Expression Of B7 Research Articles

Expression of pro-inflammatory and co-stimulatory molecules on the surface of macrophages in vitro in patients with pulmonary tuberculosis

The aim of this study was to identify features of the expression of pro-inflammatory and co-stimulatory molecules on the surface of macrophages in vitro in patients with pulmonary tuberculosis, depending on the clinical form of the disease and sensitivity of the pathogen to anti-TB drugs. Materials and methods . 40 patients (36 men and 4 women) with pulmonary tuberculosis (TB) were examined: 18 patients (16 men and 2 women, average age (44.56 ± 8.10) years) with disseminated tuberculosis (DTB) and 22 patients (20 men and 2 women, average age (46.54 ± 5.24) years) with infiltrative tuberculosis (ITB). Of those, 30 patients secreted Mycobacterium tuberculosis (MBT) sensitive to the basic anti-TB drugs (ATBD), and 10 patients secreted MBT resistant to first-line anti-TB drugs. Venous blood was the study material. To isolate monocytes from the whole blood in order to transform them into macrophages, ficoll density gradient centrifugation with gradient density of 1.077 g/cm 3 was used followed by immunomagnetic separation of CD14 + cells. Monocytes were cultured in a complete culture medium X-VIVO 10 with gentamicin and phenol red with the addition of the macrophage colony-stimulating factor (M-CSF) (5 ng/ml) at a concentration of 1×10 6 cells/ml with the following stimulators: interleukin (IL) 4 (10 ng/ml) and interferon (IFN) γ (100 ng/ml). Immunophenotyping of macrophages was performed using monoclonal antibodies to CD80, CD86, and HLA-DR on a Beckman Coulter CytoFLEX LX flow cytometer (Beckman Coulter, USA). The analysis of the obtained data was carried out using the CytExpert 2.0 software application. The results were analyzed using statistical methods. Results . The number of intact and cytokine-stimulated (IL-4 and IFNγ) CD80-positive macrophages in patients with ITB and drug-resistant TB (DR TB) exceeded their number not only in healthy donors, but also in patients with DTB and drug-sensitive TB (DS TB), respectively. In addition, an increase in CD86 expression on the surface of macrophages was registered in patients with ITB and DR TB after adding IFNγ (M1-activation inducer) to the suspension culture. In contrast, in patients with DTB and DS TB, the number of macrophages with expression of B7 family co-stimulating molecules decreased or remained within the normal values in the absence of a reaction to cytokines during cytokine induction. Deficiency of HLA-DR-positive macrophages was found in all TB patients. The minimal number of macrophages expressing HLA-DR was found in patients with DTB and DS TB after cell incubation with IL-4 (M2-activation inducer). Conclusion . Evaluation of the expression of B7 (CD80/86) and HLA-DR membrane molecules on macrophages in TB patients allows to conclude that anti-TB immune response is impaired at stages of antigen presentation (in all examined patients with TB) and co-stimulation (in DTB and DS TB). An increase in the expression of macrophage surface molecules CD80 (with M1- and M2-stimulation) and CD86 (with M1-stimulation) in patients with ITB and DR TB indicates an increase in cell reactivity in these forms of TB. In addition, deficit of expression of HLA-DR (a key marker of pro-inflammatory cell activation) on the surface of macrophages in TB can be considered as a general (independent of the clinical form of the disease and drug sensitivity of the pathogen) pathogenetic factor of immune imbalance in pulmonary tuberculosis.

Expression and Clinical Significance of KLRG1 and 2B4 on T Cells in the Peripheral Blood and Tumour of Patients with Cervical Cancer

ABSTRACT Background Killer cell lectin-like receptor G1 (KLRG1) and 2B4 play important roles in the immune regulation and immune tolerance to tumor cells by inhibiting T cell function. However, the clinical relevance of KLRG1 and 2B4 to cervical cancer remains to be understood. Methods We measured the frequency of KLRG1+ or 2B4+ cells in CD4+ or CD8 + T cells derived from peripheral blood or tumour biopsies in cervical cancer patients by flow cytometry. Results Compared with healthy controls, the level of KLRG1 and 2B4 on CD8 + T cells in the blood of the patients increased significantly (P = .0056 and .0441). KLRG1 level on CD8 + T cells and 2B4 level on CD4 + T cells in peripheral blood were significantly higher than in tumor tissues (P < .0001 and P = .0003). Higher KLRG1 level on blood-derived CD8 + T cells was observed in patients older than 54 years (P = .001) or tested to be HPV-negative (P = .026). Tumor-infiltrated CD8 + T cells demonstrated elevated KLRG1 level in patients having pelvic lymph node metastasis (P = .016). Increased 2B4 level on blood-derived CD8 + T cells was also observed in patients older than 54 years (P < .001). KLRG1 expression on both CD4 + T (P = .0158) and CD8 + T (P = .0187) cells in the peripheral blood increased after radiotherapy. Conclusion KLRG1 level on T cells was related to age and HPV in patients with cervical cancer, while 2B4 level on T cells was related to age, underlying their roles in the host immune response to cervical cancer. Radiotherapy can improve the immune function of patients.

B7-CD28 co-stimulation modulates central tolerance via thymic clonal deletion and Treg generation through distinct mechanisms

The molecular and cellular mechanisms mediating thymic central tolerance and prevention of autoimmunity are not fully understood. Here we show that B7-CD28 co-stimulation and B7 expression by specific antigen-presenting cell (APC) types are required for clonal deletion and for regulatory T (Treg) cell generation from endogenous tissue-restricted antigen (TRA)-specific thymocytes. While B7-CD28 interaction is required for both clonal deletion and Treg induction, these two processes differ in their CD28 signaling requirements and in their dependence on B7-expressing dendritic cells, B cells, and thymic epithelial cells. Meanwhile, defective thymic clonal deletion due to altered B7-CD28 signaling results in the accumulation of mature, peripheral TRA-specific T cells capable of mediating destructive autoimmunity. Our findings thus reveal a function of B7-CD28 co-stimulation in shaping the T cell repertoire and limiting autoimmunity through both thymic clonal deletion and Treg cell generation.

Exhaustion of CD8+ T cell immune functions in spleen of mice with different doses of Echinococcus multilocularis infections

To examine the changes in the immune functions of CD8+ T cells in the spleen of mice following Echinococcus multilocularis infections at various doses and at different time points. The E. multilocularis protoscoleces were collected, and E. multilocularis infection was modeled in mice via the hepatic portal vein at doses of 50 (low-dose), 500 (medium-dose) and 2 000 protoscoleces (high-dose), while physiological saline served as controls. Mouse spleen was isolated 2 (earlystage), 12 (middle-stage) and 24 weeks post-infection (late-stage), and spleen lymphocytes were harvested. The phenotype of memory CD8+ T cells and 2B4 expression were quantified in the mouse spleen, and the secretion of interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-17A and IL-10 was measured. A central-memory phenotype was predominant in the CD8+ T cells in the spleen of mice at the early stage of high-dose protoscolece infections, and the proportion of central-memory CD8+ T cells was significantly greater in the high-dose group than in the control group (35.50% ± 2.00% vs. 25.90% ± 2.46%, P < 0.01), while a effector- memory phenotype was predominant in the CD8+ T cells in the spleen of mice at the late stage of medium- and high-dose protoscolece infections, and the proportions of effector-memory CD8+ T cells were significantly greater in the medium- (25.70% ± 4.12%) and high-dose group (28.40% ± 4.12%) than in the control group (10.50% ± 6.45%) (P < 0.05). The proportions of the central-memory CD8+ T cells were significantly higher in the high-dose group than at middle and late stages than at the early stage (P < 0.01), and the proportion of effector-memory CD8+ T cells was significantly greater in the high-dose group at the late stage than at early and middle stages (P < 0.05). The secretion of IFN-γ and IL-17A by spleen CD8+ T cells was elevated in the low- and medium-dose groups at the early stage of infection, and high-dose protoscolece infection promoted the secretion of IFN-γ and TNF-α by spleen CD8+ T cells; however, the levels of IFN-γ and TNF-α were significantly lower at the late stage than at the early and middle stages (P < 0.05). In addition, high 2B4 expression was detected in spleen CD8+ T cells in the middle- and high-dose groups at the late stage of infection, and the 2B4 expression was significantly higher in the medium(4.73% ± 1.56%) and high-dose groups (4.94% ± 1.90%) than in the low-dose group (2.49% ± 0.58%) and the control group (2.92% ± 0.60%) (P < 0.05). E. multilocularis may be killed and eliminated through the host immune responses at the middle and late stages of low- and medium-dose protoscolece infections, while high-dose protoscolece infections may trigger the upregulation of 2B4 expression in mouse spleen CD8+ T cells at the late stage, which leads to immune exhaustion and the resultant chronic infections.

Brief Report: Diminished Coinhibitory Molecule 2B4 Expression Is Associated With Preserved iNKT Cell Phenotype in HIV Long-Term Nonprogressors.

We have previously shown an association of elevated coinhibitory molecule 2B4 expression with iNKT cells alterations in HIV disease. Herein, we show a comparative analysis of 2B4 expression on iNKT cells of HIV long-term nonprogressors (LTNPs) and progressors. Antiretroviral therapy-naive HIV-seropositive individuals (progressors, n = 16) and LTNPs (n = 10) were recruited for this study. We used multicolor flow cytometry on frozen peripheral blood mononuclear cells to determine iNKT subset frequencies, the levels of coinhibitory 2B4 expression, and intracellular interferon-γ (IFN-γ) production. CD1d tetramer was used to characterize iNKT cells. We report significantly lower level of 2B4 expression on bulk LTNPs iNKT cells and on their CD4 subsets compared with HIV progressors. Furthermore, the iNKT cells from LTNPs produced higher amount of IFN-γ than HIV progressors as detected by intracellular cytokine staining. Interestingly, the frequency of 2B4iNKT cells of progressors but not LTNPs significantly correlates with CD4 T-cell count, HIV viral load, and IFN-γ production by iNKT cells. Our results suggest that in addition to suppressed HIV replication, diminished 2B4 expression and associated coinhibitory signaling, and substantial production of IFN-γ could contribute to preserved iNKT cell phenotype in LTNPs.

Injection of CD40 DNA vaccine ameliorates the autoimmune pathology of non-obese diabetic mice with Sjögren’s syndrome

BackgroundOverexpression of CD40 has been reported in patients with primary Sjögren’s syndrome (pSS). The increased CD40 expression promote autoimmune response and enhance inflammation in pSS. The aim of this study is to block CD40-CD154 interaction with CD40 DNA vaccine to slow the disease progression of SS in non-obese diabetic (NOD) mice. MethodsFemale NOD mice were treated with CD40 DNA vaccine, empty vector and normal saline. The salivary flow rate was measured, whereas lymphocytes infiltration in the salivary glands was assessed by histopathology. Expression of CD40 and B220 in salivary were examined by immunohistochemistry. Splenic lymphocyte phenotypes were analyzed by flow cytometry. CD40, IL-1β, TNF-α and IL-6 levels in the salivary glands were detected by PCR. Serum anti-CD40 antibody was measured by ELISA. Serum anti-nuclear antibody (ANA) was monitored by immunofluorescence. ResultsNOD mice treated with CD40 DNA vaccine showed higher levels of anti-CD40 antibody compared with the controls. The expression of CD40 in the salivary glands of NOD mice in CD40 DNA vaccine group was decreased. The infiltration of lymphocytes was reduced in the salivary glands and saliva secretion was increased in the treatment group. The expression level of TNF-α and IL-6 in salivary glands were declined. The splenic dendritic cell and plasma cell populations were reduced and the level of ANA was decreased in NOD mice with CD40 DNA vaccine treatment. ConclusionsCD40 DNA vaccine inhibits the immune response and reduce inflammation in epithelial tissues SS in non-obese diabetic (NOD) mice, suggesting that CD40 DNA vaccine could be a new therapeutic approach in treatment of pSS.

Discovery of CD80 and CD86 as recent activation markers on regulatory T cells by protein-RNA single-cell analysis

BackgroundTraditionally, the transcriptomic and proteomic characterisation of CD4+ T cells at the single-cell level has been performed by two largely exclusive types of technologies: single-cell RNA sequencing (scRNA-seq) and antibody-based cytometry. Here, we present a multi-omics approach allowing the simultaneous targeted quantification of mRNA and protein expression in single cells and investigate its performance to dissect the heterogeneity of human immune cell populations.MethodsWe have quantified the single-cell expression of 397 genes at the mRNA level and up to 68 proteins using oligo-conjugated antibodies (AbSeq) in 43,656 primary CD4+ T cells isolated from the blood and 31,907 CD45+ cells isolated from the blood and matched duodenal biopsies. We explored the sensitivity of this targeted scRNA-seq approach to dissect the heterogeneity of human immune cell populations and identify trajectories of functional T cell differentiation.ResultsWe provide a high-resolution map of human primary CD4+ T cells and identify precise trajectories of Th1, Th17 and regulatory T cell (Treg) differentiation in the blood and tissue. The sensitivity provided by this multi-omics approach identified the expression of the B7 molecules CD80 and CD86 on the surface of CD4+ Tregs, and we further demonstrated that B7 expression has the potential to identify recently activated T cells in circulation. Moreover, we identified a rare subset of CCR9+ T cells in the blood with tissue-homing properties and expression of several immune checkpoint molecules, suggestive of a regulatory function.ConclusionsThe transcriptomic and proteomic hybrid technology described in this study provides a cost-effective solution to dissect the heterogeneity of immune cell populations at extremely high resolution. Unexpectedly, CD80 and CD86, normally expressed on antigen-presenting cells, were detected on a subset of activated Tregs, indicating a role for these co-stimulatory molecules in regulating the dynamics of CD4+ T cell responses.

Profiling of Human Circulating Dendritic Cells and Monocyte Subsets Discriminates Between Type and Mucosal Status in Patients With Inflammatory Bowel Disease.

Intestinal dendritic cells (DC) and macrophages drive disease progression in patients with inflammatory bowel disease (IBD). We aimed to characterize the activation and homing profile of human circulating DC and monocyte subsets in healthy control patients (CP) and IBD patients. Eighteen CP and 64 patients with IBD were categorized by diagnoses of Crohn disease (CD) and ulcerative colitis (UC), either endoscopically active (inflamed) or quiescent. Circulating type 1 conventional DC, type 2 conventional DC, plasmacytoid DC, classical monocytes, nonclassical monocytes, and intermediate monocytes were identified by flow cytometry in each individual and characterized for the expression of 18 markers. Association between DC/monocytes and IBD risk was tested by logistic regression. Discriminant canonical analyses were performed to classify the patients in their own endoscopy category considering all markers on each subset. CCRL1, CCR3, and CCR5 expression on circulating type 1 DC; CCRL1 expression on nonclassical monocytes; and CCR9 and β7 expression on classical monocytes allowed us to discriminate among the different study groups. Indeed, the same markers (excluding β7) were also associated with IBD when all DC and monocyte subsets were considered at the same time. Monitoring the phenotype of human circulating DC and monocyte subsets may provide novel tools as biomarkers for disease diagnosis (CD/UC) or mucosal status (inflamed/noninflamed) in the absence of an invasive colonoscopy.

Regulation of Hox and ParaHox genes by perfluorochemicals in mouse liver

Homeobox (Hox) genes encode homeodomain proteins, which play important roles in the development and morphological diversification of organisms including plants and animals. Perfluorinated chemicals (PFCs), which are well recognized industrial pollutants and universally detected in human and wildlife, interfere with animal development. In addition, PFCs produce a number of hepatic adverse effects, such as hepatomegaly and dyslipidemia. Homeodomain proteins profoundly contribute to liver regeneration. Hox genes serve as either oncogenes or tumor suppressor genes during target organ carcinogenesis. However, to date, no study investigated whether PFCs regulate expression of Hox genes. This study was designed to determine the regulation of Hox (including Hox-a to -d subfamily members) and paraHox [including GS homeobox (Gsx), pancreatic and duodenal homeobox (Pdx), and caudal-related homeobox (Cdx) family members] genes by PFCs including perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) in mouse liver. 46.4 mg/kg PFNA induced mRNA expression of Hoxa5, b7, c5, d10 and Pdx1 in wild-type and CAR-null mouse livers, but not in PPARα-null mouse livers, indicating a PPARα-dependent manner. PFOA, PFNA, and PFDA all induced mRNA expression of Hoxa5, b7, c5, d10, Pdx1 and Zeb2 in wild-type but not PPARα-null mouse livers. In addition, in Nrf2-null mouse livers, PFNA continued to increase mRNA expression of Hoxa5 and Pdx1, but not Hoxb7, c5 or d10. Furthermore, Wy14643, a classical PPARα agonist, induced mRNA expression of Hoxb7 and c5 in wild-type but not PPARα-null mouse livers. However, Wy14643 did not induce mRNA expression of Hoxa5, d10 or Pdx1 in either wild-type or PPARα-null mouse livers. TCPOBOP, a classical mouse CAR agonist, increased mRNA expression of Hoxb7, c5 and d10 but not Hoxa5 or Pdx1 in mouse livers. Moreover, PFNA decreased cytoplasmic and nuclear Hoxb7 protein levels in mouse livers. However, PFNA increased cytoplasmic Hoxc5 protein level but decreased nuclear Hoxc5 protein level in mouse livers. In conclusion, PFCs induced mRNA expression of several Hox genes such as Hoxb7, c5 and d10, mostly through the activation of PPARα and/or Nrf2 signaling.

Suppression of the CD28/B7 pathway reduces the occurrence and development of myasthenia gravis and cytokine levels

Background Myasthenia gravis (MG) is an antibody-mediated, autoimmune neuromuscular disease. Reports have indicated that the CD28/B7 ligand interactions play a crucial role during primary immune responses. Hence, the aim of the present study was to investigate the possible effects of the CD28/B7 pathway on the occurrence and development of MG and its associated cytokine factors. Methods An experimental autoimmune myasthenia gravis (EAMG) was initially established by immunization of Lewis rats with acetylcholine receptor (AChR) α97-116 peptide. Then the rats were treated with dexamethasone and CTLA4-Ig (used for inhibiting the CD28/B7 pathway). Serum levels of AChR IgG and AChR IgG2b were then detected using ELISA. The clinical features, muscle contraction function, AChR content, expression of CD28, CTLA4, B7.1 and B7.2 in mononuclear cells of peripheral blood and the secretion of cytokines (INF-γ, IL-2, IL-10 and IL-12) in serum of rats were measured. Finally, lymphocyte proliferation upon CTLA4 IgG treatment was examined in vitro. Results Inhibition of the CD28/B7 pathway and dexamethasone were found to significantly improve clinical symptoms of EAMG rats, reduce serum levels of AChR IgG, AChR IgG2b, INF-γ, IL-2, IL-10 and IL-12, the expression of CD28, CTLA4, B7.1 and B7.2 in mononuclear cells of peripheral blood, and enhance muscle contraction function and AChR content in the muscle in vivo. Meanwhile, CTLA4 IgG could abolish the increased lymphocyte proliferation following AChR stimulation in vitro. Conclusion Overall, the suppression of the CD28/B7 pathway by CTLA4-Ig can have the potential to retard the occurrence and development of MG.

Cellular requirements for B7 expression in thymic iNKT cell development

Abstract We had previously shown that the B7-CD28 co-stimulatory pathway is important for thymic iNKT cell development. iNKT cell development is dependent on glycolipid/CD1d complex presented by CD4+ CD8+ double positive thymocytes, with no requirement for CD1d-expression on other cell types, including thymic epithelial cells (TEC), dendritic cells (DC), or B cells. However, the identity of the specific cell type(s) providing B7 co-stimulation for developing thymic iNKT is unknown. Here we have analyzed the cellular requirement for B7 expression utilizing B7 conditional KO approaches. We found that B7 expression on TEC, DC and B cell have essential but redundant roles in supporting thymic iNKT cell development. These results suggest that during thymic iNKT cell development, signal 1 (glycolipid/CD1d-TCR) and signal 2 (B7-CD28) are provided by spatially and temporally distinct cell types and may provide new insight into how co-stimulation can function in immune system development.

Clinical significance of circulating tumor cells and their homeobox gene B7 expression in patients with bone and soft tissue sarcomas

Clinical significance of circulating tumor cells and their homeobox gene B7 expression in patients with bone and soft tissue sarcomas

Expression Regulation of Hox and paraHox Genes by Perfluorochemicals in Mouse Liver

Homeodomain proteins, encoded by Hox genes, play important roles in the development and morphological diversification of organisms. Perfluorochemicals (PFCs), which are persistent environmental pollutants and frequently detected in human blood, interfere with animal development. PFCs produce numerous adverse effects in the liver of research animals, such as hepatomegaly and hepatic dyslipidemia, primarily via activation of peroxisome proliferator‐activated receptors (PPARs) and/or constitutive androstane receptor (CAR). No report shows that PFCs alter the expression of Hox genes. This study was designed to determine the regulation of Hox (including Hox‐a to ‐d subfamily members) and paraHox (including Gsx, Pdx, and Cdx gene family members) gene expression by perfluorochemicals including perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) in mouse liver. A single dose of 0.1 mmole/kg PFOA, PFNA or PFDA was intraperitoneally administered to adult male C57BL/6 wild‐type mice, as well as age‐matched male PPARα‐null and male CAR‐null mice (n=6/genotype/treatment). Four days later, mouse livers were collected and processed. PFNA induced mRNA expression of Hoxa5, b7, c5, c8, and d10 in the livers of wild‐type and CAR‐null mice, but not in PPARα‐null mouse liver, indicating a PPARα‐dependent mechanism. In addition, PFOA, PFNA, and PFDA all induced mRNA expression of Hoxb7, c5, and d10 in wild‐type but not PPARα‐null mouse liver. Furthermore, Wy‐14643, a classical PPARα agonist, induced mRNA expression of Hoxc5 in wild‐type but not PPARα‐null mice. However, Wy‐14643 did not alter mRNA expression of Hoxa5, b7 or d10 in either wild‐type or PPARα‐null mouse liver. TCPOBOP, a classical CAR agonist, did not alter mRNA expression of Hoxa5, b7, c5 or d10 in mouse liver. Moreover, PFNA increased cytoplasmic levels of Hoxc5 protein in mouse liver. In conclusion, perfluorochemicals induced the expression of certain Hox genes such as Hoxc5, mainly via PPARα activation.

B7-Positive and B7-Negative Acute Myeloid Leukemias Display Distinct T Cell Maturation Profiles, Immune Checkpoint Receptor Expression, and European Leukemia Net Risk Profiles.

Acute myeloid leukemia (AML) is generally considered a poorly immunogenic malignancy, displaying a “non-inflamed” leukemia microenvironment (LME), leading to T cell tolerance. However, the immune landscape of AML is much more heterogeneous. Since B7 expression is regarded as a consequence of an interferon-mediated “inflammatory” phenotype, we have investigated by flow cytometry the B7 checkpoint ligands B7.1, B7.2, programmed death ligand 1 (PD-L1), PD-L2, ICOS-L, B7-H3, and B7-H4 on the AML blasts of 30 newly diagnosed patients and their corresponding receptors [cytotoxic T lymphocyte-associated protein 4 (CTLA-4), programmed death 1 (PD-1), and inducible T cell costimulator (ICOS)] on bone marrow (BM) T cell maturation populations. We could thus evidence B7-negative and B7-positive leukemias either with an isolated expression or part of eight different checkpoint ligand “signatures” that always included an inhibitory B7 molecule. B7-positive AMLs encompassed intermediate and adverse European Leukemia Net (ELN) risk cases and displayed mainly central memory CD4+ T cells with high ICOS levels and effector CD8+ T cells with high PD-1 expression. B7-negative cases were rather classified as AML with recurrent genetic anomalies and displayed predominantly naive T cells, with the exception of NPM1 mutated AMLs, which expressed B7-H3. These different B7 immune profiles suggest that specific immunotherapies are required to target the distinct immune evasion strategies of this genetically heterogeneous disease.

Abstract P3-09-12: Peripheral T cell clonality and exhaustion as novel biomarkers for anti-PD-1 (pembrolizumab) maintenance therapy in patients with metastatic inflammatory breast cancer (mIBC) and non-IBC triple negative breast cancer (mTNBC)

Abstract Background: Inflammatory breast cancer (IBC) and triple negative breast cancer (TNBC) are more aggressive than other breast cancer subtypes, and up until recently lacked therapy options that maintain acceptable quality of life. While chemotherapy is a treatment option for all subtypes of breast cancer, it is used long-term as maintenance therapy for metastatic TNBC (mTNBC) and often produces cumulative toxicity resulting in discontinuation of treatment. Moreover, responses are rarely durable after discontinuation of chemotherapy. Immune checkpoint blockade has the potential to maintain therapy. To determine factors associated with response to anti-PD-1 therapy (pembrolizumab), we performed minimally invasive blood-based analyses of T-cell repertoire and phenotype to evaluate their association with progression-free survival (PFS) in 15 patients with metastatic IBC (mIBC) or mTNBC. Materials and Methods: Fifteen patients with mIBC (n=6) or mTNBC (n=9) were enrolled on an ongoing phase II study to receive pembrolizumab as maintenance therapy after achieving a clinical response or stable disease to systemic chemotherapy for metastatic disease. We performed analyses of T-cell repertoire and phenotype on peripheral blood mononuclear cells (PBMC) from samples obtained post induction therapy but before initiation of pembrolizumab (baseline) therapy. Expression of T-cell exhaustion markers 2B4, CTLA4, BTLA, Lag3, PD-1, and Tim3 was evaluated on PBMC by flow cytometry. T-cell receptor (TCR) beta chain CDR3 DNA sequencing by ImmunoSEQ and richness (diversity) and clonality (reactivity) were evaluated. Patients were followed through 5 months of treatment with pembrolizumab to evaluate the association between T-cell repertoire and phenotype with PFS. Results: Seven patients had stable disease (SD) and 8 had progressive disease (PD) by 5 months. The median follow-up was 14.2 months (range: 4.5 to 27.7 months). Among the patients who progressed within 5 months, the earliest and the latest time to progression was at 1.38 months and 4.82 months, respectively. CTLA4 expression in CD4+ T cells at baseline was significantly higher in patients with PD than in patients with SD (p = 0.040). Patients with a low percentage of CD4+ T cells expressing exhaustion markers (CTLA4, Tim3, and 2B4) at baseline were more likely to have SD (chi-square p = 0.041) and significantly longer median PFS than patients with PD (median time to progression was not reached in SD vs. 4.1 months in PD, p = 0.018). Additionally, patients with high clonality and low CD4+ T exhaustion markers were more likely to have SD (chi-square p = 0.041) and a longer median time to progression (median time to progression was not reached in SD vs. 4.1 months in PD, p = 0.015). Conclusions: Baseline T-cell clonality and T-cell exhaustion markers have significant translational relevance and can help to explain variable responses to immune checkpoint blockade. Our data suggest that T-cell reactivity at baseline, and a lower percentage of CD4+ T cells expressing CTLA4/Tim3/2B4 were favorable prognostic factors for pembrolizumab maintenance therapy. This proof-of-concept provides compelling data that T-cell clonality and phenotyping of T-cell exhaustion markers can be useful and should be applied to future trials with immune checkpoint inhibitors. Citation Format: Hui Gao, Kumiko Kida, Evan N Cohen, Angela Alexander, Bora Lim, Charla Parker, Sanda Tin, Vicente Valero, Debu Tripathy, Alexandre Reuben, Naoto T Ueno, James M Reuben. Peripheral T cell clonality and exhaustion as novel biomarkers for anti-PD-1 (pembrolizumab) maintenance therapy in patients with metastatic inflammatory breast cancer (mIBC) and non-IBC triple negative breast cancer (mTNBC) [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-09-12.

Genetic loss of NFAT2 (NFATc1) impairs B cell development of B1 and B2 B cells

NFAT2 activity was shown to be of critical importance in B cell receptor signaling, development and proliferation; however its role in B cell development in the periphery is still not completely understood. We confirmed that NFAT2 deletion leads to impaired B1 B cell development, supported by our finding of limited B1 progenitors in the bone marrow and spleen of NFAT2 deficient mice. Moreover, we show for the first time that loss of NFAT2 increases immature B cells in particular transitional T2 and T3 as well as mature follicular B cells while marginal zone B cells are decreased. We further demonstrate that NFAT2 regulates the expression of B220, CD23, CD38, IgM/IgD and ZAP70 in murine B cells. In vivo analyses revealed decreased proliferation and increased apoptosis of NFAT2 deficient B cells. In summary, this study provides an extensive analysis of the role of NFAT2 in peripheral B lymphocyte development.

P004 PN-943, an oral α4β7 integrin antagonist, inhibits MAdCAM1-mediated proliferation and cytokine release from CD4+ T cells independent of trafficking

Abstract Background PN-943, an oral gastrointestinal (GI) -restricted peptide antagonist of α4β7 integrin, is being developed for the treatment of inflammatory bowel disease (IBD). Blockade of α4β7 binding to mucosal addressin cell adhesion molecule-1 (MAdCAM1) is thought to treat IBD by preventing extravascular migration of blood T cells into the inflamed GI mucosa. Recent evidence suggests the involvement of other mechanisms. Saturation of circulating T-cell α4β7 by vedolizumab is not sufficient for optimal efficacy; and PTG-100, a PN-943 analogue, showed evidence of clinical and histological remission in ulcerative colitis patients at sub-saturating blood receptor occupancy (%RO). Here, we assessed the potential of a local GI-acting function of α4β7 by evaluating the ability of PN-943 to inhibit MAdCAM1-mediated CD4+ T-cell proliferation and cytokine production. Methods Primary CD4+ T cells were labelled fluorescently and incubated with plate-bound anti-CD3 alone or together with MAdCAM1 with or without inhibitors for three days. Phenotype, distribution of T-helper (Th) subsets and %RO analyses were conducted by flow cytometry. Supernatant cytokine levels were quantified by multiplex assays. Results MAdCAM1 combined with anti-CD3 markedly enhanced proliferation of CD4+ T cells compared with anti-CD3 alone (n = 7, 12–64%). Immune phenotyping revealed that proliferation occurred in both CD45RO- naïve and CD45RO+ memory T cells and was restricted to the β7+ population with successive cycles of proliferation showing increased β7 expression. Amongst the proliferated memory T cells, the percentage of the IFNγ-producing Th1 subset was higher than IL-17A-producing Th17 and IL-4-producing Th2 subsets. Multiplex profiling identified several cytokines, including but not limited to IL-6, IL-13, GM-CSF, and TNFα, whose release were promoted by MAdCAM1. PN-943 abolished MAdCAM1-mediated stimulation (n = 4, IC50 4.6 nM). The inhibitory effects were associated with lowered β7 expression indicative of internalisation by PN-943. Blockade was not observed with an inactive analogue indicating dependency on PN-943 binding to α4β7. Consistent with the requirement for a locally acting drug, 30 mg/kg oral dosing in mice demonstrated high exposure (n = 6, 39 nM) and occupancy of T-cell α4β7 (n = 6, 92%) in the GI compared within the blood. Conclusion The α4β7-MAdCAM1 interaction promoted β7+CD4+ T-cell proliferation and cytokine release, which may contribute to chronic inflammatory responses occurring in the diseased gut of IBD patients independent of T-cell trafficking. PN-943 inhibition of MAdCAM1-mediated signalling through α4β7 supports the potential therapeutic advantages for an oral GI-restricted approach, whereby PN-943 is delivered locally and directly blocks α4β7 function in the GI.

P045 Profiling of human circulating dendritic cells and monocytes subsets discriminates type and mucosal status in patients with inflammatory bowel disease

Abstract Background Intestinal dendritic cells (DCs) and macrophages govern the mechanisms of immune homeostasis having a role in inflammatory bowel disease (IBD) onset. However, the profile of their circulating precursors (DC and monocytes) in IBD has not been previously described in depth. Our aim was to characterise blood DC and monocyte subsets in healthy controls (HCs) and IBD patients in order to understand their potential implication in IBD pathogenesis. Methods 18 HC and 64 IBD patients were recruited. IBD patients were categorised into Crohn’s disease (CD) and ulcerative colitis (UC), either endoscopically active (aCD and aUC) or quiescent (qCD and qUC), based on the SES-CD or the Mayo index endoscopic subscore. Blood circulating type 1 conventional DC (cDC1), type 2 conventional DC (cDC2), plasmacytoid DC (pDC), classical monocytes, non-classical monocytes and intermediate monocytes were identified by flow cytometry and characterised for the expression of 18 homing and activation markers (β7, CCR1, CCR2, CCR3, CCR5, CCR6, CCR7, CCR9, CCRL1, CD40, CD86, CD137L, CD274 (PD-L1), CLA, CXCR1, CXCR3, ICOSL and HLA-DR). Association between markers and the presence, type or activity of IBD was tested by logistic regression. Discriminant canonical analysis was also performed to classify the patients on their own endoscopy category. Results All groups (HC, aCD, qCD, aUC and qUC) were separated from the others based on the discriminant canonical analyses of the 18 markers applied over all DC and monocytes subsets (Figure 1). Specifically, CCRL1, CCR3 and CCR5 expression on cDC1, CCRL1 on non-classical monocytes and CCR9 and b7 on classical monocytes were highly associated to IBD. CCR3 displayed an odds ratio (OR) of 2.29 along with its 95% confidential interval (CI) between 1.11 and 4.75, showing a strong association with activity in CD; whereas the other markers displayed an inverse association with IBD. Hence, expression of CCRL1 on cDC1 and non-classical monocytes from aUC showed an OR (95% CI) of 0.23 (0.08–0.66) and 0.52 (0.28–0.95), respectively. In the case of qUC, CCR5 on cDC1 and β7 on classical monocytes displayed an OR (95% CI) of 0.10 (0.01–0.83) and 0.56 (0.34–0.90), respectively. CCR9 was inversely associated to qCD with an OR (95% CI) of 0.64 (0.46–0.89) in the classical monocytes subset. Indeed, the same markers (excluding β7) were also associated with IBD when all DC and monocyte subsets were considered at the same time. Conclusion Differences on the expression of migration markers CCR3, CCR5, CCR9, b7 and decoy receptor CCRL1 on circulating DC and monocyte subsets from IBD groups suggest the presence of constitutive migratory differences underlying IBD pathogenesis in CD or UC and its condition (inflamed or non-inflamed).

B220 expression as an immunological marker for differentiation of Feline Leukemia Virus carrying cats

ABSTRACT: Feline leukemia virus (FeLV) causes an infection in cats that, in some cases, can also be reported with other pathologies, such as infection with feline immunodeficiency virus (FIV), feline infectious peritonitis (FIP), and lymphoma. Although, a compromised immune response is reported in these animals, little is known about the immunological state of their cells. To shed some light in this area, we studied peripheral blood samples from both infected and non-infected cats with FeLV, with or without FIV, FIP, and lymphoma. We tested a panel of monoclonal antibodies (n=11) against mouse and human antigens and we reported that cat leukocytes can be stained with anti-mouse B220 monoclonal antibody; therefore, percentages of B cells were evaluated in different cat groups. Our results showed that cats with FeLV and FIP, or with leukemia, presented a large decrease in B220+ mononuclear cells. However, FeLV+ cats without clinical signs, or with unspecific clinical signs, had the same amount of B220+ mononuclear cells as healthy cats (control cats). Since the expression of B220 is exclusively restricted to the naïve B cell population, we inferred that the absence of these B cells in FeLV+ cats is related to other conditions that affect B cell numbers, such as viral infections and leukemias. Therefore, the amount of naïve B cells in peripheral blood (i.e., B220+ cells) can be used to identify FeLV+ cats concomitantly carrying FIP or leukemia, from FeLV+ cats with lymphoma or without any clinical signs.

Immune Landscape of the B7 and TNFR Families in Oral Squamous Cell Carcinoma.

To understand the immune molecular landscapes of the two major costimulatory and coinhibitory pathways (B7 and TNFR families) in oral squamous cell carcinoma. The B7 family members (CD80, CD86, CD274, ICOSLG, CD276, VTCN1, NCR3LG1, HHLA2 and PDCD1LG2) and TNFR family members (TNFSF4, CD40, CD70, TNFSF9, TNFRSF14 and TNFSF18) were used to analyse the costimulatory and coinhibitory pathway alterations in oral squamous cell carcinoma. The online tools UCSC Xena and cBioPortal were used to derive oral squamous cell carcinoma patients' clinical parameters, mRNA levels, mutations, DNA copy number alterations and methylation levels. The correlations between mRNA levels and methylation levels were determined using Spearman's correlation analysis. A Kaplan-Meier survival analysis was performed to examine the relationships between mRNA expression levels and overall survival. Compared with normal oral epithelial tissues, approximately 23.1% of patients showed upregulation of B7 expression and 15.3% showed upregulation of TNFR expression in oral squamous cell carcinoma, with CD274 (PD-L1) upregulation being the most common alteration. Mutations and copy number alterations were shown to have little effect on B7 and TNFR expression. The mRNA levels of B7 and TNFR genes were negatively correlated with their methylation levels. Furthermore, oral squamous cell carcinoma patients with high expression levels of CD274 showed poor overall survival, while those with high expression levels of CD276 or HHLA2 showed good clinical outcomes. This study elucidated the molecular landscapes of the B7 and TNFR genes in oral squamous cell carcinoma, which could provide a novel strategy for clinical therapy.