Browsing by Author "Ghiran, Ionita C."
Now showing 1 - 3 of 3
- Results Per Page
- Sort Options
Item C4d Deposits on the Surface of Red Blood Cells in Trauma Patients and Interferes with their Function(Critical Care Medicine, 5/1/2015) Muroya, Takashi; Kannan, Lakshmi; Ghiran, Ionita C.; Shevkoplyas, Sergey S.; Paz, Ziv; Tsokos, Maria; Dalle Lucca, Jurandir J.; Shapiro, Nathan I.; Tsokos, George C.Objective Complement system is activated in patients with trauma. Although complement activation is presumed to contribute to organ damage and constitutional symptoms, little is known about the involved mechanisms. Because complement components may deposit on red blood cells (RBC), we asked whether complement deposits on the surface of RBC in trauma and whether such deposition alters RBC function. Design A prospective experimental study Setting Research laboratory Subjects Blood samples collected from 42 trauma patients and 21 healthy donors Intervention None Measurements and Main Results RBC and sera were collected from trauma patients and control donors. RBC from trauma patients (n=40) were found to display significantly higher amounts of C4d on their surface by flow cytometry compared to normal RBC (n=17) (P<0.01). Increased amounts of iC3b were found in trauma sera (n=27) (vs. 12 controls, P<0.01) by ELISA. Incubation of RBC from universal donors (O,Rh-) with trauma sera (n=10) promoted C4d deposition on their surface (vs. 6 controls, P<0.05). Complement-decorated RBC (n=6) displayed limited their deformability (vs. 6 controls, P<0.05) in 2-dimensional microchannel arrays. Incubation of RBC with trauma sera (n=10) promoted the phosphorylation of band 3, a cytoskeletal protein important for the function of the RBC membrane (vs. 8 controls, P<0.05), and also accelerated calcium influx (n=9) and enhanced nitric oxide production (n=12) (vs. 4 and 8 controls respectively, P<0.05) in flow cytometry. Conclusions Our study found the presence of extensive complement activation in trauma patients and presents new evidence in support of the hypothesis that complement activation products deposit on the surface of RBC. Such deposition could limit RBC deformability and promote the production of nitric oxide. Our findings suggest that RBC in trauma patients malfunction, which may explain organ damage and constitutional symptoms that is not accounted for otherwise by previously known pathophysiologic mechanisms.Item Ligation of Glycophorin A Generates Reactive Oxygen Species Leading to Decreased Red Blood Cell Function(PLoS One, 1/19/2016) Khoory, Joseph A.; Estanislau, Jessica; Elkhal, Abdallah; Lazaar, Asmae; Melhorn, Mark I.; Brodsky, Abigail; Illigens, Ben; Hamanchi, Itaru; Kurishita, Yasutaka; Ivanov, Alexander R.; Shevkoplyas, Sergey S.; Shapiro, Nathan I.; Ghiran, Ionita C.Acute, inflammatory conditions associated with dysregulated complement activation are characterized by significant increases in blood concentration of reactive oxygen species (ROS) and ATP. The mechanisms by which these molecules arise are not fully understood. In this study, using luminometric- and fluorescence-based methods, we show that ligation of glycophorin A (GPA) on human red blood cells (RBCs) results in a 2.1-fold, NADPH-oxidase-dependent increase in intracellular ROS that, in turn, trigger multiple downstream cascades leading to caspase-3 activation, ATP release, and increased band 3 phosphorylation. Functionally, using 2D microchannels to assess membrane deformability, GPS-ligated RBCs travel 33% slower than control RBCs, and lipid mobility was hindered by 10% using fluorescence recovery after photobleaching (FRAP). These outcomes were preventable by pretreating RBCs with cell-permeable ROS scavenger glutathione monoethyl ester (GSH-ME). Our results obtained in vitro using anti-GPA antibodies were validated using complement-altered RBCs isolated from control and septic patients. Our results suggest that during inflammatory conditions, circulating RBCs significantly contribute to capillary flow dysfunctions, and constitute an important but overlooked source of intravascular ROS and ATP, both critical mediators responsible for endothelial cell activation, microcirculation impairment, platelet activation, as well as long-term dysregulated adaptive and innate immune responses.Item SLE serum deposits C4d on red blood cells, decreases red blood cell membrane deformability, and promotes nitric oxide production(Arthritis & Rheumatism, 4/23/2012) Ghiran, Ionita C.; Zeidel, Mark L.; Shevkoplyas, Sergey S.; Burns, Jennie M.; Tsokos, George C.; Kyttaris, Vasileios C.Objective Systemic lupus erythematosus (SLE) is characterized by intravascular activation of the complement system and deposition of complement fragments (C3 and C4) on plasma membranes of circulating cells, including red blood cells (RBC). The aim of this study was to address whether this process affects the biophysical properties of RBC. Methods Serum and red blood cells were isolated from patients with SLE, and healthy controls. RBC from healthy O Rh negative individuals were incubated with SLE or control serum. We used flow cytometry to assess complement fragment deposition on RBC. RBC membrane deformability was measured using 2D microchannel arrays. Protein phosphorylation levels were quantified by western blot. Results Incubation of healthy donor RBC with sera from patients with SLE but not control sera led to deposition of C4 fragments on the RBC. Complement decorated RBC exhibited significant decrease in both membrane deformability and flickering. Sera from SLE patients triggered a transitory Ca++ influx in RBC that was associated with decreased phosphorylation of ?-spectrin, and increased phosphorylation of band 3, two key proteins of RBC cytoskeleton. Finally, SLE but not control sera led to the production of nitric oxide (NO) by RBC. Conclusion Our data suggest that complement activation in patients with SLE leads to calcium dependent cytosketeletal changes in RBC that render them less deformable, likely impairing their flow through capillaries. This phenomenon may negatively impact the delivery of oxygen to the tissues.