Biology subjects

Upchurch, G.

Publications and source records attributed to Upchurch, G..

3 recordsLinked to original sources

bioRxiv2026

Proprotein convertase subtilisin kexin type 9 (PCSK9) inhibition attenuates abdominal aortic aneurysm formation via enhanced macrophage-dependent efferocytosis

Abdominal aortic aneurysms (AAAs) occur predominantly in the elderly population and currently there is no effective pharmacological therapy for mitigating AAA growth and preventing impending rupture. Proprotein subtilisin kexin type 9 (PCSK9) gene has been identified as a specific risk-locus for AAA development. However, the mechanistic and clinical role of PCSK9-mediated signaling in AAAs has not been delineated. We demonstrate that treatment with PCSK9 inhibitors, such as Evolocumab, mitigates vascular inflammation and remodeling, resulting in attenuated aneurysm growth in clinical datasets as well as experimental models of AAA and aortic rupture. Mechanistically, Evolocumab immunomodulates macrophage reprogramming to enhance clearance of apoptotic smooth muscle cells via MerTK-dependent efferocytosis that ameliorates aortic inflammation and vascular remodeling. Furthermore, Evolocumab increases the expression of oxidized phosphatidylserine species and decreases expression of lysophospholipids, succinate, and glycolytic intermediates within the aortic wall compared to untreated controls, further enhancing the pro-resolving functions of macrophages. Collectively, our data demonstrates the ability of PCSK9 inhibition to regulate macrophage-specific efferocytosis that limits AAA progression and prevents aortic rupture.

immunology↗

bioRxiv2025

Temporal changes in the protein cargo of extracellular vesicles and resultant immune reprogramming after severe burn injury in humans and mice.

IntroductionSevere injury, including burn trauma, leads to profound immune dysfunction, yet the mechanisms driving these changes remain incompletely defined. This lack of understanding has hindered efforts to modulate the immune response effectively. Additionally, a clear biomarker profile to guide clinicians in identifying burn patients at high risk for poor clinical outcomes is lacking. Extracellular vesicles (EVs) have emerged as novel mediators of immune dysfunction in various pathologies. Prior studies in mouse models have demonstrated that plasma EVs increase following burn injury and contribute to immune dysfunction. Furthermore, EVs have potential as biomarkers for predicting extended hospital stays in burn patients. This study hypothesizes that human EVs, purified early and late after burn injury, will exhibit immune reprogramming effects similar to those observed in mice and that specific EV protein cargo may serve as biomarkers of immune and physiological responses to burn injury. MethodsEVs were isolated from the plasma of burn-injury patients at early (<72h) and late ([≥]14 days) time points post-injury. Using unbiased immune transcriptome and bioinformatic causal network analyses, the immunomodulatory effects of these EVs were assessed in human THP-1 macrophages. Mass spectrometry-based quantitative proteomics and pathway analyses were conducted to characterize the protein cargo of EVs from both human and mouse models at different post-burn phases. ResultsEarly post-burn human EVs induced significant immune reprogramming in macrophages, increasing pro-inflammatory signaling while suppressing anti-inflammatory pathways. In contrast, late post-burn EVs exhibited an immunosuppressive profile, with downregulation of pro-inflammatory pathways and upregulation of anti-inflammatory signaling. Proteomic analyses revealed that human and mouse EVs contained unique and overlapping protein cargo across different time points. At day 7 post-burn, mouse EVs were enriched in circulation/complement and neuronal proteins, whereas by day 14, reductions in membrane and metabolism-associated proteins were observed. Similarly, in human EVs at 14 days post-burn, increased levels of circulation/complement, immune, and transport proteins were detected. ConclusionsEVs from burn-injury patients at distinct time points differentially modulate immune responses in macrophages, mirroring the temporal immune phenotypes observed in clinical settings. These findings suggest that EV-macrophage interactions play a crucial role in burn-induced immune dysfunction and highlight the potential of EV protein cargo as biomarkers for immune status and patient outcomes following burn injury. Summary SentenceHuman extracellular vesicles released into the plasma after severe burn injury can reprogram the immune system with corresponding immunomodulatory protein cargo.

immunology↗

bioRxiv2024

Gasdermin D deficiency attenuates development of ascending aortic dissections in a novel mouse model

BackgroundThoracic aortic dissection (TAD) is a silent killer. Approximately two-thirds of the cases occur in the ascending aorta (i.e. type A dissection) and majority of them are unrelated to genetic mutations. However, animal models of spontaneous type A dissection are not widely available. In the present study, a novel mouse TAD model was created. Further, the role of gasdermin D (GSDMD) in TAD development was evaluated. MethodsTADs were created by treating ascending aorta of adult mice (C57BL/6J) with active elastase (40.0 U/ml) and {beta}-aminopropionitrile (Act E+BAPN). The temporal progress of the TAD pathology was rigorously characterized by histological evaluation and scanning electron microscopy, while potential mechanisms explored with bulk RNA sequencing of specimens collected at multiple timepoints. With this novel TAD model, further experiments were performed with Gsdmd-/- mice to evaluate its impact on TAD formation. ResultsThe ascending aorta challenged with Act E+BAPN developed pathology characterized by an early onset of intimomedial tears (complete penetration) and intramural hematoma, followed by progressive medial loss and aortic dilation. Ingenuity Pathway Analysis and functional annotation of differentially expressed genes suggested that a unique inflammatory micro-environment, rather than general inflammation, promoted the onset of TADs by specifically recruiting neutrophils to the aortic wall, while the pathology at the advanced stage was driven by T-cell mediated immune injury. Gsdmd-/- attenuated medial loss, adventitial fibrosis, and dilation of TADs. This protective effect was associated with a reduced number of TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) positive cells and T-cells in TADs. ConclusionsA novel mouse TAD model was created in the ascending aorta. It produces a unique microenvironment to activate different immune cell subsets, promoting onset and subsequent remodeling of TADs. Consistently, Gsdmd-/- attenuates TAD development, with modulation of cell death and T-cell response likely acting as the underlying mechanism. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=173 HEIGHT=200 SRC="FIGDIR/small/609270v1_ufig1.gif" ALT="Figure 1"> View larger version (91K): org.highwire.dtl.DTLVardef@173a620org.highwire.dtl.DTLVardef@19f8f01org.highwire.dtl.DTLVardef@65bcb9org.highwire.dtl.DTLVardef@1492f88_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗