Mucosal cytokine production in radiation-induced proctosigmoiditis compared with inflammatory bowel disease

Recent advances in the management of radiation colitis

Radiation colitis, an insidious, progressive disease of increasing frequency, develops 6 mo to 5 years after regional radiotherapy for malignancy, owing to the deleterious effects of the latter on the colon and the small intestine. When dealing with radiation colitis and its complications, the most conservative modality should be employed because the areas of intestinal injury do not tend to heal. Acute radiation colitis is mostly self-limited, and usually, only supportive management is required. Chronic radiation colitis, a poorly predictable progressive disease, is considered as a precancerous lesion; radiation-associated malignancy has a tendency to be diagnosed at an advanced stage and to bear a dismal prognosis. Therefore, management of chronic radiation colitis remains a major challenge owing to the progressive evolution of the disease, including development of fibrosis, endarteritis, edema, fragility, perforation, partial obstruction, and cancer. Patients are commonly managed conservatively. Surgical intervention is difficult to perform because of the extension of fibrosis and alterations in the gut and mesentery, and should be reserved for intestinal obstruction, perforation, fistulas, and severe bleeding. Owing to the difficulty in managing the complications of acute and chronic radiation colitis, particular attention should be focused onto the prevention strategies. Uncovering the fibrosis mechanisms and the molecular events underlying radiation bowel disease could lead to the introduction of new therapeutic and/or preventive approaches. A variety of novel, mostly experimental, agents have been used mainly as a prophylaxis, and improvements have been made in radiotherapy delivery, including techniques to reduce the amount of exposed intestine in the radiation field, as a critical strategy for prevention.

Effects of transplanted bone marrow mesenchymal stem cells on the irradiated intestine of mice

We investigated the potency of exogenous bone marrow mesenchymal stem cells (MSCs) to engraft into irradiated intestine, as well as these cells' effects on radiation-induced enteric injury. MSCs from beta-Gal-transgenic mice were transplanted into C57BL/6J recipient mice that received abdominal irradiation (13 Gy). At different time points, recipient intestines were examined for the engraftment of donor-derived cells by immunofluorescence analysis. Additionally, the expression status of chemokines induced by radiation injury was analyzed in the irradiated intestine. Next, MSCs were transduced with an adenoviral vector encoding a certain chemokine receptor gene in order to promote the engraftment rate via chemotaxis. The intestinal permeability and histomorphological alterations were measured to evaluate the therapeutic effect of MSC transplantation. The results demonstrated that infused MSCs possessed the potency to engraft into irradiated enteric mucosa, but the engraftment rate was too low to produce a therapeutic effect. The expression of stromal cell-derived factor-1 (SDF-1) was up-regulated in irradiated intestine. MSCs genetically modified by CXCR4 (the receptor for SDF-1) engrafted into irradiated intestine at a significantly elevated level and ameliorated the intestinal permeability and histopathological damage.

Effects of Elaeagnus bockii Diels polysaccharide on the small intestine of mice after whole body irradiation with 60Cog ray

AIM: To study the protective effect of Elaeagnus bockii Diels (EbD) polysaccharide on the small intestine of mice after whole body irradiation with ⁶⁰Coγ ray.

METHODS: Sixty Kunming mice were divided in normal group, irradiative injury group, and EbD-treated groups (100, 300, 500 mg/kg). Irradiative injury was induced using 60Coγ ray. EbD polysaccharide was administered by clyster once a day for two weeks. Fourteen days later, the mice were sacrificed and about 2-cm segment of duodenum, jejunum and ileum were dissected respectively for crypt survival assay. The contents of intestinal mucosal protein, DNA and diamine oxidase (DAO) were determined. The activity of superoxide dismutase (SOD), the level of malondialdehyde (MDA) in the small intestine, the serum levels of tumor necrosis factor (TNF), interleukin-4 (IL-4) and IL-6 were also measured.

RESULTS: EbD polysaccharide (100, 300, 500 mg/kg) increased crypt survival rates of duodenum, jejunum and ileum (P < 0.05), promoted the synthesis of intestinal mucosal protein and DNA (P < 0.05 or P < 0.01), enhanced the levels of IL-4 (9.79 ± 2.23, 10.83 ± 2.34, 11.36 ± 2.51 vs 7.40 ± 2.08; P < 0.05 or P < 0.01), IL-6 (49.36 ± 9.65, 55.26 ± 11.32, 59.68 ± 13.65 vs 43.74 ± 12.91; P < 0.05 or P < 0.01) and the activity of SOD, while deceased the level of TNF (6.89 ± 1.33, 6.74 ± 1.24, 5.87 ± 1.13 vs 8.53 ± 1.08; P < 0.05 or P < 0.01) and the content of MDA. The above effect was dose dependent.

CONCLUSION: EbD polysaccharide can protect the small intestine from irradiation-induced injury by promoting the synthesis of intestinal mucosal protein and DNA, modulating the abnormality of cytokines, and eliminating oxygen free radicals.

Increase of hepcidin plasma and urine levels is associated with acute proctitis and changes in hemoglobin levels in primary radiotherapy for prostate cancer

PURPOSE

To analyse hepcidin serum and urine levels during radiotherapy for prostate cancer.

METHODS

In 18 patients undergoing radiotherapy for prostate cancer, blood, plasma, and urine samples were taken before and during radiotherapy. Complete blood cell count, pro-hepcidin-, ferritin-, transferrin-, IL-1beta-, IL-6-, and TNF-alpha concentration was determined. Pro-hepcidin concentration was additionally measured in urine samples. Toxicity was evaluated weekly. Differences among tested factors were tested by Wilcoxon rank sign test for paired data.

RESULTS

In ten patients developing acute radiation-induced proctitis, a significant increase in pro-hepcidin, IL-6, and TNF-alpha plasma levels (p < 0.05) was detected. Pro-hepcidin urine levels also showed a strong trend towards increase (p = 0.06). Concurrently, hemoglobin, and leucocytes were significantly decreased in the patients with acute proctitis (p < 0.05). In eight patients showing no symptoms of proctitis, solely a significant decrease for leucocytes was detected. Additive, these patients showed a significant increase of ferritin, and a decrease of transferrin levels (p < 0.05).

CONCLUSIONS

Hepcidin levels are increased and hemoglobin is decreased during radiotherapy for prostate cancer in patients who develop acute proctitis. Radiation-induced expression of cytokines may be responsible for increased hepcidin expression in the liver. Regulation of iron metabolism by hepcidin may be an underestimated response in radiotherapy.

Gene expression changes in peripheral blood cells provide insight into the biological mechanisms associated with regimen-related toxicities in patients being treated for head and neck cancers

Patients treated with radiotherapy are prone to a constellation of local and systemic toxicities including mucositis, xerostomia, fatigue and anorexia. The biological complexities and similarities underlying the development of toxicities have recently been realized. Mucosal barrier injury is one of the best studied, and gene expression patterns, based on animal tissue samples, have added to its understanding. While investigations gene expression based on tissue samples was valuable, its use precludes more generalizable conclusions relative to common pathogenic mechanisms. Additionally, attempting to define the kinetics of changes in gene expression by sequential sampling is pragmatically unrealistic. Our objectives were: 1. to determine if changes in gene expression could be detected during toxicity development using PBM from patients receiving chemoradiation; 2. to characterize the relationship of expressed genes using graph theory and pathway analysis; and 3. to evaluate potential relationships between the expression of particular genes, canonical pathways, and functional networks in explaining the pathogenesis of regimen-related toxicities.

DESIGN

Microarray analysis was performed using PBM-derived cRNA obtained before and 2 weeks after the initiation of chemoradiation in five patients with head and neck cancer who developed documented regimen-related toxicities. We created a database of those genes newly expressed at 2 weeks and evaluated their potential significance relative to toxicity, by canonical pathway analysis, compilation of regional networks around focus genes, and development of a model globalizing the individual functional networks. There was strong concordance between known pathogenic mechanisms of toxicity and the genes, pathways, and networks developed by our data. A role was elicited for unsuspected genes in toxicity development. Our results support the concept that radiation induced toxicities have common underlying mechanisms and demonstrate the utility of PBM as an RNA source for genetic studies. This methodology could be broadly applicable to the study of regimen-related toxicities.

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The insulin-like growth factor system and markers of inflammation in adult patients with inflammatory bowel disease

BACKGROUND AND OBJECTIVES

Catabolism and growth impairment are well-known complications of inflammatory bowel disease (IBD). Recent studies have demonstrated significant changes in the IGF system in IBD patients. The aim of the present study was to investigate correlations between the IGF system and markers of inflammation in IBD.

METHODS

A cross-sectional study comprising 99 IBD patients (Crohn's disease (CD, n = 50) and ulcerative colitis (UC, n = 49)). Correlations between markers of inflammation and IGF-I, IGF-II and IGFBP-3 were examined in CD and UC patients in remission and relapse. The patients were clinically scored using Crohn's Disease Activity Index (CDAI) for CD patients and Activity Index (AI) for UC patients.

RESULTS

In the UC group we found correlations between IGF-I and CRP (r(s) = Spearman's rho) (r(s) = -0.40, p < 0.01) and albumin (r(s) = 0.46, p < 0.001), IGFBP-3 and albumin (r(s) = 0.36, p < 0.01) and AI score (r(s) = -0.31, p < 0.05). IGF-II correlated with CRP (r(s) = -0.42, p < 0.01), IL-6 (r(s) = -0.65, p < 0.001), albumin (r(s) = 0.41, p < 0.01), AI score (r(s) = -0.30, p < 0.05) and orosomucoid (r(s) = -0.47, p < 0.001). In the CD group we found correlations between IGF-I and CRP (r(s) = -0.40, p < 0.05), and albumin (r(s) = -0.46, p < 0.01), IGFBP-3 and albumin (r = 0.36, p < 0.01). IGF-II correlated with IL-6 (r(s) = -0.65, p < 0.001), albumin (r(s) = 0.41, p < 0.01), CDAI score (r(s) = -0.30, p < 0.05) and orosomucoid (r(s) = -0.47, p < 0.001).

CONCLUSIONS

IGF-I, IGF-II and IGFBP-3 are correlated to albumin and IGF-I and IGF-II are correlated to CRP in IBD patients. Further, IGF-II is correlated to IL-6 in IBD patients. This may suggest a correlation between inflammation and the IGF system with involvement in muscle and bone catabolism in IBD.

Abdominal radiation exposure elicits inflammatory responses and abscopal effects in the lungs of mice

An inflammatory reaction is a classical feature of radiation exposure and appears to be a key event in the development of the acute radiation syndrome. We have investigated the radiation-induced inflammatory response in C57BL6/J mice after total abdominal or total-body irradiation at a dose of 15 Gy. Our goal was to determine the radiation-induced inflammatory response of the gut and to study the consequences of abdominal irradiation for the intestine and for the lungs as a distant organ. A comparison with total-body irradiation was used to take into account the hematopoietic response in the inflammatory process. For both irradiation regimens, systemic and intestinal responses were evaluated. A systemic inflammatory reaction was found after abdominal and total-body irradiation, concomitant with increased cytokine and chemokine production in the jejunum of irradiated mice. In the lungs, the radiation-induced changes in the production of cytokines and chemokines and in the expression of adhesion molecules after both abdominal and total-body irradiation indicate a possible abscopal effect of radiation in our model. The effects observed in the lungs after irradiation of the abdomino-pelvic region may be caused by circulating inflammatory mediators consequent to the gut inflammatory response.

Anti-inflammatory role of interleukin-15 in Crohn's disease

BACKGROUND

Interleukin (IL)-15 is overexpressed in intestinal tissue with active Crohn's disease (CD). However, its role in the pathogenesis of the disease remains uncertain. We studied the effects of IL-15 on colonic mucosal proinflammatory cytokine response in vitro using organ culture of human colonic explants.

METHODS

Colonic tissue was obtained from (1) resections in pediatric CD patients (inflamed and noninflamed) and (2) rectal biopsies in patients with CD undergoing colonoscopy (n = 31) and controls (n = 9). In preliminary experiments, explants from the resections were cultured in the presence or absence of a simulated T(H)1 stimulation using ionomycin (Io) and phorbol-myristate-acetate (PMA), with or without IL-15, or in medium alone. Rectal biopsies were cultured in the same conditions as above, with or without adding a monoclonal anti-IL-15 neutralizing antibody (mAb). Levels of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and IL-2R alpha were measured by enzyme-linked immunosorbent assay.

RESULTS

IL-15, in the absence of Io + PMA, did not induce the expression of IFN-gamma, TNF-alpha, or IL-2R alpha. Only inflamed explants from resections stimulated with Io + PMA expressed IFN-gamma, TNF-alpha, and IL-2R alpha. This T(H)1 stimulatory effect was inhibited by IL-15 in a dose-dependent fashion. In rectal biopsy explants, inflamed, noninflamed CD, and control tissue responded to stimulation with Io + PMA (P < 0.05) with increased IFN-gamma and TNF-alpha (P < 0.05). This response was again inhibited by IL-15. The inhibitory effect of IL-15 was specifically reversed by anti-IL-15 mAb (P < 0.05). The data for the CD group were also analyzed according to the severity of colonic inflammation and medication use.

CONCLUSIONS

Our results suggest a possible anti-inflammatory role for IL-15 in CD. We postulate that its overexpression in CD potentially represents a protective mechanism against the exaggerated T(H)1 immune response.

Effect of tumor necrosis factor-alpha and interferon-gamma on intestinal P-glycoprotein expression, activity, and localization in Caco-2 cells

The P-glycoprotein (Pgp), a drug efflux pump, is expressed in intestinal epithelial cells, where it constitutes a barrier against xenobiotics. In inflammatory bowel disease, a dysregulation in the production of tumor necrosis factor (TNF)alpha and interferon (IFN)gamma, and an alteration of Pgp expression and activity have been reported. The aim of this study was to investigate the effects of TNF alpha and IFN gamma on intestinal Pgp expression, activity, and localization in Caco-2 cells grown on filters. TNF alpha induced both a strong time-dependent diminution (-56%) of MDR1 mRNA (semiquantitative reverse transcription polymerase chain reaction) and a significant decrease of unidirectional transport of rhodamine 123 after 48 h of exposure at 10 ng/mL. By confocal laser scanning microscopy, the Pgp was mainly localized to the apical plasma membrane of both control and TNF alpha-treated cells. By contrast, IFN gamma induced up-regulation of both mRNA MDR1 and Pgp protein expression without incidence on Pgp activity. Interestingly, a colocalization of Pgp with lateral F-actin was observed. Associated with TNF alpha, IFN gamma produced neither an antagonist nor synergistic effect on Pgp activity. In conclusion, our results demonstrate an inhibitory effect of TNF alpha and no effect of IFN gamma on Pgp transport activity using rhodamine 123 as a substrate. Mechanisms of action of these cytokines remain to be studied.

Abdominal irradiation increases inflammatory cytokine expression and activates NF-kappaB in rat ileal muscularis layer

The small bowel is an important dose-limiting organ in abdominal radiotherapy because irradiation can cause acute enteritis that, in turn, leads to progressively reduced motility and finally, in a later phase, to fibrosis. Because these clinical symptoms may be caused by the early stage of an inflammatory process, we characterized the radiation-induced intestinal inflammation in rats. Abdominal gamma-irradiation (10-Gy) induced a cascade of inflammatory events characterized by an early (6 h after exposure) increase in IL-1beta, TNF-alpha, and IL-6 mRNA levels in the rat ileal muscularis layer. IL-8 [a cytokine-induced neutrophil chemoattractant (CINC)] mRNA appeared later (at 3 days). The expression of TGF-beta (a profibrotic cytokine) was higher in irradiated than control tissue at day 1, whereas IL-10 (an anti-inflammatory cytokine) expression vanished completely. Despite strong IL-1ra expression, the IL-1ra/IL-1beta ratio, which is an indicator of inflammatory balance, was -41% at day 1 in irradiated compared with control tissue. The nuclear transcription factors NF-kappaB and activator protein-1 (AP-1) govern transcription of these genes, directly or indirectly. Although expression of the subunits of NF-kappaB (p65, p50) and AP-1 (c-fos, c-jun) did not increase, irradiation caused a rapid and persistent translocation of p65 and p50. An imbalance between proinflammatory and anti-inflammatory mediators may contribute to perpetuating intestinal inflammation, thus making it chronic.

Downregulation of electroacupuncture at ST36 on TNF-α in rats with ulcerative colitis

AIM: To investigate the regulatory effect of electroacupuncture (EA) at Zusanli (ST36) on tumor necrosis factor-alpha (TNF-α) in rats with ulcerative colitis (UC), and further elucidate the therapeutic mechanism of EA on UC.

METHODS: Thirty-two male Sprague-Dawley (SD) rats were randomly divided into four groups (n = 8): normal control group, UC control group, UC+ST36 group and UC+non-acupoint group. A solution containing ethanol and 2,4,6-trinitrobenzenesulfonic acid (TNBS) was instilled into the distal colon in the rat (at a dose of 100 mg/kg) to set up UC rat model. Rats in wakefulness state of UC+ST36 group were stimulated at ST36 by EA once a day, while those of UC+non-acupoint group were done at 0.5 cm beside ST36. After 10 d treatment, all rats were sacrificed simultaneously. Colon musocal inflammation and damage were assessed by measuring colon mass, morphologic damage score, colonic myeloperoxidase enzyme (MPO) activity, serum TNF-α and colonic TNF-α mRNA level. Morphologic damage score was examined under stereomicroscope. Colonic MPO activity was measured by spectrophotometer method. Serum TNF-α concentration was determined by radioimmunoassay (RIA). Colonic TNF-α mRNA expression level was analyzed by semiquantitative reverse transcription polymerase chain reaction (RT-PCR).

RESULTS: Ratio of colonic mass/body mass (m_C/m_B) and activity of colonic MPO (μkat/g tissue) markedly increased (8.5 ± 2.6 vs 2.5 ± 0.4; 145 ± 25 vs 24 ± 8, P < 0.01 vs normal control group). Compared with normal control rats, serum TNF-α and colonic TNF-α mRNA level in UC control group were increased 2.5 fold (2278 ± 170 vs 894 ± 248, P < 0.01) and 4.3 fold (0.98 ± 0.11 vs 0.23 ± 0.11, P < 0.01) respectively. After EA at ST36, m_C/m_B and MPO activity were reduced significantly (5.3 ± 2.0 vs 8.5 ± 2.6; 104 ± 36 vs 145 ± 25, P < 0.01, 0.05) compared with those of UC control group. Serum TNF-α and colonic TNF-α mRNA level were inhibited by EA stimulation at ST36 (P < 0.01). The inhibitory rate was 16% and 44% respectively. Morphologic damage score was also increased markedly in rat with UC (P < 0.01), whereas it was decreased by EA at ST36 (P < 0.05). There was no significant difference between UC control group and UC+EA at non-acupoint (P > 0.05). Furthermore, these parameters were highly correlated with each other (P < 0.01).

CONCLUSION: Serum TNF-α concentration and colonic TNF-α mRNA expression level are increased significantly in UC rats in correlation with the severity of disease. It indicates that TNF-α is closely involved in the immune abnormalities and inflammatory responses in UC. EA at ST36 has therapeutic effect on UC by downregulating serum TNF-α and colonic TNF-α mRNA expression. High levels of TNF-α and its corresponding mRNA expression seem to be implicated in the pathogenesis of UC.