Increased cGAS/STING signaling components in patients with Mooren's ulcer

AIM:To explore the expression of cGAS/STING signaling components in Mooren’s ulcer(MU).METHODS:Samples were obtained from ten MU patients,and eight residual corneal-scleral rings of healthy donor corneas for controls.Human corneal epithelial cells(HCECs)were used to evaluate the effect of cGAS/STING signaling pathway.Immunohistochemistr y(IHC)and Western blot were used to examine the expression of cGAS,STING,and phosphorylated interferon regulatory factor 3(p-IRF3)in MU tissues.The expression of interferon-β(IFN-β)and interferon-stimulated genes(ISGs)was quantified by real-time polymerase chain reaction(PCR)and enzymelinked immunosorbent assay(ELISA).RESULTS:The protein levels of cGAS and STING in MU samples were significantly elevated when compared with the healthy controls by Western blot and IHC.After stimulation with cGAMP,real-time PCR and ELISA showed a dramatic increase of IFN-βand ISGs(containing CXCL10,IFIT1,and IL-6)in HCECs.Moreover,HCECs treated with cGAMP was characterized by increased phosphorylation and more nuclear translocation of IRF3.Meanwhile,increased p-IRF3 was observed in MU samples via IHC and Western blot.CONCLUSION:The pronounced expression of cGAS/STING signaling components in the patients with MU and probably contribute to the onset and development of MU.

Increased succinate receptor GPR91 involved in the pathogenesis of Mooren's ulcer

AIM： To investigate the expression of succinate receptor GPR91 and its pathogenic roles in Mooren＇s ulcer（MU）.METHODS： Biopsy specimens were obtained from 7 patients with MU and 6 healthy donors. The expression of GPR91 in MU tissues was evaluated using quantitative realtime reverse transcription polymerase chain reaction（qRTPCR） and immunohistochemistry（IHC）. Succinate was used to activate GPR91 signaling, and the effect of GPR91 on the expression of interleukin-1β（IL-1β）, NLRP3, vascular endothelial growth factor（VEGF） and matrix metalloproteinase-13（MMP-13） in human peripheral blood mononuclear cells（PBMCs） was determined. The influence of GPR91 on the nuclear factor-κB（NF-κB） signaling in PBMCs was investigated by detecting the phosphorylation of p65. Moreover, the expression of IL-1β, VEGF, MMP-13 and phosphorylated p65（p-p65） in the tissues of MU was examined by qRT-PCR or IHC.RESULTS： GPR91 mRNA expression showed a higher level in the MU group than in the healthy control group. IHC analysis also revealed that the expression of GPR91 was elevated in patients with MU compared with healthy controls. Moreover, ligation of GPR91 with succinate promoted the lipopolysaccharide-induced production of NLRP3, IL-1β, VEGF and MMP-13 in PBMCs through increased phosphorylation of p65. Pharmacological inhibition of the NF-κB signaling reversed GPR91 induced production of NLRP3, IL-1β, VEGF and MMP-13. These findings, coupled with the elevated amounts of IL-1β, VEGF, MMP-13 and p-p65 observed in the MU biopsies, constituted a rational basis for the involvement of GPR91 in the pathogenesis of MU.CONCLUSION： This study indicates the increased succinate receptor GPR91 in conjunctival or corneal tissues is involved in the pathogenesis of MU through elevated NF-κB activity, which may provide a new therapeutic target for MU.

Etiology and failure analysis of anterior lamellar keratoplasty

AIM：To analyze indications and reasons for failure of anterior lamellar keratoplasty（ALK）.METHODS：The clinical records were retrospectively reviewed.Main outcome measures included indications for ALK and reasons for failure of ALK.RESULTS：A total of 434 patients（462 eyes） were treated with ALK at Qingdao Eye Hospital,Shandong Eye Institute from June 1,2009 to May 31,2016.The main indications were infectious keratitis（33.3%）,keratoconus（23.6%）,corneal dystrophy and degeneration（9.8%）,Mooren＇s ulcer（8.4%）,corneal neoplasm（7.8%）,viral keratitis（6.5%） and regrafting（3.7%）.Fungal keratitis accounted for 73.4% in the infectious keratitis cases.ALKs were failed in 36 patients,with the major causes being recurrence of primary diseases（63.9%）.The leading causes of graft failure was Mooren＇s ulcer（36.1%）,followed by infectious keratitis（30.6%）.Recurrence of fungal keratitis accounted for 81.8% in the failed cases after ALK for infectious keratitis cases.CONCLUSION：Infectious keratitis and keratoconus are the main indications for ALK,of which fungal keratitis was the major cause of corneal infections.Recurrence of primary disease is the main reason of graft failure after ALK,in which the main primary diseases associated with graft failure are Mooren＇s ulcer and fungal keratitis.