Suppression of B-cell activation and IgE, IgA, IgG1 and IgG4 production by mammalian telomeric oligonucleotides.

BACKGROUND: The fine balance of immunoglobulins (Ig) E, IgG1, IgG4 and IgA in healthy production is maintained by the interaction of B cells with adaptive and innate immune response. The regulation of toll-like receptors (TLRs)-driven innate and adaptive immune effector B-cell response and the role of mammalian telomeric TTAGGG repeat elements represent an important research area. METHODS: Human PBMC and purified naive and memory B cells were stimulated with specific ligands for TLR2, TLR3, TLR4, TLR5, TLR7, TLR8 and TLR9 in the presence or absence of telomeric oligonucleotides. B-cell proliferation, differentiation and antibody production were determined. RESULTS: TLR9 ligand directly activates naive and memory B cells, whereas TLR7 can stimulate them in the presence of plasmacytoid dendritic cells. Human B cells proliferate and turn into antibody-secreting cells in response to TLR3, TLR7 and TLR9, but not to TLR2, TLR4, TLR5 and TLR8 ligands. Stimulation of B cells with intracellular TLR3, TLR7 and TLR9 induced an activation cascade leading to memory B-cell generation and particularly IgG1, but also IgA, IgG4 and very low levels of IgE production. Mammalian telomeric oligodeoxynucleotide (ODN) significantly inhibited all features of TLR ligand-induced events in B cells including B-cell proliferation, IgE, IgG1, IgG4, IgA production, class switch recombination, plasma cell differentiation induced by TLR3, TLR7 and TLR9 ligands. CONCLUSION: B cells require specific TLR stimulation, T-cell and plasmacytoid dendritic cell help for distinct activation and Ig production profiles. Host-derived telomeric ODN suppress B-cell activation and antibody production demonstrating a natural mechanism for the control of overexuberant B-cell activation, antibody production and generation of memory.

Effect of egg storage duration and brooding temperatures on chick growth, intestine morphology and nutrient transporters.

The effects of egg storage duration (ESD) and brooding temperature (BT) on BW, intestine development and nutrient transporters of broiler chicks were investigated. A total of 396 chicks obtained from eggs stored at 18°C for 3 days (ESD3-18°C) or at 14°C for 14 days (ESD14-14°C) before incubation were exposed to three BTs. Temperatures were initially set at 32°C, 34°C and 30°C for control (BT-Cont), high (BT-High) and low (BT-Low) BTs, respectively. Brooding temperatures were decreased by 2°C each at days 2, 7, 14 and 21. Body weight was measured at the day of hatch, 2, 7, 14, 21, 28 and 42. Cloacal temperatures of broilers were recorded from 1 to 14 days. Intestinal morphology and gene expression levels of H+-dependent peptide transporter (PepT1) and Na-dependent glucose (SGLT1) were evaluated on the day of hatch and 14. Cloacal temperatures of chicks were affected by BTs from days 1 to 8, being the lowest for BT-Low chicks. BT-High resulted in the heaviest BWs at 7 days, especially for ESD14-14°C chicks. This result was consistent with longer villus and larger villus area of ESD14-14°C chicks at BT-High conditions. From 14 days to slaughter age, BT had no effect on broiler weight. ESD3-18°C chicks were heavier than ESD14-14°C chicks up to 28 days. The PepT1 and SGLT1 expression levels were significantly higher in ESD3-18°C chicks than ESD14-14°C on the day of hatch. There was significant egg storage by BT interaction for PepT1 and SGLT1 transporters at day 14. ESD14-14°C chicks had significantly higher expression of PepT1 and SGLT1 at BT-Low than those at BT-Cont. ESD14-14°C chicks upregulated PepT1 gene expression 1.15 and 1.57-fold at BT-High and BT-Low, respectively, compared with BT-Cont, whereas PepT1 expression was downregulated 0.67 and 0.62-fold in ESD3-18°C chicks at BT-High and BT-Low. These results indicated that pre-incubation egg storage conditions and BTs affected intestine morphology and PepT1 and SGLT1 nutrient transporters expression in broiler chicks.

Egg storage duration and hatch window affect gene expression of nutrient transporters and intestine morphological parameters of early hatched broiler chicks.

In recent years, researchers have given emphasis on the differences in physiological parameters between early and late hatched chicks within a hatch window. Considering the importance of intestine development in newly hatched chicks, however, changes in gene expression of nutrient transporters in the jejunum of early hatched chicks within a hatch window have not been studied yet. This study was conducted to determine the effects of egg storage duration before incubation and hatch window on intestinal development and expression of PepT1 (H+-dependent peptide transporter) and SGLT1 (sodium-glucose co-transporter) genes in the jejunum of early hatched broiler chicks within a 30 h of hatch window. A total of 1218 eggs obtained from 38-week-old Ross 308 broiler breeder flocks were stored for 3 (ES3) or 14 days (ES14) and incubated at the same conditions. Eggs were checked between 475 and 480 h of incubation and 40 chicks from each egg storage duration were weighed; chick length and rectal temperature were measured. The chicks were sampled to evaluate morphological parameters and PepT1 and SGLT1 expression. The remaining chicks that hatched between 475 and 480 h were placed back in the incubator and the same measurements were conducted with those chicks at the end of hatch window at 510 h of incubation. Chick length, chick dry matter content, rectal temperature and weight of small intestine segments increased, whereas chick weight decreased during the hatch window. The increase in the jejunum length and villus width and area during the hatch window were higher for ES3 than ES14 chicks. PepT1 expression was higher for ES3 chicks compared with ES14. There was a 10.2 and 17.6-fold increase in PepT1 and SGLT1 expression of ES3 chicks at the end of hatch window, whereas it was only 2.3 and 3.3-fold, respectively, for ES14 chicks. These results suggested that egg storage duration affected development of early hatched chicks during 30 h of hatch window. It can be concluded that the ES14 chicks would be less efficiently adapted to absorption process for carbohydrates and protein than those from ES3 at the end of the hatch window.

Oxidative stress inhibits the phagocytosis of apoptotic cells that have externalized phosphatidylserine.

The efficient phagocytosis of apoptotic cells by macrophages reduces the potential for an inflammatory response by ensuring that the dying cells are cleared before their intracellular contents are released. Early apoptotic cells are targeted for phagocytosis through the translocation of phosphatidylserine (PS) from the inner to the outer leaflet of the plasma membrane. In this report, we show that the oxidant H(2)O(2) inhibits phagocytosis of apoptotic cells even though the cells express functional PS on their surface. Thus, B lymphoma cells induced to undergo apoptosis by the chemotherapy drug etoposide are efficiently phagocytosed by macrophages in a process that is mediated by PS (inhibitable by PS liposomes). Exposure of the apoptotic cells to H(2)O(2) inhibits phagocytosis even though the cells still express functional PS on their surface. In addition, Jurkat cells and thymocytes induced to undergo apoptosis by H(2)O(2) alone are poorly phagocytosed. Inhibition of phagocytosis by H(2)O(2) cannot be attributed to oxidative inactivation or redistribution of PS on the cell surface. The results indicate that PS externalization is necessary but is not sufficient to target apoptotic cells for phagocytosis. Another phagocytosis recognition factor must therefore exist to facilitate uptake of apoptotic cells, and this factor is sensitive to modification by H(2)O(2).

Matrix entrapment of glucose oxidase by gamma irradiation.

In this study, matrix entrapment of the enzyme glucose oxidase was achieved through gamma irradiation of monomers N-vinyl pyrrolidone, 2-hydroxyethyl methacrylate and their mixture. To test the effect of radiation on entrapment efficiency, retention of activities and properties of the system, duration and temperature were varied. The reusability of the resultant products was tested. It was generally found that inclusion of the hydrophilic monomer N-vinyl pyrrolidone into the matrix increased the water content, entrapment efficiency and enzyme activity. gamma irradiation did not have a detrimental effect on the activity of pure enzyme when exposure was at -196 degrees C, but this radioresistance was less at higher temperatures. Infrared spectroscopy indicated that there was no chemical binding between the matrix and the enzyme. Repeated use studies revealed a gradual loss of activity in all of the samples tested for 10 runs.

In vivo application of biodegradable controlled antibiotic release systems for the treatment of implant-related osteomyelitis.

In this study the construction and in vivo testing of antibiotic-loaded polyhydroxyalkanoate rods were planned for use in the treatment of implant-related osteomyelitis. The rods were constructed of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate), carrying 50% (w/w) Sulperazone or Duocid. They were implanted in rabbit tibia in which implant-related osteomyelitis (IRO) had been induced with Staphylococcus aureus. The effectiveness of the antibiotics in the treatment of IRO was determined. The establishment of IRO with bacterial inoculation was complete after 3 weeks with 100% infection rate in all groups. There was no contamination or super-infection. Both antibiotics were found to be highly effective against the bacteria. Following the application of Sulperazone-P(3-HB-co-4-HB) rods, no infective agents could be isolated from the infection site within the 6-week test period, indicating complete treatment of the infection. Macroscopical evaluation at follow-up revealed no drainage, minimal swelling and increase in local warmth, most probably due to the surgery rather than to a reaction towards the implant. The overall scores for radiological findings by the end of 6 weeks were 0.8/5 for the antibiotic-loaded rod implanted in the right limb, and 1.1/5 for the antibiotic-free rod implanted in the left limb. There was no statistical difference between the antibiotic-loaded and antibiotic-free polymeric rods. In vivo drug release was almost complete within the first week. One interesting observation, however, was that the therapy was still very effective even when the release rate was very high. In the SEM of in vitro tested rods, the polymeric component was unchanged in 2 weeks while the drug leached out, leaving voids behind. In vivo, however, the morphology of the implant was significantly modified within 6 weeks post-implantation. Since a substantial degree of the in vivo drug release was complete within 1 week, we believe that dissolution of the drug must be the predominant mechanism through which the drug release is controlled.

Synthesis and mechanical properties of interpenetrating networks of polyhydroxybutyrate-co-hydroxyvalerate and polyhydroxyethyl methacrylate.

Naturally occurring, biocompatible, and biodegradable polyhydroxybutyrate-co-hydroxyvalerate (PHBV), and synthetic, non-degrading polyhydroxyethylmethacrylate (PHEMA) membranes were prepared and their mechanical properties were studied. Their performances were compared with the interpenetrating networks (IPN) prepared by photopolymerization of HEMA in the presence of PHBV. The modulus of elasticity, failure stress and failure strain indicated that the IPNs are viscoelastic with properties closer to PHEMA but much stronger than PHEMA homopolymers. Incorporation of PHBV (7, 14 and 22% HV) affected the mechanical properties positively. Increasing the PHBV content increased the modulus of elasticity and failure stress nearly in all samples tested. PHBV (7, 14, and 22% HV, 300 mg) samples showed an approximately 17-30 fold increase in terms of modulus of elasticity and 7-10 fold increase in terms of failure stress. The scanning electron micrographs of the membranes showed that the PHEMA membranes are more porous than the PHBV membranes but the IPN structure displayed channels on the membrane surface indicating that HEMA polymerization was achieved by using the PHBV as a scaffold. With the use of the present technique, it is possible to synthesize supramolecular structures from molecules that are not compatible and miscible with each other.

Immunotherapeutic applications of CpG-containing oligodeoxynucleotides.

Bacterial DNA and synthetic oligodeoxynucleotides (ODN) expressing unmethylated CpG motifs stimulate the mammalian immune system to mount a rapid innate immune response. This response is characterized by the production of polyreactive IgM, immunomodulatory cytokines and chemokines. CpG ODN directly stimulate lymphocytes, natural killer cells and professional antigen-presenting cells (such as macrophages and dendritic cells). Owing to the strength and nature of this stimulation, CpG ODN are being harnessed for a variety of therapeutic uses. They are being tested for their ability to act as immune adjuvants, boosting the immune response elicited by conventional and DNA vaccines. As a result of their ability to activate a strong interferon gamma-dominated Th1 response while blocking the development of Th2-dependent allergies, CpG ODN are being examined for their antiallergic properties. Finally, CpG ODN are being used as "immunoprotective agents", since the innate immune response they elicit can protect the host from a variety of pathogenic bacteria, viruses and parasites.

Antibiotic release from biodegradable PHBV microparticles.

For the treatment of periodontal diseases, design of a controlled release system seemed very appropriate for an effective, long term result. In this study a novel, biodegradable microbial polyester, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV of various valerate contents containing a well established antibiotic, tetracycline, known to be effective against many of the periodontal disease related microorganisms, was used in the construction of a controlled release system. Tetracycline was loaded in the PHBV microspheres and microcapsules both in its acidic (TC) and in neutral form (TCN). Microcapsules of PHBV were prepared under different conditions using w/o/w double emulsion and their properties such as encapsulation efficiency, loading, release characteristics, and morphological properties were investigated. It was found that concentration of emulsifiers polyvinyl alcohol (PVA) and gelatin (varied between 0-4%) influenced the encapsulation efficiency appreciably. In order to increase encapsulation efficiency (from the obtained range of 18.1-30.1%) and slow down the release of the highly soluble tetracycline.HCl, it was neutralized with NaOH. Encapsulation efficiency of neutralized tetracycline was much higher (51.9-65.3%) due to the insoluble form of the drug used during encapsulation. The release behaviour of neither of the drugs was found to be of zero order. Rather the trends fitted reasonably well to Higuchi's approach for release from spherical micropheres. Biodegradability was not an appreciable parameter in the release from microcapsules because release was complete before any signs of degradation were observed.

Properties and drug release behaviour of poly(3-hydroxybutyric acid) and various poly(3-hydroxybutyrate-hydroxyvalerate) copolymer microcapsules.

Microcapsules of poly(3-hydroxybutyric acid) [PHB] and its copolymers with hydroxyvalerate [HV] were prepared by the solvent evaporation technique and loaded with a model drug, 2,7-dichlorofluorescein. Microcapsules were also prepared from the same polymers by incorporating a polyphosphate-Ca+2 complex into the membrane. The morphology of the microcapsules varied by the change in the type of polymer used, by the introduction of drug and by the incorporation of the complex. Drug release behaviour, encapsulation efficiency and loading were all found to be influenced by the polymer type. The DSC results revealed that upon incorporation of valerate as the co-monomer, the crystallinity of the polymer decreased, leading to a material with more segmental mobility. This probably was the reason why the loading and encapsulation efficiency of the homopolymer were lower than those of the copolymers. DSC also indicated that the complex became an integral part of the membrane.

Biodegradable polyhydroxyalkanoate implants for osteomyelitis therapy: in vitro antibiotic release.

Various random copolyesters of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV) and 3-hydroxybutyrate and 4-hydroxybutyrate P(3HB-4HB) were used in the construction of biodegradable, implantable rods for the local delivery of antibiotics (Sulperazone and Duocid) in chronic osteomyelitis therapy. Drug loading, type of active agent, and additional coating of the implant surface all have significant contributions to the in vitro release profile. The rate and duration of Sulperazone release from P(3HB-4HB) rods were controlled by the polymer/drug ratio (drug loading). The rate of drug dissolution was substantially higher than that of polymer degradation. Therefore, the release phenomenon was more dependent on drug dissolution rather than on polymer degradation or diffusion. Coating rods with the same type of polymer substantially reduced the initial burst effect observed with the uncoated rods, and significantly decreased the release rate so that the release kinetics became almost zero order. Antibiotic release from coated rods was sustained for over a period of 2 weeks at a constant rate, whereas uncoated rods released their contents in less than a week. Impregnation of Duocid into the hydrophobic polymer matrix yielded a rod with a smoother surface topography. The release from these rods was significantly higher than for rods loaded with Sulperazone and a zero order release could not be obtained with these samples.

Reduction of surgery-induced peritoneal adhesions by continuous release of streptokinase from a drug delivery system.

Postoperative abdominal adhesions may lead to intestinal obstruction and infertility. The effect of continuous release of streptokinase to the peritoneal cavity on postoperative adhesions was examined under experimental conditions. Peritoneal adhesions were induced in rats and the animals were further treated by intraperitoneal administration of streptokinase solution, polyhydroxybutyrate-co-hydroxyvalerate (PHBV) membrane alone and streptokinase loaded PHBV membrane and compared to sham operated and untreated groups. Formation of adhesions was evaluated by quantitative macroscopic grading, histopathologically with light microscopy, on the following week. Streptokinase loaded PHBV prevented postoperative adhesion formation in 90% of the cases. PHBV membrane alone also reduced the severity of adhesions due to its anti-adhesive properties. Histopathological examination revealed limited foreign body reaction due to PHBV. Continuous streptokinase activity in the peritoneal cavity during early post-surgical period prevents postoperative adhesion.

Sulbactam-cefoperazone polyhydroxybutyrate-co-hydroxyvalerate (PHBV) local antibiotic delivery system: in vivo effectiveness and biocompatibility in the treatment of implant-related experimental osteomyelitis.

In this study, a novel antibiotic carrier system for use in the treatment of implant-related and chronic osteomyelitis was developed. Sulbactam-cefoperazone was introduced to rods of polyhydroxybutyrate-co-hydroxyvalerate (22 mol % HV, w/w), a member of a family of microbial-origin polymer that is biodegradable, biocompatible, and osteoconductive due to its piezoelectric property. The antibiotic-loaded carrier was implanted into the infection site that was induced by Staphylococcus aureus inoculation into the rabbit tibia. The effectiveness of this was assessed macroscopically, radiographically, bacteriologically, and histopathologically. Findings of infection subsided on day 15 and almost complete remission was observed on day 30. The control side that contained antibiotic-free rods, however, worsened. These findings prompted us to conclude that the novel biodegradable antibiotic carrier developed in the present study seems to be a promising candidate for use in the treatment of severe bone infection.

In vivo response to biodegradable controlled antibiotic release systems.

In this study, the major goal was to evaluate in vitro and in vivo findings by macroscopy, radiology, and histology to determine the effectiveness of therapy of experimental implant-related osteomyelitis with antibiotic carrier rods constructed of microbial polyesters. The polymers used were poly(3-hydroxybutyrate-co-4-hydroxyvalerate) [P(3-HB-co-4-HB)] and poly(3-hydroxybutyrate-co-3-hydroxy- valerate) [P(3-HB-co-3-HV)]. Both the Sulperazone and the Duocid-P(3-HB-co-4-HB) rods with a drug to polymer ratio of 1:1 (w/w) were effective in treating the bone infection that was experimentally initiated by inoculation of a hemolytic strain of Staphylococcus aureus (coagulase positive; phage type 52/52b) together with metal implants into the medullary area of rabbit tibia. Macroscopical data revealed that the effectiveness of therapy was apparent at week 6 for all categories tested. Radiological findings with Duocid- and Sulperazone-loaded P(3-HB-co-4-HB) rods improved significantly when judged by changes in periosteal elevation, widening of bone shaft, new bone formation, and soft-tissue deformation after 6 weeks of implantation. Histologically the signs of infection were found to subside by weeks 3 and 6. Inflammatory cells were replaced with bone-forming cells upon treatment with Sulperazone-P(3-HB-co-4-HB) and Duocid-P(3-HB-co-4-HB). Osteoblastic activity was prominent. Intramedullary inflammation, although still present, started to be replaced by fibrous or bony tissue. Histological findings presented the subsidence of infection. In summary, the antibiotic-loaded biopolymeric rods appeared to have potential as a new controlled-release system for the treatment of implant related osteomyelitis and chronic osteomyelitis.

Sterically stabilized cationic liposomes improve the uptake and immunostimulatory activity of CpG oligonucleotides.

Immunostimulatory CpG oligonucleotides (ODN) show promise as immune adjuvants, anti-allergens, and immunoprotective agents. Increasing the bioavailability and duration of action of CpG ODN should improve their therapeutic utility. Encapsulating ODN in sterically stabilized cationic liposomes provides protection from serum nucleases while facilitating uptake by B cells, dendritic cells, and macrophages. In a pathogen challenge model, sterically stabilized cationic liposomes encapsulation doubled the duration of CpG ODN-induced immune protection. In an immunization model, coencapsulation of CpG ODN with protein Ag (OVA) magnified the resultant Ag-specific IFN-gamma and IgG responses by 15- to 40-fold compared with Ag plus CpG ODN alone. These findings support the use of sterically stabilized cationic liposomes to significantly enhance the therapeutic efficacy of CpG ODN.

Cutting edge: Role of Toll-like receptor 9 in CpG DNA-induced activation of human cells.

Unmethylated CpG motifs present in bacterial DNA stimulate a rapid and robust innate immune response. Human cell lines and PBMC that recognize CpG DNA express membrane-bound human Toll-like receptor 9 (hTLR9). Cells that are not responsive to CpG DNA become responsive when transfected with hTLR9. Expression of hTLR9 dramatically increases uptake of CpG (but not control) DNA into endocytic vesicles. Upon cell stimulation, hTLR9 and CpG DNA are found in the same endocytic vesicles. Cells expressing hTLR9 are stimulated by CpG motifs that are active in primates but not rodents, suggesting that evolutionary divergence between TLR9 molecules underlies species-specific differences in the recognition of bacterial DNA. These findings indicate that hTLR9 plays a critical role in the CpG DNA-mediated activation of human cells.