Glucosamine, a naturally occurring amino monosaccharide, suppresses dextran sulfate sodium-induced colitis in rats

Glucosamine, a naturally occurring amino monosaccharide, is widely used to treat osteoarthritis in humans. Furthermore, glucosamine exhibits an anti-inflammatory action by inhibiting the activation of neutrophils, chondrocytes and synoviocytes. Recently, we revealed that glucosamine suppresses cytokine-induced activation of intestinal epithelial cells in vitro. In the present study therefore, we investigated whether glucosamine exhibits the anti-inflammatory effect in vivo, using dextran sulfate sodium (DSS)-induced colitis in rats, a model of inflammatory bowel diseases (IBD). The results indicated that glucosamine improved the clinical symptoms (evaluated by disease activity index), and suppressed colonic inflammation (evaluated by colon length and weight/length ratio) and tissue injury (evaluated by histological damage score) in DSS-induced colitis. Furthermore, glucosamine inhibited the activation of intestinal epithelial cells, as evidenced by the suppressed phosphorylation of NF-kappaB in the intestinal mucosa of DSS-induced colitis. Collectively, these observations suggest that glucosamine is likely to suppress the activation of intestinal epithelial cells in vivo, thereby possibly exhibiting anti-inflammatory action in a DSS-induced rat colitis model. Thus, glucosamine could prove to be a useful agent for IBD.

Circulating micrometastases of esophageal cancer detected by carcinoembryonic antigen mRNA reverse transcriptase-polymerase chain reaction: clinical implications

In some patients without distant metastases according to conventional preoperative investigations, relapse occurs in distant organs within a few years after radical resection of esophageal cancer. Various attempts have been made to detect micrometastases that are not found by conventional techniques. A quantitative real-time reverse-transcriptase polymerase chain reaction was used to detect messenger RNA for carcinoembryonic antigen in 147 blood samples from 49 patients scheduled for radical resection of esophageal cancer at Juntendo University Hospital between September 2003 and June 2004. The number of circulating cancer cells was assessed and the clinical significance of detecting such micrometastases was analyzed. Multivariate analysis showed that positivity of this assay was significantly associated with pT1 or pT2 disease and stage III or stage IV disease. Patients with more than 40-50 carcinoembryonic antigen mRNA copies among 10(4) normal cells on quantitative analysis had a higher recurrence rate. The number of tumor cells circulating in the blood may have more influence on the prognosis of esophageal cancer than the presence of tumor cells.

Adult-onset familial pulmonary fibrosis in Japanese brothers

Two Japanese brothers were diagnosed in their 20s with familial pulmonary fibrosis, the pathological findings of which were consistent with usual interstitial pneumonia (UIP). However, an atypical characteristic was observed in the lungs of these brothers; 2-mm areas of 'honeycomb' were identified throughout the lungs, which is smaller than the generally observed 5-10 mm honeycombing seen in UIP. Fibroblastic foci were demonstrated in the second eldest brother, but not in the eldest, which indicates that the lungs of the eldest brother was in a more advanced stage of fibrosis. Their youngest brother and parents have no clinical evidence of pulmonary fibrosis. All five family members had low values for the diffusion capacity of the lung for carbon monoxide (DLCO), suggesting the presence of an inheritable disease and the existence of different phenotypes. The genomic DNA of the affected brothers was sequenced for the reported surfactant protein C (SP-C) gene mutations in patients with familial pulmonary fibrosis, but none was documented. It is necessary to clarify the presence of novel gene mutations of SP-C or other genes to explain these particular pathological findings and the low DLCO observed in this family.

Evaluation of the effect of human beta-defensins on neutrophil apoptosis

Peptide antibiotics possess the potent antimicrobial activities against invading microorganisms and contribute to the innate host defense. Antimicrobial human beta-defensins (hBDs) not only exhibit potent bactericidal activities against Gram-negative and Gram-positive bacteria but also function as immunomodulatory molecules by inducing cytokine and chemokine production and inflammatory and immune cell activation. Neutrophil is a critical effector cell in host defense against microbial infection, and its lifespan is regulated by various pathogen- and host-derived substances. Here, to further evaluate the role of hBDs in innate immunity, we investigated the action of hBD-1 to -4 on neutrophil apoptosis. Neutrophil apoptosis was assessed using human blood neutrophils based on the morphological changes. Of note, hBD-3 most potently suppressed neutrophil apoptosis among hBD-1 to -4, accompanied with the down-regulation of truncated Bid (a pro-apoptotic protein), up-regulation of Bcl-x(L) (an anti-apoptotic protein) and inhibition of mitochondrial membrane potential change and caspase 3 activity. Furthermore, we revealed that neutrophils expressed CC chemokine receptor (CCR) 6, and the action of hBD-3 was completely abrogated by a neutralizing anti-CCR6 mAb. Collectively, these observations suggest that hBDs, especially hBD-3, can not only kill bacteria but also modulate (suppress) neutrophil apoptosis via the action on CCR6. Suppression of neutrophil apoptosis results in the prolongation of their lifespan and may be advantageous for the host defense against bacterial invasion.

Activation of Integrin-Linked Kinase Is a Critical Prosurvival Pathway Induced in Leukemic Cells by Bone Marrow–Derived Stromal Cells

Integrin-linked kinase (ILK) directly interacts with beta integrins and phosphorylates Akt in a phosphatidylinositol 3-kinase (PI3K)-dependent manner. In this study, we examined the functional role of ILK activation in leukemic and bone marrow stromal cells on their direct contact. Coculture of leukemic NB4 cells with bone marrow-derived stromal mesenchymal stem cells (MSC) resulted in robust activation of multiple signaling pathways, including ILK/Akt, extracellular signal-regulated kinase 1/2 (ERK1/2), signal transducers and activators of transcription 3 (STAT3), and Notch1/Hes. Blockade of PI3K or ILK signaling with pharmacologic inhibitors LY294002 or QLT0267 specifically inhibited stroma-induced phosphorylation of Akt and glycogen synthase kinase 3beta, suppressed STAT3 and ERK1/2 activation, and decreased Notch1 and Hes1 expression in leukemic cells. This resulted in induction of apoptosis in both leukemic cell lines and in primary acute myelogenous leukemia samples that was not abrogated by MSC coculture. In turn, leukemic cells growing in direct contact with bone marrow stromal elements induce activation of Akt, ERK1/2, and STAT3 signaling in MSC, accompanied by significant increase in Hes1 and Bcl-2 proteins, which were all suppressed by QLT0267 and LY294002. In summary, our results indicate reciprocal activation of ILK/Akt in both leukemic and bone marrow stromal cells. We propose that ILK/Akt is a proximal signaling pathway critical for survival of leukemic cells within the bone marrow microenvironment. Hence, disruption of these interactions by ILK inhibitors represents a potential novel therapeutic strategy to eradicate leukemia in the bone marrow microenvironment by simultaneous targeting of both leukemic cells and activated bone marrow stromal cells.

PML-RARα and AML1–ETO translocations are rarely associated with methylation of the RARβ2 promoter

The acute promyelocytic leukemia-specific PML-RARalpha fusion protein is a dominant-negative transcriptional repressor of retinoic acid receptor (RAR) target genes, which recruits HDAC and corepressor proteins and inhibits coactivators. Another oncogenic transcription factor, AML1-ETO, was proposed to cause an HDAC-dependent repression of RAR target genes. The RAR target RARbeta2 gene has been reported to be frequently silenced by hypermethylation in many types of cancer cells. We examined the methylation status of the RARbeta2 and asked if demethylation could reverse ATRA resistance in ATRA-resistant PML-RARalpha and AML1-ETO-positive cells. PML-RARalpha positive NB4 and its ATRA-resistant subvariant MR2 and AML1-ETO expressing Kasumi-1 cells had heterozygous methylation of RARbeta2. Although DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine partially reversed RARbeta2 CpG methylation in these cells, it did not significantly enhance ATRA-induced RARbeta2 mRNA expression and induction of maturation. However, the histone acetylase inhibitor SAHA combined with ATRA significantly reactivated RARbeta2 mRNA both in NB4 and MR2 cells with degradation of PML-RARalpha, which was associated with maturation. In contrast, SAHA did not affect AML1-ETO levels and failed to induce RARbeta2 expression and maturation in Kasumi-1 cells. In primary AML samples, RARbeta2 expression was uniformly low; however, no specific correlation was observed between the methylation of the RARbeta2 gene and expression of the fusion proteins, PML-RARalpha, and AML1-ETO. These results demonstrate that oncogenic PML-RARalpha and AML1-ETO translocations are rarely associated with RARbeta2 promoter methylation in primary AML samples.

Up-regulation of MDR1 and induction of doxorubicin resistance by histone deacetylase inhibitor depsipeptide (FK228) and ATRA in acute promyelocytic leukemia cells

The multidrug resistance 1 (MDR1) gene product P-glycoprotein (P-gp) is frequently implicated in cross-resistance of tumors to chemotherapeutic drugs. In contrast, acute promyelocytic leukemia (APL) cells do not express MDR1 and are highly sensitive to anthracyclines. The combination of ATRA and the novel histone deacetylase inhibitor (HDACI) depsipeptide (FK228) induced P-gp expression and prevented growth inhibition and apoptosis in NB4 APL cells subsequently exposed to doxorubicin (DOX). ATRA/FK228 treatment after exposure to DOX, however, enhanced apoptosis. Both agents, ATRA or FK228, induced MDR1 mRNA. This effect was significantly enhanced by ATRA/FK228 administered in combination, due in part to increased H4 and H3-Lys9 acetylation of the MDR1 promoter and recruitment of the nuclear transcription factor Y alpha (NFYA) transcription activator to the CCAAT box. Cotreatment with specific P-gp inhibitor PSC833 reversed cytoprotective effects of ATRA/FK228. G1 cell-cycle arrest and p21 mRNA induction were also observed in response to ATRA/FK228, which may restrict DOX-induced apoptosis of cells in G2 phase. These results indicate that epigenetic mechanisms involving NF-YA transcription factor recruitment and histone acetylation are activated by ATRA and HDACI, induce MDR1 in APL cells, and point to the critical importance of mechanism-based sequential therapy in future clinical trials that combine HDAC inhibitors, ATRA, and anthracyclines.

Glucosamine, a naturally occurring amino monosaccharide, suppresses the ADP-mediated platelet activation in humans

OBJECTIVE

To evaluate the anti-thrombotic action of glucosamine, a naturally occurring amino monosaccharide, platelets were stimulated with ADP in the presence of glucosamine, and its effects on platelet functions were examined.

MATERIALS AND METHODS

Human platelet-rich plasma was stimulated with 2.5 microM ADP in the presence of glucosamine (0.01 approximately 1 mM) or other aminosugars (N-acetyl-glucosamine, galactosamine or N-acetyl-galactosamine, 1 mM), and platelet aggregation was monitored. Furthermore, the effects of glucosamine on the thromboxane A2 production, release of granule contents, intracellular calcium mobilization and phosphorylation of Syk (a 72 kD protein tyrosine kinase) were evaluated following ADP-stimulation. In addition, the binding of [3H] ADP to its receptors was examined.

RESULTS

Glucosamine (>0.01 mM) dose-dependently suppressed platelet aggregation in response to ADP (p < 0.05), whereas N-acetyl-glucosamine, galactosamine or N-acetyl-galactosamine (1 mM) did not affect the ADP-induced platelet aggregation. Furthermore, glucosamine (>0.1 mM) inhibited the extracellular release of granule contents (ATP and platelet factor 4) and production of thromboxane A2 from ADP-stimulated platelets (p < 0.05). Moreover, glucosamine significantly repressed the intracellular calcium mobilization at >0.1 mM and phosphorylation of Syk at >0.01 mM upon ADP-stimulation (p < 0.05). In addition, glucosamine (>0.1 mM) inhibited the binding of ADP to its receptors (p < 0.05).

CONCLUSION

Glucosamine is able to suppress platelet aggregation, release of granule constituents, thromboxane A2 production, calcium mobilization and phosphorylation of Syk possibly via the inhibition of ADP-binding to the receptors. Glucosamine could be expected as a novel anti-platelet agent for thrombotic disorders due to its suppressive actions on platelets.

Acid exposure potentiates intercellular adhesion molecule-1 and e-cadherin expression on A549 alveolar lining epithelial cells

Recruitment of neutrophils into the alveoli plays a major role in the pathogenesis of acid-induced pneumonitis. Preliminary data suggest that alteration in the expression of cellular adhesion molecules on the airway epithelial cells may play an important role in the recruitment of neutrophils following acid-induced lung injury. The aim of this study was to evaluate the change in the surface expression of intercellular adhesion molecule-1 (ICAM-1), E-cadherin, and vascular cell adhesion molecule -1 (VCAM-1) on acid-exposed A549 alveolar lining epithelial cells by flow cytometry and confocal laser microscopy. Acid exposure changed cell morphology, increased cell adhesion after trypsin-EDTA treatment, and up-regulated the expression of ICAM-1 and E-cadherin but not of VCAM-1. The up-regulation of ICAM-1 expression will induce the dysfunction of epithelial cells with or without accumulation of neutrophils in air spaces. Because the distribution of E-cadherin in acid-exposed A549 cells was at the sites where the cells attached to culture dish but not at the intercellular junctions between adjoining cells, up-regulated expression of E-cadherin will rather result in alterations of epithelial morphology and function of epithelial barrier. In addition, pentoxifylline suppressed the up-regulation of ICAM-1 and E-cadherin expression and may therefore attenuated the airway inflammation in acid-induced pneumonitis.

Modulation of human beta-defensin-2 transcription in pulmonary epithelial cells by lipopolysaccharide-stimulated mononuclear phagocytes via proinflammatory cytokine production

Human beta-defensin (hBD)-2, a cationic antimicrobial peptide primarily induced in epithelial cells in response to inflammatory stimuli, plays an important role in host defense. To elucidate the expression mechanism of hBD-2 in the lung, we investigated the modulation of hBD-2 transcription in pulmonary epithelial cells by mononuclear phagocytes stimulated with LPS. Coculture of A549 pulmonary epithelial cells with Mono-Mac-6 monocytic cells in the presence of Escherichia coli LPS markedly up-regulated hBD-2 promoter activity, whereas A549 alone did not respond to LPS to activate the hBD-2 promoter. Furthermore, IL-1beta and TNF-alpha in the culture supernatants from LPS-stimulated monocytic cells activated the hBD-2 promoter in A549 cells. Of note, IL-1beta was more potent than TNF-alpha in this effect. In addition, a mutation of the NF-kappaB site at -200 (pkappaB1 site) completely abolished this IL-1beta- and TNF-alpha-induced hBD-2 promoter activation, whereas NF-kappaB inhibitors (MG-132 and helenalin) strongly suppressed it. Moreover, electrophoretic mobility shift assay suggested that NF-kappaB, consisting of p65-p50 heterodimer, could bind to the pkappaB1 site in cytokine-stimulated A549 cells. Interestingly, flow cytometric analysis revealed that A549 cells expressed CD14 but lacked Toll-like receptor 4, which may account for the hyporesponsiveness of A549 cells to LPS. Taken together, these results suggest that hBD-2 expression in pulmonary epithelial cells is modulated by NF-kappaB via the actions of IL-1beta and TNF-alpha produced by LPS-stimulated mononuclear phagocytes.

NF-kappa B-mediated transcriptional regulation of human beta-defensin-2 gene following lipopolysaccharide stimulation

beta-Defensins are cationic peptides with broad-spectrum antimicrobial activities that contribute to innate host defense. Among human beta-defensins (hBDs), hBD-2 is up-regulated in epithelial tissues and mononuclear phagocytes in response to bacterial infection and proinflammatory cytokines. However, little is known about the molecular mechanism of hBD-2 gene regulation. Here, we investigated lipopolysaccharide (LPS)-mediated transcriptional regulation of the hBD-2 gene by focusing on the roles of NF-kappa B, STAT, and NF-IL-6 sites in mononuclear phagocytes using RAW264.7 cells, which are sensitive to LPS. Luciferase reporter analyses demonstrated that two NF-kappa B sites were essential for full LPS responsiveness of the hBD-2 gene. Further, both NF-kappa B sites were also crucial for basal transcriptional activity. In contrast, neither the NF-IL-6 nor STAT binding site was required for LPS-induced hBD-2 transcription. Electrophoretic mobility shift assay indicated that in unstimulated cells, NF-kappa B p50 homodimer bound to both NF-kappa B sites, whereas the p65-p50 heterodimer formed complexes with these sites following LPS stimulation. Together, these observations indicate that NF-kappa B plays an important role in the regulation of hBD-2 gene expression in response to LPS.

Role of CCAAT/enhancer-binding protein site in transcription of human neutrophil peptide-1 and -3 defensin genes

The human neutrophil defensins (human neutrophil peptides (HNPs)), major components of azurophilic granules, contribute to innate and acquired host immunities through their potent antimicrobial activities and ability to activate T cells. Despite being encoded by nearly identical genes, HNP-1 is more abundant in the granules than HNP-3. We investigated the regulation of HNP-1 and HNP-3 expression at the transcriptional level using a promyelocytic HL-60 cell line. Luciferase analysis showed that transcriptional levels of HNP-1 and HNP-3 promoters were equivalent and that an approximately 200-bp region identical between promoters was sufficient for transcriptional activity. Furthermore, overlapping CCAAT/enhancer-binding protein (C/EBP) and c-Myb sites in the region were found to be required for efficient transcription. Gel mobility shift assay demonstrated that C/EBPalpha predominantly bound to the C/EBP/c-Myb sites using HL-60 nuclear extracts. No specific binding to C/EBP/c-Myb sites was observed in nuclear extracts from mature neutrophils, which expressed neither C/EBPalpha protein nor HNP mRNAs. Taken together, these findings suggest that the difference in the amounts of HNP-1 and HNP-3 peptides in neutrophils is caused by posttranscriptional regulation and that C/EBPalpha plays an important role in the transcription of HNP genes in immature myeloid cells.

Evaluation of the expression of human CAP18 gene during neutrophil maturation in the bone marrow

To understand the gene expression of CAP18 (18-kDa cationic antibacterial protein), a member of cathelicidins, we evaluated mRNA and protein expression of CAP18 using human bone marrow cells and mature neutrophils. Northern blot analysis revealed that CAP18 mRNA was expressed more abundantly in bone marrow cells than mature neutrophils, whereas Western blot analysis indicated that CAP18 protein was more abundant in mature neutrophils than bone marrow cells. Consistent with this, in situ hybridization using bone marrow cells demonstrated that the expression of CAP18 mRNA was neutrophil lineage-specific and was observed primarily in myelocytes (>95%) with limited expression in more immature cells (promyelocytes) and mature cells (metamyelocytes, band cells, and segmented neutrophils). Furthermore, immunohistochemical study indicated that, coincident with the increase of CAP18 mRNA levels, CAP18-positive cells increased markedly at myelocyte stage, and the increased levels remained almost constant (>95%) in metamyelocytes, band cells, and segmented neutrophils, although the mRNA levels were remarkably reduced in these cells. Together these observations indicate that CAP18 gene transcription likely occurs lineage- and stage-specifically at the myelocyte stage of neutrophil maturation in the bone marrow and results in the synthesis and cytoplasmic accumulation of CAP18, which is present in the subsequent stages of neutrophil maturation.

Isolation of cDNA encoding guinea pig neutrophil cationic antibacterial polypeptide of 11 kDa (CAP11) and evaluation of CAP11 mRNA expression during neutrophil maturation

Neutrophils contain various antibacterial polypeptides and proteins in the granules that contribute to the killing of microorganisms. Recently, we have purified a cationic antibacterial polypeptide of 11 kDa (CAP11) from guinea pig neutrophil granules. CAP11 is a homodimer of G1LRKKFRKTRKRIQKLGRKIGKTGRKVWKAWREYGQIPYPCRI43 joined with one disulfide bond. In this study, to understand the regulation of CAP11 expression, we isolated and analyzed cDNA encoding CAP11. Furthermore, we investigated the expression of CAP11 mRNA during neutrophil maturation and localization of CAP11 among neutrophil granule subsets. Sequence analysis of CAP11 cDNA isolated from guinea pig bone marrow cells using rapid amplification of cDNA ends technique indicated that CAP11 is synthesized as a precursor comprising 178 amino acid residues, which is composed of a signal peptide (N-terminal 29 residues), a propeptide (106 residues), and a C-terminal mature peptide (43 residues). Interestingly, the predicted CAP11 precursor displayed the characteristic features of cathelicidins, a novel protein family of antibacterial polypeptides with a conserved cathelin-like pro-region and a variable C-terminal antibacterial domain. Northern blot and Western blot analyses using neutrophils, macrophages, eosinophils, mononuclear cells, and bone marrow cells revealed that only neutrophils and bone marrow cells expressed CAP11 mRNA and contained CAP11, suggesting that expression of CAP11 is neutrophil lineage-specific. Furthermore, Northern blot analysis using bone marrow cells separated according to their maturation stages showed that CAP11 mRNA was predominantly expressed in the cells at later stages of neutrophil maturation. Consistent with this, in situ hybridization using CAP11-specific cRNA probe demonstrated that CAP11 mRNA was primarily expressed at metamyelocyte stage. In addition, extracellular release assay revealed that CAP11 was readily released from neutrophils accompanied with gelatinase by low concentrations of N-formyl-Met-Leu-Phe without release of specific and azurophil granule components, and CAP11 was found to be exclusively present in the fraction containing gelatinase granules, prepared by Percoll density gradient centrifugation. Together these observations indicate that CAP11 is a member of cathelicidin family and its mRNA is preferentially expressed at the later stage of neutrophil maturation (i.e. metamyelocyte stage). Furthermore, CAP11 may be stored in the granule subset, possibly the gelatinase granule.

Roles of p53 mutation in cell line establishment and identification of the minimum transactivation and transform suppression domains

The mutation of the p53 tumour suppressor gene is the most frequently recognised genetic alteration in human cancer. We recently showed that the frequency of p53 gene mutations in oral squamous cell carcinomas (SCCs) from which cell lines were established (group A) did not significantly differ from that in SCCs from which cell lines could not be established (group B), suggesting that the presence of a p53 mutation by itself is not sufficient. To assess the relevance of p53 mutations to cell line establishment, we determined sequences of the mutated genes, constructed the expression plasmids, and compared biological and biochemical activities. Both groups contained typical mutant type mutations at a similar frequency. However, two mutations in group A had strong transforming activity. One of the mutants, codon 306 Stop mutant with C-terminal truncation, was found to have the transactivation and transform suppression activities similar to wild type. The minimum transactivation and transform suppression domains of p53 were thus determined based on analysis of various C-terminal deletions. Activity disappeared between codons 300 and 282, an interval which contains the C-terminal end of the sequence-specific DNA binding domain, which suggests that the DNA binding domain is essential for the above activities.

Response of heat shock element within the human HSP70 promoter to mutated p53 genes

Recent studies have demonstrated that mutation of the p53 gene caused a gain of new functions such as transforming activation, binding to heat shock cognate protein 70 and/or transactivation of a variety of promoters. In the course of seeking the biochemical basis for the gain of these functions, we have noticed the correlation between transforming activity of different mutated p53 genes and their transactivational activity on the human heat shock protein 70 promoter. Analysis of 5' deletion constructs of the heat shock protein 70 promoter showed that some specific elements within the heat shock domain containing two heat shock elements (HSEs) could respond to mutant p53 species but not basic promoter elements such as the TATA box, CCAAT box, and GC box. Subsequently, we identified the HSE as a responsive element using reporter constructs of minimal promoter containing synthetic proximal HSE, distal HSE, or GC/CCAAT box. Further analysis using in vitro mutagenesis of HSE suggests that HSE with heat shock factor binding ability is required for transactivation of the heat shock protein 70 promoter by mutated p53 genes.