Inflammatory and oxidative status in European captive black rhinoceroses: A link with Iron Overload Disorder?

Iron Overload Disorder (IOD) is a syndrome developed by captive browsing rhinoceroses like black rhinoceroses (Diceros bicornis), in which hemosiderosis develops in vital organs while free iron accumulates in the body, potentially predisposing to various secondary diseases. Captive grazing species like white rhinoceroses (Ceratotherium simum) do not seem to be affected. The authors hypothesized that inflammation and oxidative stress may be implicated in the pathogenesis of IOD in captive black rhinoceroses, making this syndrome a potential common denominator to various diseases described in captivity in this species. In this prospective study, 15 black (BR) and 29 white rhinoceroses (WR) originating from 22 European zoos were blood-sampled and compared for their iron status (serum iron), liver/muscle biochemical parameters (AST, GGT, cholesterol), inflammatory status (total proteins, protein electrophoresis) and oxidative stress markers (SOD, GPX, dROMs). Results showed higher serum iron and liver enzyme levels in black rhinoceroses (P < 0.01), as well as higher dROMs (P < 0.01) and a trend for higher GPX (P = 0.06) levels. The albumin/globulin ratio was lower in black rhinoceroses (P < 0.05) due to higher α2-globulin levels (P < 0.001). The present study suggests a higher inflammatory and oxidative profile in captive BR than in WR, possibly in relation to iron status. This could be either a consequence or a cause of iron accumulation. Further investigations are needed to assess the prognostic value of the inflammatory and oxidative markers in captive black rhinoceroses, particularly for evaluating the impact of reduced-iron and antioxidant-supplemented diets.

Major Depression in Children with Transfusion-Dependent Thalassemia Is Strongly Associated with the Combined Effects of Blood Transfusion Rate, Iron Overload, and Increased Pro-inflammatory Cytokines.

Beta-thalassemia major patients are treated with repeated blood transfusions, which may cause iron overload, which in turn may induce immune aberrations, and show an increased risk of depression. The aim of the present study is to examine whether repeated blood transfusions, iron overload, and immune-inflammatory responses are associated with depression in children (6-12 years) with transfusion-dependent thalassemia (TDT). The Children's Depression Inventory (CDI), iron status (serum iron, ferritin, transferrin, TS%), and serum levels of CCL11, IL-1ß, IL-10, and TNF-α were measured in TDT with (n = 54) and without (n = 57) a major depression-like episode (MDLE) and in healthy children (n = 55). The results show that MDLE due to TDT is associated with a greater number of blood transfusions and increased iron overload and IL-1ß levels. Partial least squares path analysis shows that 68.8% of the variance in the CDI score is explained by the number of blood transfusions, iron overload, and increased levels of IL-1ß and TNF-α. The latter two cytokines partly mediate the effects of iron overload on the CDI score, while the effects of blood transfusions on the CDI score are partly mediated by iron overload and the path from iron overload to immune activation. Iron overload is also associated with increased IL-10 and lower CCL11 levels, but these alterations are not significantly associated with depression. In conclusion, blood transfusions may be causally related to MDLE in TDT children and their effects are in part mediated by increased iron overload and the consequent immune-inflammatory response. The results suggest that effects of iron overload and its consequences including inflammation and oxidative stress toxicity may cause MDLE. Current treatment modalities with folic acid and vitamin C are insufficient to attenuate iron overload and immune-inflammatory responses and to prevent MDLE in children with TDT.

Modulation of urinary siderophores by the diet, gut microbiota and inflammation in mice.

Mammalian siderophores are believed to play a critical role in maintaining iron homeostasis. However, the properties and functions of mammalian siderophores have not been fully clarified. In this study, we have employed Chrome Azurol S (CAS) assay which is a well-established method for bacterial siderophores study, to detect and quantify mammalian siderophores in urine samples. Our study demonstrates that siderophores in urine can be altered by diet, gut microbiota and inflammation. C57BL/6 mice, fed on plant-based chow diets which contain numerous phytochemicals, have more siderophores in the urine compared to those fed on purified diets. Urinary siderophores were up-regulated in iron overload conditions, but not altered by other tested nutrients status. Further, germ-free mice displayed 50% reduced urinary siderophores, in comparison to conventional mice, indicating microbiota biotransformation is critical in generating or stimulating host metabolism to create more siderophores. Altered urinary siderophores levels during inflammation suggest that host health conditions influence systemic siderophores level. This is the first report to measure urinary siderophores as a whole, describing how siderophores levels are modulated under different physiological conditions. We believe that our study opens up a new field in mammalian siderophores research and the technique we used in a novel manner has the potential to be applied to clinical purpose.

Iron Regulation of Pancreatic Beta-Cell Functions and Oxidative Stress.

Dietary advice is the cornerstone in first-line treatment of metabolic diseases. Nutritional interventions directed at these clinical conditions mainly aim to (a) improve insulin resistance by reducing energy-dense macronutrient intake to obtain weight loss and (b) reduce fluctuations in insulin secretion through avoidance of rapidly absorbable carbohydrates. However, even in the majority of motivated patients selected for clinical trials, massive efforts using this approach have failed to achieve lasting efficacy. Less attention has been given to the role of micronutrients in metabolic diseases. Here, we review the evidence that highlights (a) the importance of iron in pancreatic beta-cell function and dysfunction in diabetes and (b) the integrative pathophysiological effects of tissue iron levels in the interactions among the beta cell, gut microbiome, hypothalamus, innate and adaptive immune systems, and insulin-sensitive tissues. We propose that clinical trials are warranted to clarify the impact of dietary or pharmacological iron reduction on the development of metabolic disorders.

The warm temperature acclimation protein (Wap65) has an important role in the inflammatory response of turbot (Scophthalmus maximus).

Wap65 is a molecule similar to the mammalian hemopexin that is a serum glycoprotein produced mainly by the liver with high affinity to heme. Its primary role is participating in iron metabolism scavenging heme that is released into the plasma and transporting it to the liver. It has been reported an important role of hemopexin in the inflammation as an acute-phase protein and its production is up-regulated by pro-inflammatory cytokines. There are also some evidences suggesting this immune-induction in fish Wap65 genes. Most teleost species presents two Wap65 genes but their physiological functions have not been completely elucidated; in fact, the transcriptional patterns of Wap65 genes to stimulatory treatments are variable and contradictory. In the present study two Wap65 genes, Wap65-1 and Wap65-2, have been characterized for the first time in turbot (Scophthalmus maximus). Their constitutive expression and differential modulation by thermal treatments, immune challenges (bacterial and viral), as well as iron supplementation, have been investigated. Both genes were mainly expressed in liver, but they were detected in all tested tissues. Whereas Wap65-1 and Wap65-2 were up-regulated by temperature rise and bacterial challenge, VHSV infection inhibited the expression of both genes. Moreover, iron-dextran administration induced only the overexpression of Wap65-1. Interestingly, these induction were observed in head kidney buy not in liver. The effect of Wap65 protein purified from turbot serum by hemin-agarose affinity chromatography was also studied to demonstrate a possible anti-inflammatory role, analyzing its inhibitory effect on leucocytes migration induced by zymosan injection to the peritoneal cavity.

Interleukin-6 and lipopolysaccharide modulate hepcidin mRNA expression by HepG2 cells.

Iron homeostasis is controlled by hepcidin (Hpc) as well as other ways. Hpc expression is regulated by iron (Fe) storage and by inflammation, but the joint effect of both stimuli remains unclear. We studied the modulatory role of inflammatory agents (IL6 and LPS) over Hpc and DMT1 mRNA expression in HepG2 cells preloaded with Fe. HepG2 cells were preloaded with different Fe concentrations (holo-Tf or Fe-NTA) and then incubated with IL6 or LPS. We measured intracellular Fe levels by AAS with graphite furnace, transferrin receptor (TfR) by ELISA and mRNA relative abundance of Hpc and DMT1 by qRT-PCR. The maximum effect on Fe uptake was observed in cells incubated with 30 ng/ml IL6 (p < 0.01) and 500 ng/ml LPS (p < 0.05). In HepG2 cells preloaded with holo-Tf or Fe-NTA and challenged with IL6 and LPS, we observed a decreased: (a) Hpc mRNA relative abundance (two-way ANOVA: p < 0.05 and p < 0.001, respectively), (b) DMT1 mRNA relative abundance and TfR1 protein levels (two-way ANOVA: p < 0.001), and (c) intracellular Fe concentration (two-way ANOVA: p < 0.001 and p < 0.01, respectively) compared to control cells incubated only with Fe (holo-Tf or Fe-NTA). Our results support the idea that Fe storage and inflammation act together to regulate Fe homeostasis and suggest a negative regulation in this hepatic cellular model to prevent excessive increases in Hpc.