ATP promotes immunosuppressive capacities of mesenchymal stromal cells by enhancing the expression of indoleamine dioxygenase

Abstract

IntroductionMSCs are often found within tumors, promote cancer progression and enhance metastasis. MSCs can act as immuosuppressive cells, partially due to the expression of the enzyme indoleamine dioxygenase (IDO) which converts tryptophan to kynurenine. Decreased concentration of tryptophan and increased kynurenine, both interfere with effective immune response. Damage associated molecular patterns (DAMPs) including ATP are found within the tumor microenvironment, attract MSCs, and influence their biology.MethodsBone marrow derived MSCs were exposed to ATP for 4 days, in the presence of 100 ng IFNγ/mL. Intracellular expression of IDO in MSCs was assessed by FACS. Conditioned media from thus stimulated MSCs was analyzed for kynurenine content and its suppressive effect on lymphocyte proliferation. Apyrase or P2 × 7‐receptor antagonist (AZ 11645373) were applied in order to inhibit ATP induced effect on MSCs.ResultsWe demonstrate, that ATP at concentrations between 0.062 and 0.5 mM increases dose dependently the expression of IDO in MSCs with subsequent increased kynurenine concentrations within the supernatant at about 60%. This effect could be abolished completely in the presence of ATP degrading enzyme (apyrase) or when MSCs were pretreated with a P2 × 7‐receptor antagonist (AZ 11645373). Consistently, supernatants from MSCs stimulated with ATP, inhibited lymphocyte proliferation from 65% to 16%.ConclusionsWe characterized ATP as a DAMP family member responsible for necrosis‐induced immunomodulation. Given the increased concentration of DAMPs within tumor tissue and the fact that DAMPs can act as chemotattractants to MSCs, our results have implications for therapeutic strategies targeting the tumor microenvironment.

Role of indoleamine 2,3-dioxygenase in ischemia-reperfusion injury of renal tubular epithelial cells

“…Free adenosine induces IDO expression through the adenosine A3 receptor (32). Also, extracellular ATP can upregulate IDO in mesenchymal cells directly through purinergic receptors (33). Since ATP release is a typical response to various types of stress and in numerous cell types (34), the possibility of extracellular ATP-induced IDO expression in RPTECs subjected to I-R deserves evaluation in future studies.…”

Surgical trauma‐induced immunosuppression in cancer: Recent advances and the potential therapies

“…Following trauma, numerous mediators known as DAMPs are immediately released into circulation 26 . The “alarmins” DAMPs may be nuclear or cytosolic proteins, extracellular matrix, or metabolic products 27–44 (Table 2). Plasma levels of DAPMs are associated with cellular immunity impairment in trauma patients 45 .…”

Defective Proliferation and Osteogenic Potential with Altered Immunoregulatory phenotype of Native Bone marrow-Multipotential Stromal Cells in Atrophic Fracture Non-Union

“…The immunosuppressive capacity of culture-expanded BM-MSCs was tested following treatment for 5 days with cytokines. The cells were then processed for measuring the intracellular IDO and surface TGF-β1 latency-associated peptide (LAP) levels using specific conjugated monoclonal antibodies (ThermoFisher) for flow-cytometer as demonstrated in previous studies 111–113 . For passage-zero cultured BM-MSCs that were cytokine-treated, the expression levels of IDO , PGE2 and TGF-ß transcripts was evaluated indicating the MSC immunosuppressive potential.…”