In vitro TNF blockade enhances ex vivo expansion of regulatory T cells in patients with immune thrombocytopenia

Abstract

Summary Tumour necrosis factor-α (TNF) is an inflammatory cytokine that is elevated in a number of autoimmune diseases including immune thrombocytopenia (ITP), a bleeding disorder characterized by low platelet counts. In vitro TNF blockade increases expansion of the regulatory T cell (Treg) IKZF2 (also termed Helios) subset in T cell-monocyte cocultures from healthy donors, but its role on proliferative responses of Tregs in ITP patients, who have altered immunoregulatory compartment, remains unclear. TNF in CD4+ T cells from patients with chronic ITP were elevated and negatively correlated with peripheral Treg frequencies, suggesting a possible inhibitory effect of TNF on ITP Tregs. In vitro antibody neutralization with anti-TNF in T cell-monocyte cocultures resulted in a robust expansion of pre-existing ITP Tregs, higher than in healthy controls. Similar to the effects of anti-TNF antibodies, TNF blockade with antibodies against TNFRSF1B (anti-TNFRSF1B, previously termed anti-TNFRII) almost doubled ITP Treg expansion whereas neutralization with anti-TNFRSF1A (anti-TNFRI) antibodies had no effect on proliferative responses of Tregs. In addition, TNFRSF1B levels on ITP Tregs were significantly elevated, which may explain the increased susceptibility of patient Tregs to the actions of TNF blockade. Altogether, these data raise the possibility that TNF blockers, through their ability to increase Treg proliferation, may be efficacious in ITP patients.

Abnormal Distribution and Function of Monocyte Subsets in Patients With Primary Immune Thrombocytopenia

“…31 Additionally, TNF blockers may be effective in the treatment of patients with ITP by increasing Treg proliferation. 32 Consistent with the results in RA reported by Cros et al 33 and Rossol et al, 26 we identified that the intermediate subset produces the highest level of TNF-a and IL-1b among the 3 subsets in patients with active ITP. After CR, the TNF-a secretion decreased rapidly, which suggests that the intermediate subset participates in the pathogenesis of ITP through an increased capability for cytokine secretion.…”

Effects of rituximab and dexamethasone on regulatory and proinflammatory B‐cell subsets in patients with primary immune thrombocytopenia

“…Thus, the increase in IL‐10 + B cells as well as CD5 + B cells, which may represent overlapping subsets, is compatible with induction of Tregs. It can be speculated that the increase in IL‐6 + B cells after RTX+DXM treatment may support Treg development indirectly through downregulation of TNF that would otherwise inhibit Treg expansion …”

“…It can be speculated that the increase in IL-6 + B cells after RTX+DXM treatment may support Treg development indirectly through downregulation of TNF 35,36 that would otherwise inhibit Treg expansion. 49 A number of limitations apply to this study: First and foremost, frozen PBMCs were only available from 16 ITP patients. Therefore, the study can only be regarded as explorative.…”

Tumour necrosis factor signalling in health and disease

“…TNF is known to have widespread and profound effects on both the activation and the proliferation of different subsets of immune cells in several disease states. In vitro anti-TNF blockage, used in T-cell monocyte co-cultures of patients with the autoimmune disorder thrombocytopenia, produced a robust proliferation of the immunomodulatory regulatory T (Treg) cells 71 ; interestingly, this Treg cell expansion was dependent on TNFR2 and not TNFR1. Blockage of TNFR2 resulted in a robust expansion of Treg cells, whereas neutralisation of TNFR1 had no effect on this Treg cell expansion 71 .…”