Inhibition of protein glycosylation is a novel pro-angiogenic strategy that acts via activation of stress pathways.

Endothelial cell (EC) metabolism is thought to be one of the driving forces for angiogenesis. Here we report the identification of the hexosamine D-mannosamine (ManN) as an EC mitogen and survival factor for bovine and human microvascular EC, with an additivity with VEGF. ManN inhibits glycosylation in ECs and induces significant changes in N-glycan and O-glycan profiles. We further demonstrate that ManN and two N-glycosylation inhibitors stimulate EC proliferation via both JNK activation and the unfolded protein response caused by ER stress. ManN results in enhanced angiogenesis in a mouse skin injury model. ManN also promotes angiogenesis in a mouse hindlimb ischemia model, with accelerated limb blood flow recovery compared to controls. In addition, intraocular injection of ManN induces retinal neovascularization. Therefore, activation of stress pathways following inhibition of protein glycosylation can promote EC proliferation and angiogenesis and may represent a therapeutic strategy for treatment of ischemic disorders.

Role of urinary cations in the etiology of interstitial cystitis: A multisite study.

OBJECTIVE: To determine whether patients with interstitial cystitis have elevated levels of toxic urinary cations, to identify and quantify these cationic metabolites, and to assess their cytotoxicity. METHODS: Isolation of cationic fraction was achieved by solid phase extraction using an Oasis MCX cartridge on urine specimens from interstitial cystitis patients and controls. C18 reverse phase high-performance liquid chromatography was used to profile cationic metabolites, and they were quantified by the area under the peaks and normalized to creatinine. Major cationic fraction peaks were identified by reverse phase high-performance liquid chromatography and liquid chromatography-mass spectrometry. HTB-4 urothelial cells were used to determine the cytotoxicity of cationic fraction and of individual metabolites. RESULTS: The reverse phase high-performance liquid chromatography analysis was carried out on cationic fraction metabolites isolated from urine samples of 70 interstitial cystitis patients and 34 controls. The mean for controls versus patients was 3.84 (standard error of the mean 0.20) versus 6.71 (0.37) mAU*min/µg creatinine, respectively (P = 0.0001). The cationic fraction cytotoxicity normalized to creatinine for controls versus patients in mean percentage was -7.79% (standard error of the mean 3.32%) versus 20.03% (standard error of the mean 2.75%; P < 0.0005). The major toxic cations were 1-methyladenosine, 1-methylguanine, N2 ,N2 -dimethylguanosine and L-tryptophan. CONCLUSIONS: These data confirm significant elevation of toxic cations in the urine of interstitial cystitis patients. These toxic cations likely represent a primary cause of interstitial cystitis, as they can injure the bladder mucus and initiate an epithelial leak.

A gut microbial factor modulates locomotor behaviour in Drosophila.

While research into the biology of animal behaviour has primarily focused on the central nervous system, cues from peripheral tissues and the environment have been implicated in brain development and function1. There is emerging evidence that bidirectional communication between the gut and the brain affects behaviours including anxiety, cognition, nociception and social interaction1-9. Coordinated locomotor behaviour is critical for the survival and propagation of animals, and is regulated by internal and external sensory inputs10,11. However, little is known about how the gut microbiome influences host locomotion, or the molecular and cellular mechanisms involved. Here we report that germ-free status or antibiotic treatment results in hyperactive locomotor behaviour in the fruit fly Drosophila melanogaster. Increased walking speed and daily activity in the absence of a gut microbiome are rescued by mono-colonization with specific bacteria, including the fly commensal Lactobacillus brevis. The bacterial enzyme xylose isomerase from L. brevis recapitulates the locomotor effects of microbial colonization by modulating sugar metabolism in flies. Notably, thermogenetic activation of octopaminergic neurons or exogenous administration of octopamine, the invertebrate counterpart of noradrenaline, abrogates the effects of xylose isomerase on Drosophila locomotion. These findings reveal a previously unappreciated role for the gut microbiome in modulating locomotion, and identify octopaminergic neurons as mediators of peripheral microbial cues that regulate motor behaviour in animals.

Increased toxic urinary cations in males with interstitial cystitis: a possible cause of bladder symptoms.

PURPOSE: To identify and quantify toxic urinary cations in male patients with bladder pain syndrome/interstitial cystitis versus male controls, to compare them in symptomatic patients to those significantly improved, and to evaluate cytotoxicity of these cations to cultured urothelial cells to determine whether Tamm-Horsfall protein (THP) can neutralize the cations. METHODS: Isolation of cationic fraction (CFs) was achieved by solid phase extraction on urine specimens of 51 male patients with IC and 33 male controls. C18 reverse-phase high-performance liquid chromatography was used to profile and quantify cationic metabolites. Major CF peaks were identified by liquid chromatography-tandem mass spectrometry. HTB-4 urothelial cells were used to determine the cytotoxicity of CFs, individual metabolites, and of metabolite mixture with THP of patient versus THP of control subject. RESULTS: CF content was significantly higher in patients compared to controls (p < 0.001). Patients had higher levels of modified nucleosides, amino acids, and their derivatives compared to controls. Cytotoxicity for control versus patient mean (SEM) percent was 1.7 (2.9) % versus 63.0 (3.7) %, respectively, (p < 0.001). Cytotoxicity of metabolites was reduced in the presence of THP of control compared to THP of patient (p < 0.001). CONCLUSIONS: Patients with IC had significantly higher levels of cationic metabolites with higher cytotoxicity compared to controls. THP of these patients had reduced ability to sequester cytotoxicity of cationic metabolites. Patients who significantly improved on therapy had the same levels and toxicity of cationic metabolites as symptomatic males, suggesting that these cations may be the cause of epithelial dysfunction in IC.

An evaluation of Tamm-Horsfall protein glycans in kidney stone formers using novel techniques.

Tamm-Horsfall protein (THP) is theorized to play a critical role in preventing kidney stone formation. There is conflicting literature on THP analysis in kidney stone patients; therefore, this study was conducted using sensitive and specific bio-analytical techniques to better understand differences in THP, which play a potential role in nephrolithiasis pathogenesis. THP was isolated from urine samples of 34 male and 19 female kidney stone patients and 30 male and 24 female control subjects using diatomaceous earth. Protein was quantified by Superdex-200 size-exclusion chromatography. Sialic acid was determined by 1,2-diamino-4,5-methylenedioxybenzene high-performance liquid chromatography. Neutral and amino sugars were determined by high pH anion-exchange chromatography (HPAEC) with pulsed amperometric detection. THP N-glycans were derivatized with 2-aminobenzamide (2-AB) and profiled by HPAEC with fluorescence detection. N-glycan structures were confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Results indicate that kidney stone patients had 32% lower protein content compared to controls, while sialic acid content was lower by 29 and 24% in male and female kidney stone patients, respectively, compared to controls. The neutral and amino sugars were also lower by 18 and 20% for male and female kidney stone patients, respectively, compared to controls. All results were statistically significant (p<0.001). These results are supported by 2-AB profiling of THP N-glycans and by MALDI-TOF MS of highly sialylated N-glycans in the range of m/z 3000-6000. This study demonstrates quantitative and qualitative differences in THP, which can be crucial contributing factors for nephrolithiasis.

Heparin and alkalinized lidocaine versus alkalinized lidocaine for treatment of interstitial cystitis symptoms.

INTRODUCTION: Interstitial cystitis (IC), sometimes referred to as IC/bladder pain syndrome, is a substantial health care problem. Once considered a rare, orphan disease, it is now believed to be relatively common. This pilot study was undertaken to determine if the combination of heparin and alkalinized lidocaine (heparin-lidocaine) was more efficacious than alkalinized lidocaine at relieving pain and urgency symptoms associated with IC and also capable of yielding higher lidocaine absorption. MATERIALS AND METHODS: A single blind study was conducted on 14 IC patients with a heparin-lidocaine combination versus alkalinized lidocaine instilled intravesically. In a separate study serum lidocaine levels for heparin-alkalinized lidocaine combination versus USP lidocaine only were determined by high performance liquid chromatography. RESULTS: Alkalinized lidocaine and heparin have been reported to provide relief from pain and urgency symptoms associated with IC. The heparin-lidocaine combination significantly reduced the % of bladder pain (38% versus 13%, p = 0.029) and urgency (42% versus 8% p = 0.003) compared to lidocaine. In addition the GAR was significantly better for the heparin-lidocaine combination at both 1 hr % improved (77% versus 50%, p = 0.04) and 24 hrs (57% versus 23%, p = 0.002) after study drug treatment. Serum lidocaine levels for the heparin-lidocaine combination were significantly higher compared to USP lidocaine (unalkalinized). The mean +/- SEM was 0.45 +/- 0.09 µg/mL and 0.20 +/- 0.05 µg/mL, respectively (p = 0.019). CONCLUSIONS: In this pilot study the heparin-lidocaine combination results in significantly better relief of IC symptoms compared to alkalinized lidocaine and the combination yields higher lidocaine absorption than USP lidocaine.

Role of urinary cations in the aetiology of bladder symptoms and interstitial cystitis.

OBJECTIVES: To identify and characterise urinary cationic metabolites, defined as toxic factors, in patients with interstitial cystitis (IC) and in control subjects. To evaluate the cytotoxicity of the urinary cationic metabolite fraction of patients with IC vs control subjects and of individual metabolites in cultured urothelial cells. SUBJECTS AND METHODS: Cationic fractions (CFs) were isolated from the urine specimens of 62 patients with IC and 33 control subjects by solid-phase extraction. CF metabolites were profiled using C18 reverse-phase high performance liquid chromatography (RP-HPLC) with UV detection, quantified by area-under-the-peaks using known standards, and normalized to creatinine. RP-HPLC and liquid chromatography (LC)-mass spectrometry (MS)/tandem MS (MS/MS) were used to identify major CF peaks. HTB-4 urothelial cells were used to determine the cytotoxicity of CFs and of individual metabolites with and without Tamm-Horsfall protein (THP). RESULTS: RP-HPLC analysis showed that metabolite quantity was twofold higher in patients with IC compared with control subjects. The mean (SEM) for control subjects vs patients was 3.1 (0.2) vs 6.3 (0.5) mAU*min/µg creatinine (P < 0.001). LC-MS identified 20 metabolites. Patients with IC had higher levels of modified nucleosides, amino acids and tryptophan derivatives compared with control subjects. The CF cytotoxicity was higher for patients with IC compared with control subjects. The mean (SEM) for control subjects vs patients was -2.3 (2.0)% vs 36.7 (2.7)% (P < 0.001). A total of 17 individual metabolites were tested for their cytotoxicity. Cytotoxicity data for major metabolites were all significant (P < 0.001): 1-methyladenosine (51%), 5-methylcytidine (36%), 1-methyl guanine (31%), N(4)-acetylcytidine (24%), N(7)-methylguanosine (20%) and L-Tryptophan (16%). These metabolites were responsible for higher toxicity in patients with IC. The toxicity of all metabolites was significantly lower in the presence of control THP (P < 0.001). CONCLUSIONS: Major urinary cationic metabolites were characterised and found to be present in higher amounts in patients with IC compared with control subjects. The cytotoxicity of cationic metabolites in patients with IC was significantly higher than in control subjects, and control THP effectively lowered the cytotoxicity of these metabolites. These data provide new insights into toxic factor composition as well as a framework in which to develop new therapeutic strategies to sequester their harmful activity, which may help relieve the bladder symptoms associated with IC.

Tamm-Horsfall protein-associated nucleotides in patients with interstitial cystitis.

UNLABELLED: WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: The nucleotides associated with Tamm-Horsfall protein (THP) identified in this study are 2'(3') isomers, which are uncommon and very little is known about their biochemical pathway and role in interstitial cystitis (IC). The current study provides additional evidence of our earlier finding that THP is abnormal in IC patients. This can adversely affect THP's protective function, and suggests that THP plays a role in the pathogenesis of the disease. OBJECTIVE: To identify and characterise Tamm-Horsfall protein (THP)-associated metabolites present in patients with interstitial cystitis (IC). Identification of these metabolites would give us insight into the complex interaction of THP with urinary metabolites and its effect on the protective function of THP. PATIENTS, SUBJECTS AND METHODS: THP was isolated from the urine specimens of 146 patients with IC and 87 control subjects, and was analysed for total sialic acid (SA) content by 1,2-diamino-4,5-methylenedioxybenzene. 2HCl (DMB)-high performance liquid chromatography (HPLC). THP-associated metabolites were isolated by Superdex-200 size-exclusion chromatography (SEC) as a second peak (SP2) and the SP2 was further fractionated into six major components by C18 reverse phase-HPLC. Ion-pair HPLC analysis was performed to identify and quantify THP-associated metabolites. The metabolite structures were confirmed by reversed-phase HPLC combined with electrospray ionization (ESI), liquid chromatography-tandem mass spectrometry (LC-MS and LC-MS/MS) and by high-resolution ESI-time of flight mass spectrometry (HR-ESI-TOFMS). RESULTS: The THP-associated metabolites (SP2) were more prevalent in patients with IC than in the controls (40.4% vs 12.6%, P < 0.001) as determined by Superdex-200 SEC. Superdex-200 SEC showed higher SP2 content in patients with IC than in controls, as determined by area under the peak/100 µg of THP. The mean (sem), for patients was 84.3 (8.1) vs 18.0 (2.4) milli-absorption unit*min, for controls (P < 0.001). Total SA content of THP was much lower in SP2-positive patients with IC than those who were SP2-negative. The mean (sem) was 41.6 (3.2) vs 92.6 (2.2) nmol/mg THP, respectively (P < 0.001). Ion-pair HPLC identified SP2 metabolites as nucleotides, namely 5'-CMP, 3'-UMP, 3'-AMP, 3'-GMP, 2'-AMP and 2'-GMP. The total nucleotide content of SP2 was significantly higher in patients with IC than in controls. The mean (sem) was 25.3 (2.9) vs 2.2 (0.2) µg/mg THP, respectively (P < 0.001). LC-MS and LC-MS/MS confirmed the nucleotides based on retention time on HPLC, and mass to charge ratio (m/z) of the parent ion and the daughter ions. HR-ESI-TOFMS gave further confimation of the nucleotide sturctures with high mass accuracy. CONCLUSIONS: In the THP of patients with IC, there is a direct correlation between reduced SA levels and high prevalence of nucleotides associated with it. The THP of patients with IC has a much higher content of these nucleotides than control, and these unique nucleotide isomers identified are very consistent in all SP2-positive patients with IC, suggesting biological significance. This study provides additional evidence that THP is abnormal in patients with IC.

Solubility of ammonium acid urate nephroliths from bottlenose dolphins (Tursiops truncatus).

Nephrolithiasis has been identified in managed populations of bottlenose dolphins (Tursiops truncatus); most of these nephroliths are composed of 100% ammonium acid urate (AAU). Several therapies are being investigated to treat and prevent nephrolithiasis in dolphins including the alkalization of urine for dissolution of nephroliths. This study evaluates the solubility of AAU nephroliths in a phosphate buffer, pH range 6.0-8.0, and in a carbonate-bicarbonate buffer, pH range 9.0-10.8. AAU nephroliths were obtained from six dolphins and solubility studies were conducted using reverse-phase high performance liquid chromatography with ultraviolet detection at 290 nm. AAU nephroliths were much more soluble in a carbonate-bicarbonate buffer, pH range 9.0-10.8 compared to phosphate buffer pH range 6.0-8.0. In the pH range 6.0-8.0, the solubility was 45% lower in potassium phosphate buffer compared to sodium phosphate buffer. When citrate was used along with phosphate in the same pH range, the solubility was improved by 13%. At pH 7 and pH 8, 150 mM ionic strength buffer was optimum for dissolution. In summary, adjustment of urinary pH alone does not appear to be a useful way to treat AAU stones in bottlenose dolphins. Better understanding of the pathophysiology of AAU nephrolithiasis in dolphins is needed to optimize kidney stone prevention and treatment.

A multi-site study confirms abnormal glycosylation in the Tamm-Horsfall protein of patients with interstitial cystitis.

PURPOSE: We confirm the single site observation of decreased sialylation and abnormal glycosylation of Tamm-Horsfall protein in patients with interstitial cystitis compared to control subjects. MATERIALS AND METHODS: Urine samples from 41 controls and 48 patients with interstitial cystitis from a total of 5 North American sites were obtained in blinded fashion as to participant status. Tamm-Horsfall protein was isolated from urine samples by salt precipitation. Protein content was determined by size exclusion chromatography and normalized to creatinine. Sialic acid was quantified by 1,2-diamino-4,5-methylene dioxybenzene (Sigma®) high performance liquid chromatography with fluorescence detection. Neutral and amino sugars were determined by high pH anion exchange chromatography with pulsed amperometric detection. N-glycans were labeled with 2-aminobenzamide and profiled using high pH anion exchange chromatography with fluorescence detection. Samples were also analyzed by matrix assisted laser desorption/ionization-time of flight mass spectrometry. Permethylated N-glycans were analyzed in the mass-to-charge ratio range of 3,000 to 6,000. RESULTS: There was no difference in the protein-to-creatinine ratio of Tamm-Horsfall protein from patients with interstitial cystitis vs controls (49.12 vs 46.4 mg/gm, p = 0.26). Sialic acid content (67 vs 77 nmol/mg Tamm-Horsfall protein, p = 0.025) and total monosaccharide content (590.9 vs 680.6 nmol/mg Tamm-Horsfall protein, p = 0.003) were significantly decreased in patients with interstitial cystitis vs controls. Results were supported by 2-aminobenzamide N-glycan profiling and mass spectrometry, which showed a 45% decrease in a major tetra-sialylated peak (mass-to-charge ratio 4,590) in Tamm-Horsfall protein from patients with interstitial cystitis compared to controls. CONCLUSIONS: These multisite data validate that abnormal glycosylation of Tamm-Horsfall protein occurs in patients with interstitial cystitis and may have a role in interstitial cystitis causation.

Abnormal glycosylation of Tamm-Horsfall protein in patients with interstitial cystitis.

OBJECTIVE: To confirm abnormal glycosylation of Tamm-Horsfall protein (THP) in patients with interstitial cystitis (IC). PATIENTS, SUBJECTS AND METHODS: The sialic acid content of THP, a critical component of its biological activity, is reduced in patients with IC. N-glycan shows reduced levels of high molecular weight tri- and tetra-antennary sialylated oligosaccharides. These results are supported by quantitative monosaccharide analysis of neutral and amino sugars in patients vs control subjects. THP was isolated from urine samples of 23 patients with IC and 24 control subjects by salt precipitation. The sialic acid contents were measured using 1,2-diamino-4,5-methylene dioxybenzene-high performance liquid chromatography analysis. For N-glycan profiling, purified THP was treated with peptide:N-glycosidase F to release N-glycans. The purified N-glycans were labelled with 2-aminobenzamide and were profiled by high-pH anion exchange chromatography (HPAEC) with fluorescence detection. The neutral and amino sugars were determined by HPAEC with pulsed amperometric detection. RESULTS: The total sialic acid in patients was half of that in controls. There was a pattern of reduced level of high molecular weight sialylated oligosaccharide in 17 of 23 patients vs four of 24 controls. The total neutral and amino sugars showed a approximately 30% reduction in patients. The mean (sem) for the controls was 133.79 (6.51) vs 94.76 (6.67) nmol/200 microg of THP for patients (P < 0.001). CONCLUSIONS: THP in patients with IC has reduced sialylation and overall glycosylation, and by inference, THP has a role in the pathophysiology of IC.

Defective Tamm-Horsfall protein in patients with interstitial cystitis.

PURPOSE: Normal urinary Tamm-Horsfall protein shows a urothelial cytoprotective effect against potentially toxic compounds in urine that may injure the urothelium and cause bladder disease. One such disease is interstitial cystitis. In patients with interstitial cystitis this protective effect is decreased. We hypothesized that a difference in Tamm-Horsfall protein in patients with interstitial cystitis exists that may be involved in disease pathogenesis. MATERIALS AND METHODS: Using enzyme-linked immunosorbent assay the urinary Tamm-Horsfall protein concentration was determined in patients with interstitial cystitis and control subjects. Sialic acid content was measured by high performance liquid chromatography based assay. The structure of the protein glycosylation chains was analyzed using matrix assisted laser desorption/ionization-time of flight mass spectrometry. RESULTS: The mean Tamm-Horsfall protein concentration was not significantly different in patients with interstitial cystitis and controls (28.8 vs 28.2 mg/l urine and 36.8 vs 36.7 microg/mg creatinine, respectively, p = 0.6). The total mean sialic acid content of Tamm-Horsfall protein was almost 2-fold lower in 22 patients with interstitial cystitis compared with that in 20 controls (46.3 +/- 4.3 vs 75.3 +/- 4.1 nmol sialic acid per mg Tamm-Horsfall protein, respectively, p <0.0001). On matrix assisted laser desorption/ionization-time of flight mass spectrometry N-glycans released from Tamm-Horsfall protein revealed lower molecular weight di-antennary N-glycan structures and a resulting decrease in the number of terminal sialic acid residues in 10 patients with interstitial cystitis relative to those in 10 controls. CONCLUSIONS: Tamm-Horsfall protein is qualitatively different in patients with interstitial cystitis compared to controls. These data suggest that altered Tamm-Horsfall protein may be involved in interstitial cystitis pathogenesis and it may be useful for clinical diagnosis.

A chemical reporter strategy to probe glycoprotein fucosylation.

Fucosylated glycoproteins are involved in many cell-cell recognition events and are markers of embryonic and malignant tissue. Here we report a method for rapid profiling of fucosylated glycoproteins from human cells using 6-azido fucose as a metabolic label.

Metabolic functionalization of recombinant glycoproteins.

Glycoproteins are essential for cellular communication and are the most rapidly growing class of therapeutic agents. Chemical modification of glycoproteins has been employed to improve their in vivo efficacy or to label them for detection. Methods for the controlled derivatization of glycoproteins are presently limited by the repertoire of natural amino acid side chain and carbohydrate functionalities. Here, we use metabolic oligosaccharide engineering to introduce a bioorthogonal functional group, the azide, into cellular and recombinant glycoproteins for subsequent chemical elaboration via Staudinger ligation. As most therapeutic glycoproteins are sialylated and require this saccharide for optimal pharmacokinetics, we targeted sialic acid as a host for azides using N-azidoacetylmannosamine (ManNAz) as a biosynthetic precursor. Metabolic conversion of ManNAz to N-azidoacetylsialic acid (SiaNAz) within membrane-bound and secreted glycoproteins was quantified in a variety of cell types. SiaNAz was found to comprise between 4% and 41% of total sialosides, depending on the system. Metabolic labeling of recombinant interferon-beta and GlyCAM-Ig was achieved, demonstrating the utility of the method for functionalizing N-linked and O-linked glycoproteins of therapeutic interest. More generally, the generation of recombinant glycoproteins containing chemical handles within their glycans provides a means for studying their behavior and for improving their in vivo efficacy.