Identification of a Novel Carbohydrate-Mimicking Octapeptide from Chemical Peptide Library and Characterization as Selectin Inhibitor

Abstract

Selectins are a family of integral membrane glycoproteins that mediate adhesion between leukocytes and endothelial cells during the transient rolling phase of leukocyte migration.1-3) The selectin family consists of three glycoprotein members: E-, P-and L-selectins. E-and P-selectins are expressed on activated endothelium, whereas L-selectin is constitutively expressed on neutrophils, monocytes, and most lymphocytes. P-selectin mediates attachment and is translocated to the surface of the endothelium within minutes of activation. E-selectin mediates slow rolling and is expressed after several hours on the activated cell surface. 4,5) Each selectin has a calcium-dependent carbohydrate binding domain (C-type lectin domain) in its amino-terminal, followed by an epidermal growth factor-like domain, variable numbers of complement regulatory-like units, a transmembrane domain and an intracellular region. The adhesion activity of the selectins is mediated primarily by the binding of sialyl Lewis X (sLe X ) (NeuAca2→3Galb1→4(Fuca1→3)GlcNAc-R, Fig. 1) on the leukocyte to the carbohydrate-binding domain on activated endothelial cells. [6][7][8][9][10][11] In a productive immune response, this leads to isolation of infection; however, overzealous transfer of leukocytes causes widespread tissue damage, leading to several disease states, such as reperfusion injury, cardiovascular diseases, and allergic diseases.5) Inhibition of selectin-mediated rolling is a possible means of controlling inflammation-induced diseases. Therefore, the development of selectin inhibitors, which are able to control the leukocyte-endothelia cell adhesion process, is an excellent therapeutic target to treat inflammatory diseases.It is well known that all selectins recognize the carbohydrate structure of sLe X and sialyl Lewis a (sLe a ), an isomer of sLe X ; therefore, most reported selectin inhibitors are carbohydrate-based molecules mimicking sLe X or sLe a and antibodies.5,12-20) However, they have drawbacks as therapeutics, i.e., carbohydrate chains are difficult to synthesize in high yield and purity, and carbohydrate-based molecules are generally prone to rapid metabolism and elimination. On the other hand, antibodies have potential immunogenicity, high cost, and other possible side effects.The phage-displayed library is a representative method based on affinity binding between the displayed library and the target molecule or tissue. Recently, cloning of carbohydrate mimetic peptides within a short term has become available by the phage-displayed peptide library method. Several peptides mimicking carbohydrate have been found using phage-displayed libraries. [21][22][23][24][25][26] O et al. also identified the dodecapeptide (DLWDWVVGKPAG) mimicking sLe a by screening a phage-displayed library using monoclonal antibody NS19-9. 27)Generally, the synthesis of a long peptide in high yield and purity is difficult, and long or large peptides have relatively high antigenicity. Thus, short peptides are necessary to overcome the therapeutic drawbacks....

Endothelial Cell Adhesion Molecules- (un)Attainable Targets for Nanomedicines

“…Esbp-modified bovine serum albumin (BSA) nanoparticles or Esbp-hyaluronic acid-paclitaxel (Esbp-HA-PTX) micelles were used by other groups to target DEX or PTX to acute lung injury or to inhibit breast cancer metastasis, respectively ( 88 , 89 ). Other sequences such as IELLQAR (shown to bind to E-selectin and with much lower affinity to P- and L-selectin) ( 90 – 92 ), YRNWFGRW and YRNWDGRW ( 93 ) have been proposed as well for selective targeting of E-selectin. Interestingly, a study by Fernandes et al directly compared all of these peptides for their ability to bind E-selectin.…”