1 Department of Bioscience Engineering, Research Group Environmental Ecology and Applied Microbiology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
2 Department of Pediatrics, Division of Host-Microbe Systems and Therapeutics, University of California, San Diego, 9500 Gilman Drive, MC 0760, La Jolla, CA 92093-0760, USA.
Benef Microbes. 2018 Apr 25;9(3):429-439. doi: 10.3920/BM2017.0101. Epub 2018 Apr 10.
Probiotics, mainly lactic acid bacteria (LAB), are widely focused on gastrointestinal applications. However, recent microbiome studies indicate that LAB can be endogenous members of other human body sites such as the upper respiratory tract (URT). Interestingly, DNA-based microbiome research suggests an inverse correlation between the presence of LAB and the occurrence of potential pathogens, such as Moraxella catarrhalis, an important URT pathogen linked to otitis media, sinusitis and chronic obstructive pulmonary disease. However, a direct interaction between these microbes has not been explored in detail. This study investigated the direct antipathogenic effects of Lactobacillus species, including several well-documented probiotic strains, on M. catarrhalis using agar-based assays, time course analysis, biofilm assays and minimal inhibitory concentration (MIC) testing. These assays were performed using spent culture supernatans (SCS) at two pHs (4.3 and 7) and D- and/or L-lactic acid at three pHs (2, 4 and 7). In addition, cell line assays for adhesion competition and immunomodulation were used to substantiate the inhibitory effect of lactobacilli against M. catarrhalis. A proportion of Lactobacillus strains, including the model probiotic Lactobacillus rhamnosus GG, showed a strong and direct activity against M. catarrhalis. Screening of the activity of the SCS after different treatments demonstrated that lactic acid has an important antimicrobial activity against this pathogen - at least in vitro - with mean MIC values for D- and L-lactic acid varying between 0.5 and 27 g/l depending on the pH. Furthermore, L. rhamnosus GG also decreased the adhesion of M. catarrhalis to human airway epithelial Calu-3 cells with more than 50%, and the expression of mucin MUC5AC, pro-inflammatory cytokines interleukin (IL)-8, IL-1β, and tumor necrosis factor-α at least 1.2 fold. This study suggests that several lactobacilli and their key metabolite lactic acid are possible candidates for probiotic therapeutic interventions against URT infections.
益生菌主要是乳酸菌（LAB），广泛应用于胃肠道。然而，最近的微生物组研究表明，LAB 可以成为人体其他部位的内源性成员，如上呼吸道（URT）。有趣的是，基于 DNA 的微生物组研究表明，LAB 的存在与潜在病原体的发生呈负相关，例如卡他莫拉菌（Moraxella catarrhalis），它是一种与中耳炎、鼻窦炎和慢性阻塞性肺疾病有关的重要 URT 病原体。然而，这些微生物之间的直接相互作用尚未得到详细探讨。本研究使用琼脂基础测定、时程分析、生物膜测定和最小抑菌浓度（MIC）试验，研究了包括几种有充分文献记载的益生菌株在内的乳杆菌属对 M. catarrhalis 的直接抗病原体作用。这些测定使用两种 pH 值（4.3 和 7）下的废弃培养上清液（SCS）和三种 pH 值（2、4 和 7）下的 D-和/或 L-乳酸进行。此外，还使用细胞系测定进行了粘附竞争和免疫调节测定，以证实乳杆菌对 M. catarrhalis 的抑制作用。包括模型益生菌 Lactobacillus rhamnosus GG 在内的一部分乳杆菌菌株对 M. catarrhalis 表现出强烈的直接活性。对不同处理后的 SCS 活性的筛选表明，乳酸对这种病原体具有重要的抗菌活性-至少在体外如此-其 D-和 L-乳酸的平均 MIC 值因 pH 值而异，介于 0.5 和 27 g/l 之间。此外，L. rhamnosus GG 还使 M. catarrhalis 对人气道上皮细胞 Calu-3 的粘附减少了 50%以上，并且至少使粘蛋白 MUC5AC、促炎细胞因子白细胞介素（IL）-8、IL-1β和肿瘤坏死因子-α的表达增加了 1.2 倍以上。本研究表明，几种乳杆菌及其关键代谢产物乳酸可能是针对 URT 感染的益生菌治疗干预的候选物。
