Ozaki, M. | Search bioRxiv

bioRxiv2026

Antiglycation effects of imidazole dipeptides and 2-oxo-imidazole dipeptides on glyceraldehyde-induced intracellular protein glycation and neuronal cell death

Glyceraldehyde (GA) contributes to the development of various diseases, such as diabetes and Alzheimers disease via protein glycation and the formation of advanced glycation end products (AGEs); however, effective strategies for neutralizing GA are limited. Carnosine (Car), an imidazole dipeptide (IDP) that is abundant in meat, suppresses protein glycation by scavenging reactive aldehydes. There are only a few reports on the antiglycation activity of Car against GA. For other IDPs, such as anserine, balenine (Bal), and homocarnosine, there are almost no reports on their antiglycation activity. In this study, we demonstrated the antiglycation activity of four types of IDPs and 2-oxocarnosine (2-oxo-Car), an oxidized form of Car, against GA-induced intracellular protein glycation and neuronal cytotoxicity. Car and Bal exhibited significantly higher reactivity with GA compared with other IDPs and 2-oxo-Car. An in silico analysis suggested that the difference in reactivity is dependent upon intramolecular hydrogen bond formation and the conformation of each IDP. Although there were differences in reactivity with GA, LC-MS analysis revealed that all of the IDPs and 2-oxo-Car reacted with two molecules of GA to form adducts containing pyridinium rings. Car and Bal exhibited high reactivity with GA and markedly suppressed GA-induced cytotoxicity in SH-SY5Y cells. Western blot and qPCR analyses revealed that IDPs suppressed GA-induced protein glycation and the upregulation of endoplasmic reticulum and oxidative stress response genes. Our results indicate that IDPs represent a novel preventive approach to AGE-related diseases and provide a foundation for the development of strategies to treat GA-related neurotoxicity. Graphical abstractCarnosine and balenine, which are imidazole dipeptides (IDPs), scavenged two molecules of glyceraldehyde to form adducts containing pyridinium rings and suppressed intracellular protein glycation and neuronal cell death. The formation of intramolecular hydrogen bond of IDPs played a crucial role in the strength of antiglycation activity. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=126 SRC="FIGDIR/small/734660v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@11d82dorg.highwire.dtl.DTLVardef@187aff0org.highwire.dtl.DTLVardef@12fe482org.highwire.dtl.DTLVardef@14327ee_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2019

Platelet Thrombus Formation in eHUS is Prevented by Anti-MBL2

Epidemic Hemolytic Uremic Syndrome (eHUS) caused by Shiga toxin-producing bacteria is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and acute kidney injury that cause acute renal failure in up to 65% of affected patients. We hypothesized that the mannose-binding lectin (MBL) pathway of complement activation plays an important role in human eHUS, as we previously demonstrated that injection of Shiga Toxin-2 (Stx-2) led to fibrin deposition in mouse glomeruli that was blocked by co-injection of the anti-MBL-2 antibody 3F8. However, the markers of platelet thrombosis in affected mouse glomeruli were not delineated. To investigate the effect of 3F8 on markers of platelet thrombosis, we used kidney sections from our mouse model (MBL-2+/+ Mbl-A/C-/-; MBL2 KI mouse). Mice in the control group received PBS, while mice in a second group received Stx-2, and those in a third group received 3F8 and Stx-2. Using double immunofluorescence (IF) followed by digital image analysis, kidney sections were stained for fibrin(ogen) and CD41 (marker for platelets), von-Willebrand factor (marker for endothelial cells and platelets), and podocin (marker for podocytes). Electron microscopy (EM) was performed on ultrathin sections from mice and human with HUS. Injection of Stx-2 resulted in an increase of both fibrin and platelets in glomeruli, while administration of 3F8 with Stx-2 reduced both platelet and fibrin to control levels. EM studies confirmed that CD41-positive objects observed by IF were platelets. The increases in platelet number and fibrin levels by injection of Stx-2 are consistent with the generation of platelet-fibrin thrombi that were prevented by 3F8.

pathology↗