Optimization of IL-1RA structure to achieve a smaller protein with a higher affinity to its receptor.

Interleukine-1 family cytokines are key orchestrators of innate and adaptive immunity. In particular, up-regulation of IL-1R1 via its agonistic ligands consisting of IL-1ß and IL-1α is implicated in a variety of human diseases, such as rheumatoid arthritis, psoriasis, type I diabetes, amyotrophic lateral sclerosis, and dry-eye disease. Until now, there are no small-molecule inhibitors of the IL-1R1 with increased antagonistic potency to be used for the treatment of peripheral inflammation. The objective of this study was to engineer a low-molecular-weight version of IL-1RA with increased affinity and enhanced antagonistic activity for potential therapeutic use. To develop a smaller protein-ligand with a better affinity to IL-1R, we used bioinformatics studies and in silico simulations to anticipate non-binding areas on IL-1RA. In this study, we have identified a 41aa (F57-F98) non-binding site of IL-1RA. Overall RMSF of the Truncated complex (1.5 nm) was lower than the Native complex (2 nm), which could prove higher stability of the Truncated complex. The free binding energy of the T-IL-1RA (- 1087.037 kJ/mol) was significantly lower than the IL-1RA (- 836.819 kJ/mol) which could demonstrate a higher binding affinity of the truncated ligand with its receptor as a result of new important interactions. These findings have demonstrated a higher binding affinity of the T-IL-1RA with its receptor than the native protein. These results should: have an impact on the development of new treatments that block IL-1 signaling, although more research is needed in vitro and in vivo.

Corrigendum: TNFR2 Is a Crucial Hub Controlling Mesenchymal Stem Cell Biological and Functional Properties.

[This corrects the article DOI: 10.3389/fcell.2020.596831.].

Post-decellularization techniques ameliorate cartilage decellularization process for tissue engineering applications.

Due to the current lack of innovative and effective therapeutic approaches, tissue engineering (TE) has attracted much attention during the last decades providing new hopes for the treatment of several degenerative disorders. Tissue engineering is a complex procedure, which includes processes of decellularization and recellularization of biological tissues or functionalization of artificial scaffolds by active cells. In this review, we have first discussed those conventional steps, which have led to great advancements during the last several years. Moreover, we have paid special attention to the new methods of post-decellularization that can significantly ameliorate the efficiency of decellularized cartilage extracellular matrix (ECM) for the treatment of osteoarthritis (OA). We propose a series of post-decellularization procedures to overcome the current shortcomings such as low mechanical strength and poor bioactivity to improve decellularized ECM scaffold towards much more efficient and higher integration.

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

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. Video Abstract.

TNFR2 Is a Crucial Hub Controlling Mesenchymal Stem Cell Biological and Functional Properties.

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, TGFß, 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.