Monoclonal Antibody Targeting the CD154 Cleavage Site Inhibits CD40-Dependent and -Independent Cleavage of CD154 from the Cell Surface

Abstract

In addition to the membrane-bound molecule, soluble CD154 (sCD154) is also detected at high levels in the medium of activated T cells and platelets and in the serum of patients suffering from different inflammatory diseases. This sCD154 is the result of cleavage of the full-length molecule between the glutamic acid residue at position 112 (E112) and methionine at position 113 (M113) and can be derived from the intracellular milieu and from cleavage of cell surface molecules. We have recently reported that substitution of both E112 and M113 by alanine inhibits intracellular and CD40-induced membrane cleavage of CD154 and procures to CD154 an increased biological function as compared with cleavable CD154. Thus, in this study, and in the aim of developing tools inhibiting cleavage of CD154 from the cell surface, we generated a panel of anti-human CD154 mAbs. One of the derived mAbs that did not alter the binding of sCD154 to CD40, named in this study Clone 8 mAb, totally lost its binding activity against cells expressing CD154 mutated at its E112 and M113 residues. Treatment with Clone 8 mAb was shown to completely abolish CD40-dependent and -independent cleavage of CD154 from the cell surface. Our study is highlighting the development and characterization of an innovative therapeutic tool capable of inhibiting the release/cleavage of CD154 from cells and thus maintaining its availability on the cell surface and the high probably of increasing its potency as an activator of CD40-induced responses. ImmunoHorizons, 2021, 5: 590-601.

Novel Functions of Integrins as Receptors of CD154: Their Role in Inflammation and Apoptosis

“…Intracellular and membrane-bound CD154 (mCD154) molecules are prone to cleavage, releasing a soluble form involving residues 113-261, which is biologically active (trimeric) [ 20 ]. Studies by various groups, including ours, have demonstrated that soluble CD154 (sCD154) is released from activated platelets and T cells by proteolytic cleavage at its methionine residue at position 113 (M113), mediated by various members of the metalloproteinases family and initiated by the interaction of the ligand with CD40 in cleavage from T-cell surface ( Figure 1 ) and/or with αIIbβ3 in platelets cleavage [ 20 , 21 , 22 , 23 , 24 , 25 ]. Although the physiological role of sCD154 in vivo remains unclear, increased levels were reported in many inflammatory disorders [ 26 , 27 , 28 ].…”