Biology subjects

Protty, M.

Publications and source records attributed to Protty, M..

3 recordsLinked to original sources

bioRxiv2025

The coronavirus envelope is conserved, contains bioactive lipids needed for replication, and is modulated in response to host inflammation

How inflammation or disease regulates coronavirus lipid membranes is currently unknown, while patient-derived viral envelopes have never been structurally characterized. Here, we show that four cultured SARS-CoV-2 strains (England2, Alpha, Beta, and Delta) possess conserved, phospholipid- and cholesterol-rich envelopes, with pro-thrombotic and infection-promoting aminophospholipids (aPL) displayed predominantly on the outer leaflet (approximately 70-80%). Exposure to interleukin-4 (IL-4) markedly altered envelope fatty acyl composition, whereas interleukin-6 (with or without its soluble receptor IL-6R) and dexamethasone had no detectable effect. Viral envelopes were susceptible to hydrolysis by secretory phospholipase A2 (sPLA2), an enzyme associated with adverse clinical outcomes. SARS-CoV-2 isolated directly from patient saliva exhibited cholesterol-enriched envelopes that were highly conserved across clinical isolates. In addition, clinical samples contained pro-coagulant oxidized phospholipids and bioactive lipoxygenase (LOX)-derived oxylipins. The dominance of external facing pro-coagulant aPL and eoxPL may support known thrombotic complications of severe COVID19 viremia. Last, gene-silencing experiments demonstrated that 15-LOX2 is required for replication of related coronaviruses. Together, these findings reposition the coronavirus envelope as an active, dynamic structure rather than a passive scaffold, and challenge the protein-centric view of viral function. The lipid envelope is proposed as a potential therapeutic target through modulation of host innate immunity, and dampening thrombotic potential. Significance statementViruses such as SARS-CoV-2 are surrounded by a host-derived lipid envelope. Little is known about how this changes during infection/inflammation. We determined the lipid composition of the SARS-CoV-2 envelope using both laboratory-grown viruses and patient isolates. Across several pandemic strains, the envelope was rich in cholesterol and phospholipids and showed a consistent structure. Lipids linked to thrombosis and infection were mainly exposed on the outer virus surface. The inflammatory cytokine interleukin-4 altered the envelopes fatty acid composition, while other treatments did not. Patient-derived viruses contained additional bioactive lipids, and blocking an enzyme that generates these lipids reduced coronavirus replication. In summary, the envelope is an active component of infection and potential target for new treatments to dampen infectivity and thrombosis.

immunology↗

bioRxiv2025

Interleukin-6 elevates thrombosis via pro-coagulant phospholipids from platelet 12-lipoxygenase in rheumatoid arthritis.

BackgroundRheumatoid arthritis (RA) is associated with significantly higher thrombotic risk, which is not yet mechanistically understood. Here, the role of pro-coagulant membranes of platelets and blood cells in driving thrombosis, and their regulation by inflammation was determined using human cohorts and genetically-modified mice. MethodsAntigen-induced arthritis (AIA) was induced in WT, Il27ra-/-, Il6ra-/-, Alox12-/- and Alox15-/- mice. Coagulation and inflammatory markers were measured in plasma. Lipidomics was performed on blood cells and synovium analyzing pro-coagulant enzymatically-oxidized phospholipids (eoxPL) and oxylipins. Two human RA patient cohorts were characterized for eoxPL generation in blood cells, and chronic immune response to eoxPL in vivo. ResultsAIA induction significantly elevated plasma thrombin-antithrombin (TAT) complexes, serum amyloid A (SAA), and eoxPL in blood cells and platelets. Elevations in TATs, SAA and eoxPL were suppressed by genetic deletion of IL-6Ra, while platelet Alox12 deletion prevented TAT and eoxPL increases. This indicates a direct role for IL-6 in elevating thrombosis via upregulation of platelet eoxPL. In contrast, leukocyte Alox15 deletion did not impact TATs or eoxPL. Deletion of either LOX isoform worsened AIA joint pathology. Synovial tissue demonstrated raised eoxPL, but exclusively from Alox15, indicating leukocyte origin. Thus, both LOX isoforms contribute to AIA, but through different mechanisms. In human RA, platelet counts, and plasma TATs were elevated, and plasma had significantly elevated IgG against eoxPL, indicating patients experience chronic exposure to the lipids in vivo. ConclusionsPlatelet-derived pro-coagulant eoxPL are elevated in human and murine arthritis along with higher coagulation markers. In mice, this was mediated by the IL-6/Alox12 axis and directly responsible for the higher thrombotic risk. IL-6 plays a central role in driving platelet activation in RA, with the pro-coagulant lipid membrane representing a novel target. Reducing inflammation using DMARDs, particularly targeting IL-6 may reduce platelet pro-coagulant activity and thrombosis risk in RA.

pharmacology and toxicology↗

bioRxiv2025

12/15-Lipoxygenase orchestrates murine wound healing via PPARg-activating oxylipins acting holistically to dampen inflammation.

12/15-lipoxygenase (12/15-LOX, Alox15) generates bioactive oxygenated lipids during inflammation, however its homeostatic role(s) in normal healing are unclear. Here, the role of 12/15-LOX in resolving skin wounds was elucidated, focusing on how its lipids act together in physiologically relevant amounts. In mice, wounding caused acute appearance of 12/15-LOX-expressing macrophages and stem cells, coupled to early generation of [~]12 monohydroxy-oxylipins and enzymatically oxygenated phospholipids (eoxPL). Alox15 deletion increased -smooth muscle actin, collagen deposition, stem cell/fibroblast proliferation, IL6/pSTAT3, pSMAD3, and IFN-{gamma} levels. Conversely, CD206 expression, F480+ cells, MMP9 and MMP2 activities were reduced. Alox15-/- skin was deficient in PPAR{gamma}/adiponectin activity. Furthermore, while pro-inflammatory genes were upregulated as normal during wounding, many including Il6, Il1b, ccl4, Cd14, Cd274, Clec4d, Clec4e, Csf3, and Cxcl2 failed to revert to baseline during healing, indicating disruption of an anti-inflammatory brake. Reconstituting Alox15-/- wounds with a physiological mixture of Alox15-derived primary oxylipins generated by healing wounds restored MMP and dampened collagen deposition. The oxylipin mixture activated PPAR{gamma} in vitro, while in vivo, the PPAR{gamma} co-activator, Helz2, was significantly upregulated. Additional inflammatory and proliferative gene networks impacted by Alox15-/-included Elf4, Cebpb and Tcf3, with many of their associated genes significantly dysregulated. In summary, the impact of 12/15-LOX is ascribed to the deficiency of abundantly generated monohydroxy oxylipins acting together via PPAR{gamma}/adiponectin. The identification of multiple gene alterations reveals several new targets for treatment of non-healing wounds. Our studies demonstrate that abundant 12/15-LOX oxylipins act together, dampening inflammation in vivo, revealing a need to consider lipid signaling holistically. Significance statementDefective wound healing is a significant global clinical problem. Macrophage 12/15-lipoxygenase (12/15-LOX, Alox15) generates abundant lipid mediators termed oxylipins during inflammation. However, its physiological role during resolving wound healing is unclear, with studies so far assessing the bioactivity of individual lipids pharmacologically, rather than holistically in physiological amounts. Here, we report that Alox15 deficiency in mice caused a fibrotic response with failure to dampen inflammation, due to a dysregulated PPAR{gamma}/adiponectin axis. Treatment of Alox15-/- wounds with physiological mixtures of PPAR{gamma}-activating 12/15-LOX primary monohydroxy products restored the phenotype. Several transcriptional networks (Elf4, Cebpb and Tcf3) controlled by Alox15 were uncovered, identifying new targets for promoting physiological wound healing.

pharmacology and toxicology↗