Differential isoform expression of Allergin-1 during acute and chronic inflammation

INTRODUCTION

Neutrophils are crucial to antimicrobial defense, but excessive neutrophilic inflammation elicits immune pathology. Currently, no effective treatment exists to curb neutrophil activation. However, neutrophils express a variety of inhibitory receptors which may represent potential therapeutic targets to limit neutrophilic inflammation. Indeed, we previously showed that the inhibitory collagen receptor leukocyte-associated immunoglobulin-like receptor 1 (LAIR-1) regulates neutrophilic airway inflammation and inhibits neutrophil extracellular trap formation. The inhibitory receptor Allergin-1 is expressed by myeloid cells and B cells. Allergin-1 suppresses mast cell and basophil activation, but a potential regulatory role on neutrophils remains unexplored. We aimed to demonstrate the regulation of neutrophils by Allergin-1.

METHODS

We examine Allergin-1 isoform expression on human neutrophils during homeostatic (healthy donors) and chronic inflammatory (systemic lupus erythematosus patients) conditions in comparison to other circulating leukocytes by flow cytometry. To reveal a potential role for Allergin-1 in regulating neutrophilic inflammation, we experimentally infect wild-type (WT) and Allergin-1-deficient mice with a respiratory syncytial virus (RSV) and monitor disease severity and examine cellular airway infiltrate. Flow cytometry was used to confirm Allergin-1 expression by airway-infiltrated neutrophils in RSV infection-induced bronchiolitis patients.

RESULTS

Only the short 1 (S1) isoform, but not the long (L) or S2 isoform could be detected on blood leukocytes, with the exception of nonclassical monocytes, which exclusively express the S2 isoform. Allergin-1 expression levels did not vary significantly between healthy individuals and patients with the systemic inflammatory disease on any interrogated cell type. Airway-infiltrated neutrophils of pediatric RSV bronchiolitis patients were found to express Allergin-1S1. However, Allergin-1-deficient mice experimentally infected with RSV did not show exacerbated disease or increased neutrophil airway infiltration compared to WT littermates.

CONCLUSION

Allergin-1 isoform expression is unaffected by chronic inflammatory conditions. In stark contrast to fellow inhibitory receptor LAIR-1, Allergin-1 does not regulate neutrophilic inflammation in a mouse model of RSV bronchiolitis.

An inhibitory immunoreceptor, Allergin-1, suppresses FITC-induced type 2 contact hypersensitivity

Although allergic contact dermatitis (ACD) is the most common T cell-mediated inflammatory responses against an allergen in the skin, the pathogenesis of ACD remains incompletely understood. In the sensitization phase in ACD, hapten-bearing dermal dendritic cells (DCs) play a pivotal role in the transport of an antigen to the lymph nodes (LNs), where they present the antigen to naïve T cells. Here we report that Allergin-1, an inhibitory immunoreceptor containing immunoreceptor tyrosine-based inhibitory motif (ITIM) in the cytoplasmic region, is highly expressed on dermal DCs. Mice deficient in Allergin-1 exhibited exacerbated fluorescein isothiocyanate (FITC)-induced type 2 contact hypersensitivity (CHS) such as ear swelling and skin eosinophilia. Allergin-1-deficient mice also showed larger numbers of CD4⁺ T cells and FITC-bearing DCs and greater expressions of type 2 cytokines, including IL-5, IL-10 and IL-13, in the draining LNs than did wild type mice. In sharp contrast, Allergin-1-deficient mice showed comparable level of type 1 CHS induced by 2,4-dinitrofluorobenzene (DNFB). These results suggest that Allergin-1 on dermal DC inhibits type 2, but not type 1, immune responses in the sensitization phase of CHS.

Combining an Alarmin HMGN1 Peptide with PD-L1 Blockade Results in Robust Antitumor Effects with a Concomitant Increase of Stem-Like/Progenitor Exhausted CD8+ T Cells

The expansion of intratumoral stem-like/progenitor exhausted CD8⁺ T (Tstem/Tpex) cells provides a potential approach to improve the therapeutic efficacy of immune checkpoint blockade (ICB). Thus, here we demonstrate a strategy to facilitate Tstem/Tpex cell expansion by combining an alarmin high-mobility group nucleosome binding domain 1 (HMGN1) peptide with programmed death-ligand 1 (PD-L1) blockade. The antitumor effects of HMGN1, anti-PD-L1, and their combined treatment were monitored in the B16F10, LLC, Colon26, or EO771 tumor-bearing mice. The comprehensive immunologic analyses, such as high-dimensional flow cytometry, transcriptome analysis, and single-cell RNA-sequencing (scRNA-seq), were used to investigate the cellular and molecular mechanisms of antitumor immune responses after treatments. We identified the immunostimulatory domain (EPKRR SARLS AKPPA KVEAK PKK) on HMGN1 and synthesized this domain as a therapeutic peptide (minP1). Combined treatment with minP1 and PD-L1 blockade induced durable tumor regression in tumor-bearing mice. minP1 increased the number of intratumoral mature DCs enriched in immunoregulatory molecules (mregDC) and enhanced their MHC class I antigen-presenting program. minP1 also synergized with PD-L1 blockade in augmenting intratumoral Tstem/Tpex cell number. Analysis of our scRNA-seq dataset by CellPhonDB suggested potential interactions between mregDCs and Tstem/Tpex cells in tumors. Our results indicate that HMGN1 peptide (minP1) serves as an immunoadjuvant to promote effective anti-PD-L1 immunotherapy with increased Tstem/Tpex cells in tumors.

Allergin-1 Immunoreceptor Suppresses House Dust Mite-Induced Allergic Airway Inflammation

House dust mite (HDM) allergens are leading causes of allergic asthma characterized by Th2 responses. The lung-resident CD11b⁺ dendritic cells (DCs) play a key role in Th2 cell development in HDM-induced allergic asthma. However, the regulatory mechanism of HDM-induced CD11b⁺ DC activation remains incompletely understood. In this study, we demonstrate that mice deficient in an inhibitory immunoreceptor, Allergin-1, showed exacerbated HDM-induced airway eosinophilia and serum IgE elevation. By using bone marrow-chimeric mice that were sensitized with adoptively transferred HDM-stimulated wild-type or Allergin-1-deficient CD11b⁺ bone marrow-derived cultured DCs (BMDCs), followed by challenge with HDM, we show that Allergin-1 on the BMDCs suppressed HDM-induced allergic airway inflammation. We also show that Allergin-1 suppressed HDM-induced PGE₂ production from CD11b⁺ BMDCs by inhibiting Syk tyrosine kinase activation through recruitment of SHP-1, subsequently leading to negative regulation of Th2 responses. These results suggest that Allergin-1 plays an important role in regulation of HDM-induced allergic airway inflammation.

Selective suppression of oral allergen-induced anaphylaxis by Allergin-1 on basophils in mice

Mast cells (MCs) play a critical role in oral allergen-induced anaphylaxis. However, the contribution of basophils to the anaphylaxis remains unclear. The inhibitory immunoreceptor Allergin-1 is highly expressed on MCs and basophils and inhibits FcεRI-mediated signaling in MCs. Here, we show that Allergin-1-deficient (Milr1−/−) mice developed more severe hypothermia, a higher mortality rate and a greater incidence of diarrhea than did wild-type (WT) mice in an oral ovalbumin (OVA)-induced food allergy model. MC-deficient Mas–TRECK mice, which had been reconstituted with either WT or Milr1−/− bone marrow-derived cultured MCs, did not develop hypothermia in this food allergy model. On the other hand, depletion of basophils by injection of anti-CD200R3 antibody rescued Milr1−/− mice from lethal hypothermia but not from diarrhea. In vitro analyses demonstrated that Allergin-1 inhibits IgE-dependent activation of both human and mouse basophils. Thus, Allergin-1 on basophils selectively suppresses oral allergen-induced anaphylaxis.

Allergin-1 on mast cells suppresses house dust mite-induced airway hyperresponsiveness in mice

Although airway hyperresponsiveness (AHR) is a prominent feature of asthma, how it is regulated remains incompletely understood. Allergin-1, an inhibitory immunoglobulin-like receptor containing an immunoreceptor tyrosine-based inhibitory motif (ITIM), is expressed on human and mouse mast cells (MCs) and inhibits high-affinity receptor for IgE (FcεRI)-mediated signaling. Using MC-deficient KitW-sh/W-sh mice and Mas-TRECK mice, which carries a diphtheria toxin (DT)-induced MC deletion system based on il4 enhancer elements, we demonstrate here that MCs are involved in the induction of house dust mite (HDM)-induced AHR. Further, we show that MCs deficient in Allergin-1 exacerbated HDM-induced AHR, but had no effect on airway inflammation. In vitro analysis demonstrated that Allergin-1 inhibited anti-HDM allergen antibody-dependent HDM allergen-mediated degranulation by MCs. Thus, Allergin-1 on MCs plays an important role in the regulation of HDM-induced AHR.

Combined treatment with HMGN1 and anti-CD4 depleting antibody reverses T cell exhaustion and exerts robust anti-tumor effects in mice

BACKGROUND

Transient depletion of CD4⁺ T cells results in tumor suppression and survival benefit in murine models; however, the tumor progression and recurrence still occur over more long-term monitoring of mice. Thus, we explored an additional strategy to enhance endogenous immune responses by an alarmin, high mobility group nucleosome binding protein 1 (HMGN1).

METHODS

The anti-tumor effects of HMGN1, anti-CD4 depleting antibody, and their combined treatment were monitored in the Colon26 or the B16F10 subcutaneous murine models. The tumor-infiltrating CD8⁺ T cell proliferation, differentiation, exhaustion, and its gene expression were determined by flow cytometry, transcriptome analysis, and quantitative real-time PCR.

RESULTS

Our results show that a systemic administration of low doses of HMGN1 with an anti-CD4 depleting antibody (HMGN1/αCD4) promoted expansion of CD8⁺ T cell populations (e.g. CD137⁺ PD-1⁺ and CD44^hi PD-1⁺), recruited CCR7⁺ migratory dendritic cells to the tumor, and reduced co-inhibitory molecules (e.g. PD-1, LAG-3, and TIM-3) to counteract CD8⁺ T cell exhaustion.

CONCLUSION

The HMGN1/αCD4 treatment expanded effector CD8⁺ T cells and prolonged their anti-tumor activities by rescuing them from exhaustion, thus resulting in tumor regression and even rejection in long-term monitored mice.

Allergy inhibitory receptor-1 inhibits autoantibody production via upregulation of apoptotic debris clearance by macrophages

AIM

Allergy inhibitory receptor-1 (Allergin-1) is a newly identified immune regulatory molecule thought to influence autoantibody production. Autoantibody production, like that observed in Allergin-1-deficient mice, is crucial in the pathogenesis of several autoimmune diseases such as systemic lupus erythematosus. The purpose of this study is to clarify the regulatory role of Allergin-1-mediated autoantibody production using a murine model of thymocytic anaphylaxis.

METHODS

C57BL/6 (WT) and Allergin-1-deficient mice were treated with apoptotic cells from naive thymocytes stimulated by dexamethasone. Antibody titers of total or immunoglobulin G (IgG) subclass of anti-double-stranded DNA (anti-dsDNA) and anti-histone antibody from serum were measured using an enzyme-linked immunosorbent assay. Macrophages from wild-type (WT) or Allergin-1-deficient mice were co-cultured with fluorescence-labeled apoptotic thymocytes or fluorogenic reagent and resultant phagocytic activity was quantified by with flow cytometry.

RESULTS

After apoptotic cells injection, antibody titers of total and IgG3 anti-dsDNA and total anti-histone from serum were significantly increased in Allergin-1-deficient versus WT mice. Phagocytic activity was significantly lower in macrophages from Allergin-1-deficient mice versus WT mice.

CONCLUSION

Allergin-1 might play an inhibitory role in autoantibody production via upregulation of macrophage phagocytosis.

Combination of anti-CD4 antibody treatment and donor lymphocyte infusion ameliorates graft-versus-host disease while preserving graft-versus-tumor effects in murine allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (allo‐HSCT) is not only a well‐established immunotherapy for hematologic malignancies, but is potentially useful for treating solid tumors refractory to available therapies. However, application of allo‐HSCT to solid tumors is limited, despite the beneficial antitumor effects, by the risk of graft‐versus‐host disease (GVHD). CD4⁺ T cells have been implicated in several aspects of GVHD, and suppress antitumor CD8⁺ T‐cell responses. In the present study, we investigated clinically applicable allo‐HSCT protocols designed to maximize antitumor effects while reducing the risk of GVHD. We used a mouse model of allo‐HSCT with s.c. tumors. We found that myeloablative conditioning was associated with better inhibition of tumor growth but with severe acute GVHD. Early treatment with anti‐CD4 mAb substantially ameliorated GVHD while preserving antitumor effects, leading to improved survival in myeloablative allo‐HSCT. Late treatment with anti‐CD4 mAb also ameliorated GVHD to some extent. Donor lymphocyte infusion in GVHD mice treated with anti‐CD4 mAb further suppressed tumor growth without exacerbating GVHD. Collectively, our results suggest that myeloablative allo‐HSCT followed by anti‐CD4 mAb treatment and donor lymphocyte infusion could be a potent and safe immunotherapy for patients with cancers refractory to available therapies.

T-bet regulates differentiation of forkhead box protein 3+ regulatory T cells in programmed cell death-1-deficient mice

Programmed cell death-1 (PD-1) plays an important role in peripheral T cell tolerance, but whether or not it affects the differentiation of helper T cell subsets remains elusive. Here we describe the importance of PD-1 in the control of T helper type 1 (Th1) cell activation and development of forkhead box protein 3 (FoxP3(+)) regulatory T cells (Tr(egs)). PD-1-deficient T cell-specific T-bet transgenic (P/T) mice showed growth retardation, and the majority died within 10 weeks. P/T mice showed T-bet over-expression, increased interferon (IFN)-γ production by CD4(+) T cells and significantly low FoxP3(+) T(reg) cell percentage. P/T mice developed systemic inflammation, which was probably induced by augmented Th1 response and low FoxP3(+) T(reg) count. The study identified a unique, previously undescribed role for PD-1 in Th1 and T(reg) differentiation, with potential implication in the development of Th1 cell-targeted therapy.

Suppressive effects of a novel CC chemokine receptor 4 antagonist on Th2 cell trafficking in ligand- and antigen-induced mouse models

CC chemokine receptor 4 (CCR4) has been implicated as a preferential marker for T helper type 2 (Th2) cells, and is believed to be involved in the pathology of allergic diseases by controlling Th2 cell trafficking into inflamed tissues. The objective of the study was to characterize the pharmacological properties of E0001-163, a novel CCR4 antagonist. E0001-163 was tested in both in vitro chemotaxis assays as well as in vivo mouse models of CCR4 ligand-induced air pouch and antigen-induced airway inflammation by utilizing in vitro-polarized Th2 cells. In vitro, E0001-163 inhibited migratory response of human Th2-polarized cells to CCL22, a CCR4 ligand, with an IC50 value of 11.9 nM. E0001-163 significantly suppressed CCL22-induced Th2 cell trafficking into mouse air pouch in a dose-dependent manner at doses of 3 and 10mg/kg, suggesting that E0001-163 has an inhibitory effect on CCR4-mediated T cell trafficking in vivo. In addition, E0001-163 partially decreased Th2 cell trafficking and the level of IL-4 in the lungs in Th2-tansferred and ovalbumin (OVA)-challenged mice. T cell trafficking involves multiple chemokine receptors both in acute and chronic phases, and our findings suggest that CCR4, together with other chemokine receptors, may be involved in Th2 cell trafficking under disease conditions.

Discovery of 4-[4-({(3R)-1-butyl-3-[(R)-cyclohexyl(hydroxy)methyl]-2,5-dioxo-1,4,9-triazaspiro[5.5]undec-9-yl}methyl)phenoxy]benzoic acid hydrochloride: a highly potent orally available CCR5 selective antagonist

Based on the original spirodiketopiperazine design framework, further optimization of an orally available CCR5 antagonist was undertaken. Structural hybridization of the hydroxylated analog 4 derived from one of the oxidative metabolites and the new orally available non-hydroxylated benzoic acid analog 5 resulted in another potent orally available CCR5 antagonist 6a as a clinical candidate. Full details of a structure-activity relationship (SAR) study and ADME properties are presented.

Type I interferon promotes PD-1 transcription and limits the duration of T cell-mediated immunity (63.24)

PD-1 is a co-receptor for T lymphocytes that provides feedback inhibition of T-cell activation. Although PD-1’s expression on T cells is known to be activation dependent, the factors that determine the timing, intensity, and duration of PD-1 expression in immune reactions are not fully understood. To address this question, we analyzed a conserved 5’-flanking region of the PD-1 gene, and identified a putative interferon-stimulation response element (ISRE), which was responsible for PD-1 transcription in the 2B4.11 T-cell line. Consistent with this finding, activation by interferon (IFN) alpha enhanced both the induction and maintenance of PD-1 expression on TCR-engaged primary mouse T cells through an association of interferon-responsive factor-9 (IRF9) to the ISRE. Indeed, PD-1 expression on antigen-specific CD8+ T cells was augmented by IFN alpha in vivo. We also demonstrated that IFN alpha administration in combination with PD-1 blockade in tumor-bearing mice effectively augmented the anti-tumor immunity. Thus we propose that strong innate inflammatory responses promote primary T-cell activation and their differentiation into effector cells, but also cause an attenuated T-cell response in sustained immune reactions, at least partially through type I interferon-mediated PD-1 transcription.

IFN-α directly promotes programmed cell death-1 transcription and limits the duration of T cell-mediated immunity

Programmed cell death-1 (PD-1) is an inhibitory coreceptor for T lymphocytes that provides feedback inhibition of T cell activation. Although PD-1's expression on T cells is known to be activation dependent, the factors that determine the timing, intensity, and duration of PD-1 expression in immune reactions are not fully understood. To address this question, we performed a fine mapping analysis of a conserved 5'-flanking region of the PD-1 gene and identified a putative IFN stimulation response element, which was responsible for PD-1 transcription in the 2B4.11 T cell line. Consistent with this finding, activation by IFN-α enhanced both the induction and maintenance of PD-1 expression on TCR-engaged primary mouse T cells through an association IFN-responsive factor 9 (IRF9) to the IFN stimulation response element. Furthermore, PD-1 expression on Ag-specific CD8(+) T cells was augmented by IFN-α in vivo. We propose that strong innate inflammatory responses promote primary T cell activation and their differentiation into effector cells, but also cause an attenuated T cell response in sustained immune reactions, at least partially through type I IFN-mediated PD-1 transcription. Based on this idea, we demonstrate that IFN-α administration in combination with PD-1 blockade in tumor-bearing mice effectively augments the antitumor immunity, and we propose this as a novel and rational approach for cancer immunotherapy.

Spirodiketopiperazine-based CCR5 antagonist: discovery of an antiretroviral drug candidate

Following the discovery that hydroxylated derivative 3 (Fig. 1) was one of the oxidative metabolites of the original lead 1, it was found that hydroxylated compound 4 possesses higher in vitro anti-HIV potency than the corresponding non-hydroxylated compound 2. Structural hybridation of 4 with the orally available analog 5 resulted in another orally-available spirodiketopiperazine CCR5 antagonist 6a that possesses more favorable pharmaceutical profile for use as a drug candidate.

Discovery of orally available spirodiketopiperazine-based CCR5 antagonists

Using the previously reported novel spirodiketopiperazine scaffold, the design and synthesis of orally available CCR5 antagonists was undertaken. Compounds possessing a carboxylic acid function in the appropriate position showed improved oral exposure (AUC) relative to the initial chemical leads without reduction in the antagonist activity. The optimized compound 40 was found to show potent anti-HIV activity. Full details of structure-activity relationship (SAR) study are presented.

Spirodiketopiperazine-based CCR5 antagonists: Improvement of their pharmacokinetic profiles

Spirodiketopiperazine-based CCR5 antagonists, showing improved pharmacokinetic profiles without reduction in antagonist activity, were designed and synthesized. We also demonstrate the anti-HIV activity of a representative compound 12, as measured in a p24 assay.

In vitro and clinical investigation of the relationship between CCR5 receptor occupancy and anti-HIV activity of Aplaviroc

Aplaviroc (GW873140) binds specifically to human cellular CC chemokine receptor 5 (CCR5) and demonstrates potent anti-human immunodeficiency virus activity in vitro in the subnanomolar range. In vitro studies show that aplaviroc selectively inhibits the binding of a particular monoclonal antibody, 45531, to CCR5. Based on this observation, a flow cytometry-based assay was developed to determine percentage CCR5 receptor occupancy (RO). CCR5 receptor occupancy was aplaviroc concentration-dependent and related to anti-human immunodeficiency virus activity in vitro. In the clinical setting, CCR5 receptor occupancy in peripheral blood was >98% in all subjects within 2 to 3 hours of dosing, which is consistent with the peak plasma concentrations of drug. Longitudinal analysis in the drug washout period revealed the time to 50% CCR5 receptor occupancy averaged >100 hours, in both human immunodeficiency virus-positive and human immunodeficiency virus-negative subjects, substantially longer than the plasma pharmacokinetic half-life of 3 hours. The duration of CCR5 receptor occupancy appeared to be dose-dependent and associated with antiviral activity as measured by plasma human immunodeficiency virus RNA nadir following 10 days of multiple dose administration. These data demonstrate that the analysis of CCR5 receptor occupancy, in addition to conventional plasma-based pharmacokinetic measures, provides an informative tool to assist in evaluating the pharmacodynamic and antiviral effects of cellular CC chemokine receptor antagonists.

CCR7 mediates the migration of Foxp3+ regulatory T cells to the paracortical areas of peripheral lymph nodes through high endothelial venules

Thymus-derived forkhead box p3(+) naturally occurring regulatory T cells (nTreg) are thought to circulate throughout the body to maintain peripheral immunological self-tolerance through interactions with dendritic cells (DCs), resulting in regulation of conventional T cells. However, the chemokine receptors, which are putatively involved in the in vivo migration of nTreg, have not been fully established. Here, we demonstrated that lymph node nTreg preferentially migrated to the paracortical area of lymph nodes after adoptive transfer, where they were observed to make contact frequently with CD8alpha(+) DCs and CD8alpha(-) CD11b(-) DCs. This migration of nTreg to the paracortical areas was impaired severely when cells were prepared from CCR7-deficient mice. However, to some extent, CCR7-independent migration of nTreg in such CCR7-deficient mice was also observed, but this occurred mainly in the medullary high endothelial venules. Taken together, these data provide the evidence that CCR7 mediates nTreg migration to the paracortical areas of lymph nodes under steady-state conditions; however, CCR7-independent migration also takes place in the medulla.

Specific and high-affinity binding of tetramerized PD-L1 extracellular domain to PD-1-expressing cells: possible application to enhance T cell function

The negative co-stimulatory receptor, programmed cell death 1 (PD-1), is induced on activated T cells and delivers inhibitory signals upon engagement with its ligands PD-L1 and PD-L2, which are expressed on various somatic cells and certain cancers. Accumulating evidence suggests that interfering with the PD-1-PD-L1 interaction may result in the restoration of defective T cell functions in cancer and chronic viral infection. Herein, we established procedures to produce large amounts of renatured recombinant extracellular domain proteins of mouse PD-1 (mPD-1) and PD-L1. While monomeric mPD-1 and mouse PD-L1 (mPD-L1) only marginally interacted with the cells expressing their counterpart proteins, their tetramerization markedly enhanced the affinity with the K(d) of mPD-L1 tetramer being nearly 100-fold lower than that of the corresponding monomer. The affinity of mPD-L1 tetramer was even higher than a high-affinity anti-PD-1 mAb, and it efficiently inhibited the binding of mPD-L1/Fc-chimeric protein to mPD-1(+) cells. Functionally, mPD-L1 tetramer significantly enhanced the proliferative responses as well as the cytotoxic activity of T cells against specific target cells in vitro. The results suggest that oligomeric PD-L1 extracellular domains may provide a potential means to restore T cell functions in cancer and viral infection in humans.

Spirodiketopiperazine-based CCR5 antagonists: Lead optimization from biologically active metabolite

Hydroxylated derivatives were designed and synthesized based on the information of oxidative metabolites. Compounds derived from beta-substituted (2R,3R)-2-amino-3-hydroxypropionic acid showed improved inhibitory activities against the binding of MIP-1alpha to human CCR5, compared with the non-hydroxylated derivatives and the other isomers.

Design, synthesis, and biological evaluation of the combinatorial library with a new spirodiketopiperazine scaffold. Discovery of novel potent and selective low-molecular-weight CCR5 antagonists

We previously reported the discovery of several spirodiketopiperazine derivatives as potent CCR5 antagonists with anti-HIV activity. Herein, we describe in detail the identification of these lead compounds using a combinatorial chemistry approach. A novel spirodiketopiperazine scaffold was designed on the basis of the concept of the privileged structure of G-protein-coupled receptors (GPCRs). This new framework was obtained in acceptable yield with high purity from the readily prepared isonitrile resin through the Ugi reaction, sequential transformations, and cyclative cleavage. By measuring the inhibitory activity of each compound in the initial library against the intracellular calcium mobilization stimulated by MIP-1alpha, several compounds were found to show modest but selective CCR5 antagonistic activity. After the rapid evaluation of these hit compounds, several single-digit nanomolar, low-molecular-weight CCR5 antagonists that can potently block the infectivity and replication of laboratory and clinical strains of HIV as well as those of highly drug-resistant HIV variants with minimal cytotoxicity have been identified.

Potent anti-R5 human immunodeficiency virus type 1 effects of a CCR5 antagonist, AK602/ONO4128/GW873140, in a novel human peripheral blood mononuclear cell nonobese diabetic-SCID, interleukin-2 receptor gamma-chain-knocked-out AIDS mouse model

We established human peripheral blood mononuclear cell (PBMC)-transplanted R5 human immunodeficiency virus type 1 isolate JR-FL (HIV-1(JR-FL))-infected, nonobese diabetic-SCID, interleukin 2 receptor gamma-chain-knocked-out (NOG) mice, in which massive and systemic HIV-1 infection occurred. The susceptibility of the implanted PBMC to the infectivity and cytopathic effect of R5 HIV-1 appeared to stem from hyperactivation of the PBMC, which rapidly proliferated and expressed high levels of CCR5. When a novel spirodiketopiperazine-containing CCR5 inhibitor, AK602/ONO4128/GW873140 (molecular weight, 614), was administered to the NOG mice 1 day after R5 HIV-1 inoculation, the replication and cytopathic effects of R5 HIV-1 were significantly suppressed. In saline-treated mice (n = 7), the mean human CD4(+)/CD8(+) cell ratio was 0.1 on day 16 after inoculation, while levels in mice (n = 8) administered AK602 had a mean value of 0.92, comparable to levels in uninfected mice (n = 7). The mean number of HIV-RNA copies in plasma in saline-treated mice were approximately 10(6)/ml on day 16, while levels in AK602-treated mice were 1.27 x 10(3)/ml (P = 0.001). AK602 also significantly suppressed the number of proviral DNA copies and serum p24 levels (P = 0.001). These data suggest that the present NOG mouse system should serve as a small-animal AIDS model and warrant that AK602 be further developed as a potential therapeutic for HIV-1 infection.

Spirodiketopiperazine-based CCR5 inhibitor which preserves CC-chemokine/CCR5 interactions and exerts potent activity against R5 human immunodeficiency virus type 1 in vitro

We identified a novel spirodiketopiperazine (SDP) derivative, AK602/ONO4128/GW873140, which specifically blocked the binding of macrophage inflammatory protein 1alpha (MIP-1alpha) to CCR5 with a high affinity (K(d) of approximately 3 nM), potently blocked human immunodeficiency virus type 1 (HIV-1) gp120/CCR5 binding and exerted potent activity against a wide spectrum of laboratory and primary R5 HIV-1 isolates, including multidrug-resistant HIV-1 (HIV-1(MDR)) (50% inhibitory concentration values of 0.1 to 0.6 nM) in vitro. AK602 competitively blocked the binding to CCR5 expressed on Chinese hamster ovary cells of two monoclonal antibodies, 45523, directed against multidomain epitopes of CCR5, and 45531, specific against the C-terminal half of the second extracellular loop (ECL2B) of CCR5. AK602, despite its much greater anti-HIV-1 activity than other previously published CCR5 inhibitors, including TAK-779 and SCH-C, preserved RANTES (regulated on activation normal T-cell expressed and secreted) and MIP-1beta binding to CCR5(+) cells and their functions, including CC-chemokine-induced chemotaxis and CCR5 internalization, while TAK-779 and SCH-C fully blocked the CC-chemokine/CCR5 interactions. Pharmacokinetic studies revealed favorable oral bioavailability in rodents. These data warrant further development of AK602 as a potential therapeutic for HIV-1 infection.

Novel low molecular weight spirodiketopiperazine derivatives potently inhibit R5 HIV-1 infection through their antagonistic effects on CCR5

Novel low molecular weight spirodiketopiperazine derivatives which potently inhibit R5 human immunodeficiency virus type 1 (HIV-1) infection through their antagonistic effects on CCR5 were identified. One such compound E913 (M(r) 484) specifically blocked the binding of macrophage inflammatory protein-1alpha (MIP-1alpha) to CCR5 (IC(50) 0.002 microm) and MIP-1alpha-elicited cellular Ca(2+) mobilization (IC(50) approximately 0.02 microm). E913 potently inhibited the replication of laboratory and primary R5 HIV-1 strains as well as various multidrug-resistant monocyte/macrophage tropic (R5) HIV-1 at IC(50) values of 0.03 to 0.06 microm. E913 was inactive against T cell tropic (X4) HIV-1; however, when combined with a CXCR4 antagonist AMD-3100, E913 potently and synergistically inhibited the replication of dualtropic HIV-1 and a 50:50 mixture of R5 and X4 HIV-1. Antagonism in anti-HIV-1 activity was not seen when E913 was combined with the reverse transcriptase inhibitor zidovudine or protease inhibitors. E913 proved to compete with the binding of antibodies to CCR5 which recognize the C-terminal half of the second extracellular loop (ECL2B) of CCR5. E913 and its analogs are acid-resistant and orally bioavailable in rodents. These data warrant that spirodiketopiperazine derivatives be further developed as potential therapeutics for HIV-1 infection.

Beta-amyloid peptides inhibit acetylcholine release from cholinergic presynaptic nerve endings isolated from an electric ray

We investigated the effects of beta-amyloid (Abeta) peptides on cholinergic synaptosomes isolated from the electric organ of the Japanese marine ray Narke japonica. Fresh and pre-incubated solutions of Abeta(1-42) inhibited acetylcholine (ACh) release from the synaptosomes evoked by high [K+] depolarization when incubated with synaptosomes for 10 min before the depolarizing stimulus. A freshly prepared solution of Abeta(1-40) did not inhibit the evoked ACh release, but prolonged pre-incubation of Abeta(1-40) solution caused the inhibition. Abeta(1-15) neither in fresh nor pre-incubated solution inhibited. These results have demonstrated that Abeta peptides can acutely inhibit the depolarization-evoked release of ACh by acting directly on cholinergic presynaptic nerve endings. The electrophoresis analysis showed a strong correlation between Abeta aggregation and its inhibition for ACh release.

Pure red cell aplasia after major ABO-incompatible bone marrow transplantation: two case reports of treatment with recombinant human erythropoietin

A 34-year-old man with acute myelocytic leukemia (AML: MO) and a 32-year-old woman with AML: M2 developed pure red cell aplasia (PRCA) after receiving a major ABO incompatible bone marrow transplant (BMT). The first patient responded to recombinant human erythropoietin (rhEPO) therapy, while the second did not. The second patient also received methylprednisolone (m-PSL) but developed reticulocytosis and hemolysis after the administration of m-PSL. Plasmapheresis was then performed and the patient promptly recovered from hemolysis and PRCA. We conclude that close attention must be paid when treating PRCA following major ABO-incompatible BMT with rhEPO and m-PSL, as there is always the potential for massive hemolysis.

Rationally designed syntheses of high-mannose and complex type undecasaccharides

Synthetic routes are described to a high-mannose type triantenary undecasaccharide 1 and a completely protected form 39 of the complex type biantenary undecasaccharide 2 carrying alpha-(2-->3)-linked sialic acid residues. Starting from a previously reported trisaccharide 4, the core pentasaccharides 15 and 37 were synthesized through regio- and/or stereo-selective mannosylation with a suitably protected mannosyl donor. Chain elongation of 15 by stepwise addition of a mannose residue afforded an undecasaccharide 20 that was eventually deprotected to give 1. On the other hand, coupling of 38 and a trisaccharide glycosyl donor 36 afforded 39.

Correlation between myocardial dysfunction and changes in myosin isoenzymes in diabetic rat hearts

We investigated the relationship between papillary muscle function and the myosin isoenzyme pattern, collagen content, and the type of myocardial collagen in diabetic rats to elucidate the mechanism of short-term myocardial dysfunction in diabetes. Diabetes was induced in 9-week-old male Wistar rats with a single intravenous injection of streptozotocin. One-half of the diabetic rats were treated with insulin. Age-matched control rats were also studied. The time to peak tension (TPT) of isometric papillary muscle contraction, time to 1/2 relaxation, and time from the peak tension to the peak decrease in tension (TPN) were significantly prolonged in diabetic rats at 4, 8, and 12 weeks. The peak increase and decrease in tension were slower in the diabetic rats compared with control rats. The level of the myocardial myosin isoenzyme V3 was greater in diabetic rats than in control rats at each interval. Findings in insulin-treated rats were similar to those in controls. The collagen content and the ratio of type I collagen to type III collagen were similar in all groups. The V3 level was significantly correlated with mechanical parameters (TPT versus %V3: r = 0.81, p < 0.01; TPN versus % V3: r = 0.78, p < 0.01). Our findings suggest that short-term myocardial dysfunction in diabetic rats is related to changes in the myosin isoenzyme pattern.

Hyperthyroidism complicated with sick sinus syndrome

A 50-year-old woman was transported to a hospital complaining of marked general malaise and epigastralgia with diarrhea and vomiting. Her electrocardiogram showed sinus arrest with a duration of nearly 8 sec. Atrial pacing with an external pacemaker improved her symptoms promptly. Following transfer to our hospital 3 days later, bradyarrhythmia was not detected despite the removal of the external pacemaker. Transient atrial fibrillation was found in our hospital, and she was diagnosed as hyperthyroidism based on findings of finger tremor, exophthalmos, diffuse goiter and an abnormally high level of thyroid hormone. On cardiac catheterization, left ventriculography showed anterior wall hypokinesis and mild mitral regurgitation. Coronary arteriography showed the absence of organic stenosis. Right ventricular endomyocardial biopsy showed myocardial hypertrophy and partial disarray, but no findings of myocarditis. Electrophysiological study showed the normal upper range of AH-time (120 msec) and HV-time (50 msec), and prolongation of corrected sinus recovery time (CSRT, 955 msec). After a euthyroid state was successively induced for about 10 days by methylmercaptoimidazole therapy, AH-time, HV-time and CSRT were shortened to 85, 35 and 290 msec respectively. Her complaints and sick sinus syndrome disappeared after the treatment of hyperthyroidism without a pacemaker.

Genomic organization of mouse J kappa recombination signal binding protein (RBP-J kappa) gene

We have isolated a cDNA clone (RBP-2) for the protein (RBP-J kappa) which binds to immunoglobulin recombination signals with 23-base pair spacers (Matsunami, N., Hamaguchi, Y., Yamamoto, Y., Kuze, K., Kangawa, K., Matsuo, H., Kawaichi, M., and Honjo, T. (1989) Nature 342, 934-937). During further screening of a cDNA library from the same mouse pre-B cell line (38B9), we have isolated a second cDNA clone (RBP-2N) which differs from RBP-2 in its 5' sequence. RNase protection assays indicated that the RBP-2N type mRNA was produced in 10-20 times the quantity as RBP-2 mRNA. To elucidate the relationship between these two mRNAs, we analyzed the genomic organization of the RBP-J kappa gene. Southern hybridization of mouse genomic DNA detected at least 7 EcoRI fragments hybridizing to an RBP-2 cDNA probe, suggesting a complex structure for the RBP-J kappa gene. Cloning of each EcoRI fragment revealed one functional RBP-J kappa gene and three related genes. The functional gene was composed of 11 exons and spanned at least 50 kilobase pairs. The sequence of exon 1 and its 5'-flanking region contained a GC-rich promoter-like region but no apparent TATA box. The initiation site of transcription was heterogeneous, and the two types of mRNA are produced from the same exon by transcription initiation at different sites and by different usage of splice signals. Two of the three related genes were processed pseudogenes with scattered stop codons. The other was also a processed gene with a sequence exactly the same as that of RBP-2, except that this gene lacked the sequence corresponding to the first exon of the functional gene.

Stereoselective total synthesis of glycopeptides bearing the dimeric and trimeric sialosyl-Tn epitope

The dimeric and trimeric sialosyl-Tn epitopes, [alpha-D-Neup5Ac-(2----6)-alpha-D-GalpNAc-(1----3)-L-Ser]n-L-Val (n = 2 and 3), which represent part of a clustered carbohydrate region of glycophorin A, a human erythrocyte glycoprotein, have been synthesised stereoselectively. 2-Azido-3-O-benzyl-4,6-O-benzylidene-2-deoxy-D-galactopyranosyl fluoride (GalpNAc unit), Fmoc-L-serine phenacyl ester (Ser unit), and benzyl 5-acetamido-4,7,8,9-tetra-O-benzyl-5-deoxy-3-S-phenyl-3-thio-D-erythro-L - gluco-2-nonulopyranosylonate bromide (Neup5Ac unit) were the key intermediates for stereoselective glycosylation. 2-Ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline-promoted elongation of the peptide chain and then hydrogenolysis afforded the title compounds.

Increase in left ventricular chamber stiffness in patients with non-insulin dependent diabetes mellitus

Indices of left ventricular ejection and diastolic filling were measured by cineventriculography in 11 patients with non-insulin dependent diabetes mellitus without significant coronary stenosis and 11 control subjects without diabetes mellitus. Indices of left ventricular ejection, such as ejection fraction and peak ejection rate, were the same in the two groups. The left ventricular end-diastolic volume index and the rapid filling volume index were significantly smaller, the peak filling rate was lower, the left ventricular end-diastolic pressure was higher and the modulus of left ventricular chamber stiffness was larger in the diabetic patients than in the control subjects. These results indicate that left ventricular chamber stiffness is increased in patients with non-insulin dependent diabetes mellitus.

Correlation between histopathological changes and mechanical dysfunction in diabetic rat hearts

Recent clinical and experimental studies have suggested that diabetic patients may develop myocardial dysfunction in the absence of coronary heart disease and hypertension. In this study, the correlation between histopathological changes and myocardial dysfunction was studied in experimental diabetic rat hearts. Male Wistar rats were made diabetic at 9 weeks of age with a single intravenous injection of streptozotocin 50 mg/kg. The diabetic rats were studied along with age-matched control and insulin-treated rats at 4, 8, 12 and 24 weeks after the induction of diabetes to investigate isolated papillary muscle contraction and the histopathological picture simultaneously. In the isometric contractions, resting and developed tensions were similar. Time to peak tension and time to 1/2 relaxation were prolonged and the peak rate of tension rise and tension fall was depressed. On histological examination of left ventricular walls, diameters of myocytes were similar at all disease durations. Interstitial fibrosis and disarrangement of myocytes after 12 weeks were slightly increased in the diabetic hearts. Mechanical parameters did not worsen in parallel with the duration of diabetes and histological changes, but correlated with the blood glucose level. These data suggest that short-term mechanical defects in the experimental diabetic rat heart result from the metabolic disorder itself, with histopathological changes occurring later.

An autopsy case of hypertrophic cardiomyopathy showing dilated cardiomyopathy-like features by serial ventriculography

An autopsy case of hypertrophic obstructive cardiomyopathy (HOCM), in which the clinical features of dilated cardiomyopathy (DCM) developed after 10 years is described. Three serial left ventriculograms (LVG) and bi-ventriculograms (BVG) were performed during the 10-year follow-up. At the time of the first observation, the ECG revealed a giant negative T wave (GNT) in V5 (-1.5mV) and high voltage (SV1 + RV5 = 8.1mV). The LVG and BVG showed concentric left ventricular wall hypertrophy and a pressure gradient in the left ventricular out-flow tract. However, follow-up studies disclosed resolution of the GNT with decreased high voltage. All wall thicknesses and the ejection fraction were significantly decreased and the wall motion was reduced serially. These findings were consistent with the clinical profile of DCM. At autopsy, the heart weighed 610 g and showed dilated change of the left ventricular cavity. Significant myocardial fibrosis, bizarre myocardial hypertrophy with disorganization (BMHD) and severe narrowing of the intramural small arteries due to intimal thickening were found in the left ventricular wall, especially in the anterior and interventricular septal wall. This autopsy case suggests that some cases of HCM, with serial disappearance of the deep negative T wave and high voltage, deteriorate to the clinical profile of DCM.

[A noninvasive study on characteristics of the left ventricular function in elderly hypertensive patients]

To characterize the left ventricular (LV) systolic and diastolic function in elderly hypertensives, mechano-and echocardiography was performed in 27 elderly patients more than 65 years of age (20 hypertensives and 7 normotensives) and 46 middle-aged patients (34 hypertensives and 12 normotensives). In normotensives, a positive correlation was found to exist between age and blood pressure, LV wall thickness, II-RF interval and the A/E ratio, whereas the correlation of age to systolic parameters such as ET/PEP and EF was absent. This suggests that the LV diastolic function was impaired progressively by aging with preservation of the LV systolic function. In elderly hypertensives, LV systolic function was deteriorated and the A/E ratio increased as diastolic blood pressure became elevated. The A/E ratio also increased in this group as compared with that in middle-aged hypertensives, although the differences was not statistically significant. Unlike those in middle-aged hypertensives, the indices of LV function except the elevated blood pressure and the increased cardio-thoracic ratio were not significantly different between hypertensive and normotensive elderly patients. This might be because of the wide range of normal values in elderly persons due to the various degrees of atherosclerotic changes and other pathophysiologic factors, which might have masked obvious characteristics of hypertension in elderly hypertensives.

Thyroid antigen-mediated glomerulonephritis in Graves' disease

We describe a patient with Graves' disease in whom marked proteinuria, microhematuria and hypoalbuminemia were associated. Renal biopsy demonstrated electrondense deposits in the capillary basement membrane, a finding consistent with immune complex glomerulonephritis. Indirect immunofluorescent examination with rabbit antihuman thyroglobulin indicated that these electron-dense deposits were thyroid antigen-mediated immune complexes.

Structure of the horseradish peroxidase isozyme C genes

We have isolated, cloned and characterized three cDNAs and two genomic DNAs corresponding to the mRNAs and genes for the horseradish (Armoracia rusticana) peroxidase isoenzyme C (HPR C). The amino acid sequence of HRP C1, deduced from the nucleotide sequence of one of the cDNA clone, pSK1, contained the same primary sequence as that of the purified enzyme established by Welinder [FEBS Lett. 72, 19-23 (1976)] with additional sequences at the N and C terminal. All three inserts in the cDNA clones, pSK1, pSK2 and pSK3, coded the same size of peptide (308 amino acid residues) if these are processed in the same way, and the amino acid sequence were homologous to each other by 91-94%. Functional amino acids, including His40, His170, Tyr185 and Arg183 and S-S-bond-forming Cys, were conserved in the three isozymes, but a few N-glycosylation sites were not the same. Two HRP C isoenzyme genomic genes, prxC1 and prxC2, were tandem on the chromosomal DNA and each gene consisted of four exons and three introns. The positions in the exons interrupted by introns were the same in two genes. We observed a putative promoter sequence 5' upstream and a poly(A) signal 3' downstream in both genes. The gene product of prxC1 might be processed with a signal sequence of 30 amino acid residues at the N terminus and a peptide consisting of 15 amino acid residues at the C terminus.

A total synthesis of hematoside, alpha-NeuGc-(2----3)-beta-Gal-(1----4)-beta-Glc-(1----1)-Cer

Methyl (5-acetoxyacetamido-4,7,8,9-tetra-O-acetyl-3,5- dideoxy-D-glycero-beta-D-galacto-2-nonulopyranosyl chloride)onate, prepared from N-glycolyl-neuraminic acid, was used for the glycosylation of benzyl O-(2,6-di-O-benzyl-beta-D- galactopyranosyl)-(1----4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside to give benzyl O-[methyl (5-acetoxyacetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero- alpha- and beta-D-galacto-2-nonulopyranosyl)onate]-(2----3)-O-(2,6-di-O -benzyl-beta- D-galacto-pyranosyl)-(1----4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside, and a regioisomer. Compounds 9 and 13 were converted into the corresponding glycotriaosyl glycosyl donors which, upon coupling with (2S,3R,4E)-3-O-tert-butyldiphenylsilyl-2-N- tetracosanoylsphingenine, afforded completely protected hematoside and a stereoisomer 26, respectively. Deprotection of 22 and 26 completed the first total synthesis of both hematoside and a stereoisomer, beta-NeuGc-(2----3)-beta-Gal-(1----4)-beta-Glc-(1----1)-Cer.