Vaccinia virus infection and gene transduction in cultured neurons

Monkeypox virus infection of human astrocytes causes gasdermin B cleavage and pyroptosis

Monkeypox virus (MPXV) infections in humans cause neurological disorders while studies of MPXV-infected animals indicate that the virus penetrates the brain. Pyroptosis is an inflammatory type of regulated cell death, resulting from plasma membrane rupture (PMR) due to oligomerization of cleaved gasdermins to cause membrane pore formation. Herein, we investigated the human neural cell tropism of MPXV compared to another orthopoxvirus, vaccinia virus (VACV), as well as its effects on immune responses and cell death. Astrocytes were most permissive to MPXV (and VACV) infections, followed by microglia and oligodendrocytes, with minimal infection of neurons based on plaque assays. Aberrant morphological changes were evident in MPXV-infected astrocytes that were accompanied with viral protein (I3) immunolabelling and detection of over 125 MPXV-encoded proteins in cell lysates by mass spectrometry. MPXV- and VACV-infected astrocytes showed increased expression of immune gene transcripts (IL12, IRF3, IL1B, TNFA, CASP1, and GSDMB). However, MPXV infection of astrocytes specifically induced proteolytic cleavage of gasdermin B (GSDMB) (50 kDa), evident by the appearance of cleaved N-terminal-GSDMB (30 kDa) and C-terminal- GSDMB (18 kDa) fragments. GSDMB cleavage was associated with release of lactate dehydrogenase and increased cellular nucleic acid staining, indicative of PMR. Pre-treatment with dimethyl fumarate reduced cleavage of GSDMB and associated PMR in MPXV-infected astrocytes. Human astrocytes support productive MPXV infection, resulting in inflammatory gene induction with accompanying GSDMB-mediated pyroptosis. These findings clarify the recently recognized neuropathogenic effects of MPXV in humans while also offering potential therapeutic options.

Cocaine induced inflammatory response in human neuronal progenitor cells

We have employed a genomic approach in homogenous cell culture to investigate the fundamental transcriptional responses which occur in neurons over time as a consequence of a single 30-min exposure to cocaine. Data from 24 Affymetrix microarrays, representing eight treatment groups, were analyzed by GeneChip Operating Software and then further mined by hierarchical clustering, anova, and Ingenuity Pathway Analysis software to examine known molecular pathways impacted by the observed transcriptional changes. For each time point under investigation, the data sets of genes exhibiting altered expression in treated cells compared with control were interrogated with a specific focus on differential expression of genes involved in immunomodulation and inflammation. The existing literature on the effects of cocaine in a diverse array of experimental paradigms demonstrates a significant modulation of inflammation and immune mechanisms, but these have typically been studies of chronic exposure in immune-competent cells. Our data show a time-dependent up-regulation of genes associated with pro-inflammatory and immune responses, peaking at 24 h as confirmed by all methods of analysis, suggesting a specific neuronal immunomodulatory response to acute cocaine exposure.