Caffeic acid phenethyl ester modifies the Th1/Th2 balance in ileal mucosa after γ-irradiation in the rat by modulating the cytokine pattern

Polyphenols as Potential Protectors against Radiation-Induced Adverse Effects in Patients with Thoracic Cancer

Radiotherapy is one of the standard treatment approaches used against thoracic cancers, occasionally combined with chemotherapy, immunotherapy and molecular targeted therapy. However, these cancers are often not highly sensitive to standard of care treatments, making the use of high dose radiotherapy necessary, which is linked with high rates of radiation-induced adverse effects in healthy tissues of the thorax. These tissues remain therefore dose-limiting factors in radiation oncology despite recent technological advances in treatment planning and delivery of irradiation. Polyphenols are metabolites found in plants that have been suggested to improve the therapeutic window by sensitizing the tumor to radiotherapy, while simultaneously protecting normal cells from therapy-induced damage by preventing DNA damage, as well as having anti-oxidant, anti-inflammatory or immunomodulatory properties. This review focuses on the radioprotective effect of polyphenols and the molecular mechanisms underlying these effects in the normal tissue, especially in the lung, heart and esophagus.

Depolarization of pacemaker potentials by caffeic acid phenethyl ester in interstitial cells of Cajal from the murine small intestine

Interstitial cells of Cajal (ICCs) are pacemaker cells in the gastrointestinal (GI) tract and generate pacemaker potentials. In this study, we investigated the effects of caffeic acid phenethyl ester (CAPE) on the pacemaker potentials of ICCs from the mouse small or large intestine. Using the whole-cell patch-clamp configuration, we found that CAPE depolarized the pacemaker potentials of cultured ICCs from the murine small intestine in a dose-dependent manner. The estrogen receptor (ER) β antagonist PHTPP completely inhibited CAPE-induced depolarization, but the ERα antagonist BHPI did not. Intracellular GDP-β-S and pretreatment with Ca²⁺-free solution or thapsigargin also blocked CAPE-induced depolarization. To investigate the mechanisms of CAPE-mediated depolarization of ICCs, we used the nonselective cation channel (NSCC) inhibitor flufenamic acid, the Cl^- channel blocker, mitogen-activated protein kinase (MAPK) inhibitors PD98059, SB203580, or SP600125, and PI3 kinase inhibitor LY294002. All inhibitors blocked the CAPE-induced pacemaker potential depolarization of ICCs. These results suggest that CAPE induces pacemaker potential depolarization through ERβ in a G protein, NSCC, Cl^- channel, MAPK- and PI3 kinase dependent manner via intracellular and extracellular Ca²⁺ regulation in the murine small intestine. CAPE may therefore modulate GI motility by acting on ICCs in the murine small intestine.

Interleukin 6 Signaling Blockade Exacerbates Acute and Late Injury From Focal Intestinal Irradiation

PURPOSE

To evaluate the acute changes in leukocyte populations after focal irradiation and to assess the role of interleukin 6 (IL-6) in acute and late radiation injury.

METHODS AND MATERIALS

Mice were surgically implanted with a radiopaque marker on the surface of the small intestine. Mice were then imaged with cone beam computed tomography to locate the marker and irradiated with 18 Gy of 5 × 5 mm collimated x-rays onto the marked intestine using the Small Animal Radiation Research Platform. Intestinal sections and blood were harvested 1, 3.5, 7, and 14 days and 2 months postirradiation (post-IR) for histology and complete blood count, respectively. Immune cell populations were assessed by immunofluorescence in the acute phase. Collagen deposition was assessed 2 months post-IR. IL-6^-/- intestinal sections were assessed post-IR for morphology, EdU, Ki67, and TUNEL in comparison to IL-6^+/+ mice. Furthermore, a set of IL-6^+/+ mice were treated with anti-IL-6R to assess the role of IL-6 in late intestinal injury.

RESULTS

Intestinal radiation damage peaked 14 days post-IR, and fibrosis had developed by 60 days post-IR. There was a marked infiltration of immune cells into the irradiated intestine, with increased neutrophils, macrophages, B-cells, and CD4⁺ T cells maintained from 3.5 to 14 days post-IR. CD8⁺ T cells were decreased from days 7 to 14 post-IR. Systemically, leukocytes were increased in the peripheral blood 14 days post-IR with anemia being maintained from 14 days to 2 months. IL-6 was significantly increased in the serum post-IR. IL-6^-/- mice demonstrated worsened intestinal injury acutely post-IR. Moreover, anti-IL-6R-treated mice presented with worsened intestinal fibrosis 2 months post-IR.

CONCLUSIONS

Focal irradiation of the intestine produced a significant increase in immune cells in the irradiated area and systemic inflammation and anemia. Blockade of IL-6 signaling was found to exacerbate acute intestinal injury and late intestinal injury after focal irradiation.

Impairment of the Intrinsic Capability of Th1 Polarization in Irradiated Mice: A Close Look at the Imbalanced Th1/Th2 Response after Irradiation

Two major CD4⁺ T-helper (Th) lineages are Th1 and Th2, and well balanced Th1/Th2 responses are essential for immune function. In previously published studies, it was reported that radiation induces a Th1/Th2 immune imbalance toward a Th2-dominant direction, and this imbalance may contribute to postirradiation immune dysfunction. The polarization of Th cells is driven by the cytokine milieu and controlled by intracellular regulatory pathways that respond to cytokine signaling. It is widely accepted that radiation induces cytokine aberration, however, the precise alterations of cytokines in various tissue environments have been difficult to evaluate. In addition, the effects of radiation on the intrinsic functions of Th cells remain uncharacterized. Therefore, how radiation affects Th1/Th2 balance remains somewhat unclear. To address this, we investigated the changes in the polarization capability of Th cells by isolating them from mice previously exposed to radiation and assessing the cells in an established in vitro Th polarization system. Our novel results demonstrate that prior exposure to radiation led to the persistent aberration of the inherent capability of Th cells to differentiate into Th1 and Th2 lineages. The parallel changes in expression of Th1-specific master transcription factors and the key genes in metabolic reprograming indicated that radiation affects the core components in Th1 polarization. While Th1 differentiation was impaired after irradiation, little adverse effect was observed in Th2 differentiation; both of these findings contribute to the known phenotypes of Th1/Th2 imbalance caused by radiation.

CAPE Analogs Induce Growth Arrest and Apoptosis in Breast Cancer Cells

Breast cancer is the second leading cause of death amongst women worldwide. As a result, many have turned their attention to new alternative approaches to treat this disease. Caffeic acid phenylethyl ester (CAPE), a well-known active compound from bee propolis, has been previously identified as a strong antioxidant, anti-inflammatory, antiviral and anticancer molecule. In fact, CAPE is well documented as inducing cell death by inhibiting NFκB and by inducing pro-apoptotic pathways (i.e., p53). With the objective of developing stronger anticancer compounds, we studied 18 recently described CAPE derivatives for their ability to induce apoptosis in breast cancer cell lines. Five of the said compounds, including CAPE, were selected and subsequently characterised for their anticancer mechanism of action. We validated that CAPE is a potent inducer of caspase-dependent apoptosis. Interestingly, some newly synthesized CAPE derivatives also showed greater cell death activity than the lead CAPE structure. Similarly to CAPE, analog compounds elicited p53 activation. Interestingly, one compound in particular, analog 10, induced apoptosis in a p53-mutated cell line. These results suggest that our new CAPE analog compounds may display the capacity to induce breast cancer apoptosis in a p53-dependent and/or independent manner. These CAPE analogs could thus provide new therapeutic approaches for patients with varying genotypic signatures (such as p53 mutations) in a more specific and targeted fashion.

Caffeic acid phenethyl ester promotes anti-inflammatory effects by inhibiting MAPK and NF-κB signaling in activated HMC-1 human mast cells

CONTEXT

Caffeic acid phenethyl ester (CAPE), an active component of honeybee propolis, is known to have antioxidant, anti-inflammatory, and other beneficial medicinal properties. However, the molecular mechanisms underlying its anti-allergic effects in mast cells are unknown.

OBJECTIVE

The purpose of the present study was to examine whether CAPE modulates the immunoglobulin E (IgE)-mediated local allergic reaction in animals, as well as to elucidate the effects of CAPE on mast cells in vitro.

MATERIALS AND METHODS

To investigate the bioactive potential of CAPE (10 or 20 µM), HMC-1 cells were stimulated with phorbol 12-myristate 13-acetate plus calcium ionophore A23187 (PMACI) for 24 h in the presence or absence of CAPE. To study the pharmacological effects of CAPE, enzyme-linked immunosorbent assays (ELISAs), RT-PCR, Western blot analysis, electrophoretic mobility shift assays (EMSAs), and fluorescence assays were used.

RESULTS

CAPE (10 mg/kg) inhibited local IgE-mediated allergic reactions (0.164 versus 0.065 O.D.) in a mouse model. Additionally, CAPE (20 µM) attenuated PMACI-stimulated histamine release (3146.42 versus 2564.83 pg/ml) and the production of inflammatory cytokines, such as interleukin (IL)-1β (4.775 versus 0.713 pg/ml, IC50 = 6.67 µM), IL-6 (4771.5 versus 449.1 pg/ml, IC50 = 5.25 µM), and IL-8 (5991.7 versus 2213.1 pg/ml, IC50 = 9.95 µM) in HMC-1 cells. In activated HMC-1 cells, pretreatment with CAPE decreased the phosphorylation of c-Jun N-terminal kinase. In addition, CAPE inhibited PMACI-induced nuclear factor (NF)-κB activation by suppressing IκBα phosphorylation and its degradation.

DISCUSSION AND CONCLUSION

Our results indicated that CAPE can modulate mast cell-mediated allergic disease.

Caffeic acid phenethyl ester and therapeutic potentials

Caffeic acid phenethyl ester (CAPE) is a bioactive compound of propolis extract. The literature search elaborates that CAPE possesses antimicrobial, antioxidant, anti-inflammatory, and cytotoxic properties. The principal objective of this review article is to sum up and critically assess the existing data about therapeutic effects of CAPE in different disorders. The findings elaborate that CAPE is a versatile therapeutically active polyphenol and an effective adjuvant of chemotherapy for enhancing therapeutic efficacy and diminishing chemotherapy-induced toxicities.

Bone marrow transplantation helps restore the intestinal mucosal barrier after total body irradiation in mice

Bone marrow transplantation (BMT) substantially improves 10-day survival after total body irradiation (TBI), consistent with an effect on intestinal radiation death. Total body irradiation, in addition to injuring the intestinal epithelium, also perturbs the mucosal immune system, the largest immune system in the body. This study focused on how transplanted bone marrow cells (BMCs) help restore mucosal immune cell populations after sublethal TBI (8.0 Gy). We further evaluated whether transplanted BMCs: (a) home to sites of radiation injury using green fluorescent protein labeled bone marrow; and (b) contribute to restoring the mucosal barrier in vivo. As expected, BMT accelerated recovery of peripheral blood (PB) cells. In the intestine, BMT was associated with significant early recovery of mucosal granulocytes (P = 0.005). Bone marrow transplantation did not affect mucosal macrophages or lymphocyte populations at early time points, but enhanced the recovery of these cells from day 14 onward (P = 0.03). Bone marrow transplantation also attenuated radiation-induced increase of intestinal CXCL1 and restored IL-10 levels (P = 0.001). Most importantly, BMT inhibited the post-radiation increase in intestinal permeability after 10 Gy TBI (P = 0.02) and modulated the expression of tight junction proteins (P = 0.01-0.05). Green fluorescent protein-positive leukocytes were observed both in intestinal tissue and in PB. These findings strongly suggest that BMT, in addition to enhancing general hematopoietic and immune system recovery, helps restore the intestinal immune system and enhances intestinal mucosal barrier function. These findings may be important in the development and understanding of strategies to alleviate or treat intestinal radiation toxicity.

Protection by L-carnitine against radiation-induced ileal mucosal injury in the rat: pattern of oxidative stress, apoptosis and cytokines

PURPOSE

In this study, we tested the effects of L-carnitine (LC) on radiation-induced ileal mucosal damage.

MATERIALS AND METHODS

Thirty Wistar albino rats were divided into five groups. The control group received physiological saline intraperitoneally (i.p.). Radiation-1 and radiation-2 groups received whole-body X-irradiation of 8.3 Gy as a single dose. These groups were sacrificed at the 6th hour and 4th day after irradiation, respectively. The Radiation-1 + LC and the radiation-2 + LC groups received the same dose irradiation plus a daily dose of 200 mg/kg LC. LC was applied one day before and for four days after irradiation.

RESULTS

The levels of serum monocyte chemotactic protein-1 (MCP-1) and interferon gamma (IFN-γ) were significantly higher in the radiation groups when compared with the control. Treatment with LC decreased the serum MCP-1 and IFN-γ levels considerably. In the radiations groups, the Chiu score was significantly elevated compared with that of the control group. However, LC administered prior to the irradiation reduced the severity of mucosal damage. The number of apoptotic cells of the ileal crypt in the irradiated rats increased from the 6th hour after irradiation and then decreased at 4th day.

CONCLUSIONS

Our data demonstrated that LC may be beneficial to radiation enteritis.

Regulatory effect of caffeic acid phenethyl ester on type I collagen and interferon-gamma in bleomycin-induced pulmonary fibrosis in rat

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease of unknown etiology. Recent investigations have demonstrated that the impaired immune response is a common characteristic feature of IPF. Unfortunately, no definitive and effective drug treatment is available that could improve or at least inhibit the progressive course of this fatal disease. That is why one of the main priorities of pulmonary fibrosis investigations is to identify novel and effective molecular targets for preventive and therapeutic interventions. caffeic acid phenethyl ester (CAPE) is one of the most interesting bioactive compounds extracted from bee propolis. It has been shown that CAPE has an antioxidant activity and modulatory impact on immune system. Accordingly, the aim of the present study was to investigate the regulatory effects of CAPE on the levels of type I collagen (COL-1) and Interferon-gamma (IFN-γ) in bleomycin (BLM)-induced pulmonary fibrosis. Immunohistochemistry procedure was employed to assess the effects of CAPE on lung tissue. In this study, male Sprague-Dawley rats were divided into 5 groups (n=8) included 1: Positive control group: bleomycin (BLM). 2: Negative (saline) control group. 3, 4: Treatment groups of 1 and 2: BLM+CAPE (5 and 10 μmol/kg/day, respectively). (5: Sham group: CAPE (10 μmol/kg/day). BLM application resulted in significant changes in the level of studied parameters as compared to the controls. CAPE could decrease type I collagen concentration, modulate IFN-γ level, increase the animals' body weight and decrease the lung index dose-dependently, compared with model group. In conclusion, CAPE may provide a novel therapeutic target for treating pulmonary fibrosis.

Immunomodulatory effects of crude phenylethanoid glycosides from Ligustrum purpurascens

ETHNOPHARMACOLOGICAL RELEVANCE

Ligustrum purpurascens, named as "Ku ding cha", has been used as a kind of functional tea in southern China for about two thousand years, which has the effects on diuresis, anti-hypertension, weight-loss and anti-inflammation.

THE AIM OF THE STUDY

This study was aimed to investigate the immune enhancement effects of the crude phenylethanoid glycosides (CPGs) from Ligustrum. Purpurascens on mice and analyze the chemical profiles of phenylethanoid glycosides in the CPGs.

MATERIALS AND METHODS

The immune functions enhancing potential of CPGs was determined using serum hemolysin antibody, phagocytosis, splenocyte antibody production, and NK cells activity assays. The contents of five major constituents in the crude glycosides of Ligustrum purpurascens were determined by using liquid chromatography, other five glycosides were deduced according to their UV and MS spectra compared with the literature as well.

RESULTS

In the immunizing experiment, mice treated with different doses of CPGs showed an increase (p<0.01) in the haemagglutination titre compared with the control group. The increases (p<0.05) were found to be significant at doses of 440 mg/kg and 1.32 g/kg in the experiments of antibody production of spleen cells, MΦ phagocytosis of chicken RBCs and NK cell activity. Further chemical characterization yielded 10 constituents from CPGs, five glycosides were quantified by HPLC and the structures of other five compounds were speculated according to their UV and MS spectra.

CONCLUSION

The results suggested that phenylethanoid glycosides from Ligustrum purpurascens have immunomodulatory effects on mice.

The potential usage of caffeic acid phenethyl ester (CAPE) against chemotherapy-induced and radiotherapy-induced toxicity

Protection of the patients against the side effects of chemotherapy and radiotherapy regimens has attracted increasing interest of clinicians and practitioners. Caffeic acid phenethyl ester (CAPE), which is extracted from the propolis of honeybee hives as an active component, specifically inhibits nuclear factor κB at micromolar concentrations and show ability to stop 5-lipoxygenase-catalysed oxygenation of linoleic acid and arachidonic acid. CAPE has antiinflammatory, antiproliferative, antioxidant, cytostatic, antiviral, antibacterial, antifungal and antineoplastic properties. The purpose of this review is to summarize in vivo and in vitro usage of CAPE to prevent the chemotherapy-induced and radiotherapy-induced damages and side effects in experimental animals and to develop a new approach for the potential usage of CAPE in clinical trial as a protective agent during chemotherapy and radiotherapy regimens.

Radiation-induced damage in different segments of the rat intestine after external beam irradiation of the liver

INTRODUCTION

The out-of-field effects on the intestine, caused by radiation treatment of a parenchymatous organ, have not previously been studied.

METHODS

A single dose of 25Gy was administered percutaneously to the liver of male Wistar rats after a planning CT-scan. Sham-irradiated animals served as controls. At 1, 6, 24, 96h, 1.5 and 3months the duodenum, jejunum, ileum and distal colon were removed, washed and deep-frozen or prepared for paraffin staining.

RESULTS

All animals survived the treatment. Epithelial cell damage occurred in all small-intestinal segments. However, prolonged denudation of the villi together with destruction of the crypt lining was only observed in the ileum, resulting in deficient regeneration. In the colon, changes were minor. Radiation mucositis with granulocyte (MP0+) infiltration was seen from 1 to 24h in the duodenum and jejunum, when ED1+ macrophages, CD3+ T-lymphocytes, and CD34+ hematopoietic precursor cells were recruited, accompanied by an increase in the chemokines MCP-1, MIP-1α, MIP3α and Il-8. In the ileum, early granulocyte infiltration was delayed but continuous. Recruitment of macrophages and lymphocytes was deficient and induction of chemokines as of the adhesion molecules PECAM-1, ICAM-1 was lacking.

CONCLUSION

Post-irradiation damage to the ileum was delayed and followed by an altered repair process with structural changes of the villi. The observed changes might result from a higher sensitivity to oxidative stress mechanisms with subsequent damage of the regenerative capacity of the crypt-villus axis, accompanied by a sustained "inflammatory response" and vascular damage with a lack of regeneratory cell recruitment.

The immunoregulatory effects of caffeic acid phenethyl ester on the cytokine secretion of peripheral blood mononuclear cells from asthmatic children

BACKGROUND

Asthma is a chronic inflammatory disease of the airways for which current treatments are mainly based on pharmacological interventions, such as glucocorticoid therapy. Our objective was to study the immunoregulatory effects of caffeic acid phenethyl ester (CAPE, a phytochemical synthesized from propolis) on cytokine secretion of peripheral blood mononuclear cells (PBMCs) from asthmatic children.

METHODS

PBMCs from asthmatic children (5.5 ± 3.3 years old, n=28) and healthy children (5.6 ± 2.8 years old, n=23) were co-cultured with CAPE in vitro with and without phorbol-12-myristate-13-acetate-ionomycin.

RESULTS

Our results show that predominant interleukin 4 (IL-4) and interferon-gamma secretion of cultured supernatant were detected in healthy donors compared with asthmatics. In the presence of phorbol-12-myristate-13-acetate-ionomycin, with or without CAPE treatment, the asthmatic children showed significantly decreased levels of IL-10 secretion compared with the healthy controls. However, CAPE significantly decreased IL-10 and interferon-gamma in healthy donors. There was a slight but not statistically significant reduction of IL-4 secretion in CAPE-treated PBMCs compared with untreated control PBMCs from the healthy children. Our data also shows that CAPE significantly enhanced transforming growth factor-beta 1 production from PBMCs from asthmatic children.

CONCLUSION

The immunoregulatory effects of CAPE on human PBMCs may be through the induction of regulatory T cells, as evidenced by the enhanced transforming growth factor-beta 1 production from PBMCs from asthmatic children in our study.

Inhibitory effect of caffeic acid phenethyl ester, a plant-derived polyphenolic compound, on rat intestinal contractility

Caffeic acid phenethyl ester (CAPE) exerts pharmacological actions (e.g. anti-inflammatory, chemopreventive) which are relevant for potential clinical application in the digestive tract. However, no study has been published on its possible effects on intestinal motility, to date. In the present study, we investigated the effect of this plant-derived polyphenolic compound on the spontaneous contractions of the rat isolated ileum. CAPE reduced (in a tetrodotoxin-insensitive manner) spontaneous ileal contractions and this effect was reduced by the L-type Ca2+ channel blocker nifedipine and the chelant of calcium ethylenediaminetetraacetic acid. However, the effect of CAPE was not modified by a number of inhibitors/antagonists such as of phentolamine plus propranolol, atropine, tetrodotoxin, cyclopiazonic acid, omega-conotoxin, apamin, NG-nitro-L-arginine methyl ester, 3-isobutyl-1-methylxanthine, 9-(tetrahydro-2-furanyl)-9H-purin-6-amine, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one or a combination of SR 140333, SR48968 and SR142801. In conclusion our study shows that (i) CAPE relaxed myogenic contractions of rat ileum and that (ii) this effect occurs, at least in part, throughout a mechanism involving L-type Ca2+ channels.

Influence of sublethal total-body irradiation on immune cell populations in the intestinal mucosa

The intestinal immune system is the largest in the body. This study analyzed changes in intestinal immune cell populations, cytokine protein levels, and transcript profiles after total-body irradiation (TBI) in CD2F1 mice. A single dose of 8.0 Gy gamma radiation caused negligible 30-day lethality but induced significant histological damage in jejunal mucosa that was maximal at 3.5 days and that had seemingly recovered by day 21 after irradiation. These changes were accompanied by decreased numbers of mucosal macrophages, neutrophils, and B and T lymphocytes, mostly coinciding with similar reductions in peripheral blood cell counts. Recovery of mucosal macrophages occurred within 1 week, whereas mucosal granulocytes and lymphocytes remained low until 3 weeks after TBI. Maximal suppression of T-helper cell (T(H))-related transcripts occurred at 3.5 days, but there was no obvious T(H)1 or T(H)2 bias. Genome-wide transcriptional profiling revealed a preponderance of differentially regulated genes involved in cell cycle control, cell death and DNA repair between 4 h and 3.5 days after irradiation. Genes involved in tissue recovery predominated from day 7 onward. We conclude that the intestinal immune system undergoes profound changes after sublethal TBI and that these changes likely contribute to postirradiation pathophysiological manifestations.

Food-derived bioactives as potential regulators of the IL-12/IL-23 pathway implicated in inflammatory bowel diseases

The gene-specific modulation of inflammatory cytokines by food bioactives represents a possible approach to the nutritional or pharmaceutical prevention and treatment of inflammatory bowel disease (IBD). There is evidence for a key role of the interleukin-12beta1/23 receptor (IL-12 Rbeta1/23 R) pathway in IBD, and that reduction of the normal expression of the IL-23 R gene may provide a therapeutic target for this disease. The binding of interleukin-23 (IL-23) to its receptor IL-23 R regulates a newly defined effector T-cell subset, Th17 cells, characterised by the production of interleukin-17 (IL-17) and other cytokines, including tumour necrosis factor-alpha (TNF-alpha). In this study we developed an assay that measured IL-17 and TNF-alpha expression after incubation with specific dietary bioactives in the human T-cell Kit 225. It is anticipated that these changes will reflect differences in IL-23 R production, albeit indirectly. The cell line Kit 225 has similarities to Th17 cells, a subset of T cells producing IL-17 and TNF-alpha, and in initial experiments we demonstrated that the cells express both IL-23 receptor subunits, as well as IL-17 and TNF-alpha genes. Upon verification that stimulation of Kit 225 cells with 1ng/mL IL-23 significantly upregulated IL-17 and TNF-alpha gene expression, and IL-17 production, we supplemented cells with selected food bioactives, caffeic acid phenethyl ester (CAPE), epigallocatechin gallate (EGCG), docosahexaenoic acid (DHA), and linoleic acid (LA), and with phorbol myristate acetate (PMA) and sodium salicylate, used as pro-inflammatory and anti-inflammatory controls, respectively. In both unstimulated cells and after IL-23 stimulation, bioactives modulated the pro-inflammatory cytokines involved in IBD, underlining the possible role of foods in this disease. EGCG and DHA, which significantly inhibited both IL-17 and TNF-alpha expression, appeared particularly interesting.

PPARs in Irradiation-Induced Gastrointestinal Toxicity

The use of radiation therapy to treat cancer inevitably involves exposure of normal tissues. Although the benefits of this treatment are well established, many patients experience distressing complications due to injury to normal tissue. These side effects are related to inflammatory processes, and they decrease therapeutic benefit by increasing the overall treatment time. Emerging evidence indicates that PPARs and their ligands are important in the modulation of immune and inflammatory reactions. This paper discusses the effects of abdominal irradiation on PPARs, their role and functions in irradiation toxicity, and the possibility of using their ligands for radioprotection.

Acute and persisting Th2-like immune response after fractionated colorectal γ-irradiation

AIM: To investigate if an immune imbalance may account for the development and progression of chronic radiation enteritis. We analyzed the Th1/Th2 immune response profile early and 6 mo after fractionated colorectal irradiation.

METHODS: A rat model of fractionated colorectal γ-irradiation (4-Gy fractions, 3 fractions per week) was designed to investigate the effects of cumulative dose on inflammatory mediators (cytokines and chemokines) and immune response (Th1/Th2 profile and immunosuppressive mediator IL-10) during acute (early) response and 6 mo after the end of fractionated irradiation (chronic response). Analyses were performed 1 d after the cumulative doses of 16 Gy and 36 Gy and 1 d, 3 d, and 26 wk after the cumulative dose of 52 Gy.

RESULTS: Without causing histological damage, fractionated radiation induced elevated expression of IL-1β, TNFα, MCP-1, and iNOS in distal colonic mucosa during the early post-irradiation phase. At that time, a Th2 profile was confirmed by expression of both the Th2-specific transcription factor GATA-3 and the chemokine receptor CCR4 and by suppression of the Th1 cytokine IFNγ/IP-10 throughout the irradiation protocol. After 6 mo, despite the 2-fold reduction of iNOS and MCP-1 levels, the Th2 profile persisted, as shown by a 50% reduction in the expression of the Th1 transcription factor T-bet, the chemokine receptor CCXCR3, and the IFNγ/STAT1 pathway. At the same time-point, the immunosuppressive IL-10/STAT3 pathway, known to regulate the Th1/Th2 balance, was expressed, in irradiated rats, at approximately half its level as compared to controls. This suppression was associated with an overexpression of SOCS3, which inhibits the feedback of the Th1 polarization and regulates IL-10 production.

CONCLUSION: Colorectal irradiation induces Th2 polarization, defective IL-10/STAT3 pathway activation and SOCS3 overexpression. These changes, in turn, maintain a immunological imbalance that persists in the long term.

Dynamic Changes of Soluble Fas and IL-2/IL-10 in serum and Fas Expression in Lung in the Rats of Acute Necrotizing Pancreatitis

BACKGROUND

To investigate the dynamic changes of serum IL-2, IL-10, sFas and IL-2/IL-10 in a rat model with acute necrotizing pancreatitis (ANP). To explore the role of Th1/Th2 polarization and the Fas expression in the lung of rats with ANP.

METHODS

A total of 64 Sprague-Dawley rats were randomly divided into normal control group and ANP model group. ANP models were induced by injection of 50 g/L sodium taurocholate (4 mL/kg) under the pancreatic membrane. In the normal control group, the rats received isovolumetric injection of 9 g/L normal saline solution. The blood samples in each group were obtained via superior mesenteric vein for measuring IL-2, IL-10 and soluble Fas. The levels of IL-2, IL-10 and soluble Fas were determined by ELISA. The severity of lung injury was evaluated by pathologic score. The expression of Fas in lung was measured by immunohistochemistry.

RESULTS

In the ANP model group, levels of serum IL-2 were significantly higher than those of control group (P < 0.01), and peaked at 6 hours; levels of serum IL-10 were significantly higher than those of control group at 6 and 12 hours (P < 0.01); the ratios of IL-2/IL-10 were significantly higher than those of control group at 0.5 hours and 2 hours, however, they were significantly lower than those of control group at 6 hours, (P < 0.01), and returned to the normal level (P > 0.05). In Fas/APO-1 assay, there was no significant difference between the two groups. The pathological changes were aggravated significantly in model group compared with the control group. Immunohistochemistry stain showed Fas expression was absent in normal pulmonary tissue, whereas in pulmonary tissue Fas expression gradually increased 0.5 hours after induction of pancreatitis, and reached their peaks at 12 hours.

CONCLUSIONS

Fas are involved in the pathogenesis of pancreatitis associated lung injury, the mechanism might be related to the Fas mediated T helper cell apoptosis.

Dynamic changes of IL-2/IL-10, sFas and expression of Fas in intestinal mucosa in rats with acute necrotizing pancreatitis

AIM: To investigate dynamic changes of serum IL-2, IL-10, IL-2/IL-10 and sFas in rats with acute necrotizing pancreatitis. To explore the expression of Fas in intestinal mucosa of rats with acute necrotizing pancreatitis (ANP).

METHODS: A total of 64 Sprague-Dawley (SD) rats were randomly divided into two groups: normal control group (C group), ANP group (P group). An ANP model was induced by injection of 50 g/L sodium taurocholate under the pancreatic membrane. Normal control group received isovolumetric injection of 9 g/L physiological saline solution using the same method. The blood samples of the rats in each group were obtained via superior mesenteric vein to measure levels of IL-2, IL-10, sFas and calculate the value of IL-2/IL-10. The levels of IL-2, IL-10 and sFas were determined by ELISA. The severity of intestinal mucosal injury was evaluated by pathologic score. The expression of Fas in intestinal mucosal tissue was determined by immunohistochemistry staining.

RESULTS: Levels of serum IL-2 were significantly higher in P group than those of C group (2.79 ± 0.51 vs 3.53 ± 0.62, 2.93 ± 0.89 vs 4.35 ± 1.11, 4.81 ± 1.23 vs 6.94 ± 1.55 and 3.41 ± 0.72 vs 4.80 ± 1.10, respectively, P < 0.01, for all) and its reached peak at 6 h. Levels of serum IL-10 were significantly higher in P group than those of C group at 6 h and 12 h (54.61 ± 15.81 vs 47.34 ± 14.62, 141.15 ± 40.21 vs 156.12 ± 43.10, 89.18 ± 32.52 vs 494.98 ± 11.23 and 77.15 ± 22.60 vs 93.28 ± 25.81, respectively, P < 0.01, for all). The values of IL-2/IL-10 were higher significantly in P group than those of C group at 0.5 h and 2 h (0.05 ± 0.01 vs 0.07 ± 0.02 and 0.02 ± 0.01 vs 0.03 ± 0.01, respectively, P < 0.01, for all), and it were significantly lower than those of C group at 6 h (0.05 ± 0.02 vs 0.01 ± 0.01, P < 0.01) and returned to the control level at 12 h (0.04 ± 0.01 vs 0.05 ± 0.02, P > 0.05). In sFas assay, there was no significant difference between P group and C group (3.16 ± 0.75 vs 3.31 ± 0.80, 4.05 ± 1.08 vs 4.32 ± 1.11, 5.93 ± 1.52 vs 5.41 ± 1.47 and 4.62 ± 1.23 vs 4.44 ± 1.16, respectively, P > 0.05, for all). Comparison of P group and C group, the pathological changes were aggravated significantly in P group. Immunohistochemistry staining show the expression of Fas was absent in normal intestinal tissues, however, it gradually increased after induction of pancreatitis in intestinal tissue, then reached their peaks at 12 h.

CONCLUSION: Fas were involved in the pathogenesis of pancreatitis associated intestinal injury. The mechanisms of Fas may be associated to Fas mediated T helper cell apoptosis.

Reduction of peroxisome proliferation-activated receptor gamma expression by gamma-irradiation as a mechanism contributing to inflammatory response in rat colon: modulation by the 5-aminosalicylic acid agonist

Radiation-induced intestinal injuries, including inflammation and immune response, remain a limiting factor in the effectiveness of pelvic radiotherapy and in the patient's quality of life during and after treatment. Peroxisome proliferation-activated receptor (PPAR) agonists are now emerging as therapeutic drugs for various inflammatory diseases that are characterized by impaired PPAR expression. The purpose of this study was to investigate the profile of PPAR expression in rat colonic mucosa 3 and 7 days after abdominal gamma-irradiation (10 Gy). We tested whether irradiation-induced acute inflammatory response could be modulated pharmacologically with the antiinflammatory properties of 5-aminosalicylic acid (5-ASA) (250 mg/kg/day), which is a PPAR activator. Irradiation drastically reduced mRNA and protein levels of PPARalpha and -gamma and of the heterodimer retinoid X receptor (RXR)alpha at 3 days postirradiation. 5-ASA treatment normalized both PPARgamma and RXRalpha expression at 3 days postirradiation and PPARalpha at 7 days. By promoting PPAR expression and its nuclear translocation, 5-ASA interfered with the nuclear factor (NF)-kappaB pathway, both by reducing irradiation-induced NF-kappaB p65 translocation/activation and increasing the expression of nuclear factor-kappaB inhibitor (IkappaB) mRNA and protein. Therefore, 5-ASA prevents irradiation-induced inflammatory processes as well as expression of tumor necrosis factor alpha, monocyte chemotactic protein-1, inducible nitric-oxide synthase, and macrophage infiltration. In addition, 5-ASA restores the interferon gamma/signal transducer and activator of transcription (STAT)-1 and STAT-3 concentrations that were impaired at 3 and 7 days postirradiation and are correlated with suppressor of cytokine signaling-3 repression. Collectively, these results indicate that PPAR agonists may be effective in the prevention of inflammatory processes and immune responses during and after pelvic radiotherapy.

Maintenance of radiation-induced intestinal fibrosis: cellular and molecular features

Recent advances in cell and molecular radiobiology clearly showed that tissue response to radiation injury cannot be restricted to a simple cell-killing process, but depends upon continuous and integrated pathogenic processes, involving cell differentiation and crosstalk between the various cellular components of the tissue within the extracellular matrix. Thus, the prior concept of primary cell target in which a single-cell type (whatever it's epithelial or endothelial cells) dictates the whole tissue response to radiation injury has to be replaced by the occurrence of coordinated multicellular response that may either lead to tissue recovery or to sequel development. In this context, the present review will focus on the maintenance of the radiation-induced wound healing and fibrogenic signals triggered by and through the microenvironment toward the mesenchymal cell compartment, and will highlight how sequential and sustained modifications in cell phenotypes will in cascade modify cell-to-cell interactions and tissue composition.