Convergent synthesis of glycoalkaloids solasonine and its saponin derivative.

We present a practical and convergent synthesis of glycoalkaloids solasonine 1 and its saponin derivative 2, incorporating a {3-O-α-L-rhamnopyranosyl-(1→2)-O-[ß-D-glucopyranosyl-(1→3)]-ß-D-galactopyranoside} moiety. The key features of this strategy include the following: (1) AuCl3-tBuCN cooperative catalysis enabling 1,2-trans stereoselective glycosidation of 2-branched trisaccharide trichloroacetimidate donors with steroidal aglycons, in the absence of neighboring group participation; (2) "cyanide effect" mediated regioselective benzoylation of the 4- and 6-hydroxyl groups of galactopyranosyl disaccharide; and (3) an effective approach to prevent orthoester byproduct formation.

Decoding CD4+ T cell transcriptome in giant cell arteritis: Novel pathways and altered cross-talk with monocytes.

BACKGROUND: Giant cell arteritis (GCA) is an immune-mediated large-vessels vasculitis with complex etiology. Although the pathogenic mechanisms remain poorly understood, a central role for CD4+ T cells has been demonstrated. In this context, understanding the transcriptome dysregulation in GCA CD4+ T cells will yield new insights into its pathogenesis. METHODS: Transcriptome analysis was conducted on CD4+ T cells from 70 patients with GCA with different disease activity and treatment status (active patients before treatment and patients in remission with and without glucocorticoid treatment), and 28 healthy controls. The study also evaluated potential impacts of DNA methylation on gene expression alterations and assessed cross-talk with CD14+ monocytes. RESULTS: This study has uncovered a substantial number of genes and pathways potentially contributing to the pathogenicity of CD4+ T cells in GCA. Specifically, CD4+ T cells from GCA patients with active disease exhibited altered expression levels of genes involved in multiple immune-related processes, including various interleukins (IL) signaling pathways. Notably, IL-2, a decisive interleukin for regulatory T cells homeostasis, was among the most significant. Additionally, impaired apoptotic pathways appear crucial in GCA development. Our findings also suggest that histone-related epigenetic pathways may be implicated in promoting an inflammatory phenotype in GCA active patients. Finally, our study observed altered signaling communication, such as the Jagged-Notch signaling, between CD4+ T cells and monocytes that could have pathogenic relevance in GCA. CONCLUSIONS: Our study suggests the participation of novel cytokines and pathways and the occurrence of a disruption of monocyte-T cell crosstalk driving GCA pathogenesis.

Reaction Rate and Stereoselectivity Enhancement in Glycosidations with O-Glycosyl Trihaloacetimidate Donors due to Catalysis by a Lewis Acid-Nitrile Cooperative Effect.

Activation of O-glycosyl trihaloacetimidate glycosyl donors with AuCl3 as a catalyst and pivalonitrile (tBuCN) as a ligand led to excellent glycosidation results in terms of yield and anomeric selectivity. In this way, various ß-d-gluco- and ß-d-galactopyranosides were obtained conveniently and efficiently. Experimental studies and density functional theory (DFT) calculations, in order to elucidate the reaction course, support formation of the tBuCN-AuCl2-OR(H)+ AuCl4- complex as a decisive intermediate in the glycosidation event. Proton transfer from this acceptor complex to the imidate nitrogen leads to donor activation. In this way, guided by the C-2 configuration of the glycosyl donor, the alignment of the acceptor complex enforces the stereoselective ß-glycoside formation in an intramolecular fashion, thus promoting also a fast reaction course. The high stereocontrol of this novel 'Lewis acid-nitrile cooperative effect' is independent of the glycosyl donor anomeric configuration and without the support of neighboring group or remote group participation. The power of the methodology is shown by a successful glycoalkaloid solamargine synthesis.

Synthesis of Core M3 Matriglycan Constituents via an Additive-Controlled 1,2-cis-Xylopyranosylation with O-Xylosyl Imidates as Donors.

A highly stereoselective strategy for 1,2-cis-xylopyranoside bond formation was established via a preactivation-based, additive-modulated trichloroacetimidate glycosidation strategy. The current protocol is mild, practical, and successful with various xylopyranosyl donors and glycosyl acceptors, including acceptors that are reported to be less reactive due to steric hindrance. The utility of this method was demonstrated with the facile assembly of matriglycan constituent tetra- and hexasaccharides.

Study on Enhancing the Corrosion Resistance and Photo-Thermal Antibacterial Properties of the Micro-Arc Oxidation Coating Fabricated on Medical Magnesium Alloy.

Photo-thermal antibacterial properties have attracted much attention in the biomedical field because of their higher antibacterial efficiency. Through fabricating micro-arc oxidation coatings with different treating current densities set on a Mg-Zn-Ca alloy, the present study tried to systematically investigate and optimize the corrosion resistance and photo-thermal antibacterial properties of MAO coatings. The results indicated that different current densities had great influence on the corrosion resistance and photo-thermal property of the MAO coatings, and a current density at 30 A·dm-2 exhibited the best corrosion resistance, light absorption capacity at 808 nm, and photo-thermal capability, simultaneously with good antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). This photo-thermal property of MAO coatings was probably related to the effect of current density on MgO content in the coating that could promote the separation of photo-generated electron carriers and hinder the recombination of photo-generated electron carriers and holes.

Sulfated Glycoprotein Synthesis.

Chemical protein synthesis has achieved tremendous progress in the past decades. With the development of chemical ligation as powerful tools, the scope of synthetic protein is greatly expanded. Proteoglycans are a class of sulfated glycoproteins widely distributed on the cell surface and in the extracellular matrix, which are extensively engaged in cellular communication events. Consisting of protein backbone and glycosaminoglycan(s) side chain, proteoglycans are highly complex and heterogeneous in nature. Chemical synthesis provides facile and reliable approach to these molecules, with defined glycan structure and sulfation pattern. One remaining problem is that the acid-labile sulfates could hardly survive during the typical solid phase peptide synthesis (SPPS) process. In this chapter, strategic design of a "glycopeptide cassette" for the preparation of sulfated glycoprotein is described. In particular, we provide protocols for the chemical synthesis of ectodomain fragment (23-120) of sulfated glycoprotein syndecan-1.

Methylome and transcriptome profiling of giant cell arteritis monocytes reveals novel pathways involved in disease pathogenesis and molecular response to glucocorticoids.

OBJECTIVES: Giant cell arteritis (GCA) is a complex systemic vasculitis mediated by the interplay between both genetic and epigenetic factors. Monocytes are crucial players of the inflammation occurring in GCA. Therefore, characterisation of the monocyte methylome and transcriptome in GCA would be helpful to better understand disease pathogenesis. METHODS: We performed an integrated epigenome-and transcriptome-wide association study in CD14+ monocytes from 82 patients with GCA, cross-sectionally classified into three different clinical statuses (active, in remission with or without glucocorticoid (GC) treatment), and 31 healthy controls. RESULTS: We identified a global methylation and gene expression dysregulation in GCA monocytes. Specifically, monocytes from active patients showed a more proinflammatory phenotype compared with healthy controls and patients in remission. In addition to inflammatory pathways known to be involved in active GCA, such as response to IL-6 and IL-1, we identified response to IL-11 as a new pathway potentially implicated in GCA. Furthermore, monocytes from patients in remission with treatment showed downregulation of genes involved in inflammatory processes as well as overexpression of GC receptor-target genes. Finally, we identified changes in DNA methylation correlating with alterations in expression levels of genes with a potential role in GCA pathogenesis, such as ITGA7 and CD63, as well as genes mediating the molecular response to GC, including FKBP5, ETS2, ZBTB16 and ADAMTS2. CONCLUSION: Our results revealed profound alterations in the methylation and transcriptomic profiles of monocytes from GCA patients, uncovering novel genes and pathways involved in GCA pathogenesis and in the molecular response to GC treatment.

Longitudinal analysis of blood DNA methylation identifies mechanisms of response to tumor necrosis factor inhibitor therapy in rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is a chronic, immune-mediated inflammatory disease of the joints that has been associated with variation in the peripheral blood methylome. In this study, we aim to identify epigenetic variation that is associated with the response to tumor necrosis factor inhibitor (TNFi) therapy. METHODS: Peripheral blood genome-wide DNA methylation profiles were analyzed in a discovery cohort of 62 RA patients at baseline and at week 12 of TNFi therapy. DNA methylation of individual CpG sites and enrichment of biological pathways were evaluated for their association with drug response. Using a novel cell deconvolution approach, altered DNA methylation associated with TNFi response was also tested in the six main immune cell types in blood. Validation of the results was performed in an independent longitudinal cohort of 60 RA patients. FINDINGS: Treatment with TNFi was associated with significant longitudinal peripheral blood methylation changes in biological pathways related to RA (FDR<0.05). 139 biological functions were modified by therapy, with methylation levels changing systematically towards a signature similar to that of healthy controls. Differences in the methylation profile of T cell activation and differentiation, GTPase-mediated signaling, and actin filament organization pathways were associated with the clinical response to therapy. Cell type deconvolution analysis identified CpG sites in CD4+T, NK, neutrophils and monocytes that were significantly associated with the response to TNFi. INTERPRETATION: Our results show that treatment with TNFi restores homeostatic blood methylation in RA. The clinical response to TNFi is associated to methylation variation in specific biological pathways, and it involves cells from both the innate and adaptive immune systems. FUNDING: The Instituto de Salud Carlos III.

Preparation of Tea Aroma Precursor Glycosides: An Efficient and Sustainable Approach via Chemical Glycosidation.

Tea aroma precursor glycosides are plant-derived natural products with great economic value. However, the preparation of these glycosides remains largely overlooked in the past decades. Herein, we report a mild, efficient, and sustainable chemocatalytic procedure for the production of tea aroma precursor glycosides. During the study of the glycosidation, the catalysts were found to be decisive in the product formation favoring different reaction pathways; in addition, the influence of molecular sieves was elucidated. With regard to these findings, the serious problem of the competing orthoester formation side reaction was successfully overcome with low catalyst loading (1 mol %) and the use of 5 Å molecular sieves, leading to the preparation of a variety of tea aroma precursor ß-d-glucopyranosides and ß-primeverosides on a gram scale in high yields in an economical way. Taken together, the current approach features catalytic glycosidation with non-toxic and low-cost catalysts, demonstrates highly favorable greenness and sustainability, and promises industrial production of tea aroma precursor glycosides.

Vitamin D receptor, STAT3, and TET2 cooperate to establish tolerogenesis.

The active form of vitamin D, 1,25-dihydroxyvitamin D3, induces a stable tolerogenic phenotype in dendritic cells (DCs). This process involves the vitamin D receptor (VDR), which translocates to the nucleus, binds its cognate genomic sites, and promotes epigenetic and transcriptional remodeling. In this study, we report the occurrence of vitamin D-specific DNA demethylation and transcriptional activation at VDR binding sites associated with the acquisition of tolerogenesis in vitro. Differentiation to tolerogenic DCs associates with activation of the IL-6-JAK-STAT3 pathway. We show that JAK2-mediated STAT3 phosphorylation is specific to vitamin D stimulation. VDR and the phosphorylated form of STAT3 interact with each other to form a complex with methylcytosine dioxygenase TET2. Most importantly, pharmacological inhibition of JAK2 reverts vitamin D-induced tolerogenic properties of DCs. This interplay among VDR, STAT3, and TET2 opens up possibilities for modulating DC immunogenic properties in clinics.

Epilepsy progression is associated with cumulative DNA methylation changes in inflammatory genes.

Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is the most common focal epilepsy in adults. It is characterized by alarming rates of pharmacoresistance. Epileptogenesis is associated with the occurrence of epigenetic alterations, and the few epigenetic studies carried out in MTLE-HS have mainly focused on the hippocampus. In this study, we obtained the DNA methylation profiles from both the hippocampus and anterior temporal neocortex of MTLE-HS patients subjected to resective epilepsy surgery and autopsied non-epileptic controls. We assessed the progressive nature of DNA methylation changes in relation to epilepsy duration. We identified significantly altered hippocampal DNA methylation patterns encompassing multiple pathways known to be involved in epileptogenesis. DNA methylation changes were even more striking in the neocortex, wherein pathogenic pathways and genes were common to both tissues. Most importantly, DNA methylation changes at many genomic sites varied significantly with epilepsy duration. Such progressive changes were associated with inflammation-related genes in the hippocampus. Our results suggest that the neocortex, relatively spared of extensive histopathological damage, may also be involved in epilepsy development. These results also open the possibility that the observed neocortical impairment could represent a preliminary stage of epileptogenesis before the establishment of chronic lesions or a consequence of prolonged seizure exposure. Our two-tissue multi-level characterization of the MTLE-HS DNA methylome suggests the occurrence of a self-propagating inflammatory wave of epigenetic dysregulation.

Coordinated glucocorticoid receptor and MAFB action induces tolerogenesis and epigenome remodeling in dendritic cells.

Glucocorticoids (GCs) exert potent anti-inflammatory effects in immune cells through the glucocorticoid receptor (GR). Dendritic cells (DCs), central actors for coordinating immune responses, acquire tolerogenic properties in response to GCs. Tolerogenic DCs (tolDCs) have emerged as a potential treatment for various inflammatory diseases. To date, the underlying cell type-specific regulatory mechanisms orchestrating GC-mediated acquisition of immunosuppressive properties remain poorly understood. In this study, we investigated the transcriptomic and epigenomic remodeling associated with differentiation to DCs in the presence of GCs. Our analysis demonstrates a major role of MAFB in this process, in synergy with GR. GR and MAFB both interact with methylcytosine dioxygenase TET2 and bind to genomic loci that undergo specific demethylation in tolDCs. We also show that the role of MAFB is more extensive, binding to thousands of genomic loci in tolDCs. Finally, MAFB knockdown erases the tolerogenic properties of tolDCs and reverts the specific DNA demethylation and gene upregulation. The preeminent role of MAFB is also demonstrated in vivo for myeloid cells from synovium in rheumatoid arthritis following GC treatment. Our results imply that, once directly activated by GR, MAFB plays a critical role in orchestrating the epigenomic and transcriptomic remodeling that define the tolerogenic phenotype.

Prediction of the Progression of Undifferentiated Arthritis to Rheumatoid Arthritis Using DNA Methylation Profiling.

OBJECTIVE: The term "undifferentiated arthritis (UA)" is used to refer to all cases of arthritis that do not fit a specific diagnosis. A significant percentage of UA patients progress to rheumatoid arthritis (RA), others to a different definite rheumatic disease, and the rest undergo spontaneous remission. Therapeutic intervention in patients with UA can delay or halt disease progression and its long-term consequences. It is therefore of inherent interest to identify those UA patients with a high probability of progressing to RA who would benefit from early appropriate therapy. This study was undertaken to investigate whether alterations in the DNA methylation profiles of immune cells may provide information on the genetically or environmentally determined status of patients and potentially discriminate between disease subtypes. METHODS: We performed DNA methylation profiling of a UA patient cohort, in which progression to RA occurred for a significant proportion of the patients. RESULTS: We found differential DNA methylation in UA patients compared to healthy controls. Most importantly, our analysis identified a DNA methylation signature characteristic of those UA cases that differentiated to RA. We demonstrated that the methylome of peripheral mononuclear cells can be used to anticipate the evolution of UA to RA, and that this methylome is associated with a number of inflammatory pathways and transcription factors. Finally, we designed a machine learning strategy for DNA methylation-based classification that predicts the differentiation of UA toward RA. CONCLUSION: Our findings indicate that DNA methylation profiling provides a good predictor of UA-to-RA progression to anticipate targeted treatments and improve clinical management.

Whole-Genome sequencing and comparative genomics of Mycobacterium spp. from farmed Atlantic and coho salmon in Chile.

Several members of the Mycobacterium genus cause invasive infections in humans and animals. According to a recent phylogenetic analysis, some strains of Mycobacterium salmoniphilum (Msal), which are the main culprit in bacterial outbreaks in freshwater fish aquaculture, have been assigned to a separate branch containing Mycobacterium franklinii (Mfra), another species that causes infections in humans. However, this genus is little studied in an aquaculture context. Here, we isolated four Mycobacterium spp. strains from freshwater cultures of Atlantic and coho salmon in Chile and performed whole-genome sequencing for deep genomic characterization. In addition, we described the gross pathology and histopathology of the outbreaks. Several bioinformatic analyses were performed using the genomes of these four Mycobacterium isolates in conjunction with those of Msal strains, four Msal-like strains, and one Mfra strains, plus 17 other publicly available Mycobacterium genomes. We found that three isolates are clustered into the Msal branch, whereas one isolate clustered with the Mfra/Msal-like strains. We further evaluated the presence of virulence and antimicrobial resistance genes and observed that the four isolates were closely related to the Msal and Msal-like taxa and carried several antimicrobial resistance and virulence genes that are similar to those of other pathogenic members of the Mycobacterium clade. Altogether, our characterization Msal and Msal-like presented here shed new light on the basis of mycobacteriosis provides quantitative evidence that Mycobacterium strains are a potential risk for aquaculture asetiological agents of emerging diseases, and highlight their biological scopes in the aquaculture industry.

Activation-induced deaminase is critical for the establishment of DNA methylation patterns prior to the germinal center reaction.

Activation-induced deaminase (AID) initiates antibody diversification in germinal center B cells by deaminating cytosines, leading to somatic hypermutation and class-switch recombination. Loss-of-function mutations in AID lead to hyper-IgM syndrome type 2 (HIGM2), a rare human primary antibody deficiency. AID-mediated deamination has been proposed as leading to active demethylation of 5-methycytosines in the DNA, although evidence both supports and casts doubt on such a role. In this study, using whole-genome bisulfite sequencing of HIGM2 B cells, we investigated direct AID involvement in active DNA demethylation. HIGM2 naïve and memory B cells both display widespread DNA methylation alterations, of which ∼25% are attributable to active DNA demethylation. For genes that undergo active demethylation that is impaired in HIGM2 individuals, our analysis indicates that AID is not directly involved. We demonstrate that the widespread alterations in the DNA methylation and expression profiles of HIGM2 naïve B cells result from premature overstimulation of the B-cell receptor prior to the germinal center reaction. Our data support a role for AID in B cell central tolerance in preventing the expansion of autoreactive cell clones, affecting the correct establishment of DNA methylation patterns.

Targeting aberrant DNA methylation in mesenchymal stromal cells as a treatment for myeloma bone disease.

Multiple myeloma (MM) progression and myeloma-associated bone disease (MBD) are highly dependent on bone marrow mesenchymal stromal cells (MSCs). MM-MSCs exhibit abnormal transcriptomes, suggesting the involvement of epigenetic mechanisms governing their tumor-promoting functions and prolonged osteoblast suppression. Here, we identify widespread DNA methylation alterations of bone marrow-isolated MSCs from distinct MM stages, particularly in Homeobox genes involved in osteogenic differentiation that associate with their aberrant expression. Moreover, these DNA methylation changes are recapitulated in vitro by exposing MSCs from healthy individuals to MM cells. Pharmacological targeting of DNMTs and G9a with dual inhibitor CM-272 reverts the expression of hypermethylated osteogenic regulators and promotes osteoblast differentiation of myeloma MSCs. Most importantly, CM-272 treatment prevents tumor-associated bone loss and reduces tumor burden in a murine myeloma model. Our results demonstrate that epigenetic aberrancies mediate the impairment of bone formation in MM, and its targeting by CM-272 is able to reverse MBD.

Integrative Analysis Reveals a Molecular Stratification of Systemic Autoimmune Diseases.

OBJECTIVE: Clinical heterogeneity, a hallmark of systemic autoimmune diseases, impedes early diagnosis and effective treatment, issues that may be addressed if patients could be classified into groups defined by molecular pattern. This study was undertaken to identify molecular clusters for reclassifying systemic autoimmune diseases independently of clinical diagnosis. METHODS: Unsupervised clustering of integrated whole blood transcriptome and methylome cross-sectional data on 955 patients with 7 systemic autoimmune diseases and 267 healthy controls was undertaken. In addition, an inception cohort was prospectively followed up for 6 or 14 months to validate the results and analyze whether or not cluster assignment changed over time. RESULTS: Four clusters were identified and validated. Three were pathologic, representing "inflammatory," "lymphoid," and "interferon" patterns. Each included all diagnoses and was defined by genetic, clinical, serologic, and cellular features. A fourth cluster with no specific molecular pattern was associated with low disease activity and included healthy controls. A longitudinal and independent inception cohort showed a relapse-remission pattern, where patients remained in their pathologic cluster, moving only to the healthy one, thus showing that the molecular clusters remained stable over time and that single pathogenic molecular signatures characterized each individual patient. CONCLUSION: Patients with systemic autoimmune diseases can be jointly stratified into 3 stable disease clusters with specific molecular patterns differentiating different molecular disease mechanisms. These results have important implications for future clinical trials and the study of nonresponse to therapy, marking a paradigm shift in our view of systemic autoimmune diseases.

Synthesis of nature product kinsenoside analogues with anti-inflammatory activity.

Kinsenoside is the major bioactive component from herbal medicine with a broad range of pharmacological functions. Goodyeroside A, an epimer of kinsenoside, remains less explored. In this report we chemically synthesized kinsenoside, goodyeroside A and their analogues with glycan variation, chirality inversion at chiral center(s), and bioisosteric replacement of lactone with lactam. Among these compounds, goodyeroside A and its mannosyl counterpart demonstrated superior anti-inflammatory efficacy. Furthermore, goodyeroside A was found to suppresses inflammatory through inhibiting NF-κB signal pathway, effectively. Structure-activity relationship is also explored for further development of more promising kinsenoside analogues as drug candidates.

Epigenomics and transcriptomics of systemic sclerosis CD4+ T cells reveal long-range dysregulation of key inflammatory pathways mediated by disease-associated susceptibility loci.

BACKGROUND: Systemic sclerosis (SSc) is a genetically complex autoimmune disease mediated by the interplay between genetic and epigenetic factors in a multitude of immune cells, with CD4+ T lymphocytes as one of the principle drivers of pathogenesis. METHODS: DNA samples exacted from CD4+ T cells of 48 SSc patients and 16 healthy controls were hybridized on MethylationEPIC BeadChip array. In parallel, gene expression was interrogated by hybridizing total RNA on Clariom™ S array. Downstream bioinformatics analyses were performed to identify correlating differentially methylated CpG positions (DMPs) and differentially expressed genes (DEGs), which were then confirmed utilizing previously published promoter capture Hi-C (PCHi-C) data. RESULTS: We identified 9112 and 3929 DMPs and DEGs, respectively. These DMPs and DEGs are enriched in functional categories related to inflammation and T cell biology. Furthermore, correlation analysis identified 17,500 possible DMP-DEG interaction pairs within a window of 5 Mb, and utilizing PCHi-C data, we observed that 212 CD4+ T cell-specific pairs of DMP-DEG also formed part of three-dimensional promoter-enhancer networks, potentially involving CTCF. Finally, combining PCHi-C data with SSc GWAS data, we identified four important SSc-associated susceptibility loci, TNIP1 (rs3792783), GSDMB (rs9303277), IL12RB1 (rs2305743), and CSK (rs1378942), that could potentially interact with DMP-DEG pairs cg17239269-ANXA6, cg19458020-CCR7, cg10808810-JUND, and cg11062629-ULK3, respectively. CONCLUSION: Our study unveils a potential link between genetic, epigenetic, and transcriptional deregulation in CD4+ T cells of SSc patients, providing a novel integrated view of molecular components driving SSc pathogenesis.