Effects of dietary lipids on recovery from mucosal injury

Induced oral mucositis in Wistar rats treated with different drugs: Preventive potential in cytokine production

The aim of the present study was to investigate the preventive potential of pentoxifylline, atorvastatin and trans-caryophyllene in oral mucositis through histopathological analysis of wounds in the oral mucosa of Wistar rats treated with 5-FU, and to evaluate the immunomodulatory effect of these drugs on serum nitrite production, in situ IFN-γ, TNF-α and TGF-β, and TNF-α in tissues. A total of 32 male Wistar rats with an average age of 9 weeks and an average body weight of 250 g were divided into four treatment groups: Saline, trans-caryophyllene, pentoxifylline and atorvastatin. Oral mucositis was then induced. On days 3 and 4, the mucosa of the mouth of eight pre-treated animals in each group was bilaterally scarified twice with the tip of a sterile needle, with an anesthetic solution. Mucosal samples from animals treated with trans-caryophyllene preserved a thin epithelial lining associated with focal perivascular inflammatory infiltrates. Pentoxifylline-treated animals exhibited total epithelial loss in oral wounds with severe inflammatory infiltrates and mild re-epithelialization associated with mild and diffuse inflammatory infiltrates. Samples from atorvastatin-treated animals exhibited no epithelial dissolution, with preserved thin lining and mild diffuse inflammatory infiltrates. The analysis of TNF-α expression revealed improved results in trans-caryophyllene animals. The analysis of TGF-β expression revealed positive mononuclear cells. Preventive treatment with atorvastatin was demonstrated to modulate the serum expression levels of TNF-α during all stages of the experiment. Treatment with trans-caryophyllene modulated serum IFN-γ levels negatively, whereas treatment with atorvastatin and trans-caryophyllene maintained lower levels of IFN-γ compared with the control group.

High-protein diet improves postoperative weight gain after massive small-bowel resection

INTRODUCTION

Short bowel syndrome (SBS) is a morbid clinical condition that results from massive small-bowel resection (SBR). After SBR, there is a dramatic weight loss in the acute postoperative period. Our aim was to determine the impact of a high-protein diet (HPD) on weight gain and body composition in mice after SBR.

METHODS

C57BL/6 mice underwent 50 % proximal SBR. Postoperatively, mice were randomly selected to receive standard rodent liquid diet (LD) (n = 6) or an isocaloric HPD (n = 9) for 28 days. Mice weights were recorded daily. Body composition analyses were obtained weekly. Student's t test was used for statistical comparisons with p < 0.05 considered significant.

RESULTS

Mice that were fed HPD after SBR returned to baseline weight on average at postoperative day (POD) 8 versus mice that were fed LD that returned to baseline weight on average at POD 22. Total fat mass and lean mass were significantly greater by POD 14 within the HPD group. Both groups of mice demonstrated normal structural adaptation.

CONCLUSION

HPD results in greater weight gain and improved body composition in mice after SBR. This finding may be clinically important for patients with SBS since improved weight gain may reduce the time needed for parenteral nutrition.

Role of inducible nitric oxide synthase pathway on methotrexate-induced intestinal mucositis in rodents

BACKGROUND

Methotrexate treatment has been associated to intestinal epithelial damage. Studies have suggested an important role of nitric oxide in such injury. The aim of this study was to investigate the role of nitric oxide (NO), specifically iNOS on the pathogenesis of methotrexate (MTX)-induced intestinal mucositis.

METHODS

Intestinal mucositis was carried out by three subcutaneous MTX injections (2.5 mg/kg) in Wistar rats and in inducible nitric oxide synthase knock-out (iNOS-/-) and wild-type (iNOS+/+) mice. Rats were treated intraperitoneally with the NOS inhibitors aminoguanidine (AG; 10 mg/Kg) or L-NAME (20 mg/Kg), one hour before MTX injection and daily until sacrifice, on the fifth day. The jejunum was harvested to investigate the expression of Ki67, iNOS and nitrotyrosine by immunohistochemistry and cell death by TUNEL. The neutrophil activity by myeloperoxidase (MPO) assay was performed in the three small intestine segments.

RESULTS

AG and L-NAME significantly reduced villus and crypt damages, inflammatory alterations, cell death, MPO activity, and nitrotyrosine immunostaining due to MTX challenge. The treatment with AG, but not L-NAME, prevented the inhibitory effect of MTX on cell proliferation. MTX induced increased expression of iNOS detected by immunohistochemistry. MTX did not cause significant inflammation in the iNOS-/- mice.

CONCLUSION

These results suggest an important role of NO, via activation of iNOS, in the pathogenesis of intestinal mucositis.

Methotrexate-induced intestinal mucositis delays gastric emptying and gastrointestinal transit of liquids in awake rats

CONTEXT: Methotrexate and other anticancer agents can induce intestinal mucositis, which is one of the most common limiting factor that prevent further dose escalation of the methotrexate. OBJECTIVES: To evaluate the gastric emptying and gastrointestinal transit of liquids in methotrexate-induced intestinal mucositis. METHODS: Wistar rats received methotrexate (2.5 mg/kg/day for 3 days, subcutaneously) or saline. After 1, 3 and 7 days, sections of duodenum, jejunum and ileum were removed for assessment of epithelial damage and myeloperoxidase activity (biochemical marker of granulocyte infiltration). Others rats were pre-treated with methotrexate or saline, gavage-fed after 3 or 7 days with a standard test liquid meal, and sacrificed 10, 20 or 30-min later. Gastric and small intestine dye recoveries were measured by spectrophotometry. RESULTS: After 3 days of methotrexate, there was an epithelial intestinal damage in all segments, with myeloperoxidase activity increase in both in duodenum and ileum. Seven days after methotrexate, we observed a complete reversion of this intestinal damage. There was an increase in gastric dye recoveries after 10, 20, and 30-min post-prandial intervals after 3 days, but not after 7 days, of methotrexate. Intestine dye recoveries were decreased in the first and second segments at 10 min, in the third at 20 min, and in the second and third at 30 min, only after 3 days of methotrexate treatment. CONCLUSION: Methotrexate-induced intestinal mucositis delays gastric emptying and gastrointestinal transit of liquids in awake rats.

Intervention of alpha-lipoic acid ameliorates methotrexate-induced oxidative stress and genotoxicity: A study in rat intestine

Methotrexate (MTX) is an anti-metabolite, widely used in the cancer chemotherapy and rheumatoid arthritis. However, its long-term clinical use is restricted on account of its severe intestinal toxicity. The present study was aimed to investigate the intestinal toxicity of MTX and the possible protective effect of alpha-lipoic acid (LA) on Sprague-Dawley rats. MTX-induced intestinal toxicity was evaluated at the dose of 2.5mg/kg for short-term (5 days treatment) and 1mg/kg for long-term (5 days in a week for four consecutive weeks treatment) study. The possible protective effect of LA was evaluated in both short- as well as long-term study in a dose-dependent manner. MTX treatment induced diarrhoea and mortality in rats, indicating its severe toxicity in the target organ of investigation, i.e., intestine. Further, the intestinal toxicity of MTX was assessed by evaluating different parameters of oxidative stress, DNA damage, cytotoxicity as well as histological changes. Immunostaining for p53 revealed higher genotoxic assault in the intestinal cells due to MTX treatment. Pretreatment of rats with LA led to significant decrease in the oxidative stress, DNA damage, cellular damage, inflammatory changes and apoptosis as determined by malondialdehyde level, glutathione level, comet assay parameters, histological evaluation, immunostaining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. In the present investigation, we report that LA pretreatment ameliorates MTX-induced intestinal toxicity in rat as evident from the protection against oxidative stress, decrease in DNA damage and protection of cellular morphology as well as improvement in the stool consistency and animal survival rate.

Nutritional supplementation with transforming growth factor-beta, glutamine, and short chain fatty acids minimizes methotrexate-induced injury

OBJECTIVE

Gastrointestinal (GI) damage caused by methotrexate (MTX) results in mucosal injury, bacterial invasion, and activation of an immune system that is reduced in function. Diets enriched with glutamine, short chain fatty acids (SCFAs), and transforming growth factor (TGF)-beta have demonstrated decreased infection, weight loss, and GI damage in Crohn disease. We, therefore, sought to study the cytoprotective effects of a diet enriched in glutamine, TGF-beta, and SFCAs (Modulen) in Fischer 344 rats exposed to MTX.

METHODS

Rats were divided into five groups: two receiving normal saline and three receiving MTX and fed either normal chow, Modulen supplemented chow starting with the first MTX dose, or Modulen supplemented chow beginning 3 days before MTX injection. Rats were weighed daily. On day 5, albumin and bicarbonate levels were drawn, and rats were killed for examination of their intestinal mucosa by a pathologist unaware of groupings.

RESULTS

Rats pretreated with Modulen supplemented chow maintained weight (2.6 vs, 12.3 g weight loss), albumin levels (3.13 vs, 2.43 mg/dL), and bicarbonate levels (23.8 vs. 18.1 mg/dL) as compared with rats fed normal chow throughout MTX treatment (P < 0.05). Pretreatment with Modulen also protected against crypt cell loss, villus atrophy, crypt abscesses, crypt/villus ratio, and overall histologic damage (P < 0.05).

CONCLUSION

When administered before and during MTX treatment, Modulen supplementation provided statistically significant protection against weight loss, hypoalbuminemia, acidosis, and GI damage in a rat model. Future animal research of Modulen's protective effects with other chemotherapeutic agents is needed before human trials.

Insulin-like growth factor-I (IGF-I) stimulates regrowth of the damaged intestine in rats, when administered following, but not concurrent with, methotrexate

BACKGROUND

We tested the ability of insulin-like growth factor-I (IGF-I) to reduce damage to the intestinal mucosa (mucositis) in rats injected with methotrexate. IGF-I was infused concurrent with methotrexate administration and compared to IGF-I administered following the withdrawal of methotrexate.

METHODS

Rats were injected with methotrexate at the start of days 1, 2 and 3. IGF-I was infused for 5 days, commencing at the start of day 1 [concurrent administration] or at the start of day 4 [post-methotrexate administration].

RESULTS

IGF-I administered coincident with methotrexate failed to restore mucosal integrity to the damaged small intestine. IGF-I administered post methotrexate stimulated regrowth of the damaged intestine, particularly the ileum, with 22%, 32% and 29% increases in small intestinal weight, ileal villus height and ileal crypt depth respectively.

CONCLUSIONS

Following intestinal damage of methotrexate, IGF-I primarily induced growth of the distal small intestine. The ineffectiveness of concurrently administered IGF-I may have represented an IGF-I induced recruitment of proliferating epithelial cells to the anti-proliferative effects of methotrexate.

Vitamin A deficiency exacerbates methotrexate-induced jejunal injury in rats

Two studies were conducted to investigate whether vitamin A-deficient rats were more susceptible to intestinal injury caused by methotrexate (MTX), since vitamin A deficiency alone causes only mild changes to jejunal structure and function. Weanling male rats were fed a vitamin A-deficient diet (-VA) for 40-42 d and compared to rats either pair-fed (PF) or with free access (+VA) to the same diet. Drinking water of PF and +VA rats was supplemented with 37.5 microg (Study 1) or 75 microg (Study 2) vitamin A (Rovimix A 500W)/d. Rats in each group received MTX (-VAMTX, PFMTX, +VAMTX) or vehicle. MTX administration reduced intestinal mucosal wet weight, protein and DNA concentrations, and sucrase and maltase activities in -VA and PF rats (P < 0.02). In Study 1, -VAMTX rats developed a severe jejunal enteropathy and had a higher incidence of diarrhea (P < 0.005), greater weight loss (P < 0.005), more disruption of villus architecture (P < 0.0001) and lower disaccharidase activity (P < 0.007) than PFMTX rats. Similar results were observed in Study 2. Liver retinol concentration (but no other variable) was greater in rats receiving 75 microg vitamin A/d (P < 0.001) than in those receiving 37.5 microg/d. The interaction of vitamin A deficiency and small intestinal injury may explain the efficacy of vitamin A supplementation in preventing childhood diarrheal disease mortality in developing countries, and highlights the need for ensuring adequate vitamin A status in people worldwide with diseases and/or treatments which may injure the gastrointestinal tract.

Phospholipids prevent enteric bacterial translocation in the early stage of experimental acute liver failure in the rat

BACKGROUND

Bacterial infections and bacteremia in acute liver failure may at least partly be attributed to translocation of enteric bacteria. Attempts to prevent or treat such infections by the use of antibiotics may instead result in overgrowth of surviving microbes.

METHODS

In the present study, normal saline (1.5 ml/100 g body weight), phosphatidylcholine (1.5 ml/100 g body weight), and phosphatidylinositol (1.5 ml/100 g body weight) were orally administered by means of a gastric tube both 12 h and 30 min before operation. Effects of enteric administration of phospholipids on the prevention of enteric bacterial translocation, intestinal and mucosal mass, and enterocyte protein contents in acute liver failure induced by subtotal liver resection in the rat were evaluated.

RESULTS

The incidence of bacterial translocation increased significantly 2 and 4 h after 90% hepatectomy as compared with sham-operated animals. Enteric administration of phospholipids, however, significantly reduced the incidence of bacterial translocation after 90% hepatectomy. Phospholipid treatment prevented the postoperative decrease in intestinal mucosal mass and enterocyte protein content.

CONCLUSIONS

Enteral administration of phospholipids thus seems to protect against translocation of enteric bacteria and prevent against a decrease in intestinal mucosal mass and enterocyte protein content after subtotal hepatectomy in the rat.