ABSTRACT
T he epithelium acts as a first barrie r o f defence against potentia lly pathogenic m icroorganism s, essentially by creating an in te rface betw een ex te rna l an d in te rn a l environm ents. Additionally, epithelial cells are involved in the expression o f an tim icro bial peptides, cytokine p roduction and have an active im m u n o lo g ica l ro le inc lud ing antigen processing and presentation . The production o f antim icrobial peptides m ay be considered as an active ingredient o f the protective ‘epithelial wall.’ For exam ple the defensin fam ily o f antim icrobial peptides have recently been identified in tracheal and gastrointestinal m ucosa.1,2 A drenom edullin (ADM) is sim ilar to calcitonin gene-related peptide (CGRP) in term s o f effects in v itro and in vivo, and m odest structu ra l sim ilar ity. Plasm a levels o f CGRP are difficult to m easure (except in the case o f neuroendo crine tum ours). Plasm a concentrations o f ADM , on the o ther hand , are know n to rise in a v a rie ty o f p a th o lo g ic a l co n d itio n s including sepsis.3 The aim o f this study was to investigate the an tim icrob ial effects o f ADM and CGRP based on these observa tions. Supporting evidence for an an tim i crobial role by ADM , in particular, is seen by the accum ulation o f this peptide at the apical regions o f norm al h um an bronchial epithelium and h um an skin.4,5
25.2. Methods and Materials U nless s ta ted o rgan ism s u sed w ere
CGRP/ADM was used to soak W hatm an (G rade AA) 6m m discs to give a concentra tion o f 3.5 μg for each disc. Bacterial sus pensions were m ade to a density o f 2 x l0 7 colony form ing units (CFU)/m l. Blood agar base w ith defibrinated horse blood (5% v/v) was seeded using a swab m oistened in the bacteria l suspension and the discs placed on to the surface o f the agar. The plates were incubated at 37°C in the air w ith 5% CO 2 for 24h. In the case o f B.fragilisy P gingivalis and R acnes incubation was under anaerobic conditions (80% N 2; 10% C 0 2; 10% H v/v) for 48 h at 37°C. In the case o f H. pylori incubation conditions were m icroaerophilic (85% N 2; 10% C 0 2; 5% 02 v/v) for 48 h at 37°C. All determ inations were carried ou t in triplicate.
