Intestinal barrier functions in hematologic and oncologic diseases

Epidemiology and outcomes of Candida spp. bloodstream infections in cancer patients: a comparative retrospective study from a German tertiary cancer center

BACKGROUND

Bloodstream infections (BSI) due to Candida spp. significantly contribute to morbidity and mortality among cancer patients. Understanding their clinical course, risk factors, and outcomes compared to bacterial BSI is essential.

AIM

We aim to elucidate the epidemiology and risk factors associated with Candida BSI compared to bacterial BSI in cancer patients.

METHODS

We analyzed epidemiological data of Candida BSI versus bacterial BSI among cancer patients, primarily with hematological malignancies. Blood cultures were obtained upon clinical suspicion, with species identification by VITEK 2 and MALDI-TOF. Susceptibility testing utilized VITEK 2 or antibiotic gradient tests.

RESULTS

Candida BSI was associated with higher 30-day mortality compared to bacterial BSI (Hazard ratio (HR) 4.5, 95% CI 2.5-8.1, p < 0.001) occurring predominantly in patients with relapsed/refractory disease. Univariate analysis identified risk factors for Candida BSI: hypoalbuminemia (Odds ratio (OR) 9.13, 95% CI 2.7-57, p = 0.003), prior ICU/MC stay (OR 3.91, 95% CI 1.38-9.65, p = 0.005), palliative treatment (OR 3.42, 95% CI 1.52-7.4, p = 0.002), parenteral nutrition (OR 2.44, 95% CI 0.9-5.5, p = 0.039) and prior allogeneic HSCT (OR 2.28, 95% CI 0.92-5.13, p = 0.056). Risk factors identified by multivariate analysis were palliative therapy (OR 5.23, 95% CI 3.14-8.71, p = 0.001), hypoalbuminemia (OR 9.02, 95% CI 4.23-19.2, p = 0.004), and prior ICU/IMC stay (OR 4, 95% CI 2.31-6.92, p = 0.011). In patients with confirmed Candida BSI, delayed initiation of antifungal was associated with worse outcomes.

CONCLUSION

Compared to bacterial BSI events, Candida BSI are associated with significantly higher 30-day mortality, primarily affecting heavily pretreated patients with relapsed or refractory disease.

Gut integrity in intensive care: alterations in host permeability and the microbiome as potential therapeutic targets

BACKGROUND

The gut has long been hypothesized to be the "motor" of critical illness, propagating inflammation and playing a key role in multiple organ dysfunction. However, the exact mechanisms through which impaired gut integrity potentially contribute to worsened clinical outcome remain to be elucidated. Critical elements of gut dysregulation including intestinal hyperpermeability and a perturbed microbiome are now recognized as potential therapeutic targets in critical care.

MAIN BODY

The gut is a finely tuned ecosystem comprising ~ 40 trillion microorganisms, a single cell layer intestinal epithelia that separates the host from the microbiome and its products, and the mucosal immune system that actively communicates in a bidirectional manner. Under basal conditions, these elements cooperate to maintain a finely balanced homeostasis benefitting both the host and its internal microbial community. Tight junctions between adjacent epithelial cells selectively transport essential molecules while preventing translocation of pathogens. However, critical illness disrupts gut barrier function leading to increased gut permeability, epithelial apoptosis, and immune activation. This disruption is further exacerbated by a shift in the microbiome toward a "pathobiome" dominated by pathogenic microbes with increased expression of virulence factors, which intensifies systemic inflammation and accelerates organ dysfunction. Research has highlighted several potential therapeutic targets to restore gut integrity in the host, including the regulation of epithelial cell function, modulation of tight junction proteins, and inhibition of epithelial apoptosis. Additionally, microbiome-targeted therapies, such as prebiotics, probiotics, fecal microbiota transplantation, and selective decontamination of the digestive tract have also been extensively investigated to promote restoration of gut homeostasis in critically ill patients. Future research is needed to validate the potential efficacy of these interventions in clinical settings and to determine if the gut can be targeted in an individualized fashion.

CONCLUSION

Increased gut permeability and a disrupted microbiome are common in critical illness, potentially driving dysregulated systemic inflammation and organ dysfunction. Therapeutic strategies to modulate gut permeability and restore the composition of microbiome hold promise as novel treatments for critically ill patients.

One Size Fits Small: The Narrow Utility for Plasma Metagenomics

Metagenomic sequencing of plasma has been advertised by Karius, Inc. as a way to diagnose a variety of infectious syndromes. Due to the lack of robust evidence of clinical utility, our laboratory began actively stewarding Karius testing. Microbiology Directors recommended cancelation of Karius orders when certain criteria were identified. We set out to review Karius test requests in a 52-month period of stewardship, during which we recommended cancellation on 21 of 57 orders (37%). Of Karius tests sent on samples with negative conventional testing, only 3 (7%) had positive results for Karius with plausible explanatory etiologies. Of these three cases, two were empirically covered for the positive finding without improvement and one case was never treated. Twelve (29%) had positive results that were noted by infectious diseases (ID) to reflect insignificant detections. Given the 4-fold higher detection of insignificant Karius results, we set out to systematically analyze the literature for the experience of insignificant detections at other centers. When we compared studies that included healthy controls or had clinical adjudication of positive Karius findings by ID physicians, we found a median of 17.5% of individual patients that had positive insignificant detections of potential pathogenic bacteria or fungi. The most frequently detected species were as likely to be clinically adjudicated to be insignificant as they were to be significant within the same studies. Overall, these findings highlight limited utility of Karius testing and a need for careful stewardship, not only to ensure it is sent on patients who may benefit, but also to ensure results of potential pathogens are interpreted cautiously.

Gut-bone axis perturbation: Mechanisms and interventions via gut microbiota as a primary driver of osteoporosis

A growing number of studies have highlighted the significance of human gut microbiota (GM) as a potential target for osteoporosis. In this review, we discuss the effect of GM to bone metabolism focusing on two aspects: the local alterations of the human gut permeability that modify how the GM interact with the gut-bone axis (e.g., intestinal leakage, nutrient absorption), and the alterations of the GM itself (e.g., changes in microbiota metabolites, immune secretion, hormones) that modify the events of the gut-bone axis. We then classify these changes as possible therapeutic targets of bone metabolism and highlight some associated promising microbiome-based therapies. We also extend our discussions into combinatorial treatments that incorporate conservative treatments, such as exercise. We anticipate our review can provide an overview of the current pathophysiological and therapeutic paradigms of the gut-bone axis, as well as the prospects of ongoing clinical trials for readers to gain further insights into better microbiome-based treatments to osteoporosis and other bone-degenerative diseases. The translational potential of this article: This paper reviewed the potential links between gut microbiota and osteoporosis, as well as the prospective therapeutic avenues targeting gut microbiota for osteoporosis management, presenting a thorough and comprehensive literature review.

Dose-Dependent Effects of Turmeric (Curcuma aromatica S.) Starch on Colonic Fermentation in Rats

Background; Turmeric starch (TS) has gained significant attention due to its potential health benefits. Rich in resistant starch (RS) and higher in phosphorus, TS is anticipated to possess properties of high-phosphorus-type RS. Objectives; To understand the host physiology of TS, this study investigated the dose-dependent effects of TS on colonic fermentation in rats. Methods; Four experimental diets containing different levels of TS (5%, 10%, and 20% w/w) were formulated and fed to male Fischer 344 rats for two weeks and compared with rats fed a 0% TS diet (TS0). Results; Results showed that increasing the dose of TS resulted in reduced body weight gain, lower visceral tissue weight, and increased cecal mucin and IgA levels compared with the TS0 group. Further, fecal dry weight increased dose-dependently parallel to the starch excretion rate. Higher doses of TS resulted in increased short chain fatty acid (SCFA) production, specifically cecal acetate content, as well as in a dose-dependent decrease in the cecal pH level. However, this study did not observe a positive effect of TS on colonic alkaline phosphatase (ALP) activity, and the impact on small intestinal ALP activity remains unclear. Notably, beneficial bacteria such as the family Oscillospiraceae, genus Lachnospiraceae NK4A136 group, and Ruminococcus spp. were found to have been enriched in the TS-fed groups, further supporting the beneficial effects of TS on gut microbiota and SCFA production. Additionally, the genus Mucispirillum, which is known to possess beneficial and opportunistic pathogenic traits under immunocompromised states, was found in the TS-fed groups. Conclusions; According to these results, it is clear that TS served as a prebiotic substrate in rats, with a notable modulation of the microbial composition.

Effect of preoperative oral nutritional supplements on clinical outcomes in patients undergoing surgery for gastrointestinal cancer: A systematic review and meta-analysis

BACKGROUND

The clinical benefit of preoperative oral nutritional supplements (ONS) in patients undergoing surgery for gastrointestinal cancer remains controversial.

OBJECTIVE

To evaluate the effect of preoperative ONS on postoperative clinical outcomes in patients with gastrointestinal cancer.

METHODS

We searched PubMed, EMBASE, Web of Science, Cochrane Library, Scopus, and the Chinese National Knowledge Infrastructure databases for randomized controlled trials evaluating preoperative ONS in patients undergoing surgery for gastrointestinal cancer from inception until April 2024. Two researchers independently assessed the quality of the included literature and performed statistical analyses using Review Manager 5.4 software.

RESULTS

A total of 12 eligible studies with 1201 patients (600 ONS group and 601 control group) were included in this meta-analysis. Compared with a normal diet, preoperative ONS effectively reduced infectious complications (odds ratio = 0.63; 95% confidence interval [CI], 0.40-0.98; P = .04), white blood cell count (mean difference [MD] = -0.66; 95% CI, -1.04 to -0.28; P = .0007), C-reactive protein (MD = -0.26; 95% CI, -0.33 to -0.19; P < .00001), and markedly improved albumin levels (MD = 1.71; 95% CI, 0.97-2.46; P < .00001), prealbumin (MD = 24.80; 95% CI, 1.72-47.88; P = .04), immunoglobulin G (MD = 0.86; 95% CI, 0.44-1.28; P < .00001), CD4 T lymphocyte cells (MD = 3.06; 95% CI, 2.21-3.92; P < .00001), and CD4 T lymphocyte cells/CD8 T lymphocyte cells (MD = 0.33; 95% CI, 0.10-0.56; P = .004). However, there were no significant differences between the 2 groups in terms of noninfectious complications (odds ratio = 0.77; 95% CI, 0.39-1.53; P = .46), immunoglobulin A (MD = -0.21; 95% CI, -0.44 to 0.02; P = .08) or length of hospital stay (MD = -0.04; 95% CI, -0.71 to 0.64; P = .92).

CONCLUSION

Preoperative ONS may effectively reduce postoperative infectious complications, improve postoperative nutritional status and immune function, and relieve the inflammatory response in gastrointestinal cancer patients. Therefore, we recommend that preoperative nutrition could be optimized with ONS in patients undergoing gastrointestinal cancer surgery.

The Kynurenine Pathway in Gut Permeability and Inflammation

The gut-brain axis (GBA) is a crucial communication network linking the gastrointestinal (GI) tract and the central nervous system (CNS). The gut microbiota significantly influences metabolic, immune, and neural functions by generating a diverse array of bioactive compounds that modulate brain function and maintain homeostasis. A pivotal mechanism in this communication is the kynurenine pathway, which metabolises tryptophan into various derivatives, including neuroactive and neurotoxic compounds. Alterations in gut microbiota composition can increase gut permeability, triggering inflammation and neuroinflammation, and contributing to neuropsychiatric disorders. This review elucidates the mechanisms by which changes in gut permeability may lead to systemic inflammation and neuroinflammation, with a focus on the kynurenine pathway. We explore how probiotics can modulate the kynurenine pathway and reduce neuroinflammation, highlighting their potential as therapeutic interventions for neuropsychiatric disorders. The review integrates experimental data, discusses the balance between neurotoxic and neuroprotective kynurenine metabolites, and examines the role of probiotics in regulating inflammation, cognitive development, and gut-brain axis functions. The insights provided aim to guide future research and therapeutic strategies for mitigating GI complaints and their neurological consequences.

A study on the causal relationship between the gut microbiome and herpes zoster using Mendelian randomization

Introduction

The relationship between herpes zoster recurrence and the gut microbiome was not studied. We analyzed data on the gut microbiome and herpes zoster from the Large-Scale Genome-Wide Association Study (GWAS) database using bidirectional Mendelian randomization. For the first time, we identified a potentially bidirectional causal relationship between the gut microbiome and herpes zoster (HZ). These findings are groundbreaking and hold promise for new directions in the treatment of HZ, a global disease.

Background and aims

HZ had a high global incidence, characterized by shingled blisters, blood blisters, and neuropathic pain, and could develop in various parts of the body, including the ear and throat. It was believed its onset was closely related to old age and infirmity. Some studies reported that the incidence of herpes zoster in patients with inflammatory intestinal diseases (such as Crohn's disease and ulcerative colitis) was higher than in the general population. Existing studies attributed this to the reactivation of varicella-zoster virus (VZV) due to autoinflammatory attacks and immunosuppressive drugs. This provided a basis for exploring the new pathogenesis of HZ and investigating whether there was a relationship between intestinal auto-flora and the development of HZ. This study aimed to examine this potential relationship using bidirectional Mendelian analyses.

Methods

GWAS data on HZ and gut microbiota were obtained from FinnGen, the Mibiogen consortium, and HZ meta-analysis data from the IEU Open GWAS Project. These data were subjected to two-sample Mendelian randomization (MR) analysis to determine if there is a causal relationship between gut microbiota and HZ. Additionally, bidirectional Mendelian analyses were conducted to identify the direction of causality and to clarify any potential interactions.

Results

In our Mendelian Randomization (MR) analysis, we identified, for the first time, two gut microbes that might be associated with HZ reactivation. In the reverse MR analysis, four gut microbiota showed a potential association between the genetic susceptibility of gut microbiota and HZ reactivation. We found that genus Tyzzerella3 (OR: 1.42, 95% CI: 1.17-1.72, FDR < 0.1) may be strongly correlated with an increased probability of HZ (ICD-10: B02.901) reactivation. Additionally, phylum Cyanobacteria was identified as a potential risk factor for the onset of HZ rekindling (OR: 1.42, 95% CI: 1.09-1.87). Analyzing the results of the reverse MR, we also identified a potential inhibitory effect (OR: 0.91, 95% CI: 0.84-0.99) of HZ onset on the genus Eubacteriumhallii group in the gut, suggesting that HZ might reduce its abundance. However, genus Escherichia/Shigella (OR: 1.11, 95% CI: 1.01-1.22), genus Veillonella (OR: 1.16, 95% CI: 1.04-1.30), and phylum Proteobacteria (OR: 1.09, 95% CI: 1.01-1.18) appeared to act as potential protective factors, indicating that the relative abundance and viability of these three bacteria increased in the HZ state.

Conclusion

We identified the influence of gut flora as a new causative factor for HZ reactivation. Additionally, we found that individuals suffering from HZ might potentially impact their gut flora. Specific bacterial taxa that could influence the onset and progression of HZ were identified, potentially providing new directions for HZ treatment.

Gastrointestinal mucositis: a sign of a (systemic) inflammatory response

PURPOSE OF REVIEW

Gastrointestinal mucositis (GIM) is a significant complication of cancer therapy. Whilst inflammation is a central feature of GIM, studies attempting to mitigate mucosal damage via this mechanism are scarce. This review describes the relation between GIM, local and systemic inflammation, and the microbiome and its metabolites, and explores recent research on therapeutics that target this relationship.

RECENT FINDINGS

Recent literature underscores the pivotal role of inflammation in GIM, elucidating its bidirectional relation with disturbance of the gut microbiota composition and intestinal permeability. These events cause a heightened risk of bloodstream infections and lead to systemic inflammation. While studies investigating risk prediction models or therapeutics targeting GIM-related inflammation remain scarce, results have shown promise in finding biomarkers and alleviating GIM and its accompanying clinical symptoms.

SUMMARY

The findings underscore the important role of inflammation and the microbiome in GIM. Understanding the inflammatory pathways driving GIM is crucial for developing effective treatments. Further research is needed using genomics, epigenomics, and microbiomics to explore better risk prediction models or therapeutic strategies aimed at mitigating GIM-related inflammation.

Sickle Cell Disease Update: New Treatments and Challenging Nutritional Interventions

Sickle cell disease (SCD), a distinctive and often overlooked illness in the 21st century, is a congenital blood disorder characterized by considerable phenotypic diversity. It comprises a group of disorders, with sickle cell anemia (SCA) being the most prevalent and serious genotype. Although there have been some systematic reviews of global data, worldwide statistics regarding SCD prevalence, morbidity, and mortality remain scarce. In developed countries with a lower number of sickle cell patients, cutting-edge technologies have led to the development of new treatments. However, in developing settings where sickle cell disease (SCD) is more prevalent, medical management, rather than a cure, still relies on the use of hydroxyurea, blood transfusions, and analgesics. This is a disease that affects red blood cells, consequently affecting most organs in diverse manners. We discuss its etiology and the advent of new technologies, but the aim of this study is to understand the various types of nutrition-related studies involving individuals suffering from SCD, particularly in Africa. The interplay of the environment, food, gut microbiota, along with their respective genomes collectively known as the gut microbiome, and host metabolism is responsible for mediating host metabolic phenotypes and modulating gut microbiota. In addition, it serves the purpose of providing essential nutrients. Moreover, it engages in direct interactions with host homeostasis and the immune system, as well as indirect interactions via metabolites. Nutrition interventions and nutritional care are mechanisms for addressing increased nutrient expenditures and are important aspects of supportive management for patients with SCD. Underprivileged areas in Sub-Saharan Africa should be accompanied by efforts to define and promote of the nutritional aspects of SCD. Their importance is key to maintaining well-being and quality of life, especially because new technologies and products remain limited, while the use of native medicinal plant resources is acknowledged.