bims-mideyd 2023-04-30 papers

Issue of 2023‒04‒30
four papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Molecules. 2023 Apr 09. pii: 3324. [Epub ahead of print]28(8):

Carnosine Counteracts the Molecular Alterations Aβ Oligomers-Induced in Human Retinal Pigment Epithelial Cells.

Giuseppe Caruso, Claudia G Fresta, Annamaria Fidilio, Francesca Lazzara, Nicolò Musso, Vincenzo Cardaci, Filippo Drago, Filippo Caraci, Claudio Bucolo.

Age-related macular degeneration (AMD) has been described as a progressive eye disease characterized by irreversible impairment of central vision, and unfortunately, an effective treatment is still not available. It is well-known that amyloid-beta (Aβ) peptide is one of the major culprits in causing neurodegeneration in Alzheimer's disease (AD). The extracellular accumulation of this peptide has also been found in drusen which lies under the retinal pigment epithelium (RPE) and represents one of the early signs of AMD pathology. Aβ aggregates, especially in the form of oligomers, are able to induce pro-oxidant (oxidative stress) and pro-inflammatory phenomena in RPE cells. ARPE-19 is a spontaneously arising human RPE cell line validated for drug discovery processes in AMD. In the present study, we employed ARPE-19 treated with Aβ oligomers, representing an in vitro model of AMD. We used a combination of methods, including ATPlite, quantitative real-time PCR, immunocytochemistry, as well as a fluorescent probe for reactive oxygen species to investigate the molecular alterations induced by Aβ oligomers. In particular, we found that Aβ exposure decreased the cell viability of ARPE-19 cells which was paralleled by increased inflammation (increased expression of pro-inflammatory mediators) and oxidative stress (increased expression of NADPH oxidase and ROS production) along with the destruction of ZO-1 tight junction protein. Once the damage was clarified, we investigated the therapeutic potential of carnosine, an endogenous dipeptide that is known to be reduced in AMD patients. Our findings demonstrate that carnosine was able to counteract most of the molecular alterations induced by the challenge of ARPE-19 with Aβ oligomers. These new findings obtained with ARPE-19 cells challenged with Aβ1-42 oligomers, along with the well-demonstrated multimodal mechanism of action of carnosine both in vitro and in vivo, able to prevent and/or counteract the dysfunctions elicited by Aβ oligomers, substantiate the neuroprotective potential of this dipeptide in the context of AMD pathology.

Keywords: age-related macular degeneration; amyloid-beta oligomers; carnosine; inflammation; oxidative stress

DOI: https://doi.org/10.3390/molecules28083324

Antioxidants (Basel). 2023 Apr 05. pii: 884. [Epub ahead of print]12(4):

Matrix Metalloproteinase 13 Is Associated with Age-Related Choroidal Neovascularization.

Jorge González-Zamora, María Hernandez, Sergio Recalde, Jaione Bezunartea, Ana Montoliu, Valentina Bilbao-Malavé, Sara Llorente-González, Alfredo García-Layana, Patricia Fernández-Robredo.

Age-related macular degeneration (AMD) is a leading cause of severe vision loss in older individuals in developed countries. Despite advances in our understanding of AMD, its pathophysiology remains poorly understood. Matrix metalloproteinases (MMPs) have been proposed to play a role in AMD development. In this study, we aimed to characterize MMP-13 in AMD. We used retinal pigment epithelial cells, a murine model of laser-induced choroidal neovascularization, and plasma samples from patients with neovascular AMD to conduct our study. Our results show that MMP13 expression significantly increased under oxidative stress conditions in cultured retinal pigment epithelial cells. In the murine model, MMP13 was overexpressed in both retinal pigment epithelial cells and endothelial cells during choroidal neovascularization. Additionally, the total MMP13 levels in the plasma of patients with neovascular AMD were significantly lower than those in the control group. This suggests a reduced diffusion from the tissues or release from circulating cells in the bloodstream, given that the number and function of monocytes have been reported to be deficient in patients with AMD. Although more studies are needed to elucidate the role of MMP13 in AMD, it could be a promising therapeutic target for treating AMD.

Keywords: age-related macular degeneration; angiogenesis; choroidal neovascularization; matrix metalloproteinase; oxidative stress

DOI: https://doi.org/10.3390/antiox12040884

Int J Mol Sci. 2023 Apr 18. pii: 7459. [Epub ahead of print]24(8):

Identification of 7-Ketocholesterol-Modulated Pathways and Sterculic Acid Protective Effect in Retinal Pigmented Epithelium Cells by Using Genome-Wide Transcriptomic Analysis.

Ana Pariente, Álvaro Pérez-Sala, Rodrigo Ochoa, Miriam Bobadilla, Ángela Villanueva-Martínez, Rafael Peláez, Ignacio M Larráyoz.

Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries. AMD is characterized by the formation of lipidic deposits between the retinal pigment epithelium (RPE) and the choroid called drusen. 7-Ketocholesterol (7KCh), an oxidized-cholesterol derivative, is closely related to AMD as it is one of the main molecules accumulated in drusen. 7KCh induces inflammatory and cytotoxic responses in different cell types, and a better knowledge of the signaling pathways involved in its response would provide a new perspective on the molecular mechanisms that lead to the development of AMD. Furthermore, currently used therapies for AMD are not efficient enough. Sterculic acid (SA) attenuates the 7KCh response in RPE cells and is presented as an alternative to improve these therapies. By using genome-wide transcriptomic analysis in monkey RPE cells, we have provided new insight into 7KCh-induced signaling in RPE cells, as well as the protective capacity of SA. 7KCh modulates the expression of several genes associated with lipid metabolism, endoplasmic reticulum stress, inflammation and cell death and induces a complex response in RPE cells. The addition of SA successfully attenuates the deleterious effect of 7KCh and highlights its potential for the treatment of AMD.

Keywords: 7-ketocholesterol; AMD; retina; sterculic acid; transcriptome

DOI: https://doi.org/10.3390/ijms24087459

Mol Vis. 2022 ;28 500-506

Epac1 and PKA agonists inhibit ROS to reduce NLRP3 inflammasome proteins in retinal endothelial cells.

Li Liu, Youde Jiang, Jena J Steinle.

Purpose: Reactive oxygen species (ROS) activate inflammatory pathways in several organs, including the retina. More recent work has shown that ROS activate the NOD-like receptor protein 3 (NLRP3) inflammasome pathway proteins. We recently showed that the exchange protein activated by cAMP 1 (Epac1) and protein kinase A (PKA) regulates NLRP3 proteins in the retina. Our goal was to determine whether Epac1 and PKA reduce ROS and NLRP3 inflammasome proteins.Methods: We used human primary retinal endothelial cells (RECs) grown in normal glucose (5 mM) and stimulated in normal glucose with hydrogen peroxide (H2O2) to induce ROS and measured NLRP3 pathway proteins. In some groups, we treated cells with an Epac1 or a PKA agonist in addition to H2O2 treatment to determine whether Epac1 and PKA reduced ROS and induced NLRP3 pathway proteins.
Results: The data showed that 500 µM H2O2 was the optimal dose to increase ROS in RECs. In RECs treated with H2O2, NLRP3 pathway proteins were increased, which were significantly reduced by cotreatment with PKA or Epac1 agonists. H2O2 significantly increased NIMA-related kinase 7 (Nek7) and purinergic 2X7 receptor 7 (P2X7) levels, which were blocked by Epac1 and PKA agonists.
Conclusions: Taken together, these data suggest that Epac1 and PKA reduce retinal inflammation through the reduced ROS-induced activation of NLRP3 pathway proteins.