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Isolation of Manganese-Containing Superoxide Dismutases
Published in Robert A. Greenwald, CRC Handbook of Methods for Oxygen Radical Research, 2018
Eugene M. Gregory, Charles D. Pennington
Manganese-containing superoxide dismutases (MnSOD) have been purified from diverse sources, including aerobic bacteria,1,2 yeast,3 rat and bovine liver mitochondria,4,5 and pea leaves.6 A detailed scheme for purification of MnSOD from Bacteroides thetaiotaomicron, a Gram-negative nonspore-forming anaerobe common to the gut of man and other animals, is presented here. These bacteria actually synthesize an FeSOD during their anaerobic growth, but they produce a MnSOD upon aeration of the culture.7 The purification of B. thetaiotaomicron MnSOD demonstrates the logic used in purifying an enzyme from a crude cell extract, but the sequence presented here cannot be assumed to be valid for purification of every MnSOD. A brief reveiw of procedures different from those used with B. thetaiotaomicron MnSOD is therefore also included.
Eravacycline
Published in M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson, Kucers’ The Use of Antibiotics, 2017
Table 72.3 displays the in vitro activity of eravacycline against anaerobic bacteria (Sutcliffe et al., 2010; Sutcliffe et al., 2013; Morrissey et al., 2015f; McDermott et al., 2015; Fyfe et al., 2011). In addition, in vitro susceptibility testing results for baseline Gram-positive and Gram-negative anaerobic pathogens (n = 17) are available for the microbiologically evaluable patient population enrolled in the phase II clinical trial for the treatment of community-acquired complicated intra-abdominal infections (Solomkin et al., 2014). Eravacycline has MIC90 values ≤ 1 mg/l against most anaerobic pathogens. Higher MIC90 values of 2 and 4 mg/l have occasionally been reported for Bacteroides spp. (e.g. Bacteroides ovatus, Bacteroides thetaiotaomicron, Bacteroides fragilis) and Clostridium perfringens. The eravacycline MIC50 and MIC90 values against most anaerobic species tend to show that eravacycline is two- to eightfold more potent against these species than tigecycline, and two- to fourfold more potent against these species than ertapenem (Zhanel et al., 2016; Solomkin et al., 2014).
Human Gut Microbiota–Transplanted Gn Pig Models for HRV Infection
Published in Lijuan Yuan, Vaccine Efficacy Evaluation, 2022
The mean relative abundance of phyla between UHGM pig LIC samples and the infant stool sample (PM25) was similar, which was as expected. However, HHGM pig samples differed from their infant donor (SV14). Community structure may have been different between the human donor and pigs because of the influence of different environments, differences in diet, lack of natural microbial succession in the pigs, or differences in host genetics (Schmidt et al., 2011). The phylum- and genus-level differences between HHGM and UHGM pigs at both time points warrant further study to assess the influences of these OTUs on the host immune response. In HHGM pigs, after VirHRV challenge, there was a decrease in the relative abundance of Firmicutes, similar to previous observations (Zhang et al., 2014). Although we did not sample pigs without AttHRV vaccination, human studies have shown that rotavirus vaccination does not have any major effects on the gut microbiota of children (Ang et al., 2014; Garcia-Lopez et al., 2012). Similar to a human study, HHGM pigs had an increased mean relative abundance of Bacteroides after rotavirus infection (Zhang et al., 2009). Bacteroides and Lactobacillus species have been shown to modify cell-surface glycans in human intestinal cultured cells, effectively blocking rotavirus infection (Varyukhina et al., 2012). This may partially explain why HHGM pigs had decreased viral shedding when compared to UHGM pigs. In agreement with a previous study, we also observed a decrease in levels of Streptococcus in HHGM pigs after the rotavirus challenge (Zhang et al., 2014). There is limited data on mechanisms by which microbiota directly influences enteric virus infectivity. Microbiota may modify the cell surface or bind to pathogens. In vitro experiments have demonstrated soluble factors from Bacteroides thetaiotaomicron and Lactobacillus casei can increase cell-surface galactose and block rotavirus infection (Varyukhina et al., 2012). Poliovirus binds bacterial surface polysaccharides, which enhances virion stability and cell attachment, and may enhance transmission (Robinson et al., 2014). Gnotobiotic pigs colonized with E. coli Nissle 1917 (EcN) had lower viral shedding titers, which the authors speculated was because EcN bound to HRV particles (Kandasamy et al., 2016).
Targeting the gut microbial metabolic pathway with small molecules decreases uremic toxin production
Published in Gut Microbes, 2020
Yingyi Wang, Jianping Li, Chenkai Chen, Jingbo Lu, Jingao Yu, Xuejun Xu, Yin Peng, Sen Zhang, Shu Jiang, Jianming Guo, Jinao Duan
Bacteroides thetaiotaomicron (B. theta) also exists in the intestine and can produce indole. B. theta was incubated with ISO for 2– 24 h, and the inhibitory effect of ISO on indole production was evaluated. We found that the ISO-mediated inhibition of indole synthesis was abolished when co-incubated with B. theta (Figure 6e). However, quercetin was still able to inhibit indole production in B. theta, which is consistent with the effect of quercetin on E. coli. We hypothesized that ISO could not be hydrolyzed by B. theta and, therefore, could not inhibit indole production. Next, we evaluated the hydrolysis profile of ISO in B. theta. Consistent with our hypothesis, ISO was not hydrolyzed during co-incubation with B. theta (figure 6f). Therefore, ISO does not inhibit indole synthesis in B. theta, thereby supporting the hypothesis that glycoside hydrolysis is critical for the inhibitory effects of flavonoid glycosides.
Elucidating the gut microbiota composition and the bioactivity of immunostimulatory commensals for the optimization of immune checkpoint inhibitors
Published in OncoImmunology, 2020
Romain Daillère, Bertrand Routy, Anne-Gaëlle Goubet, Alexandria Cogdill, Gladys Ferrere, Carolina Alves-Costa Silva, Aurélie Fluckiger, Pierre Ly, Yacine Haddad, Eugenie Pizzato, Cassandra Thelemaque, Marine Fidelle, Marine Mazzenga, Maria Paula Roberti, Cléa Melenotte, Peng Liu, Safae Terrisse, Oliver Kepp, Guido Kroemer, Laurence Zitvogel, Lisa Derosa
The first bacterial species known to harbor “zwitterionic” peptides capable of engaging CD4+ T cell receptors was Bacteroides fragilis.80–82 B. fragilis was very effective in boosting immune responses primed in the setting of sarcoma tumors treated with anti-CTLA4 Ab23 as well as colon carcinoma treated with oxaliplatin-based immunogenic chemotherapy.51 Antibiotics blunted the anticancer efficacy of CTLA-4 blockade against various transplantable tumors unless oral supplementation with B. fragilis was performed, which reinstated IL-12-dependent Th1 immune responses. Interestingly, anti-CTLA-4 Abs administered to tumor-bearing avatar mice reconstituted with FMT from melanoma patients foster the overrepresentation of distinct Bacteroides spp. (Bacteroides fragilis or Bacteroides thetaiotaomicron) and recapitulated the phenotype of response observed in patient.23 Interestingly, oral supplementation with B. fragilis (as opposed to Fusobacterium nucleatum or Paraprevotella clara) turned chemotherapy-induced tolerogenic ileal apoptosis into immunogenic cell demise capable of eliciting PD1high follicular helper T cells and B cell responses and of promoting the efficacy of anti-PD1 Abs against established colon cancers.51 Hence, the ileal microbiota enriched in commensals playing the role of adjuvant for ileal apoptosis triggered TFH and the efficacy of PD-1 blockade, even in tumors devoid of neoantigens.
Metagenomic analysis of the human microbiome reveals the association between the abundance of gut bile salt hydrolases and host health
Published in Gut Microbes, 2020
Baolei Jia, Dongbin Park, Yoonsoo Hahn, Che Ok Jeon
High-fat diets increase the levels of BAs in the gut. The BA concentration can reach 1 mM in the middle gut after the intake of a high-fat meal.32,33 The abundance of Firmicutes is shown to increase and the abundance of Bacteroidetes is shown to decrease in the guts of both a mouse model with high-fat diet-induced obesity or humans with obesity, compared to the respective lean control subjects.34 High-level expression of recombinant BSH in conventionally raised mice leads to a significant reduction in conjugated BAs, plasma cholesterol, liver triglycerides, and host weight gain,35 suggesting that BSH is an important target to regulate host lipid metabolism and weight gain. Our analysis showed that the abundance of BSHs from Firmicutes (Cluster 2 and 4) was not associated with obesity and T2D. In contrast, the BSHs from Cluster 1 and Cluster 3, which contain N-terminal signal peptides and are predominantly from Proteobacteria and Bacteroidetes, increased significantly in the patients with T2D and obesity, respectively, suggesting that BSHs from Proteobacteria or Bacteroidetes may contribute immensely to host health. This result is in accordance with the previous study which showed that the BSH with signal peptide from Bacteroides thetaiotaomicron can alter the in vivo BA pool and exert significant effects on the host metabolic status.5 Considering the significance of probiotics with BSH activity as a possible approach to prevent and treat obesity, we propose that the bacteria with BSH activity belonging to Bacteroidetes but not Firmicutes can be potential probiotics to ameliorate obesity.