Glycosphingolipid profile of the apical pole of human placental capillaries: the relevancy of the observed data to Fabry disease

Effects of GBA1 Variants and Prenatal Exposition on the Glucosylsphingosine (Lyso-Gb1) Levels in Gaucher Disease Carriers

Gaucher disease (GD) is a lysosomal lipid storage disorder caused by β-glucocerebrosidase (encoded by GBA1 gene) activity deficiency, resulting in the accumulation of glucosylceramide (Gb1) and its deacylated metabolite glucosylsphingosine (lyso-Gb1). Lyso-Gb1 has been studied previously and proved to be a sensitive biomarker, distinguishing patients with GD from carriers and healthy subjects. It was shown that its level corresponds with β-glucocerebrosidase activity, thus it remains unknown as to why carriers have slightly higher lyso-Gb1 level than healthy population. This is the first report on lyso-Gb1 levels describing representative cohort of GD carriers. Our data of 48 GD carriers, including three newborns, indicated that there are significant differences in lyso-Gb1 levels between carriers having a GD-affected mother and a healthy mother (11.53 and 8.45, respectively, p = 0.00077), and between carriers of the L483P GBA1 variant and carriers of other GBA1 pathogenic variants (9.85 and 7.03, respectively, p = 0.07). Through analysing our unique data of three newborns whose mothers are patients with GD, we also found that lyso-Gb1 is most probably transferred to the foetus via placenta.

Hematopoietic stem cell transplantation leads to biochemical and functional correction in two mouse models of acid ceramidase deficiency

Farber disease (FD) and spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME) are ultra-rare lysosomal storage disorders caused by deficient acid ceramidase (ACDase) activity. Although both conditions are caused by mutations in the ASAH1 gene, clinical presentations differ considerably. FD patients usually die in childhood, while SMA-PME patients can live until adulthood. There is no treatment for FD or SMA-PME. Hematopoietic stem cell transplantation (HSCT) and gene therapy strategies for the treatment of ACDase deficiency are being investigated. We have previously generated and characterized mouse models of both FD and SMA-PME that recapitulate the symptoms described in patients. Here, we show that HSCT improves lifespan, behavior, hematopoietic system anomalies, and plasma cytokine levels and significantly reduces histiocytic infiltration and ceramide accumulation throughout the tissues investigated, including the CNS, in both models of ACDase-deficient mice. HSCT was also successful in preventing lesion development and significant demyelination of the spinal cord seen in SMA-PME mice. Importantly, we note that only early and generally pre-symptomatic treatment was effective, and kidney impairment was not improved in either model.

Sphingolipids as Potential Therapeutic Targets against Enveloped Human RNA Viruses

Several notable human diseases are caused by enveloped RNA viruses: influenza, AIDS, hepatitis C, dengue hemorrhagic fever, microcephaly, and Guillain-Barré Syndrome. Being enveloped, the life cycle of this group of viruses is critically dependent on host lipid biosynthesis. Viral binding and entry involve interactions between viral envelope glycoproteins and cellular receptors localized to lipid-rich regions of the plasma membrane. Subsequent infection by these viruses leads to reorganization of cellular membranes and lipid metabolism to support the production of new viral particles. Recent work has focused on defining the involvement of specific lipid classes in the entry, genome replication assembly, and viral particle formation of these viruses in hopes of identifying potential therapeutic targets for the treatment or prevention of disease. In this review, we will highlight the role of host sphingolipids in the lifecycle of several medically important enveloped RNA viruses.

N-butyldeoxynojirimycin delays motor deficits, cerebellar microgliosis, and Purkinje cell loss in a mouse model of mucolipidosis type IV

Mucolipidosis type IV (MLIV) is a lysosomal storage disease exhibiting progressive intellectual disability, motor impairment, and premature death. There is currently no cure or corrective treatment. The disease results from mutations in the gene encoding mucolipin-1, a transient receptor potential channel believed to play a key role in lysosomal calcium egress. Loss of mucolipin-1 and subsequent defects lead to a host of cellular aberrations, including accumulation of glycosphingolipids (GSLs) in neurons and other cell types, microgliosis and, as reported here, cerebellar Purkinje cell loss. Several studies have demonstrated that N-butyldeoxynojirimycin (NB-DNJ, also known as miglustat), an inhibitor of the enzyme glucosylceramide synthase (GCS), successfully delays the onset of motor deficits, improves longevity, and rescues some of the cerebellar abnormalities (e.g., Purkinje cell death) seen in another lysosomal disease known as Niemann-Pick type C (NPC). Given the similarities in pathology between MLIV and NPC, we examined whether miglustat would be efficacious in ameliorating disease progression in MLIV. Using a full mucolipin-1 knockout mouse (Mcoln1-/-), we found that early miglustat treatment delays the onset and progression of motor deficits, delays cerebellar Purkinje cell loss, and reduces cerebellar microgliosis characteristic of MLIV disease. Quantitative mass spectrometry analyses provided new data on the GSL profiles of murine MLIV brain tissue and showed that miglustat partially restored the wild type profile of white matter enriched lipids. Collectively, our findings indicate that early miglustat treatment delays the progression of clinically relevant pathology in an MLIV mouse model, and therefore supports consideration of miglustat as a therapeutic agent for MLIV disease in humans.

Does a "thiol shield" protect tumors from natural IgM antibody, and, if so, how can it be suppressed?

Natural anti-tumor IgM antibodies are prevalent in the serum of cancer patients and normal subjects. Extensive research has been directed toward the ultimate goal of achieving a therapeutic effect from these antibodies either augmented by vaccination or by passive infusion. To date, the therapeutic effects have been limited. This thesis asserts that thiols within solid tumors reduce pentameric IgM to monomeric or other subunit form resulting in inactivation of its complement fixing and cross linking apoptosis inducing properties. A rationale for this normal physiological inactivation mechanism, possibly necessary for wound healing and pregnancy, is proposed along with therapeutic approaches, which would potentially suppress IgM inactivation.