Th1/Th2 cytokine expression in diabetic retinopathy

Area of Science:

• Immunology
• Ophthalmology
• Endocrinology

Background:

• Diabetic retinopathy (DR), a complication of diabetes mellitus (DM), lacks a clear understanding of its underlying mechanisms.
• T helper (Th) cell balance, specifically the Th1/Th2 cytokine profile, is implicated in autoimmune diseases but its role in DR is unexplored.

Purpose of the Study:

• To investigate the changes in Th1 and Th2 cytokine expression in patients with type 2 diabetes mellitus (T2DM) with and without DR.
• To analyze the correlation between Th1 and Th2 cytokine levels and their potential role in DR pathogenesis.

Main Methods:

• Blood samples were collected from healthy controls, T2DM patients without DR, and T2DM patients with DR.
• Real-time PCR and ELISA were employed to quantify mRNA and protein expression of Th1 (IL-2, TNF-α) and Th2 (IL-4, IL-10) cytokines.

Main Results:

• Both T2DM and DR groups exhibited significantly higher IL-2 and TNF-α levels compared to controls. DR patients showed elevated IL-2 and TNF-α compared to T2DM patients.
• IL-4 and IL-10 levels were significantly lower in the DR group than in normal and T2DM groups. T2DM patients showed no significant difference in IL-4 and IL-10 compared to controls.
• A negative correlation was observed between IL-2/TNF-α and IL-4/IL-10 in the DR group, indicating a Th1/Th2 imbalance.

Conclusions:

• DR is characterized by increased Th1 cytokine secretion and decreased Th2 cytokine secretion, leading to a Th1/Th2 imbalance.
• This Th1/Th2 immune imbalance is suggested to be a contributing factor in the occurrence and progression of diabetic retinopathy.