title: Development of pro-inflammatory phenotype in monocytes after engulfing Hb-activated platelets in hemolytic disorders.
abstract: Monocytes and macrophage combat infections and maintain homeostatic balance by engulfing microbes and apoptotic cells, and releasing inflammatory cytokines. Studies have described that these cells develop anti-inflammatory properties upon recycling the free-hemoglobin (Hb) in hemolytic conditions. While investigating the phenotype of monocytes in two hemolytic disorders-paroxysmal nocturnal hemoglobinuria (PNH) and sickle cell disease (SCD), we observed a high number of pro-inflammatory (CD14+CD16hi) monocytes in these patients. We further investigated in vitro the phenotype of these monocytes and found an estimated 55% of CD14+cells were transformed into the CD14+CD16hisubset after engulfing Hb-activated platelets. The CD14+CD16himonocytes, which were positive for both intracellular Hb and CD42b (platelet marker), secreted significant amounts of TNF-α and IL-1β, unlike monocytes treated with only free Hb, which secreted more IL-10. We have shown recently the presence of a high number of Hb-bound hyperactive platelets in patients with both diseases, and further investigated if the monocytes engulfed these activated platelets in vivo. As expected, we found 95% of CD14+CD16himonocytes with both intracellular Hb and CD42b in both diseases, and they expressed high TNF-α. Furthermore our data showed that these monocytes whether from patients or developed in vitro after treatment with Hb-activated platelets, secreted significant amounts of tissue factor. Besides, these CD14+CD16himonocytes displayed significantly decreased phagocytosis of E. coli. Our study therefore suggests that this alteration of monocyte phenotype may play a role in the increased propensity to pro-inflammatory/coagulant complications observed in these hemolytic disorders-PNH and SCD.
authors.affiliation: Regional Centre for Biotechnology, National Capital Region Biotech Science Cluster, Faridabad, India; Department of Biotechnology, Manipal University, Karnataka, India.
authors.forename: Rashi
authors.initials: R
authors.lastname: Singhal
authors.affiliation: Regional Centre for Biotechnology, National Capital Region Biotech Science Cluster, Faridabad, India.
authors.forename: Sheetal
authors.initials: S
authors.lastname: Chawla
authors.affiliation: Translational Health Science & Technology Institute, National Capital Region Biotech Science Cluster, Faridabad, India.
authors.forename: Deepak K
authors.initials: DK
authors.lastname: Rathore
authors.affiliation: Regional Centre for Biotechnology, National Capital Region Biotech Science Cluster, Faridabad, India; Department of Biotechnology, Manipal University, Karnataka, India.
authors.forename: Angika
authors.initials: A
authors.lastname: Bhasym
authors.affiliation: Regional Centre for Biotechnology, National Capital Region Biotech Science Cluster, Faridabad, India; Department of Biotechnology, Manipal University, Karnataka, India.
authors.forename: Gowtham K
authors.initials: GK
authors.lastname: Annarapu
authors.affiliation: Department of Hematology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Vandana
authors.initials: V
authors.lastname: Sharma
authors.affiliation: Department of Hematology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Tulika
authors.initials: T
authors.lastname: Seth
authors.affiliation: Regional Centre for Biotechnology, National Capital Region Biotech Science Cluster, Faridabad, India. Electronic address: prasenjit@rcb.res.in.
authors.forename: Prasenjit
authors.initials: P
authors.lastname: Guchhait
mesh_terms: D000755:Anemia, Sickle Cell / Q000378:metabolism / Q000473:pathology*; D001792:Blood Platelets / Q000378:metabolism / Q000473:pathology*; D006454:Hemoglobins / Q000378:metabolism*; D006457:Hemoglobinuria, Paroxysmal / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007249:Inflammation / Q000378:metabolism / Q000473:pathology*; D016753:Interleukin-10 / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D009000:Monocytes / Q000378:metabolism / Q000473:pathology*; D010641:Phenotype; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000378:metabolism; D017452:Receptors, IgG / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D006454:Hemoglobins; D053583:Interleukin-1beta; D018950:Lipopolysaccharide Receptors; D019038:Platelet Glycoprotein GPIb-IX Complex; D017452:Receptors, IgG; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10
keywords: Coagulation and hemolytic disorders; Hemoglobin; Inflammation; Monocytes; Platelets