Yongxiang Zhang

Toll-like receptor 4-related immunostimulatory polysaccharides: Primary structure, activity relationships, and possible interaction models.

Toll-like receptor (TLR) 4 is an important polysaccharide receptor; however, the relationships between the structures and biological activities of TLR4 and polysaccharides remain unknown. Many recent findings have revealed the primary structure of TLR4/MD-2-related polysaccharides, and several three-dimensional structure models of polysaccharide-binding proteins have been reported; and these models provide insights into the mechanisms through which polysaccharides interact with TLR4. In this review, we first discuss the origins of polysaccharides related to TLR4, including polysaccharides from higher plants, fungi, bacteria, algae, and animals. We then briefly describe the glucosidic bond types of TLR4-related heteroglycans and homoglycans and describe the typical molecular weights of TLR4-related polysaccharides. The primary structures and activity relationships of polysaccharides with TLR4/MD-2 are also discussed. Finally, based on the existing interaction models of LPS with TLR4/MD-2 and linear polysaccharides with proteins, we provide insights into the possible interaction models of polysaccharide ligands with TLR4/MD-2. To our knowledge, this review is the first to summarize the primary structures and activity relationships of TLR4-related polysaccharides and the possible mechanisms of interaction for TLR4 and TLR4-related polysaccharides.

Immune activities comparison of polysaccharide and polysaccharide-protein complex from Lycium barbarum L.

Lycium barbarum L., known as wolfberry, is an important Chinese herbal medicine. In the research, we purified water-soluble polysaccharide-protein complex (LBPF4) and polysaccharide (LBPF4-OL) from the fruiting bodies of L. barbarum L. The monosaccharide and amino acid composition of LBPF4 and LBPF4-OL was elucidated with fractional acid hydrolization, GC/MC and NMR techniques. LBPF4-OL molecular weight was 181 kDa, as determined by high-performance gel-permeation chromatography (HPGPC). In vitro assay, we found that LBPF4 induced splenocyte proliferations depended on both B cells and T cells, but LBPF4-OL induced splenocyte proliferations mainly depended on B cells. ELISA results showed that both LBPF4 and LBPF4-OL significantly induced TNF-α, IL-1β and NO production on macrophage. We also found that both LBPF4 and LBPF4-OL can enhance macrophage phagocytosis. Furthermore, electrophoretic mobility shift assay (EMSA) studies suggest that LBPF4 100 μg/ml treatment can more effectively increase NF-κB activity than LBPF4-OL. Taken together, our results demonstrate that LBPF4 can enhance T, B cells and macrophages functions, but LBPF4-OL can only enhance B cells and macrophage functions. This is partly due to LBPF4 being able to more significantly enhance lymphocytes NF-κB activity.

Lycium barbarum polysaccharide LBPF4-OL may be a new Toll-like receptor 4/MD2-MAPK signaling pathway activator and inducer

Recognition of the utility of the traditional Chinese medicine Lycium barbarum L. has been gradually increasing in Europe and the Americas. Many immunoregulation and antitumor effects of L. barbarum polysaccharides (LBP) have been reported, but its molecular mechanism is not yet clear. In this study, we reported that the activity of the polysaccharide LBPF4-OL, which was purified from LBP, is closely associated with the TLR4-MAPK signaling pathway. We found that LBPF4-OL can significantly induce TNF-α and IL-1β production in peritoneal macrophages isolated from wild-type (C3H/HeN) but not TLR4-deficient mice (C3H/HeJ). We also determined that the proliferation of LBPF4-OL-stimulated lymphocytes from C3H/HeJ mice is significantly weaker than that of lymphocytes from C3H/HeN mice. Furthermore, through a bio-layer interferometry assay, we found that LPS but not LBPF4-OL can directly associate with the TLR4/MD2 molecular complex. Flow cytometry analysis indicated that LBPF4-OL markedly upregulates TLR4/MD2 expression in both peritoneal macrophages and Raw264.7 cells. As its mechanism of action, LBPF4-OL increases the phosphorylation of p38-MAPK and inhibits the phosphorylation of JNK and ERK1/2, as was observed through Western blot analysis. These data suggest that the L. barbarum polysaccharide LBPF4-OL is a new Toll-like receptor 4/MD2-MAPK signaling pathway activator and inducer.

Y27, a novel derivative of 4-hydroxyquinoline-3-formamide, prevents the development of murine systemic lupus erythematosus-like diseases in MRL/lpr autoimmune mice and BDF1 hybrid mice

IntroductionNaturally occurring CD4+CD25+ regulatory T (Treg) cells are central to the maintenance of peripheral tolerance. Impaired activity and/or a lower frequency of these cells lead to systemic lupus erythematosus (SLE). Manipulating the number or activity of Treg cells is to be a promising strategy in treating it and other autoimmune diseases. We have examined the effects of Y27, a novel derivative of 4-hydroxyquinoline-3-formamide, on SLE-like symptoms in MRL/lpr autoimmune mice and BDF1 hybrid mice. Whether the beneficial effect of Y27 involves modulation of CD4+CD25+ Treg cells has also been investigated.MethodsFemale MRL/lpr mice that spontaneously develop lupus were treated orally by gavage with Y27 for 10 weeks, starting at 10 weeks of age. BDF1 mice developed a chronic graft-versus-host disease (GVHD) by two weekly intravenous injections of parental female DBA/2 splenic lymphocytes, characterized by immunocomplex-mediated glomerulonephritis resembling SLE. Y27 was administered to chronic GVHD mice for 12 weeks. Nephritic symptoms were monitored and the percentage of CD4+CD25+FoxP3+ Treg peripheral blood leukocyte was detected with mouse regulatory T cell staining kit by flowcytometry. Purified CD4+CD25+ Tregs were assessed for immune suppressive activity using the mixed lymphocyte reaction.ResultsThe life-span of MRL/lpr mice treated with Y27 for 10 weeks was significantly prolonged, proteinuria and renal lesion severity were ameliorated, and blood urea nitrogen, triglyceride and serum anti-double-stranded DNA antibodies were decreased. Similar results were found in chronic GVHD mice. Administration of Y27 had little impact on percentage of the peripheral blood lymphocyte CD4+CD25+Foxp3+ Treg cells in both groups of mice. In contrast, the suppressive capacity of CD4+CD25+ Treg cells in splenocytes was markedly augmented in Y27-treated mice ex vivo.ConclusionsExperimental evidence of the protect effects of Y27 against autoimmune nephritis has been shown. The mechanism may involve enhancement of the suppressive capacity of CD4+CD25+ Treg cells.

Hemiasterlin Analogues with Unnatural Amino Acids at the N-Terminal and Their Inhibitory Activity on Tumor Cells

Hemiasterlin is a tripeptide with highly alkylated unnatural amino acids. It acts as a potent tumor cell growth inhibitor. From the comparison of the N-terminal between hemiasterlin and its analogues, a further modification was conducted on this position for a SAR study. Some unnatural amino acids with aryl or ureido groups were introduced into the N-terminal of hemiasterlin analogues to improve their hydrophobicity/hydrophilicity. Here 14 hemiasterlin analogues were synthesized. And their activities against tumor cell lines were evaluated. Discussions on SAR preliminarily indicated that no matter whether the N-terminals come from the aryl or alkyl units, sufficient steric bulk, lipophilicity and methylation of the N-terminal should be crucial factors to the cytotoxic activity.

In vivo characterization of a novel GnRH (gonadotropin-releasing hormone) antagonist, LXT-101, in normal male rats

LXT-101 is a newly developed GnRH (gonadotropin-releasing hormone) analogue. In this study, the in vivo pharmacological profile in intact male rats and binding characters of LXT-101 were illustrated, and regulation of mRNA of hormone receptors related to the pituitary-gonadal axis during and after administration was observed to reveal its molecular mechanism of potent effect and reversibility. After single subcutaneous injections, LXT-101 produced a dose- and time-dependent suppression of serum testosterone level. Multiple administrations and osmotic pump implantation revealed that the time of onset and dose needed to maintain the effect of chemical castration decreased as the frequency of injection increased and gave direct proof that depot formulation could significantly improve the duration of antagonist delivery and pharmacological activities compared to the injectable formulation. And LXT-101 showed excellent character of regulating the pituitary-gonadal axis quickly and reversibly. Competitive binding assay showed that LXT-101 could specifically bind a pituitary GnRH receptor with high affinity. These results indicated that LXT-101 is fit for sustained-release formulation and it might possibly be developed as an ideal candidate for treating sex hormone-sensitive tumors and other disorders.

H1521, a novel derivative of 4-hydroxyquinoline-3-carboxamide, suppresses the development of lupus in mice by inducing Th1 cytokine profile in T cells

Transferring parental splenocytes into unirradiated F1 mice induces a chronic graft-versus-host disease (GVHD), characterized by the production of Th2 cytokines and immunocomplex-mediated glomerulonephritis resembling systemic lupus erythematosus (SLE). The effects of H1521, a new derivative of 4-hydroxyquinoline-3-carboxamide, were investigated in chronic GVHD lupus model. H1521 was administered to chronic GVHD mice for 10 weeks. Nephritic symptoms were monitored and cytokine expression in the spleen was detected. To clarify the direct effect of H1521 on CD4(+) T cell, CD4(+) T cells were isolated and co-cultured with H1521 under neutral and Th1 or Th2 driving conditions in vitro. H1521 (32 mg/kg) reduced the incidence of proteinuria by 50% in chronic GVHD mice. Ameliorated lupus symptoms and improved renal histopathology damage were also observed. Administration of H1521 had little impact on Th1 cytokine IL-2 and IFN-gamma or Th2 cytokine IL-4 and IL-10 mRNA expression. In contrast, severely deficient IFN-gamma production by concanavalin A-stimulated spleen cells in chronic GVHD mice was completely restored by H1521. In accordance with this, decreased T-bet mRNA expression became normalized with H1521 (32 mg/kg) treatment. In addition, in vitro studies demonstrated that H1521 preferentially favored Th1 differentiation in CD4(+) T cell and promoted IFN-gamma secretion in Th1 differential CD4(+) T cell. However, IL-4 secretion in naive or Th2 differential CD4(+) T cell was unaffected by H1521. In conclusion, H1521 can induce Th1 cytokine profile in CD4(+) T cells and has possible therapeutic value in Th2-predominant immune diseases.

Studies of Bioactivity, Conformation and Pharmacokinetic Profiles of Site-Specific PEGylated Thymosin Alpha 1 Derivatives

Site-specific mono-PEGylations were performed in different conformational regions of Thymosin alpha 1 (T alpha 1) by introducing one cysteine residue into the chosen site and coupling with thiol-specific mPEG-MAL reagent. Results demonstrated that PEGylated sites and regions influenced the conformations and pharmacokinetic profiles of the peptide greatly with following order: alpha-helix, beta-turn, random coil and terminals, but little on the immunoactivity.

The green tea polyphenol (2)-epigallocatechin-3-gallate (EGCG) is not a β-secretase inhibitor.

(2)-Epigallocatechin-3-gallate (EGCG) is a major polyphenolic component of green tea. A number of studies have demonstrated EGCG has the possibility for delaying the onset or retarding the progression of Alzheimers disease (AD) and indicated EGCG possess inhibition of β-secretase activity. We utilized homogeneous time-resolved fluorescence assay with a substrate Eu-CEVNLDAEFK-Qsy7 to screen β-secretase inhibitor in a cell-free system and AlphaLISA assay in cell system. The results first showed that EGCG had significant inhibition of β-secretase activity with IC(50) value of 7.57 × 10(-7)M in screening assay, but then we found EGCG had significant fluorescence-quenching effect in confirming assay, this indicates EGCG has the false positive β-secretase inhibitory activity. Furthermore, the followed AlphaLISA assay based on cell showed EGCG did not reduce the β-amyloid 1-40 secretion in HuAPPswe/HuBACE1 Chinese hamster ovary cell without affecting cell viability. Therefore our findings indicate EGCG do not inhibit β-secretase cleavage activity. Overall this study illustrates that EGCG is not a β-secretase inhibitor based on the compelling data. This provides further support that the choice of complementary assay format or technology is a critical factor in molecular screening and drug development for improving the hit-finding capability and efficiency.