Enzyme replacement therapy of a novel humanized mouse model of globoid cell leukodystrophy

In Krabbe disease, a mutation in GALC gene causes widespread demyelination determining cell death by apoptosis, mainly in oligodendrocytes and Schwann cells. Less is known on the molecular mechanisms induced by this deficiency. Here, we report an impairment in protein synthesis and degradation and in proteasomal clearance with a potential accumulation of the misfolded proteins and induction of the endoplasmic reticulum stress in the brain of 6-day-old twitcher mice (TM) (model of Krabbe disease). In particular, an imbalance of the immunoproteasome function was highlighted, useful for shaping adaptive immune response by neurological cells. Moreover, our data show an involvement of cytoskeleton remodeling in Krabbe pathogenesis, with a lamin meshwork disaggregation in twitcher oligodendrocytes in 6-day-old TM. This study provides interesting protein targets and mechanistic insight on the early onset of Krabbe disease that may be promising options to be tested in combination with currently available therapies to rescue Krabbe phenotype.

Section: Analysis Of Protein Synthesis and Degradation Markersmentioning

confidence: 99%

mentioning

confidence: 99%

Proteostasis network alteration in lysosomal storage disorders: Insights from the mouse model of Krabbe disease

Landi

Luddi

Bianchi

et al. 2019

“…In cell culture studies, GALC‐deficient OLs were able to take up exogenous GALC enzyme (Luddi et al, ; Kondo et al, ). In addition, systemic GALC treatments of twi mice as well as human mutant GALC knockin mice were reported to reduce the CNS PSY accumulation (Lee et al, ; Matthes et al, ). However, current ERT therapy based on recombinant GALC ERT was not successful in stopping the death of animals from KD pathologies (Lee et al, ; Matthes et al, ).…”

Section: Therapeutic Approaches For Kdmentioning

confidence: 99%

“…In addition, systemic GALC treatments of twi mice as well as human mutant GALC knockin mice were reported to reduce the CNS PSY accumulation (Lee et al, ; Matthes et al, ). However, current ERT therapy based on recombinant GALC ERT was not successful in stopping the death of animals from KD pathologies (Lee et al, ; Matthes et al, ). The reasons for the limited efficacy of recombinant GALC ERT are reported to be its inability to cross the BBB and low cross‐correction efficiency of recombinant wild‐type (WT) GALC (Wenger et al, ; Meng et al, ; Kim, ).…”

Section: Therapeutic Approaches For Kdmentioning

confidence: 99%

Biochemical, cell biological, pathological, and therapeutic aspects ofKrabbe's disease

Won

Singh

2016

Krabbe disease (KD; also called globoid cell leukodystrophy) is a genetic disorder involving demyelination of the central (CNS) and peripheral (PNS) nervous systems. The disease may be subdivided into three types; an infantile form which is most common and severe, a juvenile form, and a rare adult form. KD is an autosomal recessive disorder caused by a deficiency of galactocerebrosidase (GALC) activity in lysosomes leading to accumulation of galactoceramide and neurotoxic galactosylsphingosine (psychosine) in macrophages (globoid cells) as well as neural cells especially in oligodendrocytes and Schwann cells. This ultimately results in damage to myelin in both CNS and PNS with associated morbidity and mortality. Accumulation of psychosine, a lysolipid with detergent-like properties, over a threshold level could trigger membrane destabilization leading to cell lysis. Moreover, sub-threshold concentrations of psychosine trigger cell signaling pathways that induce oxidative stress, mitochondrial dysfunction, apoptosis, inflammation, endothelial/vascular dysfunctions, and neuronal and axonal damage. Since the proposed “psychosine hypothesis” considerable efforts have been made in search for effective therapy for lowering psychosine load using pharmacological, gene and stem cell approaches to attenuate psychosine-induced neurotoxicity. In this review, we focus on the recent advances and prospective research on understanding of disease mechanisms and therapeutic approaches for KD.

“…After the success of ERT for non‐CNS LSDs, such as Gaucher's disease (Shayman, ; Marshal et al, ), a significant advance has been the development of a “humanized” mouse model of KD by inserting a human GALC cDNA containing an adult‐onset patient mutation into the murine GALC gene. Such mice were found to exhibit all the pathological hallmarks of KD, including psychosine accumulation, neuroinflammation, CNS infiltration of macrophages, astrogliosis, and demyelination (Matthes et al, ). Residual GALC activities in mouse tissues were low, and the mice had a reduced life span of 46 days.…”

Section: Current Status Of Therapy For Kdmentioning

confidence: 99%

Quantum dots and potential therapy for Krabbe's disease

Dawson

2016

Enzyme replacement therapy and substrate reduction therapy have proved useful in reversing many pathological consequences of many non-neural lysosomal storage diseases but have not yet reversed pathology or influenced disease outcome in Krabbe disease, We will discuss the relative merits of stem cell therapy, molecular chaperone therapy, gene therapy, substrate reduction therapy, enzyme replacement therapy and combination therapy. Given the limitations of these approaches we will introduce the idea of using tiny 6nm intensely fluorescent Quantum dots to deliver a cell-penetrating peptide and His6-tagged beta-D-galactosidase across the blood-brain barrier. We can therefore follow the fate of injected material and ensure that all targets are reached and accumulated material is degraded. Uptake of lysosomal hydrolases is a complex process and our cell-penetrating peptide JB577 is uniquely able to promote endosomal egress of the QD-cargo. We further show that uptake may depend on the charge of the coating of the Quantum dot, specifically that negative charge directs the cargo to neurons. Since Krabbe disease primarily involves glia, specifically oligodendroglia we experimented with many coatings and discovered a positive charged coating (Polyethyleneglycol 600-amino) which had a positive charge and targeted oligodendrocytes. A similar effect was achieved by treating with chondroitinase ABC to degrade the extracellular matrix, indicating that enzyme replacement has several hurdles to overcome before it can become a routine CNS therapy.Enzyme replacement therapy and substrate reduction therapy have proved useful in reversing many pathological consequences of lysosomal storage disease (LSD) in extraneural tissue of storage disease patients but have not been found to reverse pathology or influence disease outcome in a human neurological lysosomal storage disease such as Krabbe disease. Thus there is an unmet need to come up with a new approach to the delivery of either beta-Dgalactocerebrosidase enzyme protein or low molecular weight inhibitors of Ceramide: galactosyltransferase (substrate reduction therapy) to patients with Krabbe disease. Protein delivery to the CNSDelivering a protein across a cell membrane and having it retain its biological function inside the cell is a major challenge in biology and medicine because of the blood-brain barrier. Many cells have developed a type of receptor (a "coated pit") which facilitates the uptake of nutritive proteins such as lipoproteins (the Apo-E LDL receptor) and transferrin but for the most part they have not evolved to take up proteins from the extracellular space and proteins are endocytosed at a very low rate (Masliah and Spencer 2015). Notable exceptions to this rule are the lysosomal hydrolases, some of which use a phosphorylated sugar (Mannose-6-phosphate) and a specific receptor to exchange enzymes between cells. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptThis specialized system has been taken advantage of to car...