Olga Zaborina - Academia.edu (original) (raw)

Papers by Olga Zaborina

British Journal of Surgery, Apr 16, 2018

Background: Previous work has demonstrated that anastomotic leak can be caused by collagenolytic ... more Background: Previous work has demonstrated that anastomotic leak can be caused by collagenolytic bacteria such as Enterococcus faecalis via an effect on wound collagen. In humans, E. faecalis is the organism cultured most commonly from a leaking anastomosis, and is not routinely eliminated by standard oral or intravenous antibiotics. Novel strategies are needed to contain the virulence of this pathogen when present on anastomotic tissues. Methods: Polyphosphorylated polymer ABA-PEG20k-Pi20 was tested in mice for its ability to prevent anastomotic leak caused by collagenolytic E. faecalis. The study design included a distal colonic resection and anastomosis followed by introduction of E. faecalis to anastomotic tissues via enema. Mice were assigned randomly to receive either ABA-PEG20-Pi20 or its unphosphorylated precursor ABA-PEG20k in their drinking water. The development of anastomotic leak was determined after the animals had been killed. Results: Overnight incubation of two different E. faecalis collagenolytic strains with 2 mmol/l of ABA-PEG20k-Pi20 led to near complete inhibition of collagenase production (from 21 000 to 1000 and from 68 000 to 5000 units; P < 0⋅001; 6 samples per group) without suppressing bacterial growth. In mice drinking 1 per cent ABA-PEG20k-Pi20, the phosphate concentration in the distal colonic mucosa increased twofold and leak rates decreased from eight of 15 to three of 15 animals (P < 0⋅001). In mice drinking ABA-PEG20k-Pi20, the percentage of collagenolytic colonies among E. faecalis populations present at anastomotic tissue sites was decreased by 6-4800-fold (P = 0⋅008; 5 animals). Conclusion: These data indicate that oral intake of ABA-PEG20k-Pi20 may be an effective agent to contain the virulence of E. faecalis and may prevent anastomotic leak caused by this organism. Clinical relevance Progress in understanding the pathogenesis of anastomotic leak continues to point to intestinal bacteria as key causative agents. The presence of pathogens such as Enterococcus faecalis that predominate on anastomotic tissues despite antibiotic use, coupled with their ability to produce collagenase, appears to alter the process of healing that leads to leakage. Further antibiotic administration may seem logical, but carries the unwanted risk of eliminating the normal microbiome, which functions competitively to exclude and suppress the virulence of pathogens such as E. faecalis. Therefore, non-antibiotic strategies that can suppress the production of collagenase by E. faecalis without affecting its growth, or potentially normal beneficial microbiota, may have unique advantages. The findings of this study demonstrate that drinking a phosphate-based polymer can achieve the goal of preventing anastomotic leak by suppressing collagenase production in E. faecalis without affecting its growth.

Journal of Surgical Research, Feb 1, 2010

Science, Aug 4, 2023

The mammalian gut secretes a family of multifunctional peptides that affect appetite, intestinal ... more The mammalian gut secretes a family of multifunctional peptides that affect appetite, intestinal secretions, and motility whereas others regulate the microbiota. We have found that peptide YY (PYY 1-36 ), but not endocrine PYY 3-36 , acts as an antimicrobial peptide (AMP) expressed by gut epithelial paneth cells (PC). PC-PYY is packaged into secretory granules and is secreted into and retained by surface mucus, which optimizes PC-PYY activity. Although PC-PYY shows some antibacterial activity, it displays selective antifungal activity against virulent Candida albicans hyphae—but not the yeast form. PC-PYY is a cationic molecule that interacts with the anionic surfaces of fungal hyphae to cause membrane disruption and transcriptional reprogramming that selects for the yeast phenotype. Hence, PC-PYY is an antifungal AMP that contributes to the maintenance of gut fungal commensalism.

Annals of Surgery, Dec 5, 2019

Objective:To investigate the role of bacterial- mediated plasminogen activation in the pathogenes... more Objective:To investigate the role of bacterial- mediated plasminogen activation in the pathogenesis of anastomotic leak (AL) and its mitigation by tranexamic acid.Summary background data:AL is the most feared complication of colorectal resections. The pathobiology of AL in the setting of a technically optimal procedure involves excessive submucosal collagen degradation by resident microbes. We hypothesized that activation of the host plasminogen (PLG) system by pathogens is a central and targetable pathway in AL.Methods:We employed kinetic analysis of binding and activation of human PLG by microbes known to cause AL, and collagen degradation assays to test the impact of PLG on bacterial collagenolysis. Further, we measured the ability of the antifibrinolytic drug tranexamic acid (TXA) to inhibit this process. Finally, using mouse models of pathogen-induced AL, we locally applied TXA via enema and measured its ability to prevent a clinically relevant AL.Results:PLG is deposited rapidly and specifically at the site of colorectal anastomoses. TXA inhibited PLG activation and downstream collagenolysis by pathogens known to have a causal role in AL. TXA enema reduced collagenolytic bacteria counts and PLG deposition at anastomotic sites. Postoperative PLG inhibition with TXA enema prevented clinically and pathologically apparent pathogen-mediated AL in mice.Conclusions:Bacterial activation of host PLG is central to collagenolysis and pathogen-mediated AL. TXA inhibits this process both in vitro and in vivo. TXA enema represents a promising method to prevent AL in high risk sites such as the colorectal anastomoses.

Gastroenterology, May 1, 2022

Journal of Surgical Research, Feb 1, 2012

Gastroenterology, May 1, 2023

Arteriosclerosis, Thrombosis, and Vascular Biology, May 1, 2018

Objectives: The goal of this study was to determine if highly collagenolytic bacteria introduced ... more Objectives: The goal of this study was to determine if highly collagenolytic bacteria introduced to the gut microbiome induces abdominal aortic aneurysm in mice. Methods: C57BL/6 mice received a prolonged 4-day course of preoperative antibiotics (oral clindamycin and subcutaneous cefoxitin) and received pre- and postoperative enemas containing either 10% glycerol solution (control) or a freshly prepared bacterial suspension with a highly collagenolytic strain of Serratia marcescens (S2). All mice underwent laparotomy, aortic crush injury with forceps, and application of either 0.9% sodium chloride (control) or 10% calcium chloride to the periadventitial aortic space. Aortic diameter was measured on initial exposure and on sacrifice on postoperative day 21. Groups were compared using a series of Student’s T-test. Results: On postoperative day 21, the difference in aortic diameter for mice treated with periadventitial sodium chloride and glycerol enema was minimal (control 1, n=6, 0.03 mm ± 0.30). In mice treated with periadventitial calcium chloride and glycerol enema, fusiform aneurysm was reliably produced compared to control 1 (control 2, n=6, 0.53 mm ± 0.30, p ≤ 0.05). In mice treated with periadventitial sodium chloride and S2 enema, fusiform aneurysm was reliably produced with a significant difference in diameter compared to control 1 (n=8, 0.63 mm ± 0.30, p ≤ 0.05). In mice treated with periadventitial calcium chloride and S2 enema, fusiform aneurysm was reliably produced with a significant difference in diameter compared to control 1 (n=8, 0.59 mm ± 0.30, p ≤ 0.05). There was no significant difference between the 2 treatment groups. Conclusions: The introduction of highly collagenolytic Serratia marcescens to the gut microbiome of mice in addition to aortic crush injury reliably produces fusiform aortic aneurysm in this model. Further investigation is required to elucidate the mechanism of aneurysm formation.

International Journal of Colorectal Disease, Dec 20, 2016

Purpose Current surgical dogma dictates that tissue ischemia and hypoxia are major contributing f... more Purpose Current surgical dogma dictates that tissue ischemia and hypoxia are major contributing factors in anastomotic leak despite scant evidence. The aim of this study was to determine if tissue hypoxia is a feature of anastomotic leakage in rats following colon resection and segmental devascularization. Methods Rats were randomly assigned to undergo sham operation, segmental colon devascularization alone, colectomy alone, or segmental devascularization plus colectomy. Tissue hypoxia present at the colon anastomosis site across the various treatment groups was determined at sacrifice on postoperative day 6. Pimonidazole HCl was injected 30 min prior to sacrifice. Anastomotic tissues were examined and scored for healing versus leakage using an anastomotic healing score (AHS). Collagen content, hypoxia, enteric smooth muscle and periendothelial stromal patterning, and apoptosis were evaluated histologically. Results No differences in tissue hypoxia were noted in the 16% of anastomotic tissues with poor healing compared to the remaining 84% of rats whose anastomoses healed well. No significant changes were found in cell death in the submucosa of any group. Consistent with previous findings, poor healing was associated with lower collagen content. Submucosal thickness correlated with increased arteriole diameter (R 2 = 0.25, p < 0.005). Conclusions These results demonstrate that tissue hypoxia is not a distinctive feature of anastomotic tissues that fail to heal and leak, even when their blood supply is interrupted. These findings suggest that compensatory factors may mitigate the effects of ischemia and hypoxia during healing of anastomotic tissues and that the process of leakage involves factors beyond their acute effects.

Gastroenterology, Mar 1, 2020

BACKGROUND & AIMS The western diet, which is high in fat, is a modifiable risk factor for col... more BACKGROUND & AIMS The western diet, which is high in fat, is a modifiable risk factor for colorectal recurrence after curative resection. We investigated the mechanisms by which the western diet promotes tumor recurrence, including changes in the microbiome, in mice that underwent colorectal resections. METHODS BALB/c male mice were fed either standard chow diet or western-type diet (characterized by high fat, no fiber, and decreased minerals and vitamins) for 4 weeks; some mice were given antibiotics or ABA-PEG20k-Pi20 (Pi-PEG), which inhibits collagenase production by bacteria but not bacterial growth, in drinking water. Colorectal resections and anastomoses were then performed. The first day after surgery, mice were given enemas containing collagenolytic rodent-derived strain of Enterococcus faecalis (strain E2), and the second day they were given mouse colon carcinoma cells (CT26). Twenty-one days later, distal colons were removed and colon contents (feces, distal colon, and tumor) were collected. Colon tissues were analyzed by histology, for the presence of collagenolytic colonies, and by 16S rRNA sequencing. determined the anatomical distribution of E faecalis at the site of the anastomosis and within tumors using in situ hybridization. Mouse imaging analyses were used to identify metastases. RESULTS Colorectal tumors were found in 88% of mice fed the western diet and given antibiotics, surgery, and E faecalis compared with only 30% of mice fed the standard diet followed by the same procedures. Colon tumor formation correlated with the presence of collagenolytic E faecalis and Proteus mirabilis. Antibiotics eliminated collagenolytic E faecalis and P mirabilis but did not reduce tumor formation. However, antibiotics promoted emergence of Candida parapsilosis, a collagenase-producing microorganism. Administration of a Pi-PEG reduced tumor formation and maintained diversity of the colon microbiome. CONCLUSIONS We identified a mechanisms by which diet and antibiotic use can promote tumorigenesis by colon cancer cells at the anastomosis following colorectal surgery. Strategies to prevent emergence of these microbe communities or their enzymatic activities might be used to reduce the risk of tumor recurrence in patients undergoing colorectal cancer surgery.

Gut, Sep 1, 2020

Objective The gut microbiota are the main source of infections in necrotising pancreatitis. We in... more Objective The gut microbiota are the main source of infections in necrotising pancreatitis. We investigated the effect of disruption of the intestinal microbiota by a Western-type diet on mortality and bacterial dissemination in necrotising pancreatitis and its reversal by butyrate supplementation. Design C57BL/6 mice were fed either standard chow or a Western-type diet for 4 weeks and were then subjected to taurocholate-induced necrotising pancreatitis. Blood and pancreas were collected for bacteriology and immune analysis. The cecum microbiota composition of mice was analysed using 16S rRNA gene amplicon sequencing and cecal content metabolites were analysed by targeted (ie, butyrate) and untargeted metabolomics. Prevention of necrotising pancreatitis in this model was compared between faecal microbiota transplantation (FMT) from healthy mice, antibiotic decontamination against Gram-negative bacteria and oral or systemic butyrate administration. Additionally, the faecal microbiota of patients with pancreatitis and healthy subjects were analysed. Results Mortality, systemic inflammation and bacterial dissemination were increased in mice fed Western diet and their gut microbiota were characterised by a loss of diversity, a bloom of Escherichia coli and an altered metabolic profile with butyrate depletion. While antibiotic decontamination decreased mortality, Grampositive dissemination was increased. Both oral and systemic butyrate supplementation decreased mortality, bacterial dissemination, and reversed the microbiota alterations. Paradoxically, mortality and bacterial dissemination were increased with FMT administration. Finally, patients with acute pancreatitis demonstrated an increase in Proteobacteria and a decrease of butyrate producers compared with healthy subjects. Conclusion Butyrate depletion and its repletion appear to play a central role in disease progression towards necrotising pancreatitis.

BJS open, Sep 6, 2021

Background: Infectious complications following experimental pancreatitis involve major disruption... more Background: Infectious complications following experimental pancreatitis involve major disruptions in the gut microbiota. The aim of this study was to characterize this disruption by examining the spatioregional distribution in microbial community structure and function following experimental pancreatitis associated with pancreatic infection. Methods: Mice were subjected to infusion of the pancreatic duct with either taurocholate to induce necrotizing pancreatitis or normal saline (control group). The spatial (lumen versus mucosa) and regional composition and function of the microbiota from the duodenum, ileum, caecum, colon, pancreas and blood were evaluated using 16S rRNA gene amplicon sequencing. Results: Mice that developed necrotizing pancreatitis demonstrated a decrease in microbial richness and significantly altered microbiota in distal parts of the gastrointestinal tract, compared with controls. Among the most differentially increased taxa were the mucus-degrading Akkermansia muciniphila, and there was a decrease of butyrate-producing bacteria following pancreatitis. Application of the SourceTracker tool to the generated metadata indicated that the duodenum was the most probable source of bacteria that subsequently infected pancreatic tissue in this model. The functional prediction annotation using pathway analyses indicated a diminished capacity of the caecal microbiota to metabolize carbohydrate, and fatty and amino acids. Discussion: The distal gut microbiota was significantly impacted in this model of experimental necrotizing pancreatitis. Data suggest that the duodenal microbiota might also play a role in bacterial translation and secondary infections. Surgical Relevance Intestinal bacteria are key disease modifiers in severe acute pancreatitis, especially when it comes to secondary infections such as pneumonia, bacteraemia and infected (peri-)pancreatic necrosis. Efficient and safe targeting of gut microbes as a way of prophylaxis warrants a deeper understanding of which bacteria in which intestinal compartment contribute to disease progression. This study investigated whether induction of necrotizing pancreatitis impacted the composition and function of the spatioregional gut microbiota in mice. Necrotizing pancreatitis had a major effect on the microbiota distribution of the distal gastrointestinal tract with a reduction of butyrate-producing bacteria. The duodenum was identified as the main source of pancreatic infection in the model. These data suggest that microbial communities of both the upper and lower gastrointestinal tract might represent future targets for prophylaxis in patients with severe acute pancreatitis.

Neoplasia, May 1, 2022

Much about the role of intestinal microbes at the site of colon cancer development and tumor prog... more Much about the role of intestinal microbes at the site of colon cancer development and tumor progression following curative resection remains to be understood. We have recently shown that collagenolytic bacteria such as Enterococcus faecalis predominate within the colon postoperatively, particularly at the site of the colon reconnection (i.e. anastomosis) in the early period of post-surgical recovery. The presence of collagenolytic bacteria at this site correlates with the tumor progression in a mouse model of post-surgical tumor development. In the present study we hypothesized, that collagenolytic bacteria, such as E. faecalis, play an important yet to be discovered role in tumor formation and progression. Therefore the aims of this study were to assess the role of collagenolytic E. faecalis on the migration and invasion of a murine colon cancer cell line. Results demonstrated that both migration and invasion were induced by E. faecalis with collagenolytic activity being required for only invasion. Bidirectional signaling in the E. faecalis-cancer cell interaction was observed by the discovering that the expression of gelE in E. faecalis, the gene required for collagenase production, is expressed in response to exposure to CT26 cells. The mechanism by which migration enhancement via E. faecalis occurs appears to be dependent on its ability to activate pro-uPA, a key element of the urokinase-plasminogen system, a pathway that is well – known to be important in cancer cell invasion and migration. Finally, we demonstrated that collagenase producing microbes preferentially colonize human colon cancer specimens.

American Journal of Physiology-gastrointestinal and Liver Physiology, 2020

Enterococcus faecalis exploits the human fibrinolytic system to drive excess collagenolysis: impl... more Enterococcus faecalis exploits the human fibrinolytic system to drive excess collagenolysis: implications in gut healing and identification of druggable targets.

Journal of Surgical Research, Feb 1, 2014

Medical Hypotheses, Nov 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Diseases of The Colon & Rectum, Aug 1, 2019

BACKGROUND:Bacteria that produce collagen digesting enzymes (collagenolytic bacteria) have been s... more BACKGROUND:Bacteria that produce collagen digesting enzymes (collagenolytic bacteria) have been shown to play a critical and previously unappreciated role in anastomotic leak pathogenesis by breaking down host tissue extracellular matrix proteins. Detection of these bacteria is labor intensive and no screening method currently exists.OBJECTIVES:In this report we evaluate a rapid screening method developed to detect the presence of these collagenolytic bacteria in clinical samples such as drain fluid, anastomotic tissue, or feces.DESIGN:We compared a new method of detecting collagenolytic bacterial species with a previously used technique using samples from a murine experimental model and then demonstrated the utility of this screening method in samples from patients with anastomotic complications.SETTING:All laboratory work and prior murine experiments were performed in Dr. Alverdy’s laboratory at the University of Chicago under IRB approved protocols.MAIN OUTCOME MEASURES:Whether this analysis can influence patient management and outcomes will require further study.PATIENTS:Samples from patients with challenging wound complications were provided by participating clinicians with verbal patient consent. Given the small number of patients this was determined to be IRB exempt.RESULTS:This screening method detects numerous strains of bacteria with collagenolytic properties, including the collagenolytic species that have previously been implicated in anastomotic leak. Once collagenolytic strains are identified, they can be speciated and tested for antibiotic resistance using standard laboratory techniques.LIMITATIONS:This study is limited by the small number of patient samples tested.CONCLUSION:Here we demonstrate the potential applicability of this assay to evaluate rare and complex anastomotic complications that often require analysis beyond standard culture and sensitivity assays. Future applications of this method may allow development of strategies to prevent anastomotic leak related to collagenolytic bacteria. See Video Abstract at http://links.lww.com/DCR/Axxx.

The journal of trauma and acute care surgery, Apr 1, 2015

Background-Wound infections are traditionally thought to occur when microbial burden exceeds the ... more Background-Wound infections are traditionally thought to occur when microbial burden exceeds the innate clearance capacity of host immune system. Here we introduce the idea that the wound environment itself plays a significant contributory role to wound infection. Methods-We developed a clinically relevant murine model of soft tissue infection to explore the role of activation of microbial virulence in response to tissue factors as a mechanism by which pathogenic bacteria cause wound infections. Mice underwent abdominal skin incision and light muscle injury with a crushing forceps versus skin incision alone followed by topical inoculation of P. aeruginosa. Mice were sacrificed on postoperative day 6 and abdominal tissues analyzed for clinical signs of wound infection. To determine if specific wound tissues components induce bacterial virulence, P. aeruginosa was exposed to skin, fascia, and muscle. Results-Gross wound infection due to P. aeruginosa was observed to be significantly increased in injured tissues vs non-injured (80% vs 10%) tissues (n=20/group, p<0.0001). Exposure of P. aeruginosa to individual tissue components demonstrated that fascia significantly induced bacterial virulence as judged by the production of pyocyanin, a redox-active phenazine compound known to kill immune cells. Whole genome transcriptional profiling of P. aeruginosa exposed to fascia demonstrated activation of multiple genes responsible for the synthesis of the iron scavenging molecule pyochelin. Conclusion-We conclude that wound elements, in particular fascia, may play a significant role in enhancing the virulence of P. aeruginosa and may contribute to the pathogenesis of clinical wound infection.