Protective effect of emodin on Streptococcus pneumoniae and matrix-assisted laser desorption time-of-flight mass spectrometry for serotype detection

Abstract

This study assessed the impact of emodin on Streptococcus pneumoniae serotype using Matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF MS) technology. After establishment of animal models, rats were classified into sham operation group, model group, low-dose and high-dose emodin group (n = 10, each group). After treatment, the pathology of rat lung tissue was detected along with analysis of the levels of Interleukin-1β, IL-1β(IL-1β), Tumor Necrosis Factor alpha (TNF-α), and IL-6. MALDI-TOF MS was used to examine the serotype of Streptococcus pneumoniae as NF-κB level in the rat lung tissue and capsular polysaccharide protein levels were detected. Compared with healthy tissues, the lung tissues in the model group exhibited collapse of alveoli and infiltration of inflammatory cells, which were greatly alleviated in low-dose and high-dose emodin groups, with more significant effect in high-dose emodin group. Additionally, treatment with emodin dramatically decreased the contents of IL-1β, TNF-α and IL-6 (P <0.05), which were lowest in the high-dose group. 60 representative strains of Streptococcus pneumoniae were divided into 18 mass spectrum types, whilst six serotypes (19F, 19A, 23F, 23A, 3 and 14) were identified. Moreover, 18 strains of serotype 19F accounted for 30% (18/60) and were distributed in 6 different MALDI-TOF MS types, and another 3 serotypes were distributed in the corresponding MALDI-TOF MS types. NF-κB and capsular polysaccharide protein expressions declined after emodin treatment (P <0.05). Collectively, Emodin effectively alleviated infection caused by Streptococcus pneumoniae and inflammatory response and improved conditions of patients while decreasing their levels of NF-κB and capsular polysaccharide protein, affecting typing of Streptococcus pneumoniae.