Managing Cardiovascular Risk in Lysosomal Acid Lipase Deficiency

Distinguishing Lysosomal Acid Lipase Deficiency From Familial Hypercholesterolemia

Lysosomal acid lipase deficiency (LAL-D) is underrecognized because it manifests clinically with lipid and lipoprotein values similar to those observed in heterozygous familial hypercholesterolemia (FH). Although LAL-D is uncommon, understanding the differences between the 2 diseases has significant management implications. We present a case of LAL-D that masqueraded as FH. (Level of Difficulty: Advanced.).

Lysosomal Acid Lipase Deficiency: Genetics, Screening, and Preclinical Study

Lysosomal acid lipase (LAL) is a lysosomal enzyme essential for the degradation of cholesteryl esters through the endocytic pathway. Deficiency of the LAL enzyme encoded by the LIPA gene leads to LAL deficiency (LAL-D) (OMIM 278000), one of the lysosomal storage disorders involving 50-60 genes. Among the two disease subtypes, the severe disease subtype of LAL-D is known as Wolman disease, with typical manifestations involving hepatomegaly, splenomegaly, vomiting, diarrhea, and hematopoietic abnormalities, such as anemia. In contrast, the mild disease subtype of this disorder is known as cholesteryl ester storage disease, with hypercholesterolemia, hypertriglyceridemia, and high-density lipoprotein disappearance. The prevalence of LAL-D is rare, but several treatment options, including enzyme replacement therapy, are available. Accordingly, a number of screening methodologies have been developed for this disorder. This review summarizes the current discussion on LAL-D, covering genetics, screening, and the tertiary structure of human LAL enzyme and preclinical study for the future development of a novel therapy.

Early Discovery of Children With Lysosomal Acid Lipase Deficiency With the Universal Familial Hypercholesterolemia Screening Program

Lysosomal acid lipase deficiency (LAL-D) is an autosomal recessive lysosomal storage disorder, caused by homozygous or compound heterozygous pathogenic variants in the LIPA gene. Clinically, LAL-D is under- and misdiagnosed, due to similar clinical and laboratory findings with other cholesterol or liver misfunctions. As a part of the Slovenian universal familial hypercholesterolemia (FH) screening, LAL-D is screened as a secondary condition among other rare dyslipidemias manifesting with hypercholesterolemia. Out of 669 children included, three were positive for a homozygous disease-causing splicing variant NM_000235.4: c.894G > A (NP_000226.2:p. Gln298Gln) in the LIPA gene (NG_008194.1). The mean age by the diagnosis of LAL-D was 9.8 ± 0.9 years. Moreover, all three LAL-D-positive children had an important elevation of transaminases and decreased activity of the lysosomal acid lipase enzyme. Abdominal MRI in all children detected an enlarged liver but a normal-sized spleen. In conclusion, universal FH screening algorithms with the confirmatory genetic analysis in the pediatric population enable also rare dyslipidemia detection at an early age. An important clinical criterion for differentiation between FH and the LAL-D-positive children has elevated transaminase levels (AST and ALT). In all three LAL-D positive children, an improvement in cholesterol and transaminase levels and steatosis of the liver has been seen after early treatment initiation.

Long-Term Sebelipase Alfa Treatment in Children and Adults With Lysosomal Acid Lipase Deficiency

OBJECTIVES

Sebelipase alfa is approved for treatment of lysosomal acid lipase deficiency (LAL-D). This single-arm, open-label study (NCT02112994) evaluated sebelipase alfa efficacy and safety in patients with LAL-D.

METHODS

Patients >8 months of age diagnosed with LAL-D received sebelipase alfa 1.0 mg/kg by intravenous infusion every other week (qow) for up to 144 weeks. Dose escalation to 3.0 mg/kg qow and subsequently to 3.0 mg/kg weekly was permitted, per protocol; dose reductions for tolerability were permitted to 0.35 mg/kg qow. Descriptive statistical analyses were conducted.

RESULTS

Thirty-one patients were enrolled and treated. Baseline median alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were 63.5 and 65.5 U/L, respectively. Twenty-eight patients completed 96 weeks of treatment, and 25 continued into the extended treatment period; 19 completed 144 weeks. From baseline to week 144, median ALT and AST levels changed by -42.0 and -22.0 U/L, respectively, median liver and spleen volumes changed from 1.4 to 1.3 and from 2.6 to 2.3 multiples of normal, respectively, median low-density lipoprotein cholesterol levels decreased by 52.6 mg/dL, and median high-density lipoprotein cholesterol increased by 9.8 mg/dL. Liver biopsies showed mostly improved or stable histopathology at 48 and 96 weeks versus baseline. Infusion-associated reactions were mild (n = 1) or moderate (n = 2). One patient (a candidate for liver transplant at baseline) discontinued treatment because of liver transplant (unrelated to treatment). Two patients tested positive for nonneutralizing, anti-drug antibodies on 1 occasion each.

CONCLUSION

Sebelipase alfa was well tolerated and resulted in sustained improvements in liver and lipid parameters.

Theranostic two-dimensional superparamagnetic maghemite quantum structures for ROS-mediated cancer therapy

In this work, size- and shape-controlled two-dimensional (2D) superparamagnetic maghemite (γ-Fe2O3) quantum flakes (MQFs) with high surface area and mesoporosity were prepared by facile hydrothermal synthesis for biological applications. These quantum flakes exhibited superparamagnetic behaviours over a wide temperature range of 75-950 K with high saturation magnetization of Ms - 23 emu g-1 and a lower coercivity of Hc - 6.1 Oe. MQFs also demonstrated a good colloidal stability and a positively charged flake surface. Selective toxicity dependent upon selective ROS scavenging/generation and cellular MQF uptake towards non-malignant human keratinocyte (HaCaT) and malignant melanoma (A357) and human breast cancer (MDA-MB 231) cell lines were witnessed. An increased ROS concentration resulted due to the peroxidase-like activity of MQFs in malignant cells. In contrast, ROS scavenging was observed in non-malignant cells due to dominant catalase-like activity. In vitro fluorescence properties added the diagnostic ability to the ambit of MQFs. Furthermore, the therapeutic efficiency could be significantly enhanced by the hyperthermic (25-47 °C) ability of MQF in cancerous cells. Our findings reveal the novel theranostic MQF structure with immense cancer therapeutic potential via augmentation of ROS generation by hyperthermia in a selective microenvironment.

Lysosomal Biology and Function: Modern View of Cellular Debris Bin

Lysosomes are the main proteolytic compartments of mammalian cells comprising of a battery of hydrolases. Lysosomes dispose and recycle extracellular or intracellular macromolecules by fusing with endosomes or autophagosomes through specific waste clearance processes such as chaperone-mediated autophagy or microautophagy. The proteolytic end product is transported out of lysosomes via transporters or vesicular membrane trafficking. Recent studies have demonstrated lysosomes as a signaling node which sense, adapt and respond to changes in substrate metabolism to maintain cellular function. Lysosomal dysfunction not only influence pathways mediating membrane trafficking that culminate in the lysosome but also govern metabolic and signaling processes regulating protein sorting and targeting. In this review, we describe the current knowledge of lysosome in influencing sorting and nutrient signaling. We further present a mechanistic overview of intra-lysosomal processes, along with extra-lysosomal processes, governing lysosomal fusion and fission, exocytosis, positioning and membrane contact site formation. This review compiles existing knowledge in the field of lysosomal biology by describing various lysosomal events necessary to maintain cellular homeostasis facilitating development of therapies maintaining lysosomal function.

Clinical and Histologic Liver Improvement in Siblings With Lysosomal Acid Lipase Deficiency After Enzyme Replacement

OBJECTIVES

To assess the effect of long-term (104 weeks) treatment with recombinant sebelipase alpha (rhSA) on serum lipid and hepatic transaminase levels, and liver histopathology in 4 siblings diagnosed with lysosomal acid lipase deficiency (LAL-D).

METHODS

Four male siblings from the same nonconsanguineous parents were diagnosed with the late-onset phenotype of LAL-D in 2015. Liver specimens were obtained by biopsy at baseline and after 104 weeks of enzyme replacement with rhSA (1 mg/kg, IV, every 2 weeks). Hepatic transaminase, lipid and lipoprotein levels were assessed at baseline and sequentially every 16 weeks for 104 weeks. Hepatic steatosis was evaluated from hematoxylin and eosin-stained specimens, and fibrosis was evaluated (Metavir-scoring system) from trichrome-stained specimens obtained at baseline and following 104 weeks of treatment with rhSA.

RESULTS

All 4 siblings had improvement in their serum lipid and hepatic transaminase levels after treatment with rhSA. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels decreased from baseline by an average of 47% and 56%, respectively. The fasting triglyceride and low-density lipoprotein cholesterol (LDL-C) levels decreased from baseline by an average of 43% and 60%, respectively. Hepatic steatosis decreased from baseline grade 3 to posttreatment grade 1. Hepatic fibrosis did not advance following 104 weeks of treatment with rhSA and regressed in 1 sibling.

CONCLUSIONS

Treatment with rhSA for 104 weeks in 4 siblings with LAL-D demonstrated improvement in their hepatic transaminase and serum lipid levels, accompanied by reduction of hepatic steatosis and no progression of fibrosis.

Silver-coated zero-valent iron nanoparticles enhance cancer therapy in mice through lysosome-dependent dual programed cell death pathways: triggering simultaneous apoptosis and autophagy only in cancerous cells

In this study, we demonstrated that zero-valent iron (ZVI), which is widely used to remediate environmental contamination through the production of high-energy reactive oxygen species (ROS), exhibited differential cytotoxicity in cancerous cells and nonmalignant cells. Nanoparticles (NPs) with different shells exhibited distinct potencies against cancerous cells, which depended on their iron-to-oxygen ratios. Silver-coated ZVI NPs (ZVI@Ag) had the highest potency among synthesized ZVI NPs, and they simultaneously exhibited adequate biocompatibility with nonmalignant keratinocytes. The assessment of the intracellular dynamics of iron species revealed that the uptake of ZVI@Ag was similar between cancerous cells and nonmalignant cells during the first 2 h; however, only cancerous cells rapidly converted NPs into iron ions and generated large amounts of intracellular ROS, which was followed by apoptosis and autophagy induction. The aforementioned processes were prevented in the presence of iron ion chelators or by preoxidizing NPs before administration. Neutralization of lysosomal pH effectively reduced ZVI@Ag NP-induced programmed cell death. In the xenograft mouse model, cancer growth was significantly inhibited by a single dose of systematically administered NPs without significant weight loss in animals.

Association Between LOX-1, LAL, and ACAT1 Gene Single Nucleotide Polymorphisms and Carotid Plaque in a Northern Chinese Population

Objective: Carotid atherosclerosis is one of the major risk factors for ischemic stroke. The presence of carotid plaque has been widely used to assess the risk of clinical atherosclerotic disease. Lectin-type oxidized LDL (low-density lipoprotein) receptor 1 (LOX-1), lysosomal acid lipase (LAL), and acyl-CoA:cholesterol acyltransferase 1 (ACAT1) are important for lipid accumulation in atherosclerosis. The objective of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) in the LOX-1, LAL, and ACAT1 genes and the presence of carotid plaque in a Northern Chinese population. Methods: Three polymorphisms in LOX-1 (rs1050286), LAL (rs11203042), and ACAT1 (rs11576517) were identified and genotyped in 215 patients with carotid plaque and 252 controls using the polymerase chain reaction with high-resolution melting analysis. Results: The LOX-1 (rs1050286) AA and LAL (rs11203042) TT genotypes were significantly associated with increased risk of carotid plaque, whereas a ACAT1 (rs11576517) TT genotype was shown to be protective against carotid plaque in a Northern Chinese population (p < 0.05). Even after the Bonferroni correction, the LAL (rs11203042) TT genotype (odds ratio = 3.838, 95% confidence interval = 1.748-8.426, p < 0.001) was still associated with an increased risk for carotid plaque. Conclusions: These results suggest that the LAL (rs11203042) TT genotype is associated with increased risk for carotid plaque in a Northern Chinese population, and that the LOX-1 (rs1050286) AA genotype shows a nonstatistically significant trend towards association. However, no association was found between the ACAT1 (rs11576517) polymorphisms and carotid plaque presence.

Persistent dyslipidemia in treatment of lysosomal acid lipase deficiency

BACKGROUND

Lysosomal acid lipase deficiency (LALD) is an autosomal recessive inborn error of lipid metabolism characterized by impaired lysosomal hydrolysis and consequent accumulation of cholesteryl esters and triglycerides. The phenotypic spectrum is diverse, ranging from severe, neonatal onset failure to thrive, hepatomegaly, hepatic fibrosis, malabsorption and adrenal insufficiency to childhood-onset hyperlipidemia, hepatomegaly, and hepatic fibrosis. Sebelipase alfa enzyme replacement has been approved by the Food and Drug Administration for use in LALD after demonstrating dramatic improvement in transaminitis and dyslipidemia with initiation of enzyme replacement therapy.

METHODS

A chart review was performed on 2 patients with childhood-onset, symptomatic LALD with persistent dyslipidemia despite appropriate enzyme replacement therapy to identify biological pathways and risk factors for incomplete response to therapy.

RESULTS

Two patients with attenuated, symptomatic LALD had resolution of transaminitis on enzyme replacement therapy without concomitant effect on dyslipidemia despite dose escalation and no evidence of antibody response to enzyme.

CONCLUSION

Enzyme replacement therapy does not universally resolve all complications of LALD. Persistent dyslipidemia remains a clinically significant issue, likely related to the complex metabolic pathways implicated in LALD pathogenesis. We discuss the possible mechanistic basis for this unexpected finding and the implications for curative LALD therapy.

Initial assessment and ongoing monitoring of lysosomal acid lipase deficiency in children and adults: Consensus recommendations from an international collaborative working group

BACKGROUND

Lysosomal acid lipase (LAL) deficiency is an ultra-rare, progressive, autosomal recessive disorder. Functional mutations in LIPA, the gene that encodes LAL, result in accumulation of cholesteryl esters and triglycerides in hepatocytes and in the macrophages of the intestines, vascular endothelial system, and numerous other organs. LAL deficiency has a broad clinical spectrum; children and adults can present with dyslipidemia, liver enzyme elevations, hepatosplenomegaly, hepatic steatosis, liver fibrosis and/or cirrhosis, and vascular disease, which may lead to significant morbidity and premature mortality in some patients. Given the systemic involvement and the wide range of healthcare specialists who manage patients with LAL deficiency, there is a need for guidelines to assess and monitor disease involvement.

OBJECTIVES

To provide a set of recommendations for the initial assessment and ongoing monitoring of patients with LAL deficiency to help physicians in various disciplines effectively manage the disease based on the observed presentation and progression in each case.

METHODS

A group of internationally recognized healthcare specialists with expertise in clinical genetics, pathology, hepatology, gastroenterology, cardiology, and lipidology convened to develop an evidence-based consensus of best practices for the initial assessment and ongoing monitoring of children and adults with LAL deficiency, regardless of treatment status; infants with LAL deficiency have been excluded from these guidelines because they require specialized care.

RESULTS

The authors present guidance for the assessment and monitoring of patients with LAL deficiency based on age and disease manifestations that include the hepatic, cardiovascular, and gastrointestinal systems. A schedule for ongoing monitoring of disease progression is provided. In addition, the need to establish an interdisciplinary and integrated care team to optimize the approach to managing this systemic disease is highlighted.

CONCLUSIONS

There is currently no published guidance on the assessment and monitoring of patients with LAL deficiency. These consensus recommendations for the initial assessment and ongoing monitoring of children and adults with LAL deficiency are intended to help improve the management of these patients.

Sebelipase alfa improves atherogenic biomarkers in adults and children with lysosomal acid lipase deficiency

BACKGROUND

Measures of atherogenic cholesterol, with and without concomitant use of lipid-lowering medications (LLMs), are reported with up to 52 weeks of sebelipase alfa treatment in children and adults with lysosomal acid lipase deficiency (LAL-D) participating in the phase 3 Acid Lipase Replacement Investigating Safety and Efficacy study (NCT01757184).

OBJECTIVE

To examine the effects of sebelipase alfa on levels of atherogenic biomarkers in the Acid Lipase Replacement Investigating Safety and Efficacy study.

METHODS

Data were prospectively collected for LDL particle (LDL-P) number, LDL-C, HDL-C, apolipoprotein B (apoB), apolipoprotein A1 (apoA1), and LDL-P size. Differences at week 20 between the sebelipase alfa and placebo groups were assessed for the overall LAL-D cohort and for patients receiving and not receiving LLMs. Changes from baseline after up to 52 weeks of treatment were also calculated for the overall cohort and separately for patients receiving and not receiving LLMs.

RESULTS

Baseline values for LDL-C, LDL-P number, and apoB were elevated while HDL-C and apoA1 were low. Treatment with sebelipase alfa for 20 weeks significantly improved atherogenic measures compared with placebo irrespective of LLM usage. The reduction in LDL-C with sebelipase alfa was associated with a reduction in the LDL-P number. Treatment for up to 52 weeks was associated with sustained improvements of LDL-P, LDL-C, HDL-C, apoB, and apoA1, regardless of LLM use.

CONCLUSION

Patients with LAL-D have high atherogenic risk. It is essential to address the underlying LAL deficiency to restore cholesterol homeostasis in LAL-D patients, as treatment with sebelipase alfa improves atherogenic measures regardless of LLM use and for a sustained period. Sebelipase alfa appears to reduce LDL-C by decreasing the LDL-P number, suggesting improvement in cardiovascular disease risk in LAL-D patients.

Consensus document. Management of non-alcoholic fatty liver disease (NAFLD). Clinical practice guideline

Non-alcoholic fatty liver disease (NAFLD) is the main cause of liver diseases in Spain and the incidence is raising due to the outbreak of type 2 diabetes and obesity. This CPG suggests recommendation about diagnosis, mainly non-invasive biomarkers, and clinical management of this entity. Life-style modifications to achieve weight loss is the main target in the management of NAFLD. Low caloric Mediterranean diet and 200 minutes/week of aerobic exercise are encouraged. In non-responders patients with morbid obesity, bariatric surgery or metabolic endoscopy could be indicated. Pharmacological therapy is indicated in patients with NASH and fibrosis and non-responders to weight loss measures. NAFLD could influence liver transplantation, as a growing indication, the impact of steatosis in the graft viability, de novo NAFLD rate after OLT and a raised cardiovascular risk that modify the management of this entity. The current CPG was the result of the First Spanish NAFLD meeting in Seville.

Lysosomes as Oxidative Targets for Cancer Therapy

Lysosomes are membrane-bound vesicles that contain hydrolases for the degradation and recycling of essential nutrients to maintain homeostasis within cells. Cancer cells have increased lysosomal function to proliferate, metabolize, and adapt to stressful environments. This has made cancer cells susceptible to lysosomal membrane permeabilization (LMP). There are many factors that mediate LMP such as Bcl-2 family member, p53; sphingosine; and oxidative stress which are often altered in cancer. Upon lysosomal disruption, reactive oxygen species (ROS) levels increase leading to lipid peroxidation, mitochondrial dysfunction, autophagy, and reactive iron. Cathepsins are also released causing degradation of macromolecules and cellular structures. This ultimately kills the cancer cell through different types of cell death (apoptosis, autosis, or ferroptosis). In this review, we will explore the contributions lysosomes play in inducing cell death, how this is regulated by ROS in cancer, and how lysosomotropic agents might be utilized to treat cancers.