[Show abstract][Hide abstract] ABSTRACT: CpG oligodeoxynucleotides (ODNs), resembling bacterial DNA, are currently tested in clinical trials as vaccine adjuvants. They have the nuclease-resistant phosphorothioate bond; the immune responses elicited differ according to the CpG ODN sequence and vaccination method. To develop a CpG ODN that can induce plasmacytoid dendritic cell (pDC)-mediated TH1 immunity through the mucosa, we constructed phosphodiester G9.1 comprising one palindromic CpG motif with unique polyguanosine-runs that allows degradation similar to naturally occurring bacterial DNA.
TH1 and TH2 immunity activation was evaluated by cytokine production pattern and T-bet/GATA-3 ratio in human peripheral blood mononuclear cells and mouse bone marrow cells. Adjuvanticity was evaluated in mice administered G9.1 with diphtheria toxoid (DT) through nasal vaccination.
G9.1 exhibited stronger IFN-α-inducing activity than A-class CpG ODN2216 and increased T-bet/GATA-3 ratio by enhancing T-bet expression. Nasally administered G9.1 plus DT induced DT-specific mucosal IgA and serum IgG, but not IgE, responses with antitoxin activity in C57BL/6 and BALB/c mice, possibly due to IFN/BAFF production. Induction of TH1, but not TH2, -type Abs depended completely on pDCs, the first in vivo demonstration by CpG ODNs.
G9.1 is a promising mucosal adjuvant for induction of pDC-mediated TH1 immunity.
[Show abstract][Hide abstract] ABSTRACT: House dust mite (HDM), the most common allergen, activate both the IgE-associated and innate immune responses. To clarify the process of sensitization, we investigated the role of the CCL21, CCL19, and CCR7 axis in a mouse model of HDM-induced allergic asthma. HDM inhalation without systemic immunization resulted in a HDM-specific IgE response. CCR7-knockout (CCR7KO) mice exhibited greater airway inflammation and IgE responses compared to wild-type mice. We examined FoxP3 expression in these mice to clarify the contribution of regulatory cells to the responses. FoxP3 expression was higher in the lungs but not in the lymph nodes of CCR7KO mice compared to wild-type mice. In CCR7KO mice, FoxP3-positive cells were found in lung, but we observed higher release of IL-13, IL-5, TGF-β, IL-17, and HMGB1 in bronchoalveolar lavage fluid. We demonstrate here that immuno-regulation through CCR7 expression in T cells plays a role in HDM-specific sensitization in the airway.
[Show abstract][Hide abstract] ABSTRACT: Interstitial cells of Cajal (ICC) generate electrical rhythmicity and transduce neural signals in the gastrointestinal musculature. ICC express the proto-oncogene c-kit, a receptor tyrosine kinase, and are identified morphologically by c-Kit immunoreactivity. The c-kit gene is allelic with the murine white-spotting locus W, and mutations of c-kit are known as W mutations. W mutations affect various developmental aspects of hematopoietic cells, germ cells, melanocytes, mast cells and ICC. We examined W(jic)/W(jic) mutant mice that have a mutation in the tyrosine kinase domain resulting in severe loss of protein function. W(jic)/W(jic) homozygotes exhibited white coats and black eyes. The gross morphology of the gastrointestinal tract showed no abnormality in mutant mice other than a forestomach papilloma. In the stomach, intramuscular ICC (ICC-IM) were missing, and myenteric ICC (ICC-MY) were reduced in number. In the small intestine, the number of ICC-MY was severely reduced; however there was a normal distribution of deep muscular plexus ICC (ICC-DMP). In the cecum, the numbers of ICC-IM and ICC-MY were severely depleted. ICC-IM were almost entirely absent in the colon, whereas ICC-MY loss was restricted to the distal colon. Patterns of ICC deficiency were generally similar between W(jic)/W(jic) mice and W/W(v) mutants, which lack a specific type of ICC. The enteric nervous system of the mutant mice appeared normal. From these findings, we conclude that W(jic)/W(jic) mice represent a distinct, novel genotype resulting in a lack of a specific type of ICC in the gastrointestinal musculature.
[Show abstract][Hide abstract] ABSTRACT: Whereas acetylcholine (ACh) acts as a bronchoconstrictor and stimulator of mucus secretion from bronchial epithelium, it acts via alpha7 nicotinic Ach receptors (nAChRs) on macrophages in the airways to exert anti-inflammatory effects by reducing synthesis of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha). Moreover, the effects of ACh are modified by secreted ly-6/urokinase-type plasminogen activator receptor-related peptide-1 (SLURP-1), a positive allosteric modulator of alpha7 nAChR signaling. Our aim was to explore the roles played by SLURP-1 in the pathophysiology of asthma by assessing SLURP-1 expression in the OVA-sensitized murine asthma model and in cultured human bronchial epithelial cells. Using real-time PCR we found that expression of SLURP-1 mRNA is down-regulated in the lungs of asthmatic model mice, as compared to healthy mice. In addition, immunohistochemical studies confirmed the diminished expression of SLURP-1 in the bronchioles of asthmatic mice, and showed it was due to extensive metaplasia of mucus-secreting cells and the concomitant loss of ciliated epithelial cells. Expression of SLURP-1 mRNA and protein was also significantly down-regulated in human epithelial cells stimulated with the pro-inflammatory cytokine interleukin-13 (IL-13), which is related to asthmatic condition. Thus SLURP-1 appears to be down-regulated in both an animal model of asthma and human epithelial cells treated with an inflammatory cytokine related to asthma. Those findings suggest that diminished expression of SLURP-1 in asthma attenuates its negative regulation of airway inflammation, and that perhaps changes in SLURP-1 expression could serve as a marker of airway damage in asthma.
No preview · Article · Aug 2010 · Biochemical and Biophysical Research Communications
[Show abstract][Hide abstract] ABSTRACT: In the gastrointestinal tract, interstitial cells of Cajal (ICC) are the regulatory cells of gut movement. W/W mutant mice that have receptor tyrosine kinase KIT mutation lack ICC along the myenteric plexus layer of small intestine. The development and maintenance of the ICC phenotype have been related to KIT, but the other genes involved in ICC development during embryogenesis are not clear. Our aim was to identify ICC-specific genes in the embryonic stage. We examined genes that are expressed less in ICC-deficient W/W mice than in wild type (WT) at embryonic day 14 (E14) in order to clarify the genes associated with the ICC development using subtractive hybridization and microarray. Among them, we identified msh-like 2 (msx2) and neurotrophic tyrosine kinase receptor type 2 (ntrk2). Using real-time PCR, msx2 and ntrk2 were found to be expressed at significantly lower levels in W/W than in WT during embryogenesis. Msx2 immunoreactivity was high in the WT small intestine. These data suggest that the gene expressions of ntrk2 and msx2 were significantly suppressed in KIT mutant mouse embryo and neonate and that these genes are likely to regulate ICC development.
No preview · Article · Jun 2010 · Biochemical and Biophysical Research Communications
[Show abstract][Hide abstract] ABSTRACT: Mammalian secreted lymphocyte antigen-6/urokinase-type plasminogen activator receptor-related peptide-1 (SLURP-1) is a positive allosteric ligand for alpha7 nicotinic acetylcholine (ACh) receptors (alpha7 nAChRs) that potentiates responses to ACh and elicits proapoptotic activity in human keratinocytes. Mutations in the gene encoding SLURP-1 have been detected in patients with Mal de Meleda, a rare autosomal recessive skin disorder characterized by transgressive palmoplantar keratoderma. On the basis of these findings, SLURP-1 is postulated to be involved in regulating tumor necrosis factor-alpha (TNF-alpha) release from keratinocytes and macrophages via alpha7 nAChR-mediated pathways. In the present study, we assessed SLURP-1 expression in lung tissue from C57BL/6J mice to investigate the functions of SLURP-1 in pulmonary physiology and pathology. Immunohistochemical and in situ hybridization analyses revealed expression of SLURP-1 protein and mRNA, respectively, exclusively in ciliated bronchial epithelial cells. This was supported by Western blotting showing the presence of the 9.5-kDa SLURP-1 protein in whole-lung tissue and trachea. In addition, high-affinity choline transporter (CHT1) was detected in apical regions of bronchial epithelial cells and in neurons located in the lamina propria of the bronchus, suggesting that bronchial epithelial cells are able to synthesize both SLURP-1 and ACh. We also observed direct contact between F4/80-positive macrophages and bronchial epithelial cells and the presence of invading macrophages in close proximity to CHT1-positive nerve elements. Collectively, these results suggest that SLURP-1 contributes to the maintenance of bronchial epithelial cell homeostasis and to the regulation of TNF-alpha release from macrophages in bronchial tissue.
Full-text · Article · Sep 2009 · Journal of Neuroscience Research
[Show abstract][Hide abstract] ABSTRACT: Platelet-derived growth factor receptors (PDGFRs) belong to the same kinase group as c-Kit receptor tyrosine kinase that is specifically expressed in the interstitial cells of Cajal (ICC) in the gastrointestinal tract. In this study, we examined PDGFRα immunoreactivity in the murine gastrointestinal tract. PDGFRα-immunopositive (PDGFRα-ip) cells were observed in the musculature in all parts of the gastrointestinal tract. Although PDGFRα-ip cells were distinct from ICC and neurons, these cells were closely associated with intramuscular ICC and enteric nerve fibers. In the myenteric layer, PDGFRα-ip cells formed a cellular network with their ramified processes and encompassed myenteric ganglia. Numerous PDGFRα-ip cells were observed in the subserosal plane and showed a multipolar shape. The distribution pattern of the PDGFRα-ip cells in the ICC-deficient W
mutant mice was the same as that in normal mice. PDGFRα-ip cells that showed intense immunoreactivity of SK3 potassium channel were considered to correspond to fibroblast-like cells or non-Cajal interstitial cells. Our observations suggest that PDGFRα-ip cells are basic cellular elements throughout the gastrointestinal musculature and are involved in the gastrointestinal functions.
[Show abstract][Hide abstract] ABSTRACT: Interstitial cells of Cajal (ICC) are important regulatory cells generating electrical rhythmicity and transducing neural signals in the gastrointestinal musculature. ICC express the proto-oncogene c-kit, a receptor tyrosine kinase, and can be examined morphologically using the c-Kit antibody. The c-kit gene is allelic with the murine white-spotting locus W, and the c-kit mutation (W mutation) affects various aspects of hematopoietic cells, germ cells, melanocytes, mast cells, and ICC. Heterozygous W/W( v) mutant mice lack a specific type of ICC and have been used to reveal its function. To search for a new model that lacks a specific type of ICC, we examined homozygous W( v)/W( v) black-eyed-white mice that are viable with anemia. Results showed the principal patterns of ICC deficiency were the same between the W/W( v) and W( v)/W( v) mutants. In the stomach of both mice, intramuscular ICC (ICC-IM) were missing and myenteric ICC (ICC-MY) were reduced in number. In the small intestine, the number of ICC-MY was severely reduced in spite of a normal distribution of deep muscular plexus ICC (ICC-DMP). The cecum also exhibited fewer reduced. ICC-IM in the colon were almost entirely missing, whereas ICC-MY were reduced only in the distal colon. In the small intestine and colon, the number of remaining ICC-MY in W( v)/W( v) mice was greater than that in W/W( v) mice. The enteric nervous system of the two mutant mice showed normal characteristics. From these findings, we conclude that W( v)/W( v) mice represent a new genotype that lacks a part of the ICC in its gastrointestinal musculature.
Preview · Article · Nov 2007 · Archives of Histology and Cytology
[Show abstract][Hide abstract] ABSTRACT: CpG DNA induces plasmacytoid dendritic cells (pDC) to produce type I IFN and chemokines. However, it has not been fully elucidated how the TLR9 signaling pathway is linked to these gene expressions. We examined the mechanisms involving the TLR9 and type I IFN signaling pathways, in relation to CpG DNA-induced IFN-alpha, IFN regulatory factor (IRF)-7, and chemokines CXCL10 and CCL3 in human pDC. In pDC, NF-kappaB subunits p65 and p50 were constitutively activated. pDC also constitutively expressed IRF-7 and CCL3, and the gene expressions seemed to be regulated by NF-kappaB. CpG DNA enhanced the NF-kappaB p65/p50 activity, which collaborated with p38 MAPK to up-regulate the expressions of IRF-7, CXCL10, and CCL3 in a manner independent of type I IFN signaling. We then examined the pathway through which IFN-alpha is expressed. Type I IFN induced the expression of IRF-7, but not of IFN-alpha, in a NF-kappaB-independent way. CpG DNA enabled the type I IFN-treated pDC to express IFN-alpha in the presence of NF-kappaB/p38 MAPK inhibitor, and chloroquine abrogated this effect. With CpG DNA, IRF-7, both constitutively and newly expressed, moved to the nuclei independently of NF-kappaB/p38 MAPK. These findings suggest that, in CpG DNA-stimulated human pDC, the induction of IRF-7, CXCL10, and CCL3 is mediated by the NF-kappaB/p38 MAPK pathway, and that IRF-7 is activated upstream of the activation of NF-kappaB/p38 MAPK in chloroquine-sensitive regulatory machinery, thereby leading to the expression of IFN-alpha.
Full-text · Article · Nov 2006 · The Journal of Immunology