The Therapeutic Effect of Tacrolimus in a Mouse Psoriatic Model is Associated with the Induction of Myeloid-derived Suppressor Cells.

Objectives: Topical administration of Tacrolimus (TAC) is efective in the treatment of psoriasis in human patients and in mouse models. Previously, we showed that, though promoting the proliferative expansion of CD4+Foxp3+ regulatory T cells (Tregs), TNFR2 was protective in mouse psoriasis model. We thus examined the role of TNFR2 signal in the efect of TAC in the treatment of mouse psoriasis. Methods: To this end, psoriasis was induced in WT, or TNFR1 KO, or TNFR2 KO mice, and the psoriatic mice were treated with or without IMQ. Results: The results showed that TAC treatment potently inhibited the development of psoriasis in WT and TNFR1 KO mice, but not in TNFR2 KO mice. However, the treatment of TAC failed to induce the expansion of Tregs in psoriatic mice. In addition to playing a decisive role in the activation of Tregs, TNFR2 stimulates the generation and activation of myeloid-derived suppressor cells (MDSCs). This led us to found that the topical treatment with TAC markedly increased the number of MDSCs in the spleen of WT and TNFR1 KO mice, but not in TNFR2 KO mice. Consequently, TAC potently decreased serum levels of IL-17A, INF-γ, and TNF and their mRNA levels in the inflamed skin lesion. Conclusion: Therefore, our study for the first time found that the therapeutic efect of TAC in psoriasis is associated with the expansion of MDSCs in a TNFR2-dependent manner.

Enhanced Microglia Activation and Glioma Tumor Progression by Inflammagen Priming in Mice with Tumor Necrosis Factor Receptor Type 2 Deficiency.

Despite the fact that accumulation of microglia, the resident macrophages of the central nervous system (CNS) are the main feature of glioblastoma, the role of microglia in the progression of glioma is still arguable. Based on the correlation of inflammation with tumor progression, in this study, we attempt to determine if peripheral inflammation aggravates glioma expansion and the activation of microglia associated with the tumor. Experimental animals were administered intraperitoneally by inflammagen lipopolysaccharide (LPS) for 7 days (LPS priming) before intracerebral implantation of glioma cells. Moreover, a reduced level of tumor necrosis factor receptor type 2 (TNFR2) that is restricted to immune cells, neurons, and microglia has been found in patients with glioblastoma through the clinic analysis of monocyte receptor expression. Thus, in addition to wildtype (WT) mice, heterogeneous TNFR2 gene deficiency (TNFR2+/-) mice and homogeneous TNFR2 gene knockout (TNFR2-/-) mice were used in this study. The results show that peripheral challenge by LPS, Iba1+- or CD11b+-microglia increase in numbers in the cortex and hippocampus of TNFR2-/- mice, when compared to WT or TNFR2+/- mice. We further conducted the intracerebral implantation of rodent glioma cells into the animals and found that the volumes of tumors formed by rat C6 glioma cells or mouse GL261 glioma cells were significantly larger in the cortex of TNFR2-/- mice when compared to that measured in LPS-primed WT or LPS-primed TNFR2+/- mice. Ki67+-cells were exclusively clustered in the tumor of LPS-primed TNFR2-/- mice. Microglia were also extensively accumulated in the tumor formed in LPS-primed TNFR2-/- mice. Accordingly, our findings demonstrate that aggravation of microglia activation by peripheral inflammatory challenge and a loss of TNFR2 function might lead to the promotion of glioma growth.

Accumulation of TNFR2-expressing regulatory T cells in malignant pleural effusion of lung cancer patients is associated with poor prognosis.

BACKGROUND: Regulatory T cells (Tregs) may represent a major cellular mechanism in immune suppression by dampening the anti-tumor response in malignant pleural effusion (MPE). Tumor necrosis factor receptor type II (TNFR2) has emerged as a novel identification for the maximally suppressive subset of Tregs in the tumor environment. At present, the significance of TNFR2 expression on Tregs in MPE remains unclear. METHODS: The distribution of TNFR2+cells in Tregs and effector T cells (Teffs) in MPE, peripheral blood (PB), and tuberculosis pleural effusion (TPE) were determined. The associations between TNFR2+Tregs frequencies present in MPE and the clinical and laboratorial characteristics of patients with lung cancer were investigated. The immunosuppressive phenotype of TNFR2+Tregs in MPE was analyzed. The effects of the TNF-TNFR2 interaction on the immunosuppressive function of Tregs was explored. The efficacy of targeting TNFR2 for MPE therapy was examined. The source of TNF in MPE was identified. RESULTS: We observed that markedly higher levels of TNFR2 were expressed in MPE Tregs compared with the levels expressed in MPE Teffs, PB Tregs, or in TPE Tregs. The frequencies of TNFR2+Tregs were positively correlated with the number of tumor cells in MPE, as well as the volume of MPE. High frequencies of TNFR2+Tregs in MPE indicated short survival time and poor performance status for MPE patients. Compared to TNFR2-Tregs, TNFR2+Tregs expressed higher levels of immunosuppressive molecules cytotoxic T lymphocyte-associated protein 4 (CTLA-4), programmed cell death-ligand 1 (PD-L1), and replicating marker Ki-67. Consequently, the proportions of interferon gamma (IFN-γ)-producing cytotoxic T lymphocytes (CTLs) were significantly increased after TNFR2 blockade. Furthermore, tumor necrosis factor (TNF), through interaction with TNFR2, enhanced the suppressive capacity of Tregs by up-regulating CTLA-4 and PD-L1 expression. Interestingly, T helper 1 (Th1) and T helper 17 (Th17) cells are the major source of TNF in MPE, suggesting that MPE Teffs may paradoxically promote tumor growth by boosting MPE Treg activity via the TNF-TNFR2 pathway. CONCLUSIONS: Our data expanded the immunosuppressive mechanism present in MPE induced by Tregs, and provides novel insight for the diagnosis, disease evaluation, and treatment of MPE patients.

TNFR2-expressing CD4+Foxp3+ regulatory T cells in cancer immunology and immunotherapy.

CD4+Foxp3+ regulatory T cells (Tregs) represent a major cellular mechanism in tumor immune evasion. Elimination of Treg activity has become a strategy to devise an effective tumor immunotherapy. We reported that TNF receptor type II (TNFR2), one of two receptors transducing TNF biological activity, is preferentially expressed by the most suppressive subset of Tregs. By interaction with TNFR2, TNF plays a decisive role in the activation, expansion and phenotype stability of Tregs. We also found that highly suppressive TNFR2-expressing Tregs appear to be tumor-associated Tregs. This finding has been supported by recent studies in mouse tumor models and in cancer patients. In this chapter, published data revealing the important role of TNFR2+ Tregs in tumor development and metastasis in different tumor types are reviewed and analyzed. The therapeutic potential of targeting TNF-TNFR2 interaction as means to eliminate Treg activity, and consequently to enhance anti-tumor immune responses, also is discussed.

Tumor necrosis factor-alpha and Fas/Fas ligand signaling pathways in chronic spontaneous urticaria.

BACKGROUND: There is increasing evidence pointing to the important role of tumor necrosis factor-alpha (TNF-α), a key inflammatory and apoptotic mediator in urticarial inflammation. However, the role of the TNF-α system and Fas/Fas ligand (FasL) in the apoptosis-inducing pathways in chronic spontaneous urticaria (CSU), remain unclear. AIM: To determine circulating concentrations of TNF-α, soluble TNF-α receptor type 1 and type 2 (sTNF-R1 and sTNF-R2, respectively) as well as soluble Fas (sFas) and FasL (sFasL) in CSU subjects. METHODS: Serum TNF-α, sTNF-R1, sTNF-R2, sFas, sFasL concentrations were measured using enzyme-linked immunosorbent assay in CSU subjects and in the healthy subjects. RESULTS: TNF-α concentrations were significantly higher in CSU subjects and moderate-to-severe CSU than in the controls, while there were no significant differences in TNF-α concentrations between subjects with mild CSU and the controls. sTNF-R1 and sTNF-R2 concentrations were significantly higher in all CSU and moderate-severe CSU subjects vs. the controls. Serum concentrations were also significantly higher in mild CSU vs. the controls, but not in moderate-severe CSU vs. mild CSU. No significant differences were observed in sFas and sFasL concentrations between CSU subjects and the healthy controls. Significant correlations were found between concentrations of TNF-α and its receptors, as well as sTNF-R1 and sTNF-R2, but not with the urticaria activity score (UAS). There was no relationship between TNF-α/sTNF-R1/sTNF-R2 and sFas/sFasL pathways in CSU. CONCLUSIONS: CSU is associated with the activation of the TNF-α/receptors signaling pathway, marked by increased circulating concentrations of TNF-α, sTNF-R1 and sTNF-R2, which are related to each other in this disease. In contrast, the circulating sFas/FasL system is not up-regulated in CSU, and sFas/sFasL may not be a useful marker of the activity/severity of urticarial processes. Considering the lack of significant changes in sFas/sFasL (mainly reflecting systemic apoptosis) in CSU patients, it appears that elevated serum TNF-α concentrations are related to its pro-inflammatory function rather than an enhanced systemic apoptotic response in CSU.