Lipid extract of Mycoplasma penetrans proteinase K-digested lipid-associated membrane proteins rapidly activates NF-kappaB and activator protein 1

Enrichment of Bacterial Lipoproteins and Preparation of N-terminal Lipopeptides for Structural Determination by Mass Spectrometry

Lipoproteins are important constituents of the bacterial cell envelope and potent activators of the mammalian innate immune response. Despite their significance to both cell physiology and immunology, much remains to be discovered about novel lipoprotein forms, how they are synthesized, and the effect of the various forms on host immunity. To enable thorough studies on lipoproteins, this protocol describes a method for bacterial lipoprotein enrichment and preparation of N-terminal tryptic lipopeptides for structural determination by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Expanding on an established Triton X-114 phase partitioning method for lipoprotein extraction and enrichment from the bacterial cell membrane, the protocol includes additional steps to remove non-lipoprotein contaminants, increasing lipoprotein yield and purity. Since lipoproteins are commonly used in Toll-like receptor (TLR) assays, it is critical to first characterize the N-terminal structure by MALDI-TOF MS. Herein, a method is presented to isolate concentrated hydrophobic peptides enriched in N-terminal lipopeptides suitable for direct analysis by MALDI-TOF MS/MS. Lipoproteins that have been separated by Sodium Dodecyl Sulfate Poly-Acrylamide Gel Electrophoresis (SDS-PAGE) are transferred to a nitrocellulose membrane, digested in situ with trypsin, sequentially washed to remove polar tryptic peptides, and finally eluted with chloroform-methanol. When coupled with MS of the more polar trypsinized peptides from wash solutions, this method provides the ability to both identify the lipoprotein and characterize its N-terminus in a single experiment. Intentional sodium adduct formation can also be employed as a tool to promote more structurally informative fragmentation spectra. Ultimately, enrichment of lipoproteins and determination of their N-terminal structures will permit more extensive studies on this ubiquitous class of bacterial proteins.

Mycoplasma fermentans inhibits the activity of cellular DNA topoisomerase I by activation of PARP1 and alters the efficacy of its anti-cancer inhibitor

To understand the effects of the interaction between Mycoplasma and cells on the host cellular function, it is important to elucidate the influences of infection of cells with Mycoplasma on nuclear enzymes such as DNA Topoisomerase type I (Topo I). Human Topo I participates in DNA transaction processes and is the target of anti-cancer drugs, the camptothecins (CPTs). Here we investigated the mechanism by which infection of human tumor cells with Mycoplasma fermentans affects the activity and expression of cellular Topo I, and the anti-cancer efficacy of CPT. Human cancer cells were infected or treated with live or sonicated M. fermentans and the activity and expression of Topo I was determined. M. fermentans significantly reduced (by 80%) Topo I activity in the infected/treated tumor cells without affecting the level of Topo I protein. We demonstrate that this reduction in enzyme activity resulted from ADP-ribosylation of the Topo I protein by Poly-ADP-ribose polymerase (PARP-1). In addition, pERK was activated as a result of the induction of the MAPK signal transduction pathway by M. fermentans. Since PARP-1 was shown to be activated by pERK, we concluded that M. fermentans modified the cellular Topo I activity by activation of PARP-I via the induction of the MAPK signal transduction pathway. Moreover, the infection of tumor cells with M. fermentans diminished the inhibitory effect of CPT. The results of this study suggest that modification of Topo I activity by M. fermentans may alter cellular gene expression and the response of tumor cells to Topo I inhibitors, influencing the anti-cancer capacity of Topo I antagonists.

Anti-Inflammatory Effect of Dohongsamultang through Inhibition of Nuclear Factor-κB Activation in Peripheral Blood Mononuclear Cells of Patients with Cerebral Infarction

The Korean indigenous medicine "Dohongsamultang (DHSMT)" has long been used for various cerebrovascular diseases. However, the exact mechanism for the anti-inflammatory effect of DHSMT is not completely understood. The aim of the present study is to elucidate how DHSMT modulates the inflammatory reaction in lipopolysaccaride (LPS)-stimulated peripheral mononuclear cells from cerebral infarction (CI) patients. Production and expression of cytokine was measured via the ELISA and RT-PCR methods. The level of nuclear factor-kappa B (NF-κB)/Rel A protein and NF-κB DNA binding activity were determined via the Western blot analysis and transcription factor enzyme-linked immunoassay. It showed that DHSMT inhibited the production of TNF-α, IL-1β, and IL-6 induced by LPS in a dose-dependent manner ( p < 0.05). The maximal inhibition rates for TNF-α, IL-1β, and IL-6 production by DHSMT were about 50.18%, 32.13%, and 38.03%, respectively. DHSMT inhibited the TNF-α mRNA expression in a dose-dependent manner. We also showed that the inhibitory effect of DHSMT is through the suppression of the NF-κB pathway. The study suggests an important molecular mechanism by GMGHT to reduce inflammation, which might explain its beneficial effect in the regulation of inflammatory reactions.

Mycoplasma hyopneumoniae induces pro-inflammatory cytokine and nitric oxide production through NFκB and MAPK pathways in RAW264.7 cells

In the present study, we confirmed the ability of M. hyopneumoniae to induce the secretion of large amount of proinflammatory cytokine and nitric oxide (NO) in murine macrophage RAW 264.7 cells. Moreover, M. hyopneumoniae-induced activation of the MAPK and NF-кB pathways by phosphorylation of ERK1/2, p38 and JNK/SAPK and by dissociation of IκB from NF-κB. Translocation of transcription factor NF-κB and its binding was confirmed through western blot and electromobility shift assay. From these results, we further hypothesized that these signal proteins were involved in M. hyopneumoniae-induced proinflammatory cytokines and NO productions in macrophages. Hence, we utilized specific blockers of MAPK and NF-κB to investigate the signaling pathway involvement in cytokine and NO production through pharmacological approaches. The results demonstrated significant inhibition of TNF-α, IL-1β, IL-6 and NO by MAPK inhibitors. NF-κB inhibitor PDTC significantly inhibited IL-1β and NO production. These findings contribute to the understanding of the mechanisms of immune reactivity and may ultimately prove useful in the development of new therapeutic strategies. In summary, we found critical evidence for the involvement of NF-κB and MAPK signaling pathways in the upregulation of proinflammatory cytokine and NO induced by M. hyopneumoniae.

Molecular cloning, expression, and characterization of a Ca2+-dependent, membrane-associated nuclease of Mycoplasma genitalium

In this study, we identified and characterized the enzymatic properties of MG_186, a calcium-dependent Mycoplasma genitalium nuclease. MG_186 displays the hallmarks of nucleases, as indicated by its amino acid sequence similarity to other nucleases. We cloned, UGA corrected, expressed, purified, and demonstrated that recombinant MG_186 (rMG_186) exhibits nuclease activity similar to that of typical sugar-nonspecific endonucleases and exonucleases. Biochemical characterization indicated that Ca2+ alone enhances its activity, which was inhibited by divalent cations, such as Zn2+ and Mn2+. Chelating agents EGTA and EDTA also inhibited nuclease activity. Mycoplasma membrane fractionation and Triton X-114 phase separation showed that MG_186 was a membrane-associated lipoprotein, and electron microscopy revealed its surface membrane location. Incubation of purified human endometrial cell nuclei with rMG_186 resulted in DNA degradation and morphological changes typical of apoptosis. Further, immunofluorescence analysis of rMG_186-treated nuclei indicated that morphological changes were linked to the disintegration of lamin and the internalization of rMG_186. Since M. genitalium has the capacity to invade eukaryotic cells and localize to the perinuclear and nuclear region of parasitized target cells, MG_186 has the potential to provide M. genitalium, which possesses the smallest genome of any self-replicating cell, with the ability to degrade host nucleic acids both as a source of nucleotide precursors for growth and for pathogenic purposes.

Curcumin attenuates the organ dysfunction caused by endotoxemia in the rat

OBJECTIVE

Curcumin has antioxidant, antitumor, and anti-inflammatory properties. However, it remains unknown whether curcumin has any protective effects on sepsis. The purpose of this study was to demonstrate whether curcumin prevents organ dysfunction in animals with sepsis.

METHODS

Rats were randomized into four groups. The control group (group I, n = 7) did not receive any treatment. The curcumin group (group II, n = 10) only received 1.2 g/kg of curcumin. Escherichia coli were injected into the remaining groups intraperitoneally after general anesthesia. Five hours after injection, 12 rats received placebo (group III), and 10 rats received 1.2 g/kg of curcumin (group IV) for 7 d. All rats were sacrificed on postsepsis day 8 and a midline laparotomy was performed. Livers, kidneys, and small bowels were excised for evaluation of the degree of inflammation and tissue alterations histopathologically.

RESULTS

In the liver, widespread hydropic degeneration of hepatocytes were seen in the sepsis group. There was no hydropic degeneration of hepatocytes and no portal inflammation in the sepsis/curcumin group. With respect to the small bowel, the sepsis group showed edema and prominent intraepithelial infiltration of neutrophil leucocytes and plasma cells. Inflammation and hyperemia in the lamina propria in the sepsis/curcumin group were less than those in the sepsis group. With respect to the kidneys, the sepsis group showed severe acute tubular necrosis that was more restricted in the sepsis/curcumin group than in the sepsis group.

CONCLUSION

Curcumin reduced organ dysfunction in rats with experimentally formed sepsis. We propose that curcumin may be useful in the therapy of organ dysfunction due to sepsis, shock, and other diseases associated with local or systemic inflammation.

Ureaplasma parvum lipoproteins, including MB antigen, activate NF-{kappa}B through TLR1, TLR2 and TLR6

Ureaplasma species (Ureaplasma parvum and Ureaplasma urealyticum) are commonly isolated pathogens from the female reproductive tract and are associated with perinatal diseases in humans. Inappropriate induction of inflammatory responses may be involved in the occurrence of such diseases; however, pathogenic agents that induce the inflammatory response have not been identified in ureaplasmas. In this study, we examined the involvement of Toll-like receptors (TLRs) in the activation of the immune response by U. parvum lipoproteins, as well as the U. parvum components responsible for nuclear factor kappaB (NF-kappaB) activation. The Triton X-114 (TX-114) detergent phase of U. parvum was found to induce NF-kappaB through TLR2. The active components of the TX-114 detergent phase were lipoproteins, such as multiple banded (MB) antigen, UU012 and UU016 of U. parvum. The activation of NF-kappaB by these lipoproteins was inhibited by dominant negative (DN) constructs of TLR1 and DN TLR6. Thus, the lipoproteins from U. parvum were found to activate NF-kappaB through TLR1, TLR2 and TLR6. Furthermore, these lipoproteins possessed an ability to induce tumour necrosis factor-alpha (TNF-alpha) in mouse peritoneal macrophages.

A triacylated lipoprotein from Mycoplasma genitalium activates NF-kappaB through Toll-like receptor 1 (TLR1) and TLR2

Mycoplasma genitalium is a sexually transmitted bacterial pathogen that causes nongonococcal chlamydia-negative urethritis, mucopurulent cervicitis, endometritis, pelvic inflammatory disease, and tubal factor infertility in humans. However, pathogenic agents that induce inflammatory responses have not been identified in M. genitalium. In this study, we examined the involvement of Toll-like receptors (TLRs) in activation of the immune response by a lipoprotein from M. genitalium and their active component responsible for NF-kappaB activation. The Triton X-114 detergent phase of M. genitalium was found to induce NF-kappaB through TLR2. The active component of the Triton X-114 detergent phase was a lipoprotein precursor, MG149. The activation of NF-kappaB by MG149 was inhibited by a dominant negative (DN) construct of TLR1 but not by a DN construct of TLR6. These results indicate that the activation of NF-kappaB by MG149 is dependent on TLR1 and TLR2. A synthetic lipopeptide derived from MG149 containing three acyl chains also induced NF-kappaB through TLR1 and TLR2. Thus, the results show that MG149, a triacylated lipoprotein from M. genitalium, activates NF-kappaB through TLR1 and TLR2.

Triacylated lipoproteins derived from Mycoplasma pneumoniae activate nuclear factor-kappaB through toll-like receptors 1 and 2

Pathogenesis of Mycoplasma pneumoniae infection is considered to be in part attributed to excessive immune responses. Recently, a mycoplasma lipoprotein has been shown to induce nuclear factor kappaB (NF-kappaB) activation through toll-like receptor 1 (TLR1), TLR2 and TLR6. In this study, we examined the ability of lipoproteins from M. pneumoniae to activate NF-kappaB through TLR1- and TLR2-dependent, but TLR6-independent, pathways, and the active components responsible for the NF-kappaB activation through the TLR6-independent pathway were identified. The active lipoproteins were found to be MPN611 and MPN162 of M. pneumoniae (designated N-ALP1 and N-ALP2, respectively). Purified N-ALP1 and N-ALP2 from M. pneumoniae and triacylated partial synthetic lipopeptides of N-ALP1 and N-ALP2 augmented the levels of NF-kappaB induction through TLR1- and TLR2-dependent pathways, whereas diacylated partial synthetic lipopeptides of N-ALP1 and N-ALP2 activated NF-kappaB through TLR1-, TLR2- and TLR6-dependent pathways. These data suggest that N-ALP1 and N-ALP2 would be triacylated lipoproteins. The activity of N-ALP1 and N-ALP2 was decreased with a pretreatment of lipoprotein lipase, and partially decreased by protease treatment, indicating that the lipid moiety of N-ALP1 and N-ALP2 is critical for the NF-kappaB activation. Thus, triacylated lipoproteins derived from M. pneumoniae might activate NF-kappaB through TLR1 and TLR2, but not TLR6.

Staphylococcal enterotoxin C1-induced pyrogenic cytokine production in human peripheral blood mononuclear cells is mediated by NADPH oxidase and nuclear factor-kappa B

The staphylococcal enterotoxins produced by Staphylococcus aureus are associated with pyrogenic response in humans and primates. This study investigates the role of NADPH oxidase and nuclear factor-kappa B (NF-kappaB) on enterotoxin staphylococcal enterotoxin C1 (SEC1)-induced pyrogenic cytokine production in human peripheral blood mononuclear cells (PBMC). The results indicate that the febrile response to the supernatant fluids of SEC1-stimulated PBMC in rabbits was in parallel with the levels of interleukin-1beta and interleukin-6 in the supernatants. The release of interleukin-1beta and interleukin-6, nuclear translocation of NF-kappaB and its DNA binding activity in the SEC1-stimulated PBMC were time-dependent and were completely eliminated by pyrrolidine dithiocarbamate or SN-50 (NF-kappaB inhibitors). The release of reactive oxygen species in the supernatants and translocation of the NADPH oxidase p47(phox) subunit to the plasma membrane of SEC1-stimulated PBMC were time-dependent. Administration of apocynin (NADPH oxidase inhibitor) attenuated the febrile response to the supernatants in rabbits and decreased the translocation of NADPH oxidase p47(phox) subunit and NF-kappaB activity in the SEC1-stimulated PBMC, and suppressed reactive oxygen species and pyrogenic cytokine production in the supernatants. Taken together, SEC1 may act through an NADPH oxidase mechanism to release reactive oxygen species, which activate NF-kappaB in PBMC to stimulate the synthesis of pyrogenic cytokines that trigger a fever response in rabbits.

The effect of SHJKS on cytokines production and NF-kappaB activation in the peripheral blood mononuclear cells of patients with cerebral infarction

The Korean genuine medicine "Seonghyangjeongkisan" (SHJKS) has long been used for various cerebrovascular diseases. However, very little scientific investigation has been carried out. Cytokines involved in the regulation of inflammatory reactions and immune responses may play a role in the pathogenesis of cerebral infarction (CI). The aim of the present study is to elucidate how SHJKS modulates the inflammatory reaction in lipopolysaccaride (LPS) plus phytohaemagglutinin (PHA)-stimulated peripheral mononuclear cells (PBMCs) from CI patients. The amount of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, and IL-8 in PBMC culture supernatant was significantly increased in the LPS plus PHA treated cells compared to unstimulated cells. SHJKS inhibited the TNF-alpha, IL-1beta, IL-6, and IL-8 production in dose dependent manner. Maximal inhibition rate of the TNF-alpha, IL-1beta, IL-6, and IL-8 by SHJGS (1.0 mg/ml) was 68.01 +/- 0.28% (P < 0.01), 52.11 +/- 0.56 % (P < 0.01), 53.42 +/- 0.46 % (P < 0.01), and 46.70 +/- 0.37% (P < 0.05), respectively. In addition, we show that SHJKS suppressed nuclear factor (NF)-kappaB activation induced by LPS plus PHA, leading to suppression of IkappaB-alpha phosphorylation and degradation. These results suggest that SHJKS might have regulatory effects on LPS plus PHA-induced cytokine production and NF-kappaB activation, which might explain its beneficial effect in the treatment of CI.

Supernatant of bacterial fermented soybean induces apoptosis of human hepatocellular carcinoma Hep 3B cells via activation of caspase 8 and mitochondria

SC-1, the aqueous phase of soybean fermentation products by bacteria (Bacillus subtilis and Bacillus brevis), significantly inhibited the growth and clonogenesity of human hepatocellular (Hep 3B), mouse hepatocellular (ML-1), and human colorectal (HCT 116 and HT-29) carcinoma cells. Cytotoxicity of SC-1 in Hep 3B cells was through the process of apoptosis characterizing by increase in cell population of sub-G(1) phase, fragmentation of DNA, and change of nuclear morphology. Treatment of Hep 3B cells with SC-1 activated caspase 8 and caspase 3. Elevation of nuclear DNA fragmentation factor 40 (DFF40) and cleavage form of poly(ADP-ribose) polymerase (PARP) were also observed. SC-1 also activated intrinsic pathway via increase of pro-apoptotic (tBid, Bak and Bax) and decrease of anti-apoptotic (Bcl-2 and Bcl-x(L)) proteins on mitochondria, disruption of mitochondrial membrane potential, release of cytochrome c and Smac (second mitochondria-derived activator of caspase/direct IAP binding protein with low PI) from mitochondria, and activation of caspase 9. Inhibition on protein expression of Ku70 in cytosol and cyclooxygenase (COX)-2, but not COX-1, in whole cell lystes were revealed in SC-1-treated Hep 3B cells. These results suggest caspase 8, Ku70 and mitochondria are involved in the antitumor mechanism of SC-1 in Hep 3B cells.

The Anti-inflammatory Effect of Gigukjiwhangwhangami through the Inhibition of Nuclear Factor-.KAPPA.B Activation in the Peripheral Blood Mononuclear Cells of Patients with Cerebral Infarction

The Korean genuine medicine "Gigukjiwhangwhangami (GJWGM)" has long been used for various cerebrovascular diseases. However, the exact mechanism that accounts for the anti-inflammatory effect of GJWGM is not completely understood. The aim of the present study is to elucidate how GJWGM modulates the inflammatory reaction in lipopolysaccaride (LPS)-stimulated peripheral mononuclear cells from patients with cerebral infarction. Production of cytokine was measured by the ELISA and RT-PCR method. The level of nuclear factor-kappaB (NF-kappaB)/Rel A protein and NF-kappaB DNA binding activity were determined by the Western blot analysis and TF-EIA method. We showed that GJWGM inhibited the production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1alpha, IL-6, and IL-8 induced by LPS in dose dependent manner (p<0.05). Maximal inhibition rate of TNF-alpha, IL-1beta, IL-6 and IL-8 production by GJWGM was about 54.34%, 41.37%, 44.04%, and 54.46%, respectively. GJWGM inhibited the TNF-alpha and IL-8 mRNA expression. In addition, we showed that the inhibitory mechanism of GJWGM is through the suppression of NF-kappaB pathway. Our study suggests that an important molecular mechanism by GJWGM reduce inflammation, which may explain its beneficial effect in the regulation of inflammatory reactions.

A Dipalmitoylated Lipoprotein fromMycoplasma pneumoniaeActivates NF-κB through TLR1, TLR2, and TLR6

The pathogenesis of Mycoplasma pneumoniae infection is considered to be in part attributed to excessive immune responses. Recently, lipoproteins from mycoplasmas have been reported to induce NF-kappaB activation. In this study, we examined the ability of lipoproteins from M. pneumoniae to activate NF-kappaB, and the active component responsible for the NF-kappaB activation was identified. Lipid-associated membrane proteins from M. pneumoniae were found to induce NF-kappaB through TLR 2 in a human monocytic cell line, THP-1. The active component of the Lipid-associated membrane proteins was a subunit b of F0F1-type ATPase (F0F1-ATPase). The F0F1-ATPase is assumed to contain two palmitic acids. The activation of NF-kappaB by the F0F1-ATPase was inhibited by a dominant negative construct of TLR1 and TLR6. These results indicate that the activation of NF-kappaB by F0F1-ATPase is dependent on TLR1, TLR2, and TLR6. The activity of the F0F1-ATPase was decreased with pretreatment of lipoprotein lipase but not protease, indicating that the lipid moiety of the F0F1-ATPase was important for the NF-kappaB activation. Thus, a dipalmitoylated lipoprotein from M. pneumoniae was found to activate NF-kappaB through TLR1, TLR2, and TLR6.

Chronic fatigue syndrome: intracellular immune deregulations as a possible etiology for abnormal exercise response

The exacerbation of symptoms after exercise differentiates Chronic fatigue syndrome (CFS) from several other fatigue-associated disorders. Research data point to an abnormal response to exercise in patients with CFS compared to healthy sedentary controls, and to an increasing amount of evidence pointing to severe intracellular immune deregulations in CFS patients. This manuscript explores the hypothetical interactions between these two separately reported observations. First, it is explained that the deregulation of the 2-5A synthetase/RNase L pathway may be related to a channelopathy, capable of initiating both intracellular hypomagnesaemia in skeletal muscles and transient hypoglycemia. This might explain muscle weakness and the reduction of maximal oxygen uptake, as typically seen in CFS patients. Second, the activation of the protein kinase R enzyme, a characteristic feature in atleast subsets of CFS patients, might account for the observed excessive nitric oxide (NO) production in patients with CFS. Elevated NO is known to induce vasidilation, which may limit CFS patients to increase blood flow during exercise, and may even cause and enhanced postexercise hypotension. Finally, it is explored how several types of infections, frequently identified in CFS patients, fit into these hypothetical pathophysiological interactions.

Lipid-associated membrane proteins of Mycoplasma fermentans and M. penetrans activate human immunodeficiency virus long-terminal repeats through Toll-like receptors

Mycoplasmas are known to enhance human immunodeficiency virus (HIV) replication, and mycoplasma-derived lipid extracts have been reported to activate nuclear factor-kappaB (NF-kappaB) through Toll-like receptors (TLRs). In this study, we examined the involvement of TLRs in the activation of HIV long-terminal repeats (LTR) by mycoplasma and their active components responsible for the TLR activation. Lipid-associated membrane proteins (LAMPs) from two species of mycoplasma (Mycoplasma fermentans and M. penetrans) that are associated with acquired immune-deficiency syndrome (AIDS), were found to activate HIV LTRs in a human monocytic cell line, THP-1. NF-kappaB deletion from the LTR resulted in inhibition of the activation. The LTR activation by M. fermentans LAMPs was inhibited by a dominant negative (DN) construct of TLR1 and TLR6, whereas HIV LTR activation by M. penetrans LAMPs was inhibited by DN TLR1, but not by DN TLR6. These results indicate that the activation of HIV LTRs by M. fermentans and M. penetrans LAMPs is dependent on NF-kappaB, and that the activation of HIV LTR by M. fermentans LAMPs is mediated through TLR1, TLR2 and TLR6. In contrast, the LTR activation by M. penetrans LAMPs is carried out through TLR1 and TLR2, but not TLR6. Subsequently, the active component of M. penetrans and M. fermentans LAMPs was purified by reverse-phase high-performance liquid chromatography (HPLC). Interestingly, the purified lipoprotein of M. penetrans LAMPs (LPMp) was able to activate NF-kappaB through TLR1 and TLR2. On the other hand, the activation of NF-kappaB by purified lipoprotein of M. fermentans LAMPs (LPMf) was mediated through TLR2 and TLR6, but not TLR1.

Synergistic activation of innate immunity by double-stranded RNA and CpG DNA promotes enhanced antitumor activity

Double-stranded RNA (dsRNA) and unmethylated CpG sequences in DNA are pathogen-associated molecular patterns of viruses and bacteria that activate innate immunity. To examine whether dsRNA and CpG DNA could combine to provide enhanced stimulation of innate immune cells, murine macrophages were stimulated with poly-rI:rC (pIC), a dsRNA analog, and CpG-containing oligodeoxynucleotides (CpG-ODN). Combined treatments demonstrated synergy in nitric oxide, interleukin (IL)-12, tumor necrosis factor alpha, and IL-6 production. Studies using neutralizing antibodies for type I interferons (IFNs), IFN-alpha and IFN-beta, indicated that nitric oxide synthase synergism is mediated by paracrine/autocrine effects of IFN-beta. In contrast, enhanced cytokine production occurred independent of type I IFN and was maintained in macrophages from IFN-alpha/beta receptor knockout mice. Cotransfection of human Toll-like receptors 3 and 9 (receptors for dsRNA and CpG DNA, respectively) into 293T cells supported synergistic activation of an IL-8 promoter reporter construct by pIC, indicating interaction of the signaling pathways in driving the synergy response. In vivo stimulation of mice with pIC and CpG-ODN demonstrated synergy for serum IL-6 and IL-12p40 levels that correlated with an enhanced antitumor effect against established B16-F10 experimental pulmonary metastases. Treatment of tumor-bearing mice with pIC and CpG-ODN in combination resulted in enhanced nitric oxide synthase expression in lung tissue and enhanced up-regulation of class I major histocompatibility complex on splenic dendritic cells relative to treatments with either agent alone. In conclusion, the combined detection of viral pathogen-associated molecular patterns, i.e., dsRNA and CpG DNA, may mimic definitive viral recognition, resulting in an enhanced innate immune response that could be used for tumor vaccination or immunotherapy.

Interaction of mycoplasmas with host cells

The mycoplasmas form a large group of prokaryotic microorganisms with over 190 species distinguished from ordinary bacteria by their small size, minute genome, and total lack of a cell wall. Owing to their limited biosynthetic capabilities, most mycoplasmas are parasites exhibiting strict host and tissue specificities. The aim of this review is to collate present knowledge on the strategies employed by mycoplasmas while interacting with their host eukaryotic cells. Prominant among these strategies is the adherence of mycoplasma to host cells, identifying the mycoplasmal adhesins as well as the mammalian membrane receptors; the invasion of mycoplasmas into host cells including studies on the role of mycoplasmal surface molecules and signaling mechanisms in the invasion; the fusion of mycoplasmas with host cells, a novel process that raises intriguing questions of how microinjection of mycoplasma components into eukaryotic cells subvert and damage the host cells. The observations of diverse interactions of mycoplasmas with cells of the immune system and their immunomodulatory effects and the discovery of genetic systems that enable mycoplasmas to rapidly change their surface antigenic composition have been important developments in mycoplasma research over the past decade, showing that mycoplasmas possess an impressive capability of maintaining a dynamic surface architecture that is antigenically and functionally versatile, contributing to the capability of the mycoplasmas to adapt to a large range of habitats and cause diseases that are often chronic in nature.

House dust mite Dermatophagoides farinae augments proinflammatory mediator productions and accessory function of alveolar macrophages: implications for allergic sensitization and inflammation

In this study, we examine the effects of Dermatophagoides farinae (Der f), a major source of airborne allergens, on alveolar macrophages (AMs), and we also test its contribution to allergic responses in mice. Der f activated NF-kappaB of AMs and, unlike OVA or LPS stimulation, up-regulated IL-6, TNF-alpha, and NO. In addition, it down-regulated antioxidants, but affected neither the expression nor production of IL-12. Der f-stimulated AMs expressed enhanced levels of costimulatory B7 molecules, supported T cell proliferation, and promoted Th2 cell development. The enhanced accessory function was suppressed by blockade mAbs to B7.2, IL-6, and TNF-alpha and by N-monomethyl-L-arginine, an NO synthase inhibitor, and N-acetylcysteine, a thiol antioxidant, whereas it was augmented by (+/-)-S-nitroso-N-acetylpenicillamine, an NO donor. Arg-Gly-Asp-Ser peptide and neo-glycoproteins galactose-BSA and mannose-BSA inhibited the Der f-induced IL-6 and TNF-alpha productions and enhanced accessory function of AMs. Der f was more potent than OVA for inducing pulmonary eosinophilic inflammation, NO, and serum allergen-specific IgG1 Ab production in mice. AMs from Der f-challenged mice expressed enhanced levels of B7 and augmented T cell proliferation ex vivo. In Der f-challenged mice, respiratory syncytial virus infection (5 x 10(5) pfu; 3 days before Der f instillation) augmented Der f-specific Ab production, whereas dexamethasone (50 mg/kg; 1 h before Der f instillation) diminished the allergic airway inflammation and Ab response. We conclude that AMs are sensitive targets for Der f and that the Der f-induced proinflammatory responses may represent an important mechanism in mediating the development of allergic sensitization and inflammation.

Opposing roles of activator protein-1 and CCAAT/enhancer binding protein beta in the regulation of inducible granulysin gene expression in a human monocytic cell line, THP-1

We previously reported that inducible granulysin gene expression in a human monocytic cell line, THP-1 is dominantly dependent on transcription factor activator protein-1 (AP-1). Here, we further examined the precise regulatory mechanisms underlying granulysin gene expression using THP-1 cells treated with Acholeplasma laidlawii. Transfection of reporter gene constructs into THP-1 cells indicated that the presence of a positive regulatory element(s) is located from -329 to -85 base pairs, containing two distinct AP-1 binding sites and one nuclear factor-kappaB (NF-kappaB) binding site. Deletion or mutation of the NF-kappaB binding site failed to affect inducible promoter activity, whereas deletion or mutation of both the AP-1 binding sites abrogated the promoter activity. Interestingly, deletion of the putative CCAAT/enhancer binding protein beta (C/EBPbeta) binding site upstream of the positive regulatory element induced the augmentation of granulysin promoter activity. Electrophoretic mobility shift assays demonstrated that nuclear extract prepared from A. laidlawii-treated THP-1 cells generated a specific binding to oligonucleotides, including AP-1, C/EBPbeta, and NF-kappaB element. Furthermore, over-expression of liver-enriched transcriptional activator protein, a subunit of C/EBPbeta, augmented A. laidlawii-induced granulysin promoter activity, whereas over-expression of liver-enriched transcriptional inhibitory protein inhibited the promoter activity. NF-kappaB p50 homodimer had no transactivation property, although it bound to the NF-kappaB site. These results indicate that AP-1 and C/EBPbeta, but not NF-kappaB participate in the regulation of inducible granulysin gene expression in THP-1 cells. Moreover, the Toll-like receptor 2-dependent signalling pathway may be involved in A. laidlawii-induced transactivation of the granulysin promoter. Thus, these results suggest that the gene expression of granulysin in macrophages would be exquisitely regulated by positive and negative transcription factors when microbial invasion occurs.

Acholeplasma laidlawii up-regulates granulysin gene expression via transcription factor activator protein-1 in a human monocytic cell line, THP-1

An antimicrobial protein granulysin is constitutively expressed in cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. However, little is known about the precise regulatory mechanisms underlying granulysin gene expression. In this study, we examined the regulatory mechanisms underlying granulysin gene expression using a human monocytic cell line, THP-1, treated with Acholeplasma laidlawii. The level of granulysin mRNA expression in THP-1 cells was significantly augmented in response to stimulation with A. laidlawii. The transfection of reporter gene constructs into THP-1 cells indicated that DNA sequences between residues -329 and -239, relative to the transcriptional start site of the granulysin gene, are responsible for mediating gene induction. In addition, mutagenesis of a putative activator protein-1 (AP-1)-binding site between residues -277 and -271 in the granulysin promoter resulted in the reduction of granulysin promoter activity. Electrophoretic mobility shift assays (EMSA) demonstrated that nuclear extract prepared from A. laidlawii-treated THP-1 cells can generate specific binding to DNA oligonucleotides encompassing the AP-1-binding site, whereas unstimulated nuclear extract from the cells failed to do so. Furthermore, competition and supershift assays confirmed that A. laidlawii can induce the activation of AP-1. These results indicate that AP-1 dominantly participates in the regulation of inducible granulysin gene expression in THP-1 cells. Therefore, the finding of inducible granulysin gene expression by A. laidlawii suggests that inducible granulysin in macrophages may function as a protective weapon when microbial invasion occurs.

Mycoplasmal infections prevent apoptosis and induce malignant transformation of interleukin-3-dependent 32D hematopoietic cells

32D cells, a murine myeloid cell line, rapidly undergo apoptosis upon withdrawal of interleukin-3 (IL-3) supplement in culture. We found that 32D cells, if infected by several species of human mycoplasmas that rapidly activated NF-kappaB, would live and continue to grow in IL-3-depleted culture. Mycoplasma-infected cells showed no evidence of autocrine production of IL-3. Pyrrolidine dithiocarbamate (PDTC) blocked activation of NF-kappaB and led to prominent cell death. Heat-killed mycoplasmas or mycoplasmal membrane preparations alone could support continued growth of 32D cells in culture without IL-3 supplement for a substantial period of time. However, upon removal of heat-inactivated mycoplasmas, 32D cells quickly became apoptotic. In comparison, live Mycoplasma fermentans or M. penetrans infection for 4 to 5 weeks induced malignant transformation of 32D cells. Transformed 32D cells grew autonomously and no longer required support of growth-stimulating factors including IL-3 and mycoplasmas. The transformed 32D cells quickly formed tumors when injected into nude mice. Karyotyping showed that development of chromosomal changes and trisomy 19 was often associated with malignant transformation and tumorigenicity of 32D cells. Mycoplasmal infections apparently affected the fidelity of genomic transmission in cell division as well as checkpoints coordinating the progression of cell cycle events.