荚膜多糖(CPS)作为益生菌成分具有调节宿主免疫系统功能的能力。然而,热镇静CPS的结构和功能如何改变仍不清楚。在本研究中,从活的(LCPS)和热灭活的(HCPS)副干酪乳杆菌6235中分离并纯化CPS。比较分析了LCPS和HCPS在结构和免疫调节方面的差异。结果表明,热杀死后,CPS的分子量从23.4kDa下降到17.5kDa,随着单糖成分中半乳糖胺的消失,和微观结构的变化。甲基化分析和核磁共振分析显示LCPS和HCPS结构相似,→3,4)-α-D-Glcp-(1→4)-α-D-Galp-(1→3)-β-L-Rhap-(1→6)-β-D-Galp-(1→,和重复单元→3,4)-α-D-Glcp-(1→,→3)-β-L-Rhap-(1→,和→4)-α-D-Galp-(1→残基。此外,LCPS和HCPS均显著下调LPS诱导的RAW264.7细胞中促炎细胞因子的表达。具体来说,HCPS降低IL-6和IL-1β水平分别为79.38%和88.42%,分别,与LCPS相比。同时,LCPS和HCPS均通过NF-κB和MAPK信号通路有效缓解炎症反应。此外,与LCPS相比,HCPS使NF-κB/p-NF-κB和IκB/p-IκB的蛋白表达分别增加26.14%和28.92%,分别。这些结果表明CPS在调节免疫应答中起作用,并且HCPS更有效。这项研究可以进一步开发与postbiotics相关的新产品。
Capsular polysaccharide (CPS) as a probiotic component has the ability to regulate the function of the host\'s immune system. However, how the structure and function of heat-killed CPS are altered remains unclear. In the present study, CPS were isolated and purified from live (LCPS) and heat-killed (HCPS) Lacticaseibacillus paracasei 6235. The differences in structure and immunomodulation between LCPS and HCPS were compared and analyzed. The results demonstrate that after heat killed, the molecular weight of CPS decreased from 23.4 kDa to 17.5 kDa, with the disappearance of galactosamine in the monosaccharide composition, and changes in the microstructure. Methylation analysis and nuclear magnetic resonance analysis revealed that the LCPS and HCPS are similar in structure, which main units of →3,4)-α-D-Glcp-(1→4)-α-D-Galp-(1→3)-β-L-Rhap-(1→6)-β-D-Galp-(1→, and repeating units of →3,4)-α-D-Glcp-(1→, →3)-β-L-Rhap-(1→, and →4)-α-D-Galp-(1→ residues. Furthermore, both LCPS and HCPS significantly downregulated the expression of pro-inflammatory cytokines in RAW264.7 cells induced by LPS. Specifically, HCPS reduced the levels of IL-6 and IL-1β by 79.38 % and 88.42 %, respectively, compared to LCPS. Concurrently, both LCPS and HCPS effectively mitigated inflammatory responses through the NF-κB and MAPK signaling pathways. Moreover, compared to LCPS, HCPS increased the protein expression levels of NF-κB/p-NF-κB and IκB/p-IκB by 26.14 % and 28.92 %, respectively. These results suggest that CPS has a role in modulating immune responses and that HCPS is more effective. This study can be further developed into new products related to postbiotics.