Optimization of culture conditions for high-level expression of soluble and active tumor necrosis factor-α in E. coli.

Anti-TNF inhibitors exert their therapeutic effect by inhibition of the excessive amounts of TNF-α within the body. Recombinant TNF-α should be produced in a soluble refolded form to investigate the effectiveness and efficiency of anti-TNF-α compounds. In this research, the designed cassette was subcloned in the pET28a expression vector and expressed in E. coli BL21 (DE3). The identity of the protein was confirmed through SDS-PAGE and Western blotting. After optimizing expression conditions, protein purification was performed using native Ni-NTA affinity chromatography. The biological activity of the soluble recombinant TNF-α was investigated using MTT assay. Also, the affinity of an anti-TNF-α agent, Altebrel, was investigated against the expressed protein through ELISA. Optimization of TNF-α expression conditions represented that the highest expression could be achieved at 37 °C using 0.5 mM IPTG 6 h post-induction. The recombinant protein represented an inhibitory effect on the L929 murine fibroblast cell line and was successfully detected by Altebrel in ELISA. Binding kinetics were also studied using Cimzia as an anti-TNF-α molecule and 7.2 E-13M was calculated as the equilibrium dissociation constant value (KD). The significant expression level of the recombinant protein in the soluble form, its high purity, and assessment of its biological activity showed that the expressed protein could be used in tests of ELISA and MTT to assess the activity of anti-TNF-α agents.

Simultaneous detection of two growth factors from human single-embryo culture medium by a bead-based digital microfluidic chip.

The measurement of growth factors released in a culture medium is considered to be an attractive non-invasive approach, apart from the embryo morphology, to identify the condition of an embryo development after fertilization in vitro (IVF), but the available embryo culture medium in the current method is only a few microlitres. This small sample volume, also of small concentration, makes difficult the application of a conventional detection method, such as an enzyme-linked immunosorbent assay (ELISA). A reliable detection of the growth factor from each embryo culture medium of such a small concentration hence remains a challenge. Here for the first time we report the results of measurement of not just one, but two, growth factors, human IL-1ß and human TNF-α, from an individual droplet of embryo culture medium with a bead-based digital microfluidic chip. The required sample volume for a single measurement is only 520 nL; the total duration of the on-chip process is less than 40 min. Using the culture media of human embryos with normal morphologic features, we found that the concentrations of TNF-α change little from day 3 to day 5-6, but the concentrations of IL-1ß for some embryos might double from day 3 to day 5-6. For other embryos even with similar normal morphologic features, some growth factors, such as IL-1ß, might exhibit different expressions during the culture period. Those growth factors could serve to distinguish the development conditions of each embryo, not merely from an observation of embryo morphology.

Small molecules that inhibit TNF signalling by stabilising an asymmetric form of the trimer.

Tumour necrosis factor (TNF) is a cytokine belonging to a family of trimeric proteins; it has been shown to be a key mediator in autoimmune diseases such as rheumatoid arthritis and Crohn's disease. While TNF is the target of several successful biologic drugs, attempts to design small molecule therapies directed to this cytokine have not led to approved products. Here we report the discovery of potent small molecule inhibitors of TNF that stabilise an asymmetrical form of the soluble TNF trimer, compromising signalling and inhibiting the functions of TNF in vitro and in vivo. This discovery paves the way for a class of small molecule drugs capable of modulating TNF function by stabilising a naturally sampled, receptor-incompetent conformation of TNF. Furthermore, this approach may prove to be a more general mechanism for inhibiting protein-protein interactions.

Smartphone-based multicolor bioluminescent 3D spheroid biosensors for monitoring inflammatory activity.

Whole-cell biosensors present many advantages, including being able to monitor the toxicity and bioavailability of chemicals; cells grown in traditional 2D cultures, however, do not reproduce the complexity of in vivo physiology. In the last years, 3D cell-culture models have garnered great attention due to their capability to better mimic in vivo cellular responses to external stimuli, providing excellent model living organisms. In order to obtain a predictive, sensitive, and robust yet low-cost 3D cell biosensor, we developed a smartphone-based bioluminescent 3D cell biosensor platform for effect-based analysis. We exploited the Nuclear Factor-kappa B (NF-kB) signal transduction pathway, which is induced by several types of stressors and is involved in the regulation of cell-cycle/growth, inflammation, apoptosis, and immunity. The smartphone-based biosensor relies on immobilized HEK293 spheroids genetically engineered with powerful red- and green-emitting luciferases utilized as inflammation and viability reporters. It provides a limit of detection for Tumor Necrosis Factor (TNFα) of 0.15 ±â€¯0.05 ng/mL and could be a useful tool to initially screen environmental samples or other compounds on-site, especially for additional more accurate chemical analyses.

Targeted Delivery of TNF Potentiates the Antibody-Dependent Cell-Mediated Cytotoxicity of an Anti-Melanoma Immunoglobulin.

The recombinant murine IgG2a antibody TA99, directed against a melanoma antigen, was used to study combination modalities that potentiate antibody-dependent cell cytotoxicity. As previously reported, IgG2a(TA99) was extremely efficacious in preventing the growth of B16 lung metastases. However, the same antibody mediated only minimal tumor growth retardation when used to treat established neoplastic masses. The therapeutic activity of IgG2a(TA99) could be substantially enhanced by co-administration with an antibody-cytokine fusion (TA99-murine tumor necrosis factor [mTNF]), consisting of the TA99 antibody in single-chain variable fragment format fused to murine TNF. This fusion protein efficiently killed endothelial cells in vitro and displayed only minimal activity against B16 melanoma cells. In vivo, TA99-mTNF boosted the influx of natural killer cells and macrophages into B16 melanoma lesions. Therapy studies with two different administration schedules showed that the combination of TA99-mTNF and IgG2a(TA99) was superior to the individual products used as single agents. The combination treatment converted most of the tumor mass into a necrotic lesion, but a vital tumor rim eventually regrew, even when dacarbazine was included in the therapeutic regimen. The treatment modality described in this article may be applicable to the treatment of melanoma patients, given the specificity of the gp75 antigen and its conservation across species.

A Single Codon Optimization Enhances Recombinant Human TNF-α Vaccine Expression in Escherichia coli.

As a proinflammatory cytokine, tumor necrosis factor-alpha (TNF-α) plays a pivotal role in various autoimmune diseases such as rheumatoid arthritis (RA). Thus, TNF-α has been defined as a therapeutic target for RA. Although some TNF-α antagonists including neutralizing monoclonal antibodies and soluble receptors have been approved to be successful in attenuating symptoms in patients suffering from RA, the long-term use of these passive immunization reagents could cause some problems like a variable degree of immunogenicity. In the present study, in order to wake up active immune responses of RA patients, we developed a recombinant TNF-α therapeutic vaccine (named mrTNF-PADRE) by coupling a 12-amino acid universal Pan HLA-DR Epitope (PADRE) to the protein. Codon optimization was performed to improve the secondary structure of mrTNF-PADRE mRNA to ensure its heterologous expression. As a result, a single codon synonymous mutation greatly elevated recombinant protein expression (about 30% of the total bacteria proteins) in E. coli as compared with the undetectable expression of the unoptimized gene. Although expressed as insoluble inclusion bodies (IBs), the vaccine can be effectively prepared with a purity of over 95% by IBs washing and one-step gel-infiltration chromatography. By this strategy, a stable yield of 5.2 mg purified mrTNF-PADRE per gram of cell paste could be obtained.

Optimizing host cell physiology and stress avoidance for the production of recombinant human tumour necrosis factor α in Escherichia coli.

As high-level recombinant protein production (RPP) exerts a massive stress on the production host, an extensive literature on RPP optimization focuses on separating the growth phase from RPP production once sufficient biomass has been obtained. The aim of the current investigation was to optimize the benefits of the relatively neglected alternative strategy to achieve high-level RPP during growth by minimizing stress on the host. High yields of the biopharmaceutical recombinant human tumour necrosis factor alpha (rhTNFα) were obtained by fed-batch fermentation relevant to industrial production based upon parameters that most severely affected RPP in preliminary laboratory scale batch cultures. Decreasing the inducer concentration and growth temperature, but increasing the production period, were far more effective for increasing RPP yields than changing the growth phase at which production was induced. High yields of up to 5 g l-1 of rhTNFα were obtained with minimal plasmid loss, even in synthetic media that lack animal-derived components and are therefore fully compliant with regulatory requirements. Most of the product was soluble and biologically active. In summary, stress minimization was shown to be an effective way to optimize the production of rhTNFα. Data generated in shake-flask experiments allowed the design of intensified bioreactor cultures in which RPP and growth could be balanced, leading to higher yield of both rhTNFα and biomass than with previous fermentations. An additional benefit of this approach is avoidance of lysis during harvesting and downstream processing.

Purification of therapeutic proteins mediated by in vivo polyester immobilized sortase.

OBJECTIVES: To overcome laborious and costly procedures often associated with therapeutic protein production and purification, in vivo polyester immobilized sortase is explored for the production of human tumor necrosis factor alpha (TNFα) and human interferon alpha 2b (IFNα2b) by Escherichia coli. RESULTS: Hybrid genes encoding PhaC-Sortase-TNFα or PhaC-Sortase-IFNα2b fusions (with a LPETG recognition signal immediately before TNFα or IFNα2b), mediated intracellular production of polyester (polyhydroxyalkanoate, PHA) beads in Escherichia coli. Upon isolation of respective PHA beads, pure soluble TNFα or IFNα2b was released by activating sortase via addition of CaCl2 and triglycine. TNFα and IFNα2b each were recognized by corresponding conformational antibodies in an ELISA assay. CONCLUSIONS: In vivo polyester immobilized sortase could be exploited for production and purification of high-value therapeutic proteins without laborious and costly downstream processing.

Correspondence on Lovell et al.: identification of chicken genes previously assumed to be evolutionarily lost.

Through RNA-Seq analyses, we identified 137 genes that are missing in chicken, including the long-sought-after nephrin and tumor necrosis factor genes. These genes tended to cluster in GC-rich regions that have poor coverage in genome sequence databases. Hence, the occurrence of syntenic groups of vertebrate genes that have not been observed in Aves does not prove the evolutionary loss of such genes.Please see related Research article: http://dx.doi.org/10.1186/s13059-014-0565-1 and Please see response from Lovell et al: https://www.dx.doi.org/10.1186/s13059-017-1234-y.

Polystyrene-divinylbenzene based nano-CaCO3 composites for the efficient removal of human tumor necrosis factor-α.

PS-DVB/nano-CaCO3, a novel abundant mesoporous structured polymer nano-composite, was successfully synthesized via suspension polymerization. Characterization of this type of bead nano-composite demonstrated that it exhibits significantly enhanced TNF-α adsorption from blood plasma and possesses good mechanical strength.

Tumor necrosis factor-alpha inhibits differentiation of myogenic cells in human urethral rhabdosphincter.

OBJECTIVES: To examine the inhibitory effects of tumor necrosis factor-α on myogenic differentiation of human urethral rhabdosphincter cells. METHODS: A rhabdosphincter sample was obtained from a patient who underwent total cystectomy. To expand the lifespan of the primary cultured cells, rhabdosphincter myogenic cells were immortalized with mutated cyclin-dependent kinase 4, cyclin D1 and telomerase. The differential potential of the cells was investigated. The transfected human rhabdosphincter cells were induced for myogenic differentiation with recombinant human tumor necrosis factor-α and/or the tumor necrosis factor-α antagonist etanercept at different concentrations, and activation of signaling pathways was monitored. RESULTS: Human rhabdosphincter cells were selectively cultured for at least 40 passages. Molecular analysis confirmed the expression of myosin heavy chain, which is a specific marker of differentiated muscle cells, significantly increased after differentiation induction. Although tumor necrosis factor-α treatment reduced the myosin heavy chain expression in a concentration-dependent manner, etanercept inhibited this suppression. Tumor necrosis factor-α suppressed phosphorylation of protein kinase B and p38, whereas etanercept pretreatment promoted phosphorylation and myosin heavy chain expression in a concentration-dependent manner. CONCLUSIONS: Tumor necrosis factor-α inhibits differentiation of urethral rhabdosphincter cells in part through the p38 mitogen-activated protein kinase and phosphoinositide 3-kinase pathways. Inhibition of tumor necrosis factor-α might be a useful strategy to treat stress urinary incontinence.

Expression analysis and ATR-FTIR characterization of the secondary structure of recombinant human TNF-α from Escherichia coli SHuffle® T7 Express and BL21 (DE3) cells.

TNF-α, a prototype member of the TNF family of ligands, has both pro-inflammatory and immune-regulatory functions, which make it as an appropriate therapeutic target for selective blockade in antibody therapy of many diseases like in rheumatoid arthritis. Using two models of SHuffle® T7 Express and BL21 (DE3) cells, we have expressed this protein and recognized it by SDS-PAGE analysis. FTIR biospectroscopy of the resulted purified proteins has been performed and mathematical calculations has been done for further identification of the structural and conformational differences between the two products. Our results showed some differences in disulfide bond formation and ß-sheet turns between these two recombinant proteins. To the best of our knowledge, this is the first study that compare secondary structure of recombinant proteins in both conventional and next generation Escherichia coli based expression systems using reliable, simple, rapid and economic ATR-FTIR analysis. Whether these differences might have significant effects on TNF-α inflammatory and immune-regulatory function in biological systems might be very much important and need further investigations.

Adsorption as a Contributor for Inflammatory Mediators Removal by Different Hemofiltration Membranes: A Pilot Study.

Atherosclerosis is an important predictor of mortality in patients with chronic kidney disease (CKD) and is associated with a wide inflammatory response. The aim of this study is to evaluate in vitro how different membranes can remove mediators associated with this pathology in a closed loop dialysis model. We performed experimental hemofiltration in vitro using three different membrane materials. Human plasma was preliminarily incubated with various inflammatory mediators and filtered in a closed loop circulation model for 240 min. Respective concentrations of 17 different mediators were measured over time to study the removal mechanisms of each membrane, including associated removal time course. The experiment was repeated three times for the assay of tumor necrosis factor (TNF)-α to document the model variability. Means were compared using Mann-Whitney test. Most of the investigated mediators were effectively removed with the different dialysis membranes. Adsorption mechanism was mainly at the origin of the decrease in mediators circulating concentrations and was maximized in the region 10 000-20 000 Da. Especially, the HeprAN membrane showed fast removal capacities of mediators with elevated isoelectric point including complement factors and chemokines or having basic groups located in the protein periphery, plasminogen activator inhibitor (PAI-1), and TNF-α-like. The latter was further significantly removed with HeprAN and polymethylmethacrylate (PMMA) compared to polyethersulfone (PES) material (P < 0.01). We concluded that dialysis using ionic adsorptive membrane could have a beneficial impact for CKD patients with atherosclerosis and would deserve further clinical investigations.

Challenges and Opportunities in the Development of Aptamers for TNFα.

RNA aptamers for tumor necrosis factor-alpha (TNFα), for which functionality was demonstrated in L929 cells, show only little affinity for the protein in vitro. Detailed investigation of the aptamer-protein interaction by surface plasmon resonance and quartz crystal microbalance analysis revealed that affinity is not the only crucial parameter for efficacy and functionality of those aptamers. Instead, the sensitive equilibrium of the monomeric and homotrimeric form of soluble TNFα decides on aptamer binding. Our results show that the field of application and the source of TNFα have to be carefully defined before selection of aptamer sequences.

Direct Write Protein Patterns for Multiplexed Cytokine Detection from Live Cells Using Electron Beam Lithography.

Simultaneous detection of multiple biomarkers, such as extracellular signaling molecules, is a critical aspect in disease profiling and diagnostics. Precise positioning of antibodies on surfaces, especially at the micro- and nanoscale, is important for the improvement of assays, biosensors, and diagnostics on the molecular level, and therefore, the pursuit of device miniaturization for parallel, fast, low-volume assays is a continuing challenge. Here, we describe a multiplexed cytokine immunoassay utilizing electron beam lithography and a trehalose glycopolymer as a resist for the direct writing of antibodies on silicon substrates, allowing for micro- and nanoscale precision of protein immobilization. Specifically, anti-interleukin 6 (IL-6) and antitumor necrosis factor alpha (TNFα) antibodies were directly patterned. Retention of the specific binding properties of the patterned antibodies was shown by the capture of secreted cytokines from stimulated RAW 264.7 macrophages. A sandwich immunoassay was employed using gold nanoparticles and enhancement with silver for the detection and visualization of bound cytokines to the patterns by localized surface plasmon resonance detected with dark-field microscopy. Multiplexing with both IL-6 and TNFα on a single chip was also successfully demonstrated with high specificity and in relevant cell culture conditions and at different times after cell stimulation. The direct fabrication of capture antibody patterns for cytokine detection described here could be useful for biosensing applications.

A Simple and Rapid Method for Expression and Purification of Functional TNF-α Using GST Fusion System.

Tumor necrosis factor alpha (TNF-α) is an inflammatory cytokine, involved in both physiological and pathological pathways. Although there have been various attempts to express and purify human TNF-α, the current work introduces a simple, rapid, and efficient method for its production without loss of biological activity. The protein was expressed based on GST-tagged fusion system in Escherichia coli under optimized condition. The expressed GST fusion protein was applied to glutathione affinity column and then, TNF-α was cleaved off the GST using thrombin protease. The purity of the product was more than 95% and further size exclusion chromatography slightly improved the purity. The purified human TNF-α was tested for its biological activity and structural analysis, using MTT assay (EC(50) of 4.1 ×10E-12 M in L929 cell death assay) and circular dichroism spectropolarimetry, respectively. The results showed that the method used in this study enables successful production of highly purified and fully functional TNF-α.

Analysis of TNF-α (-308) polymorphism and gingival crevicular fluid TNF-α levels in aggressive and chronic periodontitis: A preliminary report.

OBJECTIVES: The purpose of this study was to determine the differences in the distribution of TNF-α (-308) gene polymorphism among aggressive periodontitis, chronic periodontitis and periodontally healthy individuals and also to investigate whether this polymorphism is associated with gingival crevicular fluid TNF-α levels and periodontal disease severity. MATERIAL AND METHODS: A total of 93 individuals were enrolled in the study including 38 aggressive periodontitis, 29 chronic periodontitis patients, and 26 healthy controls. Single nucleotide polymorphism at TNF-α (-308) is analyzed by PCR-RFLP method. Gingival crevicular fluid samples were analyzed for TNF-α, using ELISA. RESULTS: The distribution of genotypes and allele frequencies for TNF-α (-308) were similar among the groups. After stratification of patients with respect to attachment level, aggressive periodontitis patients with clinical attachment level ⩾4mm was observed to have a higher frequency of TNF-α (-308) allele 2 compared to the chronic periodontitis patients with clinical attachment level ⩾4mm. No significant differences were found between the TNF-α levels of the different genotypes in spite of an insignificant increase in patient groups carrying TNF-α (-308) allele 2. CONCLUSION: The results of this study revealed an association between TNF-α (-308) allele 2 frequency and aggressive periodontitis patients with clinical attachment level ⩾4mm in the population studied.

TNF-α depuration is a predictor of mortality in critically ill patients under continuous veno-venous hemodiafiltration treatment.

INTRODUCTION: Critically ill patients with acute kidney injury (AKI) present high mortality rates. The magnitude of inflammatory response could determine the prognosis of such patients. Continuous renal replacement therapy (CRRT) may play an important role in removing inflammatory mediators in patients with AKI. AIM: To investigate whether the magnitude of inflammatory mediator's removal is associated with mortality among critically ill patients on CVVHDF, a CRRT modality. METHODS: This study consisted of 64 critically ill patients requiring CVVHDF. Plasma levels of C3a, TNF-α, IL-10, IL-6, IL-1ß, sTNFRI and sTNFRII were determined by enzyme-linked immunosorbent assay (ELISA) at the beginning of CVVHDF and after 24h (outlet). Clearance of cytokines during the first 24h of CVVHDF was calculated. Clinical and laboratory data were acquired from patient's records data. RESULTS: Mean age of patients requiring CVVHDF was 63years, 67.2% were men and 87.3% were Caucasian. Thirty-five (35) patients (54.7%) died. Comparing non-survivors with the group of survivors we observed higher incidence of sepsis (68.6 versus 37.9%, p<0.05), higher APACHE II score (34.8±7.6 versus 29.2±7.1, p<0.05) and higher lactate levels (23.2±17.6 versus 16.4±6.6, p<0.05). According to the inter-tertile range of TNF-α clearance (ITR1 (<0.54); ITR2 (0.54-2.93); ITR3 (>2.93)) we found that those patients with higher TNF-α removal by RRT (ITR3) had a better survival. Multivariable analysis showed that lower clearance of TNF-α remained independently associated with high mortality after adjustment for sex, age, use of vasoactive drugs, APACHE II score sepsis, creatinine and lactate before CVVHDF (HR: 0.179, 95% IC: 0.049-0.661, p<0.01). CONCLUSION: The attenuation of inflammatory response may be related to the lower mortality observed on those patients with higher TNF-α removal by CVVHDF.

Characterization of Adsorbents for Cytokine Removal from Blood in an In Vitro Model.

INTRODUCTION: Cytokines are basic targets that have to be removed effectively in order to improve the patient's health status in treating severe inflammation, sepsis, and septic shock. Although there are different adsorbents commercially available, the success of their clinical use is limited. Here, we tested different adsorbents for their effective removal of cytokines from plasma and the resulting effect on endothelial cell activation. METHODS: The three polystyrene divinylbenzene (PS-DVB) based adsorbents Amberchrom CG161c and CG300m and a clinically approved haemoperfusion adsorbent (HAC) were studied with regard to cytokine removal in human blood. To induce cytokine release from leucocytes, human blood cells were stimulated with 1 ng/ml LPS for 4 hours. Plasma was separated and adsorption experiments in a dynamic model were performed. The effect of cytokine removal on endothelial cell activation was evaluated using a HUVEC-based cell culture model. The beneficial outcome was assessed by measuring ICAM-1, E-selectin, and secreted cytokines IL-8 and IL-6. Additionally the threshold concentration for HUVEC activation by TNF-α and IL-1ß was determined using this cell culture model. RESULTS: CG161c showed promising results in removing the investigated cytokines. Due to its pore size the adsorbent efficiently removed the key factor TNF-α, outperforming the commercially available adsorbents. The CG161c treatment reduced cytokine secretion and expression of cell adhesion molecules by HUVEC which underlines the importance of effective removal of TNF-α in inflammatory diseases. CONCLUSION: These results confirm the hypothesis that cytokine removal from the blood should approach physiological levels in order to reduce endothelial cell activation.

Integration of binding peptide selection and multifunctional particles as tool-box for capture of soluble proteins in serum.

In this paper, we report on a general approach for the detection of a specific tumoural biomarker directly in serum. Such detection is made possible using a protein-binding peptide selected through an improved phage display technique and then conjugated to engineered microparticles (MPs). Protein biomarkers represent an unlimited source of information for non-invasive diagnostic and prognostic tests; MP-based assays are becoming largely used in manipulation of soluble biomarkers, but their direct use in serum is hampered by the complex biomolecular environment. Our technique overcomes the current limitations as it produces a selective MP--engineered with an antifouling layer--that 'captures' the relevant protein staying impervious to the background. Our system succeeds in fishing-out the human tumour necrosis factor alpha directly in serum with a high selectivity degree. Our method could have great impact in soluble protein manipulation and detection for a wide variety of diagnostic applications.