Mesenteric Tissue Research Articles

Ultrastructure and phylogenetic characterization of the microsporidian parasite Heterosporis lessepsianus n. sp. (Microsporidia: Glugeidae) infecting the lizardfish Saurida lessepsianus (Pisces: Synodontidae) inhabiting the Red Sea

Heterosporosis is an increasingly important microsporidian disease distributed worldwide, impacting wild and farmed-raised fish in both fresh and marine water environments. Twenty three out of 130 (17.69%) of the lizardfish Saurida lessepsianus were found to be naturally infected with microsporidian parasites. The rate of parasitic infection was increased during winter reaching 29.23% (19/65) and fall to 6.15% (4/65) in summer. The infection was recorded as numerous macroscopic whitish cysts reached 3.8–6.5 mm in diameter embedded in the abdominal cavity, skeletal muscles and mesenteric tissues of the infected fish inducing an enormous hypertrophy of infected tissues. Light microscopic examination revealed that parasitic foci were encapsulated by a host–derived fibrous membrane containing different developmental stages of the parasite. Spores were oval to pyriform in shape. Transmission electron microscopic study showed the presence of smooth membranes of the sarcoplasmic reticulum forming a thick, amorphous coat surrounding the various developmental stages of the examined parasite (meronts, sporont, sporoblasts, and spores). Mature spores were electron dense and uninucleate. The anchoring disk was found in a central position at the anterior end of the spore and a large vacuole was located at the posterior end. There was a definite number (7–8) of the polar filament turns. Molecular analysis based on the 16 small subunit (SSU) rDNA gene was performed to determine the phylogenetic position of the present parasite species. A 615 bp region of the 16SSU rDNA gene of the studied parasite was sequenced and deposited in GenBank under the accession number MF769371. Multiple sequence alignment demonstrated a high degree of similarity (>82%) with other twenty microsporidian species isolated from different aquatic hosts. The most closely related sequence was provided by the GenBank entry JF745533 for Heterosporis saurida isolated from the marine fish Saurida undosquamis with the highest percentage of identity (98%) and lowest divergence value (0.9). The ultrastructural characteristics and phylogenetic analysis support the recognition of a new species, herein named Heterosporis lessepsianus sp. n.

Effect of feeding Chinese herb medicine ageratum-liquid on intestinal bacterial translocations induced by H9N2 AIV in mice

BackgroundAs a low pathogenic influenza virus, avian influenza virus subtype H9N2 (H9N2 AIV) often induces high morbidity in association with secondary bacterial infections in chickens or mammals. To explore this phenomenon, the relationship between intestinal microflora changes and bacterial translocations was studied post H9N2 AIV challenge and post AIV infection plus Ageratum-liquid treatment.MethodsIllumina sequencing, histological examination and Neongreen-tagged bacteria were used in this study to research the microbiota composition, intestinal barrier, and bacterial translocation in six weeks of BALB/c mice.ResultsH9N2 AIV infection caused intestinal dysbacteriosis and mucosal barrier damages. Notably, the villus length was significantly reduced (p < 0.01) at 12 dpi and the crypt depth was significantly increased (p < 0.01) at 5 dpi and 12 dpi with infection, resulting in the mucosal regular villus-length/crypt-depth (V/C) was significantly reduced (p < 0.01) at 5 dpi and 12 dpi. Moreover, degeneration and dissolution of the mucosal epithelial cells, loose of the connective tissue and partial glandular atrophy were found in infection group, indicating that intestinal barrier function was weakened. Eventually, intestinal microbiota (Staphylococcus, E. coli, etc.) overrun the intestinal barrier and migrated to liver and lung tissues of the mice at 5 and 12 dpi. Furthermore, the bacteria transferred in mesentery tissue sites from intestine at 36 h through tracking the Neongreen-tagged bacteria. Then the Neongreen-tagged bacteria were isolated from liver at 48 h post intragastrical administration. Simultaneously, Ageratum-liquid could inhibit the intestinal microbiota disorder post H9N2 AIV challenge via the respiratory tract. In addition, this study also illustrated that Ageratum-liquid could effectively prevent intestinal bacterial translocation post H9N2 AIV infection in mice.ConclusionIn this study, we report the discovery that H9N2 AIV infection could damage the ileal mucosal barrier and induce the disturbance of the intestinal flora in BALB/c mice resulting in translocation of intestinal bacteria. In addition, this study indicated that Ageratum-liquid can effectively prevent bacterial translocation following H9N2 infection. These findings are of important theoretical and practical significance in prevention and control of H9N2 AIV infection.

Expression of SPARC in smooth muscle tissue of ob/ob mice and its clinical significance

Objective To investigate the secreted protein acidic and rich in cysteine (SPARC) expression in the smooth muscle tissue of ob/ob mice. Methods Study time: February 2017 to June 2017.Six ob/ob mice and 6 littermates aged 10 weeks were selected for the trial.The mesenteric artery smooth muscle tissues were collected.qRT-PCR was used to detect SPARC mRNA expression in smooth muscle tissue.The protein expression of SPARC was assayed by Western blot. Results The SPARC mRNA[(1.73±0.65)] and protein[(1.73±0.65)] in smooth muscle tissue of ob/ob mice presented higher expression compared with those in the littermates[(1.00±0.31), (1.00±0.33), t=8.437, 5.533, all P<0.05]. Conclusion The higher expression of SPARC in smooth muscles tissue of ob/ob mice may be involved in diabetes combined with atherosclerosis. Key words: Secreted protein acidic and rich in cysteine; Mice; Artery smooth muscle tissue; Diabetes; Mesentery; Expression; Atherosclerosis

Differential effects of the retinopathy of prematurity exam on the physiology of premature infants.

Objective:To compare the differential effects of the retinopathy of prematurity (ROP) examination on the physiology of premature infants with and without oxygen support.Study Design:We collected data from 42 premature infants (room air = 19, oxygen support = 23) and compared physiological metrics including heart rate (HR), systemic peripheral saturation (SpO2), mesenteric tissue oxygen saturation (StO2) and clinical events (oxygen desaturation episodes, bradycardia events, and gastric residuals).Results:We found significant differences between groups in HR during and briefly after the exam, and in mesenteric StO2, during eye drop administration, eye exam, and up to 8 minutes after the exam. SpO2 was significantly different between the groups at all time points. Gastric residuals were higher after the exam in infants on oxygen support, compared to baseline.Conclusion:Premature infants on oxygen support may be at a higher risk of adverse physiologic effects in response to the ROP exam.

Allergic Airway-Induced Hypersensitivity Is Attenuated by Bergapten in Murine Models of Inflammation

Bergapten (5-methoxypsoralen, 5-MOP) is a plant-derived furocoumarin with demonstrated anti-inflammatory action. The present study investigated its effects on allergic inflammation in two related pathways of mast cell degranulation. Compound 48/80 and lipopolysaccharide (LPS) were used to activate the IgE-independent pathway while bovine serum albumin (BSA) was used as allergen for the IgE-dependent pathway. The modulatory effect of bergapten on mast cell degranulation, neutrophil extravasation, protein concentration, lung histopathology, and oxidative stress was assessed. Bergapten at 10, 30, and 100 μg/ml for 15 min stabilized mast cells in rat mesenteric tissue from disruption in vitro and when administered in vivo at 3, 10, and 30 mg kg−1 for 1 h protected mice from fatal anaphylaxis induced by compound 48/80. Similarly, treatment of LPS-challenged mice with bergapten (3, 10, and 30 mg kg−1) for 24 h significantly decreased neutrophil infiltration into bronchoalveolar lavage fluid, mean protein concentration, and inflammatory cell infiltration of pulmonary tissues when compared to the saline-treated LPS-challenged control. In addition, lung histology of the bergapten-treated LPS-challenged mice showed significantly less oedema, congestion, and alveolar septa thickening when compared to the saline-treated LPS-challenged disease control. LPS-induced oxidative stress was significantly reduced through increased tissue activities of catalase and superoxide dismutase and reduced malondialdehyde levels on treatment with bergapten. In the triple antigen-induced active anaphylaxis, daily administration of bergapten at 3, 10, and 30 mg kg−1 for 10 days, respectively, protected previously sensitized and challenged mice against anaphylactic shock. Overall, our study demonstrates the ability of bergapten to attenuate allergic airway-induced hypersensitivity in murine models of inflammation, suggesting its possible therapeutic benefit in this condition.

Second evaluation of the mesenteric tissue after ethanol fixation improved the total and metastatic number of lymph nodes in colorectal resections

There is a correlation between prognosis of the colorectal carcinomas and the number of retrieved and metastatic lymph nodes (LNs) from mesentery/mesorectal region. At least 12 LNs must be sampled for accurate evaluation of patients. A number of factors related to surgeon, pathologist, patient and disease could affect the total LN number. For maximizing LN yield, pathologist can use ancillary methods, as fat clearance and special solutions. This study investigates the effect of second evaluation after ethanol fixation on total and metastatic LN number and assesses factors that influence the dissected LN number. 177 colorectal resections were refixed with ethanol for a night, after standard LN sampling. Mesentery/mesorectal tissue was reevaluated for missed LNs. Results were statistically analyzed, P values <0.05 were considered significant. Mean LN number increased from 26 to 30 (median: 20 to 25, P < 0.001) after ethanol fixation. Fourteen cases had additional metastatic LNs after reevaluation of the fat tissue and 5 of them upstaged. 22.5% (44/177) of the patients had <12 LNs before ethanol fixation and this decreased to 14.3% (26/177) after ethanol fixation. Resection type and length, tumor localization, size and histologic degree, pT and neoadjuvant therapy (P < 0.001) had an impact on the LN number (P = 0.034 for histologic degree, P = 0.02 for pT, P < 0.001 for others). Carrying out a second evaluation with ethanol fixation increased total and metastatic LN number and could lead upstage of pN. Ethanol fixation is cost-effective, easy accessible and applicable method; it may improve accuracy of LN assessment and staging, which are important for patients' outcome.

Moringa oleifera Leaf Petroleum Ether Extract Inhibits Lipogenesis by Activating the AMPK Signaling Pathway.

In recent years, obesity has become a key factor affecting human health. Moringa oleifera Lam. is a perennial tropical deciduous tree, which is widely used in human medicine due to its nutritional and unique medicinal value. It has a cholesterol-lowering effect, but its mechanism of action is unclear. In this study, we elucidated the inhibitory effect of M. oleifera leaf petroleum ether extract (MOPEE) on lipid accumulation by in vitro and in vivo experiments, and we described its mechanism of action. MOPEE suppressed adipogenesis in 3T3-L1 adipocytes in a dose-dependent manner and had no effect on cell viability at doses up to 400 μg/ml. Furthermore, MOPEE (400 μg/ml) significantly downregulated the expression of adipogenesis-associated proteins [peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding proteins α and β (C/EBPα and C/EBPβ), and fatty acid synthase (FAS)] and upregulated the expression of a lipolysis-associated protein [hormone-sensitive lipase (HSL)] in 3T3-L1 adipocytes. Additionally, MOPEE (400 μg/ml) significantly increased the degree of phosphorylation of AMP-activated protein kinase α (AMPKα) and acetyl-CoA carboxylase (ACC). An AMPK inhibitor reversed the MOPEE-induced activation of AMPKα and ACC in 3T3-L1 adipocytes. Animal experiments showed that, in high-fat diet (HFD) mice, MOPEE [0.5 g/kg body weight (BW)] effectively decreased BW; relative epididymal, perirenal, and mesenteric fat weight and fat tissue size; and hepatic fat accumulation. Furthermore, MOPEE markedly reduced the serum levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and aspartate aminotransferase (AST). Moreover, MOPEE significantly downregulated the expression of adipogenesis-associated proteins (PPARγ and FAS) and upregulated the expression of a lipolysis-associated protein [adipose triglyceride lipase (ATGL)] in HFD mice hepatic and epididymal fat tissue. Additionally, MOPEE markedly increased the degree of phosphorylation of AMPKα and ACC in HFD mice hepatic and epididymal fat tissue. Following ultrahigh-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UPLC-QTOF-MS/MS) analysis, three phytocompounds (isoquercitrin, chrysin-7-glucoside, and quercitrin) were identified as compounds with relatively high levels in MOPEE. Among them, quercitrin showed excellent fat accumulation inhibitory activity, and the three compounds had synergistic effects in inhibiting adipogenesis. Taken together, MOPEE inhibits fat accumulation by inhibiting the adipogenesis and promoting the lipolysis, and this process is related to AMPK activation.

NADPH oxidase 1/4 inhibition attenuates the portal hypertensive syndrome via modulation of mesenteric angiogenesis and arterial hyporeactivity in rats

NADPH oxidase (NOX)-derived reactive oxygen species (ROS) plays key roles in the development of portal hypertension (PHT) and represents a potential therapeutic method. The objective of this study was to investigate whether pharmacological inhibition of NADPH oxidase activity could ameliorate PHT in rats. PHT model was established by partial portal vein ligation (PPVL). Rats were treated with 30 mg/kg GKT137831 (the most specific Nox1/4 inhibitor) or vehicle daily by gavage for 14 days beginning at the day of PPVL or sham operation (SO). Hemodynamics, severity of portal-systemic shunting, vascular contractility, vascular endothelial growth factor (VEGF), VEGFR-2, CD31, AKT, phospho-AKT (p-AKT, at Ser473), endothelial nitric oxide synthase (eNOS), and phospho-eNOS (p-eNOS, at Ser1177) expressions were evaluated. Nitric oxide (NO) production and oxidative stress in mesenteric arteries, and hydrogen peroxide (H2O2) in both mesenteric tissues and arteries were measured. Inhibition of NOX1/4 with GKT137831 significantly decreased cardiac index, increased portal flow resistance, reduced portal pressure (PP), portal blood flow, mesenteric angiogenesis and portal-systemic shunting (PSS) in PPVL rats. GKT137831 reduced the production of H2O2, down regulated mesenteric angiogenesis markers (CD31, vascular endothelial growth factor (VEGF) and VEGFR-2 expression. Compared with controls), the mesenteric artery contraction to norepinephrine (NE) was impaired in PPVL rats, which was reversed by exposure to GKT137831. In addition, GKT137831 markedly decrease NADPH oxidase activity and ROS production in mesenteric arteries, and reduced NO production by decreasing the level of phosphor-AKT and eNOS. Inhibition of NOX1/4 decreased PP, ameliorated hyperdynamic circulation, mesenteric angiogenesis and arterial hyporesonse in portal hypertensive rats. Pharmacological inhibition of NOX1/4 activity may be a potential treatment for PHT-related complications.

Induction of microvascular network growth in the mouse mesentery.

Motivated by observations of mesenteries harvested from mice treated with tamoxifen dissolved in oil for inducible gene mutation studies, the objective of this study was to demonstrate that microvascular growth can be induced in the avascular mouse mesentery tissue. C57BL/6 mice were administered an IP injection for five consecutive days of: saline, sunflower oil, tamoxifen dissolved in sunflower oil, corn oil, or peanut oil. Twenty-one days post-injection, zero tissues from saline group contained branching microvascular networks. In contrast, all tissues from the three oils and tamoxifen groups contained vascular networks with arterioles, venules, and capillaries. Smooth muscle cells and pericytes were present in their expected locations and wrapping morphologies. Significant increases in vascularized tissue area and vascular density were observed when compared to saline group, but sunflower oil and tamoxifen group were not significantly different. Vascularized tissues also contained LYVE-1-positive and Prox1-positive lymphatic networks, indicating that lymphangiogenesis was stimulated. When comparing the different oils, vascularized tissue area and vascular density of sunflower oil were significantly higher than corn and peanut oils. These results provide novel evidence supporting that induction of microvascular network growth into the normally avascular mouse mesentery is possible.

T-cell Composition in Ileal and Colonic Creeping Fat - Separating Ileal from Colonic Crohn's Disease.

Creeping fat [CF] is a hyperplasia of adipose tissue adjacent to inflamed intestine in Crohn's disease [CD]. Data from genome-wide association studies [GWAS] distinguished Crohn's colitis from ileal CD and ulcerative colitis [UC]. This study analysed the T-cell compartments of ileal and colonic mesenteric fat and corresponding mucosa to provide cellular proof for the suggested GWAS classification. Samples were obtained from 34 CD or UC patients. Cells were analysed by immunohistochemistry and flow cytometry, and tissue cytokine release was assessed by cytometric bead array. Only ileal CF revealed the distinct adipocyte hyperplasia combined with dense T-cell infiltration and fibrosis; colonic fat from CD and UC patients lacked these findings. T-cell subpopulations differed between mesenteric fat in ileal CD, colonic CD and UC: ileal CF had nearly 10 times more T-cells than colonic fat. The proportions of regulatory and central memory T-cells were significantly higher in ileal CF compared with colonic fat in CD and UC. In all groups, the mucosal T-cell compartment was distinct from the mesenteric fat. Remarkably, correlation between disease activity and proportion of pro- and anti-inflammatory T-cell subpopulations was inverse, comparing ileal and colonic fat in CD. This first in-depth analysis of the T-cell compartment in ileal and colonic mesenteric adipose tissue in CD and UC identifies a unique T-cell niche in the ileal mesenteric fat tissue in CD. From a clinical point of view, our findings underscore the novel concept of colonic and ileal CD as distinct IBD entities.

Persistent Mesorectal Inflammatory Activity is Associated With Complications After Proctectomy in Crohn's Disease.

Rectal resection in inflammatory bowel disease [IBD] is frequently complicated by disturbed perineal wound healing. Close rectal dissection, where the mesorectum remains in situ, is hypothesized to reduce complications by minimizing dead space, compared to total mesorectal excision. The aim of this study was to analyse post-operative outcomes of both techniques. In addition, immune activity in mesorectal tissue was assessed. Perineal complications and healing were retrospectively assessed in a series of 74 IBD patients undergoing proctectomy using close rectal dissection or total mesorectal excision. The mesorectums of 15 patients were analysed by fluorescence-activated cell sorting, immunofluorescence and in situ hybridization. Based on the clinical and in vitro findings, a novel surgical approach for Crohn's disease patients with disturbed perineal healing after proctectomy was developed. In Crohn's disease, perineal complications were more frequent after close rectal dissection than after total mesorectal excision [59.5% vs 17.6%; p = 0.007] with lower healing rates [51.4% vs 88.2%; p = 0.014]. No differences were observed in ulcerative colitis. The mesorectal tissue in Crohn's disease contained enhanced numbers of tumour necrosis factor α-producing CD14+ macrophages, with less expression of the wound-healing marker CD206. Based on these findings, mesorectal excision with omentoplasty was performed in eight patients with perineal complications after close rectal dissection, resulting in complete perineal wound closure in six. Pro-inflammatory characteristics remained present in the mesorectum after close rectal dissection in these patients. In Crohn's disease, close rectal dissection resulted in more perineal complications, associated with a pro-inflammatory immune status of the mesorectal tissue. Excision of this pro-inflammatory mesenteric tissue resulted in improved perineal healing rates.

Glucocorticoids decrease the numbers and activation of mast cells by inducing the transactivation receptors of AGEs.

Glucocorticoids (GCs) are potent anti-allergic compounds that function, at least in part, by inhibiting signaling pathways in mast cells. We hypothesized that the GC-induced mastocytopenia and suppression of mast cell activation are mediated by the advanced glycation end products (AGEs)/receptors of AGEs (RAGEs) signaling axis. We evaluated the role of AGEs in GC-mediated mastocytopenia and impaired mast cell degranulation in male Wistar rats and Swiss-Webster mice subcutaneously injected with dexamethasone or prednisolone (0.1mg/kg) once a day for 21 consecutive days. The animals were treated with either the AGE inhibitor aminoguanidine (250mg/kg), the RAGE antagonist FPS-ZM1 (1mg/kg) or the galectin-3 antagonist GSC-100 (1mg/kg) daily for 18 days, starting 3 days following GC treatment. Aminoguanidine inhibited GC-induced mast cell apoptosis and restored mast cell numbers in the pleural cavity of GC-treated rats. Aminoguanidine also reversed the GC-induced reduction in histamine release triggered by allergens or compound 48/80 in vitro. GC treatment induced RAGE and galectin expression in mast cells, and blocking these agents by FPS-ZM1 or GSC-100 significantly reversed mast cell numbers in the peritoneal cavity and mesenteric tissue of GC-treated mice. In addition, the combination of GC and AGE-induced mast cell apoptosis in vitro was inhibited by both FPS-ZM1 and GSC-100. We concluded that the GC-induced mastocytopenia and suppression of mast cell stimulation are associated with the gene transactivation of RAGE and galectin-3.

Effect of red blood cell transfusion on the oxygenation of mesenteric tissue in premature infants

Objective: To investigate the effect of red blood cell transfusion on the oxygenation of mesenteric tissue in premature infants. Methods: In this prospective cohort study, preterm infants with gestational age <37 weeks who were treated with red blood cell transfusions were enrolled from June 2017 to March 2018 in Department of Neonatology, Children's Hospital of Fudan University. The infants were categorized into feeding intolerance group and feeding tolerance group according to the feeding intolerance standard. Near-infrared spectroscopy was applied to continuously monitor intestinal oxygen saturation from 2 h before red blood cell transfusion to 48 h after red blood cell transfusion. Intergroup differences of basic conditions were analyzed with t test, Mann-Whitney U test and χ(2) test. Mixed linear model was used to compare intragroup and intergroup differences in intestinal oxygen saturation over time. Results: A total of 73 cases with gestational age <37 weeks were enrolled, of whom 41 were males and 32 were females, with mean gestational age of (30±4)weeks and mean birth weight of (1 543±688)g; there were 33 cases in feeding intolerance group and 42 cases in feeding tolerance group. The average intestinal oxygen saturations at 2 h before blood transfusion, during blood transfusion, 2, 6, 12, 24, and 48 h after transfusion were 0.50±0.07, 0.52±0.07, 0.52±0.08, 0.51±0.08, 0.51±0.07, 0.51±0.08, and 0.51±0.07 respectively in feeding intolerance group and were 0.51±0.04, 0.55±0.04, 0.57±0.05, 0.57±0.04, 0.56±0.04, 0.56±0.04, and 0.56±0.05 respectively in feeding tolerance group. Compared with 2 h before transfusion, intestinal oxygen saturation were increased during transfusion in both group (feeding intolerance group t=4.992, P=0.000; feeding tolerance group t=9.615, P=0.000), however this effect lasted until 48 h after transfusion in feeding tolerance group (t=5.519, 12.409, 10.033, 9.133, 7.983, all P=0.000). Additionally, the increasement of intestinal oxygen saturation over time were lower in feeding intolerance group(F=8.876, P=0.000). Besides, the level of intestinal oxygen saturation was positively correlated with postmenstrual age (PMA)(F=4.863, P=0.031). In infants with PMA<30 weeks, particularly in feeding intolerance group, the level of intestinal oxygen saturation significantly decreased at 2 h after transfusion (t=23.063, P=0.002). Conclusions: Feeding status and PMA may play a role in development of transfusion-associated necrotizing enterocolitis. Red blood cell transfusion may increase the risk for mesenteric ischemia and is more likely to cause necrotizing enterocolitis in preterm infants with PMA <30 weeks as well as feeding intolerance. Clinical Trail: Children's Hospital of Fudan University, NCT02544100.

Mechanical characterisation of porcine non-intestinal colorectal tissues for innovation in surgical instrument design

This article presents an investigation into the mechanical properties of porcine mesocolon, small intestinal mesentery, fascia, and peritoneum tissues to generate a preliminary database of the mechanical characteristics of these tissues as surrogates for human tissue. No study has mechanically characterised porcine tissue correlates of the mesentery and associated structures. The samples were tested to determine the strength, stretch at failure, and stiffness of each tissue. The results indicated that porcine mesenteric and associated tissues visually resembled corresponding human tissues and had similar tactile characteristics, according to an expert colorectal surgeon. Stiffness values ranged from 0.088 MPa to 6.858 MPa across all tissues, with fascia being the weakest, and mesentery and peritoneum being the strongest. Failure stress values ranged from 0.336 MPa to 6.517 MPa, and failure stretch values ranged from 1.766 to 3.176, across all tissues. These mechanical data can serve as reference baseline data upon which future work can expand.

The role of adipose tissue in inflammatory bowel diseases.

The occurrence of creeping fat wrapping segments of inflamed gut represents a characteristic yet incompletely understood hallmark of Crohn's disease. Over the last decade, numerous studies have provided a limited understanding of this feature. Still, deciphering the detailed mechanisms and the pathophysiologic relevance of the interplay between creeping fat, barrier function and intestinal inflammation will be the aim of future studies. The last 18 months have substantially contributed to this field, starting with an elegant three-dimensional study revealing B cell aggregates around lymphatic vessels embedded in the mesenteric fat, thus bringing back the idea that Crohn's disease might represent a 'lymphatic disease'. Furthermore, studies on a cellular level elucidated the interplay of mesenteric adipocytes, immune cells and intestinal epithelial cells. Last, imaging studies provide evidence indicating that changes depicted by computed tomography within the mesenteric fat compartment rather than of the bowel wall are predictive for the presence of endoscopic lesions. This underlines the impact of mesenteric changes on Crohn's disease activity. The findings of the last 18 months further contribute to solving the puzzle that will ultimately reveal the role of the mesenteric fat tissue in the control of intestinal immunity and inflammation.

TLR9 regulates host defense via modulation of peritoneal B1 cell recruitment and functions during intra-abdominal sepsis.

Abstract Background Toll like receptor 9 (TLR9) is identified as anintracellular DNA receptor playing important roles in immunity. However, the mechanisms of how TLR9 regulates host defense are unclear. B1 cells are aninnate-like B cell population predominately residing in peritoneum and highly express TLR9. Therefore, we hypothesize that TLR9 may regulate host defense via modulation of peritoneal B1 pathobiology during sepsis. Method C57BL/6 (WT) mice and TLR9−/− mice were subjected to cecal ligation and puncture (CLP) with for 18 hours. Result Deletion of TLR9 increased survival as well as decreased bacterial load and systemic inflammation after CLP. Interestingly, peritoneal B1 cell numbers were significantly higher in TLR9−/− than WT mice, associated with significant increases of peritoneal CXCL13 level in TLR9−/− miceat baseline and after CLP. Strikingly, the expression level of CXCL13, a B cell-attracting chemokine, in the mesenteric adipo tissue was 50 fold higher inTLR9−/− than WT mice after CLP. Treatment with CXCL13 neutralizing antibody impaired bacterial clearance and decreased peritoneal B1 cell numbersin TLR9−/− mice compared to the IgG control after CLP, suggesting that TLR9 regulated B1 cell recruitment via CXCL13. Furthermore, deletion of TLR9 significantly increased peritoneal natural antibody IgM levels compared to WT at baseline and after CLP. Importantly, adoptive transfer of TLR9−/−B1 cells to WT mice improved bacterial clearance and increased peritoneal IgM levels compared to adoptive transfer of WT B1 cells after CLP. Conclusions These findings revealed an unrecognized role of TLR9 in modulating host defense via regulating B1 cell recruitment and IgM production during intra-abdominal sepsis.

Endothelial Cell Phenotypes are Maintained During Angiogenesis in Cultured Microvascular Networks

A challenge in tissue engineering biomimetic models for studying angiogenesis is building the physiological complexity of real microvascular networks. Our laboratory recently introduced the rat mesentery culture model as an ex vivo experimental platform for investigating multicellular dynamics involved in angiogenesis within intact microvascular networks. The objective of this study was to compare endothelial cell phenotypes along capillary sprouts in cultured ex vivo rat mesentery microvascular networks to in vivo endothelial cell phenotypes. For Day 3 (Ex Vivo) tissues, adult rat mesentery tissues were cultured for three days in media supplemented with 10% serum. For Day 3 (In Vivo) tissues, adult rats were anesthetized and the mesentery was exteriorized for twenty minutes to induce angiogenesis. Microvascular networks from Day 3 (Ex Vivo) and Day 3 (In Vivo) groups were angiogenic, characterized by an increase in vessel density, capillary sprouting, and identification of similar BrdU-positive endothelial cell distributions along sprouts. Endothelial cells in both groups extended pseudopodia at the distal edge of capillary sprouts and displayed similar endothelial cell UNC5b, VEGFR-2, and CD36 labeling patterns. The results from this study support the physiological relevance of the rat mesentery culture model and highlight its novelty as a biomimetic tool for angiogenesis research.

Production of omega-3 enriched tilapia through the dietary use of algae meal or fish oil: Improved nutrient value of fillet and offal.

The goal of this project was to increase the nutrient value of fillets, by-product muscle, and offal of aquacultured tilapia. A diet that includes seafood with a high omega-3 (n-3) fatty acid content, more specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are known to have numerous health benefits for consumers. Improved nutrient value of the offal may also attract new market opportunities for the aquaculture industry. Tilapia were cultured on different experimental feeds that contained various levels of n-3 fatty acids from either fish oil (FO) or algae meal (AM) that were used to replace corn oil. The experimental diets included a control (corn oil 6.3%), FO1%, FO3%, FO5%, AM1.75%, AM5.26%, and AM8.77%. All diets were formulated to be isocaloric, isonitrogenous, and isolipid. Three hundred and fifty tilapia with an initial mean weight of 158±2 g were cultured in a recirculating aquaculture system (seven diets replicated at the tank level, 14 tanks, 25 fish per tank). For all of the production performance data, no differences (P>0.05) were observed between the experimental groups which included survival (overall mean ± standard error, 99.4±0.3%), growth per week (45.4±1.0 g/wk), food conversion ratio (1.32±0.03), fillet yield (44.4±0.2%), hepatosomatic index (1.61±0.02), viscerosomatic index (2.86±0.06), and mesenteric fat index (0.97±0.04). Fillet and rib meat tissues were collected at weeks four and eight, and liver and mesenteric fat tissues were collected at week eight. Fatty acids were extracted, methylated and identified with gas chromatography–mass spectrometry. All tissues had improved fatty acid profiles (higher n-3, lower n-6, n-6:n-3) with increasing levels of FO and AM in the diet. For example, the best diet for significantly (P<0.05) improving the lipid profile in tilapia fillets at week eight was diet AM8.77%. In the fillet, total n-3 was increased (control versus AM8.77%) from 151.2±19.0 to 438.7±14.2 mg per 4 ounce (113 g) serving and n-6:n-3 ratio was improved from 5.19±0.76 to 1.29±0.03.

An Ex Vivo Platform for Studying Angiogenesis in Perfused Microvascular Networks

A challenge in tissue engineering biomimetic models for studying angiogenesis is building the physiological complexity of real microvascular networks. Utilizing an alternative top‐down approach, our laboratory recently introduced the rat mesentery culture model as an ex vivo experimental platform for investigating the multi‐cellular dynamics involved in angiogenesis within an intact microvascular network. However, a current limitation of the model is that microvessels are not perfused. The objective of this study was to demonstrate the feasibility of perfusing microvascular networks during the culture of rat mesentery tissue. Adult Wistar rat mesentery tissues were harvested along with a feeding second order arteriole and venule, and then transferred to a customized tissue chamber for perfusion. The arteriole was cannulated with a glass pipette (40 – 60 μm diameter) and secured in place with 7–0 suture. Injection with blue food dye through the cannulated arteriole identified the lumens of vessels across the hierarchy of intact microvascular networks and confirmed successful perfusion. Tissues with cannulated arterioles were cultured in the perfusion chamber up to three days with either minimum essential media (MEM) or MEM supplemented with 10% serum. Live/dead labeling confirmed that cannulated mesentery tissues remain viable after three days in culture. Additional labeling with BSI‐lectin identified endothelial cells along microvascular networks and confirmed the tissues were undergoing angiogenesis, characterized by increases in vascular density and capillary sprouting. These results demonstrate the ability to perfuse intact microvascular networks ex vivo in cultured mesentery tissues and supports the novelty of the rat mesentery culture model as a biomimetic tool for investigating angiogenesis.Support or Funding InformationNIH R01AG049821This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Induction of Microvascular Network Growth in the Mouse Mesentery

Ex Vivo biomimetic models have emerged as powerful experimental tools for basic science discovery and pre‐clinical drug testing. A challenge for microvascular research is recapitulating the complexity associated with intact networks in real tissue scenarios. To meet this challenge, our laboratory recently introduced the rat mesentery culture model, which enables the real‐time investigation of multicellular interactions during angiogenesis and lymphangiogenesis at the same time. The impact of this approach could be increased with the use of analogous transgenic mouse tissue. However, mouse mesentery is normally avascular raising the question: Can we induce microvascular growth into the mouse mesentery? Preliminary observations of mesenteric tissues harvested from mice treated with tamoxifen for conditional knockout studies suggests that vascularization in the mouse mesentery might be possible. The objective of this study was to test the hypothesis that tamoxifen treatment causes microvascular growth into avascular mouse mesenteric tissue. Female C57BL/6 mice were given a daily IP injection of 0.1 mL for 5 consecutive days containing the following experimental groups: Saline, Sunflower Seed Oil (Oil), and Tamoxifen (Tmx) dissolved in sunflower seed oil (10 mg/mL). Following 21 days post the last injection, mesenteric tissues were harvested and labeled with anti‐mouse platelet endothelial cell adhesion molecule (PECAM), neuron‐glial antigen 2 (NG2), and alpha‐smooth muscle actin (a‐SMA) antibodies to identify endothelial cells, pericytes, and smooth muscle cells, respectively. Zero tissues (0/8) from the Saline group contained a branching microvascular network. In contrast, all tissues from the Oil (8/8) and Tmx (8/8) groups contained networks with arterioles, venules, and capillaries. Smooth muscle cells and pericytes were present in their expected wrapping morphologies and locations along the hierarchy of the networks. In contrast to Saline tissues, Oil and Tmx treated tissues also contained branching LYVE‐positive lymphatic networks. The dramatic increase of vascularized tissue area and the vascularized tissue density were not significantly different between the Oil and Tmx groups (vascular area: Saline = 0.05 ± 0.05 %, Oil = 28.34 ± 8.61 %, Tmx = 35.56 ± 9.47 %; vascular density: Saline = 4.19 ± 4.19 #/mm2, Oil = 290.26 ± 32.00 #/mm2, Tmx = 275.61 ± 31.82 #/mm2; n = 8 tissues from 2 mice per group). The results of this study provide the first evidence that microvascular network growth in mouse mesenteric tissues can be induced and that sunflower seed oil is sufficient for the stimulation. More importantly, the results enable the use of mesentery tissue culture for the novel investigation of microvascular cell dynamics with transgenic mouse strains.Support or Funding InformationNIH R01AG049821This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.