Development of a novel monoclonal antibody that binds to most HLA-A allomorphs in a conformation-dependent yet peptide-promiscuous fashion.

Specificity analyses of peptide binding to human leukocyte antigen (HLA)-A molecules have been hampered due to a lack of proper monoclonal antibodies (mAbs) for certain allomorphs, such as the prevalent HLA-A1 for Caucasians and HLA-A11 for Asians. We developed a mAb that recognizes a conformational epitope common to most HLA-A allomorphs. The mAb, named A-1, does not discriminate peptides by amino acid sequences, making it suitable for measuring peptide binding. A stabilization assay using TAP-deficient cell lines and A-1 was developed to investigate the specificity of peptide binding to HLA-A molecules. Regarding the evolution of HLA-A genes, the A-1 epitope has been conserved among most HLA-A allomorphs but was lost when the HLA-A gene diversified into the HLA-A*32, HLA-A*31, and HLA-A*33 lineages together with HLA-A*29 after bifurcating from the HLA-A*25 and HLA-A*26 branchs. The establishment of A-1 is expected to help researchers investigate the peptide repertoire and develop computational tools to identify cognate peptides. Since no HLA-A locus-specific mAb has been available, A-1 will also be useful for analyzing the locus-specific regulation of the HLA gene expression.

Stat3 activation in epidermal keratinocytes induces Langerhans cell activation to form an essential circuit for psoriasis via IL-23 production.

BACKGROUND: Psoriasis is an inflammatory disease associated with aberrant crosstalk between the epidermis and immune system. However, the role of Langerhans cells (LCs) in psoriasis remains controversial. OBJECTIVES: To elucidate whether LCs are functionally involved in the development of psoriasis using a mouse model. METHODS: Two lines of transgenic mice were used and crossed. They included K5.Stat3C, the psoriasis-model mouse and langerin DTR knock-in (KI) mouse. We performed immunofluorescence staining for LCs in psoriatic lesion of human and model mice. Flow cytometric analyses were performed to compare between dendritic cells (DCs) and LCs in the epidermis and skin-draining lymph nodes (sDLNs). To assess cytokine/chemokine expression in the skin lesion or primary cultured keratinocytes, we performed RT-PCR, microarray analysis or intracellular staining on the flow cytometer. RESULTS: LCs were activated in psoriatic lesion of patients with psoriasis and K5.Stat3C mice. Compared with non-transgenic mice, K5.Stat3C mice constitutively showed an increased number of LCs in the sDLNs before psoriasis-like lesion developed. Stat3C transgenic keratinocytes expressed an elevated level of IL-1α. Psoriasis-like lesion in K5.Stat3C mice were attenuated in the absence of LCs, indicating that LCs were essential to the development of psoriasis-like lesion. Furthermore, we also recognized that epidermal LCs in psoriatic lesion of not only K5.Stat3C mice but also psoriasis patients produced IL-23. CONCLUSIONS: Our study suggests that Stat3 activation in keratinocytes may impact on LC activation in situ via IL-1α stimulation, at least in part, and that their presence may be essential for the pathogenesis of psoriasis through producing IL-23.

Use of intralesional blood to determine diffusible biomarkers from skin lesions.

BACKGROUND: Biomarkers provide beneficial information to make diagnoses and monitor the progression of many skin diseases. However, biomarkers produced by skin lesion may be too low at concentration to be detected in the systemic circulation. OBJECTIVE: To address whether intralesional blood (ILB) is advantageous to detect skin-derived biomarkers over circulation blood (CB) of patients with skin diseases. METHODS: ILB was collected as overflowing blood when a small incision was made in lesions of patients with mastocytoma and psoriasis. Concentrations of histamine and Human ß-Defensin 2 were determined by ELISA. IL-8 was measured using a cytometric beads array (CBA) kit. IL-8 levels in psoriatic lesions were assessed by immunohistochemical staining and quantitative (q) RT-PCR. MicroRNA levels were measured using qRT-PCR. RESULTS: Plasma histamine levels were increased in ILB of mastocytoma compared with those in CB. Patients with psoriasis showed increased levels of IL-8, ß-Defensin 2 in ILB as compared to those in CB. IL-8 levels in ILB correlated with local PASI scores and therefore reversed to those in CB after attenuation of psoriasis with treatment. Furthermore, ILB in psoriasis patients showed increased miR-203, which was highly expressed in psoriatic epidermis. CONCLUSION: ILB contains disease-specific biomarkers at higher concentrations than those in CB, and may be useful for diagnosis and monitoring the progression of skin diseases. Thus, this study illustrates the versatility of ILB with an easy accessibility of biomarkers of chemicals, proteins as well as nucleic acids for a myriad of diseases including inflammatory dermatoses and cancers.

Psoriatic inflammation facilitates the onset of arthritis in a mouse model.

Psoriatic arthritis (PsA) is a seronegative, inflammatory joint disease associated with psoriasis. In most patients with PsA, skin lesions precede arthritis; however, the causality of skin inflammation for the development of arthritis remains unclear. Gp130F759/F759 knock-in (F759) mice develop autoimmune arthritis after 1 year of age through persistent signal transducer and activator of transcription 3 (Stat3) activation due to impairment in SOCS3-dependent negative regulation. Here, we crossed F759 mice with K5.Stat3C transgenic mice, in which keratinocytes express constitutive active Stat3 (Stat3C), leading to generation of psoriasis-like skin change. F759 mice harboring the K5.Stat3C transgene not only had aggravated skin lesions but also spontaneously developed arthritis with high penetrance in adjacent paws as early as 3 weeks of age. The joint lesions included swelling of the peripheral paws and nail deformities contiguous with the skin lesions, closely resembling PsA. Histopathologic study revealed enthesitis and bone erosions, with mononuclear cell infiltrates. Quantitative reverse transcriptase-PCR (RT-PCR), immunohistochemical analyses, and flow cytometry showed upregulation of the IL-23/T helper type 17 (Th17) pathway in affected joints. Furthermore, enforced generation of psoriasis-like skin inflammation by topical treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) in F759 mice induced swelling of the underlying joints. This animal model renders psoriatic inflammation as the driver of arthritis and helps to further understand the pathogenesis of PsA.

Epicutaneous application of toll-like receptor 7 agonists leads to systemic autoimmunity in wild-type mice: a new model of systemic Lupus erythematosus.

OBJECTIVE: To examine whether topical treatment of wild-type mice with Toll-like receptor 7 (TLR-7) agonists leads to lupus-like autoimmunity. METHODS: Wild-type FVB/N, BALB/c, and C57BL/6 mice were treated with the topical TLR-7 agonist imiquimod or R848 administered to the ear 3 times weekly. During treatment, the mice were monitored for serum autoantibody and creatinine levels as well as histopathology of the kidneys, spleens, livers, hearts, and skin. Immunologic abnormalities were analyzed by immunohistochemistry, quantitative reverse transcription-polymerase chain reaction, and fluorescence-activated cell sorting. The role of plasmacytoid dendritic cells (PDCs) in the development of autoimmune disease was validated by in vivo treatment with an anti-PDC antibody. Diseased mice underwent ultraviolet B irradiation, to evaluate skin photosensitivity. The disease-causing effect of topical application of imiquimod was compared with that of systemic (intraperitoneal) administration. TLR-7- and TLR-9-deficient mice were used to validate the role of TLR-7. RESULTS: Wild-type mice of different genetic backgrounds developed systemic autoimmune disease following 4 weeks of topical treatment with imiquimod or R848, with elevated levels of autoantibodies to double-stranded DNA and multiple organ involvement, including glomerulonephritis, hepatitis, carditis, and photosensitivity. Expression of Ifna and Mx1, the interferon-α-stimulated gene, was up-regulated in the organs of imiquimod-treated mice. However, disease caused by intraperitoneal injection of imiquimod was less severe than that induced by topical application. In vivo depletion of PDCs by a specific antibody protected mice against the autoimmunity induced by topical administration of imiquimod, suggesting a role of PDCs. Furthermore, TLR-7-deficient mice, but not TLR-9-deficient mice, were protected against autoimmunity. CONCLUSION: This protocol provides a novel model of inducible systemic lupus erythematosus in wild-type mice and underscores the skin as the primary organ that allows TLR-7 agonists to induce SLE.

CD82 regulates STAT5/IL-10 and supports survival of acute myelogenous leukemia cells.

We recently reported that adhesion molecule CD82 is aberrantly expressed in CD34(+) /CD38(-) leukemia stem cells (LSCs). Here, we report the results of a functional analysis of CD82 in CD34(+) /CD38(-) acute myelogenous leukemia (AML) cells. Short hairpin (sh)RNA-mediated downregulation of CD82 resulted in a decrease in the level of IL-10. In contrast, forced expression of CD82 in CD34(+)/CD38(+) AML cells by transduction with CD82-expressing lentiviral particles resulted in an increase in the levels of IL-10. Notably, exposure of CD34(+)/CD38(-) AML cells to IL-10 stimulated clonogenic growth of these cells. Moreover, downregulation of CD82 by a shRNA dephosphorylated STAT5 in CD34(+)/CD38(-) AML cells. On the other hand, forced expression of CD82 resulted in increase in the levels of p-STAT5 in CD34(+)/CD38(+) AML cells. Chromatin immunoprecipitation (ChIP) assay results indicated that STAT5A binds to the promoter region of the IL-10 gene, while reporter gene assay results indicated stimulation of IL-10 expression at the transcriptional level. These results suggest that CD82 positively regulates the STAT5/IL-10 signaling pathway. Moreover, shRNA-mediated downregulation of CD82 expression in CD34(+)/CD38(-) AML cells dephosphorylated STAT5 in immunodeficient mice. Taken together, our data suggest that the CD82/STAT5/IL-10 signaling pathway is involved in the survival of CD34(+)/CD38(-) AML cells and may thus be a promising therapeutic target for eradication of AML LSCs.

Barrier abnormality due to ceramide deficiency leads to psoriasiform inflammation in a mouse model.

It has been recognized that ceramides are decreased in the epidermis of patients with psoriasis and atopic dermatitis. Here, we generated Sptlc2 (serine palmitoyltransferase long-chain base subunit 2)-targeted mice (SPT-cKO mice), thereby knocking out serine palmitoyltransferase (SPT), the critical enzyme for ceramide biosynthesis, in keratinocytes. SPT-cKO mice showed decreased ceramide levels in the epidermis, which impaired water-holding capacity and barrier function. From 2 weeks of age, they developed skin lesions with histological aberrations including hyperkeratosis, acanthosis, loss of the granular layer, and inflammatory cell infiltrates. Epidermal Langerhans cells showed persistent activation and enhanced migration to lymph nodes. Skin lesions showed upregulation of psoriasis-associated genes, such as IL-17A, IL-17F, IL-22, S100A8, S100A9, and ß-defensins. In the skin lesions and draining lymph nodes, there were increased numbers of γδ T cells that produced IL-17 (γδ-17 cells), most of which also produced IL-22, as do Th17 cells. Furthermore, IL-23-producing CD11c(+) cells were observed in the lesions. In vivo treatment of SPT-cKO mice with an anti-IL-12/23p40 antibody ameliorated the skin lesions and reduced the numbers of γδ-17 cells. Therefore, we conclude that a ceramide deficiency in the epidermis leads to psoriasis-like lesions in mice, probably mediated by IL-23-dependent IL-22-producing γδ-17 cells.

CD34⁺/CD38⁻ acute myelogenous leukemia cells aberrantly express CD82 which regulates adhesion and survival of leukemia stem cells.

To identify molecular targets in leukemia stem cells (LSCs), this study compared the protein expression profile of freshly isolated CD34(+) /CD38(-) cells with that of CD34(+) /CD38(+) counterparts from individuals with acute myelogenous leukemia (n = 2, AML) using isobaric tags for relative and absolute quantitation (iTRAQ). A total of 98 proteins were overexpressed, while six proteins were underexpressed in CD34(+) /CD38(-) AML cells compared with their CD34(+) /CD38(+) counterparts. Proteins overexpressed in CD34(+) /CD38(-) AML cells included a number of proteins involved in DNA repair, cell cycle arrest, gland differentiation, antiapoptosis, adhesion, and drug resistance. Aberrant expression of CD82, a family of adhesion molecules, in CD34(+) /CD38(-) AML cells was noted in additional clinical samples (n = 12) by flow cytometry. Importantly, down-regulation of CD82 in CD34(+) /CD38(-) AML cells by a short hairpin RNA (shRNA) inhibited adhesion to fibronectin via up-regulation of matrix metalloproteinases 9 (MMP9) and colony forming ability of these cells as assessed by transwell assay, real-time RT-PCR, and colony forming assay, respectively. Moreover, we found that down-regulation of CD82 in CD34(+) /CD38(-) AML cells by an shRNA significantly impaired engraftment of these cells in severely immunocompromised mice. Taken together, aberrant expression of CD82 might play a role in adhesion of LSCs to bone marrow microenvironment and survival of LSCs. CD82 could be an attractive molecular target to eradicate LSCs.

Identification of CTL epitopes in hepatitis C virus by a genome-wide computational scanning and a rational design of peptide vaccine.

Developing a peptide-based vaccine for the highly variable hepatitis C virus (HCV) remains a challenging task. Variant viruses not only escape antigen presentation but also persist in a patient as quasi-species. Such variants are often antagonistic to the responding T cell repertoire. To overcome these problems, we herein propose a cocktail vaccine consisting of a few epitope peptides, which make it possible to outpace the emergence of variant viruses. To design such a vaccine, we developed a way to identify HLA-A*2402-binding peptides efficiently by means of the computational scanning of the whole genome of the pathogen. Most of the predicted peptides exhibited strong binding to the HLA-A*2402 molecule, while also inducing CD8 T cell responses from the patients' peripheral blood mononuclear cells (PBMCs). Peptide-induced T cells were capable of lysing HCV-expressing HepG2 cells which process antigens endogenously. The amount of HCV core antigen in the patients' livers suggested that the lytic activity of the peptide-induced T cells was clearly in a range suitable for therapeutic use. If T cells were activated under optimal conditions by high density peptides, then they tended to be relatively tolerant of single amino acid variations for cytolysis. Finally, an analysis of the viral population isolated in Japan suggested no obvious changes due to immune evasion in the viral genome even in a host population highly biased toward HLA-A*2402.

Serum level of soluble CD30 correlates with the aggressiveness of adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATL) is a highly aggressive disease with poor prognosis. CD30(+) cells are frequently observed in lymph node cells and peripheral blood mononuclear cells of ATL patients. In order to elicit the role of CD30(+) cells in ATL development, we investigated expression of the membrane type of CD30 (mCD30) and the soluble form of CD30 (sCD30) on ATL cells. Both mCD30 and sCD30 are expressed on various numbers of ATL cells in vivo as well as cell lines such as MT-2, L540 and Karpas 299. The level of serum sCD30 in each clinical stage showed an elevated level in patients with acute type (mean +/- standard error; 545.2 +/- 18.6 U/mL) rather than with lymphoma type ATL (327.62 +/- 94.85 U/mL). In four patients whose sera were stored and examined longitudinally, the levels decreased following the response to chemotherapy but not in patients with chemotherapy resistance. Thus, our results imply that sCD30 levels may be another useful marker for the activity and aggressiveness of ATL.

Antitumor activity of eosinophils activated by IL-5 and eotaxin against hepatocellular carcinoma.

We examined the antitumor effects of eosinophils to explore the potential of eosinophils as effector cells in tumor cytotoxicity. We expressed eotaxin in hepatocellular carcinoma cells, MH134, and injected them into either normal or IL-5 TG mice intradermally and monitored cell growth. In normal mice, growth of MH134 cells containing the expression plasmid pCXN2-eotaxin was similar to that of vector-transfected MH134 cells for a period of 2 weeks, suggesting that expression of eotaxin does not change the growth rate of tumor cells. In IL-5 TG mice, however, the growth of eotaxin expressing MH134 cells was significantly suppressed. LPS induced eosinophils to produce TNF-alpha to kill MH134 cells in vitro. Intratumor injection of LPS is effective to kill MH134-pCXN2 and MH134-pCXN2-eotaxin only in normal mice. Administration of anti-CD4 or anti-CD8 antibodies suppressed growth of MH134-pCXN2-eotaxin cells compared with control antibodies, suggesting that T cells may interfere with immunity against MH134. Administration of anti-IL-5Ralpha and anti-asialo GM1 antibodies enhanced growth of MH134-pCXN2-eotaxin cells, suggesting involvement of eosinophils and NK cells in suppression of tumor cell growth. Although we cannot exclude the possibility that NK cells participate in tumor cell killing in vivo, the presence of NK markers such as DX5, asialo GM1, Ly49, and CD94, and NKG2D on large numbers of eosinophils activated by eotaxin suggests that eosinophils function in such suppression of tumor cell growth. Furthermore, we showed that anti-NKG2D antibodies could significantly inhibit the LPS-induced cytotoxicity against MH134 by highly enriched fraction of eosinophils.

Mitochondrial transmembrane potential is diminished in phorbol myristate acetate-stimulated peritoneal resident macrophages isolated from wild-type mice, but not in those from gp91-phox-deficient mice.

Macrophages produce superoxide (O2-) during phagocytosis or upon stimulation with a variety of agents including phorbol myristate acetate (PMA) through the activation of NADPH oxidase, and the formed O2- is converted to other reactive oxygen species (ROS) such as hydrogen peroxide (H2O2). The aim of the present study was to elucidate the effect of the intracellularly produced ROS on mitochondrial transmembrane potential (MTP) in mouse (C57BL/6) peritoneal resident macrophages stimulated with PMA. Using a fluorescent dye, succinimidyl ester of dichlorodihydrofluorescein (H2DCFDA), O2- was visualized in intracellular compartments in a certain subpopulation of macrophages isolated from wild-type mice. Cells deficient in gp91-phox, one of the membrane components of NADPH oxidase, were negative for the fluorescence. When cells were loaded with both H2DCFDA and MitoCapture, a fluorescent dye for mitochondria, mitochondrial fluorescence was diminished in O2- -producing cells, but not in O2- -deficient cells. Flow cytometry also revealed the decrease of mitochondrial fluorescence in wild-type cells, but not in gp91-phox-deficient cells. The loss of mitochondrial fluorescence was prevented by microinjection of catalase into cells. The present findings demonstrate that MTP is diminished by ROS, including the H2O2 dismutated from O2-, produced intracellularly by activation of the NADPH oxidase in mouse peritoneal resident macrophages stimulated with PMA.

Development and functional analysis of eosinophils from murine embryonic stem cells.

We have established a culture system for the development of eosinophils from murine embryonic stem (ES) cells. After transferring ES cells from embryonic fibroblast cells onto macrophage colony-stimulating factor-deficient stromal cells, OP9, ES cells were cultured in the presence of interleukin (IL)-5 with either IL-3 or granulocyte-macrophage colony stimulating factor (GM-CSF) for 20 d to obtain approximately 50% eosinophils. Electron microscopy confirmed the presence of crystallized major basic protein (MBP) in the granules of some of these cells. Neither IL-5, IL-3, GM-CSF nor eotaxin alone could induce eosinophils as efficiently as the conditions described above. Eotaxin induced eosinophil development in combination with either IL-3 or IL-5. Levels of GATA-1, Friend of GATA (FOG)-1, PU.1, CCAAT/enhancer binding protein (C/EBP)alpha, C/EBPbeta, IL-3 receptor alpha (IL-3Ralpha), GM-CSF receptor alpha (GM-CSFRalpha), and MBP mRNAs were increased in ES cells 10 d after transfer onto OP9 cells. In contrast, C/EBPepsilon, IL-5Ralpha, and eosinophil peroxidase mRNAs were induced in response to IL-3 and IL-5 after transfer onto OP9 cells. Eosinophils that developed in this system expressed Gr-1, F4/80, B220, CCR3, IL-3Ralpha, IL-5Ralpha, and DX5. Finally, eosinophils developed from ES cells produced reactive oxygen species in response to Leishmania as do peripheral blood eosinophils.

Role of apoptosis inhibition in various chondrocyte culture systems.

Apoptosis may limit the utility of cell-based therapies for articular cartilage disorders. We tested the hypothesis that chondrocyte apoptosis can be reduced by optimizing the conditions employed to expand chondrocyte numbers in culture. Chondrocyte apoptosis was examined in monolayer and suspension culture, in the presence of fetal bovine serum (FBS) or autologous serum, and for culture periods of 2 or 4 days. The effect of these variables was assessed by measuring cell viability, Annexin V labeling and mitochondrial membrane potential. After 2 days of culture, the greatest increase in viable cell number (3.7-fold) occurred in monolayer cultures with autologous serum. After 4 days of culture, the greatest increase in cell number (9.0-fold) occurred in monolayer cultures supplemented with FBS. By Annexin V staining, the proportion of cells undergoing apoptosis after 2 days was not affected by the type of serum used or by culture in monolayer versus suspension. After 4 days of culture, the proportion of apoptotic cells was significantly reduced (35% to 13%, p<0.02) in suspension cultures with autologous serum. Apoptosis assessed by loss of mitochondrial membrane potential was decreased in the presence of autologous serum. These data suggest that suspension culture with autologous serum is useful in simultaneously maintaining cell proliferation and minimizing apoptosis in cultured human articular chondrocytes.