Inhibition of T Helper Cell Differentiation by Tacrolimus or Sirolimus Results in Reduced B-Cell Activation: Effects on T Follicular Helper Cells

The effect of immunosuppressive drugs on the generation of T follicular helper (Tfh) cells, specialized in supporting B-cell differentiation, is largely unknown. We examined whether the calcineurin inhibitor tacrolimus (TAC) and the mammalian target of rapamycin (mtor) inhibitor sirolimus (SRL) inhibit Tfh cell differentiation, and affect subsequent B-cell functions. Isolated naive T cells were polarized into Tfh-like cells in the presence of TAC or SRL. To demonstrate their functionality, we co-cultured these cells with isolated B cells in the presence of alloantigen and studied the activation and differentiation of these B cells. Tfh-like cells were defined as CD4+CXCR5+ T cells, expressing immunoinhibitory programmed death protein 1 (pd1) and inducible T-cell costimulator (icos). We found that TAC and SRL significantly inhibited Tfh-like cell differentiation. Therapeutic concentrations of TAC and SRL reduced the percentage of pd1+ and icos+ Tfh cells compared to controls. In addition, T cells grown in the presence of TAC or SRL expressed less IL-21 and provided less B-cell help. TAC and SRL both inhibited Tfh-dependent alloantigen-activated B-cell proliferation and differentiation into plasma cells and transitional B cells. In conclusion, TAC and SRL inhibited the differentiation of naive T cells into functional Tfh-like cells, a finding that can be extrapolated to immunosuppressive regimens in transplant patients

Adipose Tissue-Derived Mesenchymal Stem Cells Have a Heterogenic Cytokine Secretion Profile

textabstractMesenchymal stem cells derived from adipose tissue (ASC) have immune regulatory function, which makes them interesting candidates for cellular therapy. ASC cultures are however heterogeneous in phenotype. It is unclear whether all ASC contribute equally to immunomodulatory processes. ASC are also responsive to cytokine stimulation, which may affect the ratio between more and less potent ASC populations. In the present study, we determined IL-6 receptor (CD126 and CD130 subunits) and IFN-γ receptor (CD119) expression on ASC by flow cytometry. The production of IL-6 and IFN-γ was measured by ELISA and the frequency of IL-6 and IFN-γ secreting cells by ELISPOT. The results showed that ASC did not express CD126, and only 10-20% of ASC expressed CD130 on their surface, whereas 18-31% of ASC expressed CD119. ASC produced high levels of IL-6 and 100% of ASC were capable of secreting IL-6. Stimulation by IFN-γ or TGF-β had no effect on IL-6 secretion by ASC. IFN-γ was produced by only 1.4% of ASC, and TGF-β significantly increased the frequency to 2.7%. These results demonstrate that ASC cultures are heterogeneous in their cytokine secretion and receptor expression profiles. This knowledge can be employed for selection of potent, cytokine-producing, or responsive ASC subsets for cellular immunotherapy

T follicular helper cells as a new target for immunosuppressive therapies

Over the past decade, antibody-mediated (humoral) rejection has been recognized as a common cause of graft dysfunction after organ transplantation and an important determinant for graft loss. In humoral alloimmunity, T follicular helper (Tfh) cells play a crucial role, because they help naïve B cells to differentiate into memory B cells and alloantibody-producing plasma cells within germinal centers. In this way, they contribute to the induction of donor-specific antibodies, which are responsible for the humoral immune response to the allograft. In this article, we provide an overview of the current knowledge on the effects of immunosuppressive therapies on Tfh cell development and function, and discuss possible new approaches to influence the activity of Tfh cells. In addition, we discuss the potential use of Tfh cells as a pharmacodynamic biomarker to improve alloimmune-risk stratification and tailoring of immunosuppression to individualize therapy after transplantation

Representative Immunohistochemical results of PD-L1/PTEN for patients with and without metastatic progression.

<p>(<b>A₁, A₂, E₁, E₂</b>) Negative control; (<b>B₁, B₂, F₁, F₂</b>) Specimens from the same patient with metastatic progression; (<b>C₁, C₂, G₁, G₂</b>) Specimens from another patient without metastatic progression; (<b>D₁, D₂</b>) A typical representative which showed that PD-L1 expression is elevated in the tumor area (T) compared with those of adjacent normal mucosa (N); (<b>H₁, H₂</b>) Specimens from patient without any PTEN expression; (<b>J, K</b>) Statistical analysis demonstrated that PD-L1 expression is increased in the patients with metastatic progression compared with those without metastatic progression, while such statistical analysis of PTEN wasn’t significant. (Two up panels, stained with PD-L1 antibody; two down panels, stained with PTEN antibody), (A₁–H₁, ×100; A₂–H₂, ×400).</p

Correlation between PD-L1 expression and clinical parameters in 347 colorectal cancer patients.

<p>Note: Data of PD-L1 expression are described with median (P25, P75). Wilcoxon rank sum test (Kruskal-Wallis test) for all analysis.</p

Effect of IFN-γ and PTEN loss on the expression of PD-L1 protein.

<p>PD-L1 protein expression level on the surface of SW480, SW620 and HCT116 was determined by flow cytometer: cells transfected with siRNA PTEN (red lines) and cells transfected with non-specific sequences (blue lines) in the absence of IFN-γ; cells transfected with siRNA PTEN (black lines) and cells transfected with non-specific sequences (orange lines) in the presence of IFN-γ; cells stained with isotype-matched control antibody (shaded area). Standard fluorescence intensity of PD-L1 protein was described by histogram in right panel: cells treated (white column) or untreated (gray column) with IFN-γ. Data were collected from three independent experiments. Error bars represent SD. (*P<0.05 by paired-samples <i>t</i> test).</p