The functional significance of the Duffy negative polymorphism

I investigated the impact of DARC expression on haematopoiesis using DARC-deficient (DD) mice and developed humanised transgenic DARC models expressing the $FYB(ES)$ and $FYB$ human genes. I developed murine irradiation chimeras with differential DARC expression and showed that the absence of erythroid DARC but continued DARC endothelial expression was associated with reduced peripheral blood neutrophil counts. FYB(ES)TG mice showed reduced peripheral neutrophil counts and expansion of BM myelopoiesis, and reduced lymphopoiesis and erythropoiesis, compared to FYBTG mice. FYB(ES)TG and DD mice had reduced GMP cells and LSK cells, and proliferation and apoptosis of these cells were reduced. Microarray analysis of differentially expressed genes showed increased myeloid gene expression in GMP and LSK cells. Mixed irradiation chimeras showed that DD BM retained these changes, suggesting an intrinsic cell effect. Analysis of BM and serum showed a significant increase in G-CSF and eotaxin. Morphological analysis of myeloid cells in femur sections revealed increased myeloid cell clustering in DD and FYB(ES)TG mice. These data suggest that neutrophils are preferentially retained in the DD BM, possibly as a result of loss of optimal chemokine gradients created by erythroblast DARC which may favour neutrophil egress and thereby leading to peripheral neutropenia

Duffy antigen receptor for chemokines and its involvement in patterning and control of inflammatory chemokines

Leukocyte functions are linked to their migratory responses, which, in turn, are largely determined by the expression profile of classical chemokine receptors. Upon binding their cognate chemokines, these G-protein-coupled receptors (GPCRs) initiate signaling cascades and downstream molecular and cellular responses, including integrin activation and cell locomotion. Chemokines also bind to an alternative subset of chemokine receptors, which have serpentine structure characteristic for GPCRs but lack DRYLAIV consensus motive required for coupling to G-proteins. Duffy antigen receptor for chemokines (DARC) is a member of this atypical receptor subfamily. DARC binds a broad range of inflammatory CXC and CC chemokines and is expressed by erythrocytes, venular endothelial cells, and cerebellar neurons. Erythrocyte DARC serves as blood reservoir of cognate chemokines but also as a chemokine sink, buffering potential surges in plasma chemokine levels. Endothelial cell DARC internalizes chemokines on the basolateral cell surface resulting in subsequent transcytosis of chemokines and their immobilization on the tips of apical microvilli. These DARC-mediated endothelial cell interactions allow chemokines produced in the extravascular tissues to optimally function as arrest chemokines on the luminal endothelial cell surface

Atypical chemokine receptor 1 on nucleated erythroid cells regulates hematopoiesis

Healthy individuals of African ancestry have neutropenia that has been linked with the variant rs2814778(G) of the gene encoding atypical chemokine receptor 1 (ACKR1). This polymorphism selectively abolishes the expression of ACKR1 in erythroid cells, causing a Duffy-negative phenotype. Here we describe an unexpected fundamental role for ACKR1 in hematopoiesis and provide the mechanism that links its absence with neutropenia. Nucleated erythroid cells had high expression of ACKR1, which facilitated their direct contact with hematopoietic stem cells. The absence of erythroid ACKR1 altered mouse hematopoiesis including stem and progenitor cells, which ultimately gave rise to phenotypically distinct neutrophils that readily left the circulation, causing neutropenia. Individuals with a Duffy-negative phenotype developed a distinct profile of neutrophil effector molecules that closely reflected the one observed in the ACKR1-deficient mice. Thus, alternative physiological patterns of hematopoiesis and bone marrow cell outputs depend on the expression of ACKR1 in the erythroid lineage, findings with major implications for the selection advantages that have resulted in the paramount fixation of the ACKR1 rs2814778(G) polymorphism in Africa

Diseño de una planta de procesamiento de productos lácteos y elaboración de un plan de contingencia contra deslaves en el Instituto Tecnológico Universitario Guatemala Sur-USAC. Palón, Escuintla.

La presente investigación se realizó en el Instituto Tecnológico Universitario Guatemala Sur, es una dependencia de la Universidad de San Carlos de Guatemala, descentralizada con patrimonio propio, encargado de desarrollar la formación teórica y práctica y la educación profesional en las áreas tecnológicas. Está ubicado en el municipio de Palín, departamento de Escuintla. En el Instituto Tecnológico Universitario Guatemala Sur (ITUGS), se imparten 5 carreras técnicas, dentro de las cuales está la carrera de Técnico en Producción Alimentaria donde se imparte el curso de procesamiento de productos lácteos. La carrera de Técnico necesita el aprendizaje práctico y técnico de la elaboración de alimentos y actualmente el ITUGS no cuenta con las instalaciones adecuadas para desarrollar las prácticas de dicha carrera, por lo que se propone el diseño de una planta de procesamiento de productos lácteos, en donde los alumnos puedan realizar las prácticas de los conocimientos aprendidos en la teoría

Differential DARC/ACKR1 expression distinguishes venular from non-venular endothelial cells in murine tissues

This work was supported by the National Institutes of Health (NIH) grant AI112521 and the John and Virginia Kaneb Fellowship

Distinct Compartmentalization of the Chemokines CXCL1 and CXCL2 and the Atypical Receptor ACKR1 Determine Discrete Stages of Neutrophil Diapedesis.

Neutrophils require directional cues to navigate through the complex structure of venular walls and into inflamed tissues. Here we applied confocal intravital microscopy to analyze neutrophil emigration in cytokine-stimulated mouse cremaster muscles. We identified differential and non-redundant roles for the chemokines CXCL1 and CXCL2, governed by their distinct cellular sources. CXCL1 was produced mainly by TNF-stimulated endothelial cells (ECs) and pericytes and supported luminal and sub-EC neutrophil crawling. Conversely, neutrophils were the main producers of CXCL2, and this chemokine was critical for correct breaching of endothelial junctions. This pro-migratory activity of CXCL2 depended on the atypical chemokine receptor 1 (ACKR1), which is enriched within endothelial junctions. Transmigrating neutrophils promoted a self-guided migration response through EC junctions, creating a junctional chemokine "depot" in the form of ACKR1-presented CXCL2 that enabled efficient unidirectional luminal-to-abluminal migration. Thus, CXCL1 and CXCL2 act in a sequential manner to guide neutrophils through venular walls as governed by their distinct cellular sources.This work was supported by funds from the British Heart Foundation (FS/14/3/30518 to T.G. and S.N.), the People Programme (Marie Curie Actions) of the EU’s 7th Framework Programme (FP7/2007-2013) under REA grant agreement 608765 (to T.G. and S.N.), and by the Wellcome Trust (098291/Z/12/Z to S.N.). D.S. is supported by the CNIC, SAF2016-79040-R from the Spanish Ministerio de Ciencia, and ERC-2016-CoG 725091 from the European Research Council. M.T. and A.R. are supported by the Sinergia grant CRSII3_160719 of the Swiss National Science Foundation. G.G. is supported by the Wellcome Trust and the MRC. U.H.v.A. and A.T. are supported by the Ragon Institute of MGH, MIT and Harvard and the HMS Center for Immune Imaging

Population-based real-world registry study to evaluate clinical outcomes of chronic graft-versus-host disease

Introduction Chronic graft-versus-host disease (cGVHD) is a serious immune-mediated complication after allogeneic haematopoietic stem cell transplantation (HSCT), but in patients with malignancy, cGVHD development is associated with superior survival. Lack of reliable biomarkers and clinical underreporting means there is insufficient understanding of cGVHD clinical outcomes and balance between cGVHD treatment and maintaining beneficial graft-versus-tumour effects. Methods We performed a Swedish population-wide registry study following patients who underwent allogeneic HSCT 2006–2015. cGVHD status was retrospectively classified using a real-world method based on the timing and extent of systemic immunosuppressive treatment. Results cGVHD incidence among patients surviving ≥6 months post-HSCT (n = 1246) was 71.9%, significantly higher than previously reported. 5-year overall survival in patients surviving ≥6 months post-HSCT was 67.7%, 63.3%, and 65.3%, in non-, mild, and moderate-severe cGVHD, respectively. Non-cGVHD patients had a mortality risk almost five-fold higher compared to moderate-severe cGVHD patients 12-months post-HSCT. Moderate-severe cGVHD patients had greater healthcare utilization compared with mild and non cGVHD patients. Conclusion cGVHD incidence was high among HSCT survivors. Non-cGVHD patients had higher mortality during the first 6 months of follow-up; however, moderate-severe cGVHD patients had more comorbidities and healthcare utilization. This study highlights the urgent need for new treatments and real-time methods to monitor effective immunosuppression after HSCT

Population-based real-world registry study to evaluate clinical outcomes of chronic graft-versus-host disease.

IntroductionChronic graft-versus-host disease (cGVHD) is a serious immune-mediated complication after allogeneic haematopoietic stem cell transplantation (HSCT), but in patients with malignancy, cGVHD development is associated with superior survival. Lack of reliable biomarkers and clinical underreporting means there is insufficient understanding of cGVHD clinical outcomes and balance between cGVHD treatment and maintaining beneficial graft-versus-tumour effects.MethodsWe performed a Swedish population-wide registry study following patients who underwent allogeneic HSCT 2006-2015. cGVHD status was retrospectively classified using a real-world method based on the timing and extent of systemic immunosuppressive treatment.ResultscGVHD incidence among patients surviving ≥6 months post-HSCT (n = 1246) was 71.9%, significantly higher than previously reported. 5-year overall survival in patients surviving ≥6 months post-HSCT was 67.7%, 63.3%, and 65.3%, in non-, mild, and moderate-severe cGVHD, respectively. Non-cGVHD patients had a mortality risk almost five-fold higher compared to moderate-severe cGVHD patients 12-months post-HSCT. Moderate-severe cGVHD patients had greater healthcare utilization compared with mild and non cGVHD patients.ConclusioncGVHD incidence was high among HSCT survivors. Non-cGVHD patients had higher mortality during the first 6 months of follow-up; however, moderate-severe cGVHD patients had more comorbidities and healthcare utilization. This study highlights the urgent need for new treatments and real-time methods to monitor effective immunosuppression after HSCT