Carbohydrate-conjugated porphyrin dimers: synthesis and photobiological evaluation for a potential application in one-photon and two-photon photodynamic therapy.

We report the synthesis of bioconjugated zinc porphyrin dimers 1a-e designed as photosensitizers for one-photon and two-photon excited photodynamic therapy. These macrocycles are substituted with carbohydrate units (glucose, mannose, lactose) in order to target tumor cells over-expressing lectin membrane receptors. Polarity, singlet oxygen production and in vitro photocytotoxicity are studied to determine their photodynamic therapy potentiality.

Investigations into an alternate approach to target mannose receptors on macrophages using 4-sulfated N-acetyl galactosamine more efficiently in comparison with mannose-decorated liposomes: an application in drug delivery.

In this study the potential of 2 different ligands, i.e., palmitoyl mannose (Man-Lip) and 4-SO(4)GalNAc (Sulf-Lip) to target resident macrophages was investigated after surface decoration of Amphotericin B (AmB) loaded liposomes. In the case of Sulf-Lip, the 4-SO(4)GalNAc was adsorbed through electrostatic interaction on cationic liposomes, which was confirmed by change in zeta potential from +48.2 ± 3.7 mV for Lip to +12.2 ± 1.3 mV for Sulf-Lip. The mean particle size of Sulf-Lip and Man-Lip was found to be 139.4 ± 7.4 nm and 147.4 ± 8.6 nm, respectively. Flow cytometric data reveal enhanced uptake of Sulf-Lip in both J774 and RAW cell lines in comparison with the uptake of Man-Lip. Intracellular localization studies indicate that the fluorescence intensity of Sulf-Lip was much higher in comparison with that of Man-Lip and Lip formulations. Sulf-Lip and Man-Lip showed significantly higher localization of AmB at all time points in comparison with Lip (P < 0.05) after intravenous (IV) administration. The studies provide evidence that 4-SO(4)GalNAc possesses a promising feature for targeting resident macrophages and its application in the conditions of leishmaniasis is in the offing. FROM THE CLINICAL EDITOR: This in vivo study compares two different ligands to deliver Amphotericin B l(AmB) loaded liposomes to resident macrophages. Targeted approaches showed significantly higher localization of AmB at all time points in comparison to non-targeted liposomes, and future applications in leishmaniasis are already under preparation.

Novel mannopyranoside esters as sterol 14α-demethylase inhibitors: Synthesis, PASS predication, molecular docking, and pharmacokinetic studies.

Direct unimolar one-step valeroylation of methyl α-d-mannopyranoside (MDM) furnished mainly 6-O-valeroate. However, similar reaction catalyzed by DMAP resulted 3,6-di-O-valeroate (21%) and 6-O-valeroate (47%) indicating reactivity sequence as 6-OH>3-OH>2-OH,4-OH. To get potential antimicrobial agents, 6-O-valeroate was converted into four 2,3,4-di-O-acyl esters, and 3,6-di-O-valeroate was converted into 2,4-di-O-acetate. Direct tetra-O-valeroylation of MDM gave a mixture of 2,3,4,6-tetra-O-valeroate and 2,3,6-tri-O-valeroate indicating that the C2-OH is more reactive than the equatorial C4-OH. The activity spectra analysis along with in vitro antimicrobial evaluation clearly indicated that these novel MDM esters had better antifungal activities over antibacterial agents. In this connection, molecular docking indicated that these MDM esters acted as competitive inhibitors of sterol 14α-demethylase (CYP51), an essential enzyme for clinical target to cure several infectious diseases. Furthermore, pharmacokinetic studies revealed that these MDM esters may be worth considering as potent candidates for oral and topical administration. Structure activity relationship (SAR) affirmed that saturated valeric chain (C5) in combination with caprylic (C8) chains was more promising CYP51 inhibitor over conventional antifungal antibiotics.

Hybrid (2D/3D) Dosimetry of Radiolabeled Gold Nanoparticles for Sentinel Lymph Node Detection in Patients with Breast Cancer.

Previously, we reported the preparation and preclinical studies of 99mTc-labeled gold nanoparticles-mannose (99mTc-AuNP-mannose) with potential for sentinel lymph node (SLN) detection by using nuclear medicine procedures. This study aimed to evaluate the biokinetics and hybrid (2D/3D) dosimetry of 99mTc-AuNP-mannose in five patients with breast cancer under a sentinel lymph node detection protocol. Anterior and posterior whole-body planar images (2D, at 0.5, 2, 6, and 24 h) and single-photon emission computed tomography (3D at 6.5 h)/computed tomography (SPECT/CT) images were acquired after 99mTc-AuNP-mannose administration (37 MBq). Through a hybrid quantification method, activity in tissues of interest at the different acquisition times was determined and integrated over time to obtain the total nuclear transformations (N), as well as the mean residence time, in each tissue. N values and the OLINDA code were used for estimating the internal radiation absorbed doses. Results demonstrated that 99mTc-AuNP-mannose successfully accumulates and remains up to 24 h in the sentinel lymph node without detectable migration to other lymph nodes and no side effects on patients. Negligible absorption of the radiolabeled nanoparticles into the circulatory system was observed, from which the radio-nanosystem is rapidly eliminated by kidneys. Hybrid (2D/3D) dosimetry evaluations showed equivalent doses to SLN, breast, and kidneys of 172.34, 5.32, and 0.08 mSv/37 MBq, respectively, with an effective dose of 2.05E - 03 mSv/MBq. The mean effective residence time in SLN was 0.92 h. This preliminary study indicates that the use of 99mTc-AuNP-mannose for successful SLN detection in patients is safe, producing an effective dose at the level recommended for diagnostic studies (<10 mSv).

Mannose-anchored N,N,N-trimethyl chitosan nanoparticles for pulmonary administration of etofylline.

Drug delivery to lungs via pulmonary administration offers potential for the development of new drug delivery systems. Here we fabricated the etofylline (ETO) encapsulated mannose-anchored N,N,N-trimethyl chitosan nanoparticles (Mn-TMC NPs). The prominent characteristics like biocompatibility, controlled release, targeted delivery, high penetrability, enhanced physical stability, and scalability mark Mn-TMC NPs as a viable alternative to various nanoplatform technologies for effective drug delivery. Mannosylation of TMC NPs leads to the evolution of new drug delivery vehicle with gratifying characteristics, and potential benefits in efficient drug therapy. It is widely accepted that following pulmonary administration, the introduction of mannose to the surface of drug nanocarriers provide selective macrophage targeting via receptor-mediated endocytosis. The fabricated Mn-TMC NPs exhibited particle size of 223.3 nm, PDI 0.490, and ζ-potential -19.1 mV, drug-loading capacity 76.26 ± 1.2%, and encapsulation efficiency of 91.75 ± 0.88%. Sustained drug release, biodegradation studies, stability, safety, and aerodynamic behavior revealed the effectiveness of prepared nanoformulation for pulmonary administration. In addition, the in vivo pharmacokinetic studies in Wistar rat model revealed a significant improvement in therapeutic efficacy of ETO, illustrating mannosylation a promising approach for efficient therapy of airway diseases following pulmonary administration.

Azido-galactose outperforms azido-mannose for metabolic labeling and targeting of hepatocellular carcinoma.

Metabolic glycoengineering of unnatural monosaccharides provides a facile method to label cancer cells with chemical tags for glycan imaging and cancer targeting. Multiple types of monosaccharides have been utilized for metabolic cell labeling. However, the comparison of different types of monosaccharides in labeling efficiency and selectivity has not been reported. In this study, we compared N-azidoacetylgalactosamine (GalAz) and N-azidoacetylmannosamine (ManAz) for metabolic labeling of HepG2 hepatocellular carcinoma in vitro and in vivo. GalAz showed higher labeling efficiency at low concentrations, and outperformed ManAz in metabolic labeling of HepG2 tumors in vivo. GalAz mediated labeling of HepG2 tumors with azido groups significantly improved the tumor accumulation of dibenzocyclooctyne (DBCO)-Cy5 and DBCO-doxorubicin conjugate via efficient Click chemistry. This study, for the first time, uncovered the distinct labeling efficiency and selectivity of different unnatural monosaccharides in liver cancers.

Mannosylated graphene oxide as macrophage-targeted delivery system for enhanced intracellular M.tuberculosis killing efficiency.

Tuberculosis (TB), caused by M.tuberculosis (Mtb), has become a top killer among infectious diseases. Enhancing the ability of anti-TB drugs to kill intracellular Mtb in host cells remains a big challenge. Here, an innovative nano-system was developed to increase drug delivery and Mtb-killing efficacy in Mtb-infected macrophages. We employed mannose surface decoration to develop mannosylated and PEGylated graphene oxide (GO-PEG-MAN). Such nano-platform exhibited increased uptake by macrophages via mannose receptor-mediated endocytosis in vitro. Interestingly, drug-loaded GO-PEG-MAN was preferentially up-taken by mannose receptor-expressing mucosal CD14+ macrophages isolated from Mtb-infected rhesus macaques than drug-loaded GO-PEG. Consistently, the drug concentration was also significantly higher in macrophages than that in T and B cells expressing no or low mannose receptor, implicating a useful macrophage/mannose receptor-targeted drug-delivery system relevant to the in vivo settings. Concurrently, rifampicin-loaded GO-PEG-MAN (Rif@GO-PEG-MAN) significantly increased rifampicin uptake, inducing long-lasting higher concentration of rifampicin in macrophages. Such innovative Rif@GO-PEG-MAN could readily get into the lysosomes of the Mtb host cells, where rifampicin underwent an accelerated release in acidic lysosomic condition, leading to explosive rifampicin release after cell entry for more effective killing of intracellular Mtb. Most importantly, Rif@GO-PEG-MAN-enhanced intracellular rifampicin delivery and pharmacokinetics significantly increased the efficacy of rifampicin-driven killing of intracellular BCG and Mtb bacilli in infected macrophages both in vitro and ex vivo. Such innovative nanocarrier approach may potentially enhance anti-TB drug efficacy and reduce drug side effects.

Mannosylated Constructs as a Platform for Cell-Specific Delivery of Bioactive Agents.

Dictating the transport of drug carriers and augmenting the drug concentration at the desired anatomical site with high selectivity are worthwhile pursuits of current pharmaceutical research. Such approaches to drug targeting have been classified into passive and active strategies. As discussed in this article, active targeting promises greater selectivity because it exploits the incorporation of appropriate ligands, which are recognized by the target cells. Ligands, such as folate, peptides, transferrin, antibodies and their fragments, sugar, and sugar-mimetics, etc., with affinity to the molecules typical to or enriched in target tissues, have been investigated in this context. Mannose receptors (MRs) are abundantly expressed on a variety of cells, such as antigen-presenting cells, dendritic cells, and macrophages. Mannose receptors have lectin recognition domains that exhibit a high binding affinity for mannose. As a result, specific recognition of mannose-functionalized constructs has extensively been explored in the cell-specific targeting of drugs, vaccines, and other bioactive agents. This review outlines and discusses the key aspects of synthesis of mannosylated constructs, their mode of cellular uptake and application to targeted delivery of bioactive agents.

Effect of mannose targeting of hydroxyl PAMAM dendrimers on cellular and organ biodistribution in a neonatal brain injury model.

Neurotherapeutics for the treatment of central nervous system (CNS) disorders must overcome challenges relating to the blood-brain barrier (BBB), brain tissue penetration, and the targeting of specific cells. Neuroinflammation mediated by activated microglia is a major hallmark of several neurological disorders, making these cells a desirable therapeutic target. Building on the promise of hydroxyl-terminated generation four polyamidoamine (PAMAM) dendrimers (D4-OH) for penetrating the injured BBB and targeting activated glia, we explored if conjugation of targeting ligands would enhance and modify brain and organ uptake. Since mannose receptors [cluster of differentiation (CD) 206] are typically over-expressed on injured microglia, we conjugated mannose to the surface of multifunctional D4-OH using highly efficient, atom-economical, and orthogonal Cu(I)-catalyzed alkyne-azide cycloaddition (CuAAC) click chemistry and evaluated the effect of mannose conjugation on the specific cell uptake of targeted and non-targeted dendrimers both in vitro and in vivo. In vitro results indicate that the conjugation of mannose as a targeting ligand significantly changes the mechanism of dendrimer internalization, giving mannosylated dendrimer a preference for mannose receptor-mediated endocytosis as opposed to non-specific fluid phase endocytosis. We further investigated the brain uptake and biodistribution of targeted and non-targeted fluorescently labeled dendrimers in a maternal intrauterine inflammation-induced cerebral palsy (CP) rabbit model using quantification methods based on fluorescence spectroscopy and confocal microscopy. We found that the conjugation of mannose modified the distribution of D4-OH throughout the body in this neonatal rabbit CP model without lowering the amount of dendrimer delivered to injured glia in the brain, even though significantly higher glial uptake was not observed in this model. Mannose conjugation to the dendrimer modifies the dendrimer's interaction with cells, but does not minimize its inherent inflammation-targeting abilities.

Inhibition of endothelial cell proliferation by per-O-acetylated mannose conjugates.

BACKGROUND: The inhibition of angiogenesis, defined as the process of new blood vessel formation, represents a promising strategy for treating cancer. MATERIALS AND METHODS: The inhibitory properties of two N-(per-O-acetylated-beta-D- mannopyranosyl)thiophene-2-carboxamides derivatives (AMTCs, [1],[2]), N-(2,3,4,6-tetra-O-ethoxycarbonyl-beta-D-mannopyranosyl)- thiophene-2-carboxamide [3] and of 2,3,4,6-tetra-O-acetyl-beta-D-mannopyranosyl-acetamide [4] on the growth of bovine aortic endothelial cells (BAECs) induced by basic fibroblast growth factor (bFGF) were assessed using a [3H]thymidine incorporation assay. The cellular uptake of AMTCs and the non-acetylated homologue (MTC) into BAEC were compared using mass spectrometry analysis of cell lysates. RESULTS: AMTCs [1],[2]), at 80 microM, reversed the increase of [3H]thymidine incorporation induced by bFGF, suggesting that these compounds inhibited bFGF-induced proliferative response in BAECs. The acetamide [4] was inactive showing the importance of the thiophene carboxamide for biological activity. The results of a study of AMTC uptake into BAEC suggest that AMTC is rapidly converted to its non-acetylated counterpart. CONCLUSION: The promising results obtained with AMTCs as inhibitors of BAEC growth could lead to the development of novel angiogenesis inhibitors.

Effect of mannose density on mannose receptor-mediated cellular uptake of mannosylated O/W emulsions by macrophages.

Carbohydrate grafted emulsions are one of the most promising cell-specific targeting systems for lipophilic drugs. We have previously reported that mannosylated (Man-) emulsions composed of soybean oil, EggPC and cholesten-5-yloxy-N-(4-((1-imino-2-d-thiomannosylethyl)amino)alkyl)formamide (Man-C4-Chol) with a ratio of 70:25:5 were significantly delivered to liver non-parenchymal cells (NPC) via mannose receptor-mediated mechanism after intravenous administration in mice. Since the efficient targeting through a receptor-mediated mechanism is largely controlled by ligand-receptor interaction, the effect of mannose density on Man-emulsions was studied with regard to both the disposition in vivo in mice and the uptake in vitro, using elicited macrophages which express a number of mannose receptors. After intravenous injection, Man-emulsions with 5.0% (Man-5.0-emulsions) and 7.5% (Man-7.5-emulsions) of Man-C4-Chol were rapidly eliminated from the blood circulation and preferentially accumulated in the liver-NPC compared with Man-emulsions with 2.5% of Man-C4-Chol (Man-2.5-emulsions) and bare emulsions (Bare-emulsions). The in vitro study showed increased internalization of Man-5.0- and Man-7.5-emulsions and significant inhibition of uptake in the presence of mannan. The enhanced uptake of Man-emulsions was related to the increasing of Man-C4-Chol content that corresponded to confocal microscopy study. These results suggest that the mannose density of Man-emulsions plays an important role in both cellular recognition and internalization via a mannose receptor-mediated mechanism.

In situ detoxification and continuous cultivation of dilute-acid hydrolyzate to ethanol by encapsulated S. cerevisiae.

Dilute-acid lignocellulosic hydrolyzate was successfully fermented to ethanol by encapsulated Saccharomyces cerevisiae at dilution rates up to 0.5h(-1). The hydrolyzate was so toxic that freely suspended yeast cells could ferment it continuously just up to dilution rate 0.1h(-1), where the cells lost 75% of their viability measured by colony forming unit (CFU). However, encapsulation increased their capacity for in situ detoxification of the hydrolyzate and protected the cells against the inhibitors present in the hydrolyzate. While the cells were encapsulated, they could successfully ferment the hydrolyzate at tested dilution rates 0.1-0.5h(-1), and keep more than 75% cell viability in the worst conditions. They produced ethanol with yield 0.44+/-0.01 g/g and specific productivity 0.14-0.17 g/(gh) at all dilution rates. Glycerol was the main by-product of the cultivations, which yielded 0.039-0.052 g/g. HMF present in the hydrolyzate was converted 48-71% by the encapsulated yeast, while furfural was totally converted at dilution rates 0.1 and 0.2h(-1) and partly at the higher rates. Continuous cultivation of encapsulated yeast was also investigated on glucose in synthetic medium up to dilution rate 1.0 h(-1). At this highest rate, ethanol and glycerol were also the major products with yields 0.43 and 0.076 g/g, respectively. The experiments lasted for 18-21 days, and no damage in the capsules was detected.

Novel PET Imaging of Atherosclerosis with 68Ga-Labeled NOTA-Neomannosylated Human Serum Albumin.

Activated macrophages take up 18F-FDG via glucose transporters, so this compound is useful for atherosclerosis imaging by PET. However, 18F-FDG application is limited for imaging of the heart and brain, in which glucose uptake is high, and in patients with aberrant glucose metabolism. The aims of this study were to confirm that mannosylated human serum albumin (MSA) specifically binds to the mannose receptor (MR) on macrophages and to test the feasibility of 68Ga-labeled NOTA-MSA for PET imaging of atherosclerotic plaques. METHODS: The peritoneal macrophages of C57/B6 mice were collected, incubated with rhodamine B isothiocyanate-MSA (10 µg/mL), and evaluated by confocal microscopy and flow cytometry. The same evaluations were performed after preincubation of the macrophages with anti-CD206 MR blocking antibodies. NOTA-MSA was synthesized by conjugating 2-(p-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid to MSA, followed by labeling with 68Ga. Rabbits with atherosclerotic aorta induced by a 3-mo cholesterol diet and chronic inflammation underwent consecutive PET/CT with 18F-FDG and 68Ga-NOTA-MSA at 2-d intervals. RESULTS: The binding of MSA to MR and its dose-dependent reduction by preincubation with anti-CD206 MR blocking antibody were confirmed. Rhodamine B isothiocyanate and fluorescein isothiocyanate fluorescence colocalized at the atherosclerotic plaque. The 68Ga-NOTA-MSA SUVs of the atherosclerotic aorta were significantly higher than those of the healthy arteries and inferior vena cava and were comparable to those obtained with 18F-FDG. CONCLUSION: These findings suggest that MR-specific 68Ga-NOTA-MSA is effective for detecting atherosclerosis in the aorta and is a promising radiopharmaceutical for imaging atherosclerosis because of the presence of M2 macrophages in atherosclerotic plaques.

Studies of mannose metabolism and effects of long-term mannose ingestion in the mouse.

Dietary mannose is used to treat glycosylation deficient patients with mutations in phosphomannose isomerase (PMI), but there is little information on mannose metabolism in model systems. We chose the mouse as a vertebrate model. Intravenous injection of [2-3H]mannose shows rapid equilibration with the extravascular pool and clearance t(1/2) of 28 min with 95% of the label catabolized via glycolysis in <2 h. Labeled glycoproteins appear in the plasma after 30 min and increase over 3 h. Various organs incorporate [2-3H]mannose into glycoproteins with similar kinetics, indicating direct transport and utilization. Liver and intestine incorporate most of the label (75%), and the majority of the liver-derived proteins eventually appear in plasma. [2-3H]Mannose-labeled liver and intestine organ cultures secrete the majority of their labeled proteins. We also studied the long-term effects of mannose supplementation in the drinking water. It did not cause bloating, diarrhea, abnormal behavior, weight gain or loss, or increase in hemoglobin glycation. Organ weights, histology, litter size, and growth of pups were normal. Water intake of mice given 20% mannose in their water was reduced to half compared to other groups. Mannose in blood increased up to 9-fold (from 100 to 900 microM) and mannose in milk up to 7-fold (from 75 to 500 microM). [2-3H]Mannose clearance, organ distribution, and uptake kinetics and hexose content of glycoproteins in organs were similar in mannose-supplemented and non-supplemented mice. Mannose supplements had little effect on the specific activity of phosphomannomutase (Man-6-P<-->Man-1-P) in different organs, but specific activity of PMI in brain, intestine, muscle, heart and lung gradually increased <2-fold with increasing mannose intake. Thus, long-term mannose supplementation does not appear to have adverse effects on mannose metabolism and mice safely tolerate increased mannose with no apparent ill effects.

Biodistribution characteristics of mannosylated and fucosylated O/W emulsions in mice.

Cell-specific drug delivery is one of the most promising strategies for improving therapeutic efficiency and minimizing systemic toxicity. Carrier systems devoted to receptor-mediated targeting need to be developed. In the case of liver-non-parenchymal cell-specific targeting systems, glycosylated emulsions have been developed as carriers for lipophilic drugs and/or peptides. This present study demonstrates the in vivo disposition behaviour and pharmacokinetic characteristics of mannosylated (Man-) and fucosylated (Fuc-) emulsions incorporated with cholesten-5-yloxy-N-(4-((1-imino-2-D-thiomannosylethyl)amino)alkyl)formamide (Man-C4-Chol) and its fucosylated derivatives (Fuc-C4-Chol), respectively. Man- (or Fuc-) emulsions are composed of soybean oil, EggPC and Man-C4-Chol (or Fuc-C4-Chol) in a weight ratio of 70:25:5. After intravenous administration to mice, these two types of [(3)H]cholesteryl hexadecyl ether (CHE)-labelled glycosylated emulsions were rapidly eliminated from the blood circulation and preferentially recovered in the liver. In contrast, bare (Bare-) emulsions composed of soybean oil:EggPC:cholesterol (Chol) in a weight ratio of 70:25:5 were more retained in the blood circulation. The hepatic uptake clearances of Man- and Fuc-emulsions were 3.3- and 4.0-times greater than that of Bare-emulsions. Interestingly, the hepatic uptake clearance of Fuc-emulsions was significantly higher that that of Man-emulsions. The uptake ratios by non-parenchymal cells (NPC) and parenchymal cells (PC) (NPC/PC ratio) for Bare-, Man- and Fuc-emulsions were found to be 0.4, 2.0 and 2.9, respectively. The hepatic uptakes of [(3)H]CHE-labelled Man- and Fuc-emulsions were reduced by pre-dosing with glycosylated proteins and liposomes. These results clearly support the conclusion that Man- and Fuc-emulsions are promising carrier systems for liver NPC-specific targeting via receptor-mediated mechanism.

Physiochemical properties, safety and pharmacokinetics of bimosiamose disodium after intravenous administration.

OBJECTIVE: Bimosiamose is a novel synthetic panselectin antagonist being developed for the treatment of acute and chronic inflammatory disorders. Therefore, we have studied the pharmacokinetics and tolerability and determined the pharmacokinetically relevant physicochemical characteristics of bimosiamose. METHOD: A randomized, double-blind, placebo-controlled dose-escalation trial in healthy male subjects has been carried out. The subjects received intravenous infusions of 0.5-30 mg/kg bimosiamose disodium. RESULTS AND CONCLUSIONS: The maximum plasma concentration (Cmax) was 675 +/- 11 microg/ml with a tmax of 0.36 +/- 0.13 h (mean +/- SD). The elimination half-life t1/2 was 4.1 +/- 1.0 h, and the AUC(o-inf) was 1,360 +/- 393 h microg/ml after the 30 mg/kg dose. The clearance and the apparent volume of distribution decreased with increasing dose to 22 +/- 6 ml/kg/h and 40 +/- 13 ml/kg/h at the highest dose, respectively, and the mean residence time increased to 1.8 +/- 0.35 h. Bimosiamose was safe and well-tolerated.

Mannosylated niosomes as carrier adjuvant system for topical immunization.

The aim of this study was to develop mannosylated niosomes as a topical vaccine delivery carrier and adjuvant for the induction of both humoral and cellular immunity. Bovine serum albumin (BSA)-loaded niosomes composed of sorbitan monostearate/sorbitan trioleate (Span 60/Span 85), cholesterol and stearylamine as constitutive lipids were prepared by the reverse-phase evaporation method. The niosomes were coated with a modified polysaccharide O-palmitoyl mannan (OPM) to target them to Langerhan's cells, the major antigen presenting cells found in abundance beneath the stratum corneum. Prepared niosomes were characterized in-vitro for their size, shape, entrapment efficiency and ligand binding specificity. The immune stimulating activity was studied by measuring serum IgG titre and its subclasses (IgG2a/IgG1 ratio) following topical application of various niosomal formulations in albino rats. The results were compared with alum-adsorbed BSA following topical application and intramuscular injection. It was observed that niosomal formulations elicited a significantly higher serum IgG titre upon topical application as compared with topically applied alum adsorbed BSA (P<0.05). The serum IgG levels were significantly higher for the mannosylated niosomes as compared with plain uncoated niosomes (P<0.05). All formulations displayed a combined serum IgG2a/IgG1 response, which suggested that the formulations were capable of eliciting both humoral and cellular responses. The study signified the potential of OPM-coated niosomes as a topical vaccine delivery carrier and adjuvant. The proposed system would be simple, stable, and cost effective and might be clinically acceptable.

A mannose-binding receptor is expressed on human keratinocytes and mediates killing of Candida albicans.

Human keratinocytes are known to kill Candida albicans in vitro, but the mechanism of killing is not yet understood. Here, we demonstrate that spontaneous, ultraviolet-B-light-induced, alpha-melanocyte-stimulating-hormone-induced, and interleukin-8-induced Candida killing by keratinocytes can be inhibited with mannan and mannosylated bovine serum albumin (Man-BSA). A polyclonal goat serum raised against the human macrophage mannose receptor stained suprabasal keratinocytes, but no staining was observed on keratinocytes with a monoclonal antibody (mAb15) specific for the human macrophage mannose receptor. Mannose-affinity chromatography of keratinocyte extract isolated a 200 kDa protein, and on the Western blot the goat antiserum reacted with a 200 kDa protein. In radioligand binding studies, the binding of 125I-Man-BSA to human keratinocytes was inhibited by mannan in a concentration-dependent manner. Analysis of the binding revealed a single class keratinocyte mannose receptor with a KD of 1.4 x 10(-8) M and a Bmax of 1 x 10(4) binding sites per cell. The binding of 125I-Man- BSA to keratinocytes proved to be time-dependent, acid-precipitable, and Ca2+- and trypsin-sensitive. After trypsinization the receptors underwent a rapid recovery at 37 degrees C. These results demonstrate the presence of mannose receptor on human keratinocytes, and its active involvement in the killing of Candida albicans.

Role of the phosphoenolpyruvate-dependent fructose phosphotransferase system in the utilization of mannose by Escherichia coli.

Mutants of Escherichia coli devoid of the membrane-spanning proteins PtsG and PtsMP, which are components of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) and which normally effect the transport into the cells of glucose and mannose, do not grow upon or take up either sugar. Pseudorevertants are described that take up, and grow upon, mannose at rates strongly dependent on the mannose concentration in the medium (apparent Km > 5 mM); such mutants do not grow upon glucose but are derepressed for the components of the fructose operon. Evidence is presented that mannose is now taken up via the fructose-PTS to form mannose 6-phosphate, which is further utilized for growth via fructose 6-phosphate and fructose 1,6-bisphosphate.

Transport of glucose by a phosphoenolpyruvate:mannose phosphotransferase system in Pasteurella multocida.

Pasteurella multocida was examined for glucose and mannose transport. P. multocida was shown to possess a phosphoenolpyruvate (PEP):mannose phosphotransferase system (PTS) that transports glucose as well as mannose and was functionally similar to the Escherichia coli mannose PTS. Phosphorylated proteins with molecular masses similar to those of E. coli mannose PTS proteins were visualized when incubated with 32P-PEP. The presence of an enzyme IIAGlc which could play an important role in regulation, as described in other Gram-negative bacteria, was detected. The enzymes of the pentose-phosphate pathway were present in P. multocida growth on glucose. The activity of 6-phosphofructokinase (the key enzyme of the Embden-Meyerhof pathway (EMP)), was very low in cell extracts, suggesting that EMP is not the major pathway for glucose catabolism.