Removal of endotoxin from protein solutions by phase separation using Triton X-114

An extended mini-complement factor H molecule ameliorates experimental C3 glomerulopathy

Abnormal regulation of the complement alternative pathway is associated with C3 glomerulopathy. Complement factor H is the main plasma regulator of the alternative pathway and consists of 20 short consensus repeat (SCR) domains. Although recombinant full-length factor H represents a logical treatment for C3 glomerulopathy, its production has proved challenging. We and others have designed recombinant mini-factor H proteins in which ‘non-essential' SCR domains have been removed. Here, we report the in vitro and in vivo effects of a mini-complement factor H protein, FH^{1–5^18–20}, using the unique factor H–deficient (Cfh−/−) mouse model of C3 glomerulopathy. FH^{1–5^18–20} is comprised of the key complement regulatory domains (SCRs 1–5) linked to the surface recognition domains (SCRs 18–20). Intraperitoneal injection of FH^{1–5^18–20} in Cfh−/− mice reduced abnormal glomerular C3 deposition, similar to full-length factor H. Systemic effects on plasma alternative pathway control were comparatively modest, in association with a short half-life. Thus, FH^{1–5^18–20} is a potential therapeutic agent for C3 glomerulopathy and other renal conditions with alternative pathway-mediated tissue injury.

Bacterial membranes enhance the immunogenicity and protective capacity of the surface exposed tick Subolesin-Anaplasma marginale MSP1a chimeric antigen

Ticks are vectors of diseases that affect humans and animals worldwide. Tick vaccines have been proposed as a cost-effective and environmentally sound alternative for tick control. Recently, the Rhipicephalus microplus Subolesin (SUB)-Anaplasma marginale MSP1a chimeric antigen was produced in Escherichia coli as membrane-bound and exposed protein and used to protect vaccinated cattle against tick infestations. In this research, lipidomics and proteomics characterization of the E. coli membrane-bound SUB-MSP1a antigen showed the presence of components with potential adjuvant effect. Furthermore, vaccination with membrane-free SUB-MSP1a and bacterial membranes containing SUB-MSP1a showed that bacterial membranes enhance the immunogenicity of the SUB-MSP1a antigen in animal models. R. microplus female ticks were capillary-fed with sera from pigs orally immunized with membrane-free SUB, membrane bound SUB-MSP1a and saline control. Ticks ingested antibodies added to the blood meal and the effect of these antibodies on reduction of tick weight was shown for membrane bound SUB-MSP1a but not SUB when compared to control. Using the simple and cost-effective process developed for the purification of membrane-bound SUB-MSP1a, endotoxin levels were within limits accepted for recombinant vaccines. These results provide further support for the development of tick vaccines using E. coli membranes exposing chimeric antigens such as SUB-MSP1a.

Excretory/secretory products of the carcinogenic liver fluke are endocytosed by human cholangiocytes and drive cell proliferation and IL6 production

Liver fluke infection caused by Opisthorchis viverrini remains a major public health problem in many parts of Asia including Thailand, Lao PDR, Vietnam and Cambodia, where there is a strikingly high incidence of cholangiocarcinoma (CCA - hepatic cancer of the bile duct epithelium). Among other factors, uptake of O. viverrini excretory/secretory products (OvES) by biliary epithelial cells has been postulated to be responsible for chronic inflammation and proliferation of cholangiocytes, but the mechanisms by which cells internalise O. viverrini excretory/secretory products are still unknown. Herein we incubated normal human cholangiocytes (H69), human cholangiocarcinoma cells (KKU-100, KKU-M156) and human colon cancer (Caco-2) cells with O. viverrini excretory/secretory products and analysed the effects of different endocytic inhibitors to address the mechanism of cellular uptake of ES proteins. Opisthorchis viverrini excretory/secretory products was internalised preferentially by liver cell lines, and most efficiently/rapidly by H69 cells. There was no evidence for trafficking of ES proteins to cholangiocyte organelles, and most of the fluorescence was detected in the cytoplasm. Pretreatment with clathrin inhibitors significantly reduced the uptake of O. viverrini excretory/secretory products, particularly by H69 cells. Opisthorchis viverrini excretory/secretory products induced proliferation of liver cells (H69 and CCA lines) but not intestinal (Caco-2) cells, and proliferation was blocked using inhibitors of the classical endocytic pathways (clathrin and caveolae). Opisthorchis viverrini excretory/secretory products drove IL6 secretion by H69 cells but not Caco-2 cells, and cytokine secretion was significantly reduced by endocytosis inhibitors. This the first known study to address the endocytosis of helminth ES proteins by host epithelial cells and sheds light on the pathways by which this parasite causes one of the most devastating forms of cancer in south-eastern Asia.

Targeting glioblastoma via intranasal administration of Ff bacteriophages

Bacteriophages (phages) are ubiquitous viruses that control the growth and diversity of bacteria. Although they have no tropism to mammalian cells, accumulated evidence suggests that phages are not neutral to the mammalian macro-host and can promote immunomodulatory and anti-tumorigenic activities. Here we demonstrate that Ff phages that do not display any proteins or peptides could inhibit the growth of subcutaneous glioblastoma tumors in mice and that this activity is mediated in part by lipopolysaccharide molecules attached to their virion. Using the intranasal route, a non-invasive approach to deliver therapeutics directly to the CNS, we further show that phages rapidly accumulate in the brains of mice and could attenuate progression of orthotopic glioblastoma. Taken together, this study provides new insight into phages non-bacterial activities and demonstrates the feasibility of delivering Ff phages intranasally to treat brain malignancies.

Apoptosis of cholangiocytes modulated by thioredoxin of carcinogenic liver fluke

Chronic infection with the food-borne liver fluke, Opisthorchis viverrini, frequently induces cancer of the bile ducts, cholangiocarcinoma. Opisthorchiasis is endemic in Thailand, Lao PDR, Cambodia and Vietnam, where eating undercooked freshwater fish carrying the juvenile stage of this pathogen leads to human infection. Because inhibition of apoptosis facilitates carcinogenesis, this study investigated modulation by thioredoxin from O. viverrini of apoptosis of bile duct epithelial cells, cholangiocytes. Cells of a cholangiocyte line were incubated with the parasite enzyme after which they were exposed hydrogen peroxide. Oxidative stress-induced apoptosis was monitored using flow cytometry, growth in real time and imaging of living cells using laser confocal microscopy. Immunolocalization revealed liver fluke thioredoxin within cholangiocytes. Cells exposed to thioredoxin downregulated apoptotic genes in the mitogen activated protein kinases pathway and upregulated anti-apoptosis-related genes including apoptosis signaling kinase 1, caspase 9, caspase 8, caspase 3, survivin and others. Western blots of immunoprecipitates of cell lysates revealed binding of thioredoxin to apoptosis signaling kinase 1. Together the findings indicated that thioredoxin from O. viverrini inhibited oxidative stress-induced apoptosis of bile duct epithelial cells, which supports a role for this liver fluke oxidoreductase in opisthorchiasis-induced cholangiocarcinogenesis.

P. falciparum and P. vivax Epitope-Focused VLPs Elicit Sterile Immunity to Blood Stage Infections

In order to design P. falciparum preerythrocytic vaccine candidates, a library of circumsporozoite (CS) T and B cell epitopes displayed on the woodchuck hepatitis virus core antigen (WHcAg) VLP platform was produced. To test the protective efficacy of the WHcAg-CS VLPs, hybrid CS P. berghei/P. falciparum (Pb/Pf) sporozoites were used to challenge immunized mice. VLPs carrying 1 or 2 different CS repeat B cell epitopes and 3 VLPs carrying different CS non-repeat B cell epitopes elicited high levels of anti-insert antibodies (Abs). Whereas, VLPs carrying CS repeat B cell epitopes conferred 98% protection of the liver against a 10,000 Pb/Pf sporozoite challenge, VLPs carrying the CS non-repeat B cell eptiopes were minimally-to-non-protective. One-to-three CS-specific CD4/CD8 T cell sites were also fused to VLPs, which primed CS-specific as well as WHcAg-specific T cells. However, a VLP carrying only the 3 T cell domains failed to protect against a sporozoite challenge, indicating a requirement for anti-CS repeat Abs. A VLP carrying 2 CS repeat B cell epitopes and 3 CS T cell sites in alum adjuvant elicited high titer anti-CS Abs (endpoint dilution titer >1x10⁶) and provided 80–100% protection against blood stage malaria. Using a similar strategy, VLPs were constructed carrying P. vivax CS repeat B cell epitopes (WHc-Pv-78), which elicited high levels of anti-CS Abs and conferred 99% protection of the liver against a 10,000 Pb/Pv sporozoite challenge and elicited sterile immunity to blood stage infection. These results indicate that immunization with epitope-focused VLPs carrying selected B and T cell epitopes from the P. falciparum and P. vivax CS proteins can elicit sterile immunity against blood stage malaria. Hybrid WHcAg-CS VLPs could provide the basis for a bivalent P. falciparum/P. vivax malaria vaccine.

Antigen delivery by filamentous bacteriophage fd displaying an anti-DEC-205 single-chain variable fragment confers adjuvanticity by triggering a TLR9-mediated immune response

Filamentous bacteriophage fd particles delivering antigenic determinants via DEC-205 (fdsc-αDEC) represent a powerful delivery system that induces CD8⁺ T-cell responses even when administered in the absence of adjuvants or maturation stimuli for dendritic cells. In order to investigate the mechanisms of this activity, RNA-Sequencing of fd-pulsed dendritic cells was performed. A significant differential expression of genes involved in innate immunity, co-stimulation and cytokine production was observed. In agreement with these findings, we demonstrate that induction of proinflammatory cytokines and type I interferon by fdsc-αDEC was MYD88 mediated and TLR9 dependent. We also found that fdsc-αDEC is delivered into LAMP-1-positive compartments and co-localizes with TLR9. Thus, phage particles containing a single-strand DNA genome rich in CpG motifs delivered via DEC-205 are able to intercept and trigger the active TLR9 innate immune receptor into late endosome/lysosomes and to enhance the immunogenicity of the displayed antigenic determinants. These findings make fd bacteriophage a valuable tool for immunization without administering exogenous adjuvants.

Removal of endotoxins from bacteriophage preparations by extraction with organic solvents

Lipopolysaccharide (LPS, endotoxin, pyrogen) constitutes a very troubling contaminant of crude phage lysates produced in Gram-negative bacteria. Toxicity of LPS depends on the strong innate immunity response including the cytokines. Therefore, its removal is important for bacteriophage applications. In this paper, we present a procedure for extractive removal of endotoxin from bacteriophage preparations with water immiscible solvents (1-octanol or 1-butanol). During extraction most of the phage lytic activity is retained in the aqueous phase, while endotoxin accumulates in the organic solvent. The levels of endotoxin (expressed as endotoxin units, EU) in the aqueous bacteriophage-containing fraction determined by limulus amebocyte lysate or EndoLISA assay were exceptionally low. While the initial endotoxin levels in the crude phage lysates ranged between 10³ and 10⁵ EU/ml the average level after organic extraction remaining in the aqueous fraction was 5.3 EU/ml. These values when related to phage titers decreased from 10³-10⁵ EU/10⁹ PFU (plaque forming units) down to an average of 2.8 EU/10⁹ PFU. The purification procedure is scalable, efficient and applicable to all the bacteriophages tested: T4, HAP1 (E. coli) and F8 (P. aeruginosa).

Mast cells present protrusions into blood vessels upon tracheal allergen challenge in mice

Mast cells (MC) and myeloid dendritic cells (DC) act proximally in detecting and processing antigens and immune insults. We sought to understand their comparative dynamic behavior with respect to the airway epithelium in the steady state and in response to an allergic stimulus in mouse trachea. We devised methods to label MC in living trachea and to demonstrate that MC and DC occupy distinct layers of the tracheal mucosa, with DC being closer to the lumen. DC numbers doubled after allergen challenge, but MC numbers remained stable. MC and DC migrated minimally in either steady state or allergen-challenge conditions, and their interactions with one another appeared to be stochastic and relatively infrequent. While DC, unlike MC, exhibited probing behaviors involving dendrites, these projections did not cross the epithelium into the airway lumen. MC typically were located too far from the epithelial surface to contact the tracheal lumen. However, MC had protrusions toward and into blood vessels, likely to load with IgE. Thus, DC and MC occupy distinct niches and engage in sessile surveillance in the mouse trachea. Little or no access of these cell types to the airway lumen suggests that trans-epithelial transport of proteins in the steady state would be required for them to access luminal antigens.

TGF-β superfamily members from the helminth Fasciola hepatica show intrinsic effects on viability and development

The helminth Fasciola hepatica causes fasciolosis throughout the world, a major disease of livestock and an emerging zoonotic disease in humans. Sustainable control mechanisms such as vaccination are urgently required. To discover potential vaccine targets we undertook a genome screen to identify members of the transforming growth factor (TGF) family of proteins. Herein we describe the discovery of three ligands belonging to this superfamily and the cloning and characterisation of an activin/TGF like molecule we term FhTLM. FhTLM has a limited expression pattern both temporally across the parasite stages but also spatially within the worm. Furthermore, a recombinant form of this protein is able to enhance the rate (or magnitude) of multiple developmental processes of the parasite indicating a conserved role for this protein superfamily in the developmental biology of a major trematode parasite. Our study demonstrates for the first time the existence of this protein superfamily within F. hepatica and assigns a function to one of the three identified ligands. Moreover further exploration of this superfamily may yield future targets for diagnostic or vaccination purposes due to its stage restricted expression and functional role.

HMGB1 Binds to Lipoteichoic Acid and Enhances TNF-α and IL-6 Production through HMGB1-Mediated Transfer of Lipoteichoic Acid to CD14 and TLR2

Lipoteichoic acid (LTA) is a component of the cell wall of Gram-positive bacteria and induces a toll-like receptor 2 (TLR2)-mediated inflammatory response upon initial binding to lipopolysaccharide-binding protein (LBP) and subsequent transfer to CD14. In this study, we identified a novel role for the nuclear protein high-mobility group box 1 (HMGB1) in LTA-mediated inflammation. Results of ELISA, surface plasmon resonance and native PAGE electrophoretic mobility shift analyses indicated that HMGB1 binds to LTA in a concentration-dependent manner and that this binding is inhibited by LBP. Native PAGE, fluorescence-based transfer and confocal imaging analyses indicated that HMGB1 catalytically disaggregates LTA and transfers LTA to CD14. NF-κB p65 nuclear transmigration, degradation of IκBα and reporter assay results demonstrated that NF-κB activity in HEK293-hTLR2/6 cells is significantly upregulated by a mixture of LTA and soluble CD14 in the presence of HMGB1. Furthermore, the production of TNF-α and IL-6 in J774A.1 and RAW264.7 cells increased significantly following treatment with a mixture of LTA and HMGB1 compared with treatment with LTA or HMGB1 alone. Thus, we propose that HMGB1 plays an important role in LTA-mediated inflammation by binding to and transferring LTA to CD14, which is subsequently transferred to TLR2 to induce an inflammatory response.

Flagellin as carrier and adjuvant in cocaine vaccine development

Cocaine abuse is problematic, directly and indirectly impacting the lives of millions, and yet existing therapies are inadequate and usually ineffective. A cocaine vaccine would be a promising alternative therapeutic option, but efficacy is hampered by variable production of anticocaine antibodies. Thus, new tactics and strategies for boosting cocaine vaccine immunogenicity must be explored. Flagellin is a bacterial protein that stimulates the innate immune response via binding to extracellular Toll-like receptor 5 (TLR5) and also via interaction with intracellular NOD-like receptor C4 (NLRC4), leading to production of pro-inflammatory cytokines. Reasoning that flagellin could serve as both carrier and adjuvant, we modified recombinant flagellin protein to display a cocaine hapten termed GNE. The resulting conjugates exhibited dose-dependent stimulation of anti-GNE antibody production. Moreover, when adjuvanted with alum, but not with liposomal MPLA, GNE-FliC was found to be better than our benchmark GNE-KLH. This work represents a new avenue for exploration in the use of hapten-flagellin conjugates to elicit antihapten immune responses.

Triggering positive selection of germinal center B cells by antigen targeting to DEC-205

Germinal centers (GCs) are the site of maturation of antibody affinity and are thus of key importance to humoral immunity. The study of B-cell dynamics and selection within the GC has been hampered by the limited number of techniques available to manipulate GC output in vivo. Here, we describe an approach to trigger positive selection of B cells in vivo by targeting antigen specifically to a subpopulation of GC B cells via the surface lectin DEC-205 and forcing their interaction with T follicular helper cells. Targeted GC B cells can then be followed over time as they progress through the stages of positive selection.

Bacillus anthracis genomic DNA enhances lethal toxin-induced cytotoxicity through TNF-α production

Background

Bacillus anthracis is the etiological agent of anthrax. Lethal toxin (LT) produced by B. anthracis is a well-known key virulence factor for anthrax because of its strong cytotoxic activity. However, little is known about the role of B. anthracis genomic DNA (BAG) in anthrax pathogenesis.

Results

We examined the effect of BAG on TNF-α production and LT-mediated cytotoxicity during B. anthracis spore infection in mouse macrophage cell lines (RAW264.7 cells and J774A.1) and BALB/c mice. Infection of RAW264.7 cells with B. anthracis spores induced TNF-α expression in a multiplicity of infection (MOI)-dependent manner, and this enhancement was attenuated by the toll-like receptor (TLR) 9 inhibitor oligodeoxynucleotide (ODN)2088. BAG led to TNF-α expression in a dose- and time-dependent manner when applied to RAW264.7 cells. TNF-α expression induced by BAG was reduced by either pretreatment with TLR9 inhibitors (ODN2088 and chloroquine (CQ)) or transfection with TLR9 siRNA. Furthermore, BAG-induced TNF-α production in TLR9^+/+ macrophages was completely abrogated in TLR9^−/− macrophages. BAG enhanced the phosphorylation of mitogen-activated protein kinases (MAPK), and BAG-induced TNF-α expression was attenuated by pretreatment with MAPK inhibitors. A reporter gene assay and confocal microscopy demonstrated that BAG increased NF-κB activation, which is responsible for TNF-α expression. Treatment with BAG alone showed no cytotoxic activity on the macrophage cell line J774A.1, whereas LT-mediated cytotoxicity was enhanced by treatment with BAG or TNF-α. Enhanced LT-induced lethality was also confirmed by BAG administration in mice. Furthermore, LT plus BAG-mediated lethality was significantly recovered by administration of Infliximab, an anti-TNF-α monoclonal antibody.

Conclusions

Our results suggest that B. anthracis DNA may contribute to anthrax pathogenesis by enhancing LT activity via TLR9-mediated TNF-α production.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-014-0300-9) contains supplementary material, which is available to authorized users.

Targeting high mobility group box protein 1 ameliorates testicular inflammation in experimental autoimmune orchitis

STUDY QUESTION

Does high mobility group box protein 1 (HMGB1) regulate inflammatory reactions in a rat model of experimental autoimmune orchitis (EAO)?

SUMMARY ANSWER

HMGB1 appears to be involved in regulating inflammatory reactions in testes, as HMGB1 is translocated from testicular cells during the course of EAO and blocking its action by ethyl pyruvate (EP) reduces disease progression and spermatogenic damage.

WHAT IS KNOWN ALREADY

Despite its immune privileged status, the human testis is prone to inflammatory lesions associated with male factor infertility. Accumulating evidence shows that HMGB1 plays an important role in onset and progression of autoimmune diseases.

STUDY DESIGN, SIZE, DURATION

This is a cross sectional and longitudinal study involving Wistar male rats immunized with testicular homogenates to induce EAO 50 (EAO50; n = 10) and 80 (EAO80; n = 10) days after first immunization. Control adjuvant animals received saline instead of testicular homogenate (n = 16). Untreated animals (n = 10) were also studied. An interventional study was performed to block the action of HMGB1 starting 20 days after first immunization in EAO animals and respective controls (n = 17). Rats were treated i.p. with EP and the effect of EP treatment on testicular pathogenesis was evaluated 30 days later. Moreover, human testicular biopsies from infertile men with focal lymphocytic infiltrates (n = 7) and sections with intact spermatogenesis (n = 6) were probed with antibodies against HMGB1.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Testicular RNA and protein extracts from EAO animals, EAO animals treated with EP and relevant controls were used for analysis of cytokine expression by real-time RT-PCR and enzyme-linked immunosorbent assay. HMGB1 was co-localized on rat testicular cross sections with antibodies against testicular macrophages (TM), peritubular cells (PTC) and Sertoli cells (SC). Interaction of HMGB1 and its receptors (RAGE, TLR4) as well signaling pathways after HMGB1 stimulation were studied in isolated TM, PTC and SC by proximity ligation assay and western blot, respectively. Furthermore, HMGB1 immunofluorescence on human testicular biopsies was performed.

MAIN RESULTS AND THE ROLE OF CHANCE

HMGB1 was translocated from the nuclei in EAO testes and testes of infertile men with impaired spermatogenesis and lymphocytic infiltrates. Elevated HMGB1 levels were observed during late phase of EAO. In testicular somatic cells HMGB1 receptors Toll-like receptor 4 (TLR4) and receptor for advanced glycation end products (RAGE) were differentially expressed: HMGB1-TLR4 binding was predominant in TM, while HMGB1-RAGE interaction was prevalent in SC and PTC. In support, HMGB1 triggered extracellular signal regulated kinase (ERK)1/2 and cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) activation in SC and PTC, while TM responded to HMGB1 stimulation with p38 mitogen-activated protein kinase (MAPK) and p65 nuclear factor Kappa B (NF-ĸB) phosphorylation followed by increased tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) mRNA levels. In vivo treatment of EAO animals with EP 20 days after induction of disease revealed beneficial effects, as documented by reduced disease progression and spermatogenic damage, lower macrophage numbers, as well as decreased concentrations of HMGB1 and IL-6 in the testis compared with EAO controls.

LIMITATIONS, REASONS FOR CAUTION

The ability of HMGB1 to bind to a wide range of receptors makes it difficult to prevent its action by blockade of a specific receptor; therefore we applied EP, a drug preventing HMGB1 release from cells. Due to its mode of action EP decreases also the secretion of some other pro-inflammatory cytokines. Using isolated primary cells imposes limitations for cell transfection studies. As a compromise between purity and yield primary cells need to be isolated from animals of different age, which has to be considered when comparing their responses.

WIDER IMPLICATIONS OF THE FINDINGS

HMGB1 could be a promising target in attenuating testicular damage caused by inflammatory reactions.

Extracellular mycobacterial DnaK polarizes macrophages to the M2-like phenotype

Macrophages are myeloid cells that play an essential role in inflammation and host defense, regulating immune responses and maintaining tissue homeostasis. Depending on the microenvironment, macrophages can polarize to two distinct phenotypes. The M1 phenotype is activated by IFN-γ and bacterial products, and displays an inflammatory profile, while M2 macrophages are activated by IL-4 and tend to be anti-inflammatory or immunosupressive. It was observed that DnaK from Mycobacterium tuberculosis has immunosuppressive properties, inducing a tolerogenic phenotype in dendritic cells and MDSCs, contributing to graft acceptance and tumor growth. However, its role in macrophage polarization remains to be elucidated. We asked whether DnaK was able to modulate macrophage phenotype. Murine macrophages, derived from bone marrow, or from the peritoneum, were incubated with DnaK and their phenotype compared to M1 or M2 polarized macrophages. Treatment with DnaK leads macrophages to present higher arginase I activity, IL-10 production and FIZZ1 and Ym1 expression. Furthermore, DnaK increased surface levels of CD206. Importantly, DnaK-treated macrophages were able to promote tumor growth in an allogeneic melanoma model. Our results suggest that DnaK polarizes macrophages to the M2-like phenotype and could constitute a virulence factor and is an important immunomodulator of macrophage responses.

Cystatin C protects neuronal cells against mutant copper-zinc superoxide dismutase-mediated toxicity

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the selective and progressive loss of motor neurons. Cystatin C (CysC), an endogenous cysteine protease inhibitor, is a major protein component of Bunina bodies observed in the spinal motor neurons of sporadic ALS and is decreased in the cerebrospinal fluid of ALS patients. Despite prominent deposition of CysC in ALS, the roles of CysC in the central nervous system remain unknown. Here, we identified the neuroprotective activity of CysC against ALS-linked mutant Cu/Zn-superoxide dismutase (SOD1)-mediated toxicity. We found that exogenously added CysC protected neuronal cells including primary cultured motor neurons. Moreover, the neuroprotective property of CysC was dependent on the coordinated activation of two distinct pathways: autophagy induction through AMPK-mTOR pathway and inhibition of cathepsin B. Furthermore, exogenously added CysC was transduced into the cells and aggregated in the cytosol under oxidative stress conditions, implying a relationship between the neuroprotective activity of CysC and Bunina body formation. These data suggest CysC is an endogenous neuroprotective agent and targeting CysC in motor neurons may provide a novel therapeutic strategy for ALS.

Combinatorial contextualization of peptidic epitopes for enhanced cellular immunity

Invocation of cellular immunity by epitopic peptides remains largely dependent on empirically developed protocols, such as interfusion of aluminum salts or emulsification using terpenoids and surfactants. To explore novel vaccine formulation, epitopic peptide motifs were co-programmed with structural motifs to produce artificial antigens using our “motif-programming” approach. As a proof of concept, we used an ovalbumin (OVA) system and prepared an artificial protein library by combinatorially polymerizing MHC class I and II sequences from OVA along with a sequence that tends to form secondary structures. The purified endotoxin-free proteins were then examined for their ability to activate OVA-specific T-cell hybridoma cells after being processed within dendritic cells. One clone, F37A (containing three MHC I and two MHC II OVA epitopes), possessed a greater ability to evoke cellular immunity than the native OVA or the other artificial antigens. The sensitivity profiles of drugs that interfered with the F37A uptake differed from those of the other artificial proteins and OVA, suggesting that alteration of the cross-presentation pathway is responsible for the enhanced immunogenicity. Moreover, F37A, but not an epitopic peptide, invoked cellular immunity when injected together with monophosphoryl lipid A (MPL), and retarded tumor growth in mice. Thus, an artificially synthesized protein antigen induced cellular immunity in vivo in the absence of incomplete Freund's adjuvant or aluminum salts. The method described here could be potentially used for developing vaccines for such intractable ailments as AIDS, malaria and cancer, ailments in which cellular immunity likely play a crucial role in prevention and treatment.

Broadly neutralizing antibodies and viral inducers decrease rebound from HIV-1 latent reservoirs in humanized mice

Latent reservoirs of HIV-1-infected cells are refractory to antiretroviral therapies (ART) and remain the major barrier to curing HIV-1. Because latently infected cells are long-lived, immunologically invisible, and may undergo homeostatic proliferation, a "shock and kill" approach has been proposed to eradicate this reservoir by combining ART with inducers of viral transcription. However, all attempts to alter the HIV-1 reservoir in vivo have failed to date. Using humanized mice, we show that broadly neutralizing antibodies (bNAbs) can interfere with establishment of a silent reservoir by Fc-FcR-mediated mechanisms. In established infection, bNAbs or bNAbs plus single inducers are ineffective in preventing viral rebound. However, bNAbs plus a combination of inducers that act by independent mechanisms synergize to decrease the reservoir as measured by viral rebound. Thus, combinations of inducers and bNAbs constitute a therapeutic strategy that impacts the establishment and maintenance of the HIV-1 reservoir in humanized mice.

Selection of pancreatic cancer cell-binding landscape phages and their use in development of anticancer nanomedicines

It is hypothesized that the use of targeted drug delivery systems can significantly improve the therapeutic index of small molecule chemotherapies by enhancing accumulation of the drugs at the site of disease. Phage display offers a high-throughput approach for selection of the targeting ligands. We have successfully isolated phage fusion proteins selective and specific for PANC-1 pancreatic cancer cells. Doxorubicin liposomes (Lipodox) modified with tumor-specific phage fusion proteins enhanced doxorubicin uptake specifically in PANC-1 cells as compared with unmodified Lipodox and also compared with normal breast epithelial cells. Phage protein-targeted Lipodox substantially increased the concentration of doxorubicin in the nuclei of PANC-1 cells in spite of P-glycoprotein-mediated drug efflux. The in vitro cytotoxic activity obtained with pancreatic cell-targeted Lipodox was greater than that of unmodified Lipodox. We present a novel and straightforward method for preparing pancreatic tumor-targeted nanomedicines by anchoring pancreatic cancer-specific phage proteins within the liposome bilayer.

Alum and squalene-oil-in-water emulsion enhance the titer and avidity of anti-Aβ antibodies induced by multimeric protein antigen (1-11)E2, preserving the Igg1-skewed isotype distribution

The development of active immunotherapy for Alzheimer's disease (AD) requires the identification of immunogens that can ensure a high titer antibody response toward Aβ, while minimizing the risks of adverse reactions. Multimeric protein (1–11)E2 induces a robust and persistent antibody response to Aβ in mice, when formulated in Freund's adjuvant. The goal of this translational study was to evaluate the immunogenicity of (1–11)E2 formulated in alum (Alhydrogel 2%), or in a squalene oil-in-water emulsion (AddaVax), or without adjuvant. A IgG1-skewed isotype distribution was observed for the anti-Aβ antibodies generated in mice immunized with either the non-adjuvanted or the adjuvanted vaccine, indicating that (1–11)E2 induces a Th2-like response in all tested conditions. Both Alhydrogel 2% and AddaVax enhanced the titer and avidity of the anti-Aβ response elicited by (1–11)E2. We conclude that (1–11)E2 is a promising candidate for anti-Aβ immunization protocols that include alum or squalene-oil-in-water emulsion, or no adjuvant.

Pertussis toxin improves immune responses to a combined pneumococcal antigen and leads to enhanced protection against Streptococcus pneumoniae

Pneumococcal surface protein A (PspA) is a candidate antigen for the composition of protein-based vaccines against Streptococcus pneumoniae. While searching for efficient adjuvants for PspA-based vaccines, our group has described the potential of combining PspA with the whole-cell pertussis vaccine (wP). When given to mice through the nasal route, a formulation composed of PspA from clade 5 (PspA5) and wP (PspA5-wP) induced high levels of antibodies and protection against challenges with different pneumococcal strains. PspA5-wP also induced the secretion of interleukin 17 (IL-17) by splenocytes and the infiltration of leukocytes in the lungs after challenge. Here, we show that protection against a pneumococcal invasive challenge was completely abrogated in μMT(-/-) mice, which are deficient in the maturation of B cells, illustrating the importance of antibodies in the survival elicited by the PspA5-wP vaccine. Moreover, passive immunization showed that IgG purified from the sera of mice immunized with PspA5-wP conferred significant protection to naive mice, whereas the respective F(ab')2 did not. Additionally, in vivo depletion of complement abolished protection against the pneumococcal challenge. The combination of PspA5 with wild-type or mutant Bordetella pertussis strains or with purified components showed that the pertussis toxin (PT)-containing formulations induced the highest levels of antibodies and protection. This suggests that the adjuvant activity of wP in the PspA5 model is mediated at least in part by PT. The sera from mice immunized with such formulations displayed high IgG binding and induction of complement deposition on the pneumococcal surface in vitro, which is consistent with the in vivo results.

Immune response of broiler chickens immunized orally with the recombinant proteins flagellin and the subunit B of cholera toxin associated with Lactobacillus spp

This study investigated the immune response of broiler chickens with oral treatment of a Lactobacillus spp. pool (PL) associated with microencapsulated recombinant proteins flagellin (FliC) and the subunit B of cholera toxin (CTB). Immune responses were evaluated by measuring IgA from intestinal fluid, serum IgY, and immunostaining of CD8(+) T lymphocytes present in the cecum. The evaluations were performed on d 0, 7, 14, 21, and 28 posttreatment. A significant increase (P < 0.05) was observed in IgA levels in all immunized groups, especially 3 wk after immunization. Treatments 2 (recombinant CTB) and 3 (recombinant FliC+CTB) showed the highest concentrations. Similarly, serum concentrations IgY (μg/mL) increased along the experiment, and the means for treatments 2 and 3 showed significant differences (P < 0.05) compared with controls, reaching concentrations of 533 and 540 μg/mL, respectively. The number of CD8(+) T lymphocytes in all treatments greatly differed (P < 0.05) compared with the negative control at 21 d posttreatment. However, only treatment 2 (recombinant CTB), 4 (PL), and 5 (recombinant FliC+ recombinant CTB + PL) remained significantly (P < 0.05) different from the control at 28 d posttreatment. Thus, it is concluded that the microencapsulated recombinant proteins administered orally to broiler chickens are capable of stimulating humoral and cellular immune response, and the combinations of these antigens with Lactobacillus spp. can influence the population of CD8(+) T cells residing in the cecum.

Highly purified mussel adhesive protein to secure biosafety for in vivo applications

BACKGROUND

Unique adhesive and biocompatibility properties of mussel adhesive proteins (MAPs) are known for their great potential in many tissue engineering and biomedical applications. Previously, it was successfully demonstrated that redesigned hybrid type MAP, fp-151, mass-produced in Gram-negative bacterium Escherichia coli, could be utilized as a promising adhesive biomaterial. However, purification of recombinant fp-151 has been unsatisfactory due to its adhesive nature and polarity which make separation of contaminants (especially, lipopolysaccharide, a toxic Gram-negative cell membrane component) very difficult.

RESULTS

In the present work, we devised a high resolution purification approach to secure safety standards of recombinant fp-151 for the successful use in in vivo applications. Undesirable impurities were remarkably eliminated as going through sequential steps including treatment with multivalent ion and chelating agent for cell membrane washing, mechanical cell disruption, non-ionic surfactant treatment for isolated inclusion body washing, acid extraction of washed inclusion body, and ion exchange chromatography purification of acid extracted sample. Through various analyses, such as high performance liquid chromatographic purity assay, limulus amoebocyte lysate endotoxin assay, and in vitro mouse macrophage cell tests on inflammation, viability, cytotoxicity, and apoptosis, we confirmed the biological safety of bacterial-derived purified recombinant fp-151.

CONCLUSIONS

Through this purification design, recombinant fp-151 achieved 99.90% protein purity and 99.91% endotoxin reduction that nearly no inflammation response was observed in in vitro experiments. Thus, the highly purified recombinant MAP would be successfully used as a safety-secured in vivo bioadhesive for tissue engineering and biomedical applications.

Ostertagia ostertagi macrophage migration inhibitory factor is present in all developmental stages and may cross-regulate host functions through interaction with the host receptor

Macrophage migration inhibitory factor (MIF) of Ostertagia ostertagi, an abomasal parasite of cattle, was characterised in the present study. Phylogenetic analysis identified at least three O. ostertagi MIFs (Oos-MIFs), each encoded by a distinct transcript: Oos-MIF-1.1, Oos-MIF-1.2 and Oos-MIF-2. Oos-MIF-2 is only distantly related to Oos-MIF-1s, but has higher sequence similarity with the Caenorhabditis elegans MIF2. Oos-MIF-1.1 and Oos-MIF-1.2 are similar (93%) and thus collectively referred to as Oos-MIF-1 when characterised with immunoassays. Recombinant Oos-MIF-1.1 (rOos-MIF-1.1) is catalytically active as a tautomerase. A mutation (rOos-MIF-1.1P1G) or duplication of Pro1 residue (rOos-MIF-1.1P1+P) resulted in reduced oligomerisation and loss of tautomerase activity. The tautomerase activity of rOos-MIF-1.1 was only partially inhibited by ISO-1 but was abrogated by a rOos-MIF-1.1-specific antibody. Oos-MIF-1 was detected in all developmental stages of O. ostertagi, with higher levels in the adult stage; it was also detected in adult worm excretory/secretory product. Oos-MIF-1 was localised to the hypodermis/muscle, reproductive tract and intestine, but not to the cuticle. rOos-MIF-1.1, but not rOos-MIF-1.1P1G, was able to specifically bind to human CD74, a MIF cell surface receptor, with an affinity comparable with human MIF. Immunostaining indicated that macrophages were able to internalise rOos-MIF-1.1, further supporting receptor-mediated transportation. Herein we also show that rOos-MIF-1.1 inhibited migration of bovine macrophages and restored glucocorticoid-suppressed, lipopolysaccharide-induced TNF-α and IL-8 in human and/or bovine macrophages. Given its dual role in self-regulation and molecular mimicry, this secreted parasite protein warrants investigation as a vaccine candidate against O. ostertagi infections in cattle.

Bacillus subtilis spores as vaccine adjuvants: further insights into the mechanisms of action

Bacillus subtilis spores have received growing attention regarding potential biotechnological applications, including the use as probiotics and in vaccine formulations. B. subtilis spores have also been shown to behave as particulate vaccine adjuvants, promoting the increase of antibody responses after co-administration with antigens either admixed or adsorbed on the spore surface. In this study, we further evaluated the immune modulatory properties of B. subtilis spores using a recombinant HIV gag p24 protein as a model antigen. The adjuvant effects of B. subtilis spores were not affected by the genetic background of the mouse lineage and did not induce significant inflammatory or deleterious effects after parenteral administration. Our results demonstrated that co-administration, but not adsorption to the spore surface, enhanced the immunogenicity of that target antigen after subcutaneous administration to BALB/c and C57BL/6 mice. Spores promoted activation of antigen presenting cells as demonstrated by the upregulation of MHC and CD40 molecules and enhanced secretion of pro-inflammatory cytokines by murine dendritic cells. In addition, in vivo studies indicated a direct role of the innate immunity on the immunomodulatory properties of B. subtilis spores, as demonstrated by the lack of adjuvant effects on MyD88 and TLR2 knockout mouse strains.

Parenteral Adjuvant Effects of an Enterotoxigenic Escherichia coli Natural Heat-Labile Toxin Variant

Native type I heat-labile toxins (LTs) produced by enterotoxigenic Escherichia coli (ETEC) strains exert strong adjuvant effects on both antibody and T cell responses to soluble and particulate antigens following co-administration via mucosal routes. However, inherent enterotoxicity and neurotoxicity (following intra-nasal delivery) had reduced the interest in the use of these toxins as mucosal adjuvants. LTs can also behave as powerful and safe adjuvants following delivery via parenteral routes, particularly for activation of cytotoxic lymphocytes. In the present study, we evaluated the adjuvant effects of a new natural LT polymorphic form (LT2), after delivery via intradermal (i.d.) and subcutaneous (s.c.) routes, with regard to both antibody and T cell responses. A recombinant HIV-1 p24 protein was employed as a model antigen for determination of antigen-specific immune responses while the reference LT (LT1), produced by the ETEC H10407 strain, and a non-toxigenic LT form (LTK63) were employed as previously characterized LT types. LT-treated mice submitted to a four dose-base immunization regimen elicited similar p24-specific serum IgG responses and CD4⁺ T cell activation. Nonetheless, mice immunized with LT1 or LT2 induced higher numbers of antigen-specific CD8⁺ T cells and in vivo cytotoxic responses compared to mice immunized with the non-toxic LT derivative. These effects were correlated with stronger activation of local dendritic cell populations. In addition, mice immunized with LT1 and LT2, but not with LTK63, via s.c. or i.d. routes developed local inflammatory reactions. Altogether, the present results confirmed that the two most prevalent natural polymorphic LT variants (LT1 or LT2) display similar and strong adjuvant effects for subunit vaccines administered via i.d. or s.c. routes.

Crucial roles of Glu60 in human neuroglobin as a guanine nucleotide dissociation inhibitor and neuroprotective agent

Mammalian neuroglobin (Ngb) protects neuronal cells under conditions of oxidative stress. We previously showed that human Ngb acts as a guanine nucleotide dissociation inhibitor (GDI) for the α-subunits of heterotrimeric Gi/o proteins and inhibits reductions in cAMP concentration, leading to protection against cell death. In the present study, we created human E60Q Ngb mutant and clarified that Glu60 of human Ngb is a crucial residue for its GDI and neuroprotective activities. Moreover, we investigated structural and functional properties of several human Ngb mutants and demonstrated that the neuroprotective effect of human Ngb is due to its GDI activity and not due to its scavenging activity against reactive oxygen species.

Soluble expression of human leukemia inhibitory factor with protein disulfide isomerase in Escherichia coli and its simple purification

Human leukemia inhibitory factor (hLIF) is a multifunctional cytokine that is essential for maintaining the pluripotency of embryonic stem cells. hLIF may be also be useful in aiding fertility through its effects on increasing the implantation rate of fertilized eggs. Thus these applications in biomedical research and clinical medicine create a high demand for bioactive hLIF. However, production of active hLIF is problematic since eukaryotic cells demonstrate limited expression and prokaryotic cells produce insoluble protein. Here, we have adopted a hybrid protein disulfide isomerase design to increase the solubility of hLIF in Escherichia coli. Low temperature expression of hLIF fused to the b'a' domain of protein disulfide isomerase (PDIb'a') increased the soluble expression in comparison to controls. A simple purification protocol for bioactive hLIF was established that includes removal of the PDIb'a' domain by cleavage by TEV protease. The resulting hLIF, which contains one extra glycine residue at the N-terminus, was highly pure and demonstrated endotoxin levels below 0.05 EU/μg. The presence of an intramolecular disulfide bond was identified using mass spectroscopy. This purified hLIF effectively maintained the pluripotency of a murine embryonic stem cell line. Thus we have developed an effective method to produce a pure bioactive version of hLIF in E. coli for use in biomedical research.

Soluble antigen traffics rapidly and selectively from the corneal surface to the eye draining lymph node and activates T cells when codelivered with CpG oligonucleotides

The transport of antigen to the secondary lymphoid tissue is a central component in the initiation of the adaptive immune response. The mechanism of antigen delivery to the DLN from the avascular cornea has not been fully explored. Previous studies in the mouse have shown that cell-associated corneal antigen is delivered within 6 h to the eye draining SM DLN via DCs and macrophages. In this study, we used a system in which antigen and the processed p-MHCII complexes derived from the antigen could be tracked in vivo. We report that soluble antigen applied to an abraded cornea in the mouse is transported rapidly (within 30 min) to the SM DLN, where a proportion is taken up by resident DCs and presented as p-MHCII complexes, while the larger part is cleared by 8 h. At a later time, a second wave of antigen transport in migratory DCs enters the DLN and participates in further continued antigen presentation. With the use of an antigen-specific TCR transgenic mouse system, we demonstrate that T cell activation does not occur during the early stages of soluble antigen delivery to LN, even though p-MHCII complexes are generated. Antigen-specific T cell activation occurs in the later, presumed cell-associated phase but requires codelivery of a "danger" signal, such as the TLR ligand CpG. We suggest that the early delivery of soluble antigen is more likely to induce T cell nonresponsiveness (anergy) unless presented in the context of an innate-immune cell activation (danger) signal.

First characterization of a teleost Epstein-Barr virus-induced gene 3 (EBI3) reveals a regulatory effect of EBI3 on the innate immune response of peripheral blood leukocytes

Epstein-Barr virus-induced gene 3 (EBI3) encodes a protein that in mammals is known to be a subunit of interleukin (IL)-27 and IL-35, both which regulate cytokine production and inflammatory response. To date, no studies on fish EBI3 have been documented. In this work, we report the identification of an EBI3 homologue, CsEBI3, from tongue sole (Cynoglossus semilaevis) and analysis of its expression and biological effect. CsEBI3 is composed of 245 amino acid residues and possesses a Fibronectin type 3 (FN3) domain that is preserved in lower and higher vertebrates. Expression of CsEBI3 was detected in a wide range of tissues, in particular those of immune relevant organs, and upregulated in a time-dependent manner by experimental challenge with bacterial and viral pathogens. Bacterial infection of peripheral blood leukocytes (PBL) enhanced CsEBI3 expression and caused extracellular secretion of CsEBI3. Purified recombinant CsEBI3 (rCsEBI3) stimulated the respiratory burst activity of PBL and upregulated the expression of IL-1β, IL-8, Myd88, interferon-induced gene 15, CD28, and chemokines. In contrast, rCsEBI3M, a mutant CsEBI3 that lacks the FN3 domain failed to activate PBL and induced much weaker expression of the immune genes. Treatment of PBL with rCsEBI3, but not with the mutant rCsEBI3M, enhanced cellular resistance against bacterial invasion, whereas antibody blocking of CsEBI3 on PBL significantly reduced cellular resistance against bacterial infection. Taken together, these results indicate for the first time that a teleost EBI3 possesses immunoregulatory property in a manner that is dependent on the conserved FN3 domain, and that CsEBI3 is involved in the innate immune defense of PBL against microbial pathogens.

Fasciola hepatica - the pilot study of in vitro assessing immune response against native and recombinant antigens of the fluke

Fasciola hepatica is a liver fluke that infects 2.4 million of people and causes great economical loss in animal production. To date a 100% effective vaccine has not been developed and the disease is controlled by drug therapy. Great efforts are put into development of effective vaccine against parasite what is difficult since Fasciola spp. (like other helmints) during evolutionary process has developed sophisticated and efficient methods to evade immune response. During preliminary experiments it is convenient to use cell lines which are relatively cheap and allow for reproducible comparison of results between laboratories. We stimulated BOMA (bovine monocyte/macrophage cell line) and BOMAC (bovine macrophage cell line) with native or recombinant antigens of Fasciola hepatica and assessed IFN-γ, IL-4 and TNF-α level upon stimulation. We observed diminished secretion of proinflammatory TNF-α in LPS activated BOMA cells stimulated with Excretory/Secretory products of adult fluke (Fh-ES). We also observed greater changes in gene expression in LPS activated BOMA cells than in non activated BOMA cells upon stimulation using Fh-ES. The results show possibility of using cell lines for in vitro research of bovine immune response against liver fluke, although this model still requires validation and further characterization.

Biomimetic protein nanoparticles facilitate enhanced dendritic cell activation and cross-presentation

Many current cancer vaccine strategies suffer from the inability to mount a CD8 T cell response that is strong enough to overcome the low immunogenicity of tumors. Viruses naturally possess the sizes, geometries, and physical properties for which the immune system has evolved to recognize, and mimicking those properties with nanoparticles can produce robust platforms for vaccine design. Using the nonviral E2 core of pyruvate dehydrogenase, we have engineered a viral-mimicking vaccine platform capable of encapsulating dendritic cell (DC)-activating CpG molecules in an acid-releasable manner and displaying MHC I-restricted SIINFEKL peptide epitopes. Encapsulated CpG activated bone marrow-derived DCs at a 25-fold lower concentration in vitro when delivered with the E2 nanoparticle than with unbound CpG alone. Combining CpG and SIINFEKL within a single multifunctional particle induced ∼3-fold greater SIINFEKL display on MHC I by DCs over unbound peptide. Importantly, combining CpG and SIINFEKL to the E2 nanoparticle for simultaneous temporal and spatial delivery to DCs showed increased and prolonged CD8 T cell activation, relative to free peptide or peptide-bound E2. By codelivering peptide epitopes and CpG activator in a particle of optimal DC-uptake size, we demonstrate the ability of a noninfectious protein nanoparticle to mimic viral properties and facilitate enhanced DC activation and cross-presentation.

Removal of lipopolysaccharide from protein solution using nanostructured porous supports bearing lipid membranes

Polymeric lipid membranes of N-octadecylchitosan, which consists of 70 mol% of 2-(octadecylamino)-2-deoxy-d-glucopyranose, 17 mol% of 2-amino-2-deoxy-d-glucopyranose, and 13 mol% of 2-acetamido-2-deoxy-d-glucopyranose, were covalently immobilized to carboxylated porous supports composed of chitosan and used for the adsorption of pyrogenic lipopolysaccharide. When human serum albumin solution, including 5 mg mL-1 of albumin and 5.6 ng mL-1 of lipopolysaccharide, was passed through a column packed with the resulting porous supports bearing lipid membranes assembled in nanoscale, lipopolysaccharide was removed to as low as a detection limit of 0.020 ng mL-1 with a quantitative recovery of protein. On the other hand, in the case of directly N-octadecylated porous supports having cationic and hydrophobic ligands which are not assembled as lipid membranes, lipopolysaccharide could not be removed to the detection limit and protein recovery was lower than the porous supports bearing lipid membranes. The difference above as well as difference from conventional adsorbents suggested that the selectivity was attributable to an interaction between the cationic lipid membranes of N-octadecylchitosan and lipopolysaccharide as well as protein. The porous supports bearing lipid membranes were stable in 0.5 M NaOH and 0.1 M HCl at ambient temperature. Considering the confirmed excellent selectivity and chemical stability, their practical use as separation media in the pharmaceutical manufacturing can be expected.

The HIV-1 envelope protein gp120 impairs B cell proliferation by inducing TGF-β1 production and FcRL4 expression

The humoral immune response after acute infection with HIV-1 is delayed and ineffective. The HIV-1 envelope protein gp120 binds to and signals through integrin α4β7 on T cells. We found that gp120 also bound to and signaled through α4β7 on naive B cells, which resulted in an abortive proliferative response. In primary B cells, signaling by gp120 through α4β7 resulted in increased expression of the immunosuppressive cytokine TGF-β1 and FcRL4, an inhibitory receptor expressed on B cells. Coculture of B cells with HIV-1-infected autologous CD4(+) T cells also increased the expression of FcRL4 by B cells. Our findings indicated that in addition to mediating chronic activation of the immune system, viral proteins contributed directly to HIV-1-associated B cell dysfunction. Our studies identify a mechanism whereby the virus may subvert the early HIV-1-specific humoral immune response.

Cold-inducible RNA-binding protein (CIRP) triggers inflammatory responses in hemorrhagic shock and sepsis

Excessive production of proinflammatory mediators is observed in patients undergoing hemorrhagic and septic shock. Here, we report the detection of cold-inducible RNA-binding protein (CIRP) in the blood of surgical ICU individuals. In animal models of hemorrhage and sepsis, CIRP is up-regulated in several organs and released into the circulation. Under hypoxic stresses, CIRP in macrophages is translocated from the nucleus to the cytosol and actively released. Recombinant CIRP stimulates TNF-α and HMGB1 release in macrophages as well as induces inflammatory responses and causes tissue injury in animals. Antisera to CIRP attenuate shock-induced inflammation, tissue injury, and lethality. Extracellular CIRP's activity is mediated through the TLR4/MD2 complex. Surface plasmon resonance analysis indicates that CIRP binds to the TLR4/MD2 complex as well as to individual TLR4 and MD2. The human CIRP amino-acid segment 106-125 binds to MD2 with high affinity. Collectively, CIRP is a new proinflammatory mediator of shock.

Immunological study of the outer membrane proteins of Vibrio harveyi: insights that link immunoprotectivity to interference with bacterial infection

Vibrio harveyi is a bacterial pathogen that affects marine vertebrates and invertebrates. In this study, we identified 13 outer membrane proteins (OMPs) from a pathogenic V. harveyi strain and analyzed their immunological properties. In vivo immunogenicity analysis showed that antibodies specific to recombinant proteins of the 13 OMPs were detected in the antiserum of V. harveyi-infected rat. When used as subunit vaccines to immunize Japanese flounder (Paralichthys olivaceus), all OMPs were able to elicit specific serum antibody production in the vaccinated fish; however, only two OMPs (OMP173 and OMP214) induced high levels (>70%) of relative percent survival. Pre-incubation of V. harveyi with the antisera of protective OMPs significantly impaired bacterial infectivity against peripheral blood leukocytes (PBL), whereas the antisera of non-protective OMPs had no apparent effect on infection. OMP173 antibodies could bind whole V. harveyi cells and exhibit bactericidal effect in a complement-dependent manner. Passive immunization showed that fish received OMP173 antiserum before being infected with V. harveyi exhibited significantly reduced mortality rate and lower bacterial loads in liver, spleen, and kidney. Finally, treatment of FG cells with OMP173 prior to V. harveyi infection protected the cells from bacterial invasion to a significant extent. Take together, these results indicate that two of the examined OMPs induce protective immunity through production of specific antibodies that block bacterial invasion, and that one OMP is likely to be involved in host cell interaction during the infection process. Thus, the immunoprotectivity of the OMPs is probably associated with functional participations of the OMPs in bacterial infection.

Edwardsiella tarda Ivy, a lysozyme inhibitor that blocks the lytic effect of lysozyme and facilitates host infection in a manner that is dependent on the conserved cysteine residue

Edwardsiella tarda is a Gram-negative bacterial pathogen with a broad host range that includes fish and humans. In this study, we examined the activity and function of the lysozyme inhibitor Ivy (named IvyEt) identified in the pathogenic E. tarda strain TX01. IvyEt possesses the Ivy signature motif CKPHDC in the form of (82)CQPHNC(87) and contains several highly conserved residues, including a tryptophan (W55). For the purpose of virulence analysis, an isogenic TX01 mutant, TXivy, was created. TXivy bears an in-frame deletion of the ivyEt gene. A live infection study in a turbot (Scophthalmus maximus) model showed that, compared to TX01, TXivy exhibited attenuated overall virulence, reduced tissue dissemination and colonization capacity, an impaired ability to replicate in host macrophages, and decreased resistance against the bactericidal effect of host serum. To facilitate functional analysis, recombinant IvyEt (rIvy) and three mutant proteins, i.e., rIvyW55A, rIvyC82S, and rIvyH85D, which bear Ala, Ser, and Asp substitutions at W55, C82, and H85, respectively, were prepared. In vitro studies showed that rIvy, rIvyW55A, and rIvyH85D were able to block the lytic effect of lysozyme on a Gram-positive bacterium, whereas rIvyC82S could not do so. Likewise, rIvy, but not rIvyC82S, inhibited the serum-facilitated killing effect of lysozyme on E. tarda. In vivo analysis showed that rIvy, but not rIvyC82S, restored the lost pathogenicity of TXivy and enhanced the infectivity of TX01. Together these results indicate that IvyEt is a lysozyme inhibitor and a virulence factor that depends on the conserved C82 for biological activity.

Toxicity and efficacy evaluation of multiple targeted polymalic acid conjugates for triple-negative breast cancer treatment

Engineered nanoparticles are widely used for delivery of drugs but frequently lack proof of safety for cancer patient's treatment. All-in-one covalent nanodrugs of the third generation have been synthesized based on a poly(β-L-malic acid) (PMLA) platform, targeting human triple-negative breast cancer (TNBC). They significantly inhibited tumor growth in nude mice by blocking synthesis of epidermal growth factor receptor, and α4 and β1 chains of laminin-411, the tumor vascular wall protein and angiogenesis marker. PMLA and nanodrug biocompatibility and toxicity at low and high dosages were evaluated in vitro and in vivo. The dual-action nanodrug and single-action precursor nanoconjugates were assessed under in vitro conditions and in vivo with multiple treatment regimens (6 and 12 treatments). The monitoring of TNBC treatment in vivo with different drugs included blood hematologic and immunologic analysis after multiple intravenous administrations. The present study demonstrates that the dual-action nanoconjugate is highly effective in preclinical TNBC treatment without side effects, supported by hematologic and immunologic assays data. PMLA-based nanodrugs of the Polycefin™ family passed multiple toxicity and efficacy tests in vitro and in vivo on preclinical level and may prove to be optimized and efficacious for the treatment of cancer patients in the future.

The major fimbrial subunit protein of Edwardsiella tarda: vaccine potential, adjuvant effect, and involvement in host infection

Edwardsiella tarda is a Gram-negative bacterium that is reckoned one of the most severe fish pathogens. In this study, we analyzed the biological properties of the E. tarda major fimbrial subunit protein, FimA. We found that mutation of fimA resulted in defective biofilm growth, attenuated infectivity against host cells, and impaired ability to disseminate into and colonize host tissues following experimental infection. When used as a subunit vaccine, recombinant FimA (rFimA) elicited a high level of protection in turbot (Scophthalmus maximus) against lethal E. tarda challenge. Immunological analysis showed that rFimA vaccination induced production of specific serum antibodies that bound to live E. tarda via interaction with the FimA on bacterial cells, and that antibody-E. tarda interaction blocked bacterial infection. Furthermore, passive immunization of turbot with anti-rFimA serum before E. tarda infection reduced bacterial loads in fish tissues to significant extents. To examine the adjuvant potential of FimA, turbot were vaccinated with rVhhP2, a protective Vibrio harveyi antigen, in the presence or absence of rFimA. Subsequent analysis showed that the presence of rFimA significantly augmented the protectivity of rVhhP2. ELISA and quantitative real time RT-PCR showed that rFimA significantly increased rVhhP2-specific serum antibody production and enhanced the expression of immune relevant genes. Taken together, these results indicate that FimA is a virulence-associated protein that possesses vaccine as well as adjuvant potentials, and that the immunoprotectivity of FimA is most likely due to its ability to induce specific immune response that inhibits E. tarda infection.

Development of an unbiased antigen-mining approach to identify novel vaccine antigens and diagnostic reagents for bovine tuberculosis

Previous experiments for the identification of novel diagnostic or vaccine candidates for bovine tuberculosis have followed a targeted approach, wherein specific groups of proteins suspected to contain likely candidates are prioritized for immunological assessment (for example, with in silico approaches). However, a disadvantage of this approach is that the sets of proteins analyzed are restricted by the initial selection criteria. In this paper, we describe a series of experiments to evaluate a nonbiased approach to antigen mining by utilizing a Gateway clone set for Mycobacterium tuberculosis, which constitutes a library of clones expressing 3,294 M. tuberculosis proteins. Although whole-blood culture experiments using Mycobacterium bovis-infected animals and M. bovis BCG-vaccinated controls did not reveal proteins capable of differential diagnosis, several novel immunogenic proteins were identified and prioritized for efficacy studies in a murine vaccination/challenge model. These results demonstrate that Rv3329-immunized mice had lower bacterial cell counts in their spleens following challenge with M. bovis. In conclusion, we demonstrate that this nonbiased approach to antigen mining is a useful tool for identifying and prioritizing novel proteins for further assessment as vaccine antigens.