IntroductionMesenchymal stem cells (MSCs) comprise an adult population that resides in many organs and exhibits multiple functions and phenotypes upon in vitro culture; MSCs can be induced to differentiate into mesodermal cell lineages, 1,2 support and regulate hematopoiesis, [3][4][5][6][7] regulate the stem-cell niche, [8][9][10][11][12] and may participate in the repair of tissue damage inflicted by normal wear and tear, injury, or disease. [13][14][15][16] MSCs comprise 0.01% to 0.001% of the bone marrow (BM)-nucleated cells and are obtained by expansion of the BM, plastic-adherent cell fraction. 1,[17][18][19][20][21] Under certain physiologic or experimental conditions, MSCs can be induced to differentiate in vitro into cells of the mesodermal lineage, specifically to osteocytes, adipocytes, chondrocytes, myocytes, tenocytes, myocardiocytes, and hematopoietic supportive stroma. 1,17,19,22 MSCs are an attractive cell-based therapy tool for developmental defects; degenerating diseases; and bone, cartilage, muscle, and other mesodermal tissue injuries. [23][24][25][26][27][28][29][30] Toll-like receptors (TLRs) are a class of molecules first discovered to play a role in body development 31 and later found to play a role in body maintenance. [32][33][34][35][36] The TLR family has been shown to be of importance in the innate immune system for the recognition of pathogen-associated molecular patterns (PAMPs) by immune cells, initiating a primary response toward invading pathogens and recruitment of the adaptive immune response. 32,[37][38][39][40][41][42][43][44][45][46][47][48][49] TLRs can be activated not only by pathogen components, but also by mammalian endogenous molecules such as heat-shock proteins and extracellular matrix breakdown products. [50][51][52] In the steady state, during the generation of immune cells, as well as under pathologic conditions, there are intimate interactions between lymphocyte populations and the organ stroma mesenchyme. These interactions regulate cell growth and differentiation and control cell functions. It is possible therefore that lymphocytes and the stromal mesenchyme share regulatory mechanisms. To test this possibility we aimed, in the present study, to examine the expression and possible regulatory functions of TLRs in mesenchymal cells.We explored the expression of TLRs by MSCs, the response of MSCs to known TLR activators, and the ability of a TLR-2 ligand to regulate MSC proliferation and differentiation. We show here that cultured MSCs express TLR molecules 1 to 8, but not TLR-9. Activation of MSCs by TLR ligands induced interleukin-6 (IL-6) secretion and nuclear factor B (NF-B) nuclear translocation. Pam3Cys, a prototypic ligand for TLR-2, induced proliferation of MSCs and regulated their differentiation. Relatively little is known about the signals that regulate MSC proliferation, differentiation, and development. 53,54 Our findings suggest that TLR signaling may play a role in restraining MSC differentiation and thus promote MSC renewal. Materials and methods ...

Chemokines presented by the endothelium are critical for integrin-dependent adhesion and transendothelial migration of naive and memory lymphocytes. Here we found that effector lymphocytes of the type 1 helper T cell (T(H)1 cell) and type 1 cytotoxic T cell (T(C)1 cell) subtypes expressed adhesive integrins that bypassed chemokine signals and established firm arrests on variably inflamed endothelial barriers. Nevertheless, the transendothelial migration of these lymphocytes strictly depended on signals from guanine nucleotide-binding proteins of the G(i) type and was promoted by multiple endothelium-derived inflammatory chemokines, even without outer endothelial surface exposure. Instead, transendothelial migration-promoting endothelial chemokines were stored in vesicles docked on actin fibers beneath the plasma membranes and were locally released within tight lymphocyte-endothelial synapses. Thus, effector T lymphocytes can cross inflamed barriers through contact-guided consumption of intraendothelial chemokines without surface-deposited chemokines or extraendothelial chemokine gradients.

Purpose: To evaluate the efficacy and safety of eplerenone for chronic nonresolving central serous chorioretinopathy (CSC). Methods: Prospective, double-blind, randomized placebo-controlled study. Nineteen eyes of 17 patients with persistent subretinal fluid (SRF) due to CSC were enrolled and randomized to receive eplerenone 50 mg/day or placebo for 3 months, followed by a 3-month follow-up. The main outcome measure was change in SRF from baseline to 3 months of treatment. Secondary outcomes included change in SRF at any time-point, complete resolution of SRF, improvement in choroidal thickness and change in best-corrected visual acuity (BCVA). Results: Thirteen eyes were treated with eplerenone and six with placebo. Both groups showed reduction in SRF throughout the treatment period, with a significant reduction at months 1, 3 and 5 only in the treatment group. Twentythree per cent in the treatment group and 30.8% per cent in the placebo group experienced complete resolution of SRF. A significant improvement in BCVA was noted in the placebo group at 4 months, as well as a significant difference in BCVA between groups at 3 months in favour of the placebo group (p = 0.005). There was no significant difference in choroidal thickness in either group throughout the study period. No adverse events related to eplerenone were noted in the treatment group. Conclusion: In this study, eplerenone was not found to be superior to placebo in eyes with chronic CSC.

Proper regulation of cell proliferation, cell apoptosis, and cell death are vital for the development and survival of living organisms. Failure or dysfunction of any of these processes can have devastating effects, including cancer. The Hippo pathway, first discovered in Drosophila, has been found to be a major growth-regulatory signaling pathway that controls these crucial processes and has been implicated in cell-progress regulation and organ size determination. Abnormal regulation of this pathway has been found in several cancer types. However, the mechanisms that regulate the pathway and its core members yet have to be elucidated. One of the main core components of this pathway is LATS1, a serine/threonine kinase. Therefore, understanding how LATS1 activity is regulated is expected to shed light on new mechanisms that regulate the Hippo pathway. In the current work, we identified several potential LATS1 regulators and proved that NEDD4 E3 ubiquitin ligase controls LATS1 stability. We demonstrate that NEDD4 directly interacts with LATS1, leading to ubiquitination and decreased levels of LATS1 and, thus, increased YAP localization in the nucleus, which subsequently increases the transcriptional activity of YAP. As such, we show that NEDD4 acts as an additional regulator of the Hippo pathway on the protein level via interactions between WW domain-containing and PPxY motif-containing proteins. These findings might be applied in the development of new therapeutic approaches through the activation of LATS1.

Viruses have evolved several strategies to modify cellular processes and evade the immune response in order to successfully infect, replicate, and persist in the host. By utilizing in-silico testing of a transmembrane sequence library derived from virus protein sequences, we have pin-pointed a nine amino-acid motif shared by a group of different viruses; this motif resembles the transmembrane domain of the α-subunit of the T-cell receptor (TCRα). The most striking similarity was found within the immunodeficiency virus (SIV and HIV) glycoprotein 41 TMD (gp41 TMD). Previous studies have shown that stable interactions between TCRα and CD3 are localized to this nine amino acid motif within TCRα, and a peptide derived from it (TCRα TMD, GLRILLLKV) interfered and intervened in the TCR function when added exogenously. We now report that the gp41 TMD peptide co-localizes with CD3 within the TCR complex and inhibits T cell proliferation in vitro. However, the inhibitory mechanism of gp41 TMD differs from that of the TCRα TMD and also from the other two known immunosuppressive regions within gp41.