The Effect Of Immunostimulatory CpG ODN On Experimental Allergic Conjunctivitis Caused By Aspergillus Fumigatus

Background Allergic conjunctivitis (AC) is one of the most common eye diseases involving Th2-biased immune response. This study investigated into whether the Th1-Th2 switching immunostimulatory CpG ODN could reverse the response in the murine AC model caused by Aspergillus fumigatus (Af).Methods A mixture of spores and hyphae of Af strain was used to induce AC in male BALB/C mice (six to eight weeks), which were further subjected to preventive or therapeutical treatment. Under both settings, AC animals were treated with CpG ODN, nonstimulatory GpC ODN or PBS as control. After the last challenge with the allergen, the animals were examined for clinical symptoms and then executed. Cellular infiltration and TLR4 expression in conjunctiva were analyzed by histology and real-time PCR assay. The responsiveness and populations of lymphocytes in spleen and draining lymph nodes were analyzed by flow cytometry.Results In the prevention mode, CpG ODN decreased subconjunctival infiltration compared with GpC ODN and PBS groups, the average neutrophil count index being 21.25±11.59, 30.75±11.44 and 69.00±9.90 per vision field respectively. Expression of TLR4 mRNA was up-regulated significantly by CpG ODN. The clinical scores for CpG ODN group were lower than in other two groups but did not reach significant level (P>0.05). In the therapeutic mode, compared with GpC ODN and PBS groups, CpG ODN group manifested significantly lower allergic symptom score, lower cellular infiltration and higher expression of TLR4 mRNA. In the cultured splenic and draining lymph node cells, increased percentages of both CD4~+CD25~+ and CD4~+CD25~+CD69~+ in CpG ODN group were observed compared with control groups. Conclusion Treatment of Af-induced AC animals with either subconjunctival injection or topical application with CpG ODN could relieved allergical inflammation-related histological or clinical expression. Modulation of TLR4 expression and Treg lymphocytes activation might be involved such a modulation effect of CpG ODN in this Af-sensitized AC model.