cremoris on immune responses to keyhole limpet hemocyanin immunization and gut microbiota: A randomized placebo-controlled trial in healthy volunteers

Introduction

Lactococcus lactis spp. cremoris has been associated with promising immunomodulatory results in preclinical trials. The aim of this study was to investigate the pharmacodynamic (PD) effects of three monoclonal microbial formulations of L. lactis spp. cremoris (EDP1066) on the immune response to keyhole limpet hemocyanin (KLH). Potential effects on the gut microbiota were also investigated.

Methods

The trial was registered on Netherlands Trial Register (trial ID NL7519, https://trialsearch.who.int). Eighty-one healthy subjects (median 28, range 18-59 years) were randomized to 28 days of enteric-coated capsules at five doses (n = 13) (1.5 * 1012 total cells daily), freeze-dried powder at one dose (n = 12) (3.0 * 1011 total cells daily) or five doses (n = 12), minitablets at one dose (n = 12) or five doses (n = 12), or placebo (n = 20) prior to KLH immunization. Antibody responses and circulating regulatory T cells (Tregs) were measured after KLH immunization, and skin responses were evaluated after a KLH rechallenge by laser speckle contrast imaging and multispectral imaging. Ex vivo lymphocyte (phytohemagglutinin) and monocyte (lipopolysaccharide (LPS)) cytokine release assays were explored in the minitablet-treated groups only. The prevalence of L. lactis spp. cremoris in the gastrointestinal tract and the impact on the fecal microbiota were assessed by qPCR and 16S rRNA sequencing, respectively.

Results

Repeated-measures analysis of covariances revealed no significant treatment effects on the antibody responses to KLH, number of Tregs, or KLH skin rechallenge outcomes. Ex vivo LPS-driven cytokine responses in whole blood were lower in the low dose minitablet group compared to placebo: tumor necrosis factor (estimated difference (ED) from placebo: -44.2%, 95% confidence interval (CI) -65.3% to -10.3%), interleukin (IL)-1β (ED -41.4%, 95% CI -63.5% to -5.8%), and IL-6 (ED -39.2%, 95% CI -56.8% to -14.5%). The fecal presence of L. lactis spp. cremoris increased during treatment by all EDP1066 formulations and normalized 5 days after the last dose. Microbiome α-diversity did not change by the treatments compared to placebo.

Discussion

The EDP1066 formulations did not affect the immune response to KLH immunization in healthy individuals. However, exposure to L. lactis spp. cremoris in minitablet formulation impacted ex vivo whole blood LPS cytokine response. The clinical impact of these effects awaits further investigations.

Netherlands Trial Register

trialsearch.who.int, trial ID NL7519.

Paraquat Preferentially Induces Apoptosis of Late Stage Effector Lymphocyte and Impairs Memory Immune Response in Mice

Paraquat (PQ) is a toxic non-selective herbicide. To date, the effect of PQ on memory immune response is still unknown. We investigated the impact of PQ on memory immune response. Adult C57BL/6 mice were subcutaneously injected with 2 mg/kg PQ, 20 mg/kg PQ or vehicle control every three days for two weeks. A single injection of keyhole limpet hemocyanin (KLH) at day four after the initial PQ treatment was used to induce a primary immune response; a second KLH challenge was performed at three months post the first KLH immunization to induce a secondary immune response. In steady state, treatment with 20 mg/kg PQ reduced the level of serum total IgG, but not that of IgM; treatment with 20 mg/kg PQ decreased the number of effector and memory lymphocytes, but not naïve or inactivated lymphocytes. During the primary immune response to KLH, treatment with 20 mg/kg PQ did not influence the proliferation of lymphocytes or expression of co-stimulatory molecules. Instead, treatment with 20 mg/kg PQ increased the apoptosis of lymphocytes at late stage, but not early stage of the primary immune response. During the secondary immune response to KLH, treatment with 20 mg/kg PQ reduced the serum anti-KLH IgG and KLH-responsive CD4 T cells and B cells. Moreover, effector or activated lymphocytes were more sensitive to PQ-induced apoptosis in vitro. Treatment with 2 mg/kg PQ did not impact memory immune response to KLH. Thus, treatment with 20 mg/kg PQ increased apoptosis of late stage effector cells to yield less memory cells and thereafter impair memory immune response, providing a novel understanding of the immunotoxicity of PQ.

Keyhole limpet hemocyanin induces innate immunity via Syk and Erk phosphorylation

Hemocyanin is an extracellular respiratory protein containing copper in hemolymph of invertebrates, such as Mollusk and Arthropod. Keyhole limpet hemocyanin (KLH) is one of hemocyanins and has many years of experience for vaccine developments and immunological studies in mammals including human. However, the association between KLH and the immune systems, especially the innate immune systems, remains poorly understood. The aim of this study is to clarify the direct effects of KLH on the innate immune systems. KLH activated an inflammation-related transcription factor NF-κB as much as lipopolysaccharide (LPS) in a human monocytic leukemia THP-1 reporter cell line. We have found that the KLH-induced NF-κB activation is partially involved in a spleen tyrosine kinase (Syk) pathway. We have also successfully revealed that an extracellular signal-regulated kinase (Erk), a member of mitogen-activated protein kinases, is located in an upstream of NF-κB activation induced by KLH. Furthermore, a Syk phosphorylation inhibitor partially suppressed the Erk activation in KLH-stimulated THP-1. These results suggest that both Syk and Erk associate with the KLH-induced NF-κB activation in the human monocyte.

Exploring the ocean for new drug developments: Marine pharmacology

Disease ailments are changing the patterns, and the new diseases are emerging due to changing environments. The enormous growth of world population has overburdened the existing resources for the drugs. And hence, the drug manufacturers are always on the lookout for new resources to develop effective and safe drugs for the increasing demands of the world population. Seventy-five percentage of earth's surface is covered by water but research into the pharmacology of marine organisms is limited, and most of it still remains unexplored. Marine environment represents countless and diverse resource for new drugs to combat major diseases such as cancer or malaria. It also offers an ecological resource comprising a variety of aquatic plants and animals. These aquatic organisms are screened for antibacterial, immunomodulator, anti-fungal, anti-inflammatory, anticancer, antimicrobial, neuroprotective, analgesic, and antimalarial properties. They are used for new drug developments extensively across the world. Marine pharmacology offers the scope for research on these drugs of marine origin. Few institutes in India offer such opportunities which can help us in the quest for new drugs. This is an extensive review of the drugs developed and the potential new drug candidates from marine origin along with the opportunities for research on marine derived products. It also gives the information about the institutes in India which offer marine pharmacology related courses.

Immunoreactivity of glucose transporter 5 is located in epithelial cells of the choroid plexus and ependymal cells

High fructose intake is associated with increased plasma triglyceride concentration, hepatic steatosis, impaired glucose tolerance, insulin resistance, and high blood pressure. In addition, increased fructose intake has recently been supposed to be a risk factor for dementia. However, direct effects of fructose on the brain function remain to be clarified. The localization of glucose transporter 5 (Glut5), a representative transporter of fructose, was immunohistochemically examined in the brains of humans, rats, and mice to clarify whether fructose was transported from the blood into the brain. Glut5 immunoreactivity was demonstrated to be located in the epithelial cells of the choroid plexus and the ependymal cells in the brains of humans and rats using commercial antibodies for Glut5. In addition, mRNA expression of mouse Glut5 was confirmed in the brains of mice. Immunohistochemical examination using a custom-made antibody against two regions of amino acid sequences of mouse Glut5 revealed that Glut5 immunoreactivity was also seen in the epithelial cells of the choroid plexus and the ependymal cells in the brains of mice. These findings show that Glut5 immunoreactivity is located in the epithelial cells of the choroid plexus and the ependymal cells, suggesting the possibility of the direct transportation of intravascular fructose into the brain parenchyma.

N-terminus regulation of VMAT2 mediates methamphetamine-stimulated efflux

The 20 amino acid (AA) N-terminus of the vesicular monoamine transporter 2 (VMAT2) was examined as a regulator of VMAT2 function. Removal of the first 16 or 19 AAs of the N-terminus resulted in a molecule with reduced ability to sequester [(3)H]-5HT. A glutathione-S-transferase-construct of the N-terminus underwent phosphorylation in the presence of PKC at serines 15 and 18. These putative phosphorylation sites were examined for effects on function. Phospho-mimetic substitution of serines 15 and 18 with aspartate in the full-length VMAT2 resulted in reduced [(3)H]-5HT sequestration and reduced methamphetamine (METH)-stimulated efflux of preloaded [(3)H]-5HT. In contrast, mutation of serines 15 and 18 to alanines maintained intact net substrate sequestration but eliminated METH-stimulated efflux of pre-accumulated [(3)H]-5HT. In summary, these data suggest a model in which the VMAT2 N-terminus regulates monoamine sequestration.

Selectivity of binding of PEGs and PEG-like oligomers to anti-PEG antibodies induced by methoxyPEG-proteins

The use of methoxypoly(ethylene glycol) (mPEG) in PEG conjugates of proteins and non-protein therapeutic agents has led to the recognition that the polymer components of such conjugates can induce anti-PEG antibodies (anti-PEGs) that may accelerate the clearance and reduce the efficacy of the conjugates. Others have classified anti-PEGs as "methoxy-specific" or "backbone-specific". The results of our previous research on anti-PEGs in the sera of rabbits immunized with mPEG or hydroxyPEG (HO-PEG) conjugates of three unrelated proteins were consistent with that classification (Sherman, M.R., et al., 2012. Bioconjug. Chem. 23, 485-499). Enzyme-linked immunosorbent assays (ELISAs) were performed on rabbit antisera and rabbit monoclonal anti-PEGs with competitors including 10 kDa mPEG, 10 kDa PEG diol and six linear or cyclic oligomers of oxyethylene (CH2CH2O), with molecular weights of ca. 150-264 Da. Our results demonstrate that (1) the binding affinities of anti-mPEGs depend more on the backbone lengths of the polymers and the hydrophobicities of their end-groups than on their resemblance to the methoxy terminus of the immunogenic polymer; (2) anti-PEGs raised against HO-PEG-proteins are not directed against the terminal hydroxy group, but against the backbone; (3) rabbit anti-PEGs bind to and distinguish among PEG-like oligomers with as few as three oxyethylene groups; and (4) none of the monoclonal or polyclonal anti-PEGs was absolutely "methoxy-specific" or "backbone-specific", but displayed distinct relative selectivities. If these results are relevant to human immune responses, the clinical use of stable conjugates of HO-PEG with proteins and non-protein therapeutic agents would be expected to produce fewer and less intense immune responses than those induced by conjugates with mPEG or PEGs with larger alkoxy groups.

Effects of intestinal bacteria-derived p-cresyl sulfate on Th1-type immune response in vivo and in vitro

Protein fermentation by intestinal bacteria generates various compounds that are not synthesized by their hosts. An example is p-cresol, which is produced from tyrosine. Patients with chronic kidney disease (CKD) accumulate high concentrations of intestinal bacteria-derived p-cresyl sulfate (pCS), which is the major metabolite of p-cresol, in their blood, and this accumulation contributes to certain CKD-associated disorders. Immune dysfunction is a CKD-associated disorder that frequently contributes to infectious diseases among CKD patients. Although some studies imply pCS as an etiological factor, the relation between pCS and immune systems is poorly understood. In the present study, we investigated the immunological effects of pCS derived from intestinal bacteria in mice. For this purpose, we fed mice a tyrosine-rich diet that causes the accumulation of pCS in their blood. The mice were shown to exhibit decreased Th1-driven 2, 4-dinitrofluorobenzene-induced contact hypersensitivity response. The concentration of pCS in blood was negatively correlated with the degree of the contact hypersensitivity response. In contrast, the T cell-dependent antibody response was not influenced by the accumulated pCS. We also examined the in vitro cytokine responses by T cells in the presence of pCS. The production of IFN-γ was suppressed by pCS. Further, pCS decreased the percentage of IFN-γ-producing Th1 cells. Our results suggest that intestinal bacteria-derived pCS suppressesTh1-type cellular immune responses.

A morphine conjugate vaccine attenuates the behavioral effects of morphine in rats

Vaccines for opioid dependence may provide a treatment that would reduce or slow the distribution of the drug to brain, thus reducing the drug's reinforcing effects. We tested whether a conjugate vaccine against morphine (keyhole limpet hemocyanin-6-succinylmorphine; KLH-6-SM) administered to rats would produce antibodies and show specificity for morphine or other heroin metabolites. The functional effects of the vaccine were tested with antinociceptive and conditioned place preference (CPP) tests. Rats were either vaccinated with KLH-6-SM and received two boosts 3 and 16 weeks later or served as controls and received KLH alone. Anti-morphine antibodies were produced in vaccinated rats; levels increased and were sustained at moderate levels through 24 weeks. Antibody binding was inhibited by free morphine and other heroin metabolites as demonstrated by competitive inhibition ELISA. Vaccinated rats showed reduced morphine CPP, tested during weeks 4 to 6, and decreased antinociceptive responses to morphine, tested at week 7. Brain morphine levels, assessed using gas-chromatography coupled to mass spectrometry (GC-MS) on samples obtained at 26 weeks, were significantly lower in vaccinated rats. This suggests that morphine entry into the brain was reduced or slowed. These results provide support for KLH-6-SM as a candidate vaccine for opioid dependence.

Vaccination protects rats from methamphetamine-induced impairment of behavioral responding for food

(+)-Methamphetamine (METH) addiction is a chronic disease that interferes with fundamental brain-mediated behaviors and biological functions like eating. These studies present preclinical efficacy and safety profiles for a METH conjugate vaccine (IC(KLH)-SMO9) designed to treat METH abuse. ICKLH-SMO9 efficacy and safety were assessed over a 16-week period by monitoring general health and stability of responding in a food maintained behavioral paradigm. Male Sprague-Dawley rats were trained to lever press for food reinforcers until stable behavior was established. Rats (n=9/group) were then immunized with 100 μg of a control antigenic carrier protein (IC(KLH)-Cys) or IC(KLH)-SMO9 in Alhydrogel adjuvant, with booster immunizations at 4, 8 and 12 weeks. Health, immunization site and behavior were assessed daily. No adverse effects were found. During weeks 14-16, when antibody titers and METH affinity (K(d)=13.9 ± 1.7 nM) were maximal, all rats received progressively higher METH doses (0.3-3.0 mg/kg) every 3-4 days, followed by behavioral testing. Even though the lower METH doses from 0.3 to 1.0 mg/kg produced no impairment in food maintained behavior, 3.0-mg/kg in control rats showed significantly (p<0.05) reduced response rates and number of reinforcers earned, as well as reduced food intake. In sharp contrast, the IC(KLH)-SMO9 group showed no changes in food maintained behavior at any METH dose, even though METH serum concentrations showed profound increases due to anti-METH antibody binding. These findings suggest the IC(KLH)-SMO9 vaccine is effective and safe at reducing adverse METH-induced effects, even at high METH doses.

An engineered Fc variant of an IgG eliminates all immune effector functions via structural perturbations

The Fc variant of IgG2, designated as IgG2σ, was engineered with V234A/G237A /P238S/H268A/V309L/A330S/P331S substitutions to eliminate affinity for Fcγ receptors and C1q complement protein and consequently, immune effector functions. IgG2σ was compared to other previously well-characterized Fc 'muted' variants, including aglycosylated IgG1, IgG2m4 (H268Q/V309L/A330S/P331S, changes to IgG4), and IgG4 ProAlaAla (S228P/L234A/L235A) in its capacity to bind FcγRs and activate various immune-stimulatory responses. In contrast to the previously characterized muted Fc variants, which retain selective FcγR binding and effector functions, IgG2σ shows no detectable binding to the Fcγ receptors in affinity and avidity measurements, nor any detectable antibody-dependent cytotoxicity, phagocytosis, complement activity, or Fc-mediated cytokine release. Moreover, IgG2σ shows minimal immunogenic potential by T-cell epitope analysis. The circulating half-life of IgG2σ in monkeys is extended relative to IgG1 and IgG2, in spite of similar in vitro binding to recombinant FcRn. The three-dimensional structure of the Fc, needed for assessing the basis for the absence of effector function, was compared with that of IgG2 revealing a number of conformational differences near the hinge region of the CH2 domain that result from the amino acid substitutions. Modeling reveals that at least one of the key interactions with FcγRs is disrupted by a conformational change that reorients P329 to a position that prevents it from interacting with conserved W90 and W113 residues of the FcγRs. Inspection of the structure also indicated significant changes to the conformations of D270 and P329 in the CH2 domain that could negatively impact C1q binding. Thus, structural perturbations of the Fc provide a rationale for the loss of function. In toto, these properties of IgG2σ suggest that it is a superior alternative to previously described IgG variants of minimal effector function, for future therapeutic applications of non-immunostimulatory mAb and Fc-fusion platforms.

Development of an ELISA for the quantification of the C-terminal decapeptide prothymosin α(100-109) in sera of mice infected with bacteria

Apoptosis is characterized by a series of discrete biochemical events, among which is the truncation of the nuclear polypeptide prothymosin alpha (proTα) by activated caspase-3. This early apoptotic event results in the generation of a carboxy-terminal fragment of proTα, the immunoactive decapeptide proTα(100-109). We hypothesized that the detection of increased levels of proTα(100-109) in serum can be directly correlated with the induction of massive cell apoptosis, resulting from a severe bacterial infection. Thus, using high-affinity-purified polyclonal antibodies (Abs), raised in rabbits and a prototype antibody-capture system, we developed a highly sensitive and specific competitive ELISA for proTα(100-109). The sensitivity of the ELISA (0.1ng/mL to 10μg/mL) is acceptable for the quantification of the decapeptide in serum samples. To assess our initial hypothesis, we determined the concentration of proTα(100-109) in the sera of mice infected with the bacterium Streptococcus pyogenes over the course of the infection. We show that serum concentration of proTα(100-109) was marginal to undetectable before infection, increased over time and peaked at 72h postinfection. In silico analysis suggests that the Abs generated are unlikely to cross-react with any other unrelated mouse or bacterial protein. Further validation of our ELISA using serum samples from humans, infected with bacteria, may provide a useful tool to differentiate the causative agent of a potentially lethal septic infection.

Treating chronic arsenic toxicity with high selenium lentil diets

Arsenic (As) toxicity causes serious health problems in humans, especially in the Indo-Gangetic plains and mountainous areas of China. Selenium (Se), an essential micronutrient is a potential mitigator of As toxicity due to its antioxidant and antagonistic properties. Selenium is seriously deficient in soils world-wide but is present at high, yet non-toxic levels in the great plains of North America. We evaluate the potential of dietary Se in counteracting chronic As toxicity in rats through serum biochemistry, blood glutathione levels, immunotoxicity (antibody response), liver peroxidative stress, thyroid response and As levels in tissues and excreta. To achieve this, we compare diets based on high-Se Saskatchewan (SK) lentils versus low-Se lentils from United States. Rats drank control (0ppm As) or As (40ppm As) water while consuming SK lentils (0.3ppm Se) or northwestern USA lentils (<0.01ppm Se) diets for 14weeks. Rats on high Se diets had higher glutathione levels regardless of As exposure, recovered antibody responses in As-exposed group, higher fecal and urinary As excretion and lower renal As residues. Selenium deficiency caused greater hepatic peroxidative damage in the As exposed animals. Thyroid hormones, triiodothyronine (T3) and thyroxine (T4), were not different. After 14weeks of As exposure, health indicators in rats improved in response to the high Se lentil diets. Our results indicate that high Se lentils have a potential to mitigate As toxicity in laboratory mammals, which we hope will translate into benefits for As exposed humans.

Assessment of the respiratory sensitization potential of proteins using an enhanced mouse intranasal test (MINT)

There remains a need for a simple and predictive animal model to identify potential respiratory sensitizers. The mouse intranasal test (MINT) was developed to assess the relative allergic potential of detergent enzymes, however, the experimental endpoints were limited to evaluation of antibody levels. The present study was designed to evaluate additional endpoints (serum and allergic antibody levels, pulmonary inflammation and airway hyperresponsiveness (AHR)) to determine their value in improving the predictive accuracy of the MINT. BDF1 mice were intranasally instilled on days 1, 3, 10, 17 and 24 with subtilisin, ovalbumin, betalactoglobulin, mouse serum albumin or keyhole limpet hemocyanin; challenged with aerosolized methacholine or the sensitizing protein on day 29 to assess AHR, and sacrificed on day 29 or 30. Under the conditions of this study, evaluation of AHR did not improve the predictive power of this experimental model. Allergic antibody responses and IgG isotype characterization proved to be the most sensitive and reliable indicators of the protein allergenic potential with BAL responses providing additional insight. These data highlight that the evaluation of the respiratory sensitization potential of proteins can be best informed when multiple parameters are evaluated and that further improvements and refinements of the assay are necessary.

A vaccine against methamphetamine attenuates its behavioral effects in mice

BACKGROUND

Vaccines have treatment potential for methamphetamine (MA) addiction. We tested whether a conjugate vaccine against MA (succinyl-methamphetamine-keyhole limpet hemocyanin carrier protein; SMA-KLH) would generate MA antibodies and alter MA-induced behaviors.

METHODS

Mice were injected with SMA-KLH and received booster administrations 3 and 20 weeks later. Serum antibody titers reached peak levels by 4-6 weeks, remained at a modest level through 18 weeks, peaked again at 22 weeks after the second boost, and were still elevated at 35 weeks. At 7 weeks, groups of vaccinated and non-vaccinated mice were administered one of three MA doses (1, 2 or 3 mg/kg) to assess locomotor activity.

RESULTS

Non-vaccinated mice showed dose-dependent effects of MA with hypolocomotion at the lowest dose and elevated activity levels at the highest dose. Both dose effects were reduced in SMA-KLH groups, particularly low dose-induced hypolocomotion at later times post MA administration. Separate groups of vaccinated and non-vaccinated mice were trained in MA place conditioning at 30 weeks with either 0 (vehicle) or 0.5mg/kg MA. Although times spent in the MA-paired side did not differ between groups on test vs. baseline sessions, SMA-KLH mice conditioned with MA showed reduced conditioned approach behaviors and decreased conditioned activity levels compared to control groups.

CONCLUSION

These data suggest SMA-KLH attenuates the ability of MA to support place conditioning and reduces or delays its locomotor effects. Overall, results support SMA-KLH as a candidate MA vaccine.

Evolution of molluscan hemocyanin structures

Hemocyanin transports oxygen in the hemolymph of many molluscs and arthropods and is therefore a central physiological factor in these animals. Molluscan hemocyanin molecules are oligomers composed of many protein subunits that in turn encompass subsets of distinct functional units. The structure and evolution of molluscan hemocyanin have been studied for decades, but it required the recent progress in DNA sequencing, X-ray crystallography and 3D electron microscopy to produce a detailed view of their structure and evolution. The basic quaternary structure is a cylindrical decamer 35nm in diameter, consisting of wall and collar (typically at one end of the cylinder). Depending on the animal species, decamers, didecamers and multidecamers occur in the hemolymph. Whereas the wall architecture of the decamer seems to be invariant, four different types of collar have been identified in different molluscan taxa. Correspondingly, there exist four subunit types that differ in their collar functional units and range from 350 to 550kDa. Thus, molluscan hemocyanin subunits are among the largest polypeptides in nature. In this report, recent 3D reconstructions are used to explain and visualize the different functional units, subunits and quaternary structures of molluscan hemocyanins. Moreover, on the basis of DNA analyses and structural considerations, their possible evolution is traced. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.

Systemic immunity influences hearing preservation in cochlear implantation

HYPOTHESIS

To determine whether a systemic immune response influences hearing thresholds and tissue response after cochlear implantation of hearing guinea pigs.

METHODS

Guinea pigs were inoculated with sterile antigen (Keyhole limpet hemocyanin) 3 weeks before cochlear implantation. Pure-tone auditory brainstem response thresholds were performed before implantation and 1 and 4 weeks later. Dexamethasone phosphate 20% was adsorbed onto a hyaluronic acid carboxymethylcellulose sponge and was applied to the round window for 30 minutes before electrode insertion. Normal saline was used for controls. Cochlear histology was performed at 4 weeks after implantation to assess the tissue response to implantation. To control for the effect of keyhole limpet hemocyanin priming, a group of unprimed animals underwent cochlear implantation with a saline-soaked pledget applied to the round window.

RESULTS

Keyhole limpet hemocyanin priming had no significant detrimental effect on thresholds without implantation. Thresholds were elevated after implantation across all frequencies tested (2-32 kHz) in primed animals but only at higher frequencies (4-32 kHz) in unprimed controls. In primed animals, dexamethasone treatment significantly reduced threshold shifts at 2 and 8 kHz. Keyhole limpet hemocyanin led to the more frequent observation of lymphocytes in the tissue response to the implant.

CONCLUSION

Systemic immune activation at the time of cochlear implantation broadened the range of frequencies experiencing elevated thresholds after implantation. Local dexamethasone provides partial protection against this hearing loss, but the degree and extent of protection are less compared to previous studies with unprimed animals.

A phase I study of autologous dendritic cell-based immunotherapy for patients with unresectable primary liver cancer

BACKGROUND/AIMS

To evaluate the safety and feasibility of immunotherapy based on autologous dendritic cells (DC) for patients with unresectable primary liver cancer (PLC).

METHODS

A total of ten patients were enrolled and immunized with DCs. Autologous DCs were generated ex vivo in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). Cells were then pulsed with tumor lysate (TL), tumor necrosis factor-alpha (TNF-alpha) and keyhole limpet hemocyanin (KLH). Non-adherent cells were collected on day 9 and cells were administered into the inguinal lymph node. Each patient received 1-10 x 10(6) cells four times at weekly intervals.

RESULTS

Immunization was well tolerated in all patients without significant toxicity. DC vaccination induced delayed-type hypersensitivity (DTH) against KLH in seven out of ten patients. In one patient, one of the two liver tumors (tumor in segment 7, 13 mm in diameter) decreased in size to 7 mm and showed necrotic change on computed tomography examination after eight immunizations. In two patients, serum levels of tumor markers decreased after vaccination.

CONCLUSION

The present clinical trial suggested that immunization by TL-pulsed DCs is feasible in patients with unresectable PLC without any toxicity. Further improvement in the clinical results of immunotherapy might be expected by modifying the therapeutic protocol.

Carbohydrate vaccines that induce antibodies against cancer. 2. Previous experience and future plans

The primary function of antibodies is the elimination of circulating viral or bacterial pathogens from the blood-stream, lymphatics and interstitial spaces, and so, once induced, antibodies should be ideally suited for eliminating tumor cells and micrometastases from these spaces as well. Natural or tumor-induced and vaccine-induced antibodies against human cancer-associated antigens have been correlated with an improved clinical outcome. In the mouse, passive administration of monoclonal antibodies against cell-surface antigens 1–4 days after tumor challenge, and active induction of antibodies with vaccines, has resulted in prolonged survival or complete protection from tumor growth. This is a setting similar to the adjuvant setting in humans. Carbohydrates are the most abundant antigens at the cell surface of cancer cells, where they play important roles in cell-cell interactions, proliferation and the metastatic process. They have been shown to be excellent targets for immune attack by antibodies against human cancers, especially in the adjuvant setting. Vaccines containing these carbohydrate antigens covalently attached to immunogenic carrier proteins, such as KLH, plus potent immunological adjuvants, such as QS-21, effectively induce antibodies against these antigens in patients, which can result in complement-mediated lysis of antigen-positive tumor cells. Phase III trials with KLH conjugate vaccines have been initiated in the adjuvant setting against two carbohydrate antigens, the ganglioside GM2 and the blood-group-related antigen sTn. As the immunogenicity of additional vaccines is confirmed in small pilot trials, trials with polyvalent vaccines against two to five different antigens tailored for particular cancer types are planned.

Significant prolongation of disease-free period gained by oral polysaccharide K (PSK) administration after curative surgical operation of colorectal cancer

To examine the clinical efficacy and the mechanism of action of polysaccharide K (PSK), a protein-bound polysaccharide extracted from a Basidiomycetes fungus, a randomized double-blind trial was performed by administering PSK to 56 patients and a placebo to another group of 55 patients after surgical operations on their colorectal cancers. The rate of patients in remission (or disease-free) was significantly higher in the PSK group than in the placebo group; the difference between both groups was statistically significant at P less than 0.05 by the log-rank test. The survival rate of patients was also significantly (P less than 0.05) higher in the PSK group than in the control group. The most significant laboratory finding was that polymorphonuclear leukocytes from PSK-treated patients showed remarkable enhancement in their activities, such as random and/or chemotactic locomotion, and phagocytic activity, when compared with those in the control group. In conclusion, PSK was useful as a maintenance therapy for patients after their curative surgical operations for colorectal cancer. The beneficial effects were probably due to the activation of leukocyte functions as one of the many biological-response-modifying (activities induced by PSK).