Jinhyun Ryu, Nal Ae Yoon, Hyemin Seong, Joo Yeon Jeong, Seokmin Kang, Nammi Park, Jungil Choi, Dong Hoon Lee, Gu Seob Roh, Hyun Joon Kim, Gyeong Jae Cho, Wan Sung Choi, Jae-Yong Park, Jeong Woo Park, and Sang Soo Kang. Mol. Cells 2015;38:991-7. https://doi.org/10.14348/molcells.2015.0197

We investigated the role of nuclear factor of activated T cells 5 (NFAT5) under hyperosmotic conditions in human lens epithelial cells (HLECs). Hyperosmotic stress decreased the viability of human lens epithelial B-3 cells and significantly increased NFAT5 expression. Hyperosmotic stress-induced cell death occurred to a greater extent in NFAT5-knockout (KO) cells than in NFAT5 wild-type (NFAT5 WT) cells. Bcl-2 and Bcl-xl expression was down-regulated in NFAT5 WT cells and NFAT5 KO cells under hyperosmotic stress. Pre-treatment with a necroptosis inhibitor (necrostatin-1) significantly blocked hyperosmotic stress-induced death of NFAT5 KO cells, but not of NFAT5 WT cells. The phosphorylation levels of receptor-interacting protein kinase 1 (RIP1) and RIP3, which indicate the occurrence of necroptosis, were up-regulated in NFAT5 KO cells, suggesting that death of these cells is predominantly related to the necroptosis pathway. This finding is the first to report that necroptosis occurs when lens epithelial cells are exposed to hyperosmolar conditions, and that NFAT5 is involved in this process.

Acute kidney injury (AKI) is an inflammatory sequence. It can lead to distant organ injury, including damage to the central nervous system (CNS), mediated by increased circulating cytokines and other inflammatory mediators. It can also lead to increased blood–brain barrier (BBB) permeability. However, the effect of AKI on the inflammatory response of the brain has not yet been investigated. Therefore, we observed the effect of AKI on BBB permeability, microglia and astrocyte activation, and neuronal toxicity in the brain. The striatum and ventral midbrain, known to control overall movement, secrete the neurotransmitter dopamine. The activation of microglia and astrocytes present in this area causes neuro-degenerative diseases, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). The activation of astrocytes and microglia in the hippocampus and cerebral cortex, which are responsible for important functions, including memory, learning, concentration, and language, can trigger nerve cell apoptosis. The activation of astrocytes and microglia at this site is also involved in the inflammatory response associated with the accumulation of beta-amyloid. In the situation of kidney ischemia reperfusion (IR)-induced AKI, activation of microglia and astrocytes were observed in the striatum, ventral midbrain, hippocampus, and cortex. However, neuronal cell death was not observed until 48 h.

Dry eye disease (DED) is caused by inflammation and damage to the corneal surface due to tear film instability and hyperosmolarity. Various eye drops are used to treat this condition. Each eye drop has different properties and mechanisms of action, so the appropriate drug should be used according to clinical phenotypes. This study aims to compare the therapeutic mechanisms of cyclosporine A (CsA) and diquafosol tetrasodium (DQS). An experimental in vivo/in vitro model of DED using hyperosmolarity showed decreased cell viability, inhibited wound healing, and corneal damage compared to controls. Treatment with cyclosporine or diquafosol restored cell viability and wound healing and reduced corneal damage by hyperosmolarity. The expression of the inflammation-related genes il-1β, il-1α, and il-6 was reduced by cyclosporine and diquafosol, and the expression of Tnf-α, c1q, and il-17a was reduced by cyclosporine. Increased apoptosis in the DED model was confirmed by increased Bax and decreased Bcl-2 and Bcl-xl expression, but treatment with cyclosporine or diquafosol resulted in decreased apoptosis. Diquafosol increased NGF expression and translocation into the extracellular space. DED has different damage patterns depending on the progression of the lesion. Thus, depending on the type of lesion, eye drops should be selected according to the therapeutic target, focusing on repairing cellular damage when cellular repair is needed or reducing inflammation when inflammation is high and cellular damage is severe.

Steroid-induced cataracts (SIC) are defined as cataracts associated with the administration of corticosteroids. Long-term glucocorticoid treatment for inflammatory diseases reportedly increases the risk of SIC, and steroids can induce cataracts by disrupting ocular growth factor balance or homeostasis. In this study, we verified the effect of chondroitin sulfate proteoglycan 5 (CSPG5) using dexamethasone (dexa)-treated human lens epithelial (HLE-B3) cells and the lens epithelium from the anterior capsule of SIC patients obtained during cataract surgery. CSPG5 expression increased in the lens epithelium of SIC patients. The downregulation of CSPG5 suppressed the dexa-induced epithelial–mesenchymal transition (EMT)-related protein expression and motility in HLE-B3 cells. The disruption of the transcription factors EZH2 and B-Myb downregulated CSPG5, dexa-induced fibronectin expression, and cell migration in HLE-B3 cells, reaffirming that CSPG5 expression regulates EMT in lens epithelial cells. Taken together, these results indicate that the steroid-induced effects on lens epithelial cells are mediated via alterations in CSPG5 expression. Therefore, our study emphasizes the potential of CSPG5 as a therapeutic target for the prevention and treatment of SIC.

Background/Objectives: Parkinson’s disease (PD) is a neuro-degenerative disease for which a radical cure is not available, only symptomatic control. Studies have shown that hypoxia may have disease-modifying effects on PD. Methods: Herein, we investigated whether short-term hypoxia activates astrocytes and whether it has a protective effect on pre-formed fibril (PFF)-treated primary cortical neurons. Results: Long-term hypoxia suppresses astrocyte activation and induces cell death, whereas short-term hypoxia activates astrocytes without affecting cellular apoptosis or viability. Short-term hypoxia restored the cellular apoptosis and viability of PFF-treated neurons and reduced toxic phospho-α-synuclein (p-α-syn) aggregation. Similarly, the short-term hypoxia-exposed astrocyte-conditioned medium rescued cellular apoptosis and the viability of PFF-treated neurons and p-α-syn expression. Quantitative polymerase chain reaction revealed that short-term hypoxia promotes protective A2 astrocytes and suppresses toxic A1 astrocytes. Conclusions: Our findings suggest that short-term hypoxia has a neuro-protective effect against PD by activating protective A2 astrocytes, which rescue PFF-induced neuronal cell death. This provides insights into the clinical implications of short-term hypoxia as a disease-modifying PD strategy.