Lovastatin impairs cellular proliferation and enhances hyaluronic acid production in fibroblast-like synoviocytes.

INTRODUCTION: Statins have demonstrated chondroprotective effects by reducing inflammation and mitigating extracellular matrix degradation. However, statins are also reported to be cytotoxic to several types of cells. Early-onset osteoarthritis (OA) is characterized by synovial inflammation, which adversely affects hyaluronan (HA) production in fibroblast-like synoviocytes (FLSs). Nevertheless, the precise effects of statins on the synovium remain unclear. METHODS: This study investigated the impact of lovastatin on human FLSs, and HA secretion-related genes, signaling pathways, and production were evaluated. RESULTS: The findings revealed that high doses of lovastatin (20 or 40 µM) decreased FLS viability and increased cell death. FLS proliferation ceased when cultured in a medium containing 5 or 10 µM lovastatin. mRNA expression analysis demonstrated that lovastatin (5 and 10 µM) upregulated the gene level of hyaluronan synthase 1 (HAS1), HAS2, and proteoglycan 4 (PRG4), but not HAS3. While the expression of multidrug resistance-associated protein 5 transporter gene remained unaffected, both inward-rectifying potassium channel and acid-sensing ion channel 3 were upregulated. Western blot further confirmed that lovastatin increased the production of HAS1 and PRG4, and activated the PKC-α, ERK1/2, and p38-MAPK signaling pathways. Additionally, lovastatin elevated intracellular cAMP levels and HA production in FLSs. CONCLUSION: Lovastatin impairs cellular proliferation but enhances HA production in human FLSs.

Overexpressing glyoxalase 1 attenuates acute hyperglycemia-exacerbated neurological deficits of ischemic stroke in mice.

Stress-induced hyperglycemia (SIH) is associated with poor functional recovery and high mortality in patients with acute ischemic stroke (AIS). However, intensive controlling of blood glucose by using insulin was not beneficial in patients with AIS and acute hyperglycemia. This study investigated the therapeutic effects of the overexpression of glyoxalase I (GLO1), a detoxifying enzyme of glycotoxins, on acute hyperglycemia-aggravated ischemic brain injury.  In the present study, adeno-associated viral (AAV)-mediated GLO1 overexpression reduced infarct volume and edema level but did not improve neurofunctional recovery in the mice with middle cerebral artery occlusion (MCAO). AAV-GLO1 infection significantly enhanced neurofunctional recovery in the MCAO mice with acute hyperglycemia but not in the mice with normoglycemia. Methylglyoxal (MG)-modified proteins expression significantly increased in the ipsilateral cortex of the MCAO mice with acute hyperglycemia. AAV-GLO1 infection attenuated the induction of MG-modified proteins, ER stress formation, and caspase 3/7 activation in MG-treated Neuro-2A cells, and reductions in synaptic plasticity and microglial activation were mitigated in the injured cortex of the MCAO mice with acute hyperglycemia. Treatment with ketotifen, a potent GLO1 stimulator, after surgery, alleviated neurofunctional deficits and ischemic brain damage in the MCAO mice with acute hyperglycemia.  Altogether, our data substantiate that, in ischemic brain injury, GLO1 overexpression can alleviate pathologic alterations caused by acute hyperglycemia. Upregulation of GLO1 may be a therapeutic strategy for alleviating SIH-aggravated poor functional outcomes in patients with AIS.

Ability of Local Clearance of Senescent Cells in Ipsilateral Hemisphere to Mitigate Acute Ischemic Brain Injury in Mice.

Senolytic treatment has potential therapeutic efficacy for acute ischemic stroke (AIS). However, the systemic treatment of senolytics may produce off-target side effects and a toxic profile, which affect analysis of the role of acute senescence of neuronal cells in pathogenesis of AIS. We constructed a novel lenti-INK-ATTAC viral vector to introduce INK-ATTAC genes to the ipsilateral brain and locally eliminate senescent brain cells by administering AP20187 to activate caspase-8 apoptotic cascade. In this study, we have found that acute senescence is triggered by middle cerebral artery occlusion (MCAO) surgery, particularly in astrocytes and cerebral endothelial cells (CECs). The upregulation of p16INK4a and senescence-associated secretory phenotype (SASP) factors including matrix metalloproteinase-3, interleukin-1 alpha and -6 were observed in oxygen-glucose deprivation-treated astrocytes and CECs. The systemic administration of a senolytic, ABT-263, prevented the impairment of brain activity from hypoxic brain injury in mice, and significantly improved the neurological severity score, rotarod performance, locomotor activity, and weight loss. The treatment of ABT-263 reduced senescence of astrocytes and CECs in MCAO mice. Furthermore, the localized removal of senescent cells in the injured brain through the stereotaxical injection of lenti-INK-ATTAC viruses generates neuroprotective effects, protecting against acute ischemic brain injury in mice. The content of SASP factors and mRNA level of p16INK4a in the brain tissue of MCAO mice were significantly reduced by the infection of lenti-INK-ATTAC viruses. These results indicate that local clearance of senescent brain cells is a potential therapy on AIS, and demonstrate the correlation between neuronal senescence and pathogenesis of AIS.