Propolis modulates NOS2/arginase-1 pathway in tropomyosin-induced experimental autoimmune uveitis

Area of Science:

• Ophthalmology
• Immunology
• Pharmacology

Background:

• Uveitis is an inflammatory eye condition.
• α-Tropomyosin-induced uveitis serves as an experimental model for studying ocular inflammation.
• Nitric oxide synthase (NOS2) and arginase-1 play crucial roles in regulating inflammatory responses.

Purpose of the Study:

• To evaluate the preventive and curative effects of ethanolic extract of Propolis (EEP) on α-Tropomyosin-induced uveitis in Wistar rats.
• To investigate the mechanisms underlying EEP's effects, focusing on NOS2 and arginase-1 regulation.

Main Methods:

• Rats were treated with EEP (100 mg/kg) either preventively or curatively.
• Histological examination of retinal damage was performed.
• Expression of NOS2, arginase-1, and nuclear factor-κB (NF-κB) was assessed.
• Plasmatic levels of nitric oxide (NO), urea, IL-4, and TNF-α were measured.

Main Results:

• EEP treatment significantly reduced retinal histological damage.
• EEP decreased levels of NO and TNF-α.
• EEP down-modulated NOS2 and NF-κB expression in the retina.
• EEP increased urea and IL-4 levels, concomitant with up-modulated arginase-1 expression.

Conclusions:

• EEP exhibits both preventive and curative effects against α-Tropomyosin-induced uveitis.
• EEP attenuates retinal damage by inhibiting the NF-κB/NOS2 pathway.
• EEP promotes a Th2 immune response, indicated by increased IL-4 and arginase-1 activity.