Suppressive intratumoral myeloid populations

Suppressive intratumoral myeloid populations, primarily consisting of myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs), are critical components of the tumor microenvironment that facilitate immune evasion and disease progression (Gabrilovich, 2017). These cells utilize various mechanisms to inhibit the anti-tumor activity of T cells and natural killer cells, including the production of immunosuppressive enzymes like Arginase-1 and inducible nitric oxide synthase (iNOS), as well as the secretion of inhibitory cytokines such as IL-10 and TGF-beta (Veglia et al., 2021). Beyond their role in immune suppression, these myeloid populations promote tumor growth by stimulating angiogenesis, supporting cancer stem cell niches, and facilitating metastatic dissemination through extracellular matrix remodeling (Cassetta & Pollard, 2018). Therapeutic strategies targeting these cells include blocking their recruitment from the bone marrow (e.g., via CCR2 or CSF1R inhibition), direct depletion, or metabolic and epigenetic reprogramming to restore their pro-inflammatory, anti-tumor functions. However, the inherent plasticity of myeloid cells and their essential roles in normal tissue homeostasis and wound healing present significant challenges for achieving targeted therapeutic effects without inducing systemic toxicity or secondary immune deficiencies.

Other names

Myeloid-derived suppressor cellsMDSCsTumor-associated macrophagesTAMsTumor-associated neutrophilsTANsSuppressive myeloid cells

Inhibition of recruitment, depletion of cell populations, or phenotypic reprogramming from immunosuppressive to immunostimulatory states.