Determination of globotriaosylceramide analogs in the organs of a mouse model of Fabry disease

Distinctive accumulation of globotriaosylceramide and globotriaosylsphingosine in a mouse model of classic Fabry disease

Fabry disease (FD) is an inherited disease caused by deficient α-galactosidase A activity that is characterized by the accumulation of globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3). Although plasma lyso-Gb3 is a sensitive biomarker of FD, the correlation between its concentration and clinical symptoms remains unclear. To clarify the influence of plasma Gb3 and lyso-Gb3 in a symptomatic Gla ^tm Tg(CAG-A4GALT) FD mouse model, the total contents of Gb3, lyso-Gb3 and their analogs in various organs and plasma were determined in mice with early- (5-week-old) and late-stage (20-week-old) renal dysfunction. A marked increase in total Gb3 content in the heart, kidneys, spleen, liver, small intestine, lungs, brain, and plasma was observed in the 20-week-old mice compared to that in 5-week-old mice. In contrast, the increase in lyso-Gb3 was relatively small, and the total content in the lungs and plasma was unchanged. Lyso-Gb3 analogs {lyso-Gb3(-2) and lyso-Gb3(+18)} and Gb3 analogs {Gb3(-2) and Gb3(+18)} were observed in all organs and plasma at both ages, and the percentages of the analogs were unique to specific organs. The pattern of 37 Gb3 analogs/isoforms of liver Gb3 corresponded well with that of plasma Gb3. Although the analog pattern of plasma lyso-Gb3 did not resemble that of any organ lyso-Gb3, the relative content {lyso-Gb3: lyso-Gb3(-2)} in the sum of all organs corresponded well to that of the plasma at both ages. These data indicate that liver Gb3 may contribute to the plasma Gb3 level, while plasma lyso-Gb3 may be released from all organs, and the capacity of the plasma lyso-Gb3 pool may reach a maximum at an early stage of renal dysfunction.

A universal GlycoDesign for lysosomal replacement enzymes to improve circulation time and biodistribution

Currently available enzyme replacement therapies for lysosomal storage diseases are limited in their effectiveness due in part to short circulation times and suboptimal biodistribution of the therapeutic enzymes. We previously engineered Chinese hamster ovary (CHO) cells to produce α-galactosidase A (GLA) with various N-glycan structures and demonstrated that elimination of mannose-6-phosphate (M6P) and conversion to homogeneous sialylated N-glycans prolonged circulation time and improved biodistribution of the enzyme following a single-dose infusion into Fabry mice. Here, we confirmed these findings using repeated infusions of the glycoengineered GLA into Fabry mice and further tested whether this glycoengineering approach, Long-Acting-GlycoDesign (LAGD), could be implemented on other lysosomal enzymes. LAGD-engineered CHO cells stably expressing a panel of lysosomal enzymes [aspartylglucosamine (AGA), beta-glucuronidase (GUSB), cathepsin D (CTSD), tripeptidyl peptidase (TPP1), alpha-glucosidase (GAA) or iduronate 2-sulfatase (IDS)] successfully converted all M6P-containing N-glycans to complex sialylated N-glycans. The resulting homogenous glycodesigns enabled glycoprotein profiling by native mass spectrometry. Notably, LAGD extended the plasma half-life of all three enzymes tested (GLA, GUSB, AGA) in wildtype mice. LAGD may be widely applicable to lysosomal replacement enzymes to improve their circulatory stability and therapeutic efficacy.

Fabry disease pain: patient and preclinical parallels

ABSTRACT

Severe neuropathic pain is a hallmark of Fabry disease, a genetic disorder caused by a deficiency in lysosomal α-galactosidase A. Pain experienced by these patients significantly impacts their quality of life and ability to perform everyday tasks. Patients with Fabry disease suffer from peripheral neuropathy, sensory abnormalities, acute pain crises, and lifelong ongoing pain. Although treatment of pain through medication and enzyme replacement therapy exists, pain persists in many of these patients. Some has been learned in the past decades regarding clinical manifestations of pain in Fabry disease and the pathological effects of α-galactosidase A insufficiency in neurons. Still, it is unclear how pain and sensory abnormalities arise in patients with Fabry disease and how these can be targeted with therapeutics. Our knowledge is limited in part due to the lack of adequate preclinical models to study the disease. This review will detail the types of pain, sensory abnormalities, influence of demographics on pain, and current strategies to treat pain experienced by patients with Fabry disease. In addition, we discuss the current knowledge of Fabry pain pathogenesis and which aspects of the disease preclinical models accurately recapitulate. Understanding the commonalities and divergences between humans and preclinical models can be used to further interrogate mechanisms causing the pain and sensory abnormalities as well as advance development of the next generation of therapeutics to treat pain in patients with Fabry disease.