Shared gut, but distinct oral microbiota composition in primary Sjögren's syndrome and systemic lupus erythematosus.

OBJECTIVE: Alterations in the microbiota composition of the gastro-intestinal tract are suspected to be involved in the etiopathogenesis of two closely related systemic inflammatory autoimmune diseases: primary Sjögren's syndrome (pSS) and systemic lupus erythematosus (SLE). Our objective was to assess whether alterations in gut and oral microbiota compositions are specific for pSS and SLE. METHODS: 16S ribosomal RNA gene sequencing was performed on fecal samples from 39 pSS patients, 30 SLE patients and 965 individuals from the general population, as well as on buccal swab and oral washing samples from the same pSS and SLE patients. Alpha-diversity, beta-diversity and relative abundance of individual bacteria were used as outcome measures. Multivariate analyses were performed to test associations between individual bacteria and disease phenotype, taking age, sex, body-mass index, proton-pump inhibitor use and sequencing-depth into account as possible confounding factors. RESULTS: Fecal microbiota composition from pSS and SLE patients differed significantly from population controls, but not between pSS and SLE. pSS and SLE patients were characterized by lower bacterial richness, lower Firmicutes/Bacteroidetes ratio and higher relative abundance of Bacteroides species in fecal samples compared with population controls. Oral microbiota composition differed significantly between pSS patients and SLE patients, which could partially be explained by oral dryness in pSS patients. CONCLUSIONS: pSS and SLE patients share similar alterations in gut microbiota composition, distinguishing patients from individuals in the general population, while oral microbiota composition shows disease-specific differences between pSS and SLE patients.

Dysbiosis of the buccal mucosa microbiome in primary Sjögren's syndrome patients.

Objectives: Environmental factors in the aetiology of primary Sjögren's syndrome (pSS) are largely unknown. Host-microbiome interaction at mucosal surfaces is presumed to be involved in the aetiopathogenesis of pSS. Here, we assessed whether the microbiome of the buccal mucosa is specific for pSS compared with symptom-controls. Methods: The bacterial composition of buccal swab samples from 37 pSS patients, 86 non-SS sicca patients (with similar dryness symptoms to pSS patients, but not fulfilling the classification criteria) and 24 healthy controls (HCs) was determined with 16S rRNA sequencing. Multivariate Association with Linear Models was used to find associations between individual taxa and pSS, taking into account smoking and dental status. Associations were replicated in a general population cohort (n = 103). Results: The buccal mucosa microbiome of pSS and non-SS sicca patients both differed from HCs. A higher Firmicutes/Proteobacteria ratio was characteristic for both pSS and non-SS sicca patients. Disease status (pSS, non-SS sicca, HCs) and salivary secretion rate contributed almost equally to the variation in bacterial composition between individuals (3.8 and 4.3%, respectively). Two taxa were associated with pSS compared with non-SS sicca patients and 19 compared with HCs. When salivary secretion rate was taken into account, no taxon was associated with pSS compared with non-SS sicca. Twelve of the 19 pSS-associated taxa were correlated with salivary secretion. Conclusion: Dysbiosis of the buccal mucosa microbiome in pSS patients resembles that of symptom-controls. The buccal mucosa microbiome in pSS patients is determined by a combination of reduced salivary secretion and disease-specific factors.

Patient attitudes towards faecal sampling for gut microbiome studies and clinical care reveal positive engagement and room for improvement.

Faecal sample collection is crucial for gut microbiome research and its clinical applications. However, while patients and healthy volunteers are routinely asked to provide stool samples, their attitudes towards sampling remain largely unknown. Here, we investigate the attitudes of 780 Dutch patients, including participants in a large Inflammatory Bowel Disease (IBD) gut microbiome cohort and population controls, in order to identify barriers to sample collection and provide recommendations for gut microbiome researchers and clinicians. We sent questionnaires to 660 IBD patients and 112 patients with other disorders who had previously been approached to participate in gut microbiome studies. We also conducted 478 brief interviews with participants in our general population cohort who had collected stool samples. Statistical analysis of the data was performed using R. 97.4% of respondents reported that they had willingly participated in stool sample collection for gut microbiome research, and most respondents (82.9%) and interviewees (95.6%) indicated willingness to participate again, with their motivations for participating being mainly altruistic (57.0%). Responses indicated that storing stool samples in the home freezer for a prolonged time was the main barrier to participation (52.6%), but clear explanations of the sampling procedures and their purpose increased participant willingness to collect and freeze samples (P = 0.046, P = 0.003). To account for participant concerns, gut microbiome researchers establishing cohorts and clinicians trying new faecal tests should provide clear instructions, explain the rationale behind their protocol, consider providing a small freezer and inform patients about study outcomes. By assessing the attitudes, motives and barriers surrounding participation in faecal sample collection, we provide important information that will contribute to the success of gut microbiome research and its near-future clinical applications.

CD95 is a key mediator of invasion and accelerated outgrowth of mouse colorectal liver metastases following radiofrequency ablation.

BACKGROUND & AIMS: Recently, we have shown that micro-metastases, in the hypoxic transition zone surrounding lesions generated by radiofrequency ablation (RFA), display strongly accelerated outgrowth. CD95 is best known for its ability to induce apoptosis but can also promote tumorigenesis in apoptosis-resistant tumor cells. Therefore, we tested whether CD95 signaling plays a role in accelerated outgrowth of colorectal liver metastases following RFA. METHODS: Hypoxia-induced invasion was assessed in three-dimensional EGFP-expressing C26 tumor cell cultures by confocal microscopy. CD95 localization was tested by immunofluorescence. Invasion and outgrowth of liver metastases following RFA were analyzed by post-mortem confocal microscopy and by morphometric assessment of tumor load. Neutralization of CD95L was performed by using antibody MFL4. CD95 was suppressed by lentiviral RNA interference. The role of host CD95L was assessed using gld mice. RESULTS: Micro-metastases in the hypoxic transition zone following RFA displayed a highly invasive phenotype and increased expression of CD95 and CD95L. Hypoxia-induced tumor cell invasion in vitro increased the expression of CD95 and CD95L and induced translocation of CD95 to the invasive front. In vitro invasion, metastasis invasion, and accelerated tumor growth in the transition zone were strongly suppressed by neutralizing CD95L or by suppressing tumor cell CD95. In contrast, metastasis invasion and outgrowth were unaffected in gld mice. CONCLUSIONS: Hypoxia causes autocrine activation of CD95 on colorectal tumor cells, thereby promoting local invasion and accelerated metastasis outgrowth in the hypoxic transition zone following RFA. Further pre-clinical work is needed to assess the role of CD95L neutralization, either alone or in combination with chemotherapy, in limiting aggressive recurrence of liver metastases following RFA.

The new EuroSCORE II does not improve prediction of mortality in high-risk patients undergoing cardiac surgery: a collaborative analysis of two European centres.

OBJECTIVES: Prediction of operative risk in adult patients undergoing cardiac surgery remains a challenge, particularly in high-risk patients. In Europe, the EuroSCORE is the most commonly used risk-prediction model, but is no longer accurately calibrated to be used in contemporary practice. The new EuroSCORE II was recently published in an attempt to improve risk prediction. We sought to assess the predictive value of EuroSCORE II compared with the original EuroSCOREs in high-risk patients. METHODS: Patients who underwent surgery between 1 April 2006 and 31 March 2011 with a preoperative logistic EuroSCORE ≥ 10 were identified from prospective cardiac surgical databases at two European institutions. Additional variables included in EuroSCORE II, but not in the original EuroSCORE, were retrospectively collected through patient chart review. The C-statistic to predict in-hospital mortality was calculated for the additive EuroSCORE, logistic EuroSCORE and EuroSCORE II models. The Hosmer-Lemeshow test was used to assess model calibration by comparing observed and expected mortality in a number of risk strata. The fit of EuroSCORE II was compared with the original EuroSCOREs using Akaike's Information Criterion (AIC). RESULTS: A total of 933 patients were identified; the median additive EuroSCORE was 10 (interquartile range [IQR] 9-11), median logistic EuroSCORE 15.3 (IQR 12.0-24.1) and median EuroSCORE II 9.3 (5.8-15.6). There were 90 (9.7%) in-hospital deaths. None of the EuroSCORE models performed well with a C-statistic of 0.67 for the additive EuroSCORE and EuroSCORE II, and 0.66 for the logistic EuroSCORE. Model calibration was poor for the EuroSCORE II (chi-square 16.5; P = 0.035). Both the additive EuroSCORE and logistic EuroSCORE had a numerically better model fit, the additive EuroSCORE statistically significantly so (difference in AIC was -5.66; P = 0.017). CONCLUSIONS: The new EuroSCORE II does not improve risk prediction in high-risk patients undergoing adult cardiac surgery when compared with original additive and logistic EuroSCOREs. The key problem of risk stratification in high-risk patients has not been addressed by this new model. Future iterations of the score should explore more advanced statistical methods and focus on developing procedure-specific algorithms. Moreover, models that predict complications in addition to mortality may prove to be of increasing value.