Synthetic Polyclonal-Derived CDR Peptides as an Innovative Strategy in Glaucoma Therapy

Abstract

The pathogenesis of glaucoma is strongly associated with the occurrence of autoimmune-mediated loss of retinal ganglion cells (RGCs) and additionally, recent evidence shows that specific antibody-derived signature peptides are significantly differentially expressed in sera of primary-open angle glaucoma patients (POAG) compared to healthy controls. Synthetically antibody-derived peptides can modulate various effector functions of the immune system and act as antimicrobial or antiviral molecules. In an ex vivo adolescent glaucoma model, this study, for the first time, demonstrates that polyclonal-derived complementarity-determining regions (CDRs) can significantly increase the survival rate of RGCs (p = 0.013). We subsequently performed affinity capture experiments that verified the mitochondrial serine protease HTRA2 (gene name: HTRA2) as a high-affinity retinal epitope target of CDR1 sequence motif ASGYTFTNYGLSWVR. Quantitative proteomic analysis of the CDR-treated retinal explants revealed increased expression of various anti-apoptotic and anti-oxidative proteins (e.g., VDAC2 and TXN) compared to untreated controls (p < 0.05) as well as decreased expression levels of cellular stress response markers (e.g., HSPE1 and HSP90AA1). Mitochondrial dysfunction, the protein ubiquitination pathway and oxidative phosphorylation were annotated as the most significantly affected signaling pathways and possibly can be traced back to the CDR-induced inhibition or modulation of the master regulator HTRA2. These findings emphasize the great potential of synthetic polyclonal-derived CDR peptides as therapeutic agents in future glaucoma therapy and provide an excellent basis for affinity-based biomarker discovery purposes.

Regulation of the HTRA2 Protease Activity by an Inhibitory Antibody-Derived Peptide Ligand and the Influence on HTRA2-Specific Protein Interaction Networks in Retinal Tissues

“…However, in a recent study of our group we identified the protein HTRA2 as a high-affinity interaction partner of the synthetic peptide ASGYTFTNYGLSWVR [ 16 ]. Thereby, this synthetic peptide encodes a complementary-determining region 1 (CDR1) of polyclonal antibody molecules, which was originally identified as a potential biomarker candidate in primary-open angle glaucoma (POAG) patients [ 17 ].…”

“…Thereby, this synthetic peptide encodes a complementary-determining region 1 (CDR1) of polyclonal antibody molecules, which was originally identified as a potential biomarker candidate in primary-open angle glaucoma (POAG) patients [ 17 ]. Furthermore, the synthetic CDR1 peptide ASGYTFTNYGLSWVR induced neuroprotective effects on retinal ganglion cells (RGCs) in an organ culture model for glaucoma, and was also accompanied by specific proteomic changes in the CDR1-treated retinal explants [ 16 ]. These important findings lead to the assumption that HTRA2 might represent a key player in neurodegenerative diseases such as glaucoma, and may serve as a potential therapeutic target in the future.…”

Aqueous Fibronectin Correlates With Severity of Macular Edema and Visual Acuity in Patients With Branch Retinal Vein Occlusion: A Proteome Study

“…11 Large-scale protein analyses are effectively performed with mass spectrometry-based proteomic techniques, which aim at identifying and quantifying the entire set of proteins in a given tissue or body fluid. [12][13][14][15][16] Proteome studies of aqueous humor may bring valuable insights into molecular changes following BRVO. 11,17 However, the human aqueous proteome of BRVO remains largely unstudied with mass spectrometry except for a study on aqueous humor from six BRVO patients, which was published by Yao et al 18 in 2013.…”

“…With major advances in recent years, proteomic techniques allow for in-depth protein analysis that may elucidate molecular mechanisms underlying ocular diseases. [11][12][13][14][15][16][17] In…”

Age related retinal Ganglion cell susceptibility in context of autophagy deficiency

“…In gel tryptic digestion was performed as described in detail previously and SOLAµ TM HRP Spin plates were used for peptide purification prior to LC-MS/ MS analysis with a Rheos Allegro Pump downscaling to a capillary HPLC system and coupled to a hybrid linear ion trap-Orbitrap MS system (LTQ Orbitrap XL; Thermo Fischer Scientific, Rockfeld, IL USA). Elution gradient of the HPLC and MS-specific parameters are described elsewhere in detail 38 . Parameters used for elution gradient and MS parameters were applied as described previously 39,40 .…”