Tumor Necrosis Factor-α Trimer Disassembly and Inactivation via Peptide-Small Molecule Synergy

Serotonin: A new super effective functional monomer for molecular imprinting. The case of TNF-α detection in real matrix by Surface Plasmon Resonance

Molecular imprinting and related technologies are becoming increasingly appreciated in bioanalysis and diagnostic applications. Among the imprinted polymers, we have already demonstrated that the endogenous neurotransmitters (NTs) dopamine (DA) and norepinephrine (NE) can be efficiently used as natural and sustainable monomers to straightforwardly design and synthesize a new generation of green and "soft" Molecularly Imprinted BioPolymers (MIBPs). Here, we demonstrated for the first time the ability of a further NT, i.e., serotonin (SE), in forming adhesive imprinted nanofilms coupled to label-free optical biosensing. Its imprinting efficiency is compared with those obtained with PDA and PNE. As a model study, tumor necrosis factor-alpha (TNF-α) was selected as a biomolecular target of interest in clinical diagnostics. The biomimetic receptor was coupled to Surface Plasmon Resonance (SPR), and TNF-α detection was performed in label-free and real-time manner both in buffer and biological matrices, i.e. synovial fluid and human serum. The results indicate that, under the same imprinting and binding conditions, the analytical performances of PSE are impressively superior to those of PDA and PNE. The PSE-based MIBP was able to detect TNF-α in human matrices with a good sensitivity, selectivity, and repeatability.

Small-molecule modulators of tumor necrosis factor signaling

Tumor necrosis factor (TNF) is a pleiotropic cytokine with a major role in immune system homeostasis and is involved in many inflammatory and autoimmune diseases, such as rheumatoid arthritis (RA), psoriasis, Alzheimer's disease (AD), and multiple sclerosis (MS). Thus, TNF and its receptors, TNFR1 and TNFR2, are relevant pharmacological targets. Biologics have been developed to block TNF-dependent signaling cascades, but they display serious side effects, and their pharmacological effectiveness decreases over time because of their immunogenicity. In this review, we present recent discoveries in small molecules targeting TNF and its receptors and discuss alternative strategies for modulating TNF signaling. Teaser: This review presents several recent and innovative strategies for the modulation of tumor necrosis factor function, with a focus on small molecules.

Trimer-to-Monomer Disruption Mechanism for a Potent, Protease-Resistant Antagonist of Tumor Necrosis Factor-α Signaling

Aberrant tumor necrosis factor-α (TNFα) signaling is associated with many inflammatory diseases. The homotrimeric quaternary structure of TNFα is essential for receptor recognition and signal transduction. Previously, we described an engineered α/β-peptide inhibitor that potently suppresses TNFα activity and resists proteolysis. Here, we present structural evidence that both the α/β-peptide inhibitor and an all-α analogue bind to a monomeric form of TNFα. Calorimetry data support a 1:1 inhibitor/TNFα stoichiometry in solution. In contrast, previous cocrystal structures involving peptide or small-molecule inhibitors have shown the antagonists engaging a TNFα dimer. The structural data reveal why our inhibitors favor monomeric TNFα. Previous efforts to block TNFα-induced cell death with peptide inhibitors revealed that surfactant additives to the assay conditions cause a more rapid manifestation of inhibitory activity than is observed in the absence of additives. We attributed this effect to a loose surfactant TNFα association that lowers the barrier to trimer dissociation. Here, we used the new structural data to design peptide inhibitors bearing a surfactant-inspired appendage intended to facilitate TNFα trimer dissociation. The appendage modified the time course of protection from cell death.

Small molecule approaches to treat autoimmune and inflammatory diseases (Part III): Targeting cytokines and cytokine receptor complexes

Chronic and dysregulated cytokine signaling plays an important role in the pathogenic development of many autoimmune and inflammatory diseases. Despite intrinsic challenges in the disruption of interactions between cytokines and cytokine receptors, many first-in-class small-molecule inhibitors have been discovered over the past few years. The third part of the digest series presents recent progress in identifying such inhibitors and highlights the application of novel research tools in the fields of structural biology, computational analysis, screening methods, biophysical/biochemical assays and medicinal chemistry strategy.

In vitro display evolution of the PURE system-expressed TNFα-binding unnatural cyclic peptide containing an N-methyl-d-amino acid

Tumor necrosis factor-alpha (TNFα) is a multifunctional cytokine associated with inflammation, immune responses, and autoimmune diseases including rheumatoid arthritis, inflammatory bowel disease, and psoriasis. In the present study, we performed in vitro selection, systematic evolution of ligands by exponential enrichment (SELEX) against human TNFα from mRNA-displayed peptide library prepared with Escherichia coli-reconstituted cell-free transcription/translation system (PURE system) and cyclized by N-chloroacetyl-N-methyl-d-phenylalanine incorporated by genetic code expansion (sense suppression). We identified a novel TNFα-binding thioether-cyclized peptide that contains an N-methyl-d-phenylalanine. Since cyclic structure and presence of an N-methyl-d-amino acid can increase proteolytic stability, the TNFα binding peptide has potential to be used for therapeutic, research and diagnostic applications.