Effects of TNF-alpha and IL-1beta on iron metabolism by A549 cells and influence on cytotoxicity

Synergistic action of lactoferrin in enhancing the safety and effectiveness of docetaxel treatment against prostate cancer

BACKGROUND

Tumor metastasis is promoted by an immunosuppressive environment. Lactoferrin (Lf) is known to regulate immunological activity in tumor cells and inhibit processes associated with tumor metastasis. A delivery of lactoferrin with docetaxel (DTX) in prostate cancer cells in the form of DTX-loaded lactoferrin nanoparticles (DTX-LfNPs) would provide a dual activity wherein the lactoferrin affects metastasis and DTX chemotherapeutically inhibits mitosis and cell division.

METHODS

DTX-LfNPs were prepared using sol-oil chemistry, and particles were characterized using transmission electron microscopy. Antiproliferation activity was analyzed in prostate cancer Mat Ly Lu cells. The target localization and efficacy of DTX-LfNPs were studied in an orthotopic prostate cancer induced by Mat Ly Lu cells in a rat model. Biomarkers were estimated using ELISA and biochemical reactions.

RESULTS

DTX was loaded in pure Lf nanoparticles without involving any chemical modification and conjugation, thus when these nanoparticles are delivered in cancer cells both DTX and Lf will be present in biologically active forms. DTX-LfNps exhibit a spherical morphology of dimension of 60 ± 10 nm with DTX Encapsulation Efficiency of 62.06 ± 4.07%. Competition experiments using soluble Lf confirm that DTX-LfNPs enter prostate cancer cells through the Lf receptor. DTX-LfNPs exhibit an improved anti-proliferative activity by 2.5 times compared to DTX. Further, analysis of the bioavailability of the drug in the prostate showed that DTX-LfNPs increased drug bioavailability in the prostate by two times more than the DTX. The analysis of efficacy in the Mat Ly Lu cells-induced orthotopic prostate cancer model showed that DTX-LfNPs significantly enhanced the anti-cancer activity compared to DTX in terms of regression of weight and volume of prostate tissue, the efficacy was confirmed by histochemical analysis. Lf provides synergistic activity along with DTX in inhibiting metastasis as assessed by the reduction of lactate dehydrogenase, alkaline phosphatase, TNF alpha, and IFNγ. LfNPs facilitate higher DTX localization along with Lf-mediated protection from DTX-associated toxicity to neutrophils and kidneys as assessed by C-reactive protein, creatinine, and uric acid. Thus, DTX LfNPs show a dual action by enhancing DTX bioavailability in prostate along with Lf-mediated suppression of metastasis as well as DTX-associated toxicity.

CONCLUSION

In conclusion, DTX-LfNPs enhance the bioavailability of DTX in the prostate along with Lf-assisted improvement in inhibition of tumor metastasis and drug-associated toxicity.

Determination of functional similarity of biosimilar H9P2S from an investigational CHO clone with Adalimumab

Biosimilars, which are replicas of innovator pharmaceuticals, constitute the most significant share of biopharmaceutical products. These products are associated with structural and manufacturing complexities and are hence considered as similar to innovator drugs. Adalimumab is a monoclonal antibody that has been approved by the US FDA for blocking TNF-α. Adalimumab, also known as Humira, is preferred over other anti-TNF-α mAbs because of its lower immunogenicity and enhanced clinical efficacy. As cost-effective mAb development is still a challenging area, we developed an in-house stable CHO-K1 cell line for the production of recombinant monoclonal mAb against TNF-α. This clone yielded H9P2S, as a biosimilar against TNF-α, for which several functional assays were conducted to prove its biosimilarity to Adalimumab. Two batches of H9P2S and their subsequent dilutions were compared with Adalimumab. H9P2S and Adalimumab showed highly similar TNF-α binding and neutralizing activities, confirming the suitability of our clone for yielding biosimilar drugs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03384-z.

Evaluation of iron, ferritin, copper, and ceruloplasmin along with proviral load in human T lymphotropic virus type 1-associated myelopathy

Human T-cell lymphotropic virus type 1 (HTLV-1) infection can cause HTLV-I-associated myelopathy (HAM). In this study, we evaluated the levels of serum iron, ferritin, copper, and ceruloplasmin, and their correlations with HTLV-1 proviral load (PVL) and standard indices of HAM severity. In total, 114 subjects were recruited in this cross sectional study in Qaem Hospital, Mashhad, Iran between 2017 and 2018, including 36 HAM and 32 asymptomatic cases (ACs) and 46 healthy people (HSs). The clinical examination and evaluation of serum levels of biochemical factors and proviral load were performed. The PVL in HAM and ACs were 1835.49 ± 382.81 and 280.97 ± 67.41 copies/104 PBMCs, which statistically differed. Significant differences were also observed in plasma levels of iron, copper, and ceruloplasmin, among the three groups, while ferritin level was not considerably different. For HAM severity, the mean Osame motor disability scale (OMDS) and overactive bladder-validated-8-questionnaire (OABV-8) scores were 4.97 ± 0.38 and 15.75 ± 0.83, respectively, that had no significant correlations with the biochemical variables. Even though the studied elements in HAM group did not affect the severity of the disease, the levels of copper and ceruloplasmin might be determinants of the development and progression of HAM, as they are shown to play role in progression of other neurological diseases.

Iron Deficiency in Vegetarian and Omnivorous Individuals: Analysis of 1340 Individuals

The objective of this study was to evaluate the serum levels of ferritin and the prevalence of iron deficiency in vegan and omnivorous individuals by taking into account the presence of elements that cause an elevation of ferritin levels, such as increased homeostatic model assessment of insulin resistance (HOMA-IR), body mass index (BMI), and high-sensitivity C-reactive protein (hs-CRP) values. The parameters were evaluated in 1340 individuals, i.e., 422 men and 225 women who do not menstruate and 693 women who do menstruate, based on omnivorous or vegetarian eating habits. The progressive increase in BMI, HOMA-IR, and inflammation caused an elevation in ferritin concentration, regardless of the eating habits in the groups studied. In the overall sample, omnivores had a higher prevalence of obesity, higher ferritin levels, and a lower prevalence of iron deficiency (ferritin < 30 ng/mL). However, after the exclusion of individuals with inflammation (with overweight/obesity and elevated hs-CRP levels), the actual iron deficiency was assessed and was not higher among vegetarians, except in women with regular menstrual cycles. Our data show that nutritional status and inflammation levels affect ferritin levels and may interfere with the correct diagnosis of iron deficiency in both vegetarian and omnivorous individuals. Compared to vegetarians, women who do not menstruate and men had the same prevalence of iron deficiency when following an omnivorous diet.

Hypoferremia is Associated With Increased Hospitalization and Oxygen Demand in COVID-19 Patients

Iron metabolism might play a crucial role in cytokine release syndrome in COVID-19 patients. Therefore, we assessed iron metabolism markers in COVID-19 patients for their ability to predict disease severity. COVID-19 patients referred to the Heidelberg University Hospital were retrospectively analyzed. Patients were divided into outpatients (cohort A, n = 204), inpatients (cohort B, n = 81), and outpatients later admitted to hospital because of health deterioration (cohort C, n = 23). Iron metabolism parameters were severely altered in patients of cohort B and C compared to cohort A. In multivariate regression analysis including age, gender, CRP and iron-related parameters only serum iron and ferritin were significantly associated with hospitalization. ROC analysis revealed an AUC for serum iron of 0.894 and an iron concentration <6 μmol/l as the best cutoff-point predicting hospitalization with a sensitivity of 94.7% and a specificity of 67.9%. When stratifying inpatients in a low- and high oxygen demand group serum iron levels differed significantly between these two groups and showed a high negative correlation with the inflammatory parameters IL-6, procalcitonin, and CRP. Unexpectedly, serum iron levels poorly correlate with hepcidin. We conclude that measurement of serum iron can help predicting the severity of COVID-19. The differences in serum iron availability observed between the low and high oxygen demand group suggest that disturbed iron metabolism likely plays a causal role in the pathophysiology leading to lung injury.

Genetic predisposition for inflammation exacerbates effects of striatal iron content on cognitive switching ability in healthy aging

Non-heme iron homeostasis interacts with inflammation bidirectionally, and both contribute to age-related decline in brain structure and function via oxidative stress. Thus, individuals with genetic predisposition for inflammation may be at greater risk for brain iron accumulation during aging and more vulnerable to cognitive decline. We examine this hypothesis in a lifespan sample of healthy adults (N = 183, age 20-94 years) who underwent R2*-weighted magnetic resonance imaging to estimate regional iron content and genotyping of interleukin-1beta (IL-1β), a pro-inflammatory cytokine for which the T allelle of the single nucleotide polymorphism increases risk for chronic neuroinflammation. Older age was associated with greater striatal iron content that in turn accounted for poorer cognitive switching performance. Heterozygote IL-1β T-carriers demonstrated poorer switching performance in relation to striatal iron content as compared to IL-1β C/C counterparts, despite the two groups being of similar age. With increasing genetic inflammation risk, homozygote IL-1β T/T carriers had lesser age-related variance in striatal iron content as compared to the other groups but showed a similar association of greater striatal iron content predicting poorer cognitive switching. Non-heme iron and inflammation, although necessary for normal neuronal function, both promote oxidative stress that when accumulated in excess, drives a complex mechanism of neural and cognitive decline in aging.

Quantitative Susceptibility Mapping of the Thalamus: Relationships with Thalamic Volume, Total Gray Matter Volume, and T2 Lesion Burden

BACKGROUND AND PURPOSE

Both thalamic iron deposition and atrophy have been reported in patients with multiple sclerosis compared with healthy controls, but how they are related is unclear. The purpose of this study was to understand the pathophysiologic basis for this iron deposition.

MATERIALS AND METHODS

Ninety-five patients with relapsing-remitting multiple sclerosis underwent 3T MR imaging with a standardized protocol that included quantitative susceptibility mapping to measure iron concentration and a 3D T1 echo-spoiled gradient-echo sequence to obtain thalamic volumes. Volumes of interest were manually delineated on the quantitative susceptibility map to encompass both thalami. Multivariate regression analyses were performed to identify the association between thalamic susceptibility and volume. Associations between thalamic susceptibility and total gray matter volume, cortical thickness, and T2 lesion volume were also assessed.

RESULTS

The relative susceptibility of the thalamus was associated with T2 lesion volume (P = .015) and was higher in the presence of enhancing lesions (P = .013). The relative susceptibility of the thalami was not associated with thalamic volumes, total gray matter volumes, or cortical thickness (P > .05).

CONCLUSIONS

Iron levels in the thalami are associated with T2 lesion burden and the presence of enhancing lesions, but not with thalamic or gray matter volumes, suggesting that iron accumulation is associated with white matter inflammation rather than gray matter neurodegeneration.

Hepatitis E virus ORF1 encoded macro domain protein interacts with light chain subunit of human ferritin and inhibits its secretion

Hepatitis E Virus (HEV) is the major causative agent of acute hepatitis in developing countries. Its genome has three open reading frames (ORFs)-called as ORF1, ORF2, and ORF3. ORF1 encodes nonstructural polyprotein having multiple domains, namely: Methyltransferase, Y domain, Protease, Macro domain, Helicase, and RNA-dependent RNA polymerase. In the present study, we show that HEV-macro domain specifically interacts with light chain subunit of human ferritin (FTL). In cultured hepatoma cells, HEV-macro domain reduces secretion of ferritin without causing any change in the expression levels of FTL. This inhibitory effect was further enhanced upon Brefeldin-A treatment. The levels of transferrin Receptor 1 or ferroportin, two important proteins in iron metabolism, remained unchanged in HEV-macro domain expressing cells. Similarly, there were no alterations in the levels of cellular labile iron pool and reactive oxygen species, indicating that HEV-macro domain does not influence cellular iron homeostasis/metabolism. As ferritin is an acute-phase protein, secreted in higher level in infected persons and HEV-macro domain has the property of reducing synthesis of inflammatory cytokines, we propose that by directly binding to FTL, macro domain prevents ferritin from entering into circulation and helps in further attenuation of the host immune response.

The CD68(+)/H-ferritin(+) cells colonize the lymph nodes of the patients with adult onset Still's disease and are associated with increased extracellular level of H-ferritin in the same tissue: correlation with disease severity and implication for pathogenesis

In this work, we aimed to evaluate the levels of ferritin enriched in H subunits (H-ferritin) and ferritin enriched in L subunits (L-ferritin) and the cells expressing these two molecules in the lymph node (LN) biopsies obtained from adult-onset Still's disease (AOSD) patients, and the possible correlation among these data and the severity of the disease. Ten patients with AOSD underwent LN biopsy. All the samples were stained by immunofluorescence. A statistical analysis was performed to estimate the possible correlation among both H-ferritin and L-ferritin tissue expression and the clinical picture of the disease. Furthermore, the same analysis was performed to evaluate the possible correlation among the number of CD68(+)/H-ferritin(+) or CD68(+)/L-ferritin(+) cells and the clinical picture. Immunofluorescence analysis demonstrated an increased tissue H-ferritin expression in the LNs of AOSD patients. This increased expression correlated with the severity of the disease. An increased number of CD68 macrophages expressing H-ferritin was observed in the LN samples of our patients. Furthermore, we observed that the number of CD68(+)/H-ferritin(+) cells correlated significantly with the severity of the clinical picture. Our data showed an imbalance between the levels of H- and L-ferritin in LNs of AOSD patients and the evidence of an increased number of CD68(+)/H-ferritin(+) cells in the same organs. Furthermore, a correlation among both the tissue H-ferritin levels and the CD68(+)/H-ferritin(+) cells and the clinical picture was observed.

Ferritin in adult-onset still's disease: just a useful innocent bystander?

Background. Adult-Onset Still's Disease (AOSD) is an immune-mediated systemic disease with quotidian-spiking fever, rash, and inflammatory arthritis. Hyperferritinemia is a prominent feature, often used for screening. Methods. The key terms “ferritin” and “hyperferritinemia” were used to search PubMed and Medline and were cross-referenced with “Still's Disease.” Results. Hyperferritinemia, although nonspecific, is particularly prevalent in AOSD. While most clinicians associate ferritin with iron metabolism, this is mostly true for the H isoform and not for the L isoform that tends to increase dramatically in hyperferritenemia. In these situations, hyperferritinemia is not associated with iron metabolism and may even mask an underlying iron deficiency. We review, in systematic fashion, the current basic science and clinical literature regarding the regulation of ferritin and its use in the diagnosis and management of AOSD. Conclusion. Serum hyperferritinemia in AOSD has been described for 2 decades, although its mechanism has not yet been completely elucidated. Regulation by proinflammatory cytokines such as interleukin (IL)-1b, IL-6, IL-18, MCSF, and INF-α provides a link to the disease pathogenesis and may explain rapid resolution of hyperferritinemia after targeted treatment and inhibition of key cytokines.

Disruption of paraoxonase 3 impairs proliferation and antioxidant defenses in human A549 cells and causes embryonic lethality in mice

We had shown previously that paraoxonase 3 (PON3), a putative circulating antioxidant, was systemically upregulated in late-gestation rat, sheep, and human fetuses. Our overarching hypothesis is that preterm human infants are delivered with low levels of PON3 and that this contributes to a state of oxidative stress. We sought to determine whether absence of Pon3 was associated with reduced neonatal viability in mice and studied the offspring from crosses between Pon3(+/-) mice. The number of Pon3(-/-) animals at E10.5 and E17.5 was significantly lower than the expected 25% (9.3 and 7.9% respectively, P < 0.001). On the first day of postnatal life, this was reduced further (2.4%, significantly less than the proportion in fetal life, P = 0.04). Pon3(+/-) animals had lower body and placental weights than wild-type littermates at E17.5, an effect that was independent of the parent of origin of the mutant allele. We then studied the effect of PON3 knockdown in a human cell line, A549. Stable knockdown of PON3 using short-hairpin RNA reduced cell proliferation in 21% oxygen. We then studied the effect of transient knockdown of PON3 using short interfering RNA (siRNA) in the same cell line in low (2%) or ambient (21%) oxygen. Knockdown of PON3 using siRNA reduced total antioxidant capacity in 21% (P = 0.008) but not 2% oxygen. We conclude that the absence of Pon3 in mice resulted in increased rates of early fetal and neonatal death. Knockdown of PON3 in human cells reduced cell proliferation and total antioxidant capacity.

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.

Interplay Between Cytokine-Induced and Cyclic Equibiaxial Deformation-Induced Nitric Oxide Production and Metalloproteases Expression in Human Alveolar Epithelial Cells

Ventilator-induced lung overdistension has been a growing concern in the management of mechanically ventilated patients. Mechanical ventilation triggers or enhances the net inflammatory and tissue remodeling activities. Although it has been shown that proinflammatory and tissue remodeling factors play important roles during airway remodeling, the interplay between them is not well understood. Thus, our objective was to study and characterize the molecular mechanism of cyclic equibiaxial deformation-induced airway inflammation and remodeling either in the presence or absence of a pre-existing inflammatory condition. This study was done using an in vitro dynamic model, which can simulate different mechanical ventilative conditions. Type II alveolar epithelial cell (A549) monolayers were exposed to the different levels of mechanical ventilative conditions using the Flexcell^® Tension Plus^™ 4000T system, which generated the different levels of cyclic equibiaxial deformation (5, 10, 15, and 20%) at 0.2 Hz deformation frequency. The production of nitric oxide (NO), the expression of metalloprotease-2 (MMP-2)/tissue inhibitor metalloprotease-2 (TIMP-2), and the activation of MMP-2 were measured under the different levels of cyclic equibiaxial deformation either in the presence or absence of TNF-α. Our study indicated that cyclic equibiaxial deformation-induced production of NO and MMP-2/TIMP-2. Higher levels of cyclic equibiaxial deformation increased the expression of the active form of MMP-2. In particular, in the presence of TNF-α, the more active form of MMP-2 was detected during both cyclic equibiaxial deformation and remodeling periods.

Development of budesonide microparticles using spray-drying technology for pulmonary administration: design, characterization, in vitro evaluation, and in vivo efficacy study

The purpose of this research was to generate, characterize, and investigate the in vivo efficacy of budesonide (BUD) microparticles prepared by spray-drying technology with a potential application as carriers for pulmonary administration with sustained-release profile and improved respirable fraction. Microspheres and porous particles of chitosan (drug/chitosan, 1:2) were prepared by spray drying using optimized process parameters and were characterized for different physicochemical parameters. Mass median aerodynamic diameter and geometric standard deviation for conventional, microspheres, and porous particles formulations were 2.75, 4.60, and 4.30 microm and 2.56, 1.75, and 2.54, respectively. Pharmacokinetic study was performed in rats by intratracheal administration of either placebo or developed dry powder inhalation (DPI) formulation. Pharmacokinetic parameters were calculated (Ka, Ke, T(max), C(max), AUC, and Vd) and these results indicated that developed formulations extended half life compared to conventional formulation with onefold to fourfold improved local and systemic bioavailability. Estimates of relative bioavailability suggested that developed formulations have excellent lung deposition characteristics with extended T(1/2) from 9.4 to 14 h compared to conventional formulation. Anti-inflammatory activity of BUD and developed formulations was compared and found to be similar. Cytotoxicity was determined in A549 alveolar epithelial cell line and found to be not toxic. In vivo pulmonary deposition of developed conventional formulation was studied using gamma scintigraphy and results indicated potential in vitro-in vivo correlation in performance of conventional BUD DPI formulation. From the DPI formulation prepared with porous particles, the concentration of BUD increased fourfold in the lungs, indicating pulmonary targeting potential of developed formulations.

Cytokine responses of human lung cells (BEAS-2B) treated with micron-sized and nanoparticles of metal oxides compared to soil dusts

BACKGROUND

The induction of cytokines by airway cells in vitro has been widely used to assess the effects of ambient and occupational particles. This study measured cytotoxicity and the release of the proinflammatory cytokines IL-6 and IL-8 by human bronchial epithelial cells treated with manufactured nano- and micron-sized particles of Al2O3, CeO2, Fe2O3, NiO, SiO2, and TiO2, with soil-derived particles from fugitive dust sources, and with the positive controls LPS, TNF-alpha, and VOSO4.

RESULTS

The nano-sized particles were not consistently more potent than an equal mass of micron-sized particles of the same nominal composition for the induction of IL-6 and IL-8 secretion in the in vitro models used in this study. The manufactured pure oxides were much less potent than natural PM2.5 particles derived from soil dust, and the cells were highly responsive to the positive controls. The nano-sized particles in the media caused artifacts in the measurement of IL-6 by ELISA due to adsorption of the cytokine on the high-surface-area particles. The potency for inducing IL-6 secretion by BEAS-2B cells did not correlate with the generation of reactive oxygen species in cell-free media.

CONCLUSION

Direct comparisons of manufactured metal oxide nanoparticles and previously studied types of particles and surrogate proinflammatory agonists showed that the metal oxide particles have low potency to induce IL-6 secretion in BEAS-2B cells. Particle artifacts from non-biological effects need to be considered in experiments of this type, and the limitations inherent in cell culture studies must be considered when interpreting in vitro results. This study suggests that manufactured metal oxide nanoparticles are not highly toxic to lung cells compared to environmental particles.

Cytokine responses of human lung cells (BEAS-2B) treated with micron-sized and nanoparticles of metal oxides compared to soil dusts

BACKGROUND

The induction of cytokines by airway cells in vitro has been widely used to assess the effects of ambient and occupational particles. This study measured cytotoxicity and the release of the proinflammatory cytokines IL-6 and IL-8 by human bronchial epithelial cells treated with manufactured nano- and micron-sized particles of Al2O3, CeO2, Fe2O3, NiO, SiO2, and TiO2, with soil-derived particles from fugitive dust sources, and with the positive controls LPS, TNF-alpha, and VOSO4.

RESULTS

The nano-sized particles were not consistently more potent than an equal mass of micron-sized particles of the same nominal composition for the induction of IL-6 and IL-8 secretion in the in vitro models used in this study. The manufactured pure oxides were much less potent than natural PM2.5 particles derived from soil dust, and the cells were highly responsive to the positive controls. The nano-sized particles in the media caused artifacts in the measurement of IL-6 by ELISA due to adsorption of the cytokine on the high-surface-area particles. The potency for inducing IL-6 secretion by BEAS-2B cells did not correlate with the generation of reactive oxygen species in cell-free media.

CONCLUSION

Direct comparisons of manufactured metal oxide nanoparticles and previously studied types of particles and surrogate proinflammatory agonists showed that the metal oxide particles have low potency to induce IL-6 secretion in BEAS-2B cells. Particle artifacts from non-biological effects need to be considered in experiments of this type, and the limitations inherent in cell culture studies must be considered when interpreting in vitro results. This study suggests that manufactured metal oxide nanoparticles are not highly toxic to lung cells compared to environmental particles.

Distinct roles of basal steady-state and induced H-ferritin in tumor necrosis factor-induced death in L929 cells

Tumor necrosis factor (TNF) alpha is a cytokine capable of inducing caspase-dependent (apoptotic) cell death in some cells and caspase-independent (necrosis-like) cell death in others. Here, using a mutagenesis screen for genes critical in TNF-induced death in L929 cells, we have found that H-ferritin deficiency is responsible for TNF resistance in a mutant line and that, upon treatment with TNF, this line fails to elevate levels of labile iron pool (LIP), critical for TNF-induced reactive oxygen species (ROS) production and ROS-dependent cell death. Since we found that TNF-induced LIP in L929 cells is primarily furnished by intracellular storage iron, the lesser induction of LIP in H-ferritin-deficient cells results from a reduction of intracellular iron storage caused by less H-ferritin. Different from some other cell lines, the H-ferritin gene in L929 cells is not TNF inducible; however, when H-ferritin is expressed in L929 cells under a TNF-inducible system, the TNF-induced LIP and subsequent ROS production and cell death were all prevented. Thus, LIP is a common denominator of ferritin both in the enhancement of cell death by basal steady-state H-ferritin and in protection against cell death by induced H-ferritin, thereby acting as a key determinant of TNF-induced cell death.

TNF, IFN-γ, and endotoxin increase expression of DMT1 in bronchial epithelial cells

Regulation of the metal transport protein divalent metal transporter-1 (DMT1) may contribute to the uptake and detoxification of iron by cells resident in the respiratory tract. Inflammation has been associated with an increased availability of this metal resulting in an oxidative stress. Because proinflammatory cytokines and LPS have been demonstrated to affect an elevated expression of DMT1 in a macrophage cell line, we tested the hypothesis that tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and LPS increase DMT1 expression in airway epithelial cells. We used RT-PCR to detect mRNA for both −IRE DMT1 and +IRE DMT1 in BEAS-2B cells. Treatment with TNF-α, IFN-γ, or LPS increased both forms. Western blot analysis also demonstrated an increase in the expression of both isoforms of DMT1 after these treatments. Twenty-four hours after exposure of an animal model to TNF-α, IFN-γ, or LPS, a significant increase in pulmonary expression of −IRE DMT1 was seen by immunohistochemistry; the level of +IRE DMT1 was too low in the lung to be visualized using this methodology. Finally, iron transport into BEAS-2B cells was increased after inclusion of TNF-α, IFN-γ, or LPS in the media. We conclude that proinflammatory cytokines and LPS increase mRNA and protein expression of DMT1 in airway cells in vitro and in vivo. Furthermore, both −IRE and +IRE isoforms are elevated after exposures. Increased expression of this protein appears to be included in a coordinated response of the cell and tissue where the function might be to diminish availability of metal.

Hepcidin regulation of ferroportin 1 expression in the liver and intestine of the rat

Hepcidin has been implicated as the iron stores regulator: a hepatic signaling molecule that regulates intestinal iron absorption by undefined mechanisms. The possibility that hepcidin regulates the expression of ferroportin 1 (FPT1), the basolateral iron transporter, was examined in rats after administration of LPS, an iron chelator, or His-tagged recombinant hepcidin (His-rHepc). In the liver, LPS stimulated a biphasic increase of hepcidin mRNA with peaks of mRNA at 6 and 36 h. Concurrently, hepatic FPT1 mRNA expression decreased to minimal level at 6 h and then increased with a peak at 24-36 h. LPS also induced biphasic changes in intestinal FPT1 mRNA expression, with decreased levels at 6 h and increased expression at 48 h. Whereas the initial decrease of FPT1 coincides with an LPS-induced decrease in serum iron, both intestinal and hepatic FPT1 expression recovered, whereas serum iron concentration continued to decrease for at least 24 h. Dietary iron ingestion increased intestinal ferritin protein production but did not reduce intestinal FPT1 mRNA expression. The iron chelator pyrrolidinedithiocarbamate (PDTC) stimulated hepatic hepcidin without suppressing intestinal FPT1 expression. In PDTC-treated rats, LPS stimulated no additional hepatic hepcidin expression but did increase intestinal FPT1 expression. Administration of HisrHepc induced significant reduction of intestinal FPT1 expression. Taken together, these data suggest that hepcidin mediates LPS-induced downregulation of intestinal FPT1 expression and that the hepcidin signaling pathway involves a PDTC-sensitive step.