Danielsson Niemi L, Hernell O, Johansson I
Department of Odontology/Cariology, Umeå University, Umeå, Sweden.
Caries Res. 2009;43(3):171-8. doi: 10.1159/000213888. Epub 2009 Apr 23.
Acquisition of mutans streptococci at an early age is a risk factor for later caries development. Following our recent finding that human milk may inhibit adhesion of Streptococcus mutans the aim of the present study was to identify compounds in human milk preventing adhesion of mutans streptococci to saliva- or gp340-coated hydroxyapatite (s-HA and gp340-HA) using an in vitro model system. Superdex 200 fractions of human milk and purified proteins were screened for binding inhibition of the S. mutans strain Ingbritt. Avid inhibition was seen to both s-HA and gp340-HA for caseins, lactoferrin, IgA and IgG, and moderate inhibition for alpha-lactalbumin and bile salt-stimulated lipase, whereas albumin and lysozyme had no effect. The inhibitory epitope in beta-casein was delineated to its C-terminal LLNQELLNPTHQIYPVTQPLAPVHNPISV stretch by use of synthetic peptides. Similarly, a peptide (SCKFDEYFSQSCA) corresponding to the human lactoferrin stretch that is highly homologous to the previously shown inhibitory stretch of bovine lactoferrin was found to inhibit S. mutans Ingbritt binding. Inhibition by human milk, IgA, and the inhibitory beta-casein peptide was universal among 4 strains of S. mutans (Ingbritt, NG8, LT11, JBP) and 2 strains of S. sobrinus (6715 and OMZ176). IgG inhibited 4, alpha-lactalbumin 3 and lactoferrin 2 of these 6 strains. It was also confirmed that none of the milk components coated on HA mediated S. mutans Ingbritt adhesion, which was consistent with the finding that no milk protein was recognized on Western blots by gp340/DMBT1 monoclonal antibodies.
幼年时期获得变形链球菌是日后发生龋齿的一个风险因素。基于我们最近发现人乳可能抑制变形链球菌的黏附这一结果，本研究的目的是使用体外模型系统，鉴定人乳中可防止变形链球菌黏附于唾液包被或gp340包被的羟基磷灰石（s-HA和gp340-HA）的化合物。对人乳的Superdex 200级分和纯化蛋白进行筛选，以检测其对变形链球菌英布里特菌株黏附的抑制作用。发现酪蛋白、乳铁蛋白、IgA和IgG对s-HA和gp340-HA均有显著抑制作用，α-乳白蛋白和胆汁盐刺激的脂肪酶有中度抑制作用，而白蛋白和溶菌酶则无作用。通过使用合成肽，将β-酪蛋白中的抑制性表位定位到其C末端的LLNQELLNPTHQIYPVTQPLAPVHNPISV片段。同样，发现一段与人乳铁蛋白片段相对应的肽（SCKFDEYFSQSCA），该片段与先前显示的牛乳铁蛋白抑制片段高度同源，可抑制变形链球菌英布里特菌株的黏附。人乳、IgA和抑制性β-酪蛋白肽的抑制作用在4株变形链球菌（英布里特、NG8、LT11、JBP）和2株远缘链球菌（6715和OMZ176）中具有普遍性。IgG抑制了这6株菌株中的4株，α-乳白蛋白抑制了3株，乳铁蛋白抑制了2株。还证实，包被在HA上的任何乳成分均未介导变形链球菌英布里特菌株的黏附，这与gp340/DMBT1单克隆抗体在蛋白质印迹上未识别出乳蛋白的结果一致。
