Myeloid Derived Suppressor Cells as Disease Modulators

Myeloid Derived Suppressor Cells (MDSCs) are a heterogeneous population of immature myeloid cells that can suppress the function of multiple immune cells and in particular, T cells, through various mechanisms. MDSCs can be divided into two major subtypes based on their cell surface phenotype and morphology: polymorphonuclear MDSC (PMN-MDSC or G-MDSC) and monocytic MDSC (M-MDSC). Additional subtypes have been proposed, such as the early MDSC (e-MDSC) that lack both macrophage and granulocyte markers. There is still considerable ambiguity about the phenotype of these cells that corresponds to their immunosuppressive function and there are on-going challenges on how to identify, purify and/or potentially generate and expand these cells in vitro. MDSCs were first discovered in cancer patients where they have been most extensively studied as components of the immunosuppressive tumor microenvironment. In the last several years, however, the importance of their immunomodulatory role in many other disease and clinical settings has emerged.

In this Research Topic, we aim to highlight: (i) the recent advances in our understanding of the roles of MDSCs in pre-malignancy; established tumors and metasteses and (ii) the emerging roles of MDSCs in diseases beyond cancer including obesity, autoimmunity, transplantation and infectious diseases. In addition, we will gather contributions on the current and emerging methodologies for isolation and phenotyping of MDSC to help improve the characterization of MDSC subsets in both normal and pathologic states. In this way, we hope to establish an interface through which investigators studying the diverse roles of MDSCs can bring their latest ideas and research in one place in order to (i) bring increased attention to the less-studied, but likely equally important roles of MDSCs and (ii) foster collaboration between scientists working on MDSCs in different diseases.

We welcome the submission of Original Research, Reviews, Mini-Reviews, Opinion and Perspective articles that address the following sub-topics:

1. The immunobiology of MDSCs including their modulation of immune cell responses.
2. Identification and characterization of MDSC subsets in physiological and pathological conditions.
3. Role of MDSCs in premalignancy, established cancers, tumor angiogenesis and metastases.
4. Role of MDSCs in obesity and metabolism.
5. MDSCs in hematopoietic and solid organ transplantation and related immune tolerance.
6. Role of MDSCs in autoimmunity.
7. Role of MDSCs in chronic infectious diseases (bacterial, parasitic and viral).

We acknowledge the initiation and support of this Research Topic by the International Union of Immunological Societies (IUIS). We hereby state publicly that the IUIS has had no editorial input in articles included in this Research Topic, thus ensuring that all aspects of this Research Topic are evaluated objectively, unbiased by any specific policy or opinion of the IUIS.