Carbon nanotubes' surface chemistry determines their potency as vaccine nanocarriers in vitro and in vivo

Carbon nanotubes (CNTs) have shown marked capabilities in enhancing antigen delivery to antigen presenting cells. However, proper understanding of how altering the physical properties of CNTs may influence antigen uptake by antigen presenting cells, such as dendritic cells (DCs), has not been established yet.Wehypothesized that altering the physical properties of multi-walled CNTs (MWNTs)-antigen conjugates, e.g. length and surface charge, can affect the internalization of MWNT-antigen by DCs, hence the induced immune response potency. For this purpose, pristineMWNTs (p-MWNTs) were exposed to various chemical reactions to modify their physical properties then conjugated to ovalbumin (OVA), a model antigen. The yieldedMWNTs-OVA conjugateswere longMWNT-OVA (~386 nm), bearing net positive charge (5.8mV), or shortMWNTs-OVA (~122 nm) of increasing negative charges (−23.4, −35.8 or −39 mV). Compared to the short MWNTs-OVA bearing high negative charges, short MWNT-OVA with the lowest negative charge demonstrated better cellular uptake and OVAspecific immune response both in vitro and in vivo. However, long positively-chargedMWNT-OVA showed limited cellular uptake and OVA specific immune response in contrast to shortMWNT-OVA displaying the least negative charge. We suggest that reduction in charge negativity of MWNT-antigen conjugate enhances cellular uptake and thus the elicited immune response intensity. Nevertheless, length of MWNT-antigen conjugate might also affect the cellular uptake and immune response potency; highlighting the importance of physical properties as a consideration in designing a MWNT-based vaccine delivery system

Copper(II) binding properties of hepcidin

Hepcidin is a peptide hormone that regulates the homeostasis of iron metabolism. The N-terminal domain of hepcidin is conserved amongst a range of species and is capable of binding Cu(II) and Ni(II) through the amino terminal copper–nickel binding motif (ATCUN). It has been suggested that the binding of copper to hepcidin may have biological relevance. In this study we have investigated the binding of Cu(II) with model peptides containing the ATCUN motif, fluorescently labelled hepcidin and hepcidin using MALDI-TOF mass spectrometry. As with albumin, it was found that tetrapeptide models of hepcidin possessed a higher affinity for Cu(II) than that of native hepcidin. The log K(1) value of hepcidin for Cu(II) was determined as 7.7. Cu(II) binds to albumin more tightly than hepcidin (log K(1) = 12) and in view of the serum concentration difference of albumin and hepcidin, the bulk of kinetically labile Cu(II) present in blood will be bound to albumin. It is estimated that the concentration of Cu(II)-hepcidin will be less than one femtomolar in normal serum and thus the binding of copper to hepcidin is unlikely to play a role in iron homeostasis. As with albumin, small tri and tetra peptides are poor models for the metal binding properties of hepcidin. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00775-016-1342-2) contains supplementary material, which is available to authorized users

Correlates of serum hepcidin levels and its association with cardiovascular disease in the elderly population

AbstractThe expression of the key iron regulatory hormone hepcidin is regulated by iron availability, inflammation, hormones, hypoxia, and anaemia. Increased serum concentrations of hepcidin have recently been linked to atherosclerosis. We studied demographic, haematologic, biochemical, and dietary correlates of serum hepcidin levels and its associations with incident cardiovascular disease and with carotid atherosclerosis.Serum hepcidin concentrations were measured by tandem mass spectrometry in samples taken in 2000 from 675 infection-free participants of the prospective population-based Bruneck study (age, mean±standard deviation, 66.0±10.2; 48.1% male). Blood parameters were measured by standard methods. Dietary intakes of iron and alcohol were surveyed with a food frequency questionnaire. Carotid atherosclerosis (365 cases) was assessed by ultrasound and subjects were observed for incident stroke, myocardial infarction, or sudden cardiac death (91 events) until 2010.Median (interquartile range) hepcidin levels were 2.27 nM (0.86, 4.15). Most hepcidin correlates were in line with hepcidin as an indicator of iron stores. Independently of ferritin, hepcidin was related directly to physical activity (p=0.024) and fibrinogen (p&lt;0.0001), and inversely to alcohol intake (p=0.006), haemoglobin (p=0.027), and γ-glutamyltransferase (p&lt;0.0001). Hepcidin and hepcidin-to-ferritin ratio were not associated with prevalent carotid atherosclerosis (p=0.43 and p=0.79) or with incident cardiovascular disease (p=0.62 and p=0.33).In this random sample of the general community, fibrinogen and γ-glutamyltransferase were the most significant hepcidin correlates independent of iron stores, and hepcidin was related to neither atherosclerosis nor cardiovascular disease.</jats:p

Cross-Reactivity between the Rheumatoid Arthritis-Associated Motif EQKRAA and Structurally Related Sequences Found in Proteus mirabilis

Cross-reactivity or molecular mimicry may be one of the underlying mechanisms involved in the etiopathogenesis of rheumatoid arthritis (RA). Antiserum against the RA susceptibility sequence EQKRAA was shown to bind to a similar peptide ESRRAL present in the hemolysin of the gram-negative bacterium Proteus mirabilis, and an anti-ESRRAL serum reacted with EQKRAA. There was no reactivity with either anti-EQKRAA or anti-ESRRAL to a peptide containing the EDERAA sequence which is present in HLA-DRB1∗0402, an allele not associated with RA. Furthermore, the EQKRAA and ESRRAL antisera bound to a mouse fibroblast transfectant cell line (Dap.3) expressing HLA-DRB1∗0401 but not to DRB1∗0402. However, peptide sequences structurally related to the RA susceptibility motif LEIEKDFTTYGEE (P. mirabilis urease), VEIRAEGNRFTY (collagen type II) and DELSPETSPYVKE (collagen type XI) did not bind significantly to cell lines expressing HLA-DRB1∗0401 or HLA-DRB1∗0402 compared to the control peptide YASGASGASGAS. It is suggested here that molecular mimicry between HLA alleles associated with RA and P. mirabilis may be relevant in the etiopathogenesis of the disease

Serum Hemojuvelin and Hepcidin Levels in Chronic Kidney Disease

&lt;i&gt;Background:&lt;/i&gt; Hemojuvelin (HJV) has recently emerged as one of a number of significant regulators of iron homeostasis and hepcidin expression. Recently, an immunoassay has been developed to measure circulating levels of soluble HJV (sHJV). The aim of this study was to measure serum hepcidin and sHJV levels in a chronic kidney disease (CKD) population. &lt;i&gt;Methods:&lt;/i&gt; A total of 93 patients participated in the study (31 hemodialysis, 31 non-dialysis, 31 transplant recipients), and were matched for age and gender. Serum samples were taken for measurement of hepcidin-25 and sHJV, along with standard hematological, biochemical and inflammatory markers, and univariate/multivariate analyses were performed. &lt;i&gt;Results:&lt;/i&gt; Serum sHJV levels were markedly elevated in the hemodialysis patients (2,619 ± 1,445 ng/ml) compared to the CKD (590 ± 344 ng/ml) and transplant recipients (870 ± 638 ng/ml) (p &lt; 0.001), normal range 370–890 ng/ml. There was a strong correlation between serum ferritin and sHJV, which remained after adjustment for potential confounders (beta 0.92, p &lt; 0.001). In the univariate analysis, sHJV levels correlated with serum hepcidin but this was not evident in the multivariate analysis. No associations were seen between sHJV and markers of inflammation or eGFR. &lt;i&gt;Conclusions:&lt;/i&gt; sHJV is elevated in hemodialysis patients compared to non-dialysis CKD patients. There was no association between sHJV and eGFR (in the non-dialysis groups), suggesting that factors other than decreased renal clearance are responsible for the high sHJV levels. The strong association between sHJV and ferritin suggests an interdependent relationship, although further studies are required to elucidate the possible mechanism(s) for this.</jats:p

Hepcidin Response to Iron Therapy in Patients with Non-Dialysis Dependent CKD: An analysis of the FIND-CKD Trial

Hepcidin is the key regulator of iron homeostasis but data are limited regarding its temporal response to iron therapy, and response to intravenous versus oral iron. In the 56-week, open-label, multicenter, prospective, randomized FIND-CKD study, 626 anemic patients with non-dialysis dependent chronic kidney disease (ND-CKD) and iron deficiency not receiving an erythropoiesis stimulating agent were randomized (1:1:2) to intravenous ferric carboxymaltose (FCM), targeting higher (400-600μg/L) or lower (100-200μg/L) ferritin, or to oral iron. Serum hepcidin levels were measured centrally in a subset of 61 patients. Mean (SD) baseline hepcidin level was 4.0(3.5), 7.3(6.4) and 6.5(5.6) ng/mL in the high ferritin FCM (n = 17), low ferritin FCM (n = 16) and oral iron group (n = 28). The mean (SD) endpoint value (i.e. the last post-baseline value) was 26.0(9.1),15.7(7.7) and 16.3(11.0) ng/mL, respectively. The increase in hepcidin from baseline was significantly smaller with low ferritin FCM or oral iron vs high ferritin FCM at all time points up to week 52. Significant correlations were found between absolute hepcidin and ferritin values (r = 0.65, p<0.001) and between final post-baseline increases in both parameters (r = 0.70, p<0.001). The increase in hepcidin levels over the 12-month study generally mirrored the cumulative iron dose in each group. Hepcidin and transferrin saturation (TSAT) absolute values showed no correlation, although there was an association between final post-baseline increases (r = 0.42, p<0.001). Absolute values (r = 0.36, p = 0.004) and final post-baseline increases of hepcidin and hemoglobin (p = 0.30, p = 0.030) correlated weakly. Baseline hepcidin levels were not predictive of a hematopoietic response to iron therapy. In conclusion, hepcidin levels rose in response to either intravenous or oral iron therapy, but the speed and extent of the rise was greatest with intravenous iron targeting a higher ferritin level. However neither the baseline level nor the change in hepcidin was able to predict response to therapy in this cohort