Human iPSC-derived glia models for the study of neuroinflammation.

Neuroinflammation is a complex biological process that plays a significant role in various brain disorders. Microglia and astrocytes are the key cell types involved in inflammatory responses in the central nervous system. Neuroinflammation results in increased levels of secreted inflammatory factors, such as cytokines, chemokines, and reactive oxygen species. To model neuroinflammation in vitro, various human induced pluripotent stem cell (iPSC)-based models have been utilized, including monocultures, transfer of conditioned media between cell types, co-culturing multiple cell types, neural organoids, and xenotransplantation of cells into the mouse brain. To induce neuroinflammatory responses in vitro, several stimuli have been established that can induce responses in either microglia, astrocytes, or both. Here, we describe and critically evaluate the different types of iPSC models that can be used to study neuroinflammation and highlight how neuroinflammation has been induced and measured in these cultures.

Dysregulation of TDP-43 intracellular localization and early onset ALS are associated with a TARDBP S375G variant.

We investigated the Central Nervous System (CNS) and skeletal muscle tissue from A woman was clinically diagnosed with amyotrophic lateral sclerosis (ALS) at the age of 22. Neuropathologic evaluation showed upper and lower motor neuron loss, corticospinal tract degeneration and skeletal muscle denervation. Analysis of the patient's Deoxyribonucleic acid (DNA) revealed a AGT>GGT change resulting in an S375G substitution in the C-terminal region of TDP-43. This variant was previously reported as being benign. Considering the early onset and severity of the disease in this patient, we tested the effects of this genetic variant on TDP-43 localization, pre-mRNA splicing activity and toxicity, in parallel with the effects on known neighboring disease-associated mutations. In cell lines, expressed in culture, S375G TDP-43 appeared to be more significantly localized in the nucleus and to exert higher toxicity than wild-type TDP-43. Strikingly, a phosphomimic mutant at the same residue (S375E) showed a strong tendency to accumulate in the cytoplasm, especially under stress conditions, and molecular dynamics simulations suggest that phosphorylation of this residue can disrupt TDP-43 intermolecular interactions. The results of the current study highlight the importance of phosphorylation and regulation of TDP-43 nuclear-cytoplasmic shuttling/redistribution, in relation to the pathogenetic mechanisms involved in different forms of ALS.