CYP4F2 affects phenotypic outcome in adrenoleukodystrophy by modulating the clearance of very long-chain fatty acids

Lipidomic biomarkers in plasma correlate with disease severity in adrenoleukodystrophy

BACKGROUND

X-linked adrenoleukodystrophy (ALD) is a neurometabolic disorder caused by pathogenic variants in ABCD1 resulting very long-chain fatty acids (VLCFA) accumulation in plasma and tissues. Males can present with various clinical manifestations, including adrenal insufficiency, spinal cord disease, and leukodystrophy. Female patients typically develop spinal cord disease and peripheral neuropathy. Predicting the clinical outcome of an individual patient remains impossible due to the lack of genotype-phenotype correlation and predictive biomarkers.

METHODS

The availability of a large prospective cohort of well-characterized patients and associated biobank samples allowed us to investigate the relationship between lipidome and disease severity in ALD. We performed a lipidomic analysis of plasma samples from 24 healthy controls, 92 male and 65 female ALD patients.

RESULTS

Here we show that VLCFA are incorporated into different lipid classes, including lysophosphatidylcholines, phosphatidylcholines, triglycerides, and sphingomyelins. Our results show a strong association between higher levels of VLCFA-containing lipids and the presence of leukodystrophy, adrenal insufficiency, and severe spinal cord disease in male ALD patients. In female ALD patients, VLCFA-lipid levels correlate with X-inactivation patterns in blood mononuclear cells, and higher levels are associated with more severe disease manifestations. Finally, hematopoietic stem cell transplantation significantly reduces, but does not normalize, plasma C26:0-lysophosphatidylcholine levels in male ALD patients. Our findings are supported by the concordance of C26:0-lysophosphatidylcholine and total VLCFA analysis with the lipidomics results.

CONCLUSIONS

This study reveals the profound impact of ALD on the lipidome and provides potential biomarkers for predicting clinical outcomes in ALD patients.

Four-dimensional lipidomics profiling in X-linked adrenoleukodystrophy using trapped ion mobility mass spectrometry

Lipids play pivotal roles in an extensive range of metabolic and physiological processes. In recent years, the convergence of trapped ion mobility spectrometry and MS has enabled 4D-lipidomics, a highly promising technology for comprehensive lipid analysis. 4D-lipidomics assesses lipid annotations across four distinct dimensions-retention time, collisional cross section, m/z (mass-to-charge ratio), and MS/MS spectra-providing a heightened level of confidence in lipid annotation. These advantages prove particularly valuable when investigating complex disorders involving lipid metabolism, such as adrenoleukodystrophy (ALD). ALD is characterized by the accumulation of very-long-chain fatty acids (VLCFAs) due to pathogenic variants in the ABCD1 gene. A comprehensive 4D-lipidomics strategy of ALD fibroblasts demonstrated significant elevations of various lipids from multiple classes. This indicates that the changes observed in ALD are not confined to a single lipid class and likely impacts a broad spectrum of lipid-mediated physiological processes. Our findings highlight the incorporation of mainly saturated and monounsaturated VLCFA variants into a range of lipid classes, encompassing phosphatidylcholines, triacylglycerols, and cholesterol esters. These include ultra-long-chain fatty acids with a length of up to thirty carbon atoms. Lipid species containing C26:0 and C26:1 were the most frequently detected VLCFA lipids in our study. Furthermore, we report a panel of 121 new candidate biomarkers in fibroblasts, exhibiting significant differentiation between controls and individuals with ALD. In summary, this study demonstrates the capabilities of a 4D-lipid profiling workflow in unraveling novel insights into the intricate lipid modifications associated with metabolic disorders like ALD.

The pathology of X-linked adrenoleukodystrophy: tissue specific changes as a clue to pathophysiology

Although the pathology of X-linked adrenoleukodystrophy (ALD) is well described, it represents the end-stage of neurodegeneration. It is still unclear what cell types are initially involved and what their role is in the disease process. Revisiting the seminal post-mortem studies from the 1970s can generate new hypotheses on pathophysiology. This review describes (histo)pathological changes of the brain and spinal cord in ALD. It aims at integrating older works with current insights and at providing an overarching theory on the pathophysiology of ALD. The data point to an important role for axons and glia in the pathology of both the myelopathy and leukodystrophy of ALD. In-depth pathological analyses with new techniques could help further unravel the sequence of events behind the pathology of ALD.

Change in plasma α-tocopherol associations with attenuated pulmonary function decline and with CYP4F2 missense variation

BACKGROUND

Vitamin E (vitE) is hypothesized to attenuate age-related decline in pulmonary function.

OBJECTIVES

We investigated the association between change in plasma vitE (∆vitE) and pulmonary function decline [forced expiratory volume in the first second (FEV1)] and examined genetic and nongenetic factors associated with ∆vitE.

METHODS

We studied 1144 men randomly assigned to vitE in SELECT (Selenium and Vitamin E Cancer Prevention Trial). ∆vitE was the difference between baseline and year 3 vitE concentrations measured with GC-MS. FEV1 was measured longitudinally by spirometry. We genotyped 555 men (vitE-only arm) using the Illumina Expanded Multi-Ethnic Genotyping Array (MEGAex). We used mixed-effects linear regression modeling to examine the ∆vitE-FEV1 association.

RESULTS

Higher ∆vitE was associated with lower baseline α-tocopherol (α-TOH), higher baseline γ-tocopherol, higher baseline free cholesterol, European ancestry (as opposed to African) (all P < 0.05), and the minor allele of a missense variant in cytochrome P450 family 4 subfamily F member 2 (CYP4F2) (rs2108622-T; 2.4 µmol/L higher ∆vitE, SE: 0.8 µmol/L; P = 0.0032). Higher ∆vitE was associated with attenuated FEV1 decline, with stronger effects in adherent participants (≥80% of supplements consumed): a statistically significant ∆vitE × time interaction (P = 0.014) indicated that a 1-unit increase in ∆vitE was associated with a 2.2-mL/y attenuation in FEV1 decline (SE: 0.9 mL/y). The effect size for 1 SD higher ∆vitE (+4 µmol/mmol free-cholesterol-adjusted α-TOH) was roughly one-quarter of the effect of 1 y of aging, but in the opposite direction. The ∆vitE-FEV1 association was similar in never smokers (2.4-mL/y attenuated FEV1 decline, SE: 1.0 mL/y; P = 0.017, n = 364), and current smokers (2.8-mL/y, SE: 1.6 mL/y; P = 0.079, n = 214), but there was little to no effect in former smokers (-0.64-mL/y, SE: 0.9 mL/y; P = 0.45, n = 564).

CONCLUSIONS

Greater response to vitE supplementation was associated with attenuated FEV1 decline. The response to supplementation differed by rs2108622 such that individuals with the C allele, compared with the T allele, may need a higher dietary intake to reach the same plasma vitE concentration.

Genetic variation of pharmacogenomic VIP variants in the Chinese Li population: an updated research

Previous studies have shown that the frequency of very important pharmacogenomic (VIP) genes varies in different populations which leads to the diversities in drug efficacy, safety, and the risk associated with adverse drug reactions (ADRs). The purpose of this study was to identify the distribution differences of VIP variants between the Li population and the other 13 populations. Based on the Pharmacogenomics Knowledgebase database (PhamGKB), we successfully genotyped 52 VIP variants within 27 genes in 200 unrelated Li population. χ² test was used to evaluate the significant differences of genotype and allele frequencies between the Li and the other 13 populations from 1000 Genomes Project. Our study showed that the genotype frequencies of single nucleotide polymorphisms (SNPs) on KCNH2, ACE, CYP4F2, and CYP2E1 were considerably different between Li and the other 13 populations, especially in rs1805123 (KCNH2), rs4291 (ACE), rs3093105 (CYP4F2), and rs6413432 (CYP2E1) loci. Meanwhile, we found several VIP variants that might alter the drug metabolism of cisplatin-cyclophosphamide (CYP2E1), vitamin E (CYP4F2), asthma amlodipine, chlorthalidone, and lisinopril (ACE) through PharmGKB. We also identified other variants which were associated with adverse effects in isoniazid and rifampicin (CYP2E1; hepatotoxicity). The four loci rs1805123 (KCNH2), rs4291 (ACE), rs3093105 (CYP4F2), and rs6413432 (CYP2E1) provided a reliable basis for the prediction of the efficacy of certain drugs. The study complemented the existed pharmacogenomics information, which could provide theoretical basis for predicting the efficacy of certain drugs in the Li population.

Deciphering the modifiers for phenotypic variability of X-linked adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD), an inborn error of peroxisomal β-oxidation, is caused by defects in the ATP Binding Cassette Subfamily D Member 1 (ABCD1) gene. X-ALD patients may be asymptomatic or present with several clinical phenotypes varying from severe to mild, severe cerebral adrenoleuko-dystrophy to mild adrenomyeloneuropathy (AMN). Although most female heterozygotes present with AMN-like symptoms after 60 years of age, occasional cases of females with the cerebral form have been reported. Phenotypic variability has been described within the same kindreds and even among monozygotic twins. There is no association between the nature of ABCD1 mutation and the clinical phenotypes, and the molecular basis of phenotypic variability in X-ALD is yet to be resolved. Various genetic, epigenetic, and environmental influences are speculated to modify the disease onset and severity. In this review, we summarize the observations made in various studies investigating the potential modifying factors regulating the clinical manifestation of X-ALD, which could help understand the pathogenesis of the disease and develop suitable therapeutic strategies.

Multi-Omic Approach to Identify Phenotypic Modifiers Underlying Cerebral Demyelination in X-Linked Adrenoleukodystrophy

X-linked adrenoleukodystrophy (ALD) is a peroxisomal metabolic disorder with a highly complex clinical presentation. ALD is caused by mutations in the ABCD1 gene, and is characterized by the accumulation of very long-chain fatty acids in plasma and tissues. Disease-causing mutations are 'loss of function' mutations, with no prognostic value with respect to the clinical outcome of an individual. All male patients with ALD develop spinal cord disease and a peripheral neuropathy in adulthood, although age of onset is highly variable. However, the lifetime prevalence to develop progressive white matter lesions, termed cerebral ALD (CALD), is only about 60%. Early identification of transition to CALD is critical since it can be halted by allogeneic hematopoietic stem cell therapy only in an early stage. The primary goal of this study is to identify molecular markers which may be prognostic of cerebral demyelination from a simple blood sample, with the hope that blood-based assays can replace the current protocols for diagnosis. We collected six well-characterized brother pairs affected by ALD and discordant for the presence of CALD and performed multi-omic profiling of blood samples including genome, epigenome, transcriptome, metabolome/lipidome, and proteome profiling. In our analysis we identify discordant genomic alleles present across all families as well as differentially abundant molecular features across the omics technologies. The analysis was focused on univariate modeling to discriminate the two phenotypic groups, but was unable to identify statistically significant candidate molecular markers. Our study highlights the issues caused by a large amount of inter-individual variation, and supports the emerging hypothesis that cerebral demyelination is a complex mix of environmental factors and/or heterogeneous genomic alleles. We confirm previous observations about the role of immune response, specifically auto-immunity and the potential role of PFN1 protein overabundance in CALD in a subset of the families. We envision our methodology as well as dataset has utility to the field for reproducing previous or enabling future modifier investigations.

The correlation between CYP4F2 variants and chronic obstructive pulmonary disease risk in Hainan Han population

Background

Chronic obstructive pulmonary disease (COPD) is a complex pulmonary disease. Cytochrome P450 family 4 subfamily F member 2 (CYP4F2) belongs to cytochrome P450 superfamily of enzymes responsible for metabolism, its single nucleotide polymorphisms (SNPs) were reported to be involved in metabolism in the development of many diseases. The study aimed to assess the relation between CYP4F2 SNPs and COPD risk in the Hainan Han population.

Method

We genotyped five SNPs in CYP4F2 in 313 cases and 508 controls by Agena MassARRAY assay. The association between CYP4F2 SNPs and COPD risk were assessed by χ² test and genetic models. Besides, logistic regression analysis was introduced into the calculation for odds ratio (OR) and 95% confidence intervals (CIs).

Results

Allele model analysis indicated that rs3093203 A was significantly correlated with an increased risk of COPD. Also, rs3093193 G and rs3093110 G were associated with a reduced COPD risk. In the genetic models, we found that rs3093203 was related to an increased COPD risk, while rs3093193 and rs3093110 were related to a reduced risk of COPD. After gender stratification, rs3093203, rs3093193 and rs3093110 showed the association with COPD risk in males. With smoking stratification, rs3093144 was significantly associated with an increased risk of COPD in smokers. CYP4F2 SNPs were significantly associated with COPD risk.

Conclusions

Our findings illustrated potential associations between CYP4F2 polymorphisms and COPD risk. However, large-scale and well-designed studies are needed to determine conclusively the association between the CYP4F2 SNPs and COPD risk.

X-linked adrenoleukodystrophy: Pathology, pathophysiology, diagnostic testing, newborn screening and therapies

Adrenoleukodystrophy (ALD) is a rare X-linked disease caused by a mutation of the peroxisomal ABCD1 gene. This review summarizes our current understanding of the pathogenic cell- and tissue-specific roles of lipid species in the context of experimental therapeutic strategies and provides an overview of critical historical developments, therapeutic trials and the advent of newborn screening in the USA. In ALD, very long-chain fatty acid (VLCFA) chain length-dependent dysregulation of endoplasmic reticulum stress and mitochondrial radical generating systems inducing cell death pathways has been shown, providing the rationale for therapeutic moiety-specific VLCFA reduction and antioxidant strategies. The continuing increase in newborn screening programs and promising results from ongoing and recent therapeutic investigations provide hope for ALD.

X-linked Adrenoleukodystrophy: Pathology, Pathophysiology, Diagnostic Testing, Newborn Screening, and Therapies

Adrenoleukodystrophy (ALD) is a rare X-linked disease caused by a mutation of the peroxisomal ABCD1 gene. This review summarizes our current understanding of the pathogenic cell- and tissue-specific role of lipid species in the context of experimental therapeutic strategies and provides an overview of critical historical developments, therapeutic trials, and the advent of newborn screening in the United States. In ALD, very long chain fatty acid (VLCFA) chain-length-dependent dysregulation of endoplasmic reticulum stress and mitochondrial radical generating systems inducing cell death pathways has been shown, providing the rationale for therapeutic moiety-specific VLCFA reduction and antioxidant strategies. The continuing increase in newborn screening programs and promising results from ongoing and recent therapeutic investigations provide hope for ALD.

Effect of Lorenzo's Oil on Hepatic Gene Expression and the Serum Fatty Acid Level in abcd1-Deficient Mice

Lorenzo's oil is known to decrease the saturated very long chain fatty acid (VLCFA) level in the plasma and skin fibroblasts of X-linked adrenoleukodystrophy (ALD) patients. However, the involvement of Lorenzo's oil in in vivo fatty acid metabolism has not been well elucidated. To investigate the effect of Lorenzo's oil on fatty acid metabolism, we analyzed the hepatic gene expression together with the serum fatty acid level in Lorenzo's oil-treated wild-type and abcd1-deficient mice. The change in the serum fatty acid level in Lorenzo's oil-treated abcd1-defcient mice was quite similar to that in the plasma fatty acid level in ALD patients supplemented with Lorenzo's oil. In addition, we found that the hepatic gene expression of two peroxisomal enzymes, Dbp and Scp2, and three microsomal enzymes, Elovl1, 2, and 3, were significantly stimulated by Lorenzo's oil. Our findings indicate that Lorenzo's oil activates hepatic peroxisomal fatty acid β-oxidation at the transcriptional level. In contrast, the transcriptional stimulation of Elovl1, 2, and 3 by Lorenzo's oil does not cause changes in the serum fatty acid level. It seems likely that the inhibition of these elongation activities by Lorenzo's oil results in a decrease in saturated VLCFA. Thus, these results not only contribute to a clarification of the mechanism by which the saturated VLCFA level is reduced in the serum of ALD patients by Lorenzo's oil-treatment, but also suggest the development of a new therapeutic approach to peroxisomal β-oxidation enzyme deficiency, especially mild phenotype of DBP deficiency.