Increased activation and expansion of a CD57+ subset within peripheral CD8+ T lymphocytes in mycobacterium tuberculosis-infected patients

Background: Mycobacterium tuberculosis-specific CD8+ and CD4+ T lymphocyte responses restrict the spread of extracellular pathogens by limiting M. tuberculosis replication. Alterations in cytolytic function, inappropriate maturation/differentiation, and limited proliferation could reduce their ability to control M. tuberculosis replication. Methods: In an attempt to further characterize the immune responses during M.tuberculosis infection, we enumerated γδ and αβ receptor-bearing T cells expressing CD8 or CD4 phenotype and analyzed the differentiation phenotypes of CD8+ and CD4+ T lymphocyte subpopulations in 47 cases (23 new cases and 24 multidrug resistant patients) and 20 control subjects, using flowcytometry. Results: We found that the CD4/CD8 ratio was significantly lower in newly-diagnosed M.tuberculosis patients compared to multidrug resistant and control subjects (P < 0.003). Also, we found that a large proportion of CD8+ T lymphocytes in newly-diagnosed patients was defined by increased surface expression of CD57 as compared to the two other settings (P < 0.002). This increase was more profound in patients with an inverted CD4/CD8 ratio. Analysis of the late activation antigen revealed that this was predominantly HLA-DR+ (P < 0.003). No significant changes were observed in the percentages of CDB+CD57+ T cells between the different settings. Moreover, the co-stimulatory molecule CD28+ tended to be underexpressed by CD8+ T cells in multidrug resistant patients when compared to newly-diagnosed subjects (P < 0.002), but not to the control subjects. In contrast, the frequency of CD28+ marker on CD4+ T cells was higher in the setting of multidrug resistant compared with those of new cases (P < 0.0001). No significant changes were observed in percentages of γδ receptor-bearing T cells between different groups. Conclusion: We suggest that the increase in the proportion of CD57+ within CD8+ T cells in newly-diagnosed patients results from M.tuberculosis antigenic stimulation, which is a hallmark of many infections and that the protracted accumulation of CD57+ T lymphocytes might reflect an end-stage differentiation phenotype

"Proliferation of cytotoxic and activated T cells during acute Epstein-Barr virus induced Infectious Mononucleosis "

The immune responses that develop following Epstien-Barr Virus (EBV) infection are complex and involve both humoral and to a greater extent cell-mediated immune mechanisms. To evaluate the immune response, flow cytometric analysis of the peripheral blood of six patients during the acute phase of EBV infection was performed. This analysis revealed a significant increase in the percentages and the absolute number of CD8+cytotoxic and activated (HLA-DR+ - T lymphocytes and in some cases with a concomitan decrease in the percentages of B (CD19+) lymphocytes and T helper (CD4+) lymphocytes. These patient invariably had inverted CD4/CD8 ratio. All changes reversed to normal level during the recovery phase of infection. It is therefore concluded that EBV specific cytotoxic and activated T lymphocytes are essential in controlling acute EBV infection presented by the infected B cells

Electrospun PGA/gelatin nanofibrous scaffolds and their potential application in vascular tissue engineering

Hadi Hajiali1, Shapour Shahgasempour1, M Reza Naimi-Jamal2, Habibullah Peirovi11Nanomedicine and Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences; 2Department of Chemistry, Iran University of Science and Technology, Tehran, IranBackground and methods: In this study, gelatin was blended with polyglycolic acid (PGA) at different ratios (0, 10, 30, and 50 wt%) and electrospun. The morphology and structure of the scaffolds were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The mechanical properties were also measured by the tensile test. Furthermore, for biocompatibility assessment, human umbilical vein endothelial cells and human umbilical artery smooth muscle cells were cultured on these scaffolds, and cell attachment and viability were evaluated.Results: PGA with 10 wt% gelatin enhanced the endothelial cells whilst PGA with 30 wt% gelatin increased smooth muscle cell adhesion, penetration, and viability compared with the other scaffold blends. Additionally, with the increase in gelatin content, the mechanical properties of the scaffolds were improved due to interaction between PGA and gelatin, as revealed by Fourier transform infrared spectroscopy and differential scanning calorimetry.Conclusion: Incorporation of gelatin improves the biological and mechanical properties of PGA, making promising scaffolds for vascular tissue engineering.Keywords: polyglycolic acid, gelatin, nanofiber, vascular tissue engineering, biocompatible scaffold&amp;nbsp

Systemic sclerosis immunoglobulin G autoantibodies bind the human cytomegalovirus late protein UL94 and induce apoptosis in human endothelial cells

Systemic sclerosis is an autoimmune disease characterized by immunological and vascular abnormalities. Autoantibodies against intracellular antigens are associated with particular clinical features of the disease, whereas autoantibodies against cell surface antigens may be pathogenic by inducing endothelial cell damage, considered the primary event in the pathogenesis of the disease. Latent human cytomegalovirus infection may contribute to progression of systemic sclerosis through its ability to infect endothelial cells; however, direct links between human cytomegalovirus infection and systemic sclerosis are still lacking. Molecular mimicry is one of the mechanisms that account for the link between infection and autoimmunity. Here we have identified an immunodominant peptide using systemic sclerosis serum screening of a random peptide library; such peptide shares homology with autoantigens and with the human cytomegalovirus late protein UL94 (ref. 9). Immunoglobulin G antibodies against the peptide affinity-purified from the sera of patients with systemic sclerosis specifically recognized the viral product and autoantigens; moreover, such antibodies induced endothelial cell apoptosis through specific interaction with the cell surface integrin-NAG-2 protein complex. Our results provide evidence that antibodies against human cytomegalovirus cause apoptosis of endothelial cells, considered the initial pathogenic event of systemic sclerosis, and indicate a previously unknown mechanism for the etiological link between human cytomegalovirus infection and autoimmunity

A Sensitive Method for Quantifying Cytomegalic Endothelial Cells in Peripheral Blood from Cytomegalovirus-Infected Patients

A sensitive method has been developed for the quantification of cytomegalic endothelial cells (CEC) in peripheral blood (PB) of patients with active cytomegalovirus (CMV) infections. The three subsequent key steps of this method are density centrifugation to enrich endothelial cells (EC) in the mononuclear cell (MNC) fraction, EC-specific staining, and fluorescence-activated cell sorting (FACS) of EC onto adhesion slides. The FACS method was compared with the conventional method of cytocentrifugation of the MNC fraction onto slides, followed by EC-specific staining. The main advantage of the additional steps for the isolation and quantification of CEC in PB by FACS is a 10-times-greater sensitivity than by cytocentrifugation of the MNC fraction alone. The recovery percentages of EC from whole blood were comparable for both methods. Recoveries of EC obtained after FACS were 53% ± 16.5%, (mean ± standard deviation), and recoveries of EC obtained after cytocentrifugation of the MNC fraction were 43% ± 4.3%. In patients with active CMV infection, 5 to 72 CEC were detected by FACS, equivalent to 0.8 to 9.0 CEC/ml of blood. With this method for isolation and quantification, the characterization of CEC in PB of patients with CMV-associated clinical symptoms, as well as the quantification of EC in PB of patients with pathophysiological manifestations involving endothelial damage that are different from those caused by CMV infections, can be performed