Biomarkers in Serbian patients with Gaucher disease

Patient centered guidelines for the laboratory diagnosis of Gaucher disease type 1

Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder due to the deficient activity of the acid beta-glucosidase (GCase) enzyme, resulting in the progressive lysosomal accumulation of glucosylceramide (GlcCer) and its deacylated derivate, glucosylsphingosine (GlcSph). GCase is encoded by the GBA1 gene, located on chromosome 1q21 16 kb upstream from a highly homologous pseudogene. To date, more than 400 GBA1 pathogenic variants have been reported, many of them derived from recombination events between the gene and the pseudogene. In the last years, the increased access to new technologies has led to an exponential growth in the number of diagnostic laboratories offering GD testing. However, both biochemical and genetic diagnosis of GD are challenging and to date no specific evidence-based guidelines for the laboratory diagnosis of GD have been published. The objective of the guidelines presented here is to provide evidence-based recommendations for the technical implementation and interpretation of biochemical and genetic testing for the diagnosis of GD to ensure a timely and accurate diagnosis for patients with GD worldwide. The guidelines have been developed by members of the Diagnostic Working group of the International Working Group of Gaucher Disease (IWGGD), a non-profit network established to promote clinical and basic research into GD for the ultimate purpose of improving the lives of patients with this disease. One of the goals of the IWGGD is to support equitable access to diagnosis of GD and to standardize procedures to ensure an accurate diagnosis. Therefore, a guideline development group consisting of biochemists and geneticists working in the field of GD diagnosis was established and a list of topics to be discussed was selected. In these guidelines, twenty recommendations are provided based on information gathered through a systematic review of the literature and two different diagnostic algorithms are presented, considering the geographical differences in the access to diagnostic services. Besides, several gaps in the current diagnostic workflow were identified and actions to fulfill them were taken within the IWGGD. We believe that the implementation of recommendations provided in these guidelines will promote an equitable, timely and accurate diagnosis for patients with GD worldwide.

Chitotriosidase: a marker and modulator of lung disease

Chitotriosidase (CHIT1) is a highly conserved and regulated chitinase secreted by activated macrophages; it is a member of the 18-glycosylase family (GH18). CHIT1 is the most prominent chitinase in humans, can cleave chitin and participates in the body's immune response and is associated with inflammation, infection, tissue damage and remodelling processes. Recently, CHIT1 has been reported to be involved in the molecular pathogenesis of pulmonary fibrosis, bronchial asthma, COPD and pulmonary infections, shedding new light on the role of these proteins in lung pathophysiology. The potential roles of CHIT1 in lung diseases are reviewed in this article.

This is the first review of chitotriosidase in lung diseasehttp://bit.ly/2LpZUQI

Human Chitotriosidase Does Not Catabolize Hyaluronan

Humans express an enzyme that degrades chitin, called chitotriosidase, despite the fact that we do not produce chitin. One possible explanation for this is that chitinase also degrades hyaluronan, a polysaccharide that is abundant in human tissues and shares structural attributes in common with chitinase. The objective of this study was to determine whether human chitotriosidase is capable of hydrolyzing hyaluronan. Hyaluronan of various sizes under a range of pH conditions displayed no degradation when incubated with various chitinases over a period of 5 days, while commercial hyaluronidase readily digested the hyaluronan. Under the same conditions, recombinant chitinase but not our negative control chitinase, was able to digest chitosan. We conclude that human chitinase does not digest hyaluronan. Because chitin is a prominent component of certain fungi and insects, it seems likely that human chitinase evolved for roles in host defense rather than serving to catabolize the endogenous polymer hyaluronan.

Verifying Sarcoidosis Activity: Chitotriosidase versus ACE in Sarcoidosis - a Case-control Study

Background

Until now, a proper biomarker(s) to evaluate sarcoidosis activity has not been recognized. The aims of this study were to evaluate the sensitivity and specificity of the two biomarkers of sarcoidosis activity already in use (serum angiotensin converting enzyme – ACE and serum chitotriosidase) in a population of 430 sarcoidosis patients. The activities of these markers were also analyzed in a group of 264 healthy controls.

Methods

Four hundred and thirty biopsy positive sarcoidosis patients were divided into groups with active and inactive disease, and groups with acute or chronic disease. In a subgroup of 55 sarcoidosis patients, activity was also assessed by F-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET) scanning. Both serum chitotriosidase and ACE levels showed non-normal distribution, so nonparametric tests were used in statistical analysis.

Results

Serum chitotriosidase activities were almost 6 times higher in patients with active sarcoidosis than in healthy controls and inactive disease. A serum chitotriosidase value of 100 nmol/mL/h had the sensitivity of .5% and specificity of 70.0%. A serum ACE activity cutoff value of 32.0 U/L had the sensitivity of 66.0% and the specificity of 54%. A statistically significant correlation was obtained between the focal granulomatous activity detected on ¹⁸F-FDG PET/CT and serum chitotriosidase levels, but no such correlation was found with ACE. The levels of serum chitotriosidase activity significantly correlated with the disease duration (P < 0.0001). Also, serum chitotriosidase significantly correlated with clinical outcome status (COS) categories (ρ =0.272, P =0.001).

Conclusions

Serum chitotriosidase proved to be a reliable biomarker of sarcoidosis activity and disease chronicity.

Chitotriosidase Expression during Monocyte-Derived Dendritic Cells Differentiation and Maturation

The chitotriosidase (CHIT-1) is a glycosyl hydrolase (GH), which has been found highly expressed in activated macrophages and in different monocyte-derived cell lines such as Kupffer cells and osteoclasts, as well is differently produced in diverse stages of macrophage polarization (M1 and M2). Recent finding suggests that CHIT-1 plays a crucial role in innate and acquired immunity. Dendritic cells (DCs) are a complex group of cells that play a critical role in immune response. The aim of this study was to investigate the presence of CHIT-1 during the differentiation and maturation of DCs. Magnetically-isolated peripheral blood monocytes were differentiated toward immature DCs (iDC) and mature DCs (mDCs). Our results showed, for the first time, that CHIT-1 is expressed during the process of differentiation and maturation of DCs in a time-dependent manner. We found that CHIT1 is evenly distributed in cytoplasm of both the iDCs and mDCs. Additionally, a significantly increased expression of CHIT1 mRNA and protein was observed in mature DCs. These results suggest that CHIT-1 play an important role in the DCs immunoresponse.

Macrophage-derived soluble CD163 level in young patients with Gaucher disease: relation to phenotypes, disease severity and complications

OBJECTIVES

Bone and lung involvement are two major causes of morbidity in Gaucher disease (GD). The soluble form of CD163 (sCD163) is a valuable diagnostic biomarker for monitoring diseases with increased macrophage activation. We determined sCD163 levels in 30 children and adolescence with GD compared with 30 healthy controls and assessed the relation to phenotypes, disease severity and complications.

METHODS

Thirty GD patients (10 had type 1 and 20 had type 3) were studied stressing on skeletal, pulmonary or neurological manifestations, enzyme replacement therapy (ERT), hematological profile, plasma chitotriosidase activity, D-dimer and sCD163. Liver and spleen volumes and bone mineral density (BMD) were assessed.

RESULTS

sCD163 levels were markedly elevated in patients compared with controls. D-dimer, chitotriosidase activity and sCD163 levels were significantly increased in type 3 GD patients compared with type 1. sCD163 was significantly elevated in GD patients with dysphagia, developmental delay, pulmonary hypertension risk or abnormal BMD (osteopenia/osteoporosis) than those without. GD patients receiving ERT every 2weeks had lower levels than those under ERT for more than 2weeks. sCD163 was positively correlated with age, disease duration, severity score index, D-dimer and chitotriosidase activity. The cutoff value of sCD163 at 9400ng/mL could differentiate GD patients with and without pulmonary hypertension risk with a sensitivity of 90% and specificity of 95%.

CONCLUSIONS

sCD163 is a biomarker for the clinical assessment of macrophage proliferation and activity that would help in risk prediction of bone and lung involvement and monitoring treatment response.

Role of chitotriosidase (chitinase 1) under normal and disease conditions

Mammalian chitinases belong to the glycosyl hydrolase 18 family based on structural homology and the family includes a large number of bacterial and eukaryotic chitinases. Among the mammalian chitinases, chitotriosidase (CHIT1) and acidic mammalian chitinase (AMCase) are capable of hydrolyzing the β-(1, 4)-linkage between the adjacent N-acetyl glucosamine residues of chitin. CHIT1 is one of the most abundantly secreted proteins, being mainly produced by activated macrophages and epithelial cells. CHIT1 plays a pivotal role in the context of infectious disease including malaria and fungi infections as a host defense towards chitin in pathogen's cell structure and as a diagnostic marker of disease. In contrast, CHI1 released by activated Kupffer cells in liver could induce hepatic fibrosis and cirrhosis. Increased serum levels of CHIT1 were observed in patients with many disorders, including Gaucher's disease, bronchial asthma, and atherosclerosis. Therefore, CHIT1 seems to have dual (regulatory and pathogenic) roles depending on the disease and producing cell types during the inflammatory conditions.