Oral lichen planus (OLP) is a T cell-mediated common chronic inflammatory mucosal disease, with limited therapies available for long-term use. Previous study showed that ratio of genus Streptococcus decreased significantly in OLP patients when compared with controls. Buccal cotton swab samples of 43 OLP patients and 48 healthy individuals were collected for real-time quantitative polymerase chain reaction (RT-PCR) to investigate relative abundance alteration of Streptococcus salivarius in OLP lesions. Bacterial supernatants of S. salivarius ATCC® BAA-2593™ were collected by centrifugation and added to HSC-3 cells, and quantitative analysis of expression of IL-1β, IL-6, IL-8, and TNF-α in the HSC-3 cells was determined by RT-PCR. Then, a randomized, non-blinded, controlled study was conducted. Forty patients with symptomatic OLP were randomly allocated into two groups and received topical treatment of 0.1% triamcinolone acetonide dental paste (group A) and S. salivarius K12 lozenge (group B), respectively, for 4 weeks. Sign scores, visual analogue scale (VAS), and adverse reactions were recorded. Relative abundance of S. salivarius in the OLP group was lower than that of control group (P < 0.05). After treated with 0.1% supernatants of S. salivarius ATCC® BAA-2593™, the expression level of IL-6 in the HSC-3 cells significantly reduced (P < 0.001), while IL-1β, IL-8, and TNF- α showed a decreasing tendency (P > 0.05). There was significant reduction in sign scores and VAS scores in both groups after the 4-week treatment, with no significant difference between two groups. No adverse reaction was observed. S. salivarius might maintain local immune balance by inhibiting the NF-κB pathway. Topical application of Streptococcus salivarius K12 seemed to be effective in treatment of symptomatic OLP, especially with promising potential in long-term use. More detailed clinical studies with long follow-up period and standardized usage/dosage are expected to acquire definite conclusions.

口腔扁平苔藓（OLP）是T细胞介导的常见慢性炎性粘膜疾病，可长期使用的疗法有限。先前的研究表明，与对照组相比，OLP患者链球菌属的比例显着下降。收集43例OLP患者和48例健康个体的颊棉签样本进行实时定量聚合酶链反应（RT-PCR），以研究唾液链球菌在OLP病变中的相对丰度变化。唾液链球菌细菌上清液通过离心收集ATCC®BAA-2593™并添加到HSC-3细胞中，并通过RT定量分析HSC-3细胞中IL-1β，IL-6，IL-8和TNF-α的表达。 -PCR。然后，进行了一项随机，非盲对照研究。将40名有症状OLP的患者随机分为两组，分别接受0.1％曲安奈德丙酮糊剂（A组）和唾液链球菌K12锭剂（B组）的局部治疗，持续4周。记录体征得分，视觉模拟量表（VAS）和不良反应。OLP组唾液链球菌的相对丰度低于对照组（P  <0.05）。用0.1％唾液链球菌上清液处理后ATCC®BAA-2593™，HSC-3细胞中IL-6的表达水平显着降低（P  <0.001），而IL-1β，IL-8和TNF-α则呈下降趋势（P  > 0.05） 。治疗4周后，两组的体征评分和VAS评分均显着降低，两组之间无显着差异。没有观察到不良反应。唾液链球菌可能通过抑制NF-κB途径维持局部免疫平衡。唾液链球菌K12的局部应用似乎可有效治疗有症状的OLP，尤其是在长期使用中具有广阔的前景。长期随访和标准用法/剂量的更详细的临床研究有望获得明确的结论。