Exclusive Enteral Nutrition Beneficially Modulates Gut Microbiome in a Preclinical Model of Crohn's-like Colitis.

Exclusive enteral nutrition (EEN) is an established dietary treatment for Crohn's disease (CD) by alleviating inflammation and inducing remission. However, the mechanisms of action of EEN are incompletely understood. As CD is associated with gut microbiome dysbiosis, we investigated the effect of EEN on the microbiome in a rat model of CD-like colitis. The rat model of CD-like colitis was established by an intracolonic instillation of TNBS at 65 mg/kg in 250 µL of 40% ethanol. Sham control rats were instilled with saline. Rats were fed ad libitum with either regular pellet food or EEN treatment with a clear liquid diet (Ensure). Rats were euthanized at 7 days. Fecal pellets were collected from the distal colon for 16S rRNA sequencing analysis of gut microbiota. In addition, colon tissues were taken for histological and molecular analyses in all the groups of rats. EEN administration to TNBS-induced CD rats significantly improved the body weight change, inflammation scores, and disease activity index. The mRNA expression of IL-17A and interferon-γ was significantly increased in the colonic tissue in TNBS rats when fed with regular food. However, EEN treatment significantly attenuated the increase in IL-17A and interferon-γ in TNBS rats. Our 16S rRNA sequencing analysis found that gut microbiota diversity and compositions were significantly altered in TNBS rats, compared to controls. However, EEN treatment improved alpha diversity and increased certain beneficial bacteria such as Lactobacillus and Dubosiella and decreased bacteria such as Bacteroides and Enterorhabdus in CD-like rats, compared to CD-like rats with the regular pellet diet. In conclusion, EEN treatment increases the diversity of gut microbiota and the composition of certain beneficial bacteria. These effects may contribute to the reduced inflammation by EEN in the rat model of CD-like colitis.

A recently isolated Lassa virus from Mali demonstrates atypical clinical disease manifestations and decreased virulence in cynomolgus macaques.

The virulence of Soromba-R, a Lassa virus strain recently isolated from southern Mali, was assessed in 2 animal models of Lassa fever: inbred strain 13 guinea pigs and cynomolgus macaques. In both models, the Malian isolate demonstrated tissue tropism and viral titers similar to those of historical Lassa virus isolates from Sierra Leone (Josiah) and Liberia (Z-132); however, the Soromba-R isolate was found to be less pathogenic, as determined by decreased mortality and prolonged time to euthanasia in macaques. Interestingly, in addition to the classic indicators of Lassa fever, Soromba-R infection presented with moderate to severe pulmonary manifestations in the macaque model. Analysis of host responses demonstrated increased immune activation in Soromba-R-infected macaques, particularly in neutrophil-activating or -potentiating proinflammatory cytokines or growth factors, including tumor necrosis factor α, macrophage inflammatory protein 1α, interleukin 1ß, and granulocyte colony-stimulating factor, as well as interleukin 5, which may be responsible for the decreased lethality and uncharacteristic clinical presentation. These results suggest that the strain of Lassa virus circulating in Mali might be less pathogenic than strains circulating in the historical region of endemicity and may result in an atypical presentation for Lassa fever, which could complicate clinical diagnosis.

Antibodies are necessary for rVSV/ZEBOV-GP-mediated protection against lethal Ebola virus challenge in nonhuman primates.

Ebola viruses cause hemorrhagic disease in humans and nonhuman primates with high fatality rates. These viruses pose a significant health concern worldwide due to the lack of approved therapeutics and vaccines as well as their potential misuse as bioterrorism agents. Although not licensed for human use, recombinant vesicular stomatitis virus (rVSV) expressing the filovirus glycoprotein (GP) has been shown to protect macaques from Ebola virus and Marburg virus infections, both prophylactically and postexposure in a homologous challenge setting. However, the immune mechanisms of protection conferred by this vaccine platform remain poorly understood. In this study, we set out to investigate the role of humoral versus cellular immunity in rVSV vaccine-mediated protection against lethal Zaire ebolavirus (ZEBOV) challenge. Groups of cynomolgus macaques were depleted of CD4+ T, CD8+ T, or CD20+ B cells before and during vaccination with rVSV/ZEBOV-GP. Unfortunately, CD20-depleted animals generated a robust IgG response. Therefore, an additional group of vaccinated animals were depleted of CD4+ T cells during challenge. All animals were subsequently challenged with a lethal dose of ZEBOV. Animals depleted of CD8+ T cells survived, suggesting a minimal role for CD8+ T cells in vaccine-mediated protection. Depletion of CD4+ T cells during vaccination caused a complete loss of glycoprotein-specific antibodies and abrogated vaccine protection. In contrast, depletion of CD4+ T cells during challenge resulted in survival of the animals, indicating a minimal role for CD4+ T-cell immunity in rVSV-mediated protection. Our results suggest that antibodies play a critical role in rVSV-mediated protection against ZEBOV.

Recently emerged swine influenza A virus (H2N3) causes severe pneumonia in Cynomolgus macaques.

The triple reassortant H2N3 virus isolated from diseased pigs in the United States in 2006 is pathogenic for certain mammals without prior adaptation and transmits among swine and ferrets. Adaptation, in the H2 hemagglutinin derived from an avian virus, includes the ability to bind to the mammalian receptor, a significant prerequisite for infection of mammals, in particular humans, which poses a big concern for public health. Here we investigated the pathogenic potential of swine H2N3 in Cynomolgus macaques, a surrogate model for human influenza infection. In contrast to human H2N2 virus, which served as a control and largely caused mild pneumonia similar to seasonal influenza A viruses, the swine H2N3 virus was more pathogenic causing severe pneumonia in nonhuman primates. Both viruses replicated in the entire respiratory tract, but only swine H2N3 could be isolated from lung tissue on day 6 post infection. All animals cleared the infection whereas swine H2N3 infected macaques still presented with pathologic changes indicative of chronic pneumonia at day 14 post infection. Swine H2N3 virus was also detected to significantly higher titers in nasal and oral swabs indicating the potential for animal-to-animal transmission. Plasma levels of IL-6, IL-8, MCP-1 and IFNγ were significantly increased in swine H2N3 compared to human H2N2 infected animals supporting the previously published notion of increased IL-6 levels being a potential marker for severe influenza infections. In conclusion, the swine H2N3 virus represents a threat to humans with the potential for causing a larger outbreak in a non-immune or partially immune population. Furthermore, surveillance efforts in farmed pig populations need to become an integral part of any epidemic and pandemic influenza preparedness.

Clinical outcome of henipavirus infection in hamsters is determined by the route and dose of infection.

Nipah virus (NiV) and Hendra virus (HeV) are emerging zoonotic viruses and the causative agents of severe respiratory disease and encephalitis in humans. Little is known about the mechanisms that govern the development of respiratory and neurological disease. Using a hamster model of lethal NiV and HeV infection, we describe the role of the route and dose of infection on the clinical outcome and determine virus tropism and host responses following infection. Infection of hamster with a high dose of NiV or HeV resulted in acute respiratory distress. NiV initially replicated in the upper respiratory tract epithelium, whereas HeV initiated infection primarily in the interstitium. In contrast, infection with a low dose of NiV or HeV resulted in the development of neurological signs and more systemic spread of the virus through involvement of the endothelium. The development of neurological signs coincided with disruption of the blood-brain barrier (BBB) and expression of tumor necrosis alpha (TNF-α) and interleukin 1 ß (IL-1ß). In addition, interferon-inducible protein 10 (IP-10) was identified as playing an important role in NiV and HeV pathogenesis. These studies reveal novel information on the development and progression of NiV and HeV clinical disease, provide a mechanism for the differences in transmission observed between NiV and HeV outbreaks, and identify specific cytokines and chemokines that serve as important targets for treatment.

Endoluminal suturing may overcome the limitations of clip closure of a gaping wide colon perforation (with videos).

BACKGROUND: It is unclear whether large gaping perforations of the colon can be closed by the endoluminal route. OBJECTIVE: To evaluate the feasibility and the outcome of closure of large perforations of colon with clips and sutures by using through-the-endoscope novel devices. DESIGN: Prospective animal study. SETTING: University hospital. PATIENTS: Ten pigs. INTERVENTIONS: Closure of a 4-cm full-thickness colon perforation freshly created by an insulated-tip knife with the InScope Multi-Clip Applier (n = 6) and with the tissue approximation device (n = 4). MAIN OUTCOME MEASUREMENTS: (a) Technical feasibility of closure, (b) clinical monitoring for 2 weeks, (c) necropsy (day 14), (d) healing by a dye-leak test and histology. RESULTS: Endoluminal closure of a 4-cm-long colon perforation was successful in 9 of 10 animals. The clips failed to close a gaping wide colon perforation in 1 animal. The sutures were successful in the closure of both nongaping and gaping perforations. Successful closure resulted in a leakproof sealing at 2 weeks and prevented clinical peritonitis in all the animals in the clip-closure group and in 3 of 4 animals in the suture-closure group. Necropsy at 2 weeks revealed mild peritonitis in 2 of the 5 animals in the clip closure group and in 2 of the 4 animals in the suture-closure group; none developed fecal peritonitis. LIMITATIONS: None. CONCLUSIONS: Endoluminal closure of a 4-cm colon perforation with clips was successful in the majority of cases. Sutures were useful in the closure of gaping colon perforations that could not be closed with clips.

Endoluminal clip closure of a circular full-thickness colon resection in a porcine model (with videos).

BACKGROUND: Linear perforations of the colon can be closed by the application of clips through a colonoscope. It is unclear whether circular perforations after full-thickness resection of the colon can be closed with clips. OBJECTIVE: To develop an animal model for circular perforation of the colon and to study different techniques to accomplish a leakproof sealing of the circular perforation of the colon. DESIGN: Pilot study. SETTING: University medical center. ANIMALS: Ten pigs: 2 perforations in the 1st pig and 1 perforation in the 2nd to 9th pigs were closed with clips. In the 10th pig, 5 perforations were created, and the dimensions of the perforation were measured. INTERVENTIONS: Creation of a circular full-thickness resection of the colon with a band-ligation-resection device, followed by longitudinal or transverse endoluminal closure of the perforation by using the first clip opened and applied in the 3- to 9-o'clock or the 6- to 12-o'clock direction in relation to the circular perforation, respectively. MAIN OUTCOME MEASUREMENTS: The mean (standard deviation) size of circular perforation was 1.7 +/- 0.075 cm (range, 1.5-2.0 cm). Necropsy immediately after closure of the perforation was done to examine the closure and to confirm the quality of sealing with the methylene blue dye leak test. RESULTS: The transverse closure was unsuccessful in the closure of 3 perforations, whereas the longitudinal closure resulted in a leakproof sealing in 6 of the 7 closures. LIMITATIONS: Perforation of the adjacent viscera limits it to a nonsurvival study. CONCLUSIONS: Endoluminal application of clips by using the longitudinal closure technique results in a leak proof sealing of circular perforations of the colon.

Controlled trial of immediate endoluminal closure of colon perforations in a porcine model by use of a novel clip device (with videos).

BACKGROUND: Although endoluminal closure of a small perforation of the colon is technically feasible, the outcome of such a closure is unclear. OBJECTIVE: Our purpose was to evaluate the feasibility and the outcome of endoluminal closure of a small perforation of the colon with a novel clip device, the InScope MultiClip Applier (IMCA), and to assess the number of clips required for successful closure. DESIGN: Prospective controlled study. SETTING: University hospital. ANIMALS: 17 pigs. INTERVENTIONS: A 2-cm full-thickness colon perforation was randomized to 3 groups: control, no closure (n = 4), 2-clip closure (n = 7), and 4-clip closure (n = 6). MAIN OUTCOME MEASUREMENTS: (1) Technical feasibility of closure, (2) closure time, (3) clinical monitoring for 2 weeks, (4) necropsy (day 14), and (5) healing by a dye leak test and histologic examination. RESULTS: Endoscopic closure of the colon perforation was technically successful in 12 of 13 animals. A wide gaping hole prevented satisfactory closure in 1 animal. The median time for closure with 2 and 4 clips was 2 and 3 minutes, respectively. Clip closure of perforation prevented clinical sepsis (P = .008) and diminished the risk for fibrinous peritonitis (P = .02 for a single test of hypothesis; however, correction for the multiple testing of data removes this significance) and adhesion formation (P = .008) compared with controls, without any leakage. The outcomes of 2- and 4-clip closure were similar. CONCLUSIONS: Endoluminal closure of a 2-cm colon perforation with clips is successful in preventing peritonitis and adhesions and it can be accomplished quickly with this novel device. Clip closure at 1-cm intervals is sufficient for successful closure of a 2-cm colon perforation.

Endoluminal closure of large perforations of colon with clips in a porcine model (with video).

BACKGROUND: Endoluminal clip closure of small perforations of the colon is possible. It is unclear whether large perforations of the colon can be closed with clips deployed through a colonoscope. OBJECTIVES: To evaluate the technical feasibility and outcome of endoluminal closure of large perforations of the colon with clips. DESIGN: Pilot study. SUBJECTS: Eight pigs. INTERVENTIONS: Endoluminal clip closure of large perforations of the colon. MAIN OUTCOME MEASUREMENTS: Technical feasibility of endoluminal closure was evaluated in 8 animals. A dye leak test was performed to evaluate quality of endoluminal sealing immediately after closure and 2 weeks after closure. The animals in the survival group were monitored daily for 2 weeks for sepsis and peritonitis. Necropsy was done on day 14 to check for fecal peritonitis, wound dehiscence, and histological healing of perforation. RESULTS: Endoscopic closure of colon perforation was successful in 6 of 8 animals; in 2 animals closure was unsuccessful due to prolapse of adjacent viscera into the colon (n = 1) and severe bleeding that obscured the view (n = 1). There was a leak-proof sealing of the perforation site in 2 animals tested immediately and in all the animals tested (n = 3) 2 weeks after closure. All 4 animals in the survival group recovered well, without any sepsis or peritonitis. Necropsy did not reveal fecal peritonitis or pericolonic abscess formation. The perforation site demonstrated a thin scar and there was histological healing. CONCLUSIONS: Endoluminal application of clips is successful in the closure of a large perforation of the colon in a porcine model.

Immediate endoscopic closure of colon perforation by using a prototype endoscopic suturing device: feasibility and outcome in a porcine model (with video).

BACKGROUND: Perforation is an uncommon but potentially devastating complication of colonoscopy. Surgical closure is the standard of care. Immediate endoluminal closure of a perforation would avoid the morbidity and mortality associated with general anesthesia, laparotomy, and surgical repair. OBJECTIVES: To evaluate the feasibility and safety of full-thickness endoscopic closure of colonic perforations with a prototype endoscopic suturing device, the Eagle Claw, in a porcine model. DESIGN: Endoscopic animal experimental study of closure of colon perforation by using a porcine model. SUBJECTS: Ten pigs were included in the study. INTERVENTIONS: The Eagle Claw was used to close small perforations (1.5 to 2 cm) of the colon created by needle-knife with the animal under general anesthesia by using the endoluminal route. All animals received intravenous antibiotics and were allowed to eat after 24 hours. MAIN OUTCOME MEASUREMENTS: The animals were monitored daily for signs of sepsis and peritonitis. On day 7, they were euthanized. The peritoneal cavity was examined for fecal peritonitis, and the colon perforation site was checked for wound dehiscence and pericolic abscess formation. RESULTS: Endoscopic closure of the colon perforation was successful in 7 animals, and they recovered well without any sepsis or peritonitis. Necropsy did not reveal fecal peritonitis or pericolonic abscess formation at the site of perforation, and the perforation healed well. Closure was successful in 1 animal, but necropsy revealed dehiscence of the colon perforation site. Endoscopic closure was unsuccessful in 2 animals, and these were euthanized immediately. CONCLUSIONS: Closure of acute perforation of the colon is feasible with the Eagle Claw endoscopic suturing device in a porcine model.

A pilot study of endoscopic closure of colonic perforations with endoclips in a swine model.

BACKGROUND: Surgical closure of a colon perforation is accompanied by the risks of general anesthesia and prolonged recovery from surgery because of ileus and other sequelae. Very little is known about the effectiveness of endoluminal repair of colon perforations with clips, which eliminates incisions of the abdominal wall and provides a less invasive alternative to surgical closure. The aim of this study is to evaluate the feasibility and the safety of endoscopic closure of colonic perforations with endoclips in a porcine model. METHODS: Approximately 1.5- to 2-cm colon perforations created with a needle knife in 4 50-kg, female pigs that were under general anesthesia were closed with endoclips. After 24 hours of recovery, the animals were allowed to eat. All the animals received intravenous antibiotics and were carefully monitored for signs of sepsis. After a follow-up of 1 week, the pigs were euthanized for postmortem examination. The fifth pig was euthanized immediately after closure of a 5-cm colon perforation with clips to evaluate the extent of transmural closure with endoclips. RESULTS: The animals recovered well, without any clinical features of sepsis or peritonitis. Postmortem examination did not reveal fecal peritonitis, and there was no evidence of pericolonic abscess formation at the site of perforation. The perforation site showed signs of healing without any evidence of transmural dehiscence. Histopathology demonstrated granulation tissue bridging the site of perforation. In the fifth pig, euthanized immediately after closure of the perforation, nice mucosal apposition was seen, while the muscular and serosal coats remained dehisced. CONCLUSIONS: Endoscopic closure of small iatrogenic colon perforations with clips results in mucosal and submucosal healing and prevents fecal soiling of peritoneal cavity.

A novel shape-locking guide for prevention of sigmoid looping during colonoscopy.

BACKGROUND: Looping of the endoscope in the sigmoid colon and other colonic segments often represents a significant challenge to the performance of comfortable, complete, and swift colonoscopy. This report describes the design and operation of a new device that addresses this problem, together with preliminary preclinical experience with this use of this shape-locking guide (SG-1). METHODS: The shape-locking guide is an overtube that can be converted from a flexible to a rigid configuration on demand. When in the rigid configuration, the shape-locking guide is designed to protect the colon wall from lateral forces exerted by the colonoscope. The shape-locking guide was evaluated in vitro by using an artificial colon model to learn how to operate it, and to assess feasibility for prevention of colon looping. In addition, safety was assessed in vivo in a pig model. RESULTS: In vitro, the shape-locking guide prevented colonic looping and, thereby, aided completion of "colonoscopy" in the artificial colon model. Subsequent in vivo studies demonstrated that use of the shape-locking guide is safe and feasible; it performed well with respect to ease of insertion and avoidance of sigmoid looping. There was no evidence of significant injury to the colon or adjacent abdominal viscera. CONCLUSIONS: This preliminary study shows that use of the shape-locking guide is safe and that it has performance characteristics that may assist the performance of colonoscopy. Human trials are being undertaken.