Studies showed that the content of nitric oxide synthase (NOS) in aqueous and lenses elevates in cataract eyes. But it is difficult to measure the NOS content in eye tissue. So to determine whether the overepression of NOS is associated with cataractogenesis is significant for the prevention and treatment of cataract.

This study was to detect the expression of NOS in the peripheral blood of cataract patients and evaluate the association of blood NOS with cataractogenesis.

Twenty-five patients with age-related cataract and 12 patients with diabetic cataract were collected from January to June 2014 in Affiliated First Hospital of Soochow University and Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, and 20 matched healthy volunteers were enrolled in the Health Check Centre in the same duration. The 2.0 ml peripheral blood was collected from each subject under the informed consent. The blood specimens were centrifuged to obtain cell pellets. The contents of NOS mRNA and inducible nitric oxide synthase (iNOS) mRNA and their proteins in leukocytes were measured by reverse transcription PCR (RT-PCR) and flow cytometry.

The relative expression levels of total NOS mRNA were 1.46±0.31, 1.59±0.28 and 1.22±0.23 in the age-related cataract group, the diabetic cataract group and the healthy control group, respectively, with a significant difference among the three groups (F=7.572, P=0.001). The relative expression level of total NOS mRNA was significantly higher in the age-related cataract group and the diabetic cataract group than that of the healthy control group (q=4.095, 5.170, both at P<0.01). The relative expression levels of iNOS in blood were 1.17±0.21, 1.08±0.15 and 0.89±0.17 in the age-related cataract group, the diabetic cataract group and the healthy control group, respectively, showing a significant difference among the three groups (F=12.801, P=0.000), and the level of iNOS in blood was significantly increased in the age-related cataract group and the diabetic cataract group compared with the healthy control group (q=7.112, 3.932, both at P<0.01). The expressions of total NOS protein in the age-related cataract group, the diabetic cataract group and the healthy control group were 15.82±2.11, 17.19±3.37 and 10.63±2.28, with a significant difference among them (F=34.895, P=0.000), and the expressions of total NOS protein were significantly elevated in the age-related cataract group and the diabetic cataract group in comparison with the healthy control group (q=9.885, 10.266, both at P<0.01).

NOS content in periphery blood elevates in age-related and diabetic cataract patients. These results indicate that blood NOS may be associated with cataractogenesis. The measurement of blood NOS may be a useful indicator in monitoring and preventing cataract formation and development.

Nitric oxide synthase; Nitric oxide; Cataract; Peripheral blood; Reverse transcription PCR; Flow cytometry