Biology subjects

Maloney, D. J.

Publications and source records attributed to Maloney, D. J..

5 recordsLinked to original sources

bioRxiv2025

12-Lipoxygenase (12-LOX) Plays a Key Role in Hyperinflammatory Response Caused by SARS-CoV-2

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has led to significant global morbidity and mortality. The severe disease outcomes are often linked to a hyperinflammatory response known as a "cytokine storm." The underlying mechanisms responsible for this exaggerated immune response remain incompletely understood. This study aimed to investigate the molecular pathways contributing to the severe inflammatory damage and mortality associated with COVID-19. SARS-CoV-2 hijacks host lipid metabolism, particularly the phospholipase A2 (PLA2) pathway, which leads to the production of the bioactive molecules, including the 12-Lipoxygenase (12-LOX)-derived lipid mediators in platelets, as well as in lung and vascular cells. We hypothesized that 12-LOX drives the hyperinflammatory response and disease severity, and that its inhibition could reduce inflammation and improve outcomes. Analysis of autopsy lung samples from COVID-19 decedents and SARS-CoV-2-infected K18-hACE2 transgenic mice revealed increased 12-LOX expression. We evaluated VLX-1005, a selective small-molecule 12-LOX inhibitor, in infected mice. Treatment initiated 48 hours post-infection significantly improved survival, reduced body weight loss, and decreased lung inflammation compared to controls. Notably, male mice showed higher survival rates than females. VLX-1005 treatment also suppressed key chemokines and cytokines associated with the cytokine storm, and reduced lung damage. These findings identify 12-LOX as a critical mediator of the hyperinflammatory response in severe COVID-19 and support its inhibition as a promising therapeutic strategy to mitigate inflammatory damage and reduce mortality. SignificanceThis study provides critical insights into the mechanisms underlying severe COVID-19, identifying 12-Lipoxygenase (12-LOX) as a key driver of the hyperinflammatory response that contributes to disease severity and mortality. By demonstrating that SARS-CoV-2 hijacks host lipid metabolism to elevate pro-inflammatory lipid mediators, the research uncovers a novel pathogenic pathway that exacerbates lung inflammation. The use of VLX-1005, a selective 12-LOX inhibitor, significantly improved survival and reduced inflammatory damage in a mouse model, highlighting its therapeutic potential. These findings not only deepen our understanding of COVID-19 pathogenesis but also position 12-LOX as a promising target for intervention, offering a new avenue for mitigating the effects of cytokine storms in severe cases.

microbiology↗

bioRxiv2025

12-Lipoxygenase inhibition improves glucose homeostasis and obesity-associated inflammation in human gene replacement mice

Obesity-associated inflammation is characterized by macrophage infiltration into peripheral tissues, contributing to the progression of prediabetes and type 2 diabetes (T2D). The enzyme 12-lipoxygenase (12-LOX) catalyzes the formation of pro-inflammatory eicosanoids and is known to promote the migration of macrophages, yet its role in obesity-associated inflammation remains incompletely understood. Furthermore, differences between mouse and human orthologs of 12-LOX have limited efforts to study existing pharmacologic inhibitors of 12-LOX. In this study, we utilized a human gene replacement mouse model in which the gene encoding mouse 12-LOX (Alox15) is replaced by the human ALOX12 gene. As a model of obesity and dysglycemia, we administered these mice a high-fat diet. We subsequently investigated the effects of VLX-1005, a potent and selective small molecule inhibitor of human 12-LOX. Oral administration of VLX-1005 resulted in improved glucose homeostasis, decreased {beta} cell dedifferentiation, and reduced macrophage infiltration in islets and adipose tissue. Analysis of the stromal vascular fraction from adipose tissue showed a reduction in myeloid cells and cytokine expression with VLX-1005 treatment, indicating decreased adipose tissue inflammation. In a distinct mouse model in which Alox15 was selectively deleted in myeloid cells, we observed decreased {beta} cell dedifferentiation and reduced macrophage infiltration in both islets and adipose tissue, suggesting that the effects of VLX-1005 may relate to the inhibition of 12-LOX in macrophages. These findings highlight 12-LOX as a key factor in obesity-associated inflammation and suggest that 12-LOX inhibition could serve as a therapeutic strategy to improve glucose homeostasis and peripheral inflammation in the setting of obesity and T2D.

physiology↗

bioRxiv2024

12-Lipoxygenase Inhibition Suppresses Islet Immune and Inflammatory Responses and Delays Autoimmune Diabetes in Human Gene Replacement Mice

Type 1 diabetes (T1D) is characterized by the autoimmune destruction of insulin-producing {beta} cells and involves an interplay between {beta} cells and cells of the innate and adaptive immune systems. We investigated the therapeutic potential of targeting 12-lipoxygenase (12-LOX), an enzyme implicated in inflammatory pathways in {beta} cells and macrophages, using a mouse model in which the endogenous mouse Alox15 gene is replaced by the human ALOX12 gene. Our finding demonstrated that VLX-1005, a potent 12-LOX inhibitor, effectively delayed the onset of autoimmune diabetes in human gene replacement non-obese diabetic mice. By spatial proteomics analysis, VLX-1005 treatment resulted in marked reductions in infiltrating T and B cells and macrophages with accompanying increases in immune checkpoint molecule PD-L1, suggesting a shift towards an immune-suppressive microenvironment. RNA sequencing analysis of isolated islets and polarized proinflammatory macrophages revealed significant alteration of cytokine-responsive pathways and a reduction in interferon response after VLX-1005 treatment. Our studies demonstrated that the ALOX12 human replacement gene mouse provides a platform for the preclinical evaluation of LOX inhibitors and supports VLX-1005 as an inhibitor of human 12-LOX that engages the enzymatic target and alters the inflammatory phenotypes of islets and macrophages to promote the delay of autoimmune diabetes.

molecular biology↗

bioRxiv2020

Ameliorative effect of a quinazoline-based bromodomain inhibitor, CN210, on experimentally-induced Crohn's disease-like murine ileitis via inhibition of inflammatory cytokine expression

Inhibitors of bromodomain and extra-terminal motif proteins ("BET inhibitors") are emerging epigenetic therapeutics that exert their effects by suppressing the expression of genes that drive cancer and inflammation. The present study examined the anti-inflammatory effects of a quinazoline-based BET inhibitor, CN210, which also inhibits bromodomains of two paralogous histone acetyltransferases (HATs), such as cAMP-responsive element binding protein-binding protein (CBP) and p300. To assess its effectiveness against inflammatory bowel disease (IBD), CN210 was tested in an experimentally-induced murine Crohns disease (CD)-like ileitis model. Ileitis was induced in mice by subcutaneous administration of indomethacin and CN210 was given orally 30 min before and 24 h after the indomethacin administration. Whilst indomethacin produced severe ileitis accompanied by an increase in ileal mucosal myeloperoxidase (MPO) activity, administration of CN210 reduced the severity of ileitis in a dose-dependent manner and suppressed the MPO activity. Similarly, upregulation of inflammatory cytokines was observed in ileitis mucosa after indomethacin injection but this response was significantly attenuated by CN210 administration. To further characterize the effects of CN210 on inflammatory pathways, monocyte/macrophage-like cell line RAW264 treated with lipopolysaccharide (LPS) was exposed to CN210. CN210 significantly attenuated the expression of inflammatory cytokines and reversed the activation of NF-{kappa}B and MAP kinases induced by LPS. These findings suggest that CN210 ameliorates indomethacin-induced ileitis due at least in part to the inhibition of inflammatory cytokine expression via attenuation of NF-{kappa}B and MAP kinase pathways, thus representing a new mode of therapy for CD.

pharmacology and toxicology↗

bioRxiv2018

Molecular basis for activation of lecithin:cholesterol acyltransferase by a compound that increases HDL cholesterol

Lecithin:cholesterol acyltransferase (LCAT) and LCAT-activating small molecules are being investigated as treatments for coronary heart disease (CHD) and familial LCAT deficiency (FLD). Herein we report the crystal structure of LCAT bound to a potent activator and an acyl intermediate-like inhibitor, thereby revealing an active conformation of LCAT and that the activator is bound exclusively to its membrane-binding domain (MBD). Functional studies indicate that the compound does not modulate the affinity of LCAT for HDL, but instead stabilizes residues in the MBD and likely facilitates channeling of substrates into the active site. By demonstrating that these activators increase the activity of an FLD variant, we show that compounds targeting the MBD have therapeutic potential. In addition, our data better define the acyl binding site of LCAT and pave the way for rational design of LCAT agonists and improved biotherapeutics for augmenting or restoring reverse cholesterol transport in CHD and FLD patients.

biochemistry↗