Acute myocardial infarction (AMI) is associated with well-established metabolic risk factors, especially hyperlipidemia and obesity. Myocardial ischemia-reperfusion injury (mIRI) significantly offsets the therapeutic efficacy of revascularization. Previous studies indicated that disrupted lipid homeostasis can lead to lipid peroxidation damage and inflammation, yet the underlying mechanisms remain unclear. Here, the study demonstrates that hyperlipidemia is a key driver of mIRI. Long-chain fatty acyl-CoA synthetase 1 (ACSL1) is upregulated in both hyperlipidemia and AMI patients. ACSL1 expression is induced by a high-fat microenvironment (oxLDL and palmitic acid) in a concentration-dependent manner. Interestingly, the protein level is positively correlated with total cholesterol level and thromboinflammatory biomarkers. Furthermore, ACSL1 reprogrammed lipid metabolism in monocytes, leading to the accumulation of lysophosphatidylcholine (LPC)/lysophosphatidic acid (LPA). The monocytic LPC/LPA axis accelerated lipid peroxidation and neutrophil extracellular traps (NETs)-induced thromboinflammation via the paracrine effect. The main LPA producer Autotaxinis is also induced under high-fat conditions and then exerts thromboinflammation response through converted LPC to LPA. Finally, ACSL1 knockdown or NETs release inhibitor (DNase I or GSK484) significantly alleviated mIRI in mice. These findings highlight ACSL1 and NETosis as potential key targets for preventing mIRI and underscore the lipid peroxidation in the mechanisms of ACSL1-mediated thromboinflammation.
© 2025 The Author(s). Advanced Science published by Wiley‐VCH GmbH.

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare yet serious adverse effect of the adenoviral vector vaccines ChAdOx1 nCoV-19 (AstraZeneca) and Ad26.COV2.S (Janssen) against COVID-19. The mechanisms involved in clot formation and thrombocytopenia in VITT are yet to be fully determined. Here we show neutrophils undergoing NETosis and confirm expression markers of NETs in VITT patients. VITT antibodies directly stimulate neutrophils to release NETs and induce thrombus formation containing abundant platelets, neutrophils, fibrin, extracellular DNA and citrullinated histone H3 in a flow microfluidics system and in vivo. Inhibition of NETosis prevents VITT-induced thrombosis in mice but not thrombocytopenia. In contrast, in vivo blockage of FcγRIIa abrogates both thrombosis and thrombocytopenia suggesting these are distinct processes. Our findings indicate that anti-PF4 antibodies activate blood cells via FcγRIIa and are responsible for thrombosis and thrombocytopenia in VITT. Future development of NETosis and FcγRIIa inhibitors are needed to treat VITT and similar immune thrombotic thrombocytopenia conditions more effectively, leading to better patient outcomes.
© 2022. The Author(s).

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare yet serious adverse effect of adenoviral vector vaccines (AstraZeneca and Johnson Johnson) against COVID-19 1 . Anti-platelet factor 4 (PF4) antibodies are present in VITT patients 2,3 . Although the current view suggests that platelet activation by anti-PF4 antibodies is the cause of thrombosis there is as yet no direct evidence that the antibodies induce clot formation and thrombocytopenia (reduction in platelet counts) in VITT and the mechanisms involved remain unknown 4 . Here we show that VITT antibodies induce thrombosis and thrombocytopenia, and that thrombus formation is mediated by neutrophil extracellular traps (NETs). We found markers of NETosis, abundance of neutrophil/platelet aggregates and presence of neutrophils undergoing NETosis in patients with active VITT. VITT antibodies directly stimulate neutrophils to release NETs and induce thrombus formation containing abundant platelets, neutrophils, fibrin, extracellular DNA and citrullinated histone H3 using an in vitro blood flow microfluidic system. In transgenic mice expressing human PF4 and FcγRIIa, VITT antibodies lead to thrombosis, thrombocytopenia and formation of low density granulocytes. Pharmacological and genetic inhibition of NETosis prevents VITT-induced thrombosis in mice but not thrombocytopenia. In contrast, in vivo blockage of FcγRIIa abrogates both thrombosis and thrombocytopenia suggesting they are distinct processes. Our findings indicate that VITT antibodies activate cells via FcγRIIa and are responsible for thrombosis and thrombocytopenia. This study identifies NETosis as a pathogenic mechanism for thrombus formation in VITT. We anticipate our findings will motivate future development of NETosis and FcγRIIa inhibitors as potential specific therapies for VITT and consequently better patient outcomes.

Heparin-induced thrombocytopenia/thrombosis (HIT) is a serious immune reaction to heparins, characterized by thrombocytopenia and often severe thrombosis with high morbidity and mortality. HIT is mediated by IgG antibodies against heparin/platelet factor 4 antigenic complexes. These complexes are thought to activate platelets leading to thrombocytopenia and thrombosis. Here we show that HIT immune complexes induce NETosis via interaction with FcγRIIa on neutrophils and through neutrophil-platelet association. HIT immune complexes induce formation of thrombi containing neutrophils, extracellular DNA, citrullinated histone H3 and platelets in a microfluidics system and in vivo, while neutrophil depletion abolishes thrombus formation. Absence of PAD4 or PAD4 inhibition with GSK484 abrogates thrombus formation but not thrombocytopenia, suggesting they are induced by separate mechanisms. NETs markers and neutrophils undergoing NETosis are present in HIT patients. Our findings demonstrating the involvement of NETosis in thrombosis will modify the current concept of HIT pathogenesis and may lead to new therapeutic strategies.

Bilineage T lymphoid and myeloid (T/My) neoplasms are rare entities among the hematopoietic and lymphoid malignancies. The majority of patients present with leukemic symptoms in which blasts are observed in the peripheral blood (PB) or bone marrow (BM) at a percentage of >20% of nucleated cells. Only a minimal number of cases of T/My bilineage hematopoietic and lymphoid malignancy have been reported with extramedullary infiltration as the initial symptom. The origin of the neoplastic cells in T/My bilineage malignancy has been documented as the hematopoietic stem cells. The present study reports the case of a 31-year-old man with a T/My bilineage malignancy, which initially showed cervical lymph node enlargement beyond the diagnostic criteria of leukemia in the PB and in the BM. Two distinct malignant populations were detected in the cervical lymph node and pleural effusion, one of which was positive for MPO-staining, while the other was positive for cytoplasmic cluster of differentiation 3. Mutations in platelet-derived growth factor receptor α, platelet-derived growth factor receptor β, fibroblast growth factor receptor 1 and other chromosome abnormalities were excluded. The patient obtained complete remission after conventional chemotherapy, but relapsed with bilineage leukemia within a short period of time. Lymphoid and myeloid lineages have been reported to be differentiated from multipotent progenitors asymmetrically. However, the cellular mutation stage in T/My bilineage malignancy remains unclear. The present study also reviews the origin, development and therapeutic strategies for extramedullary T/My bilineage malignancy.