Regulation of ferritin: a specific role for interferon-alpha (IFN-alpha)? The acute phase response in patients treated with IFN-alpha-2b

Type I interferon score is associated with the severity and poor prognosis in anti-MDA5 antibody-positive dermatomyositis patients

Objectives

To investigate the clinical significance of the interferon (IFN) score, especially the IFN-I score, in patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis (anti-MDA5+ DM).

Methods

We enrolled 262 patients with different autoimmune diseases, including idiopathic inflammatory myopathy, systemic lupus erythematosus, rheumatoid arthritis, adult-onset Still’s disease, and Sjögren’s syndrome, as well as 58 healthy controls. Multiplex quantitative real-time polymerase chain reaction (RT-qPCR) using four TaqMan probes was used to evaluate type I IFN-stimulated genes (IFI44 and MX1), one type II IFN-stimulated gene (IRF1), and one internal control gene (HRPT1), which were used to determine the IFN-I score. The clinical features and disease activity index were compared between the high and low IFN-I score groups in 61 patients with anti-MDA5+ DM. The associations between laboratory findings and the predictive value of the baseline IFN-I score for mortality were analyzed.

Results

The IFN score was significantly higher in patients with anti-MDA5+ DM than in healthy controls. The IFN-I score was positively correlated with the serum IFN-α concentration, ferritin concentration, and Myositis Disease Activity Assessment Visual Analogue Scale (MYOACT) score. Compared with patients with a low IFN-I score, patients with a high IFN-I score showed a higher MYOACT score, C-reactive protein concentration, aspartate transaminase concentration, ferritin concentration, plasma cell percentage, and CD3+ T-cell percentage, as well as lower lymphocyte, natural killer cell, and monocyte counts. The 3-month survival rate was significantly lower in patients with an IFN-I score of >4.9 than in those with an IFN-I score of ≤4.9 (72.9% vs. 100%, respectively; P = 0.044).

Conclusion

The IFN score, especially the IFN-I score, measured by multiplex RT-qPCR is a valuable tool to monitor disease activity and predict mortality in patients with anti-MDA5+ DM.

Oral famotidine versus placebo in non-hospitalised patients with COVID-19: a randomised, double-blind, data-intense, phase 2 clinical trial

OBJECTIVE

We assessed whether famotidine improved inflammation and symptomatic recovery in outpatients with mild to moderate COVID-19.

DESIGN

Randomised, double-blind, placebo-controlled, fully remote, phase 2 clinical trial (NCT04724720) enrolling symptomatic unvaccinated adult outpatients with confirmed COVID-19 between January 2021 and April 2021 from two US centres. Patients self-administered 80 mg famotidine (n=28) or placebo (n=27) orally three times a day for 14 consecutive days. Endpoints were time to (primary) or rate of (secondary) symptom resolution, and resolution of inflammation (exploratory).

RESULTS

Of 55 patients in the intention-to-treat group (median age 35 years (IQR: 20); 35 women (64%); 18 African American (33%); 14 Hispanic (26%)), 52 (95%) completed the trial, submitting 1358 electronic symptom surveys. Time to symptom resolution was not statistically improved (p=0.4). Rate of symptom resolution was improved for patients taking famotidine (p<0.0001). Estimated 50% reduction of overall baseline symptom scores were achieved at 8.2 days (95% CI: 7 to 9.8 days) for famotidine and 11.4 days (95% CI: 10.3 to 12.6 days) for placebo treated patients. Differences were independent of patient sex, race or ethnicity. Five self-limiting adverse events occurred (famotidine, n=2 (40%); placebo, n=3 (60%)). On day 7, fewer patients on famotidine had detectable interferon alpha plasma levels (p=0.04). Plasma immunoglobulin type G levels to SARS-CoV-2 nucleocapsid core protein were similar between both arms.

CONCLUSIONS

Famotidine was safe and well tolerated in outpatients with mild to moderate COVID-19. Famotidine led to earlier resolution of symptoms and inflammation without reducing anti-SARS-CoV-2 immunity. Additional randomised trials are required.

Tumor interferon signaling and suppressive myeloid cells are associated with CAR T-cell failure in large B-cell lymphoma

Axicabtagene ciloleucel (axi-cel) is a chimeric antigen receptor (CAR) T-cell therapy for relapsed or refractory large B-cell lymphoma (LBCL). This study evaluated whether immune dysregulation, present before CAR T-cell therapy, was associated with treatment failure. Tumor expression of interferon (IFN) signaling, high blood levels of monocytic myeloid-derived suppressor cells (M-MDSCs), and high blood interleukin-6 and ferritin levels were each associated with a lack of durable response. Similar to other cancers, we found that in LBCL tumors, IFN signaling is associated with the expression of multiple checkpoint ligands, including programmed cell death-ligand 1, and these were higher in patients who lacked durable responses to CAR-T therapy. Moreover, tumor IFN signaling and blood M-MDSCs associated with decreased axi-cel expansion. Finally, patients with high tumor burden had higher immune dysregulation with increased serum inflammatory markers and tumor IFN signaling. These data support that immune dysregulation in LBCL promotes axi-cel resistance via multiple mechanistic programs: insufficient axi-cel expansion associated with both circulating M-MDSC and tumor IFN signaling, which also gives rise to expression of immune checkpoint ligands.

Lipids, glucose and iron metabolic alterations in chronic hepatitis C after viral eradication - comparison of the new direct-acting antiviral agents with the old regimens

BACKGROUND

Hepatitis C virus (HCV) is a unique virus which interacts with cholesterol, iron and insulin metabolism. There is limited data on the effects of direct-acting antiviral agents (DAAs) on metabolic profiles. We aimed at evaluating the behavior of metabolic risk factors of chronically HCV-infected patients after sustained virologic response (SVR), comparing the outcomes with the new DAAs versus the old treatment regimen Peg-interferon ± ribavirin.

METHODS

A total of 178 patients who achieved SVR and completed one year of follow-up were prospectively included in this study: group 1 with 105 patients treated with DAAs and group 2 with 73 patients treated with old regimens. Outcomes included lipid, glucose and iron metabolism variation after SVR.

RESULTS

There was a significant increase in total cholesterol in both groups (group 1: p < .001, 95% CI: 0.41-0.78; group 2: p < .001, 95% CI: 0.24-0.69). Triglyceride levels significantly decreased (p = .015, 95% CI: -0.33-0.04) in group 1 and increased (p = .014, 95% CI: 0.07-0.59) in group 2. LDL levels increased in group 1 (p = .029, 95% CI: 0.05-0.88), but no significant variation was found in group 2. No significant variation in HDL, fast glucose and iron was seen in both groups. There was a significant increase of HOMA (p = .002, 95% CI: 0.17592-0.72317) only in group 2. Ferritin serum levels significantly decreased (p < .001, 95% CI:-138.3-74.4) in group 1 but no significant variation was found in group 2.

CONCLUSION

Patients who have achieved SVR may have increased risk of cardiovascular outcomes due to development of hyperlipidemia and insulin resistance.

Markers of iron status in chronic kidney disease

Anemia is one of the main comorbidities related to chronic kidney disease (CKD). Until the advent of erythropoiesis stimulating agents (ESA), endogenous erythropoietin deficiency has been thought to be the main culprit of anemia in CKD patients. The use of ESAs has shed new light on the physiology of CKD anemia, where iron homeostasis plays an increasingly important role. Disorders of iron homeostasis occurring in CKD turn the anemia management in those patients into a complex multifactorial therapeutic task, where ESA and Iron dose must be properly balanced to achieve the desired outcome without exposing the patients to the risk of serious adverse events. This review covers diagnostic markers traditionally used for quantifying iron status in CKD patients, such as serum ferritin and transferrin saturation, new ones, such as reticulocyte hemoglobin content and percent hypochromic red cells (HRC), as well as experimental ones, such as hepcidin and soluble transferrin receptor (sTfR). Each marker is presented in terms of their diagnostic performance, followed by biological and analytical variability data. Advantages and disadvantages of each marker are briefly discussed. Although serum ferritin and transferrin saturation are easily available, they exhibit large biological variability and require caution when used for diagnosing iron status in CKD patients. Reticulocyte hemoglobin content and the percentage of HRC are more powerful, but their widespread use is hampered by the issue of sample stability in storage. sTfR and hepcidin show promise, but require further investigation as well as the development of standardized, low-cost assay platforms.

Serum ferritin level correlates with SLEDAI scores and renal involvement in SLE

Introduction

Ferritin is an acute-phase reactant that is elevated in various autoimmune disorders. Serum ferritin levels have been positively correlated with disease activity scores of rheumatoid arthritis and systemic lupus erythematosus (SLE). Further, enhanced levels of ferritin have also been reported in lupus nephritis. However, there are no reports from the Indian subcontinent.

Methods

Seventy-six female SLE patients, diagnosed on the basis of revised ACR criteria, and 50 healthy females, age matched from similar geographical areas, were enrolled in the present study. Serum levels of ferritin, IFN-α and IL-6 were quantified by enzyme-linked immunosorbent assay (ELISA). Clinical, biochemical, serological and other markers of disease activity (C3, C4 and anti-dsDNA) were measured by standard laboratory procedure.

Results

Serum ferritin levels were significantly higher in SLE patients compared to healthy controls ( p < 0.0001). Ferritin levels positively correlated with SLE Disease Activity Index (SLEDAI) ( p = 0.001, r = 0.35), anti-dsDNA ( p = 0.001, r = 0.35), IFN-α ( p < 0.0001, r = 0.51) and IL-6 (p < 0.0001, r = 0.65) and negatively correlated with C3 ( p = 0.0006, r = −0.38) and C4 ( p = 0.01, r = −0.28). Interestingly, serum levels of ferritin were positively associated with proteinuria ( p = 0.001, r = 0.36), serum urea ( p = 0.0004, r = 0.39) and serum creatinine ( p = 0.0006, r = 0.38).

Conclusion

Serum ferritin is an excellent marker of disease activity and renal dysfunction in SLE.

Predictive role of acute phase reactants in the response to therapy in patients with chronic hepatitis C virus infection

BACKGROUND/AIMS

Biochemical parameters and acute-phase proteins (APPs) may provide complementary data in patients with chronic hepatitis C (CHC). We aimed to evaluate the predictive role of APPs in the response to antiviral therapy.

METHODS

Forty-five patients underwent antiviral therapy. Serum ferritin, C-reactive protein (CRP), transferrin, albumin, alpha-1 acid glycoprotein (A1AG), and alpha-2 macroglobulin (A2MG) levels were examined at the initial evaluation and at the 4th, 12th, and 48th weeks. HCV RNA levels were examined at the initial evaluation and at the 12th and 48th weeks.

RESULTS

Ferritin, transferrin, A1AG, and A2MG levels were significantly higher in the patient group (p<0.05). CRP, ferritin, A1AG, and A2MG levels were significantly increased from baseline to the 4th week (p<0.05). The responders and nonresponders to antiviral therapy had insignificantly but remarkably different levels of CRP, ferritin, transferrin, A1AG, A2MG, and alanine aminotransferase (ALT) both at the initial evaluation and at the 12th week.

CONCLUSIONS

Variations in ferritin, A1AG, A2MG, albumin, CRP, and transferrin levels are not alternatives to virological and biochemical parameters for predicting an early response to therapy in patients with CHC. However, the investigation of ALT levels and hepatitis C virus RNA in combination with acute-phase reactants may provide supplementary data for evaluating responses to antiviral therapy.

Serum ferritin levels in chronic hepatitis C patients during antiviral therapy and prediction of treatment response

OBJECTIVE

Increased serum ferritin (SF) levels are encountered in various conditions, such as inflammatory syndromes and haemochromatosis. Interferon alpha is one of the stimulants of SF. In this study we aimed to evaluate SF changes in patients with chronic hepatitis C (CHC) during antiviral therapy, and the relationship between SF and treatment response.

METHODS

Data from a total of 97 patients who had received peginterferon (PEG-IFN) plus ribavirin combination therapy for CHC, and who had been followed up for more than 6 months after treatment, were analyzed retrospectively. Patients who had undetectable hepatitis C virus RNA at 6 months after the completion of antiviral therapy were regarded as having achieved a sustained viral response (SVR), while the remaining patients were categorized as non-SVR. Differences in SF levels during therapy between SVR patients and non-SVR patients were examined.

RESULTS

We found that patients who achieved SVR had lower baseline ferritin levels. It was observed that SF levels increased dramatically in both the SVR and non-SVR groups after starting therapy, remained high until the end of the treatment period, and returned to baseline levels after completion of treatment. However the SF rise was found to be significantly higher in patients who achieved an SVR than in those without SVR at each time-point during treatment.

CONCLUSIONS

SF levels increase during PEG-IFN-based therapy for CHC. A lower SF level before starting treatment and higher SF levels during therapy appear to be associated with a favourable treatment response. Therefore, rises in SF, especially during the early phase of treatment, could be a predictor of SVR.

Serum ferritin concentration and transferrin saturation before liver transplantation predict decreased long-term recipient survival

Serum ferritin (SF) concentration is a widely available parameter used to assess iron homeostasis. It has been described as a marker to identify high-risk patients awaiting liver transplantation (LT) but is also elevated in systemic immune-mediated diseases, metabolic syndrome, and in hemodialysis where it is associated with an inferior prognosis. This study analyzed whether SF is not only a predictor of liver-related mortality prior to LT but also an independent marker of survival following LT. In a dual-center, retrospective study, a cohort of 328 consecutive first-LT patients from Hannover Medical School, Germany (2003-2008, follow-up 1260 days), and 82 consecutive LT patients from Regensburg University Hospital, Germany (2003-2007, follow-up 1355 days) as validation cohort were analyzed. In patients exhibiting SF ≥365 μg/L versus <365 μg/L prior to LT, 1-, 3-, and 5-year post-LT survival was 73.3% versus 81.1%, 64.4% versus 77.3%, and 61.1% versus 74.4%, respectively (overall survival P = 0.0097), which was confirmed in the validation cohort (overall survival of 55% versus 83.3%, P = 0.005). Multivariate analyses identified SF ≥365 μg/L combined with transferrin saturation (TFS) <55%, hepatocellular carcinoma, and the survival after LT (SALT) score as independent risk factors for death. In patients with SF concentrations ≥365 μg/L and TFS <55%, overall survival was 54% versus 74.8% in the remaining group (P = 0.003). In the validation cohort, it was 28.6% versus 72% (P = 0.017), respectively.

CONCLUSION

SF concentration ≥365 μg/L in combination with TFS <55% before LT is an independent risk factor for mortality following LT. Lower TFS combined with elevated SF concentrations indicate that acute phase mechanisms beyond iron overload may play a prognostic role. SF concentration therefore not only predicts pre-LT mortality but also death following LT.

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.

The prognostic value of changes in serum ferritin levels during therapy for hepatitis C virus infection

An increase in serum ferritin levels during combined interferon-ribavirin treatment in chronic patients infected with hepatitis C virus (HCV) can occur. A study was conducted to determine whether observing the kinetics of serum ferritin levels during antiviral therapy, may assist in predicting the rate of sustained virological response. The kinetics of serum ferritin levels during antiviral therapy in treatment-naive, adherent patients with chronic HCV who had early virological response were characterized. Thirteen patients achieved sustained virological response (group 1) while eight patients did not (group 2). Pre-treatment serum ferritin levels were higher in group 2 patients. During antiviral therapy, serum ferritin levels increased in both groups. On treatment, the median increase (compared to baseline) and the calculated rate of the increase in serum ferritin levels was higher in group 1 patients (874% vs. 272%, P < 0.05, 63%/week vs. 13%/week, P = 0.024, respectively). Red blood cell lysis did not contribute to the increase in serum ferritin level. Post-treatment (1st month) serum ferritin levels in group 1 patients were lower than in group 2 patients. In addition, the degree of decline in the 1st month serum ferritin levels (from peak levels) in group 1 patients was higher (76% vs. 49%, P = 0.039). Measuring serum ferritin levels during antiviral therapy in HCV patients who had an early virological response may assist in predicting sustained virological response.

A possible role for secreted ferritin in tissue iron distribution

Ferritin is known as a well-conserved iron detoxification and storage protein that is found in the cytosol of many prokaryotic and eukaryotic organisms. In insects and worms, ferritin has evolved into a classically secreted protein that transports iron systemically. Mammalian ferritins are found intracellularly in the cytosol, as well as in the nucleus, the endo-lysosomal compartment and the mitochondria. Extracellular ferritin is found in fluids such as serum and synovial and cerebrospinal fluids. We recently characterized the biophysical properties, secretion mechanism and cellular origin of mouse serum ferritin, which is actively secreted by a non-classical pathway involving lysosomal processing. Here, we review the data to support a hypothesis that intracellular and extracellular ferritin may play a role in intra- and intercellular redistribution of iron.

Immunologic functions as prognostic indicators in melanoma

Outcome in melanoma patients with advanced disease is poor and systemic treatment seems to benefit only a subset of patients. Predictive markers identifying these patients are currently not available. Early studies showed an association of immune-related side effects such as vitiligo and autoimmune thyroiditis with response to IL-2 or IFNα treatment. However, conflicting data have been reported as well, mentioning the effect of a higher rate of immune-related toxicities during prolonged administration of the drug in responders. The review discusses the prognostic significance of autoimmunity during various forms of immunotherapy and stresses the importance of correcting for guarantee-time bias. In addition, other immune-related factors which have been associated with melanoma prognosis such as, CRP, white blood cell count, absolute lymphocyte count and human leukocyte antigen will be reviewed as well. A better understanding of the immune system and the host-tumor interactions should ultimately lead to more effective treatment. A major challenge expected to be addressed in future is proving ways to uncouple tumor immunity from autoimmunity.

Serum ferritin as a predictor of treatment outcome in patients with chronic hepatitis C

OBJECTIVES

Antiviral treatment in chronic hepatitis C (CHC) involves ribavirin, a hemolytic agent. We planned a prospective study to evaluate whether drug-induced iron perturbation is clinically relevant as it relates to therapeutic outcome.

METHODS

Iron variables were sequentially assessed in 206 CHC patients undergoing antiviral therapy and were correlated with pretreatment iron status and histology, hemolysis, and therapeutic outcome.

RESULTS

At week 1 of therapy, serum iron (SI), transferrin saturation (TS), and serum ferritin (SF) increased markedly in all patients. All iron parameters correlated with hemolysis up to week 4; this correlation was lost for SF at later time points. SF rise during treatment was inversely related to baseline SF and iron deposits in hepatic mesenchymal/Kupffer cells. Both baseline SF and mesenchymal iron significantly correlated with fibrosis at multivariate analysis (P=0.015 and 0.008, respectively). Interestingly, baseline SF, despite good specificity (89%), had low sensitivity in predicting siderosis (25%). During therapy, SI, TS, and hemolysis parameters did not correlate with sustained virological response (SVR), whereas SF rise became an independent predictor of therapeutic response: a 2.5-fold increase of SF at week 12 associated with higher likelihood of SVR (odds ratio 1.91, P=0.032). Accordingly, lack of mesenchymal iron deposits at the baseline biopsy correlated with SVR (odds ratio 3.02, P=0.043).

CONCLUSIONS

In CHC, SF is a useful marker for assessing disease duration and progression before starting treatment and for predicting therapeutic response while on therapy. SF rise during antiviral therapy is largely independent of hemolysis and likely indicates activation of macrophages in response to antivirals.

Increased ferritin response in adult Still's disease: specificity and relationship to outcome

BACKGROUND

The disproportionate ferritin response encountered in some patients with adult Still's disease (ASD) may reflect a fundamental aspect in the pathophysiology of ASD.

METHODS

An observational case-control study of 22 ASD patients followed for 63 months. Baseline laboratory data were compared with age- and gender-matched controls with new-onset rheumatoid arthritis (RA). Serum levels of ferritin and C-reactive protein (CRP) and the ferritin/CRP ratio were related to clinical outcome in ASD through nonparametric statistical analyses.

RESULTS

Compared to RA patients, haemoglobin levels were lower (11.8 vs. 13.5 g/dL; p = 0.009) and leucocyte counts (17.1 vs. 8.6 10(9)/mL; p<0.001), erythrocyte sedimentation rate (ESR) (84 vs. 38 mm; p = 0.001), CRP (154 vs. 27 mg/L; p<0.001), aspartate aminotransferase (ASAT) (52 vs. 23 U/l; p = 0.004), serum ferritin (8750 vs. 62 microg/L; p<0.001) and ferritin/CRP ratios (9.7 vs. 1.7; p<0.001) were higher in ASD patients at baseline. Six patients (27%) achieved sustained remission (monocyclic disease), while 16 patients (73%) developed chronic disease (progressive in 27%, relapsing/remitting in 46%). The levels of ESR and CRP or other baseline variables were not associated with outcome. However, baseline serum ferritin was significantly higher in ASD patients with chronic disease (p = 0.04), while a cut-off of five times the normal upper level (NUL) was 100% sensitive and 60% specific for predicting chronic disease.

CONCLUSION

An exaggerated ferritin response with levels>5 times the NUL and high ferritin/CRP ratios is useful for distinguishing between ASD and RA patients. Ferritin levels>5 times the NUL are also associated with a chronic disease course.

Iron homeostasis in chronic inflammation

Inflammation induced anemia and resistance to erythropoietin are common features in patients with chronic kidney disease (CKD). Elevated levels of cytokines and enhanced oxidative stress, conditions associated with inflammatory states, are implicated in the development of anemia. Accumulating evidence suggests that activation of cytokine cascade and the associated acute-phase response, as it often occurs in patients with CKD, divert iron from erythropoiesis to storage sites within the reticuloendothelial system leading to functional iron deficiency and subsequently to anemia or resistance to erythropoietin. Other processes have also been shown to be involved in the pathogenesis of anemia provoked by the activated immune system including an inhibition of erythroid progenitor proliferation and differentiation, a suppression of erythropoietin production and a blunted response to erythropoietin. The present review concerns the underlying alterations in iron metabolism induced by chronic inflammation that result in anemia.

Infectious and inflammatory stimuli decrease endothelial nitric oxide synthase activity in vitro

BACKGROUND

Perturbation of iron metabolism, especially the increase of serum ferritin levels, is often associated with both inflammation and hypertension. Changes in iron availability can affect an important regulator of vascular tone, the endothelial nitric oxide synthase (eNOS), activated by a heme-dependent dimerization.

OBJECTIVE

To study the regulation of the anti-hypertensive eNOS in human endothelial cells, in correlation with iron metabolism alterations and stimuli triggering them in vivo, such as inflammation or infection.

DESIGN

Cells were treated with stimuli mimicking infection or inflammation [lipopolysaccharide (LPS) and/or tumor necrosis factor alpha (TNFalpha)]. and iron shortage (succinylacetone and desferrioxamine). The effect on eNOS expression and activation was evaluated, as well as ferritin content.

METHODS

eNOS protein expression was evaluated by separating the monomeric from the active dimeric form by low-temperature sodium dodecyl sulphate poly-acrylamide gel electrophoresis (SDS-PAGE), and mRNA was analyzed by semi-quantitative reverse transcriptase (RT)-polymerase chain reaction (PCR). As for LPS and TNFalpha, eNOS monomer decreased already after a 72-h treatment and further at 144 h, whereas the down-regulation of the dimer was slower, peaking at 144 h. Succinylacetone and desferrioxamine were effective only at 144 h. The mRNA levels were increasingly reduced after incubation, more markedly by LPS and TNFalpha together, whereas succinylacetone and desferrioxamine had no effect on transcription. We found that endothelial cells are not the source of increased ferritin production.

CONCLUSIONS

The results of this study suggest a down-regulating effect of infectious and inflammatory stimuli on eNOS expression, both at the mRNA level and protein expression or stability and dimerization, enhanced by heme and iron shortage, and indicate eNOS as a possible link between infection and hypertension.

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.