Human Chitinases: Structure, Function, and Inhibitor Discovery

The Exploitation of the Glycosylation Pattern in Asthma: How We Alter Ancestral Pathways to Develop New Treatments

Asthma has reached epidemic levels, yet progress in developing specific therapies is slow. One of the main reasons for this is the fact that asthma is an umbrella term for various distinct subsets. Due to its high heterogeneity, it is difficult to establish biomarkers for each subset of asthma and to propose endotype-specific treatments. This review focuses on protein glycosylation as a process activated in asthma and ways to utilize it to develop novel biomarkers and treatments. We discuss known and relevant glycoproteins whose functions control disease development. The key role of glycoproteins in processes integral to asthma, such as inflammation, tissue remodeling, and repair, justifies our interest and research in the field of glycobiology. Altering the glycosylation states of proteins contributing to asthma can change the pathological processes that we previously failed to inhibit. Special emphasis is placed on chitotriosidase 1 (CHIT1), an enzyme capable of modifying LacNAc- and LacdiNAc-containing glycans. The expression and activity of CHIT1 are induced in human diseased lungs, and its pathological role has been demonstrated by both genetic and pharmacological approaches. We propose that studying the glycosylation pattern and enzymes involved in glycosylation in asthma can help in patient stratification and in developing personalized treatment.

Cloning and biochemical characterization of a recombinant chitinase encoded by the CHT4 gene from Candida albicans

As one of the major components in the fungal cell wall, chitin is a polymer of β-1,4-linked N-acetylglucosamine. Chitinases are hydrolytic enzymes that break down glycosidic bonds in the chitin. The human fungal pathogen Candida albicans has three chitinase-encoding genes, CaCHT1, CaCHT2 and CaCHT3. The CaCHT4 gene encodes a protein with the glycoside hydrolase family GH18 domain, Glyco_18, which suggests that CaCht4 might be a chitinase. In the present study, we have cloned, expressed and purified the N-terminally His6-tagged CaCht4 protein from bacterial cells. Further biochemical characterization has shown that this recombinant CaCht4 protein shows both exochitinase (chitobiosidase) and endochitinase activities, but has no N-acetylglucosaminase activity. The optimal temperature for the exochitinase activity of CaCht4 is 55 °C. Taken together, these data support that the CaCHT4 gene encodes a chitinase. Our finding provides a basis for us to understand the biological functions of the CaCHT4 gene in C. albicans.

Chitinase-1 Activity in Serum of Cats with FIP

BACKGROUND

Chitotriosidase (chitinase 1 or CHIT1) is secreted by activated macrophages. Macrophages are involved in the pathogenesis of feline infectious peritonitis (FIP). No reports on CHIT1 activity in cats with FIP are available.

OBJECTIVE

To preliminarily investigate the possible changes in serum CHIT1 activity in cats with FIP.

METHODS

CHIT1 activity was measured in serum samples from clinically healthy cats (n = 17), cats with FIP (n = 19) and cats with diseases potentially characterized by macrophage activation (n = 20), after a preliminary assessment of the imprecision and linearity of the method.

RESULTS

The highest CHIT1 activity was found in cats with FIP, followed by sick cats and clinically healthy cats. The magnitude of the differences between groups was higher than the intra- and inter-assay imprecision of the method (<5% and >57%, respectively). Based on receiver operating characteristic (ROC) curves, CHIT1 may differentiate sick from clinically healthy cats and, to a lesser extent, cats with FIP from cats without FIP.

CONCLUSIONS

CHIT1 activity may identify sick cats and, within the appropriate clinical context, cats with FIP, although larger and more standardized studies, coupled with additional information on analytical performances of the method, are required to fully explore the diagnostic or prognostic potential of this test for FIP.

Bacterial Chitinases and Their Role in Human Infection

It has been widely appreciated that numerous bacterial species express chitinases for the purpose of degrading environmental chitin. However, chitinases and chitin-binding proteins are also expressed by pathogenic bacterial species during infection even though mammals do not produce chitin. Alternative molecular targets are therefore likely present within the host. Here, we will describe our current understanding of chitinase/chitin-binding proteins as virulence factors that promote bacterial colonization and infection. The targets of these chitinases in the host have been shown to include immune system components, mucins, and surface glycans. Bacterial chitinases have also been shown to interact with other microorganisms, targeting the peptidoglycan or chitin in the bacterial and fungal cell wall, respectively. This review highlights that even though the name "chitinase" implies activity toward chitin, chitinases can have a wide diversity of targets, including ones relevant to host infection. Chitinases may therefore be useful as a target of future anti-infective therapeutics.

An overview of fungal chitinases and their potential applications

Chitin, the world's second most abundant biopolymer after cellulose, is composed of β-1,4-N-acetylglucosamine (GlcNAc) residues. It is the key structural component of many organisms, including crustaceans, mollusks, marine invertebrates, algae, fungi, insects, and nematodes. There has been a significant increase in the generation of chitinous waste from seafood businesses, resulting in a big amount of scrap. Although several organisms, such as plants, crustaceans, insects, nematodes, and animals, produce chitinases, microorganisms are promising candidates and a sustainable option that mediates chitin degradation. Fungi are the dominant group of chitinase producers among microorganisms. In fungi, chitinases are involved in morphogenesis, cell division, autolysis, chitin acquisition for nutritional purposes, and mycoparasitism. Many efficient chitinolytic fungi with potential applications have been identified in a variety of environments, including soil, water, marine wastes, and plants. The current review highlights the key sources of chitinolytic fungi and the characterization of fungal chitinases. It also discusses the applications of fungal chitinases and the cloning of fungal chitinase genes.

Circulating 18-Glycosyl Hydrolase Protein Chitiotriosidase-1 is Associated with Renal Dysfunction and Systemic Inflammation in Diabetic Kidney Disease

Introduction

Chitotriosidase-1 (CHIT-1) is a marker of macrophage activation and recently attributed to type 2 diabetes mellitus (T2DM). However, its role in the development and progression of diabetic kidney disease (DKD) has been sparsely discussed in the recent literature.

Materials and Methods

In this cross-sectional exploratory study, 81 participants with T2DM were classified into two groups based on the presence of DKD. Their anthropometric, biochemical, and pathological profiles were estimated. Circulatory CHIT-1 concentration was determined using the enzyme-linked immuno-sorbent assay (ELISA) in plasma.

Results

CHIT-1 was significantly elevated in diabetic nephropathy, independent of age and gender. It is associated with severity of kidney disease, as assessed using urinary protein-creatinine ratio (uPCR) in a multiple linear regression model, independent of age, gender, diabetes duration, and insulin resistance. CHIT-1 positively predicted the likelihood of DKD in the study population (area under the curve = 0.724, P < 0.05). The duration of diabetes correlated positively with uPCR and negatively with estimated glomerular-filtration rate. Neutrophil-Lymphocyte ratio was elevated in participants with DKD. This well-established marker of systemic inflammation exhibited significant positive association with CHIT-1.

Conclusion

Plasma CHIT-1 protein is elevated in DKD and associated with disease progression. It is capable of reflecting disease severity and is closely related to systemic inflammation possibly caused by pro-inflammatory circulatory immune cells.

Cloning, expression, purification and biochemical characterization of the recombinant chitinase enzyme encoded by CTS2 in the budding yeast

Chitin is a polymer of β-1,4-linked N-acetylglucosamine (GlcNAc) and plays a central role in the assembly of the fungal cell wall. Chitinases are hydrolytic enzymes that break down glycosidic bonds in the chitin. Chitinases are classified into three categories, endochitinases, exochitinases and N-acetylglucosaminases, according to the manner in which the enzyme cleaves the chitin polymer. Saccharomyces cerevisiae has two chitinase-encoding genes, CTS1 and CTS2. However, whether Cts2p shows a chitinase activity remains unknown. In this study, we have cloned, expressed and purified the recombinant Cts2p protein from bacterial cells. We have demonstrated that Cts2p has a higher chitobiosidase (exochitinase) activity than endochitinase activity, but no N-acetylglucosaminase activity. The optimal temperature for the chitobiosidase activity of Cts2p is 37 °C.

The synergistic action of two chitinases from Vibrio harveyi on chitin degradation

In this study, two chitinases (VhChit2 and VhChit6) from Vibrio harveyi possessed specific activity of 36.5 and 20.8 U/mg, respectively. Structure analysis indicates that their amino acid composition of active sites is similar, but the substrate binding cleft of VhChit2 is deeper than that of VhChit6. They were shown to have a synergistic effect on chitin degradation, and the optimized degree of synergy and the degradation ratio of chitin reached 1.75 and 23.6 %, respectively. The saturated adsorption capacity of VhChit2 and VhChit6 adsorbed in 1 g of chitin was 48.5 and 33.4 mg. It was found that VhChit2 and VhChit6 had different adsorption sites on chitin, making more enzymes absorbed by chitin. Furthermore, the combined use of VhChit2 and VhChit6 increased their binding force of chitinases with the substrate. The synergistic action of VhChit2 and VhChit6 may be attributed to their different adsorption sites on chitin and the increased binding force with chitin.

Chitotriosidase and Neopterin as Two Novel Potential Biomarkers for Advanced Stage and Survival Prediction in Gastric Cancer—A Pilot Study

Gastric cancer is the fifth type of neoplasia most frequently diagnosed and the fourth cause of death among other cancers. Prevalence is around two times higher for males than females. Chitotriosidase and neopterin are two molecular biomarkers with potential diagnostic and prognostic use in malignant pathology. We conducted a longitudinal prospective cohort study on thirty-nine patients with gastric adenocarcinoma, with a male-to-female ratio of 1.78 and an average age of 64.3 ± 9.97 years. No statistically significant differences in biomarker levels at presentation were observed between curative-intent surgery (28 patients) and advanced cases, suited only for palliative procedures (11 patients). Biomarker values were not significantly different for the advanced T stage and the presence of metastasis (p > 0.05—Mann Whitney test). The patients that died in the first 30 days after surgery did not present significantly different values at baseline, in comparison with those that had longer survival times, though a significant cut-off value was observed for chitotriosidase activity at 310 nmol/mL/h [AUC (area under the curve) = 0.78; 95% CI (0.61–0.92)]. The cut-off values corresponding to death after the first year, tumor invasion, and metastasis were not statistically significant. In the COX multivariate model, neopterin did not validate itself as a prognostic biomarker, however, chitotriosidase activity before surgery was significantly associated with overall survival (HR = 1.0038, p = 0.03). We conclude that chitotriosidase may have the potential to improve the prognostic model for gastric adenocarcinoma.

High chitotriosidase and AGE levels in acromegaly: a case-control study

PURPOSE

Acromegaly is associated with oxidative stress and inflammation parameters. Chitotriosidase (CHITO) is a marker of macrophage activation and plays a pivotal role in the activation of inflammatory and immunological responses. Our study aimed to determine CHITO,YKL-40, advanced glycation end product (AGE), and high-sensitivity C-reactive protein (hsCRP) levels to investigate malondialdehyde (MDA), catalase, superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities and to evaluate any association of these parameters with carotid intima media thickness (cIMT) in patients with controlled acromegaly.

METHODS

Thirty controlled acromegaly patients and 41 age- and sex-matched control cases were studied. We obtained demographic data, hormonal and metabolic parameters, and cIMT. CHITO activity was measured with the fluorometric method of Chamoles et al. YKL-40 and hsCRP levels were measured using ELISA. AGEs were measured based on spectrofluorimetric detection. GSH-Px activity was determined by a colorimetric assay. MDA, SOD, and catalase activities were determined in hemolysis.

RESULTS

Higher CHITO, AGE, and hsCRP concentrations were observed in patients with acromegaly compared to controls. SOD levels were non-significantly higher in the acromegaly group, while catalase activities were lower in patients with acromegaly. Correlation analyses of CHITO, AGEs, YKL-40, hsCRP, MDA, catalase, GSH-Px, and SOD with metabolic, anthropometric, and laboratory parameters did not demonstrate any significant correlation (p > 0.05). There was no significant difference between groups with regard to cIMT levels.

CONCLUSION

This is the first study investigating CHITO and AGE levels in patients with acromegaly. Serum CHITO, AGE, and hsCRP levels in acromegalic patients were significantly increased. It may be important to evaluate CHITO, AGE, and hsCRP levels in acromegalic patients who are already under cardiometabolic surveillance due to risk of developing cardiovascular disease.

Chitotriosidase and Neopterin as Potential Biomarkers for the Evaluation of Complicated Cholecystitis-A Pilot Study

Gallstones are a common surgical pathology. Laparoscopic cholecystectomy represents the elective treatment. Complicated cases can increase the rate of conversion, the duration, and the difficulty of the intervention, along with the hospitalization period. A prospective cohort study was conducted on 51 patients with gallstones. Only subjects with normal renal, pancreatic, and hepatic functions were included. The severity of cholecystitis was evaluated by considering the ultrasound examination, intraoperative findings, and pathology report. We evaluated two potential biomarkers, namely neopterin and chitotriosidase, by comparing their levels before and after the intervention for chronic (n = 36) and complicated (n = 15) cases, as well as their eventual association with the hospitalization period. Subjects with complicated cholecystitis had significantly higher (p = 0.01) neopterin levels at presentation (16.82 nmol/L vs. 11.92 nmol/L, median values), but the differences in chitotriosidase activity between complicated (170.00 nmol/mL/h) and chronic (160.00 nmol/mL/h) cases were not significant (p = 0.66). Patients with neopterin levels above the cut-off value 14.69 nmol/L had a 3.34 times higher risk of complicated cholecystitis. Twenty-four hours after the laparoscopic cholecystectomy, the differences in neopterin level and chitotriosidase activity between chronic and complicated cases were not significant. A significant decrease in chitotriosidase activity was observed after the intervention, only for complicated cases (190 nmol/mL/h vs. 145 nmol/mL/h, p = 0.007); for neopterin, the postoperative decrease was not statistically significant (19.42 nmol/L vs. 10.92 nmol/L, p = 0.06). No significant association with the hospitalization period was observed. Neopterin may be a useful biomarker for complicated cholecystitis, and chitotriosidase may have prognostic utility in early patient follow-up.

Molecular Genetics and Cytotoxic Responses to Titanium Diboride and Zinc Borate Nanoparticles on Cultured Human Primary Alveolar Epithelial Cells

Titanium diboride (TiB₂) and zinc borate (Zn₃BO₆) have been utilized in wide spectrum industrial areas because of their favorable properties such as a high melting point, good wear resistance, high hardness and thermal conductivity. On the other hand, the biomedical potentials of TiB₂ and Zn₃BO₆ are still unknown because there is no comprehensive analysis that uncovers their biocompatibility features. Thus, the toxicogenomic properties of TiB₂ and Zn₃BO₆ nanoparticles (NPs) were investigated on human primary alveolar epithelial cell cultures (HPAEpiC) by using different cell viability assays and microarray analyses. Protein-Protein Interaction Networks Functional Enrichment Analysis (STRING) was used to associate differentially expressed gene probes. According to the results, up to 10 mg/L concentration of TiB₂ and Zn₃BO₆ NPs application did not stimulate a cytotoxic effect on the HPAEpiC cell cultures. Microarray analysis revealed that TiB₂ NPs exposure enhances cellular adhesion molecules, proteases and carrier protein expression. Furthermore, Zn₃BO₆ NPs caused differential gene expressions in the cell cycle, cell division and extracellular matrix regulators. Finally, STRING analyses put forth that inflammation, cell regeneration and tissue repair-related gene interactions were affected by TiB₂ NPs application. Zn₃BO₆ NPs exposure significantly altered inflammation, lipid metabolism and infection response activator-related gene interactions. These investigations illustrated that TiB₂ and Zn₃BO₆ NPs exposure may affect different aspects of cellular machineries such as immunogenic responses, tissue regeneration and cell survival. Thus, these types of cellular mechanisms should be taken into account before the use of the related NPs in further biomedical applications.

Dynamic personalized risk prediction in chronic heart failure patients: a longitudinal, clinical investigation of 92 biomarkers (Bio-SHiFT study)

The aim of our observational study was to derive a small set out of 92 repeatedly measured biomarkers with optimal predictive capacity for adverse clinical events in heart failure, which could be used for dynamic, individual risk assessment in clinical practice. In 250 chronic HFrEF (CHF) patients, we collected trimonthly blood samples during a median of 2.2 years. We selected 537 samples for repeated measurement of 92 biomarkers with the Cardiovascular Panel III (Olink Proteomics AB). We applied Least Absolute Shrinkage and Selection Operator (LASSO) penalization to select the optimal set of predictors of the primary endpoint (PE). The association between repeatedly measured levels of selected biomarkers and the PE was evaluated by multivariable joint models (mvJM) with stratified fivefold cross validation of the area under the curve (cvAUC). The PE occurred in 66(27%) patients. The optimal set of biomarkers selected by LASSO included 9 proteins: NT-proBNP, ST2, vWF, FABP4, IGFBP-1, PAI-1, PON-3, transferrin receptor protein-1, and chitotriosidase-1, that yielded a cvAUC of 0.88, outperforming the discriminative ability of models consisting of standard biomarkers (NT-proBNP, hs-TnT, eGFR clinically adjusted) − 0.82 and performing equally well as an extended literature-based set of acknowledged biomarkers (NT-proBNP, hs-TnT, hs-CRP, GDF-15, ST2, PAI-1, Galectin 3) − 0.88. Nine out of 92 serially measured circulating proteins provided a multivariable model for adverse clinical events in CHF patients with high discriminative ability. These proteins reflect wall stress, remodelling, endothelial dysfunction, iron deficiency, haemostasis/fibrinolysis and innate immunity activation. A panel containing these proteins could contribute to dynamic, personalized risk assessment.

Clinical Trial Registration: 10/05/2013 https://clinicaltrials.gov/ct2/show/NCT01851538?term=nCT01851538&draw=2&rank=1.

Nutritional and Other Trace Elements and Their Associations in Raw King Bolete Mushrooms, Boletus edulis

The occurrence and associations of Ag, As, Ba, Bi, Cd, Co, Cu, Cs, Hg, Ni, Pb, Rb, Sb, Sr, Tl, U, V, W, and Zn, including data that have not been previously reported on Be, Hf, In, Li, Mo, Nb, Sn, Ta, Th, Ti and Zr, and the sum of (14) rare earth elements (ƩREE), were studied in a spatially diverse collection of the B. edulis caps, stipes, and whole fruiting bodies using a validated procedure with measurement by quadrupole ICP-MS. Toxic Cd and Pb were in B. edulis at concentrations below limits set by the European Union in regulations for raw cultivated mushrooms, while Ag, As, Hg, Sb, Tl, and U, which are not regulated, were at relatively low or typical levels as is usually found in mushrooms from an unpolluted area. The elements Be, Bi, Ga, Ge, Hf, In, Nb, Ta, Th, and W, and also ƩREEs, were found at relatively low concentrations in B. edulis, i.e., with levels from below 0.1 to below 0.01 mg kg-1 dw, and for Ʃ14 REEs, the median was 0.31 mg kg-1 dw. The composite samples of caps showed Ag, Cd, Cu, Cs, Ga, Ge, Hg, Mo, Ni, Rb, Sb, Ti, and Zn at higher concentrations than stipes, while Ba, Co, Hf, Sr, Tl, and Zr were found at higher concentrations in stipes than caps (p < 0.05). Mushrooms were characterized by a low coefficient of variation (CV) of below 20%, between sites for concentrations of As, Cu, Ge, Hg, Ni, V, and Zn, while substantial differences (CV > 100%) were found for Ba, Bi, Co, Hf, Zr, and ƩREEs, and an intermediate variation was found for Sr, W, and U. Principal component analysis performed on mushrooms allowed differentiation with respect to 13 collection sites and separation of a consignment that was specifically contaminated, possibly due to a legacy pollution, with significantly higher levels of Ba, Co, Ga, Li, Nb, Ni, Sr, Th, Ti, Y, Zr, and ƩREEs, and another due to possible recent pollution (Pb-gasoline and also Ni); two due to geological contamination because of the Bi, In, Sc, Sb, Sn, Ta, V and W; and one more, the Sudety Mts. site, which was considered as "geogenic/anthropogenic" due to Ag, As, Be, Cd, Cs, Ni, Pb, Rb, Tl, and U.

Increased chitotriosidase 1 concentration following nusinersen treatment in spinal muscular atrophy

Background

Studies regarding the impact of (neuro)inflammation and inflammatory response following repetitive, intrathecally administered antisense oligonucleotides (ASO) in 5q-associated spinal muscular atrophy (SMA) are sparse. Increased risk of hydrocephalus in untreated SMA patients and a marginal but significant increase of the serum/CSF albumin ratio (Qalb) with rare cases of communicating hydrocephalus during nusinersen treatment were reported, which confirms the unmet need of an inflammatory biomarker in SMA. The aim of this study was to investigate the (neuro)inflammatory marker chitotriosidase 1 (CHIT1) in SMA patients before and following the treatment with the ASO nusinersen.

Methods

In this prospective, multicenter observational study, we studied CSF CHIT1 concentrations in 58 adult and 21 pediatric patients with SMA type 1, 2 or 3 before treatment initiation in comparison to age- and sex-matched controls and investigated its dynamics during nusinersen treatment. Concurrently, motor performance and disease severity were assessed.

Results

CHIT1 concentrations were elevated in treatment-naïve SMA patients as compared to controls, but less pronounced than described for other neurodegenerative diseases such as amyotrophic lateral sclerosis. CHIT1 concentration did not correlate with disease severity and did not distinguish between clinical subtypes. CHIT1 concentration did show a significant increase during nusinersen treatment that was unrelated to the clinical response to nusinersen therapy.

Conclusions

CHIT1 elevation in treatment-naïve SMA patients indicates the involvement of (neuro)inflammation in SMA. The lacking correlation of CHIT1 concentration with disease severity argues against its use as a marker of disease progression. The observed CHIT1 increase during nusinersen treatment may indicate an immune response-like, off-target reaction. Since antisense oligonucleotides are an establishing approach in the treatment of neurodegenerative diseases, this observation needs to be further evaluated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01961-8.

Chitinases and Chitinase-Like Proteins as Therapeutic Targets in Inflammatory Diseases, with a Special Focus on Inflammatory Bowel Diseases

Chitinases belong to the evolutionarily conserved glycosyl hydrolase family 18 (GH18). They catalyze degradation of chitin to N-acetylglucosamine by hydrolysis of the β-(1-4)-glycosidic bonds. Although mammals do not synthesize chitin, they possess two enzymatically active chitinases, i.e., chitotriosidase (CHIT1) and acidic mammalian chitinase (AMCase), as well as several chitinase-like proteins (YKL-40, YKL-39, oviductin, and stabilin-interacting protein). The latter lack enzymatic activity but still display oligosaccharides-binding ability. The physiologic functions of chitinases are still unclear, but they have been shown to be involved in the pathogenesis of various human fibrotic and inflammatory disorders, particularly those of the lung (idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease, sarcoidosis, and asthma) and the gastrointestinal tract (inflammatory bowel diseases (IBDs) and colon cancer). In this review, we summarize the current knowledge about chitinases, particularly in IBDs, and demonstrate that chitinases can serve as prognostic biomarkers of disease progression. Moreover, we suggest that the inhibition of chitinase activity may be considered as a novel therapeutic strategy for the treatment of IBDs.

Discovery of Kasugamycin as a Potent Inhibitor of Glycoside Hydrolase Family 18 Chitinases

Kasugamycin, a well-known aminoglycoside antibiotic, has been used widely in agriculture and medicine to combat microbial pathogens by binding the ribosome to inhibit translation. Here, kasugamycin was discovered to be a competitive inhibitor of glycoside hydrolase family 18 (GH18) chitinases from three different organisms (bacterium, insect and human). Results from tryptophan fluorescence spectroscopy and molecular docking revealed that kasugamycin binds to the substrate-binding clefts in a similar mode as the substrate. An electrostatic interaction between the amino group of kasugamycin and the carboxyl group of a conserved aspartate in GH18 chitinase (one of the catalytic triad residues) was found to be vital for the inhibitory activity. This paper not only reports new molecular targets of kasugamycin, but also expands our thinking about GH inhibitor design by using a scaffold unrelated to the substrate.

Associations of plasma YKL-40 concentrations with heel ultrasound parameters and bone turnover markers in the general adult population

OBJECTIVE

YKL-40, also known as chitinase-3-like protein 1, is a new proinflammatory biomarker, that might play a role in tissue remodeling and bone resorption. Here we evaluated the associations of the YKL-40 plasma concentration with heel ultrasound parameters and bone turnover markers (BTMs) in adult men and women from the general population. We tested for a causal role of YKL-40 on bone metabolism using published single nucleotide polymorphisms (SNPs) with consequences for YKL-40 expression and function.

METHODS

Data were obtained from two population-based cohorts: the Study of Health in Pomerania (SHIP) and SHIP-Trend. Quantitative ultrasound (QUS) measurements at the heel were performed and bone turnover was assessed by measurement of intact amino-terminal propeptide of type I procollagen (PINP) and carboxy-terminal telopeptide of type I collagen (CTX). Associations between the YKL-40 plasma concentration and the QUS-based parameters, bone turnover marker (BTM) concentrations and 44 SNPs, including the lead SNP rs4950928, were evaluated in 382 subjects. Furthermore, we assessed the associations between the same SNPs and the QUS-based parameters (n = 5777) or the BTM concentrations (n = 7190).

RESULTS

Sex-specific linear regression models adjusted for a comprehensive panel of interfering covariantes revealed statistically significant inverse associations between YKL-40 and all QUS-based parameters as well as positive associations with CTX in women. The rs4950928 polymorphism was associated with YKL-40 in men and women but none of the tested SNPs was associated with the QUS-based parameters or the BTMs after correction for multiple testing.

CONCLUSIONS

Plasma YKL-40 concentrations are associated with QUS-based parameters as well as CTX concentrations in women but these associations are probably not causal.

Benzoxazepine-Derived Selective, Orally Bioavailable Inhibitor of Human Acidic Mammalian Chitinase

Human acidic mammalian chitinase (hAMCase) is one of two true chitinases in humans, the function of which remains elusive. In addition to the defense against highly antigenic chitin and chitin-containing pathogens in the gastric and intestinal contents, AMCase has been implicated in asthma, allergic inflammation, and ocular pathologies. Potent and selective small-molecule inhibitors of this enzyme have not been identified to date. Here we describe structural modifications of compound OAT-177, a previously developed inhibitor of mouse AMCase, leading to OAT-1441, which displays high activity and selectivity toward hAMCase. Significantly reduced off-target activity toward the human ether-à-go-go-related gene (hERG) and a good pharmacokinetic profile make OAT-1441 a potential candidate for further preclinical development as well as a useful tool compound to study the physiological role of hAMCase.

Saliva proteomic patterns in patients with molar incisor hypomineralization

Molar incisor hypomineralization (MIH) is an endemic pediatric disease with an unclear pathogenesis. Considering that saliva controls enamel remineralization and that MIH is associated with higher saliva flow rate, we hypothesized that the protein composition of saliva is linked to disease. To test this, we enrolled 5 children aged 6-14 years with MIH showing at least one hypersensitive molar and 5 caries-free children without hypomineralization. Saliva samples were subjected to proteomic analysis followed by protein classification in to biological pathways. Among 618 salivary proteins identified with high confidence, 88 proteins were identified exclusively in MIH patients and 16 proteins in healthy controls only. Biological pathway analysis classified these 88 patient-only proteins to neutrophil-mediated adaptive immunity, the activation of the classical pathway of complement activation, extracellular matrix degradation, heme scavenging as well as glutathione -and drug metabolism. The 16 controls-only proteins were associated with adaptive immunity related to platelet degranulation and the lysosome. This report suggests that the proteaneous composition of saliva is affected in MIH patients, reflecting a catabolic environment which is linked to inflammation.

Revisiting Old Questions and New Approaches to Investigate the Fungal Cell Wall Construction

The beginning of our understanding of the cell wall construction came from the work of talented biochemists in the 70-80's. Then came the era of sequencing. Paradoxically, the accumulation of fungal genomes complicated rather than solved the mystery of cell wall construction, by revealing the involvement of a much higher number of proteins than originally thought. The situation has become even more complicated since it is now recognized that the cell wall is an organelle whose composition continuously evolves with the changes in the environment or with the age of the fungal cell. The use of new and sophisticated technologies to observe cell wall construction at an almost atomic scale should improve our knowledge of the cell wall construction. This essay will present some of the major and still unresolved questions to understand the fungal cell wall biosynthesis and some of these exciting futurist approaches.

A Cold-Adapted Chitinase-Producing Bacterium from Antarctica and Its Potential in Biocontrol of Plant Pathogenic Fungi

To obtain chitinase-producing microorganisms with high chitinolytic activity at low temperature, samples collected from Fildes Peninsula in Antarctica were used as sources for bioprospecting of chitinolytic microorganisms. A cold-adapted strain, designated as GWSMS-1, was isolated from marine sediment and further characterized as Pseudomonas. To improve the chitinase production, one-factor-at-a-time and orthogonal test approaches were adopted to optimize the medium components and culture conditions. The results showed that the highest chitinolytic activity (6.36 times higher than that before optimization) was obtained with 95.41 U L^-1 with 15 g L^-1 of glucose, 1 g L^-1 of peptone, 15 g L^-1 of colloid chitin and 0.25 g L^-1 of magnesium ions contained in the medium, cultivated under pH 7.0 and a temperature of 20 °C. To better understand the application potential of this strain, the enzymatic properties and the antifungal activity of the crude chitinase secreted by the strain were further investigated. The crude enzyme showed the maximum catalytic activity at 35 °C and pH 4.5, and it also exhibited excellent low-temperature activity, which still displayed more than 50% of its maximal activity at 0 °C. Furthermore, the crude chitinase showed significant inhibition of fungi Verticillium dahlia CICC 2534 and Fusarium oxysporum f. sp. cucumerinum CICC 2532, which can cause cotton wilt and cucumber blight, respectively, suggesting that strain GWSMS-1 could be a competitive candidate for biological control in agriculture, especially at low temperature.