Mechanism of Action for an All-in-One Monoclonal Antibody Against Staphylococcus aureus Infection

Staphylococcus aureus is a major human pathogen associated with high mortality rates. The extensive use of antibiotics is associated with the rise of drug resistance, and exotoxins are not targeted by antibiotics. Therefore, monoclonal antibody (mAb) therapy has emerged as a promising solution to solve the clinical problems caused by refractory S aureus. Recent research suggests that the synergistic effects of several cytotoxins, including bicomponent toxins, are critical to the pathogenesis of S aureus. By comparing the amino acid sequences, researchers found that α-toxin and bicomponent toxins have high homology. Therefore, we aimed to screen an antibody, designated an all-in-one mAb, that could neutralize α-toxin and bicomponent toxins through hybridoma fusion. We found that this mAb has a significant pharmacodynamic effect within in vivo mouse models and in vitro experiments.

Ssa1-targeted antibody prevents host invasion by Candida albicans

INTRODUCTION

Candida albicans is a commensal fungus that colonizes most healthy individuals' skin and mucosal surfaces but can also cause life-threatening invasive infections, particularly in immunocompromised patients. Despite antifungal treatment availability, drug resistance is increasing, and mortality rates remain unacceptably high. Heat shock protein Ssa1, a conserved member of the Hsp70 family in yeast, is a novel invasin that binds to host cell cadherins, induces host cell endocytosis, and enables C. albicans to cause maximal damage to host cells and induces disseminated and oropharyngeal disease.

RESULT

Here we discovered a mouse monoclonal antibody (mAb 13F4) that targeting C. albicans Ssa1 with high affinity (EC50 = 39.78 ng/mL). mAb 13F4 prevented C. albicans from adhering to and invading human epithelial cells, displayed antifungal activity, and synergized with fluconazole in proof of concept in vivo studies. mAb 13F4 significantly prolonged the survival rate of the hematogenous disseminated candidiasis mice to 75%. We constructed a mAb 13F4 three-dimensional structure using homology modeling methods and found that the antigen-binding fragment (Fab) interacts with the Ssa1 N-terminus.

DISCUSSION

These results suggest that blocking Ssa1 cell surface function may effectively control invasive C. albicans infections and provide a potential new treatment strategy for invasive fungal infections.

Potential of Polyethyleneimine as an Adjuvant To Prepare Long-Term and Potent Antifungal Nanovaccine

Background

Candida albicans infections are particularly prevalent in immunocompromised patients. Even with appropriate treatment with current antifungal drugs, the mortality rate of invasive candidiasis remains high. Many positive results have been achieved in the current vaccine development. There are also issues such as the vaccine's protective effect is not persistent. Considering the functionality and cost of the vaccine, it is important to develop safe and efficient new vaccines with long-term effects. In this paper, an antifungal nanovaccine with Polyethyleneimine (PEI) as adjuvant was constructed, which could elicit more effective and long-term immunity via stimulating B cells to differentiate into long-lived plasma cells.

Materials and Methods

Hsp90-CTD is an important target for protective antibodies during disseminated candidiasis. Hsp90-CTD was used as the antigen, then introduced SDS to "charge" the protein and added PEI to form the nanovaccine. Dynamic light scattering and transmission electron microscope were conducted to identify the size distribution, zeta potential, and morphology of nanovaccine. The antibody titers in mice immunized with the nanovaccine were measured by ELISA. The activation and maturation of long-lived plasma cells in bone marrow by nanovaccine were also investigated via flow cytometry. Finally, the kidney of mice infected with Candida albicans was stained with H&E and PAS to evaluate the protective effect of antibody in serum produced by immunized mice.

Results

Nanoparticles (NP) formed by Hsp90-CTD and PEI are small, uniform, and stable. NP had an average size of 116.2 nm with a PDI of 0.13. After immunizing mice with the nanovaccine, it was found that the nano-group produced antibodies faster and for a longer time. After 12 months of immunization, mice still had high and low levels of antibodies in their bodies. Results showed that the nanovaccine could promote the differentiation of B cells into long-lived plasma cells and maintain the long-term existence of antibodies in vivo. After immunization, the antibodies in mice could protect the mice infected by C. albicans.

Conclusion

As an adjuvant, PEI can promote the differentiation of B cells into long-lived plasma cells to maintain long-term antibodies in vivo. This strategy can be adapted for the future design of vaccines.

Evaluation of the in vitro Activity and in vivo Efficacy of Anidulafungin-Loaded Human Serum Albumin Nanoparticles Against Candida albicans

Recent decades have seen a significant increase in invasive fungal infections, resulting in unacceptably high mortality rates. Anidulafungin (AN) is the newest echinocandin and appears to have several advantages over existing antifungals. However, its poor water solubility and burdensome route of administration (i.e., repeated, long-term intravenous infusions) have limited its practical use. The objective of this study was to develop anidulafungin-loaded Human Serum Albumin (HSA) nanoparticles (NP) so as to increase both its solubility and antifungal efficacy. HSA was reduced using SDS and DTT, allowing liberation of free thiols to form the intermolecular disulfide network and nanoassembly. Reduced HSA was then added to MES buffer (0.1 M, pH 4.8) and magnetically stirred at 350 rpm and 25°C with AN (m/m 50:1) for 2 h to form nanoparticles (AN NP). We next performed routine antifungal susceptibility testing of Candida strains (n = 31) using Clinical and Laboratory Standards Institute (CLSI) methodologies. Finally, the in vivo efficacy of both AN and AN NP was investigated in a murine model of invasive infection by one of the most common fungal species—C. albicans. The results indicated that our carrier formulations successfully improved the water solubility of AN and encapsulated AN, with the latter having a particle size of 29 ± 1.5 nm with Polymer dispersity index (PDI) equaling 0.173 ± 0.039. In vitro AN NP testing revealed a stronger effect against Candida species (n = 31), with Minimum Inhibitory Concentration (MIC) values 4- to 32-fold lower than AN alone. In mice infected with Candida and having invasive candidiasis, we found that AN NP prolonged survival time (P < 0.005) and reduced fungal burden in kidneys compared to equivalent concentrations of free drug (P < 0.0001). In conclusion, the anidulafungin nanoparticles developed here have the potential to improve drug administration and therapeutic outcomes for individuals suffering from fungal diseases.

Preventing Candida albicans from subverting host plasminogen for invasive infection treatment

Candida albicans is a common fungal pathogen in humans that colonizes the skin and mucosal surfaces of the majority healthy individuals. How C. albicans disseminates into the bloodstream and causes life-threatening systemic infections in immunocompromised patients remains unclear. Plasminogen system activation can degrade a variety of structural proteins in vivo and is involved in several homeostatic processes. Here, for the first time, we characterized that C. albicans could capture and “subvert” host plasminogen to invade host epithelial cell surface barriers through cell-wall localized Eno1 protein. We found that the “subverted” plasminogen system plays an important role in development of invasive infection caused by C. albicans in mice. Base on this finding, we discovered a mouse monoclonal antibody (mAb) 12D9 targeting C. albicans Eno1, with high affinity to the ₂₅₄FYKDGKYDL₂₆₂ motif in α-helices 6, β-sheet 6 (H6S6) loop and direct blocking activity for C. albicans capture host plasminogen. mAb 12D9 could prevent C. albicans from invading human epithelial and endothelial cells, and displayed antifungal activity and synergistic effect with anidulafungin or fluconazole in proof-of-concept in vivo studies, suggesting that blocking the function of cell surface Eno1 was effective for controlling invasive infection caused by Candida spp. In summary, our study provides the evidence of C. albicans invading host by “subverting” plasminogen system, suggesting a potential novel treatment strategy for invasive fungal infections.

Dectin-1 Facilitates IL-18 Production for the Generation of Protective Antibodies Against Candida albicans

Invasive candidiasis (IC) is one of the leading causes of death among immunocompromised patients. Because of limited effective therapy treatment options, prevention of IC through vaccine is an appealing strategy. However, how to induce the generation of direct candidacidal antibodies in host remains unclear. Gpi7 mutant C. albicans is an avirulent strain that exposes cell wall β-(1,3)-glucans. Here, we found that vaccination with the gpi7 mutant strain could protect mice against invasive candidiasis caused by C. albicans and non-albicans Candida spp. The protective effects induced by gpi7 mutant relied on long-lived plasma cells (LLPCs) secreting protective antibodies against C. albicans. Clinically, we verified a similar profile of IgG antibodies in the serum samples from patients recovering from IC to those from gpi7 mutant-vaccinated mice. Mechanistically, we found cell wall β-(1,3)-glucan of gpi7 mutant facilitated Dectin-1 receptor dependent nuclear translocation of non-canonical NF-κB subunit RelB in macrophages and subsequent IL-18 secretion, which primed protective antibodies generation in vivo. Together, our study demonstrate that Dectin-1 engagement could trigger RelB activation to prime IL-18 expression and established a new paradigm for consideration of the link between Dectin-1 mediated innate immune response and adaptive humoral immunity, suggesting a previously unknown active vaccination strategy against Candida spp. infection.

Turning weakness into strength: Albumin nanoparticle-redirected amphotericin B biodistribution for reducing nephrotoxicity and enhancing antifungal activity

As the gold standard treatment for invasive fungal infection, amphotericin B (AmB) is limited by its severe nephrotoxicity. It has been shown that AmB complex with albumin in vivo forms a sub-10 nm nanocomplex within kidney excretion size range and eventually induces the nephrotoxicity. This study presents an approach to take advantage of the "weakness" of such unique interaction between AmB and albumin to form AmB nanocomplex beyond the size range of kidney excretion. Herein, a novel strategy was developed by directly assembling molecular BSA into larger-sized nanostructures with the reconstructed intermolecular disulfide bond and hydrophobic interaction. The rich binding sites of AmB within BSA nanostructures enabled the efficient AmB loading and forming nanoparticle (AmB-NP) which exceeds the size range of kidney excretion (~ 60 nm). We found nanoassembly with BSA redirected biodistribution of AmB with a 2.8-fold reduction of drug accumulation in the kidney and significantly improved its renal impairment in mice. Furthermore, we found that nanoassembly with BSA significantly increased the biodistribution of AmB in brain and endowed it 100-folds increase in pharmacological effect against meningoencephalitis caused by common fungal pathogen Cryptococcus neoformans. Together, this study not merely overcomes the nephrotoxicity of AmB using its "weakness" by a nanoassembly method, and provides a new strategy for reducing toxicity of drugs with high albumin binding rate in vivo.

Chemical constituents from the rhizome of Polygonum paleaceum and their antifungal activity

A new compounds neopaleaceolactoside (1), along with nine known compounds phyllocoumarin (2), quercetin (3), quercitrin (4), quercetin-3-methyl ether (5), vincetoxicoside B (6), isoquercitrin (7), kaempferol (8), (-)-epicatechin (9), and chlorogenic acid (10), was isolated from Polygonum paleaceum Wall. Their chemical structures were established based on one-dimensional and two-dimensional nuclear magnetic resonance techniques, mass spectrometry and by comparison with spectroscopic data reported. Some selected compounds were screened for their antifungal activity. Quercetin (3), vincetoxicoside B (6), kaempferol (8), and (-)-epicatechin (9) showed synergistic antifungal activities with the FICI values <0.5. A preliminary structure-activity relationship could be observed that free 3-OH in the structure of flavonoids was important for synergistic antifungal activity.

Heterogeneous evolution of Ty3-gypsy retroelements among bamboo species

Ty3-gypsy long-terminal repeat retroelements are ubiquitously found in many plant genomes. This study reports the occurrence of heterogeneous Ty3-gypsy retroelements in four representative bamboo species: Phyllostachys heterocycla (Carr.) Mitford cv. pubescens, P. heterocycla (Carr.) Mitford cv. heterocycla, Dendrocalamopsis oldhami, and Pleioblastus fortunei. Using degenerate oligonucleotide primers corresponding to the conserved domains of reverse transcriptase (rt) genes of Ty3-gypsy retroelements, 165 distinct sequences were amplified from genomic DNA. The length of the nucleotide sequences varied from 366 to 438 bp. The sequences demonstrated a high heterogeneity, with homology ranging from 52.2 to 99.8%. A phylogenetic tree was constructed, including Arabidopsis thaliana and Oryza sativa. Bamboo Ty3-gypsy sequences formed three distinct retroelement clusters (gypsy I-III). Further analysis indicated that there were not only nearly identical Ty3-gypsy retroelements found in distantly related species, but also highly diverse Ty3-gypsy retroelements observed in closely related species. The results of this study provide genetic and evolutionary information about the bamboo genome that could contribute to further studies of repetitive elements in bamboo as well as in other species.

Identification of genes involved in spontaneous leaf color variation in Pseudosasa japonica

Spontaneous leaf color variation in bamboo provides the opportunity to study the mechanisms of leaf color formation and the breeding of ornamental bamboos. Despite the fact that many genes are known to be involved in leaf color variation in model plants, molecular mechanisms governing natural leaf color variation in bamboo have remained obscure. This study aimed to identify the genes responsible for the occurrence of such phenomena in bamboo using the suppression subtractive hybridization (SSH) method between green and albino leaves in Pseudosasa japonica f. A total of 1062 and 1004 differentially expressed transcripts were obtained from the forward and reverse SSH libraries, respectively. Subsequently, 59 differentially expressed unigenes with potential roles in leaf color formation, predicted via computational analysis of their functional relevance, were selected for further analysis using qPCR. Ten genes, involved in photosynthesis, plastid development, and cation signal transduction, showed 2-fold changes in expression levels between green and albino leaves. Further expression pattern analyses of these genes at three developmental stages revealed much lower expression abundance of Lhca1-encoded chlorophyll a/b binding protein in the albino leaves than in the green leaves. Our results suggest that, together with the concatenated negative pressure for subsequent photosynthetic processes, the albino phenotype is at least partly attributable to chloroplast inner membrane damage or to the impairment of photosynthetic pigment accumulation, which results from low Lhca1 expression.

Probiotic BIFICO cocktail ameliorates Helicobacter pylori induced gastritis

AIM: To determine the protective effect of triple viable probiotics on gastritis induced by Helicobacter pylori (H. pylori) and elucidate the possible mechanisms of protection.

METHODS: Colonization of BIFICO strains in the mouse stomach was determined by counting colony-forming units per gram of stomach tissue. After treatment with or without BIFICO, inflammation and H. pylori colonization in the mouse stomach were analyzed by hematoxylin and eosin and Giemsa staining, respectively. Cytokine levels were determined by enzyme-linked immunosorbent assay and Milliplex. The activation of nuclear factor (NF)-κB and MAPK signaling in human gastric epithelial cells was evaluated by Western blot analysis. Quantitative reverse transcription-polymerase chain reaction was used to quantify TLR2, TLR4 and MyD88 mRNA expression in the mouse stomach.

RESULTS: We demonstrated that BIFICO, which contains a mixture of Enterococcus faecalis, Bifidobacterium longum and Lactobacillus acidophilus, was tolerant to the mouse stomach environment and was able to survive both the 8-h and 3-d courses of administration. Although BIFICO treatment had no effect on the colonization of H. pylori in the mouse stomach, it ameliorated H. pylori-induced gastritis by significantly inhibiting the expression of cytokines and chemokines such as TNF-α, IL-1β, IL-10, IL-6, G-CSF and MIP-2 (P < 0.05). These results led us to hypothesize that BIFICO treatment would diminish the H. pylori-induced inflammatory response in gastric mucosal epithelial cells in vitro via the NF-κB and MAPK signaling pathways. Indeed, we observed a decrease in the expression of the NF-κB subunit p65 and in the phosphorylation of IκB-α, ERK and p38. Moreover, there was a significant decrease in the production of IL-8, TNF-α, G-CSF and GM-CSF (P < 0.05), and the increased expression of TLR2, TLR4 and MyD88 induced by H. pylori in the stomach was also significantly reduced following BIFICO treatment (P < 0.05).

CONCLUSION: Our results suggest that the probiotic cocktail BIFICO can ameliorate H. pylori-induced gastritis by inhibiting the inflammatory response in gastric epithelial cells.

Synthesis and antibacterial activity of 2, 3-dehydro-3-O-(3-aryl-E-prop-2-enyl)-10, 11-anhydroclarithromycin derivatives

An allyl group was attached to 3-keto function of ketolides in the presence of allyl bromide and KOtBu. Consequently, the Heck reaction of the resulting 2, 3-dehydro-3-O-allyl-10, 11-anhydroclarithromycin derivatives, in the presence of palladium (II) acetate and tri(o-tolyl)phosphine, afforded a 3-O-(3-aryl-E-prop-2-enyl) sidechain, not the previously reported 3-O-(3-aryl-Z-prop-1-enyl) sidechain. The results suggested that some steric factors in β-hydrogen elimination might regulate the isomerization. The activity of 2, 3-dehydro-3-O-(3-aryl-E-prop-2-enyl)-10, 11-anhydroclarithromycin derivatives was low.

Iron-Depletion prevents biofilm formation in Pseudomonas Aeruginosa through twitching mobility and quorum sensing

Influence of iron-depletion on twitching motility and quorum sensing (QS) system in P. aeruginosa was evaluated. The results demonstrated iron-depletion can retard biofilm formation and increase the twitching motility and expression of QS-related genes, suggesting a potential interaction between twitching motility and QS system in P. aeruginosa biofilm formation.

Effects of iron depletion on antimicrobial activities against planktonic and biofilm Pseudomonas aeruginosa

Objectives

Iron plays an important role in the development of Pseudomonas aeruginosa biofilm. Here we evaluated effects of iron depletion on the antimicrobial activity of ceftazidime, tobramycin and ciprofloxacin against planktonic and biofilm Pseudomonas aeruginosa.

Methods

We tested the sensitivities of wild-type PAO1, type-IV pilus mutant PAO-ΔpilHIJK and the quorum-sensing mutant PAO-JP2 P. aeruginosa planktonic cultures and biofilms to antibiotics under iron-depleted conditions.

Key findings

In planktonic bacteria, the minimum concentration that inhibited visible growth (MIC) of ciprofloxacin was increased slightly in an iron-depleted environment in all three strains, whereas the MIC of tobramycin was similar in iron-depleted and control environments. The MIC of ceftazidime increased in the PAO-JP2 strain when iron was depleted. Tobramycin achieved the best bactericidal effect in biofilms. Viable counts were reduced by one log under iron-depleted conditions in all three strains when tobramycin reached 4 MIC and when ceftazidime and ciprofloxacin reached 8 MIC.

Conclusions

This study suggests that once the biofilm is formed, iron depletion may only slightly promote the bactericidal effect of antibiotics on PAO1, PAO-ΔpilHIJK and PAO-JP2. Although these changes were relatively small, iron as one of the environmental factors should not be ignored when evaluating bactericidal effect of antibiotics. The combination of an iron chelator and antibiotics may have therapeutic value under certain bacterial growth conditions.

Effects of iron depletion on antimicrobial activities against planktonic and biofilm Pseudomonas aeruginosa

OBJECTIVES

Iron plays an important role in the development of Pseudomonas aeruginosa biofilm. Here we evaluated effects of iron depletion on the antimicrobial activity of ceftazidime, tobramycin and ciprofloxacin against planktonic and biofilm Pseudomonas aeruginosa.

METHODS

We tested the sensitivities of wild-type PAO1, type-IV pilus mutant PAO-DeltapilHIJK and the quorum-sensing mutant PAO-JP2 P. aeruginosa planktonic cultures and biofilms to antibiotics under iron-depleted conditions.

KEY FINDINGS

In planktonic bacteria, the minimum concentration that inhibited visible growth (MIC) of ciprofloxacin was increased slightly in an iron-depleted environment in all three strains, whereas the MIC of tobramycin was similar in iron-depleted and control environments. The MIC of ceftazidime increased in the PAO-JP2 strain when iron was depleted. Tobramycin achieved the best bactericidal effect in biofilms. Viable counts were reduced by one log under iron-depleted conditions in all three strains when tobramycin reached 4 MIC and when ceftazidime and ciprofloxacin reached 8 MIC.

CONCLUSIONS

This study suggests that once the biofilm is formed, iron depletion may only slightly promote the bactericidal effect of antibiotics on PAO1, PAO-DeltapilHIJK and PAO-JP2. Although these changes were relatively small, iron as one of the environmental factors should not be ignored when evaluating bactericidal effect of antibiotics. The combination of an iron chelator and antibiotics may have therapeutic value under certain bacterial growth conditions.

Synergistic effects of aminoglycosides and fosfomycin on Pseudomonas aeruginosa in vitro and biofilm infections in a rat model

OBJECTIVES

To study the in vitro and in vivo efficacy of aminoglycosides against Pseudomonas aeruginosa, either alone or in combination with fosfomycin.

METHODS

Using an in vitro study to assess inhibition of the growth of P. aeruginosa, MIC(90) and MIC(50) values of amikacin, gentamicin, netilmicin, tobramycin and isepamicin were determined, either alone or in combination with fosfomycin, and then the fractional inhibitory concentration index was calculated. In the biofilm-infected rat model, the efficacy and effects of treatment with isepamicin and fosfomycin on infection were studied.

RESULTS

The combinations of amikacin and fosfomycin or isepamicin and fosfomycin showed the most significant synergistic effects against P. aeruginosa as compared with other treatments. In the biofilm-infected rat model, as a single agent, neither isepamicin nor fosfomycin reduced C-reactive protein level and numbers of white blood cells, or reduced the colony counts of the bacteria from both tissue and silica gel tubes. However, the combination of these two agents resulted in a good therapeutic effect.

CONCLUSIONS

Combination of aminoglycosides and fosfomycin not only showed a positive effect in vitro but also improved the therapeutic effect in a biofilm-infected rat model. This offers an effective treatment strategy against some therapy-resistant infections.

Fcr1p inhibits development of fluconazole resistance in Candida albicans by abolishing CDR1 induction

Overexpression of Candida drug resistance 1 (CDR1) gene in Candida albicans (C. albicans), an efflux pump, is one of the major mechanisms contributing to drug resistance. C. albicans for fluconazole resistance 1 protein (Fcr1p) is a member of the family of zinc cluster proteins homologous to Pdr1p and Pdr3p (pleiotropic drug resistance protein) mediating azole resistance in Saccharomyces cerevisiae (S. cerevisiae) by regulating the expression of pleiotropic drug resistance 5 (PDR5) homologous to C. albicans CDR1. A previous study has showed that for fluconazole resistance 1 (FCR1) could also confer azole resistance in S. cerevisiae pdr1 pdr3 mutant by regulating PDR5. Therefore, we investigated the role of FCR1 in the development of C. albicans azole resistance in vitro and in vivo. Our results showed that Fcr1p inhibited fluconazole (FLC) resistance development in C. albicans through abolishing the induction of CDR1 expression by FLC, and in contrast FLC resistance development was accelerated resulting from the deletion of FCR1.

Lymphtoxin beta receptor-Ig protects from T-cell-mediated liver injury in mice through blocking LIGHT/HVEM signaling

LIGHT is a member of the TNF superfamily, which is transiently expressed on the surface of activated T lymphocytes and immature dendritic cells. Its known receptors are herpesvirus entry mediator (HVEM) prominently in T lymphocytes, and lymphtoxin beta receptor (LTbetaR) in stromal cells or nonlymphoid hematopoietic cells. Previous studies have shown that overexpression of LIGHT on T cells could lead to autoimmune reaction including lymphocytes activation, inflammation, and tissue destruction. To address the role of LIGHT/HVEM signaling in autoimmune hepatitis, an experimental colitis model induced by intravenous administration of concanavalin A (ConA) was given a soluble LTbetaR-Ig fusion protein as a competitive inhibitor of LIGHT/HVEM pathway. Marked elevation of LIGHT expression was detected in isolate intrahepatic leukocytes (IHLs) of the experimental animal. Treatment with LTbetaR-Ig significantly attenuated the progression and histological manifestations of the hepatic inflammation and reduced the production of inflammatory cytokines including TNF-alpha, IFN-gamma. Moreover, LTbetaR-Ig treatment significantly down-regulated LIGHT expression, leading to reduced lymphocytes (particularly CD4+ T cells), infiltrating into the hepatic inflammation and inhibited NF-kappaB activation and expression. We postulated that blockade of LIGHT/HVEM signaling by LTbetaR-Ig may ameliorate hepatitis by down-regulating LIGHT expression, and therefore we envision that LTbetaR-Ig would prove to a promising strategy for the clinical treatment of human autoimmune hepatitis.

Antifungal activities and action mechanisms of compounds from Tribulus terrestris L

Antifungal activity of natural products is being studied widely. Saponins are known to be antifungal and antibacterial. We used bioassay-guided fractionation to have isolated eight steroid saponins from Tribulus terrestris L., which were identified as hecogenin-3-O-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-8), tigogenin-3-O-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-9), hecogenin-3-O-beta-D-glucopyranosyl (1-->2)-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-10), hecogenin-3-O-beta-D-xylopyranosyl (1-->3)-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-11), tigogenin-3-O-beta-D-xylopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-[alpha-L-rhamnopyranosyl (1-->2)]-beta-D-galactopyranoside (TTS-12), 3-O-[beta-D-xylopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-[alpha-L-rhamnopyranosyl (1-->2)]-beta-D-galactopyranosyl]-26-O-beta-D-glucopyranosyl-22-methoxy-(3beta,5alpha,25R)-furostan-3,26-diol (TTS-13), hecogenin-3-O-beta-D-glucopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-14), tigogenin-3-O-beta-D-glucopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-15). The in vitro antifungal activities of the eight saponins against five yeasts, Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis and Cryptococcus neoformans were studied using microbroth dilution assay. In vivo activity of TTS-12 in a Candida albicans vaginal infection model was studied in particular. The results showed that TTS-12 and TTS-15 were very effective against several pathogenic candidal species and Cryptococcus neoformans in vitro. It is noteworthy that TTS-12 and TTS-15 were very active against Candida albicans (MIC(80) = 10 and 2.3 microg/mL) and Cryptococcus neoformans (MIC(80) = 1.7 and 6.7 microg/mL). Phase contrast microscopy showed that TTS-12 inhibited hyphal formation, an important virulence factor of Candida albicans, and transmission electron microscopy showed that TTS-12 destroyed the cell membrane of Candida albicans. In conclusion, TTS-12 has significant in vitro and in vivo antifungal activity, weakening the virulence of Candida albicans and killing fungi through destroying the cell membrane.

Lymphtoxin β receptor-Ig ameliorates TNBS-induced colitis via blocking LIGHT/HVEM signaling

LIGHT is a member of the TNF superfamily, which is transiently expressed on the surface of activated T lymphocytes and immature dendritic cells. Its known receptors are herpesvirus entry mediator (HVEM) prominently in T lymphocytes, and lymphtoxin beta receptor (LTbetaR) in stromal cells or nonlymphoid hematopoietic cells. Previous studies have shown that overexpression of LIGHT on T cells could lead to lymphocytes activation, inflammation, and tissue destruction focused on intestinal mucosal tissues. To address the role of LIGHT/HVEM signaling in colonic inflammation, an experimental colitis model induced by rectal administration of trinitrobenzene sulfonic acid (TNBS) was given a soluble LTbetaR-Ig fusion protein as a competitive inhibitor of LIGHT/HVEM pathway. Marked elevation of LIGHT expression was detected in colonic tissue of the experimental colitis. Treatment with LTbetaR-Ig significantly attenuated the progression and histological manifestations of the colonic inflammation and reduced the production of inflammatory cytokines including TNF-alpha, IL-1beta and IL-8. Moreover, LTbetaR-Ig treatment significantly down-regulated LIGHT expression, leading to reduced lymphocytes, particularly CD4+ T cells, infiltrating into the colonic inflammation tissue as shown by histological analysis. In addition, comparison of the therapeutic effects on TNBS-induced colitis between LTbetaR-Ig and mesalazine showed that both treatments were equally efficacious. We postulated that blockade of LIGHT/HVEM signaling by LTbetaR-Ig may ameliorate TNBS-induced colitis by down-regulating LIGHT expression, and therefore we envision that LTbetaR-Ig would prove to a promising strategy for the clinical treatment of inflammatory bowel disease.

In Vitro and in Vivo Antifungal Activities of the Eight Steroid Saponins from Tribulus terrestris L. with Potent Activity against Fluconazole-Resistant Fungal

Antifungal activity of natural products is being studied widely. Saponins are known to be antifungal and antibacterial. We have isolated eight steroid saponins from Tribulus terrestris L., namely TTS-8, TTS-9, TTS-10, TTS-11, TTS-12, TTS-13, TTS-14 and TTS-15. TTS-12 and TTS-15 were identified as tigogenin-3-O-beta-D-xylopyranosyl(1-->2)-[beta-D-xylopyranosyl(1-->3)]-beta-D-glucopyranosyl(1-->4)-[alpha-L-rhamnopyranosyl(1-->2)]-beta-D-galactopyranoside and tigogenin-3-O-beta-D-glucopyranosyl(1-->2)-[beta-D-xylopyranosyl(1-->3)]-beta-D-glucopyranosyl(1-->4)-beta-D-galactopyranoside, respectively. The in vitro antifungal activities of the eight saponins against six fluconazole-resistant yeasts, Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis, Candida krusei, and Cryptococcus neoformans were studied using microbroth dilution assay. The results showed that TTS-12 and TTS-15 were very effective against several pathogenic candidal species and C. neoformans in vitro. It is noteworthy that TTS-12 and TTS-15 were very active against fluconazole-resistant C. albicans (MIC(80)=4.4, 9.4 microg/ml), C. neoformans (MIC(80)=10.7, 18.7 microg/ml) and inherently resistant C. krusei (MIC(80)=8.8, 18.4 microg/ml). So in vivo activity of TTS-12 in a vaginal infection model with fluconazole-resistant C. albicans was studied in particular. Our studies revealed TTS-12 also showed in vivo activities against fluconazole-resistant yeasts. In conclusion, steroid saponins TTS-12 and TTS-15 from Tribulus terrestris L. have significant in vitro antifungal activity against fluconazole-resistant fungi, especially TTS-12 also showed in vivo activity against fluconazole-resistant C. albicans.