Dual IFN-γ/hypoxia priming enhances immunosuppression of mesenchymal stromal cells through regulatory proteins and metabolic mechanisms

Abstract

The immunosuppressive capacity of human mesenchymal stromal cells (MSCs) renders them promising candidates for treating diverse immune disorders. However, after hundreds of clinical trials, there are still no MSC therapies approved in the United States. MSCs require specific cues to adopt their immunosuppressive phenotype, and yet most clinical trials use cells expanded in basic culture medium and growth conditions. We propose that priming MSCs prior to administration will improve their therapeutic efficacy. Interferon-gamma (IFN-γ) priming are cues common to situations of immune escape that have individually shown promise as MSC priming cues but have not been systematically compared. Using mixed lymphocyte reactions, we show that priming MSCs with either cue alone improves T-cell inhibition. However, combining the two cues results in additive effects and markedly enhances the immunosuppressive phenotype of MSCs. We demonstrate that IFN-γ induces expression of numerous immunosuppressive proteins (IDO, PD-L1, HLA-E, HLA-G), whereas hypoxia switches MSCs to glycolysis, causing rapid glucose consumption and production of T-cell inhibitory lactate levels. Dual IFN-γ/hypoxia primed MSCs display both attributes and have even higher induction of immunosuppressive proteins over IFN-γ priming alone (IDO and HLA-G), which may reflect another benefit of metabolic reconfiguration.

Priming approaches to improve the efficacy of mesenchymal stromal cell-based therapies

“…Preconditioning of AT-MSC with hypoxia and IFN-γ led to synergic effects [ 75 ]. The authors reported increased anti-proliferative capacity that correlated with higher secretion of IDO and HLA-G, and significant upregulation of proteins involved in gluconeogenesis [ 75 ].…”

“…Preconditioning of AT-MSC with hypoxia and IFN-γ led to synergic effects [ 75 ]. The authors reported increased anti-proliferative capacity that correlated with higher secretion of IDO and HLA-G, and significant upregulation of proteins involved in gluconeogenesis [ 75 ]. Dual priming with hypoxia/IFN-γ decreased the production of VEGF and IL-8, increased the secretion of MCP-1 and IL-6, and increased endothelial cell migration in a “wound closure” assay [ 76 ].…”

HIF1α‐dependent metabolic reprogramming governs mesenchymal stem/stromal cell immunoregulatory functions

“…During osteogenesis, HIF1α expression level progressively decreased in MSC to activate mitochondrial OXPHOS 22 . Regarding MSC immunosuppressive properties, MSC metabolic activity has been recently proposed to be correlated with their suppressive capacity 23,24 . However, the role of the metabolic reprogramming mediated by HIF1α on MSC immunoregulatory function remains to be better defined.…”

Controlled presentation of cues during biomanufacturing to influence IDO mediated immune modulation by human MSCs

“…Pre-licensing did not make MSCs equivalent but with the appropriate strategy, it did consistently enhance immunomodulatory capacity. Other groups studying IFNγ pre-licensing have used a large range of doses and durations [48][49][50][51][52] , but less is better.…”

“…Although senescent MSCs transcibe IDO at a similar rate as earlier passage cells, IDO protein concentration is lower due to proteosomal degredation41 . performed with the addition of the inflammatory cytokine TNFα as well as culturing under hypoxia51 .Without pre-licensing, MSCs immunomodulatory potency can differ widely depending on the donor and tissue source. Pre-licensing, however, has been proposed to be a way to improve the consistency of performance between donors.…”