Requirement for the chemokine receptor CCR6 in allergic pulmonary inflammation.

Allergic asthmatic responses in the airway are associated with airway hyperreactivity, eosinophil accumulation in the lung, and cytokine production by allergen-specific, T helper cell type 2 (Th2) lymphocytes. Here, we show that in a cockroach antigen (CA) model of allergic pulmonary inflammation, the chemokine macrophage inflammatory protein (MIP)-3alpha is expressed in the lung within hours of allergen challenge. To determine the biologic relevance of this expression, mice lacking CCR6, the only known receptor for MIP-3alpha, were studied for their response to CA. CCR6-deficient mice were immunized to the same extent as their wild-type counterparts, as judged by cytokine production in antigen-challenged lymphocytes. However, compared with CA-challenged wild-type mice, challenged CCR6-deficient mice had reduced airway resistance, fewer eosinophils around the airway, lower levels of interleukin 5 in the lung, and reduced serum levels of immunoglobulin E. Together, these data demonstrate that MIP-3alpha and CCR6 function in allergic pulmonary responses and suggest that these molecules might represent novel therapeutic targets for treatment of asthma.

Transgenic expression of the chemokine receptor encoded by human herpesvirus 8 induces an angioproliferative disease resembling Kaposi's sarcoma.

Human herpesvirus 8 (HHV8, also known as Kaposi's sarcoma [KS]-associated herpesvirus) has been implicated as an etiologic agent for KS, an angiogenic tumor composed of endothelial, inflammatory, and spindle cells. Here, we report that transgenic mice expressing the HHV8-encoded chemokine receptor (viral G protein-coupled receptor) within hematopoietic cells develop angioproliferative lesions in multiple organs that morphologically resemble KS lesions. These lesions are characterized by a spectrum of changes ranging from erythematous maculae to vascular tumors, by the presence of spindle and inflammatory cells, and by expression of vGPCR, CD34, and vascular endothelial growth factor. We conclude that vGPCR contributes to the development of the angioproliferative lesions observed in these mice and suggest that this chemokine receptor may play a role in the pathogenesis of KS in humans.

Aberrant in vivo T helper type 2 cell response and impaired eosinophil recruitment in CC chemokine receptor 8 knockout mice.

Chemokine receptors transduce signals important for the function and trafficking of leukocytes. Recently, it has been shown that CC chemokine receptor (CCR)8 is selectively expressed by Th2 subsets, but its functional relevance is unclear. To address the biological role of CCR8, we generated CCR8 deficient (-/-) mice. Here we report defective T helper type 2 (Th2) immune responses in vivo in CCR8(-/)- mice in models of Schistosoma mansoni soluble egg antigen (SEA)-induced granuloma formation as well as ovalbumin (OVA)- and cockroach antigen (CRA)-induced allergic airway inflammation. In these mice, the response to SEA, OVA, and CRA showed impaired Th2 cytokine production that was associated with aberrant type 2 inflammation displaying a 50 to 80% reduction in eosinophils. In contrast, a prototypical Th1 immune response, elicited by Mycobacteria bovis purified protein derivative (PPD) was unaffected by CCR8 deficiency. Mechanistic analyses indicated that Th2 cells developed normally and that the reduction in eosinophil recruitment was likely due to systemic reduction in interleukin 5. These results indicate an important role for CCR8 in Th2 functional responses in vivo.

Golimumab, a human antibody to tumour necrosis factor {alpha} given by monthly subcutaneous injections, in active rheumatoid arthritis despite methotrexate therapy: the GO-FORWARD Study.

OBJECTIVE: The phase III GO-FORWARD study examined the efficacy and safety of golimumab in patients with active rheumatoid arthritis (RA) despite methotrexate therapy. METHODS: Patients were randomly assigned in a 3 : 3 : 2 : 2 ratio to receive placebo injections plus methotrexate capsules (group 1, n = 133), golimumab 100 mg injections plus placebo capsules (group 2, n = 133), golimumab 50 mg injections plus methotrexate capsules (group 3, n = 89), or golimumab 100 mg injections plus methotrexate capsules (group 4, n = 89). Injections were administered subcutaneously every 4 weeks. The co-primary endpoints were the proportion of patients with 20% or greater improvement in the American College of Rheumatology criteria (ACR20) at week 14 and the change from baseline in the health assessment questionnaire-disability index (HAQ-DI) score at week 24. RESULTS: The proportion of patients who achieved an ACR20 response at week 14 was 33.1% in the placebo plus methotrexate group, 44.4% (p = 0.059) in the golimumab 100 mg plus placebo group, 55.1% (p = 0.001) in the golimumab 50 mg plus methotrexate group and 56.2% (p<0.001) in the golimumab 100 mg plus methotrexate group. At week 24, median improvements from baseline in HAQ-DI scores were 0.13, 0.13 (p = 0.240), 0.38 (p<0.001) and 0.50 (p<0.001), respectively. During the placebo-controlled portion of the study (to week 16), serious adverse events occurred in 2.3%, 3.8%, 5.6% and 9.0% of patients and serious infections occurred in 0.8%, 0.8%, 2.2% and 5.6%, respectively. CONCLUSION: The addition of golimumab to methotrexate in patients with active RA despite methotrexate therapy significantly reduced the signs and symptoms of RA and improved physical function.

Tumorigenesis induced by the HHV8-encoded chemokine receptor requires ligand modulation of high constitutive activity.

ORF74 (or KSHV-vGPCR) is a highly constitutively active G protein-coupled receptor encoded by HHV8 that is regulated both positively and negatively by endogenous chemokines. When expressed in transgenic mice, this chemokine receptor induces an angioproliferative disease closely resembling Kaposi sarcoma (KS). Here we demonstrate that several lines of mice carrying mutated receptors deficient in either constitutive activity or chemokine regulation fail to develop KS-like disease. In addition, animals expressing a receptor that preserves chemokine binding and constitutive activity but that does not respond to agonist stimulation have a much lower incidence of angiogenic lesions and tumors. These results indicate that induction of the KS-like disease in transgenic mice by ORF74 requires not only high constitutive signaling activity but also modulation of this activity by endogenous chemokines.

Molecular identification and characterization of the platelet ADP receptor targeted by thienopyridine antithrombotic drugs.

ADP plays a critical role in modulating thrombosis and hemostasis. ADP initiates platelet aggregation by simultaneous activation of two G protein-coupled receptors, P2Y1 and P2Y12. Activation of P2Y1 activates phospholipase C and triggers shape change, while P2Y12 couples to Gi to reduce adenylyl cyclase activity. P2Y12 has been shown to be the target of the thienopyridine drugs, ticlopidine and clopidogrel. Recently, we cloned a human orphan receptor, SP1999, highly expressed in brain and platelets, which responded to ADP and had a pharmacological profile similar to that of P2Y12. To determine whether SP1999 is P2Y12, we generated SP1999-null mice. These mice appear normal, but they exhibit highly prolonged bleeding times, and their platelets aggregate poorly in responses to ADP and display a reduced sensitivity to thrombin and collagen. These platelets retain normal shape change and calcium flux in response to ADP but fail to inhibit adenylyl cyclase. In addition, oral clopidogrel does not inhibit aggregation responses to ADP in these mice. These results demonstrate that SP1999 is indeed the elusive receptor, P2Y12. Identification of the target receptor of the thienopyridine drugs affords us a better understanding of platelet function and provides tools that may lead to the discovery of more effective antithrombotic therapies.

Generation and analysis of mice lacking the chemokine fractalkine.

Fractalkine (CX(3)CL1) is the first described chemokine that can exist either as a soluble protein or as a membrane-bound molecule. Both forms of fractalkine can mediate adhesion of cells expressing its receptor, CX(3)CR1. This activity, together with its expression on endothelial cells, suggests that fractalkine might mediate adhesion of leukocytes to the endothelium during inflammation. Fractalkine is also highly expressed in neurons, and its receptor, CX(3)CR1, is expressed on glial cells. To determine the biologic role of fractalkine, we used targeted gene disruption to generate fractalkine-deficient mice. These mice did not exhibit overt behavioral abnormalities, and histologic analysis of their brains did not reveal any gross changes compared to wild-type mice. In addition, these mice had normal hematologic profiles except for a decrease in the number of blood leukocytes expressing the cell surface marker F4/80. The cellular composition of their lymph nodes did not differ significantly from that of wild-type mice. Similarly, the responses of fractalkine(-/-) mice to a variety of inflammatory stimuli were indistinguishable from those of wild-type mice.

Monoclonal antibodies as probes for a function of large T antigen during the elongation process of simian virus 40 DNA replication.

Various monoclonal antibodies specific for simian virus 40 large tumor antigen (T antigen) inhibit the elongation process of viral DNA replication in an in vitro system. The results provide strong evidence for a function intrinsic to T antigen during ongoing replicative-chain elongation. The antibody inhibition studies were further used to establish a correlation between the known biochemical activities of T antigen and its function during the elongation phase. The data demonstrate that, in addition to DNA binding and ATPase, a third function of T antigen is required for replicative chain elongation. This function is most probably related to the recently described DNA helicase activity of T antigen. This conclusion is based on the following results: aphidicolin treatment of actively replicating simian virus 40 minichromosomes causes a partial uncoupling of parental DNA strand separation and DNA synthesis; the strand separation reaction is blocked by the same monoclonal antibodies which strongly inhibit the elongation process. DNA helicase activity of isolated T antigen is equally well inhibited by the same set of monoclonal antibodies that affect minichromosome replication in vitro.

Requirements for promoter activity in mouse oocytes and embryos distinguish paternal pronuclei from maternal and zygotic nuclei.

Fertilization of mouse eggs produces a 1-cell embryo containing both a paternal and maternal pronucleus. These two nuclei combine during the first mitosis to form the zygotic nuclei of 2-cell embryos. This transition is accompanied by the onset of transcription and the decline of maternal mRNA-dependent gene expression. To determine how changes in nuclear composition affect gene expression, plasmid DNA containing a promoter and an enhancer that function throughout a broad host range was injected into nuclei of oocytes and embryos. The requirements for promoter activity in paternal pronuclei of 1-cell embryos were distinct from those in maternal or zygotic nuclei: (1) Paternal pronuclei permitted high levels of promoter activity relative to maternal or zygotic nuclei. (2) Butyrate, an agent that alters chromatin structure, stimulated promoter activity in maternal or zygotic nuclei, but not in paternal pronuclei. (3) The embryo-responsive polyomavirus F101 enhancer also stimulated promoter activity, but only after formation of a 2-cell embryo. Either butyrate or the F101 enhancer stimulated promoter activity in zygotic nuclei to the level observed in paternal pronuclei. Stimulation also was observed with 2-cell embryos containing nuclei of only maternal or paternal origin, but their transcriptional capacity was more limited. These and other results support the hypothesis that the need for enhancers in 2-cell embryos results from repression by chromatin structure, and the role of enhancers is to relieve this repression.

Regulation of gene expression in preimplantation mouse embryos: effects of the zygotic clock and the first mitosis on promoter and enhancer activities.

Previous studies have reported that promoters requiring enhancers for full activity in mammalian somatic cells also require enhancers when injected into mouse two-cell embryos, whereas the same promoters can be expressed just as efficiently in the absence of an enhancer when injected into arrested one-cell embryos. Experiments were designed to determine whether this phenomenon reflected normal developmental changes at the beginning of mammalian development, or simply differences in the physiological states of these cells under the experimental conditions employed. The activity of three different promoters that function in a wide variety of mammalian cells was measured both in embryos whose morphological development was arrested and in embryos that continued development in vitro. Expression of the injected gene was related to the onset of zygotic gene expression ("zygotic clock"), the phase of the cell proliferation cycle, the use of aphidicolin to arrest cell proliferation, and formation of two-cell embryos in vitro and in vivo. The results demonstrated that promoter activity was tightly linked to zygotic gene expression, while the need for enhancers to stimulate promoter activity depended only on formation of a two-cell embryo. These results further support the hypothesis that the first mitosis induces a general repression of promoters prior to initiation of zygotic gene expression that is relieved specifically by enhancers.

Simian virus 40 large T antigen DNA helicase. Characterization of the ATPase-dependent DNA unwinding activity and its substrate requirements.

The ATPase of SV40 large T antigen (T antigen) which is essential for the replication of SV40 minichromosomes was recently shown to be functionally related to a newly discovered DNA helicase activity. The T antigen helicase unwinds DNA duplices of several kilobase pairs in a reaction depending on the presence of hydrolyzable ribo- or deoxyribonucleoside triphosphates. The in vitro rate of movement through duplex DNA was found to be about 100 base pairs/min at 37 degrees C. For DNA unwinding, T antigen requires a 3'-single strand extension of a partially double-stranded substrate and invades the double strand section processively, in a 3' to 5' direction. The minimum length of the single-stranded tail was determined to be less than 5 nucleotides. Unwinding studies in the presence of the Escherichia coli single strand-specific DNA-binding protein and competition experiments indicate that T antigen helicase binds preferentially at the single-stranded/double-stranded DNA junction. This DNA structure is therefore proposed to serve as an entry site for the T antigen helicase. Previously reported data suggest that T antigen is the replicative helicase of the SV40 minichromosome. The results presented here are consistent with these findings and imply that T antigen migrates actively and processively along the template for the leading strand.

Changes in histone synthesis and modification at the beginning of mouse development correlate with the establishment of chromatin mediated repression of transcription.

The transition from a late 1-cell mouse embryo to a 4-cell embryo, the period when zygotic gene expression begins, is accompanied by an increasing ability to repress the activities of promoters and replication origins. Since this repression can be relieved by either butyrate or enhancers, it appears to be mediated through chromatin structure. Here we identify changes in the synthesis and modification of chromatin bound histones that are consistent with this hypothesis. Oocytes, which can repress promoter activity, synthesized a full complement of histones, and histone synthesis up to the early 2-cell stage originated from mRNA inherited from the oocyte. However, while histones H3 and H4 continued to be synthesized in early 1-cell embryos, synthesis of histones H2A, H2B and H1 (proteins required for chromatin condensation) was delayed until the late 1-cell stage, reaching their maximum rate in early 2-cell embryos. Moreover, histone H4 in both 1-cell and 2-cell embryos was predominantly diacetylated (a modification that facilitates transcription). Deacetylation towards the unacetylated and monoacetylated H4 population in fibroblasts began at the late 2-cell to 4-cell stage. Arresting development at the beginning of S-phase in 1-cell embryos prevented both the appearance of chromatin-mediated repression of transcription in paternal pronuclei and synthesis of new histones. These changes correlated with the establishment of chromatin-mediated repression during formation of a 2-cell embryo, and the increase in repression from the 2-cell to 4-cell stage as linker histone H1 accumulates and core histones are deacetylated.

Repression of gene expression at the beginning of mouse development.

The transition from maternal to zygotic gene expression in the mouse occurs in the 2-cell embryo. Previous studies in which DNA was injected into 2-cell embryos revealed that transcription promoters and origins of DNA replication are strongly repressed in cleavage stage embryos unless linked to an embryo-responsive enhancer. Repression also occurs when DNA is injected into the paternal pronucleus of a 1-cell embryo and the injected embryo subsequently undergoes mitosis, except that repression is no longer relieved by enhancers. Here we extend this observation to maternal pronuclei in 1-cell embryos and show that this repression could not be relieved either by linking the promoter to an embryo-responsive enhancer or by inducing hyperacetylation of chromatin inorder to increase its accessibility to transcription factors. However, repression could be relieved by transplanting the injected pronucleus to a 2-cell embryo, even when the recipient cell subsequently underwent mitosis. Both the extent of promoter repression and the ability of enhancers to stimulate promoter activity increased as development proceeded from the early 2-cell stage to the 4-cell stage. Once repression was established in late 2-cell embryos, transplanting an injected 2-cell embryo nucleus back to an early 1-cell embryo failed to restore activity to the injected promoter, even when it was linked to an enhancer. These and other data demonstrate that cytoplasmic factors appear during formation of a 2-cell embryo that can repress promoter activity and activate enhancer activity. These factors are absent from the paternal pronucleus and cytoplasm of early (S-phase arrested) 1-cell embryos. Moreover, the cytoplasm of early 1-cell embryos appears to lack the ability to reprogram expression of genes once they have progressed to the late 2-cell stage in mouse development.

Characterization of potential antagonists of human interleukin 5 demonstrates their cross-reactivity with receptors for interleukin 3 and granulocyte-macrophage colony-stimulating factor.

The ligand-binding alpha-chain of the human interleukin 5 (IL-5) receptor was expressed in its soluble form, lacking the transmembrane and cytoplasmic domains, from recombinant baculovirus. The soluble receptor was used in a scintillation proximity assay to identify two chemical compounds that inhibit binding of human IL-5 to the soluble receptor alpha chain with IC50 of 8 microM and 11 microM. These compounds also inhibited the interaction of human IL-5 with its membrane-bound receptor, composed of the ligand-binding alpha chain and signal-transducing beta chain, and prevented signaling through the receptor. Analysis by surface plasmon resonance and matrix-assisted laser-desorption/ionization mass spectrometry showed that the identified compounds bound irreversibly to the receptor at a 1:1 (mol/mol) ratio, suggesting a covalent interaction with the alpha chain of the human IL-5 receptor. Both compounds also inhibited the interaction of the receptors for interleukin 3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF), which are involved in hematopoietic differentiation and activation of immune cells, thus eliminating them as potential therapeutic agents. The inhibition of the structurally closely related receptors for IL-5, IL-3 and GM-CSF by both compounds, while binding of interleukin-4 to its receptor was not affected, suggests that a similar reactive site exists in the ligand-binding domains of the receptors for IL-5, IL-3 and GM-CSF.

Tachykinin NK3-receptor deficiency does not inhibit pulmonary eosinophilia in allergic mice.

Tachykinins are important in the development of pulmonary inflammation in mice but the tachykinin receptor subtype mediating this response has not been defined. To elucidate the role of tachykinin NK3-receptors on allergen-induced pulmonary inflammation, studies were performed on ovalbumin (OVA) sensitized and challenged mice with genetic disruption of the tachykinin NK3-receptor (NK3-/-). Aerosol OVA (0.5%) challenge produced eosinophil influx into the bronchoalveolar lavage fluid and lung tissue, goblet cell hyperplasia and damage to the airway epithelium of both NK3-/- mice and in wild type control mice (NK3+/+). There was no difference in the magnitude of these allergic inflammatory pulmonary responses between NK3-/- and NK3+/+ mice. These results find no role for tachykinin NK3-receptors on the pulmonary eosinophilia and lung damage after antigen challenge in mice.

Ubiquitous transgenic expression of the IL-23 subunit p19 induces multiorgan inflammation, runting, infertility, and premature death.

p19, a molecule structurally related to IL-6, G-CSF, and the p35 subunit of IL-12, is a subunit of the recently discovered cytokine IL-23. Here we show that expression of p19 in multiple tissues of transgenic mice induced a striking phenotype characterized by runting, systemic inflammation, infertility, and death before 3 mo of age. Founder animals had infiltrates of lymphocytes and macrophages in skin, lung, liver, pancreas, and the digestive tract and were anemic. The serum concentrations of the proinflammatory cytokines TNF-alpha and IL-1 were elevated, and the number of circulating neutrophils was increased. In addition, ubiquitous expression of p19 resulted in constitutive expression of acute phase proteins in the liver. Surprisingly, liver-specific expression of p19 failed to reproduce any of these abnormalities, suggesting specific requirements for production of biologically active p19. Bone marrow transfer experiments showed that expression of p19 by hemopoietic cells alone recapitulated the phenotype induced by its widespread expression, pointing to hemopoietic cells as the source of biologically active p19. These findings indicate that p19 shares biological properties with IL-6, IL-12, and G-CSF and that cell-specific expression is required for its biological activity.

Impaired pulmonary host defense in mice lacking expression of the CXC chemokine lungkine.

Lungkine (CXCL15) is a novel CXC chemokine that is highly expressed in the adult mouse lung. To determine the biologic function of Lungkine, we generated Lungkine null mice by targeted gene disruption. These mice did not differ from wild-type mice in their hematocrits or in the relative number of cells in leukocyte populations of peripheral blood or other tissues, including lung and bone marrow. However, Lungkine null mice were more susceptible to Klebsiella pneumonia infection, with a decreased survival and increased lung bacterial burden compared with infected wild-type mice. Histologic analysis of the lung and assessment of leukocytes in the bronchioalveolar lavage revealed that neutrophil numbers were normal in the lung parenchyma, but reduced in the airspace. The production of other neutrophil chemoattractants in the Lungkine null mice did not differ from that in wild-type mice, and neutrophil migration into other tissues was normal. Taken together, these findings demonstrate that Lungkine is an important mediator of neutrophil migration from the lung parenchyma into the airspace.

Leukocytes expressing green fluorescent protein as novel reagents for adoptive cell transfer and bone marrow transplantation studies.

Transgenic mice expressing green fluorescent protein (GFP) were generated to provide a source of labeled leukocytes for cell transfer studies. The transgene comprises the GFP coding region under the transcriptional control of the chicken ss-actin promoter and human cytomegalovirus enhancer. Mice expressing this GFP transgene were generated in the B6D2 and in the 129SvEv backgrounds. Flow cytometric analysis of cells from the blood, spleen, and bone marrow of these transgenic mice revealed that most leukocytes, including dendritic cells and memory T cells, express GFP. In allogeneic cell transfers, donor GFP+ splenocytes were detected in the spleen and mesenteric lymph nodes of recipient mice within 2 hours after transfer and for at least 9 days thereafter. In syngeneic experiments using 129-derived GFP+ donor splenocytes, donor cells were detected in multiple tissues of 129 recipients from 2 hours to 3 weeks after transfer. In bone-marrow transplantation experiments using irradiated allogeneic recipients, the percent of GFP+ donor cells in recipients at 3 weeks was comparable to that seen in similar tissues of GFP+ donor mice. These data demonstrate that GFP+ transgenic mice provide a ready source of GFP-expressing primary cells that can be easily monitored after their transfer to recipient animals.