A novel fatty acid analogue triggers CD36-GPR120 interaction and exerts anti-inflammatory action in endotoxemia.

Inflammation is a mediator of a number of chronic pathologies. We synthesized the diethyl (9Z,12Z)-octadeca-9,12-dien-1-ylphosphonate, called NKS3, which decreased lipopolysaccharide (LPS)-induced mRNA upregulation of proinflammatory cytokines (IL-1ß, IL-6 and TNF-α) not only in primary intraperitoneal and lung alveolar macrophages, but also in freshly isolated mice lung slices. The in-silico studies suggested that NKS3, being CD36 agonist, will bind to GPR120. Co-immunoprecipitation and proximity ligation assays demonstrated that NKS3 induced protein-protein interaction of CD36 with GPR120in RAW 264.7 macrophage cell line. Furthermore, NKS3, via GPR120, decreased LPS-induced activation of TAB1/TAK1/JNK pathway and the LPS-induced mRNA expression of inflammatory markers in RAW 264.7 cells. In the acute lung injury model, NKS3 decreased lung fibrosis and inflammatory cytokines (IL-1ß, IL-6 and TNF-α) and nitric oxide (NO) production in broncho-alveolar lavage fluid. NKS3 exerted a protective effect on LPS-induced remodeling of kidney and liver, and reduced circulating IL-1ß, IL-6 and TNF-α concentrations. In a septic shock model, NKS3 gavage decreased significantly the LPS-induced mortality in mice. In the last, NKS3 decreased neuroinflammation in diet-induced obese mice. Altogether, these results suggest that NKS3 is a novel anti-inflammatory agent that could be used, in the future, for the treatment of inflammation-associated pathologies.

Downregulation of Elovl5 promotes breast cancer metastasis through a lipid-droplet accumulation-mediated induction of TGF-ß receptors.

Metastatic breast cancer cannot be cured, and alteration of fatty acid metabolism contributes to tumor progression and metastasis. Here, we were interested in the elongation of very long-chain fatty acids protein 5 (Elovl5) in breast cancer. We observed that breast cancer tumors had a lower expression of Elovl5 than normal breast tissues. Furthermore, low expression of Elovl5 is associated with a worse prognosis in ER+ breast cancer patients. In accordance with this finding, decrease of Elovl5 expression was more pronounced in ER+ breast tumors from patients with metastases in lymph nodes. Although downregulation of Elovl5 expression limited breast cancer cell proliferation and cancer progression, suppression of Elovl5 promoted EMT, cell invasion and lung metastases in murine breast cancer models. The loss of Elovl5 expression induced upregulation of TGF-ß receptors mediated by a lipid-droplet accumulation-dependent Smad2 acetylation. As expected, inhibition of TGF-ß receptors restored proliferation and dampened invasion in low Elovl5 expressing cancer cells. Interestingly, the abolition of lipid-droplet formation by inhibition of diacylglycerol acyltransferase activity reversed induction of TGF-ß receptors, cell invasion, and lung metastasis triggered by Elovl5 knockdown. Altogether, we showed that Elovl5 is involved in metastasis through lipid droplets-regulated TGF-ß receptor expression and is a predictive biomarker of metastatic ER+ breast cancer.

High lipoprotein(a) levels predict severity of coronary artery disease in patients hospitalized for acute myocardial infarction. Data from the French RICO survey.

BACKGROUND: Lipoprotein(a) (Lp(a)) is a well-recognized independent risk factor for atherosclerotic cardiovascular disease (ASCVD). However, limited data are available on the relationship between coronary artery disease (CAD) burden and Lp(a) levels in patients with acute myocardial infarction (MI). OBJECTIVE: The objective of this study was to assess the severity of CAD according to Lp(a) levels from a French regional registry of acute MI. METHODS: CAD burden was assessed in 1213 consecutive patients hospitalized for acute MI in 2019-2020 who underwent coronary angiography. Patients were compared according to their Lp(a) levels: <50 mg/dL (normal), ≥50 mg/dL and ≤100 mg/dL (high) and >100 mg/dL (very high). RESULTS: The prevalence of high and very high Lp(a) was 13% and 6%, respectively. Median age, and rates of diabetes and smoking were similar in all groups. Patients with high or very high Lp(a) were more often under statin therapy, their corrected LDL-cholesterol levels were lower and previous ASCVD rates higher. When compared with lower levels, patients with very high Lp(a) levels had more elevated SYNTAX scores and more frequent multivessel disease. By multivariate logistic regression analysis, the odd ratio for the estimate of multivessel disease was the highest for patients with Lp(a) >100 mg/dL. Moreover, there was a gradual increase in the number of in-hospital deaths across the three Lp(a) groups (p=0.028). CONCLUSIONS: In real-world patients hospitalized for acute MI in France, very high Lp(a) levels are independently associated with a severe CAD burden, supporting the need for systematic screening of Lp(a) in these patients.

Cholesterol and HIF-1α: Dangerous Liaisons in Atherosclerosis.

HIF-1α exerts both detrimental and beneficial actions in atherosclerosis. While there is evidence that HIF-1α could be pro-atherogenic within the atheromatous plaque, experimental models of atherosclerosis suggest a more complex role that depends on the cell type expressing HIF-1α. In atheroma plaques, HIF-1α is stabilized by local hypoxic conditions and by the lipid microenvironment. Macrophage exposure to oxidized LDLs (oxLDLs) or to necrotic plaque debris enriched with oxysterols induces HIF-1α -dependent pathways. Moreover, HIF-1α is involved in many oxLDL-induced effects in macrophages including inflammatory response, angiogenesis and metabolic reprogramming. OxLDLs activate toll-like receptor signaling pathways to promote HIF-1α stabilization. OxLDLs and oxysterols also induce NADPH oxidases and reactive oxygen species production, which subsequently leads to HIF-1α stabilization. Finally, recent investigations revealed that the activation of liver X receptor, an oxysterol nuclear receptor, results in an increase in HIF-1α transcriptional activity. Reciprocally, HIF-1α signaling promotes triglycerides and cholesterol accumulation in macrophages. Hypoxia and HIF-1α increase the uptake of oxLDLs, promote cholesterol and triglyceride synthesis and decrease cholesterol efflux. In conclusion, the impact of HIF-1α on cholesterol homeostasis within macrophages and the feedback activation of the inflammatory response by oxysterols via HIF-1α could play a deleterious role in atherosclerosis. In this context, studies aimed at understanding the specific mechanisms leading to HIF-1α activation within the plaque represents a promising field for research investigations and a path toward development of novel therapies.

The expanding role of lyso-phosphatidylcholine acyltransferase-3 (LPCAT3), a phospholipid remodeling enzyme, in health and disease.

PURPOSE OF REVIEW: The turnover of fatty acids (FAs) at the sn-2 position of phospholipids is mediated by the reciprocal actions of phospholipases A2 and lyso-PL acyltransferases (LPLAT). LPCAT3, a major LPLAT isoform, exhibits a strong specificity for polyunsaturated FAs s (PUFAs). Although the enzyme was originally studied in the context of cardiometabolism, recent investigations have shed light on the role of LPCAT3 in other tissues such as skeletal muscle and in unexpected biological processes such as cell death and oncogenesis. RECENT FINDINGS: The three-dimensional structure of LPCAT3 has been elucidated allowing further understanding of the mechanism of the acylation reaction as well as the substrate specificity of the enzyme. In skeletal muscle, LPCAT3-mediated phospholipid remodeling modulates membrane domain clustering and insulin signalingLPCAT3 plays an important role in the process of ferroptosis by modulating the PUFA content of phospholipids and possibly of plasmalogens.In tumor-associated macrophages, LPCAT3 can prevent ER stress induced by the tumor microenvironment and may equally modulate antitumor immunity. SUMMARY: LPCAT3 is an attractive therapeutic target in the cardiometabolic disorders. Nevertheless, the involvement of LPCAT3 in processes such as cell death and oncogenesis demands caution with respect to the potential deleterious effects of enzyme modulation.

Leukocyte cell population data in patients with cardiac surgery and cardiopulmonary bypass: A potential readily available tool to monitor immunity.

Purpose: Cardiac surgery with cardiopulmonary bypass triggers sterile inflammation that is responsible for post-operative morbidity. Automated flow cytometry devices used for leucocyte count provide cell population data (CPD) regarding fluorescence intensity, size and granularity of leukocytes that have never been studied in the context of sterile inflammation. Our objective was to explore leukocyte cell population data in patients undergoing cardiac surgery with cardiopulmonary bypass in order to determine whether CPD could be used to monitor immune cell activation. Methods: This is an ancillary study of a cohort of patients undergoing cardiac surgery with cardiopulmonary bypass. Cell population data (CPD) extracted from a routine automated flow cytometer were analyzed (Fluorescence targeted to nucleic acids). The time points of interest were: pre-operative, postoperative and 5 days after surgery. The variations in those parameters were studied. Data were then compared between patients according to the occurrence of a composite criteria (supra-ventricular arrythmia, stroke, acute renal failure, and/or death). Results: Data from 1453 patients were analyzed. The neutrophil count, fluorescence granularity (NE-SCC), intensity (NE-SFL) and size (NE-FSC) increased with surgery. Heterogeneity of neutrophils decreased in terms of fluorescence granularity (NE-WX) and size (NE-WZ) but increased in terms of intensity (NE-WY). The lymphocyte count decreased with surgery. While fluorescence granularity (LY-X) and size increased (LY-Z), Lymphocyte intensity decreased (LY-Y). Lymphocytes were less heterogeneous in terms of their granularity, size and intensity after surgery (LY-WX, LY-WY, LY-WZ). Patients who developed the composite complication criteria had a higher pre-operative neutrophil count (5.08 [3.89;6.95] vs 4.76 [3.60;6.13], p = 0.02; AUC = 0.56 [0.51;0.60]), and more heterogeneous neutrophils in terms of fluorescence granularity (NE-WX, AUC = 0.57 [0.52;0.62]) and intensity (NE-WY, AUC 0.61 [0.56;0.65]). Those patients also had lower pre-operative lymphocyte count (1.49 [1.10;1.14] vs 1.81 [1.39;2.39], p<0.01, AUC = 0.61 [0.57;0.66]) and fluorescence granularity (LY-X, AUC = 0.57 [0.53;0.62]). NE-WX, NE-WY and LY-X were associated with post-operative complications after adjustment on the EuroSCORE 2 (adjusted odd ratio of 1.01 [1.00;1.02]; 1.01 [1.00;1.01] and 1.08 [1.02;1.15] respectively). Conclusion: Cardiac surgery with cardiopulmonary bypass was associated with substantial alterations of CPD probably reflecting leukocytes activation in sterile inflammation. Pre-operative NE-WX, NE-WY and LY-X biomarkers levels were associated with post-operative complications, independently of the EuroSCORE 2. Such routine, unexploited and low cost parameters might represent useful tools likely to monitor immune function and predict outcomes for patients undergoing cardiac surgery. Our findings requires validation on a larger external cohort.

Tumor-induced reshuffling of lipid composition on the endoplasmic reticulum membrane sustains macrophage survival and pro-tumorigenic activity.

Tumor-associated macrophages (TAMs) display pro-tumorigenic phenotypes for supporting tumor progression in response to microenvironmental cues imposed by tumor and stromal cells. However, the underlying mechanisms by which tumor cells instruct TAM behavior remain elusive. Here, we uncover that tumor-cell-derived glucosylceramide stimulated unconventional endoplasmic reticulum (ER) stress responses by inducing reshuffling of lipid composition and saturation on the ER membrane in macrophages, which induced IRE1-mediated spliced XBP1 production and STAT3 activation. The cooperation of spliced XBP1 and STAT3 reinforced the pro-tumorigenic phenotype and expression of immunosuppressive genes. Ablation of XBP1 expression with genetic manipulation or ameliorating ER stress responses by facilitating LPCAT3-mediated incorporation of unsaturated lipids to the phosphatidylcholine hampered pro-tumorigenic phenotype and survival in TAMs. Together, we uncover the unexpected roles of tumor-cell-produced lipids that simultaneously orchestrate macrophage polarization and survival in tumors via induction of ER stress responses and reveal therapeutic targets for sustaining host antitumor immunity.

Increased Phospholipid Transfer Protein Activity Is Associated With Markers of Enhanced Lipopolysaccharide Clearance in Human During Cardiopulmonary Bypass.

Introduction: Lipopolysaccharide (LPS) is a component of gram-negative bacteria, known for its ability to trigger inflammation. The main pathway of LPS clearance is the reverse lipopolysaccharide transport (RLT), with phospholipid transfer protein (PLTP) and lipoproteins playing central roles in this process in experimental animal models. To date, the relevance of this pathway has never been studied in humans. Cardiac surgery with cardiopulmonary bypass is known to favor LPS digestive translocation. Our objective was to determine whether pre-operative PLTP activity and triglyceride or cholesterol-rich lipoprotein concentrations were associated to LPS concentrations in patients undergoing cardiac surgery with cardiopulmonary bypass. Methods: A post-hoc analysis was conducted on plasma samples obtained from patients recruited in a randomized controlled trial.Total cholesterol, high density lipoprotein cholesterol (HDLc), low density lipoprotein cholesterol (LDLc), triglyceride and PLTP activity were measured before surgery. LPS concentration was measured by mass spectrometry before surgery, at the end of cardiopulmonary bypass and 24 h after admission to the intensive care unit. Results: High PLTP activity was associated with lower LPS concentration but not with inflammation nor post-operative complications. HDLc, LDLc and total cholesterol were not associated with LPS concentration but were lower in patients developing post-operative adverse events. HDLc was negatively associated with inflammation biomarkers (CRP, PCT). Triglyceride concentrations were positively correlated with LPS concentration, PCT and were higher in patients with post-operative complications. Conclusion: Our study supports the role of PLTP in LPS elimination and the relevance of RLT in human. PLTP activity, and not cholesterol rich lipoproteins pool size seemed to be the limiting factor for RLT. PLTP activity was not directly related to post-operative inflammation and adverse events, suggesting that LPS clearance is not the main driver of inflammation in our patients. However, HDLc was associated with lower inflammation and was associated with favorable outcomes, suggesting that HDL beneficial anti-inflammatory effects could be, at least in part independent of LPS clearance.

Brown adipose tissue monocytes support tissue expansion.

Monocytes are part of the mononuclear phagocytic system. Monocytes play a central role during inflammatory conditions and a better understanding of their dynamics might open therapeutic opportunities. In the present study, we focused on the characterization and impact of monocytes on brown adipose tissue (BAT) functions during tissue remodeling. Single-cell RNA sequencing analysis of BAT immune cells uncovered a large diversity in monocyte and macrophage populations. Fate-mapping experiments demonstrated that the BAT macrophage pool requires constant replenishment from monocytes. Using a genetic model of BAT expansion, we found that brown fat monocyte numbers were selectively increased in this scenario. This observation was confirmed using a CCR2-binding radiotracer and positron emission tomography. Importantly, in line with their tissue recruitment, blood monocyte counts were decreased while bone marrow hematopoiesis was not affected. Monocyte depletion prevented brown adipose tissue expansion and altered its architecture. Podoplanin engagement is strictly required for BAT expansion. Together, these data redefine the diversity of immune cells in the BAT and emphasize the role of monocyte recruitment for tissue remodeling.

Regulation of glycolytic genes in human macrophages by oxysterols: a potential role for liver X receptors.

BACKGROUND AND PURPOSE: Subset of macrophages within the atheroma plaque displays a high glucose uptake activity. Nevertheless, the molecular mechanisms and the pathophysiological significance of this high glucose need remain unclear. While the role for hypoxia and hypoxia inducible factor 1α has been demonstrated, the contribution of lipid micro-environment and more specifically oxysterols is yet to be explored. EXPERIMENTAL APPROACH: Human macrophages were conditioned in the presence of homogenates from human carotid plaques, and expression of genes involved in glucose metabolism was quantified. Correlative analyses between gene expression and the oxysterol composition of plaques were performed. KEY RESULTS: Conditioning of human macrophages by plaque homogenates induces expression of several genes involved in glucose uptake and glycolysis including glucose transporter 1 (SLC2A1) and hexokinases 2 and 3 (HK2 and HK3). This activation is significantly correlated to the oxysterol content of the plaque samples and is associated with a significant increase in the glycolytic activity of the cells. Pharmacological inverse agonist of the oxysterol receptor liver X receptor (LXR) partially reverses the induction of glycolysis genes without affecting macrophage glycolytic activity. Chromatin immunoprecipitation analysis confirms the implication of LXR in the regulation of SLC2A1 and HK2 genes. CONCLUSION AND IMPLICATIONS: While our work supports the role of oxysterols and the LXR in the modulation of macrophage metabolism in atheroma plaques, it also highlights some LXR-independent effects of plaques samples. Finally, this study identifies hexokinase 3 as a promising target in the context of atherosclerosis. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc.

Interplay between Liver X Receptor and Hypoxia Inducible Factor 1α Potentiates Interleukin-1ß Production in Human Macrophages.

Low-grade inflammation is constitutive of atherosclerosis, and anti-inflammatory therapy inhibiting interleukin-1ß (IL-1ß) reduces the rate of cardiovascular events. While cholesterol accumulation in atheroma plaque and macrophages is a major driver of the inflammatory process, the role of the LXR cholesterol sensors remains to be clarified. Murine and human macrophages were treated with LXR agonists for 48 h before Toll-like receptor (TLR) stimulation. Unexpectedly, we observe that, among other cytokines, LXR agonists selectively increase IL1B mRNA levels independently of TLR activation. This effect, restricted to human macrophages, is mediated by activation of HIF-1α through LXR. Accordingly, LXR agonists also potentiate other HIF-1α-dependent pathways, such as glycolysis. Treatment of human macrophages with carotid plaque homogenates also leads to induction of IL1B in an LXR-dependent manner. Thus, our work discloses a mechanism by which cholesterol and oxysterols trigger inflammation in atherosclerosis. This suggests perspectives to target IL-1ß production in atherosclerotic patients.

Macrophage fatty acid metabolism and atherosclerosis: The rise of PUFAs.

Among the pathways involved in the regulation of macrophage functions, the metabolism of unsaturated fatty acids is central. Indeed, unsaturated fatty acids act as precursors of bioactive molecules such as prostaglandins, leukotrienes, resolvins and related compounds. As components of phospholipids, they have a pivotal role in cell biology by regulating membrane fluidity and membrane-associated cellular processes. Finally, polyunsaturated fatty acids (PUFAs) are also endowed with ligand properties for numerous membrane or nuclear receptors. Although myeloid cells are dependent on the metabolic context for the uptake of essential FAs, recent studies showed that these cells autonomously handle the synthesis of n-3 and n-6 long chain PUFAs such as arachidonic acid and eicosapentaenoic acid. Moreover, targeting PUFA metabolism in macrophages influences pathological processes, including atherosclerosis, by modulating macrophage functions. Omics evidence also supports a role for macrophage PUFA metabolism in the development of cardiometabolic diseases in humans. Currently, there is a renewed interest in the role of n-3/n-6 PUFAs and their oxygenated derivatives in the onset of atherosclerosis and plaque rupture. Purified n-3 FA supplementation appears as a potential strategy in the treatment and prevention of cardiovascular diseases. In this context, the ability of immune cells to handle and to synthesize very long chain PUFA must absolutely be integrated and better understood.

Healthy adiposity and extended lifespan in obese mice fed a diet supplemented with a polyphenol-rich plant extract.

Obesity may not be consistently associated with metabolic disorders and mortality later in life, prompting exploration of the challenging concept of healthy obesity. Here, the consumption of a high-fat/high-sucrose (HF/HS) diet produces hyperglycaemia and hypercholesterolaemia, increases oxidative stress, increases endotoxaemia, expands adipose tissue (with enlarged adipocytes, enhanced macrophage infiltration and the accumulation of cholesterol and oxysterols), and reduces the median lifespan of obese mice. Despite the persistence of obesity, supplementation with a polyphenol-rich plant extract (PRPE) improves plasma lipid levels and endotoxaemia, prevents macrophage recruitment to adipose tissues, reduces adipose accumulation of cholesterol and cholesterol oxides, and extends the median lifespan. PRPE drives the normalization of the HF/HS-mediated functional enrichment of genes associated with immunity and inflammation (in particular the response to lipopolysaccharides). The long-term limitation of immune cell infiltration in adipose tissue by PRPE increases the lifespan through a mechanism independent of body weight and fat storage and constitutes the hallmark of a healthy adiposity trait.

LPCAT3 deficiency in hematopoietic cells alters cholesterol and phospholipid homeostasis and promotes atherosclerosis.

BACKGROUND AND AIMS: LPCAT3 plays a major role in phospholipid metabolism in the liver and intestine. However, the impact of LPCAT3 on hematopoietic cell and macrophage functions has yet to be described. Our aim was to understand the functions of LPCAT3 in macrophages and to investigate whether LPCAT3 deficiency in hematopoietic cells may affect atherosclerosis development. METHODS: Mice with constitutive Lpcat3 deficiency (Lpcat3-/-) were generated. We used fetal hematopoietic liver cells to generate WT and Lpcat3-/- macrophages in vitro and to perform hematopoietic cell transplantation in recipient Ldlr-/- mice. RESULTS: Lpcat3-deficient macrophages displayed major reductions in the arachidonate content of phosphatidylcholines, phosphatidylethanolamines and, unexpectedly, plasmalogens. These changes were associated with altered cholesterol homeostasis, including an increase in the ratio of free to esterified cholesterol and a reduction in cholesterol efflux in Lpcat3-/- macrophages. This correlated with the inhibition of some LXR-regulated pathways, related to altered cellular availability of the arachidonic acid. Indeed, LPCAT3 deficiency was associated with decreased Abca1, Abcg1 and ApoE mRNA levels in fetal liver cells derived macrophages. In vivo, these changes translated into a significant increase in atherosclerotic lesions in Ldlr-/- mice with hematopoietic LPCAT3 deficiency. CONCLUSIONS: This study identifies LPCAT3 as a key factor in the control of phospholipid homeostasis and arachidonate availability in myeloid cells and underlines a new role for LPCAT3 in plasmalogen metabolism. Moreover, our work strengthens the link between phospholipid and sterol metabolism in hematopoietic cells, with significant consequences on nuclear receptor-regulated pathways and atherosclerosis development.

Fatty acid metabolism in macrophages: a target in cardio-metabolic diseases.

PURPOSE OF REVIEW: Recent studies have highlighted that macrophages dynamically and autonomously handle all the facets of fatty acid (FA) metabolism including FA oxidation and FA synthesis as well as the synthesis of monounsaturated FAs and long chain n-3 and n-6 polyunsaturated FAs. RECENT FINDINGS: Macrophage M2 polarization is associated with an increase of FA oxidation. However, whether increased FA oxidation simply correlates with or is required for M2 polarization needs to be further evaluated. Macrophage M1 polarization is associated with the activation of FA synthesis, which directly contributes to the inflammatory response and affects cholesterol homeostasis and neutral lipid accumulation. Finally, recent evidences suggest that macrophages are able to autonomously produce signaling monounsaturated FAs, such as palmitoleic acid (C16 : 1 n-7), and long chain n-3 and n-6 polyunsaturated FAs, such as arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. This pathway is regulated by liver X receptors and has significant consequences on inflammation and on the FA composition of atheroma plaques. SUMMARY: These studies shed new light on the tight relationship between FA metabolism, macrophage polarization, and M1/M2 macrophage functions. These processes may have major consequences for atherosclerosis pathogenesis as well as other metabolic disorders.

LXR agonist treatment of blastic plasmacytoid dendritic cell neoplasm restores cholesterol efflux and triggers apoptosis.

Blastic plasmacytoid dendritic cell (PDC) neoplasm (BPDCN) is an aggressive hematological malignancy with a poor prognosis that derives from PDCs. No consensus for optimal treatment modalities is available today and the full characterization of this leukemia is still emerging. We identified here a BPDCN-specific transcriptomic profile when compared with those of acute myeloid leukemia and T-acute lymphoblastic leukemia, as well as the transcriptomic signature of primary PDCs. This BPDCN gene signature identified a dysregulation of genes involved in cholesterol homeostasis, some of them being liver X receptor (LXR) target genes. LXR agonist treatment of primary BPDCN cells and BPDCN cell lines restored LXR target gene expression and increased cholesterol efflux via the upregulation of adenosine triphosphate-binding cassette (ABC) transporters, ABCA1 and ABCG1. LXR agonist treatment was responsible for limiting BPDCN cell proliferation and inducing intrinsic apoptotic cell death. LXR activation in BPDCN cells was shown to interfere with 3 signaling pathways associated with leukemic cell survival, namely: NF-κB activation, as well as Akt and STAT5 phosphorylation in response to the BPDCN growth/survival factor interleukin-3. These effects were increased by the stimulation of cholesterol efflux through a lipid acceptor, the apolipoprotein A1. In vivo experiments using a mouse model of BPDCN cell xenograft revealed a decrease of leukemic cell infiltration and BPDCN-induced cytopenia associated with increased survival after LXR agonist treatment. This demonstrates that cholesterol homeostasis is modified in BPDCN and can be normalized by treatment with LXR agonists which can be proposed as a new therapeutic approach.

Extreme hyperferritinemia in the setting of acute myeloid leukaemia: a case report of hemophagocytic lymphohistiocytosis.

INTRODUCTION: Major hyperferritinemia is a rare feature in clinical laboratories associated with a wide variety of disorders, including hemophagocytic lymphohistiocytosis (HLH). The diagnosis of HLH is based on clinical and biological criteria, such as those proposed by the Histiocyte Society. However, several of these criteria are not relevant in the specific setting of hematologic malignancies. MATERIALS AND METHODS: A 69-year-old male was treated for an acute myeloid leukaemia. On day 15 after the start of chemotherapy, he developed severe sepsis with high fever, low blood pressure and hepatosplenomegaly. RESULTS: Blood tests were marked by extreme hyperferritinemia (191,000 µg/L, reference range: 26-388 µg/L) with increased C-reactive protein (87.0 mg/L) and procalcitonin (1.94 µg/L) and aspartate aminotransferase (499 U/L 37 °C) in the setting of chemotherapy-induced aplasia. This unusual extreme ferritinemia led to suspect HLH triggered by an invasive infection. Under intensive treatment, the clinical status improved and ferritin levels significantly decreased. CONCLUSIONS: The diagnosis of HLH is usually based on clinical and biological criteria, mainly fever, splenomegaly, cytopenias, hypertriglyceridemia, hypofibrinogenemia, hemophagocytosis and hyperferritinemia. In this patient, the diagnosis of HLH was challenging because several criteria, such as hypertriglyceridemia, hemophagocytosis and hypofibrinogenemia, were absent. In addition, some criteria of HLH are not relevant in the setting of hematologic malignancy, in which fever, splenomegaly, cytopenias and elevated lactate dehydrogenase are commonly observed independently of HLH. This unusual case of extremely high ferritinemia emphasizes the important weight of the ferritin level for the diagnosis of HLH in adult patients in the setting of hematologic malignancies.

Diagnostic Accuracy of Inflammatory Markers As Early Predictors of Infection After Elective Colorectal Surgery: Results From the IMACORS Study.

BACKGROUND: Intra-abdominal infections are frequent and life-threatening complications after colorectal surgery. An early detection could diminish their clinical impact and permit safe early discharge. OBJECTIVE: This study aimed to find the most accurate marker for the detection of postoperative intra-abdominal infection and the appropriate moment to measure it. METHODS: A prospective, observational study was conducted in 3 centers. Consecutive patients undergoing elective colorectal surgery with anastomosis were included. C-reactive protein and procalcitonin were measured daily until the fourth postoperative day. Postoperative infections were recorded according to the definitions of the Centres for Diseases Control. The areas under the receiver operating characteristic curve were analyzed and compared to assess the diagnostic accuracy of each marker. RESULTS: Five-hundred and one patients were analyzed. The incidence of intra-abdominal infection was 11.8%, with 24.6% of patients presenting at least one infectious complication. Overall mortality was 1.2%. At the fourth postoperative day, C-reactive protein was more discriminating than procalcitonin for the detection of intra-abdominal infection (areas under the ROC curve: 0.775 vs 0.689, respectively, P = 0.03). Procalcitonin levels showed wide dispersion. For the detection of all infectious complications, C-reactive protein was also significantly more accurate than procalcitonin on the fourth postoperative day (areas under the ROC curve: 0.783 vs 0.671, P = 0.0002). CONCLUSIONS: C-reactive protein is more accurate than procalcitonin for the detection of infectious complications and should be systematically measured at the fourth postoperative day. It is a useful tool to ensure a safe early discharge after elective colorectal surgery.