Analysis of the culturable gut yeast microbiota of dogs with digestive disorders

Despite the increasing interest in studying the gut mycobiota of dogs, the association between fungal colonization and the development of digestive disorders in this species remains largely understudied. On the other hand, the high prevalence of antifungal-resistant yeasts detected in previous studies in samples from animals represents a major threat to public health. We analyzed the presence of culturable yeasts in 112 rectal swab samples obtained from dogs with digestive disorders attended in a veterinary teaching hospital. Our results revealed that Malassezia pachydermatis was frequently isolated from the studied dog population (33.9% of samples), and that the isolation of this yeast was significantly associated to the age of animals, but not to their sex, disease group, or the presence of vomits and/or diarrhea. In contrast, other yeast species were less prevalent (17.9% of samples in total), and their isolation was not significantly associated to any variable included in the analysis. Additionally, we observed that 97.5% of the studied M. pachydermatis isolates (n = 158, 1-6 per positive episode) displayed a minimum inhibitory concentration (MIC) value >4 μg/ml to nystatin, 31.6% had a MIC ≥32 μg/ml to fluconazole, and 27.2% had a MIC >4 μg/ml to amphotericin B. The antifungal susceptibility profiles of non-Malassezia (n = 43, 1-7 per episode) were more variable and included elevated MIC values for some antifungal-species combinations. These results confirm that the intestine of dogs is a reservoir of opportunistic pathogenic yeasts and suggest that the prevalence of M. pachydermatis colonization depends more on the age of animals than on any specific digestive disorder.

Fecal microbiota transplantation and its repercussions in patients with melanoma refractory to anti-PD-1 therapy: scope review

INTRODUCTION

despite being extremely effective in some cases, up to 70% of patients with melanoma do not respond to anti-PD-1/PD-L1 (primary resistance) and many of the responders eventually progress (secondary resistance). Extensive efforts are being made to overcome this resistance through new strategies, especially aimed at modulating the intestinal microbiota.

OBJECTIVE

to assess whether fecal microbiota transplantation (FMT), associated with immunotherapy, is beneficial in the clinical course of patients with refractory melanoma.

METHODS

this is a scope review, based on studies collected on the MEDLINE, ScienceDirect, The Cochrane Library, Embase and BMJ Journals; using the terms: "Antibodies, Monoclonal"; "Drug Resistance, Neoplasm"; "Fecal Microbiota Transplantation"; "Host Microbial Interactions"; "Immunotherapy"; "Melanoma"; and "Microbiota". Clinical trials, in English, with relevant data on the subject and fully available were included. A cut-off period was not determined, due to the limited amount of evidence on the topic.

RESULTS

crossing the descriptors allowed the identification of 342 publications and, after applying the eligibility criteria, allowed the selection of 4 studies. From the analyses, it was observed that a considerable part of those studied overcame resistance to immune checkpoint inhibitors after FMT, with better response to treatment, less tumor growth and increased beneficial immune response.

CONCLUSION

it is noted that FMT favors the response of melanoma to immunotherapy, translated into significant clinical benefit. However, further studies are necessary for the complete elucidation of the bacteria and the mechanisms involved, as well as for the translation of new evidence to oncological care practice.

Colorectal Cancer in Inflammatory Bowel Diseases: Epidemiology and Prevention: A Review

Simple Summary

Colorectal cancer (CRC) is one of the most serious potential complications of inflammatory bowel diseases (IBDs). The aging of patients affected by IBDs makes this issue a challenge that will increasingly be faced by clinicians in clinical practice, especially in light of the poorer prognosis for CRC in this group of people when compared with the general population. In this review, we summarize the current epidemiology, risk factors and various prevention strategies proposed for CRC in patients with IBDs.

Abstract

Colorectal cancer (CRC) is currently the third most frequent form of malignancy and the second in terms of mortality. Inflammatory bowel diseases (IBDs) are recognized risk factors for this type of cancer. Despite a worldwide increase in the incidence of CRC, the risk of CRC-related death in IBD patients has declined over time, probably because of successful surveillance strategies, the use of more effective drugs in the management of remission and improved indications to colectomy. This notwithstanding, CRC 5-year survival in patients with IBD is poorer than in the general population. This review provides a summary of the epidemiological features, risk factors and various prevention strategies proposed for CRC in IBD patients. Moreover, there is a special focus on reporting and highlighting the various prevention strategies proposed by the most important international scientific societies, both in terms of chemoprevention and endoscopic surveillance. Indeed, in conducting the analysis, we have given attention to the current primary, secondary and tertiary prevention guidelines, attempting to emphasize unresolved research and clinical problems related to this topic in order to improve diagnostic strategies and management.

Complete Genome Sequences of Leclercia sp. W6 and W17 Isolated from a Gastric Cancer Patient

Leclercia sp. W6 and W17, which belong to the Enterobacteriaceae, were isolated from a stomach sample from a 78-year-old female gastric cancer patient, and genomic sequencing and analysis were performed. The genome of Leclercia sp. W6 consists of one chromosome with a size of 4,945,486 bp, while that of Leclercia sp. W17 contains one chromosome and two plasmids with a total size of 5,125,645 bp. Average nucleotide identity (ANI) calculations indicated that strains W6 and W17 exhibited similarities < 91.0% to other strains within the Enterobacteriaceae, except for six Leclercia strains. Phylogenomic analysis based on core-genome showed that strains W6 and W17 belong to the genus Leclercia, and phylogenetic analysis based on ANI values revealed that strains W6 and W17 formed an independent clade from those six Leclercia strains. Furthermore, comparative genomic analysis revealed that strains W6 and W17 had 5086 orthologous clusters (OCs) in their pan-genomes, and 59 exclusive OCs which were absent in their closest relatives. Genomic annotations revealed that the genomes of strains W6 and W17 encoded genes related to multidrug resistance clusters, multiple antibiotic resistance loci, and multidrug efflux pumps and had an identical urease gene cluster and a dissimilatory nitrate reduction pathway. Bioinformatic analyses indicated that strains W6 and W17 represented a novel species within the genus Leclercia. Genomic annotations revealed that these strains encoded genes related to multidrug resistance, nitrate reduction, and urease activity, which contribute to gastric malignant transformation. This will broaden our knowledge of the genetic mechanisms of the Enterobacteriaceae and help improve the clinical conditions of gastric cancer patients.

Analysis of Risk Factors of Gastric Low-Grade Intraepithelial Neoplasia in Asymptomatic Subjects Undergoing Physical Examination

Secondary prevention is an important strategy in gastric cancer. Low-grade intraepithelial neoplasia (LGIN) is the last stage of precancerous lesion, and its timely diagnosis can greatly improve the detection rate of early gastric cancer. We performed a prospective study to analyze the risk factors of gastric LGIN in asymptomatic subjects undergoing physical examination. A total of 3437 subjects were included in this study, and 2259 asymptomatic subjects were investigated from March 2015 to April 2018. Risk factors were evaluated, and the endoscopic features of LGIN and prognosis were described. The overall incidence of LGIN was 19.73% (678/3437), while the incidence of LGIN in the asymptomatic and symptomatic groups was 19.65% (444/2259) and 19.86% (234/1178), respectively (P = 0.884). The rate of Helicobacter pylori infection in this physical examination population was 39.13% (35.8% asymptomatic group, 45.5% symptomatic group; P ≤ 0.001). Risk factors including age, H. pylori infection, history of antibiotic misuse, and spicy and high-fat diet (all P < 0.05) were further verified by multivariate analysis as independent risk factors. History of antibiotic misuse and H. pylori infection showed significant associations with LGIN (odds ratio (OR) = 6.767, 95% confidence interval (CI) 3.873-11.825 and OR = 3.803, 95% CI 3.009-4.808, respectively). The most common endoscopic classification of LGIN was erosive gastritis (50.78%), and the major endoscopic appearance was Paris IIa (flat with slight elevation located mostly in the antrum). During the mean follow-up period of 15.02 months, 49.4% of LGIN regressed, 0.61% of LGIN progressed, and 50% of LGIN remained unchanged. History of antibiotic misuse and H. pylori infection were predominant risk factors of LGIN in asymptomatic subjects, and those individuals should consider early screening for gastric cancer.

Genomic and molecular alterations in human inflammatory bowel disease-associated colorectal cancer

Patients with inflammatory bowel disease are at increased risk of colorectal cancer, which has worse prognosis than sporadic colorectal cancer. Until recently, understanding of pathogenesis in inflammatory bowel disease-associated colorectal cancer was restricted to the demonstration of chromosomic/microsatellite instabilities and aneuploidy. The advance of high-throughput sequencing technologies has highlighted the complexity of the pathobiology and revealed recurrently mutated genes involved in the RTK/RAS, PI3K, WNT, and TGFβ pathways, leading to potentially new targetable mutations. Moreover, alterations of mitochondrial DNA and the dysregulation of non-coding sequences have also been described, as well as several epigenetic modifications. Although recent studies have brought new insights into pathobiology and raised the prospect of innovative therapeutic approaches, the understanding of colorectal carcinogenesis in inflammatory bowel disease and how it differs from sporadic colorectal cancer remains not fully elucidated. Further studies are required to better understand the pathogenesis and molecular alterations leading to human inflammatory bowel disease-associated colorectal cancer.

A potential species of next-generation probiotics? The dark and light sides of Bacteroides fragilis in health

Bacteroides fragilis (B. fragilis) is a commensal Gram-negative obligate anaerobe that resides in the mammalian lower gut and can profoundly affect the susceptibility of the host to inflammatory diseases. Previous studies have identified B. fragilis as a common opportunistic pathogen in clinical infections and suggested that it may be responsible for a range of diseases involving a permeable intestinal barrier. However, recent studies of the relationship between nontoxigenic B. fragilis and the immune system have indicated that several B. fragilis strains may be potential probiotic. In the present review, we summarize the factors influencing the intestinal abundance of B. fragilis and discuss the biological interactions between this microbe and the host. Immune system development, age, individual dietary habits, physical condition, drug intake and personal lifestyle habits can all affect the abundance of B. fragilis in the human intestine. Polysaccharide A or outer membrane vesicles from nontoxigenic B. fragilis may mediate beneficial interactions with the host, whereas enterotoxigenic B. fragilis toxin or lipopolysaccharide may stimulate colitis or even systemic inflammation. Generally, this review summarizes the biological characteristics of B. fragilis and describes future application of probiotics.

Cancer immunotherapy: the art of targeting the tumor immune microenvironment

For many decades, cancer treatment has been strongly directed toward the development of cytotoxic and cytostatic drugs, quite often leading to disappointing results due to the inter- and intra-tumoral heterogeneity. Lately, this intra-cellular look has given way to the understanding of the tumor microenvironment, thus enabling modification of the immunological dynamics between tumor cells and their host. An era of new drugs aiming to unlock the host immune system against tumor cells is steadily increasing. Strategies involving adoptive cell therapy, therapeutic vaccines, immune checkpoint inhibitors and so on have provided spectacular clinical responses and increased survival in previously refractory settings and "hard-to-treat" cancers. Based on a comprehensive search in the main scientific databases, annals of recent renowned oncology congresses and platforms of ongoing trials, the clinical pharmacology characteristics of the main classes of immunotherapeutic agents, as well as the new treatment strategies related to immunotherapy in solid tumors, are carefully discussed throughout this review.

Impact of Gut Dysbiosis on Neurohormonal Pathways in Chronic Kidney Disease

Chronic kidney disease (CKD) is a worldwide major health problem. Traditional risk factors for CKD are hypertension, obesity, and diabetes mellitus. Recent studies have identified gut dysbiosis as a novel risk factor for the progression CKD and its complications. Dysbiosis can worsen systemic inflammation, which plays an important role in the progression of CKD and its complications such as cardiovascular diseases. In this review, we discuss the beneficial effects of the normal gut microbiota, and then elaborate on how alterations in the biochemical environment of the gastrointestinal tract in CKD can affect gut microbiota. External factors such as dietary restrictions, medications, and dialysis further promote dysbiosis. We discuss the impact of an altered gut microbiota on neuroendocrine pathways such as the hypothalamus⁻pituitary⁻adrenal axis, the production of neurotransmitters and neuroactive compounds, tryptophan metabolism, and the cholinergic anti-inflammatory pathway. Finally, therapeutic strategies including diet modification, intestinal alpha-glucosidase inhibitors, prebiotics, probiotics and synbiotics are reviewed.

Colorectal cancer prevention in patients with ulcerative colitis

Ulcerative colitis is characterized by chronic inflammation, which may lead to the accumulation of high levels of pro-inflammatory cytokines within the colonic mucosa, and thus to dysplastic lesions and cancer. Although the trend is decreasing, ulcerative colitis patients still have a 2.4 fold higher risk of colorectal cancer compared to the general population. The key task is to control colonic inflammation, and a rapid step-up approach while closely monitoring intestinal inflammation are recommented. Surveillance colonoscopy program demonstrated its efficacy for reducing the incidence of colorectal cancer in ulcerative colitis. The impact of medication on the reduction of colorectal cancer risk was hardly investigated and it remains unclear whether they have intrinsic anti-neoplastic properties or only downregulate inflammatory pathways. Several studies showed a decreased risk of colorectal cancer in ulcerative colitis patients treated with 5-aminosalicylic acid and chemoprevention with mesalamine compounds is currently recommended. The current level of evidence is too low for thiopurines and anti-TNFα agents. Large, prospective cohort studies are ongoing and are likely to bring new findings about the impact of drugs on colorectal cancer risk in the current era of biologics.