In individuals with Alzheimer’s disease, the brain exhibits elevated levels of IL-1β and oxygenated cholesterol molecules (oxysterols). This study aimed to investigate the effects of side-chain oxysterols on IL-1β expression using HMC3 microglial cells and ApoE-deficient mice. Treatment of HMC3 cells with 25-hydroxycholesterol (25OHChol) and 27-hydroxycholesterol (27OHChol) led to increased IL-1β expression at the transcript and protein levels. Additionally, these oxysterols upregulated the surface expression of MHC II, a marker of activated microglia. Immunohistochemistry performed on the mice showed increased microglial expression of IL-1β and MHC II when fed a high-cholesterol diet. However, cholesterol and 24s-hydroxycholesterol did not increase IL-1β transcript levels or MHC II expression. The extent of IL-1β increase induced by 25OHChol and 27OHChol was comparable to that caused by oligomeric β-amyloid, and the IL-1β expression induced by the oxysterols was not impaired by polymyxin B, which inhibited lipopolysaccharide-induced IL-1β expression. Both oxysterols enhanced the phosphorylation of Akt, ERK, and Src, and inhibition of these kinase pathways with pharmacological inhibitors suppressed the expression of IL-1β and MHC II. The pharmacological agents chlorpromazine and cyclosporin A also impaired the oxysterol-induced expression of IL-1β and upregulation of MHC II. Overall, these findings suggest that dysregulated cholesterol metabolism leading to elevated levels of side-chain oxysterols, such as 25OHChol and 27OHChol, can activate microglia to secrete IL-1β through a mechanism amenable to pharmacologic intervention. The activation of microglia and subsequent neuroinflammation elicited by the immune oxysterols can contribute to the development of neurodegenerative diseases.

Astaxanthin (3,3′-dihydroxy-β,β-carotene-4,4′-dione; AXT) is a xanthophyll β-carotenoid found in microalgae, seafood, fungi, complex plants, flamingos, and quail. It is well known that AXT plays a role as a drug with antioxidant and antitumor properties. Furthermore, several studies have reported that the reagent shows anti-inflammatory and neuroprotective effects. Recently, it was found that AXT acts as a peroxisome proliferator-activated receptor γ (PPARγ) modulator. To investigate the effect of AXT on MCF-7 cells (a human breast cancer cell line), the cells were treated with various concentrations of AXT. The treatment induced the decrease in cell number in a dose-dependent manner. Additionally, the Annexin V-positive cells were increased by the AXT treatment. These results indicated that apoptosis was induced in the tumor cells through the treatment of AXT. To elucidate the connection between apoptosis and p53, the levels of p53 and p21 proteins were assessed. Consequently, it was observed that the expression of p53 and p21 increased proportionally to the concentration of the AXT treatment. These findings suggest that the apoptosis of MCF-7 cells induced by AXT operates through a p53-dependent pathway, implying that AXT could potentially have a beneficial role in future breast cancer treatments. Thus, our results will provide a direction for future cancer challenges.

Microglia, essential immune cells in the brain, play crucial roles in neuroinflammation by performing various functions such as neurogenesis, synaptic pruning, and pathogen defense. These cells are activated by inflammatory factors like β-amyloid (Aβ) and oxysterols, leading to morphological and functional changes, including the secretion of inflammatory cytokines and the upregulation of MHC class II molecules. This study focused on identifying specific markers for microglial activation, with a particular emphasis on the roles of oxysterols in this process. We used the HMC3 human microglial cell line to investigate the induction of heat shock protein 60 (HSP60), a chaperonin protein by oxysterols, specifically in the presence of 25-hydroxycholesterol (25OHChol) and 27-hydroxycholesterol (27OHChol). Our findings obtained by the proteomics approach revealed that these oxysterols significantly increased HSP60 expression on microglial cells. This induction was further confirmed using Western blot analysis and immunofluorescence microscopy. Additionally, Aβ_1–42 also promoted HSP60 expression, indicating its role as a microglial activator. HSP60 involved in protein folding and immune modulation was identified as a potential marker for microglial activation. This study underscores the importance of HSP60 in the inflammatory response of microglia, suggesting its utility as a target for new therapeutic approaches in neuroinflammatory diseases such as Alzheimer’s disease (AD).