LF 15-0195 immunosuppressive agent enhances activation-induced T-cell death by facilitating caspase-8 and caspase-10 activation at the DISC level

Abstract

The deoxyspergualin derivative LF 15-0195 has demonstrated some efficacy in animal models of autoimmune and graftversus-host diseases and is currently tested in clinics. The molecular mechanisms of LF 15-0195 immunosuppressive activity remained unknown. We show that exposure to LF 15-0195 sensitizes Jurkat T cells to apoptosis induced by an agonistic anti-CD95 antibody (CH11 clone) and by the cytokine TNF-related apoptosisinducing ligand. LF 15-0195 does not demonstrate any significant effect on the postmitochondrial activation of caspases, nor does it modify overall expression of CD95, Fas-associated death domain, and procaspase-8. The compound facilitates the recruitment of these molecules to the death-inducing signaling complex (DISC) and enhances caspase-8 and -10 activation, thus increasing cytochrome c and direct IAP binding with low pI (DIABLO)/ Smac mitochondrial release. LF 15-0195 also sensitizes Jurkat T cells to CD3-mediated apoptosis, an in vitro model for activation-induced T-cell death (AICD). LF 15-0195-mediated sensitization to AICD was further confirmed in human peripheral T cells exposed to anti-CD3 antibodies, then cultured in the presence of interleukin-2. In these cells, LF 15-0195 increased apoptosis triggered by either anti-CD95 antibodies or CD3 restimulation, whereas no effect was observed on "passive apoptosis." Finally, in bone marrow recipient mice, LF 15-0195 enhanced allogeneic donor T-cell death, which required a functional CD95 pathway. These results suggest that LF 15-0195 sensitizes T cells to AICD by increasing caspase activation at the DISC level in response to CD95 engagement. This original mechanism, together with LF 15-0195 efficacy in various disease models, makes this compound a promising immunosuppressive drug. Introduction 15-deoxyspergualin is an antibiotic that possesses both antitumor 1 and immunosuppressive 2 activities. This compound was shown to bind specifically to the constitutively expressed cytosolic heat shock protein (Hsp) Hsc70 as well as the Hsp90 family of proteins and to inhibit their ATPase activity. [3][4][5] Although it has proven effectiveness in the prevention and treatment of transplant rejection, the clinical use of 15-deoxyspergualin has been limited by its toxicity. 6 Several analogs were obtained recently through organic synthesis. 7,8 One of these compounds, designated LF 15-0195, has demonstrated its efficacy in preventing graft-versus-host disease 8 and in treating collagen type II-induced arthritis 9,10 in mice models. Although LF 15-0195 is now tested in human clinics, the molecular mechanisms of its immunosuppressive activity differ from currently used immunosuppressive agents but remain poorly understood.Mature peripheral T cells can be deleted by a so-called "passive apoptosis." 11 It occurs in T lymphocytes that are not sufficiently stimulated by growth factors. 12,13 T cells are also capable of undergoing a unique form of cell death called activation-induced cell death (AICD). [14][15][16][17] This cell death results from repeated an...

Induction of T Regulatory Cells Attenuates Idiopathic Nephrotic Syndrome

“…15,28 LF15-0195 can also sensitize cells to activation-induced cell death by a Fas-dependent mechanism that triggers the activation of caspases. 33 One of our initial hypotheses concerning this model was that LF15-0195 acts via the inhibition of NF-B activation in glomerular epithelial cells to modify the pathway of a putative nephrotoxic factor. This hypothesis was supported by the observation of an increase in NF-B expression in kidney biopsies of patients with INS recurrence.…”

“…Alternatively, LF15-0195 could sensitize cells to activation-induced cell death, thereby providing a model to understand how LF15-0195 can eliminate renal infiltrating cells or other pathologic populations. 33 A recent study showed that the injection of CD34 ϩ stem cells from patients with INS into immunocompromised mice triggered an albuminuria associated with the effacement of podocyte process in these animals. 42 We performed the inverse process of transferring cells with the capacity to block and control such pathogenic cells.…”

Resveratrol-induced Apoptosis Is Associated with Fas Redistribution in the Rafts and the Formation of a Death-inducing Signaling Complex in Colon Cancer Cells

“…In turn, FADD recruits procaspase-8 to form the death-inducing signaling complex (DISC) in which caspase-8 is activated, thus leading to apoptosis (21)(22)(23). We and others (24,25) have shown that the Fas-mediated pathway may contribute, in a ligand-dependent or -independent manner, to the death of cells exposed to various stimuli, including anticancer drugs and immunomodulatory molecules (26). Whether resveratrol-induced apoptosis also implicates death receptors remains a controversial issue (10 -13).…”

LF 15–0195, a novel immunosuppressive agent prevents rejection and induces operational tolerance in a mouse cardiac allograft model

“…This mode of action would prevent NF-B from dissociating from its inhibitor and would sequester it in the cytoplasm to suppress its downstream effects in the nucleus of antigen presenting cells (APCs) and lymphocytes. Furthermore, it has been demonstrated that LF promotes activation-induced cell death (AICD) of T cells, a process that has been linked to the induction of tolerance (26). In addition, we have recently reported that LF significantly reduces the humoral immune response in both allograft and xenograft transplant models (27,28).…”