Faecalibacterium prausnitzii (formerly known as Fusobacterium prausnitzii), present in Clostridium cluster IV, is the most abundant bacterium in healthy gut microbiota representing more than 5% of bacterial population[40]. They are widely spread in the gastrointestinal tract of humans and some other species such as pigs, mice and calves and are functionally highly active organisms. F. prausnitzii is an extremely oxygen sensitive(EOS) bacterium and is difficult to cultivate even in anaerobic conditions. They ferment glucose and produce formate, lactate and mainly butyrate[40]. Butyrate is an important SCFA in colonocytes development and gut homeostasis regulation. It has an anti-inflammatory activity in colon mucosa and can modulate the host immune system. The abundance of F. prausnitzii is being considered as an indicator of intestinal health and depletion of this bacteria was revealed in studies of IBD patients. The causality is not fully known. Since a decline in number of F.
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prausnitzii is not fully understood. However, it was observed that specific F. prausnitzii strain, A2-165 in comparing with others[41], highly induces IL-10 secretion in human peripheral blood mononuclear cells (hPBMCs) and hardly stimulates IL-12 production in cellular model and consequently attenuates the symptoms of TNBS-induced colitis in a mouse model[42]. Indeed, the IL-10/IL-12 ratio is modulated by affecting the dendritic cells (DCs) and induction of T cells subsets in the mucosal lymphoid tissue[41, 43]. The IL-10 and TGF-B enriched environment, enhances differentiation of Naïve CD4+ T cells into Tregs. Besides, it is also believed that by means of some not fully identified molecules, this bacteria is capable of dampening IL-8 production via an inhibitory effect on NF-kB transcription factor. Although some evidence about the role of extracellular polymeric matrix in cytokine modulation is available, further investigations seem crucial
prausnitzii is not fully understood. However, it was observed that specific F. prausnitzii strain, A2-165 in comparing with others[41], highly induces IL-10 secretion in human peripheral blood mononuclear cells (hPBMCs) and hardly stimulates IL-12 production in cellular model and consequently attenuates the symptoms of TNBS-induced colitis in a mouse model[42]. Indeed, the IL-10/IL-12 ratio is modulated by affecting the dendritic cells (DCs) and induction of T cells subsets in the mucosal lymphoid tissue[41, 43]. The IL-10 and TGF-B enriched environment, enhances differentiation of Naïve CD4+ T cells into Tregs. Besides, it is also believed that by means of some not fully identified molecules, this bacteria is capable of dampening IL-8 production via an inhibitory effect on NF-kB transcription factor. Although some evidence about the role of extracellular polymeric matrix in cytokine modulation is available, further investigations seem crucial