Iron deficiency activates pro-inflammatory signaling in macrophages and foam cells via the p38 MAPK-NF-κB pathway

Antiferroptosis therapy alleviated the development of atherosclerosis

Ferroptosis has been confirmed to be associated with various diseases, but the relationship between ferroptosis and atherosclerosis (AS) remains unclear. Our research detailly clarified the roles of ferroptosis in three continuous and main pathological stages of AS respectively (injury of endothelial cells [ECs], adhesion of monocytes, and formation of foam cells). We confirmed that oxidized low-density lipoprotein (ox-LDL), the key factor in the pathogenesis of AS, strongly induced ferroptosis in ECs. Inhibition of ferroptosis repressed the adhesion of monocytes to ECs by inhibiting inflammation of ECs. Ferroptosis also participated in the formation of foam cells and lipids by regulating the cholesterol efflux of macrophages. Further research confirmed that ox-LDL repressedthe activity of glutathione peroxidase 4 (GPX4), the classic lipid peroxide scavenger. Treatment of a high-fat diet significantly induced ferroptosis in murine aortas and aortic sinuses, which was accompanied by AS lesions and hyperlipidemia. Treatment with ferroptosis inhibitors significantly reduced ferroptosis, hyperlipidemia, and AS lesion development. In conclusion, our research determined that ox-LDL induced ferroptosis by repressing the activity of GPX4. Antiferroptosis treatment showed promising treatment effects in vivo. Ferroptosis-associated indexes also showed promising diagnostic potential in AS patients.

Ferroptosis mechanisms and regulations in cardiovascular diseases in the past, present, and future

Cardiovascular diseases (CVDs) are the main diseases that endanger human health, and their risk factors contribute to high morbidity and a high rate of hospitalization. Cell death is the most important pathophysiology in CVDs. As one of the cell death mechanisms, ferroptosis is a new form of regulated cell death (RCD) that broadly participates in CVDs (such as myocardial infarction, heart transplantation, atherosclerosis, heart failure, ischaemia/reperfusion (I/R) injury, atrial fibrillation, cardiomyopathy (radiation-induced cardiomyopathy, diabetes cardiomyopathy, sepsis-induced cardiac injury, doxorubicin-induced cardiac injury, iron overload cardiomyopathy, and hypertrophic cardiomyopathy), and pulmonary arterial hypertension), involving in iron regulation, metabolic mechanism and lipid peroxidation. This article reviews recent research on the mechanism and regulation of ferroptosis and its relationship with the occurrence and treatment of CVDs, aiming to provide new ideas and treatment targets for the clinical diagnosis and treatment of CVDs by clarifying the latest progress in CVDs research.

Ferroptosis Involved in Cardiovascular Diseases: Mechanism Exploration of Ferroptosis' Role in Common Pathological Changes

ABSTRACT

Regulated cell death is a controlled form of cell death that protects cells by adaptive responses in pathophysiological states. Ferroptosis has been identified as a novel method of controlling cell death in recent years. Several cardiovascular diseases (CVDs) are shown to be profoundly influenced by ferroptosis, and ferroptosis is directly linked to the majority of cardiovascular pathological alterations. Despite this, it is still unclear how ferroptosis affects the pathogenic alterations that take place in CVDs. Based on a review of the mechanisms that regulate ferroptosis, this review explores the most recent research on the role of ferroptosis in the major pathological changes associated with CVDs, to provide new perspectives and strategies for cardiovascular research and clinical treatment.

Dysmetabolic Iron Overload Syndrome: Going beyond the Traditional Risk Factors Associated with Metabolic Syndrome

Dysmetabolic iron overload syndrome (DIOS) corresponds to the increase in iron stores associated with components of metabolic syndrome (MtS) and in the absence of an identifiable cause of iron excess. The objective of this work was to review the main aspects of DIOS. PUBMED and EMBASE were consulted, and PRISMA guidelines were followed. DIOS is usually asymptomatic and can be diagnosed by investigating MtS and steatosis. About 50% of the patients present altered hepatic biochemical tests (increased levels of γ-glutamyl transpeptidase itself or associated with increased levels of alanine aminotransferase). The liver may present parenchymal and mesenchymal iron overload, but the excess of iron is commonly mild. Steatosis or steatohepatitis is observed in half of the patients. Fibrosis is observed in about 15% of patients. Hyperferritinemia may damage the myocardium, liver, and several other tissues, increasing morbidity and mortality. Furthermore, DIOS is closely related to oxidative stress, which is closely associated with several pathological conditions such as inflammatory diseases, hypertension, diabetes, heart failure, and cancer. DIOS is becoming a relevant finding in the general population and can be associated with high morbidity/mortality. For these reasons, investigation of this condition could be an additional requirement for the early prevention of cardiovascular diseases.

Ironing out macrophages in atherosclerosis

<p indent="0mm">The most common cause of death worldwide is atherosclerosis and related cardiovascular disorders. Macrophages are important players in the pathogenesis of atherosclerosis and perform critical functions in iron homeostasis due to recycling iron by phagocytosis of senescent red blood cells and regulating iron availability in the tissue microenvironment. With the growth of research on the "iron hypothesis" of atherosclerosis, macrophage iron has gradually become a hotspot in the refined iron hypothesis. Macrophages with the M1, M2, M(Hb), Mox, and other phenotypes have been defined with different iron-handling capabilities related to the immune function and immunometabolism of macrophages, which influence the progression of atherosclerosis. In this review, we focus on macrophage iron and its effects on the development of atherosclerosis. We also cover the contradictory discoveries and propose a possible explanation. Finally, pharmaceutical modulation of macrophage iron is discussed as a promising target for atherosclerosis therapy.</p>.

CD147 Mediates 5-Fluorouracil Resistance in Colorectal Cancer by Reprogramming Glycolipid Metabolism

Chemoresistance against 5-fluorouracil (5-FU) is a major issue for colorectal cancer (CRC) patients. Increasing evidence for the roles of CD147 in glycolipid metabolic reprogramming and chemoresistance of tumor cells has emerged in recent years. However, whether CD147 contributes to 5-FU resistance in CRC and the role of abnormal glycolipid metabolism in this process remain poorly understood. We analyzed CD147 expression in primary tumor samples of CRC patients and found that upregulated CD147 correlated with decreased 5-FU chemosensitivity and an unfavorable prognosis of CRC patients. Moreover, in vivo and in vitro experiments confirmed that CD147 regulates glycolipid metabolism through two separate pathways. Mechanistically, CD147 upregulates HIF-1α-mediated glycolysis by activating the PI3K/AKT/mTOR pathway and CD147 also attenuates PPARα-mediated fatty acid oxidation by activation of the MAPK pathway. Most importantly, we found that CD147 confers 5-FU resistance in CRC via these glycolipid metabolic signatures. Our results demonstrated that CD147 is a potential 5-FU resistance biomarker for CRC patients and a candidate therapeutic target to restore 5-FU sensitivity of 5-FU-resistant CRC by remodeling glycolipid metabolism.

Cigarette Smoke Particle-Induced Lung Injury and Iron Homeostasis

It is proposed that the mechanistic basis for non-neoplastic lung injury with cigarette smoking is a disruption of iron homeostasis in cells after exposure to cigarette smoke particle (CSP). Following the complexation and sequestration of intracellular iron by CSP, the host response (eg, inflammation, mucus production, and fibrosis) attempts to reverse a functional metal deficiency. Clinical manifestations of this response can present as respiratory bronchiolitis, desquamative interstitial pneumonitis, pulmonary Langerhans’ cell histiocytosis, asthma, pulmonary hypertension, chronic bronchitis, and pulmonary fibrosis. If the response is unsuccessful, the functional deficiency of iron progresses to irreversible cell death evident in emphysema and bronchiectasis. The subsequent clinical and pathological presentation is a continuum of lung injuries, which overlap and coexist with one another. Designating these non-neoplastic lung injuries after smoking as distinct disease processes fails to recognize shared relationships to each other and ultimately to CSP, as well as the common mechanistic pathway (ie, disruption of iron homeostasis).

NF-κB-dependent induction of porcine β-defensin 114 regulates intestinal epithelium homeostasis

Intestinal epithelial cells (IECs) offer a primary physical barrier against commensal and pathogenic microorganisms in the gastrointestine. However, the influence of IECs on the development and regulation of mucosal immunity to infection is unknown. Here, we show that the porcine β-defensin 114 (PBD114) is an endotoxin-responsive gene expressed in IECs. Analysis on expression profiling of PBD114 gene using an infected porcine model and IPEC-J2 cells unveiled a pattern of induction in response to stimulation of various toll-like receptors (TLRs). By means of promoter analysis, PBD114 was found to be a NF-κB-dependent gene. Importantly, PBD114 suppresses endotoxin-induced inflammation and apoptosis in IECs through downregulation of two critical inflammation-associated signaling proteins, NF-kappa-B inhibitor alpha (IkB-α) and extracellular signal-regulated kinase1/2 (ERK1/2). PBD114 also suppresses inflammation and IEC apoptosis in mice exposed to bacterial endotoxins. Thus, we propose that TLR-activated NF-kB rapidly increases the expression of PBD114 that operates a feedback control of the NF-kB-dependent inflammation. The NF-kB-dependent induction of PBD114 may be a key event through which the mammalian host maintains intestinal epithelium homeostasis in response to various infections or diseases.

Ferroptosis: the potential value target in atherosclerosis

In advanced atherosclerosis (AS), defective function-induced cell death leads to the formation of the characteristic necrotic core and vulnerable plaque. The forms and mechanisms of cell death in AS have recently been elucidated. Among them, ferroptosis, an iron-dependent form of necrosis that is characterized by oxidative damage to phospholipids, promotes AS by accelerating endothelial dysfunction in lipid peroxidation. Moreover, disordered intracellular iron causes damage to macrophages, vascular smooth muscle cells (VSMCs), vascular endothelial cells (VECs), and affects many risk factors or pathologic processes of AS such as disturbances in lipid peroxidation, oxidative stress, inflammation, and dyslipidemia. However, the mechanisms through which ferroptosis initiates the development and progression of AS have not been established. This review explains the possible correlations between AS and ferroptosis, and provides a reliable theoretical basis for future studies on its mechanism.

Transfer of exosomal microRNA-203-3p from dendritic cells to bone marrow-derived macrophages reduces development of atherosclerosis by downregulating Ctss in mice

Dendritic cell-derived exosomes have been proven to be efficient adjuvant options for anti-tumor vaccines in cancer immunotherapy. However, their potency in atherosclerosis remains unclear. Here we summarize the association of microRNA-203-3p (miR-203-3p) with dendritic cell-derived exosomes and atherosclerosis. Firstly, dendritic cell-derived exosomes and bone marrow-derived macrophages were isolated, after which expression of miR-203-3p and cathepsin S was determined. After the establishment of atherosclerosis mouse models, gain- and loss-of-function experiments were conducted for the analysis of effects of miR-203-3p and cathepsin S on foam-cell formation, lipid accumulation, collagen deposition and serum total cholesterol. The results found high expression of cathepsin S in atherosclerosis mice and downregulation of miR-203-3p in the serum of atherosclerosis patients and ox-LDL-simulated bone marrow-derived macrophages. Cathepsin S was the target gene of miR-203-3p. miR-203-3p transporting from exosomes to bone marrow-derived macrophages resulted in inhibition of cathepsin S expression and atherosclerosis-related phenotypes in bone marrow-derived macrophages, thus alleviating atherosclerosis in mice, and this process was found to involve the p38/MAPK signaling pathway. These findings provided evidence that the transfer of miR-203-3p by dendritic cell-derived exosomes targeted cathepsin S in bone marrow-derived macrophages to attenuate atherosclerosis progression in mice, serving as a promising clinical target for atherosclerosis.

Air pollutants disrupt iron homeostasis to impact oxidant generation, biological effects, and tissue injury

Air pollutants cause changes in iron homeostasis through: 1) a capacity of the pollutant, or a metabolite(s), to complex/chelate iron from pivotal sites in the cell or 2) an ability of the pollutant to displace iron from pivotal sites in the cell. Through either pathway of disruption in iron homeostasis, metal previously employed in essential cell processes is sequestered after air pollutant exposure. An absolute or functional cell iron deficiency results. If enough iron is lost or is otherwise not available within the cell, cell death ensues. However, prior to death, exposed cells will attempt to reverse the loss of requisite metal. This response of the cell includes increased expression of metal importers (e.g. divalent metal transporter 1). Oxidant generation after exposure to air pollutants includes superoxide production which functions in ferrireduction necessary for cell iron import. Activation of kinases and phosphatases and transcription factors and increased release of pro-inflammatory mediators also result from a cell iron deficiency, absolute or functional, after exposure to air pollutants. Finally, air pollutant exposure culminates in the development of inflammation and fibrosis which is a tissue response to the iron deficiency challenging cell survival. Following the response of increased expression of importers and ferrireduction, activation of kinases and phosphatases and transcription factors, release of pro-inflammatory mediators, and inflammation and fibrosis, cell iron is altered, and a new metal homeostasis is established. This new metal homeostasis includes increased total iron concentrations in cells with metal now at levels sufficient to meet requirements for continued function.

Dynamics of the Physicochemical Characteristics, Microbiota, and Metabolic Functions of Soybean Meal and Corn Mixed Substrates during Two-Stage Solid-State Fermentation

Solid-state fermentation (SSF) plays pivotal roles not only in human food but also farm animal diets. Soybean meal (SBM) and corn account for approximately 70% of the global feed consumption. However, the nutritional value of conventional SBM and corn mixed substrates (MS) is limited by antinutritional factors, causing substantial economic loss in livestock production. Although emerging studies have reported that SSF can improve the nutritional value of SBM-based substrates, the dynamic changes in the physicochemical features, microbiota, and metabolic functions of MS during SSF remain poorly understood, limiting further investigation. To provide insights into the dynamics of the physicochemical characteristics and the complex microbiome during the two-stage SSF of MS, multiple physicochemical analyses combined with high-throughput sequencing were applied here. These novel insights shed light on the complex changes that occur in the nutrition and microbiome during two-stage SSF of MS and are of great value for industrial feed-based practices and metabolomic research on SSF ecosystems.

Substantial annual economic loss in livestock production is caused by antinutritional factors in soybean meal and corn mixed substrates, which can be degraded by microbial fermentation. Although considerable efforts have been made to explain the effects of fermentation on soybean meal and corn-based feed, the dynamics of the physicochemical characteristics, microbiota, and metabolic functions of soybean meal and corn mixed substrates during solid-state fermentation remain unclear. Here, multiple physicochemical analyses combined with high-throughput sequencing were performed to reveal the dynamic changes that occur during a novel two-stage solid-state fermentation process. Generally, inoculated bacteria rapidly proliferated in the initial 12-h aerobic fermentation (P = 0.002). Notably, most nutritional changes occurred during 12 to 24 h compared to 0 to 12 h. Second-stage anaerobic fermentation increased the bacterial abundance and lactic acid content (P < 0.00). Bacillus spp., Enterococcus spp., and Pseudomonas spp. were predominantly involved in the maturation of the fermented mixed substrates (P < 0.05). Additionally, the available phosphorus exhibited the greatest interaction with the microbial community structure. Cellular processes and environmental information processing might be the main metabolic processes of the microbiota during this fermentation. An in vivo model further evaluated the growth-promoting effects of the fermented products. These results characterized the dynamic changes that occur during two-stage solid-state fermentation and provided potential references for additional interventions to further improve the effectiveness and efficiency of solid-state fermentation of feed.

IMPORTANCE Solid-state fermentation (SSF) plays pivotal roles not only in human food but also farm animal diets. Soybean meal (SBM) and corn account for approximately 70% of the global feed consumption. However, the nutritional value of conventional SBM and corn mixed substrates (MS) is limited by antinutritional factors, causing substantial economic loss in livestock production. Although emerging studies have reported that SSF can improve the nutritional value of SBM-based substrates, the dynamic changes in the physicochemical features, microbiota, and metabolic functions of MS during SSF remain poorly understood, limiting further investigation. To provide insights into the dynamics of the physicochemical characteristics and the complex microbiome during the two-stage SSF of MS, multiple physicochemical analyses combined with high-throughput sequencing were applied here. These novel insights shed light on the complex changes that occur in the nutrition and microbiome during two-stage SSF of MS and are of great value for industrial feed-based practices and metabolomic research on SSF ecosystems.

Activation of RXR by bexarotene inhibits inflammatory conditions in human rheumatoid arthritis fibroblast‑like synoviocytes

Rheumatoid arthritis (RA) is a debilitating joint disease characterized by chronic inflammation, pathologic alteration of fibroblast‑like synoviocytes (FLS), destruction of cartilage and bone, and the formation of an invasive pannus. RA‑FLS exhibit increased proliferation and resistance to apoptosis. The retinoid X receptor (RXR) has a role in regulating cell cycle, differentiation and apoptosis, and agonism of RXR has been investigated as a treatment strategy in several types of cancer. However, there is little research on the effects of RXR agonism in other diseases. Bexarotene is a novel selective RXR ligand used in the treatment of T‑cell lymphoma. In the present study, bexarotene was used to investigate the involvement of RXR in tumor necrosis factor‑α (TNF‑α)‑induced RA conditions in human FLS. To the best of our knowledge, this is the first time that RXR has been demonstrated to be expressed in FLS and to be downregulated in response to TNF‑α stimulation. The present study also demonstrated that bexarotene exerted an anti‑inflammatory effect by downregulating expression of interleukin (IL)‑6, IL‑8, monocyte chemoattractant protein‑1, and high mobility group box‑1. Notably, bexarotene also rescued the TNF‑α‑induced downregulation of the anti‑inflammatory cytokines IL‑4 and transforming growth factor‑β1. Bexarotene treatment exhibited a potential protective effect against cartilage degradation by downregulating the expression of matrix metalloproteinase (MMP)‑1, MMP‑3 and MMP‑13. In addition, the present results demonstrated that the effects of bexarotene were mediated through the p38 mitogen‑activated protein kinase/nuclear factor‑κB pathway, via inhibition of p38 protein and the inhibitor α of κB phosphorylation. Taken together, the present findings demonstrated the potential of RXR agonism using bexarotene as a treatment against the development and progression of RA.

The role of iron metabolism in cancer therapy focusing on tumor-associated macrophages

Iron is an essential micronutrient in mammalian cells for basic processes such as DNA synthesis, cell cycle progression, and mitochondrial activity. Macrophages play a vital role in iron metabolism, which is tightly linked to their phagocytosis of senescent and death erythrocytes. It is now recognized that the polarization process of macrophages determines the expression profile of genes associated with iron metabolism. Although iron metabolism is strictly controlled by physiology, cancer has recently been connected with disordered iron metabolism. Moreover, in the environment of cancer, tumor-associated macrophages (TAMs) exhibit an iron release phenotype, which stimulates tumor cell survival and growth. Usually, the abundance of TAMs in the tumor is implicated in poor disease prognosis. Therefore, important attention has been drawn toward the development of tumor immunotherapies targeting these TAMs focussing on iron metabolism and reprogramming polarized phenotypes. Although further systematic research is still required, these efforts are almost certainly valuable in the search for new and effective cancer treatments.

The association of ferritin with cardiovascular and all-cause mortality in community-dwellers: The English longitudinal study of ageing

BACKGROUND

Ferritin constitutes a sensitive iron-storage index and multi-functional protein. Evidence on its association with mortality in general population is scarce and conflicting. We investigated the sex-specific associations of ferritin levels with all-cause and cardiovascular mortality in a population-based cohort.

METHODS

Data came from the English Longitudinal Study of Ageing and the national mortality registry. The sample comprised 5,471 participants aged ≥52 years. Blood concentration of ferritin was measured at baseline in 2004-05. Sex-specific Cox proportional hazards models were estimated with adjustment for age, major chronic diseases, marital status, educational attainment, total net household wealth, anemia, inflammatory markers, body mass index, smoking, and physical activity. Stratified analyses by chronic disease status were also performed.

RESULTS

We categorized ferritin in sex-specific quartiles. In men, we used, the following categorization: lowest (2-69ng/ml), second lowest (70-118ng/ml), second highest (reference category) (119-193ng/ml) and highest (194-598ng/ml) ferritin quartiles. In women, ferritin was categorized as follows: lowest (2-44ng/ml), second lowest (45-73ng/ml), second highest (reference category) (74-115ng/ml) and highest (116-341ng/ml) ferritin quartiles. 841 deaths of which 262 cardiovascular disease-related were recorded over a mean follow-up time of 7.7 years. Risk for all-cause mortality was found increased in men with hyperferritinemia (194-598ng/ml) and no history of major chronic diseases compared with the reference group [fully-adjusted HR: 1.49 (95%CI 1.03-2.16)]. Among women, those in the lowest ferritin quartile (2-44ng/ml) had increased risk for all-cause mortality [fully-adjusted HR: 1.59 (95%CI 1.18-2.13)] compared with the reference group after adjustment for all covariates. Regarding cardiovascular mortality, we observed a positive association with ferritin levels in men, which was blunted after adjustment for inflammatory markers and lifestyle parameters. Men with no major chronic diseases who were in the highest ferritin quartile had a significantly increased risk of cardiovascular mortality. No association between ferritin levels and cardiovascular mortality was detected in women.

CONCLUSION

Circulating ferritin levels showed sex-specific prognostic patterns. High ferritin levels in men with no major chronic disease and low ferritin levels in all women were associated with increased all-cause mortality after adjusting for covariates. High ferritin levels in men with no major chronic diseases were also independently associated with an increased risk of cardiovascular mortality. Future research is needed to clarify the prognostic role of ferritin.

The role of mitogen-activated protein kinases and sterol receptor coactivator-1 in TGF-β-regulated expression of genes implicated in macrophage cholesterol uptake

The anti-atherogenic cytokine TGF-β inhibits macrophage foam cell formation by suppressing the expression of key genes implicated in the uptake of modified lipoproteins. We have previously shown a critical role for p38 MAPK and JNK in the TGF-β-mediated regulation of apolipoprotein E expression in human monocytes. However, the roles of these two MAPK pathways in the control of expression of key genes involved in the uptake of modified lipoproteins in human macrophages is poorly understood and formed the focus of this study. TGF-β activated both p38 MAPK and JNK, and knockdown of p38 MAPK or c-Jun, a key downstream target of JNK action, demonstrated their requirement in the TGF-β-inhibited expression of several key genes implicated in macrophage lipoprotein uptake. The potential role of c-Jun and specific co-activators in the action of TGF-β was investigated further by studies on the lipoprotein lipase gene. c-Jun did not directly interact with the minimal promoter region containing the TGF-β response elements and a combination of transient transfection and knock down assays revealed an important role for SRC-1. These studies provide novel insights into the mechanisms underlying the TGF-β-mediated inhibition of macrophage gene expression associated with the control of cholesterol homeostasis.

Asthma as a disruption in iron homeostasis

Over several decades, asthma has evolved from being recognized as a single disease to include a diverse group of phenotypes with dissimilar natural histories, pathophysiologies, responses to treatment, and distinctive molecular pathways. With the application of Occam's razor to asthma, it is proposed that there is one cause underlying the numerous phenotypes of this disease and that the responsible molecular pathway is a deficiency of iron in the lung tissues. This deficiency can be either absolute (e.g. asthma in the neonate and during both pregnancy and menstruation) or functional (e.g. asthma associated with infections, smoking, and obesity). Comparable associations between asthma co-morbidity (e.g. eczema, urticaria, restless leg syndrome, and pulmonary hypertension) with iron deficiency support such a shared mechanistic pathway. Therapies directed at asthma demonstrate a capacity to impact iron homeostasis, further strengthening the relationship. Finally, pathophysiologic events producing asthma, including inflammation, increases in Th2 cells, and muscle contraction, can correlate with iron availability. Recognition of a potential association between asthma and an absolute and/or functional iron deficiency suggests specific therapeutic interventions including inhaled iron.

Oxidative stress, HDL functionality and effects of intravenous iron administration in women with iron deficiency anemia

BACKGROUND AND AIMS

Iron deficiency anemia (IDA) affects around 20-30% of adults worldwide. An association between IDA and cardiovascular disease (CVD) has been reported. Oxidative stress, inflammation and low concentration of high-density lipoproteins (HDL) were implicated on endothelial dysfunction and CVD in IDA. We studied the effects of iron deficiency and of an intravenous iron administration on oxidative stress and HDL characteristics in IDA women.

METHODS

Two studies in IDA women are presented: a case-control study, including 18 patients and 18 age-matched healthy women, and a follow-up study 72hr after the administration of intravenous iron (n = 16). Lipids, malondialdehyde, cholesteryl ester transfer protein (CETP), paraoxonase-1 (PON-1) and HDL chemical composition and functionality (cholesterol efflux and antioxidative activity) were measured. Cell cholesterol efflux from iron-deficient macrophages to a reference HDL was also evaluated.

RESULTS

IDA patients showed higher triglycerides and CETP activity and lower HDL-C than controls (all p < 0.001). HDL particles from IDA patients showed higher triglyceride content (+30%,p < 0.05) and lower antioxidative capacity (-23%,p < 0.05). Although HDL-mediated cholesterol efflux was similar between the patients and controls, iron deficiency provoked a significant reduction in macrophage cholesterol efflux (-25%,p < 0.05). Arylesterase activity of PON-1 was significantly lower in IDA patients than controls (-16%,p < 0.05). The intravenous administration of iron was associated with a decrease in malondialdehyde levels and an increase in arylesterase activity of PON-1 (-22% and +18%, respectively, p < 0.05).

CONCLUSION

IDA is associated with oxidative stress and functionally deficient HDL particles. It remains to be determined if such alterations suffice to impair endothelial function in IDA.

'Ride on the ferrous wheel'--the cycle of iron in macrophages in health and disease

Iron homeostasis and macrophage biology are closely interconnected. On the one hand, iron exerts multiple effects on macrophage polarization and functionality. On the other hand, macrophages are central for mammalian iron homeostasis. The phagocytosis of senescent erythrocytes and their degradation by macrophages enable efficient recycling of iron and the maintenance of systemic iron balance. Macrophages express multiple molecules and proteins for the acquisition and utilization of iron and many of these pathways are affected by inflammatory signals. Of note, iron availability within macrophages has significant effects on immune effector functions and metabolic pathways within these cells. This review summarizes the physiological and pathophysiological aspects of macrophage iron metabolism and highlights its relevant consequences on immune function and in common diseases such as infection and atherosclerosis.

An Asp49 phospholipase A2 from snake venom induces cyclooxygenase-2 expression and prostaglandin E2 production via activation of NF-κB, p38MAPK, and PKC in macrophages

Phospholipases A2 (PLA2) are key enzymes for production of lipid mediators. We previously demonstrated that a snake venom sPLA2 named MT-III leads to prostaglandin (PG)E2 biosynthesis in macrophages by inducing the expression of cyclooxygenase-2 (COX-2). Herein, we explored the molecular mechanisms and signaling pathways leading to these MT-III-induced effects. Results demonstrated that MT-III induced activation of the transcription factor NF-κB in isolated macrophages. By using NF-κB selective inhibitors, the involvement of this factor in MT-III-induced COX-2 expression and PGE2 production was demonstrated. Moreover, MT-III-induced COX-2 protein expression and PGE2 release were attenuated by pretreatment of macrophages with SB202190, and Ly294002, and H-7-dihydro compounds, indicating the involvement of p38MAPK, PI3K, and PKC pathways, respectively. Consistent with this, MT-III triggered early phosphorylation of p38MAPK, PI3K, and PKC. Furthermore, SB202190, H-7-dihydro, but not Ly294002 treatment, abrogated activation of NF-κB induced by MT-III. Altogether, these results show for the first time that the induction of COX-2 protein expression and PGE2 release, which occur via NF-κB activation induced by the sPLA2-MT-III in macrophages, are modulated by p38MAPK and PKC, but not by PI3K signaling proteins.

Role of the JAK/STAT signaling pathway in the pathogenesis of acute myocardial infarction in rats and its effect on NF-κB expression

The Janus kinase/signal transducer and activator of transcription pathway (JAK/STAT signaling pathway) is involved in the development of numerous cardiovascular diseases, although the specific role of this pathway in the pathogenesis of acute myocardial infarction (AMI) has not been elucidated. The purpose of this study was to evaluate the role of the JAK/STAT signaling pathway in the onset of AMI in rats. We also tested the effect of this pathway on nuclear factor κB (NF-κB) expression in the myocardium and tumor necrosis factor-α (TNF-α) levels in the plasma of AMI rats. An AMI rat model was successfully established and AG490 was used to block the JAK/STAT signaling pathway. The plasma TNF-α levels of AMI rats were measured by ELISA. The protein expression of NF-κB in the myocardial cells of AMI rats was detected by immunohistochemistry. The infarction area was significantly smaller in rats treated with AG490 after coronary artery ligation (group C) compared with that in the myocardial infarction control group (group B). The left ventricular mass indices in the sham surgery group (group A) and group C were significantly lower compared with those of group B. Plasma TNF-α concentrations in group B were significantly higher compared with those of groups A and C. There were significantly fewer cardiomyocytes positively exhibiting NF-κB protein expression in groups A and C compared with group B. The JAK/STAT signaling pathway is involved in the onset of myocardial infarction and may also be involved in left ventricular remodeling after myocardial infarction. The involvement of the JAK/STAT signaling pathway in the onset of myocardial infarction may be correlated with its effects on the expression of NF-κB and TNF-α.

Acute phase reactants as novel predictors of cardiovascular disease

Acute phase reaction is a systemic response which usually follows a physiological condition that takes place in the beginning of an inflammatory process. This physiological change usually lasts 1-2 days. However, the systemic acute phase response usually lasts longer. The aim of this systemic response is to restore homeostasis. These events are accompanied by upregulation of some proteins (positive acute phase reactants) and downregulation of others (negative acute phase reactants) during inflammatory reactions. Cardiovascular diseases are accompanied by the elevation of several positive acute phase reactants such as C-reactive protein (CRP), serum amyloid A (SAA), fibrinogen, white blood cell count, secretory nonpancreatic phospholipase 2-II (sPLA2-II), ferritin, and ceruloplasmin. Cardiovascular disease is also accompanied by the reduction of negative acute phase reactants such as albumin, transferrin, transthyretin, retinol-binding protein, antithrombin, and transcortin. In this paper, we will be discussing the biological activity and diagnostic and prognostic values of acute phase reactants with cardiovascular importance. The potential therapeutic targets of these reactants will be also discussed.

Pathogenic implications of iron accumulation in multiple sclerosis

Iron, an essential element used for a multitude of biochemical reactions, abnormally accumulates in the CNS of patients with multiple sclerosis (MS). The mechanisms of abnormal iron deposition in MS are not fully understood, nor do we know whether these deposits have adverse consequences, that is, contribute to pathogenesis. With some exceptions, excess levels of iron are represented concomitantly in multiple deep gray matter structures often with bilateral representation, whereas in white matter, pathological iron deposits are usually located at sites of inflammation that are associated with veins. These distinct spatial patterns suggest disparate mechanisms of iron accumulation between these regions. Iron has been postulated to promote disease activity in MS by various means: (i) iron can amplify the activated state of microglia resulting in the increased production of proinflammatory mediators; (ii) excess intracellular iron deposits could promote mitochondria dysfunction; and (iii) improperly managed iron could catalyze the production of damaging reactive oxygen species (ROS). The pathological consequences of abnormal iron deposits may be dependent on the affected brain region and/or accumulation process. Here, we review putative mechanisms of enhanced iron uptake in MS and address the likely roles of iron in the pathogenesis of this disease.