Synthetic Peptides to Pave Way for Diagnostic Tests to Detect Inflammatory Diseases

By LabMedica International staff writers
Posted on 24 May 2023

Image: Lateral flow assay detecting calprotectin in blood sample (Photo courtesy of BÜHLMANN & EPFL)

Common inflammatory disorders such as Crohn's disease and ulcerative colitis can be diagnosed or monitored by evaluating the protein calprotectin in fecal specimens, while serum levels of calprotectin can provide insight into inflammation status in rheumatoid arthritis. Calprotectin levels in patient samples are usually measured using antibodies that latch onto and identify the protein, such as in lateral flow assays. However, antibody-based calprotectin assays present a challenge: the outcomes can vary based on the type of antibody and test employed. This inconsistency arises because antibodies might attach to different sites on the protein or lack a uniform composition. Additionally, antibodies can become inactivated over time due to unfolding or precipitation.

A viable alternative could be employing peptides instead of antibodies to identify and quantify disease indicators like calprotectin. Peptides are sequences of up to 50 amino acids capable of binding to proteins with high specificity and affinity. Unlike antibodies, they can be synthetically produced with high purity and uniformity. Additionally, peptides are stable over time, cost less to produce, have lower inter-batch variability, and can be fixed to a specific location on a surface, simplifying the development of diagnostic assays by enabling a more precise and controlled method for biomarker detection. The use of synthetic peptides for detecting disease markers is highly promising as they are more accurate, reliable, and cost-effective than the commonly used antibodies in diagnostic tests.

BÜHLMANN Laboratories AG (Schönenbuch, Switzerland), in collaboration with a group of scientists at EPFL (Lausanne, Switzerland), has created a peptide that binds to the protein calprotectin, a key marker for major inflammatory disorders, demonstrating its suitability for diagnostic tests. From a library of over 500 billion different peptides, the researchers isolated several calprotectin binders and demonstrated their effectiveness for calprotectin quantification in simplified lateral flow assays. The top-performing peptide showed a dissociation constant of 26 nM, indicating its strong bond with calprotectin, making it a potential candidate for diagnostic tests.

The peptide developed binds not only to a large surface area of calprotectin but also to a specific form of calprotectin that is the relevant species in patient samples. The peptide was also tested in professionally assembled lateral flow cassettes and was found to be suitable for the accurate detection and quantification of calprotectin. In a proof-of-concept study, researchers used this setup to quantify calprotectin concentration in blood serum derived from patient samples. The peptide developed marks the first synthetic affinity agent that could be produced against the biomarker calprotectin.

“The EPFL and BÜHLMANN teams are currently performing more tests with the calprotectin-specific peptide to translate the assay into a product that can bring the diagnostic power of this increasingly important biomarker to a new level to help patients suffering from inflammatory diseases,” said Professor Christian Heinis at EPFL

“This collaboration greatly benefited from BÜHLMANN's knowhow to produce and handle the biomarker, and expertise of the EPFL team to generate and screen large combinatorial libraries of peptides by phage display,” added Christian Gerhold, CTO of BÜHLMANN.

Related Links:
BÜHLMANN Laboratories AG
EPFL