Alzheimer's disease (AD) is a neurodegenerative disorder that causes memory loss and dementia and is characterized by a decline in cognitive functions. Brain infections, especially induced by herpes simplex virus type-1 (HSV-1), are suggested to play a key role in the pathogenesis of AD. Within the scope of this study, two different AD models (Tau model and amyloid beta [Aβ]) were created in the SH-SY5Y cell line, and HSV glycoprotein B (gB) was applied to the cell line and on the generated AD models. Study groups (n = 3) were designed as (1) control, (2) HSV-gB group, (3) retinoic acid (RA) and brain derived neurotrophic factor (BDNF) induced Alzheimer's model (AD), (4) RA and BDNF induced Alzheimer's model + HSV-gB (ADH), (5) Aβ 1-42 peptide-induced Alzheimer's model (Aβ), and (6) Aβ 1-42 peptide-inducedAlzheimer's model + HSV-gB (AβH). Levels of complement proteins and cytokines were determined comparatively. In addition, specific markers of AD (hyperphosphorylated Tau proteins, Aβ 1-40 peptide and amyloid precursor protein) were measured in all groups. HSV-gB administration was found to increase Aβ and hyperphosphorylated Tau levels, similar to AD models. In addition, our data confirmed that the immune system and chronic inflammation might have a crucial role in AD development and that HSV-1 infection might also be an underlying factor of AD.

Dihydrolipoic acid (DHLA) is a natural antioxidant known for its ability to counteract metal toxicity and oxidative stress. It has shown the potential to safeguard cells from harmful environmental substances. It may hold therapeutic benefits in treating neurodegenerative disorders by defending against oxidative damage and chronic inflammation. Thus, this study aimed to explore the potential neuroprotective effects of DHLA against aluminum (Al)‐induced toxicity using an Alzheimer's disease (AD) model in vitro. The study focused on two important pathways: GSK‐3β and the Wnt signaling pathways. The SH‐SY5Y cell line was differentiated to establish AD, and the study group were as follows: control, Al, DHLA, Al‐DHLA, AD, AD‐Al, AD‐DHLA, and AD‐Al‐DHLA. The impact of DHLA on parameters related to oxidative stress was assessed. The activity of the GSK‐3β pathway was measured by evaluating the levels of PPP1CA, PP2A, GSK‐3β, and Akt. The Wnt signaling pathway was assessed by measuring Wnt/β‐catenin in the different study groups. Exposure to DHLA significantly reduced oxidative stress by effectively decreasing the levels of reactive oxygen species, thereby protecting against protein oxidation and limiting the production of malonaldehyde. Moreover, the DHLA‐treated groups exhibited a remarkable increase in the total antioxidant capacity. Furthermore, the study observed an upregulation of the Wnt signaling pathway and a downregulation of the GSK‐3β pathway in the groups treated with DHLA. In summary, the neuroprotective effects of DHLA, primarily achieved by reducing oxidative stress and modulating critical imbalanced pathways associated with AD, indicate its potential as a promising addition to the treatment regimens of AD patients.

Dihydrolipoic acid (DHLA) is a natural antioxidant that is recognized as being useful in combating metal toxicity and oxidative stress. It can protect cells from environmental contaminants and may be beneficial in treating neurodegenerative diseases by protecting against oxidative damage and chronic inflammation. Therefore, this study aimed to investigate the possible neuroprotective effects of DHLA against aluminum-induced toxicity in an in vitro Alzheimer’s disease (AD) model. The study focused on the glycogen synthase kinase3 (GSK3) pathway, and the Wnt signaling. A differentiated SH-SY5Y cell line model of AD was developed, and the study groups were as follows: control, Al, DHLA, Al-DHLA, AD, AD-Al, AD-DHLA, and AD-Al-DHLA. The impact of DHLA on oxidative stress parameters was evaluated, and GSK3 pathway was evaluated by measuring GSK3-β, human serine/threonine-protein phosphatase PP1-alpha catalytic subunit (PPP1CA), protein phosphatase 2A (PP2A) levels, and human RAC-alpha serine/threonine-protein kinase (AKT1). The Wnt signaling pathway was evaluated by measuring canonical Wingless and Int-1/β-catenin (Wnt/β-catenin) on different study groups. Exposure to DHLA reduced oxidative stress by dramatically lowering reactive oxygen species levels, protecting against protein oxidation, and limiting malonaldehyde production. Additionally, the total antioxidant capacity of DHLA-treated groups increased drastically. Furthermore, upregulation of Wnt signaling and downregulation of GSK3 pathways were observed in the groups treated by DHLA. Overall, the neuroprotective effects of DHLA, especially by reducing oxidative stress and regulating key imbalanced pathways in AD disease, make it a good candidate to be added to AD patients' treatment regimens.

In this study, we aimed to evaluate possible toxic effects of thimerosal, aluminum and combination of thimerosal and aluminum in SH-SY5Y cells. Inhibitory concentrations were determined by MTT assay; reactive oxygen species (ROS) were determined by a fluorometric kit and antioxidant/oxidant parameters were measured by spectrophotometric kits. Nuclear factor erythroid 2-associated factor 2 (Nrf2), norepinephrine (NE), dopamine transporter (DAT) and dopamine beta β-hydroxylase (DBH) levels were measured by sandwich ELISA kits while 8-hydroxy deoxyguanosine (8-OHdG) and dopamine levels were determined by competitive ELISA kits. Thimerosal (1.15 μM) and aluminum (362 μM) were applied to cells at inhibitory concentrations 20 (IC20s) for 24 h. ROS increased significantly in cells aluminum- and aluminum+thimerosal-treated cells. Glutathione levels decreased in aluminum group while total antioxidant capacity and protein oxidation levels increased significantly in aluminum and aluminum+thimerosal groups. Lipid peroxidation increased significantly in groups treated with aluminum and aluminum+thimerosal. Nrf2 levels and DNA damage were significantly higher in all groups while dopamine levels significantly increased in cells treated with thimerosal and aluminum+thimerosal, DAT levels were found to be higher in all experimental groups compared to the control. These findings showed that both thimerosal and aluminum can change oxidant/antioxidant status, cause DNA damage, alter dopamine and DAT levels. Changes seen in cells treated with combined exposure to aluminum and thimerosal are more pronounced. Special care should be taken while vaccinating sensitive populations and safer alternatives for aluminum and thimerosal should used.

No abstract