Identification of Closed Linear Epitopes in S1-RBD and S2-HR1/2 of SARS-CoV-2 Spike Protein Able to Induce Neutralizing Abs

SARS-CoV-2 has evolved as several variants. Immunization to boost the Ab response to Spike antigens is effective, but similar vaccines could not enhance Ab efficacy enough. Effective Ab responses against the human ACE2 (hACE2)-mediated infection of the emerging SARS-CoV-2 variants are needed. We identified closed linear epitopes of the SARS-CoV-2 Spike molecule that induced neutralizing Abs (nAbs) against both S1-RBD, responsible for attachment to hACE2, and S2-HR1/2, in convalescents and vaccine recipients. They inhibited a pseudo-virus infection mediated by the hACE2 pathway. The epitope sequences included epitopes #7 (aa411-432), #11 (aa459-480) and #111 (aa1144-1161), in S1-RBD and S2-HR2. Epitope #111 was conserved in Wuhan and variant strains, whereas #7 and #11 were conserved in Wuhan carried mutations K417N and S477N/T478K in Omicron BA.4/5. These mutations were recognized by the original epitope-specific Abs. These epitopes in RBD and HR2 neither contained, nor overlapped with, those responsible for the antibody-dependent enhancement of the SARS-CoV-2 infection. The sublingual administration of multiple epitope-conjugated antigens increased the IgG and IgA Abs specific to the neutralizing epitopes in mice pre-immunized subcutaneously. The findings indicated that S1-RBD and S2-HR2 epitopes were responsible for pseudo-virus SARS-CoV-2 infections and that sublingual boosts with multiple epitope-conjugated antigens could enhance the protection by nAbs of IgG and IgA against infection by a wide range of variants.

Anemia of chronic diseases: current state of the problem and perspectives

Anemia of chronic diseases is a condition, that accompanies several chronic conditions, that have inflammation as an underlying cause. The article covers current concepts of pathogenesis, evaluation and treatment of this type of anemia. The new perspectives in the development of investigational methods and treatment are discussed. The new methods of iron deficiency assessment in patients with systemic inflammation are discussed separately.

Iron disorders and hepcidin

Iron is an essential element due to its role in a wide variety of physiological processes. Iron homeostasis is crucial to prevent iron overload disorders as well as iron deficiency anemia. The liver synthesized peptide hormone hepcidin is a master regulator of systemic iron metabolism. Given its role in overall health, measurement of hepcidin can be used as a predictive marker in disease states. In addition, hepcidin-targeting drugs appear beneficial as therapeutic agents. This review emphasizes recent development on analytical techniques (immunochemical, mass spectrometry and biosensors) and therapeutic approaches (hepcidin agonists, stimulators and antagonists). These insights highlight hepcidin as a potential biomarker as well as an aid in the development of new drugs for iron disorders.

JTZ-951 (enarodustat), a hypoxia-inducible factor prolyl hydroxylase inhibitor, improves iron utilization and anemia of inflammation: Comparative study against recombinant erythropoietin in rat

Anemia with inflammation-induced defective iron utilization is a pathological condition observed in patients suffering from chronic kidney disease (CKD) or chronic inflammatory disease. There is no reasonable treatment for these conditions, because the effects of erythropoiesis stimulating agents (ESAs) or iron supplementation in the treatment of anemia are insufficient. JTZ-951 (enarodustat) has been characterized as a novel, orally bioavailable inhibitor of hypoxia-inducible factor prolyl hydroxylase (HIF-PH), and has been developed as a novel therapeutic agent for anemia with CKD. In this study, the effects of JTZ-951 on iron utilization during erythropoiesis and on anemia of inflammation were compared with those of recombinant human erythropoietin (rHuEPO) using normal rat and rat model of anemia of inflammation. In normal rats, under conditions in which JTZ-951 and rHuEPO showed similar erythropoietic effect, repeated doses of JTZ-951 induced erythropoiesis while retaining the hemoglobin content in red blood cells, while administration of rHuEPO resulted in decrease in some erythrocyte-related parameters. As for iron-related parameters during erythropoiesis, JTZ-951 exhibited more efficient iron utilization compared to rHuEPO. A single dose of JTZ-951 resulted in decrease in hepcidin expression observed within 24 h after administration, but a single dose of rHuEPO did not. In a rat model of anemia of inflammation (also known as a model with functional iron-deficiency), JTZ-951 showed erythropoietic effect, in contrast with rHuEPO. These results suggest that, unlike rHuEPO, JTZ-951 stimulates erythropoiesis by increasing iron utilization, and improves anemia of inflammation.