Biology subjects

Orzalli, M. H.

Publications and source records attributed to Orzalli, M. H..

5 recordsLinked to original sources

bioRxiv2026

IFN-κ directs antiviral immunity in human skin

Inducible expression of type I IFNs is a well-established host innate defense mechanism to limit virus infection. Yet, many viruses have evolved strategies to suppress the induction of these cytokines to enhance replication, spread, and transmission between hosts. Whether additional antiviral mechanisms protect against infection when inducible responses are compromised is not well understood. Here, we demonstrate that human keratinocytes preemptively protect the skin against virus infection through constitutive production of IFN-kappa (IFN-{kappa}), a poorly studied type I IFN family member. We find that constitutive IFNK expression protects keratinocytes against skin tropic RNA and DNA viruses, including vesicular stomatitis virus (VSV) and herpes simplex virus-1 (HSV-1). Using a human skin organoid model, we further demonstrate that keratinocyte-derived IFN-{kappa} establishes an antiviral state in dermal fibroblasts. Genetic and chemical analysis of the type I IFN receptor (IFNAR) signaling pathway in monocultured keratinocytes and skin organoids revealed that distinct pathways control VSV and HSV-1 replication. While canonical JAK-STAT signaling provided protection against VSV, HSV-1 infection was controlled through a JAK-STAT-independent mechanism. Using transcriptomic analysis, we further identified an IFN-{kappa}-dependent gene signature in keratinocytes that is not similarly driven by other type I IFNs. Together, this work establishes constitutive IFN-{kappa} production by keratinocytes as a broadly antiviral tissue autonomous defense mechanism.

immunology↗

bioRxiv2025

Gram-positive bacterial cell wall components inhibit herpes simplex virus infection.

The role of the mucosal microbiome in viral infections remains unclear. Genital herpes, caused by herpes simplex virus 1 and 2 (HSV-1 and HSV-2), is among the most prevalent sexually transmitted infections worldwide. Despite evidence linking vaginal Lactobacillus to protection against sexually transmitted viruses, the specific microbial components and mechanisms that mediate this defense are not well understood. Here, we show that multiple cell wall components from diverse gram-positive bacteria, including lactobacilli, inhibit HSV-1 and HSV-2 infection in cells and in a mouse model of genital herpes infection. Peptidoglycan (PG) and lipoteichoic acid (LTA), both major components of the gram-positive bacterial cell wall, significantly reduced HSV infectivity in vitro and improved survival and disease outcomes in mice. We further showed that Lactobacillus crispatus surface layer proteins SlpA and SlpB bind HSV-1 and inhibit infection. Antiviral effects of cell wall components were dose-dependent, relied on intact PG structure, and, in the case of PG and LTA, were independent of TLR2-mediated host signaling. Collectively, our findings identify a species-independent antiviral function for gram-positive bacterial cell wall components against HSV and suggest that the composition of the mucosal microbiome may play an underappreciated role in suppressing mucosal herpes infection in humans.

microbiology↗

bioRxiv2025

Lineage memory shapes viral resistance barriers in human skin

Individual cells within a given population exhibit striking variability in viral susceptibility, but it remains unknown whether this heterogeneity reflects memories encoded into the cellular lineage or true probabilistic variability. We used multi-color lineage tracing in a human primary organotypic skin model to reveal that viral resistance is encoded within specific cellular lineages. These lineages create distinct boundaries that block viral spread. Our lineage analyses in vitro confirmed that viral susceptibility exhibits strong heritability across cell generations, with siblings and cousins displaying remarkably similar infection outcomes. ATAC and proteomics profiling of resistant and susceptible clones revealed distinct epigenomic and proteomic states, with the transcription factor AP-1 emerging as a potential central regulator of lineage-encoded viral resistance. Inducing AP-1 activity with PMA rendered cells resistant to viral infection, suggesting a causative role in mediating resistance memory. Our findings demonstrate that antiviral resistance in human skin cells is encoded within cellular lineages and preserved through cell divisions, revealing how cell memory may shape infection dynamics and viral containment in tissues.

bioengineering↗

bioRxiv2024

Development of a high-throughput, quantitative platform using human cerebral organoids to study virus-induced neuroinflammation in Alzheimer's disease

Neuroinflammation is a central process in the pathogenesis of several neurodegenerative diseases such as Alzheimers disease (AD), and there are active efforts to target pathways involved in neuroinflammation for molecular biomarker discovery and therapeutic development in neurodegenerative diseases. It was also proposed that there may be an infectious etiology in AD that is associated with viruses such as herpes simplex virus (HSV-1) and influenza A virus (IAV), leading to neuroinflammation-induced AD pathogenesis or disease progression. We sought to develop high-throughput, quantitative molecular biomarker assays using dissociated cells from human cerebral organoids (dcOrgs), that can used for screening compounds to reverse AD-associated neuroinflammation. We found that HSV-1 infection, but not IAV infection, in dcOrgs led to increased intracellular A{beta}42 and phosphorylated Tau-Thr212 (pTau-212) expression, lower ratios of secreted A{beta}42/40, as well as neuronal loss, and increased proportions of astrocytes and microglia, which are hallmarks of AD. Among the glia cell-type markers, Iba1 (microglia) and GFAP (astrocyte) expression were most strongly correlated with HSV-1 expression, which further supported that these biomarkers are perturbed by glia-mediated neuroinflammation. By performing large-scale RNA sequencing, we observed that differentially expressed transcripts in HSV-1 infected dcOrgs were specifically enriched for AD-associated GWAS genes, but not for genes associated with other common neurodegenerative, neuropsychiatric or autoimmune diseases. Immediate treatment of HSV-1 infected dcOrgs with anti-herpetic drug acyclovir (ACV) rescued most of the cellular and transcriptomic biomarkers in a dosage-dependent manner, indicating that it is possible to use our high-throughput platform to identify compounds or target genes that can reverse these neuroinflammation-induced biomarkers associated with AD.

genomics↗

bioRxiv2022

Methotrexate inhibition of muropeptide transporter SLC46A2 controls psoriatic skin inflammation

Cytosolic innate immune sensing is critical for protecting barrier tissues. NOD1 and NOD2 are cytosolic sensors of small peptidoglycan fragments (muropeptides) derived from the bacterial cell wall. These muropeptides enter cells, especially epithelial cells, through unclear mechanisms. We previously implicated SLC46 transporters in muropeptide transport in Drosophila immunity. Here we focus on Slc46a2, which is highly expressed in mammalian epidermal keratinocytes, and show that it is critical for delivery of DAP-muropeptides and activation of NOD1 in keratinocytes, while the related transporter Slc46a3 is critical for responding to MDP, the NOD2 ligand. In a mouse model, Slc46a2 and Nod1 deficiency strongly suppressed psoriatic inflammation, while methotrexate, a commonly used psoriasis therapeutic, inhibited Slc46a2-dependent transport of DAP-muropeptides. Collectively these studies define SLC46A2 as a transporter of NOD1 activating muropeptides, with critical roles in the skin barrier, and identify this transporter as an important target for anti-inflammatory intervention.

immunology↗