Hum. Reprod. Advance Access originally published online on September 10, 2008
Human Reproduction 2009 24(1):211-218; doi:10.1093/humrep/den318
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Hemoglobin and its derived peptides may play a role in the antibacterial mechanism of the vagina
1 Research Unit of Infection and Immunity, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, People's Republic of China 2 Department of Gynecology and Obstetrics, West China Woman and Children Hospital, Sichuan University, Chengdu, Sichuan 610041, People's Republic of China
3 Correspondence address. Tel: +86-28-85503132; Fax: +86-28-85503204; E-mail: huangpanxiao{at}sina.com
BACKGROUND: Hemoglobin is a precursor of antibacterial peptides. Our aim was to identify an antibacterial peptide in human endometrium. We tested the antimicrobial activities of hemoglobin and a derived peptide in vitro and in vivo in rats.
METHODS: Samples (n = 3) were scraped from the surface of endometrium. Acid-soluble proteins underwent electrophoresis followed by gel overlay assay and reversed-phase high-performance liquid chromatography. Antibacterial activities were determined by agar radial diffusion assay. Purified peptides were further characterized by electrophoresis, mass spectrometry, N-terminal amino acid (AA) sequencing and protein structure analysis. A rat model was used to test the inhibitory activity of human hemoglobin on vaginal infection with Escherichia coli, using one experimental group (intravaginal hemoglobin, n = 9) and three control groups (n = 14). Vaginal histology was studied.
RESULTS: The purified peptide exhibited potent antibacterial activities against E. coli ML-35P. The N-terminal AA sequence was F L S F P T T K T Y, identical to AA 32–41 of the human hemoglobin
chain, and it had the same mass (m/z = 6776.8) as the
chain 32–93 AA fragment, with at least three
-helices. Histology indicated that the hemoglobin group changed significantly compared with the matrix control group (no treatment after infection): the surface layer of stratified squamous epithelium was smoother, inflammatory cell infiltration was relieved in the lamina propria and congestion pattern was decreased.
CONCLUSIONS: These results suggest that erythrocytes from endometrium are another source of the antimicrobial molecules. Hemoglobin and its derived peptides may play a role in the host defense against pathogens in human vagina.
Key words: endometrial scraping samples/antibacterial polypeptide/hemoglobin-derived peptide/vagina
Submitted on December 11, 2007; resubmitted on May 20, 2008; accepted on June 30, 2008.