Dual role of erythrocyte complement receptor type 1 in immune complex-mediated macrophage stimulation: implications for the pathogenesis of Plasmodium falciparum malaria

Human complement receptor type 1 (CR1) protein levels and genetic variants in chronic Chagas Disease

Complement is an essential element in both innate and acquired immunity contributing to the immunopathogenesis of many disorders, including Chagas Disease (CD). Human complement receptor 1 (CR1) plays a role in the clearance of complement opsonized molecules and may facilitate the entry of pathogens into host cells. Distinct CR1 exon 29 variants have been found associated with CR1 expression levels, increased susceptibility and pathophysiology of several diseases. In this study, CR1 plasma levels were assessed by ELISA and CR1 variants in exon 29 by sequencing in a Brazilian cohort of 232 chronic CD patients and 104 healthy controls. CR1 levels were significantly decreased in CD patients compared to controls (p < 0.0001). The CR1 rs1704660G, rs17047661G and rs6691117G variants were significantly associated with CD and in high linkage disequilibrium. The CR1*AGAGTG haplotype was associated with T. cruzi infection (p = 0.035, OR 3.99, CI 1.1-14.15) whereas CR1*AGGGTG was related to the risk of chagasic cardiomyopathy (p = 0.028, OR 12.15, CI 1.13-113). This is the first study that provides insights on the role of CR1 in development and clinical presentation of chronic CD.

Elevated lead levels and changes in blood morphology and erythrocyte CR1 in preschool children from an e-waste area

Improper dismantling and combustion of electronic waste (e-waste) may release persistent organic pollutants and heavy metals that possess potential risk for human health. Lead (Pb) is carried through the circulatory system by erythrocytes and is known to alter the functions of hematopoietic and immune systems. The aim of the study was to investigate the effect of Pb exposure on blood morphology and erythrocyte complement receptor 1 (CR1) levels as related to immunologic function in preschool children. We recruited 484 preschool children, 2- to 6-years of age, among whom 332 children were from Guiyu, a typical and primitive e-waste processing area, and 152 children from Haojiang (reference area). Results showed that the blood Pb level (BPb) and erythrocyte Pb level (EPb) of exposed children were significantly higher, but, the mean corpuscular hemoglobin concentration (MCHC) and erythrocyte CR1 levels were significantly lower than reference children. Elevated EPb and BPb was related to disadvantageous changes in hematocrit (HCT), mean corpuscular volume (MCV), hemoglobin (HGB), mean corpuscular hemoglobin (MCH), and MCHC, respectively, in children from the e-waste recycling area. Furthermore, in the high Pb-exposed group, the Pb toxicity of erythrocytes was more significant compared to the low Pb-exposed group in e-waste-exposed children. Combine with the BPb and EPb would be better to evaluating the Pb toxicity of erythrocytes. Compared to low Pb exposure, high BPb and EPb were associated with lower erythrocyte CR1 expression in all children. Our data suggests that elevated Pb levels result in adverse changes in blood morphology, hemoglobin synthesis and CR1 expression, which might be a non-negligible threat to erythrocyte immunity development in local preschool children. It is therefore imperative for any intervention to control the Pb exposure of children and actively educate adults to raise their environmental awareness of potential e-waste pollution during the recycling process.

Erythrocytes as Carriers for Drug Delivery in Blood Transfusion and Beyond

Red blood cells (RBCs) are innate carriers that can also be engineered to improve the pharmacokinetics and pharmacodynamics of many drugs, particularly biotherapeutics. Successful loading of drugs, both internally and on the external surface of RBCs, has been demonstrated for many drugs including anti-inflammatory, antimicrobial, and antithrombotic agents. Methods for internal loading of drugs within RBCs are now entering clinical use. Although internal loading can result in membrane disruption that may compromise biocompatibility, surface loading using either affinity or chemical ligands offers a diverse set of approaches for the production of RBC drug carriers. A wide range of surface determinants is potentially available for this approach, although there remains a need to characterize the effects of coupling agents to these surface proteins. Somewhat surprisingly, recent data also suggest that red cell-mediated delivery may confer tolerogenic immune effects. Questions remaining before widespread application of these technologies include determining the optimal loading protocol, source of RBCs, and production logistics, as well as addressing regulatory hurdles. Red blood cell drug carriers, after many decades of progress, are now poised to enter the clinic and broaden the potential application of RBCs in blood transfusion.