TNFα priming through its interaction with TNFR2 enhances endothelial progenitor cell immunosuppressive effect: new hope for their widespread clinical application

Abstract

Background Bone marrow derived endothelial progenitor cells (EPCs) are immature endothelial cells (ECs) involved in neo-angiogenesis and endothelial homeostasis and are considered as a circulating reservoir for endothelial repair. Many studies showed that EPCs from patients with cardiovascular pathologies are impaired and insufficient; hence, allogenic sources of EPCs from adult or cord blood are considered as good choices for cell therapy applications. However, allogenic condition increases the chance of immune rejection, especially by T cells, before exerting the desired regenerative functions. TNFα is one of the main mediators of EPC activation that recognizes two distinct receptors, TNFR1 and TNFR2. We have recently reported that human EPCs are immunosuppressive and this effect was TNFα-TNFR2 dependent. Here, we aimed to investigate if an adequate TNFα pre-conditioning could increase TNFR2 expression and prime EPCs towards more immunoregulatory functions. Methods EPCs were pre-treated with several doses of TNFα to find the proper dose to up-regulate TNFR2 while keeping the TNFR1 expression stable. Then, co-cultures of human EPCs and human T cells were performed to assess whether TNFα priming would increase EPC immunosuppressive and immunomodulatory effect. Results Treating EPCs with 1 ng/ml TNFα significantly up-regulated TNFR2 expression without unrestrained increase of TNFR1 and other endothelial injury markers. Moreover, TNFα priming through its interaction with TNFR2 remarkably enhanced EPC immunosuppressive and anti-inflammatory effects. Conversely, blocking TNFR2 using anti-TNFR2 mAb followed by 1 ng/ml of TNFα treatment led to the TNFα-TNFR1 interaction and polarized EPCs towards pro-inflammatory and immunogenic functions. Conclusions We report for the first time the crucial impact of inflammation notably the TNFα-TNFR signaling pathway on EPC immunological function. Our work unveils the pro-inflammatory role of the TNFα-TNFR1 axis and, inversely the anti-inflammatory implication of the TNFα-TNFR2 axis in EPC immunoregulatory functions. Priming EPCs with 1 ng/ml of TNFα prior to their administration could boost them toward a more immunosuppressive phenotype. This could potentially lead to EPCs’ longer presence in vivo after their allogenic administration resulting in their better contribution to angiogenesis and vascular regeneration.

Flexibility of Oxidized and Reduced States of the Chloroplast Regulatory Protein CP12 in Isolation and in Cell Extracts

“…CP12 is present in the chloroplast of photosynthetic organisms from cyanobacteria, green and red algae, higher plants, as well as heterokonts [ 27 , 28 , 32 ]. Various functions have been assigned to this protein, in particular, the dark down-regulation of two CBB enzymes: GAPDH and PRK, as well as their fast re-activation upon dark-to-light transition [ 22 ].…”

“…Various functions have been assigned to this protein, in particular, the dark down-regulation of two CBB enzymes: GAPDH and PRK, as well as their fast re-activation upon dark-to-light transition [ 22 ]. Genetic and proteomic studies on higher plants and heterokonts suggest that CP12 has other functions, for example, related to stress regulation [ 32 , 56 , 57 , 58 , 59 ]. The enigmatic and multiple functions of CP12 is not an unusual property for a protein belonging to the CDP family [ 1 ].…”

“…This latter protein also binds to GAPDH with a high affinity. In addition, other organisms possess CP12 homologs that only contain the conserved N -terminal motif A 34 WxxVEEL 41 that is embedded in the dynamical PRK-binding region defined above [ 27 , 32 ], but the function of these proteins remains to be elucidated.…”

“…CP12 belongs to the CDP family and its conditional disorder allows for nuanced control of CBB enzymes and their fine regulation through binding processes. Besides the dark down regulation of CBB enzymes, this protein is a jack-of-all trades and can perform different functions in a photosynthetic cell [ 22 , 32 ].…”

A compact integrated microfluidic oxygenator with high gas exchange efficiency and compatibility for long-lasting endothelialization

“…We used cord blood ECFCs because these cells display higher performance and immunoregulatory function than adult cells, and they can be easily obtained. 29,30 To introduce and seed endothelial cells into the device, cells were maintained under a 1 μl min −1 flow rate for 60 minutes before the flow rate was increased to 10 μl min −1 . To assess endothelialization success and maintenance, images were acquired at different time points from day 1 to day 12 (Fig.…”