The production mechanism and immunosuppression effect of pulmonary surfactant protein D via toll like receptor 4 signaling pathway in human corneal epithelial cells during Aspergillus fumigatus infection.
OBJECTIVE
To observe the production mechanism of surfactant protein D (SP-D) in human corneal epithelial cells (HCECs) when infected by Aspergillus fumigatus (A. fumigatus) hyphae, and explore whether SP-D can inhibit the cell activations through toll-like receptor 4 signaling pathway during fungal infection.


METHODS
mRNA and protein expressions of SP-D were evaluated in HCECs after stimulation by A. fumigatus, with or without pretreatment of TLR4 inhibitor (CLI-095) by real time PCR and Western blot. The expression levels of inflammatory cytokines IL-1β and IL-8 evaluated when pretreated with SP-D antibody or recombinant human SP-D in fungi-stimulated HCECs by real time PCR and ELISA, IL-1β and IL-8 expressions were also detected in A. fumigatus-stimulated HCECs that pretreated with CLI095 or MyD88 inhibitor (Pepinh-MYD) and recombinant human SP-D.


RESULTS
mRNA and protein levels of SP-D increased after stimulation of A. fumigatus for 16h and 20h respectively. The upregulation of SP-D could be inhibited by CLI-095. mRNA and protein expressions of IL-1β and IL-8 decreased significantly when pretreated HCECs with recombinant human SP-D for 4h before A. fumigatus stimulation, while IL-1β and IL-8 increased when pretreated with SP-D antibody for 1h. Pretreatment of CLI095 or Pepinh-MYD can increase the expressions of IL-1β and IL-8 mRNA and protein in HCECs induced by recombinant human SP-D and A. fumigatus.


CONCLUSIONS
SP-D can be stimulated by TLR4 during A. fumigatus infection. Recombinant human SP-D can inhibit the expression of inflammatory cytokines through TLR4 signaling pathway.
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China.
Xian
X
Wu
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China. Electronic address: guiqiuzhao@126.com.
Guiqiu
G
Zhao
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China.
Jing
J
Lin
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China.
Nan
N
Jiang
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China.
Cui
C
Li
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China.
Liting
L
Hu
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China.
Xudong
X
Peng
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China.
Qiang
Q
Xu
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China.
Qian
Q
Wang
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China.
Hui
H
Li
Department of Ophthalmology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China.
Yan
Y
Zhang
D001228:Aspergillosis / Q000473:pathology*; D001232:Aspergillus fumigatus; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000187:drug effects; D019573:Epithelium, Corneal / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D053583:Interleukin-1beta / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D016209:Interleukin-8 / Q000037:antagonists & inhibitors; D053594:Myeloid Differentiation Factor 88 / Q000037:antagonists & inhibitors; D037663:Pulmonary Surfactant-Associated Protein D / Q000096:biosynthesis* / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000235:genetics; D013449:Sulfonamides / Q000494:pharmacology; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors*
C508606:CXCL8 protein, human; C508585:IL1B protein, human; D007166:Immunosuppressive Agents; D053583:Interleukin-1beta; D016209:Interleukin-8; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D037663:Pulmonary Surfactant-Associated Protein D; D011994:Recombinant Proteins; D013449:Sulfonamides; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; C507035:ethyl 6-(N-(2-chloro-4-fluorophenyl)sulfamoyl)cyclohex-1-ene-1-carboxylate
Aspergillus fumigatus; Fungal keratitis; Surfactant protein D; Toll-like receptor 4