Biomarkers for lysosomal storage disorders: identification and application as exemplified by chitotriosidase in Gaucher disease

A biomarker is an analyte that indicates the presence of a biological process linked to the clinical manifestations and outcome of a particular disease. An ideal biomarker provides indirect but ongoing determinations of disease activity. In the case of lysosomal storage disorders (LSDs), metabolites or proteins specifically secreted by storage cells are good candidates for biomarkers. Potential clinical applications of biomarkers are found in improved diagnosis, monitoring of disease progression and assessment of therapeutic correction. These applications are illustrated by reviewing the use of plasma chitotriosidase in the clinical management of patients with Gaucher disease, the most common LSD. The ongoing debate on the value of biomarkers in patient management is addressed. Novel analytical methods have revolutionized the identification and measurement of biomarkers at the protein and metabolite level. Recent developments in biomarker discovery by proteomics are described and the future for biomarkers of LSDs is discussed. CONCLUSION: Besides direct applications for biomarkers in patient management, biomarker searches are likely to render new insights into pathophysiological mechanisms and metabolic adaptations, and may provide new targets for therapeutic intervention.     

Biomarkers in lysosomal storage diseases: a review

A biomarker is generally an analyte that indicates the presence or extent of a biological process, which is itself directly linked to the clinical manifestations and outcome of a particular disease. An ideal biomarker provides indirect but ongoing and specific determinations of disease activity. These characteristics emphasize the value of surrogate biomarkers for non-invasive and detailed monitoring to demonstrate the efficacy of orphan drugs in clinical trials. The emergence of novel laboratory methods has facilitated the search for biomarkers in lysosomal storage diseases (LSDs), by allowing the systematic identification of molecules whose expression is altered as a result of the primary storage pathology. In Gaucher disease, for example, a chemokine, CCL18, has been identified as a biomarker for clinical development that reflects disease severity and response to treatment.
Conclusion: New methods for the identification of novel biomarkers have the potential to provide mechanistic insights into the molecular pathogenesis of LSDs, including Fabry disease and Gaucher disease.     

Identification and use of biomarkers in Gaucher disease and other lysosomal storage diseases

The value of biomarkers in the clinical management of lysosomal storage diseases is best illustrated by the present use of plasma chitotriosidase levels in the diagnosis and monitoring of Gaucher disease. The enzyme chitotriosidase is specifically produced and secreted by the pathological storage macrophages (Gaucher cells). Plasma chitotriosidase levels are elevated on average 1000-fold in symptomatic patients with Gaucher disease and reflect the body burden on storage cells. Changes in plasma chitotriosidase reflect changes in clinical symptoms. Monitoring of plasma chitotriosidase levels is nowadays commonly used in decision making regarding initiation and optimization of costly therapeutic interventions (enzyme replacement therapy or substrate reduction therapy). A novel substrate has been developed that further facilitates the measurement of chitotriosidase in plasma samples. Moreover, an alternative Gaucher-cell marker, CCL18, has been very recently identified and can also be employed to monitor the disease, particularly in those patients lacking chitotriosidase due to a genetic mutation. There is a need for comparable surrogate markers for other lysosomal storage diseases and the search for such molecules is an area of intense investigation.
Conclusion: The use of biomarkers can provide valuable insight into the molecular pathogenesis of LSDs, such as Gaucher disease and Fabry disease.     

Clinical evaluation of biomarkers in Gaucher disease

Novel or candidate biomarkers require thorough evaluation to establish their utility in a clinical setting. This paper describes an evaluation of several established enzyme markers of Gaucher disease and a newly-described chemokine, pulmonary and activation-regulated chemokine (PARC). The ability of the biomarkers to rank patients with Gaucher disease in order of disease severity and organ bulk, and to reflect changes in key clinical parameters in response to enzyme replacement therapy were evaluated. PARC concentrations were found to be reliably correlated with visceral disease and with key clinical responses to enzyme replacement in an unbiased manner. Unlike chitotriosidase and serum angiotensin-converting enzyme activity, genetic variation in serum PARC did not appear to influence its utility as a biomarker.
Conclusion: For each new candidate biomarker of lysosomal storage diseases, a similar clinical evaluation will be required, though the approach will need to be modified according to the clinical features and natural history of each disorder.     

Hydrops fetalis: manifestation in lysosomal storage diseases including Farber disease

The authors describe a case of disseminated lipogranulomatosis (Farber disease) presenting as nonimmune hydrops fetalis. This is the tenth lysosomal storage disease which can show this clinical manifestation. The literature is reviewed for all hydrops cases associated with lysosomal storage diseases. Conclusion Although rare, the lysosomal storage diseases collectively are significant causes of non-immune hydrops and appropriate investigations are required in all cases of unexplained hydrops fetalis. Received: 25 July 1996 / Accepted: 21 August 1996     

Lysosomal storage disorders: A review of the musculoskeletal features

The lysosomal storage disorders are a collection of progressive, multisystem disorders that frequently present in childhood. Their timely diagnosis is paramount as they are becoming increasingly treatable. Musculoskeletal manifestations often occur early in the disease course, hence are useful as diagnostics clues. Non‐inflammatory joint stiffness or pain, carpal tunnel syndrome, trigger fingers, unexplained pain crises and short stature should all prompt consideration of a lysosomal storage disorder. Recurrent ENT infections, hepatosplenomegaly, recurrent hernias and visual/hearing impairment – especially when clustered together – are important extra‐skeletal features. As diagnostic and therapeutic options continue to evolve, children with lysosomal storage disorders and their families are facing more sophisticated options for screening and treatment. The aim of this article is to highlight the paediatric presentations of lysosomal storage disorders, with an emphasis on the musculoskeletal features.     

Substrate reduction therapy for lysosomal storage diseases

The treatment of disordered lipoprotein metabolism with the statin class of drugs is one of the most striking successes in the field of applied medical science: here the use of selective inhibitors of the first committed step of cholesterol biosynthesis, in a complex and highly regulated pathway, leads to improved outcome from a common lipid storage disease that is a blight on whole populations – atherosclerosis. By the same token, substrate reduction is an emerging therapeutic strategy for the arcane field of the lysosomal storage diseases (LSDs). Reduced biosynthesis of glucosylceramide is postulated to allow correction of the imbalance between formation and breakdown of glycosphingolipids; the therapeutic effect of substrate reduction depends upon the presence of residual hydrolytic activity towards those accumulated glycosphingolipid substrates derived from glucosylceramide. First pioneered in the laboratory by Norman Radin, this approach has now been introduced into the clinic: based on the ability to inhibit uridine diphosphate glucosylceramide transferase, the semi-selective iminosugar, N -butyldeoxynojirimycin, is licensed for the treatment of type 1 Gaucher disease.
Conclusion: Inhibition of substrate formation has wide application in the treatment of LSDs. Decreased glucosylceramide biosynthesis has therapeutic potential in glycosphingolipidoses other than Gaucher disease, and offers promise in several neurodegenerative storage disorders that are currently beyond the reach of other procedures. The results of ongoing clinical trials of miglustat in type 3 Gaucher disease, Niemann–Pick disease type C and GM2 gangliosidosis are eagerly awaited.     

腺相关病毒介导的基因疗法在溶酶体贮积症中的应用

溶酶体贮积症(lysosomal storage disorders,LSDs)是一组由溶酶体酶或功能相关蛋白缺陷所致的单基因遗传代谢性疾病。临床治疗以酶替代疗法为主,但该疗法对有神经系统症状的LSDs患者疗效较差。随着多组学、测序技术和生物工程学的快速发展,基因治疗已在LSDs患者中开展。腺相关病毒(adeno-associated virus,AAV)作为基因治疗的载体之一,在治疗遗传代谢性等疾病中具有较好的前景。越来越多的研究表明,AAV介导的基因治疗在LSDs中有效。该文就其在LSDs中的应用作一综述。[中国当代儿科杂志,2022,24 (11):1281-1287]     

Insulin-like growth factors in lysosomal storage disease

Recent data indicate that insulin-like growth factor II (IGF II) and lysosomal enzymes bind to a common receptor. We measured serum IGF I and II levels in 16 patients with various lysosomal storage disorders. The IGF serum concentrations were normal as long as no marked liver disease was present. Under these conditions no direct interconnection between the lysosomal system and the serum IGF levels was found.     

外周血淋巴细胞异常空泡检查对溶酶体贮积病筛查和诊断的价值

目的 探讨外周血淋巴细胞空泡检查在溶酶体贮积病的筛查和诊断中的应用价值.方法 对2008年1月至2009年12月在我院接受外周血淋巴细胞光镜和电子显微镜检查的疑诊溶酶体贮积病患儿的临床和病理资料进行回顾性分析.结果 本组42例患儿均为隐匿起病,均存在进行性智力运动发育落后或倒退,其中32例伴抽搐,3例视力下降,4例肝脾大.本组均接受外周血涂片检查,其中14例外周血淋巴细胞存在异常空泡,这14例中8例经进一步检查确诊为溶酶体贮积病,包括4例淋巴细胞超微结构检查发现曲线体,确诊为神经元蜡样质脂褐质沉积症;2例经酶活性测定分别确诊为异染性脑白质营养不良和糖原累积症Ⅱ型,2例依据骨髓涂片和鞘磷脂酶活性检查诊断为尼曼-匹克病C型;6例未能明确诊断.结论 由于方法简单且微创,外周血淋巴细胞异常空泡检查可以用于溶酶体贮积病的筛查.对于疑诊为神经元蜡样质脂褐质沉积症的病例,外周血淋巴细胞超微结构检查有可能提供确诊依据.

Abstract：

Objective Lysosomal storage diseases are a group of inherited disorders caused by deficiency of lysosomal enzymes or structural components. The manifestations of lysosomal storage diseases are complicated due to different enzyme deficiency. It has been reported that a range of metabolic diseases resulting in abnormal accumulation of metabolic byproducts may exhibit abnormal cytoplasmic vacuolation of lymphocytes. The aim of this study was to elicit the usefulness of vacuolated peripheral lymphocytes detection in screening and diagnosis of lysosomal storage diseases. Method Clinical data of 42 patients who underwent microscopic and electron microscopic examination of peripheral blood specimens in our department were retrospectively evaluated between January 2008 and December 2009. Result Forty-two patients with the suspected lysosomal storage diseases were included, these patients presented with motor and developmental retardation and/or regression. Seizure occurred in 32 patients. Hepatosplenomegaly were found in 4 patients. Three patients presented with declined visual acuity. Atrophy and/or abnormal signals were detected on cranial CT/MRI images in 24 patients. Blood biochemical tests were normal. Serum levels of ammonia, lactic acid and pyruvate were normal. Serum amino acid profiles and urinary organic acid profiles were normal. Serum fatty acid profiles were normal. Vacuolated lymphocytes were detected on microscopic examination of blood film in 14 patients, and 8 of these patients were confirmed to have lysosomal storage disease. Curvilinear body was found on electronic microscopic examination of peripheral lymphocytes specimens in 4 patients, confirming the diagnosis of neuronal ceroid lipofuscinosis. In 3 of these 4 patients, curvilinear body were also found on electronic microscopic examination of skin and/or muscle specimens. Enzyme analysis confirmed the diagnosis of metachromatic leukodystrophy in one patient and Pompe's disease in another patient. Typical pathological changes were found on the examination of bone marrow in 2 patients with normal acid sphingomyelinase activity. So the patients were diagnosed with Niemann-Pick disease type C. The diagnosis of other 6 patients with vacuolated lymphocytes was unknown.Conclusion Because of its usefulness and minimal invasiveness, vacuolated peripheral lymphocytes examination should be a screening test for lysosomal storage disease. As for patients with suspected neuronal ceroid lipofuscinosis, electron microscopic examination of peripheral lymphocyte specimens may provide specific clues to the final diagnosis.     

Gene therapy approaches for lysosomal storage disorders, a good model for the treatment of mendelian diseases

This review describes the different gene therapy technologies applied to approach lysosomal storage disorders, monogenic conditions, with known genetic and biochemical defects, for many of which animal models are available. Both viral and nonviral procedures are described, underlying the specific needs that the treatment of genetic disorders requires. CONCLUSIONS: Lysosomal storage disorders represent a good model of study of gene therapeutic procedures that are, or could be, relevant to the treatment of several other mendelian diseases.     

Nephrosis in two siblings with infantile sialic acid storage disease

The diagnosis of infantile sialic acid storage disease (ISSD) was established in two siblings on the basis of typical clinical signs and the biochemical findings of hyperexcretion and intracellular storage of free sialic acid. A severe, steroid resistant nephrosis occurred in both siblings. The activities of lysosomal enzymes, including sialidase, were normal. A combined detection method for sialic acids withLimax flavus agglutinin labelling and phosphotungstic acid staining showed severely alterated sialic acid components in epithelial kidney cells and indicate a causal relationship between the nephrosis and the underlying biochemical defect. Further observations of ISSD patients with renal involvement will prove if a separate nephropathic phenotype exists.     

Paediatric non-neuronopathic Gaucher disease: recommendations for treatment and monitoring

In individuals with non-neuronopathic Gaucher disease, childhood manifestations are usually predictive of a more severe phenotype. Although children with Gaucher disease are at risk of irreversible disease complications, early intervention with an optimal dose of enzyme therapy can prevent the development of complications and ensure adequate, potentially normal, development through childhood and adolescence. Very few, if any, children diagnosed by signs and symptoms should go untreated. Evidence suggests that disease severity, disease progression and treatment response in different organs where glucocerebroside accumulates are often non-uniform in affected individuals. Therefore, serial monitoring of the affected compartments is important. This should include a thorough physical examination at 6- to 12-monthly intervals. Neurological assessment should be performed to rule out neurological involvement and should be undertaken periodically thereafter in children who are considered to have risk factors for developing neuronopathic disease. Haematological and biochemical markers, such as haemoglobin, platelet counts and chitotriosidase levels, should be assessed every 3 months initially, but when clinical goals have been met through treatment with enzyme therapy, the frequency can be reduced to every 12 to 24 months. Careful monitoring of bone disease is vitally important, as the resulting sequelae are associated with the greatest level of morbidity. By combining various imaging modalities, the skeletal complications of non-neuronopathic Gaucher disease can be effectively monitored so that irreversible skeletal pathology is avoided and pain due to bone involvement is diminished or eliminated. Monitoring must include regular psychosocial, functional status and quality-of-life evaluation, as well as consistent assessment of therapeutic goal attainment and necessary dosage adjustments based on the patients progress. Conclusion: Through comprehensive and serial monitoring, ultimately, a therapeutic dose of enzyme therapy that achieves sustained benefits can be found for each child with non-neuronpathic Gaucher disease.Abbreviations ACE angiotensin-converting enzyme - BMD bone mineral density - DXA dual-energy X-ray absorptiometry - QoL quality-of-life - TRAP tartrate-resistant acid phosphatase     

Hemophagocytic lymphohistiocytosis triggered by Gaucher disease in a preterm neonate

Objective: To present the diagnostic workup in an extremely low birth weight infant patient with signs of both sepsis and hemophagocytosis. Participants: A preterm infant presented with clinical and laboratory signs of early-onset sepsis including hepatosplenomegaly, thrombocytopenia, direct hyperbilirubinemia, and elevated liver enzymes. Methods: Despite extensive septic workup, no underlying infection was detected. Additional hyperferritinemia and other elevated inflammatory parameters raised the suspicion of a primary or secondary hemophagocytic lymphohistiocytosis (HLH). Results: However, further metabolic analysis yielded a positive result for Gaucher disease (GD) type 2, a rare, but possible trigger of HLH. Conclusions: Our case shows that GD may lead to the picture of a secondary HLH and that a metabolic workup should always be performed in patients in whom primary HLH has been excluded.     

Sphingomyelinase enzyme assay in Niemann-Pick disease

Niemann-Pick group of diseases are rare autosomal recessive disorders of lysosomal enzymes. These are divisible into six types depending on clinical and biochemical features. On the basis of sphingomyelinase assay in five cases of Niemann-Pick disease, three cases were classified as type IA, one as type IS and one as type IIS. Their clinicopathological profiles are compared with 17 cases reported previously from India.