Signaling Signatures and Functional Properties of Anti-Human CD28 Superagonistic Antibodies (original) (raw)
Related papers
A CD28 superagonistic antibody elicits 2 functionally distinct waves of T cell activation in rats
Journal of Clinical Investigation, 2008
Administration of the CD28 superagonistic antibody JJ316 is an efficient means to treat autoimmune diseases in rats, but the humanized antibody TGN1412 caused devastating side effects in healthy volunteers during a clinical trial. Here we show that JJ316 treatment of rats induced a dramatic redistribution of T lymphocytes from the periphery to the secondary lymphoid organs, resulting in severe T lymphopenia. Live imaging of secondary lymphoid organs revealed that JJ316 administration almost instantaneously (<2 minutes) arrested T cells in situ. This reduction in T cell motility was accompanied by profound cytoskeletal rearrangements and increased cell size. In addition, surface expression of lymphocyte function-associated antigen-1 was enhanced, endothelial differentiation sphingolipid G protein-coupled receptor 1 and L selectin levels were downregulated, and the cells lost their responsiveness to sphingosine 1-phosphate-directed migration. These proadhesive alterations were accompanied by signs of strong activation, including upregulation of CD25, CD69, CD134, and proinflammatory mediators. However, this did not lead to a cytokine storm similar to the clinical trial. While most of the early changes disappeared within 48 hours, we observed that CD4 + CD25 + FoxP3 + regulatory T cells experienced a second phase of activation, which resulted in massive cell enlargement, extensive polarization, and increased motility. These data suggest that CD28 superagonists elicit 2 qualitatively distinct waves of activation.
CD28 superagonists (CD28SAs) are potent T-cell-activating monoclonal antibodies (mAbs). In contrast to their benign behavior and marked therapeutic efficacy as activators of regulatory T (Treg) cells in preclinical rodent models, a phase I trial of the human CD28SA TGN1412 (now called TAB08) in 2006 resulted in a life-threatening cytokine release syndrome (CRS). We studied TAB08-mediated Treg-cell activation in a recently developed in vitro system of human PBMCs, which also reproduces the CRS experienced by the healthy volunteers. We show that just as in rodents, CD28SAs are potent activators and expanders of Treg cells from healthy donors and rheumatoid arthritis patients, even under effective blockade of pro-inflammatory cytokine release by a corticosteroid. Moreover, CD28SA titration identifies a dose range where pro-inflammatory cytokine secretion from conventional T cells is absent while appreciable Treg-cell activation is maintained. Finally, we report that low-dose application of TAB08 to healthy volunteers results in dose-dependent systemic release of the Treg-cell signature cytokine IL-10 in the absence of the pro-inflammatory factors associated with the CRS of the 2006 TGN1412 study. These results demonstrate the potential of appropriately dosed CD28SA and corticosteroid comedication to mobilize human Treg cells for the treatment of autoimmune and inflammatory conditions. Keywords: CD28 r Regulatory T cells r Rheumatoid arthritis r TAB08 r TGN142 Additional supporting information may be found in the online version of this article at the publisher's web-site Abbreviations: CD28SA: CD28 superagonist · CRS: cytokine-release syndrome · EM: effector memory · FIH: first in human · HD: high density · HV: healthy volunteer · MP: methylprednisolone · RA: rheumatoid arthritis · Tconv: conventional T
Rapid Regulatory T-Cell Response Prevents Cytokine Storm in CD28 Superagonist Treated Mice
PLoS ONE, 2009
Superagonistic CD28-specific monoclonal antibodies (CD28SA) are highly effective activators of regulatory T-cells (Treg cells) in rats, but a first-in-man trial of the human CD28SA TGN1412 resulted in an unexpected cytokine release syndrome. Using a novel mouse anti-mouse CD28SA, we re-investigate the relationship between Treg activation and systemic cytokine release. Treg activation by CD28SA was highly efficient but depended on paracrine IL-2 from CD28SA-stimulated conventional Tcells. Systemic cytokine levels were innocuous, but depletion of Treg cells prior to CD28SA stimulation led to systemic release of proinflammatory cytokines, indicating that in rodents, Treg cells effectively suppress the inflammatory response. Since the human volunteers of the TGN1412 study were not protected by this mechanism, we also tested whether corticosteroid prophylaxis would be compatible with CD28SA induced Treg activation. We show that neither the expansion nor the functional activation of Treg cells is affected by high-dose dexamethasone sufficient to control systemic cytokine release. Our findings warn that preclinical testing of activating biologicals in rodents may miss cytokine release syndromes due to the rapid and efficacious response of the rodent Treg compartment, and suggest that polyclonal Treg activation is feasible in the presence of antiphlogistic corticosteroid prophylaxis.
Human-like Response of Pig T Cells to Superagonistic Anti-CD28 Monoclonal Antibodies
The Journal of Immunology, 2021
Because of its size, anatomical similarities, and now also accessibility to genetic manipulations, pigs are used as animal models for human diseases and immune system development. However, expression and function of CD28, the most important costimulatory receptor expressed by T cells, so far is poorly understood in this species. Using a newly generated mAb (mAb 3D11) with specificity for pig CD28, we detected CD28 on CD8+ and CD4+ αβ T cells. Among γδ T cells, CD28 expression was restricted to a small CD2+ subpopulation of phenotypically naive cells. Functionally, CD28 ligation with mAb 3D11-costimulated porcine T cells, enhanced proliferation and cytokine secretion in vitro. We used a second, likewise newly generated but superagonistic, anti-CD28 mAb (CD28-SA; mAb 4D12) to test the function of CD28 on porcine T cells in a pilot study in vivo. Injection of the CD28-SA into pigs in vivo showed a very similar dose-response relationship as in humans (i.e., 100 µg/kg body weight [BW]) o...
IL-2-Independent Activation and Proliferation in Human T Cells Induced by CD28
The Journal of Immunology
Although the role of CD28 in T cell costimulation is firmly established, the mechanisms by which it exerts its costimulatory actions are less clear. In many circumstances it is difficult to distinguish the effects of CD28 from subsequent actions of cytokines, such as IL-2, on T cell proliferation. Here, we report a model of CD28 costimulation using PMA plus the natural ligand CD80 that resulted in very limited stimulation of IL-2, as evidenced by both cytokine production and IL-2 promoter stimulation. Promoter assays revealed CD28-dependent effects on both NF-κB and AP-1, but not on NF-AT or the intact IL-2 promoter. In addition, T cell proliferation was completely resistant to the actions of the immunosuppressant cyclosporin A (CsA). Moreover T cell proliferation was unaffected by the addition of blocking Abs to both IL-2 and the IL-2 receptor, demonstrating that this form of costimulation by CD28 was independent of IL-2. We also investigated the effects of stimulating T cell blast...
Vaccine, 2007
We consider essential, still ignored, basic research aspects of the failed clinical trial (13 March 2006) of a recombinantly expressed humanised superagonist anti-CD28 mAb, TGN14122. Without hindsight, if for approval of the first ever recombinantly expressed anti-CD28 mAb use in humans attention had been paid to the physico-chemical factors and receptor saturation, the possible catastrophe will have been predictable and preventable. To understand what went wrong and, crucially, to prevent any future disasters to safeguard human health, safety and welfare, the information provided is likely to be of wide interest.
Antagonist Anti-CD28 Therapeutics for the Treatment of Autoimmune Disorders
Antibodies
The effector functions of T lymphocytes are responsible for most autoimmune disorders and act by directly damaging tissues or by indirectly promoting inflammation and antibody responses. Co-stimulatory and co-inhibitory T cell receptor molecules are the primary pharmacological targets that enable interference with immune-mediated diseases. Among these, selective CD28 antagonists have drawn special interest, since they tip the co-stimulation/co-inhibition balance towards efficiently inhibiting effector T cells while promoting suppression by pre-existing regulatory T-cells. After having demonstrated outstanding therapeutic efficacy in multiple models of autoimmunity, inflammation and transplantation, and safety in phase-I studies in humans, selective CD28 antagonists are currently in early clinical development for the treatment of systemic lupus erythematous and rheumatoid arthritis. Here, we review the available proof of concept studies for CD28 antagonists in autoimmunity, with a special focus on the mechanisms of action.
European Journal of Immunology, 2008
Co-stimulatory signals are important for development of effector and regulatory T cells. In this case, CD28 signaling is usually considered inert in the absence of signaling through the TCR. By contrast, mitogenic rat CD28 mAbs reportedly expand regulatory T cells without TCR stimulation. We found that a commercially available human CD28 mAb (ANC28) stimulated PBMCs without TCR co-ligation or cross-linking; ANC28 selectively expanded CD4 + CD25 + FoxP3 − (T effector) and CD4 + CD25 + FoxP3 + (T reg) cells. ANC28 stimulated the CD45RO + CD4 + (memory) population whereas CD45RA + CD4 + (naïve) cells did not respond. ANC28 also induced inflammatory cytokines. Treg induced by ANC28 retain the Treg phenotype longer than did costimulated Treg. Treg induced by ANC28 suppressed CD25 − T cells through a contact-dependent mechanism. Purity influenced the response of CD4 + CD25 + cells because bead-purified CD4 + CD25 + cells (85-90% pure) responded strongly to ANC28, whereas 98% pure FACS-sorted CD4 + CD25 bright (T-reg) did not respond. Purified CD4 + CD25 int cells responded similarly to the bead-purified CD4 + CD25 + cells. Thus, pre-activated CD4 + T cells (CD25 int) respond to ANC28 rather than Treg (CD25 bright). The ability of ANC28 to expand both effectors producing inflammatory cytokines as well as suppressive regulatory T cells might be useful for ex vivo expansion of therapeutic T cells.