Diet-induced shifts in the gut microbiota influence anastomotic healing in a murine model of colonic surgery

Host diet and gut microbiota interact to contribute to perioperative complications, including anastomotic leak (AL). Using a murine surgical model of colonic anastomosis, we investigated how diet and fecal microbial transplantation (FMT) impacted the intestinal microbiota and if a predictive signature for AL could be determined. We hypothesized that a Western diet (WD) would impact gut microbial composition and that the resulting dysbiosis would correlate with increased rates of AL, while FMT from healthy, lean diet (LD) donors would reduce the risk of AL. Furthermore, we predicted that surgical outcomes would allow for the development of a microbial preclinical translational tool to identify AL. Here, we show that AL is associated with a dysbiotic microbial community characterized by increased levels of Bacteroides and Akkermansia. We identified several key taxa that were associated with leak formation, and developed an index based on the ratio of bacteria associated with the absence and presence of leak. We also highlight a modifiable connection between diet, microbiota, and anastomotic healing, potentially paving the way for perioperative modulation by microbiota-targeted therapeutics to reduce AL.

The Influence of the Microbiome on Anastomotic Leak

Anastomotic leak, defined by the International Study Group of Rectal Cancer as "a communication between the intra- and extraluminal compartments owing to a defect of the integrity of the intestinal wall at the anastomosis," is one of the most devastating complications in colorectal surgery. Much work has been done to identify causes of leak; however, despite advances in surgical technique, the prevalence of anastomotic leak has remained at around 11%. The potential causative role of bacteria in the etiopathology of anastomotic leak was established in the 1950s. More recently, alterations in the colonic microbiome have been shown to affect rates of anastomotic leak. Multiple perioperative factors that alter the homeostasis of the gut microbiota community structure and function have been linked to anastomotic leak after colorectal surgery. Here, we discuss the role of diet, radiation, bowel preparation, medications including nonsteroidal anti-inflammatory drugs, morphine, and antibiotics, and specific microbial pathways that have been implicated in anastomotic leak via their effects on the microbiome.

Endoscopic polypectomy for malignant polyps: Should tumor location (right versus left side) guide clinical decisions?

BACKGROUND

Current guidelines consider endoscopic resection appropriate treatment for malignant colon polyps with negative margins, low-grade histology, and no lymphovascular invasion. While increasing literature demonstrates a worse prognosis for advanced stage right- versus left-sided colon cancers after curative treatment, there is paucity of data regarding prognostic effect of location in patients undergoing endoscopic resection of T1 polyps. We hypothesized the more aggressive biologic behavior observed in advanced right-sided cancers would be similarly represented in malignant polyps, and this location would be associated with lower overall survival.

METHODS

The National Cancer Database was queried for adults with T1NxMx tumors who underwent endoscopic polypectomy (2004-2017). Patients with positive margins or without follow-up information were excluded.

RESULTS

A total of 2,337 patients met inclusion criteria; 22% had right-sided polyps. Endoscopically excised proximal tumors were more common in elderly, and those with public insurance and more comorbidities (all P < .01). Among patients with complete pathologic data, there were no statistical differences between right- and left-sided polyps with 1 cm median size, >92% without lymphovascular invasion, and 100% without tumor deposits. Univariate analysis showed 73% vs 86% 5-year overall survival for right versus left polyps (P < .01). After adjustment for available confounders, right-sided location remained significantly associated with worse overall survival (hazard ratio 1.49, 95% confidence interval 1.21-1.83).

CONCLUSION

In this national cohort of patients with endoscopically excised malignant polyps, we identified right colon location as an independent prognostic factor associated with increased risk of mortality. Our data suggest polyp location should be taken into consideration when making clinical decisions regarding treatment and/or surveillance.

Colon and Rectal Cancer Management in Low-Resource Settings

Colorectal cancer (CRC) incidence is rising in low- and middle-income countries, which also face disproportionate mortality from CRC, mainly due to diagnosis at late stages. Various challenges to CRC care exist at multiple societal levels in underserved populations. In this article, barriers to CRC care, strategies for screening, and treatment in resource-limited settings, and future directions are discussed within a global context.

Equivalency of short-term perioperative outcomes after open, laparoscopic and robotic ileal anal pouch anastomosis. Does procedure complexity override operative approach?

Background

Ileal pouch anal anastomosis is the treatment of choice for patients with chronic ulcerative colitis and familial adenomatous polyposis undergoing a proctocolectomy and desiring bowel continuity. It is a technically complex operation associated with significant morbidity and may be performed by an open, laparoscopic, or robotic approach. However, there is a paucity of data regarding the comparative perioperative outcomes between these 3 techniques outside of institutional studies.

Methods

The NSQIP targeted proctectomy data set was used to identify patients who underwent open, laparoscopic, and robotic ileal pouch anal anastomosis between 2016 and 2019. Thirty-day outcomes between different surgical approaches were compared using univariate and multivariable analysis.

Results

During the study period, 1,067 open, 971 laparoscopic, and 341 robotic ileal pouch anal anastomosis were performed. The most frequent indications were inflammatory bowel disease (64%), malignancy (18%), and familial adenomatous polyposis (7%). Mean age of the cohort was 43 ± 15 years with 43% female and 76% with body mass index ≤ 30 kg/m². Overall morbidity was 26.8% for the entire cohort with 4% anastomotic leak, 6% reoperation, 21% ileus, and 21% readmission rate. After adjusting for available confounders, operative approach was not associated with better short-term outcomes, including length of stay, overall morbidity, anastomotic leak, reoperation, incidence of ileus, and 30-day readmissions.

Conclusion

Ileal pouch anal anastomosis continues to be associated with significant postoperative morbidity regardless of operative approach. Patient-related advantages in terms of perioperative outcomes for laparoscopic and robotic platforms compared to open surgery are less pronounced in complex operations such as ileal pouch anal anastomosis.

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Ileal anal pouch anastomosis is a technically complex operation associated with significant postoperative 30-day morbidity.

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Postoperative morbidity is similar between open, laparoscopic, and robotic approaches.

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In complex operations such as ileal anal pouch anastomosis, the short-term perioperative advantages of minimally invasive approaches may not be clinically evident.

Encapsulated Fecal Microbiota Transplantation: Development, Efficacy, and Clinical Application

Fecal microbiota transplantation (FMT) has been established as a highly restorative therapeutic approach for treating recurrent Clostridioides difficile infection (rCDI). Recently, the use of capsule-based fecal microbiota transplantation (cFMT) has been shown to be a clinically effective approach to restore intestinal microbiota composition. This convenient, oral delivery provides an easy route of administration and a newfound flexibility for clinicians and patients. In this review, we discuss the development of cFMT, paying particular attention to lyophilized cFMT products. We review the available published clinical studies comparing cFMT with lower endoscopic FMT (eFMT) or placebo. We further discuss the pharmacokinetics of FMT, which should be understood in a framework of microbial ecology that considers the complex and dynamic interactions of gut microbiota with host factors and other microorganisms. Promisingly, the results of multiple trials investigating cFMT vs. eFMT in rCDI show cFMT to be as effective as eFMT at preventing rCDI. However, its efficacy in non-rCDI conditions, including obesity and metabolic syndrome, inflammatory bowel disease, HIV, and neurologic conditions, is less clear and more research is needed in these areas. Standardization of formulation, dose, and timing of administration to ensure optimal microbiota engraftment and clinical response is also a challenge to be addressed. Overall, cFMT is a practical method for fecal microbiota transplantation, with similar efficacy to eFMT in the resolution of rCDI, that holds therapeutic potential in a variety of other diseases.

Common variants in signaling transcription-factor-binding sites drive phenotypic variability in red blood cell traits

Genome-wide association studies identify genomic variants associated with human traits and diseases. Most trait-associated variants are located within cell-type-specific enhancers, but the molecular mechanisms governing phenotypic variation are less well understood. Here, we show that many enhancer variants associated with red blood cell (RBC) traits map to enhancers that are co-bound by lineage-specific master transcription factors (MTFs) and signaling transcription factors (STFs) responsive to extracellular signals. The majority of enhancer variants reside on STF and not MTF motifs, perturbing DNA binding by various STFs (BMP/TGF-β-directed SMADs or WNT-induced TCFs) and affecting target gene expression. Analyses of engineered human blood cells and expression quantitative trait loci verify that disrupted STF binding leads to altered gene expression. Our results propose that the majority of the RBC-trait-associated variants that reside on transcription-factor-binding sequences fall in STF target sequences, suggesting that the phenotypic variation of RBC traits could stem from altered responsiveness to extracellular stimuli.

Angiopoietin-like proteins stimulate HSPC development through interaction with notch receptor signaling

Angiopoietin-like proteins (angptls) are capable of ex vivo expansion of mouse and human hematopoietic stem and progenitor cells (HSPCs). Despite this intriguing ability, their mechanism is unknown. In this study, we show that angptl2 overexpression is sufficient to expand definitive HSPCs in zebrafish embryos. Angptl1/2 are required for definitive hematopoiesis and vascular specification of the hemogenic endothelium. The loss-of-function phenotype is reminiscent of the notch mutant mindbomb (mib), and a strong genetic interaction occurs between angptls and notch. Overexpressing angptl2 rescues mib while overexpressing notch rescues angptl1/2 morphants. Gene expression studies in ANGPTL2-stimulated CD34(+) cells showed a strong MYC activation signature and myc overexpression in angptl1/2 morphants or mib restored HSPCs formation. ANGPTL2 can increase NOTCH activation in cultured cells and ANGPTL receptor interacted with NOTCH to regulate NOTCH cleavage. Together our data provide insight to the angptl-mediated notch activation through receptor interaction and subsequent activation of myc targets.

Opioid requirement, opioid receptor expression, and clinical outcomes in patients with advanced prostate cancer

BACKGROUND

Preclinical studies show that opioids stimulate angiogenesis and tumor progression through the mu opioid receptor (MOR). Although MOR is overexpressed in several human malignancies, the effect of chronic opioid requirement on cancer progression or survival has not been examined in humans.

METHODS

We performed a retrospective analysis on 113 patients identified in the Minneapolis VA Tumor Registry (test cohort) and 480 patients from the national VA Central Cancer Registry (validation cohort) who had been diagnosed with stage IV prostate cancer between 1995 and 2010 to examine whether MOR expression or opioid requirement is associated with disease progression and survival. All opioids were converted to oral morphine equivalents for comparison. Laser scanning confocal microscopy was used to analyze MOR immunoreactivity in prostate cancer biopsies. The effects of variables on outcomes were analyzed in univariable and multivariable models.

RESULTS

In patients with metastatic prostate cancer, MOR expression and opioid requirement were independently associated with inferior progression-free survival (hazard ratio [HR] 1.65, 95% confidence interval [CI] 1.33-2.07, P<.001 and HR 1.08, 95% CI 1.03-1.13, P<.001, respectively) and overall survival (HR 1.55, 95% CI 1.20-1.99, P<.001 and HR 1.05, 95% CI 1.00-1.10, P = .031, respectively). The validation cohort confirmed that increasing opioid requirement was associated with worse overall survival (HR 1.005, 95% CI 1.002-1.008, P = .001).

CONCLUSION

Higher MOR expression and greater opioid requirement are associated with shorter progression-free survival and overall survival in patients with metastatic prostate cancer. Nevertheless, clinical practice should not be changed until prospective randomized trials show that opioid use is associated with inferior clinical outcomes, and that abrogation of the peripheral activities of opioids ameliorates this effect.

Assaying hematopoiesis using zebrafish

The zebrafish has become a commonly used model for studying hematopoiesis as a result of its unique attributes. Zebrafish are highly suitable for large-scale genetic and chemical screens compared to other vertebrate systems. It is now possible to analyze hematopoietic lineages in zebrafish and validate cell function via transplantation assays. Here, we review advancements over the past decade in forward genetic screens, chemical screens, fluorescence-activated cell sorting analysis, and transplantation assays. Integrating these approaches enables new chemical and genetic screens that assay cell function within the hematopoietic system. Studies in zebrafish will continue to contribute and expand our knowledge about hematopoiesis, and develop novel treatments for clinical applications.