PPARß/δ directs the therapeutic potential of mesenchymal stem cells in arthritis.

OBJECTIVES: To define how peroxisome proliferator-activated receptor (PPAR) ß/δ expression level in mesenchymal stem cells (MSCs) could predict and direct both their immunosuppressive and therapeutic properties. PPARß/δ interacts with factors such as nuclear factor-kappa B (NF-κB) and regulates the expression of molecules including vascular cell adhesion molecule (VCAM)-1 and intercellular adhesion molecule (ICAM)-1. Since these molecules are critical for MSC function, we investigated the role of PPARß/δ on MSC immunosuppressive properties. METHODS: We either treated human MSCs (hMSCs) with the irreversible PPARß/δ antagonist (GSK3787) or derived MSCs from mice deficient for PPARß/δ (PPARß/δ-/- MSCs). We used the collagen-induced arthritis (CIA) as model of immune-mediated disorder and the MSC-immune cell coculture assays. RESULTS: Modulation of PPARß/δ expression in hMSCs either using GSK3787 or hMSCs from different origin reveals that MSC immunosuppressive potential is inversely correlated with Ppard expression. This was consistent with the higher capacity of PPARß/δ-/- MSCs to inhibit both the proliferation of T lymphocytes, in vitro, and arthritic development and progression in CIA compared with PPARß/δ+/+ MSCs. When primed with proinflammatory cytokines to exhibit an immunoregulatory phenotype, PPARß/δ-/- MSCs expressed a higher level of mediators of MSC immunosuppression including VCAM-1, ICAM-1 and nitric oxide (NO) than PPARß/δ+/+ MSCs. The enhanced NO2 production by PPARß/δ-/- MSCs was due to the increased retention of NF-κB p65 subunit on the κB elements of the inducible nitric oxide synthase promoter resulting from PPARß/δ silencing. CONCLUSIONS: Our study is the first to show that the inhibition or knockdown of PPARß/δ in MSCs primes their immunoregulatory functions. Thus, the regulation of PPARß/δ expression provides a new strategy to generate therapeutic MSCs with a stable regulatory phenotype.

Identification of common cricket (Acheta domesticus) proteins, extracted by acid and alkaline methods.

Edible insects currently represent an interesting alternative protein source to the animal ones. The objective of the present wok is to characterize proteins isolated from common cricket (Acheta domesticus). Powder samples of this insect-based flour were obtained using two extraction methods, i.e. acid and alkaline. Subsequently, the proteins isolated have been characterized. The fractionation of proteins in the flour of Acheta domesticus by acid or alkaline-based methods, gave rise to isolates with up to 71.6% in protein content. Extraction in an alkaline medium of insoluble proteins (pellet) resulted in the best performance on protein recovery. These isolates present a wide variety of peptides and proteins, having identified the following ones in the pellet fraction obtained with the acid method: myosin heavy-chain isoforms C, E and Miosin heavy chain (Mhc); tropomyosin; troponin; α and ß actin, and some enzymes such as the ß subunit ATP synthetase. The characterization results provide information which will enable us to predict the possible physicochemical (gel formation, solubility, water retention capacity, etc.) changes that could take place in the cricket protein during processing in the food and feed industry.

PPARß/δ-dependent MSC metabolism determines their immunoregulatory properties.

Mesenchymal stem cell (MSC)-based therapy is being increasingly considered a powerful opportunity for several disorders based on MSC immunoregulatory properties. Nonetheless, MSC are versatile and plastic cells that require an efficient control of their features and functions for their optimal use in clinic. Recently, we have shown that PPARß/δ is pivotal for MSC immunoregulatory and therapeutic functions. However, the role of PPARß/δ on MSC metabolic activity and the relevance of PPARß/δ metabolic control on MSC immunosuppressive properties have never been addressed. Here, we demonstrate that PPARß/δ deficiency forces MSC metabolic adaptation increasing their glycolytic activity required for their immunoregulatory functions on Th1 and Th17 cells. Additionally, we show that the inhibition of the mitochondrial production of ATP in MSC expressing PPARß/δ, promotes their metabolic switch towards aerobic glycolysis to stably enhance their immunosuppressive capacities significantly. Altogether, these data demonstrate that PPARß/δ governs the immunoregulatory potential of MSC by dictating their metabolic reprogramming and pave the way for enhancing MSC immunoregulatory properties and counteracting their versatility.

Glucocorticoid-induced leucine zipper governs the therapeutic potential of mesenchymal stem cells by inducing a switch from pathogenic to regulatory Th17 cells in a mouse model of collagen-induced arthritis.

OBJECTIVE: Mesenchymal stem cells (MSCs) are potent immunosuppressive cells that have shown promise in the treatment of rheumatoid arthritis (RA). Deciphering the intrinsic characteristics of MSCs that correlate with their biologic activity will facilitate their clinical use. Recently, the role of glucocorticoid-induced leucine zipper (GILZ) in the development of RA has been documented. The aim of this study was to evaluate whether GILZ expression by MSCs may contribute to their therapeutic effect. METHODS: MSCs were isolated from GILZ-deficient (GILZ(-/-) ) mice and wild-type mice. MSCs (1 × 10(6) cells) were injected twice via the tail vein into mice with collagen-induced arthritis (CIA). RESULTS: In vitro, we showed that GILZ is a key factor involved in the immunosuppressive potential of MSCs. MSCs derived from GILZ(-/-) mice did not suppress the proliferation of CD4+ T cells and were less efficient than MSCs derived from WT mice in altering Th17 cell polarization. Thus, we investigated the role of GILZ in an experimental model of arthritis and demonstrated that although WT MSCs significantly reduced paw swelling in arthritic mice, GILZ(-/-) MSCs did not. Moreover, the magnitude of the effects of GILZ(-/-) MSCs on Th17 cell frequency was significantly lower than that of WT MSCs. The therapeutic effect of MSCs correlated with the generation of Treg cells bearing the CD4 + RORγt+IL-17(low) IL-10+ signature, and Th17 cell polarization was GILZ dependent. CONCLUSION: This study demonstrates that GILZ has an essential role in the therapeutic effectiveness of MSCs in arthritis by favoring Th17 cell polarization toward a regulatory phenotype. Therefore, potentiation of GILZ expression in MSCs could represent a means to enhance their therapeutic effect in autoimmune diseases.

In-hospital mortality due to infectious disease in an Internal Medicine Department. Epidemiology and risk factors.

OBJECTIVE: Hospital mortality is a leading indicator of quality of healthcare and a valuable tool for planning and management. Infectious diseases represent a substantial part of the activity of internal medicine.Our aim was to describe the characteristics of in-hospital mortality due to infectious diseases and associated risk factors in our environment. MATERIALS AND METHODS: A retrospective case-control study was designed. We reviewed deaths during 2012 from an Internal Medicine Department. 187 cases (infectious disease related mortality) and 224 controls were found. Clinical and demographic information was obtained from medical records. Comorbidity was evaluated with Charlson index (CI). Data were analyzed using SPSS 15.0 (p-value < 0.05). RESULTS: During 2012, of the 3193 discharge, 187 were exitus due to infectious disease (5.8%). Mean age was 85.7 ± 7.6, higher in women (88 ± 7 vs 83 ± 7.4, p < 0.001), and 55% were aged over 85 years. The CI mean was 4.2 ± 3, higher in younger than 85 years (5.3 ± 3.4 vs 3.6 ± 2.6, p < 0.001). Most frequent causes of death were respiratory sepsis (29%), severe pneumonia (23.5%) and urinary sepsis (16.6%) and risk factors were living in Nursing Home (55.6% vs 34%, p < 0.001), being dependent (73.8% vs. 44.6%, p < 0.001), dementia (59.4% vs 27.2%, p < 0.001) and cerebrovascular disease (25.7% vs 17.4%, p = 0.041). CONCLUSIONS: Dementia, cerebrovascular disease, living in Nursing Home and being dependent were risk factors for infectious disease in-hospital mortality in our study, but not comorbidity, age or length of stay. Our series, although limited by retrospective design, is the first qualitative study of in-hospital mortality due to infectious disease in an Internal Medicine Service in our environment. Most frequent cause of death in our setting was respiratory etiology.