Triggers and regulation: the gut microbiome in rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis is a chronic inflammatory disease marked by systemic symptoms and joint degeneration. Interestingly, the development and progression of rheumatoid arthritis have been linked to the microbiome, notably the gut microbiome. Dysbiosis, an alteration in the gut microbiome, has been connected to the etiology and pathogenesis of rheumatoid arthritis. For instance, dysbiosis increases intestinal permeability and promotes the movement of bacteria and their products, which in turn triggers and aggravates systemic inflammation.

AREAS COVERED

The correlation between the gut microbiome and RA. Triggers of RA including dysbiosis. The therapeutic potential of the gut microbiome in RA due to its critical function in influencing the immune response. The fecal microbiota transplantation (FMT), a therapeutic strategy that involves the transfer of healthy fecal microbiota from a donor to a recipient, has produced encouraging results in the treatment of several autoimmune illnesses, including rheumatoid arthritis.

EXPERT OPINION

The role of the gut microbiome in RA is critical and serves as a basis for etiology and pathogenesis, as well as having therapeutic implications. In our opinion, FMT is an excellent example of this correlation. Still, more investigations and well-designed studies are needed in order to make firm conclusions and recommendations.

Psychoactive Effects of Lactobacillus johnsonii Against Restraint Stress-Induced Memory Dysfunction in Mice Through Modulating Intestinal Inflammation and permeability-a Study Based on the Gut-Brain Axis Hypothesis

Though the underlying mechanism remains elusive, a close relationship between psychological stress and intestinal inflammation has been widely accepted. Such a link is very important to set the basis for our understanding of the critical role of gut-brain axis (GBA) in homeostatic processes in health and disease. Probiotics that could confer benefits to mental health through GBA are referred to as "psychobiotics". This study aimed to further determine whether a potential psychobiotic strain, Lactobacillus johnsonii BS15 could prevent memory dysfunction in mice induced by psychological stress through modulating the gut environment, including intestinal inflammation and permeability. Memory dysfunction in mice was induced by restraint stress (RS), one of the most commonly utilized models to mimic psychological stress. The mice were randomly categorized into three groups including no stress (NS), restraint stress (RS), and probiotic (RS-P) and administered with either phosphate buffered saline (NS and RS groups) or L. johnsonii BS15 (RS-P group) every day from day 1-28. From days 22-28, the mice in RS and RS-P groups were subjected to RS each day. Results revealed that BS15-pretreatment enhanced the performance of RS-induced mice during three different behavioral tests for memory ability and positively modulated the hypothalamic-pituitary-adrenal axis by attenuating the serum corticosterone level. In the hippocampus, L. johnsonii BS15 positively modulated the memory-related functional proteins related to synaptic plasticity, increased neurotransmitter levels, and prevented RS-induced oxidative stress and mitochondria-mediated apoptosis. In the intestines, L. johnsonii BS15 protected the RS-induced mice from damaged gut barrier by enhancing the mRNA levels of tight junction proteins and exerted beneficial effects on the anti-inflammatory cytokine levels reduced by RS. These findings provided more evidence to reveal the psychoactive effect of L. johnsonii BS15 against memory dysfunction in RS-induced mice by modulating intestinal inflammation and permeability.

Silencing interleukin 1α underlies a novel inhibitory role of miR-181c-5p in alleviating low-grade inflammation of rats with irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common disorder of unknown etiology. Studies have found a close relation between IBS and microRNAs (miRNAs), but the study concerning the relationship between IBS and miR-181c-5p in IBS is still blank. Thus, this study aims to explore the role of miR-181c-5p in IBS via interleukin 1α (IL1A). Initially, microarray analysis was used to retrieve the genes related to IBS and to predict miRNAs regulating IL1A gene. IBS model was then established with abdominal withdraw reflection (AWR) and Bristol stool grading in mice measured. Afterwards, the functional role of miR-181c-5p in IBS was determined using the ectopic expression, depletion and reporter assay experiments, as well as miR-181c-5p and IL1A expression detected. Subsequently, expression of tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2), and IL-6 were detected to further determine the effects of miR-181c-5p and IL1A on inflammation in IBS. miR-181c-5p and IL1A might be involved in IBS. miR-181c-5p was found to be decreased while IL1A was increased in IBS rats. In addition, miR-181c-5p could target and inhibit expression of IL1A, and IBS mice exhibited elevated AWR and Bristol stool grading, namely 6 to 7 points (70.4 [38 of 54]). Moreover, with the overexpression of miR-181c-5p or silencing of IL1A, the expression of TNF-α, IL-2, and IL-6 was decreased. Collectively, this study suggested that overexpressed miR-181c-5p could silence IL1A, thus inhibiting low-grade inflammation in IBS rats. miR-181c-5p/IL1A is expected to serve as a novel target for the treatment of IBS.

Inulin as a multifaceted (active) substance and its chemical functionalization: From plant extraction to applications in pharmacy, cosmetics and food

This review is aimed at critically discussing a collection of research papers on Inulin (INU) in different scientific fields. The first part of this work gives an overview on the main characteristics of native INU, including production, applications in food or cosmetics industries, its benefits on human health as well as its main nutraceutical properties. A particular focus is dedicated to the extraction techniques and to the specific effects of INU on intestinal microbiota. Other than in food industry, the number of INU applications increases dramatically in the pharmaceutical field especially due to its simple chemical functionalization. Thus, aim of this review is also to give practical examples of chemical functionalization performed on INU also by including critical comments based on the direct experience of the Authors. With this aim, a full paragraph is dedicated to practical chemical experiences useful to reduce the efforts when establishing new experimental conditions. Moreover, the pharmaceutical technology is also taken in special consideration by underlining the aspects leading at the preparation of formulations based on INU. At the end of the review, a critical paragraph is intended to feed the scientists' curiosity on this versatile polysaccharide.

Gut : liver : brain axis: the microbial challenge in the hepatic encephalopathy

Hepatic encephalopathy (HE) is a debilitating neuropsychiatric condition often associated with acute liver failure or cirrhosis. Advanced liver diseases are characterized by a leaky gut and systemic inflammation. There is strong evidence that the pathogenesis of HE is linked to a dysbiotic gut microbiota and to harmful microbial by-products, such as ammonia, indoles, oxindoles and endotoxins. Increased concentrations of these toxic metabolites together with the inability of the diseased liver to clear such products is thought to play an important patho-ethiological role. Current first line clinical treatments target microbiota dysbiosis by decreasing the counts of pathogenic bacteria, blood endotoxemia and ammonia levels. This review will focus on the role of the gut microbiota and its metabolism in HE and advanced cirrhosis. It will critically assess data from different clinical trials measuring the efficacy of the prebiotic lactulose, the probiotic VSL#3 and the antibiotic rifaximin in treating HE and advanced cirrhosis, through gut microbiota modulation. Additionally data from Randomised Controlled Trials using pre-, pro- and synbiotic will be also considered by reporting meta-analysis studies. The large amount of existing data showed that HE is a clear example of how an altered gut microbiota homeostasis can influence and impact on physiological functions outside the intestine, with implication for host health at the systems level. Nevertheless, a strong effort should be made to increase the information on gut microbiota ecology and its metabolic function in liver diseases and HE.

A double blind, placebo-controlled, randomized clinical trial that breast milk derived-Lactobacillus gasseri BNR17 mitigated diarrhea-dominant irritable bowel syndrome

The exact pathogenesis of diarrhea-dominant irritable bowel syndrome (IBS) is not known, but the abnormal microbiota of the gastrointestinal tract is considered to be one of the important contributing factors as in other gastrointestinal diseases such as inflammatory bowel disease, antibiotic-associated diarrhea, and colorectal cancer as well as systemic diseases. Though diverse trials of probiotics had been continued in the treatment of diarrhea-IBS, only a few proved by randomized clinical trial. To prove the efficacy of Lactobacillus gasseri BNR17 isolated from breast milk in patients with diarrhea-IBS, prospective, randomized, placebo controlled clinical trial was done including health related-quality of life analysis, colon transit time, and the changes of fecal microbiota. BNR17 significantly improved the symptoms of diarrhea compared to control group. Health related-QOL analysis showed significant improvement of abdominal pain, distension, disturbed daily life, and mean defecation frequency with BNR17. On comparative CTT before and after BNR17, 6 out of 24 subjects showed significant correction of rapid colon transit pattern, while only 2 out of 24 in placebo (p<0.01). Upon fecal microbiota analysis, BNR17 significantly increased B. fecalis, E. rectale, C. aerofaciens, F. prausnitzil and B. steroris. Conclusively, Lactobacillus gasseri BNR17 can be a potential probiotics to ameliorate diarrhea-IBS.

Lactobacillus reuteri DSM 17938 in the Treatment of Functional Abdominal Pain in Children: RCT Study

OBJECTIVES

Beneficial therapeutic effect of probiotics has been reported in children with the irritable bowel syndrome (IBS) but not consistently in other functional abdominal pain-related disorders. The aim of the present study was to investigate the effect of Lactobacillus reuteri DSM 17938 in the treatment of functional abdominal pain (FAP) and IBS in children.

METHODS

Children (age 4-18 years) referred to pediatric gastroenterologist at Children's Hospital Zagreb from May 2012 to December 2014, diagnosed as FAP or IBS, were randomized to receive L reuteri DSM 17938 10⁸ CFU daily or placebo. The study was a prospective, randomized, double-blind, placebo-controlled parallel study. Symptoms were evaluated using Wong-Baker FACES pain rating scale for pain and Bristol scale for stool shape and consistence.

RESULTS

Data were analyzed for 55 children (26 in the intervention group and 29 in the placebo group). Children in the intervention group had significantly more days without pain (median 89.5 vs 51 days, P = 0.029). Abdominal pain was less severe in children taking probiotics during the second month (P < 0.05) and fourth month (P < 0.01). The 2 groups did not differ in the duration of abdominal pain, stool type, or absence from school. Both groups experienced significant reduction in the severity of abdominal pain from first to fourth month, with the reduction more prominent in the intervention group (P < 0.001 vs P = 0.004).

CONCLUSIONS

Administration of L reuteri DSM 17938 was associated with a possible reduction of the intensity of pain and significantly more days without pain in children with FAP and IBS.

Brown rice and retrograded brown rice alleviate inflammatory response in dextran sulfate sodium (DSS)-induced colitis mice

We investigate the impact of brown rice and retrograded brown rice consumption on colonic health in dextran sulfate sodium induced colitis mice.

Lymphocytic duodenitis or microscopic enteritis and gluten-related conditions: what needs to be explored?

Microscopic enteritis (ME) is characterized by abnormal infiltration of intraepithelial lymphocytes in intestinal mucosa. It was described as duodenal lymphocytosis or lymphocytic duodenitis until the dedicated Consensus Conference of 2015. ME represents a common feature of several gluten-mediated and non-gluten related diseases; therefore, it is an umbrella term embracing several conditions. The most frequent causes of ME are gluten-related disorders (celiac disease, non-celiac gluten sensitivity, wheat allergy), Helicobacter pylori infection and drug-related damages. Less frequently, ME may be secondary to inflammatory bowel disease, some autoimmune conditions, immunoglobulin deficiencies, blood malignancies, infections and irritable bowel syndrome. Therefore, the differential diagnosis of ME may be challenging. The diagnosis of ME needs to be driven by predominant symptoms and patient history. However, it is often difficult to achieve an immediate identification of the underlying condition, and a broad variety of diagnostic tests may be required. Ultimately, long-term surveillance is needed for a final diagnosis in many cases, since a hidden or quiescent condition may be disclosed after a period of latency. In any case, strict collaboration between the clinician and the pathologist is pivotal. The treatment of ME should be personalized, depending on the underlying disease. For gluten-related conditions (celiac disease, gluten sensitivity, wheat allergy, dermatitis herpetiformis), a gluten-free diet may be proposed. For other conditions, a targeted etiologic treatment is necessary. In conclusion, ME represents a novel entity that is attracting increasing interest. The growing epidemiologic trend confirms that it will become a common condition in clinical practice.

Ameliorative effects of atractylodin on intestinal inflammation and co-occurring dysmotility in both constipation and diarrhea prominent rats

Intestinal disorders often co-occur with inflammation and dysmotility. However, drugs which simultaneously improve intestinal inflammation and co-occurring dysmotility are rarely reported. Atractylodin, a widely used herbal medicine, is used to treat digestive disorders. The present study was designed to characterize the effects of atractylodin on amelioration of both jejunal inflammation and the co-occurring dysmotility in both constipation-prominent (CP) and diarrhea-prominent (DP) rats. The results indicated that atractylodin reduced proinflammatory cytokines TNF-α, IL-1β, and IL-6 in the plasma and inhibited the expression of inflammatory mediators iNOS and NF-kappa B in jejunal segments in both CP and DP rats. The results indicated that atractylodin exerted stimulatory effects and inhibitory effects on the contractility of jejunal segments isolated from CP and DP rats respectively, showing a contractile-state-dependent regulation. Atractylodin-induced contractile-state-dependent regulation was also observed by using rat jejunal segments in low and high contractile states respectively (5 pairs of low/high contractile states). Atractylodin up-regulated the decreased phosphorylation of 20 kDa myosin light chain, protein contents of myosin light chain kinase (MLCK), and MLCK mRNA expression in jejunal segments of CP rats and down-regulated those increased parameters in DP rats. Taken together, atractylodin alleviated rat jejunal inflammation and exerted contractile-state-dependent regulation on the contractility of jejunal segments isolated from CP and DP rats respectively, suggesting the potential clinical implication for ameliorating intestinal inflammation and co-occurring dysmotility.

Microbial translocation and microbiome dysbiosis in HIV-associated immune activation

PURPOSE OF REVIEW

This article describes the mechanisms and consequences of both microbial translocation and microbial dysbiosis in HIV infection.

RECENT FINDINGS

Microbes in HIV are likely playing a large role in contributing to HIV pathogenesis, morbidities and mortality. Two major disruptions to microbial systems in HIV infection include microbial translocation and microbiome dysbiosis. Microbial translocation occurs when the bacteria (or bacterial products) that should be in the lumen of the intestine translocate across the tight epithelial barrier into systemic circulation, where they contribute to inflammation and pathogenesis. This is associated with poorer health outcomes in HIV-infected individuals. In addition, microbial populations in the gastrointestinal tract are also altered after HIV infection, resulting in microbiome dysbiosis, which further exacerbates microbial translocation, epithelial barrier disruption, inflammation and mucosal immune functioning.

SUMMARY

Altered microbial regulation in HIV infection can lead to poor health outcomes, and understanding the mechanisms underlying microbial dysbiosis and translocation may result in novel pathways for therapeutic interventions.

The Significance of the Enteric Microbiome on the Development of Childhood Disease: A Review of Prebiotic and Probiotic Therapies in Disorders of Childhood

Recent studies have highlighted the fact that the enteric microbiome, the trillions of microbes that inhabit the human digestive tract, has a significant effect on health and disease. Methods for manipulating the enteric microbiome, particularly through probiotics and microbial ecosystem transplantation, have undergone some study in clinical trials. We review some of the evidence for microbiome alteration in relation to childhood disease and discuss the clinical trials that have examined the manipulation of the microbiome in an effort to prevent or treat childhood disease with a primary focus on probiotics, prebiotics, and/or synbiotics (ie, probiotics + prebiotics). Studies show that alterations in the microbiome may be a consequence of events occurring during infancy and/or childhood such as prematurity, C-sections, and nosocomial infections. In addition, certain childhood diseases have been associated with microbiome alterations, namely necrotizing enterocolitis, infantile colic, asthma, atopic disease, gastrointestinal disease, diabetes, malnutrition, mood/anxiety disorders, and autism spectrum disorders. Treatment studies suggest that probiotics are potentially protective against the development of some of these diseases. Timing and duration of treatment, the optimal probiotic strain(s), and factors that may alter the composition and function of the microbiome are still in need of further research. Other treatments such as prebiotics, fecal microbial transplantation, and antibiotics have limited evidence. Future translational work, in vitro models, long-term and follow-up studies, and guidelines for the composition and viability of probiotic and microbial therapies need to be developed. Overall, there is promising evidence that manipulating the microbiome with probiotics early in life can help prevent or reduce the severity of some childhood diseases, but further research is needed to elucidate biological mechanisms and determine optimal treatments.

Scientific evidence for health effects attributed to the consumption of probiotics and prebiotics: an update for current perspectives and future challenges

Probiotics and prebiotics, mainly commercialised as food ingredients and also as supplements, are considered highly profitable niche markets. However, in recent years, the food industry has suffered from a series of health claim restrictions on probiotics and prebiotics in many parts of the world, including those made by the European Food Safety Authority. Therefore, we reviewed the core benefits of probiotic and prebiotic consumption on health. A number of studies have examined the prevention and/or management of intestinal infections, respiratory tract infections, CVD, osteoporosis, urogenital infections, cavities, periodontal disease and halitosis, allergic reactions, inflammatory bowel disease and irritable bowel syndrome and Helicobacter pylori gastric infections. In fact, a deeper understanding of the mechanisms involved in human microbiota and immune system modulation by probiotics and prebiotics relies on continuous efforts to establish suitable biomarkers of health and diseases risk factors for the design of clinical trials required for health claim approval. In spite of the promising results, the performance of large, long-term, well-planned, well-aligned clinical studies is crucial to provide more reliability and a more solid basis for the outcomes achieved and to support the potential use of probiotics and prebiotics in clinical practice.

The transient but not resident (TBNR) microbiome: a Yin Yang model for lung immune system

The concept of microbial content of the lung is still controversial. What make this more complicated are controversial results obtaining from different methodologies about lung microbiome and the definition of "lung sterility". Lungs may have very low bacteria but are not completely germ-free. Bacteria are constantly entering from the upper respiratory tract, but are then quickly being cleared. We can find bacterial DNA in the lungs, but it is much harder to ask about living bacteria. Here, we propose that if there is any trafficking of the microorganisms in the lung, it should be a "Transient But Not Resident (TBNR)" model. So, we speculate a "Yin Yang model" for the lung immune system and TBNR. Despite beneficial roles of microbiome on the development of lung immune system, any disruption and alteration in the microbiota composition of upper and lower airways may trigger or lead to several diseases such as asthma, chronic obstructive pulmonary disease and mustard lung disease.

The Influence of the Gut Microbiome on Obesity, Metabolic Syndrome and Gastrointestinal Disease

There is a fine balance in the mutual relationship between the intestinal microbiota and its mammalian host. It is thought that disruptions in this fine balance contribute/account for the pathogenesis of many diseases. Recently, the significance of the relationship between gut microbiota and its mammalian host in the pathogenesis of obesity and the metabolic syndrome has been demonstrated. Emerging data has linked intestinal dysbiosis to several gastrointestinal diseases including inflammatory bowel disease, irritable bowel syndrome, nonalcoholic fatty liver disease, and gastrointestinal malignancy. This article is intended to review the role of gut microbiota maintenance/alterations of gut microbiota as a significant factor as a significant factor discriminating between health and common diseases. Based on current available data, the role of microbial manipulation in disease management remains to be further defined and a focus for further clinical investigation.

Foreword: All things considered about probiotics, prebiotics and ıntestinal microbiota in children – from bench to bedside

There are numerorus published and ongoing experimental/clinical studies about probiotics and prebiotics, intestinal microbiota and nutrition. Three years ago, at the first International Symposium of Probiotics Prebiotics in Paediatrics in Istanbul (2012) we highlighted the ‘paediatric perspective’ on these issues and brought together more than 40 global key opinion leaders and 400 attendants to have a chance to extensively discuss the past, present and the future. In 2014, the second state of art congress, held in Antalya, aimed to discuss the gut microbiota and microbiotics and their impact through lifespan. Selected papers of this conference are presented in this special issue ‘prebiotics and probiotics in paediatrics’ of Beneficial Microbes. A summary of the conference results is provided below.