近藤 泰之

Plasma concentration of high-density lipoprotein cholesterol (HDL) is among the most important risk factors for coronary artery disease and apolipoprotein A1 (APOA1) is an essential apolipoprotein that constitutes HDL. However, few comprehensive searches have been conducted to identify non-coding functional SNPs around the APOA1 gene. In this study, we report the identification of a functional SNP, rs12718466, which influences hepatocyte-specific APOA1 gene expression. Furthermore, we identified SOX7 as the transcription factor interacting with the rs12718466 SNP, using a novel screening method Transcription Factor Expression Library (TFEL) scan, which employs a comprehensive library of mouse transcription factors. SOX7 binding is allele-dependent, with stronger binding to the normal allele leading to increased APOA1 transcription. In vitro experiments in hepatocytes and in vivo experiments in mice confirmed that overexpressing SOX7 increased APOA1 expression, while knocking it down decreased both APOA1 gene expression and plasma HDL-C levels. Our research demonstrates that rs12718466 is a functional SNP that modulates APOA1 gene expression through its interaction with SOX7, thereby affecting plasma HDL-C concentrations.

Vasoactive intestinal peptide-secreting tumors (VIPomas) are extremely rare functional pancreatic neuroendocrine neoplasms (p-NENs) characterized by watery diarrhea, hypokalemia, and achlorhydria. Here, we report the case of a 51-year-old female patient with VIPoma that recurred after a long-term disease-free interval. This patient had been asymptomatic for approximately 15 years after the initial curative surgery for pancreatic VIPoma, with no metastasis. The patient underwent a second curative surgery for the locally recurrent VIPoma. Whole-exome sequencing of the resected tumor revealed a somatic mutation in MEN1, which is reportedly responsible not only for multiple endocrine neoplasia type 1 (MEN1) syndrome but also sporadic p-NENs. Symptoms were controlled with lanreotide before and after surgery. The patient is alive with no relapse following 14 months after surgery. This case demonstrates the importance of long-term observation of patients with VIPoma.

BACKGROUND: 25-hydroxycholesterol (25HC), produced by cholesterol 25-hydroxylase (CH25H) in macrophages, has been reported to inhibit the replication of viral pathogens such as severe acute respiratory syndrome coronavirus-2. Also, CH25H expression in macrophages is robustly induced by interferons (IFNs). OBJECTIVE: To better understand the serum level increase of 25HC in coronavirus disease 2019 (COVID-19) and how it relates to the clinical picture. METHODS: We measured the serum levels of 25HC and five other oxysterols in 17 hospitalized COVID-19 patients. RESULTS: On admission, 25HC and 27-hydroxycholesterol (27HC) serum levels were elevated; however, 7-ketocholesterol (7KC) levels were lower in patients with COVID-19 than in the healthy controls. There was no significant correlation between 25HC serum levels and disease severity markers, such as interferon-gamma (IFN-γ) and interleukin 6. Dexamethasone effectively suppressed cholesterol 25-hydroxylase (CH25H) mRNA expression in RAW 264.7 cells, a murine leukemia macrophage cell line, with or without lipopolysaccharide or IFNs; therefore, it might mitigate the increasing effects of COVID-19 on the serum levels of 25HC. CONCLUSIONS: Our results highlighted that 25HC could be used as a unique biomarker in severe COVID-19 and a potential therapeutic candidate for detecting the severity of COVID-19 and other infectious diseases.