Detoxification of Salmonella typhimurium lipopolysaccharide by ionizing radiation

Processing of collagen based biomaterials and the resulting materials properties

Collagen, the most abundant extracellular matrix protein in animal kingdom belongs to a family of fibrous proteins, which transfer load in tissues and which provide a highly biocompatible environment for cells. This high biocompatibility makes collagen a perfect biomaterial for implantable medical products and scaffolds for in vitro testing systems. To manufacture collagen based solutions, porous sponges, membranes and threads for surgical and dental purposes or cell culture matrices, collagen rich tissues as skin and tendon of mammals are intensively processed by physical and chemical means. Other tissues such as pericardium and intestine are more gently decellularized while maintaining their complex collagenous architectures. Tissue processing technologies are organized as a series of steps, which are combined in different ways to manufacture structurally versatile materials with varying properties in strength, stability against temperature and enzymatic degradation and cellular response. Complex structures are achieved by combined technologies. Different drying techniques are performed with sterilisation steps and the preparation of porous structures simultaneously. Chemical crosslinking is combined with casting steps as spinning, moulding or additive manufacturing techniques. Important progress is expected by using collagen based bio-inks, which can be formed into 3D structures and combined with live cells. This review will give an overview of the technological principles of processing collagen rich tissues down to collagen hydrolysates and the methods to rebuild differently shaped products. The effects of the processing steps on the final materials properties are discussed especially with regard to the thermal and the physical properties and the susceptibility to enzymatic degradation. These properties are key features for biological and clinical application, handling and metabolization.

Th17 activation by dendritic cells stimulated with gamma-irradiated Streptococcus pneumoniae

Dendritic cells (DCs) play an important role in antigen presentation, which is an essential step for the induction of antigen-specific adaptive immunity. Inactivated bacterial whole cell vaccines have been widely used to prevent many bacterial infections because they elicit good immunogenicity due to the presence of various antigens and are relatively inexpensive and easy to manufacture. Recently, gamma-irradiated whole cells of nonencapsulated Streptococcus pneumoniae were developed as a broad-spectrum and serotype-independent multivalent vaccine. In the present study, we generated gamma-irradiated S. pneumoniae (r-SP) and investigated its capacity to stimulate mouse bone marrow-derived DCs (BM-DCs) in comparison with heat-inactivated and formalin-inactivated S. pneumoniae (h-SP and f-SP, respectively). r-SP showed an attenuated binding and internalization level to BM-DCs when compared to h-SP or f-SP. r-SP weakly induced the expression of CD80, CD83, CD86, MHC class I, and PD-L2 compared with h-SP or f-SP. Furthermore, r-SP less potently induced IL-6, TNF-α, and IL-23 expression than h-SP or f-SP but more potently induced IL-1β expression than h-SP or f-SP in BM-DCs. Since Th17-mediated immune responses are known to be important for the protection against pneumococcal infections, r-SP-primed DCs were co-cultured with splenocytes or splenic CD4⁺ T cells. Interestingly, r-SP-sensitized BM-DCs markedly induced IL-17A⁺ CD4⁺ T cells whereas h-SP- or f-SP-sensitized BM-DCs weakly induced them. Collectively, these results suggest that r-SP could be an effective pneumococcal vaccine candidate eliciting Th17-mediated immune responses by stimulation of DCs.

Effect of gamma irradiation on mistletoe (Viscum album) lectin-mediated toxicity and immunomodulatory activity

This study evaluated the effect of gamma irradiation on the reduction of the toxicity of mistletoe lectin using both in vitro and in vivo models. To extract the lectin from mistletoe, an (NH4)2SO4 precipitation method was employed and the precipitant purified using a Sepharose 4B column to obtain the pure lectin fraction. Purified lectin was then gamma-irradiated at doses of 0, 5, 10, 15, and 20 kGy, or heated at 100 °C for 30 min. Toxic effects of non-irradiated, irradiated, and heat-treated lectins were tested using hemagglutination assays, cytotoxicity assays, hepatotoxicity, and a mouse survival test and immunological response was tested using cytokine production activity. Hemagglutination of lectin was remarkably decreased (P < 0.05) by irradiation at doses exceeding 10 kGy and with heat treatment. However, lectin irradiated with 5 kGy maintained its hemagglutination activity. The cytotoxicity of lectin was decreased by irradiation at doses over 5 kGy and with heat treatment. In experiments using mouse model, glutamate oxaloacetate transaminase (GOT) and glutamic pyruvic transaminase (GPT) levels were decreased in the group treated with the 5 kGy irradiated and heat-treated lectins as compared to the intact lectin, and it was also shown that 5 kGy irradiated and heat-treated lectins did not cause damage in liver tissue or mortality. In the result of immunological response, tumor necrosis factor (TNF-α) and interleukin (IL-6) levels were significantly (P < 0.05) increased in the 5 kGy gamma-irradiated lectin treated group. These results indicate that 5 kGy irradiated lectin still maintained the immunological response with reduction of toxicity. Therefore, gamma-irradiation may be an effective method for reducing the toxicity of lectin maintaining the immune response.

Return of inactivated whole-virus vaccine for superior efficacy

The swine, influenza, H1N1 outbreak in 2009 highlighted the inadequacy of the currently used antibody-based vaccine strategies as a preventive measure for combating influenza pandemics. The ultimate goal for successful control of newly arising influenza outbreaks is to design a single-shot vaccine that will provide long-lasting immunity against all strains of influenza A virus. A large amount of data from animal studies has indicated that the cross-reactive cytotoxic T (Tc) cell response against conserved influenza virus epitopes may be the key immune response needed for a universal influenza vaccine. However, decades of research have shown that the development of safe T-cell-based vaccines for influenza is not an easy task. Here, I discuss the overlooked but potentially highly advantageous inactivation method, namely, γ-ray irradiation, as a mean to reach the Holy Grail of influenza vaccinology.

Induction of antigen-specific Th1-type immune responses by gamma-irradiated recombinant Brucella abortus RB51

Brucella abortus strain RB51 is an attenuated rough mutant used as the live vaccine against bovine brucellosis in the United States and other countries. We previously reported the development of strain RB51 as a bacterial vaccine vector for inducing Th1-type immune responses against heterologous proteins. Because safety concerns may preclude the use of strain RB51-based recombinant live vaccines, we explored the ability of a gamma-irradiated recombinant RB51 strain to induce heterologous antigen-specific immune responses in BALB/c mice. Exposure of strain RB51G/LacZ expressing Escherichia coli beta-galactosidase to a minimum of 300 kilorads of gamma radiation resulted in complete loss of replicative ability. These bacteria, however, remained metabolically active and continued to synthesize beta-galactosidase. A single intraperitoneal inoculation of mice with 10(9) CFU equivalents of gamma-irradiated, but not heat-killed, RB51G/LacZ induced a beta-galactosidase-specific Th1-type immune response. Though no obvious differences were detected in immune responses to B. abortus-specific antigens, mice vaccinated with gamma-irradiated, but not heat-killed, RB51G/LacZ developed significant protection against challenge with virulent B. abortus. In vitro experiments indicated that gamma-irradiated and heat-killed RB51G/LacZ induced maturation of dendritic cells; however, stimulation with gamma-irradiated bacteria resulted in more interleukin-12 secretion. These results suggest that recombinant RB51 strains exposed to an appropriate minimum dose of gamma radiation are unable to replicate but retain their ability to stimulate Th1 immune responses against the heterologous antigens and confer protection against B. abortus challenge in mice.

Radio-detoxified endotoxin activates natural immunity: A review

It is well demonstrated that serial endotoxin injections produce endotoxin tolerance and elevate the natural immunity/resistance. However, such injections may also have harmful effects such as high fever, hypotension and abortion. For this reason endotoxin (LPS) injections are not suitable to enhance nonspecific resistance in endotoxin-sensitive species like man. Various techniques have been designed (physical, chemical, etc.) for the detoxification of endotoxins while the beneficial effects are maintained. Perhaps one of the best detoxification techniques is the treatment with ionizing radiation. The irradiation of LPS with 60Co (150 kGy) decreased its toxicity in a dose-dependent manner. Such radio-detoxified endotoxin (RD-LPS) preparations show decreased toxicity whereas the beneficial effects were preserved. Irradiation causes marked chemical alterations in LPS, such as a decrease of glucosamine, ketodeoxyoctonic and fatty acids. A single parenteral RD-LPS injection prevents various forms of shock in experimental animals. This preparation has a membrane-stabilizing effect, and thereby it can prevent the membrane-damaging effect of LPS and of some cytostatic agents. Unlike endotoxin, RD-LPS has little hypotensive effects, and the pretreatment with this preparation can prevent practically all the hemodynamic changes induced by LPS. LPS plays an important role in the pathogenesis of intestinal syndrome of radiation disease, which may be prevented by RD-LPS pretreatment up to 70% in rats. RD-LPS retains the adjuvant activity of LPS, and it serves as a good adjuvant for inactivated virus vaccines. RD-LPS can also evoke the regeneration of the immune system in irradiated animals. The decrease of nonspecific resistance in immunodeficient or immunosuppressed patients is the most important cause of opportunistic infections that may lead to sepsis like in endotoxaemia and pneumonia. Organ transplant recipients commonly die of septicaemia. Antilymphocyte serum (ALS) is used in such patients as an immunosuppressant. The augmentation of natural resistance and the induction of endotoxin tolerance are of major significance in such patients. In ALS-treated rats RD-LPS induces also tolerance against the lethal dose of LPS. This demonstrates that in spite of the suppressive effect of ALS on T-lymphocytes the induction of LPS tolerance (the enhancement of natural resistance) remains normal. Facultative pathogenic organisms may flourish and cause disease when specific and nonspecific resistance is impaired. RD-LPS can produce a significant proliferation of lymphoid cells in germ-free animals which are immunodeficient. Many other beneficial effects are preserved by RD-LPS preparations, such as the activation of macrophages and of the reticuloendothelial system and antitumor activity. On the basis of these favorable experimental results, RD-LPS has been tested on 350 surgical patients suffering from gastrointestinal tumors, patients suffering from acquired immunodeficiency syndrome (AIDS) and cancer patients treated with CYSPLATIN. RD-LPS treatment prevented sepsis and activated the bone marrow function in these patients.

Neurohormonal host defense in endotoxin shock

Lipopolysaccharide (LPS) of gram-negative bacteria is capable of activating the immune system of higher animals, which may lead to cytokine-induced lethal shock and death. LPS has little toxicity for the frog and fish, but it kills the horseshoe crab instantly by causing intravascular blood coagulation. The response to LPS evolved from simple reactions in lower animals into an intense reaction in mammals that involves a massive immune activation leading to a profound neuroendocrine and metabolic response. This is now known as the acute-phase response (APR). During APR, LPS-binding proteins (LBP) are produced by the liver in rapidly increasing quantities under the influence of interleukin-6, glucocorticoids, and catecholamines. After combination with LPS, LPB is capable of activating monocyte-macrophages and granulocytes via the CD14 surface receptor. Other receptors (CD18, 80-kDa receptor) allow for direct action by LPS of phagocytes, B and T lymphocytes, and other cells. Numerous other acute-phase proteins are produced in the liver, including C-reactive protein, complement components, fibrinogen, enzyme inhibitors, and anti-inflammatory proteins. Similar responses may be stimulated by subtoxic doses of LPS or by detoxified LPS, which manifest in endotoxin tolerance. Tolerant animals and man show increased resistance to LPS, to infections, and to various noxious insults. Infection and various forms of tissue injury are also capable of causing APR. There is much evidence to indicate that APR, which manifests in febrile illness, is an efficient host defense reaction. It is an emergency response in cases where specific immunity fails to protect the host. Therefore, the neuroimmunoregulatory network converts the immune system to a less specific, but rapid and more efficient response, APR. The hypothesis is presented that intestinal LPS serves to amplify the APR in response to various insults, which contribute to host defense, regeneration, and healing.

Stimulation of macrophages and antitumor activity of radiodetoxified endotoxin

Lipopolysaccharide of Salmonella typhimurium was irradiated with gamma radiation at 10, 15, and 30 kGy doses. A dose of 30 kGy significantly detoxified the LPS (180 times). Mice were injected intraperitoneally with the radiodetoxified LPS, and it was found that it stimulated peritoneal macrophages as was evident from the enhancement of their acid hydrolases and cellular RNA content. Both LPS and radiodetoxified LPS exhibited antitumor activity against S180 cells in Swiss mice. Treatment with 20 micrograms/mouse of either LPS or 30 kGy LPS gave maximum survival of the mice (90%). These mice were found to resist the challenge of S180 cells (1 X 10(6)).

Toxicity of microbial products in cell culture

Cytotoxicity of a mixed pyrogen preparation and its components as well as native and radiodetoxified lipopolysacharides (LPS) was determined with established HEp-2 cell cultures and by measuring plating efficiency. This proved to be more sensitive to the damaging effect of both microbe-containing LPS (Escherichia coli) and purified LPS. Microorganisms without this compound (Lactobacillus casei, Streptococcus faecalis) seem to be more infifferent on cells, even Saccharomyces cerevisiae has a marked augmenting effect on cell plating. Divergence in null-toxicity between the established cultures and plating efficiency makes it possible to presume that the primary effect of microorganisms on epithelial cells is medited by LPS, and the subsequent liberation of lysosomal proteinases is responsible for major biological effects.

Prevention of cardiac damage induced by formyl-leurosine, a potent cytostatic agent, by radio-detoxified endotoxin (Tolerin) in dogs

Radio-detoxified endotoxin (Tolerin), produced by 60Co-gamma irradiation of Escherichia coli 089 endotoxin, can protect dogs against the acute cardiotoxic side-effects of formyl-leurosine, a semi-synthetic Vinca derivative with promising antineoplastic potency. Formyl-leurosine induces a rapid decrease in arterial blood pressure and diminishes the contractile force of the myocardium in the anaesthetized dog. These responses indicate a direct pharmacologic relaxant effect of the drug on the heart and vasculature smooth muscle. The early cardiovascular depression is of short duration and is unaffected by Tolerin. Tolerin can prevent, however, the secondary, more dangerous phase of circulatory depression that is associated with the severe cardiotoxic manifestations of the drug, as demonstrated by hemodynamic and morphologic (light and electronmicroscopic) patterns.

Physical and biological properties of U.S. standard endotoxin EC after exposure to ionizing radiation

Techniques that reduce the toxicity of bacterial endotoxins are useful for studying the relationship between structure and biological activity. We used ionizing radiation to detoxify a highly refined endotoxin preparation. U.S. standard endotoxin EC. Dose-dependent changes occurred by exposure to 60Co-radiation in the physical properties and biological activities of the endotoxin. Sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis showed gradual loss of the polysaccharide components (O-side chain and R-core) from the endotoxin molecules. In contrast, although endotoxin revealed a complex absorption pattern in the UV range, radiation treatment failed to modify that pattern. Dose-related destruction of the primary toxic component, lipid A, was suggested by the results of activity tests: both the pyrogenicity and limulus reactivity of the endotoxin were destroyed by increasing doses of radiation. The results indicate that the detoxification is probably due to multiple effects of the ionizing radiation on bacterial lipopolysaccharides, and the action involves (i) the destruction of polysaccharide moieties and possibly (ii) the alteration of lipid A component of the endotoxin molecule.

Effect of radio-detoxified endotoxin on the liver microsomal drug metabolizing enzyme system in rats

E. coli endotoxin (LPS) depresses the hepatic microsomal mono-oxygenase activity. Radio-detoxified LPS (TOLERIN: 60 Co irradiated endotoxin preparation) decreases this biotransforming activity to a smaller extent. Phenobarbital, an inducer of this mono-oxygenase system, failed to induce in LPS-treated animals. In radio-detoxified LPS-treated rats, phenobarbital induced the mono-oxygenase and almost fully restored the biotransformation.

Biologic preparation of diseased root surfaces

Untreated periodontally-involved teeth contain cementum-bound endotoxin, that may prevent periodontal new attachment during healing after pocket therapy. The purpose of this study was to restore biocompatibility to diseased root surfaces by a non-invasive treatment. Untreated human teeth removed for severe chronic periodontal disease were split buccolingually, the level of connective tissue was scribed on the roots, the specimens cleaned of plaque and visible calculus, and autoclaved. Cementum removal was not attempted. One member of each pair was treated with phosphate-buffered saline as a control. Sodium desoxycholate (2%), Cohn plasma fraction IV1 (5%), or deoxycholate followed by plasma fraction were applied for one minute. Roots were incubated in a suspension of gingival fibroblasts for 48 hours, then rinsed, fixed, and stained. Counts were made of the number of attached cells at 40 x magnification using an ocular grid. There was a significant increase (p less than 0.01) of the combination treatment over controls. All treatments provided a biological surface for attachment of fibroblasts, in vitro, compared to untreated roots.

Radiation induced alterations in the endotoxin of S. typhimurium

The lipopolysaccharide (LPS) of S. typhimurium has been shown to be significantly detoxified after in vivo irradiation at 500 krad. Radiation is thus a useful method for converting endotoxin into toxoid. The structural alterations in the detoxified LPS are shown to be mainly in the lipid A molecule, resulting in the loss of beta-hydroxymyristic acid.

Interactions of radio-detoxified Escherichia coli endotoxin preparations with the complement system

Escherichia coli O89 lipopolysaccharide (LPS) was treated with different doses of gamma irradiation (5, 10, 15, and 20 Mrad). Various biological activities such as lethal effect, decrease in arterial blood pressure in dogs, and interaction with the complement system were determined for the parent and irradiated preparations. Irradiation of LPS significantly and in a dose-dependent manner decreased its lethal and blood pressure-depressing effects along with its ability to activate the complement system. In contrast, radio-detoxified LPS fixed more strongly the isolated human C1 than did the parent LPS. The possible connection between the toxicity of endotoxin and endotoxin-induced complement activation is discussed.

Characteristics of Endotoxin-Altering Fractions Derived from Normal Serum III. Isolation and Properties of Horse Serum α 2 -Macroglobulin

The endotoxin-altering activity of fractions isolated from normal horse serum was examined by incubation of Salmonella typhosa strain 0-901 endotoxin (Boivin) in a solution of the fraction, and subsequent quantitation of any diminution in the capacity of endotoxin to be precipitated by specific anti-endotoxin antiserum. The horse serum fraction isolated by precipitation with ammonium sulfate at a concentration between 1.6 and 2.7 m was incubated with Pronase PA and then with trypsin. When this partly digested fraction was passed twice through a Sephadex G-200 column and eluted with 0.2 m tris(hydroxymethyl)aminomethane buffer, most of the endotoxinaltering activity was found in the first protein peak designated F-1a. F-1a was found to be homogeneous and corresponded to an α 2 -macroglobulin by the techniques of electrophoresis, immunodiffusion, and ultracentrifugation. Approximately 100-fold more F-1a than endotoxin was needed to reduce the antigenicity of the endotoxin by one-half. Alteration was increased when F-1a was incubated with the endotoxin at acid p H or at 45 C rather than at 37 C and was lost after heating F-1a at 56 C for 30 min. N -ethylmaleimide increased the endotoxin-altering activity of horse serum, F-1a, and human plasma fraction III 0 , whereas p -chloromercuribenzoate did not. On the other hand, diazonium-1-H-tetrazole, iodoacetic acid, and benzylchloride suppressed the activity of F-1a. When the interaction of endotoxin and F-1a was examined by immunodiffusion techniques, depolymerization of the endotoxin molecule was indicated. The endotoxin-altering factor of horse serum is discussed in relation to the mechanisms of other known reagents, such as deoxycholate and sodium lauryl sulfate.

Toxicity of Pasteurella tularensis killed by ionizing radiation

Approximately 2 x 10(11) viable Pasteurella tularensis cells per ml, contained in suspensions, were killed by exposure to 10(6) r of gamma-radiation. When injected intraperitoneally into mice, the irradiated suspensions initially contained about 10 ld(50) per ml, and immunized mice against challenge with fully virulent strains of P. tularensis. Toxicity and immunizing activity of the suspensions decreased significantly within a few days at 5 C. Mice were protected against the toxin by immune serum or by prior injection of endotoxin of Escherichia coli. Cortisone did not protect against the newly prepared suspension, but was effective against the aged suspension. Lethal doses of newly prepared suspension for guinea pigs and rabbits were approximately 0.5 ml and 2 ml, respectively. Cortisone protected rabbits, but not guinea pigs, against lethal challenge. Pyrogenic effects resembling those shown by endotoxin-containing suspensions were demonstrated in rabbits. The results suggested that two toxins are responsible for the toxicity of irradiated suspensions of P. tularensis: one labile and associated with the immunizing activity of the suspension, the other more stable and resembling classical endotoxin.

Immunogenicity of irradiated Salmonella typhimurium cells and endotoxin

The effects of high doses of radiation (1, 5, or 20 Mrad) on the toxicity, pyrogenicity, and immunogenicity of Salmonella typhimurium cells and endotoxin were studied. Toxicity decreased progressively after exposure to 1, 5, or 20 Mrad. The lethal effect of 1-Mrad exposed cells was greater than that of heat-, acetone-, or alcohol-killed preparations. An amount of 5 Mrad is about a 50% end point in terms of inactivation of the lethal lipopolysaccharide or cell-associated determinants. The fever response to radiation-killed salmonellae decreased between 1- and 20-Mrad exposure. The immunogenicity of 1-Mrad-treated cells usually exceeded that of nonirradiated preparations in mouse-protection tests. With increasing radiation doses, there was a dramatic decrease in, but not an abolition of, immunogenicity. Preparations exposed to 20 Mrad which were nonlethal afforded significant protection. The results are interpreted as a reflection of a dissociation of the primary and secondary toxic determinants of endotoxin after irradiation. The data indicate the potential value of radiation sterilization as a means of production of Salmonella vaccine.