Biomedical subjects

Brian D Brown

Publications and source records attributed to Brian D Brown.

9 recordsLinked to original sources

PubMed2026

A serpin-myeloid axis in pancreatic cancer heterogeneity and immune evasion.

Pancreatic ductal carcinoma (PDAC) is characterized by a highly immunosuppressive, extracellular matrix-rich microenvironment, yet tumours display marked heterogeneity1-4. This raises the question of whether immune resistance is a global tumour property or is organized within spatially restricted niches. Here, using Perturb-map spatial functional genomics, we determine how different genes shape the growth and cellular environments of PDAC clones across space and time. This analysis revealed early gene-driven remodelling of local immune neighbourhoods preceding late-stage spatial clonal dominance. We identify SERPINE1 (encoding plasminogen activator inhibitor 1 (PAI1)) and SERPINB2 (encoding PAI2) as dominant regulators of tumour microenvironment control and immune evasion. These serpins promote stabilization of fibrin-rich extracellular matrix niches that spatially retain and programme macrophages towards immunosuppressive states while excluding cytotoxic T cells. Loss of Serpine1 or Serpinb2, or pharmacological inhibition of PAI1 or CD18, improves tumour control in mice and synergizes with anti-PD-1. Multimodal spatial analysis of patient tumours revealed that immunosuppressive niches form around rare SERPINB2- and SERPINE1-expressing PDAC subpopulations, dominated by SPP1+/MARCO+ macrophages. These findings identify cancer-derived SERPINE1 and SERPINB2 as local spatial organizers of immune suppression, linking tumour-intrinsic heterogeneity to local microenvironmental control and immunotherapy resistance in PDAC.

Journal Article↗

PubMed2026

Emerging Principles in Spatial Functional Genomics.

Spatial transcriptomic and proteomic atlases have enabled mapping of gene programs within intact tissues, but these measurements remain largely descriptive and do not define the mechanisms controlling tissue biology. Pooled CRISPR screening provides scalable causal interrogation of gene function but remains largely confined to dissociated systems that lack spatial context. In vivo spatial functional genomics (SFG) bridges these approaches by integrating genetic perturbations with in situ transcriptomic and proteomic readouts to measure gene function within intact tissue ecosystems. By preserving spatial organization, SFG enables interpretation of perturbations through effects on cell-cell interactions, diffusible signals, multicellular niches, and tissue architecture. Here, we outline key design axes of SFG: perturbation strategy, barcoding strategy, and phenotypic readout. We discuss computational challenges, including spatial autocorrelation, neighborhood dependence, and context-aware null modeling, and highlight how SFG reveals non-cell-autonomous, architecture-dependent mechanisms of gene function, advancing toward predictive models of tissue organization and gene function.

Genomics↗

PubMed2026

Dendritic cells control tertiary lymphoid structure development and maintenance in cancer.

Tertiary lymphoid structures (TLSs) are associated with immunotherapy response, yet the mechanisms controlling their formation and maintenance remain unclear. Using spatial transcriptomics and multiplex imaging across human tumors, we found that CCR7+ mature dendritic cells (DCs) accumulate in TLSs. In a mouse non-small cell lung cancer model that forms mature TLSs, we show that early TLS development requires interferon-γ (IFN-γ)-driven type 1 conventional dendritic cell (cDC1) maturation, migration to tumor-draining lymph nodes (tdLNs), and T cell recruitment. As tumors progress, TLSs persist independently of tdLN T cell egress, coinciding with cDC1 accumulation within intratumoral CCL19 stromal hubs. There, cDC1-major histocompatibility complex class 1 (MHC-I) and -MHC-II concomitant antigen presentation, along with CD40 signaling, sustain TLS, T follicular helper (TFH) cell pool, germinal centers, and tumor-specific immunoglobulin G (IgG). These findings highlight local mature cDC1s as key TLS orchestrators and potential targets to enhance antitumor TLS function.

Animals↗

PubMed2026

mRNA vaccine immunity is enhanced by hepatocyte detargeting and not dependent on dendritic cell expression.

Proteins encoded by mRNA vaccines can be expressed by a diversity of transfected cell types but how cell-type-specific expression influences immunity is poorly understood. To investigate this, we incorporated synthetic microRNA target sites (miRT) into lipid nanoparticle (LNP)-delivered mRNA vaccines to silence mRNA expression specifically in professional antigen-presenting cells (pAPCs), hepatocytes or myocytes. We found that mRNA expression in pAPCs was dispensable for priming antigen-specific T cells, whereas mRNA expression in myocytes induced similar or stronger immune responses, including for SARS-CoV-2, suggesting that antigen cross-presentation or cross-dressing may be more impactful than direct mRNA expression in pAPCs. In contrast, mRNA expression in hepatocytes suppressed the antigen-specific T cell response, partly through PD1/PDL1. In mice bearing tumor-associated antigen (TAA)-expressing lymphoma cells, miRT-mediated hepatocyte-silenced TAA mRNA vaccine enhanced immune response and reduced tumor burden. Thus, non-pAPC expression shapes immunity to mRNA-encoded protein and inclusion of miRTs can boost or blunt mRNA-LNP immunogenicity.

Journal Article↗

PubMed2024

Accelerating diabetic wound healing by ROS-scavenging lipid nanoparticle-mRNA formulation.

Current treatment options for diabetic wounds face challenges due to low efficacy, as well as potential side effects and the necessity for repetitive treatments. To address these issues, we report a formulation utilizing trisulfide-derived lipid nanoparticle (TS LNP)-mRNA therapy to accelerate diabetic wound healing by repairing and reprogramming the microenvironment of the wounds. A library of reactive oxygen species (ROS)-responsive TS LNPs was designed and developed to encapsulate interleukin-4 (IL4) mRNA. TS2-IL4 LNP-mRNA effectively scavenges excess ROS at the wound site and induces the expression of IL4 in macrophages, promoting the polarization from the proinflammatory M1 to the anti-inflammatory M2 phenotype at the wound site. In a diabetic wound model of db/db mice, treatment with this formulation significantly accelerates wound healing by enhancing the formation of an intact epidermis, angiogenesis, and myofibroblasts. Overall, this TS LNP-mRNA platform not only provides a safe, effective, and convenient therapeutic strategy for diabetic wound healing but also holds great potential for clinical translation in both acute and chronic wound care.

Wound Healing↗

PubMed2007

In vivo administration of lentiviral vectors triggers a type I interferon response that restricts hepatocyte gene transfer and promotes vector clearance.

Liver gene transfer is a highly sought goal for the treatment of inherited and infectious diseases. Lentiviral vectors (LVs) have many desirable properties for hepatocyte-directed gene delivery, including the ability to integrate into nondividing cells. Unfortunately, upon systemic administration, LV transduces hepatocytes relatively inefficiently compared with nonparenchymal cells, and the duration of transgene expression is often limited by immune responses. Here, we investigated the role of innate antiviral responses in these events. We show that administration of LVs to mice triggers a rapid and transient IFNalphabeta response. This effect was dependent on functional vector particles, and in vitro challenge of antigen-presenting cells suggested that plasmacytoid dendritic cells initiated the response. Remarkably, when LVs were administered to animals that lack the capacity to respond to IFNalphabeta, there was a dramatic increase in hepatocyte transduction, and stable transgene expression was achieved. These findings indicate that, even in the setting of acute delivery of replication-defective vectors, IFNs effectively interfere with transduction in a cell-type-specific manner. Moreover, because disabling a single component of the innate/immune network was sufficient to establish persistent xenoantigen expression, our results raise the hope that the immunologic barriers to gene therapy are less insurmountable than expected.

Animals↗

PubMed2006

Endogenous microRNA regulation suppresses transgene expression in hematopoietic lineages and enables stable gene transfer.

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression by repressing translation of target cellular transcripts. Increasing evidence indicates that miRNAs have distinct expression profiles and play crucial roles in numerous cellular processes, although the extent of miRNA regulation is not well known. By challenging mice with lentiviral vectors encoding target sequences of endogenous miRNAs, we show the efficiency of miRNAs in sharply segregating gene expression among different tissues. Transgene expression from vectors incorporating target sequences for mir-142-3p was effectively suppressed in intravascular and extravascular hematopoietic lineages, whereas expression was maintained in nonhematopoietic cells. This expression profile, which could not be attained until now, enabled stable gene transfer in immunocompetent mice, thus overcoming a major hurdle to successful gene therapy. Our results provide novel in situ evidence of miRNA regulation and demonstrate a new paradigm in vector design with applications for genetic engineering and therapeutic gene transfer.

Animals↗

PubMed2003

Helper-dependent adenoviral vectors mediate therapeutic factor VIII expression for several months with minimal accompanying toxicity in a canine model of severe hemophilia A.

Two helper-dependent (HD) adenoviral vectors encoding a canine factor VIII B-domain-deleted transgene (cFVIII) were constructed and evaluated in 4 hemophilia A dogs. One vector was regulated by the cytomegalovirus (CMV) promoter (HD-CMV-cFVIII), while the other vector contained a tissue-restricted promoter comprised of the human FVIII proximal promoter with an upstream concatemer of 5 hepatocyte nuclear factor 1 binding sites (HD-HNF-cFVIII). We detected no toxicity at low dose (5 x 10(11) vp/kg), but at higher vector doses (> 1 x 10(12) vp/kg) transient hepatotoxicity and thrombocytopenia were observed. Low-level increases in FVIII activity were detected in all 3 HD-HNF-cFVIII-treated dogs, which corresponded with decreased whole blood clotting times. None of the animals receiving the HD-HNF-cFVIII vector developed FVIII inhibitors, and in 1 of the 3 animals, FVIII activity was sustained for over 6 months after treatment. One animal, which received the HD-CMV-cFVIII vector, achieved peak levels of FVIII above 19 000 mU/mL, but FVIII activity disappeared within 1 week, coincident with the development of a potent anti-canine FVIII antibody response. This study supports previous demonstrations of improved safety using HD gene transfer and suggests that these vectors can provide transient FVIII expression with minimal, acute toxicity in the absence of inhibitor formation.

Acute-Phase Reaction↗

PubMed2002

Dangerous liaisons: the role of "danger" signals in the immune response to gene therapy.

Recent studies in gene transfer suggest that the innate immune system plays a significant role in impeding gene therapy. In this review, we examine factors that might influence the recruitment and activation of the innate system in the context of gene therapy. We have adopted a novel model of immunology that contends that the immune system distinguishes not between self and nonself, but between what is dangerous and what is not dangerous. In taking this perspective, we provide an alternative and complementary insight into some of the failures and successes of current gene therapy protocols.

Animals↗