Novel SK channel positive modulators prevent ferroptosis and excitotoxicity in neuronal cells.

Small conductance calcium-activated potassium (SK) channel activity has been proposed to play a role in the pathology of several neurological diseases. Besides regulating plasma membrane excitability, SK channel activation provides neuroprotection against ferroptotic cell death by reducing mitochondrial Ca2+ uptake and reactive oxygen species (ROS). In this study, we employed a multifaceted approach, integrating structure-based and computational techniques, to strategically design and synthesize an innovative class of potent small-molecule SK2 channel modifiers through highly efficient multicomponent reactions (MCRs). The compounds' neuroprotective activity was compared with the well-studied SK positive modulator, CyPPA. Pharmacological SK channel activation by selected compounds confers neuroprotection against ferroptosis at low nanomolar ranges compared to CyPPA, that mediates protection at micromolar concentrations, as shown by an MTT assay, real-time cell impedance measurements and propidium iodide staining (PI). These novel compounds suppress increased mitochondrial ROS and Ca2+ level induced by ferroptosis inducer RSL3. Moreover, axonal degeneration was rescued by these novel SK channel activators in primary mouse neurons and they attenuated glutamate-induced neuronal excitability, as shown via microelectrode array. Meanwhile, functional afterhyperpolarization of the novel SK2 channel modulators was validated by electrophysiological measurements showing more current change induced by the novel modulators than the reference compound, CyPPA. These data support the notion that SK2 channel activation can represent a therapeutic target for brain diseases in which ferroptosis and excitotoxicity contribute to the pathology.

Mitochondrial transplantation rescues neuronal cells from ferroptosis.

Ferroptosis is a type of oxidative cell death that can occur in neurodegenerative diseases and involves damage to mitochondria. Previous studies demonstrated that preventing mitochondrial dysfunction can rescue cells from ferroptotic cell death. However, the complexity of mitochondrial dysfunction and the timing of therapeutic interventions make it difficult to develop an effective treatment strategy against ferroptosis in neurodegeneration conditions. In this study, we explored the use of mitochondrial transplantation as a novel therapeutic approach for preventing ferroptotic neuronal cell death. Our data showed that isolated exogenous mitochondria were incorporated into both healthy and ferroptotic immortalized hippocampal HT-22 cells and primary cortical neurons (PCN). The mitochondrial incorporation was accompanied by increased metabolic activity and cell survival through attenuating lipid peroxidation and mitochondrial superoxide production. Further, the function of mitochondrial complexes I, III and V activities contributed to the neuroprotective activity of exogenous mitochondria. Similarly, we have also showed the internalization of exogenous mitochondria in mouse PCN; these internalized mitochondria were found to effectively preserve the neuronal networks when challenged with ferroptotic stimuli. The administration of exogenous mitochondria into the axonal compartment of a two-compartment microfluidic device induced mitochondrial transportation to the cell body, which prevented fragmentation of the neuronal network in ferroptotic PCN. These findings suggest that mitochondria transplantation may be a promising therapeutic approach for protecting neuronal cells from ferroptotic cell death.

The TNFR1 antagonist Atrosimab reduces neuronal loss, glial activation and memory deficits in an acute mouse model of neurodegeneration.

Tumor necrosis factor alpha (TNF-α) and its key role in modulating immune responses has been widely recognized as a therapeutic target for inflammatory and neurodegenerative diseases. Even though inhibition of TNF-α is beneficial for the treatment of certain inflammatory diseases, total neutralization of TNF-α largely failed in the treatment of neurodegenerative diseases. TNF-α exerts distinct functions depending on interaction with its two TNF receptors, whereby TNF receptor 1 (TNFR1) is associated with neuroinflammation and apoptosis and TNF receptor 2 (TNFR2) with neuroprotection and immune regulation. Here, we investigated the effect of administering the TNFR1-specific antagonist Atrosimab, as strategy to block TNFR1 signaling while maintaining TNFR2 signaling unaltered, in an acute mouse model for neurodegeneration. In this model, a NMDA-induced lesion that mimics various hallmarks of neurodegenerative diseases, such as memory loss and cell death, was created in the nucleus basalis magnocellularis and Atrosimab or control protein was administered centrally. We showed that Atrosimab attenuated cognitive impairments and reduced neuroinflammation and neuronal cell death. Our results demonstrate that Atrosimab is effective in ameliorating disease symptoms in an acute neurodegenerative mouse model. Altogether, our study indicates that Atrosimab may be a promising candidate for the development of a therapeutic strategy for the treatment of neurodegenerative diseases.