Removal of endotoxin from recombinant protein preparations

Inter-epitope spacer variation within polytopic L2-based human papillomavirus antigens affects immunogenicity

The human papillomavirus minor capsid protein L2 is being extensively explored in pre-clinical studies as an attractive vaccine antigen capable of inducing broad-spectrum prophylactic antibody responses. Recently, we have developed two HPV vaccine antigens - PANHPVAX and CUT-PANHPVAX- both based on heptameric nanoparticle antigens displaying polytopes of the L2 major cross-neutralizing epitopes of eight mucosal and twelve cutaneous HPV types, respectively. Prompted by the variable neutralizing antibody responses against some of the HPV types targeted by the antigens observed in previous studies, here we investigated the influence on immunogenicity of six distinct glycine-proline spacers inserted upstream to a specific L2 epitope. We show that spacer variants differentially influence antigen immunogenicity in a mouse model, with the antigen constructs M8merV6 and C12merV6 displaying a superior ability in the induction of neutralizing antibodies as determined by pseudovirus-based neutralization assays (PBNAs). L2-peptide enzyme-linked immunosorbent assay (ELISA) assessments determined the total anti-L2 antibody level for each antigen variant, showing for the majority of sera a correlation with their repective neutralizing antibody level. Surface Plasmon Resonance revealed that L2 epitope-specific, neutralizing monoclonal antibodies (mAbs) display distinct avidities to different antigen spacer variants. Furthermore, mAb affinity toward individual spacer variants was well correlated with their neutralizing antibody induction capacity, indicating that the mAb affinity assay predicts L2-based antigen immunogenicity. These observations provide insights on the development and optimization of L2-based HPV vaccines.

Efficient expression and purification of tag-free recombinant human procalcitonin (hPCT) with precise sequence in E.coli

We present an efficient method for expression and purification of recombinant human procalcitonin (hPCT) in E. coli T7 express LysY/Iq cells, ensuring precise N- and C-terminal amino acid sequences. Our method involves fusing codon-optimized cDNA with two distinct tag sequences: eXact tag and chitin binding domain (CBD) tag. To purify the protein, we employ a two-step affinity chromatography process. Firstly, we utilize the N-terminal Profinity eXact tag and purify the protein through Profinity eXact-affinity column chromatography using a resin on which a mutant subtilisin protease was immobilized. The eXact tag was removed by adding NaF to activate the enzyme. Subsequently, the digested sample containing C-terminal CBD tag is directly loaded for the second step of chitin affinity chromatography. Elution is achieved through dithiothreitol (DTT)-catalyzed self-cleavage of the intein sequence from the fusion protein. As a result, the target protein is selectively recovered in the flow-through, completely tag-free, with a purity exceeding 95%. To ensure high purity and eliminate potential contaminants, we effectively remove E. coli host DNA and endotoxins through a combination of streptomycin sulfate, Triton X-114, and ammonium sulfate treatment. The exceptional level of purity obtained eliminates the need for further purification steps in most applications. This highly purified hPCT can be used as a calibrator in procalcitonin or calcitonin immunoassays. Notably, our approach effectively manages small peptides that are prone to degradation by E. coli host proteases, offering a robust solution for various research and application requirements.

Molecular cloning, expression, and functional analysis of a putative lectin from the pearl oyster (Pinctada fucata, Gould 1850)

Marine lectins are a group of proteins that possess specific carbohydrate recognition and binding domains. They exhibit various activities, including antimicrobial, antitumor, antiviral, and immunomodulatory effects. In this study, a novel galectin-binding lectin gene named PFL-96 (GenBank: OQ561753.1) was cloned from Pinctada fucata. The PFL-96 gene has an open reading frame of 324 base pairs (bp) and encodes a protein comprising 107 amino acids. The protein has a molecular weight of 11.95 kDa and an isoelectric point of 9.27. It contains an N-terminal signal peptide and a galactose-binding lectin domain. The sequence identity to lectin proteins from fish, echinoderms, coelenterates, and shellfish ranges from 31.90 to 40.00 %. In the phylogenetic analysis, it was found that the PFL-96 protein is closely related to the lectin from Pteria penguin. The PFL-96 recombinant protein exhibited coagulation activity on 2 % rabbit red blood cells at a concentration of ≥8 μg/mL. Additionally, it showed significant hemolytic activity at a concentration of ≥32 μg/mL. The PFL-96 recombinant protein exhibited significant antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Candida albicans, and Vibrio alginolyticus, with minimum inhibitory concentrations (MIC) of 4, 8, 16, and 16 μg/mL, respectively. The minimum bactericidal concentrations (MBC) were determined to be 8, 16, 32, and 32 μg/mL, respectively. Furthermore, the PFL-96 recombinant protein exhibited inhibitory effects on the proliferation of Hela tumor cells, HepG2 tumor cells, and C666-1 tumor cells, with IC50 values of 7.962, 8.007, and 9.502 μg/mL, respectively. These findings suggest that the recombinant protein PFL-96 exhibits significant bioactivity in vitro, contributing to a better understanding of the active compounds found in P. fucata. The present study establishes a fundamental basis for further investigation into the mechanism of action and structural optimization of the recombinant protein PFL-96. The aim is to develop potential candidates for antibacterial and anti-tumor agents.

An arabinogalactan extracted with alkali from Portulaca oleracea L. used as an immunopotentiator and a vaccine carrier in its conjugate to BSA

A neutral polysaccharide (POPAN) from Portulaca oleracea L. was isolated with alkali and purified to obtain. HPLC analysis suggested POPAN (40.9 kDa) was mainly composed of Ara and Gal with traces of Glc and Man. GC-MS and 1D/2D NMR analysis confirmed POPAN was an arabinogalactan possessing a backbone mainly composing of (1 → 3)-α-l-Araf-linked arabinan and (1 → 4)-β-d-Galp-linked galactan, which was different from structure characterization of typical arabinogalactan reported previously. Importantly, we conjugated POPAN to BSA (POPAN-BSA), and detected the potential and mechanism of POPAN as an adjuvant in POPAN-BSA. The results indicated, in contrast to BSA, POPAN-BSA induced the robust and persistent humoral response in addition to the cellular response with Th2-biased immunity response in mice. Further investigations of mechanism revealed effects of POPAN-BSA were a result of POPAN as the adjuvant to: 1) significantly activate DCs in vitro or in vivo including the upgraded expressions of costimulators, MHCs and cytokines; 2) greatly facilitated the capture of BSA. Overall, present studies demonstrated POPAN can be a potential adjuvant as an immunopotentiator and an antigen delivery vehicle in its conjugate to recombinant protein vaccines.

The Promising Potential of Reverse Vaccinology-Based Next-Generation Vaccine Development over Conventional Vaccines against Antibiotic-Resistant Bacteria

The clinical use of antibiotics has led to the emergence of multidrug-resistant (MDR) bacteria, leading to the current antibiotic resistance crisis. To address this issue, next-generation vaccines are being developed to prevent antimicrobial resistance caused by MDR bacteria. Traditional vaccine platforms, such as inactivated vaccines (IVs) and live attenuated vaccines (LAVs), were effective in preventing bacterial infections. However, they have shown reduced efficacy against emerging antibiotic-resistant bacteria, including MDR M. tuberculosis. Additionally, the large-scale production of LAVs and IVs requires the growth of live pathogenic microorganisms. A more promising approach for the accelerated development of vaccines against antibiotic-resistant bacteria involves the use of in silico immunoinformatics techniques and reverse vaccinology. The bioinformatics approach can identify highly conserved antigenic targets capable of providing broader protection against emerging drug-resistant bacteria. Multi-epitope vaccines, such as recombinant protein-, DNA-, or mRNA-based vaccines, which incorporate several antigenic targets, offer the potential for accelerated development timelines. This review evaluates the potential of next-generation vaccine development based on the reverse vaccinology approach and highlights the development of safe and immunogenic vaccines through relevant examples from successful preclinical and clinical studies.

Mycobacterium avium subsp. paratuberculosis antigens induce cellular immune responses in cattle without causing reactivity to tuberculin in the tuberculosis skin test

Mycobacterium avium subspecies paratuberculosis (MAP) causes chronic progressive granulomatous enteritis leading to diarrhea, weight-loss, and eventual death in ruminants. Commercially available vaccine provides only partial protection against MAP infection and can interfere with the use of current diagnostic tests for bovine tuberculosis in cattle. Here, we characterized immune responses in calves to vaccines containing four truncated MAP antigens as a fusion (Ag85A^202-347-SOD^1-72-Ag85B^173-330-74F^{1-148+669-786}), either displayed on protein particles, or expressed as a soluble recombinant MAP (rMAP) fusion protein as well as to commercially available Silirum^® vaccine. The rMAP fusion protein elicited the strongest antigen-specific antibody responses to both PPDA and recombinant antigen and strong and long-lasting T-cell immune responses to these antigens, as indicated by increased production of IFN-γ and IL-17A in antigen-stimulated whole blood cultures. The MAP fusion protein particle vaccine induced minimal antibody responses and weak IFN-γ responses but stimulated IL-17A responses to recombinant antigen. The immune response profile of Silirum^® vaccine was characterized by weak antibodies and strong IFN-γ and IL-17A responses to PPDA. Transcription analysis on antigen-stimulated leukocytes from cattle vaccinated with rMAP fusion protein showed differential expression of several immune response genes and genes involved in costimulatory signaling, TLR4, TLR2, PTX3, PTGS2, PD-L1, IL1B, IL2, IL6, IL12B, IL17A, IL22, IFNG, CD40, and CD86. Moreover, the expression of several genes of immune pathways correlated with cellular immune responses in the rMAP fusion protein vaccinated group. These genes have key roles in pathways of mycobacterial immunity, including autophagy, manipulation of macrophage-mediated killing, Th17- and regulatory T cells- (Treg) mediated responses. Calves vaccinated with either the rMAP fusion protein or MAP fusion protein particle vaccine did not induce reactivity to PPDA and PPDB in a comparative cervical skin test, whereas Silirum^® induced reactivity to these tuberculins in most of the vaccinated animals. Overall, our results suggest that a combination of recombinant MAP antigens in the form of a soluble fusion protein vaccine are capable of inducing strong antigen-specific humoral and a balanced Th1/Th17-cell immune response. These findings, together with the absence of reactivity to tuberculin, suggest this subunit vaccine could provide protective immunity against intracellular MAP infection in cattle without compromising the use of current bovine tuberculosis surveillance test.

Accessing the In Vivo Efficiency of Clinically Isolated Phages against Uropathogenic and Invasive Biofilm-Forming Escherichia coli Strains for Phage Therapy

Escherichia coli is one of the most common members of the intestinal microbiota. Many of its strains are associated with various inflammatory infections, including urinary or gut infections, especially when displaying antibiotic resistance or in patients with suppressed immune systems. According to recent reports, the biofilm-forming potential of E. coli is a crucial factor for its increased resistance against antibiotics. To overcome the limitations of using antibiotics against resistant E. coli strains, the world is turning once more towards bacteriophage therapy, which is becoming a promising candidate amongst the current personalized approaches to target different bacterial infections. Although matured and persistent biofilms pose a serious challenge to phage therapy, they can still become an effective alternative to antibiotic treatment. Here, we assess the efficiency of clinically isolated phages in phage therapy against representative clinical uropathogenic and invasive biofilm-forming E. coli strains. Our results demonstrate that irrespective of host specificity, bacteriophages producing clear plaques with a high burst size, and exhibiting depolymerizing activity, are good candidates against biofilm-producing E. coli pathogens as verified from our in vitro and in vivo experiments using Galleria mellonella where survival was significantly increased for phage-therapy-treated larvae.

Quantitative assessment of LPS-HBsAg interaction by introducing a novel application of immunoaffinity chromatography

Lipopolysaccharide (LPS), as a stubborn contamination, should be monitored and kept in an acceptable level during the pharmaceutical production process. Recombinant hepatitis B surface antigen (r-HBsAg) is one of the recombinant biological products, which is probable to suffer from extrinsic endotoxin due to its long and complex production process. This research aims to assess the potential interaction between LPS and r-HBsAg by recruiting immunoaffinity chromatography (IAC) as a novel tool to quantify the interaction. Molecular modeling was performed on the HBsAg molecule to theoretically predict its potential binding and interaction sites. Then dynamic light scattering (DLS) analysis was implemented on HBsAg, LPS, and mixtures of them to reveal the interaction. The virus-like particle (VLP) structure of HBsAg and the ribbon-like structure of LPS were visualized by transmission electron microscopy (TEM). Finally, the interaction was quantified by applying various LPS/HBsAg ratios ranging from 1.67 to 120 EU/dose in the IAC. Consequently, the LPS/HBsAg ratios in the eluate were measured from 1.67 to a maximum of 92.5 EU/dose. The results indicated that 77 to 100% of total LPS interacted with HBsAg by an inverse relationship to the incubated LPS concentration. The findings implied that the introduced procedure is remarkably practical in the quantification of LPS interaction with a target recombinant protein.

A broadly protective vaccine against cutaneous human papillomaviruses

Skin colonization by human papillomavirus (HPV) is typically related to inconspicuous cutaneous infections without major disease or complications in immunocompetent individuals. However, in immunosuppressed patients, especially organ transplanted recipients, cutaneous HPV infections may cause massive, highly spreading and recurrent skin lesions upon synergism with UV-exposure. Current HPV prophylactic vaccines are not effective against cutaneous HPV types (cHPV). By applying a modular polytope-based approach, in this work, we explored different vaccine candidates based on selected, tandemly arranged cHPV-L2 epitopes fused to thioredoxin (Trx) as a scaffold protein. Upon conversion to heptameric nanoparticles with the use of a genetically fused oligomerization domain, our candidate Trx-L2 vaccines induce broadly neutralizing immune responses against 19 cHPV in guinea pigs. Similar findings were obtained in mice, where protection against virus challenge was also achieved via passive transfer of immune sera. Remarkably, immunization with the candidate cHPV vaccines also induced immune responses against several mucosal low- and high-risk HPV types, including HPV16 and 18. Based on cumulative immunogenicity data but also on ease and yield of production, we identified a lead vaccine candidate bearing 12 different cHPV-L2 epitopes that holds great promise as a scalable and GMP production-compatible lead molecule for the prevention of post-transplantation skin lesions caused by cHPV infection.

Immune response induced in mice by a hybrid rPotD-PdT pneumococcal protein

Streptococcus pneumoniae is a human pathogen that colonizes the naso and/or oropharynx and can cause otitis, pneumonia, bacteremia and meningitis. To broaden the protection against pneumococcus, several pneumococcal proteins have been investigated as vaccine candidates. In this study we analyzed the immunological response induced by mouse subcutaneous immunization with a fusion of the Polyamine transport protein D (PotD) and a pneumolysin derivative (PdT), resulting in a hybrid rPotD-PdT protein. Immunization of mice with rPotD-PdT induced increased production of nitric oxide, indicating a higher innate immune response. In agreement, immunization of mice with the hybrid protein was more immunogenic than the individual proteins or their combination, eliciting higher antibody levels. The anti-rPotD-PdT IgG displayed increased binding onto the pneumococcal surface. Furthermore, the anti-rPotD-PdT antisera promoted superior opsonophagocytosis as compared with the other tested formulations. However, despite that the encouraging results in vitro, immunization with the hybrid was not sufficient to induce protection against sepsis with a highly virulent pneumococcal strain. taken together, the results suggest that hybrid proteins are an interesting strategy, able to promote improved immune responses, but the inclusion of other antigens may be necessary to promote protection against invasive infections caused by this bacterium.

Heat Shock Protein 70 Is a Damage-Associated Molecular Pattern That by Binding to Lipopolysaccharide and β-1,3-Glucan-Binding Protein Activates the Prophenoloxidase System in Shrimp

Recent studies have initiated a paradigm shift in understanding heat shock protein 70 (HSP70) functions in the shrimp immune system. However, the mechanism by which Litopenaeus vannamei (Lv)HSP70 modulates the innate immune response remains unclear. This study shows that LvHSP70 binds to the pattern recognition receptor LPS and β-1,3-glucan-binding protein (LvLGBP), and subsequently leads to the activation of the prophenoloxidase system. Injection of shrimp with rLvHSP70 significantly (p < 0.05) upregulated the gene and protein expression of the key pattern recognition receptor LvLGBP. A coimmunoprecipitation and ELISA-based binding assay strongly confirmed the binding of LvHSP70 to LvLGBP at polysaccharide recognition motifs (PLS motifs) with a Kd of 4.44 μM and its competitive binding with LPS (IC50) is 8.036 μM. Conversely, LPS efficiently competed with LvHSP70 for binding to LvLGBP in a concentration-dependent manner with an IC50 of 7.662 μM, indicating that both are ligands of LvLGBP and likely bind at the same site. Binding of LvHSP70 to LvLGBP highly activated phenoloxidase activity in shrimp hemocyte lysate supernatants. Gene silencing of LvLGBP impaired the activation of phenoloxidase activity in shrimp by rLvHSP70, indicating that LvHSP70-LvLGBP interaction was essential for stimulating the immune cascade. Taken together, these results demonstrated that LvHSP70 is a ligand of LvLGBP similar to LPS and acts as a damage-associated molecular pattern to modulate the shrimp immune system via the prophenoloxidase system, eventually leading to the production of melanin and toxic reactive intermediates against invading pathogens.

Diagnostic Value of IgA Antibody Measurement in Tick-Borne Spotted Fever (Astrakhan Rickettsial Fever)

Tick-borne spotted fevers caused by Rickettsia occur worldwide. The symptoms of this bacterial infection are similar to those of viral infection, and thus, diagnostic accuracy has special clinical importance. One of the commonly used methods for the diagnosis of tick-borne spotted fever is enzyme-linked immunosorbent assay (ELISA), which is based on estimation of the presence of specific IgM antibodies in blood. However, IgA analysis has not been used for the diagnosis of rickettsial diseases thus far. We investigated the diagnostic value of IgA antibody determination using patient sera collected in the Astrakhan region of Russia, where an isolated site of Astrakhan rickettsial fever (ARF) caused by Rickettsia conorii subsp. caspia is located. Our investigation was performed on serum samples collected from 185 patients diagnosed with Astrakhan rickettsial fever from May to October 2019. Western blot analysis revealed that specific IgA antibodies, as well as IgM antibodies, from patient sera bind to high-molecular-weight pathogen proteins with similar masses. The obtained data show that the determination of IgM alone allows for serological confirmation of diagnosis in only 46.5% of cases but that the determination of both IgM and IgA increases this rate to 66.5%. Taken together, the findings show an important diagnostic value of IgA evaluation for tick-borne spotted fever rickettsiosis. IMPORTANCE Tick-borne spotted fevers caused by Rickettsia occur worldwide. The symptoms of this bacterial infection are similar to the symptoms of viral infection, and thus, diagnostic accuracy has special clinical importance. The most serious spotted fever group rickettsiosis is Rocky Mountain fever in the United States, which is caused by Rickettsia rickettsii, and disease complications can lead to hemiparesis, blindness, or amputation. Rickettsia conorii subsp. caspia causes a rickettsial spotted fever named Astrakhan rickettsial fever (ARF). One of the commonly used methods for the diagnosis of tick-borne spotted fevers is ELISA, which is based on estimation of the presence of specific IgM antibodies in blood, though IgA has not been used for the diagnosis of rickettsial diseases thus far. In this study, we showed that both IgA and IgM should be analyzed in the blood serum samples of patients to significantly enhance the accuracy of diagnostics of tick-borne spotted fever rickettsiosis.

Alboserpin, the Main Salivary Anticoagulant from the Disease Vector Aedes albopictus, Displays Anti-FXa-PAR Signaling In Vitro and In Vivo

Blood-feeding arthropods secrete potent salivary molecules, which include platelet aggregation inhibitors, vasodilators, and anticoagulants. Among these molecules, Alboserpin, the major salivary anticoagulant from the mosquito vector Aedes albopictus, is a specific inhibitor of the human coagulation factor Xa (FXa). In this study, we investigated the anti-inflammatory properties of Alboserpin, in vitro and in vivo. In vitro, Alboserpin inhibited FXa-induced protease-activated receptor (PAR)-1, PAR-2, PAR-3, VCAM, ICAM, and NF-κB gene expression in primary dermal microvascular endothelial cells. Alboserpin also prevented FXa-stimulated ERK1/2 gene expression and subsequent inflammatory cytokine release (MCP-1, TNF-α, IL-6, IL-8, IL-1β, IL-18). In vivo, Alboserpin reduced paw edema induced by FXa and subsequent release of inflammatory cytokines (CCL2, MCP-1, IL-1α, IL-6, IL-1β). Alboserpin also reduced FXa-induced endothelial permeability in vitro and in vivo. These findings show that Alboserpin is a potent anti-inflammatory molecule, in vivo and in vitro, and may play a significant role in blood feeding.

Applying Modified VP53A Recombinant Protein as an Anti-White Spot Syndrome Virus Biological Agent in Litopenaeus vannamei Farming

Shrimp farming is an important economic activity. However, due to the spread of pathogens, shrimp aquaculture is becoming increasingly difficult. Many studies have confirmed that white spot syndrome virus (WSSV) recombinant proteins can inhibit viral infection. Among them, VP53 recombinant protein has been found to reduce mortality upon WSSV challenge. This study was conducted in Kaohsiung, Taiwan and reports the first field feeding trial to demonstrate that WSSV recombinant proteins can improve shrimp survival rates at a farming scale. Prior to the feeding trial, the shrimp were confirmed to be slightly infected with WSSV, Vibrio parahaemolyticus strains causing acute hepatopancreatic necrosis disease (AHPND), non-AHPND V. parahaemolyticus strains, and Enterocytozoon hepatopenaei (EHP), which are common pathogens that shrimp farmers often face. The shrimp were then divided into two groups: a control group (C group) fed with a commercial diet and a protein group (P group) fed with the same commercial feed with VP53 recombinant protein. Our findings indicated that the survival rate and expression of immune genes of the P group were higher than those of the C group. The intestinal microbiota of the two groups were also analysed. Collectively, our results confirmed that the recombinant WSSV envelope protein derivative can be used as an effective anti-virus biological agent in shrimp farms.

Immunization with CSP and a RIG-I Agonist is Effective in Inducing a Functional and Protective Humoral Response Against Plasmodium

Malaria is a major public health concern, as a highly effective human vaccine remains elusive. The efficacy of a subunit vaccine targeting the most abundant protein of the sporozoite surface, the circumsporozoite protein (CSP) has been hindered by difficulties in generating an effective humoral response in both quantity and quality. Using the rodent Plasmodium yoelii model we report here that immunization with CSP adjuvanted with 5’ppp-dsRNA, a RIG-I agonist, confers early and long-lasting sterile protection in mice against stringent sporozoite and mosquito bite challenges. The immunization induced high levels of antibodies, which were functional in targeting and killing the sporozoites and were sustained over time through the accumulation of long-lived plasma cells in the bone marrow. Moreover, 5’ppp-dsRNA-adjuvanted immunization with the CSP of P. falciparum was also significantly protective against challenges using a transgenic PfCSP-expressing P. yoelii parasite. Conversely, using the TLR3 agonist poly(A:U) as adjuvant resulted in a formulation that despite inducing high antibody levels was unable to generate equally functional antibodies and was, consequently, less protective. In conclusion, we demonstrate that using 5’ppp-dsRNA as an adjuvant to vaccines targeting CSP induces effective anti-Plasmodium humoral immunity.

Rapid, site-specific labeling of "off-the-shelf" and native serum autoantibodies with T cell-redirecting domains

Extensive antibody engineering and cloning is typically required to generate new bispecific antibodies. Made-to-order genes, advanced expression systems, and high-efficiency cloning can simplify and accelerate this process, but it still can take months before a functional product is realized. We developed a simple method to site-specifically and covalently attach a T cell-redirecting domain to any off-the-shelf, human immunoglobulin G (IgG) or native IgG isolated from serum. No antibody engineering, cloning, or knowledge of the antibody sequence is required. Bispecific antibodies are generated in just hours. By labeling antibodies isolated from tumor-bearing mice, including two syngeneic models, we generated T cell-redirecting autoantibodies (TRAAbs) that act as an effective therapeutic. TRAAbs preferentially bind tumor tissue over healthy tissue, indicating a previously unexplored therapeutic window. The use of autoantibodies to direct the tumor targeting of bispecific antibodies represents a new paradigm in personalized medicine that eliminates the need to identify tumor biomarkers.

4-Arylthiosemicarbazide Derivatives as Toxoplasmic Aromatic Amino Acid Hydroxylase Inhibitors and Anti-inflammatory Agents

Approximately one-third of the human population is infected with the intracellular cosmopolitan protozoan Toxoplasma gondii (Tg), and a specific treatment for this parasite is still needed. Additionally, the increasing resistance of Tg to drugs has become a challenge for numerous research centers. The high selectivity of a compound toward the protozoan, along with low cytotoxicity toward the host cells, form the basis for further research, which aims at determining the molecular targets of the active compounds. Thiosemicarbazide derivatives are biologically active organic compounds. Previous studies on the initial preselection of 58 new 4-arylthiosemicarbazide derivatives in terms of their anti-Tg activity and selectivity made it possible to select two promising derivatives for further research. One of the important amino acids involved in the proliferation of Tg and the formation of parasitophorous vacuoles is tyrosine, which is converted by two unique aromatic amino acid hydroxylases to levodopa. Enzymatic studies with two derivatives (R: para-nitro and meta-iodo) and recombinant aromatic amino acid hydroxylase (AAHs) obtained in the E. coli expression system were performed, and the results indicated that toxoplasmic AAHs are a molecular target for 4-arylthiosemicarbazide derivatives. Moreover, the drug affinity responsive target stability assay also confirmed that the selected compounds bind to AAHs. Additionally, the anti-inflammatory activity of these derivatives was tested using THP1-Blue™ NF-κB reporter cells due to the similarity of the thiosemicarbazide scaffold to thiosemicarbazone, both of which are known NF-κB pathway inhibitors.

DnaJ-induced TLR7 mediates an increase in interferons through the TLR4-engaged AKT/NF-κB and JNK signaling pathways in macrophages

Toll-like receptor 7 (TLR7) signaling plays pivotal roles in innate immunity by sensing viral single-stranded RNA thereby triggering inflammatory signaling cascades and eliciting protective antiviral responses. In this study, we found that TLR7 expression is highly induced in response to Pseudomonas aeruginosa (P. aeruginosa) infection in a dose- and time-dependent manner. P. aeruginosa-derived DnaJ, a homolog of HSP40, was identified as a related inducing agent for TLR7 expression, and expression of DnaJ was stimulated when host cells were infected with P. aeruginosa. Interestingly, DnaJ was not involved in mediating an increase in the expression levels of TLR3 and TLR8, other well-known antiviral receptors. The induction of TLR7 in response to DnaJ was mediated by the activation of the AKT (Thr308 and Ser473)/NF-κB and p38/JNK MAPKs signaling pathways, consequently transmitting related signals for the expression of interferons (IFNs). Of note, these antiviral responses were regulated, at least in part, by TLR4, which senses the presence of DnaJ and then promotes downstream activation of the AKT (Ser473)/NF-κB and JNK signaling cascades. Taken together, these results suggest that P. aeruginosa-derived DnaJ is sufficient to promote an increase in TLR7 expression in the TLR4-engaged AKT/NF-κB and JNK signaling pathways, thereby promoting an increased antiviral response through the elevated expression of IFNs.

The small heat shock protein HSPB5 attenuates the severity of lupus nephritis in lupus-prone mice

Lupus nephritis (LN) is a common and serious complication of systemic lupus erythematosus. The current treatments for LN are accompanied with severe immunotoxicity and have limits of effectiveness. Since our in vitro experiments demonstrated that a small heat shock protein (HSP), alpha-B crystallin (HSPB5; CRYAB), selectively modulates myeloid cells towards anti-inflammatory and tolerogenic phenotypes, the aim of this study was to investigate whether HSPB5 can attenuate the severity of LN. MRL/lpr mice were treated intravenously with HSPB5 at 2.5 or 10 μg/dose twice per week after disease onset, from 11 to 21 weeks of age. Disease progression was monitored by weekly measurements of proteinuria, and sera, spleens, and kidneys were collected for assessment at the terminal time point. Treatment with 10 μg HSPB5 substantially reduced endocapillary proliferation and tubular atrophy, which significantly reduced proteinuria and blood urea nitrogen (BUN). Compared to vehicle, 10 μg HSPB5 treatment substantially decreased activation/proliferation of splenocytes, increased IL-10+ macrophages, T and B regulatory cells (Treg, Breg), increased serum IL-10, and lowered expression of IL-6 in kidneys, which correlated with improved kidney function and pathology. This study demonstrated the utility of exogenous human HSPB5 to attenuate severe nephropathy in MRL/lpr mice and provides evidence in favour of a novel therapeutic approach for lupus nephritis.

The Lipopolysaccharide Mutant Re-LPS Is a Useful Tool for Detecting LPS Contamination in Rheumatoid Synovial Cell Cultures

INTRODUCTION

Lipopolysaccharide (LPS) contamination of commercially available proteins has seriously impeded research on citrullinated fibrinogen (cit-Fb) in rheumatoid synovial cells (RSCs).

METHODS

RSCs obtained from 4 rheumatoid arthritis patients who underwent full knee arthroplasty were cultured, stimulated with cit-Fb, and cytokine expression levels were measured. We then evaluated polymyxin-B (PMB), heat inactivation, and rough (R)-type LPS mutants for rapid detection of LPS contamination.

RESULTS

cit-Fb induced expression of CXCL10 and IFNB in RSCs via the toll-like receptor. PMB inhibited cit-Fb-mediated CXCL10 gene expression but not protein expression induced by 20 μg/mL cit-Fb. Heat inactivation did not affect LPS-mediated CXCL10 or IL-6 induction; however, cit-Fb-mediated CXCL10expression was inhibited. Wild-type LPS from Escherichia coli (WT-LPS) strongly induces CXCL10 expression, but induction by Ra-LPS was weak, and induction by Rc- and Re-LPS was minimal. Re-LPS suppression of WT-LPS-mediated CXCL10 induction in RSCs and peripheral blood monocytes (PBMs) was dose dependent. Furthermore, Re-LPS completely suppressed cit-Fb-mediated CXCL10 induction in RSCs and PBMs.

CONCLUSION

To easily identify LPS contamination during routine experiments, our results suggest that Re-LPS is a better tool for rapid detection of LPS contamination compared to PMB and heat treatment.

A respirable HPV-L2 dry-powder vaccine with GLA as amphiphilic lubricant and immune-adjuvant

Vaccines not requiring cold-chain storage/distribution and suitable for needle-free delivery are urgently needed. Pulmonary administration is one of the most promising non-parenteral routes for vaccine delivery. Through a multi-component excipient and spray-drying approach, we engineered highly respirable dry-powder vaccine particles containing a three-fold repeated peptide epitope derived from human papillomavirus (HPV16) minor capsid protein L2 displayed on Pyrococcus furious thioredoxin as antigen. A key feature of our engineering approach was the use of the amphiphilic endotoxin derivative glucopyranosyl lipid A (GLA) as both a coating agent enhancing particle de-aggregation and respirability as well as a built-in immune-adjuvant. Following an extensive characterization of the in vitro aerodynamic performance, lung deposition was verified in vivo by intratracheal administration in mice of a vaccine powder containing a fluorescently labeled derivative of the antigen. This was followed by a short-term immunization study that highlighted the ability of the GLA-adjuvanted vaccine powder to induce an anti-L2 systemic immune response comparable to (or even better than) that of the subcutaneously administered liquid-form vaccine. Despite the very short-term immunization conditions employed for this preliminary vaccination experiment, the intratracheally administered dry-powder, but not the subcutaneously injected liquid-state, vaccine induced consistent HPV neutralizing responses. Overall, the present data provide proof-of-concept validation of a new formulation design to produce a dry-powder vaccine that may be easily transferred to other antigens.

Endotoxin contamination in ovalbumin as viewed from a nano-immunotherapy perspective

Ovalbumin (OVA) is a model antigen commonly incorporated in smartly designed nanoparticles for delivery into antigen-presenting cells (APC), aiming to investigate the immune activity and therapeutic efficacy of nanoparticles that contain immunoregulatory compounds. However, the immunoresponse observed in nano-immunotherapy may unexpectedly arise from endotoxin impurity of OVA in the nanoparticles. Literature review shows that most researchers did not notice the importance of endotoxin-free OVA when used in nano-immunotherapy studies. Concentration at as low as 5 μg/ml OVA from Sigma-Aldrich (contains 0.625 ng/ml endotoxin) was able to activate APC such as dendritic cells and macrophages. Here, we proposed that the endotoxin impurity in OVA or the finished nanoproducts should be determined by both Limulus Amebocyte Lysate (LAL) and cell-based assay, to ensure the endotoxin-free quality of the nanoparticles. The endotoxin in OVA can be removed by endotoxin removal column and phase separation methods and endotoxin-free OVA can be purchased. This perspective alerts the researchers of endotoxin impurity of OVA that may transfer into the finished nanoparticles and introduce an unfavorable immunoregulatory function with false-positive results. OVA with minimal endotoxin level should be used in nano-immunotherapy studies to accurately reflect the true effects of nanoparticles on the immune system. This article is categorized under: Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

An antibody-based enzymatic therapy for cancer treatment: The selective localization of D-amino acid oxidase to EDA fibronectin

In order to generate an antibody directed enzyme prodrug therapy, here we designed a chimeric protein by fusing the F8 antibody that recognizes the EDA of fibronectin (expressed on the tumor neovasculature) and an evolved variant of the ROS-generating enzyme D-amino acid oxidase (DAAO). The F8(scFv)-DAAO-Q144R recombinant protein is expressed by both CHO-S and E. coli cells. The F8(scFv)-DAAO-Q144R from E. coli cells is fully soluble, shows a high specific activity, is more thermostable in blood than the native DAAO, possesses a binding affinity for EDA well suited for efficient tumor accumulation, and localizes in tumor tissues. Notably, the F8(scFv)-DAAO-Q144R conjugate generates a stronger cytotoxicity to tumor cells than the native enzyme, especially when an inhibitor of heme oxygenase-1 (HO-1) is used, making it a promising candidate for a selective antitumor oxidative therapy controlled by the substrate addition, in the so called "activity on demand", thus sparing normal tissue from damage.

Soluble Prokaryotic Overexpression and Purification of Human GM-CSF Using the Protein Disulfide Isomerase b'a' Domain

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a member of the colony-stimulating factor (CSF) family, which functions to enhance the proliferation and differentiation of hematopoietic stem cells and other hematopoietic lineages such as neutrophils, dendritic cells, or macrophages. These proteins have thus generated considerable interest in clinical therapy research. A current obstacle to the prokaryotic production of human GM-CSF (hGM-CSF) is its low solubility when overexpressed and subsequent complex refolding processes. In our present study, the solubility of hGM-CSF was examined when combined with three N-terminal fusion tags in five E. coli strains at three different expression temperatures. In the five E. coli strains BL21 (DE3), ClearColi BL21 (DE3), LOBSTR, SHuffle T7 and Origami2 (DE3), the hexahistidine-tagged hGM-CSF showed the best expression but was insoluble in all cases at each examined temperature. Tagging with the maltose-binding protein (MBP) and the b'a' domain of protein disulfide isomerase (PDIb'a') greatly improved the soluble overexpression of hGM-CSF at 30 °C and 18 °C. The solubility was not improved using the Origami2 (DE3) and SHuffle T7 strains that have been engineered for disulfide bond formation. Two conventional chromatographic steps were used to purify hGM-CSF from the overexpressed PDIb'a'-hGM-CSF produced in ClearColi BL21 (DE3). In the experiment, 0.65 mg of hGM-CSF was isolated from a 0.5 L flask culture of these E. coli and showed a 98% purity by SDS-PAGE analysis and silver staining. The bioactivity of this purified hGM-CSF was measured at an EC₅₀ of 16.4 ± 2 pM by a CCK8 assay in TF-1 human erythroleukemia cells.

Pseudomonas aeruginosa DnaK Stimulates the Production of Pentraxin 3 via TLR4-Dependent NF-κB and ERK Signaling Pathways

Microbe-derived factors trigger innate immune responses through the production of inflammatory mediators, including pentraxin 3 (PTX3). PTX3 is a soluble pattern recognition molecule that stimulates the clearance of clinically important bacterial pathogens such as Pseudomonas aeruginosa. However, the P. aeruginosa factors responsible for the production of PTX3 have not been elucidated. In this study, we found that P. aeruginosa DnaK, a homolog of heat shock protein 70, induced PTX3 production. Induction was mediated by intracellular signals transmitted through the Toll-like receptor 4 (TLR4) signaling pathway. Following receptor engagement, the stimulatory signals were relayed initially through the nuclear factor kappa B (NF-κB) signaling pathway and subsequently by extracellular signal-regulated kinases (ERK), which are mitogen-activated protein kinases. However, ERK activation was negatively controlled by NF-κB, implying the existence of negative crosstalk between the NF-κB and the ERK pathways. These data suggest that P. aeruginosa DnaK acts as a pathogen-associated molecular pattern to trigger modulation of host defense responses via production of PTX3.

Primary and Memory Response of Human Monocytes to Vaccines: Role of Nanoparticulate Antigens in Inducing Innate Memory

Innate immune cells such as monocytes and macrophages are activated in response to microbial and other challenges and mount an inflammatory defensive response. Exposed cells develop the so-called innate memory, which allows them to react differently to a subsequent challenge, aiming at better protection. In this study, using human primary monocytes in vitro, we have assessed the memory-inducing capacity of two antigenic molecules of Schistosoma mansoni in soluble form compared to the same molecules coupled to outer membrane vesicles of Neisseria lactamica. The results show that particulate challenges are much more efficient than soluble molecules in inducing innate memory, which is measured as the production of inflammatory and anti-inflammatory cytokines (TNFα, IL-6, IL-10). Controls run with LPS from Klebsiella pneumoniae compared to the whole bacteria show that while LPS alone has strong memory-inducing capacity, the entire bacteria are more efficient. These data suggest that microbial antigens that are unable to induce innate immune activation can nevertheless participate in innate activation and memory when in a particulate form, which is a notion that supports the use of nanoparticulate antigens in vaccination strategies for achieving adjuvant-like effects of innate activation as well as priming for improved reactivity to future challenges.

Triton X-114 and Amine-Based Wash Strategy Reduces Lipopolysaccharides to FDA Limit and Achieves Purer, More Potent Recombinant Immunotoxin

Many proteins are still routinely expressed prokaryotically in Escherichia coli, some because they are toxic to eukaryotes. Immunotoxins, which are fusion proteins of a targeting moiety and a truncated Pseudomonas exotoxin A, kill target cells by arresting protein synthesis. Thus, immunotoxins must be expressed in E. coli. Proteins expressed in E. coli are contaminated by endotoxin (also called lipopolysaccharides (LPS)). LPS binds to toll-like receptors, inducing up to life-threatening systemic inflammation in mammals. Therefore, accepted LPS limits for therapeutics as well as for substances used in immunological studies in animals are very low. Here, we report the use of Triton X-114 and polyamine-based wash strategies, which only in combination achieved LPS-contamination well below FDA limits. Resulting LPS-reduced immunotoxins were purer and up to 2.4-fold more active in vitro. Increased activity was associated with a 2.4-fold increase in affinity on cell surface expressed target antigen. The combination method maintained enzymatic function, protein stability, and in vivo efficacy and was effective for Fab as well as dsFv formats. With some modifications, the principle of this novel combination may be applied to any chromatography-based purification process.

Electrostatic-Mediated Affinity Tuning of Lysostaphin Accelerates Bacterial Lysis Kinetics and Enhances In Vivo Efficacy

Drug-resistant bacterial pathogens are a serious threat to global health, and antibacterial lysins are at the forefront of innovative treatments for these life-threatening infections. While lysins' general mechanism of action is well understood, the design principles that might enable engineering of performance-enhanced variants are still being formulated. Here, we report a detailed analysis of molecular determinants underlying the in vivo efficacy of lysostaphin, a canonical anti-MRSA (methicillin-resistant Staphylococcus aureus) lysin. Systematic analysis of bacterial binding, growth inhibition, lysis kinetics, and in vivo therapeutic efficacy revealed that binding affinity, and not inherent catalytic firepower, is the dominant driver of lysostaphin efficacy. This insight enabled electrostatic affinity tuning of lysostaphin to produce a single point mutant that manifested dramatically enhanced processivity and lysis kinetics and trended toward improved in vivo efficacy. More generally, these studies provide important insights into the complex relationships between lysin electrostatics, bacterial targeting, cell lysis efficiency, and in vivo efficacy. The lessons learned may enable engineering of other high-performance antibacterial biocatalysts.

Combined Method to Remove Endotoxins from Protein Nanocages for Drug Delivery Applications: The Case of Human Ferritin

Protein nanocages represent an emerging candidate among nanoscaled delivery systems. Indeed, they display unique features that proved to be very interesting from the nanotechnological point of view such as uniform structure, stability in biological fluids, suitability for surface modification to insert targeting moieties and loading with different drugs and dyes. However, one of the main concerns regards the production as recombinant proteins in E. coli, which leads to a product with high endotoxin contamination, resulting in nanocage immunogenicity and pyrogenicity. Indeed, a main challenge in the development of protein-based nanoparticles is finding effective procedures to remove endotoxins without affecting protein stability, since every intravenous injectable formulation that should be assessed in preclinical and clinical phase studies should display endotoxins concentration below the admitted limit of 5 EU/kg. Different strategies could be employed to achieve such a result, either by using affinity chromatography or detergents. However, these strategies are not applicable to protein nanocages as such and require implementations. Here we propose a combined protocol to remove bacterial endotoxins from nanocages of human H-ferritin, which is one of the most studied and most promising protein-based drug delivery systems. This protocol couples the affinity purification with the Endotrap HD resin to a treatment with Triton X-114. Exploiting this protocol, we were able to obtain excellent levels of purity maintaining good protein recovery rates, without affecting nanocage interactions with target cells. Indeed, binding assay and confocal microscopy experiments confirm that purified H-ferritin retains its capability to specifically recognize cancer cells. This procedure allowed to obtain injectable formulations, which is preliminary to move to a clinical trial.

Chitosan hydrogel loaded with recombinant protein containing epitope C from HSP90 of Candida albicans induces protective immune responses against systemic candidiasis

We reported previously a recombinant protein (rP-HSP90C) containing epitope C from heat shock protein 90 of Candida albicans mediates protective immune responses against systemic candidiasis. However, it exhibits weak immunogenicity. Therefore, we evaluated the potential and mechanisms of thermosensitive chitosan hydrogel (CH-HG) as an adjuvant in rP-HSP90C vaccine. CH-HG synthesized by ionic cross-linking showed buffering capacity and control-released rP-HSP90C in vitro. In comparison to naked rP-HSP90C, CH-HG-loaded rP-HSP90C (CH-HG/rP-HSP90C) not only evoked a long-lasting rP-HSP90C-specific IgG, but also enhanced Th1, Th2, Th17 responses and the ratio of Th1/Th2 in vivo; Meanwhile, CH-HG/rP-HSP90C provoked a stronger CTL response than rP-HSP90C. Notably, CH-HG increased the protective immune responses against systemic candidiasis in rP-HSP90C-immunized mice since CH-HG/rP-HSP90C enhanced the survival rate of infected mice, and diminished the CFUs in kidneys compared to rP-HSP90C, which were similar to that of QuilA. Further in vitro investigation displayed CH-HG upgraded the expressions of costimulators, MHCs and cytokines in BMDCs compared to rP-HSP90C；CH-HG also promoted cellular uptake, endosomal escape and "cross-presentation" of rP-HSP90C. In addition, it recruited immune cells at the injection site. Our study demonstrated that CH-HG can be an efficient adjuvant in fungal vaccines.

Exploring the potential of the recombinant human collagens for biomedical and clinical applications: a short review

Natural animal collagen and its recombinant collagen are favourable replacements in human tissue engineering due to their remarkable biomedical property. However, this exploitation is largely restricted due to the potential of immunogenicity and virus contamination. Exploring new ways to produce human collagen is fundamental to its biomedical and clinical application. All human fibrillar collagen molecules have three polypeptide chains constructed from a repeating Gly-Xaa-Yaa triplet, where Xaa and Yaa represent one random amino acid. Using cDNA techniques to modify several repeat sequences of the cDNA fragment, a novel human collagen, named recombinant human-like collagen (rHLC), with low immunogenicity and little risk from hidden virus can be engineered and notably tailored to specific applications. Human-like collagen (HLC) was initially used as a coating to modify the tissue engineering scaffold, and then used as the scaffold after cross-link agents were added to increase its mechanical strength. Due to its good biocompatibility, low immunogenicity, stabilised property, and the ability of mass production, HLC has been widely used in skin injury treatments, vascular scaffolds engineering, cartilage, bone defect repair, skincare, haemostatic sponge, and drug delivery, including coating with medical nanoparticles. In this review, we symmetrically reviewed the development, recent advances in design and application of HLC, and other recombinant human collagen-based biomedicine potentials. At the end, future improvements are also discussed.

HSP70-Homolog DnaK of Pseudomonas aeruginosa Increases the Production of IL-27 through Expression of EBI3 via TLR4-Dependent NF-κB and TLR4-Independent Akt Signaling

IL-27, a heterodimeric cytokine composed of the p28 subunit and Epstein–Barr virus-induced gene 3 (EBI3), acts as a potent immunosuppressant and thus limits pathogenic inflammatory responses. IL-27 is upregulated upon Pseudomonas aeruginosa infection in septic mice, increasing susceptibility to the infection and decreasing clearance of the pathogen. However, it remains unclear which P. aeruginosa-derived molecules promote production of IL-27. In this study, we explored the mechanism by which P. aeruginosa DnaK, a heat shock protein 70-like protein, induces EBI3 expression, thereby promoting production of IL-27. Upregulation of EBI3 expression did not lead to an increase in IL-35, which consists of the p35 subunit and EBI3. The IL-27 production in response to DnaK was biologically active, as reflected by stimulation of IL-10 production. DnaK-mediated expression of EBI3 was driven by two distinct signaling pathways, NF-κB and Akt. However, NF-κB is linked to TLR4-associated signaling pathways, whereas Akt is not. Taken together, our results reveal that P. aeruginosa DnaK potently upregulates EBI3 expression, which in turn drives production of the prominent anti-inflammatory cytokine IL-27, as a consequence of TLR4-dependent activation of NF-κB and TLR4-independent activation of the Akt signaling pathway.

Globally deimmunized lysostaphin evades human immune surveillance and enables highly efficacious repeat dosing

There is a critical need for novel therapies to treat methicillin-resistant Staphylococcus aureus (MRSA) and other drug-resistant pathogens, and lysins are among the vanguard of innovative antibiotics under development. Unfortunately, lysins' own microbial origins can elicit detrimental antidrug antibodies (ADAs) that undermine efficacy and threaten patient safety. To create an enhanced anti-MRSA lysin, a novel variant of lysostaphin was engineered by T cell epitope deletion. This "deimmunized" lysostaphin dampened human T cell activation, mitigated ADA responses in human HLA transgenic mice, and enabled safe and efficacious repeated dosing during a 6-week longitudinal infection study. Furthermore, the deimmunized lysostaphin evaded established anti-wild-type immunity, thereby providing significant anti-MRSA protection for animals that were immune experienced to the wild-type enzyme. Last, the enzyme synergized with daptomycin to clear a stringent model of MRSA endocarditis. By mitigating T cell-driven antidrug immunity, deimmunized lysostaphin may enable safe, repeated dosing to treat refractory MRSA infections.

Intravitreal Pharmacokinetic Study of the Antiangiogenic Glycoprotein Opticin

Opticin is an endogenous vitreous glycoprotein that may have therapeutic potential as it has been shown that supranormal concentrations suppress preretinal neovascularization. Herein we investigated the pharmacokinetics of opticin following intravitreal injection in rabbits. To measure simultaneously concentrations of human and rabbit opticin, a selected reaction monitoring mass spectrometry assay was developed. The mean concentration of endogenous rabbit opticin in 7 uninjected eyes was measured and found to be 19.2 nM or 0.62 μg/mL. When the vitreous was separated by centrifugation into a supernatant and collagen-containing pellet, 94% of the rabbit opticin was in the supernatant. Intravitreal injection of human opticin (40 μg) into both eyes of rabbits was followed by enucleation at 5, 24, and 72 h and 7, 14, and 28 days postinjection (n = 6 at each time point) and measurement of vitreous human and rabbit opticin concentrations in the supernatant and collagen-containing pellet following centrifugation. The volume of distribution of human opticin was calculated to be 3.31 mL, and the vitreous half-life was 4.2 days. Assuming that rabbit and human opticin are cleared from rabbit vitreous at the same rate, opticin is secreted into the vitreous at a rate of 0.14 μg/day. We conclude that intravitreally injected opticin has a vitreous half-life that is similar to currently available antiangiogenic therapeutics. While opticin was first identified bound to vitreous collagen fibrils, here we demonstrate that >90% of endogenous opticin is not bound to collagen. Endogenous opticin is secreted by the nonpigmented ciliary epithelium into the rabbit vitreous at a remarkably high rate, and the turnover in vitreous is approximately 15% per day.

The preparation of endotoxin-free genetically engineered murine B1 antisense RNA

One of the major limitations in the production of genetically engineered RNA from Escherichia coli (E. coli) is contamination by endotoxin. Here we report the first method that is capable of removing endotoxin from genetically engineered RNA. As a proof of concept, we transformed E. coli with a plasmid containing a tandem short interspersed nuclear elements from the mouse genome (SINE B1 elements). We then evaluated several extraction methods (SDS-NaCl centrifugation, SDS-NaCl filtration, TRIzol and SDS hot-phenol) and refinements thereof, and measured the resulting RNA yield, RNA purity, RNA integrity and endotoxin content. SDS-NaCl filtration with 2 mol/L NaCl, incorporating DEPC as an RNA protective agent, effectively removed endotoxin and resulted in a good RNA yield. Triton X-114 phase separation further reduced the endotoxin content of SDS-NaCl filtration-extracted RNA. RNA extracted by SDS-NaCl filtration with Triton X-114 phase separation did not cause adverse reactions in BALB/c mice and did not induce fever in rabbits when injected into these animals. The RNA met the requirements of nucleic acid reagents for in vivo experiments on animals.

Current technologies to endotoxin detection and removal for biopharmaceutical purification

Endotoxins are the major contributors to the pyrogenic response caused by contaminated pharmaceutical products, formulation ingredients, and medical devices. Recombinant biopharmaceutical products are manufactured using living organisms, including Gram-negative bacteria. Upon the death of a Gram-negative bacterium, endotoxins (also known as lipopolysaccharides) in the outer cell membrane are released into the lysate where they can interact with and form bonds with biomolecules, including target therapeutic compounds. Endotoxin contamination of biologic products may also occur through water, raw materials such as excipients, media, additives, sera, equipment, containers closure systems, and expression systems used in manufacturing. The manufacturing process is, therefore, in critical need of methods to reduce and remove endotoxins by monitoring raw materials and in-process intermediates at critical steps, in addition to final drug product release testing. This review paper highlights a discussion on three major topics about endotoxin detection techniques, upstream processes for the production of therapeutic molecules, and downstream processes to eliminate endotoxins during product purification. Finally, we have evaluated the effectiveness of endotoxin removal processes from a perspective of high purity and low cost.

Immunization with PhtD truncated fragments reduces nasopharyngeal colonization by Streptococcus pneumoniae

Despite the undeniable success of polysaccharide vaccines against Streptococcus pneumoniae infections, there is a consensus on the scientific field that this approach should be revised in order to overpass the problems related with these formulations, such as serotype replacement and high production costs. The study of conserved pneumococcal proteins or its truncated fragments has emerged as a serotype independent alternative. In this work, we have characterized the immune response elicited by systemic immunization of mice with the Histidine triad protein D (PhtD) and its' amino and carboxyl terminal fragments. The proteins were shown to be immunogenic and protective against pneumococcal colonization, with increased IL-17 production, and induction of antibodies able to limit pneumococcal adhesion to human respiratory cells. Antiserum against PhtD_Nter, but not C_ter or PhtD, promoted an increase in bacterial phagocytosis in vitro. Interestingly, antibodies against the PhtD_Nter displayed cross-reactivity with two other pneumococcal proteins, PspA and PspC, due to sequence similarities in the proline rich region of the molecules. On a whole, our results support the inclusion of PhtD, and more specifically, its N-terminal fragment, in a multicomponent serotype independent vaccine.

Quantitative Control of Gene-Engineered T-Cell Activity through the Covalent Attachment of Targeting Ligands to a Universal Immune Receptor

Universal immune receptors represent a rapidly emerging form of adoptive T-cell therapy with the potential to overcome safety and antigen escape challenges faced by conventional chimeric antigen receptor (CAR) T-cell therapy. By decoupling antigen recognition and T-cell signaling domains via bifunctional antigen-specific targeting ligands, universal immune receptors can regulate T-cell effector function and target multiple antigens with a single receptor. Here, we describe the development of the SpyCatcher immune receptor, the first universal immune receptor that allows for the post-translational covalent attachment of targeting ligands at the T-cell surface through the application of SpyCatcher-SpyTag chemistry. The SpyCatcher immune receptor redirected primary human T cells against a variety of tumor antigens via the addition of SpyTag-labeled targeting ligands, both in vitro and in vivo. SpyCatcher T-cell activity relied upon the presence of both target antigen and SpyTag-labeled targeting ligand, allowing for dose-dependent control of function. The mutational disruption of covalent bond formation between the receptor and the targeting ligand still permitted redirected T-cell function but significantly compromised antitumor function. Thus, the SpyCatcher immune receptor allows for rapid antigen-specific receptor assembly, multiantigen targeting, and controllable T-cell activity.

Antimicrobial Role of RNASET2 Protein During Innate Immune Response in the Medicinal Leech Hirudo verbana

The innate immune response represents a first-line defense against pathogen infection that has been widely conserved throughout evolution. Using the invertebrate Hirudo verbana (Annelida, Hirudinea) as an experimental model, we show here that the RNASET2 ribonuclease is directly involved in the immune response against Gram-positive bacteria. Injection of lipoteichoic acid (LTA), a key component of Gram-positive bacteria cell wall, into the leech body wall induced a massive migration of granulocytes and macrophages expressing TLR2 (the key receptor involved in the response to Gram-positive bacteria) toward the challenged/inoculated area. We hypothesized that the endogenous leech RNASET2 protein (HvRNASET2) might be involved in the antimicrobial response, as already described for other vertebrate ribonucleases, such as RNase3 and RNase7. In support of our hypothesis, HvRNASET2 was mainly localized in the granules of granulocytes, and its release in the extracellular matrix triggered the recruitment of macrophages toward the area stimulated with LTA. The activity of HvRNASET2 was also evaluated on Staphylococcus aureus living cells by means of light, transmission, and scanning electron microscopy analysis. HvRNASET2 injection triggered the formation of S. aureus clumps following a direct interaction with the bacterial cell wall, as demonstrated by immunogold assay. Taken together, our data support the notion that, during the early phase of leech immune response, granulocyte-released HvRNASET2 triggers bacterial clumps formation and, at the same time, actively recruits phagocytic macrophages in order to elicit a rapid and effective eradication of the infecting microorganisms from inoculated area.

Recombinant HvRNASET2 protein induces marked connective tissue remodelling in the invertebrate model Hirudo verbana

The RNASET2 ribonuclease, belonging to the highly conserved RH/T2/s RNase gene family, has been recently shown to modulate inflammatory processes in both vertebrates and invertebrates. Indeed, the RNASET2 protein acts as a chemoattractor for macrophages in both in vitro and in vivo experimental settings and its expression significantly increases following bacterial infections. Moreover, we recently observed that injection of human recombinant RNASET2 protein in the body wall of the medicinal leech (a consolidated invertebrate model for both immune response and tissue regeneration) not only induced immune cell recruitment but also apparently triggered massive connective tissue remodelling as well. Based on these data, we evaluate here a possible role of leech recombinant RNASET2 protein (rHvRNASET2) in connective tissue remodelling by characterizing the cell types involved in this process through histochemical, morphological and immunofluorescent assays. Moreover, a time-course expression analysis of newly synthesized pro-collagen1α1 (COL1α1) and basic FGF receptor (bFGFR, a known fibroblast marker) following rHvRNASET2 injection in the leech body wall further supported the occurrence of rHvRNASET2-mediated matrix remodelling. Human MRC-5 fibroblast cells were also investigated in order to evaluate their pattern of collagen neosynthesis driven by rHvRNASET2 injection.Taken together, the data reported in this work provide compelling evidence in support of a pleiotropic role for RNASET2 in orchestrating an evolutionarily conserved crosstalk between inflammatory response and regenerative process, based on macrophage recruitment and fibroblast activation, coupled to a massive extracellular reorganization.

LRR domain of NLRX1 protein delivery by dNP2 inhibits T cell functions and alleviates autoimmune encephalomyelitis

Multiple sclerosis (MS) is a demyelinating inflammatory disease of the central nervous system (CNS), which is a chronic progressive disease and is caused by uncontrolled activation of myelin antigen specific T cells. It has high unmet medical needs due to the difficulty of efficient drug delivery into the CNS to control tissue inflammation. In this study, we demonstrate that a fusion protein of NOD-like receptor family member X1 (NLRX1) and blood brain barrier (BBB)-permeable peptide, dNP2 ameliorates experimental autoimmune encephalomyelitis (EAE). Methods: We purified recombinant LRR or NBD regions of NLRX1 protein conjugated with dNP2. To examine intracellular delivery efficiency of the recombinant protein, we incubated the proteins with Jurkat T cells or murine splenic T cells and their delivery efficiency was analyzed by flow cytometry. To investigate the therapeutic efficacy in an EAE model, we injected the recombinant protein into mice with 3 different treatment schemes e.g., prevention, semi-therapeutic, and therapeutic. To analyze their functional roles in T cells, we treated MACS-sorted naïve CD4 T cells with the proteins during their activation and differentiation into Th1, Th17, and Treg cells. Results: dNP2-LRR protein treatment showed significantly higher delivery efficiency than TAT-LRR or LRR alone in Jurkat T cells and mouse splenic T cells. In all three treatment schemes of EAE experiments, dNP2-LRR administration showed ameliorated tissue inflammation and disease severity with reduced number of infiltrating T cells producing inflammatory cytokines such as IFNγ. In addition, dNP2-LRR inhibited T cell activation, cytokine production, and Th1 differentiation. Conclusion: These results suggest that dNP2-LRR is a novel agent, which regulates effector T cell functions and could be a promising molecule for the treatment of CNS autoimmune diseases such as multiple sclerosis.

Immunization with the recombinant myosin regulatory light chain (FhrMRLC) in Adjuplex® adjuvant elicits a Th1-biased immune response and a reduction of parasite burden in Fasciola hepatica infected rats

The aim of this study was to assess the immune response and the protective efficacy elicited by the vaccination with the recombinant Fasciola hepatica myosin regulatory light chain (FhrMRLC) in Adjuplex® adjuvant against the infection with F. hepatica in rats. Four groups of 15 animals each were used for the study, one group was immunized with the recombinant F. hepatica MRLC in Adjuplex® adjuvant and the other groups remained as adjuvant, positive and negative control groups. The parasitological study showed that a statistically significant reduction of 65.1% and 82.1% in fluke burden and fecal egg count, respectively, was detected in vaccinated animals. In addition, vaccination with FhrMRLC induced a well-defined humoral and cellular immune response characterized by a significant production of specific IgG and IL-2, IL-12, TNF-α and IFN-γ; which confirms the immunogenic capacity of the FhrMRLC.

Cowpea Mosaic Virus Nanoparticles and Empty Virus-Like Particles Show Distinct but Overlapping Immunostimulatory Properties

Cowpea mosaic virus (CPMV) is a plant virus that has been developed for multiple biomedical and nanotechnology applications, including immunotherapy. Two key platforms are available: virus nanoparticles (VNPs) based on the complete CMPV virion, including the genomic RNA, and virus-like nanoparticles (VLPs) based on the empty CPMV (eCPMV) virion. It is unclear whether these platforms differ in terms of immunotherapeutic potential. We therefore compared their physicochemical properties and immunomodulatory activities following in situ vaccination of an aggressive ovarian tumor mouse model (ID8-Defb29/Vegf-A). In physicochemical terms, CPMV and eCPMV were very similar, and both significantly increased the survival of tumor-bearing mice and showed promising antitumor efficacy. However, they demonstrated distinct yet overlapping immunostimulatory effects due to the presence of virus RNA in wild-type particles, indicating their suitability for different immunotherapeutic strategies. Specifically, we found that the formulations had similar effects on most secreted cytokines and immune cells, but the RNA-containing CPMV particles were uniquely able to boost populations of potent antigen-presenting cells, such as tumor-infiltrating neutrophils and activated dendritic cells. Our results will facilitate the development of CPMV and eCPMV as immunotherapeutic vaccine platforms with tailored responses.IMPORTANCE The engagement of antiviral effector responses caused by viral infection is essential when using viruses or virus-like particles (VLPs) as an immunotherapeutic agent. Here, we compare the chemophysical and immunostimulatory properties of wild-type cowpea mosaic virus (CPMV) (RNA containing) and eCPMV (RNA-free VLPs) produced from two expression systems (agrobacterium-based plant expression system and baculovirus-insect cell expression). CPMV and eCPMV could each be developed as novel adjuvants to overcome immunosuppression and thus promote tumor regression in ovarian cancer (and other tumor types). To our knowledge, this is the first study to define the immunotherapeutic differences between CPMV and eCPMV, which is essential for the further development of biomedical applications for plant viruses and the selection of rational combinations of immunomodulatory reagents.

Design and immunogenicity analysis of the combined vaccine against zoonotic hepatitis E and foot-and-mouth disease

AIM

Design and immunogenicity assessment of the combined vaccine candidate against zoonotic hepatitis E virus (HEV) and foot-and-mouth disease virus (FMDV).

METHODS

Using the molecular cloning technology, we produced and purified 9 HEV ORF2-truncated proteins (HEV genotype 4). Then, we compared their thermal stability, antigenicity, and immunogenicity to select the best HEV immunogen. Next, we used the adjuvant Montanide ISA-206 to prepare different formulations of HEV vaccine alone, FMDV vaccine alone and HEV-FMDV combined vaccine. The formulations were injected into mice and the induced humoral immune responses were monitored up 12 weeks post-immunization.

RESULTS

The HEV p222 protein could self-assemble into VLPs (∼34 nm) and showed higher stability and better antigenicity/immunogenicity than the other HEV antigens, thus it was selected as the best HEV immunogen. Mice immunization with the FMDV vaccine alone induced high FMDV-specific antibody titers in a dose-dependent manner; the HEV p222 protein also induced high levels of anti-HEV antibodies but in a dose-independent manner. The HEV-FMDV combination induced anti-FMDV antibody titers 7-16-fold higher than the titers induced by the FMDV vaccine alone, and HEV-specific antibody titers 2.4-fold higher than those induced by the HEV p222 antigen alone.

CONCLUSION

Herein, we proposed a new approach for the control of zoonotic HEV infection through its control in its main host (pig). We also designed the first HEV-FMDV combined vaccine and the preliminary analyses revealed a synergistic effect on the immunogenicity of both HEV and FMDV antigens.

A small-sized protein binder specific for human PD-1 effectively suppresses the tumour growth in tumour mouse model

Immune checkpoint inhibitors have drawn a consider attention as an effective cancer immunotherapy, and several monoclonal antibodies targeting the immune checkpoint receptors, such as human programmed cell death-1 (hPD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), are clinically used for treatment of various cancers. Here we present the development of a small-sized protein binder which specifically binds to hPD-1. The protein binder, which is composed of leucine-rich repeat (LRR) modules, was selected against hPD-1 through phage display, and its binding affinity was maturated up to 17 nM by modular evolution approach. The protein binder was shown to be highly specific for hPD-1, effectively inhibiting the interaction between hPD-1 and its ligand, hPD-L1. The protein binder restored T-cell function in vitro, and exhibited a strong anti-tumour activity in tumour mouse model, indicating that it acts as an effective checkpoint blockade. Based on the results, the developed protein binder specific for hPD-1 is likely to find a potential use in cancer immunotherapy.