Novel Antibacterial Activity of β2-Microglobulin in Human Amniotic Fluid

Abstract

An antibacterial protein (about 12 kDa) was isolated from human amniotic fluid through dialysis, ultrafiltration and C18 reversed-phase HPLC steps. Automated Edman degradation showed that the N-terminal sequence of the antibacterial protein was NH2-Ile-Gln-Arg-Thr-Pro-Lys-Ile-Gln-Val-Tyr-Ser-Arg-His-Pro-Ala-Glu-Asn-Gly-. The N-terminal sequence of the antibacterial protein was found to be identical to that of β2-microglobulin, a component of MHC class I molecules, which are present on all nucleated cells. Matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) revealed that the molecular mass of the antibacterial protein was 11,631 Da. This antibacterial protein, β2M, possessed potent antibacterial activity against pathogenic bacteria. Specially, antibacterial activity was observed in potassium buffer, and potassium ion was found to be critical for the antibacterial activity. Interestingly, the antibacterial action of β2M was associated with dissipation of the transmembrane potential, but the protein did not cause damage to the membrane that would result in SYTOX green uptake. In addition, stimulation of WISH amniotic epithelial cells with the bacterial endotoxin lipopolysaccharide (LPS) induced dose-dependent upregulation of β2M mRNA expression. These results suggest that β2M contributes to a self-defense response when amniotic cells are exposed to pathogens.

Residual Antibiotics in Decontaminated Human Cardiovascular Tissues Intended for Transplantation and Risk of Falsely Negative Microbiological Analyses

“…Tissue samples decontaminated with antibiotic cocktails are a specific type of microbiological sample that may present bacteriostatic and/or fungistatic properties [8] , [15] . The intrinsic properties of the tissues, such as enzymatic activity, immunologic events, and presence of antimicrobial peptides [16] , which are well described in the skin [17] , cornea [18] , and amniotic membrane [19] , may be exacerbated by the presence of residual antibiotics following tissue decontamination with antibiotic cocktails [7] , [8] , [20] . The European and US Pharmacopoeias indicate eliminating any factor that may interfere with microbial growth during sterility testing from samples [9] , [10] .…”

PG-2, a Potent AMP against Pathogenic Microbial Strains, from Potato (Solanum tuberosum L cv. Gogu Valley) Tubers Not Cytotoxic against Human Cells

“…A 16.5% tricine acrylamide gel, based on the formulation of Schagger and von Jagow [20], was used to resolve the peptide isolated by HPLC. Samples were diluted to 0.5 mg/mL in sample buffer containing 0.5% ( w / v ) SDS, 50 mM Tris-HCl, pH 6.8, 12% ( v / v ) glycerol, 2% 2-mercaptoethanol and 0.01% Brilliant Blue G, after which samples containing 10 μg of protein were loaded into each well, and electrophoresis was carried out at 25 mA for approximately 3 h in running buffer composed of 0.1 M Tris-HCl, 0.1 M tricine and 0.1% ( w / v ) SDS.…”

Molecular insights into post‐mating immune response in a fish with internal fertilization

“…In human placenta, the binding of Fas ligand to its receptor on activated immune cells, which results in cells apoptosis, plays an important immune‐regulatory role in limiting the host immune response (Kauma, Huff, Hayes, & Nilkaeo, 1999). Interestingly, B2M encodes an antimicrobial protein that in humans exhibits antibacterial activity in amniotic fluid (Kim et al, 2012). GSEA highlighted additional differentially expressed gene sets associated with immunity, such as ‘NF‐kB signalling pathway’, ‘signal transduction through IL1R’, ‘selective expression of chemokine receptors during T‐cell polarization’ and ‘antigen processing and presentation’, which were all up‐regulated.…”