Regulation and consequences of monocytosis

Determining toxicity of europium oxide nanoparticles in immune cell components and hematopoiesis in dominant organs in mice: Role of lysosomal fluid interaction

Extensive application of rare earth element oxide nanoparticles (REE NPs) has raised a concern over the possible toxic health effects after human exposure. Once entering the body, REE NPs are primarily processed by phagocytes in particular macrophages and undergo biotic phosphate complexation in lysosomal compartment. Such biotransformation affects the target organs and in vivo fate of REE NPs after escaping the lysosomes. However, the immunomodulatory effects of intraphagolysosomal dissolved REE NPs remains insufficient. Here, europium oxide (Eu2O3) NPs were pre-incubated with phagolysosomal simulant fluid (PSF) to mimic the biotransformation of europium oxide (p-Eu2O3) NPs under acid phagolysosome conditions. We investigated the alteration in immune cell components and the hematopoiesis disturbance on adult mice after intravenous administration of Eu2O3 NPs and p-Eu2O3 NPs. Our results indicated that the liver and spleen were the main target organs for Eu2O3 NPs and p-Eu2O3 NPs. Eu2O3 NPs had a much higher accumulative potential in organs than p-Eu2O3 NPs. Eu2O3 NPs induced more alterations in immune cells in the spleen, while p-Eu2O3 NPs caused stronger response in the liver. Regarding hematopoietic disruption, Eu2O3 NPs reduced platelets (PLTs) in peripheral blood, which might be related to the inhibited erythrocyte differentiation in the spleen. By contrast, p-Eu2O3 NPs did not cause significant disturbance in peripheral PLTs. Our study demonstrated that the preincubation with PSF led to a distinct response in the immune system compared to the pristine REE NPs, suggesting that the potentially toxic effects induced by the release of NPs after phagocytosis should not be neglected, especially when evaluating the safety of NPs application in vivo.

Association of troponin I and macrophages in cardiac tamponade with Stanford type A aortic dissection

Background

Acute aortic dissection has a high mortality rate, especially for Stanford type A with a dissected ascending aorta. Cardiac tamponade is one of the most common complications of acute type A aortic dissection (ATAAD) and can cause death. However, the pathogenesis is often unclear. We aimed to examine laboratory findings at the onset of disease and macrophage involvement.

Methods

Hematological and biochemical parameters, and D-dimer, brain natriuretic peptide (BNP), and high-sensitivity troponin I (hs-cTnI) levels in 70 patients with ATAAD at our hospital were investigated. Additionally, the myocardium and aorta after autopsy of an ATAAD case with cardiac tamponade were pathologically examined.

Results

Forty-four ATAAD cases were complicated by cardiac tamponade. The mean age of patients with cardiac tamponade and proportion of patients over 70 years of age were both significantly higher than for those without cardiac tamponade. Evaluable D-dimer values were higher than 0.5 μg/mL in all patients. Significantly elevated laboratory parameters in patients with cardiac tamponade included: lactate dehydrogenase, aspartate aminotransferase, C-reactive protein, lactate, BNP, and hs-cTnI. However, multivariate analysis showed only hs-cTnI was significantly associated with cardiac tamponade. Histological examination revealed numerous M2-like macrophages infiltrating the myocardium and dissecting aorta, expressing CC chemokine ligand (CCL)2 together with vascular endothelial growth factor-C and matrix metalloproteinase-9. The peripheral monocyte-to-neutrophil ratio (MNR) was also significantly higher in cardiac tamponade.

Conclusions

In ATAAD patients with cardiac tamponade, hs-cTnI was significantly elevated and CCL2 expression was observed, which may be involved in the expression of M2-like macrophages via an increased MNR.

Hemolysis dictates monocyte differentiation via two distinct pathways in sickle cell disease vaso-occlusion

Sickle cell disease (SCD) is a hereditary hemoglobinopathy characterized by painful vaso-occlusive crises (VOC) and chronic hemolysis. The mononuclear phagocyte system is pivotal to SCD pathophysiology, but the mechanisms governing monocyte/macrophage differentiation remain unknown. This study examined the influence of hemolysis on circulating monocyte trajectories in SCD. We discovered that hemolysis stimulated CSF-1 production, partly by endothelial cells via Nrf2, promoting classical monocyte (CMo) differentiation into blood patrolling monocytes (PMo) in SCD mice. However, hemolysis also upregulated CCL-2 through IFN-I, inducing CMo transmigration and differentiation into tissue monocyte-derived macrophages. Blocking CMo transmigration by anti-P selectin antibody in SCD mice increased circulating PMo, corroborating that CMo-to-tissue macrophage differentiation occurs at the expense of CMo-to-blood PMo differentiation. We observed a positive correlation between plasma CSF-1/CCL-2 ratios and blood PMo levels in patients with SCD, underscoring the clinical significance of these two opposing factors in monocyte differentiation. Combined treatment with CSF-1 and anti-P selectin antibody more effectively increased PMo numbers and reduced stasis compared with single-agent therapies in SCD mice. Altogether, these data indicate that monocyte fates are regulated by the balance between two heme pathways, Nrf2/CSF-1 and IFN-I/CCL-2, and suggest that the CSF-1/CCL-2 ratio may present a diagnostic and therapeutic target in SCD.

The prospective outcome of the monkeypox outbreak in 2022 and characterization of monkeypox disease immunobiology

A new threat to global health re-emerged with monkeypox's advent in early 2022. As of November 10, 2022, nearly 80,000 confirmed cases had been reported worldwide, with most of them coming from places where the disease is not common. There were 53 fatalities, with 40 occurring in areas that had never before recorded monkeypox and the remaining 13 appearing in the regions that had previously reported the disease. Preliminary genetic data suggest that the 2022 monkeypox virus is part of the West African clade; the virus can be transmitted from person to person through direct interaction with lesions during sexual activity. It is still unknown if monkeypox can be transmitted via sexual contact or, more particularly, through infected body fluids. This most recent epidemic's reservoir host, or principal carrier, is still a mystery. Rodents found in Africa can be the possible intermediate host. Instead, the CDC has confirmed that there are currently no particular treatments for monkeypox virus infection in 2022; however, antivirals already in the market that are successful against smallpox may mitigate the spread of monkeypox. To protect against the disease, the JYNNEOS (Imvamune or Imvanex) smallpox vaccine can be given. The spread of monkeypox can be slowed through measures such as post-exposure immunization, contact tracing, and improved case diagnosis and isolation. Final Thoughts: The latest monkeypox epidemic is a new hazard during the COVID-19 epidemic. The prevailing condition of the monkeypox epidemic along with coinfection with COVID-19 could pose a serious condition for clinicians that could lead to the global epidemic community in the form of coinfection.

Peripheral Ischemia Imprints Epigenetic Changes in Hematopoietic Stem Cells to Propagate Inflammation and Atherosclerosis

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.

Peripheral Blood Monocytosis Is Associated With Long-Term Disease Severity in Pediatric-Onset Inflammatory Bowel Disease

OBJECTIVES

Peripheral blood monocytosis (PBM) is a marker of increased disease severity in adults with inflammatory bowel diseases (IBDs). We sought to determine whether PBM serves as a prognostic biomarker in patients with pediatric-onset IBD for a more aggressive long-term disease course when followed into adulthood.

METHODS

Patients with pediatric-onset inflammatory bowel disease were identified within an adult tertiary care center, within a consented, prospectively collected natural history disease registry, to compare clinical outcomes between patients with and without PBM from the years 2009 to 2019. Patients demonstrating elevation in PBM at any time defined membership and long-term clinical trajectories were compared with pediatric-onset patients without PBM.

RESULTS

A total of 581 patients with IBD, diagnosed by 18 years of age, were identified for inclusion, of which 440 patients were diagnosed with Crohn disease and 141 with ulcerative colitis. Monocytosis was detected by complete blood cell counts in 40.1% of patients. PBM was associated with steroid and biologic exposure, number of IBD-related surgeries, and increased health care utilization. Multivariate logistic regression analyses, accounting for elevation of inflammatory markers and other values associated with acute disease activity as well as steroid use, showed persistently increased odds of biologic exposure, emergency department visits, and hospitalizations, but not surgeries, after detection of monocytosis.

CONCLUSIONS

Within patients with pediatric-onset IBD, the sub-cohort with PBM had associated worse clinical outcomes and other markers of increased disease severity.

Macrophage membrane biomimetic drug delivery system: for inflammation targeted therapy

In recent years, there have been many exciting developments in the biomedical applications of the macrophage membrane bionic drug delivery system (MM-Bio-DDS). Macrophages, as an important immune cell, are involved in initiating and regulating the specific immune response of the body. Therefore, the inflammatory process related to macrophages is an important goal in the diagnosis and treatment of many diseases. In this review, we first summarise the different methods of preparation, characterisation, release profiles and natural advantages of using macrophages as a drug delivery system (DDS). Second, we introduce the processes of various chronic inflammatory diseases and the role of macrophages in them, specifically clarifying how the MM-Bio-DDS provides a wide and effective treatment for the targeted inflammatory site. Finally, based on the existing research, we propose the application prospect and existing challenges of the MM-Bio-DDS, especially the problems in clinical transformation, to provide new ideas for the development and utilisation of the MM-Bio-DDS in targeted drug delivery for inflammation and the treatment of diseases.

Monkeypox: disease epidemiology, host immunity and clinical interventions

Monkeypox virus (MPXV), which causes disease in humans, has for many years been restricted to the African continent, with only a handful of sporadic cases in other parts of the world. However, unprecedented outbreaks of monkeypox in non-endemic regions have recently taken the world by surprise. In less than 4 months, the number of detected MPXV infections has soared to more than 48,000 cases, recording a total of 13 deaths. In this Review, we discuss the clinical, epidemiological and immunological features of MPXV infections. We also highlight important research questions and new opportunities to tackle the ongoing monkeypox outbreak.

In this Review, Ng and colleagues examine the clinical, epidemiological and immunological aspects of monkeypox virus (MPXV) infections, with a focus on mechanisms of host immunity to MPXV. The authors also consider the unique epidemiological and pathological characteristics of the current non-endemic outbreak of the virus and discuss vaccines, therapeutics and outstanding research questions.

Monocytosis and its association with clonal hematopoiesis in community-dwelling individuals

Monocytosis associates with a higher frequency of CH with spliceosome and multiple gene mutations, but not isolated DNMT3A/TET2/ASXL1.

Few community-based individuals with monocytosis and CH develop myeloid malignancy (among 166 individuals: n = 4 cases including n = 1 CMML).

Monocytosis may occur in numerous inflammatory conditions but is also the defining feature of chronic myelomonocytic leukemia (CMML). Clonal somatic mutations detectable in CMML may occur with aging in otherwise healthy individuals, so-called “clonal hematopoiesis” (CH). We investigated whether the combination of CH and monocytosis would represent an early developmental stage of CMML. We studied community-dwelling individuals with monocytosis (≥1 × 10⁹/L and ≥10% of leukocytes) in the population-based Lifelines cohort (n = 144 676 adults). The prevalence and spectrum of CH were evaluated for individuals ≥60 years with monocytosis (n = 167 [0.8%]), and control subjects 1:3 matched for age and sex (n = 501). Diagnoses of hematological malignancies were retrieved by linkage to the Netherlands Cancer Registry (NCR). Monocyte counts and the prevalence of monocytosis increased with advancing age. Older individuals with monocytosis more frequently carried CH (50.9% vs 35.5%; P < .001). Monocytosis is associated with enrichment of multiple gene mutations (P = .006) and spliceosome mutations (P = .007) but not isolated mutated DNMT3A, TET2, or ASXL1. Persistent monocytosis over 4 years was observed in 30/102 evaluable individuals and associated with a higher prevalence of CH (63%). Myeloid malignancies, including 1 case of CMML, developed in 4 individuals with monocytosis who all carried CH. In conclusion, monocytosis and CH both occur at an older age and do not necessarily reflect clonal monocytic proliferation. In a fraction of older subjects with monocytosis, CH might constitute early clonal dominance in developing malignant myelomonocytic disease. Mutational spectra deviating from age-related CH require attention.

Association Between Peripheral Blood Monocyte Count and Mucosal Healing in Japanese Patients With Ulcerative Colitis

INTRODUCTION

Monocytes play an important role in innate immunity. Some epidemiological evidence indicates an association between peripheral blood monocytes and ulcerative colitis (UC). The association between peripheral blood monocytes and mucosal healing (MH), however, remains unclear. We evaluated this issue in patients with UC.

METHODS

Study subjects consisted of 272 Japanese patients with UC. Monocyte counts were taken in the morning after overnight fasting. Monocyte count was divided into tertiles based on the distribution of values among all study subjects. Information on clinical remission was obtained from medical records. MH was assessed using the Mayo endoscopic subscore.

RESULTS

The mean monocyte count was 360.1 ± 155.3/mm3. Rates of clinical remission, MH, and complete MH were 61.0%, 66.2%, and 27.9%, respectively. High monocyte count was significantly inversely associated with clinical remission, MH, and complete MH (adjusted odds ratio [OR] 0.45 [95% confidence interval [CI]: 0.23-0.89], OR 0.45 [95% CI: 0.23-0.89], and OR 0.48 [95% CI: 0.23-0.97], respectively). Patients were also classified according to C-reactive protein (CRP) levels; in the low CRP group (<0.1 mg/dL), high monocyte count was independently inversely associated with complete MH but not with clinical remission or MH (OR 0.33 [95% CI: 0.10-0.92], P for trend = 0.027). In the high CRP group, there was no association between monocyte count and clinical outcomes.

DISCUSSION

Our findings suggest that peripheral blood monocyte count can be used as a serum supplemental marker for MH in UC patients with low CRP levels.

Silencing Myeloid Netrin-1 Induces Inflammation Resolution and Plaque Regression

Rationale: Therapeutic efforts to decrease atherosclerotic cardiovascular disease risk have focused largely on reducing atherogenic lipoproteins, yet lipid-lowering therapies alone are insufficient to fully regress plaque burden. We postulate that arterial repair requires resolution of a maladaptive immune response and that targeting factors that hinder inflammation resolution will facilitate plaque regression. Objective: The guidance molecule Ntn1 (netrin-1) is secreted by macrophages in atherosclerotic plaques, where it sustains inflammation by enhancing macrophage survival and blocking macrophage emigration. We tested whether silencing Ntn1 in advanced atherosclerosis could resolve arterial inflammation and regress plaques. Methods and Results: To temporally silence Ntn1 in myeloid cells, we generated genetically modified mice in which Ntn1 could be selectively deleted in monocytes and macrophages using a tamoxifen-induced CX3CR1-driven cre recombinase (Ntn1fl/flCx3cr1creERT2+) and littermate control mice (Ntn1fl/flCx3cr1WT). Mice were fed Western diet in the setting of hepatic PCSK9 (proprotein convertase subtilisin/kexin type 9) overexpression to render them atherosclerotic and then treated with tamoxifen to initiate deletion of myeloid Ntn1 (MøΔNtn1) or not in controls (MøWT). Morphometric analyses performed 4 weeks later showed that myeloid Ntn1 silencing reduced plaque burden in the aorta (−50%) and plaque complexity in the aortic root. Monocyte-macrophage tracing experiments revealed lower monocyte recruitment, macrophage retention, and proliferation in MøΔNtn1 compared with MøWT plaques, indicating a restructuring of monocyte-macrophage dynamics in the artery wall upon Ntn1 silencing. Single-cell RNA sequencing of aortic immune cells before and after Ntn1 silencing revealed upregulation of gene pathways involved in macrophage phagocytosis and migration, including the Ccr7 chemokine receptor signaling pathway required for macrophage emigration from plaques and atherosclerosis regression. Additionally, plaques from MøΔNtn1 mice showed hallmarks of inflammation resolution, including higher levels of proresolving macrophages, IL (interleukin)-10, and efferocytosis, as compared to plaques from MøWT mice. Conclusion: Our data show that targeting Ntn1 in advanced atherosclerosis ameliorates atherosclerotic inflammation and promotes plaque regression.

Inherited deficiency of stress granule ZNFX1 in patients with monocytosis and mycobacterial disease

Human inborn errors of IFN-γ underlie mycobacterial disease, due to insufficient IFN-γ production by lymphoid cells, impaired myeloid cell responses to this cytokine, or both. We report four patients from two unrelated kindreds with intermittent monocytosis and mycobacterial disease, including bacillus Calmette-Guérin-osis and disseminated tuberculosis, and without any known inborn error of IFN-γ. The patients are homozygous for ZNFX1 variants (p.S959* and p.E1606Rfs*10) predicted to be loss of function (pLOF). There are no subjects homozygous for pLOF variants in public databases. ZNFX1 is a conserved and broadly expressed helicase, but its biology remains largely unknown. It is thought to act as a viral double-stranded RNA sensor in mice, but these patients do not suffer from severe viral illnesses. We analyze its subcellular localization upon overexpression in A549 and HeLa cell lines and upon stimulation of THP1 and fibroblastic cell lines. We find that this cytoplasmic protein can be recruited to or even induce stress granules. The endogenous ZNFX1 protein in cell lines of the patient homozygous for the p.E1606Rfs*10 variant is truncated, whereas ZNFX1 expression is abolished in cell lines from the patients with the p.S959* variant. Lymphocyte subsets are present at normal frequencies in these patients and produce IFN-γ normally. The hematopoietic and nonhematopoietic cells of the patients tested respond normally to IFN-γ. Our results indicate that human ZNFX1 is associated with stress granules and essential for both monocyte homeostasis and protective immunity to mycobacteria.

Monocytosis Is a Biomarker of Severity in Inflammatory Bowel Disease: Analysis of a 6-Year Prospective Natural History Registry

BACKGROUND

Inflammatory bowel disease (IBD) is associated with alterations of the innate and adaptive immune systems. Monocytes respond to inflammation and infection, yet the relationship between monocytosis and IBD severity is not fully understood. We aimed to characterize the prevalence of monocytosis in IBD and the association between monocytosis and disease severity and IBD-related health care utilization.

METHODS

We used a multiyear, prospectively collected natural history registry to compare patients with IBD with monocytosis to those without monocytosis, among all patients and by disease type.

RESULTS

A total of 1290 patients with IBD (64.1% with Crohn disease; 35.9% with ulcerative colitis) were included (mean age 46.4 years; 52.6% female). Monocytosis was found in 399 (30.9%) of patients with IBD (29.3% with Crohn disease; 33.9% with ulcerative colitis). Monocytosis was significantly associated with abnormal C-reactive protein level and erythrocyte sedimentation rate, anemia, worse quality of life, active disease, and increased exposure to biologics (all P < 0.001). Compared with patients without monocytosis, patients with monocytosis had a 3-fold increase in annual financial health care charges (median: $127,013 vs. $32,925, P < 0.001) and an increased likelihood of hospitalization (adjusted odds ratio [AOR], 4.5; P < 0.001), IBD-related surgery (AOR, 1.9; P = 0.002), and emergency department (ED) use (AOR, 2.8; P < 0.001). Patients with monocytosis had a shorter time to surgery, hospitalization, and ED visit after stratifying by disease activity (all P < 0.05).

CONCLUSIONS

Patients with IBD with monocytosis, regardless of disease type, are at increased risk for worse clinical outcomes, hospitalization, surgery, and ED use. Peripheral monocytosis may represent a routinely available biomarker of a distinct subgroup with severe disease.

ILT4 inhibition prevents TAM- and dysfunctional T cell-mediated immunosuppression and enhances the efficacy of anti-PD-L1 therapy in NSCLC with EGFR activation

Rationale: Immune checkpoint inhibitors (ICIs) against the PD-1/PD-L1 pathway showed limited success in non-small cell lung cancer (NSCLC) patients, especially in those with activating epidermal growth factor receptor (EGFR) mutations. Elucidation of the mechanisms underlying EGFR-mediated tumor immune escape and the development of effective immune therapeutics are urgently needed. Immunoglobulin-like transcript (ILT) 4, a crucial immunosuppressive molecule initially identified in myeloid cells, is enriched in solid tumor cells and promotes the malignant behavior of NSCLC. However, the upstream regulation of ILT4 overexpression and its function in tumor immunity of NSCLC with EGFR activation remains unclear. Methods: ILT4 expression and EGFR phosphorylation in human NSCLC tissues and cell lines were analyzed using immunohistochemistry (IHC), real-time PCR, Western blotting, immunofluorescence, and flow cytometry. The molecular signaling for EGFR-regulated ILT4 expression was investigated using mRNA microarray and The Cancer Genome Atlas (TCGA) database analyses and then confirmed by Western blotting. The regulation of tumor cell proliferation and apoptosis by ILT4 was examined by CCK8 proliferation and apoptosis assays. The impact of ILT4 and PD-L1 on tumor-associated macrophage (TAM) recruitment and polarization was evaluated using Transwell migration assay, flow cytometry, enzyme linked immunosorbent assay (ELISA) and real-time PCR, while their impact on T cell survival and cytotoxicity was analyzed by CFSE proliferation assay, apoptotic assay, flow cytometry, ELISA and cytolytic assay. Tumor immunotherapy models targeting at paired Ig-like receptor B (PIR-B, an ortholog of ILT4 in mouse)/ILT4 and/or PD-L1 were established in C57BL/6 mice inoculated with stable EGFR- overexpressing Lewis lung carcinoma (LLC) cells and in humanized NSG mice inoculated with EGFR mutant, gefitinib-resistant PC9 (PC9-GR) or EGFR-overexpressing wild type H1299 cells. PIR-B and ILT4 inhibition was implemented by infection of specific knockdown lentivirus and PD-L1 was blocked using human/mouse neutralizing antibodies. The tumor growth model was established in NSG mice injected with PIR-B-downregulated LLC cells to evaluate the effect of PIR-B on tumor proliferation. The frequencies and phenotypes of macrophages and T cells in mouse spleens and blood were detected by flow cytometry while those in tumor tissues were determined by IHC and immunofluorescence. Results: We found that ILT4 expression in tumor cells was positively correlated with EGFR phosphorylation in human NSCLC tissues. Using NSCLC cell lines, we demonstrated that ILT4 was upregulated by both tyrosine kinase mutation-induced and epidermal growth factor (EGF)-dependent EGFR activation and subsequent AKT/ERK1/2 phosphorylation. Overexpressed ILT4 in EGFR-activated tumor cells induced TAM recruitment and M2-like polarization, which impaired T cell function. ILT4 also directly inhibited T cell proliferation, cytotoxicity, and IFN-γ expression and secretion. In EGFR-activated cell lines in vitro and in wild-type EGFR-activated C57BL/6 and humanized NSG immunotherapy models in vivo, either ILT4 (PIR-B) or PD-L1 inhibition enhanced anti-tumor immunity and suppressed tumor progression by counteracting TAM- and dysfunctional T cell- induced immuno-suppressive TME; the combined inhibition of both molecules showed the most dramatic tumor retraction. Surprisingly, in EGFR mutant, TKI resistant humanized NSG immunotherapy model, ILT4 inhibition alone rather than in combination with a PD-L1 inhibitor suppressed tumor growth and immune evasion. Conclusions: ILT4 was induced by activation of EGFR-AKT and ERK1/2 signaling in NSCLC cells. Overexpressed ILT4 suppressed tumor immunity by recruiting M2-like TAMs and impairing T cell response, while ILT4 inhibition prevented immunosuppression and tumor promotion. Furthermore, ILT4 inhibition enhanced the efficacy of PD-L1 inhibitor in EGFR wild-type but not in EGFR mutant NSCLC. Our study identified novel mechanisms for EGFR-mediated tumor immune escape, and provided promising immunotherapeutic strategies for patients with EGFR-activated NSCLC.

Early Changes in Circulating Interleukins and Residual Inflammatory Risk After Acute Myocardial Infarction

Fundamento

Pacientes com infarto agudo do miocárdio podem apresentar uma grande área infartada e disfunção ventricular mesmo com trombólise e revascularização precoces.

Objetivo

Investigar o comportamento das citocinas circulantes em pacientes com infarto agudo do miocárdio com supradesnivelamento do segmento ST (IAMCSST) e a relação delas com a função ventricular.

Métodos

No estudo BATTLE-AMI (Avaliação dos Linfócitos Tipos B e T no Infarto Agudo do Miocárdio), os pacientes com IAMCSST foram tratados com uma estratégia farmacoinvasiva. Os níveis de citocinas (IL-1β, IL-4, IL-6, IL-10 e IL-18) no plasma foram testados através de ensaio de imunoadsorção enzimática (ELISA) no início do estudo e após 30 dias. A massa infartada e a fração de ejeção ventricular esquerda (FEVE) foram examinadas por ressonância magnética cardíaca 3-T. Valores de p menores que 0,05 foram considerados significativos.

Resultados

Na comparação com o início do estudo, níveis mais baixos foram detectados para IL-1β (p = 0,028) e IL-18 (p < 0,0001) após 30 dias do IAMCSST, enquanto níveis mais altos foram observados para IL-4 (p = 0,001) e IL-10 (p < 0,0001) no mesmo momento. Em contrapartida, nenhuma mudança foi detectada nos níveis de IL-6 (p = 0,63). Os níveis da proteína C-reativa de alta sensibilidade e de IL-6 se correlacionaram no início do estudo (rho = 0,45, p < 0,0001) e 30 dias após o IAMCSST (rho = 0,29, p = 0,009). No início do estudo, a correlação entre os níveis de IL-6 e FEVE também foi observada (rho = -0,50, p = 0,004).

Conclusões

Durante o primeiro mês pós-infarto agudo do miocárdio, observamos uma melhora significativa no balanço das citocinas pró e anti-inflamatórias, exceto da IL-6. Esses achados sugerem risco inflamatório residual. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)

Myeloproliferative blood cancers as a human neuroinflammation model for development of Alzheimer's disease: evidences and perspectives

Chronic inflammation and involvement of myeloid blood cells are associated with the development of Alzheimer's disease (AD). Chronic inflammation is a highly important driving force for the development and progression of the chronic myeloproliferative blood cancers (MPNs), which are characterized by repeated thrombotic episodes years before MPN-diagnosis, being elicited by elevated erythrocytes, leukocytes, and platelets. Mutations in blood cells, the JAK2V617F and TET2-mutations, contribute to the inflammatory and thrombogenic state. Herein, we discuss the MPNs as a human neuroinflammation model for AD development, taking into account the many shared cellular mechanisms for reduction in cerebral blood, including capillary stalling with plugging of blood cells in the cerebral microcirculation. The therapeutic consequences of an association between MPNs and AD are immense, including reduction in elevated cell counts by interferon-alpha2 or hydroxyurea and targeting the chronic inflammatory state by JAK1-2 inhibitors, e.g., ruxolitinib, in the future treatment of AD.

Analysis of Biochemical Parameters in Children with Chronic Tonsillitis

Chronic tonsillitis are frequent in pediatric pathology with numerous involved risk factors and pathogenic mechanisms. In this study, epidemiological data and biochemical values addressed to inflammation and mineral, lipid and hepatic metabolism were analyzed for 37 children of school age with chronic tonsillitis. We found that in the majority of cases, chronic tonsillitis was associated with increasing number of blood circulating inflammatory cells, high values of transaminases, cholesterol, triglycerides and low values of procalcitonin, C-reactive protein, calcium, vitamin D and serum iron. The results indicated relations of the biochemical profile analyzed with risk factors and systemic mechanisms for initiation and maintenance of chronic tonsillitis, aspects that can be used to optimize the prognosis of chronic tonsillitis in children.

Long-Term Protection of Rhesus Macaques from Zika Virus Reinfection

By the end of the 2016 Zika virus (ZIKV) outbreak, it is estimated that there were up to 100 million infections in the Americas. In approximately one in seven infants born to mothers infected during pregnancy, ZIKV has been linked to microcephaly, developmental delays, or other congenital disorders collectively known as congenital Zika syndrome, as well as Guillain-Barré syndrome, in ZIKV-infected adults. It is a global health priority to develop a vaccine against ZIKV that elicits long-lasting immunity; however, the durability of immunity to ZIKV is unknown. Previous studies in mice and nonhuman primates have been crucial in vaccine development but have not defined the duration of immunity generated by ZIKV infection. In this study, we rechallenged five rhesus macaques with ZIKV 22 to 28 months after a primary ZIKV infection. We show that primary ZIKV infection generates high titers of neutralizing antibodies that protect from detectable plasma viremia following rechallenge and persist for at least 22 to 28 months. While additional longitudinal studies are necessary with longer time frames, this study establishes a new experimentally defined minimal length of protective ZIKV immunity.IMPORTANCE ZIKV emerged as a vector-borne pathogen capable of causing illness in infected adults and congenital birth defects in infants born to mothers infected during pregnancy. Despite the decrease in ZIKV cases since the 2015-2016 epidemic, questions concerning the prevalence and longevity of protective immunity have left vulnerable communities fearful that they may become the center of next ZIKV outbreak. Although preexisting herd immunity in regions of past outbreaks may dampen the potential for future outbreaks to occur, we currently do not know the longevity of protective immunity to ZIKV after a person becomes infected. Here, we establish a new experimentally defined minimal length of protective ZIKV immunity. We show that five rhesus macaques initially infected with ZIKV 22 to 28 months prior to rechallenge elicit a durable immune response that protected from detectable plasma viremia. This study establishes a new minimal length of protective immunity.

Hyperglycemia (high-glucose) decreases L-cysteine and glutathione levels in cultured monocytes and blood of Zucker diabetic rats

L-Cysteine (LC) is an essential precursor of GSH biosynthesis. GSH is a major physiological antioxidant, and its depletion increases oxidative stress. Diabetes is associated with lower blood levels of LC and GSH. The mechanisms leading to a decrease in LC in diabetes are not entirely known. This study reports a significant decrease in LC in human monocytes exposed to high glucose (HG) concentrations as well as in the blood of type 2 diabetic rats. Thus, a significant decrease in the level of LC in response to exposure to HG supports the assertion that uncontrolled hyperglycemia contributes to a reduction of blood levels of LC and GSH seen in diabetic patients. Increased requirement of LC to replace GSH needed to scavenge excess ROS generated by hyperglycemia can result in lower levels of LC and GSH. Animal and human studies report that LC supplementation improves GSH biosynthesis and is beneficial in lowering oxidative stress and insulin resistance. This suggests that hyperglycemia has a direct role in the impairment of LC and GSH homeostasis in diabetes.

TNF, but not hyperinsulinemia or hyperglycemia, is a key driver of obesity-induced monocytosis revealing that inflammatory monocytes correlate with insulin in obese male mice

Inflammation contributes to obesity-related hyperinsulinemia and insulin resistance, which often precede type 2 diabetes. Inflammation is one way that obesity can promote insulin resistance. It is not clear if the extent of obesity, hyperinsulinemia, or hyperglycemia, underpins changes in cellular immunity during diet-induced obesity. In particular, the requirement for obesity or directionality in the relationship between insulin resistance and monocyte characteristics is poorly defined. Inflammatory cytokines such as tumor necrosis factor (TNF) can contribute to insulin resistance. It is unclear if TNF alters monocytosis or specific markers of cellular immunity in the context of obesity. We measured bone marrow and blood monocyte characteristics in WT and TNF-/- mice that were fed obesogenic, high fat (HF) diets. We also used hyperglycemic Akita mice and mice implanted with insulin pellets in order to determine if glucose or insulin were sufficient to alter monocyte characteristics. We found that diet-induced obesity in male mice increased the total number of monocytes in blood, but not in bone marrow. Immature, inflammatory (Ly6Chigh ) monocytes decreased within the bone marrow and increased within peripheral blood of HF-fed mice. We found that neither hyperinsulinemia nor hyperglycemia was sufficient to induce the observed changes in circulating monocytes in the absence of diet-induced obesity. In obese HF-fed mice, antibiotic treatment lowered insulin and insulin resistance, but did not alter circulating monocyte characteristics. Fewer Ly6Chigh monocytes were present within the blood of HF-fed TNF-/- mice in comparison to HF-fed wild-type (WT) mice. The prevalence of immature Ly6Chigh monocytes in the blood correlated with serum insulin and insulin resistance irrespective of the magnitude of adipocyte or adipose tissue hypertrophy in obese mice. These data suggest that diet-induced obesity instigates a TNF-dependent increase in circulating inflammatory monocytes, which predicts increased blood insulin and insulin resistance independently from markers of adiposity or adipose tissue expansion.

Liver segment imaging using monocyte sequestration: a potential tool for fluorescence-guided liver surgery

Background: The accurate determination of liver segment anatomy is essential to perform liver resection without complications and to ensure long-term outcomes after this operation. There are several perioperative methods for segment identification and surgical navigation, such as intraoperative ultrasound, indigo carmine and near-infrared imaging with indocyanine green. The present study experimentally analyzed the usefulness of monocyte sequestration for liver segment labeling and imaging.

Methods: Human monocytes were isolated from peripheral blood and directly or indirectly labeled with calcein or IRDye 800CW. Potential toxicity, labeling stability, and adhesion to ICAM-1 were analyzed in vitro. Monocyte sequestration in the liver microvasculature and liver segment labeling and boundary demarcation were studied using isolated mouse and pig liver perfusion and via intraportal injection in mouse liver tumor models.

Results: The highest monocyte labeling efficiency was achieved using direct labeling with IRDye 800CW. Labeling was stable and did not influence cell viability. The labeled monocytes were highly sequestrated in the liver microvasculature, both after ex vivo perfusion and after injection in vivo , resulting in excellent labeling of selected liver segments and strong segment boundary demarcation. In contrast to results to a normal liver, monocyte sequestration was very low in tumor-associated blood vessels.

Conclusions: The present experimental study shows that sequestration of labeled monocytes after superselective application demarcates the selected liver segment. These results illustrate potential of this technique for surgical navigation during liver surgery.

PARPi Triggers the STING-Dependent Immune Response and Enhances the Therapeutic Efficacy of Immune Checkpoint Blockade Independent of BRCAness

PARP inhibitors (PARPi) have shown remarkable therapeutic efficacy against BRCA1/2-mutant cancers through a synthetic lethal interaction. PARPi exert their therapeutic effects mainly through the blockade of ssDNA damage repair, which leads to the accumulation of toxic DNA double-strand breaks specifically in cancer cells with DNA repair deficiency (BCRAness), including those harboring BRCA1/2 mutations. Here we show that PARPi-mediated modulation of the immune response contributes to their therapeutic effects independently of BRCA1/2 mutations. PARPi promoted accumulation of cytosolic DNA fragments because of unresolved DNA lesions, which in turn activated the DNA-sensing cGAS-STING pathway and stimulated production of type I IFNs to induce antitumor immunity independent of BRCAness. These effects of PARPi were further enhanced by immune checkpoint blockade. Overall, these results provide a mechanistic rationale for using PARPi as immunomodulatory agents to harness the therapeutic efficacy of immune checkpoint blockade. SIGNIFICANCE: This work uncovers the mechanism behind the clinical efficacy of PARPi in patients with both BRCA-wild-type and BRCA-mutant tumors and provides a rationale for combining PARPi with immunotherapy in patients with cancer.

The roles of mechanotransduction, vascular wall cells, and blood cells in atheroma induction

BACKGROUND

This paper describes and analyzes the cellular and molecular mechanisms underlying atherosclerosis development. In particular, the roles of monocytes/macrophages, smooth muscle cells, and vascular endothelium in the formation of stable/unstable atheromatous plaques, and the contributions of some processes to atheroma formation.

METHODS AND RESULTS

In this study we analyzed endothelium: function, dysfunction, and involvement into atherogenesis; cell proteins mediating mechanotransduction; proatherogenic role of monocytes; the role of macrophages in the development of unstable atheromatous plaques and smooth muscle cell origin in atherosclerosis. Smooth muscle cell phenotypic switching; their functioning; the ability to retain cholesterol and lipoproteins as well as secretion of pro- and anti-inflammatory molecules and extracellular matrix proteins, their response to extracellular stimuli secreted by other cells, and the effect of smooth muscle cells on the cells surrounding atheromatous plaques are fundamentally important for the insight into atherosclerosis molecular basis.

CONCLUSION

Atheromatous plaque transcriptome studies will be helpful in the identification of the key genes involved in atheroma transformation and development as well as discovery of the new targets for diagnosis and therapy.

Mechanisms Underlying Atheroma Induction: The Roles of Mechanotransduction, Vascular Wall Cells, and Blood Cells

BACKGROUND

The objective of this article is to review cellular mechanism of atherosclerosis (AS) development. The pathogenesis of AS comprises a sequence of biological events leading to build up of a dense or loose atheromatous plaque (AP).

METHODS

In this review, we tried to attempt to analyze the cellular mechanisms underlying AS development, including the roles of monocytes/macrophages and smooth muscle cells in the formation of stable/unstable APs.

RESULTS

As a rule, APs are formed in the regions with irregular blood flow; both mechanical perturbations of the vascular wall and several biological events contribute to plaque formation. Blood lipid/lipoprotein deposition, recruitment of monocytes/macrophages, foam cell formation, migration and proliferation of smooth muscle cells, secretion of extracellular matrix, and formation of the connective tissue in plaques are among the latter events.

CONCLUSIONS

The review briefs the contributions of different processes to atheroma formation and describes the molecular mechanisms involved in AS development. AP transcriptome studies will be helpful in the identification of the key genes involved in atheroma transformation and development as well as discovery of the new targets for diagnosis and therapy.

Human Gingiva-Derived Mesenchymal Stem Cells Modulate Monocytes/Macrophages and Alleviate Atherosclerosis

Atherosclerosis is the major cause of cardiovascular diseases. Current evidences indicate that inflammation is involved in the pathogenesis of atherosclerosis. Human gingiva-derived mesenchymal stem cells (GMSC) have shown anti-inflammatory and immunomodulatory effects on autoimmune and inflammatory diseases. However, the function of GMSC in controlling atherosclerosis is far from clear. The present study is aimed to elucidate the role of GMSC in atherosclerosis, examining the inhibition of GMSC on macrophage foam cell formation, and further determining whether GMSC could affect the polarization and activation of macrophages under different conditions. The results show that infusion of GMSC to AopE^−/− mice significantly reduced the frequency of inflammatory monocytes/macrophages and decreased the plaque size and lipid deposition. Additionally, GMSC treatment markedly inhibited macrophage foam cell formation and reduced inflammatory macrophage activation, converting inflammatory macrophages to anti-inflammatory macrophages in vitro. Thus, our study has revealed a significant role of GMSC on modulating inflammatory monocytes/macrophages and alleviating atherosclerosis.

Protective and recuperative effects of 3-bromopyruvate on immunological, hepatic and renal homeostasis in a murine host bearing ascitic lymphoma: Implication of niche dependent differential roles of macrophages

3-bromopyruvate (3-BP) possesses promising antineoplastic potential, however, its effects on immunological homeostasis vis a vis hepatic and renal functions in a tumor bearing host remain unclear. Therefore, the effect of 3-BP administration to a murine host bearing a progressively growing tumor of thymoma origin, designated as Dalton's lymphoma (DL), on immunological, renal and hepatic homeostasis was investigated. Administration of 3-BP (4 mg/kg) to the tumor bearing host reversed tumor growth associated thymic atrophy and splenomegaly, accompanied by altered cell survival and repertoire of splenic, bone marrow and tumor associated macrophages (TAM). TAM displayed augmented phagocytic, tumoricidal activities and production of IL-1 and TNF-α. 3-BP-induced activation of TAM was of indirect nature, mediated by IFN-γ. Blood count of T lymphocytes (CD4⁺ & CD8⁺) and NK cells showed a rise in 3-BP administered tumor bearing mice. Moreover, 3-BP administration triggered modulation of immunomodulatory cytokines in serum along with refurbished hepatic and renal functions. The study indicates the role of altered cytokines balance, site specific differential macrophage functions and myelopoiesis in restoration of lymphoid organ homeostasis in 3-BP administered tumor bearing host. These observations will have long lasting impact in understanding of alternate mechanisms underlying the antitumor action of 3-BP accompanying appraisal of safety issues for optimizing its antineoplastic actions.

Bone Morphogenetic Proteins in Vascular Homeostasis and Disease

It is well established that control of vascular morphogenesis and homeostasis is regulated by vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), Delta-like 4 (Dll4), angiopoietin, and ephrin signaling. It has become clear that signaling by bone morphogenetic proteins (BMPs), which have a long history of studies in bone and early heart development, are also essential for regulating vascular function. Indeed, mutations that cause deregulated BMP signaling are linked to two human vascular diseases, hereditary hemorrhagic telangiectasia and pulmonary arterial hypertension. These observations are corroborated by data obtained with vascular cells in cell culture and in mouse models. BMPs are required for normal endothelial cell differentiation and for venous/arterial and lymphatic specification. In adult life, BMP signaling orchestrates neo-angiogenesis as well as vascular inflammation, remodeling, and calcification responses to shear and oxidative stress. This review emphasizes the pivotal role of BMPs in the vascular system, based on studies of mouse models and human vascular disorders.

Autophagy in Stem Cell Biology: A Perspective on Stem Cell Self-Renewal and Differentiation

Autophagy is a highly conserved cellular process that degrades modified, surplus, or harmful cytoplasmic components by sequestering them in autophagosomes which then fuses with the lysosome for degradation. As a major intracellular degradation and recycling pathway, autophagy is crucial for maintaining cellular homeostasis, as well as for remodeling during normal development. Impairment of this process has been implicated in various diseases, in the pathogenic response to bacterial and viral infections, and in aging. Pluripotent stem cells, with their ability to self-replicate and to give rise to any specialized cell type, are very valuable resources for cell-based medical therapies and open a number of promising avenues for studying human development and disease. It has been suggested that autophagy is vital for the maintenance of cellular homeostasis in stem cells, and subsequently more in-depth knowledge about the regulation of autophagy in stem cell biology has been acquired recently. In this review, we describe the most significant advances in the understanding of autophagy regulation in hematopoietic and mesenchymal stem cells, as well as in induced pluripotent stem cells. In particular, we highlight the roles of various autophagy activities in the regulation of self-renewal and differentiation of these stem cells.

Topiramate modulates post-infarction inflammation primarily by targeting monocytes or macrophages

Aims

Monocytes/macrophages response plays a key role in post-infarction inflammation that contributes greatly to post-infarction ventricular remodelling and cardiac rupture. Therapeutic targeting of the GABAA receptor, which is enriched in monocytes/macrophages but not expressed in the myocardium, may be possible after myocardial infarction (MI).

Methods and results

After MI was induced by ligation of the coronary artery, C57BL/6 mice were intraperitoneally administered with one specific agonist or antagonist of the GABAA receptor (topiramate or bicuculline), in the setting of presence or depletion of monocytes/macrophages. Our data showed that within the first 2 weeks after MI, when monocytes/macrophages dominated, in contrast with bicuculline, topiramate treatment significantly reduced Ly-6Chigh monocyte numbers by regulating splenic monocytopoiesis and promoted foetal derived macrophages preservation and conversion of M1 to M2 or Ly-6Chigh to Ly-6Clow macrophage phenotype in the infarcted heart, though GABAAergic drugs failed to affect M1/M2 or Ly-6Chigh/Ly-6Clow macrophage polarization directly. Accordingly, pro-inflammatory activities mediated by M1 or Ly-6Chigh macrophages were decreased and reparative processes mediated by M2 or Ly-6Clow macrophages were augmented. As a result, post-infarction ventricular remodelling was attenuated, as reflected by reduced infarct size and increased collagen density within infarcts. Echocardiographic indices, mortality and rupture rates were reduced. After depletion of monocytes/macrophages by clodronate liposomes, GABAAergic drugs exhibited no effect on cardiac dysfunction and surrogate clinical outcomes.

Conclusion

Control of the GABAA receptor activity in monocytes/macrophages can potently modulate post-infarction inflammation. Topiramate emerges as a promising drug, which may be feasible to translate for MI therapy in the future.

Applying nanomedicine in maladaptive inflammation and angiogenesis

Inflammation and angiogenesis drive the development and progression of multiple devastating diseases such as atherosclerosis, cancer, rheumatoid arthritis, and inflammatory bowel disease. Though these diseases have very different phenotypic consequences, they possess several common pathophysiological features in which monocyte recruitment, macrophage polarization, and enhanced vascular permeability play critical roles. Thus, developing rational targeting strategies tailored to the different stages of the journey of monocytes, from bone marrow to local lesions, and their extravasation from the vasculature in diseased tissues will advance nanomedicine. The integration of in vivo imaging uniquely allows studying nanoparticle kinetics, accumulation, clearance, and biological activity, at levels ranging from subcellular to an entire organism, and will shed light on the fate of intravenously administered nanomedicines. We anticipate that convergence of nanomedicines, biomedical engineering, and life sciences will help to advance clinically relevant therapeutics and diagnostic agents for patients with chronic inflammatory diseases.

The PSMP-CCR2 interactions trigger monocyte/macrophage-dependent colitis

Monocytes/macrophages have been found to be an important component of colitis. However, the key chemokine that initiates the CCR2⁺ monocytes migration from circulation to colitis tissue remains to be undiscovered. PC3-secreted microprotein (PSMP) is a novel chemokine whose receptor is CCR2. The physiological and pathological functions of PSMP have not yet been reported. In this study, PSMP was found to be expressed in colitis and colonic tumor tissues from patients and significantly up-regulated in mouse DSS-induced colitis tissues. PSMP overexpression in the colon aggravated the DSS-induced colitis and the anti-PSMP neutralizing antibody mollified the colitis by reducing macrophage infiltration and inhibiting the expression of IL-6, TNF-α and CCL2. Furthermore, we demonstrated that lipopolysaccharide and muramyl dipeptide induced PSMP expression in the colonic epithelial cells. PSMP was up-regulated in the initial stage prior to IL-6, TNF-α and CCL2 up-regulated expression in DSS colitis and promoted the M1 macrophages to produce CCL2. PSMP chemo-attracted Ly6C^hi monocytes in a CCR2 dependent manner via in situ chemotaxis and adoptive transfer assays. Our data identify PSMP as a key molecule in ulcerative colitis, which provides a novel mechanism of monocyte/macrophage migration that affects gut innate immunity and makes PSMP a potential target for controlling colitis.

Peripheral monocytosis as a predictive factor for adverse outcome in the emergency department: Survey based on a register study

Monocytosis is associated with chronic infections such as tuberculosis or endocarditis as well as rheumatic and myeloproliferative disorders. Monocytes are also involved in the pathogenesis of atherosclerosis, coronary artery disease, and stroke. The value of monocytosis as a prognostic marker in different diagnostic groups in the emergency setting, however, has not been investigated so far.The aim of the article is to study monocytosis as an outcome factor in the emergency setting.In a Swiss register study, we analyzed monocyte counts in 4238 patients aged >18 years who were admitted to the emergency department of a regional tertiary care hospital. Monocytosis was defined as 0.8×10 cells/L. Diagnoses were grouped into infection, cardiovascular, neurological, metabolic, gastrointestinal, pulmonary, or other. Thirty-day mortality was defined as the primary endpointA total of 1217 patients with monocytosis were identified. Patients with monocytosis at admission suffered more frequently from respiratory symptoms (17.7% vs 8.9%, P <.001) and infection as the final diagnosis (20.8% vs 10.3%, P <.001) while neurological diagnoses were significantly lower in the monocytosis group (15.3% vs 30.9%, P <.001). Patients with monocytosis suffered from more comorbidities such as congestive heart failure, chronic obstructive pulmonary disease, tumor, diabetes, or renal failure but not dementia. When adjusted for age, gender, comorbidities, and main diagnosis, the 30-day mortality (P = .002) and length of stay (P = .001) were significantly higher in patients with monocytosis. The 30-day mortality in patients with monocytosis was most notably influenced by a cardiological diagnosis (odds ratio 3.91).An increased monocyte count predicts adverse outcome in patients admitted to the emergency department. Mechanistic studies will be necessary to specify the potentially detrimental role of monocytosis in critical illness.

Yeast surface display identifies a family of evasins from ticks with novel polyvalent CC chemokine-binding activities

Chemokines function via G-protein coupled receptors in a robust network to recruit immune cells to sites of inflammation. Due to the complexity of this network, targeting single chemokines or receptors has not been successful in inflammatory disease. Dog tick saliva contains polyvalent CC-chemokine binding peptides termed evasins 1 and 4, that efficiently disrupt the chemokine network in models of inflammatory disease. Here we develop yeast surface display as a tool for functionally identifying evasins, and use it to identify 10 novel polyvalent CC-chemokine binding evasin-like peptides from salivary transcriptomes of eight tick species in Rhipicephalus and Amblyomma genera. These evasins have unique binding profiles compared to evasins 1 and 4, targeting CCL2 and CCL13 in addition to other CC-chemokines. Evasin binding leads to neutralisation of chemokine function including that of complex chemokine mixtures, suggesting therapeutic efficacy in inflammatory disease. We propose that yeast surface display is a powerful approach to mine potential therapeutics from inter-species protein interactions that have arisen during evolution of parasitism in ticks.

Monocytes and macrophages in abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a life-threatening disease associated with high morbidity, and high mortality in the event of aortic rupture. Major advances in open surgical and endovascular repair of AAA have been achieved during the past 2 decades. However, drug-based therapies are still lacking, highlighting a real need for better understanding of the molecular and cellular mechanisms involved in AAA formation and progression. The main pathological features of AAA include extracellular matrix remodelling associated with degeneration and loss of vascular smooth muscle cells and accumulation and activation of inflammatory cells. The inflammatory process has a crucial role in AAA and substantially influences many determinants of aortic wall remodelling. In this Review, we focus specifically on the involvement of monocytes and macrophages, summarizing current knowledge on the roles, origin, and functions of these cells in AAA development and its complications. Furthermore, we show and propose that distinct monocyte and macrophage subsets have critical and differential roles in initiation, progression, and healing of the aneurysmal process. On the basis of experimental and clinical studies, we review potential translational applications to detect, assess, and image macrophage subsets in AAA, and discuss the relevance of these applications for clinical practice.

Remnant Cholesterol Elicits Arterial Wall Inflammation and a Multilevel Cellular Immune Response in Humans

OBJECTIVE

Mendelian randomization studies revealed a causal role for remnant cholesterol in cardiovascular disease. Remnant particles accumulate in the arterial wall, potentially propagating local and systemic inflammation. We evaluated the impact of remnant cholesterol on arterial wall inflammation, circulating monocytes, and bone marrow in patients with familial dysbetalipoproteinemia (FD).

APPROACH AND RESULTS

Arterial wall inflammation and bone marrow activity were measured using ¹⁸F-FDG PET/CT. Monocyte phenotype was assessed with flow cytometry. The correlation between remnant levels and hematopoietic activity was validated in the CGPS (Copenhagen General Population Study). We found a 1.2-fold increase of ¹⁸F-FDG uptake in the arterial wall in patients with FD (n=17, age 60±8 years, remnant cholesterol: 3.26 [2.07-5.71]) compared with controls (n=17, age 61±8 years, remnant cholesterol 0.29 [0.27-0.40]; P<0.001). Monocytes from patients with FD showed increased lipid accumulation (lipid-positive monocytes: Patients with FD 92% [86-95], controls 76% [66-81], P=0.001, with an increase in lipid droplets per monocyte), and a higher expression of surface integrins (CD11b, CD11c, and CD18). Patients with FD also exhibited monocytosis and leukocytosis, accompanied by a 1.2-fold increase of ¹⁸F-FDG uptake in bone marrow. In addition, we found a strong correlation between remnant levels and leukocyte counts in the CGPS (n=103 953, P for trend 5×10-276). In vitro experiments substantiated that remnant cholesterol accumulates in human hematopoietic stem and progenitor cells coinciding with myeloid skewing.

CONCLUSIONS

Patients with FD have increased arterial wall and cellular inflammation. These findings imply an important inflammatory component to the atherogenicity of remnant cholesterol, contributing to the increased cardiovascular disease risk in patients with FD.

Mesenchymal Stromal Cells Modulate Monocytes Trafficking in Coxsackievirus B3-Induced Myocarditis

Mesenchymal stromal cell (MSC) application in Coxsackievirus B3 (CVB3)‐induced myocarditis reduces myocardial inflammation and fibrosis, exerts prominent extra‐cardiac immunomodulation, and improves heart function. Although the abovementioned findings demonstrate the benefit of MSC application, the mechanism of the MSC immunomodulatory effects leading to a final cardioprotective outcome in viral myocarditis remains poorly understood. Monocytes are known to be a trigger of myocardial tissue inflammation. The present study aims at investigating the direct effect of MSC on the mobilization and trafficking of monocytes to the heart in CVB3‐induced myocarditis. One day post CVB3 infection, C57BL/6 mice were intravenously injected with 1 x 10⁶ MSC and sacrificed 6 days later for molecular biology and flow cytometry analysis. MSC application reduced the severity of myocarditis, and heart and blood pro‐inflammatory Ly6C^high and Ly6C^middle monocytes, while those were retained in the spleen. Anti‐inflammatory Ly6C^low monocytes increased in the blood, heart, and spleen of MSC‐treated CVB3 mice. CVB3 infection induced splenic myelopoiesis, while MSC application slightly diminished the spleen myelopoietic activity in CVB3 mice. Left ventricular (LV) mRNA expression of the chemokines monocyte chemotactic protein‐1 (MCP)−1, MCP‐3, CCL5, the adhesion molecules intercellular adhesion molecule‐1, vascular cell adhesion molecule‐1, the pro‐inflammatory cytokines interleukin‐6, interleukin‐12, tumor necrosis factor‐α, the pro‐fibrotic transforming growth factorβ1, and circulating MCP‐1 and MCP‐3 levels decreased in CVB3 MSC mice, while LV stromal cell‐derived factor‐1α RNA expression and systemic levels of fractalkine were increased in CVB3 MSC mice. MSC application in CVB3‐induced myocarditis modulates monocytes trafficking to the heart and could be a promising strategy for the resolution of cardiac inflammation and prevention of the disease progression. Stem Cells Translational Medicine2017;6:1249–1261

Chronic, not acute, skin-specific inflammation promotes thrombosis in psoriasis murine models

Background

Psoriasis patients exhibit an increased risk of atherothrombotic events, including myocardial infarction and stroke. Clinical evidence suggests that psoriasis patients with early onset and more severe disease have the highest risk for these co-morbidities, perhaps due to the extent of body surface involvement, subsequent levels of systemic inflammation, or chronicity of disease. We sought to determine whether acute or chronic skin-specific inflammation was sufficient to promote thrombosis.

Methods

We used two experimental mouse models of skin-specific inflammation generated in either an acute (topical Aldara application onto wild-type C57Bl/6 mice for 5 days) or chronic (a genetically engineered K5-IL-17C mouse model of psoriasiform skin inflammation) manner. Arterial thrombosis was induced using carotid artery photochemical injury (Rose Bengal-green light laser) and carotid artery diameters were measured post-clot formation. We also examined measures of clot formation including prothrombin (PT) and activated partial thromboplastin time (aPTT). Skin inflammation was examined histologically and we profiled plasma-derived lipids. The number of skin-draining lymph-node (SDLN) and splenic derived CD11b⁺Ly6C^high pro-inflammatory monocytes and CD11b⁺Ly6G⁺ neutrophils was quantified using multi-color flow cytometry.

Results

Mice treated with topical Aldara for 5 days had similar carotid artery thrombotic occlusion times to mice treated with vehicle cream (32.2 ± 3.0 vs. 31.4 ± 2.5 min, p = 0.97); in contrast, K5-IL-17C mice had accelerated occlusion times compared to littermate controls (15.7 ± 2.1 vs. 26.5 ± 3.5 min, p < 0.01) while carotid artery diameters were similar between all mice. Acanthosis, a surrogate measure of inflammation, was increased in both Aldara-treated and K5-IL-17C mice compared to their respective controls. Monocytosis, defined as elevated SDLN and/or splenic CD11b⁺Ly6C^high cells, was significantly increased in both Aldara-treated (SDLN: 3.8-fold, p = 0.02; spleen: 2.0-fold, p < 0.01) and K5-IL-17C (SDLN: 3.4-fold, p = 0.02; spleen: 3.5-fold, p < 0.01) animals compared to controls while neutrophilia, defined as elevated SDLN and/or splenic CD11b⁺Ly6G⁺ cells, was significantly increased in only the chronic K5-IL-17C model (SDLN: 11.6-fold, p = 0.02; spleen: 11.3-fold, p < 0.01). Plasma-derived lipid levels, PT and aPTT times showed no difference between the Aldara-treated mice or the K5-IL-17C mice and their respective controls.

Conclusions

Chronic, but not acute, skin-specific inflammation was associated with faster arterial thrombotic occlusion. Increased numbers of splenic and SDLN monocytes were observed in both acute and chronic skin-specific inflammation, however, increased splenic and SDLN neutrophils were observed only in the chronic skin-specific inflammation model. Understanding the cellular response to skin-specific inflammation may provide insights into the cellular participants mediating the pathophysiology of major adverse cardiovascular events associated with psoriasis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0738-z) contains supplementary material, which is available to authorized users.

Post-myocardial infarct inflammation and the potential role of cell therapy

Myocardial infarction triggers reparative inflammatory processes programmed to repair damaged tissue. However, often additional injury to the myocardium occurs through the course of this inflammatory process, which ultimately can lead to heart failure. The potential beneficial effects of cell therapy in treating cardiac ischemic disease, the number one cause of death worldwide, are being studied extensively, both in clinical trials using adult stem cells as well as in fundamental research on cardiac stem cells and regenerative biology. This review summarizes the current knowledge on molecular and cellular processes implicated in post-infarction inflammation and discusses the potential beneficial role cell therapy might play in this process. Due to its immunomodulatory properties, the mesenchymal stromal cell is a candidate to reverse the disease progression of the infarcted heart towards heart failure, and therefore is emphasized in this review.

Hybrid nanoparticles improve targeting to inflammatory macrophages through phagocytic signals

Macrophages are innate immune cells with great phenotypic plasticity, which allows them to regulate an array of physiological processes such as host defense, tissue repair, and lipid/lipoprotein metabolism. In this proof-of-principle study, we report that macrophages of the M1 inflammatory phenotype can be selectively targeted by model hybrid lipid-latex (LiLa) nanoparticles bearing phagocytic signals. We demonstrate a simple and robust route to fabricate nanoparticles and then show their efficacy through imaging and drug delivery in inflammatory disease models of atherosclerosis and obesity. Self-assembled LiLa nanoparticles can be modified with a variety of hydrophobic entities such as drug cargos, signaling lipids, and imaging reporters resulting in sub-100nm nanoparticles with low polydispersities. The optimized theranostic LiLa formulation with gadolinium, fluorescein and "eat-me" phagocytic signals (Gd-FITC-LiLa) a) demonstrates high relaxivity that improves magnetic resonance imaging (MRI) sensitivity, b) encapsulates hydrophobic drugs at up to 60% by weight, and c) selectively targets inflammatory M1 macrophages concomitant with controlled release of the payload of anti-inflammatory drug. The mechanism and kinetics of the payload discharge appeared to be phospholipase A2 activity-dependent, as determined by means of intracellular Förster resonance energy transfer (FRET). In vivo, LiLa targets M1 macrophages in a mouse model of atherosclerosis, allowing noninvasive imaging of atherosclerotic plaque by MRI. In the context of obesity, LiLa particles were selectively deposited to M1 macrophages within inflamed adipose tissue, as demonstrated by single-photon intravital imaging in mice. Collectively, our results suggest that phagocytic signals can preferentially target inflammatory macrophages in experimental models of atherosclerosis and obesity, thus opening the possibility of future clinical applications that diagnose/treat these conditions. Tunable LiLa nanoparticles reported here can serve as a model theranostic platform with application in various types of imaging of the diseases such as cardiovascular disorders, obesity, and cancer where macrophages play a pathogenic role.

Nanoparticle uptake by macrophages in vulnerable plaques for atherosclerosis diagnosis

The composition of atherosclerotic (AS) plaques is crucial concerning rupture, thrombosis and clinical events. Two plaque types are distinguished: stable and vulnerable plaques. Vulnerable plaques are rich in inflammatory cells, mostly only M1 macrophages, and are highly susceptible to rupture. These plaques represent a high risk particularly with the standard invasive diagnosis by coronary angiography. So far there are no non-invasive low-risk clinical approaches available to detect and distinguish AS plaque types in vivo. The perspective review introduces a whole work-flow for a novel approach for non-invasive detection and classification of AS plaques using the diffusion reflection method with gold nanoparticle loaded macrophages in combination with flow and image cytometric analysis for quality assurance. Classical biophotonic methods for AS diagnosis are summarized. Phenotyping of monocytes and macrophages are discussed for specific subset labelling by nanomaterials, as well as existing studies and first experimental proofs of concept for the novel approach are shown. In vitro and in vivo detection of NP loaded macrophages (MΦ). Different ways of MΦ labelling include (1) in vitro labelling in suspension (whole blood or buffy coat) or (2) labelling of short-term MΦ cultures with re-injection of MΦ-NP into the animal to detect migration of the cells in the plaques and (3) in vivo injection of NP into the organism.

Monocytes in myocardial infarction

Myocardial infarction (MI) is the leading cause of death in developed countries. Though timely revascularization of the ischemic myocardium and current standard therapy reduce acute mortality after MI, long-term morbidity and mortality remain high. During the first 1 to 2 weeks after MI, tissues in the infarcted myocardium undergo rapid turnover, including digestion of extracellular matrix and fibrosis. Post-MI repair is crucial to survival. Monocytes recruited to the infarcted myocardium remove debris and facilitate the repair process. However, exaggerated inflammation may also impede healing, as demonstrated by the association between elevated white blood cell count and in-hospital mortality after MI. Monocytes produced in the bone marrow and spleen enter the blood after MI and are recruited to the injured myocardium in 2 phases. The first phase is dominated by Ly-6c(high) monocytes and the second phase by Ly-6c(low) monocytes. Yet the number of Ly6C(low) monocytes recruited to the infarct is much lower, and Ly6C(high) monocytes can differentiate to Ly6C(low) macrophages in later healing stages. Understanding the signals regulating monocytosis after MI will help design new therapies to facilitate cardiac healing and limit heart failure.