Mannose metabolism and immune regulation:Insights into its therapeutic potential in immunology-related diseases

Mannose,a different isomer of the hydroxyl group at the C-2 position of glucose,shares the same transport carrier protein with glucose to enter cells and participate in the regulation of glucose metabolism.It affects cell growth,differentiation,and function and plays an active role in tumor immunity and inflammatory processes.This paper provides theoretical support for expanding the clinical applications of mannose by exploring its constitution,metabolic pathways,and role in regulating immune cell function and treating immunology-related diseases.

Construction of Chimonanthus praecox(L.)Link Aquaporin CpTIP Plant Expression Vector with Mannose Selection System

[ Objective] The aim was to construct drought and saline-alkaline resistance plant expression vector with mannose as selective agent, and further breed unmarked resilient varieties. [ Method] The plant expression vector was constructed by using Chimonanthus praecox（ L. ）Link aquapor.in CpTIP cDNA and Escherichia coli pmi gene, combined stress resistance gene with mannose positive selection system. [ Result] The test successfully constructed the plant expression vector pPMI：：CpTIP. [ Conclusion] The constructed vector linked advantages of stress resistance gene and mannose positive selection system.

Soluble mannose receptor as a predictor of prognosis of hepatitis B virus-related acute-on-chronic liver failure

BACKGROUND Hepatitis B virus-related acute-on-chronic liver failure(HBV-ACLF)is a syndrome with a high short-term mortality rate,and it is crucial to identify those patients at a high mortality risk clinically.AIM To investigate the clinical value of soluble mannose receptor(sMR)in predicting the 90-day mortality of HBV-ACLF patients.METHODS A total of 43 patients were diagnosed with HBV-ACLF between October 2017 and October 2018 at the Second Hospital of Anhui Medical University,and all of them were enrolled in this retrospective study.Their serum sMR levels were determined using an enzyme-linked immunosorbent assay.Demographic and clinical data,including gender,age,albumin level,total bilirubin(TBIL)level,international normalized ratio,HBV-DNA level,HBV serological markers,procalcitonin level,interleukin-6 level,and model for end-stage liver disease(MELD)score were accessed at the time of diagnosis of HBV-ACLF.A multivariate logistic regression analysis was used to analyze the independent risk factors for mortality.RESULTS Serum sMR level was significantly increased in HBV-ACLF patients compared with chronic hepatitis B patients and healthy controls(P<0.01).When compared with surviving patients,it was higher in those patients who succumbed to HBVACLF(P<0.05).Serum sMR level was positively correlated with MELD score(rs=0.533,P=0.001),HBV-DNA level(rs=0.497,P=0.022),and TBIL level(rs=0.894,P<0.001).Serum sMR level(odds ratio=1.007,95%confidence interval:1.004–1.012,P=0.001)was an independent risk factor for the 90-day mortality in the HBV-ACLF cases.The patients with HBV-ACLF were stratified into two groups in accordance with their serum sMR levels at the baseline(low risk:<99.84 pg/mL and high risk:≥99.84 pg/mL).The 90-day mortality rates were 27.3%in the low-risk group and 87.5%in the high-risk group.Furthermore,sMR level apparently improved the performance of MELD score for predicting the prognosis of patients with HBV-ACLF.CONCLUSION Serum sMR level may be a predictor of the prognosis of HBV-ACLF patients.

Determination of <i>α</i>-1,3-Linked Mannose Residue in the Cell Wall Mannan of <i>Candida tropicalis</i>NBRC 1400 Strain

To investigate the chemical structure of cell wall mannan obtained from pathogenic yeast, Candida tropicalis NBRC 1400 (former antigenic standard strain, IFO 1400). As a result of two-dimensional NMR analysis, it was shown that the mannan of this strain is composed of α-1,6-, α-1,3-, α-1,2- and β-1,2-linked mannose residues. In this research, the mannan was subjected to three degradation procedures, acid-treatment, α-mannosidase, and acetolysis under two conditions in order to determine the chemical structure of the antigenic oligomannosyl side chains in this molecule. The 1H-nuclear magnetic resonance spectra of resultant oligosaccharides, pentaose and hexaose, demonstrated the existence of the oligomannosyl side chains corresponding to Manα1-3Manα1-2Manα1-2Manα1-2Man and Manα1-3Manα1-2Manα1-2Manα1-2Manα1-2Man, respectively, which have previously also been found in Candida albicans serotype A strain mannans. These findings indicate that C. tropicalis and C. albicans serotype A have no significant difference in the chemical structure of these cell wall mannans. Therefore, it can be interpreted that it is extremely difficult to distinguish both species by targeting the antigenic group in these mannans.

The Protective Effect of Arabinose + Mannose on Mice with Acute Liver Injury Induced by CCl_4 and Its Mechanism

[Objectives] Taking mice with acute liver injury induced by CCl_4 as the model,the effect of arabinose + mannose( w/w = 1∶ 1) on mice with acute liver injury induced by CCl_4 was studied. [Methods]60 experimental mice were selected and then randomly divided into normal control,model group and positive group( bifendate 120 mg/kg),high-dose arabinose + mannose group( 800 mg/kg),middle-dose arabinose + mannose group( 400 mg/kg) and low-dose arabinose + mannose group( 200 mg/kg),each group had 10 mice,which were fed adaptively for 1 week. Except normal control group and model group,each treatment group was given medicine by gavage once a day and lasted for7 days according to the dosage of 20 ml/kg. After the last drug,except normal control group,the mice of other groups were injected 10 ml/kg0. 12% CC14 peanut oil through enterocoelia,thereby establishing acute liver injury model. The mice were fasted but not water for 24 h,after that,blood was sampled from mice eyes,then dissected rapidly. The activities of ALT and AST in the serum were determined,the expression levels of TNF-α,IL-1β and IL-6 from the hepatic tissues were detected by enzyme-linked immunosorbent assay( ELISA); then after HE dye,the changes of liver histopathology were observed. [Results]Compared with CCl_4 model,the activities of ALT and AST from the serum of mice from high-dose and middle dose groups decreased significantly( P < 0. 01); the contents of TNF-α,IL-1β and IL-6 from the hepatic tissues of mice decreased significantly( P < 0. 01); the pathological section showed that the liver injury of mice from the combined drug groups showed alleviating trend to varying degrees,in which the liver injury of mice from the high-dose group was the best. [Conclusions] Arabinose + mannose has an obvious protective effect on mice with acute liver injury induced by CCl_4,and its mechanism may relate to anti-inflammatory.

Changes in fetal mannose and other carbohydrates induced by a maternal insulin infusion in pregnant sheep

Background： The importance of non-glucose carbohydrates, especially mannose and inositol, for normal development is increasingly recognized. Whether pregnancies complicated by abnormal glucose transfer to the fetus also affect the regulation of non-glucose carbohydrates is unknown. In pregnant sheep, maternal insulin infusions were used to reduce glucose supply to the fetus for both short （2-wk） and long （8-wk） durations to test the hypothesis that a maternal insulin infusion would suppress fetal mannose and inositol concentrations. We also used direct fetal insulin infusions （1-wk hyperinsulinemic-isoglycemic clamp） to determine the relative importance of fetal glucose and insulin for regulating non-glucose carbohydrates. Results： A maternal insulin infusion resulted in lower maternal （50%, P 〈 0.01） and fetal （35-45%, P 〈 0.01） mannose concentrations, which were highly correlated （r^2 = 0.69, P 〈 0.01）. A fetal insulin infusion resulted in a 50% reduction of fetal mannose （P 〈 0.05）. Neither maternal nor fetal plasma inositol changed with exogenous insulin infusions. Additionally, maternal insulin infusion resulted in lower fetal sorbitol and fructose （P 〈 0.01）. Conclusions： Chronically decreased glucose supply to the fetus as well as fetal hyperinsulinemia both reduce fetal non-glucose carbohydrates. Given the role of these carbohydrates in protein glycosylation and lipid production, more research on their metabolism in pregnancies complicated by abnormal glucose metabolism is clearly warranted.

Highly Selective Preparation of 3-and 6-Modified Mannose/Altrose Derivatives

A highly efficient method to get 3-and 6-modified mannose/ahrose derivatives for oligosaccharide synthesis is described. All the compounds were obtained exclusively with the combinations of 3-and/or 6-hydroxyl protection and/or activation（ including the configuration conversion of 3-carbon atom）.

Size-dependent macrophage-targeting of mannose-modified rosiglitazone liposomes to alleviate inflammatory bowel disease

Inflammatory bowel disease (IBD) is a refractory chronic intestinal inflammatory disease caused by a malfunction of immune system. As the key immune cells in the intestine, macrophages play an important role in maintaining intestinal homeostasis and tissue repair of the IBD. Pharmacological modulation of macrophage function exhibits the promising therapeutic effect for IBD. In this study, mannose-modified liposomes (MAN-LPs) are prepared for macrophage targeting to improve therapeutic efficiency. Rosiglitazone (ROSI) as an agonist of peroxisome proliferators-activated receptor γ (PPAR-γ) is used as the model drug to fabricate different sized liposomes. The impacts of mannose modification and particle size for macrophage targeting are investigated in cells, zebrafish, and mouse models and the therapeutic effects of the MAN-LPs are evaluated on dextran sulfate sodium (DSS)-induced IBD mouse. Compared to unmodified liposome, MAN-LPs display higher uptake by RAW 264.7 cells and better co-localization with macrophage in zebrafish model. Furthermore, MAN-LPs could effectively accumulate in the inflammatory intestinal sites in IBD mouse model. Most importantly, the targeting ability of MAN-LPs is obviously enhanced with the increasing of particle size, whereas the largest MAN-LPs particles achieve the best anti-inflammatory effect in cells, and a higher therapeutic efficiency in IBD mouse model. Therefore, mannose-modified liposome is a promising strategy for macrophage-targeting in IBD treatment. Particle size of MAN-LPs will affect macrophage targeting ability, as well as the therapeutic effect in-vivo.

Mannose metabolism normalizes gut homeostasis by blocking the TNF-α-mediated proinflammatory circuit

Mannose is a naturally occurring sugar widely consumed in the daily diet;however,mechanistic insights into how mannose metabolism affects intestinal inflammation remain lacking.Herein,we reported that mannose supplementation ameliorated colitis development and promoted colitis recovery.Macrophage-secreted inflammatory cytokines,particularly TNF-α,induced pathological endoplasmic reticulum stress(ERS)in intestinal epithelial cells(IECs),which was prevented by mannose via normalization of protein N-glycosylation.By preserving epithelial integrity,mannose reduced the inflammatory activation of colonic macrophages.On the other hand,mannose directly suppressed macrophage TNF-αproduction translationally by reducing the glyceraldehyde 3-phosphate level,thus promoting GAPDH binding to TNF-αmRNA.Additionally,we found dysregulated mannose metabolism in the colonic mucosa of patients with inflammatory bowel disease.Finally,we revealed that activating PMM2 activity with epalrestat,a clinically approved drug for the treatment of diabetic neuropathy,elicited further sensitization to the therapeutic effect of mannose.Therefore,mannose metabolism prevents TNF-α-mediated pathogenic crosstalk between IECs and intestinal macrophages,thereby normalizing aberrant immunometabolism in the gut.

Application of mannose-modified fullerene immunomodulator selectively polarizes tumor-associated macrophages potentiating antitumor immunity

Polarization of tumor associated macrophages(TAMs)has been a promising therapeutic paradigm for tumor.However,how to achieve precise regulation of TAMs and high efficiency of tumor immunotherapy is still a huge challenge.Here,we report dicarboxy fullerene modified with mannose(DCFM)as an immunomodulator to selectively polarize TAMs and prominently boost anti-tumor immunity.The dicarboxy fullerene molecule was synthesized through the Prato reaction and further covalently bonded with mannose,obtaining the DCFM with well-defined structure.Due to the exist of mannose in DCFM,it could accurately recognize mannose receptor in TAMs.Our cellular experiment results showed that mannose modification could notably promote the uptake of DCFM by the immunosuppressive M2-type macrophages that effectively reprogrammed M2-type macrophages into anti-tumor M1-type macrophages,leading to enhance the phagocytosis of tumor cells by macrophages and inhibiting tumor cells migration.Subsequently,we observed that DCFM could significantly distribute into tumor tissues by in vivo fluorescence imaging.Importantly,DCFM exhibited a superior anti-tumor efficiency in the subcutaneous colorectal tumor model.In addition,it showed that DCFM precisely polarized TAMs into M1-type macrophages and actively increased the infiltration of cytotoxic T lymphocytes(CTLs),inducing profound tumor growth inhibition.

High Mannose-Specific Aptamers for Broad-Spectrum Virus Inhibition and Cancer Targeting

High mannose oligosaccharides are characteristic and essential for immune evasion of many viruses and cancer cells.They are potential targets for viral inhibition and cancer diagnosis/therapy.Particularly,high mannose-binding reagents may be a unique asset for fighting the ongoing and mutating SARSCoV-2 virus.Lectins are prevailing reagents for saccharide binding but suffer from inadequate specificity and apparent immunogenicity.Meanwhile,other reagents for the same purpose,such as antibodies and aptamers,have rarely been reported.Herein,using molecularly imprinted magnetic nanoparticles as a potent platform,we report a smart selection method for fine screening of high mannose-specific aptamers.Monovalent aptamers were first effectively screened within eight rounds of selection.Multivalent aptamers,in the forms of dendritic polymer or tetrahedral DNA nanostructure(TDN),were further engineered.The aptamers exhibited high affinity toward the spike protein of SARS-CoV-2 and the envelope protein GP120 of HIV.Both the monovalent aptamer and its TDN form exhibited a certain inhibition effect to the SARS-CoV-2 pseudovirus.On the other hand,both the monovalent aptamer and its dendritic form permitted the recognition of cancer cells over normal cells.Therefore,as unprecedented reagents for broad-spectrum viral inhibition and cancer targeting,these aptamers hold great promise for clinical treatment and diagnosis.

Mannose inhibits the growth of prostate cancer through a mitochondrial mechanism

The limited treatment options for advanced prostate cancer(PCa)lead to the urgent need to discover new anticancer drugs.Mannose,an isomer of glucose,has been reported to have an anticancer effect on various tumors.However,the anticancer effect of mannose in PCa remains unclear.In this study,we demonstrated that mannose inhibits the proliferation and promotes the apoptosis of PCa cells in vitro,and mannose was observed to have an anticancer effect in mice without harming their health.Accumulation of intracellular mannose simultaneously decreased the mitochondrial membrane potential,increased mitochondrial and cellular reactive oxygen species(ROS)levels,and reduced adenosine triphosphate(ATP)production in PCa cells.Mannose treatment of PCa cells induced changes in mitochondrial morphology,caused dysregulated expression of the fission protein,such as fission,mitochondrial 1(FIS1),and enhanced the expression of proapoptotic factors,such as BCL2-associated X(Bax)and BCL2-antagonist/killer 1(Bak).Furthermore,lower expression of mannose phosphate isomerase(MPI),the key enzyme in mannose metabolism,indicated poorer prognosis in PCa patients,and downregulation of MPI expression in PCa cells enhanced the anticancer effect of mannose.This study reveals the anticancer effect of mannose in PCa and its clinical significance in PCa patients.

Toll-like receptor agonists shape the immune responses to a mannose receptor-targeted cancer vaccine

Previous studies have documented that selective delivery of protein antigens to cells expressing mannose receptor （MR） can lead to enhanced immune responses. We postulated that agents that influenced the MR expression level, and the activation and migration status of MR-expressing antigen presenting cells, would modulate immune responses to MR-targeted vaccines. To address this question, we investigated the effect of clinically used adjuvants in human MR transgenic （hMR-Tg） mice immunized with an MR-targeting cancer vaccine composed of the human anti-MR monoclonal antibody B 11 fused with the oncofetal protein, human chorionic gonadotropin beta chain （hCGβ）, and referred to as B 11-hCGβ. We found that humoral responses to low doses of B11-hCGβ could be enhanced by prior administration of GM-CSF, which upregulated MR expression in vivo. However, co-administration of the Toll-like receptor （TLR） agonists, poly-ICLC and/or CpG with B11-hCGβ was required to elicit Thl immunity, as measured by antigen-specific T-cell production of IFN-γ. The TLR agonists were shown to increase the number of vaccine-containing cells in the draining lymph nodes of immunized hMR-Tg mice. In particular, with B11-hCGβand poly-ICLC, a dramatic increase in vaccine-positive cells was observed in the T-ceU areas of the lymph nodes, compared to the vaccine alone or combined with GM-CSF. Importantly, the absence of the TLR agonists during the priming immunization led to antigen-specific tolerance. Therefore, this study provides insight into the mechanisms by which adjuvants can augment immune responses to B11-hCGβ and have implications for the rationale design of clinical studies combining MR-targeted vaccination with TLR agonists.

Fluorescence detection of Escherichia coli on mannose modified ZnTe quantum dots

Rapid detection and identification of Escherichia coli(E.coli)is essential to prevent its quickly spread.In this study,a novel fluorescence probe based on ZnTe quantum dots(QDs)modified by mannose(MAN)had been prepared for the determination of E.coli.The results showed that the obtained QDs showed excellent selectivity toward E.coli,and presented a good linearity in range of 1.0×10~5~1.0×10~8 CFU/mL.The optimum fluorescence intensity for detecting E.coli was found to be at pH 7.0 with a temperature of25℃and incubation time of 20 min.Under these optimum conditions,the detection limit of E.coli was4.6×10~4 CFU/mL.The quenching was discussed to be a static quenching procedure,which was proved by the quenching efficiency of QDs decreased with the temperature increasing.

Recognition of HBV antigens and HBV DNA by dendritic cells

BACKGROUND: Hepatitis B virus (HBV) is a hepatotropic, noncytopathic, DNA virus which can cause acute and chronic infection. Viral persistence is associated with a weak or absent specific immune responses to HBV, particularly the cellular immune response. Dendritic cells (DCs) are professional antigen-presenting cells with a unique T cell stimulatory aptitude that play a crucial role in the instruction of adaptive immune responses upon infection. An impaired function of DCs was suggested by recent studies to account for the T and B cell hyporesponsiveness in chronic HBV infection. This review summarizes recent insights into the recognition of HBV antigens by DCs. DATA SOURCES: Studies were identified by searching MEDLINE and/or PubMed for articles using the key words 'hepatitis B virus (HBV)', 'dendritic cells', 'C-type lectins', 'mannose receptor', 'toll-like receptor', and 'dendritic cell-specific intercellular-adhesion-molecule-3 grabbing nonintegrin (DC-SIGN)' up to December 2009. Additional papers were identified by a manual search of the references from the key articles. RESULTS: DCs play an important role in the progress of hepatitis B, especially in the recognition of HBV. There are three main ways of recognition of HBV antigens by DCs. First, HBV DNA can be recognized by DCs through toll-like receptor 9 (TLR9) which activates the NF-kappa B signal pathway and p38 MAPK to up-regulate the expression of interferon (IFN) regulatory factor 7 (IRF-7) in a manner independent of type I IFN signaling, resulting in secretion of type I IFN and inflammatory cytokines, and induction of DC maturation and the adaptive immune response. Second, HBc/HBeAg cannot be recognized by DCs, but DNA or ssRNA encapsulated within HBcAg can be internalized by DCs through TLRs. Third, HBsAg can be internalized by DCs through the mannose receptor, which lacks the ability to induce DC maturation without the assistance of DC-SIGN. Meanwhile, there is some cross-talk among the three mechanisms, which induces an effective anti-viral response or HBV persistence. CONCLUSIONS: On the basis of these recognition processes, methods have been used to enhance the efficacy of DC-based vaccine against HBV and have been useful in the clinical application of HBV vaccine therapy. But the interactions between HBV antigens/HBV DNA and DCs are not clear, and cross-talk between TLRs and various ligands makes HBV antigen recognition by DCs more complicated. More efforts should be made to define the mechanisms and develop effective vaccines and therapies. (Hepatobiliary Pancreat Dis Int 2010; 9:584-592)

Clinical significance of loss of heterozygosity for M6P/IGF2R in patients with primary hepatocellular carcinoma

AIM:To investigate the relationship between loss of heterozygosity (LOH) for mannose 6-phosphate/insulin- like growth factor 2 receptor (M6P/IGF2R) and the outcomes for primary HCC patients treated with partial hepatectomy. METHODS: The LOH for M6P/IGF2R in primary HCC patients was assessed using six different gene-specific nucleotide polymorphisms. The patients studied were enrolled to undergo partial hepatectomy. RESULTS: M6P/IGF2R was found to be polymorphic in 73.3% (22/30) of the patients, and of these patients, 50.0% (11/22) had tumors showing LOH in M6P/IGF2R. Loss of heterozygosity in M6P/IGF2R was associated with significant reductions in the two year overall survival rate (24.9% vs 65.5%; P = 0.04) and the disease-free survival rate (17.8% vs 59.3%; P = 0.03). CONCLUSION: These results show M6P/IGF2R LOH predicts poor clinical outcomes in surgically resected primary HCC patients.

Rapid Method for the Determination of Total Monosaccharide in <i>Enterobacter cloacae</i>Strains Using Fourier Transform Infrared Spectroscopy

Fourier Transform Infrared Spectroscopy (FTIR) was used to quantify total monosaccharide content in the bacterium Enterobacter cloacae and several of its biofilm mutants. Bacterial biofilm samples were grown on trypticase soy agar, and 30 μL aliquots of aqueous sample bacterial plus biofilm were deposited into the center of barium fluoride crystals and dried at 50°C for 1-hour before being scanned by FTIR. The total amounts of monosaccharides were estimated using the absorbance of the mono-saccharide peak, 1192 - 958 cm–1, and normalized using the amide II peak, 1585 - 1483 cm–1. This method provided a linear correlation between the absorbance of the monosaccharide peak and concentration of monosaccharide in standard monosaccharides, fructose, glucose, mannose, and rhamnose, over a concentration range of 0.5 - 2.0 mg/mL.

Anomeric Proton and Carbon (H1-C1) NMR Chemical Shifts of Antigenic Mannans Obtained from Pathogenic Yeast <i>Candida tropicalis</i>

On two dimensional maps of 1H-13C correlation spectroscopy (H-C COSY) analysis for the mannan of Candida tropicalis, nine cross peaks of anomeric proton and carbon were useful for the purpose of obtaining information on the chemical structure of this molecule. Namely, the mannans was comb-like structure constructed with the linear α-1,6-linked polymannnosyl backbone and several oligomannnosyl side chains composed of α-1,2-, α-1,3-, and β-1,2-linkages. Therefore, in the structural investigation of comb-like mannan, two-dimensional H-C COSY analysis is as useful as two-dimensional nuclear Hartmann-Hahn (HOHAHA) analysis.

MBL2 Gene Polymorphism and the Association with Neonatal Sepsis in Egyptian Neonates, a Case Control Study

Mannose binding lectin (MBL) is an important component of innate immunity particularly in neonates whose adaptive immunity is not fully developed. Polymorphism in MBL2 gene promoter and exon1 determines MBL serum level and function. The aim of this study was to investigate the frequency of different MBL2 genotypes in neonatal sepsis among patients of neonatal intensive care unit (NICU). Two hundred and forty-five neonates were enrolled in this study (127 infected and 118 uninfected controls). Multiplex PCR and double amplification refractory mutation system (dARMS) were used for typing of MBL2 exon1 and promoter respectively. Klebsiella species were the most frequently isolated organisms (22.8%). There is no statistical significance difference in the distribution of different expression genotypes between infected group and controls (P = 0.11). However, prevalence of low MBL2 expression genotypes (XA/O and O/O) was higher in infected patients compared to control group (patients 25.2% and controls 15.3%). Low and medium MBL2 expression genotypes were mostly associated with Gram-negative bacterial infections (18.9% and 22.8%) respectively. A statistically significant association of Gram-negative bacterial infections with low MBL2 expression genotypes was found (P = 0.02). Higher frequency of AB and BB genotypes was observed (31.5% and 7.9%) in patients group compared to control, but without statistical significant difference.

Studies on the Total Synthesis of the Repeat Unit of Candida kefyr IFO 0586 Strain

The repeat unit of Candida kefyr IFO 0586 strain was designed, and a protected pentasaccharide was synthesized by thirteen-step reactions. Trichloroacetoxy was used as leaving group at anomeric carbon.