Hemoglobin and its derived peptides may play a role in the antibacterial mechanism of the vagina

Abstract

† Introduction † Materials and Methods † Results † Discussion † Funding † Referencesbackground: 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 ¼ 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 ¼ 9) and three control groups (n ¼ 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 a chain, and it had the same mass (m/z ¼ 6776.8) as the a chain 32 -93 AA fragment, with at least three a-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.

The chromosomal protein HMGN2 mediates lipopolysaccharide‐induced expression of β‐defensins in A549 cells

“…Significantly, the HBD level in the LPS group was fivefold higher than that in the control group, while the HBD‐2 level in the HMGN2 knockdown group was threefold less than in the LPS group. The results of the microarray are reliable because they agree well with the expression of genes known to be modulated by HMGN2, such as N‐cadherin, Sry‐related HMG‐box gene 9 (Sox9), pituitary homeobox 2, heat shock proteins and type 2 glucose transporters (Glut2) [4,29–35]. Pathway analysis of the microarray results showed that HMGN2 modulates the Toll–NF‐κB pathway upon LPS stimulation because the expression of RELA (p65), IKBKB (IκB) and myeloid differentiation primary response gene 88 (MyD88), which were the main members on the Toll–NF‐κB pathway, was changed in HMGN2 knockdown plus LPS groups compared with the LPS group.…”

The Chromosomal Protein HMGN2 Mediates the LPS-Induced Expression of β-Defensins in Mice

“…Moreover, in our previous studies, we have demonstrated a role of HMGN2 in modulating specific gene expression and have identified HBD-2 as an HMGN2 target in LPS-induced A549 cells. Our data indicated that HMGN2 and NF-κB p65 synergistically promote their specific binding to the promoter of the HBD-2 chromatin, thereby affecting downstream transcription and HBD-2 expression [28,29].…”

Evaluation of antibacterial activity and innate immune components in skin mucus of Indian major carp,Cirrhinus mrigala

“…Intact haemoglobin and its fragments isolated from human and Alligator mississippiensis have been shown to possess a broad spectrum of antimicrobial activity (Hodson & Hirsch 1958;Parish, Jiang, Tokiwa, Berova, Nakanishi, McCabe, Zuckerman, Xia & Gabay 2001). Antimicrobial peptides derived from haemoglobin were reported in the gill epithelium of Ictalurus punctatus (Ullal, Litaker & Noga 2008) and in the female human reproductive tract (Deng, Pan, Wang, Wang, Zhou, Li, Feng, Wu, Wang & Huang 2009). Haemoglobin subunits (alpha and beta) have also been identified in the normal buccal cavity mucus in female Oreochromis spp.…”