Biology subjects

Blackman, A.

Publications and source records attributed to Blackman, A..

6 recordsLinked to original sources

bioRxiv2026

MicroRNA-21 restrains myD88-dependent protective inflammation worsening Staphylococcus aureus skin infection

Staphylococcus aureus skin infections are driven by tissue-resident and recruited immune cells. A proper immune response requires a tightly regulated balance between inflammatory responses and the prevention of tissue damage. MicroRNAs are key post-transcriptional regulators of immune responses and influence both pro- and anti-inflammatory pathways. We show that S. aureus skin infection elevates miR-21 levels in the skin, and applying a topical miR-21 antagomir improves bacterial clearance and resolution of skin infection. In MRSA-infected mice lacking miR-21 in myeloid cells (miR21{Delta}myel), lesions are smaller, bacterial load decreases, macrophage infiltration is reduced, and collagen around the abscess increases. MiR-21 helps shape the inflammatory environment by modulating mediators such as IL-1{beta}, TNF, IL-33, and IL-10. Additionally, miR-21 deficiency increases MyD88 expression in infected skin, and blocking MyD88 actions abolishes the protective effects observed in miR21{Delta}myel mice. Overall, the miR-21/MyD88 pathway is a key regulator of the resolution of inflammation and antibacterial immunity during S. aureus skin infections, highlighting miR-21 inhibition as a promising therapy for antibiotic-resistant S. aureus infections.

immunology↗

bioRxiv2026

Establishment of a murine resident dermal macrophage cell line.

Resident dermal macrophages (DMs) play essential roles in maintaining skin homeostasis and initiating inflammatory responses during tissue injury and against infectious agents. However, studies of their cellular mechanisms have been limited by their low abundance in steady-state skin and by technical challenges in isolating resident DMs. Here, we describe the generation and characterization of a novel DM cell line, termed SB89. F4/80+ skin-resident DMs were sorted and immortalized using J2 retroviral transduction. SB89 cells display a stable, homogeneous macrophage phenotype and distinct surface markers compared with Langerhans cells and alveolar macrophages. Functionally, SB89 cells efficiently phagocytose methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, zymosan particles, and apoptotic cells, and effectively kill MRSA. Importantly, SB89 cells respond to LPS, as evidenced by production of IL-6, TNF, and IL-10, and by MRSA-induced production of inflammatory cytokines, chemokines, and eicosanoids. RNA-seq and gene ontology analyses revealed that SB89 cells elicit stronger responses in innate immunity, cell signaling, and epigenetic regulation than immortalized bone marrow-derived macrophages. SB89 cells are genetically tractable, amenable to gene silencing via RNAi and gene introduction via plasmid transfection. Overall, SB89 cells provide a renewable, dermis-imprinted macrophage model that preserves key functional and transcriptional features of resident DMs while reducing reliance on primary cells and animal models. This cell line represents a powerful platform for mechanistic, genetic, and translational studies in skin immunobiology.

immunology↗

bioRxiv2026

Hyperglycemia promotes maladaptive Dectin-1 signaling and impairs skin antifungal host defense.

People with chronic hyperglycemia are more susceptible to fungal skin infections, but the mechanisms underlying their worse clinical outcomes remain unclear. Using both in vivo and in vitro models, we explored how hyperglycemia influences skin antifungal defenses and how GLP1 agonists might restore host defense in diabetic conditions. Hyperglycemic mice showed increased susceptibility to Candida albicans skin infections, with larger lesions and higher fungal loads at all time points tested. Histology revealed larger abscesses, more extensive myeloid cell infiltration, and poorer control of fungal invasion, associated with increased chemoattractant production on day 1 post-infection. Despite heightened inflammatory responses, macrophages and keratinocytes exposed to high glucose exhibit markedly impaired fungal ingestion. RNAseq analysis of C. albicans-infected dermal macrophages cultured in high glucose showed enrichment of genes related to antimicrobial effectors and the C-type lectin receptor pathway, including Clec7a (Dectin-1), while suppressing downstream signaling pathways required for effective phagocytosis. Pharmacologic blockade or genetic deletion of Dectin-1 restored fungal uptake under high-glucose conditions and improved host defense in vivo. Mechanistically, Dectin-1 signaling in hyperglycemia promoted increased prostaglandin E2 (PGE2) production via induction of microsomal Prostaglandin E Synthase-1 (mPGES-1), and inhibition of PGE2 synthesis rescued deficient phagocytic function. Finally, treatment with the glucagon-like peptide-1 (GLP-1) receptor agonist liraglutide reduced lesion size, fungal burden, inflammation, and tissue damage in diabetic mice, linking metabolic control to restoration of innate immune function. These findings identify maladaptive innate immune sensing as a key mechanism underlying susceptibility to fungal infection in diabetes and reveal how metabolic stress converts antifungal recognition pathways into drivers of inflammatory dysfunction.

immunology↗

bioRxiv2024

MYC is sufficient to generate mid-life high-grade serous ovarian and uterine serous carcinomas in a p53-R270H mouse model

Genetically engineered mouse models (GEMM) have fundamentally changed how ovarian cancer etiology, early detection, and treatment is understood. However, previous GEMMs of high-grade serous ovarian cancer (HGSOC) have had to utilize genetics rarely or never found in human HGSOC to yield ovarian cancer within the lifespan of a mouse. MYC, an oncogene, is amongst the most amplified genes in HGSOC, but it has not previously been utilized to drive HGSOC GEMMs. We coupled Myc and dominant negative mutant p53-R270H with a fallopian tube epithelium-specific promoter Ovgp1 to generate a new GEMM of HGSOC. Female mice developed lethal cancer at an average of 15.1 months. Histopathological examination of mice revealed HGSOC characteristics including nuclear p53 and nuclear MYC in clusters of cells within the fallopian tube epithelium and ovarian surface epithelium. Unexpectedly, nuclear p53 and MYC clustered cell expression was also identified in the uterine luminal epithelium, possibly from intraepithelial metastasis from the fallopian tube epithelium (FTE). Extracted tumor cells exhibited strong loss of heterozygosity at the p53 locus, leaving the mutant allele. Copy number alterations in these cancer cells were prevalent, disrupting a large fraction of genes. Transcriptome profiles most closely matched human HGSOC and serous endometrial cancer. Taken together, these results demonstrate the Myc and Trp53-R270H transgene was able to recapitulate many phenotypic hallmarks of HGSOC through the utilization of strictly human-mimetic genetic hallmarks of HGSOC. This new mouse model enables further exploration of ovarian cancer pathogenesis, particularly in the 50% of HGSOC which lack homology directed repair mutations. Histological and transcriptomic findings are consistent with the hypothesis that uterine serous cancer may originate from the fallopian tube epithelium.

cancer biology↗

bioRxiv2022

Prostaglandin E2 production is required for phagocyte CXCR2-mediated skin host defense in obese hyperglycemic mice.

Poorly controlled glucose observed in obese individuals with diabetes is associated with a significantly increased risk of infection, particularly in the skin and soft tissues. Staphylococcus aureus is a significant cause of skin and soft tissue infections (SSTIs) in obese and hyperglycemic individuals with growing antibiotic resistance making these infections difficult to treat. However, the events that drive dysregulated skin host defense during hyperglycemia remain to be fully elucidated. Here we examined how the prostaglandin E2 (PGE2) threshold impacts tissue injury and host defense during methicillin-resistant S. aureus (MRSA) skin infection in obese and hyperglycemic mice. Our data show that obesity and hyperglycemia are accompanied by impaired expression of prostaglandin E synthase 1 and PGE2 production in infected skin. Restoration of PGE2 levels with the PGE analog misoprostol improved infection outcomes in obese and hyperglycemic mice in a manner dependent on E prostanoid 3-mediated cAMP inhibition. Topical misoprostol restored the levels of CXC chemokines and CXCR2+ monocyte and neutrophil recruitment. Here, we are unveiling a defective signaling program that culminates in inadequate CXCR2 phagocyte migration to the infected skin of obese and hyperglycemic mice. Furthermore, these data also lead to a novel drug repurposing opportunity to treat antibiotic-resistant pathogens in hyperglycemic conditions.

immunology↗

bioRxiv2020

Leukotriene B4 licenses inflammasome activation to enhance skin host defense

The initial production of inflammatory mediators dictates host defense as well as tissue injury. Inflammasome activation is a constituent of the inflammatory response by recognizing pathogen and host-derived products and eliciting the production of IL-1{beta}, IL-18 as well as inducing a type of inflammatory cell death termed "pyroptosis". Leukotriene B4 (LTB4) is a lipid mediator produced quickly (seconds to minutes) by phagocytes and induces chemotaxis, enhances cytokine/chemokine production, and enhances antimicrobial effector functions. Whether LTB4 directly activates the inflammasome is not well understood. Our data show that endogenously produced LTB4 is required for the expression of pro-IL-1{beta} in vivo and in vitro and enhances inflammasome assembly. Furthermore, LTB4-mediated Brutons tyrosine kinase (BTK) activation is required for inflammasome assembly in vivo as well for IL-1{beta}-enhanced skin host defense. Together, these data unveil a new role for LTB4 in enhancing the expression and assembly of inflammasome components and suggest that while blocking LTB4 actions could be a promising therapeutic strategy to prevent inflammasome-mediated diseases, exogenous LTB4 can be used as an adjuvant to boost inflammasome-dependent host defense.

immunology↗