A non-conserved amino acid variant regulates differential signalling between human and mouse CD28

Nicla Porciello,Marta Mastrogiovanni,Paola Grazioli,Aldo Borroto,Balbino Alarcon,Francesca Spadaro,Loretta Tuosto,Martina Kunkl,Isabella Screpanti,Antonio F Campese,Cédric Favre,Silvana Caristi,Michela Muscolini,Jacques A Nunès

doi:10.1038/s41467-018-03385-8

Abstract

CD28 superagonistic antibodies (CD28SAb) can preferentially activate and expand immunosuppressive regulatory T cells (Treg) in mice. However, pre-clinical trials assessing CD28SAbs for the therapy of autoimmune diseases reveal severe systemic inflammatory response syndrome in humans, thereby implying the existence of distinct signalling abilities between human and mouse CD28. Here, we show that a single amino acid variant within the C-terminal proline-rich motif of human and mouse CD28 (P212 in human vs. A210 in mouse) regulates CD28-induced NF-κB activation and pro-inflammatory cytokine gene expression. Moreover, this Y209APP212 sequence in humans is crucial for the association of CD28 with the Nck adaptor protein for actin cytoskeleton reorganisation events necessary for CD28 autonomous signalling. This study thus unveils different outcomes between human and mouse CD28 signalling to underscore the importance of species difference when transferring results from preclinical models to the bedside.

Highlights

CD28 superagonistic antibodies (CD28SAb) can preferentially activate and expand immunosuppressive regulatory T cells (Treg) in mice
During T: antigen presenting cell (APC) encounter, CD28 binds to B7.1/ CD80-expressing cells (B7).1/CD80 and/or B7.2/CD86 co-stimulatory molecules, expressed on the surface of APCs, enhancing the close contact between T cells and APCs and mediating the actin cytoskeleton rearrangement events required for the generation of a dynamic platform at the immunological synapse, where many signalling molecules are recruited and protected from phosphatases[1]
Since its discovery, it has becoming clear that CD28 may function as a T cell receptor (TCR)-independent signalling unit that delivers biochemical signals inducing several gene expression programmes in T lymphocytes

Summary

Introduction

CD28 superagonistic antibodies (CD28SAb) can preferentially activate and expand immunosuppressive regulatory T cells (Treg) in mice. Pre-clinical trials assessing CD28SAbs for the therapy of autoimmune diseases reveal severe systemic inflammatory response syndrome in humans, thereby implying the existence of distinct signalling abilities between human and mouse CD28. We show that a single amino acid variant within the C-terminal proline-rich motif of human and mouse CD28 (P212 in human vs A210 in mouse) regulates CD28-induced NF-κB activation and pro-inflammatory cytokine gene expression. This Y209APP212 sequence in humans is crucial for the association of CD28 with the Nck adaptor protein for actin cytoskeleton reorganisation events necessary for CD28 autonomous signalling. By comparing the sequence of the cytoplasmic tail of CD28 between human and mouse, a single amino acid variant within the C-terminal prolinerich motif was found: P212 in human CD28 (hCD28) (PYAPP212) vs. A210 (PYAPA210) in mouse

Methods

Results

Conclusion