Tuftsin derivatives of FITC, Tb–DOTA or Gd–DOTA as potential macrophage‐specific imaging biomarkers

Abstract

Fluorescein- and terbium-labelled tuftsin (Thr-Lys-Pro-Arg) and pentapeptide (Thr-Lys-Pro-Pro-Arg) were synthesized and their properties were evaluated in vitro by luminescence spectrometry and confocal microscopy as fluorescence probes to target macrophage cells in biological systems. An increase in fluorescence of macrophages incubated with varying concentrations of fluorescein isothiocyanate or Tb-DOTA-tuftsin/pentapeptide conjugates was observed in a concentration-dependent manner. Tb-DOTA-pentapeptide had a greater affinity to macrophages than Tb-DOTA-tuftsin. Lipopolysaccharide (LPS) stimulation strengthened the internalization of peptide conjugates by macrophages through the tuftsin receptor mechanism. Tb-DOTA-tuftsin/pentapeptide conjugates are likely to be a promising optical reagents as probes of the immune response with involvement of macrophage cells in a variety of diseases. Gd-DOTA-tuftsin conjugate was also evaluated as a cell-specific contrast agent in in vitro MRI experiments. In this context, the macrophages labelled by Gd-DOTA-tuftsin were highly magnetic and detectable by MRI, which confirms that this vectorized MRI probe has the potential to image macrophage-mediated inflammation in diseases like brain traumas and stroke. Tuftsin receptor-specific biological-function domain may have a modified in vivo biodistribution profile, bioavailability and pharmacokinetics subsequent to its conjugation to a metal ion-binding backbone.

Sensitive protein detection and visualization using protein‐binding peptides

“…This method also had high specificity to distinguish the target miRNA and mismatched sequence. FITC is often used as a fluorescent label for morphological observation by fluorescence imaging (Feng et al, 2010;Tang et al, 2018;Yeo, Kim, Choi, & Pack, 2016). Moreover, Sert et al used FITC for fluorescence imaging of Toxoplasma Gondii (Sert, Koc, & Kilinc, 2017).…”

Enhanced Cellular Uptake of a New, in Silico Identified Antitubercular Candidate by Peptide Conjugation

“…20−22 Recently, the relevance of tuftsin conjugates as macrophage specific imaging biomarkers was also demonstrated. 23,24 Tuftsin is a natural phagocytosis stimulating peptide produced by enzymatic cleavage of the Fc-domain of the heavy chain of immunoglobulin G. Binding of tuftsin to its receptor causes macrophage activation. An activated macrophage has the ability to enhance phagocytosis and lysis of intracellular parasites.…”

“… , More efficient inhibition of M. tuberculosis from infected phagocytes would be based on the internalization through receptors which are expressed mainly on macrophages. On the basis of the literature, the tuftsin receptor is used for targeted drug delivery. − Recently, the relevance of tuftsin conjugates as macrophage specific imaging biomarkers was also demonstrated. , Tuftsin is a natural phagocytosis stimulating peptide produced by enzymatic cleavage of the Fc-domain of the heavy chain of immunoglobulin G. Binding of tuftsin to its receptor causes macrophage activation. An activated macrophage has the ability to enhance phagocytosis and lysis of intracellular parasites .…”