Defects in CD4+ T cell LFA-1 integrin-dependent adhesion and proliferation protect Cd47-/- mice from EAE

Area of Science:

• Immunology
• Cellular and Molecular Immunology
• Neuroimmunology

Background:

• CD47 is crucial for CD4+ T cell homeostasis, influencing adhesion and transendothelial migration (TEM) via LFA-1 and VLA-4 integrins.
• Previous studies indicated CD47-deficient (Cd47-/-) mice are resistant to experimental autoimmune encephalomyelitis (EAE), attributing it to failed T cell activation.

Purpose of the Study:

• To investigate the mechanism behind Cd47-/- mice's resistance to MOG35-55-induced EAE, specifically examining T cell activation and integrin function.
• To test the hypothesis that impaired LFA-1 and VLA-4 integrin function contributes to EAE resistance in Cd47-/- mice.

Main Methods:

• Experimental autoimmune encephalomyelitis (EAE) induction using myelin oligodendrocyte glycoprotein peptide 35-55 (MOG35-55) in Cd47-/- and wild-type mice.
• In vivo and in vitro assessment of CD4+ T cell activation, proliferation, survival, and integrin (LFA-1, VLA-4) expression and function.
• T cell receptor (TCR) crosslinking and mitogen activation assays were employed.

Main Results:

• Cd47-/- mice confirmed resistance to MOG35-55-induced EAE.
• Contrary to prior reports, CD4+ T cells in immunized Cd47-/- mice were activated but exhibited contracted clonal expansion within 72 hours.
• Naïve Cd47-/- CD4+ T cells showed a premature block in proliferation and survival due to impaired LFA-1 activation, despite intact TCR signaling.

Conclusions:

• CD47 is essential for regulating LFA-1 and VLA-4 integrin-dependent functions in T cell proliferation and recruitment.
• The resistance of Cd47-/- mice to MOG35-55-induced EAE is mediated by impaired T cell proliferation and survival, not a complete failure of T cell activation.
• These findings clarify the role of CD47 in T cell responses and EAE pathogenesis.