Abstract 4600: Potent and selective C-C chemokine receptor (CCR4) antagonists potentiate anti-tumor immune responses by inhibiting regulatory T cells (Treg)

Abstract Myeloid antigen-presenting cells (APCs), regulatory cells, and the HLA-G molecule are involved in modulating immune responses and promoting tolerance. APCs are known to induce regulatory cells and to express HLA-G as well as 2 of its receptors; regulatory T cells can express and act through HLA-G; and HLA-G has been directly involved in the generation of regulatory cells. Thus, interplay(s) among HLA-G, APCs, and regulatory cells can be easily envisaged. However, despite a large body of evidence on the tolerogenic properties of HLA-G, APCs, and regulatory cells, little is known on how these tolerogenic players cooperate. In this review, we first focus on key aspects of the individual relationships between HLA-G, myeloid APCs, and regulatory cells. In its second part, we highlight recent work that gathers individual effects and demonstrates how intertwined the HLA-G/myeloid APCs/regulatory cell relationship is.

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Mesenchymal stem cells induce the expansion of regulatory T cells in abortion-prone mice

Reproduction ◽

10.1530/rep-20-0320 ◽

2021 ◽

Author(s):

Amir Salek Farrokhi ◽

Amir-Hassan Zarnani ◽

Fatemeh Rezaei kahmini ◽

Seyed Mohammad Moazzeni

Keyword(s):

Stem Cells ◽

T Cells ◽

Mesenchymal Stem Cells ◽

Regulatory T Cells ◽

Immune Responses ◽

Lymph Nodes ◽

De Novo ◽

Abortion Rate ◽

Cellular Mechanisms ◽

Inguinal Lymph Nodes

Recurrent pregnancy loss (RPL) is one of the most common complications of early pregnancy associated in most cases with local or systemic immune abnormalities such as the diminished proportion of regulatory T cells (Tregs). Mesenchymal stem cells (MSCs) have been shown to modulate immune responses by de novo induction and expansion of Tregs. In this study, we analyzed the molecular and cellular mechanisms involved in Treg-associated pregnancy protection following MSCs administration in an abortion-prone mouse mating. In a case-control study, syngeneic abdominal fat-derived MSCs were administered intraperitoneally (i.p) to the DBA/2-mated CBA/J female mice on day 4.5 of pregnancy. Abortion rate, Tregs proportion in spleen and inguinal lymph nodes, and Ho1, Foxp3, Pd1, and Ctla4 genes expression at the feto-maternal interface were then measured on day 13.5 of pregnancy using flow cytometry and quantitative RT- PCR, respectively. The abortion rate in MSCs-treated mice was significantly reduced and normalized to the level observed in normal pregnant animals. We demonstrated a significant induction of Tregs in inguinal lymph nodes but not in the spleen following MSCs administration. Administration of MSCs remarkably upregulated the expression of HO1, Foxp3, Pd1, and Ctla4 genes in both placenta and decidua. Here, we show that MSCs therapy could protect the fetus in the abortion-prone mice through Tregs expansion and up-regulation of Treg-related genes. These events could establish an immune-privileged microenvironment, which participates in regulation of detrimental maternal immune responses against the semi-allogeneic fetus.

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