Acute Symptomatic Influenza A Virus (IAV) Infection in Humans Leads to Expansion of Highly Diverse CD8 T Cell Repertoires Crossreactive with Persistent Epstein Barr Virus (EBV)

The competence of T cell responses predominantly depends on how efficient T cell receptors (TCRs) are at recognizing antigenic epitopes. We show here that during acute severely symptomatic IAV infection there was an expansion of IAV-M1/EBV-BRLF1 and IAV-M1/EBV-BMLF1 double-tetramer+ cells directly ex-vivo in 5 HLA-A2+ patients. We questioned whether this expansion specific to these two different crossreactive responses would lead to alterations in the TCR repertoire of the IAV-M158 , EBV-BRLF1109 and -BMLF1280 from before, during and following acute IAV infection. Using staining with Vb MAb we found that T cell responses generated to these epitopes became surprisingly more polyclonal, with the sharing of Vb between M1, BMLF1 and BRLF1 populations which is not seen in healthy donors and which decreased 2 months later consistent with crossreactive expansion. Furthermore, by using single-cell analysis of TCRα and TCRβ repertoire of tetramer sorted IAV-M1 cells we showed dramatic changes in specific clonotype usage and in JA and JB family usage during acute IAV infection compared to before infection. In summary, these changes in TCR repertoire during acute symptomatic IAV infection suggest that during severe infection there is a preferential expansion of highly diverse crossreactive responses between IAV and the persistent virus, EBV, which leads to permanent changes in TCR repertoires to both of these two viruses. (NIHAI49320)

Severity of Infectious Mononucleosis (IM) Correlates with the Frequency of Crossreactive Influenza A Virus (IAV)-M1 and Epstein Barr Virus (EBV)-BMLF-1-specific CD8 T Cells

During EBV-associated IM IAV-specific crossreactive memory T cells are activated and play a role in disease severity. In HLA-A2+ IM patients, influenza M158 (IAV-M1)-specific CD8 memory T cell responses crossreacted with two different EBV lytic epitopes, BMLF1280 (17/29) and BRLF1190 (19/20). Furthermore, 11/22 IM patients demonstrated some intra-viral crossreactivity between EBV-BRLF1 and -BMLF1 responses. Disease severity of IM directly correlated with significantly increased frequencies of crossreactive IAV-M1/EBV-BMLF1, IAV-M1, and EBV-BMLF1 specific CD8 cells, and with mean viral load over the first 5 weeks of infection. Disease severity did not correlate with BRLF1 or M1/BRLF1 crossreactive responses. When severity of IM was scored and patients were assigned to either mild or severe groups, disease severity correlated with specific TCR Vb usage in IAV-M1 population suggesting that TcR selection is driving disease outcome. Consistent with IAV-M1 and EBV-BMLF1 responses driving increased immunopathology was the observation that patients with severe disease had significantly more IAV-M1 and EBV-BMLF1 cells producing IFNg/MIP1-b in response to antigen as compared to patients with mild disease. These results suggest that T cell crossreactivity impacts T cell selection and function and ultimately disease outcome. Insights on these issues are important for the intelligent design of vaccines and to develop therapeutic interventions for virally induced disease (NIHAI49320)

Crossreactive Epstein-Barr Virus (EBV)-Influenza A Virus (IAV) Specific CD8 Memory T Cells During Acute Symptomatic IAV Infection

We previously showed that crossreactivity is common between IAV and EBV in HLA-A2+ patients during infectious mononucleosis. IAV-M1-GIL58-66 specific CD8 T cells, along with expanded populations of IAV-M1-GIL58-66/EBV-BRLF-1109-117 -YVL and IAV-M1-GIL58-66/EBV-BMLF1280-288-GLC double-tetramer+ cells were detected directly ex-vivo in 5 HLA-A2+ patients. Altered IAV-M158-66, EBV-BRLF1119-117 and -BMLF1280-288 TCR repertoires were observed over the course of infection and in comparison to healthy donors. After culture, cells were sorted and analyzed by gene array in order to assess global changes in immune responses following different stimulations, either cognate or crossreactive, in different patient populations. M1-GIL and BRLF1-YVL specific cells had similar immune-response gene signatures, but the -GLC specific CD8 cells were more similar to the two-crossreactive populations. Crossreactive M1-GIL/BRLF1-YVL cells from the BRLF1-YVL line were different in their activation status than the BRLF1-specific cells, consistent with BRLF1-YVL ligand stimulation of different gene activation profiles in these two populations. These results suggest that during symptomatic IAV infection there is an expansion of EBV/IAV crossreactive memory CD8 T cell responses. Ongoing studies are investigating whether EBV-IAV cross-reactive CD8+ T cells may contribute to immunopathology during acute IAV infection (NIH / NIAID PO1 AI 049320)

Genotoxicity of anti-tumor necrosis factor therapy in patients with juvenile idiopathic arthritis

Objective. To assess the possible effects of both inflammation and the anti-tumor necrosis factor agents (anti-TNF) on DNA damage with a specific assay, and their effects on the repair capacity of DNA. Methods. From a group of 20 children with juvenile idiopathic arthritis (JIA), 16 patients who completed the study and 16 control subjects were evaluated. DNA damage and repair capacity were analyzed by the comet assay at the level of peripheral lymphocytes before anti-TNF (etanercept) injections and on the 15th, 90th, and 180th days after the first injection. Results. The amount of damage as detected by the aforementioned assay was higher in patients with JIA compared with controls. On the 15th day after the initial anti-TNF injection, there was a decrease in the mean DNA tail length of JIA patients, however on the 90th day an increase was observed; thereafter, an upward trend was observed until the end of the study. JIA patients had a DNA repair capacity that was significantly less than that of controls. Conclusion. The results of the comet technique suggests that JIA patients already have increased basal DNA damage before anti-TNF therapy; they are more sensitive to the DNA damage produced by H 2O 2, and have a less efficient DNA repair system in comparison with control cells. After an initial improvement at 2 weeks, parameters of genotoxicity worsened, and DNA repair was further impaired 6 months after the addition of an anti-TNF agent to treatment. © 2010, American College of Rheumatology

Epstein-Barr Virus (EBV)-lytic Cross-reactive Influenza-A (IAV) Memory CD8 T-cells in EBV Sero-negative Middle-aged Adults

EBV is a common human pathogen, which infects ~90% of people and establishes a life-long chronic infection. The clinical outcomes of acute infection can range from asymptomatic to severe immunopathology such as infectious mononucleosis (IM). However, for unknown reasons 5-10% of middle-aged adults (\u3e35 years) remain EBV-seronegative (EBV-SN) when the virus infects the vast majority of people, and is actively shed at high titers during chronic infection. Here we show that EBV-SN (ASN) HLA-A2+ middle-aged adults possess a unique IAV-M1-GIL58-66 memory CD8 T-cell response that cross-reacts with EBV lytic epitopes that differs from teenage EBV-SN (TSN) (18-19 years) and EBV-seropositive (EBV-SP) adult donors. The five tested HLA-A2+ EBV-SN middle-aged adults had a significantly increased IAV-M158-66-GIL tetramer+ CD8 frequency compared to EBV-SP donors. Upon exposure to EBV antigens in vitro both IAV-M158-66GIL/EBV-BMLF1280-288-GLC and IAV-M158-66-GIL/EBV-BRLF1109-117-YVL, functionally cross-reactive CD8+ responses could be detected in the peripheral blood of middle-aged EBV-SN donors, while only IAV-M1/EBV-YVL cross-reactive responses were detected in some teenage EBV-SN or EBV-seropositive people . Surprisingly, these IAV-M1-GIL-specific CD8 T-cells in middle-aged EBV-SN adults expanded dramatically to EBV lytic antigens and produced cytokines at high functional avidity. They lysed EBV-infected targets and showed potential (by CD103 expression) to enter mucosal epithelial tissue where infection initiates. Additionally, these cross-reactive cells had an oligo-clonal T-cell receptor repertoire different than EBV-SP donors. Taken together these data suggest that an altered cross-reactive T cell repertoire could mediate protective immunity against viral infection. Our results imply that sero-negative adults might have the ability to resist viral infection via heterologous immunity. (NIH-AI49320)

Epstein-Barr Virus Epitope-Major Histocompatibility Complex Interaction Combined with Convergent Recombination Drives Selection of Diverse T Cell Receptor alpha and beta Repertoires

Recognition modes of individual T cell receptors (TCRs) are well studied, but factors driving the selection of TCR repertoires from primary through persistent human virus infections are less well understood. Using deep sequencing, we demonstrate a high degree of diversity of Epstein-Barr virus (EBV)-specific clonotypes in acute infectious mononucleosis (AIM). Only 9% of unique clonotypes detected in AIM persisted into convalescence; the majority (91%) of unique clonotypes detected in AIM were not detected in convalescence and were seeming replaced by equally diverse de novo clonotypes. The persistent clonotypes had a greater probability of being generated than nonpersistent clonotypes due to convergence recombination of multiple nucleotide sequences to encode the same amino acid sequence, as well as the use of shorter complementarity-determining regions 3 (CDR3s) with fewer nucleotide additions (i.e., sequences closer to germ line). Moreover, the two most immunodominant HLA-A2-restricted EBV epitopes, BRLF1109 and BMLF1280, show highly distinct antigen-specific public (i.e., shared between individuals) features. In fact, TCRalpha CDR3 motifs played a dominant role, while TCRbeta played a minimal role, in the selection of TCR repertoire to an immunodominant EBV epitope, BRLF1. This contrasts with the majority of previously reported repertoires, which appear to be selected either on TCRbeta CDR3 interactions with peptide/major histocompatibility complex (MHC) or in combination with TCRalpha CDR3. Understanding of how TCR-peptide-MHC complex interactions drive repertoire selection can be used to develop optimal strategies for vaccine design or generation of appropriate adoptive immunotherapies for viral infections in transplant settings or for cancer. IMPORTANCE Several lines of evidence suggest that TCRalpha and TCRbeta repertoires play a role in disease outcomes and treatment strategies during viral infections in transplant patients and in cancer and autoimmune disease therapy. Our data suggest that it is essential that we understand the basic principles of how to drive optimum repertoires for both TCR chains, alpha and beta. We address this important issue by characterizing the CD8 TCR repertoire to a common persistent human viral infection (EBV), which is controlled by appropriate CD8 T cell responses. The ultimate goal would be to determine if the individuals who are infected asymptomatically develop a different TCR repertoire than those that develop the immunopathology of AIM. Here, we begin by doing an in-depth characterization of both CD8 T cell TCRalpha and TCRbeta repertoires to two immunodominant EBV epitopes over the course of AIM, identifying potential factors that may be driving their selection

Embryonal subregion-derived stromal cell lines from novel temperature-sensitive SV40 T antigen transgenic mice support hematopoiesis

Throughout life, the hematopoietic system requires a supportive microenvironment that allows for the maintenance and differentiation of hematopoietic stem cells (HSC). To understand the cellular interactions and molecules that provide these functions, investigators have previously established stromal cell lines from the late gestational stage and adult murine hematopoietic microenvironments. However, the stromal cell microenvironment that supports the emergence, expansion and maintenance of HSCs during mid-gestational stages has been largely unexplored. Since several tissues within the mouse embryo are known to harbor HSCs (i.e. aortagonads-mesonephros, yolk sac, liver), we generated numerous stromal cell clones from these mid-gestational sites. Owing to the limited cell numbers, isolations were performed with tissues from transgenic embryos containing the ts SV40 Tag gene (tsA58) under the transcriptional control of constitutive and ubiquitously expressing promoters. We report here that the growth and cloning efficiency of embryonic cells (with the exception of the aorta) is increased in the presence of the tsA58 transgene. Furthermore, our results show that the large panel of stromal clones isolated from the different embryonal subregions exhibit heterogeneity in their ability to promote murine and human hematopoietic differentiation. Despite our findings of heterogeneity in hematopoietic growth factor gene expression profiles, high-level expression of some factors may influence hematopoietic differentiation. Interestingly, a few of these stromal clones express a recently described chordin-like protein, which is an inhibitor of bone morphogenic proteins and is preferentially expressed in cells of the mesenchymal lineage