Circulating adiponectin levels, expression of adiponectin receptors, and methylation of adiponectin gene promoter in relation to Alzheimer’s disease

Abstract

Background The role of adiponectin (ADIPOQ) in Alzheimer’s disease (AD) has been documented, however, demonstrating controversial results. In this study, we investigated blood serum ADIPOQ levels, methylation of the adiponectin gene promoter, and adiponectin receptors (AdipoR1 and AdipoR2) expression in blood samples isolated from AD patients and healthy controls. Methods We performed a case–control study including 248 subjects (98 AD patients and 150 healthy controls); ADIPOQ serum levels, AdipoR1, and AdipoR2 levels in PBMC were measured by ELISA Kits, and ADIPOQ gene methylation was analyzed using methyl-specific PCR. Results Serum adiponectin levels were threefold higher in the AD group compared to the controls. We have also found a positive correlation between adiponectin and MMSE scores and high-density lipoprotein cholesterol (HDL-C) in AD patients. A significant difference in the proportion of methylation of the CpG sites at − 74 nt of the ADIPOQ gene promoter was detected in AD cases, and the levels of adiponectin in blood serum were significantly higher in methylated samples in the AD group compared to controls. The amount of AdipoR1 was significantly higher among AD subjects, while the expression of AdipoR2 did not vary between AD patients and controls. Conclusion These findings may contribute to a deeper understanding of the etiological factors leading to the development of dementia and may serve as a basis for the development of predictive biomarkers of AD.

Assessing adipokines as potential biomarkers of dementia, Alzheimer's disease, and mild cognitive impairment: A systematic review and meta‐analysis

“…We included 24 studies published between 2009 and 2023. All of them presented results on blood (serum or plasma) adiponectin 45,47–50,52,53,59–61,65,67–79 . Additionally, two of them included CSF measurements of adiponectin.…”

“…All of them presented results on blood (serum or plasma) adiponectin. 45,[47][48][49][50]52,53,[59][60][61]65,[67][68][69][70][71][72][73][74][75][76][77][78][79] Additionally, two of them included CSF measurements of adiponectin. They included 6757 participants, and 3778 of them were women.…”

Questions Regarding Variants in ADIPOQ in Maternal Circulating Adipokine Profile in Gestational Diabetes Mellitus [Letter]

“…Moreover, the expression of adiponectin receptors and methylation of the adiponectin gene promoter have been reported to be associated in the development of dementia in patients diagnosed with Alzheimer’s disease. 4 However, the expression of adiponectin receptors in gestational diabetes mellitus patients could not be detected, while a study on methylation has been reported previously. 5 An additional thoughtful response to this interesting study is that the detection of polymorphisms of the ADIPOQ gene in the study model of Macaca fascicularis was suggested to be performed in future research, such as that performed in a previous study.…”

Regulation and Role of Adiponectin Secretion in Rat Ovarian Granulosa Cells

“…This growing body of evidence highlights the potential importance of locally produced adiponectin in autocrine or paracrine actions. In mammalian ovaries, adiponectin and its receptors (AdipoR1 and AdipoR2) are found in different ovarian cell types, follicular fluid, and accessory gonadal organs across species [9][10][11][12]. However, the regulatory mechanism of local adiponectin secretion in the ovary remains unclear.…”