Visualization of Activated T Cells by OX40-ImmunoPET as a Strategy for Diagnosis of Acute Graft-versus-Host Disease.

Graft-versus-host disease (GvHD) is a major complication of allogeneic hematopoietic cell transplantation (HCT), mediated primarily by donor T cells that become activated and attack host tissues. Noninvasive strategies detecting T-cell activation would allow for early diagnosis and possibly more effective management of HCT recipients. PET imaging is a sensitive and clinically relevant modality ideal for GvHD diagnosis, and there is a strong rationale for the use of PET tracers that can monitor T-cell activation and expansion with high specificity. The TNF receptor superfamily member OX40 (CD134) is a cell surface marker that is highly specific for activated T cells, is upregulated during GvHD, and mediates disease pathogenesis. We recently reported the development of an antibody-based activated T-cell imaging agent targeting OX40. In the present study, we visualize the dynamics of OX40 expression in an MHC-mismatch mouse model of acute GvHD using OX40-immunoPET. This approach enabled visualization of T-cell activation at early stages of disease, prior to overt clinical symptoms with high sensitivity and specificity. This study highlights the potential utility of the OX40 PET imaging as a new strategy for GvHD diagnosis and therapy monitoring. SIGNIFICANCE: OX40-immunoPET imaging is a promising noninvasive strategy for early detection of GvHD, capable of detecting signs of GvHD pathology even prior to the development of overt clinical symptoms.

Diagnostic performance in active TB of QFT-Plus assay and co-expression of CD25/CD134 in response to new antigens of Mycobacterium tuberculosis.

The new QuantiFERON-TB Gold Plus employs modified peptides optimized to elicit an IFNγ response from CD8+ cytotoxic T lymphocytes in addition to CD4+ T cells. With a view to improve the difficult identification of TB cases, we assessed the combination of two specific immunological markers comprising IFNγ secretion and T cells co-expression of CD25 and CD134 in response to Mycobacterium tuberculosis-specific antigens. A total of 34 subjects with suspected TB and 10 age-matched HD were prospectively enrolled. Assessing the performance of QFT-Plus in terms of the TB1 and TB2 results, we found that in TB patients, the quantitative IFNγ value in TB2 was similar to that in TB1, and we did not find any differences irrespective of the disease (pulmonary or extra-pulmonary). The flow cytometric CD25/CD134 assay, allowed a more accurate differentiation between M. tuberculosis-infected and uninfected patients, with a better combination of sensitivity and specificity, especially by evaluation of CD4+ T-cell subset. All individuals with negative QFT-Plus results displayed a positive CD25/CD134 response. Overall, a positive correlation was found between T cells co-expressing CD25/CD134 and IFNγ levels in response to both QFT-Plus TB antigen tubes, as well as between the QFT-Plus TB1 and TB2 tubes. We demonstrated that both TB1 and TB2 induce a higher expression of CD25+CD134+ markers on CD4+ T cells among infected TB subjects, compared to the lower degree of CD8+ T cells, mainly induced to TB2 stimulation. We suggest that a combined use of classic QFT-Plus and specific CD25/CD134 response may be a useful means in the diagnostic workup for active TB.

The In Vitro Impact of Glycyrrhizic Acid on CD4+ T Lymphocytes through OX40 Receptor in the Patients with Allergic Rhinitis.

Glycyrrhizic acid (GA), the major bioactive component of glycyrrhiza, possesses anti-inflammatory, anti-allergic, and immunomodulatory activities. This study aimed to investigate the in vitro anti-allergic effect of GA through the OX40 receptor in patients with allergic rhinitis. Purified naive CD4+ T cells of patients with allergic rhinitis (n = 12) were activated with anti-CD3/anti-CD28 with and without anti-OX40 agonist mAbs and then treated with 50, 100, and 200 µM GA and 0.1 µM dexamethasone. Cells were incubated (72 h) to measure cell proliferation. Expression of OX40 in anti-OX40 mAb stimulated CD4+ T cells was evaluated by flow cytometry. mRNA expression of the OX40 receptor and T-bet, GATA-3, and forkhead box P3 (FoxP3) transcriptional factors were measured by a quantitative polymerase chain reaction. The levels of interleukin (IL)-4, IL-10, and interferon-γ (IFN-γ) were also measured. GA inhibited significantly the augmented T cell proliferation induced with anti-OX40 mAb. Protein and gene expression of OX40 was also decreased significantly. Dexamethasone and GA inhibited T-bet and GATA-3 genes expression, but this inhibition was only significant for GATA-3. In contrast, enhanced gene expression of FoxP3 was seen using 200 µM GA and dexamethasone. The levels of IL-4, IL-10, and IFN-γ decreased after treatment with both dexamethasone and GA, but the ratio of IFN-γ/IL-4 (Th1/Th2 balance) increased significantly due to 200 µM GA treatment. This study suggests that GA may have a therapeutic effect on allergic rhinitis, partly by modulation of the Th1/Th2 balance through suppression of OX40 and increasing the activity of regulatory T cells.

Augmentation of CD134 (OX40)-dependent NK anti-tumour activity is dependent on antibody cross-linking.

CD134 (OX40) is a member of the tumour necrosis factor receptor superfamily (TNFRSF). It acts as a costimulatory receptor on T cells, but its role on NK cells is poorly understood. CD137, another TNFRSF member has been shown to enhance the anti-tumour activity of NK cells in various malignancies. Here, we examine the expression and function of CD134 on human and mouse NK cells in B-cell lymphoma. CD134 was transiently upregulated upon activation of NK cells in both species. In contrast to CD137, induction of CD134 on human NK cells was dependent on close proximity to, or cell-to-cell contact with, monocytes or T cells. Stimulation with an agonistic anti-CD134 mAb but not CD134 ligand, increased IFNγ production and cytotoxicity of human NK cells, but this was dependent on simultaneous antibody:Fcγ receptor binding. In complementary murine studies, intravenous inoculation with BCL1 lymphoma into immunocompetent syngeneic mice resulted in transient upregulation of CD134 on NK cells. Combination treatment with anti-CD20 and anti-CD134 mAb produced a synergistic effect with durable remissions. This therapeutic benefit was abrogated by NK cell depletion and in Fcγ chain -/- mice. Hence, anti-CD134 agonists may enhance NK-mediated anti-tumour activity in an Fcγ receptor dependent fashion.

CD4+ T Cells Coexpressing CD134 (OX40) Harbor Significantly Increased Levels of Human Herpesvirus 6B DNA Following Umbilical Cord Blood Transplantation.

Human herpesvirus 6B (HHV-6B) commonly reactivates after umbilical cord blood transplantation (UCBT) and is associated with delayed engraftment, fever, rash, and central nervous system dysfunction. Recently, CD134 (OX40) has been implicated as a potential viral entry receptor. We evaluated CD4+CD134+/neg-lo and CD8+CD134+/neg-lo cells at day 28 after UCBT in 20 subjects with previously documented HHV-6 reactivation and persistent viremia. Analysis of CD4+CD134+ cells as compared to CD4+CD134neg-lo cells showed 0.308 versus 0.129 copies of HHV-6B/cell (P = .0002). CD8+CD134+/neg-lo cells contained little to no HHV-6B copies. Following UCBT, CD4+CD134+ cells harbor significantly increased levels of HHV-6B, suggesting that CD134 (OX40) may facilitate viral entry.

Surface expression of inhibitory (CTLA-4) and stimulatory (OX40) receptors by CD4+ regulatory T cell subsets circulating in human malaria.

Several CD4+ T cell subtypes contribute to immune homeostasis in malaria, but the markers that define the main suppressive T cell subsets induced by this infection remain largely unknown. Here we provide a detailed phenotypic characterization of immunoregulatory CD4+ T cell populations in uncomplicated human malaria. We found an increased proportion of CD4+ T cells expressing CTLA-4, OX40, GITR, TNFRII, and CD69 in acute-phase single-species infections with Plasmodium vivax, Plasmodium falciparum, or both. Such an increase was not proportional to parasite density in P. vivax infections, and did not persist after parasite clearance. Significantly, less than 10% of CD4+ T cells expressing these regulatory molecules had the classical T regulatory (Treg) phenotype (CD4+CD25+CD127-FoxP3+). Two major Treg cell subpopulations, which together accounted for 19-23% of all Treg cells circulating in malaria patients, expressed surface receptors with opposing regulatory functions, either CTLA-4 or OX40. OX40+ Treg cells outnumbered their CTLA-4+ counterparts (1.8:1) during acute P. vivax infection, while a more balanced ratio (1.3:1) was observed following parasite clearance These data reveal new players in the complex CD4+ Treg cell network that maintains immune homeostasis in malaria and suggest potential targets for therapeutic interventions to improve parasite-specific effector immune responses.

Imbalanced expression of functional surface molecules in regulatory and effector T cells in systemic lupus erythematosus.

Regulatory T (TREG) cells play an important role in maintaining immune tolerance and avoiding autoimmunity. We analyzed the expression of membrane molecules in TREG and effector T cells in systemic lupus erythematosus (SLE). TREG and effector T cells were analyzed for the expression of CTLA-4, PD1, CD28, CD95, GITR, HLA-DR, OX40, CD40L, and CD45RO in 26 patients with active disease, 31 with inactive disease, and 26 healthy controls. TREG cells were defined as CD25+/high CD127 Ø/low FoxP3+, and effector T cells were defined as CD25+CD127+FoxP3 Ø. The ratio of TREG to effector T cells expressing GITR, PD1, HLA-DR, OX40, CD40L, and CD45RO was determined in the three groups. The frequency of TREG cells was similar in patients with SLE and controls. However, SLE patients had a decreased frequency of CTLA-4+TREG and CD28+TREG cells and an increased frequency of CD40L+TREG cells. There was a decrease in the TREG/effector-T ratio for GITR+, HLA-DR+, OX40+, and CD45RO+ cells, and an increased ratio of TREG/effector-T CD40L+ cells in patients with SLE. In addition, CD40L+TREG cell frequency correlated with the SLE disease activity index (P=0.0163). In conclusion, our findings showed several abnormalities in the expression of functionally critical surface molecules in TREG and effector T cells in SLE that may be relevant to the pathogenesis of this disease.

Establishment of a healthy human range for the whole blood "OX40" assay for the detection of antigen-specific CD4+ T cells by flow cytometry.

BACKGROUND: Clinical investigation of antigen-specific T cells in potentially immunodeficient patients is an important and often challenging aspect of patient diagnostic work up. Methods for detection of microbial exposure to the T-cell compartment exist but are laborious and time consuming. Recently, a whole blood technique involving flow cytometry and detection of CD25 and OX40 (CD134) expression on the surface of activated CD4+ T cells was shown to be accurate and concordant when compared with more traditional methods of antigen-specific T-cell detection. METHODS: Whole heparinized blood was collected from healthy donors and set up using the "OX40" assay to detect antigen-specific CD4+ T-cell responses to Varicella Zoster Virus, Epstein-Barr Virus (EBV), Cytomegalovirus, Candida albicans, and Streptococcus pneumoniae. RESULTS: The "OX40" assay technique was clinically validated for routine use in an NHS clinical immunology laboratory by analysis of incubation length (40-50 h), sample transport time (up to 24 h at room temperature), concordance with serology testing, proliferation and interferon-gamma production. In addition, 63 healthy controls (age range 21-78) were tested for responses to generate a healthy control reference range. CONCLUSIONS: The OX40 assay, as presented in this report, represents an economical, rapid, robust whole blood technique to detect antigen-specific T cells, which is suitable for clinical immunology diagnostic laboratory use.

Increased expression of OX40 is associated with progressive disease in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis.

BACKGROUND: OX40 is a member of the tumor necrosis factor receptor family that is expressed primarily on activated CD4+ T cells and promotes the development of effector and memory T cells. Although OX40 has been reported to be a target gene of human T-cell leukemia virus type-1 (HTLV-1) viral transactivator Tax and is overexpressed in vivo in adult T-cell leukemia (ATL) cells, an association between OX40 and HTLV-1-associated inflammatory disorders, such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), has not yet been established. Moreover, because abrogation of OX40 signals ameliorates chronic inflammation in animal models of autoimmune disease, novel monoclonal antibodies against OX40 may offer a potential treatment for HTLV-1-associated diseases such as ATL and HAM/TSP. RESULTS: In this study, we showed that OX40 was specifically expressed in CD4+ T cells naturally infected with HTLV-1 that have the potential to produce pro-inflammatory cytokines along with Tax expression. We also showed that OX40 was overexpressed in spinal cord infiltrating mononuclear cells in a clinically progressive HAM/TSP patient with a short duration of illness. The levels of the soluble form of OX40 (sOX40) in the cerebrospinal fluid (CSF) from chronic progressive HAM/TSP patients or from patients with other inflammatory neurological diseases (OINDs) were not different. In contrast, sOX40 levels in the CSF of rapidly progressing HAM/TSP patients were higher than those in the CSF from patients with OINDs, and these patients showed higher sOX40 levels in the CSF than in the plasma. When our newly produced monoclonal antibody against OX40 was added to peripheral blood mononuclear cells in culture, HTLV-1-infected T cells were specifically removed by a mechanism that depends on antibody-dependent cellular cytotoxicity. CONCLUSIONS: Our study identified OX40 as a key molecule and biomarker for rapid progression of HAM/TSP. Furthermore, blocking OX40 may have potential in therapeutic intervention for HAM/TSP.

Serial study of lymph node cell subsets using fine needle aspiration in pigtail macaques.

Lymphoid tissues are of intense interest for studies of the pathogenesis of human immunodeficiency virus (HIV) in humans and simian immunodeficiency virus (SIV) in macaques but are relatively difficult to sample non-invasively. Fine needle aspiration (FNA) cytology, conventionally a diagnostic procedure for lymphadenopathy, can be used for longitudinal study of tissue cell subsets during HIV/SIV infection. In this study, we serially sampled lymph node (LN) FNA from pigtail macaques and studied cell subsets in the aspect of absolute count, frequency, and functionality by flow cytometry. The median recovered lymphocyte count from FNA samples was 2.01×10(5) (3.0×10(3) to 2.25×10(6), n=38) and median CD4+ T cell subset recovered was 5.94×10(4) (277 to 6.17×10(5), n=38). Although we observed a relatively large variation in the frequencies of cell subsets of FNA samples taken from different time points, the cell subset composition of FNA samples, in particular T cell and CD4+ T cell frequencies, was broadly comparable to whole excised LNs (n=6) and distinct from peripheral blood. A subset of CD4+ T cells that is located almost exclusively in secondary lymphoid tissues, T follicular helper (TFH) cells, was readily identifiable in LN FNAs and the TFH cell frequencies were strongly correlated with B cell frequencies. In vitro functionality of FNA lymphocytes was demonstrated using polyclonal SEB stimulation, resulting in a median 6% of responding CD4+ T cells, comparable to circulating CD4+ T lymphocytes. We conclude that serial sampling of macaque LNs using FNA is a potentially useful method to study the immunopathogenesis of SIV infection and may be extended to HIV infection.

OX40+ T lymphocytes and IFN-γ are associated with American tegumentary leishmaniasis pathogenesis.

BACKGROUND: Leishmaniases are zoonoses considered a public health problem, representing a complex group of diseases with a broad clinical spectrum and epidemiological diversity. Leishmaniasis is caused by several species of protozoa of the genus Leishmania. The evolution of the pathology and the resolution of the leishmaniasis are dependent mainly on the Leishmania species involved, although the cytokine profile plays an important role in the development of the immune response. OBJECTIVES: The purpose of our study was to evaluate the immune response of patients affected by lesions of cutaneous leishmaniasis by immunostaining of the OX40, CD20, IFN-γ and IL-4 proteins. METHODS: The tissue samples were collected from indolent skin ulcers confirmed as cutaneous leishmaniasis of 41 patients aged between six and 90 years. The lesions were submitted to OX40, CD20, INF-γ and IL-4 immunolabeling. RESULTS: We observed a statistically significant higher expression of IFN-γ compared with IL-4 (p=0.009). Besides, OX40 had higher expression when compared with CD20 (p<0.001). CONCLUSION: The present study indicates that the immune response in lesions of cutaneous leishmaniasis is associated with a healing process, which can be explained by the higher expression of IFN-γ when compared with IL4 protein levels.

Study on the expression of co-stimulatory marker CD134 on CD4+ T cells in HIV-1-infected individuals.

CD4+CD25+CD134+ T cells play an important role in suppressing T cell responses to foreign pathogens, including human immunodeficiency virus (HIV). Thus, we aimed to investigate an increase in these populations in HIV-1-infected individuals. In this study, we used a panel of monoclonal antibodies staining of CD3/CD4/CD25/CD134. Without antigen stimulation, the expression of CD4+CD25+CD134+ T cells in 14 HIV-1-infected and 24 healthy individuals were 4.01% and 3.21%, respectively. However, there was an increase in the expression of CD4 + CD25+CD134+ T cells in HIV-1-infected individuals (6.85%) when stimulated with gag peptide. The upregulation of CD4+CD25+CD134+ T cells in HIV-1-infected individuals may result from activation of naturally occurring or by disease-associated antigen stimulation.

Determination of the activity of CD134 (OX-40) and CD137 (4-1BB) adhesive molecules by means of flow cytometry in patients with colorectal cancer metastases to the liver.

UNLABELLED: Colorectal carcinoma (CRC) is one of the most common reasons of mortality in patients diagnosed with neoplasms. In nearly 20% of patients with colorectal carcinoma metastatic lesions are diagnosed. In general, survival of patients with metastatic lesions to the liver and other organs is poor. Conventional therapy of colorectal carcinoma is based on the surgical excision of the tumor, chemotherapy, and radiotherapy. THE AIM OF THE STUDY: was to determine the expression of CD134 and CD137 molecules inside the tumor, at the border of the tumor, in the healthy tissue, and peripheral blood, considering patients with colorectal carcinoma metastases to the liver. MATERIAL AND METHODS: The study group comprised 39 patients subject to surgical treatment at the Department of General and Gastroenterological Surgery, due to colorectal carcinoma with liver metastases. CD134 and CD137 adhesive molecule levels were determined inside the tumor, at the border of the tumor, and in the healthy margins of the surgical incision. Additionally, the authors evaluated the peripheral blood level of the above-mentioned molecules on the day of the surgical procedure, and 10 days, thereafter. RESULTS: The mean CD134 levels were the highest inside the tumor, significantly decreasing towards the direction of healthy tissues. The average peripheral blood molecule levels were four-fold higher on the day of the surgical procedure, as compared to values obtained on the tenth postoperative day. This dependency also concerned the remaining statistical measures.The mean CD137 levels showed no significant difference, regardless their location. The authors observed significant, peripheral blood, CD137 level differences, considering the day of the surgical procedure and tenth postoperative period. The mean CD137 peripheral blood level was several times higher on the day of the surgical procedure, as compared to the postoperative period. CONCLUSIONS: The determination of the activity of CD134 and CD137 molecules might create opportunities to plan treatment and predict prognosis in case of colorectal carcinoma. Proper immuno-therapeutic management which is based on the expression of the above-mentioned molecules might help determine the risk of metastases, preventing from their development. In advanced cases treatment of liver metastases might be possible.

Incorporation of endothelial progenitor cells into the neovasculature of malignant glioma xenograft.

Endothelial progenitor cells (EPCs) are important initiators of vasculogenesis in the process of tumor neovascularization. However, it is unclear how circulating EPCs contribute to the formation of tumor microvessels. In this study, we isolated CD34(+)/CD133(+) cells from human umbilical cord blood (HUCB) and obtained EPCs with the capacities of forming colonies, uptaking acetylated low-density lipoprotein (ac-LDL), binding lectins and expressing vascular endothelial growth factor (VEGF) receptor 2 (VEGFR-2, KDR), CD31 and von Willebrand factor (vWF). These EPCs were actively proliferative and migratory, and could formed capillary-like tubules in response to VEGF. When injected into mice bearing subcutaneously implanted human malignant glioma, EPCs specifically accumulated at the sites of tumors and differentiated into mature endothelial cells (ECs), which accounted for 18% ECs of the tumor microvessels. The incorporation of circulating EPCs into tumor vessel walls significantly affected the morphology and structure of the vasculature. Our results suggest that circulating EPCs constitute important components of tumor microvessel network and contribute to tumor microvascular architecture phenotype heterogeneity.

Establishment of a feline astrocyte-derived cell line (G355-5 cells) expressing feline CD134 and a rapid quantitative assay for T-lymphotropic feline immunodeficiency viruses.

Few laboratory strains of feline immunodeficiency virus (FIV) can infect Crandell feline kidney cells (an epithelial-type of cells), however, most primary isolates are T-lymphotropic. T-lymphotropic FIV requires both feline CD134 (an activation marker of helper T-lymphocytes) and CXCR4 (a chemokine receptor) in infection as primary and secondary receptors, respectively. Using feline T-lymphoblastoid cell lines, titration of primary FIV isolates was carried out, however the titration assay was laborious and time-consuming. In this study, using G355-5 cells (a feline astrocyte-derived cell line) transduced with a cDNA of feline CD134 as target cells, an assay system was developed to quantitate primary FIV isolates. With a previous method using a feline T-lymphoblastoid cell line (MYA-1 cells) highly sensitive to FIV, it took 12 days to complete the assay, however, it took only 2 days with the new method. The FIV-infected cells became in a state of persistent infection, producing a large amount of FIV, indicating that the cells will be useful for propagation of T-lymphotropic FIV strains.

Synovial fluid OX40T lymphocytes of patients with rheumatoid arthritis display a Th2/Th0 polarization.

Rheumatoid arthritis (RA) is an autoimmune disease in which T-cell activation plays a pivotal role in the induction of articular damage. CD4+/OX40+ T cells accumulate in the synovial fluid (SF) of RA patients, which suggests that they are involved in the pathogenesis of the disease. In this study, we assessed the intracellular cytokine production of peripheral blood and SF CD4+ and CD4+/OX40+ T cells from RA patients in order to evaluate their role in this disorder. Our results show that SF CD4+ cells are predominantly interferon gamma (IFN-gamma)-positive and express a Th1-like cytokine pattern. In SF, significantly more CD4+/OX40+ T cells expressed interleukin-4 (IL-4) and IL4/IFN-gamma than IFN-gamma alone. Our data demonstrate that SF CD4+/OX40+ T cells express a Th2/Th0 cytokine profile, which suggests that they are involved in inflammatory responses in RA joints.