BACKGROUND: Aldosterone has been described to initiate cardiovascular diseases by triggering exacerbated sterile vascular inflammation. The functions of CCL5 (C-C motif chemokine ligand 5) and its receptor CCR5 (C-C motif chemokine receptor 5) are well known in infectious diseases, their contributions to aldosterone-induced vascular injury and hypertension remain unknown. METHODS: We analyzed the vascular profile, blood pressure, and renal damage in wild-type (CCR5 ^+/+ ) and CCR5 knockout (CCR5 ^−/− ) mice treated with aldosterone (600 µg/kg per day for 14 days) while receiving 1% saline to drink. Vascular function was analyzed in aorta and mesenteric arteries, blood pressure was measured by telemetry and renal injury and inflammation were analyzed via histology and flow cytometry. Endothelial cells were used to study the molecular signaling whereby CCL5 induces endothelial dysfunction. RESULTS: Aldosterone treatment resulted in exaggerated CCL5 circulating levels and vascular CCR5 expression in CCR5 ^+/+ mice accompanied by endothelial dysfunction, hypertension, and renal inflammation and damage. CCR5 ^−/− mice were protected from these aldosterone-induced effects. Mechanistically, we demonstrated that CCL5 increased NOX1 (NADPH oxidase 1) expression, reactive oxygen species formation, NFκB (nuclear factor kappa B) activation, and inflammation and reduced NO production in isolated endothelial cells. These effects were abolished by antagonizing CCR5 with Maraviroc. Finally, aorta incubated with CCL5 displayed severe endothelial dysfunction, which is prevented by blocking NOX1, NFκB, or CCR5. CONCLUSIONS: Our data demonstrate that CCL5/CCR5, through activation of NFκB and NOX1, is critically involved in aldosterone-induced vascular and renal damage and hypertension placing CCL5 and CCR5 as potential therapeutic targets for conditions characterized by aldosterone excess.

How cellular metabolism facilitates tissue-resident macrophage maintenance remains elusive. Here we show that visceral adipose tissue (VAT)-resident macrophages, unlike monocyte-derived macrophages, are enriched with mitochondrial-specific antioxidant enzymes restraining inflammation and promoting VAT homeostasis and insulin sensitivity. Additionally, VAT resident macrophages express high levels of plasminogen activator inhibitor type 2, encoded by SerpinB2, which is involved in the blood coagulation cascade. SerpinB2 promotes adipose resident macrophage survival by regulating mitochondrial oxidative phosphorylation and preventing the release of pro-apoptotic cytochrome c from the mitochondria into the cytoplasm via antioxidant glutathione production. Chronic inflammation, such as obesity, diminishes SerpinB2 expression in VAT macrophages in patients and mice, leading to the decline of this macrophage subset. Mechanistically, interferon-γ elevation in diabetes induces Ikaros, a transcriptional suppressor, which binds to the SerpinB2 promoter and decreases SerpinB2 expression. Congruently, selective depletion of the IFN-γ receptor in myeloid cells or supplementation of macrophage-specific SerpinB2 deficient mice with N-acetylcysteine, a glutathione precursor, restores VAT resident macrophage survival, decreases adipocyte size, and improves glucose tolerance and insulin sensitivity. Our data thus reveal an unexpected function of SerpinB2 in the regulation of mitochondrial function and survival of tissue-resident macrophages.

Background: Peripheral ischemia caused by peripheral artery disease is associated with systemic inflammation, which may aggravate underlying comorbidities such as atherosclerosis and heart failure. However, the mechanisms of increased inflammation and inflammatory cell production in patients with peripheral artery disease remain poorly understood. Methods: We used peripheral blood collected from patients with peripheral artery disease and performed hind limb ischemia (HI) in Apoe ^−/− mice fed a Western diet and C57BL/6J mice with a standard laboratory diet. Bulk and single-cell RNA sequencing analysis, whole-mount microscopy, and flow cytometry were performed to analyze hematopoietic stem and progenitor cell (HSPC) proliferation, differentiation, and relocation. Results: We observed augmented numbers of leukocytes in the blood of patients with peripheral artery disease and Apoe ^−/− mice with HI. RNA sequencing and whole-mount imaging of the bone marrow revealed HSPC migration into the vascular niche from the osteoblastic niche and their exaggerated proliferation and differentiation. Single-cell RNA sequencing demonstrated alterations in the genes responsible for inflammation, myeloid cell mobilization, and HSPC differentiation after HI. Heightened inflammation in Apoe ^−/− mice after HI aggravated atherosclerosis. Surprisingly, bone marrow HSPCs expressed higher amounts of the receptors for IL (interleukin)-1 and IL-3 after HI. Concomitantly, the promoters of Il1r1 and Il3rb had augmented H3K4me3 and H3K27ac marks after HI. Genetic and pharmacological inhibition of these receptors resulted in suppressed HSPC proliferation, reduced leukocyte production, and ameliorated atherosclerosis. Conclusions: Our findings demonstrate increased inflammation, HSPC abundance in the vascular niches of the bone marrow, and elevated IL-3Rb and IL-1R1 (IL-1 receptor 1) expression in HSPC following HI. Furthermore, the IL-3Rb and IL-1R1 signaling plays a pivotal role in HSPC proliferation, leukocyte abundance, and atherosclerosis aggravation after HI.

Air pollution has become an emerging invisible killer in recent years and is a major cause of morbidity and mortality globally. More than 90% of the world’s children breathe toxic air every day. India is among the top ten most highly polluted countries with an average PM₁₀ level of 134 μg/m³ per year. It is reported that 99% of India’s population encounters air pollution levels that exceed the World Health Organization Air Quality Guideline, advising a PM_2.5 permissible level of 10 μg/m³. Maternal exposure to air pollution has serious health outcomes in offspring because it can affect embryonic phases of development during the gestation period. A fetus is more prone to effects from air pollution during embryonic developmental phases due to resulting oxidative stress as antioxidant mechanisms are lacking at that stage. Any injury during this vulnerable period (embryonic phase) will have a long-term impact on offspring health, both early and later in life. Epidemiological studies have revealed that maternal exposure to air pollution increases the risk of development of airway disease in the offspring due to impaired lung development in utero. In this review, we discuss cellular mechanisms involved in maternal exposure to air pollution and how it can impact airway disease development in offspring. A better understanding of these mechanisms in the context of maternal exposure to air pollution can offer a new avenue to prevent the development of airway disease in offspring.

BACKGROUND: Emergency myelopoiesis by bone marrow hematopoietic stem and progenitor cells (HSPCs) exacerbates disease pathology in various chronic diseases, including myocardial infarction (MI) and atherosclerosis. However, the mechanisms triggering myelopoiesis in the bone marrow after a distant organ injury, such as MI, remain unknown. METHODS: We ligated the left descending coronary artery to induce MI in mice. Platelet-derived extracellular vesicles (pEVs) were detected and enumerated in mice and patients with MI using NanoSight, ImageStream, and flow cytometry. microRNA in pEVs was quantified using a microRNA array. We used parabiosis, flow cytometry, adoptive transfer experiments, and transgenic mice to assess the effects of pEVs and microRNA on HSPC lineage commitment and inflammatory cell generation. In addition, we carried out RNA sequencing, luciferase assay, lentivirus-mediated in vivo gene overexpression, and echocardiography to evaluate the merit of lactoferrin/lactotransferrin in post-MI pathogenesis. RESULTS: In this study, we demonstrate that patients and mice with MI and mice with hindlimb ischemia exhibit an increased number of circulating pEVs, which, in turn, augment HSPC number and proliferation in the bone marrow, leading to inflammatory myeloid cell generation and disease progression. S100A8/9 (S100 calcium-binding protein A8/A9), an alarmin complex produced by cardiomyocytes after MI, induced pEV secretion. In vivo and in vitro inhibition of platelet activation and exocytosis, and HSPC endocytosis, markedly lessened the production of pEV, HSPC proliferation, and myeloid cell generation in emergency hematopoiesis. A microRNA array revealed that pEVs isolated after MI had elevated cargo levels of miR-499 and miR-184, which were enriched in reticulated platelets after MI. miR-499 and miR-184 overexpression in mouse and human HSPCs resulted in enhanced hematopoiesis and myelopoiesis. miR-499–deficient pEVs were inefficient in stimulating emergency myelopoiesis and inducing cardiac remodeling after MI. RNA sequencing analysis, luciferase assay, and lentivirus-mediated in vivo gene overexpression demonstrated that miR-499 bound to the 3′ region of lactoferrin/lactotransferrin in HSPC to downregulate this gene, promoting myelopoiesis and unleashing inflammation. CONCLUSIONS: Our study suggests that pEVs generated after MI induce HSPC proliferation and inflammatory cell generation. These discoveries uncover several therapeutic targets to reduce cardiac inflammation and remodeling after MI.

Metabolic pathways, such as fatty acid oxidation and oxidative phosphorylation, can modulate inflammatory cells. However, little is known about the effects of the fatty acid synthesis pathway in macrophages on inflammation and cardiac remodeling after myocardial infarction (MI). Using spatial metabolomics, here we show that cardiac macrophages residing in the infarct synthesize de novo fatty acids and increase the production of fatty acid enzymes including ACLY and FASN. Mice deficient in myeloid Acly and Fasn have improved cardiac function after MI and reduced fibrosis. Combining Cleavage Under Targets and Release Using Nuclease (CUT&RUN), RNA sequencing analysis of Acly ^−/− macrophages, and macrophage-specific in vivo gene silencing, we demonstrate that ACLY acetylates the promoter region of the upstream regulator Krt17 , which drives the production of pro-fibrotic cytokines, including IL-33. Single-cell RNA sequencing of cardiac fibroblasts shows that the expansion of a population of fibroblasts (Fibroblast 5) expressing high levels of extracellular matrix genes after MI is confined in the absence of macrophage Acly . Finally, the analysis of spatial multi-omics data of human hearts with MI uncovers myofibroblasts with the Fibroblast 5 gene signature. These myofibroblasts are located near cardiac macrophages expressing high levels of ACLY. In summary, we show that macrophage ACLY and FASN are deleterious in MI pathogenesis.