TNFR2 Is a Crucial Hub Controlling Mesenchymal Stem Cell Biological and Functional Properties
Authors: Georges Uzan
Sina Naserian
Chloé Lezin
Ghada Beldi
Sheyda Bahiraii
Mahsa Nouri Barkestani
Mohamed Essameldin Abdelgawad
Journal: Frontiers in Cell and Developmental Biology (2020)
Discipline: MOLECULAR BIOLOGY & GENETICS
Keywords: TNFα–TNFR2 signaling pathway; angiogenesis; immune-checkpoint; immunoregulation; mesenchymal stem cells
Affiliations: INSERM UMR-S-MD 1197, Hôpital Paul Brousse, Villejuif, France., Department of Pharmacognosy, University of Vienna, Vienna, Austria., Paris-Saclay University, Villejuif, France., Biochemistry Division, Chemistry Department, Faculty of Science, Helwan University, Cairo, Egypt., CellMedEx, Saint Maur Des Fossés, France.

Abstract:  Mesenchymal stem cells (MSCs) have drawn lots of attention as gold standard stem cells in fundamental and clinical researches during the last 20 years. Due to their tissue and vascular repair capacities, MSCs have been used to treat a variety of degenerative disorders. Moreover, MSCs are able to modulate immune cells' functions, particularly T cells while inducing regulatory T cells (iTregs). MSCs are very sensitive to inflammatory signals. Their biological functions could remarkably vary after exposure to different pro-inflammatory cytokines, notably TNFα. In this article, we have explored the importance of TNFR2 expression in a series of MSCs' biological and functional properties. Thus, MSCs from wild-type (WT) and TNFR2 knockout (TNFR2 KO) mice were isolated and underwent several ex vivo experiments to investigate the biological significance of TNFR2 molecule in MSC main functions. Hampering in TNFR2 signaling resulted in reduced MSC colony-forming units and proliferation rate and diminished the expression of all MSC characteristic markers such as stem cell antigen-1 (Sca1), CD90, CD105, CD44, and CD73. TNFR2 KO-MSCs produced more pro-inflammatory cytokines like TNFα, IFNγ, and IL-6 and less anti-inflammatory mediators such as IL-10, TGFβ, and NO and induced Tregs with less suppressive effect. Furthermore, the TNFR2 blockade remarkably decreased MSC regenerative functions such as wound healing, complex tube formation, and endothelial pro-angiogenic support. Therefore, our results reveal the TNFα-TNFR2 axis as a crucial regulator of MSC immunological and regenerative functions. 

Retracted: No

PubPeer comments:
 Two images in Figure 7A appear to overlap, with different magnification. *** ![file] ![file] , 
 Figure 6A has some repeated features and background, which may be from dirty equipment. Could the authors please check? *** Enhanced contrast and brightness. ![file] , 
 #2 We are thankful for these comments and the interest in our work. Concerning figure 7A, we confirm that they are not with different magnifications and that the compared photos are representing equivalent magnifications. The probable similarity is within the negative control groups (not the interest groups as illustrated below them). Mesenchymal stem cells are incapable of network formation in the absence of proper growth factors like VEGF, IGF, FGF and etc. We have seeded our control group on Matrigel and added DMEM medium without any additional growth factors, therefore, neither WT nor KO MSCs are not able to form networks. However, the addition of the EGM2 medium that contains several growth factors will cause the MSCs to form complex networks. In this case, one can see a complete difference between WT and TNFR2 KO MSCs. In order to be sure we will check our images and verify if they have been selected wrongly. We will contact the journal as soon as possible if we have noticed the wrong images were communicated. Concerning the second comment, these kinds of features are very normal while culturing MSCs and upon further experimentations. Indeed, the presence of contamination will cause the integrity of the seeded cells and is completely obvious in the images which is not the case here. The presence of dead cells or debris is quite normal not a matter of concern. We are dealing with these images on a daily basis. Once again we are thankful for our comments and ready to share our images with anyone how asks for them. , 
 Corrigendum published 24 August 2021 In the original article, there were two mistakes in the legend for Figure 5 and in Figure 7A. Regarding the legend for Figure 5, we neglected to mention that the graphical images in Figure 5A were created with BioRender.com. The correct version appears as below. Figure 5. The TNFR2 Expression by mesenchymal stem cells (MSCs) is associated with the induction of Tregs with more immunosuppressive effect. (A) T cells were freshly isolated and depleted from CD25 subpopulation in order to eliminate natural Tregs and highly activated T cells. CD3+CD25u2212 Tconvs (orange population) were then added to wild-type (WT) and TNFR2 knockout (KO)-MSCs in a fixed 1 10 MSC T cell ratio. After 72 h, CD4+CD25+Foxp3+ induced regulatory T cells (iTregs) generated in those co-cultures (green population) were put in an mixed lymphocyte reaction (MLR) test with newly isolated and activated mouse CFSE+CD3+CD25u2212 Tconvs in a fixed 1 5 iTreg Tconv ratio. Then, the CD4+ and CD8+ proliferation capacity was measured by fluorescence-activated cell sorting (FACS). (B) Percentage of proliferation of CD4+ and CD8+ Tconvs in the presence of MSC induced Foxp3+ Tregs. Control groups consist of unstimulated T cells alone as depicted by the white columns (n = 6), while the stimulated T cells alone are depicted by the black columns (n = 6). The blue columns represent the stimulated T cells co-cultured with iTregs derived from WT-MSCs (n = 6), and the red columns represent the stimulated T cells co-cultured with iTregs derived from TNFR2 KO-MSCs (n = 6). Results are collected from two independent experiments. The graphical images were created with BioRender.com. Regarding Figure 7A, the representative images used for control groups i.e., MSCs WT and TNFR2 KO in DMEM medium were both from the MSC WT group. New representative images from proper control groups were added in the corrected version of Figure 7. The corrected Figure 7 appears below. ![file] The authors apologize for these errors and state that this does not change the scientific conclusions of the article in any way. The original article has been updated. ,