Introduction Exosomes are nanovesicles found in large quantities in biological fluids and tumors of patients with nasopharyngeal carcinoma (NPC). These tumor exosomes play an important role in tumor ...progression due to their immunosuppressive properties. In addition, it has been reported that the frequency and suppressor functions of CD4 + CD25highFOXP3 + CD127low regulatory T cells (Treg) are also higher in NPC patients than healthy donors. Interactions between NPC-derived exosomes and Treg remain unknown. Here we investigated their ability to induce, expand, activate and recruit human Treg. Material and methods Treg recruitment by exosomes derived from NPC cell lines (C15/C17-Exo), exosomes isolated from NPC patients’ plasma (Patient-Exo), and CCL20 was tested in vitro using Boyden chamber assays and in vivo using a xenograft SCID mouse model ( N = 5), both in the presence and absence of anti-CCL20 monoclonal antibodies (mAb). Impact of these NPC exosomes (NPC-Exo) on Treg phenotype and function was determined using adapted assays (FACS, Q-PCR, ELISA and MLR). Experiments were performed in comparison with exosomes derived from plasma of healthy donors (HD-Exo). Results CCL20 allowed the intra-tumoral recruitment of human Treg. NPC-Exo also facilitated Treg recruitment (3.30 ± 0.34-fold increase, P < .001), which was statistically significantly inhibited ( P < .001) by an anti-CCL20 blocking mAb. NPC-Exo also recruited conventional CD4 + CD25- T cells and mediated their conversion into inhibitory CD4 + CD25high cells. Moreover, NPC-Exo statistically significantly enhanced ( P = 0.0048) the expansion of human Treg, inducing the generation of Tim3Low Treg with increased expression of CD25 and FOXP3. Finally, NPC-Exo induced an overexpression of cell markers associated with Treg phenotype, properties and recruitment capacity. For example, GZMB mean fold change was 21.45 ± 1.75. These results were consistent with a stronger suppression of responder cells’ proliferation ( P < .001), and the secretion of immunosuppressive cytokines (IL10, TGFB1). Conclusion Interactions between NPC-Exo and Treg represent a newly defined mechanism that may be involved in regulating peripheral tolerance by tumors and in supporting immune evasion in human NPC.
Abstract Background Inevitable hepatitis C virus (HCV) recurrence after liver transplantation is a major barrier to the survival of a transplanted liver. It may be promoted by immunosuppression and ...the emergence of CD4+ CD25+ regulatory T cells (Treg). Treg cells can mediate the induction and maintenance of immunological self-tolerance as well as transplant tolerance. We investigated the effects of cyclosporine (CsA), a widely used immunosuppressive agent, on human CD4+ CD25+ Treg cells. Methods Human CD4+ CD25+ cells isolated from healthy donors were cultured in the presence of 40 or 400 ng/mL CsA. The suppressive activity of Treg was assessed in mixed leukocyte reactions (MLR) using CD25+ and autologous activated peripheral blood mononuclear cells (PBMC). Phenotype analysis (flow cytometric, Q-PCR) and cytokine production (ELISA) of Treg cells were then performed on cultures. Results CsA (40 or 400 ng/mL) inhibited the proliferative capacity of PBMC and CD4+ CD25+ Treg in a dose-dependent manner. Interestingly, addition of 40 ng/mL CsA in MLR impaired the suppressive activity of CD4+ CD25+ cells, whereas a higher dose of CsA had no effect on Treg function. It appears that a therapeutic dose of CsA (40 ng/mL) did not change the phenotype of CD4+ CD25+ T cells, but altered Treg activity by switching the regulatory to an inflammatory cytokine profile. Conclusion CsA significantly impaired the function of CD4+ CD25+ Treg cells by inducing interleukin-2 (IL-2) and interferon-γ (IFN-γ) secretion. The present studies suggested that CsA may block the induction of immune tolerance and decrease the risk of hepatitis C recurrence.
Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and also the third most common cause of cancer-related death. HCC arises most frequently in males with cirrhosis, which is ...most often a consequence of chronic hepatitis infection (HBV and HCV) or alcohol abuse. To date, the only effective approaches for patients with HCC are resection or liver transplantation. Immunological mechanisms are important in the surveillance of malignancy and control of tumor progression. Tumor-infiltrating lymphocytes (TILs) have been described in HCC, and extensive infiltration has been associated with reduced tumor recurrence following resection. However continued tumor-growth, despite the presence of a lymphocytic infiltration, including tumor-specific T-cells within and surrounding tumors, suggests a failure of immune control. Although, many mechanisms have been proposed for this attenuated immune response, it becomes evident that direct suppression of effector cells, supported by regulatory T-cells could play a pivotal role in the suppression of immune response to tumors. Initially described in context of immune disorders such as inflammatory autoimmune pathologies, regulatory T lymphocytes are characterized by their capacity to inhibit T helper response. To date, several regulatory T-cells are described, however CD4+CD25+ regulatory T-cells and Tr1 subpopulations remain best characterized. Currently, there is no evidence for direct implication of CD4+CD25+ regulatory T-cells in the malignancy and control of HCC progression. However, recent studies showed that both regulatory T-cells subpopulations and particularly Tr1 have been implicated in the modulation of the immune response during HCV chronic infection, supporting HCC progression.
Abstract Background Inevitable hepatitis C virus recurrence after liver transplantation, a major barrier to survival of the transplanted liver may be promoted by immunosuppression and by CD4+ CD25+ ...regulatory T cells (Treg). Treg cells are essential for the induction and maintenance of immunologic self-tolerance as well as transplant tolerance. Moreover, we have previously described low doses of cyclosporine (CsA) to inhibit Treg activity by inducing interleukin-2 and interfron-γ. We investigated here in, the effect of mycophenolate mofetil (MMF) and corticosteroids, usually used in combination with a calcineurin inhibitor on human CD4+ CD25+ Treg cells. Methods Human CD4+ CD25+ cells isolated from healthy donors were cultured in the presence of CsA +/− corticoids or MMF. Suppressive activity of regulatory T cells was assessed in mixed leukocyte reactions including CD25+ solvents with autologous activated peripheral blood mononuclear cells (PBMC). Results MMF and dexamethasone inhibited PBMC and Treg proliferation in dose-dependent fashing, maintaining the suppressive activity of Treg cells. However, the association of corticoids with CsA could not reverse the inhibitory effects of CsA on Treg activity, unlike the MMF and CsA combination. Conclusion We have previously shown CsA to significantly impair the function of CD4+ CD25+ Treg cells. Herein we reports that corticoids were not able to reverse this effect, whereas MMF couterbalanced it, suggesting that the combination of MMF with CsA maintains regulatory T cells activity promoting tolerance.
Summary
We demonstrated here that schistosomal egg antigen (SEA) is able to stimulate an antigen‐specific, cytotoxic CD8+ T‐cell response in mice. Indeed, a single i.p. immunization with SEA resulted ...in the in vivo induction of significant cytotoxic T lymphocyte (CTL) activity in the spleen within 20 days. Effector cells were classic class I major histocompatibility complex (MHC)‐restricted CD8+ lymphocytes producing interferon‐γ (IFN‐γ) and interleukin‐2 (IL‐2), suggesting a type 1 response to SEA. We therefore investigated the relevance of these observations in the context of the Schistosoma mansoni parasite infection. CTL activity against SEA‐pulsed target cells was evidenced throughout the infection after in vitro stimulation of recovered splenic cells with SEA demonstrating that SEA‐specific CD8+ T cells with cytotoxic potentialities are present during infection. This activity was strongly increased after immunization of mice with SEA like the production of IFN‐γ in the sera. A marked reduction in the number of granulomas and of fibrosis with the presence of cells producing IFN‐γ in the liver was also observed leading to the survival of SEA‐immunized mice.
Immune response failure during HCV infection has been associated with the activity of regulatory T cells. Hepatitis C‐related cirrhosis is the main reason for liver transplantation. However, 80% of ...transplanted patients present an accelerated recurrence of the disease. This study assessed the involvement of regulatory T‐cell subsets (CD4+CD25+ cells: ‘Treg’ and CD49b+CD18+ cells: ‘T regulatory‐1’ cells), in the recurrence of HCV after liver transplantation, using transcriptomic analysis, ELISA assays on serum samples and immunohistochemistry on liver biopsies from liver recipients 1 and 5 years after transplantation. Three groups of patients were included: stable HCV‐negative recipients and those with mild and severe hepatitis C recurrence. At 5 years, Treg markers were overexpressed in all HCV+ recipients. By contrast, Tr1 markers were only overexpressed in patients with severe recurrence. At 1 year, a trend toward the overexpression of Tr1 was noted in patients evolving toward severe recurrence. IL‐10 production, a characteristic of the Tr1 subset, was enhanced in severe recurrence at both 1 and 5 years. These results suggest that Tr1 are enhanced during severe HCV recurrence after liver transplantation and could be predictive of HCV recurrence. High levels of IL‐10 at 1 year could be predictive of severe recurrence, and high IL‐10 producers might warrant more intensive management.
This study of regulatory T cell subsets (CD4+CD25+ cells: “Treg” and CD49b+CD18+ cells: “T regulatory‐1” cells) in recurrence of HCV after liver transplantation found that Tr1 are enhanced during severe HCV recurrence.
We have characterized the immunological behaviour of major histocompitibility complex (MHC) Class II molecule‐deficient (Aβ°) mice after infection by Schistosoma mansoni. In Aβ° mice, morbidity ...developed dramatically 7 weeks after infection leading to death, despite the absence of an increase in parasite burden or of eggs trapped in the liver. Histological examination of the liver revealed the absence of a classical granulomatous reaction. Antibodies were produced only against schistosomulum antigens. Specific antibodies against adult worm (SWAP) or egg antigen (SEA) were not detected. Cytokine production (IFN‐γ and IL‐4) was absent after in vitro restimulation of splenic cells from infected Aβ° mice with parasite antigens. Adoptive transfer of primed splenic cells (total, purified CD4+ or CD8+ T cells) failed to improve survival or to induce a granulomatous reaction in infected Aβ° mice. Survival, cellular and humoral responses in CD8+ T‐cell‐depleted Aβ° mice or MHC° mice (lacking MHC class I and II molecules) were similar to nondepleted Aβ° mice, suggesting that anti‐schistosomula antibody production was thymo‐independent. Our results demonstrate a high degree of susceptibility of Aβ° mice to infection and corroborate the importance of CD4+ T cells in the initiation of the granulomatous response. However, our results do not show evidence for the involvement of CD8+ T cells in response to S. mansoni infection.
Liver transplantation is the treatment of end-stage liver diseases, including hepatitis C. Immunosuppression prevents graft rejection but seems to accelerate the recurrence of hepatitis C. Regulatory ...T cells (Tregs) may be beneficial in tolerance but deleterious in recurrent hepatitis C. We evaluated the effects of cyclosporine or tacrolimus, the principal immunosuppressive drugs, on Treg proliferation and function.
Human Tregs were isolated from healthy donors and cultured with cyclosporine, tacrolimus, or NIM811, a cyclosporine analog devoid of calcineurin-inhibiting activity. Treg proliferation and suppressive activity were assessed. The phenotype, cytokine production, and phosphorylation profile of nuclear factor of activated T cell of Tregs were also analyzed.
Cyclosporine and tacrolimus both decreased Treg proliferation, but only low doses of cyclosporine reduced Treg activity, by inducing the production of interleukin 2 proinflammatory cytokines in these cells. Moreover, NIM811 also inhibited Treg activity. The phosphorylation of nuclear factor of activated T cell in Tregs was not altered by cyclosporine, suggesting that the effects of this drug are independent of the calcineurin pathway.
In summary, low doses of cyclosporine inhibit Treg activity, a finding that might explain the beneficial effect of this drug on hepatitis C recurrence. In contrast, by maintaining Treg activity, tacrolimus could be more helpful than cyclosporine in controlling rejection.
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