Diabetes is a conventional risk factor for atherosclerotic cardiovascular disease and myocardial infarction (MI) is the most common cause of death among these patients. Mesenchymal stromal cells (MSCs) in patients with type 2 diabetes (T2DM) and atherosclerosis have impaired ability to suppress activated T-cells (i.e. reduced immunopotency). This is mediated by an inflammatory shift in MSC secreted soluble factors (i.e. pro-inflammatory secretome) and can contribute to the reduced therapeutic effects of autologous T2DM and atherosclerosis-MSC post-myocardial infarction. The signaling pathways driving the altered secretome of atherosclerosis- and T2DM-MSC are unknown. Specifically, the effect of IκB kinase β (IKKβ) modulation, a key regulator of inflammatory responses, on the immunopotency of MSCs from T2DM patients with advanced atherosclerosis has not been studied.
MSCs were isolated from adipose tissue obtained from patients with (i) Atherosclerosis and T2DM (Atherosclerosis+T2DM MSCs, n = 17), (ii) Atherosclerosis without T2DM (Atherosclerosis MSCs, n = 17). MSCs from atherosclerosis+T2DM individuals displayed an inflammatory senescent phenotype and constitutively expressed active forms of effectors of the canonical IKKβ NF-κB inflammatory pathway. Importantly, this constitutive pro-inflammatory IKKβ signature resulted in an altered secretome and impaired in vitro immunopotency and in vivo healing capacity in an acute MI model. Notably, treatment with a selective IKKβ inhibitor or IKKβ knockdown (CRISPR/Cas9-mediated IKKβ KD) in atherosclerosis+T2DM MSCs reduced the production of pro-inflammatory secretome, increased survival and rescued their immunopotency both in vitro and in vivo.
Constitutively active IKKβ reduces the immunopotency of atherosclerosis+T2DM MSC by changing their secretome composition. Modulation of IKKβ in atherosclerosis+T2DM MSCs enhance their myocardial repair ability.
Mesenchymal stromal cells (MSCs) are potent modulators of the immune system and used in clinical trials of inflammatory conditions including atherosclerotic cardiovascular diseases. MSC-secreted bioactive molecules (i.e. secretome) mediate the crosstalk between MSCs and innate/adaptive immune cells. Further, the balance between anti- and pro-inflammatory factors in secretome determines immunopotency. We show that MSCs from diabetic patients with atherosclerosis constitutively express activated forms of the inflammatory effector IKKβ and NF-κB that shifts their secretome towards a pro-inflammatory phenotype and reduces their healing capacity in vivo. Our work emphasizes the importance of proper donor selection and the feasibility of enhancing the immunopotency of atherosclerotic+T2DM-MSC by ex vivo targeting IKKβ.

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