Erythropoietin for oncology supportive care

Recombinant human erythropoietin (rhEPO), the prototype erythropoiesis-stimulating agent developed in the 1980s, was among the first recombinant human proteins to be marketed for clinical use in the oncology setting. Anemia is a frequent concern in patients with cancer receiving myelosuppressive chemotherapy and the availability of rhEPO as an alternative to red blood cell transfusions to treat symptomatic anemia created excitement among clinicians, particularly during an era of mounting concern for transfusion-transmissible infections. Early studies of rhEPO for chemotherapy-induced anemia in patients with non-myeloid malignancies showed these agents improved hemoglobin levels and reduced transfusion rates. rhEPO therapy was reported to decrease fatigue and improve quality of life, although the magnitude and clinical meaningfulness of these effects have been debated. More recent clinical trials since 2003 linking rhEPO therapy to increased risk of tumor progression, thrombo-vascular events and mortality prompted implementation of use restrictions to minimize potential for harm. Scientific research to understand the basic mechanisms of the biologic effects of erythropoietin at the cellular receptor and signaling level has revealed pleiotropic cytokine effects extending beyond erythropoiesis regulation. The importance of erythropoietin receptor signaling in normal, non-erythroid tissues and in pre-clinical tumor models has been under intense investigation and scrutiny, as potential mechanisms of the adverse outcomes associated with rhEPO therapy have been debated. Further research will be required to clarify the complex interplay between the diverse hematopoietic and non-hematopoietic effects of erythropoietin in normal and malignant tissues and to optimize the clinical use of rhEPO in the supportive care of cancer patients.     

Blood and bones: Osteoblastic HIF signaling regulates erythropoiesis

Comment on: Rankin EB, et al. Cell 2012; 149:63-74.     

FANCD2 is a target for caspase 3 during DNA damage-induced apoptosis

The Fanconi anemia (FA) pathway, of which the FANCD2 protein is a key component, plays crucial roles in the maintenance of hematopoietic stem cells and suppression of carcinogenesis. However, the function of FANCD2 remains unclear. Here, we report that FANCD2 is a novel and specific substrate of caspase 3. Cleavage of FANCD2 by caspase 3 did not require either the FA core complex or mono-ubiquitylation of FANCD2, and was stimulated by p53. In addition, we identified the cleavage sites and generated cell lines that stably express a caspase-resistant FANCD2 mutant. Our data suggest that FANCD2 is regulated by caspase-mediated degradation during apoptosis induced by DNA damage.     

Structural flexibility and the positive charges are the key factors in bacterial cell selectivity and membrane penetration of peptoid-substituted analog of Piscidin 1

Piscidin 1 (Pis-1) is a novel cytotoxic peptide with a cationic α-helical structure isolated from the mast cells of hybrid striped bass. In our previous study, we showed that Pis-1[PG] with a substitution of Pro⁸ for Gly⁸ in Pis-1 had higher bacterial cell selectivity than Pis-1. We designed peptoid residue-substituted peptide, Pis-1[NkG], in which Gly⁸ of Pis-1 was replaced with Nlys (Lys peptoid residue). Pis-1[NkG] had higher antibacterial activity and lower cytotoxicity against mammalian cells than Pis-1 and Pis-1[PG]. We determined the tertiary structure of Pis-1[PG] and Pis-1[NkG] in the presence of DPC micelles by NMR spectroscopy. Both peptides had a three-turn helix in the C-terminal region and a bent structure in the center. Pis-1[PG] has a rigid bent structure at Pro⁸ whereas Pis-1[NkG] existed as a dynamic equilibrium of two conformers with a flexible hinge structure at Nlys⁸. Depolarization of the membrane potential of Staphylococcus aureus and confocal laser-scanning microscopy study revealed that Pis-1[NkG] effectively penetrated the bacterial cell membrane and accumulated in the cytoplasm, whereas Pis-1[PG] did not penetrate the membrane but remained outside or on the cell surface. Introduction of a lysine peptoid at position 8 of Pis-1 provided conformational flexibility and increased the positive charge at the hinge region; both factors facilitated penetration of the bacterial cell membrane and conferred bacterial cell selectivity on Pis-1[NkG].     

Life and death in a civitas capital: Metabolic disease and trauma in the children from late Roman Dorchester,Dorset

The impact that “Romanization” and the development of urban centers had on the health of the Romano‐British population is little understood. A re‐examination of the skeletal remains of 364 nonadults from the civitas capital at Roman Dorchester (Durnovaria) in Dorset was carried out to measure the health of the children living in this small urban area. The cemetery population was divided into two groups; the first buried their dead organized within an east–west alignment with possible Christian‐style graves, and the second with more varied “pagan” graves, aligned north–south. A higher prevalence of malnutrition and trauma was evident in the children from Dorchester than in any other published Romano‐British group, with levels similar to those seen in postmedieval industrial communities. Cribra orbitalia was present in 38.5% of the children, with rickets and/or scurvy at 11.2%. Twelve children displayed fractures of the ribs, with 50% of cases associated with rickets and/or scurvy, suggesting that rib fractures should be considered during the diagnosis of these conditions. The high prevalence of anemia, rickets, and scurvy in the Poundbury children, and especially the infants, indicates that this community may have adopted child‐rearing practices that involved fasting the newborn, a poor quality weaning diet, and swaddling, leading to general malnutrition and inadequate exposure to sunlight. The Pagan group showed no evidence of scurvy or rib fractures, indicating difference in religious and child‐rearing practices but that both burial groups were equally susceptible to rickets and anemia suggests a shared poor standard of living in this urban environment. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

Activity optimization of an undecapeptide analogue derived from a frog-skin antimicrobial peptide

While natural antimicrobial peptides are potential therapeutic agents, their physicochemical properties and bioactivity generally need to be enhanced for clinical and commercial development. We have previously developed a cationic, amphipathic α-helical, 11-residue peptide (named herein GA-W2: FLGWLFKWASK-NH₂) with potent antimicrobial and hemolytic activity, which was derived from a 24-residue, natural antimicrobial peptide isolated from frog skin. Here, we attempted to optimize peptide bioactivity by a rational approach to sequence modification. Seven analogues were generated from GA-W2, and their activities were compared with that of a 12-residue peptide, omiganan, which is being developed for clinical and commercial applications. Most of the modifications reported here improved antimicrobial activity. Among them, the GA-K4AL (FAKWAFKWLKK-NH₂) peptide displayed the most potent antimicrobial activity with negligible hemolytic activity, superior to that of omiganan. The therapeutic index of GA-K4AL was improved more than 53- and more than 31-fold against Gram-negative and Gram-positive bacteria, respectively, compared to that of the starting peptide, GA-W2. Given its relatively shorter length and simpler amino acid composition, our sequence-optimized GA-K4AL peptide may thus be a potentially useful antimicrobial peptide agent.     

Increased concentrations of IL-18 and uric acid in sickle cell anemia: contribution of hemolysis, endothelial activation and the inflammasome

Sickle cell anemia (SCA) is a common, severe monogenetic disorder characterized by chronic hemolysis, frequent infections, a chronic inflammatory state and recurrent occlusions of the microcirculation, resulting in painful crises, organ damage and premature death. This study evaluated associations between serum levels of IL-18, uric acid, hemolytic markers, and inflammatory molecules in SCA patients. A cross-sectional study was performed including 45 SCA patients (median age of 20.5 years) without general symptoms and who had not undergone blood transfusions. Inclusion criteria for the steady-state SCA patients were the absence of hospitalization and the absence of infections. Interleukin-18 and uric acid levels were correlated closely with markers of hemolysis, endothelial dysfunction and others cytokines levels. These findings suggest probable influences of IL-18 and uric acid in the pathophysiology of vascular occlusion in SCA. Additional studies should be performed to characterize similar prognosis markers and possible therapeutic targets.     

Influence of N-acylation of a peptide derived from human lactoferricin on membrane selectivity

Increasing numbers of bacterial strains being resistant to conventional antibiotics emphasize the urgent need for new antimicrobial agents. One strategy is based on host defence peptides that can be found in every organism including humans. We have studied the antimicrobial peptide LF11, derived from the pepsin cleavage product of human lactoferrin, known for its antimicrobial and lipid A-binding activity, and peptide C12LF11, the N-lauryl-derivative of LF11, which has owing to the attached hydrocarbon chain an additional hydrophobic segment. The influence of this hydrocarbon chain on membrane selectivity was studied using model membranes composed of dipalmitoylphosphatidylglycerol (DPPG), mimicking bacterial plasma membranes, and of dipalmitoylphosphatidylcholine (DPPC), a model system for mammalian membranes. A variety of biophysical techniques was applied. Thereby, we found that LF11 did not affect DPPC bilayers and showed only moderate effects on DPPG membranes in accordance with its non-hemolytic and weak antimicrobial activity. In contrast, the introduction of the N-lauryl group caused significant changes in the phase behaviour and lipid chain packing in both model membrane systems. These findings correlate with the in vitro tests on methicillin resistant S. aureus, E. coli, P. aeruginosa and human red blood cells, showing increased biological activity of C12LF11 towards these test organisms. This provides evidence that both electrostatic and hydrophobic interactions are crucial for biological activity of antimicrobial peptides, whereas a certain balance between the two components has to be kept, in order not to loose the specificity for bacterial membranes.