Abstract
Purpose :
Inflammation is a critical player in the etiology and pathogenesis of Age-related Macular Degeneration (AMD). Humanin G (HNG) is a Mitochondrial Derived Peptide (MDP) that is cytoprotective in AMD. The goal of this study was to test our hypothesis that the inflammation markers- CD62P i.e., P Selectin and CD62E i.e., E Selectin proteins, are increased in AMD and HNG treatment in vitro leads to reduction in their protein levels.
Methods :
In this study, we used: 1) blood plasma isolated from AMD patients and age-matched control subjects, and 2) AMD and control transmitochondrial RPE cybrid cell lines. HNG was exogenously added to AMD cybrids, which have identical nuclei from the mitochondria-deficient ARPE-19 cells but differed in mitochondrial DNA (mtDNA) content derived from clinically characterized AMD patients and control subjects. Cell lysates were extracted from untreated and HNG-treated AMD and control cybrids, and then analyzed using the Luminex multiplex assay to determine the protein levels of CD62P and CD62E.
Results :
The CD62P protein levels were 152% higher in AMD plasma samples (2.52±0.41, n=3) vs. Controls (1±0.2, n=3) (p=0.03). Treatment with HNG led to a 37% decrease in CD62P protein levels in control cybrid cell lysates (Untreated: 1±0.34; HNG-treated: 0.63±0.04) and a 21% decrease in CD62P protein levels in AMD cybrid cell lysates (Untreated: 1±0.24; HNG-treated: 0.79±0.09). Furthermore, CD62E protein levels were 176% higher in AMD plasma samples (2.76±0.48, n=3) vs. Controls (1±0.28, n=3) (p=0.03). Treatment with HNG led to 18% decrease in CD62E protein levels in AMD cell lysates (Untreated:1±0.02; HNG-treated: 0.82±0.02). No difference was found in CD62E protein levels between untreated vs. HNG-treated control cell lysates.
Conclusions :
In summary, we observed: 1) significantly higher levels of CD62P and CD62E proteins in AMD plasma samples compared with control plasma samples, and 2) HNG reduced the CD62P and CD62E protein levels in cell lysates, thereby suggesting that HNG may rescue the mtDNA-mediated inflammation in AMD cybrids. In conclusion, this study presents novel findings that suggest the role of 1) CD62P and CD62E in AMD pathogenesis and 2) HNG as a potential target for reducing Selectins-associated inflammation in AMD. Further studies are required to establish the role of HNG in reducing inflammation by decreasing the protein levels of Selectins in AMD.
This is a 2021 ARVO Annual Meeting abstract.