Is classical pseudoxanthoma elasticum a consequence of hepatic 'intoxication' due to ABCC6 substrate accumulation in the liver?

Cardiovascular Manifestations of Pseudoxanthoma Elasticum: Pathophysiology, Management, and Research

Pseudoxanthoma elasticum is a rare genetic disorder characterized by calcification of elastic fibers in the connective tissue. The abundance of elastic tissues at these sites: skin, eyes, and heart make them the most affected systems. It has multifactorial pathogenesis, meaning, it manifests due to both environmental and genetic factors, but ABCC6 gene mutation plays an important role. This gene is responsible for causing defective MRP6 protein which in return is required for cell transport in the connective tissue. The clinical features range from minor skin lesions to fatal cardiovascular complications. Thus, it is important to diagnose it early and give appropriate treatment. This article provides insight into the cardiovascular manifestations of pseudoxanthoma elasticum, its diagnosis and management plans.

Insights into the liver-eyes connections, from epidemiological, mechanical studies to clinical translation

Maintenance of internal homeostasis is a sophisticated process, during which almost all organs get involved. Liver plays a central role in metabolism and involves in endocrine, immunity, detoxification and storage, and therefore it communicates with distant organs through such mechanisms to regulate pathophysiological processes. Dysfunctional liver is often accompanied by pathological phenotypes of distant organs, including the eyes. Many reviews have focused on crosstalk between the liver and gut, the liver and brain, the liver and heart, the liver and kidney, but with no attention paid to the liver and eyes. In this review, we summarized intimate connections between the liver and the eyes from three aspects. Epidemiologically, we suggest liver-related, potential, protective and risk factors for typical eye disease as well as eye indicators connected with liver status. For molecular mechanism aspect, we elaborate their inter-organ crosstalk from metabolism (glucose, lipid, proteins, vitamin, and mineral), detoxification (ammonia and bilirubin), and immunity (complement and inflammation regulation) aspect. In clinical application part, we emphasize the latest advances in utilizing the liver-eye axis in disease diagnosis and therapy, involving artificial intelligence-deep learning-based novel diagnostic tools for detecting liver disease and adeno-associated viral vector-based gene therapy method for curing blinding eye disease. We aim to focus on and provide novel insights into liver and eyes communications and help resolve existed clinically significant issues.

Untargeted metabolomics analysis of the plasma metabolic signature of moderate-to-severe acne

BACKGROUND

Acne vulgaris is a chronic inflammatory disease of pilosebaceous units and sebaceous glands. This study aimed to find out metabolites and metabolite pathways abnormal in moderate-to-severe acne vulgaris patients.

METHODS

The plasma metabolites LC-MS/MS analysis was conducted on 30 moderate-to-severe acne patients and 32 healthy controls. Multivariate data analyses were applied to identify the distinguishing metabolites.

RESULTS

Totally, 63 significant differential metabolites and 40 metabolic pathways were significantly changed. The top 3 metabolites on the basis of their VIP scores obtained from the PLS-DA were 2-Oxoadipic acid, Myo-inositol and Citrate. In addition, four sphingolipid metabolites include sphinganine, sphingosine, O-Phosphoethanolamine, and sphingomyelin (d18:1/18:0) were identified. The most closely related metabolic pathways included ATP-binding cassette (ABC) transporters and sphingolipid signaling pathway in moderate-to-severe acne patients.

CONCLUSIONS

The observed difference in metabolic profiles between acne patients and healthy controls provides a new insight into the link between plasma metabolic changes and acne vulgaris.

Untargeted Metabolomics Analysis of ABCC6-Deficient Mice Discloses an Altered Metabolic Liver Profile

Loss-of-function mutations in the transmembrane ABCC6 transport protein cause pseudoxanthoma elasticum (PXE), an ectopic, metabolic mineralization disorder that affects the skin, eye, and vessels. ABCC6 is assumed to mediate efflux of one or several small molecule compounds from the liver cytosol to the circulation. Untargeted metabolomics using liquid chromatography-mass spectrometry was employed to inspect liver cytosolic extracts from mice with targeted disruption of the Abcc6 gene. Absence of the ABCC6 protein induced an altered profile of metabolites in the liver causing accumulation of compounds as more features were upregulated than downregulated in ABCC6-deficient mice. However, no differences of the identified metabolites in liver could be detected in plasma, whereas urine reflected some of the changes. Of note, N-acetylated amino acids and pantothenic acid (vitamin B5), which is involved in acetylation reactions, were accumulated in the liver. None of the identified metabolites seems to explain mineralization in extrahepatic tissues, but the present study now shows that abrogated ABCC6 function does cause alterations in the metabolic profile of the liver in accordance with PXE being a metabolic disease originating from liver disturbance. Further studies of these changes and the further identification of yet unknown metabolites may help to clarify the liver-related pathomechanism of PXE.