Reduced Villus Height Research Articles

Transgenic mice that overexpress the human trefoil peptide pS2 have an increased resistance to intestinal damage.

pS2 is a member of the trefoil peptide family, all of which are overexpressed at sites of gastrointestinal injury. We hypothesized that they are important in stimulating mucosal repair. To test this idea, we have produced a transgenic mice strain that expresses human pS2 (hpS2) specifically within the jejunum and examined the effect of this overexpression on proliferation and susceptibility to indomethacin-induced damage. A transgenic mouse was produced by microinjecting fertilized oocytes with a 1.7-kb construct consisting of rat intestinal fatty acid binding protein promoter (positions -1178 to +28) linked to full-length (490 bp) hpS2 cDNA. Screening for positive animals was by Southern blot analysis. Distribution of hpS2 expression was determined by using Northern and Western blot analyses and immunohistochemical staining. Proliferation of the intestinal mucosa was determined by assessing the crypt cell production rate. Differences in susceptibility to intestinal damage were analyzed in animals that had received indomethacin (85 mg/kg s.c.) 0-30 h previously. Expression of hpS2 was limited to the enterocytes of the villi within the jejunum. In the nondamaged intestine, villus height and crypt cell production rate were similar in transgenic and negative (control) litter mates. However, there was a marked difference in the amount of damage caused by indomethacin in control and transgenic animals in the jejunum (30% reduction in villus height in controls vs. 12% reduction in transgenic animals, P < 0.01) but the damage sustained in the non-hpS2-expressing ileal region was similar in control and transgenic animals. These studies support the hypothesis that trefoil peptides are important in stimulating gastrointestinal repair.

Effects of dietary soybean and cowpea on gut morphology and faecal composition in creep and noncreep-fed pigs.

The effects of creep feeding and different levels of soybean meal (SBM) and cowpea meal on the intestinal morphology and faecal characteristics were investigated in weaners. Prior to the feeding trial, one group of piglets was creep-fed and the other noncreep-fed. The two groups of piglets were weaned at 28 days and randomly assigned to four different diets whose main sources of protein were: T1-skimmed milk powder (control); T2-31 % soybean meal; t(3)-15% soybean meal and 12 % skimmed milk powder; and T(4)-100% raw cowpea meal. Live weight gain was highest in the T1 group, and least in the T(4) group. At weaning only the noncreep-fed weaners showed villus atrophy and crypt hyperplasia, but at 7 days postweaning these changes were evident in all groups except the control and were more severe in the noncreep (T2,T3) and cowpea-fed groups. At 21 days postweaning, only noncreep cowpea-fed pigs showed a reduced villus height when compared to the T1 group. A mild diarrhoea was generally observed in all noncreep-fed weaners but its onset was more rapid (P < 0.01) and the duration longer (P < 0.05) in the T2 and T4 pigs than in T3 and T1 groups. A lower faecal pH was observed in weaners that had diarrhoea when compared with a pH of 7.1 in pigs with normal moisture. The glucose content of the faeces was found to be significantly higher (P<0.05) in the T2 and T4 groups. The observations of enteropathology and low growth performance in the T4 group suggest that feeding raw cowpea to weaners is capable of inducing considerable antigenicity in the intestinal mucosa, causing damage and a consequent decrease in productivity. However, the introduction of creepfeeding before weaning appears to have some ameliorative effects.

Small intestinal injury in a neonatal rat model of giardiasis is strain dependent

Background & Aims : The factors that determine the severity of giardiasis are poorly understood. Host factors are important, but parasite virulence may also play a role. The aim of this study was to compare the apparent virulence of three genotypically different Giardia isolates (P01, VNB3, and WB). Methods : Infection rates, parasite loads, structural damage, disaccharidase activity, and water and electrolyte absorption were observed at 10 days after inoculation in a neonatal rat model of infection. Results : DNA fingerprinting showed differences between isolates studied. The infective rate varied between 67% and 100%. There were no differences in intestinal parasite load. Infection with strains P01 and WB, but not with VNB3, was associated with a reduction in villus height. There was precocious expression of sucrase at 10 days after inoculation in all infected groups. Water absorption of a plasma electrolyte solution was decreased in VNB3-infected animals when compared with P01- and WB-infected animals and controls. Water absorption and lactose hydrolysis were impaired during perfusion with a lactose-containing solution in all infected groups. Conclusions : Three genotypically different Giardia isolates that infect neonatal rats with the same trophozoite load differ in their ability to cause functional mucosal damage. Infection with Giardia lamblia induced precocious expression of sucrase activity and impaired mucosal absorption

Novel delivery system for inducing quiescence in intestinal stem cells in rats by transforming growth factor β1

Background/Aims: Intestinal mucosa, a tissue in a dynamic state of rapid cellular proliferation, is often adversely affected by cytotoxic drugs. The purpose of this study was to develop an oral delivery system targeting transforming growth factor (TGF) β1 locally and analyze its effects on the epithelial stem cells of gastrointestinal mucosa. Methods: Rats were treated with recombinant TGF-β1 in alginate beads perorally or with recombinant TGF-β1 in phosphate-buffered saline perorally or intraperitoneally. Control animals received phosphate-buffered saline only. The size of the villi was measured. Proliferating and mitotic indices were determined by quantifying immunohistochemical staining for proliferating cell nuclear antigen. Results: Alginate beads released no TGF-β1 in acid. However, in pH 7.4, TGF-β1 was released in an active form. Histomorphometrical analysis showed a marked reduction in villus height (50%–70%) in the intestinal mucosa of animals treated perorally with recombinant TGF-β1 in alginate beads. Also, the proliferating and mitotic indices were significantly reduced (P < 0.01) in these animals as compared with controls and other routes of administration. Conclusions: This study shows that recombinant TGF-β1 administered using a novel oral delivery system induces stem cell quiescence in the intestinal mucosa of the rat.

Sepsis in rats stimulates cellular proliferation in the mucosa of the small intestine

Background/Aims: Increased protein synthesis in intestinal mucosa during sepsis may reflect increased cell turnover. The influence of sepsis and endotoxemia on cellular proliferation in the mucosa of the small intestine was studied. Methods: Sepsis was induced in rats by cecal ligation and puncture. Control rats were sham-operated. Other rats were treated with endotoxin (total dose, 2 mg/kg), human recombinant tumor necrosis factor α, or human recombinant interleukin 1α at a dose of 100 μ/kg each. Villus height and crypt depth in the jejunum were measured as the number of cells along the side of the villus and crypt, respectively. Cellular proliferation was assessed by measuring the rate of [3H]thymidine incorporation into DMA of the jejunal mucosa and performing autoradiographic studies after intravenous administration of [3H]thymidine. Results: Sepsis resulted in reduced villus height, increased crypt depth, and increased incorporation of [3H]thymidine into DNA in the jejunal mucosa. Autoradiography after administration of [3H]thymidine showed labeled cells almost exclusively in the crypts; the number of labeled cells per crypt was higher in septic than in control rats. Administration of endotoxin or recombinant interleukin 1α, but not recombinant tumor necrosis factor α, stimulated the incorporation of [3H]-thymidine into DNA in the jejunal mucosa. Conclusions: Sepsis and endotoxemia stimulate cellular proliferation in the mucosa of the small intestine. This response to sepsis and endotoxemia may be partly mediated by interleukin 1.

Malabsorption of vitamin A in preruminating calves infected with Cryptosporidium parvum

SUMMARY Serum retinol, retinyl palmitate, and total vitamin A concentrations, and jejunoileal morphology were examined in neonatal calves infected with Cryptosporidium parvum. Group-1 calves served as noninfected controls and, after an adjustment period, were given 50 ml of saline solution iv every 12 hours for 6 days. Group-2 calves were inoculated with 107 C parvum oocysts and, after the onset of diarrhea, were given 50 ml of saline solution iv every 12 hours for 6 days. Group-3 calves were inoculated with 107 C parvum oocysts and, after the onset of diarrhea, were treated with difluoromethylornithine (dfmo, 200 mg/kg of body weight iv, q 12 h) for 6 days. Group-4 calves were naturally infected with C parvum. Jejunoileal biopsy specimens were excised from calves of groups 1-3 at 3 and again at 15 to 16 days of age. During the course of diarrhea and 3 days after saline or dfmo administration, water-miscible retinyl palmitate was administered orally (2,750 μg/kg) to each calf in each group. Cryptosporidium parvum infection was associated with significant (P ≤ 0.05) reduction in postadministration serum retinol, retinyl palmitate, and total vitamin A concentrations in calves of groups 2, 3, and 4. Cryptosporidium parvum infection caused significant (P ≤ 0.05) reduction in villus height. Decreased villus height, villus blunting and fusion, and attenuation of the intestinal mucosa were associated with reduced absorption of vitamin A, as indicated by lower peak postadministration retinyl palmitate concentration in C parvum-infected calves. Intravenous administration of dfmo to group-3 calves did not improve retinol absorption. Vitamin A should be provided parenterally to young calves with enteric cryptosporidiosis in an attempt to avoid depletion of concurrent low liver vitamin A reserves.

Subclinical characteristics of the wasting pig syndrome

The plasma concentrations of cortisol and corticosteroid-binding globulin and the adrenal synthesis capacity of cortisol were analysed in 10-week-old healthy and age-matched wasting or unthrifty pigs. Crypt cell multiplication, villus height and intestinal mucosal alkaline phosphatase (ALP) activity were also investigated. Furthermore, the effect of amperozide, a psychotropic drug with specific effects on emotional behaviour, was analysed for its effect on plasma ALP activity and villus height. Although the wasting pigs exhibited an increased cortisol synthesis capacity, there was a decreased plasma concentration of cortisol in these pigs. Furthermore, the plasma cortisol binding capacity was found to be significantly lowered in wasting pigs. There was also a reduced crypt cell proliferation, a reduced villus height and a decreased ALP activity in the ileal mucosa. Treatment with amperozide resulted in a normalisation of plasma ALP activity in unthrifty pigs, indicating a stimulation of body growth. The results indicate that the growth depression of wasting pigs is most probably a chronic stress syndrome caused by the inability of these animals to cope with the events following weaning and mixing.

Physiological relationships between microbiological status and dietary copper levels in the pig

Ten germ-free pigs and 10 conventionally reared pigs were fed one of two nutritionally balanced diets containing either 16 ppm Cu (basal) or 283 ppm Cu (high-Cu) to evaluate the physiological relationships between Cu and microbiological environment. Germ-free pigs tended to have higher ADG and average daily feed intake (ADFI) than conventionally reared pigs. Feeding the high-Cu diet tended to reduce ADG and ADFI in germ-free pigs but it increased ADG and ADFI in conventionally reared pigs. Hemoglobin and hematocrit were higher in germ-free pigs than in conventionally reared pigs (P less than .001), and hematocrit (P less than .01) and erythrocyte count (P less than .06) were reduced by feeding the high-Cu diet. Germ-free pigs had lower total leukocyte count (P less than .01) and the relative percentages of differentiated leukocytes were altered compared with conventionally reared pigs. Feeding the high-Cu diet increased the percentage of band neutrophils and monocytes in germ-free pigs but reduced the percentage of these cells in conventionally reared pigs (P less than .04). Germ-free pigs had higher concentrations of Cu and Zn in liver and plasma (P less than .001) and greater plasma ceruloplasmin oxidase activity (P less than .001) than conventionally reared pigs did. The high-Cu diet increased liver Cu and Zn (P less than .001) and plasma Cu (P less than .001) and reduced liver and plasma Fe (P less than .05). Organ weights (g/kg BW) differed between germ-free and conventionally reared pigs, and feeding the high-Cu diet reduced thymus weights (P less than .002). Intestinal weight and thickness were reduced in germ-free pigs, and feeding the high-Cu diet generally reduced villus height and width and crypt depth in germ-free pigs, whereas it increased these measurements in conventionally reared pigs.

Morphologic Changes in the Small Intestine after Chronic Alcohol Consumption

The morphology of the small-intestinal mucosa was studied in 11 alcoholic patients admitted to hospital for detoxification. A first biopsy specimen from the small intestine was taken as soon as possible after admission and a second specimen after about 6 weeks of abstinence. The specimens were studied in the light microscope, in the scanning electron microscope, and by immunohistochemistry. Morphometrically, a slight reduction in villus height in relation to crypt depth was observed. One patient had a subtotal villus atrophy. After abstinence the villus height was increased in five of the six patients who accepted a second biopsy. No obvious changes were seen in the frequency and appearance of peptidergic nerves or endocrine cells. Ultrastructurally, pronounced alterations were seen in the surface ultrastructure of the enterocytes. In two specimens bacterial adhesion to the mucosal surface was also found. The ultrastructural changes were unaltered after abstinence. In serum the concentrations of zinc were reduced, and the levels of copper were elevated compared with a group of teetotallers. A recently developed marker of high alcohol consumption, carbohydrate-deficient transferrin, was as good an indicator as the other conventional biochemical markers.

Effect of various fat sources on starter pig gut morphology and nutrient digestibility (1989)

One digestion trial utilizing 24 weanling pigs was conducted to compare the effect of various fat sources on gut morphology and ileal nutrient digestibility. Diets had either no added oil (control) or were supplemented with 10% either soybean oil, coconut oil or a combination of soybean oil and coconut oil (1:1 ratio). Pigs were sacrificed on 29 d of age, and ileal digesta were collected. Villus height and crypt depth were measured at the midpoint of the small intestine. Results indicate that pigs fed the combination of soybean oil and coconut oil had longer villus height and slightly higher ileal digestibility of medium chain fatty acids compared to the pigs fed either soybean oil or coconut oil alone. The reduction of villus height caused by feeding soybean oil or coconut oil alone may decrease the absorptive area and could result in inadequate transport of nutrient at the villus surface. The net result is a decreased nutrient digestibility.; Swine Day, Manhattan, KS, November 16, 1989

Relationship between distention and absorption in rat intestine: I. Effect of luminal volume on the morphology of the absorbing surface

Previous studies in vivo have suggested that distention of the intestinal lumen may enhance intestinal absorption by augmenting absorptive surface area. The precise anatomic mechanism for this increase in surface area, however, has not been explored in detail. We developed methods for rapidly freezing and fixing intestinal segments in situ in the nondistended or distended state. Distention led to a reduction in villus height (309.2 ± 9.9 to 230.7 ± 11.8 μm) and a marked increase in the width of intervillus space in both the transverse (50.4 ± 4.8 to 298.0 ± 24.8 μm) and longitudinal (15.2 ± 3.4 to 76.0 ± 10.6 μm) dimensions. There was, however, no absolute change in total mucosal surface area. The changes in morphology occurred instantaneously, were entirely reversible, and were demonstrated at pressures that occur spontaneously in the mammalian intestine. These studies demonstrate that luminal distention results in marked alterations in intestinal histology that promote increased access of luminal contents to intervillus transport sites in the intestine in vivo. The resulting alterations could lead to an increase in functional rather than absolute absorptive surface area.

Repair of rabbit duodenal mucosa after acid injury in vivo and in vitro

Epithelial repair after luminal acid exposure was studied in the rabbit duodenum in vivo and in vitro. Hydrochloric acid (200 mM, 30 min in vivo; 10 mM, 10 min in vitro) caused a uniform damage of the mucosa confined to the villi. After demarcation and detachment of the necrotic tissue the defect was bridged by the remaining viable epithelial cells, resulting in a reduction of villus height. This process of mucosal repair proceeded continuously, so that 9 h after acid damage only 33% of villi in the proximal duodenum and 41% in the distal duodenum remained not fully restored, at both luminal pH 7 and luminal pH 3. The difference is due to the higher acid susceptibility of the distal duodenum. In vitro, most of the mucosal surface was reconstituted 5 h after acid injury, at both luminal pH 7.4 and luminal pH 3. The potential difference declined and reversed after mucosal damage; restitution to original values was only observed at luminal pH 7 in vivo and luminal pH 7.4 in vitro.

Absorptive capacity of the transplanted small bowel.

Small bowel transplantation (SBT) has been carried out in man in several cases without success, because immunologic problems were unsolved. In experimental SBT a 'two step' model was developed, which enables long term observation of immunologic phenomena. In this model the graft is in a heterotopic position to the recipient's own small bowel. After 35 days the recipient's own bowel is removed and replaced by the graft, now in orthotopic position and again in contact with luminal chymus. To investigate functional and morphological changes, which result from the procedure, the resorption of glucose and water was measured in syngeneic transplanted rats by an in vivo recirculation system and the mucosa was evaluated three dimensionally. The graft mucosa showed a significant reduction in villus height, crypt length and villus surface and a corresponding decrease in glucose and water absorption during heterotopic position. If the graft came into the orthotopic position, the mucosa did regenerate which was expressed by the significant longer crypts of the graft compared with those of the controls, although the graft's villus height and surface are still smaller. Glucose and water absorption increased and were higher in orthotopic transplanted animals, when absorption was expressed per unit intestinal length. The results indicate that in the 'two step' model of SBT the absorption of water and glucose is influenced to such an extent, that recovery is possible after three weeks, thus enabling orthotopic SBT. This almost complete recovery of the mucosa is further evidence of the regeneratory capacity of the small bowel, which enables clinical small bowel transplantation.

Water and electrolyte absorption in ileal segments surgically transposed to the urinary bladder in the cat

Net transport of water and electrolytes was studied in ileal segments which had been exposed to urine during three months in seven cats. During surgery, a 5 cm long ileal segment was interposed between the ureters and the urinary bladder. At the same time a control segment (5 cm) was indicated with silver clips. After three months, the net transport of water and electrolytes was studied using a continuous perfusion technique with an isotonic and with a hypertonic, urine-like perfusate. Microscopic examination of the mucosa showed a significant reduction of villus height in the transposed segments compared to the controls (p < 0.05). With the isotonic perfusate there was a net absorption of water in the control segments, and a net secretion in the transposed segments, the difference being statistically significant (p < 0.05). When the hypertonic perfusate was used, a net secretion occurred in both control and transposed segments. Net transport of electrolytes (Na+. K+, CI-) was in the same direction as wat...

Contributions of ischemia and reperfusion to mucosal lesion formation.

Two theories have been proposed to account for the mucosal injury associated with intestinal ischemia, hypoxia-countercurrent exchange, and oxygen free radicals. The countercurrent mechanism suggests that mucosal injury should occur predominately during the ischemic period, whereas the oxygen free radical hypothesis predicts that the majority of mucosal injury results from reperfusion of ischemic tissue. Histological specimens obtained during the ischemic period and following reperfusion allowed a systematic evaluation of the time course of development of mucosal lesions in a regional ischemia model. Reperfusion after 3 h of regional hypotension reduced mean mucosal thickness from 1,022.2 +/- 6.3 to 503.6 +/- 10.0 microns. The decrease in mucosal thickness was largely due to a reduction in villus height, inasmuch as the reduction in crypt depth was statistically insignificant. A significantly smaller change in mucosal thickness was observed when the bowel was subjected to 3 h ischemia without reperfusion. The mucosal injury produced by 3 h ischemia and 1 h reperfusion was more severe than that produced by 4 h ischemia without reperfusion. The results of this study suggest that most of the tissue damage produced by the widely employed regional hypotension model occurs at the time of reperfusion.

Alterations in piglet small intestinal structure at weaning

The small intestinal mucosa of 112 piglets aged between 21 and 32 days was examined to identify the effects on its structure of weaning and of consumption of creep food. In unweaned control pigs a gradual increase in crypt depth occurred with age, while villus height altered little. In contrast, weaned pigs showed a highly significant increase in crypt depth and an increase in the complexity of villus morphology with a dramatic reduction in villus height. Crypts elongated most in the distal small intestine, while the loss of villus height was greatest proximally. No inflammatory reaction was seen and the alterations were not influenced by consumption of creep food before weaning. This failed to support the hypothesis that hypersensitivity to dietary antigens is involved in the aetiology of such intestinal changes. The reduction in small intestinal absorptive area and the appearance of a less mature enterocyte population help to explain the increased susceptibility of the pig to diarrhoea and growth checks in the post-weaning period.

Water and electrolyte absorption in ileal segments surgically transposed to the urinary bladder in the cat.

Net transport of water and electrolytes was studied in ileal segments which had been exposed to urine during three months in seven cats. During surgery, a 5 cm long ileal segment was interposed between the ureters and the urinary bladder. At the same time a control segment (5 cm) was indicated with silver clips. After three months, the net transport of water and electrolytes was studied using a continuous perfusion technique with an isotonic and with a hypertonic, urine-like perfusate. Microscopic examination of the mucosa showed a significant reduction of villus height in the transposed segments compared to the controls (p less than 0.05). With the isotonic perfusate there was a net absorption of water in the control segments, and a net secretion in the transposed segments, the difference being statistically significant (p less than 0.05). When the hypertonic perfusate was used, a net secretion occurred in both control and transposed segments. Net transport of electrolytes (Na+, K+, Cl-) was in the same direction as water transport in both control and transposed segments. The results indicate that there does not seem to be any risk of water or electrolyte reabsorption by intestinal mucosa which has been exposed to urine.

THE DEVELOPMENT OF THE LATE-TERM OVINE FETAL SMALL INTESTINE AND THE EFFECT OF ADRENALECTOMY

In the fetal sheep small intestine, enterocytes divide in the crypts before migrating up the villus. Adrenalectomy results in reduced villus height, migration rate and altered cytology. Key words: Sheep, intestine, fetus, normal development, adrenalectomy

Increased mucosal damage during parasite infection in mice fed an elemental diet.

We have examined the effects of parasite infection on the mucosal architecture of mice maintained on an elemental diet (Vivonex). Techniques used were conventional histology, micro-dissection and measurement of individual villi and crypts, and measurement of crypt cell proliferation rate by a metaphase accumulation technique. In normal, non-parasitised mice the elemental diet caused no change in villus height, crypt depth, or crypt cell proliferation. Likewise, the only effects of chronic protozoal infection or Nippostrongylus brasiliensis infection on the intestine of mice fed a normal diet have been a slight crypt hypertrophy and an increase in crypt cell proliferation rate without villous atrophy. However, the combination of elemental diet and parasite infection resulted in increased mucosal damage when compared with infected mice on a normal diet. Elemental diet mice infected with the nematode Nippostrongylus brasiliensis had significantly reduced villus height and correspondingly raised crypt length and metaphase accumulation rate. Elemental diet mice infected with the protozoan Giardia muris did not have villous atrophy but there was a significant increase in crypt length and metaphase accumulation when compared with infected normal diet mice. These experiments show that in two animal models of enteric infection, elemental diet has altered the host parasite relationship to the detriment of the host.

Small intestinal epithelial cell kinetics and protozoal infection in mice

The effects of chronic protozoal infection on small intestinal architecture have been examined in mice, infected with Giardia muris and Hexamita muris. Techniques used were conventional histology, quantitation of intraepithelial lymphocytes, microdissection and measurement of individual villi and crypts, and epithelial cell kinetic studies. The histology of small intestine from infected mice appeared normal apart from the intraepithelial lymphocyte numbers. Mean intraepithelial lymphocyte counts in two groups of uninfected mice were 11.6 and 13.6 per 100 epithelial cells, and in two groups of infected mice were 17.6 and 21.8. Dynamic studies showed that protozoal infection doubled the cell production per crypt per hour from mean values of 6.2, 7.3, and 8.2 in three groups of uninfected animals, to 11.8, 13.4, and 17.1 in groups of chronically infected mice. Cell production per villus was also influenced by protozoal infection, with values of 93, 99, and 101 cells per hr in groups of uninfected animals whereas in infected mice the values were 155, 162, and 180 cells per hr. Although there was no reduction in villus height in the infected animals, radioautography using [3H]thymidine confirmed that the enterocytes moved more rapidly up the sides of the villi than was the case for uninfected mice.