Differential Susceptibility to Propofol and Ketamine in Primary Cultures of Young and Senesced Astrocytes

The adverse effects of general anesthesia on the long-term cognition of young children and senior adults have become of concern in recent years. Previously, mechanistic and pathogenic investigations focused on neurons, and little is known about the effect of commonly used intravenous anesthetics such as propofol and ketamine on astrocytes. Recently, astrocyte dysfunction has been implicated in a wide range of age-related brain diseases. In this study, we examined the survival and viability of both young and senescent astrocytes in culture after adding propofol and ketamine to the media at varying strengths. Oxidative stimulus was applied to commercially available fetal cell lines of human astrocytes in vitro to induce morphological changes in cellular senescence. Our results indicate that propofol reduces the survival of young astrocytes as compared to controls, as well as to ketamine. These effects were seen in comparisons of total cell count and at both high and low dose concentrations. High doses of propofol also significantly reduced cell viability compared to those exposed to baseline controls and ketamine. Senescent astrocytes, on the other hand, demonstrated cell count reductions as compared to baseline controls and ketamine when exposed to either DMSO or propofol. The data show differential susceptibility of young astrocytes to propofol than to ketamine. The observed cell count reduction may be related to the adverse effects of propofol on mitochondrial function and free radical production, as described in previous studies. We speculate that ketamine may have a more favorable safety profile in infants and young children

Changes in the Transcriptome of Human Astrocytes Accompanying Oxidative Stress-Induced Senescence

Aging is a major risk factor for many neurodegenerative disorders. A key feature of aging biology that may underlie these diseases is cellular senescence. Senescent cells accumulate in tissues with age, undergo widespread changes in gene expression, and typically demonstrate altered, pro-inflammatory profiles. Astrocyte senescence has been implicated in neurodegenerative disease, and to better understand senescence-associated changes in astrocytes, we investigated changes in their transcriptome using RNA sequencing. Senescence was induced in human fetal astrocytes by transient oxidative stress. Brain-expressed genes, including those involved in neuronal development and differentiation, were downregulated in senescent astrocytes. Remarkably, several genes indicative of astrocytic responses to injury were also downregulated, including glial fibrillary acidic protein and genes involved in the processing and presentation of antigens by major histocompatiblity complex class II proteins, while pro-inflammatory genes were upregulated. Overall, our findings suggest that senescence-related changes in the function of astrocytes may impact the pathogenesis of age-related brain disorders

Astrocyte Senescence and Metabolic Changes in Response to HIV Antiretroviral Therapy Drugs

With the advent of highly active antiretroviral therapy (HAART) survival rates among patients infected by HIV have increased. However, even though survival has increased HIV-associated neurocognitive disorders (HAND) still persist, suggesting that HAART-drugs may play a role in the neurocognitive impairment observed in HIV-infected patients. Given previous data demonstrating that astrocyte senescence plays a role in neurocognitive disorders such as Alzheimer’s disease (AD), we examined the role of HAART on markers of senescence in primary cultures of human astrocytes (HAs). Our results indicate HAART treatment induces cell cycle arrest, senescence-associated beta-galactosidase, and the cell cycle inhibitor p21. Highly active antiretroviral therapy treatment is also associated with the induction of reactive oxygen species and upregulation of mitochondrial oxygen consumption. These changes in mitochondria correlate with increased glycolysis in HAART drug treated astrocytes. Taken together these results indicate that HAART drugs induce the senescence program in HAs, which is associated with oxidative and metabolic changes that could play a role in the development of HAND

Differential Susceptibility to Propofol and Ketamine in Primary Cultures of Young and Senesced Astrocytes

The adverse effects of general anesthesia on the long-term cognition of young children and senior adults have become of concern in recent years. Previously, mechanistic and pathogenic investigations focused on neurons, and little is known about the effect of commonly used intravenous anesthetics such as propofol and ketamine on astrocytes. Recently, astrocyte dysfunction has been implicated in a wide range of age-related brain diseases. In this study, we examined the survival and viability of both young and senescent astrocytes in culture after adding propofol and ketamine to the media at varying strengths. Oxidative stimulus was applied to commercially available fetal cell lines of human astrocytes in vitro to induce morphological changes in cellular senescence. Our results indicate that propofol reduces the survival of young astrocytes as compared to controls, as well as to ketamine. These effects were seen in comparisons of total cell count and at both high and low dose concentrations. High doses of propofol also significantly reduced cell viability compared to those exposed to baseline controls and ketamine. Senescent astrocytes, on the other hand, demonstrated cell count reductions as compared to baseline controls and ketamine when exposed to either DMSO or propofol. The data show differential susceptibility of young astrocytes to propofol than to ketamine. The observed cell count reduction may be related to the adverse effects of propofol on mitochondrial function and free radical production, as described in previous studies. We speculate that ketamine may have a more favorable safety profile in infants and young children

Introducing metallocene into a triazole peptide conjugate reduces its off‐rate and enhances its affinity and antiviral potency for HIV‐1 gp120

In this work, we identified a high affinity and potency metallocene-containing triazole peptide conjugate that suppresses the interactions of HIV-1 envelope gp120 at both its CD4 and co-receptor binding sites. The ferrocene-peptide conjugate, HNG-156, was formed by an on-resin copper-catalysed [2 + 3] cycloaddition reaction. Surface plasmon resonance interaction analysis revealed that, compared to a previously reported phenyl-containing triazole conjugate HNG-105 (105), peptide 156 had a higher direct binding affinity for several subtypes of HIV-1 gp120 due mainly to the decreased dissociation rate of the conjugate-gp120 complex. The ferrocene triazole conjugate bound to gp120 of both clade A (92UG037-08) and clade B (YU-2 and SF162) virus subtypes with nanomolar K(D) in direct binding and inhibited the binding of gp120 to soluble CD4 and to antibodies that bind to HIV-1(YU-2) gp120 at both the CD4 binding site and CD4-induced binding sites. HNG-156 showed a close-to nanomolar IC(50) for inhibiting cell infection by HIV-1(BaL) whole virus. The dual receptor site antagonist activity and potency of HNG-156 make it a promising viral envelope inhibitor lead for developing anti-HIV-1 treatments