Mutual interaction between iron homeostasis and obesity pathogenesis

Daily intake of baru (Dipteryx alata Vog.), a Cerrado native almond, promotes changes in the intestinal microbiota of individuals with obesity: A pilot study

The Brazilian Cerrado biome is rich in plant biodiversity, with fruits that have unique sensory characteristics and high nutritional quality. Among the various fruits, baru (Dipteryx alata Vog.) has attracted the attention of researchers because of its high lipid, protein, carbohydrate, fiber, and micronutrient (minerals and vitamins) contents. The present study evaluated the effects of regular consumption of baru almonds for over 60 days on the biochemical and anthropometric profiles and fecal microbiota of obese individuals. A pilot study was conducted on 15 individuals with obesity who were instructed to consume a 20-gram portion of baru almonds throughout the day. The body composition was assessed using anthropometric measurements. Blood pressure, glucose levels, lipid profile, serum insulin and iron contents, and fecal microbiota composition were determined at baseline (day 0) and after 60 days. Baru almond consumption contributed to changes in biochemical parameters, improved HDL cholesterol levels, and reduced total and LDL cholesterol levels. Some positive changes in the microbiota composition after consuming baru almonds include a decrease in the Faecalibacterium family and an increase in the Provotella genus. Therefore, ingesting baru almonds can modulate gut microbiota of individuals with obesity.

Obesity-related glomerulopathy: recent advances in inflammatory mechanisms and related treatments

Obesity-related glomerulopathy, which is an obesity-triggered kidney damage, has become a significant threat to human health. Several studies have recently highlighted the critical role of inflammation in obesity-related glomerulopathy development. Additionally, excess adipose tissue and adipocytes in patients with obesity produce various inflammatory factors that cause systemic low-grade inflammation with consequent damage to vascular endothelial cells, exacerbating glomerular injury. Therefore, we conducted a comprehensive review of obesity-related glomerulopathy and addressed the critical role of obesity-induced chronic inflammation in obesity-related glomerulopathy pathogenesis and progression, which leads to tubular damage and proteinuria, ultimately impairing renal function. The relationship between obesity and obesity-related glomerulopathy is facilitated by a network of various inflammation-associated cells (including macrophages, lymphocytes, and mast cells) and a series of inflammatory mediators (such as tumor necrosis factor α, interleukin 6, leptin, adiponectin, resistin, chemokines, adhesion molecules, and plasminogen activator inhibitor 1) and their inflammatory pathways. Furthermore, we discuss a recently discovered relationship between micronutrients and obesity-related glomerulopathy inflammation and the important role of micronutrients in the body's anti-inflammatory response. Therefore, assessing these inflammatory molecules and pathways will provide a strong theoretical basis for developing therapeutic strategies based on anti-inflammatory effects to prevent or delay the onset of kidney injury.

Association between nutrient intake and female infertility: a study based on NHANES database

BACKGROUND

This study was designed to investigate the association between nutrients and female infertility.

METHODS

A cross-sectional study on 18-45 years of age reproductive-age women was conducted using the data from the National Health and Nutrition Examination Surveys (NHANES) for the periods 2013-2014 and 2015-2016. Multivariate logistic regression analysis was performed to evaluate the association between nutrients and female infertility. Subgroup analysis was applied to the body mass index (BMI). Results were summarised using an odds ratio (OR) with a 95% confidence interval (CI).

RESULTS

Of the total 1713 women, 204 women (11.91%) were infertile. The result demonstrated that higher intake of carbohydrate (OR: 0.46, 95% CI: 0.24-0.86, p = 0.018), vitamin A (OR: 0.44, 95% CI: 0.24-0.80, p = 0.009), vitamin C (OR: 0.48, 95% CI: 0.26-0.88, p = 0.020), magnesium (OR: 0.36, 95% CI: 0.17-0.76, p = 0.009), iron (OR: 0.43, 95% CI: 0.23-0.82, p = 0.012), lycopene (OR: 0.55, 95% CI: 0.33-0.91, p = 0.022), and total folate (OR: 0.38, 95% CI: 0.20-0.70, p = 0.003) were associated with a lower risk of female infertility. The subgroup analysis also reported that intakes of vitamin A, vitamin C, and lycopene were related to a lower risk of female infertility among women with a BMI being 18.5-24.9 kg/m2. Among women with BMI > 24.9 kg/m2, high intakes of magnesium, iron and total folate were associated with a decreased risk of female infertility.

CONCLUSIONS

The intake of several nutrients is associated with a decreased risk of female infertility. These findings provide insight into potentially modifiable lifestyle factors associated with female infertility.

Interactive Effects of Obesity and Hypertension on Patterns of Hair Essential Trace Element and Mineral Content in Adult Women

The objective of the present study was to evaluate potential similar patterns and interactive effects of obesity and hypertension on hair essential trace element and mineral content in adult women. In this cross-sectional study, a total of 607 adult women divided into controls (n = 101), groups with obesity without hypertension (n = 199), hypertension without obesity (n = 143), and both obesity and hypertension (n = 164) were included in the study. Assessment of hair mineral and trace element levels was performed by inductively-coupled plasma mass-spectrometry. Hair Ca, Mg, Co, and Mn levels in women with obesity, hypertension, and both diseases were significantly lower, compared to controls. Hair Mg levels in women with obesity and hypertension were significantly lower, whereas hair Na and K were found to be higher when compared to other groups. Hair Fe and V content in obese patients was lower than in other groups. Obesity was associated with lower hair Cu levels, whereas patients with hypertension had higher hair Cu content. Hypertension was also associated with higher hair Cr and Se content irrespective of body weight. Hair Zn levels in obese women with and without hypertension were significantly lower than those in healthy controls and normal-weight women with hypertension. In multiple regression models hair Mg was considered as a significant negative predictor of both systolic and diastolic blood pressure values. The observed alterations in hair trace element and mineral content provide an additional link between obesity and hypertension, although further detailed studies are required.

Chronic intermittent hypobaric hypoxia improves iron metabolism disorders via the IL-6/JAK2/STAT3 and Epo/STAT5/ERFE signaling pathways in metabolic syndrome rats

AIM

Our previous study demonstrated that chronic intermittent hypobaric hypoxia (CIHH) improved iron metabolism disorder in obese rats through the downregulation of hepcidin. This study aimed to observe the molecular mechanism of CIHH in improving iron metabolism disorders, especially by Janus kinase/signal transducer and activation of the transcription (JAK/STAT) signaling pathway in metabolic syndrome (MS) rats.

METHODS

Six-week-old male Sprague-Dawley rats were randomly divided into four groups: CON, CIHH (subjected to hypobaric hypoxia simulating 5000-m altitude for 28 days, 6 h daily), MS (induced by high fat diet and fructose water), and MS+CIHH. The serum levels of glucose, lipid metabolism, iron metabolism, interleukin-6 (IL-6), erythropoietin (Epo) and hepcidin were measured. The protein expressions of JAK2, STAT3, STAT5, bone morphogenetic protein 6 (BMP6), small mothers against decapentaplegic 1 (SMAD1) and hepcidin were examined. The mRNA expressions of erythroferrone (ERFE) and hepcidin were analyzed.

RESULTS

The MS rats displayed obesity, hyperglycemia, hyperlipidemia, iron metabolism disorder, increased IL-6 and hepcidin serum levels, upregulation of JAK2/STAT3 signaling pathway, decreased Epo serum levels, downregulation of STAT5/ERFE signaling pathway in spleen, upregulation of BMP/SMAD signaling pathway in liver, and increased hepcidin mRNA and protein expression compared to CON rats. All the aforementioned abnormalities in MS rats were ameliorated in MS + CIHH rats.

CONCLUSIONS

CIHH improved iron metabolism disorders, possibly by inhibiting IL-6/JAK2/STAT3 and activating Epo/STAT5/ERFE signaling pathway, thus downregulating hepcidin in MS rats.

Micronutrient Deficiency in Children and Adolescents with Obesity-A Narrative Review

Childhood obesity represents a serious public health burden. Despite excessive dietary consumption, children with obesity present high rates of micronutrient deficiencies, such as deficiencies in minerals and specific vitamins; micronutrient deficiencies may have a pathogenic role in obesity-related metabolic comorbidities. In this narrative review, we analyzed the main deficiencies associated with obesity, their clinical consequences, and the evidence about a possible supplementation. Iron; vitamins A, B, C, D, and E; folic acid; zinc; and copper deficiencies represent the most common deficient microelements. The relationship between obesity and multiple micronutrient deficiencies remains unclear, and different mechanisms have been proposed. The medical care plan for pediatric obesity should include food choices with high nutritional content as part of a crucial approach to obesity-related complications. Unfortunately, only a few studies are available regarding the efficacy of oral supplementation or weight loss for treating them; thus, continuous nutritional monitoring is necessary.

Associations of dietary antioxidant micronutrients with the prevalence of obesity in adults

Background

Antioxidant micronutrients have a therapeutic potential for clinical treatment of obesity. NO research, however, has examined the connection between the complex level of dietary antioxidants and obesity.

Materials and methods

We mainly aimed to investigate the relationship between a combination of antioxidants and obesity using the database of the national health and nutrition examination survey (NHANES). This cross-sectional study contains a survey of 41,021 people (≥18 years) in total ranging from 2005 to 2018. Multivariate logistic and weighted quantile sum (WQS) regression were performed to investigate the associations between these antioxidants, both individually and collectively, and the prevalence of obesity. The restricted cubic spline (RCS) regression was also utilized to analyze the linearity of these associations.

Results

According to multivariate logistic models, we found that the levels of most antioxidants in the highest quartile were independently related to a lower prevalence of obesity, while a reverse result was observed in selenium (p for trend <0.05). The WQS index revealed that a total of the 11 antioxidants is negatively related to the prevalence of obesity and abdominal obesity (all p<0.001), and iron/vitamin C have the greatest weight in the negative associations between antioxidant complex and obesity, as well as abdominal obesity. In addition, the RCS regression showed that retinol, vitamin A, α-carotene, β-carotene, β-cryptoxanthin, vitamin C, iron, and copper all had a non-linear association with obesity. Threshold effect analysis demonstrated that the inflection points of retinol, vitamin A, α-carotene, β-carotene, β-cryptoxanthin, vitamin C, iron, and cooper were 235.57, 374.81, 58.89, 891.44, 30.70, 43,410.00, 11,240.00, and 990.00 μg/day, respectively.

Conclusion

Our study found that a high level of a complex of 11 dietary antioxidants is related to a lower prevalence of obesity and abdominal obesity, among this inverse associations iron and vitamin C have the greatest weight.

The role of iron metabolism in chronic diseases related to obesity

Obesity is one of the major public health problems threatening the world, as well as a potential risk factor for chronic metabolic diseases. There is growing evidence that iron metabolism is altered in obese people, however, the highly refined regulation of iron metabolism in obesity and obesity-related complications is still being investigated. Iron accumulation can affect the body’s sensitivity to insulin, Type 2 diabetes, liver disease and cardiovascular disease. This review summarized the changes and potential mechanisms of iron metabolism in several chronic diseases related to obesity, providing new clues for future research.

The relationship between anemia and obesity

INTRODUCTION

Obesity is linked to a variety of unfavourable outcomes, including anaemia, which is a serious global public health problem. The prevalence of obesity along with anaemia suggests a relationship between obesity and anaemia. Recent studies have demonstrated strong associations between anaemia and obesity, chronic diseases, ageing, hepato-renal impairment, chronic infection, autoimmune diseases, and widespread malignancy. Thus, the intersection point of obesity and anaemia is an important area of attention.

AREA COVERED

This paper reviews the pathophysiology of obesity and anaemia. Then, It deliberates the relationship between obesity and different types of anaemia and other clinical forms associated with anaemia.

EXPERT OPINION

Obesity, especially obesity-related to excessive visceral fat distribution, is accompanied by several disturbances at the endothelial, hormonal, and inflammatory levels. These disturbances induce activation of several mechanisms that contribute to the anaemic state. Over-weight patients with chronic anaemias are required to maintain the related vitamins and minerals at optimum levels and appropriate BMI. In addition, a regular clinical follow-up is essential to be scheduled to reduce the risk of complications associated with anaemia in obese patients.

Sex-Specific Associations between Serum Ferritin and Osteosarcopenic Obesity in Adults Aged over 50 Years

We investigated the sex-specific association between ferritin and adverse body composition in adults aged over 50 years in a population-based cohort. A total of 25,546 participants (16,912 women; 8634 men) were stratified into three groups by the tertiles of ferritin. The number of adverse body compositions was categorized as 0 (without osteopenia/osteoporosis, low muscle mass, or obesity), 1 (having one of the components), 2 (two), and 3 (all three; osteosarcopenic obesity). As ferritin tertile increased, the prevalence of one, two, or three simultaneous adverse body compositions increased, significant only in women (p < 0.0001), not in men (p = 0.125). Among women, the prevalence of osteosarcopenic obesity gradually increased from 1.7% in the lowest, to 2.2% in the middle, and 2.5% in the highest tertile. Using multivariate-adjusted analysis, women in the higher tertile had an increased likelihood of having multiple adverse body compositions compared with those in the lowest tertile. Women in the highest tertile had a 1.52 times increased risk of osteosarcopenic obesity than those in the lowest tertile. A high ferritin level was associated with an increased risk of having multiple adverse body compositions, especially for osteosarcopenic obesity in women aged >50 years, suggesting its potential use for detecting osteosarcopenic obesity.

The role of iron in obesity and diabetes

Iron is an essential trace metal for all life, but excess iron causes oxidative stress through catalyzing the toxic hydroxy-radical production via the Fenton reaction. The number of patients with obesity and diabetes has been increasing worldwide, and their onset and development are affected by diet. In both clinical and experimental studies, a high body iron content was associated with obesity and diabetes, and the reduction of body iron content to an appropriate level can ameliorate the status and development of obesity and diabetes. Macrophages play an essential role in the pathophysiology of obesity and diabetes, and in the metabolism and homeostasis of iron in the body. Recent studies demonstrated that macrophage polarization is related to adipocyte hypertrophy and insulin resistance through their capabilities of iron handling. Control of iron in macrophages is a potential therapeutic strategy for obesity and diabetes. J. Med. Invest. 69 : 1-7, February, 2022.

Different trends of Cr, Fe and Zn contents in hair between obese, overweight and normal-weight men

OBJECTIVES

Overweight and obesity are risk factors for many diseases, nutrition leading to these phenomena is not only a question of disbalance between energy intake and expenditure, but also the presence of micronutrients. In our study, we focused on measuring residues of chromium, zinc and iron in the hair of men with different BMI.

METHODS

Hair samples and anthropometric questionnaires were collected from 45 males. Numbers of subjects and age structure were comparable between the three BMI groups. The determination of metal levels was performed by inductively coupled plasma mass spectrometry after mineralization of the hair.

RESULTS

The hair of obese men contained significantly higher chromium (0.096 μg/g vs. 0.045 μg/g, p = 0.0039) and iron (9.42 μg/g vs. 5.84 μg/g, p = 0.0009) concentrations than that of overweight men, but no significant difference between the normal-weight group and the obese group were found. The concentration of zinc was lower in obese subjects compared to overweight subjects (183.5 μg/g vs. 206.2 μg/g, p = 0.038). Also, statistically significant correlations between chromium and iron concentrations in hair and BMI were found (r = 0.307, p = 0.040, r = 0.360, p = 0.015, respectively). According to our results, age did not significantly affect chromium, iron and zinc concentrations in hair.

CONCLUSION

Consistent with some published studies, we have found that obese men have higher chromium and iron concentrations and lower zinc concentrations in hair.

The effect of prepregnancy body mass index on maternal micronutrient status: a meta-analysis

The relationship between prepregnancy body mass index (BMI) and maternal micronutrient status is inconsistent and has not received sufficient attention. This meta-analysis aimed to evaluate the effect of prepregnancy BMI on micronutrient levels in pregnant women. PubMed, Embase, Web of Science, and the Cochrane Library were searched for articles that contained information on micronutrient levels and prepregnancy BMI. A random-effects model was used to determine the association between prepregnancy BMI and maternal micronutrient status. Sixty-one eligible articles were eventually included, with 83,554 participants. Vitamin B12, folate, vitamin D, iron and ferritin were the main micronutrients evaluated in our meta-analysis. Prepregnancy obesity and overweight may lead to an increased risk of micronutrient deficiency, including vitamin B12, folate and vitamin D deficiency, while prepregnancy obesity or overweight may have no significant association with ferritin deficiency. Additionally, the results of the dose-response analyses demonstrated a possible significant inverse correlation between prepregnancy BMI and levels of micronutrient, except for iron and ferritin. Compared with women with normal weight, women who were overweight or obese prepregnancy have lower micronutrient concentrations and are more likely to exhibit micronutrient deficiency during pregnancy, which is harmful to both mothers and neonates.

Trace Element and Mineral Levels in Serum, Hair, and Urine of Obese Women in Relation to Body Composition, Blood Pressure, Lipid Profile, and Insulin Resistance

The objective of this study was to evaluate serum, hair, and urinary trace element and mineral content in normal-weight and obese women in relation to metabolic risk factors. A total of 80 women aged 30–70 y.o. were enrolled in the obese group (n = 40) and normal-weight group (n = 40). Serum, hair, and urinary trace element and mineral levels were assessed using inductively coupled plasma spectrometry. Body fat percentage was evaluated using bioimpedance. Obese subjects were characterized by significantly higher body fat percentage, blood pressure, serum triglyceride concentration, and insulin resistance. Serum Ca, Fe, Mg, Se, V, Zn levels, hair Fe, Mg, V content, and urinary Se and V concentrations were found to be lower in obese subjects as compared to lean controls. In turn, serum Cu and urinary Fe levels in obese women were characterized by a significant increase. In multiple regression models serum Cu, Se, and Zn levels were significantly associated with BMI even after adjustment for blood biochemistry, body composition, and blood pressure. Serum trace element and mineral levels also significantly contributed to group discrimination. These findings allow to propose that obesity-associated disturbances in trace element and mineral status may at least partially contribute to metabolic risk in obese subjects.

H. Shehada A, Abdelnasser AbouHassanein E, Moawad J, Bawadi H, Shi Z. Association between central obesity indices and iron status indicators among Qatari adults

Co-existence of iron deficiency and obesity in adults has been reported in many countries. However, little is known on the association between obesity and iron deficiency in Qatar. This study aimed to investigate the link between abdominal obesity indices and iron status among adults in Qatar. A random sample of 1000 healthy Qatari adults, aged 20-50 years, was obtained from Qatar Biobank study. Body weight, waist circumference, dual x-ray absorptiometry (DXA) parameters and iron status indicators were measured using standard techniques. Multiple regression analysis was used to examine the associations. The prevalence of iron deficiency and anaemia were 35.4 and 25%, respectively. Of the participants with a large waist circumference, 31.7% had anaemia. Ferritin significantly increased with the increase in the android fat to gynoid fat ratio and visceral fat in both genders. Serum iron and transferring saturation decreased significantly with the increase in waist circumference in women. In both genders, C-reactive protein increased with the increase in all obesity indices. Standardized values of waist circumference, android fat, gynoid fat ratio and visceral fat were significantly associated with log transformed ferritin in men and women. Waist circumference was inversely related to serum iron (β:-0.95, 95% CI:-1.50,-0.39) and transferrin saturation (β:-1.45, 95%CI:-2.46, -0.43) in women. In men, waist circumference was positively associated with haemoglobin level (β: 0.16, 95% CI:0.04, 0.29). Central obesity coexists with anaemia among the study population. Elevated central obesity indices were associated with an increase in ferritin concentration. The increased ferritin concentration may be attributed to the increase in inflammatory status as a result of an increase in c-reactive protein concentration associated with central obesity.

Iron Deficiency in Obesity and after Bariatric Surgery

Iron deficiency (ID) is particularly frequent in obese patients due to increased circulating levels of acute-phase reactant hepcidin and adiposity-associated inflammation. Inflammation in obese subjects is closely related to ID. It induces reduced iron absorption correlated to the inhibition of duodenal ferroportin expression, parallel to the increased concentrations of hepcidin. Obese subjects often get decreased inflammatory response after bariatric surgery, accompanied by decreased serum hepcidin and therefore improved iron absorption. Bariatric surgery can induce the mitigation or resolution of obesity-associated complications, such as hypertension, insulin resistance, diabetes mellitus, and hyperlipidemia, adjusting many parameters in the metabolism. However, gastric bypass surgery and sleeve gastrectomy can induce malabsorption and may accentuate ID. The present review explores the burden and characteristics of ID and anemia in obese patients after bariatric surgery, accounting for gastric bypass technique (Roux-en-Y gastric bypass-RYGB) and sleeve gastrectomy (SG). After bariatric surgery, obese subjects' iron status should be monitored, and they should be motivated to use adequate and recommended iron supplementation.

Oxidative Stress, Plant Natural Antioxidants, and Obesity

Oxidative stress is important in the pathophysiology of obesity, altering regulatory factors of mitochondrial activity, modifying the concentration of inflammation mediators associated with a large number and size of adipocytes, promoting lipogenesis, stimulating differentiation of preadipocytes to mature adipocytes, and regulating the energy balance in hypothalamic neurons that control appetite. This review discusses the participation of oxidative stress in obesity and the important groups of compounds found in plants with antioxidant properties, which include (a) polyphenols such as phenolic acids, stilbenes, flavonoids (flavonols, flavanols, anthocyanins, flavanones, flavones, flavanonols, and isoflavones), and curcuminoids (b) carotenoids, (c) capsaicinoids and casinoids, (d) isothiocyanates, (e) catechins, and (f) vitamins. Examples are analyzed, such as resveratrol, quercetin, curcumin, ferulic acid, phloretin, green tea, Hibiscus Sabdariffa, and garlic. The antioxidant activities of these compounds depend on their activities as reactive oxygen species (ROS) scavengers and on their capacity to prevent the activation of NF-κB (nuclear factor κ-light-chain-enhancer of activated B cells), and reduce the expression of target genes, including those participating in inflammation. We conclude that natural compounds have therapeutic potential for diseases mediated by oxidative stress, particularly obesity. Controlled and well-designed clinical trials are still necessary to better know the effects of these compounds.

Chronic intermittent hypobaric hypoxia improves markers of iron metabolism in a model of dietary-induced obesity

BACKGROUND

Obesity, a risk factor for many chronic diseases, is a potential independent risk factor for iron deficiency. Evidence has shown that chronic intermittent hypobaric hypoxia (CIHH) has protective or improved effects on cardiovascular, nervous, metabolic and immune systems. We hypothesized that CIHH may ameliorate the abnormal iron metabolism in obesity. This study was aimed to investigate the effect and the underlying mechanisms of CIHH on iron metabolism in high-fat-high-fructose-induced obese rats.

METHODS

Six to seven weeks old male Sprague-Dawley rats were fed with different diet for 16 weeks, and according to body weight divided into four groups: control (CON), CIHH (28-day, 6-h daily hypobaric hypoxia treatment simulating an altitude of 5000 m), dietary-induced obesity (DIO; induced by high fat diet and 10% fructose water feeding), and DIO + CIHH groups. The body weight, systolic arterial pressure (SAP), Lee index, fat coefficient, blood lipids, blood routine, iron metabolism parameters, interleukin6 (IL-6) and erythropoietin (Epo) were measured. The morphological changes of the liver, kidney and spleen were examined. Additionally, hepcidin mRNA expression in liver was analyzed.

RESULTS

The DIO rats displayed obesity, increased SAP, lipids metabolism disorders, damaged morphology of liver, kidney and spleen, disturbed iron metabolism, increased IL-6 level and hepcidin mRNA expression, and decreased Epo compared to CON rats. But all the aforementioned abnormalities in DIO rats were improved in DIO + CIHH rats.

CONCLUSIONS

CIHH improves iron metabolism disorder in obese rats possibly through the down-regulation of hepcidin by decreasing IL-6 and increasing Epo.

Lactoferrin from Bovine Milk: A Protective Companion for Life

Lactoferrin (Lf), an iron-binding multifunctional glycoprotein belonging to the transferrin family, is present in most biological secretions and reaches particularly high concentrations in colostrum and breast milk. A key function of lactoferrin is non-immune defence and it is considered to be a mediator linking innate and adaptive immune responses. Lf from bovine milk (bLf), the main Lf used in human medicine because of its easy availability, has been designated by the United States Food and Drug Administration as a food additive that is generally recognized as safe (GRAS). Among the numerous protective activities exercised by this nutraceutical protein, the most important ones demonstrated after its oral administration are: Antianemic, anti-inflammatory, antimicrobial, immunomodulatory, antioxidant and anticancer activities. All these activities underline the significance in host defence of bLf, which represents an ideal nutraceutical product both for its economic production and for its tolerance after ingestion. The purpose of this review is to summarize the most important beneficial activities demonstrated following the oral administration of bLf, trying to identify potential perspectives on its prophylactic and therapeutic applications in the future.

Deletion of H-ferritin in macrophages alleviates obesity and diabetes induced by high-fat diet in mice

AIMS/HYPOTHESIS

Iron accumulation affects obesity and diabetes, both of which are ameliorated by iron reduction. Ferritin, an iron-storage protein, plays a crucial role in iron metabolism. H-ferritin exerts its cytoprotective action by reducing toxicity via its ferroxidase activity. We investigated the role of macrophage H-ferritin in obesity and diabetes.

METHODS

Conditional macrophage-specific H-ferritin (Fth, also known as Fth1) knockout (LysM-Cre Fth KO) mice were used and divided into four groups: wild-type (WT) and LysM-Cre Fth KO mice with normal diet (ND), and WT and LysM-Cre Fth KO mice with high-fat diet (HFD). These mice were analysed for characteristics of obesity and diabetes, tissue iron content, inflammation, oxidative stress, insulin sensitivity and metabolic measurements. RAW264.7 macrophage cells were used for in vitro experiments.

RESULTS

Iron concentration reduced, and mRNA expression of ferroportin increased, in macrophages from LysM-Cre Fth KO mice. HFD-induced obesity was lower in LysM-Cre Fth KO mice than in WT mice at 12 weeks (body weight: KO 34.6 ± 5.6 g vs WT 40.1 ± 5.2 g). mRNA expression of inflammatory cytokines and infiltrated macrophages and oxidative stress increased in the adipose tissue of HFD-fed WT mice, but was not elevated in HFD-fed LysM-Cre Fth KO mice. However, WT mice fed an HFD had elevated iron concentration in adipose tissue and spleen, which was not observed in LysM-Cre Fth KO mice fed an HFD (adipose tissue [μmol Fe/g protein]: KO 1496 ± 479 vs WT 2316 ± 866; spleen [μmol Fe/g protein]: KO 218 ± 54 vs WT 334 ± 83). Moreover, HFD administration impaired both glucose tolerance and insulin sensitivity in WT mice, which was ameliorated in LysM-Cre Fth KO mice. In addition, energy expenditure, mRNA expression of thermogenic genes, and body temperature were higher in KO mice with HFD than WT mice with HFD. In vitro experiments showed that iron content was reduced, and lipopolysaccharide-induced Tnf-α (also known as Tnf) mRNA upregulation was inhibited in a macrophage cell line transfected with Fth siRNA.

CONCLUSIONS/INTERPRETATION

Deletion of macrophage H-ferritin suppresses the inflammatory response by reducing intracellular iron levels, resulting in the prevention of HFD-induced obesity and diabetes. The findings from this study highlight macrophage iron levels as a potential therapeutic target for obesity and diabetes.

A Search for Similar Patterns in Hair Trace Element and Mineral Content in Children with Down's Syndrome, Obesity, and Growth Delay

The objective of the present study was to perform comparative analysis of hair trace element and mineral levels in children with Down's syndrome, growth delay, and obesity in order to reveal common and specific patterns. Hair Zn (14, 7, and 15%), Ca (38%, 24%, and 47%), and Mg (33%, 31%, and 49%) levels in children with Down's syndrome, obesity, and growth delay were lower than the respective control values. At the same time, patients with Down's syndrome and growth delay were characterized by 27% and 21%, as well as 24% and 20% lower hair Co as well as Cu content than healthy examinees. Certain alterations were found to be disease-specific. Particularly, in Down's syndrome children, hair Cr, Fe, and V levels were significantly lower, whereas hair P content exceeded the control values. Obese children were characterized by significantly increased hair Cr content. At the same time, hair Mn and Si levels in children with growth delay were lower as compared with the controls. In regression models, all three studied diseases were considered as negative predictors of hair Cu content. Down's syndrome and growth delay, but not obesity, were inversely associated with hair Co content. Both Down's syndrome and obesity were inversely associated with hair Zn content. Based on the revealed similarities in altered hair element, content it is proposed that deficiency of essential elements may predispose Down's syndrome patients to certain syndrome comorbidities including growth delay and obesity, although further detailed studies are required.

The Impact of Maternal Overweight on Hair Essential Trace Element and Mineral Content in Pregnant Women and Their Children

The aim of the present study was to investigate hair essential trace elements and mineral levels in 105 pregnant normal-weight (control) and 55 overweight and obese women in the third trimester of pregnancy, as well as in their children at the age of 9 months. The hair essential trace elements and mineral levels were assessed using inductively coupled plasma mass-spectrometry. Overweight pregnant women had significantly reduced Cr (- 24%; p = 0.047) and Zn (- 13%; p = 0.008) content, as well as elevated hair Na and K levels as compared to the controls. Children from overweight and obese mothers had lower hair Mo (- 18%; p = 0.017), Se (- 8%; p = 0.043), and V (- 24%; p = 0.028) levels, as well as elevated Sr content (19%; p = 0.025). Correlation analysis revealed a significant relationship between maternal and child hair levels of Co (r = 0.170; p = 0.038), Cu (r = 0.513; p < 0.001), Mn (r = 0.240; p = 0.003), and Na (r = 0.181; p = 0.027) in the whole sample. Pre-pregnancy maternal body mass index (BMI) positively correlated with maternal hair K (r = 0.336; p < 0.001) and Na (r = 0.212; p = 0.008) and negatively correlated with V (r = - 0.204; p = 0.011) and Zn (r = - 0.162; p = 0.045) levels. The results indicate that impaired trace element and mineral metabolism may play a role in the link between maternal obesity, complications of pregnancy and child's postnatal development. Hypothetically, dietary improvement may be used as a tool to reduce these risks. However, further experimental and clinical studies are required to investigate the relationship between obesity and trace element metabolism in pregnancy.

Iron status and hepcidin levels as potential regulators of haemoglobin homeostasis in overweight and obese women of childbearing age

Objectives

Overweight is considered a risk factor for anaemia. However, the mechanisms underlying anaemia development in overweight and obese people remain unclear. This study analysed the correlation of iron status (soluble transferrin receptor [sTfR]/log ferritin ratio) and hepcidin levels with haemoglobin (Hb) levels in overweight and obese women of childbearing age.

Methods

In this cross-sectional study, we recruited 66 women aged 20–29 years with a body mass index ≥23 kg/m². We gathered data on informed consent, demographic characteristics, questionnaire responses, anthropometric and laboratory values. A Spearman correlation test was performed to determine the correlation.

Results

The mean levels of ferritin and sTfR were 10.2 ± 8.12 and 22.2 ± 7.96 ng/ml, respectively, and the mean sTfR/log ferritin ratio was 29.3 ± 17.65 nmol/L. The mean hepcidin levels were 9.0 ± 3.05 ng/ml. In total, 75.8% of subjects had low ferritin levels, high sTfR (51.5%) levels, and a high sTfR/log ferritin ratio (87.9%). The sTfR levels (r = −0.359; p = 0.003) and sTfR/log ferritin ratio (r = −0.375; p = 0.002) were negatively correlated with Hb levels. There was no correlation between the levels of hepcidin and Hb (r = −0.140; p = 0.264), but there was a positive correlation between ferritin and Hb levels (r = 0.350; p = 0.004).

Conclusion

This study showed a correlation between iron status and Hb levels in overweight and obese women of childbearing age. All the women had erythropoiesis with iron deficiency anaemia. We recommend that overweight and obese women undergo further iron parameters for the detection of early anaemia. In this group, the consumption of foods that enhance iron absorption, such as ascorbic acid, should be encouraged.

Relationship between Selenium and Hematological Markers in Young Adults with Normal Weight or Overweight/Obesity

Selenium deficiency has been linked to anemia of inflammation, which is mediated by hepcidin. However, there are few studies providing evidence of the role of hepcidin in this relationship. In this study, we investigated the interrelationships among selenium biomarkers, hepcidin concentration, and iron status among individuals with overweight/obesity compared to their normal weight counterparts, since obesity is associated with chronic inflammation. A total of 59 college students were recruited for this study. Fasting blood samples were collected for the analysis of iron status, plasma selenoproteins (glutathione peroxidase (GPX) activity and selenoprotein P (SEPP1)), and plasma hepcidin. Subjects completed three-day dietary records to determine average daily nutrient intakes. SEPP1 concentration, GPX activity, and iron status biomarkers (serum iron, transferrin saturation, and hemoglobin concentration) were lower among individuals with overweight/obesity compared with individuals with normal weight, but these differences were not significant (p > 0.05). Regression analysis showed that GPX activity (β = −0.018, p = 0.008) and SEPP1 concentration (β = −1.24, p = 0.03) were inversely associated with hepcidin concentration. The inverse association between selenoproteins and hepcidin concentration supports a potential role of hepcidin as a mediator between selenium and iron status and warrants further studies to better understand this relationship.

Determination of Trace Elements in Adipose Tissue of Obese People by Microwave-Assisted Digestion and Inductively Coupled Plasma Optical Emission Spectrometry

In the present work, analytical method for the determination of trace elements in adipose tissue by means of inductively coupled plasma optical emission spectrometry (ICP-OES) was developed. Adipose tissue from two groups of the patients with obesity (with and without metabolic syndrome) was investigated. The main aim of this study was to reveal some differences and regularities in concentrations of trace elements in adipose tissue between these two groups of the individuals. Moreover, different types of adipose tissue (subcutaneous, preperitoneal, and visceral) were analyzed separately in order to investigate distribution of metals between these types in different groups of obese people. Al, Ba, Ca, Co, Cu, Cr, Fe, K, Li, Mg, Mn, Na, Ni, Sr, and Zn were selected for the quantitative determination. However, only 6 elements (Na, K, Ca, Fe, Mg, and Zn) were determined in all analyzed samples independently of the type of adipose tissue and presence of metabolic disorder of the patient. Concentrations of Ca, Fe, K, and Na were found to be strongly dependent on the type of adipose tissue. Other elements in terms of detection frequency in adipose tissue samples can be arranged in the following sequence Sr (94.7%), Cr (86.2%), Cu (24.6%), Li (18%), Ba (1.8%), Co (0.05%). The concentrations of Al, Mn, and Ni were found to be lower than limit of detection (LOD) in all analyzed samples. Comparison of metal distribution depending on the type of adipose tissue of people with and without metabolic syndrome is discussed in this work.

Relationship between pre-pregnancy body mass index and mineral concentrations in serum and amniotic fluid in pregnant women during labor

The aim of the study was to determine the correlations between body mass index (BMI) values before pregnancy and the concentrations of selected elements (Mg, Co, Cu, Zn, Sr, Cd, Ba, Pb, U, Ca, Cr, Al, Mn, V, Fe) in blood serum and amniotic fluid (AF) in pregnant women. Elemental analysis of serum and amniotic fluid in 225 Polish women (Caucasian/white) showed a relationship between the concentration of minerals in the above-mentioned samples and the pre-pregnancy BMI. Analysis of blood serum was performed by using ICP-MS and it demonstrated that iron concentration was significantly lower in overweight and obese women. Being underweight in pregnant women was associated with a significantly lower concentration of magnesium and cobalt in the blood serum. Both underweight and overweight women were associated with significantly lower concentrations of calcium and strontium in the blood serum. The concentration of cobalt was significantly higher in underweight women. The concentration of lead in the blood serum of overweight and obese women was significantly higher than in other groups. Analysis of the AF showed that the concentration of copper was significantly lower in overweight and obese women, and the concentration of manganese and vanadium significantly higher than in other groups of women. A deficiency in essential minerals and an excess of heavy metals in women may be associated with abnormal body weight and this is important in the etiopathogenesis of pregnancy and fetal development disorders.

Hair Trace Elements in Overweight and Obese Adults in Association with Metabolic Parameters

The objective of the present study was to investigate the level of toxic and essential trace elements in hair of adult overweight and obese persons as well as its association with metabolic parameters. Hair trace element levels were assessed using inductively coupled plasma mass-spectrometry in 112 overweight and obese patients and 106 lean controls. Serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), glucose, uric acid (UA) levels, and cholinesterase (CE) and gamma-glutamyltransferase (GGT) activity were also assessed. Excessive body weight significantly affected hair trace element levels. In particular, hair Co (33%), Cu (13%), I (30%), Mg (2-fold), Mn (25%), Zn (17%), and Ni (21%) levels were lower, whereas Al (14%) and As levels were higher in comparison to those in the control group. Correlation analysis demonstrated the most significant correlations for hair Mg with body weight, BMI, systolic and diastolic blood pressure, and UA, and for hair Al with body weight, BMI, TC, glucose, TG, CE, GGT, and UA. Multiple regression analysis demonstrated that trace elements were not associated with TC and LDL-C levels neither in crude nor in adjusted models. In turn, crude and adjusted models accounted for 25 and 43% of serum TG variance. The most significant associations were observed for hair Al, Fe, Si, and V in adjusted model. The obtained data demonstrate that obesity-related metabolic disorders may be at least partially mediated by altered trace element and mineral levels.

Anemia and Iron Status Among Different Body Size Phenotypes in Chinese Adult Population: a Nation-Wide, Health and Nutrition Survey

Previous studies have shown that there is a controversial relationship between iron homeostasis and obesity. This study aims to explore the relationship of anemia and iron status with different body size phenotypes in adult Chinese population. Using information on iron status-related parameters and lifestyle data from 8462 participants of the 2009 wave of China Health and Nutrition Survey (2009 CHNS), we performed multivariable logistic regression analyses to estimate the odds ratios (ORs) for the risk of anemia and iron parameters according to different body size phenotypes. Participants with higher body mass index (BMI) had a lower anemia prevalence with significant trends in both metabolic status groups (P < 0.001). Serum ferritin, transferrin, and soluble transferrin receptor (sTfR)/log ferritin index were significant in different metabolic status groups and in different body size phenotypes, respectively. The ORs for higher ferritin and transferrin increased across different body size phenotypes in both genders, and for sTfR/log ferritin index decreased (P < 0.01 for trend). This association was still statistically significant after adjustment for multiple confounders. We found an inverse association of BMI levels with the prevalence of anemia and strong association of serum ferritin and transferrin with higher risk of obesity or overweight in both metabolic status groups.

No effects without causes: the Iron Dysregulation and Dormant Microbes hypothesis for chronic, inflammatory diseases

Since the successful conquest of many acute, communicable (infectious) diseases through the use of vaccines and antibiotics, the currently most prevalent diseases are chronic and progressive in nature, and are all accompanied by inflammation. These diseases include neurodegenerative (e.g. Alzheimer's, Parkinson's), vascular (e.g. atherosclerosis, pre-eclampsia, type 2 diabetes) and autoimmune (e.g. rheumatoid arthritis and multiple sclerosis) diseases that may appear to have little in common. In fact they all share significant features, in particular chronic inflammation and its attendant inflammatory cytokines. Such effects do not happen without underlying and initially 'external' causes, and it is of interest to seek these causes. Taking a systems approach, we argue that these causes include (i) stress-induced iron dysregulation, and (ii) its ability to awaken dormant, non-replicating microbes with which the host has become infected. Other external causes may be dietary. Such microbes are capable of shedding small, but functionally significant amounts of highly inflammagenic molecules such as lipopolysaccharide and lipoteichoic acid. Sequelae include significant coagulopathies, not least the recently discovered amyloidogenic clotting of blood, leading to cell death and the release of further inflammagens. The extensive evidence discussed here implies, as was found with ulcers, that almost all chronic, infectious diseases do in fact harbour a microbial component. What differs is simply the microbes and the anatomical location from and at which they exert damage. This analysis offers novel avenues for diagnosis and treatment.

Biomarkers of Nutrition for Development (BOND)-Iron Review

This is the fifth in the series of reviews developed as part of the Biomarkers of Nutrition for Development (BOND) program. The BOND Iron Expert Panel (I-EP) reviewed the extant knowledge regarding iron biology, public health implications, and the relative usefulness of currently available biomarkers of iron status from deficiency to overload. Approaches to assessing intake, including bioavailability, are also covered. The report also covers technical and laboratory considerations for the use of available biomarkers of iron status, and concludes with a description of research priorities along with a brief discussion of new biomarkers with potential for use across the spectrum of activities related to the study of iron in human health.The I-EP concluded that current iron biomarkers are reliable for accurately assessing many aspects of iron nutrition. However, a clear distinction is made between the relative strengths of biomarkers to assess hematological consequences of iron deficiency versus other putative functional outcomes, particularly the relationship between maternal and fetal iron status during pregnancy, birth outcomes, and infant cognitive, motor and emotional development. The I-EP also highlighted the importance of considering the confounding effects of inflammation and infection on the interpretation of iron biomarker results, as well as the impact of life stage. Finally, alternative approaches to the evaluation of the risk for nutritional iron overload at the population level are presented, because the currently designated upper limits for the biomarker generally employed (serum ferritin) may not differentiate between true iron overload and the effects of subclinical inflammation.

Association between pre-pregnancy weight status and maternal micronutrient status in early pregnancy

OBJECTIVE

Inadequate maternal micronutrient status during pregnancy can lead to short- and long-term health risks for mother and offspring. The present study investigated the association between pre-pregnancy weight status and micronutrient status during pregnancy.

DESIGN

Maternal blood samples were collected during early pregnancy (median 13, interquartile range 12-15 weeks) and were assayed for serum folate, ferritin, Fe and vitamin B12. Regression modelling was used to assess the association between pre-pregnancy underweight, normal weight, overweight and obesity, and micronutrient levels, as well as the odds for deficiencies.

SETTING

The Amsterdam Born Children and their Development (ABCD) study, the Netherlands.

SUBJECTS

Women with singleton pregnancies without diabetes (n 4243).

RESULTS

After adjustment for covariates, overweight women and obese women had lower (β; 95 % CI) folate (-1·2; -2·2, -0·2 and -2·3; -4·0, -0·7 nmol/l, respectively) and Fe (-1·7; -2·3, -1·1 and -3·6; -4·7, -2·6 μmol/l, respectively) levels than women with normal weight. Furthermore, overweight women had 6 % (95 % CI -9, -3 %) and obese women had 15 % (-19, -10 %), lower vitamin B12 levels, and obese women had 19 % (6, 32 %) higher ferritin levels, than normal-weight women. Obese women had higher odds (OR; 95 % CI) for folate deficiency (2·03; 1·35, 3·06), Fe deficiency (3·26; 2·09, 5·08) and vitamin B12 deficiency (2·05; 1·41, 2·99) than women with normal weight. Underweight was not associated with micronutrient status.

CONCLUSIONS

During early pregnancy, women with pre-pregnancy overweight and obesity had lower serum folate, Fe and vitamin B12 status. This resulted in increased risk of serum folate, Fe and vitamin B12 deficiencies in women with obesity.

Ablation of hephaestin and ceruloplasmin results in iron accumulation in adipocytes and type 2 diabetes

Little is known about the iron efflux mechanism in adipocytes. Here, we used hephaestin (Heph) and ceruloplasmin (Cp) single-knockout (KO) mice and Heph/Cp double-KO mice to investigate the roles of multicopper ferroxidases (MCFs) in this process. We show that both HEPH and CP are expressed in subcutaneous adipose tissue. Ablation of either MCF leads to a compensatory increase in the other, which contributes to the balance of iron status. However, ablation of both MCFs together induces severe iron deposition in adipocytes which is associated with decreased adiponectin and leptin mRNA expression. Furthermore, Heph/Cp KO mice display disordered carbohydrate metabolism characterized as type 2 diabetes. Together, these results demonstrate the protective roles of HEPH and CP in preventing iron overload in adipocytes.

Serum copper, zinc, and iron levels, and markers of carbohydrate metabolism in postmenopausal women with prediabetes and type 2 diabetes mellitus

The objective of the present study was to evaluate serum level of copper, zinc, iron and metabolic parameters in postmenopausal women with diabetes. A total of 413 postmenopausal women were enrolled in the current study. Women were divided into 4 groups with equal age and body mass index according to glycated hemoglobin (HbA_1c) levels (≤5.5; 5.5-6.0; 6.0-6.5; >6.5%). Serum Fe, Cu, and Zn levels were assessed using inductively-coupled plasma mass-spectrometry. Blood HbA_1c, serum glucose, insulin, C-reactive protein (CRP), ferritin, and ceruloplasmin (Cp) were assessed using commercial kits. Homeostatic model assessment insulin resistance (HOMA-IR) and transferrin (Tf) saturation were calculated. The obtained data demonstrate that every 0.5% increase in HbA_1c levels from 5.5% is associated with a significant elevation of glucose, insulin, CRP, and HOMA-IR values. Diabetic patients were characterized by significantly higher Fe (11%), Cu (8%), and Zn (6%) levels as compared to the controls. At the same time, the overall trend to increased metal levels in association with HbA_1c was detected only for Fe (p<0.05) and Cu (p<0.05). Serum ferritin levels in diabetic women was 3-fold higher than in the controls, whereas Tf saturation was decreased by 35%. Serum Cp levels were significantly increased by 19% in prediabetes, whereas in diabetic postmenopausal women no such increase was observed. A significant elevation of total metal concentration in diabetic subjects without a concomitant elevation of transport proteins may be indicative of increased levels of "free" Fe and Cu, known to be toxic.

The impacts of maternal iron deficiency and being overweight during pregnancy on neurodevelopment of the offspring

Both maternal Fe deficiency (ID) and being overweight or obese (Ow/Ob, BMI≥25 kg/m2) may negatively affect offspring brain development. However, the two risk factors correlate and their independent effects on infant neurodevelopment are unclear. PREOBE is a prospective observational study that included 331 pregnant Spanish women, of whom 166 had pre-gestational Ow/Ob. Fe status was analysed at 34 weeks and at delivery, and babies were assessed using Bayley III scales of neurodevelopment at 18 months. In confounder-adjusted analyses, maternal ID at 34 weeks was associated with lower composite motor scores at 18 months (mean 113·3 (sd 9·9) v. 117·1 (sd 9·2), P=0·039). Further, the offspring of mothers with ID at delivery had lower cognitive scores (114·0 (sd 9·7) v. 121·5 (sd 10·9), P=0·039) and lower receptive, expressive and composite (99·5 (sd 8·6) v. 107·6 (sd 8·3), P=0·004) language scores. The negative associations between maternal ID at delivery and Bayley scores remained even when adjusting for maternal Ow/Ob and gestational diabetes. Similarly, maternal Ow/Ob correlated with lower gross motor scores in the offspring (12·3 (sd 2·0) v. 13·0 (sd 2·1), P=0·037), a correlation that remained when adjusting for maternal ID. In conclusion, maternal ID and pre-gestational Ow/Ob are both negatively associated with Bayley scores at 18 months, but independently and on different subscales. These results should be taken into account when considering Fe supplementation for pregnant women.

Early High-Fat Feeding Induces Alteration of Trace Element Content in Tissues of Juvenile Male Wistar Rats

The primary objective of the current study was to assess the influence of early high-fat feeding on tissue trace element content in young male Wistar rats. Twenty weanling male Wistar rats were divided into two groups fed standard (STD) or high-fat diet (HFD) containing 10 and 31.6 % of total calories from fat, respectively, for 1 month. Serum lipid spectrum, apolipoproteins, glucose, insulin, adiponectin, and leptin levels were assessed. The level of trace elements was estimated using inductively coupled plasma mass spectrometry. High-fat feeding significantly increased epidydimal (EDAT) and retroperitoneal adipose tissue (RPAT), as well as total adipose tissue mass by 34, 103, and 59 %, respectively. Serum leptin levels in HFD animals were twofold higher than those in the control rats. No significant difference in serum lipid spectrum, apolipoproteins, glucose, adiponectin, and insulin was detected between the groups. HFD significantly altered tissue trace element content. In particular, HFD-fed animals were characterized by significantly lower levels of Cu, I, Mn, Se, and Zn in the liver; Cr, V, Co, Cu, Fe, and I content of EDAT; Co, Cu, I, Cr, V, Fe, and Zn concentration in RPAT samples. At the same time, only serum Cu was significantly depressed in HFD-fed animals as compared to the control ones. Hair Co, Mn, Si, and V levels were significantly increased in comparison to the control values, whereas Se and I content was decreased. HFD feeding induced excessive adiposity and altered tissue trace element content in rats without insulin resistance, adiponectin deficiency, and proatherogenic state. Hypothetically, trace element disbalance may precede obesity-associated metabolic disturbances.

Iron mediated toxicity and programmed cell death: A review and a re-examination of existing paradigms

Iron is an essential micronutrient that is problematic for biological systems since it is toxic as it generates free radicals by interconverting between ferrous (Fe²⁺) and ferric (Fe³⁺) forms. Additionally, even though iron is abundant, it is largely insoluble so cells must treat biologically available iron as a valuable commodity. Thus elaborate mechanisms have evolved to absorb, re-cycle and store iron while minimizing toxicity. Focusing on rarely encountered situations, most of the existing literature suggests that iron toxicity is common. A more nuanced examination clearly demonstrates that existing regulatory processes are more than adequate to limit the toxicity of iron even in response to iron overload. Only under pathological or artificially harsh situations of exposure to excess iron does it become problematic. Here we review iron metabolism and its toxicity as well as the literature demonstrating that intracellular iron is not toxic but a stress responsive programmed cell death-inducing second messenger.

Effect of Spirulina maxima Supplementation on Calcium, Magnesium, Iron, and Zinc Status in Obese Patients with Treated Hypertension

The effects of Spirulina maxima supplementation on calcium, magnesium, iron, and zinc status were studied in a double-blind placebo-controlled trial of 50 obese subjects with treated hypertension, each randomized to receive 2 g of spirulina or a placebo daily for 3 months. At baseline and after treatment, the calcium, magnesium, iron, and zinc concentration in plasma was assessed. It was found that 3 months of S. maxima supplementation resulted in a significant decrease in the iron level in the plasma of obese patients. In conclusion, this is the first clinical study on the influence of spirulina supplementation on mineral status in obese patients with hypertension. Spirulina supplementation affects the iron status of obese Caucasians with well-treated hypertension.

Lactoferrin, a Pleiotropic Protein in Health and Disease

SIGNIFICANCE

Lactoferrin (Lf) is a nonheme iron-binding glycoprotein strongly expressed in human and bovine milk and it plays many functions during infancy such as iron homeostasis and defense against microorganisms. In humans, Lf is mainly expressed in mucosal epithelial and immune cells. Growing evidence suggests multiple physiological roles for Lf after weaning.

RECENT ADVANCES

The aim of this review is to highlight the recent advances concerning multifunctional Lf activities.

CRITICAL ISSUES

First, we will provide an overview of the mechanisms related to Lf intrinsic synthesis or intestinal absorption as well as its interaction with a wide spectrum of mammalian receptors and distribution in organs and cell types. Second, we will discuss the large variety of its physiological functions such as iron homeostasis, transportation, immune regulation, oxidative stress, inflammation, and apoptosis while specifying the mechanisms of action. Third, we will focus on its recent physiopathology implication in metabolic disorders, including obesity, type 2 diabetes, and cardiovascular diseases. Additional efforts are necessary before suggesting the potential use of Lf as a diagnostic marker or as a therapeutic tool.

FUTURE DIRECTIONS

The main sources of Lf in human cardiometabolic disorders should be clarified to identify new perspectives for future research and develop new strategies using Lf in therapeutics. Antioxid. Redox Signal. 24, 813-836.

Iron Overload Coordinately Promotes Ferritin Expression and Fat Accumulation in Caenorhabditis elegans

The trace element iron is crucial for living organisms, since it plays essential roles in numerous cellular functions. Systemic iron overload and the elevated level of ferritin, a ubiquitous intracellular protein that stores and releases iron to maintain the iron homeostasis in cells, has long been epidemiologically associated with obesity and obesity-related diseases. However, the underlying mechanisms of this association remain unclear. Here, using Caenorhabditis elegans, we show that iron overload induces the expression of sgk-1, encoding the serum and glucocorticoid-inducible kinase, to promote the level of ferritin and fat accumulation. Mutation of cyp-23A1, encoding a homolog of human cytochrome P450 CYP7B1 that is related to neonatal hemochromatosis, further enhances the elevated expression of ftn-1, sgk-1, and fat accumulation. sgk-1 positively regulates the expression of acs-20 and vit-2, genes encoding homologs of the mammalian FATP1/4 fatty acid transport proteins and yolk lipoproteins, respectively, to facilitate lipid uptake and translocation for storage under iron overload. This study reveals a completely novel pathway in which sgk-1 plays a central role to synergistically regulate iron and lipid homeostasis, offering not only experimental evidence supporting a previously unverified link between iron and obesity, but also novel insights into the pathogenesis of iron and obesity-related human metabolic diseases.

Deranged iron status in psoriasis: the impact of low body mass

BACKGROUND

Iron deficiency (ID) frequently complicates inflammatory-mediated chronic disorders, irrespective of anaemia. Psoriasis is a chronic, immune-mediated skin disease with systemic pro-inflammatory activation; thus, these patients may be prone to develop ID. ID adversely affects immune cells function, which can further contribute to disease progression. This study investigates iron status in psoriasis.

METHODS

Serum concentrations of ferritin, transferrin saturation (Tsat), soluble transferrin receptor (sTfR), and hepcidin were assessed as the biomarkers of iron status in 39 patients with psoriasis (17 men, age: 47 ± 10 years) and 44 healthy subjects (30 men, age: 53 ± 6 years).

RESULTS

Compared with healthy controls, patients with psoriasis demonstrated similar haematologic status but deranged iron status as evidenced by decreased Tsat and elevated sTfR (negative tissue iron balance) and low levels of hepcidin (depleted iron stores) (all P < 0.05 vs. controls). In patients, the levels of interleukin-6 (level of pro-inflammatory activation) significantly correlated with hepcidin (R = 0.54), but not with ferritin, Tsat, and sTfR. Biomarkers reflecting ID were not associated with the severity of the disease (assessed with the Psoriasis Area and Severity Index) but significantly correlated low body mass index (BMI). Patients with BMI < 24 kg/m(2) compared with those with BMI ≥ 24 kg/m(2) demonstrated lower levels of ferritin (40 ± 30 vs. 186 ± 128 ng/mL, P < 0.001) and hepcidin (4.9 ± 2.3 vs. 10.7 ± 6.7 ng/mL, P = 0.03).

CONCLUSION

Psoriasis is associated with deranged iron status characterized by depleted iron stores with concomitant unmet cellular iron requirements. The magnitude of these abnormalities is particularly strong in patients with low body mass index. Whether iron deficiency may become a therapeutic target in psoriasis needs to be investigated.

Iron Metabolism Dysregulation and Cognitive Dysfunction in Pediatric Obesity: Is There a Connection?

Obesity and iron deficiency (ID) are two of the most common nutritional disorders in the world. In children both conditions deserve particular attention. Several studies revealed an association between obesity and iron deficiency in children and, in some cases, a reduced response to oral supplementation. The connecting mechanism, however, is not completely known. This review is focused on: (1) iron deficiency in obese children and the role of hepcidin in the connection between body fat and poor iron status; (2) iron status and consequences on health, in particular on cognitive function; (3) cognitive function and obesity; (4) suggestion of a possible link between cognitive dysfunction and ID in pediatric obesity; and implications for therapy and future research.

Conflicting effects of BMI and waist circumference on iron status

The association between obesity and iron status has a long history and is still receiving attention. However comparative analysis of the association between general obesity (BMI) and visceral obesity (waist circumference) with iron status has not been extensively researched. The aim of the present study is thus to determine if body mass index and waist circumference have the same correlation with iron status. One thousand one hundred and thirty people (225 men and 905 women) aged 30 years and above participated in this study. Anthropometric parameters, haemoglobin, iron and total iron binding capacity concentrations were measured using standard methods. Percentage transferrin saturation was calculated and ferritin concentrations were measured using an enzyme linked immunosorbent assay. Obese or overweight women had significantly lower iron and transferrin saturation concentration when compared to non-obese women. In contrast, women with high waist circumference had comparable plasma iron and transferrin saturation to women with normal waist circumference. Partial correlation analysis and linear regression analysis showed that BMI is negatively and significantly associated with plasma iron, transferrin saturation, Hb and ferritin concentration, whilst waist circumference is positively but insignificantly associated with plasma iron, transferrin saturation, Hb and ferritin concentration. Binary regression analysis showed that obese or overweight people are more likely to have iron deficiency, whilst those with raised waist circumference are more likely to have iron overload. Multivariate analysis showed that body mass index is negatively and significantly associated with low iron status, while waist circumference is positively and insignificantly associated with iron status. This is supported by a comparison of plasma iron, transferrin saturation and ferritin concentrations in participants with high body mass index and normal waist circumference and participants with normal body mass index and high waist circumference to those participants having normal body mass index and normal waist circumference. The present study suggests that in women body mass index is associated with low plasma iron, transferrin saturation and ferritin concentrations, while waist circumference is associated with high plasma iron, transferrin saturation and ferritin concentrations.

Pleiotropic actions of iron balance in diabetes mellitus

As an essential element, iron plays a central role in many physiological processes, including redox balance, inflammation, energy metabolism, and environment sensing. Perturbations in iron homeostasis are associated with several conditions, including hyperglycemia and diabetes, both of which have been studied in patients and animal models. To clarify the pleiotropic role of iron homeostasis in diabetes development, the early studies on diseases with iron-overload, studies on clinical iron depletion therapies, associations between iron-related genetic polymorphisms and diabetes, and etiological mechanisms underlying iron perturbations-impaired insulin secretion and insulin sensitivity were carefully reviewed and discussed. Hereditary hemochromatosis, transfusion-dependent thalassemia, and excess heme iron intake can increase the risk of developing diabetes. Genetically modified mice and mice fed a high-iron diet present with discrepant phenotypes due to differences in tissue iron distribution. Moreover, several genetic polymorphisms related to iron homeostasis have been associated with the risk of developing diabetes. Tightly controlled iron metabolism is essential for insulin secretion and insulin sensitivity, and iron overload in pancreatic islets alters reactive oxygen species (ROS) generation, as well as hypoxia-inducible factor-1α (HIF-1α) stability and adenosine triphosphate (ATP) synthesis, thereby impairing the function and viability of β-cells. Decreased levels of adiponectin, macrophage-mediated inflammation, and ROS-mediated liver kinase B1 (LKB1)/adenosine monophosphate-activated protein kinase (AMPK) activation can contribute to iron overload-induced insulin resistance, whereas iron deficiency could also participate in obesity-related inflammation, hypoxia, and insulin resistance. Because iron homeostasis is closely correlated with many metabolic processes, future studies are needed in order to elucidate the finely tuned network among iron homeostasis, carbohydrate and lipid metabolism, inflammation, and hypoxia.

Oxidative stress in obesity: a critical component in human diseases

Obesity, a social problem worldwide, is characterized by an increase in body weight that results in excessive fat accumulation. Obesity is a major cause of morbidity and mortality and leads to several diseases, including metabolic syndrome, diabetes mellitus, cardiovascular, fatty liver diseases, and cancer. Growing evidence allows us to understand the critical role of adipose tissue in controlling the physic-pathological mechanisms of obesity and related comorbidities. Recently, adipose tissue, especially in the visceral compartment, has been considered not only as a simple energy depository tissue, but also as an active endocrine organ releasing a variety of biologically active molecules known as adipocytokines or adipokines. Based on the complex interplay between adipokines, obesity is also characterized by chronic low grade inflammation with permanently increased oxidative stress (OS). Over-expression of oxidative stress damages cellular structures together with under-production of anti-oxidant mechanisms, leading to the development of obesity-related complications. The aim of this review is to summarize what is known in the relationship between OS in obesity and obesity-related diseases.