Toll-like receptor agonists partially restore the production of pro-inflammatory cytokines and type I interferon in Sézary syndrome

Abstract

Sézary syndrome (SS) carries a poor prognosis, and infections represent the most frequent cause of death in SS patients. Toll-like receptors (TLRs) are a family of innate immune receptors that induce protective immune responses against infections. We sought to evaluate the ability of TLR agonists to induce inflammatory cytokine, Th2 cytokine, and type I interferon (IFN-I) production by peripheral blood mononuclear cells (PBMC) of untreated SS patients. We detected impaired IL-6, IL-10 and IL-13 secretion by PBMC induced by the agonists for TLR5, TLR3, TLR7 and TLR9 in SS patients, while it was partially recovered by TLR2/TLR4 and TLR7/8 agonists TNF secretion was restored following stimulation with TLR2/TLR4 agonists. IFN-γ was scarcely produced upon TLR activation in SS cells, albeit TLR 7/8 (CL097) enhanced their secretion at lower levels than the control group. TLR9 agonist efficiently induced IFN-I in SS patients, although this positive regulation was not observed for other cytokines, in direct contrast to the broad activity of CL097. Among the TLR agonists, TLR4 was able to induce pro-inflammatory, IL-10 and Th2 secretion, while TLR7-8 agonist induced the inflammatory cytokines, IFN-I and IFN-γ. These findings reveal a dysfunctional cytokine response upon both extracellular and intracellular TLR activation in SS patients, which was partially restored by TLRs agonists.

Profile of differentially expressed Toll-like receptor signaling genes in the natural killer cells of patients with Sézary syndrome

“…Among the TLRs, the most intensively expressed was TLR2, which was possibly a consequence of bacterial infection; this is not surprising considering that sepsis is a common cause of death among SS patients. This aligns with a previous finding that some patients with SS showed up-regulation of TLR2 mRNA expression in unstimulated PBMCs [ 41 ].…”

“…Previously, we verified that TLR ligands have the ability to restore, at least partially, the expression of a broad range of cytokines and type I/III IFN in the PBMCs from SS patients [ 41 ]. We assessed the NK effector molecules, such as degranulating CD107a, IFN-γ and TNF, induced by TLR7/8 stimulation by means of flow cytometry; PMA plus ionomycin was used as a positive control.…”

“…Human NK cells express TLR3, TLR7, and TLR8 [ 53 ]. Previously, we verified that the compound CL097, a TLR7/8 dual agonist, was able to induce type I and II IFNs and other cytokines in the PBMCs of SS patients [ 41 ]. For NK cells, we observed that activation through the TLR7/8 pathway induced mainly degranulating factor CD107a and TNF by CD56 bright NK cells.…”

“…Moreover, interaction of KIR3DL2 with CpG ODN can directly promote malignant cell death in SS [ 40 ]. Previously we observed a dysfunctional cytokine response in the PBMCs of SS patients upon TLR agonists (TLR2-TLR9) stimulation, emphasizing the role of TLR7/8 agonists (CL097), which partially restored inflammatory cytokine and type I and type II interferon (IFN) secretion [ 41 ]. Evaluating the effector response and the differential gene profile in NK cells upon TLR7/8 stimulation on the adaptor and effector molecules and the downstream TLR pathway may lead to the development of novel immunotherapies to enhance immunity in SS patients.…”

Double-positive CD4 and CD8 Sézary syndrome

“…A previous study from our group showed a deficient immune response in patients with SS. 10 The data suggest that double-positive CD4 + CD8 + neoplastic T-cells shows a lower cytotoxic potential compared to CD4 + CD8 – cells.…”