Inflammasome signaling affects anxiety- and depressive-like behavior and gut microbiome composition.

The inflammasome is hypothesized to be a key mediator of the response to physiological and psychological stressors, and its dysregulation may be implicated in major depressive disorder. Inflammasome activation causes the maturation of caspase-1 and activation of interleukin (IL)-1ß and IL-18, two proinflammatory cytokines involved in neuroimmunomodulation, neuroinflammation and neurodegeneration. In this study, C57BL/6 mice with genetic deficiency or pharmacological inhibition of caspase-1 were screened for anxiety- and depressive-like behaviors, and locomotion at baseline and after chronic stress. We found that genetic deficiency of caspase-1 decreased depressive- and anxiety-like behaviors, and conversely increased locomotor activity and skills. Caspase-1 deficiency also prevented the exacerbation of depressive-like behaviors following chronic stress. Furthermore, pharmacological caspase-1 antagonism with minocycline ameliorated stress-induced depressive-like behavior in wild-type mice. Interestingly, chronic stress or pharmacological inhibition of caspase-1 per se altered the fecal microbiome in a very similar manner. When stressed mice were treated with minocycline, the observed gut microbiota changes included increase in relative abundance of Akkermansia spp. and Blautia spp., which are compatible with beneficial effects of attenuated inflammation and rebalance of gut microbiota, respectively, and the increment in Lachnospiracea abundance was consistent with microbiota changes of caspase-1 deficiency. Our results suggest that the protective effect of caspase-1 inhibition involves the modulation of the relationship between stress and gut microbiota composition, and establishes the basis for a gut microbiota-inflammasome-brain axis, whereby the gut microbiota via inflammasome signaling modulate pathways that will alter brain function, and affect depressive- and anxiety-like behaviors. Our data also suggest that further elucidation of the gut microbiota-inflammasome-brain axis may offer novel therapeutic targets for psychiatric disorders.

From gut dysbiosis to altered brain function and mental illness: mechanisms and pathways.

The human body hosts an enormous abundance and diversity of microbes, which perform a range of essential and beneficial functions. Our appreciation of the importance of these microbial communities to many aspects of human physiology has grown dramatically in recent years. We know, for example, that animals raised in a germ-free environment exhibit substantially altered immune and metabolic function, while the disruption of commensal microbiota in humans is associated with the development of a growing number of diseases. Evidence is now emerging that, through interactions with the gut-brain axis, the bidirectional communication system between the central nervous system and the gastrointestinal tract, the gut microbiome can also influence neural development, cognition and behaviour, with recent evidence that changes in behaviour alter gut microbiota composition, while modifications of the microbiome can induce depressive-like behaviours. Although an association between enteropathy and certain psychiatric conditions has long been recognized, it now appears that gut microbes represent direct mediators of psychopathology. Here, we examine roles of gut microbiome in shaping brain development and neurological function, and the mechanisms by which it can contribute to mental illness. Further, we discuss how the insight provided by this new and exciting field of research can inform care and provide a basis for the design of novel, microbiota-targeted, therapies.

The human microbiome: opportunities and challenges for clinical care.

There is a growing appreciation of the importance of the human microbiome to our normal physiology. This complex microbial ecosystem plays a range of roles, including influencing the development and function of our immune systems, providing essential nutrients, regulating metabolism and protecting us from opportunistic infections. Our increasing understanding of these processes is due, to a large extent, to the development of high-throughput sequencing technologies, providing for the first time a means by which complex microbial dynamics can be detailed. There is also a growing recognition that disruption of commensal microbiota, a phenomenon known as dysbiosis, is associated with several common disorders, including inflammatory bowel disease, type 2 diabetes and oncogenesis. Further, where innate immunity fails to protect us, the microbial communities that colonise the external surfaces of our bodies represent a ready source of infection. This review discusses the mechanisms that govern our interaction with our resident microbiota, both in health and disease, the technological advances that allow us to gain insight into these relationships, and the way in which our growing understanding can inform clinical practice.

Functional divergence in gastrointestinal microbiota in physically-separated genetically identical mice.

Despite the fundamental contribution of the gut microbiota to host physiology, the extent of its variation in genetically-identical animals used in research is not known. We report significant divergence in both the composition and metabolism of gut microbiota in genetically-identical adult C57BL/6 mice housed in separate controlled units within a single commercial production facility. The reported divergence in gut microbiota has the potential to confound experimental studies using mammalian models.

Challenges and opportunities for faecal microbiota transplantation therapy.

The incidence, morbidity, and mortality associated with Clostridium difficile gastrointestinal infections has increased greatly over recent years, reaching epidemic proportions; a trend due, in part, to the emergence of hypervirulent and antibiotic-resistant strains. The need to identify alternative, non-antibiotic, treatment strategies is therefore urgent. The ability of bacteria in faecal matter transplanted from healthy individuals to displace pathogen populations is well recognized. Further, there is growing evidence that such faecal microbiota transplantation can be of benefit in a wide range of conditions associated with gut dysbiosis. Recent technical advances have greatly increased our ability to understand the processes that underpin the beneficial changes in bacterial community composition, as well as to characterize their extent and duration. However, while much of the research into faecal microbiota transplantation focuses currently on achieving clinical efficacy, the potential for such therapies to contribute to the transmission of infective agents also requires careful consideration.

Impact of antibiotic treatment for pulmonary exacerbations on bacterial diversity in cystic fibrosis.

BACKGROUND: A diverse array of bacterial species is present in the CF airways, in addition to those recognised as clinically important. Here, we investigated the relative impact of antibiotics, used predominantly to target Pseudomonas aeruginosa during acute exacerbations, on other non-pseudomonal species. METHODS: The relative abundance of viable P. aeruginosa and non-pseudomonal species was determined in sputa from 12 adult CF subjects 21, 14, and 7 days prior to antibiotics, day 3 of treatment, the final day of treatment, and 10-14 days afterwards, by T-RFLP profiling. RESULTS: Overall, relative P. aeruginosa abundance increased during antibiotic therapy compared to other bacterial species; mean abundance pre-antibiotic 51.0±36.0% increasing to 71.3±30.4% during antibiotic (ANOVA: F(1,54)=5.16; P<0.027). Further, the number of non-pseudomonal species detected fell; pre-antibiotic 6.0±3.3 decreasing to 3.7±3.3 during treatment (ANOVA: F(1,66)=5.11; P<0.027). CONCLUSIONS: Antibiotic treatment directed at P. aeruginosa has an additional significant impact on non-pseudomonal, co-colonising species.

Characterisation of bacteria in ascites--reporting the potential of culture-independent, molecular analysis.

Spontaneous bacterial peritonitis (SBP) is a severe complication of liver disease. A significant proportion of patients have culture-negative ascites, despite having similar signs, symptoms and mortality to those with SBP. Therefore, empirical antibiotic treatment for infection is often started without knowledge of the causative organisms. Here, we investigated the potential of molecular techniques to provide rapid and accurate characterisation of the bacteria present in ascitic fluid. Ascites samples were obtained from 29 cirrhotic patients undergoing clinically indicated therapeutic paracentesis. Bacterial content was determined by terminal restriction fragment length polymorphism (T-RFLP) analysis, quantitative polymerase chain reaction (PCR) and 16S ribosomal clone sequence analysis. Bacterial signal was detected in all samples, compared to three out of ten using standard methods. Bacterial loads ranged from 5.5 x 10(2) to 5.4 x 10(7) cfu/ml, with a mean value of 1.9 x 10(6) cfu/ml (standard deviation +/- 9.6 x 10(6) cfu/ml). In all but one instance, bacterial species identified by culture were also confirmed by molecular analyses. Preliminary data presented here suggests that culture-independent, molecular analyses could provide rapid characterisation of the bacterial content of ascites fluid, providing a basis for the investigation of SBP development and allowing early and targeted antibiotic intervention.

The exclusion of dead bacterial cells is essential for accurate molecular analysis of clinical samples.

The DNA-based techniques used to detect bacteria in clinical samples are unable to discriminate between live bacteria, dead bacteria, and extracellular DNA. This failure to limit analysis to viable bacterial cells represents a significant problem, leading to false-positive results, as well as a failure to resolve the impact of antimicrobial therapy. The use of propidium monoazide treatment significantly reduces the contribution of dead cells and extracellular DNA to such culture-independent analyses. Here, the increased ability to resolve the impact of antibiotic therapy on Pseudomonas aeruginosa load in cystic fibrosis respiratory samples reveals statistically significant changes that would otherwise go undetected.

Use of 16S rRNA gene profiling by terminal restriction fragment length polymorphism analysis to compare bacterial communities in sputum and mouthwash samples from patients with cystic fibrosis.

The bacterial communities present in the oral cavity and the lungs of 19 adult cystic fibrosis (CF) patients were compared by using terminal restriction fragment length polymorphism analysis of 16S rRNA gene PCR products amplified from nucleic acids extracted directly from bacteria in clinical samples. Sputum samples were not found to be subject to profound contamination by oral cavity bacteria. Evidence of colonization of the CF lung by certain oral bacterial species was found.

Clinical impact of conventional endosonography and endoscopic ultrasound-guided fine-needle aspiration in the assessment of patients with Barrett's esophagus and high-grade dysplasia or intramucosal carcinoma who have been referred for endoscopic ablation therapy.

BACKGROUND AND STUDY AIMS: Endoscopic mucosal resection and photodynamic therapy are exciting, minimally invasive curative techniques that represent an alternative to surgery in patients with Barrett's esophagus and high-grade dysplasia or intramucosal adenocarcinoma. However, there is lack of uniformity regarding which staging method should be used prior to therapy, and some investigators even question whether staging is required prior to ablation. We report our experience with a protocol of conventional endoscopic ultrasound staging prior to endoscopic therapy. PATIENTS AND METHODS: A total of 25 consecutive patients with a diagnosis of high-grade dysplasia or intramucosal adenocarcinoma in Barrett's esophagus who had been referred to the University of Chicago for staging in preparation for endoscopic therapy between March 2002 and November 2004 were included in the study. All 25 patients underwent repeat diagnostic endoscopy and conventional endosonography with a radial echo endoscope. Any suspicious lymph nodes that were detected were sampled using endoscopic ultrasound-guided fine-needle aspiration. RESULTS: Baseline pathology in the 25 patients (mean age 70, range 49-85) revealed high-grade dysplasia in 12 patients and intramucosal carcinoma in 13 patients. Five patients were found to have submucosal invasion on conventional endosonography. Seven patients had suspicious adenopathy, six regional (N1) and one metastatic to the celiac axis (M1a). Fine-needle aspiration confirmed malignancy in five of these seven patients. Based on these results, five patients (20%) were deemed to be unsuitable candidates for endoscopic therapy. CONCLUSIONS: By detecting unsuspected malignant lymphadenopathy, conventional endosonography and endoscopic ultrasound with fine-needle aspiration dramatically changed the course of management in 20% of patients referred for endoscopic therapy of Barrett's esophagus with high-grade dysplasia or intramucosal carcinoma. Based on our results, we believe that conventional endosonography and endoscopic ultrasound with fine-needle aspiration when nodal disease is present should be performed routinely in all patients referred for endoscopic therapy in this setting.

characterization of bacterial community diversity in cystic fibrosis lung infections by use of 16s ribosomal DNA terminal restriction fragment length polymorphism profiling.

Progressive loss of lung function resulting from the inflammatory response to bacterial colonization is the leading cause of mortality in cystic fibrosis (CF) patients. A greater understanding of these bacterial infections is needed to improve lung disease management. As culture-based diagnoses are associated with fundamental drawbacks, we used terminal restriction fragment (T-RF) length polymorphism profiling and 16S rRNA clone data to characterize, without prior cultivation, the bacterial community in 71 sputa from 34 adult CF patients. Nineteen species from 15 genera were identified in 53 16S rRNA clones from three patients. Of these, 15 species have not previously been reported in CF lung infections and many were species requiring strict anaerobic conditions for growth. The species richness and evenness were determined from the T-RF length and volume for the 71 profiles. Species richness was on average 13.3 +/- 7.9 per sample and 13.4 +/- 6.7 per patient. On average, the T-RF bands of the lowest and highest volumes represented 0.6 and 59.2% of the total volume in each profile, respectively. The second through fifth most dominant T-RF bands represented 15.3, 7.5, 4.7, and 2.8% of the total profile volume, respectively. On average, the remaining T-RF bands represented 10.2% of the total profile volume. The T-RF band corresponding to Pseudomonas aeruginosa had the highest volume in 61.1% of the samples. However, 18 other T-RF band lengths were dominant in at least one sample. In conclusion, this reveals the enormous complexity of bacteria within the CF lung. Although their significance is yet to be determined, these findings alter our perception of CF lung infections.

Bacterial diversity in cases of lung infection in cystic fibrosis patients: 16S ribosomal DNA (rDNA) length heterogeneity PCR and 16S rDNA terminal restriction fragment length polymorphism profiling.

The leading cause of morbidity and mortality in cystic fibrosis (CF) patients stems from repeated bacterial respiratory infections. Many bacterial species have been cultured from CF specimens and so are associated with lung disease. Despite this, much remains to be determined. In the present study, we characterized without prior cultivation the total bacterial community present in specimens taken from adult CF patients, extracting DNA directly from 14 bronchoscopy or sputum samples. Bacterial 16S ribosomal DNA (rRNA) gene PCR products were amplified from extracted nucleic acids, with analyses by terminal restriction fragment length polymorphism (T-RFLP), length heterogeneity PCR (LH-PCR), and sequencing of individual cloned PCR products to characterize these communities. Using the same loading of PCR products, 12 distinct T-RFLP profiles were identified that had between 3 and 32 T-RFLP bands. Nine distinct LH-PCR profiles were identified containing between one and four bands. T-RFLP bands were detected in certain samples at positions that corresponded to pathogens cultured from CF samples, e.g., Burkholderia cepacia and Haemophilus influenzae. In every sample studied, one T-RFLP band was identified that corresponded to that produced by Pseudomonas aeruginosa. A total of 103 16S rRNA gene clones were examined from five patients. P. aeruginosa was the most commonly identified species (59% of clones). Stenotrophomonas species were also common, with eight other (typically anaerobic) bacterial species identified within the remaining 17 clones. In conclusion, T-RFLP analysis coupled with 16S rRNA gene sequencing is a powerful means of analyzing the composition and diversity of the bacterial community in specimens sampled from CF patients.

The effect of closure processing on the microbial inactivation of biological indicators at the closure-container interface.

Two biological indicators are routinely used by the Hospital Products Division to demonstrate the sterilization of the closure-container interface. The use of a moist heat (Clostridium sporogenes) and a dry heat (Bacillus subtilis) biological indicator allows a better understanding of the parameters that impact sterilization of the closure-container system. The ability to sterilize a given closure-container interface is defined in large part by closure moisture and product time above 100 degrees C. The data will demonstrate several different means to alter these two key factors, thereby enhancing sterilization of the closure-container interface. A categorization of closure types and processing parameters allows for more efficient cycle development in the R&D facility and a higher success rate for the final subprocess validation in the manufacturing steam vessels.