Analysis of IL-6 and IL-1β release in cryopreserved pooled human whole blood stimulated with endotoxin

A novel alternative for pyrogen detection based on a transgenic cell line

Pyrogen, often as a contaminant, is a key indicator affecting the safety of almost all parenteral drugs (including biologicals, chemicals, traditional Chinese medicines and medical devices). It has become a goal to completely replace the in vivo rabbit pyrogen test by using the in vitro pyrogen test based on the promoted 'reduction, replacement and refinement' principle, which has been highly considered by regulatory agencies from different countries. We used NF-κB, a central signalling molecule mediating inflammatory responses, as a pyrogenic marker and the monocyte line THP-1 transfected with a luciferase reporter gene regulated by NF-κB as an in vitro model to detect pyrogens by measuring the intensity of a fluorescence signal. Here, we show that this test can quantitatively and sensitively detect endotoxin (lipopolysaccharide from different strains) and nonendotoxin (lipoteichoic acid, zymosan, peptidoglycan, lectin and glucan), has good stability in terms of NF-κB activity and cell phenotypes at 39 cell passages and can be applied to detect pyrogens in biologicals (group A & C meningococcal polysaccharide vaccine; basiliximab; rabies vaccine (Vero cells) for human use, freeze-dried; Japanese encephalitis vaccine (Vero cells), inactivated; insulin aspart injection; human albumin; recombinant human erythropoietin injection (CHO Cell)). The within-laboratory reproducibility of the test in three independent laboratories was 85%, 80% and 80% and the interlaboratory reproducibility among laboratories was 83.3%, 95.6% and 86.7%. The sensitivity (true positive rate) and specificity (true negative rate) of the test were 89.9% and 90.9%, respectively. In summary, the test provides a novel alternative for pyrogen detection.

The future of pyrogenicity testing: Phasing out the rabbit pyrogen test. A meeting report

The rabbit pyrogen test (RPT) was the benchmark for pyrogenicity testing, but scientific advancements have provided innovative and humane methods, such as the in vitro monocyte-activation test (MAT). However, transitioning from the RPT to the MAT has been challenging. The European Directorate for the Quality of Medicines & HealthCare, the Council of Europe, and the European Partnership for Alternative Approaches to Animal Testing jointly hosted an international conference entitled "The future of pyrogenicity testing: phasing out the rabbit pyrogen test". The conference aimed to show how the European Pharmacopoeia intends to remove the RPT from its texts by 2026, facilitate the use of MAT, and identify gaps in the suppression of RPT. The events contributed to a better understanding of the barriers to RPT replacement and acceptance of in vitro alternatives. Participants comprised stakeholders from Asia, Europe, and North America, including vaccine developers, contract laboratories, and regulators. Participants shared their replacement strategies and experiences with MAT implementation. They emphasised the need for continued cooperation between stakeholders and stressed the importance of international harmonisation of regulatory requirements to help accelerate MAT acceptance outside Europe. Despite the challenges, the willingness to eliminate the unnecessary use of RPT was common across all participants.

Simple and fast colorimetric detection of lipopolysaccharide based on aptamer and SYBR Green I mediated aggregation of gold nanoparticles

Lipopolysaccharide (LPS) poses a considerable threat to food safety and human health. A colorimetric assay for LPS detection based on LPS binding aptamer (LBA) and SYBR Green I (SG) mediated aggregation of gold nanoparticles (AuNPs) was established. In the absence of LPS, the LBA was absorbed onto the AuNPs surface which prevented SG-induced aggregation of AuNPs, and the sensing system exhibited red color. When LPS was added, it interacted with the LBA, forming a complex. At higher LPS concentration, many LBAs were exhausted resulting in SG-induced aggregation of AuNPs, and color change from red to blue. The range of colorimetric detection of LPS was linear in 0-12 EU/mL, with a limit of detection of 0.1698 EU/mL. Spiked LPS in real samples and interfering substances were also identified. This assay ingeniously using the fluorescent dye SG as an effective trigger of AuNPs aggregation, is rapid and facile than most of those earlier reported LBA-based LPS assays, and there is potential to be modified to construct assays for other targets.

An Immunomodulatory Peptide Dendrimer Inspired from Glatiramer Acetate

Glatiramer acetate (GA) is a random polypeptide drug used to treat multiple sclerosis (MS), a chronic autoimmune disease. With the aim of identifying a precisely defined alternative to GA, we synthesized a library of peptide dendrimers with an amino acid composition similar to GA. We then challenged the dendrimers to trigger the release of the anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1Ra) from human monocytes, which is one of the effects of GA on immune cells. Several of the largest dendrimers tested were as active as GA. Detailed profiling of the best hit showed that this dendrimer induces the differentiation of monocytes towards an M2 (anti-inflammatory) state as GA does, however with a distinct immune marker profile. Our peptide dendrimer might serve as starting point to develop a well-defined immunomodulatory analog of GA.

Applicability of Monocyte Activation Test for Pyrogen Detection in Succinylated Gelatin Injection

Background::

Pyrogens are fever-inducing substances and pyrogen detection is mandatory in parenteral pharmaceuticals. Succinylated Gelatin Injection (SGI) is a biopharmaceutical product, containing multi-component, and it is administered parenterally.

Objective:

The study aimed to assess pyrogen in SGI and to evaluate the feasibility of the Monocyte Activation Test (MAT) for pyrogen detection in a multi-component pharmaceutical product.

Method:

In the present study, the Bacterial Endotoxin Test (BET) and the Monocyte Activation Test (MAT) were employed to assess pyrogen in SGI. The MAT method was developed on the basis of the HL-60/IL-6 assay. HL-60 cells were incubated with lipopolysaccharide (LPS) standards and sample solutions. The endotoxin produced by the incubation, interleukin-6 (IL-6), was measured by ELISA. The MAT method was validated and main parameters were investigated. Finally, the pyrogenicity of SGIs from two different enterprises was determined by the developed MAT method.

Results:

The BET failed in the test for interfering factors and the MAT was proved suitable for the pyrogen detection of SGI. All the products examined showed negative results in the pyrogen detection test.

Conclusion:

The MAT method is feasible in pyrogen detection of SGI. It can be applied in pyrogen detection for quality and safety control of multi-component biological products.

A Novel Reporter Gene Assay for Pyrogen Detection

Fever is a systemic inflammatory response of the body to pyrogens. Nuclear factor κB (NF-κB) is a central signaling molecule that causes the excessive secretion of various pyrogen-induced pro-inflammatory factors. This study explored the feasibility of a novel reporter gene assay (RGA) for pyrogen detection using RAW264.7 cells stably transfected with the NF-κB reporter gene as a pyrogenic marker. The RGA could detect different types of pyrogens, including the lipopolysaccharide of gram-negative bacteria, the lipoteichoic acid of gram-positive bacteria, and the zymosan of fungi, and a good dose-effect relationship was observed in terms of NF-κB activity. The limits of detection of the RGA to those pyrogens were 0.03 EU/ml, 0.001 μg/ml, and 1 μg/ml, respectively. The method had good precision and accuracy and could be applied to many molecules (e.g., nivolumab, rituximab, bevacizumab, etanercept, basiliximab, Haemophilus influenzae type b conjugate vaccine, 23-valent pneumococcal polysaccharide vaccine, group A and group C meningococcal conjugate vaccine, diphtheria, tetanus, pertussis [acellular, component], poliomyelitis [inactivated] vaccine, and imject alum adjuvant). The results of this study suggest that the novel RGA has a wide pyrogen detection spectrum and is sufficiently sensitive, stable, and accurate for various applications.

Highly Sensitive Endotoxin Assay Combining Peptide/Graphene Oxide and DNA-Modified Gold Nanoparticles

Endotoxin is a highly toxic stimulator originated from the outer membrane of Gram-negative bacteria, which should be monitored sensitively and selectively for human health concerns. Traditional detection methods mainly rely on limulus amoebocyte lysate assay. However, it suffers drawbacks like the narrow detection range, and the results may be environment-dependent. In this work, we have developed a sensitive electrochemical biosensor for endotoxin assay. Peptide is first designed as specific recognition element toward endotoxin. Graphene oxide and DNA-modified gold nanoparticles are then used to enhance the electrochemical signal. The analytical performances are excellent with the limit of detection as low as 0.001 EU mL^-1. This method has also been successfully applied in endotoxin assay in complex biological samples, which may have great potential use.