JuJing formula protects retinal by regulating Nrf2/HO-1 pathways and sphingolipid rheostat and its key protein levels on liver-kidney Yin deficient retinal damage mice.

Ethnopharmacological Relevance: Dry age-related macular degeneration (AMD) has a high rate of blindness, which still lacks effective treatment. JuJing Formula (JJF) is a traditional herbal prescription known for its hepatorenal tonic effects and therapeutic applications in ocular disorders. Previous investigations have demonstrated its efficacy in the management of dry AMD. However, the underlying mechanisms of JJF against dry AMD have not been fully characterized.

Aim Of The Study: The protective effect and mechanism of JJF on dry AMD were investigated in the liver-kidney Yin deficient retinal damage (LKYD-RD) model of mice.

Materials And Methods: Initially, a LKYD-RD mouse model was established through a combination of thyroxine administration, tail clamping, and sodium iodate injection. Secondly, the amelioration of Yin deficiency symptoms was examined by detecting biochemical indices and histopathologic changes. Meanwhile, the therapeutic efficacy on retinal damage was evaluated using optical coherence tomography (OCT), hematoxylin and eosin (H&E) staining, terminal deoxynucleotidyl (TUNEL) staining, and levels of oxidative stress markers (SOD, MDA, and GSH) and inflammatory factors (IL-1β, IL-6, and TNF-α). Furthermore, serum metabolomics studies were performed to predict the mechanisms of JJF on LKYD-RD mice. Eventually, ELISA, immunofluorescence analysis, RT-qPCR, and Western blotting assays were conducted to verify the mechanisms.

Results: JJF not only significantly ameliorated LKYD syndrome but also restored the retinal structure and function in LKYD-RD mice. Furthermore, JJF inhibited the inflammatory response and suppressed oxidative stress through the Nrf2/HO-1 signaling pathway. Metabolomic profiling revealed sphingolipid signaling as the predominant regulatory pathway mediating JJF's therapeutic effects on LKYD-RD. Specifically, JJF treatment normalized sphingolipid metabolism by reducing elevated ocular levels of ceramide and sphingosine while increasing sphingosine-1-phosphate concentrations. At the molecular level, JJF upregulated the expression of p-Sphk1/Sphk1, Asah1, and Bcl2, while downregulating Cers2, Cers6, Bax, cleaved-Caspase 3, and Sgpp1. The findings suggested that regulation of the sphingolipid rheostat and its critical proteins is a potential mechanism of JJF resistance to dry AMD.

Conclusions: In summary, the current study demonstrates that JJF exerts significant therapeutic effects in the LKYD-RD murine model, primarily through the modulation of sphingolipid metabolic signaling pathways. This research provides a reference for the clinical management of dry AMD.