Elevated plasma chemokine CCL18/PARC in β-thalassemia

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.

Plasma proteome profiling combined with clinical and genetic features reveals the pathophysiological characteristics of β-thalassemia

The phenotype of β-thalassemia underlies multigene interactions, making clinical stratification complicated. An increasing number of genetic modifiers affecting the disease severity have been identified, but are still unable to meet the demand of precision diagnosis. Here, we systematically conducted a comparative plasma proteomic profiling on patients with β-thalassemia and healthy controls. Among 246 dysregulated proteins, 13 core protein signatures with excellent biomarker potential are proposed. The combination of proteome and patients' clinical data revealed patients with codons 41/42 -TTCT mutations have an elevated risk of higher iron burden, dysplasia, and osteoporosis than patients with other genotypes. Notably, 85 proteins correlating to fetal hemoglobin (Hb F) were identified, among which the abundance of 27 proteins may affect the transfusion burden in patients with β-thalassemia. The current study thus provides protein signatures as potential diagnostic biomarkers or therapeutic clues for β-thalassemia.

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246 dysregulated proteins are detected in plasma of patients with β-thalassemia

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13 potential biomarkers and 27 proteins related to disease progression are found

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Variations in plasma proteome reveal the disease pathophysiological characteristics

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Codons 41/42 -TTCT carriers have higher ferritin levels compared to non-carriers

Hyperferritinemia and iron overload in type 1 Gaucher disease

Hyperferritinemia occurs in Gaucher disease but its clinical spectrum or its association with systemic iron overload and HFE mutations are not known. In 114 patients with Type 1 Gaucher disease, we determined serum ferritin, transferrin saturation and HFE genotype. The results were correlated with the extent of hepatosplenomegaly, overall Gaucher disease severity score index, and response to enzyme replacement therapy. In a subset of patients with radiological and/or laboratory evidence of systemic iron overload, liver biopsy was performed. There was a mean 3.7-fold elevation of serum ferritin over the upper limit of normal (ULN). Prior splenectomy was associated with most severe hyperferritinemia compared to patients with intact spleen (6.53 x ULN vs. 2.69 x ULN, P = 0.003). HFE genotyping revealed two patients homozygous for H63D mutation and 30% of patients heterozygote carriers of H63D mutation; no patients harbored C282Y mutation; there was no correlation of ferritin with HFE genotype. Ferritin level correlated with liver volume (Pearson correlation coefficient = 0.254, P = 0.035) and it was negatively correlated with hemoglobin (r = -0.315, P = 0.004); there was no relationship with other indicators of Gaucher disease activity. Enzyme replacement therapy (ERT) resulted in amelioration of hyperferritinemia: 707 +/- 898 ng/ml vs. 301 +/- 310 ng/ml (P = 0.001), transferrin saturation remained normal. Three patients were suspected of clinical iron overload, confirmed on liver biopsy. Iron accumulation was variably noted in hepatocytes and Kupffer cells. There is a high prevalence of hyperferritinemia in Type 1 Gaucher disease that is associated with indicators of disease severity, reversed by ERT and is not related to HFE mutations.

Plasma chitotriosidase and CCL18 as surrogate markers for granulomatous macrophages in sarcoidosis

BACKGROUND

Accumulation of macrophages in multiple organs is a common feature of sarcoidosis and Gaucher disease. The vast number of storage macrophages in Gaucher patients has facilitated the discovery of suitable plasma markers like chitotriosidase and CCL18.

METHODS

Plasma specimens of patients with sarcoidosis were examined on chitotriosidase activity and CCL18 protein levels.

RESULTS

Chitotriosidase was markedly increased, being on average 13.7-fold elevated (range: 1.1-43.3). The sensitivity of demonstrating sarcoidosis using plasma chitotriosidase values exceeded that using serum angiotensin-converting enzyme values. A 3.5-fold (range: 1-15) increase in CCL18 was also observed. The relative changes in chitotriosidase and CCL18 during the course of disease closely mimicked each other, suggesting an identical cellular source. In situ hybridization analysis confirmed massive production of chitotriosidase by sarcoid macrophages. The increase in plasma chitotriosidase correlated with the stage of disease, being highest in active sarcoidosis with extrapulmonary involvement. Therapy with steroids resulted in clear reduction of plasma chitotriosidase and CCL18 and relapse of disease activity was preceded by increases in these parameters.

CONCLUSIONS

Sarcoid macrophages secrete high quantities of chitotriosidase and CCL18. Determination of plasma chitotriosidase and CCL18 may be useful to monitor changes in granulomatous macrophages during the course of sarcoidosis.

Microarray analysis of liver gene expression in iron overloaded patients with sickle cell anemia and beta-thalassemia

Chronic transfusion therapy is used clinically to supply healthy erythrocytes for patients with sickle cell anemia (SCA) or beta-thalassemia major (TM). Despite the benefits of red blood cell transfusions, chronic transfusions lead to iron accumulation in key tissues such as the heart, liver, and endocrine glands. Transfusion-acquired iron overload is recognized as a cause of morbidity and mortality among patients receiving chronic transfusions. At present, there is little understanding of molecular events that occur during transfusional iron loading and the reasons for the large inter-individual variation observed clinically in transfusion-acquired iron accumulation. To address these issues, we examined whether any liver-expressed genes in SCA or TM patients with transfusional iron overload were associated with the degree of iron accumulation. Specifically, we performed microarray analysis on liver biopsy specimens comparing SCA patients with mild or severe iron overload and also compared SCA with TM patients. Fifteen candidate genes were identified with significantly differential expression between the high and low liver iron concentrations. SCA patients and 20 candidate genes were detected between the SCA and TM patient comparison. Subsequent quantitative PCR experiments validated 12 candidate genes; with GSTM1, eIF5a, SULF2, NTS, and HO-1 being particularly good prospects as genes that might affect the degree of iron accumulation. Future work will determine the baseline expression of these genes prior to transfusional iron overload and elucidate the full impact of these genes on the inter-individual variation observed clinically in transfusion-acquired iron accumulation.

Management of non-neuronopathic Gaucher disease with special reference to pregnancy, splenectomy, bisphosphonate therapy, use of biomarkers and bone disease monitoring

Enzyme replacement was introduced as treatment for non-neuronopathic Gaucher disease more than 15 years ago. To ensure the best use of this costly ultra-orphan agent, a systematic disease management approach has been proposed by an international panel; this includes the development, by consensus, of achievable treatment goals. Here we critically review these goals and monitoring guidelines and incorporate emerging experience of the disease in the therapeutic era, as well as contemporary clinical research. This review makes recommendations related specifically to the management of pregnancy; the appropriate use of splenectomy and bisphosphonate treatment; the relevance of biochemical markers to disease monitoring; and the use of semi-quantitative methods for assessing bone marrow infiltration. In addition, we identify key areas for development, including the requirement for a validated index of disease severity; the need to correlate widely used biomarkers with long-term disease outcomes, and the desirability of establishing agreed standards for monitoring of bone disease particularly in infants and children with Gaucher disease.

The biology of the Gaucher cell: the cradle of human chitinases

Gaucher disease (GD) is the most common lysosomal storage disorder and is caused by inherited deficiencies of glucocerebrosidase, the enzyme responsible for the lysosomal breakdown of the lipid glucosylceramide. GD is characterized by the accumulation of pathological, lipid laden macrophages, so-called Gaucher cells. Following the development of enzyme replacement therapy for GD, the search for suitable surrogate disease markers resulted in the identification of a thousand-fold increased chitinase activity in plasma from symptomatic Gaucher patients and that decreases upon successful therapeutic intervention. Biochemical investigations identified a single enzyme, named chitotriosidase, to be responsible for this activity. Chitotriosidase was found to be an excellent marker for lipid laden macrophages in Gaucher patients and is now widely used to assist clinical management of patients. In the wake of the identification of chitotriosidase, the presence of other members of the chitinase family in mammals was discovered. Amongst these is AMCase, an enzyme recently implicated in the pathogenesis of asthma. Chitinases are omnipresent throughout nature and are also produced by vertebrates in which they play important roles in defence against chitin-containing pathogens and in food processing.