Receptor CD36 Research Articles

Clearance of Neutrophils From ICH-Affected Brain by Macrophages Is Beneficial and Is Assisted by Lactoferrin and CD91.

Within hours after intracerebral hemorrhage (ICH) onset, masses of polymorphonuclear neutrophils (PMNs) infiltrate the ICH-affected brain. After degranulation involving controlled release of many toxic antimicrobial molecules, the PMNs undergo rapid apoptosis and then are removed by phagocytic microglia/macrophages (MΦ) through a process called efferocytosis. Effective removal of PMNs may limit secondary brain damage and inflammation; however, the molecular mechanisms governing these cleanup activities are not well understood. We propose that scavenger receptor CD91 on myeloid phagocytes especially in presence of CD91 ligand, LTF (lactoferrin, protein abundant in PMNs), plays an important role in clearance of dead apoptotic PMNs (ANs). Mice/rats were subjected to an autologous blood injection model of ICH. Primary cultured microglia were used to assess phagocytosis of ANs. Immunohistochemistry was employed to assess CD91 expression and PMN infiltration. CD91 knockout mice selectively in myeloid phagocytes (Mac-CD91-KO) were used to establish the CD91/LTF function in phagocytosis and in reducing ICH-induced injury, as assessed using behavioral tests, hematoma resolution, and oxidative stress. Masses of PMNs are found in ICH-affected brain, and they contain LTF. MΦ at the outer border of hematoma are densely packed, expressing CD91 and phagocytosing ANs. Microglia deficient in CD91 demonstrate defective phagocytosis of ANs, and mice deficient in CD91 (Mac-CD91-KO) subjected to ICH injury have increased neurological dysfunction that is associated with impaired hematoma resolution (hemoglobin and iron clearance) and elevated oxidative stress. LTF that normally ameliorates ICH injury in CD91-proficient control mice shows reduced therapeutic effects in Mac-CD91-KO mice. Our study suggests that CD91 plays a beneficial role in improving ANs phagocytosis and ultimately post-ICH outcome and that the beneficial effect of LTF in ICH is in part dependent on presence of CD91 on MΦ.

MONOCYTE‐DERIVED CELLS INVADE AMYLOID PLAQUES IN HUMAN ALZHEIMER’S DISEASE HIPPOCAMPUS

AbstractBackgroundMicroglia, the brain‐resident myeloid cells, play a major role in the immune responses of the nervous system and in the pathogenesis of Alzheimer’s disease (AD). However, the presence of peripheral myeloid cells in the AD brains, and their contribution to disease progression, remain to be demonstrated.MethodCellular (immunostainings and image analysis) and molecular (qPCR and western blots) approaches have been carried out in post‐mortem hippocampal samples from patients with AD (Braak V‐VI) and age‐matched controls without neurological symptoms (Braak II).ResultsOur study provides evidence that circulating monocytes infiltrate the AD brains. Our findings showed that a high proportion of demented individuals was associated with up‐regulation of genes rarely expressed by microglial cells and abundant in monocytes‐derived cells (MDC), among which stands the scavenger receptor Cd163. These Cd163‐positive MDC invaded the brain parenchyma, acquired a microglial‐like morphology, and were located in close proximity to blood vessels. These cells infiltrated the nearby amyloid plaques contributing to plaque‐associated myeloid cell heterogeneity. Besides, control individuals with high amyloid pathology, showed no signs of MDC brain infiltration or plaque invasion. The MDC infiltration was associated with the progression and severity of AD pathology.ConclusionThese results reveal the co‐existence of distinct myeloid populations associated with amyloid plaques during disease progression, as well their region‐specific contribution to neuroimmune protection. The recruitment of monocytes could be a consequence rather than the cause of the severity of the disease. Whether monocyte infiltration is beneficial or detrimental to AD pathology remains to be fully elucidated. These findings open the opportunity to design targeted therapies, not only to microglia, but also to peripheral immune cell population to modulate amyloid pathology and provide a better understanding of the immunological mechanisms underlying AD progression.Supported by ISCiii grants(PI21‐0915 (to AG),PI21‐00914 (to JV) co‐financed by FEDER funds from European Union, by Junta de Andalucia grants P18‐RT‐2233 (to AG) and US‐1262734 (to JV) co‐financed by Programa Operativo FEDER 2014‐2020, and by grant PPIT.UMA.B1‐2019‐07 (to ESM).

Fatty acids are crucial to fuel NK cells upon acute retrovirus infection.

Natural killer (NK) cells are cytotoxic innate immune cells, able to recognize and eliminate virus-infected as well as cancer cells. Metabolic reprogramming is crucial for their activity as they have enhanced energy and nutritional demands for their functions during an infection. Fatty acids (FAs) represent an important source of cellular energy and are essential for proliferation of immune cells. However, the precise role of FAs for NK cells activity in retrovirus infection was unknown. Here we show that activated NK cells increase the expression of the FA uptake receptor CD36 and subsequently the uptake of FAs upon acute virus infection. We found an enhanced flexibility of NK cells to utilize FAs as source of energy compare to naïve NK cells. NK cells that were able to generate energy from FAs showed an augmented target cell killing and increased expression of cytotoxic parameters. However, NK cells that were unable to generate energy from FAs exhibited a severely decreased migratory capacity. Our results demonstrate that NK cells require FAs in order to fight acute virus infection. Susceptibility to severe virus infections as it is shown for people with malnutrition may be augmented by defects in the FA processing machinery, which might be a target to therapeutically boost NK cell functions in the future.

Hemoglobin Receptor CD163 As a Potential Biomarker of Hemolysis Induced Hepatobiliary Injury in Sickle Cell Disease

Sickle cell disease (SCD) associated chronic hemolysis promotes oxidative stress, inflammation and thrombosis leading to organ damage, including liver damage. Hemoglobin scavenger receptor CD163 plays a protective role in SCD by scavenging both hemoglobin-haptoglobin complexes and cell free hemoglobin. A limited number of studies in the past have shown a positive correlation of CD163 expression with poor disease outcomes in patients with SCD. However, the role and regulation of CD163 in SCD related hepatobiliary injury has not been fully elucidated yet. Here, we show that chronic liver injury in SCD mice and patients is associated with elevated levels of hepatic CD163. Hemolysis and increase in hepatic heme, hemoglobin, iron and haptoglobin levels elevate CD163 expression in the SCD mouse liver. Mechanistically we show that HO-1 positively regulates CD163 expression and that HO-1 and NRF2 form a complex with CD163 in the SCD liver. Finally, we demonstrate that blocking CD163 activity promotes hemolysis induced liver injury in SCD. These findings indicate that CD163 is a mediator and a potential biomarker of SCD associated hepatobiliary injury. Understanding the role of HO-1 in CD163 regulation may help identify novel therapeutic targets for hemolysis induced chronic liver injury.

Soluble CD163; A Possible New Biomarker in Multiple Myeloma

INTRODUCTION Tumor associated macrophages (TAM) constitute a major part of the bone marrow microenvironment and play a pivotal role in growth of various hematologic malignancies, such as Multiple Myeloma (MM). Cytokines secreted by TAM, such as hemoglobin scavenger receptor CD163, can be detected in their soluble form (sCD163) and reflect the TAM burden. It was recently published that bone marrow TAMs protect neoplastic plasmacytes from chemotherapy-based apoptosis. In our study, we aimed to investigate the clinical utility of sCD163 in patients with Multiple Myeloma. PATIENTS AND METHODS One hundred and nineteen patients were included in the study of whom 80 had symptomatic MM, 30 appeared to have SMM and 8 had MGUS. Clinical and laboratory characteristics were reviewed, after patients' informed consent form. Their median age was 68 yrs (range, 30-89), 53% were men and 47%women; 39%, 27%, and 35% of MM patients were staged ISS1, ISS2 and ISS3 respectively. Serum sCD163 was tested in frozen sera collected at patients' diagnosis and in 30 healthy individuals (HI) . Measurements were performed by ELISA (Duo-Set R&D Quantiquine) according to the manufacturer's instructions. Median value of variables was used as the cut off point. Median time to treatment (TTT) was 0 months (range,0-248) in MM patients and median overall survival (OS) was 67 months (range, 0-248). Statistical analysis was performed with the SPSS v.26 software. RESULTS Median sCD163 was 26618 pg/ml (11831- 35548) in HI, 24366 pg/ml (13166 - 27429) in MGUS, 27665 (18266-39088) pg/ml in SMM, and 27870 (20720-37478) pg/ml in MM patients.Significantly lower levels of CD163 were observed between MGUS and HI (p=0.001) and HI and MM patients (p=0.015). Shorter time to treatment was observed in all MM patients including SMM with sCD163 levels above median (p = 0.034). Patients who became symptomatic after 6 months of diagnosis were studied separately, with levels above the median indicating a shorter time to therapy (p=0.003). Also, a trend of shorter overall survival was observed in all patients (MM, SMM, MGUS) with levels of CD163 above median (p=0.07). CONCLUSION Our findings reveal that serum sCD163 levels differed in patients with MGUS, SMM, MM, and HI, and could predict TTT in MM, indicating that cells of the monocyte-macrophage lineage may play a role in disease pathophysiology and progression. sCD163 could eventually prove to be a significant prognostic factor in MM.

Reduced in utero substrate supply decreases mitochondrial abundance and alters the expression of metabolic signalling molecules in the fetal sheep heart.

Babies born with fetal growth restriction (FGR) are at higher risk of developing cardiometabolic diseases across the life course. The reduction in substrate supply to the developing fetus that causes FGR not only alters cardiac growth and structure but may have deleterious effects on metabolism and function. Using a sheep model of placental restriction to induce FGR, we investigated key cardiac metabolic and functional markers that may be altered in FGR. We also employed phase-contrast magnetic resonance imaging MRI to assess left ventricular cardiac output (LVCO) as a measure of cardiac function. We hypothesized that signalling molecules involved in cardiac fatty acid utilisation and contractility would be impaired by FGR and that this would have a negative impact on LVCO in the late gestation fetus. Key glucose (GLUT4 protein) and fatty acid (FATP, CD36 gene expression) substrate transporters were significantly reduced in the hearts of FGR fetuses. We also found reduced mitochondrial numbers as well as abundance of electron transport chain complexes (complexes II and IV). These data suggest that FGR diminishes metabolic and mitochondrial capacity in the fetal heart; however, alterations were not correlated with fetal LVCO. Overall, these data show that FGR alters fetal cardiac metabolism in late gestation. If sustained ex utero, this altered metabolic profile may contribute to poor cardiac outcomes in FGR-born individuals after birth. KEY POINTS: Around the time of birth, substrate utilisation in the fetal heart switches from carbohydrates to fatty acids. However, the effect of fetal growth restriction (FGR) on this switch, and thus the ability of the fetal heart to effectively metabolise fatty acids, is not fully understood. Using a sheep model of early onset FGR, we observed significant downregulation in mRNA expression of fatty acid receptors CD36 and FABP in the fetal heart. FGR fetuses also had significantly lower cardiac mitochondrial abundance than controls. There was a reduction in abundance of complexes II and IV within the electron transport chain of the FGR fetal heart, suggesting altered ATP production. This indicates reduced fatty acid metabolism and mitochondrial function in the heart of the FGR fetus, which may have detrimental long-term implications and contribute to increased risk of cardiovascular disease later in life.

Innate immune response to double-stranded RNA in American heritage chicken breeds

Backyard poultry flocks that employ heritage breeds of chicken play a crucial role in the maintenance of poultry pathogens of economic and zoonotic importance. This study examined innate immunity to viral pathogens in heritage chicken breeds using a model of viral double-stranded RNA (dsRNA). Following intraperitoneal injection of high molecular weight (HMW) -poly(I:C)/Lyovec into 4-wk-old chicks, we evaluated gene expression in peripheral blood mononuclear cells (PBMCs) and splenocytes. There was a significant difference across breeds in the expression of IL-4, IL-12p40, IFNγ, and B-cell activating factor (BAFF) in the spleen. In PBMCs, a significant difference in IFN-α expression was seen across breeds. Approximately 57% of IFN-α transcripts in PBMCs was explained by levels of expression of MDA5 transcripts. Using flow cytometry, we showed that only monocytes/macrophages (KUL01+ cells) expressed the scavenger receptor CD163. Regression analysis showed that 42% of fold change in CD163 expression on PBMCs was explained by breed (P < 0.0004). In general, breeds that responded to HMW-poly(I:C) by showing higher upregulation of IFNγ, IL-1β, and IL-12p40 transcripts in the spleen, and higher IFNα transcripts in peripheral blood, expressed less CD163 on blood monocytes. These findings suggest a genetic basis for the response of chickens to double-stranded RNA. Surface expression of the scavenger receptor CD163 in PBMCs following injection of high molecular weight poly(I:C) may be a rapid method to select chickens for breeding based on innate immune response to viral dsRNA.

Clinical utility of circulating TWEAK and CD163 as biomarkers of iron-induced cardiac decompensation in transfusion dependent thalassemia major

Background and aimTumor necrosis factor-like weak inducer of apoptosis (TWEAK) affects most of the cells involved in cardiac fibrosis like inflammatory cells, cardiomyocytes and fibroblasts. CD163, the receptor of TWEAK on the surface of type 2 macrophages, is shed into plasma upon macrophages activation. This work aimed to evaluate serum TWEAK and its decoy receptor CD163 as probable biomarkers to monitor myocardial iron overload (MIO) in transfusion dependent thalassemia major (TDTM) patients and to predict iron-induced cardiac decompensation (IICD). MethodsA total of 140 TDTM patients were enrolled. Patients were categorized into two groups; group I (n = 70) diagnosed with IICD while group II (n = 70) had no evidence of IICD. sTWEAK and sCD163 were quantitated utilizing Enzyme-linked-immunosorbent- assay. ResultssTWEAK was evidently lower in group I than group II (medians, 412 and 1052 pg/mL respectively). sCD163 was higher in group I than group II (medians, 615.5 and 323.5 ng/mL respectively). sTWEAK positively correlated with cardiac MRI-T2 mapping and ventricular ejection fractions and negatively correlated with B-Natriuretic peptide and cardiac troponin. An inverse relationship between TWEAK and CD163 was documented throughout the study. sTWEAK, sCD163 and TWEAK/CD163 ratio proved to be significant predictors of IICD in TDTM patients. TWEAK/CD163 ratio < 1.04 discriminated IICD in TDTM patients with 100 % clinical sensitivity and specificity. ConclusionCirculating TWEAK and CD163 appears to be promising biomarkers for monitoring MIO and predicting IICD in TDTM patients.

The role of CD14 and CSF1R in osteoarthritis and gastritis.

Osteoarthritis (OA) is a non-inflammatory degenerative joint disease that mainly involves articular cartilage damage and involves the whole joint tissue. Gastritis is a common stomach disorder, typically referring to inflammation or lesions of the gastric mucosa. However, the relationship between CD14 and colony stimulating factor-1 receptor (CSF1R) and these 2 diseases is not yet clear. OA datasets GSE46750, GSE82107 and gastritis datasets GSE54043 profiles were downloaded from gene expression omnibus databases generated by GPL10558 and GPL570.The R package limma was used to screen differentially expressed genes (DEGs). Weighted gene co-expression network analysis was performed. The construction and analysis of protein-protein interaction network, functional enrichment analysis, gene set enrichment analysis and comparative toxicogenomics database analysis were performed. TargetScan was used to screen miRNAs regulating central DEGs. A total of 568 DEGs were identified. According to the gene ontology (GO) and biological processes analysis, they were mainly enriched in ATP metabolism negative regulation, toll-like receptor TLR1:TLR2 signaling pathway, and intracellular transport. The enrichment terms for OA and gastritis were similar to the GO and Kyoto encyclopedia of gene and genome enrichment terms of DEGs, mainly enriched in ATP metabolism negative regulation, secretion granules, transmembrane receptor protein kinase activity, cytokine-cytokine receptor interaction, Toll-like receptor signaling pathway, MAPK signaling pathway, and TGF-β signaling pathway. In the Metascape enrichment projects, GO enrichment projects showed functions related to cell-cell receptor interaction, cell secretion, and growth. Two core genes were identified through the construction and analysis of the protein-protein interaction network. The core genes (CD14 and CSF1R) exhibited high expression in OA and gastritis samples and low expression in normal samples. Comparative toxicogenomics database analysis revealed associations between core genes (CD14 and CSF1R) and diseases such as OA, osteoporosis, gastritis, juvenile arthritis, diarrhea, and inflammation. CD14 and CSF1R are highly expressed in OA and gastritis, making them potential therapeutic targets for both diseases.

Nanobodies against porcine CD163 as PRRSV broad inhibitor

PRRSV (Porcine Reproductive and Respiratory Syndrome Virus) is a major swine pathogen causing economic losses. To the date, effective broad PRRSV inhibitory strategies have not been available in practice yet. Targeting the key viral receptor CD163 to block PRRSV entry has emerged as an alternative approach beside vaccines for PRRSV inhibition. As an effective therapeutic tool, nanoantibodies (Nbs) have been widely used in antiviral research. In this study, a phage display VHH library was constructed for the selection of Nbs against porcine CD163 scavenger receptor cysteine-rich 5–9 domain (SRCR5–9). After five rounds of bio-panning and indirect ELISA, seven CD163-specific Nbs (Nb1-Nb7) were identified. All obtained Nbs displayed strong affinity to CD163 receptor and excellent antiviral activity. In particular, Nb2 exhibited significant broad inhibitory effects on variable PRRSV lineages and downregulated virus-related NF-κB signaling. Further studies suggested that Nbs mainly exerted antiviral functions by interfering with virus attachment stage, and also decreased the transcription of CD163. The conformational epitopes recognized by Nbs were localized in the SRCR5 domain of CD163, a crucial region in PRRSV infection. Overall, our findings provide a novel insight into the biofunction of CD163 in antiviral infection and the development of broad-spectrum strategies against PRRSV.

Optimization of Statin-Loaded Delivery Nanoparticles for Treating Chronic Liver Diseases by Targeting Liver Sinusoidal Endothelial Cells.

In this study, we developed functionalized polymeric micelles (FPMs) loaded with simvastatin (FPM-Sim) as a drug delivery system to target liver sinusoidal endothelial cells (LSECs) for preserving liver function in chronic liver disease (CLD). Polymeric micelles (PMs) were functionalized by coupling peptide ligands of LSEC membrane receptors CD32b, CD36 and ITGB3. Functionalization was confirmed via spectroscopy and electron microscopy. In vitro and in vivo FPM-Sim internalization was assessed by means of flow cytometry in LSECs, hepatocytes, Kupffer and hepatic stellate cells from healthy rats. Maximum tolerated dose assays were performed in healthy mice and efficacy studies of FPM-Sim were carried out in bile duct ligation (BDL) and thioacetamide (TAA) induction rat models of cirrhosis. Functionalization with the three peptide ligands resulted in stable formulations with a greater degree of in vivo internalization in LSECs than non-functionalized PMs. Administration of FPM-Sim in BDL rats reduced toxicity relative to free simvastatin, albeit with a moderate portal-pressure-lowering effect. In a less severe model of TAA-induced cirrhosis, treatment with FPM-CD32b-Sim nanoparticles for two weeks significantly decreased portal pressure, which was associated with a reduction in liver fibrosis, lower collagen expression as well as the stimulation of nitric oxide synthesis. In conclusion, CD32b-FPM stands out as a good nanotransporter for drug delivery, targeting LSECs, key inducers of liver injury.

Dual action of macrophage miR-204 confines cyclosporine A-induced atherosclerosis.

Atherosclerosis induced by cyclosporine A (CsA), an inhibitor of the calcineurin/nuclear factor of activated T cells (NFAT) pathway, is a major concern after organ transplantation. However, the atherosclerotic mechanisms of CsA remain obscure. We previously demonstrated that calcineurin/NFAT signalling inhibition contributes to atherogenesis via suppressing microRNA-204 (miR-204) transcription. We therefore hypothesised that miR-204 is involved in the development of CsA-induced atherosclerosis. ApoE-/- mice with macrophage-miR-204 overexpression were generated to determine the effects of miR-204 on CsA-induced atherosclerosis. Luciferase reporter assays and chromatin immunoprecipitation sequencing were performed to explore the targets mediating miR-204 effects. CsA alone did not significantly affect atherosclerotic lesions or serum lipid levels. However, it exacerbated high-fat diet-induced atherosclerosis and hyperlipidemia in C57BL/6J and ApoE-/- mice, respectively. miR-204 levels decreased in circulating monocytes and plaque lesions during CsA-induced atherosclerosis. The upregulation of miR-204 in macrophages inhibited CsA-induced atherosclerotic plaque formation but did not affect serum lipid levels. miR-204 limited the CsA-induced foam cell formation by reducing the expression of the scavenger receptors SR-BII and CD36. SR-BII was post-transcriptionally regulated by mature miR-204-5p via 3'-UTR targeting. Additionally, nuclear-localised miR-204-3p prevented the CsA-induced binding of Ago2 to the CD36 promoter, suppressing CD36 transcription. SR-BII or CD36 expression restoration dampened the beneficial effects of miR-204 on CsA-induced atherosclerosis. Macrophage miR-204 ameliorates CsA-induced atherosclerosis, suggesting that miR-204 may be a potential target for the prevention and treatment of CsA-related atherosclerotic side effects.

A Novel Polysaccharide from Sargassum weizhouense: Extraction Optimization, Structural Characterization, Antiviral and Antioxidant Effects.

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically important pathogens in the global swine industry over the past three decades. There is no licensed antiviral medication that can effectively control this infection. In the present study, the structure of SP-1 isolated and purified from Sargassum weizhouense was analyzed, and its antioxidant capacity and antiviral effect in MARC-145 cells against PRRSV were investigated. The results showed that SP-1 is a novel polysaccharide which mainly is composed of →4)-β-D-ManpA-(1→, →4)-α-L-GulpA-(1→ and a small amount of →4)-β-D-GalpA-(1→. PRRSV adsorption, replication, and release were all suppressed by SP-1. SP-1 therapy down-regulated mRNA expression of the CD163 receptor while increasing the antioxidant gene expression of Nrf2, TXNIP, and HO-1; increasing the protein expression of NQO1 and HO-1; and drastically reducing the protein expression of p-p65. The findings indicated that SP-1 reduces PRRSV adsorption, replication, and release through blocking the expression of the crucial CD163 receptor during infection. Meanwhile, SP-1 exerts antioxidant effects in PRRSV-infected cells through the activation of the Nrf2-HO1 signaling pathway.

Border-associated macrophages promote cerebral amyloid angiopathy and cognitive impairment through vascular oxidative stress

BackgroundCerebral amyloid angiopathy (CAA) is a devastating condition common in patients with Alzheimer’s disease but also observed in the general population. Vascular oxidative stress and neurovascular dysfunction have been implicated in CAA but the cellular source of reactive oxygen species (ROS) and related signaling mechanisms remain unclear. We tested the hypothesis that brain border-associated macrophages (BAM), yolk sac-derived myeloid cells closely apposed to parenchymal and leptomeningeal blood vessels, are the source of radicals through the Aβ-binding innate immunity receptor CD36, leading to neurovascular dysfunction, CAA, and cognitive impairment.MethodsTg2576 mice and WT littermates were transplanted with CD36−/− or CD36+/+ bone marrow at 12-month of age and tested at 15 months. This approach enables the repopulation of perivascular and leptomeningeal compartments with CD36−/− BAM. Neurovascular function was tested in anesthetized mice equipped with a cranial window in which cerebral blood flow was monitored by laser-Doppler flowmetry. Amyloid pathology and cognitive function were also examined.ResultsThe increase in blood flow evoked by whisker stimulation (functional hyperemia) or by endothelial and smooth muscle vasoactivity was markedly attenuated in WT → Tg2576 chimeras but was fully restored in CD36−/− → Tg2576 chimeras, in which BAM ROS production was suppressed. CAA-associated Aβ1-40, but not Aβ1-42, was reduced in CD36−/− → Tg2576 chimeras. Similarly, CAA, but not parenchymal plaques, was reduced in CD36−/− → Tg2576 chimeras. These beneficial vascular effects were associated with cognitive improvement. Finally, CD36−/− mice were able to more efficiently clear exogenous Aβ1-40 injected into the neocortex or the striatum.ConclusionsCD36 deletion in BAM suppresses ROS production and rescues the neurovascular dysfunction and damage induced by Aβ. CD36 deletion in BAM also reduced brain Aβ1-40 and ameliorated CAA without affecting parenchyma plaques. Lack of CD36 enhanced the vascular clearance of exogenous Aβ. Restoration of neurovascular function and attenuation of CAA resulted in a near complete rescue of cognitive function. Collectively, these data implicate brain BAM in the pathogenesis of CAA and raise the possibility that targeting BAM CD36 is beneficial in CAA and other conditions associated with vascular Aβ deposition and damage.Graphical

Immunosuppressive M2 TAMs represent a promising target population to enhance phagocytosis of ovarian cancer cells in vitro.

Tumor-associated macrophages (TAMs) represent an important cell population within the tumor microenvironment, but little is known about the phenotype and function of these cells. The present study aims to characterize macrophages in high-grade serous ovarian cancer (HGSOC). Phenotype and expression of co-regulatory markers were assessed on TAMs derived from malignant ascites (MA) or peripheral blood (PB) by multiparametric flow cytometry. Samples were obtained from HGSOC patients (n=29) and healthy donors (HDs, n=16). Additional expression analysis was performed by RNAseq (n=192). Correlation with clinically relevant parameters was conducted and validated by a second patient cohort (n=517). Finally, the role of TIGIT in repolarization and phagocytosis was investigated in vitro. Expression of the M2-associated receptors CD163, CD204, and CD206, as well as of the co-regulatory receptors TIGIT, CD226, TIM-3, and LAG-3 was significantly more frequent on macrophages in HGSOC than in HDs. CD39 and CD73 were broadly expressed on (mainly M2) macrophages, but without a clear clustering in HGSOC. CD163 mRNA levels were higher in TAMs from patients with residual tumor mass after surgery and associated with a shorter overall survival. In addition, TIGIT expression was associated with a higher tumor grading, indicating a prognostic relevance of M2 infiltration in HGSOC. TIGIT blockade significantly reduced the frequency of M2 macrophages. Moreover, combined blockade of TIGIT and CD47 significantly increased phagocytosis of ovarian cancer cells by TAMs in comparison to a single blockade of CD47. Combined blockade of TIGIT and CD47 represents a promising approach to enhance anti-CD47-facilitated phagocytosis.

LDL binding to cell receptors and extracellular matrix is proatherogenic in obesity but improves after bariatric surgery

Obesity is a major global public health issue involving dyslipidemia, oxidative stress, inflammation, and increased risk of CVD. Weight loss reduces this risk, but the biochemical underpinnings are unclear. We explored how obesity and weight loss after bariatric surgery influence LDL interactions that trigger proatherogenic versus antiatherogenic processes. LDL was isolated from plasma of six patients with severe obesity before (basal) and 6–12 months after bariatric surgery (basal BMI = 42.7 kg/m2; 6-months and 12-months postoperative BMI = 34.1 and 30 kg/m2). Control LDL were from six healthy subjects (BMI = 22.6 kg/m2). LDL binding was quantified by ELISA; LDL size and charge were assessed by chromatography; LDL biochemical composition was determined. Compared to controls, basal LDL showed decreased nonatherogenic binding to LDL receptor, which improved postoperatively. Conversely, basal LDL showed increased binding to scavenger receptors LOX1 and CD36 and to glycosaminoglycans, fibronectin and collagen, which is proatherogenic. One year postoperatively, this binding decreased but remained elevated, consistent with elevated lipid peroxidation. Serum amyloid A and nonesterified fatty acids were elevated in basal and postoperative LDL, indicating obesity-associated inflammation. Aggregated and electronegative LDL remained elevated, suggesting proatherogenic processes. These results suggest that obesity-induced inflammation contributes to harmful LDL alterations that probably increase the risk of CVD. We conclude that in obesity, LDL interactions with cell receptors and extracellular matrix shift in a proatherogenic manner but are partially reversed upon postoperative weight loss. These results help explain why the risk of CVD increases in obesity but decreases upon weight loss.

Alleviating Effects of Ovatodiolide and Antcin K Supplements on High-Fat Diet-Induced Cardiovascular Dysfunction in ApoE-Knockout Mice by Attenuating Oxidative Stress.

A high-fat diet (HFD) is a major risk factor for cardiovascular diseases. Many pure compounds have been demonstrated to be effective in treating cardiovascular diseases. In this study, we investigated the alleviating effects of oral ovatodiolide and antcin K (OAK) supplements on HFD-induced cardiovascular dysfunction in apolipoprotein E (ApoE)-knockout mice. Cardiovascular dysfunction was induced in ApoE-knockout mice by feeding them an HFD for 12 weeks. The degree of cardiovascular dysfunction was assessed through echocardiography, hematological and biochemical analyses, and immunofluorescence and immunohistochemical staining. The HFD-fed mice exhibited cardiovascular dysfunction-abnormal blood biochemical index. The arterial wall tissue exhibited the marked deposition of lipids, upregulated expression of vascular cell adhesion molecule-1 and CD36 receptors, and downregulated expression of the ABCA1 receptor. Macrophages isolated from the peritoneal cavity of the mice exhibited increased levels of lipid accumulation, reactive oxygen species, and CD11b expression but reduced mitochondrial membrane potential. The expression of superoxide dismutase 2 was downregulated and that of tumor necrosis factor-α was upregulated in the myocardial tissue. Oral OAK supplements twice a day for 12 weeks significantly mitigated HFD-induced cardiovascular dysfunction in the experimental mice. Oral OAK supplements appear to be a promising strategy for treating HFD-induced cardiovascular dysfunction. The underlying mechanisms may involve the reduction of lipid accumulation in the artery and oxidative stress and inflammation in the cardiovascular tissue.

Amphipathic Helical Peptide L37pA Protects against Lung Vascular Endothelial Dysfunction Caused by Truncated Oxidized Phospholipids via Antagonism with CD36 Receptor.

The generation of bioactive truncated oxidized phospholipids (Tr-OxPLs) from oxidation of cell-membrane or circulating lipoproteins is a common feature of various pathological states. Scavenger receptor CD36 is involved in lipid transport and acts as a receptor for Tr-OxPLs. Interestingly, Tr-OxPLs and CD36 are involved in endothelial dysfunction-derived acute lung injury, but the precise mechanistic connections remain unexplored. In the present study, we investigated the role of CD36 in mediating pulmonary endothelial cell (EC) dysfunction caused by Tr-OxPLs. Our results demonstrated that the Tr-OxPLs KOdia-PC, Paz-PC, PGPC, PON-PC, POV-PC, and lysophosphocholine caused an acute EC barrier disruption as revealed by measurements of transendothelial electrical resistance and VE-cadherin immunostaining. More importantly, a synthetic amphipathic helical peptide, L37pA, targeting human CD36 strongly attenuated Tr-OxPL-induced EC permeability. L37pA also suppressed Tr-OxPL-induced endothelial inflammatory activation monitored by mRNA expression of inflammatory cytokines/chemokines and adhesion molecules. In addition, L37pA blocked Tr-OxPL-induced NF-κB activation and tyrosine phosphorylation of Src kinase and VE-cadherin. The Src inhibitor SU6656 attenuated KOdia-PC-induced EC permeability and inflammation, but inhibition of the Toll-like receptors (TLRs) TLR1, TLR2, TLR4, and TLR6 had no such protective effects. CD36-knockout mice were more resistant to Tr-OxPL-induced lung injury. Treatment with L37pA was equally effective in ameliorating Tr-OxPL-induced vascular leak and lung inflammation as determined by an Evans blue extravasation assay and total cell and protein content in BAL fluid. Altogether, these results demonstrate an essential role of CD36 in mediating Tr-OxPL-induced EC dysfunction and suggest a strong therapeutic potential of CD36 inhibitory peptides in mitigating lung injury and inflammation.

Macrophage-associated markers of metaflammation are linked to metabolic dysfunction in pediatric obesity

BackgpoundMetabolically driven chronic low-grade adipose tissue inflammation, so-called metaflammation, is a central feature in obesity. This inflammatory tone is largely driven by adipose tissue macrophages (ATM), which express pro- and anti-inflammatory markers and cytokines such as, e.g., IL-1 receptor antagonist (IL-1RA), CD163 and osteopontin (OPN). Metaflammation ultimately leads to the development of cardiometabolic diseases. This study aimed to evaluate the association between selected adipose tissue macrophage-associated markers and metabolic comorbidities in pediatric obesity. MethodsFrom a pediatric cohort with obesity (n = 108), clinically thoroughly characterized including diverse routine blood parameters, oral glucose tolerance test and liver MRI, plasma IL-1RA, soluble (s)CD163 and OPN were measured by ELISA. ResultsWe observed significantly higher IL-1RA, sCD163, and OPN levels in the plasma of children with metabolic-dysfunction associated fatty liver disease (MAFLD) and metabolic syndrome. Moreover, IL-1RA and sCD163 correlated with hepatic disease and apoptosis markers alanine aminotransferase and CK-18. IL-1RA concentrations additionally correlated with insulin resistance, while children with disturbed glucose metabolism had significantly higher levels of sCD163. ConclusionMAFLD and other metabolic disorders in pediatric patients with obesity are associated with an elevation of adipose tissue macrophage-related inflammation markers.

Myeloid cell iron uptake pathways and paramagnetic rim formation in multiple sclerosis

In multiple sclerosis (MS), sustained inflammatory activity can be visualized by iron-sensitive magnetic resonance imaging (MRI) at the edges of chronic lesions. These paramagnetic rim lesions (PRLs) are associated with clinical worsening, although the cell type-specific and molecular pathways of iron uptake and metabolism are not well known. We studied two postmortem cohorts: an exploratory formalin-fixed paraffin-embedded (FFPE) tissue cohort of 18 controls and 24 MS cases and a confirmatory snap-frozen cohort of 6 controls and 14 MS cases. Besides myelin and non-heme iron imaging, the haptoglobin-hemoglobin scavenger receptor CD163, the iron-metabolizing markers HMOX1 and HAMP as well as immune-related markers P2RY12, CD68, C1QA and IL10 were visualized in myeloid cell (MC) subtypes at RNA and protein levels across different MS lesion areas. In addition, we studied PRLs in vivo in a cohort of 98 people with MS (pwMS) via iron-sensitive 3 T MRI and haptoglobin genotyping by PCR. CSF samples were available from 38 pwMS for soluble CD163 (sCD163) protein level measurements by ELISA. In postmortem tissues, we observed that iron uptake was linked to rim-associated C1QA-expressing MC subtypes, characterized by upregulation of CD163, HMOX1, HAMP and, conversely, downregulation of P2RY12. We found that pwMS with ge 4 PRLs had higher sCD163 levels in the CSF than pwMS with le 3 PRLs with sCD163 correlating with the number of PRLs. The number of PRLs was associated with clinical worsening but not with age, sex or haptoglobin genotype of pwMS. However, pwMS with Hp2-1/Hp2-2 haplotypes had higher clinical disability scores than pwMS with Hp1-1. In summary, we observed upregulation of the CD163-HMOX1-HAMP axis in MC subtypes at chronic active lesion rims, suggesting haptoglobin-bound hemoglobin but not transferrin-bound iron as a critical source for MC-associated iron uptake in MS. The correlation of CSF-associated sCD163 with PRL counts in MS highlights the relevance of CD163-mediated iron uptake via haptoglobin-bound hemoglobin. Also, while Hp haplotypes had no noticeable influence on PRL counts, pwMS carriers of a Hp2 allele might have a higher risk to experience clinical worsening.