Immunosuppressive effects of melanoma-derived heavy-chain ferritin are dependent on stimulation of IL-10 production

Ferritin heavy chain supports stability and function of the regulatory T cell lineage

Regulatory T (TREG) cells develop via a program orchestrated by the transcription factor forkhead box protein P3 (FOXP3). Maintenance of the TREG cell lineage relies on sustained FOXP3 transcription via a mechanism involving demethylation of cytosine-phosphate-guanine (CpG)-rich elements at conserved non-coding sequences (CNS) in the FOXP3 locus. This cytosine demethylation is catalyzed by the ten-eleven translocation (TET) family of dioxygenases, and it involves a redox reaction that uses iron (Fe) as an essential cofactor. Here, we establish that human and mouse TREG cells express Fe-regulatory genes, including that encoding ferritin heavy chain (FTH), at relatively high levels compared to conventional T helper cells. We show that FTH expression in TREG cells is essential for immune homeostasis. Mechanistically, FTH supports TET-catalyzed demethylation of CpG-rich sequences CNS1 and 2 in the FOXP3 locus, thereby promoting FOXP3 transcription and TREG cell stability. This process, which is essential for TREG lineage stability and function, limits the severity of autoimmune neuroinflammation and infectious diseases, and favors tumor progression. These findings suggest that the regulation of intracellular iron by FTH is a stable property of TREG cells that supports immune homeostasis and limits the pathological outcomes of immune-mediated inflammation.

A novel view of ferritin in cancer

Since its discovery more than 85 years ago, ferritin has principally been known as an iron storage protein. However, new roles, beyond iron storage, are being uncovered. Novel processes involving ferritin such as ferritinophagy and ferroptosis and as a cellular iron delivery protein not only expand our thinking on the range of contributions of this protein but present an opportunity to target these pathways in cancers. The key question we focus on within this review is whether ferritin modulation represents a useful approach for treating cancers. We discussed novel functions and processes of this protein in cancers. We are not limiting this review to cell intrinsic modulation of ferritin in cancers, but also focus on its utility in the trojan horse approach in cancer therapeutics. The novel functions of ferritin as discussed herein realize the multiple roles of ferritin in cell biology that can be probed for therapeutic opportunities and further research.

A novel prognostic model based on ferritin and nomogram-revised risk index could better stratify patients with extranodal natural killer/T-cell lymphoma

BACKGROUND

Extranodal natural killer (NK)/T-cell lymphoma (ENKTCL) is an aggressive lymphoma with marked heterogeneity, resulting in a distinct prognosis even in patients with the same disease stage. The nomogram-revised risk index (NRI) has been proposed to stratify patients with ENKTCL. Numerous reports have revealed the prognostic role of serum ferritin in various cancers.

PURPOSE

We aimed to evaluate the role of NRI in our single cohort of patients with ENKTCL treated uniformly, explore the prognostic value of ferritin, and establish a new prognostic model to better stratify patients with ENKTCL.

METHODS

We included 326 patients with ENKTCL with detailed data regarding clinical characteristics and survival outcomes. All patients were treated with asparaginase-based chemotherapy with or without radiotherapy. Multiple R packages were used to analyze the prognostic factors and derive a novel prognostic model.

RESULTS

In the training cohort comprising 236 patients with ENKTCL, NRI significantly correlated with progression-free survival (PFS) and overall survival (p < 0.0001). Using a ferritin level of 400 μg/L as the cutoff value, patients with high ferritin levels had significantly inferior PFS (p = 0.00028). Integrating the NRI score and four easily accessible clinical parameters, namely ferritin, hemoglobin, albumin, and D-dimer, a new prognostic model was constructed, stratifying patients with ENKTCL into three risk groups. This new prognostic model was independent of disease stage and NRI and performed better than NRI. Furthermore, this model helped to stratify patients within the same NRI risk groups. Finally, the role of this novel prognostic model was validated in the external validation cohort comprising 90 patients with ENKTCL.

CONCLUSIONS

Serum ferritin level could be a novel prognostic factor in patients with ENKTCL. The new prognostic model combining NRI and clinical parameters could better predict the prognosis of ENKTCL, thereby warranting further validation and potentially guiding individualized treatment in future prospective clinical trials.

Impact of clinico-biochemical and inflammatory biomarkers on the immunogenicity and efficacy of SARS-CoV-2 adenoviral vaccine: a longitudinal study

Purpose

Due to a lack of effective antiviral treatment, several vaccines have been put forth to curb SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection and to reduce the mortality and morbidity rate by eliciting a protective immune response, primarily through virus-neutralizing antibodies specific for SARS-CoV-2 spike protein. This longitudinal study was designed to evaluate the vaccine effectiveness and immune response following the administration of adenoviral vaccine, COVISHIELD, in Indian population who were previously uninfected with SARS-CoV-2 and to reveal the effect of various sociodemographic, inflammatory and biochemical factors on antibody response.

Methods

Briefly, the total immunoglobulin G (IgG) against SARS-CoV-2 spike and nucleocapsid protein along with the immunological markers were estimated by chemiluminescent microparticle immunoassay (CMIA) technology. Biochemical parameters were estimated by spectrometry.

Results

A total of 348 subjects received two doses of COVISHIELD (224 males, 124 females). The mean age of the study subjects was 42.03 ± 13.54 years. Although both the doses of COVISHIELD against SARS-CoV-2 spike protein induced a robust immune response that lasted for months in all the subjects, the total IgG titer against SARS-CoV-2 spike protein was found significantly higher in subjects ≥50 years of age, and those with obesity, elevated triglycerides and elevated lactate dehydrogenase levels.

Conclusions

There is a definite effect of age and biochemical factors on the immunogenicity of COVISHIELD. An understanding of these factors could not only impact the design of vaccines and help improve vaccine immunogenicity and efficacy but also assist in decisions on vaccination schedules, in order to combat this deadly pandemic.

Ferritin - from iron, through inflammation and autoimmunity, to COVID-19

While it took decades to arrive to a conclusion that ferritin is more than an indicator of iron storage level, it took a short period of time through the COVID-19 pandemic to wonder what the reason behind high levels of ferritin in patients with severe COVID-19 might be. Unsurprisingly, acute phase reactant was not a satisfactory explanation. Moreover, the behavior of ferritin in patients with severe COVID-19 and the subsequent high mortality rates in patients with high ferritin levels necessitated further investigations to understand the role of ferritin in the diseases. Ferritin was initially described to accompany various acute infections, both viral and bacterial, indicating an acute response to inflammation. However, with the introduction of the hyperferritinemic syndrome connecting four severe pathological conditions such as adult-onset Still's disease, macrophage activation syndrome, catastrophic antiphospholipid syndrome, and septic shock added another aspect of ferritin where it could have a pathogenetic role rather than an extremely elevated protein only. In fact, suggesting that COVID-19 is a new member in the spectrum of hyperferritinemic syndrome besides the four mentioned conditions could hopefully direct further search on the pathogenetic role of ferritin. Doubtlessly, improving our understanding of those aspects of ferritin would enormously contribute to better coping with severe diseases in terms of treatment and prevention of complications. The origin, history, importance, and the advances of searching the role of ferritin in various pathological and clinical processes are presented hereby in our article. In addition, the implications of ferritin in COVID-19 are addressed.

HCV-Induced Immunometabolic Crosstalk in a Triple-Cell Co-Culture Model Capable of Simulating Systemic Iron Homeostasis

Iron is crucial to the regulation of the host innate immune system and the outcome of many infections. Hepatitis C virus (HCV), one of the major viral human pathogens that depends on iron to complete its life cycle, is highly skilled in evading the immune system. This study presents the construction and validation of a physiologically relevant triple-cell co-culture model that was used to investigate the input of iron in HCV infection and the interplay between HCV, iron, and determinants of host innate immunity. We recorded the expression patterns of key proteins of iron homeostasis involved in iron import, export and storage and examined their relation to the iron regulatory hormone hepcidin in hepatocytes, enterocytes and macrophages in the presence and absence of HCV. We then assessed the transcriptional profiles of pro-inflammatory cytokines Interleukin-6 (IL-6) and interleukin-15 (IL-15) and anti-inflammatory interleukin-10 (IL-10) under normal or iron-depleted conditions and determined how these were affected by infection. Our data suggest the presence of a link between iron homeostasis and innate immunity unfolding among liver, intestine, and macrophages, which could participate in the deregulation of innate immune responses observed in early HCV infection. Coupled with iron-assisted enhanced viral propagation, such a mechanism may be important for the establishment of viral persistence and the ensuing chronic liver disease.

COVID-19-A Theory of Autoimmunity Against ACE-2 Explained

The COVID-19 pandemic caused by the coronavirus SARS-COV-2 has cost many lives worldwide. In dealing with affected patients, the physician is faced with a very unusual pattern of organ damage that is not easily explained on the basis of prior knowledge of viral-induced pathogenesis. It is established that the main receptor for viral entry into tissues is the protein angiotensin-converting enzyme-2 ["ACE-2", (1)]. In a recent publication (2), a theory of autoimmunity against ACE-2, and/or against the ACE-2/SARS-COV-2 spike protein complex or degradation products thereof, was proposed as a possible explanation for the unusual pattern of organ damage seen in COVID-19. In the light of more recent information, this manuscript expands on the earlier proposed theory and offers additional, testable hypotheses that could explain both the pattern and timeline of organ dysfunction most often observed in COVID-19.

Effect of Heme Oxygenase-1 on Melanoma Development in Mice-Role of Tumor-Infiltrating Immune Cells

OBJECTIVE

Heme oxygenase-1 (HO-1) is a cytoprotective, proangiogenic and anti-inflammatory enzyme that is often upregulated in tumors. Overexpression of HO-1 in melanoma cells leads to enhanced tumor growth, augmented angiogenesis and resistance to anticancer treatment. The effect of HO-1 in host cells on tumor development is, however, hardly known.

METHODS AND RESULTS

To clarify the effect of HO-1 expression in host cells on melanoma progression, C57BL/6xFvB mice of different HO-1 genotypes, HO-1+/+, HO-1+/-, and HO-1-/-, were injected with the syngeneic wild-type murine melanoma B16(F10) cell line. Lack of HO-1 in host cells did not significantly influence the host survival. Nevertheless, in comparison to the wild-type counterparts, the HO-1+/- and HO-1-/- males formed bigger tumors, and more numerous lung nodules; in addition, more of them had liver and spleen micrometastases. Females of all genotypes developed at least 10 times smaller tumors than males. Of importance, the growth of primary and secondary tumors was completely blocked in HO-1+/+ females. This was related to the increased infiltration of leukocytes (mainly lymphocytes T) in primary tumors.

CONCLUSIONS

Although HO-1 overexpression in melanoma cells can enhance tumor progression in mice, its presence in host cells, including immune cells, can reduce growth and metastasis of melanoma.

Overcoming Immune Evasion in Melanoma

Melanoma is the most aggressive and dangerous form of skin cancer that develops from transformed melanocytes. It is crucial to identify melanoma at its early stages, in situ, as it is "curable" at this stage. However, after metastasis, it is difficult to treat and the five-year survival is only 25%. In recent years, a better understanding of the etiology of melanoma and its progression has made it possible for the development of targeted therapeutics, such as vemurafenib and immunotherapies, to treat advanced melanomas. In this review, we focus on the molecular mechanisms that mediate melanoma development and progression, with a special focus on the immune evasion strategies utilized by melanomas, to evade host immune surveillances. The proposed mechanism of action and the roles of immunotherapeutic agents, ipilimumab, nivolumab, pembrolizumab, and atezolizumab, adoptive T- cell therapy plus T-VEC in the treatment of advanced melanoma are discussed. In this review, we implore that a better understanding of the steps that mediate melanoma onset and progression, immune evasion strategies exploited by these tumor cells, and the identification of biomarkers to predict treatment response are critical in the design of improved strategies to improve clinical outcomes for patients with this deadly disease.

Iron in infection and immunity

Iron is an essential micronutrient for virtually all living cells. In infectious diseases, both invading pathogens and mammalian cells including those of the immune system require iron to sustain their function, metabolism and proliferation. On the one hand, microbial iron uptake is linked to the virulence of most human pathogens. On the other hand, the sequestration of iron from bacteria and other microorganisms is an efficient strategy of host defense in line with the principles of 'nutritional immunity'. In an acute infection, host-driven iron withdrawal inhibits the growth of pathogens. Chronic immune activation due to persistent infection, autoimmune disease or malignancy however, sequesters iron not only from infectious agents, autoreactive lymphocytes and neoplastic cells but also from erythroid progenitors. This is one of the key mechanisms which collectively result in the anemia of chronic inflammation. In this review, we highlight the most important interconnections between iron metabolism and immunity, focusing on host defense against relevant infections and on the clinical consequences of anemia of inflammation.

Predicting chemotherapy-induced thrombocytopenia in cancer patients with solid tumors or lymphoma

Purpose

Chemotherapy-induced thrombocytopenia is a serious complication in chemotherapy-treated patients. Identification of patients at risk for chemotherapy-induced thrombocytopenia could have clinical value in personalized management of patients and optimized administration of prophylactic thrombopoietic agents. The aim of this study was to develop a predictive model for chemotherapy-induced thrombocytopenia (platelet count < 100,000/µl) in cancer patients undergoing chemotherapy.

Methods

A total of 14 covariates were prospectively assessed as explanatory variables in a cohort of consecutive patients with solid tumors or lymphoma. A multivariable logistic regression model was developed after univariable analysis. A bootstrapping technique was applied for internal validation.

Results

Data from 305 patients during 1732 chemotherapy cycles were considered for analysis. Forty-eight patients (15.73%) developed chemotherapy-induced thrombocytopenia during their treatment course. The multivariable model exhibited three final predictors for chemotherapy-induced thrombocytopenia, including high ferritin (odds ratio, 4.41; bootstrap P = 0.001), estimated glomerular filtration rate <60 ml/min/1.73 m2(odds ratio, 3.08; bootstrap P = 0.005), and body mass index <23 kg/m2(odds ratio, 2.23; bootstrap P = 0.044). The main characteristics of the model include sensitivity 75%, specificity 65.4%, positive likelihood ratio 2.16, and negative likelihood ratio 0.382. Moreover, the model was well calibrated (Hosmer–Lemeshow P = 0.713) and the area under the receiver operating characteristic curve was 0.735 (95% confidence interval, 0.654–0.816; P < 0.001).

Conclusions

We developed a predictive model for chemotherapy-induced thrombocytopenia based on readily available and easily assessable clinical and laboratory factors. This study may provide a valuable insight to guide optimized treatment of cancer patients. Further studies with larger sample size are warranted.

Prognostic evaluation of serum ferritin in acute exacerbation of idiopathic pulmonary fibrosis

BACKGROUND

Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) has an extremely poor prognosis. The role of ferritin in the pathogenesis of AE-IPF is not well known while serum ferritin is a key prognostic indicator for patients with clinically amyopathic dermatomyositis with rapidly progressive interstitial pneumonia.

OBJECTIVE

To elucidate the clinical importance of serum ferritin in patients with AE-IPF.

METHODS

Thirty-seven patients (48 episodes), who were diagnosed with AE-IPF and treated at our hospital between 1997 and 2015, were retrospectively studied.

RESULTS

Patients with AE-IPF had significantly higher levels of serum ferritin than baseline levels at the first diagnosis of IPF (P = 0.0017). Receiver operating characteristic analysis showed the cut-off value 174 ng/mL for the separation of AE (area under the curve, 0.700). No patients with AE-IPF were positive for anti- melanoma differentiation-associated gene 5 antibody. Patients with AE-IPF and higher ferritin (≥174 ng/mL) had lower %FVC and %DLCO before AE, and those with much higher ferritin (≥500 ng/mL) had significantly worse prognosis than those with lower ferritin (log-rank, P = 0.024). Immunohistochemical staining in autopsy specimens showed alveolar macrophages that were producing ferritin. Finally, in multivariate Cox proportional hazards analyses, serum ferritin level of ≥500 ng/mL was a significant worse prognostic factor (hazard ratio 5.280, P = 0.046).

CONCLUSION

Higher serum ferritin may be related to a worse prognosis in patients with AE-IPF.

Emerging and Dynamic Biomedical Uses of Ferritin

Ferritin, a ubiquitously expressed protein, has classically been considered the main iron cellular storage molecule in the body. Owing to the ferroxidase activity of the H-subunit and the nucleation ability of the L-subunit, ferritin can store a large amount of iron within its mineral core. However, recent evidence has demonstrated a range of abilities of ferritin that extends well beyond the scope of iron storage. This review aims to discuss novel functions and biomedical uses of ferritin in the processes of iron delivery, delivery of biologics such as chemotherapies and contrast agents, and the utility of ferritin as a biomarker in a number of neurological diseases.

Exploring the Immunomodulatory Moonlighting Activities of Acute Phase Proteins for Tolerogenic Dendritic Cell Generation

The acute phase response is generated by an overwhelming immune-inflammatory process against infection or tissue damage, and represents the initial response of the organism in an attempt to return to homeostasis. It is mediated by acute phase proteins (APPs), an assortment of highly conserved plasma reactants of seemingly different functions that, however, share a common protective role from injury. Recent studies have suggested a crosstalk between several APPs and the mononuclear phagocyte system (MPS) in the resolution of inflammation, to restore tissue integrity and function. In fact, monocyte-derived dendritic cells (Mo-DCs), an integral component of the MPS, play a fundamental role both in the regulation of antigen-specific adaptive responses and in the development of immunologic memory and tolerance, particularly in inflammatory settings. Due to their high plasticity, Mo-DCs can be modeled in vitro toward a tolerogenic phenotype for the treatment of aberrant immune-inflammatory conditions such as autoimmune diseases and allotransplantation, with the phenotypic outcome of these cells depending on the immunomodulatory agent employed. Yet, recent immunotherapy trials have emphasized the drawbacks and challenges facing tolerogenic Mo-DC generation for clinical use, such as reduced therapeutic efficacy and limited in vivo stability of the tolerogenic activity. In this review, we will underline the potential relevance and advantages of APPs for tolerogenic DC production with respect to currently employed immunomodulatory/immunosuppressant compounds. A further understanding of the mechanisms of action underlying the moonlighting immunomodulatory activities exhibited by several APPs over DCs could lead to more efficacious, safe, and stable protocols for precision tolerogenic immunotherapy.

Advances in immunopathogenesis of macrophage activation syndrome during rheumatic inflammatory diseases: toward new therapeutic targets?

INTRODUCTION

Macrophage activation syndrome (MAS) is a severe, hyperinflammatory life-threatening syndrome, generally complicating different rheumatic diseases. Despite the severity of the disease, little is known about the pathogenic mechanisms and, thus, possible targeted therapies in the management of these patients. Areas covered: In this review, we aimed to update the current pathogenic knowledge of MAS, during rheumatic diseases, focusing mainly on immunologic abnormalities and on new possible therapeutic strategies. Expert commentary: The difficult pathogenic scenario of MAS, in which genetic defects, predisposing diseases, and triggers are mixed together with the high mortality rate, make it difficult to manage these patients. Although most efforts have been focused on investigating the disease in children, in recent years, several studies are trying to elucidate the possible pathogenic mechanism in adult MAS patients. In this context, genetic and immunological studies might lead to advances in the knowledge of pathogenic mechanisms and possible new therapeutic targets. In the future, the results of ongoing clinical trials are awaited in order to improve the management and, thus, the survival of these patients.

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.

Serum Ferritin Is Inversely Correlated with Testosterone in Boys and Young Male Adolescents: A Cross-Sectional Study in Taiwan

Objective

The transition from childhood to teenaged years is associated with increased testosterone and a decreased iron status. It is not clear whether higher testosterone levels cause the decreased iron status, and to what extent, obesity-related inflammation influences the iron-testosterone relationship. The aim of the present study was to examine relationships of testosterone, iron status, and anti-/proinflammatory cytokines in relation to nutritional status in boys and young adolescent Taiwanese males.

Methods

In total, 137 boys aged 7~13 yr were included. Parameters for obesity, the iron status, testosterone, and inflammatory markers were evaluated.

Results

Overweight and obese (ow/obese) boys had higher mean serum testosterone, interleukin (IL)-1β, and nitric oxide (NO) levels compared to their normal-weight counterparts (all p<0.05). Mean serum ferritin was slightly higher in ow/obese boys compared to normal-weight boys, but this did not reach statistical significance. A multiple linear regression showed that serum ferritin (β = -0.7470, p = 0.003) was inversely correlated with testosterone, while serum IL-10 (β = 0.3475, p = 0.009) was positively associated with testosterone after adjusting for covariates. When normal-weight boys were separately assessed from ow/obesity boys, the association between testosterone and serum ferritin became stronger (β = -0.9628, p<0.0001), but the association between testosterone and IL-10 became non-significant (β = 0.1140, p = 0.4065) after adjusting for covariates. In ow/obese boys, only IL-10 was weakly associated with serum testosterone (β = 0.6444, p = 0.051) after adjusting for age.

Conclusions

Testosterone and serum ferritin are intrinsically interrelated but this relationship is weaker in ow/obese boys after adjusting for age.

H-Ferritin Is Preferentially Incorporated by Human Erythroid Cells through Transferrin Receptor 1 in a Threshold-Dependent Manner

Ferritin is an iron-storage protein composed of different ratios of 24 light (L) and heavy (H) subunits. The serum level of ferritin is a clinical marker of the body's iron level. Transferrin receptor (TFR)1 is the receptor not only for transferrin but also for H-ferritin, but how it binds two different ligands and the blood cell types that preferentially incorporate H-ferritin remain unknown. To address these questions, we investigated hematopoietic cell-specific ferritin uptake by flow cytometry. Alexa Fluor 488-labeled H-ferritin was preferentially incorporated by erythroid cells among various hematopoietic cell lines examined, and was almost exclusively incorporated by bone marrow erythroblasts among human primary hematopoietic cells of various lineages. H-ferritin uptake by erythroid cells was strongly inhibited by unlabeled H-ferritin but was only partially inhibited by a large excess of holo-transferrin. On the other hand, internalization of labeled holo-transferrin by these cells was not inhibited by H-ferritin. Chinese hamster ovary cells lacking functional endogenous TFR1 but expressing human TFR1 with a mutated RGD sequence, which is required for transferrin binding, efficiently incorporated H-ferritin, indicating that TFR1 has distinct binding sites for H-ferritin and holo-transferrin. H-ferritin uptake by these cells required a threshold level of cell surface TFR1 expression, whereas there was no threshold for holo-transferrin uptake. The requirement for a threshold level of TFR1 expression can explain why among primary human hematopoietic cells, only erythroblasts efficiently take up H-ferritin.

Macrophage and epithelial cell H-ferritin expression regulates renal inflammation

Inflammation culminating in fibrosis contributes to progressive kidney disease. Cross-talk between the tubular epithelium and interstitial cells regulates inflammation by a coordinated release of cytokines and chemokines. Here we studied the role of heme oxygenase-1 (HO-1) and the heavy subunit of ferritin (FtH) in macrophage polarization and renal inflammation. Deficiency in HO-1 was associated with increased FtH expression, accumulation of macrophages with a dysregulated polarization profile, and increased fibrosis following unilateral ureteral obstruction in mice: a model of renal inflammation and fibrosis. Macrophage polarization in vitro was predominantly dependent on FtH expression in isolated bone marrow-derived mouse monocytes. Using transgenic mice with conditional deletion of FtH in the proximal tubules (FtH(PT-/-)) or myeloid cells (FtH(LysM-/-)), we found that myeloid FtH deficiency did not affect polarization or accumulation of macrophages in the injured kidney compared with wild-type (FtH(+/+)) controls. However, tubular FtH deletion led to a marked increase in proinflammatory macrophages. Furthermore, injured kidneys from FtH(PT-/-) mice expressed significantly higher levels of inflammatory chemokines and fibrosis compared with kidneys from FtH(+/+) and FtH(LysM-/-) mice. Thus, there are differential effects of FtH in macrophages and epithelial cells, which underscore the critical role of FtH in tubular-macrophage cross-talk during kidney injury.

The hyperferritinemic syndrome: macrophage activation syndrome, Still's disease, septic shock and catastrophic antiphospholipid syndrome

BACKGROUND

Over the last few years, accumulating data have implicated a role for ferritin as a signaling molecule and direct mediator of the immune system. Hyperferritinemia is associated with a multitude of clinical conditions and with worse prognosis in critically ill patients.

DISCUSSION

There are four uncommon medical conditions characterized by high levels of ferritin, namely the macrophage activation syndrome (MAS), adult onset Still's disease (AOSD), catastrophic antiphospholipid syndrome (cAPS) and septic shock, that share a similar clinical and laboratory features, and also respond to similar treatments, suggesting a common pathogenic mechanism. Ferritin is known to be a pro-inflammatory mediator inducing expression of pro-inflammatory molecules, yet it has opposing actions as a pro-inflammatory and as an immunosuppressant. We propose that the exceptionally high ferritin levels observed in these uncommon clinical conditions are not just the product of the inflammation but rather may contribute to the development of a cytokine storm.

SUMMARY

Here we review and compare four clinical conditions and the role of ferritin as an immunomodulator. We would like to propose including these four conditions under a common syndrome entity termed "Hyperferritinemic Syndrome".

The significance of ferritin in cancer: anti-oxidation, inflammation and tumorigenesis

The iron storage protein ferritin has been continuously studied for over 70years and its function as the primary iron storage protein in cells is well established. Although the intracellular functions of ferritin are for the most part well-characterized, the significance of serum (extracellular) ferritin in human biology is poorly understood. Recently, several lines of evidence have demonstrated that ferritin is a multi-functional protein with possible roles in proliferation, angiogenesis, immunosuppression, and iron delivery. In the context of cancer, ferritin is detected at higher levels in the sera of many cancer patients, and the higher levels correlate with aggressive disease and poor clinical outcome. Furthermore, ferritin is highly expressed in tumor-associated macrophages which have been recently recognized as having critical roles in tumor progression and therapy resistance. These characteristics suggest ferritin could be an attractive target for cancer therapy because its down-regulation could disrupt the supportive tumor microenvironment, kill cancer cells, and increase sensitivity to chemotherapy. In this review, we provide an overview of the current knowledge on the function and regulation of ferritin. Moreover, we examine the literature on ferritin's contributions to tumor progression and therapy resistance, in addition to its therapeutic potential.

Ferritin blocks inhibitory effects of two-chain high molecular weight kininogen (HKa) on adhesion and survival signaling in endothelial cells

Angiogenesis is tightly regulated through complex crosstalk between pro- and anti-angiogenic signals. High molecular weight kininogen (HK) is an endogenous protein that is proteolytically cleaved in plasma and on endothelial cell surfaces to HKa, an anti-angiogenic protein. Ferritin binds to HKa and blocks its anti-angiogenic activity. Here, we explore mechanisms underlying the cytoprotective effect of ferritin in endothelial cells exposed to HKa. We observe that ferritin promotes adhesion and survival of HKa-treated cells and restores key survival and adhesion signaling pathways mediated by Erk, Akt, FAK and paxillin. We further elucidate structural motifs of both HKa and ferritin that are required for effects on endothelial cells. We identify an histidine-glycine-lysine (HGK) -rich antiproliferative region within domain 5 of HK as the target of ferritin, and demonstrate that both ferritin subunits of the H and L type regulate HKa activity. We further demonstrate that ferritin reduces binding of HKa to endothelial cells and restores the association of uPAR with α5β1 integrin. We propose that ferritin blocks the anti-angiogenic activity of HKa by reducing binding of HKa to UPAR and interfering with anti-adhesive and anti-proliferative signaling of HKa.

Degradation of superparamagnetic iron oxide nanoparticle-induced ferritin by lysosomal cathepsins and related immune response

AIM

To examine the physiological impact of superparamagnetic iron oxide nanoparticles (SPIONs) on cell function and its interaction with oxysterol laden cells.

MATERIALS & METHODS

Intracellular iron was determined by Prussian blue staining. Cellular ferritin, cathepsin L and ferroportin were analyzed by flow cytometry and fluorescence microscopy. Cytokine secretion was determined by ELISA and immunoblotting.

RESULTS

In U937 and THP 1 cells, we did not detect any loss of cell viability on SPION loading. Desferrioxamine prevents induction of both ferritin and cathepsin L by SPIONs. Inhibition of lysosomal cathepsins upregulates both endogenous- and SPION-induced ferritin. SPION loading induces membranous ferroportin and incites secretion of ferritin, TNF-α and IL-10. 7β-hydroxycholesterol exposure reduces SPION uptake by cells.

CONCLUSION

SPION loading results in upregulation of lysosomal cathepsin, membranous ferroportin and ferritin degradation, which is associated with secretion of both pro- and anti-inflammatory cytokines. A reduced SPION uptake by oxysterol-laden cells may lead to a compromised MRI with elevated cathepsins and ferritin.

Perioperative dynamic alterations in peripheral regulatory T and B cells in patients with hepatocellular carcinoma

Background

Intratumoral and circulating regulatory T cells (Tregs) have been shown to be critical in the pathogenesis of hepatocellular carcinoma (HCC). However there is limited knowledge on the alterations of regulatory B cells (Bregs). We here investigated perioperative dynamic alterations of peripheral circulating Tregs and Bregs in HCC patients to reveal the relationship between regulatory lymphocytes and its clinical implications.

Methods

36 patients with HCC, 6 with chronic hepatitis B infection and 10 healthy donors were enrolled for this study. Frequencies of peripheral Tregs and Bregs were measured by flow cytometry with antibodies against CD4, CD25, CD127, CD19 and IL-10 before, and after radical surgery. Then, clinical informatics of HCC patients was achieved through Digital Evaluation Score System (DESS) for the assessment of disease severity. Finally, we analysed correlations between digitalized clinical features and kinetics of circulating regulatory lymphocytes.

Results

Level of circulating CD4⁺CD25⁺CD127^- Tregs in HCC patients was significantly lower than that in healthy donors and patients with chronic hepatitis B infection before surgery, but was increased after surgery. Preoperative level of CD19⁺ IL-10⁺ Bregs in HCC patients was also significantly lower than the other groups. However it dramatically was elevated right after surgery and remained elevated compared to controls (about 7 days after surgery, P = 0.04). Frequency of circulating Tregs was correlated with circulating leukocytes, ferritin, and clinical features suggesting tumor aggressiveness including portal vein thrombosis, hepatic vein involvement and advanced clinical stages. Frequency of circulating Bregs was associated with Hepatitis B e Antigen (HBeAg) and Hepatitis B virus (HBV) DNA copy number. In addition, DESS was significantly and positively correlated with other staging systems.

Conclusion

Frequencies of peripheral Tregs and Bregs in HCC patients increased after surgery. These results suggest that a postoperative combination of therapies against Tregs and Bregs may be beneficial for better outcome of HCC patients after resection.

Changes of ferritin and CRP levels in melanoma patients treated with adjuvant interferon-α (EORTC 18952) and prognostic value on treatment outcome

Adjuvant therapy with interferon-α (IFN) only benefits a small subgroup of melanoma patients and a predictive marker selecting responders does not exist. IFN induces increased ferritin and decreased C-reactive protein (CRP) levels; however, an association with treatment effect was not studied. Serum was collected from patients participating in the European Organization for Research and Treatment of Cancer 18 952 trial comparing adjuvant treatment with IFN to observation. Serial ferritin and CRP levels were determined using enzyme-linked immunosorbent assays, before treatment and up to 24 months. Ferritin levels are influenced by sex and age; therefore ratios of serial ferritin and CRP values with corresponding pretreatment values were calculated. Cox regression model and landmark method at end of induction and 6 months were used to evaluate the association between ferritin, CRP and distant metastasis-free survival (DMFS). Baseline ferritin levels were comparable in the two treatment groups (P=0.92). However, ferritin ratios were significantly higher in IFN-treated patients (N=96) compared with untreated patients (N=21) at end of induction (mean: 2.88 vs. 0.75; P=0.0003) and at 6 months (mean: 3.18 vs. 1.02; P=0.009). In the IFN arm, higher ferritin ratios at end of induction and at 6 months were not associated with improved outcome (respectively, P=0.66 and 0.86). Concerning CRP ratios, no differences between the treatment groups, neither an association with DMFS, were observed. Administration of IFN in melanoma patients induced increase in ferritin levels but not in CRP levels. Ferritin and CRP ratios have no prognostic value regarding DMFS.

Iron uptake mediated by binding of H-ferritin to the TIM-2 receptor in mouse cells

Ferritin binds specifically and saturably to a variety of cell types, and recently several ferritin receptors have been cloned. TIM-2 is a specific receptor for H ferritin (HFt) in the mouse. TIM-2 is a member of the T cell immunoglobulin and mucin domain containing (TIM) protein family and plays an important role in immunity. The expression of TIM-2 outside of the immune system indicates that this receptor may have broader roles. We tested whether ferritin binding to TIM-2 can serve as an iron delivery mechanism. TIM-2 was transfected into normal (TCMK-1) mouse kidney cells, where it was appropriately expressed on the cell surface. HFt was labeled with ⁵⁵Fe and ⁵⁵Fe-HFt was incubated with TIM-2 positive cells or controls. ⁵⁵Fe-HFt uptake was observed only in TIM-2 positive cells. HFt uptake was also seen in A20 B cells, which express endogenous TIM-2. TIM-2 levels were not increased by iron chelation. Uptake of ⁵⁵Fe-HFt was specific and temperature-dependent. HFt taken up by TIM-2 positive cells transited through the endosome and eventually entered a lysosomal compartment, distinguishing the HFt pathway from that of transferrin, the classical vehicle for cellular iron delivery. Iron delivered following binding of HFt to TIM-2 entered the cytosol and became metabolically available, resulting in increased levels of endogenous intracellular ferritin. We conclude that TIM-2 can function as an iron uptake pathway.

The role of iron in tumour cell proliferation

Iron has a pivotal role in homeostasis due to its participation in virtually all of the body's oxidation-reduction processes. However, iron can also be considered a double-edged weapon, as its excess may lead to an increased risk of developing cancer, presumably by the generation of reactive oxygen species, and its role as substrate to enzymes that participate in cell proliferation. Thus, iron might as well be considered a cofactor in tumour cell proliferation. In certain pathological conditions, such as haemochromatosis, hepatitis B and C virus infection, asbestosis and endometriosis, iron overload may increase the risk of cancer. By contrast, iron depletion could be considered a useful adjunct in antitumour therapy. This paper reviews the current scientific evidence behind iron's role as a protumoral agent, and the potential benefit of a state of iron depletion in patients with cancer.

Heavy chain ferritin siRNA delivered by cationic liposomes increases sensitivity of cancer cells to chemotherapeutic agents

Approximately half of all gliomas are resistant to chemotherapy, and new therapeutic strategies are urgently needed to treat this cancer. We hypothesized that disrupting iron homeostasis in glioma cells could block tumor growth, based on an acute requirement for high levels of iron to meet energy requirements associated with their rapid growth. Ferritin is best known as an intracellular iron storage protein, but it also localizes to tumor cell nuclei where it seems to protect DNA from oxidative damage and to promote transcription. In this study, we hypothesize that silencing the H-ferritin (heavy chain ferritin) gene could increase tumor sensitivity to chemotoxins. To test this hypothesis, H-ferritin siRNA was delivered to several human cancer cell lines by using cationic liposomes (C-liposome). H-ferritin siRNA decreased protein expression by 80% within 48 hours, and this decrease was associated with more than 50% decrease in the LD(50) for DNA-alkylating agent carmustine (BCNU), which is commonly used to treat glioma in clinic. In a subcutaneous mouse model of human glioma, intratumoral injections of liposomes containing H-ferritin siRNA reduced the effective dose of BCNU needed for tumor suppression by more than 50%. A plasmid supercoil relaxation assay showed that H-ferritin specifically and directly protected DNA from BCNU treatment. H-ferritin siRNA additionally seemed to increase apoptosis in glioma cells in vitro upon H-ferritin knockdown. Overall, our results illustrate how silencing H-ferritin can effectively sensitize tumors to chemotherapy and also show the ability of C-liposomes to serve as a novel in vivo delivery tool for siRNAs.

Cancer biomarker discovery: the entropic hallmark

Background

It is a commonly accepted belief that cancer cells modify their transcriptional state during the progression of the disease. We propose that the progression of cancer cells towards malignant phenotypes can be efficiently tracked using high-throughput technologies that follow the gradual changes observed in the gene expression profiles by employing Shannon's mathematical theory of communication. Methods based on Information Theory can then quantify the divergence of cancer cells' transcriptional profiles from those of normally appearing cells of the originating tissues. The relevance of the proposed methods can be evaluated using microarray datasets available in the public domain but the method is in principle applicable to other high-throughput methods.

Methodology/Principal Findings

Using melanoma and prostate cancer datasets we illustrate how it is possible to employ Shannon Entropy and the Jensen-Shannon divergence to trace the transcriptional changes progression of the disease. We establish how the variations of these two measures correlate with established biomarkers of cancer progression. The Information Theory measures allow us to identify novel biomarkers for both progressive and relatively more sudden transcriptional changes leading to malignant phenotypes. At the same time, the methodology was able to validate a large number of genes and processes that seem to be implicated in the progression of melanoma and prostate cancer.

Conclusions/Significance

We thus present a quantitative guiding rule, a new unifying hallmark of cancer: the cancer cell's transcriptome changes lead to measurable observed transitions of Normalized Shannon Entropy values (as measured by high-througput technologies). At the same time, tumor cells increment their divergence from the normal tissue profile increasing their disorder via creation of states that we might not directly measure. This unifying hallmark allows, via the the Jensen-Shannon divergence, to identify the arrow of time of the processes from the gene expression profiles, and helps to map the phenotypical and molecular hallmarks of specific cancer subtypes. The deep mathematical basis of the approach allows us to suggest that this principle is, hopefully, of general applicability for other diseases.

Serum ferritin: Past, present and future

BACKGROUND

Serum ferritin was discovered in the 1930s, and was developed as a clinical test in the 1970s. Many diseases are associated with iron overload or iron deficiency. Serum ferritin is widely used in diagnosing and monitoring these diseases.

SCOPE OF REVIEW

In this chapter, we discuss the role of serum ferritin in physiological and pathological processes and its use as a clinical tool.

MAJOR CONCLUSIONS

Although many aspects of the fundamental biology of serum ferritin remain surprisingly unclear, a growing number of roles have been attributed to extracellular ferritin, including newly described roles in iron delivery, angiogenesis, inflammation, immunity, signaling and cancer.

GENERAL SIGNIFICANCE

Serum ferritin remains a clinically useful tool. Further studies on the biology of this protein may provide new biological insights.

Macrophage activation syndrome: serological markers and treatment with anti-thymocyte globulin

Two patients presented at the University of Rochester Medical Center with a febrile illness, cytopenias, organ failure (liver failure or respiratory failure), and markedly elevated serum ferritin and sIL-2R. A diagnosis of probable macrophage activation syndrome was made. Both patients failed initial therapy with steroids and cyclosporine, either due to toxicity or lack of efficacy. Both patients responded dramatically to rabbit anti-thymocyte globulin (ATG).

Morphine increases brain levels of ferritin heavy chain leading to inhibition of CXCR4-mediated survival signaling in neurons

This study focuses on the effect of mu-opioid receptor agonists on CXCR4 signaling in neurons and the mechanisms involved in regulation of neuronal CXCR4 by opiates. The data show that CXCR4 is negatively modulated by long-term morphine treatments both in vitro and in vivo; CXCR4 inhibition is caused by direct stimulation of mu-opioid receptors in neurons, leading to alterations of ligand-induced CXCR4 phosphorylation and upregulation of protein ferritin heavy chain (FHC), a negative intracellular regulator of CXCR4. Reduced coupling of CXCR4 to G-proteins was found in the brain of morphine-treated rats, primarily cortex and hippocampus. CXCR4-induced G alpha(i)/G betagamma activities were suppressed after 24 h treatment of cortical neurons with morphine or the selective mu-opioid agonist DAMGO (D-Ala2-N-Me-Phe(4)-glycol(5)-enkephalin), as shown by analysis of downstream targets of CXCR4 (i.e., cAMP, Akt, and ERK1/2). These agonists also prevented CXCL12-induced phosphorylation of CXCR4, indicating a deficit of CXCR4 activation in these conditions. Indeed, morphine (or DAMGO) inhibited prosurvival signaling in neurons. These effects are not attributable to a reduction in CXCR4 expression or surface levels but rather to upregulation of FHC by opioids. The crucial role of FHC in inhibition of neuronal CXCR4 was confirmed by in vitro and in vivo RNA interference studies. Overall, these findings suggest that opiates interfere with normal CXCR4 function in the brain. By this mechanism, opiates could reduce the neuroprotective functions of CXCR4 and exacerbate neuropathology in opiate abusers who are affected by neuroinflammatory/infectious disorders, including neuroAIDS.

Ferritin and FasL (CD95L) mediate density dependent apoptosis in primary rat hepatocytes

Based on a recent description of an apoptosis stimulating property for hepatocyte derived isoferritins, this investigation demonstrates that ferritin, released in vitro from hepatocytes substantially contributes to density dependent apoptosis in primary hepatocytes and is significantly (P < or = 0.05) inhibited by anti-H-ferritin antibody rH02. Furthermore, total protein release and albumin secretion rapidly decline in a time and density dependent mode under serum-free conditions, whereas ferritin secretion, which is upregulated at initial stages of primary culture is not affected by cell density. Supplementation with dexamethasone (DEX) or proliferative stimulation by epidermal growth factor (EGF) and insulin strongly suppresses density dependent apoptosis. Both regimens have previously been shown to inhibit isoferritin mediated apoptosis in hepatocytes, most likely by interrupting proapotitc mitochondrial signalling. Finally, FasL/Fas also participates in density dependent apoptosis, since apoptosis is significantly (P < or = 0.005) reduced in high density cultures supplemented with an anti-FasL antibody. This antibody has also been shown to neutralise ferritin mediated apoptosis in primary hepatocytes, suggesting a linkage of ferritin and Fas in density dependent apoptosis. In conclusion, ferritin contributes to apoptosis in primary hepatocytes in an autocrine, density dependent mode, involving Fas stimulation and proapoptotic mitochondrial signalling. With respect to liver physiology, these findings may indicate that ferritin plays a yet unrecognised role as an acute phase signalling molecule in early stages of tissue repair and liver regeneration, and may also be responsible for the limited ability to propagate human hepatocytes in culture and the limited expansion of donor cells in the recipient liver upon cell transplantation.

Ferritins: a family of molecules for iron storage, antioxidation and more

Ferritins are characterized by highly conserved three-dimensional structures similar to spherical shells, designed to accommodate large amounts of iron in a safe, soluble and bioavailable form. They can have different architectures with 12 or 24 equivalent or non-equivalent subunits, all surrounding a large cavity. All ferritins readily interact with Fe(II) to induce its oxidation and deposition in the cavity in a mineral form, in a reaction that is catalyzed by a ferroxidase center. This is an anti-oxidant activity that consumes Fe(II) and peroxides, the reagents that produce toxic free radicals in the Fenton reaction. The mechanism of ferritin iron incorporation has been characterized in detail, while that of iron release and recycling has been less thoroughly studied. Generally ferritin expression is regulated by iron and by oxidative damage, and in vertebrates it has a central role in the control of cellular iron homeostasis. Ferritin is mostly cytosolic but is found also in mammalian mitochondria and nuclei, in plant plastids and is secreted in insects. In vertebrates the cytosolic ferritins are composed of H and L subunit types and their assembly in a tissues specific ratio that permits flexibility to adapt to cell needs. The H-ferritin can translocate to the nuclei in some cell types to protect DNA from iron toxicity, or can be actively secreted, accomplishing various functions. The mitochondrial ferritin is found in mammals, it has a restricted tissue distribution and it seems to protect the mitochondria from iron toxicity and oxidative damage. The various functions attributed to the cytosolic, nuclear, secretory and mitochondrial ferritins are discussed.

New functions for an iron storage protein: the role of ferritin in immunity and autoimmunity

Ferritin is a ubiquitous and specialised protein involved in the intracellular storage of iron; it is also present in serum and other biological fluids, although its secretion processes are still unclear. We here review evidence supporting the hypothesis that macrophages play a role in the production and secretion of extracellular ferritin, as well as evidence supporting a novel function as a signalling molecule and immune regulator. In particular, H-ferritin, which inhibits the proliferation of lymphoid and myeloid cells, may be regarded as a negative regulator of human and murine hematopoiesis. The idea that it also acts as a signalling protein has been supported by the cloning and characterisation of the specific H-ferritin receptor TIM-2, a member of the TIM gene family. A number of studies of the mouse TIM gene family indicate that this protein plays an important role in immune-mediated diseases. This last finding, together with the fact that ferritin acts as an immuno-suppressor, has allowed us to formulate hypotheses regarding the possible role of alterations of H-ferritin/TIM-2 binding/signalling in the pathogenesis of autoimmune diseases.

Immune regulation by the TIM gene family

Recent studies have demonstrated that proteins of the T cell immunoglobulin and mucin domain (TIM) family are important regulators of immune function. Here we discuss the functional effects of TIM proteins on immune responses, how the effects of TIM proteins may be modulated by interactions with ligands and the limited information available on intracellular signals downstream of TIM proteins.

Ferritin-a mediator of apoptosis?

Previously we have demonstrated an apoptosis inducing activity for a rat hepatocyte conditioned medium (CM) presumably mediated by acidic isoferritins. Here, we present support for this assumption since isoferritins purified from different rat hepatocyte CM significantly enhanced the frequency of apoptotic cells in primary rat hepatocytes, an effect completely inhibited by a neutralizing anti-H-ferritin antibody. The apoptosis induction appears to be related to a 43 kDa ferritin subunit contained in the isoferritins released from primary hepatocytes, presumably representing a ferritin heavy/light chain heterodimer. In addition, these isoferritins immunologically crossreact with antibodies raised against placental isoferritin p43-PLF (which also contains a 43 kDa ferritin subunit) and melanoma-derived H-chain ferritin, representing ferritin isoforms which reveal immunomodulatory properties. Furthermore, p53 and FasL are upregulated upon isoferritin treatment in a time dependent mode, and apoptosis induction can be suppressed by neutralizing anti-FasL antibodies. Proapoptotic Bid is upregulated too and translocated into mitochondria in primary hepatocytes exposed to the isoferritins purified from the CM. Finally, epidermal growth factor (EGF) and dexamethasone (DEX), which counteract proapoptotic mitochondrial signalling, almost completely abolished the proapoptotic effect of the hepatocyte derived isoferritins. In conclusion, our findings demonstrate that acidic isoferritins with homology to immunomodulatory ferritin isoforms (p43-PLF, melanoma-derived-H-chain ferritin) are released from hepatocytes in vitro, and are able to stimulate upregulation of p53 and mediate apoptosis involving Fas (CD95) signalling as well as addressing the intrinsic mitochondrial proapoptotic pathway.

Iron-withholding strategy in innate immunity

The knowledge of how organisms fight infections has largely been built upon the ability of host innate immune molecules to recognize microbial determinants. Although of overwhelming importance, pathogen recognition is but only one of the facets of innate immunity. A primitive yet effective antimicrobial mechanism which operates by depriving microbial organisms of their nutrients has been brought into the forefront of innate immunity once again. Such a tactic is commonly referred to as the iron-withholding strategy of innate immunity. In this review, we introduce various vertebrate iron-binding proteins and their invertebrate homologues, so as to impress upon readers an obscured arm of innate immune defense. An excellent comprehension of the mechanics of innate immunity paves the way for the possibility that novel antimicrobial therapeutics may emerge one day to overcome the prevalent antibiotic resistance in bacteria.

Dendritic cells from chronic lymphocytic leukemia patients are normal regardless of Ig V gene mutation status

Patients with B-type chronic lymphocytic leukemia (B-CLL) segregate into 2 subgroups based on the mutational status of the immunoglobulin (Ig) V genes and the patients in these subgroups follow very different clinical courses. To examine whether dendritic cells (DCs) generated from CLL patients can be candidates for immune therapy, we compared the phenotypic and functional capacities of DCs generated from patients of the 2 CLL subgroups (normal age-matched subjects [normal-DCs]). Our data show that immature DCs from B-CLL patients (B-CLL-DCs) have the same capacity to take up antigen as those from normal controls. Furthermore, B-CLL-DCs generated from the 2 CLL subgroups up-regulated MHC-II, CD80, CD86, CD83, CD40, and CD54 and down-regulated CD206 in response to stimulation with a cocktail of cytokines (CyC) and secreted increased levels of tumor necrosis factor alpha, interleukin (IL)-8, IL-6, IL-12 (p70), and RANTES in a manner typical of mature normal-DCs. Interestingly, CD54 was significantly more up-regulated by CyC in B-CLL-DCs compared with normal-DCs. Except for CD54, no significant differences in surface molecule expression were observed between normal-DCs and B-CLL-DCs. B-CLL-DCs from both subgroups, including 6 patients with VH1-69, that usually fare poorly, presented tetanus toxoid to autologous T cells in vitro similar to normal- DCs. Our data show that DCs generated from the B-CLL subgroup with unmutated Ig V genes are functionally normal. These results are very promising for the use of DCs from patients with poor prognosis for immunotherapy.

Prostaglandin E2 impairs CD4+ T cell activation by inhibition of lck: implications in Hodgkin's lymphoma

Many tumors, including Hodgkin's lymphoma, are associated with decreased cellular immunity and elevated levels of prostaglandin E(2) (PGE(2)), a known inhibitor of CD4+ T cell activation, suggested to be involved in immune deviation in cancer. To address the molecular mechanisms tumor-derived PGE(2) might have on primary human CD4+ T cells, we used a whole genome-based transcriptional approach and show that PGE(2) severely limited changes of gene expression induced by signaling through the T cell receptor and CD28. This data suggests an interference of PGE(2) at an early step of T cell receptor signaling: indeed, PGE(2) stimulation of T cells leads to inactivation of lck and reduced phosphorylation of ZAP70. Antiapoptotic genes escaped PGE(2)-induced inhibition resulting in partial protection from apoptosis in response to irradiation or Fas-mediated signaling. As a functional consequence, PGE(2)-treated CD4+ T cells are arrested in the cell cycle associated with up-regulation of the cyclin/cyclin-dependent kinase inhibitor p27(kip1). Most importantly, CD4+ T cells in Hodgkin's lymphoma show similar regulation of genes that were altered in vitro by PGE(2) in T cells from healthy individuals. These data strongly suggest that PGE(2) is an important factor leading to CD4+ T cell impairment observed in Hodgkin's lymphoma.

Ferritin contributes to melanoma progression by modulating cell growth and sensitivity to oxidative stress

PURPOSE

Employing an in vitro model system of human melanoma progression, we previously reported ferritin light chain (L-ferritin) gene overexpression in the metastatic phenotype. Here, we attempted to characterize the role of ferritin in the biology of human melanoma and in the progression of this disease.

EXPERIMENTAL DESIGN

Starting from the LM human metastatic melanoma cell line, we engineered cell clones in which L-ferritin gene expression was down-regulated by the stable expression of a specific antisense construct. These cells were then assayed for their growth capabilities, chemoinvasive properties, and sensitivity to oxidative stress. Additionally, ferritin protein content in primary and metastatic human melanomas was determined by immunohistochemistry.

RESULTS

Artificial L-ferritin down-regulation in the LM cells strongly inhibited proliferation and chemoinvasion in vitro and cell growth in vivo. In addition, L-ferritin down-regulated cells displayed enhanced sensitivity to oxidative stress and to apoptosis. Concurrently, immunohistochemical analysis of a human melanoma tissue array revealed that ferritin expression level in metastatic lesions was significantly higher (P < 0.0001) than in primary melanomas. Furthermore, ferritin expression was constantly up-regulated in autologous lymph node melanoma metastases when compared with the respective primary tumors in a cohort of 11 patients.

CONCLUSIONS

These data suggest that high ferritin expression can enhance cell growth and improve resistance to oxidative stress in metastatic melanoma cells by interfering with their cellular antioxidant system. The potential significance of these findings deserves to be validated in a clinical setting.

Regulated secretion of glycosylated human ferritin from hepatocytes

Serum ferritin has been used widely in clinical medicine chiefly as an indicator of iron stores and inflammation. Circulating ferritin also can have paracrine effects. Despite the clinical significance of serum ferritin, its secretion remains an enigma. The consensus view is that serum ferritin arises from tissue ferritins--principally ferritin light--which can be glycosylated. Ferritin heavy and light chains are cytosolic proteins that form cages of 24 subunits to store intracellular iron. We show that ferritin light is secreted when its expression is increased in stable, transfected HepG2 cells or adenovirus-infected HepG2 cells. Export occurs through the classical secretory pathway and some chains are N-glycosylated. Ferritins do not need to form cages prior to secretion. Secretion is blocked specifically, effectively, and rapidly by a factor in serum. The timing of this inhibition of ferritin secretion suggests that normally cytosolic ferritin L is targeted to the secretory pathway during translation despite the absence of a conventional signal sequence. Thus, secretion of glycosylated and unglycosylated ferritin is a regulated and not a stochastic process.

Synoviocyte-mediated expansion of inflammatory T cells in rheumatoid synovitis is dependent on CD47-thrombospondin 1 interaction

Fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis elicit spontaneous proliferation of autologous T cells in an HLA-DR and CD47 costimulation-dependent manner. T cell costimulation through CD47 is attributed to specific interaction with thrombospondin-1 (TSP1), a CD47 ligand displayed on FLS. CD47 binding by FLS has broad biological impact that includes adhesion and the triggering of specific costimulatory signals. TSP1(+) FLS are highly adhesive to T cells and support their aggregation and growth in situ. Long-term cultures of T cells and FLS form heterotypic foci that are amenable to propagation without exogenous growth factors. T cell adhesion and aggregate formation on TSP1(+) FLS substrates are inhibited by CD47-binding peptides. In contrast, FLS from arthroscopy controls lack adhesive or T cell growth-promoting activities. CD47 stimulation transduces a costimulatory signal different from that of CD28, producing a gene expression profile that included induction of ferritin L chain, a component of the inflammatory response. Ferritin L chain augments CD3-induced proliferation of T cells. Collectively, these results demonstrate the active role of FLS in the recruitment, activation, and expansion of T cells in a CD47-dependent manner. Because TSP1 is abundantly expressed in the rheumatoid synovium, CD47-TSP1 interaction is proposed to be a key component of an FLS/T cell regulatory circuit that perpetuates the inflammatory process in the rheumatoid joint.

PLIF induces IL-10 production in monocytes: a calmodulin-p38 mitogen-activated protein kinase-dependent pathway

Recently, we reported the cloning and preliminary characterization of a novel human immunomodulator named PLIF (placenta immunomodulatory ferritin). PLIF has a unique molecular structure, which is composed of a ferritin heavy chain-like domain and a novel cytokine-like domain called C48. Both intact molecule and C48 inhibit T cell proliferation following allogeneic or anti-CD3 stimuli. PLIF is localized at the fetal-maternal interface of human placenta and might play a role in down-modulating the maternal immune reaction toward the embryo. The inhibitory effect of PLIF on T cell activation can be direct, indirect through cytokine mediators, or both. In the present study we investigated the possible indirect effects of PLIF by using its bioactive domain C48. Measurement of various cytokines revealed that C48, predominantly, induce pronounced and rapid IL-10 production in monocytes, which is immune activation-independent. Further, we discovered that C48-induced IL-10 production is mediated through a calcium/calmodulin-p38 mitogen-activated protein (MAP) kinase signaling pathway. However, extracellular signal-related kinases1,2 (ERK1,2), also activated by C48 stimulation, exhibited a limiting effect on IL-10 production.

Aspects of cancer immunotherapy

Cancer immunotherapy has traditionally undergone a 'revolution' every decade, from the use of Bacille Calmette-Guérin by scarification in the 1970s, to interleukin-2 therapies in the 1980s, and monoclonal antibody treatments in the early 1990s. Usually the early reports on the use of such agents were encouraging, but when more patients were studied in multiple centres, the initial promising results could not be confirmed. Now in a new century, we have more reagents and methods available than ever before - indeed, with such a plethora of reagents it is difficult to envisage them being fully and appropriately tested within the next decade, by which time there will be even more reagents to test. However, there have been three major advances which should lead to substantial progress in cancer immunotherapy: (1) the widespread use of genetic engineering, enabling identification of candidate vaccine proteins and manipulation of their sequences; (2) the production of antigens, antibodies and cytokines in large amounts by recombinant technologies, and (3) an understanding of the mode of presentation of peptides by major histocompatibility complex Class I and Class II molecules and their recognition by T cells. Despite these advances, there are major problems facing cancer immunotherapy, such as the ability of tumours to mutate and evade the immune system and the difficulty of precisely defining the interactions of effector cells in mediating 'rejection' or destruction of a tumour. There are clearly immunological similarities with diseases such as malaria and schistosomiasis, where the invading foreign organisms can use a variety of strategies to resist an elicited immune response. The failure to find a suitable vaccine for these diseases must lead to some pessimism for the development of immunotherapy for an autologous tumour. However, there are promising studies now in progress which should give an indication of the most important directions to follow. This review provides a commentary on aspects of cancer immunotherapy and in particular will deal with: (1) the selection of antigens as vaccine components; (2) the modes of presentation of antigens, particularly by major histocompatibility complex Class I molecules; and (3) new modes of delivery of vaccine immunogens.

The mengovirus leader protein suppresses alpha/beta interferon production by inhibition of the iron/ferritin-mediated activation of NF-kappa B

In our studies on the biological function of the mengovirus leader protein, we identified a casein kinase II (CK-2) phosphorylation site in the protein. Here we report that the mengovirus leader protein can be phosphorylated by CK-2 in vitro. Expression of a recombinant leader protein in which the consensus CK-2 sequence around threonine 47 was disturbed resulted in a mutant protein that could no longer be phosphorylated. The CK-2 consensus sequence was modified by site-directed mutagenesis and subsequently introduced into a mengovirus cDNA clone to investigate the effect of the phosphorylation of the leader protein on virus replication and on the host cell response. Modifications by which the CK-2 consensus sequence was disturbed resulted in mutant viruses with reduced growth kinetics. We demonstrated that the integrity of the CK-2 phosphorylation site of the mengovirus leader protein was specifically related to the suppression of NF-kappa B activation and subsequent suppression of alpha/beta interferon production in infected cells. We also found that the integrity of the CK-2 phosphorylation site of the leader protein coincided with an increase of ferritin expression in the infected cell. These data indicate that the leader protein suppresses the iron-mediated activation of NF-kappa B and thereby inhibits alpha/beta interferon expression in the infected cell.