Defects in the expression of colonic host defense factors associate with barrier dysfunction induced by a high-fat/high-cholesterol diet

The effect of Western diets in the gastrointestinal system is largely mediated by their ability to promote alterations in the immunity and physiology of the intestinal epithelium, and to affect the composition of the commensal microbiota. To investigate the response of the colonic epithelium to high-fat/high-cholesterol diets (HFHCDs), we evaluated the synthesis of host defense factors involved in the maintenance of the colonic homeostasis. C57BL/6 mice were fed an HFHCD for 3 weeks and their colons were evaluated for histopathology, gene expression, and microbiota composition. In addition, intestinal permeability and susceptibility to Citrobacter rodentium were also studied. HFHCD caused colonic hyperplasia, loss of goblet cells, thinning of the mucus layer, moderate changes in the composition of the intestinal microbiota, and an increase in intestinal permeability. Gene expression analyses revealed significant drops in the transcript levels of Muc1, Muc2, Agr2, Atoh1, Spdef, Ang4, Camp, Tff3, Dmbt1, Fcgbp, Saa3, and Retnlb. The goblet cell granules of HFHCD-fed mice were devoid of Relmβ and Tff3, indicating defective production of those two factors critical for intestinal epithelial defense and homeostasis. In correspondence with these defects, colonic bacteria were in close contact with, and invading the epithelium. Fecal shedding of C. rodentium showed an increased bacterial burden in HFHCD-fed animals accompanied by increased epithelial damage. Collectively, our results show that HFHCD perturbs the synthesis of colonic host defense factors, which associate with alterations in the commensal microbiota, the integrity of the intestinal barrier, and the host's susceptibility to enteric infections.

A259 HIGH-FAT/HIGH-CHOLESTEROL DIETS PREDISPOSE THE HOST TO EXACERBATED ENTERIC INFECTIONS

Background

High-fat/high-cholesterol diets are a well established risk factor for cardiovascular and metabolic diseases, given their propensity to trigger perturbations ranging from altering whole body lipid profile to the induction of intestinal dysbiosis. However much less is known about their effects on the host’s susceptibility to enteric infections.

Aims

To determine the effects of high-fat/high-cholesterol diets over the host’s susceptibility to enteric bacterial infections and identify the underlying molecular mechanisms.

Methods

C57BL/6 mice were given two different high-fat/high-cholesterol diets; HFHC (40% kcal fat, 1.25% cholesterol) or HFHCC (40% kcal fat, 1.25% cholesterol, 0.5% sodium cholate) and a control, normal diet (ND, 10% kcal fat, 0% cholesterol, 0% sodium cholate). After four weeks of administration, animals were euthanized and colonic tissue samples taken for histology, immunofluorescence, gene expression analyses, total protein lysates and microbiome sequencing (16S). A separated group of animals was gavaged with FITC-dextran to measure intestinal permeability. Mice fed with the diets for three weeks were infected with ~5x108 cfu of Citrobacter rodentium DBS100/StrpR by oral gavage, and kept on the corresponding diets after the infections. Bacterial shedding in the feces was followed for up to 30 days after infection.

Results

Administration of the HFHC and HFHCC diets caused an increase in intestinal permeability. Colonic sections stained with H&E and alcian blue evidenced a decreased in the number of mucin-filled goblet cells and a thinner mucus layer, suggesting a defect in the assembly and/or stability of the mucus layer. Expression analyses revealed a drop in the mRNA levels of Muc1 and Muc2, suggesting reduced mucin production. The concentration of IgA was slightly reduced in colon lysates and the transcript levels of the antimicrobial peptide genes Ang4, Leap2 and Cramp were also significantly reduced. Immunofluorescent microscopy showed that goblet cell granules of HFHC- and HFHCC-fed mice were devoid of Relmβ and Tff3, indicating defective production of those two factors critical for intestinal epithelial defense and homeostasis. Collectively, our results suggest that HFHC and HFHCC diets induce differentiation and functional defects in goblet cells. Fecal shedding of C. rodentium showed an increased bacterial burden in HFHC- and HFHCC-fed animals, indicating a more aggressive bacterial infection, accompanied by increased epithelial damage.

Conclusions

Consumption of high-fat/high cholesterol diets perturb the colonic homeostasis and alter intestinal defenses and the integrity of the intestinal barrier, predisposing the host to a higher susceptibility to enteric infections.

Funding Agencies

CIHRNSERC

A206 SUSCEPTIBILITY OF HNF4AΔIEC MICE TO SALMONELLA INFECTIONS

Background

Inflammatory bowel diseases (IBD) are a group of chronic disorders that affect more than 233 000 Canadians and for which there is not yet an effective treatment. In addition, IBD is a multifactorial disease depending on genetic, immune and environmental dysregulations. The gastrointestinal epithelium plays an important role as a barrier that protects against antigens and bacterial products that are in the lumen. It is well recognized that a defect in the integrity of the barrier and its functions may be involved in the development of these diseases. On the other hand, our laboratory has shown that the conditional deletion of HNF4alpha nuclear receptor (Hnf4a) in the intestinal epithelium of mice can lead to the development of chronic inflammation of the intestine. However, the impact of the loss of this transcriptional factor on the epithelial barrier is still controversial.

Aims

To evaluate the impact of Hnf4a deletion on the epithelial barrier during bacterial infections.

Methods

We used a tamoxifen-inducible Cre-loxP system to delete the Hnf4a gene in the intestinal epithelium of 2-month-old mice, that were then infected with an attenuated strain of Salmonella typhimurium (SB1003) during 4 days. S. typhimurium loads were determined in cecum and colon content, and in liver, spleen tissues by plating homogenates on LB agar supplemented with streptomycin. Also, histological examinations and gene expression of selected targets were assessed between mutant (Hnf4aΔIEC) and control mice.

Results

The tamoxifen-inducible Cre-loxP system was able to delete intestinal Hnf4a gene expression with almost 100% of efficacy. Analysis by qPCR showed that the infection caused significant changes on the response of different infection responsive components (Relmβ, Muc2 and IL-33) in mutant mice. In addition, morphological analyses revealed an increase in the infiltration of immune cells and the number of goblets cells, indicative of an increase in the susceptibility to Salmonella typhimurium (SB1003) infection of the mutant mice.

Conclusions

Altogether, our results suggest that Hnf4a could be involved or play an important role as a modulator of the intestinal epithelial barrier function during Salmonella typhimurium (SB1003) infection. Therefore, understanding the mechanisms involved in this process could allow the development of better therapies for IBD.

Funding Agencies

CIHR

Diversity of Dickeya Strains Collected from Pineapple Plants and Irrigation Water in Hawaii

Bacterial heart rot caused by a yet undetermined species of Dickeya was first observed in December 2003 in Oahu, HI, on a pineapple cultivar (Ananas comosus 'PRI 73-114') recently imported from Central America. Identical symptoms were later seen in the same plantation in fields that had been planted with propagules from the Philippines. Dickeya strains isolated from symptomatic plants and irrigation water collected over subsequent years were identified using bacteriological tests and partial 16S ribosomal DNA sequencing and characterized using repetitive sequence-based polymerase chain reaction (rep-PCR) with the BOXA1R primer (BOX-PCR), pathogenicity on pineapple leaves, and reactivity with two monoclonal antibodies (MAbs). Strains exhibited variability in pathogenicity and in reactivity with MAbs. BOX-PCR separated the plant-isolated Dickeya strains into seven haplotypes that were placed into four fingerprint groups (A to D). Strains from the A and B groups were isolated from the Central American stocks, whereas strains in the D group were identified from Philippine material. Strains from the C group were isolated from both planting materials. Most strains from water sources were placed into three haplotypes that loosely formed group E. BOX-PCR polymorphisms between the Dickeya strains isolated from foreign pineapple plants, a local collection of Dickeya strains, and strains from the plantation's water sources support the possibility that at least two separate introductions of genetically distinct strains occurred via imported planting stocks.

Effects of in utero exposure to D-004, a lipid extract from Roystonea regia fruits, in the male rat: a comparison with finasteride

D-004 is a lipid extract obtained from Cuban royal palm fruits, consisting of a mixture of free fatty acids, that prevents prostate hyperplasia induced with testosterone in rodents. This study investigated the possible alterations due to D-004 of androgen-dependent development after exposure in utero and compared them with those due to finasteride. Rats were randomized into five experimental groups: a control group, three groups treated with D-004 at 500, 750, or 1,000 mg/kg/day, respectively, and a group treated with finasteride (10 mg/kg/day). Male rats were treated 10 weeks before and during mating. Female rats were treated for 15 days prior mating, during mating, during pregnancy, and until lactation (day 21) except for those treated with finasteride, which were only administered the drug on gestational days 12-21. All male offspring were monitored individually until necropsy after postnatal day 90. The results of the present study indicate that D-004 induced no alterations in androgen-dependent development after the exposure in utero. Also, the current study demonstrated a permanent reduction in anogenital distance and retention of nipples in adult male rats exposed to finasteride during late gestation. Significant alterations induced by exposure to finasteride were mainly in tissues dependent on dihydrotestosterone during development.

Oral subchronic toxicity of a lipid extract from Roystonea regia fruits in mice

D-004 is a lipid extract of royal palm (Rosytonea regia) fruits that prevents prostate hyperplasia induced with testosterone in rodents. Previous studies have shown no D-004-related toxicity in rats, but no study in mice had been reported. D-004 (500, 1000, and 2000 mg/kg) was evaluated in a subchronic (eight weeks) study in NMRI mice. No evidences of treatment-related toxicity were detected. Thus, body-weight gain, clinical observations, food consumption, blood biochemical, hematology, organ-weight ratios, and histopathological findings were similar in control and treated groups. This study supports that D-004 orally administered up to 2000 mg/kg did not induce treatment-related toxicity.

Perinatal/postnatal study of D-003, a mixture of long-chain fatty acids, in rats

D-003 is a mixture of long-chain fatty acids isolated and purified from sugar cane wax with cholesterol-lowering and antiplatelet effects. In order to further characterize the developmental toxicity during the treatment period from late gestation up to weaning of the offspring, pregnant females received 0 (control), 500, and 1,000 mg/kg/day D-003 daily by oral gavage beginning at day 15 of pregnancy and through gestation until day 21 postpartum. Maternal clinical signs, body weight, and food intake were measured at regular intervals during gestation and lactation. Live pups were weighed, sexed, and examined for developmental signs. One female and male of each litter were randomly selected to evaluate the reproductive potential. There were no spontaneous or dose-related maternal deaths during the course of this study. The general health and behavioral condition of offspring was good in all groups. No significant differences among groups were found in comparisons of litter size, survival through the weaning period, sex ratio, and male and female weights. This peri- and postnatal study conducted with D-003 in rats indicated that treatment of the dam during late gestation and lactation did not show adversely effects on reproductive performance or fetal development over two generations.

Deaggregation is an integral component of the response of platelets to ADP in vitro: kinetic studies of literature and original data

Adenosine diphosphate (ADP) is recognized as an important mediator of platelet aggregation. Transient aggregation at low (< or =1 microM), and sustained aggregation at higher ADP concentrations are consistently observed. Dissociation of platelet aggregates has been described and may explain the reversible component of the aggregation response. We hypothesized that the net aggregation response to ADP in vitro results from the concurrent activation of two opposing processes, aggregation and deaggregation. Different purinergic receptor subtypes may mediate these effects. To test this hypothesis and its generalizability, we performed a kinetic analysis of representative published ADP-induced aggregation responses supplemented with original data from our laboratory. A four-compartment kinetic model was used to estimate k(3), a rate constant of deaggregation. Two model-independent parameters, the magnitude of the aggregation response (DeltaOD) and the time to reach maximal aggregation (t(peak)) were also assessed. Greater sustained aggregation at higher ADP concentrations was consistently associated with increased DeltaOD and t(peak) but decreased k(3) values. These relationships were independent of type of platelet preparation or experimental conditions and not due to ADP receptor desensitization. Conversely, blockade of the P2Y(12) receptor subtype (ticlopidine, clopidogrel or 2-MeS-AMP) decreased DeltaOD and t(peak) but increased k(3) values. This supports the presence of active deaggregation which is decelerated by activation of the P2Y(12) receptor subtype.

Lasers in dermatology: a review

The revolution in laser technology has had a significant impact on medicine in general and dermatology in particular and has piqued the interest of physicians, the lay public, and the media. Advances in laser therapy have dramatically improved the clinicians' ability to treat cosmetic and noncosmetic skin lesions safely and effectively. The number and variety of skin problems amenable to laser treatment continues to grow. We will provide a review of the major cosmetic and therapeutic applications of laser therapy.

[Effect of diltiazem on cold-induced left ventricular dysfunction in patients with systemic sclerosis]

Patients with systemic sclerosis (SS) have cardiac dysfunction induced by cold exposure. We and others have demonstrated this finding after corporal chilling, suggesting a "coronary Raynaud phenomenon" mediated by intermittent vascular spasm. In this study we evaluated the effect of diltiazem (DTZ) in cardiac dysfunction induced by cold test in patients with SS without clinical evidence of heart disease. Twelve patients with SS were studied. One patient was excluded because he did not fulfill the prescribed treatment. Eleven patients (age of 49.9 +/- 3.8 years and illness duration of 9.3 +/- 4.8 years) were included. Gated equilibrium radionuclide ventriculography was recorded after red blood cells were labeled in vivo using an intravenous injection of stannous pirophosphate followed by 20 mc of 99 Tc (gamma camera with electrocardiographic R wave gating was used). Left ventricular injection fraction (LVEF) was calculated using computer analysis and wall motion abnormalities by visual interpretation. Patients were cooled using a thermic blanket set at 5 degrees centigrade. They were evaluated before and after a period of cooling. After corporal chilling LVEF decreased more than 10% in all of them. DTZ 270 mg a day was administered to the same patients during 48 hs. Basal and cold LVEF were repeated in all patients. The results with and without DTZ were compared by Student's t Test. The basal LVEF with and without DTZ was not different (64.8 +/- 2.6 and 63.1 +/- 1.8). After corporal chilling LVEF decreased (64.8 +/- 2.6 to 54.8 +/- 2.5 p < 0.00001) and reversible abnormalities in wall motion were noticed in patients without DTZ. When they received DTZ neither difference in LVEF (63.1 +/- 1.8 to 62.1 +/- 2.4) nor wall motion abnormalities were observed. We compared the LVEF after chilling (62.1 +/- 2.4 and 54.8 +/- 2.5) and we found an important difference with the use of DTZ (p < 0.005). It can be concluded that in patients with SS and no overt heart disease, DTZ prevents the early cardiac dysfunction induced by cold test. Probably this drug blunts the coronary spasm induced by cold test in this group of patients.

Effectiveness of different endodontic files for preparing curved root canals: a scanning electron microscopic study

In this study, the effect of using four endodontic files from different manufacturers on the final shape of 80 prepared curved root canals of extracted single-rooted teeth were comparatively analyzed with scanning electron microscopy. The instruments tested were Tri-files, Flex-R files, Flexofiles and conventional K-type files. All files were used with in and out linear movements with a circumferential motion starting with a size 15 file. Final preparation of the apical thirds was performed with a size 30 file. Shaping effectiveness of the tested files was qualitatively evaluated in terms of respect for conservation of the apical constriction and the presence or absence of ledging, specially in the apical third of the root canals. A well-centered and tapered preparation without apical transportation or ledging was detected when Tri-file or Flex-R files were used. Conversely, the use of Flexofile or conventional K-type files resulted in frequent alteration of the initial pattern of the root canals, showing an hour-glass preparation with alteration of the apical constriction and ledge formations.

Avoiding paraplegia during anterior spinal surgery. The role of somatosensory evoked potential monitoring with temporary occlusion of segmental spinal arteries

Three patients paraplegic following anterior spinal fusion for congenital kyphoscoliosis were noted to have complete somatosensory evoked potential signal loss shortly after segmental arterial ligations at the apex of their respective kyphosis. This has prompted us to use temporary segmental arterial occlusion with somatosensory evoked potential monitoring prior to ligation during anterior spinal fusion. As a result, we have noted seven additional cases, out of a total of 44 cases monitored in this fashion, in which complete loss of somatosensory evoked potential signals, reversible by release of vascular clips, has occurred. For each of these additional cases the critical segmental arteries were identified and were not ligated, usually resulting in some modifications in the planned surgical procedure, and the patients remained neurologically intact. We recommend temporary segmental arterial occlusion with somatosensory evoked potential monitoring during thoracolumbar anterior spinal fusion to potentially avert ischemic neurologic injury. Based on published data and the experience described herein, this technique should be especially important in anterior spinal fusion for congenital kyphoscoliosis.

Congenital pseudarthrosis of the clavicle: a review of the literature and surgical results of six cases

This article is a retrospective review of six symptomatic patients who, when treated surgically, all healed with excision of pseudarthrosis, bone grafting, and plating. We discuss congenital pseudarthrosis of the clavicle with emphasis on etiologies, clinical presentation, differential diagnosis, and method of treatment. Our patients' chief complaints were cosmesis, pain, or shoulder deformity.

Results of 21 Wagner limb lengthenings in 20 patients

Roentgenograms and charts were reviewed on 20 patients (average age: 13.2 years) who had 21 Wagner limb lengthenings since 1975. Lengthenings included 15 femora (six acquired, eight congenital, and one fibrous dysplasia), four tibiae, and two humeri (one acquired and one congenital). Average femoral lengthening was 6.6 cm; tibial, 5.9 cm; and humeral, 9.7 cm. Lengthening of femora with congenital shortening (6.5 cm) was nearly the same as femora with acquired shortening (6.8 cm), and 85% of all lengthenings were greater than 5 cm. Humeri were lengthened more than 50%. Seventy-two percent of patients were in the 50th percentile or less of stature; 61% were in the 15th percentile or less of stature. Seventy-five percent had complications, with 65% having more than one major complication: pin tract and superficial infections in 40%; deep infections in 20%. All infections were in femoral lengthenings. Nonunion occurred in two patients (10%), and fracture after plate removal in two patients (10%). Five patients (25%) had nerve palsies, and four of these resolved without treatment. Malunion rate was 20%. Five patients developed joint contractures. Complications did not correlate with amount of lengthening but congenital deformities had a higher incidence of complication. Eleven patients required 19 additional procedures necessitated by the lengthening procedure. Wagner leg lengthening is generally recommended when amputation is only other surgical alternative and a full, complete informed consent is given to the parents and patient.