The anti-inflammatory regulation of calcitonin gene-related peptide in mouse Aspergillus fumigatus keratitis

AIM:To analyze the impact of calcitonin gene-related peptide(CGRP)in mouse keratitis after Aspergillus fumigatus(A.fumigatus)infection.METHODS:C57 BL/6 mice were treated subconjunctivally with different concentrations of exogenous CGRP,and BALB/c mice were treated with CGRP8-37(a CGRP antagonist)before corneas were infected with A.fumigatus.The cornea was assessed under the slit-lamp and the clinical score was recorded.The mRNA levels of IL-1β,TNF-α,IL-6,and MIP-2 were detected by quantitative real-time polymerase chain reaction(PCR),while the protein level of IL-1βwas determined by Western blotting.In vitro,RAW264.7 cells were used to investigate NLRP3 and IL-1βexpression induced by A.fumigatus after the pretreatment of exogenous CGRP or CGRP8-37.Cytokines expression in RAW264.7 cells was evaluated by real-time PCR and Western blotting.RESULTS:Using exogenous CGRP resulted in downregulated synthesis of IL-1βand MIP-2 stimulated by A.fumigatus in C57 BL/6 mice keratitis,and the synthesis of IL-1β,MIP-2 and IL-6 was up-regulated in BALB/c mice corneas after the pretreatment with CGRP8-37.Pretreatment with exogenous CGRP and CGRP8-37 did not influence TNF-αmRNA levels either in BALB/c or C57 BL/6 mice keratitis.The levels of NLRP3 and IL-1βwere both reduced in A.fumigatus stimulated-macrophages after treatment with exogenous CGRP.And CGRP8-37 pretreatment would increase NLRP3 and IL-1βlevels.CONCLUSION:CGRP may alleviate the inflammatory reaction in mice keratitis after infection with A.fumigatus.The anti-inflammatory effect may be related to the inhibition of NLRP3 expression by CGRP.

Expression and role of calcitonin gene-related peptide in mouse Aspergillus fumigatus keratitis

AIM: To investigate the expression and role of calcitonin gene-related peptide(CGRP) in the mouse models induced by Aspergillus fumigatus(A. fumigatus). METHODS: C57 BL/6 mice were randomized into a control group and A. fumigatus keratitis group. The cornea photography was assessed under the slit lamp and the clinical score was recorded after infection. Western blot, real-time polymerase chain reaction(PCR) and immunohistofluorescence analysis were applied to detect CGRP expression in cornea of both groups. In vitro, tests were conducted with C57 BL/6 mice macrophages to investigate CGRP expression after interaction with A. fumigatus. Cytokines expression induced by exogenous CGRP and the antagonist CGRP8-37 in A. fumigatus-exposed macrophages was evaluated by real-time PCR and ELISA.RESULTS: The cornea expression of CGRP was significantly elevated in C57 BL/6 mice corneas and macrophages after A. fumigatus infection. After treatment with exogenous CGRP, the levels of interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α) and IL-6 were reduced, and IL-10 level was increased in the A. fumigatus stimulatedmacrophages. However, IL-1β, TNF-α and IL-6 levels were upregulated after pretreatment of CGRP8-37. But the m RNA levels of MIP-2, TGF-β and IL-10 were not changed. CONCLUSION: This study provides evidence that A. fumigatus increased CGRP expression. CGRP may play a protective role against inflammation in A. fumigatus keratitis.