Krabbe disease (KD) is an autosomal recessive sphingolipidosis due to mutations of the GALC gene encoding for the lysosomal β-galactosylceramidase (GALC) that removes β-galactose from β-galactosylceramide, β-lactosylceramide (LacCer) and the neurotoxic metabolite β-galactosylsphingosine (psychosine). At present, the accumulation of psychosine is thought to be the main cause of demyelination, neurodegeneration and neuroinflammation that characterize the early infantile KD with a 1.5-2-year median survival. Currently, the standard of care of KD is haematopoietic stem cell transplantation which, however, improves the lifespan of Krabbe patients only when performed before symptoms appear. Thus, a better understanding of the pathogenesis of KD is required for the development of more efficacious therapeutic approaches. This largely depends upon the availability of novel suitable animal models of the disease. Zebrafish (Danio rerio) represents a useful platform for the study of the mechanisms responsible for human hereditary diseases, including sphingolipidoses, and for the identification of new therapeutics. Two co-orthologues of human GALC have been identified in zebrafish, named galca and galcb. Here, we generated a mutant zebrafish line for each of the two co-orthologues by CRISPR/Cas9 genome editing. Galcb knockout (KO), but not galca KO, exerts a dramatic decrease of total GALC activity both in zebrafish embryos and in the brain of adult mutants. At 3-4 months post-fertilization, galcb KO zebrafish showed impaired locomotion and reduced lifespan. Gene expression analysis, immunohistochemistry, spectral confocal reflectance and transmission electron microscopy showed the presence of demyelination, neuroinflammation and neurodegeneration in the brain of galcb KO mutants. Notably, double galca/galcb KO did not cause a further worsening of the disease when compared with galcb KO mutants. Finally, targeted lipidomic analysis demonstrated a dramatic accumulation of the bioactive sphingolipid LacCer in the brain of both galcb KO and double galca/galcb KO mutants with a modest increase of psychosine levels. Accordingly, activation of LacCer-related signalling occurs in the brain of galcb KO animals. Furthermore, intraventricular injection of LacCer upregulates the expression of various proinflammatory markers and increase mpeg1-positive macrophage infiltration in the brain of 5 dpf zebrafish embryos. In conclusion, galcb KO zebrafish recapitulates several pathological features of KD and is characterized by the accumulation of the bioactive LacCer. This model sheds new light on a possible role of LacCer as a neuroinflammatory/neurodegenerative metabolite in KD with implications for the development of novel therapeutic strategies.

Gaucher disease (GD) is one of the most common lysosomal storage disorders. It is caused by bi-allelic mutations in the GBA1 gene responsible for the production of β-glucocerebrosidase, an enzyme responsible for the hydrolysis of the sphingolipid glucocerebroside. This results in its accumulation in various organs, and patients can present with a variety of symptoms ranging from visceral enlargement, bone pathology and hematological manifestations. Neuronopathic effects are seen in the severe form of the disease. GD patients also have an increased risk of B-cell malignancies. Some of the hematological symptoms of GD resemble those of the systemic hyperinflammatory condition, hemophagocytic lymphohistiocytosis (HLH). HLH can be familial, due to functional deficiencies in cytotoxic lymphocytes, or acquired from a variety of causes ranging from infections to blood cancers. While patients with inherited and acquired HLH receive the same first-line therapy, patients with the familial form can only be cured by stem cell transplantation, although this treatment may be detrimental to patients with the acquired form of the disease. Therefore, we investigated whether the abnormal lipid accumulation in GD patient cytotoxic lymphocytes and in cells with irreversibly inhibited glucocerebrosidase activity affects their cytotoxicity. Our detailed analysis of primary cytotoxic T lymphocytes and natural killer cells revealed that the activity of these cells was not affected. This finding has important implications for the treatment choices for patients with GD and suggests that these patients can be treated with autologous immunotherapy if they develop hematological cancers.

Lysosomal storage diseases (LSDs) are a class of hereditary metabolic disorders primarily caused by lysosomal enzyme defects, leading to the accumulation of undegraded substrates. Sphingolipidoses, a subset of LSDs, are primarily associated with profound involvement of the central nervous system (CNS), characterized by progressive neurodegeneration due to massive sphingolipid accumulation. A common pathological feature among many CNS-involved LSDs is the early activation of microglia and astrocytes, which often precedes and predicts regions of subsequent neuronal loss. The extent to which neuroinflammation disrupts CNS homeostasis appears to be determined by its onset, magnitude, and duration. Although neuroinflammatory processes are increasingly recognized as critical contributors to disease progression in sphingolipidoses, the molecular mechanisms underlying glial activation and the initiation of inflammatory cascades remain incompletely understood. Therefore, mouse models of sphingolipidoses have been instrumental in elucidating these pathogenic processes and provide valuable platforms for evaluating therapeutic strategies. This review critically examines the role of neuroinflammation in sphingolipidoses, summarizes insights derived from pre-clinical models, and discusses the therapeutic potential of anti-inflammatory interventions to mitigate CNS pathology and improve clinical outcomes.

Fabry disease (FD) is an X-linked lysosomal sphingolipidosis. It is caused by pathogenic variants in the GLA gene with a consequent deficiency of the enzyme α-galactosidase A, resulting in the pathological accumulation of glycolipids - mainly globotriosyl ceramide (GL-3, GB3) and its deacylated product, globotriaosylsphingosine (Lyso-Gb-3) - in plasma and in a wide variety of cell types throughout the human body; it is characterized as a chronic, multisystemic disease with progressive evolution, which causes deterioration of the patient's quality of life and decreases survival and life expectancy.In Latin America there are different limitations to the management of patients with Fabry disease, in most countries, access to diagnostic tools and treatment on time is complex and can sometimes suffer delays in its implementation. This situation is due to the high costs to health systems of follow-up and pharmacological therapy for Fabry patients, creating barriers to timely access. Although medical criteria are fundamental in the choice of pharmacological therapy, the final decision should also rely on the patient's choice according to their expectations and the adherence and compliance with the treatment that they are willing to follow. As it has been described, there are currently three therapeutic options, for which the appropriate profile must be defined to achieve the best clinical outcomes, considering that it is a permanent treatment; experts consider that Fabry patients need comprehensive and interdisciplinary management to stop the progression and functional deterioration of the affected organs by its multiple systemic manifestations. In Latin-American countries, it is difficult to guarantee this comprehensive and coordinated management, due to limited public policies related to orphan diseases diagnosis, treatment and follow up.It is considered crucial to structure support networks specialized in Fabry disease and generate partnerships with health institutions and other health system stakeholders, that would articulate and coordinate patients and relatives counseling and management, establish the specific pharmacological treatment to reduce the progression of the disease and the systemic involvement, deciding between the administration of enzyme replacement therapy or the most recent option of oral management with pharmacological chaperone both with proven effectiveness. This will be the decision of the attending physician, who will propose and advise the therapeutic choice that best suits the patient's needs.

Lysosomal storage disorders (LSD) are a group of inherited inborn metabolism errors that are characterized by a deficiency in the lysosomal enzyme. In patients with suspected lipid storage disorders, confirmation of the diagnosis relies predominantly on the measurement of specific enzymatic activities and molecular genetic studies. New approaches to the measurement of lysosphingolipids have been developed that may serve as a rapid first-tier screening tests for the evaluation of lysosomal storage disorders. The present study evaluates the results of lysosphingolipid screening tests in patients with suspected lysosomal storage diseases. Lysosphingolipid elevation was detected in five patients examined with suspected lysosomal storage disease, and a definitive diagnosis was reached based on genetic analysis. Our data support recent evidence of the primary role of LysoSLs in the diagnosis of sphingolipidosis, and suggest that these biomarkers may be used for diagnosis and treatment monitoring in the future. Lysosomale Speicherstörungen (LSD) sind eine Gruppe erblicher angeborener Stoffwechselstörungen, die durch einen Mangel des lysosomalen Enzyms gekennzeichnet sind. Bei Patienten mit Verdacht auf Lipidspeicherstörungen stützt sich die Diagnosesicherung überwiegend auf die Messung spezifischer enzymatischer Aktivitäten und molekulargenetische Untersuchungen. Es wurden neue Ansätze zur Messung von Lysosphingolipiden entwickelt, die als schnelle Screening-Tests der ersten Stufe zur Beurteilung lysosomaler Speicherstörungen dienen können. Die vorliegende Studie wertet die Ergebnisse von Lysosphingolipid-Screeningtests bei Patienten mit Verdacht auf lysosomale Speicherkrankheiten aus. Bei fünf untersuchten Patienten mit Verdacht auf eine lysosomale Speicherkrankheit wurde ein Anstieg des Lysosphingolipids festgestellt, und auf der Grundlage einer genetischen Analyse konnte eine endgültige Diagnose gestellt werden. Unsere Daten stützen aktuelle Hinweise auf die primäre Rolle von LysoSLs bei der Diagnose von Sphingolipidose und legen nahe, dass diese Biomarker in Zukunft für die Diagnose und Behandlungsüberwachung verwendet werden könnten.