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Published on: December 12, 2014
Establishing PDE4 as a Novel Target of Urolithin-A in Mitigating LPS-induced Inflammation in Retinal Pigmented
Likhitha Purna Kondapaneni1,2,3, Meenakshi Arora1,2,3,4, Erin M Scott5
1The Center for Convergent Bioscience and Medicine (CCBM), The University of Alabama, Tuscaloosa, AL, USA.
Abstract:
Ocular inflammation is a major contributor to vision-threatening disorders, with phosphodiesterase 4 (PDE4), a key regulator of cAMP playing a central role in pro-inflammatory signaling. Although investigational PDE4 inhibitors like Rolipram (RP) show therapeutic promise, their systemic toxicity limits clinical application, underscoring the need for safer, targeted alternatives. Urolithin A (UA), a gut-derived metabolite of ellagic acid with emerging anti-inflammatory properties, was evaluated as a novel PDE4 inhibitor. Molecular docking revealed that UA binds with high affinity to the A-chain of PDE4A (-8.79 kcal/mol), forming unique π-π stacking and multiple hydrogen bonds. In contrast, RP binds preferentially to the B-chain with slightly lower affinity (-8.42 kcal/mol) and fewer stabilizing interactions. While both ligands engage similar catalytic residues, UA exhibited a more extensive binding profile, suggesting enhanced stability and specificity. In lipopolysaccharide (LPS)-stimulated human retinal pigment epithelial cells (ARPE-19), UA significantly inhibited PDE4A activity, elevated intracellular cAMP, and reduced key inflammatory mediators (NF-κB, IL-6, TNF-α), as demonstrated by immunofluorescence, ELISA, and gene expression analysis. These findings support UA's function as an anti-inflammatory agent by inhibiting PDE4A, highlighting its potential as a safer systemic or localized therapy for ocular inflammatory diseases.
Insights
Urolithin A (UA) shows potential as a novel anti-inflammatory agent for ocular diseases by inhibiting phosphodiesterase 4 (PDE4). This gut metabolite effectively reduced inflammation in eye cells, offering a safer alternative to existing treatments.
Area of Science:
- Ophthalmology
- Pharmacology
- Biochemistry
Background:
- Ocular inflammation contributes to vision loss, with phosphodiesterase 4 (PDE4) central to inflammatory signaling.
- Current PDE4 inhibitors like Rolipram (RP) have systemic toxicity, necessitating safer alternatives.
Purpose of the Study:
- To evaluate Urolithin A (UA), a gut metabolite, as a novel PDE4 inhibitor for ocular inflammation.
- To compare UA's binding affinity and interactions with PDE4A against Rolipram (RP).
Main Methods:
- Molecular docking simulations to assess UA and RP binding to PDE4A.
- In vitro experiments using LPS-stimulated ARPE-19 cells to measure PDE4A activity, cAMP levels, and inflammatory markers (NF-κB, IL-6, TNF-α).
- Immunofluorescence, ELISA, and gene expression analysis were employed.
Main Results:
- UA demonstrated high-affinity binding to the PDE4A catalytic site, with favorable interactions.
- UA significantly inhibited PDE4A activity and reduced inflammatory mediators in ARPE-19 cells.
- UA elevated intracellular cAMP levels, indicating PDE4 inhibition.
Conclusions:
- Urolithin A functions as an effective anti-inflammatory agent by inhibiting PDE4A.
- UA presents a promising therapeutic potential for ocular inflammatory diseases, possibly with improved safety profiles.
