Puerarin suppresses hypoxia-induced vascular endothelial growth factor upregulation in human retinal pigmented epithelial cells by blocking JAK2/STAT3 pathway

Morroniside ameliorates lipopolysaccharide-induced inflammatory damage in iris pigment epithelial cells through inhibition of TLR4/JAK2/STAT3 pathway

AIM

To investigate the effect of morroniside (Mor) on lipopolysaccharide (LPS)-treated iris pigment epithelial cells (IPE).

METHODS

IPE cells were induced by LPS and treated with Mor. Cell proliferation was detected by cell counting kit (CCK) -8, apoptosis was detected by flow cytometry, the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-8 were measured by enzyme-linked immunosorbent assay (ELISA) kits, and the protein expression of TLR4, JAK2, p-JAK2, STAT3, and p-STAT3 was analyzed by Western blotting. In addition, overexpression of TLR4 and Mor treatment of LPS-stimulated IPE cells were also tested for the above indices.

RESULTS

Mor effectively promoted the proliferation and inhibited the apoptosis of LPS-treated IPE cells. In addition, Mor significantly reduced the levels of TNF-α, IL-6, and IL-8 and significantly inhibited the expression of TLR4, p-JAK2, and p-STAT3 in LPS-treated IPE cells. The effect of Mor on LPS-treated IPE cells was markedly attenuated after overexpression of TLR4.

CONCLUSION

These findings suggest that Mor may ameliorate LPS-induced inflammatory damage and apoptosis in IPE through inhibition of TLR4/JAK2/STAT3 pathway.

A simplified protocol to induce hypoxia in a standard incubator: A focus on retinal cells

Hypoxia chambers have traditionally been used to induce hypoxia in cell cultures. Cellular responses to hypoxia can also be mimicked with the use of chemicals such as cobalt chloride (CoCl2), which stabilizes hypoxia-inducible factor alpha-subunit proteins. In studies of ocular cells using primary cells and cell lines, such as Müller glial cell (MGC) lines, photoreceptor cell lines, retinal pigment epithelial (RPE) cell lines and retinoblastoma cell lines oxygen levels employed in hypoxia chambers range typically between 0.2% and 5% oxygen. For chemical induction of hypoxic response in these cells, the CoCl2 concentrations used typically range from 100 to 600 μM. Here, we describe simplified protocols for stabilizing cellular hypoxia-inducible factor-1α (HIF-1α) in cell culture using either a hypoxia chamber or CoCl2. In addition, we also provide a detailed methodology to confirm hypoxia induction by the assessment of protein levels of HIF-1α, which accumulates in response to hypoxic conditions. Furthermore, we provide a summary of conditions applied in previous studies of ocular cells.