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AIM: To establish a dry eye mouse model of iron overload by intraperitoneal injection of iron dextran and preliminarily explore its possible mechanism.METHODS: A total of 40 male C57BL/6 mice(taking the right eye as the experimental eye)were divided into 4 groups by random number table method: There were 10 mice in the control group, each time by intraperitoneal injection of 0.2mL of normal saline; Low-dose group, middle-dose group and high-dose iron group with 10 mice in each group were the model group. Each time, 0.2mL of iron dextran solution with concentrations of 12.5, 25, and 50 mg/mL was injected intraperitoneally. One injection 3d for a total of 28d. We observed the ocular surface inflammation index, corneal fluorescein staining, tear break-up time(BUT)and Schimer I test(SIt)on the 7, 14 and 28d after injection and evaluated the degree of dry eye and ocular surface inflammation. After 28d, the mice were sacrificed for cornea, conjunctiva and lacrimal glands tissue for HE staining, Prussian blue staining and tissue iron detection, to evaluate the inflammatory reaction and iron overload. The expression of inflammatory factors interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α)and matrix metallo proteinase-9(MMP-9)were detected by enzyme-linked immunosorbent assay(ELISA).RESULTS: Compared with the control group, the mice in the model group showed a series of dry eye symptoms, the inflammation index of ocular surface in mice were increased, the score of corneal fluorescein staining increased, the BUT shortened and the amount of tear secretion decreased(all P<0.05). The cornea, conjunctiva and lacrimal gland tissues of the mice were damaged to varying degrees, the iron deposition on the eye surface of the model group was more serious than that of the control group, and the iron content of the tissue was significantly increased than the control group(all P<0.01). The contents of inflammatory factors(IL-1β, TNF-α, MMP-9)in the cornea, conjunctiva and lacrimal gland tissue of the mice in the model group were significantly higher than those of the control group(all P<0.01). With the increase of injection time and concentration of iron dextran, the degree of dry eye and ocular surface inflammation in mice gradually increased. CONCLUSION: The mouse iron overload dry eye model was successfully established by intraperitoneal injection of iron dextran, the mechanism may be related to the ocular surface inflammation aggravated by iron overload.
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AIM: To explore whether efferocytosis impacts ocular surface inflammation in high-iron environment by regulating macrophage polarization. METHODS: A total of 50 healthy C57BL/6 male mice aged 6-8wk were randomly divided into normal control group, iron group, inhibitor group, enhancer group and solvent control group, with 10 mice in each group. The normal control group was injected intraperitoneally with 0.2mL of normal saline, and the other groups were injected intraperitoneally with 50mg/mL iron dextran of 0.2mL, once every 3d. From the 14d, the inhibitor group, the enhancer group and the solvent control group were injected intraperitoneally with the same volume(0.2mL)50mg/kg XMD8-92, 10mg/kg simvastatin and 50% DMSO solvent once a day, respectively. The anterior segment of the eyes was observed under slit lamp microscope on the 7, 14, 28d after intraperitoneal injection, and the ocular surface inflammation index and corneal fluorescein staining score were evaluated. The cornea, conjunctiva and lacrimal gland tissues were taken at 28d for the HE staining and immunofluorescence staining, and RT-PCR were used to detect the expression of macrophage polarization related indexes(CD86, CD206, iNOS, Arg-1); Western blot were used to detect the expression of efferocytosis related signal factors(Gas6, MerTK); ELISA was used to detect the expression of inflammatory factors(IL-1β, TNF-α, MMP-9).RESULTS: After injection for 28d, compared with the normal control group, the ocular surface inflammatory index and corneal fluorescein staining score were increased in the iron group and the solvent control group. HE staining showed incomplete corneal epithelium, reduced conjunctival goblet cells, unclear lacrimal gland structure and relatively disordered arrangement of cells. In all tissues, the expressions of polarization related indexes of M1 macrophages such as CD86 and iNOS were up-regulated, while those of M2 macrophages such as CD206 and Arg-1 were down-regulated, and the expressions of inflammatory factors such as IL-1β, TNF-α and MMP-9 were up-regulated(all P<0.05). Compared with the iron group and the solvent control group, the ocular surface inflammation index and corneal fluorescein staining score of the inhibitor group were further increased. HE staining showed obvious exfoliation of corneal epithelium, further decrease or even disappearance of conjunctival goblet cells, disorder of lacrimal gland structure and irregular arrangement of cells. In all tissues, the expression of signal factors related to efferocytosis such as Gas6 and MerTK was down-regulated(all P<0.05), the expression of polarization related indexes of M1 macrophages such as CD86 and iNOS and the expression of inflammatory factors such as IL-1β, TNF-α and MMP-9 were further up-regulated(all P<0.05). But the ocular surface inflammation index and corneal fluorescein staining score decreased in the enhancer group. HE staining showed the integrity of corneal epithelial, the increase of conjunctival goblet cells and the improvement of lacrimal gland structure and morphology. In all tissues, the expression of signal factors related to efferocytosis such as Gas6 and MerTK was up-regulated(all P<0.05), and the expression of polarization related indexes of M2 macrophages such as CD206 and Arg-1 was up-regulated, while the expression of inflammatory factors such as IL-1β, TNF-α and MMP-9 was down-regulated(all P<0.05). CONCLUSION: High-iron environment induces macrophages polarize to M1, which aggravates ocular surface inflammation and tissue damage. Efferocytosis by regulating the polarization of macrophages impact the occurrence of ocular surface inflammation in high-iron environment.
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Objective:To investigate the prevalence of metabolic syndromes （MS） and MS scores as well as related health behavior factors in Zhongshan Community， Songjiang， Shanghai. Methods:A total of 6 802 residents aged 20-74 years old in Zhongshan Community were selected. Face-to-face survey and body measurement were used to collect information such as MS-related behavioral factors （including smoking， alcohol intake， exercise and diet） and to determine the MS scores. MS scores were divided into 6 levels. Ordered logit model was used to analyze the factors related to MS score， and logit model was used to analyze the factors related to MS. Results:The prevalence of 6 metabolic syndrome scores in the sample population were 13.5%， 24.3%， 25.1%， 19.7%， 12.3%， 5.1%， respectively. The prevalence of MS was 37.0%. The related factors of high MS score in male were advanced age， alcohol intake and tea drinking， while the related factors of high MS score in female were advanced age and previous smoking. The related factors of MS was alcohol intake in male while female with advanced age had higher risk in developing MS. Conclusion:The prevalence of MS in Zhongshan Community is relatively high， which has become one of the important public health problems in this community. Attention should be paid to the elderly men who drink alcohol and tea， and aged women who have ever smoked.