Saad Gewa, Azrad Maya, Aias Meral, Leshem Tamar, Hamo Zohar, Rahmoun Layan Abu, Peretz Avi
Azrieli Faculty of Medicine, Bar Ilan University, Safed, 1311502, Israel.
Clinical Microbiology Laboratory, Tzafon Medical Center, Poriya, Tiberias 1528001, Israel.
Heliyon. 2023 Feb 17;9(3):e13846. doi: 10.1016/j.heliyon.2023.e13846. eCollection 2023 Mar.
is the most common infectious agent of nosocomial diarrhea. infection (CDI) pathogenesis and disease severity depend on its toxins (toxins A, B and binary) and on the host's immune response, especially the innate immune system. The current study examined the efficacy of macrophage activity, macrophages viability and cytokine secretion levelsin response to different sequence type (ST) strains of .
RAW 264.7 macrophages were exposed to six different strains of as well as to both toxins A and B and macrophage viability was measured. The levels of four secreted cytokines were determined by RT-PCR and ELISA. Morphological changes to the macrophages were investigated by fluorescent microscopy.
Strains ST37 and ST42 affected macrophages' vitality the most. Toxins A and B led to a significant reduction in macrophages' vitality at most time points. In addition, starting at 30-min post-exposure to 5 ng/μl of both toxins led to significant differences in macrophage viability versus at lower concentrations. Furthermore, cytokine secretion levels, including IL-12, IL-6 and TNF-α, increased dramatically when macrophages were exposed to strains ST42 or ST104. Finally, gene expression surveys point to increases in IL-12 gene expression in response to both ST42 and ST104.
strains with higher toxins levels induced an increased activation of the innate immune system and may activate macrophages more profoundly resulting in secretion of higher levels of pro-inflammatory cytokines. However, higher toxin levels may also damage macrophages' normal skeletal structure, reducing macrophage viability.
艰难梭菌是医院获得性腹泻最常见的感染病原体。艰难梭菌感染（CDI）的发病机制和疾病严重程度取决于其毒素（毒素A、B和二元毒素）以及宿主的免疫反应，尤其是先天免疫系统。本研究检测了巨噬细胞活性、巨噬细胞活力和细胞因子分泌水平对不同序列类型（ST）的艰难梭菌菌株的反应。
将RAW 264.7巨噬细胞暴露于六种不同的艰难梭菌菌株以及毒素A和B，然后测量巨噬细胞活力。通过RT-PCR和ELISA测定四种分泌细胞因子的水平。通过荧光显微镜观察巨噬细胞的形态变化。
ST37和ST42菌株对巨噬细胞活力的影响最大。毒素A和B在大多数时间点导致巨噬细胞活力显著降低。此外，在暴露于5 ng/μl的两种毒素后30分钟开始，与较低浓度相比，巨噬细胞活力存在显著差异。此外，当巨噬细胞暴露于ST42或ST104菌株时，细胞因子分泌水平，包括IL-12、IL-6和TNF-α显著增加。最后，基因表达调查表明，对ST42和ST104的反应中IL-12基因表达增加。
毒素水平较高的艰难梭菌菌株可诱导先天免疫系统的激活增加，并可能更深刻地激活巨噬细胞，导致更高水平的促炎细胞因子分泌。然而，较高的毒素水平也可能损害巨噬细胞的正常骨架结构，降低巨噬细胞活力。
