memory T cells.
• To identify strategies to enhance the efficacy of costimulatory blockade in transplantation.

Main Methods:

• Developed a novel experimental transplant system modeling donor-specific memory CD8(+) T-cell responses.
• Investigated the role of integrins (VLA-4 and LFA-1) in costimulatory blockade-resistant rejection.
• Assessed the impact of anti-VLA-4 and anti-LFA-1 on T-cell trafficking and effector function.

Main Results:

• Confirmed that memory T cells mediate costimulatory blockade-resistant rejection.
• Coupling costimulatory blockade with anti-VLA-4 or anti-LFA-1 abrogated this resistance.
• Anti-VLA-4 primarily inhibited T-cell trafficking, while anti-LFA-1 inhibited both trafficking and effector function.

Conclusions:

• Integrins play a critical role in memory T-cell-mediated rejection resistant to costimulatory blockade.
• Targeting VLA-4 and LFA-1 in combination with costimulatory blockade offers a potential strategy to improve transplant outcomes.
• These findings have significant translational potential for clinical kidney transplant trials.