V-domain Ig suppressor of T cell activation (VISTA) is a novel negative checkpoint ligand that is homologous to PD-L1 and suppresses T cell activation. This study demonstrates the multiple mechanisms whereby VISTA relieves negative regulation by hematopoietic cells and enhances protective anti-tumor immunity. VISTA is highly expressed on myeloid cells and Foxp3+CD4+ regulatory cells, but not on tumor cells within the tumor microenvironment (TME). VISTA monoclonal antibody (mab) treatment increased the number of tumor-specific T cells in the periphery, and enhanced the infiltration, proliferation and effector function of tumor-reactive T cells within the TME. VISTA blockade altered the suppressive feature of the TME, by decreasing the presence of monocytic myeloid-derived suppressor cells and increasing the presence of activated DCs within the TME. In addition, VISTA blockade impaired the suppressive function and reduced the emergence of tumor-specific Foxp3+CD4+ regulatory T cells. Consequently, VISTA mab administration as a monotherapy significantly suppressed the growth of both transplantable and inducible melanoma. Initial studies explored a combinatorial regimen using VISTA blockade and a peptide-based cancer vaccine with TLR agonists as adjuvants. VISTA blockade synergized with the vaccine to effectively impair the growth of established tumors. Our study therefore establishes a foundation for designing VISTA-targeted approaches either as a monotherapy or in combination with additional immune-targeted strategies for cancer immunotherapy.

V-domain immunoglobulin suppressor of T-cell activation (VISTA) is a negative immune-checkpoint protein that suppresses T-cell responses. To determine whether VISTA synergizes with another immune-checkpoint, programmed death 1 (PD-1), this study characterizes the immune responses in VISTA-deficient, PD-1-deficient (KO) mice and VISTA/PD-1 double KO mice. Chronic inflammation and spontaneous activation of T cells were observed in both single KO mice, demonstrating their nonredundancy. However, the VISTA/PD-1 double KO mice exhibited significantly higher levels of these phenotypes than the single KO mice. When bred onto the 2D2 T-cell receptor transgenic mice, which are predisposed to development of inflammatory autoimmune disease in the CNS, the level of disease penetrance was significantly enhanced in the double KO mice compared with in the single KO mice. Consistently, the magnitude of T-cell response toward foreign antigens was synergistically higher in the VISTA/PD-1 double KO mice. A combinatorial blockade using monoclonal antibodies specific for VISTA and PD-L1 achieved optimal tumor-clearing therapeutic efficacy. In conclusion, our study demonstrates the nonredundant role of VISTA that is distinct from the PD-1/PD-L1 pathway in controlling T-cell activation. These findings provide the rationale to concurrently target VISTA and PD-1 pathways for treating T-cell-regulated diseases such as cancer.

Significance The discovery of V domain-containing Ig suppressor of T-cell activation (VISTA) as a novel immune-checkpoint regulator comes at an exciting time, as the field of cancer immunotherapy has made significant progress owing to the clinical success of targeting immune-checkpoint proteins such as cytotoxic T lymphocyte-associated antigen 4 and programmed death 1 and ligand. Recent studies also show the promise of monoclonal antibody-mediated VISTA targeting for enhancing antitumor immunity in murine tumor models. The current study demonstrates the spectrum of immune alterations upon genetic disruption of VISTA in mice in the context of self-tolerance as well as immune response against neoantigen. These results enhance the understanding of the immune-regulatory role of VISTA and form the foundation for designing future clinical applications that target VISTA in treating human diseases.

Forest dynamics plots, which now span longitudes, latitudes, and habitat types across the globe, offer unparalleled insights into the ecological and evolutionary processes that determine how species are assembled into communities. Understanding phylogenetic relationships among species in a community has become an important component of assessing assembly processes. However, the application of evolutionary information to questions in community ecology has been limited in large part by the lack of accurate estimates of phylogenetic relationships among individual species found within communities, and is particularly limiting in comparisons between communities. Therefore, streamlining and maximizing the information content of these community phylogenies is a priority. To test the viability and advantage of a multi-community phylogeny, we constructed a multi-plot mega-phylogeny of 1347 species of trees across 15 forest dynamics plots in the ForestGEO network using DNA barcode sequence data (rbcL, matK, and psbA-trnH) and compared community phylogenies for each individual plot with respect to support for topology and branch lengths, which affect evolutionary inference of community processes. The levels of taxonomic differentiation across the phylogeny were examined by quantifying the frequency of resolved nodes throughout. In addition, three phylogenetic distance (PD) metrics that are commonly used to infer assembly processes were estimated for each plot [PD, Mean Phylogenetic Distance (MPD), and Mean Nearest Taxon Distance (MNTD)]. Lastly, we examine the partitioning of phylogenetic diversity among community plots through quantification of inter-community MPD and MNTD. Overall, evolutionary relationships were highly resolved across the DNA barcode-based mega-phylogeny, and phylogenetic resolution for each community plot was improved when estimated within the context of the mega-phylogeny. Likewise, when compared with phylogenies for individual plots, estimates of phylogenetic diversity in the mega-phylogeny were more consistent, thereby removing a potential source of bias at the plot-level, and demonstrating the value of assessing phylogenetic relationships simultaneously within a mega-phylogeny. An unexpected result of the comparisons among plots based on the mega-phylogeny was that the communities in the ForestGEO plots in general appear to be assemblages of more closely related species than expected by chance, and that differentiation among communities is very low, suggesting deep floristic connections among communities and new avenues for future analyses in community ecology.

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A series of multiblock copolymers of PLLA/PEG(PLE) with high molecular weight were synthesized by coupling PLLA‐PEG‐PLLA triblock copolymers with succinic anhydride in the presence of N‐dimethylaminopyridine(DMAP) and dicyclohexylcarbodimide (DCC). The results of the viscometry measurement, GPC and 1H NMR, elucidated that multiblock PLE copolymers with high content of short PEG segments had been successfully obtained. The thermal properties and the crystallinity were investigated by DSC and X‐ray diffraction. When LA/EG molar ratio and the length of PEG segments were the same in both multiblock and triblock copolymers, multiblock copolymers were less crystalline than the corresponding triblock ones. Mechanical testing showed that multiblock copolymers had relatively high tensile strength and large elongation. In a word, the measurements showed that this multiblock PLE copolymers had high content of short PEG segments (Mn = 2000,4000), high molecular weight (Mw∼50 000), high hydrophilicity, and good mechanical properties. The drug (5‐Fluorourecil) release behavior of these PLE multiblock copolymers had been studied in 0.10M pH7.4 phosphate buffer solution (PBS), and the releasing rate could be tailored by adjusting copolymers composition. All of these results indicated that the multiblock PLE copolymers might be useful in medical applications. Copyright © 2003 John Wiley & Sons, Ltd.

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Background and Purpose Neurodegenerative diseases present progressive neurological disorder induced by cell death or apoptosis. Catalpol, an iridoid glucoside isolated from the root of Rehmannia glutinosa Libosch, is present in a wide range of plant families. Although catalpol is an effective anti‐apoptotic agent in LPS‐induced neurodegeneration, the underlying mechanism has not been established. Here we have identified some of the mechanisms involved the prevention by catalpol of apoptosis induced by LPS in an experimental model of neurodegeneration in vitro. Experimental Approach Apoptosis was induced by adding LPS (80 ng·mL−1) to pheochromocytoma (PC12) cells, pretreated with catalpol for 12 h. We measured intracellular reactive oxygen species (ROS), apoptosis and intracellular calcium concentration ( [Ca2+]i) by flow cytometry or laser confocal scanning microscopy. We also analysed the protein expression of Bcl‐2, Bax and Ca2+‐calmodulin‐dependent protein kinase II (CaMKII)‐dependent apoptosis signal‐regulating kinase‐1 (ASK‐1)/JNK/p38 signalling pathway in PC12 cells by Western blot. Key Results Catalpol stimulated expression of Bcl‐2 and inhibited the expression of Bax. Catalpol also attenuated the increase in Ca2+ concentration induced by LPS in PC12 cells and down‐regulated CaMK phosphorylation. The CaMKII‐dependent ASK‐1/JNK/p38 signalling cascade was blocked by catalpol. All these changes were accompanied by a decrease of apoptosis induced by LPS in PC12 cells. Conclusions and Implications The data presented here provide new mechanistic insights into the links between the CaMKII‐dependent ASK‐1/JNK/p38 signalling pathway and the protective effect of catalpol on apoptosis induced by LPS in PC12 cells.