Morse, David

Abstract Metabolic reprogramming is a fundamental determinant of immune cell fate and effector function during inflammation, yet how distinct metabolic pathways regulate pathogenic lung macrophage activity and contribute to fibrotic remodeling remains incompletely understood. Here, we integrated single-cell RNA sequencing, lineage-specific genetic mouse models, and fate-mapping approaches to define the metabolic pathways that regulate the pro-fibrotic activity of lung macrophages. We found that such cells undergo pronounced aerobic glycolysis in the bleomycin-induced mouse model of pulmonary fibrosis. Myeloid cell-specific depletion of lactate dehydrogenase A (Ldha), but not of mitochondrial pyruvate carrier (Mpc), markedly attenuated lung fibrosis and improved survival. Mechanistically, enhanced glycolytic flux increased lactate production, which promoted histone lysine lactylation and facilitated Arginase 1 (Arg1) expression in lung macrophages, thereby driving fibrotic progression. Using monocyte fate-mapping, we further demonstrated that Arg1 expression is largely restricted to recruited monocyte-derived macrophages rather than lung-resident macrophages. Notably, selective deletion of Ldha in granulocyte-monocyte progenitors and their progeny was sufficient to suppress Arg1 expression and reduce fibrosis severity. In human lung samples, we observed significantly elevated expression of ARG1 and key glycolytic enzymes in patients with idiopathic pulmonary fibrosis, despite species-specific differences in the immune cell types expressing ARG1. Together, these findings identify an aerobic glycolysis–lactate–histone lactylation axis that regulates pro-fibrotic myeloid cell function and represents a potential therapeutic target in pulmonary fibrosis.

e24015 Background: Anthracyclines are effective cancer therapeutics but can cause cardiotoxicity. Recent studies suggest a connection between efficacy and toxicity in that the effects of anthracyclines on cancer cells leads to the release of interleukin 1-alpha (IL-1⍺), which negatively impacts cardiomyocyte metabolism and thereby cardiac function. This observation was made in in vivo and in vitro models of acute myeloid leukemia (AML); whether this holds true for other cancer cell lines remains unclear. Methods: Herein we characterized the cytokine profile of 9 cancer cell lines exposed to doxorubicin (1 µM for 24 hours) and then tested the effects of interleukin 1-alpha (IL-1⍺, 50-150 ng/mL) on the viability and metabolism of neonatal cardiomyocyte. We used Seahorse to assess cardiomyocyte glycolysis via extracellular acidification rate (ECAR) and mitochondrial oxidative phosphorylation based on the oxygen consumption rate (OCR). Results: As outlined in Table 1, different hematological and breast cancer cell lines showed a range of cytokine profile in response to doxorubicin exposure. Of the cytokines with putative action on cardiomyocyte metabolism IL-1⍺was one of the most induced in 3 out of 5 murine breast cancer, murine B- and T-cell lymphoma, as well as murine and human AML human and murine cell lines. Doxorubicin did not induce IL-1⍺ expression in macrophage cell lines (RAW) or directly in cardiomyocytes. Exposing neonatal cardiomyocytes to different concentrations of IL-1⍺ did not decrease but rather increased OCR and especially ECAR. Conclusions: These data confirm the release of IL-1⍺ from AML as well as several, but not all breast cancer cell lines. Furthermore, purified IL-1⍺ increased oxidative phosphorylation and glycolysis in murine neonatal cardiomyocytes. These data point out heterogeneity in the cytokine release pattern from anthracycline-treated cancer cell lines and their impact on cardiomyocyte metabolism. Further studies are required to define the nuances of crosstalk between cancer and the heart and its contribution to the variation in cardiotoxicity risk. Cytokine profile of cancer cell lines. Cytokines RAW Neonatal MC38HuPD-L1 EMT6 JC E0771 4T1 B Lymphoma: A20 T Lymphoma: E.G7-OVA AML Human: THP-1 AML mouse: C1498 ICAM-1, CD54 ++ ++ ++ ++ ++ ++ IL-1α IL-1F1 + + + + + + + IL-10 + + IL-16 ++ ++ ++ CXCL10/CRG-2 ++ + ++ ++ ++ ++ ++ ++ ++ M-CSF ++ ++ ++ + ++ ++ ++ ++ + RANTES CCL5 + ++ ++ ++ ++ TNF-α +++ + ++ + + + + +

Carotid plaque vulnerability features beyond the degree of stenosis may play a key role in the pathogenesis and recurrence of ischemic cerebrovascular events. This study sought to compare intraplaque hemorrhage (IPH) as a marker of plaque vulnerability in symptomatic patients with mild (<50%), moderate (50%–69%), and severe (≥70%) carotid artery stenosis. We included patients who experienced ischemic cerebrovascular events with no other identifiable sources and underwent carotid endarterectomy for mild (n=32), moderate (n=47), and severe (n=58) carotid artery stenosis. The degree of stenosis and imaging hallmarks were assessed by computed tomography angiography or magnetic resonance angiography. Plaque specimens were stained with hematoxylin and eosin and Movat pentachrome staining. Carotid plaques of patients with mild stenosis had a higher extent of IPH (%) on tissue analysis compared with patients with moderate (mild, 15.7% [interquartile range, 7.8%–26.7%]; moderate, 3.9% [0.0%–9.2%]; P <0.001) and severe carotid artery stenosis (mild, 15.7% [interquartile range, 7.8%–26.7%]; severe, 2.5% [interquartile range, 0.0%–11.2%]; P <0.001). When considering the degree of carotid artery stenosis as a continuous variable, a lower lumen narrowing was associated with higher extent of IPH ( P <0.001; R, −0.329). Our major finding is the association of IPH with mild carotid artery stenosis based on histological analysis. The current study may suggest that IPH potentially plays a role in the mechanism of stroke in patients with nonobstructive carotid stenosis.

Abstract Aims Circulating progenitor cells (CPCs) play a role in vascular repair and plaque stability, while osteocalcin (OC) expressing CPCs have been linked to unstable plaque and adverse cardiovascular outcomes. However, their role in cardiac allograft vasculopathy (CAV) has not been elucidated. This cohort study aimed to investigate the contribution of CPCs on CAV progression and cardiovascular events after heart transplantation. Methods and results A total of 80 heart transplant patients (mean age 55 ± 14 years, 72% male) undergoing annual intravascular ultrasound (IVUS) had fresh CPCs marked by CD34, CD133, and OC counted in peripheral blood using flow cytometry, on the same day as baseline IVUS. CAV progression was assessed by IVUS as the change (Δ) in plaque volume divided by segment length (PV/SL), adjusted for the time between IVUS measurements [median 3.0, interquartile range (2.8–3.1) years] and was defined as ΔPV/SL that is above the median ΔPV/SL of study population. Major adverse cardiac events (MACEs) were defined as any incident of revascularization, myocardial infarction, heart failure admission, re-transplantation, stroke, and death. Patients with higher CD34+CD133+ CPCs had a decreased risk of CAV progression [odds ratio 0.58, 95% confidence interval (CI) (0.37–0.92), P = 0.01] and MACE [hazard ratio (HR) 0.79, 95% CI (0.66–0.99), P = 0.05] during a median (interquartile range) follow-up of 8.0 years (7.2–8.3). Contrarily, higher OC+ cell counts were associated with an increased risk of MACE [HR 1.26, 95% CI (1.03–1.57), P = 0.02]. Conclusions Lower levels of CD34+CD133+ CPCs are associated with plaque progression and adverse long-term outcomes in patients who underwent allograft heart transplantation. In contrast, higher circulating OC+ levels are associated with adverse long-term outcomes. Thus, CPCs might play a role in amelioration of transplant vasculopathy, while OC expression by these cells might play a role in progression.