Role of P-selectin in radiation-induced intestinal inflammatory damage

Surface Decoration via Physical Interaction of Cupric Diethyldithiocarbamate Nanocrystals and Its Impact on Biodistribution and Tumor Targeting

The vascular wall is the first physiologic barrier that circulating nanoparticles (NPs) encounter, which also is a key biological barrier to cancer drug delivery. NPs can continually scavenge the endothelium for biomarkers of cancer, and the chance of NPs' extravasation into the tumors can be enhanced. Here, we envision P-selectin as a target for specific delivery of drug nanocrystals to tumors. The cupric diethyldithiocarbamate nanocrystals (CuET NCs) were first prepared by an antisolvent method, and then nanocrystals were coated with fucoidan via physical interaction. The fucoidan-coated CuET nanocrystals (CuET@Fuc) possess high drug loading and have the ability to interact with human umbilical vein endothelial cells expressing P-selectin, which transiently enhances the endothelial permeability and facilitates CuET@Fuc extravasation from the peritumoral vascular to achieve higher tumor accumulation of drugs than bare CuET NCs. The CuET NC shows poorer anticancer efficacy than CuET@Fuc at the same dose of CuET. Upon repeated dosing of CuET@Fuc for 2 weeks, no mortality was observed in treated melanoma-bearing mice, while the mortality in the control group and excipient-treated groups reached 23%. The growth rate of melanoma in the CuET@Fuc-treated group was significantly lower than those in other groups. Furthermore, an acute toxicity study revealed that CuET@Fuc is a safe formulation for cancer treatment.

Fucoidan-coated nanoparticles target radiation-induced P-selectin to enhance chemoradiotherapy in murine colorectal cancer

Colorectal cancer (CRC) is a leading cause of cancer-related death for both men and women, highlighting the need for new treatment strategies. Advanced disease is often treated with a combination of radiation and cytotoxic agents, such as DNA damage repair inhibitors and DNA damaging agents. To optimize the therapeutic window of these multimodal therapies, advanced nanomaterials have been investigated to deliver sensitizing agents or enhance local radiation dose deposition. In this study, we demonstrate the feasibility of employing an inflammation targeting nanoscale metal-organic framework (nMOF) platform to enhance CRC treatment. This novel formulation incorporates a fucoidan surface coating to preferentially target P-selectin, which is over-expressed or translocated in irradiated tumors. Using this radiation stimulated delivery strategy, a combination PARP inhibitor (talazoparib) and chemotherapeutic (temozolomide) drug-loaded hafnium and 1,4-dicarboxybenzene (Hf-BDC) nMOF was evaluated both in vitro and in vivo. Significantly, these drug-loaded P-selectin targeted nMOFs (TT@Hf-BDC-Fuco) show improved tumoral accumulation over multiple controls and subsequently enhanced therapeutic effects. The integrated radiation and nanoformulation treatment demonstrated improved tumor control (reduced volume, density, and growth rate) and increased survival in a syngeneic CRC mouse model. Overall, the data from this study support the continued investigation of radiation-priming for targeted drug delivery and further consideration of nanomedicine strategies in the clinical management of advanced CRC.

Biomarkers of radiation-induced vascular injury

OBJECTIVE

Cancer survivorship has thrown the spotlight on the incidence of nonmalignant chronic diseases in cancer patients. Endothelial injury is increasingly recognized as a consequence of cancer treatment, particularly after radiation therapy (RT). This review is to provide a current understanding on the pathophysiological mechanisms and predictive biomarkers of radiation-induced vascular injury.

RECENT FINDINGS

Radiation directly impacts vasculature by causing endothelial apoptosis and senescence, and alterations in normal homeostasis. This altered milieu at the endothelial surface may contribute to a systemic chronic inflammatory state that is superimposed upon the cascade of normal senescence processes leading to acceleration of age-related disorders, atherosclerosis, and chronic fibrosis. Vasculature imaging, blood-based or cell-component biomarkers, and signatures of genomics, proteomics, metabolomics, and radiomics are potential tools for detection of vascular damage after irradiation.

CONCLUSIONS

Development of a valid prediction model by combining an array of imaging tools, blood-based biomarkers, coupled with novel predictors like exosomes and metabolic degradation products can serve to identify RT-induced vascular injury early for subsequent introduction of newer therapeutic approaches to counter radiation morbidity.

Quinic Acid-Conjugated Nanoparticles Enhance Drug Delivery to Solid Tumors via Interactions with Endothelial Selectins

Current nanoparticle (NP) drug carriers mostly depend on the enhanced permeability and retention (EPR) effect for selective drug delivery to solid tumors. However, in the absence of a persistent EPR effect, the peritumoral endothelium can function as an access barrier to tumors and negatively affect the effectiveness of NPs. In recognition of the peritumoral endothelium as a potential barrier in drug delivery to tumors, poly(lactic-co-glycolic acid) (PLGA) NPs are modified with a quinic acid (QA) derivative, synthetic mimic of selectin ligands. QA-decorated NPs (QA-NP) interact with human umbilical vein endothelial cells expressing E-/P-selectins and induce transient increase in endothelial permeability to translocate across the layer. QA-NP reach selectin-upregulated tumors, achieving greater tumor accumulation and paclitaxel (PTX) delivery than polyethylene glycol-decorated NPs (PEG-NP). PTX-loaded QA-NP show greater anticancer efficacy than Taxol or PTX-loaded PEG-NP at the equivalent PTX dose in different animal models and dosing regimens. Repeated dosing of PTX-loaded QA-NP for two weeks results in complete tumor remission in 40-60% of MDA-MB-231 tumor-bearing mice, while those receiving control treatments succumb to death. QA-NP can exploit the interaction with selectin-expressing peritumoral endothelium and deliver anticancer drugs to tumors to a greater extent than the level currently possible with the EPR effect.

HIF-1α Deletion in the Endothelium, but Not in the Epithelium, Protects From Radiation-Induced Enteritis

BACKGROUND & AIMS

Radiation therapy in the pelvic area is associated with side effects that impact the quality of life of cancer survivors. Interestingly, the gastrointestinal tract is able to adapt to significant changes in oxygen availability, suggesting that mechanisms related to hypoxia sensing help preserve tissue integrity in this organ. However, hypoxia-inducible factor (HIF)-dependent responses to radiation-induced gut toxicity are unknown. Radiation-induced intestinal toxicity is a complex process involving multiple cellular compartments. Here, we investigated whether epithelial or endothelial tissue-specific HIF-1α deletion could affect acute intestinal response to radiation.

METHODS

Using constitutive and inducible epithelial or endothelial tissue-specific HIF-1α deletion, we evaluated the consequences of epithelial or endothelial HIF-1α deletion on radiation-induced enteritis after localized irradiation. Survival, radiation-induced tissue injury, molecular inflammatory profile, tissue hypoxia, and vascular injury were monitored.

RESULTS

Surprisingly, epithelium-specific HIF-1α deletion does not alter radiation-induced intestinal injury. However, irradiated VECad-Cre^+/-HIF-1α^FL/FL mice present with lower radiation-induced damage, showed a preserved vasculature, reduced hypoxia, and reduced proinflammatory response compared with irradiated HIF-1α^FL/FL mice.

CONCLUSIONS

We demonstrate in vivo that HIF-1α impacts radiation-induced enteritis and that this role differs according to the targeted cell type. Our work provides a new role for HIF-1α and endothelium-dependent mechanisms driving inflammatory processes in gut mucosae. Results presented show that effects on normal tissues have to be taken into account in approaches aiming to modulate hypoxia or hypoxia-related molecular mechanisms.

Blockage of caspase-1 activation ameliorates bone marrow inflammation in mice after hematopoietic stem cell transplantation

Conditioning regimens before hematopoietic stem cell transplantation (HSCT), cause damage to bone marrow and inflammation. Whether inflammasomes are involved in bone marrow inflammation remains unclear. The study aims to evaluate the role of inflammasomes in bone marrow inflammation after HSCT. On days 7, 14, 21 and 28 after HSCT, mice were sacrificed for analysis of bone marrow inflammation, pro-inflammatory cytokines secretion, inflammasomes expression and caspase-1 activation. Bone marrow inflammation with neutrophils and macrophages infiltration was observed after HSCT. Secretion of IL-1β, IL-18, TNF-α and IL-6 were elevated, with increased caspase-1 activation and inflammasomes expression. Caspase-1 inhibitor administration after HSCT significantly reduced infiltration of neutrophils and macrophages into bone marrow and increased the numbers of megakaryocytes and platelets. In conclusion, inflammasomes activation is involved in bone marrow inflammation after HSCT and caspase-1 inhibition attenuates bone marrow inflammation and promoted hematopoietic reconstitution, suggesting targeting caspase-1 might be beneficial for improving HSCT outcomes.

New model for long-term investigations of cutaneous microcirculatory and inflammatory changes following irradiation

Radiotherapy is used for curative and palliative treatment. However, its negative effect on normal tissue is a limiting factor for the deliverable dose. Microcirculatory breakdown and prolonged inflammation in particular are major features of late side effects. The purpose of this study was to develop a reliable animal model that will allow a long-term in vivo analysis of microcirculation and inflammation following irradiation. A single dose of 90 Gy was delivered to the ears of hairless mice (n = 15). Intravital fluorescent microscopy was used to assess microcirculatory parameters and leukocyte behaviour. Values for the identical (control) areas were obtained before as well as during the following days, weeks and months following irradiation. The arteriolar and venular diameter increased up to Day 14, decreased during the following months, and increased again after one year. The red blood cell velocity increased up to 145% on Day 3, decreased on Day 7 to 115%, and stayed above baseline value the whole year. The integrity loss of the endothelium increased up to Day 7 and continued up to Day 75 after radiation. After one year, the oedema was at the baseline level. Leukocytes showed their maximal activity at one year after trauma. An increase was measured up to Day 25; the lowest values were measured at Day 40 post-irradiation, followed by a repeated increase. The present model allows a certain visualization of microcirculatory disturbances and inflammation over a period of months. This permits the possibility of long-term investigations of the underlying pathophysiology following irradiation, including possible drug interactions.

Gut microbiota and inflammation

Systemic and local inflammation in relation to the resident microbiota of the human gastro-intestinal (GI) tract and administration of probiotics are the main themes of the present review. The dominating taxa of the human GI tract and their potential for aggravating or suppressing inflammation are described. The review focuses on human trials with probiotics and does not include in vitro studies and animal experimental models. The applications of probiotics considered are systemic immune-modulation, the metabolic syndrome, liver injury, inflammatory bowel disease, colorectal cancer and radiation-induced enteritis. When the major genomic differences between different types of probiotics are taken into account, it is to be expected that the human body can respond differently to the different species and strains of probiotics. This fact is often neglected in discussions of the outcome of clinical trials with probiotics.

Irradiation induces regionally specific alterations in pro-inflammatory environments in rat brain

PURPOSE

Pro-inflammatory environments in the brain have been implicated in the onset and progression of neurological disorders. In the present study, we investigate the hypothesis that brain irradiation induces regionally specific alterations in cytokine gene and protein expression.

MATERIALS AND METHODS

Four month old F344 x BN rats received either whole brain irradiation with a single dose of 10 Gy gamma-rays or sham-irradiation, and were maintained for 4, 8, and 24 h following irradiation. The mRNA and protein expression levels of pro-inflammatory mediators were analysed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence staining. To elucidate the molecular mechanisms of irradiation-induced brain inflammation, effects of irradiation on the DNA-binding activity of pro-inflammatory transcription factors were also examined.

RESULTS

A significant and marked up-regulation of mRNA and protein expression of pro-inflammatory mediators, including tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and monocyte chemoattractant protein-1 (MCP-1), was observed in hippocampal and cortical regions isolated from irradiated brain. Cytokine expression was regionally specific since TNF-alpha levels were significantly elevated in cortex compared to hippocampus (57% greater) and IL-1beta levels were elevated in hippocampus compared to cortical samples (126% greater). Increases in cytokine levels also were observed after irradiation of mouse BV-2 microglial cells. A series of electrophoretic mobility shift assays (EMSA) demonstrated that irradiation significantly increased activation of activator protein-1 (AP-1), nuclear factor-kappaB (NF-kappaB), and cAMP response element-binding protein (CREB).

CONCLUSION

The present study demonstrated that whole brain irradiation induces regionally specific pro-inflammatory environments through activation of AP-1, NF-kappaB, and CREB and overexpression of TNF-alpha, IL-1beta, and MCP-1 in rat brain and may contribute to unique pathways for the radiation-induced impairments in tissue function.

Predicting and monitoring colitis development in mice by micro-computed tomography

BACKGROUND

Computed tomography (CT) has been developed as a tool for monitoring human inflammatory bowel disease (IBD). The aim of this study was to evaluate colon wall thickness as a noninvasive marker in the dextran sodium sulfate (DSS) mouse model of colitis using micro-CT.

METHODS

Mice were examined by micro-CT 1, 2, or 4 times between day 0 (d0) and d26 after induction of colitis to document the kinetics of changes in colon wall thickness and its relation to colitis development.

RESULTS

DSS-treated mice displayed a significantly thicker colon wall at all timepoints (days 5, 8, 12, 19, and 26) investigated compared to healthy controls. Colon wall thickness showed a good correlation to the macroscopic grading of colitis (r = 0.81). The increase in colon wall thickness occurred mainly during the acute phase of colitis (between days 5 and 12) and did not progress much further in the chronic phase of colitis (d26). Colon wall thickness at d26 was thereby predicted by measurements at d12. All mice did not respond equally to DSS and this difference was manifest during the first 2 weeks of colitis, providing an important tool in stratifying responders from nonresponders.

CONCLUSIONS

While the potential impact of handling and anesthesia should be considered on repeated micro-CT, irradiation exposure during repeated micro-CT did not affect the development of colitis. Thus, the results suggest that micro-CT can be used for monitoring and prediction of the inflammatory response in mouse colitis in future therapeutic studies.

Local radiotherapy of exposed murine small bowel: apoptosis and inflammation

Background

Preoperative radiotherapy of the pelvic abdomen presents with complications mostly affecting the small bowel. The aim of this study was to define the features of early radiation-induced injury on small bowel.

Methods

54 mice were divided into two groups (36 irradiated and 18 sham irradiated). Animals were placed on a special frame and (in the radiated group) the exteriorized segment of ileum was subjected to a single absorbed dose of 19 or 38 Gy radiation using 6 MV high energy photons. Specimens were collected for histology, immunohistochemistry (IHC) and ELISA analysis after 2, 24 and 48 hours. Venous blood was collected for systemic leucocyte count in a Burker chamber.

Results

Histology demonstrated progressive infiltration of inflammatory cells with cryptitis and increased apoptosis. MIP-2 (macrophage inflammatory protein) concentration was significantly increased in irradiated animals up to 48 hours. No significant differences were observed in IL-10 (interleukin) and TNF-α (tumour necrosis factor) levels. IHC with CD45 showed a significant increase at 2 hours of infiltrating leucocytes and lymphocytes after irradiation followed by progressive decrease with time. Caspase-3 expression increased significantly in a dose dependent trend in both irradiated groups up to 48 hours.

Conclusion

Acute small bowel injury caused by local irradiation is characterised by increased apoptosis of crypt epithelial cells and by lymphocyte infiltration of the underlying tissue. The severity of histological changes tends to be dose dependent and may affect the course of tissue damage.

Critical role of P-selectin and lymphocyte function antigen-1 in radiation-induced leukocyte-endothelial cell interactions in the colon

PURPOSE

Radiation therapy is frequently used in treating different types of tumors, although associated with serious side effects, such as fibrosis and complicated diarrhea. This study was designed to define the adhesive mechanisms behind radiotherapy-induced leukocyte recruitment in the colon.

METHODS

All mice, except control animals, were radiated with a single dose of 20 Gy. Mice were pretreated with an isotype-matched control antibody or a monoclonal antibody directed against P-selectin. In separate experiments, lymphocyte function antigen-1-deficient animals were used. Leukocyte rolling and firm adhesion were determined by use of inverted intravital fluorescence microscopy 16 hours after radiation.

RESULTS

It was found that immunoneutralization of P-selectin reduced leukocyte rolling by 83 percent and adhesion by 87 percent in radiated mice. Moreover, radiation-induced leukocyte adhesion in LFA-1-deficient mice was decreased by 94 percent compared with wild-type animals.

CONCLUSIONS

This study demonstrates that leukocyte rolling is mediated by P-selectin and that firm leukocyte adhesion is supported by lymphocyte function antigen-1 in radiation-induced enteritis. Moreover, P-selectin-dependent leukocyte rolling is a precondition for subsequent leukocyte adhesion in radiation-induced intestinal injury. Thus, targeting P-selectin and/or lymphocyte function antigen-1 may protect against pathologic inflammation in the colon induced by radiotherapy.

Thrombotic molecule expression in cerebral vascular malformations

Thrombosis is an important end-point in the obliteration of vascular malformations after radiosurgery. The aim of this study was to investigate the expression of thrombotic molecules in arteriovenous malformations (AVMs) and cavernous malformations (CMs), and in AVMs after radiosurgery. Fresh-frozen surgical specimens from 18 AVMs (including three that had previously been treated with radiosurgery), seven CMs, and three control specimens were studied. The expression of tissue factor, thrombomodulin and von Willebrand factor (vWF) were examined using immunofluorescence. Thrombomodulin and vWF were expressed in the endothelium of all specimens, while tissue factor was predominately found in the perivascular region and vascular adventitia. Previous treatment of AVMs with either radiation or embolisation did not significantly alter the intensity of expression. In some irradiated lesions, vessels were found with absent endothelial vWF staining and exposed tissue factor. This study has demonstrated that loss of the endothelium and exposure of underlying tissue factor occurs in irradiated AVMs. There were no significant differences in the expression of these thrombotic molecules in vascular malformations when compared to control vessels. While no long-term alterations in antigen expression were observed after radiosurgery, further work may elucidate the nature of the immediate response to irradiation.

Radiation-induced intestinal inflammation

Radiation induces an important inflammatory response in the irradiated organs, characterized by leukocyte infiltration and vascular changes that are the main limiting factor in the application of this therapeutic modality for the treatment of cancer. Recently, a considerable investigative effort has been directed at determining the molecular mechanisms by which radiation induces leukocyte recruitment, in order to create strategies to prevent intestinal inflammatory damage. In these review, we consider current available evidence on the factors governing the process of leukocyte recruitment in irradiated organs, mainly derived from experimental studies, with special attention to adhesion molecules, and their value as therapeutic targets.

Adhesion molecules in radiotherapy

Recent studies have documented changes in adhesion molecule expression and function after exposure to ionizing radiation. Adhesion molecules mediate cell-cell and cell-matrix interactions and are essential for a variety of physiological and pathological processes including maintenance of normal tissue integrity as well as tumor development and progression. Consequently, modulation of adhesion molecules by radiation may have a role in radiation-induced tumor control and normal tissue damage by interfering with cell signaling, radioresistance, metastasis, angiogenesis, carcinogenesis, immune response, inflammation and fibrosis. In addition, the interactions of radiation with adhesion molecules could have a major impact in developing new strategies to increase the efficacy of radiation therapy. Remarkable progress has been made in recent years to design targeted drug delivery to radiation-up-regulated adhesion molecules. Furthermore, the inhibition of adhesion, migration, invasion and angiogenesis by blocking adhesion receptors may represent a new therapeutic approach to improve tumor control and decrease radiation toxicity. This review is focused on current data concerning the mechanistic interactions of radiation with adhesion molecules and the possible clinical-pathological implications in radiotherapy.

Influence of endothelial cells on vascular smooth muscle cells phenotype after irradiation: implication in radiation-induced vascular damages

Damage to vessels is one of the most common effects of therapeutic irradiation on normal tissues. We undertook a study in patients treated with preoperative radiotherapy and demonstrated in vivo the importance of proliferation, migration, and fibrogenic phenotype of vascular smooth muscle cells (VSMCs) in radiation-induced vascular damage. These lesions may result from imbalance in the cross talk between endothelial cells (ECs) and VSMCs. Using co-culture models, we examined whether ECs influence proliferation, migration, and fibrogenic phenotype of VSMCs. In the presence of irradiated ECs, proliferation and migration of VSMCs were increased. Moreover, expressions of alpha-smooth muscle actin, connective tissue growth factor, plasminogen activator inhibitor type 1, heat shock protein 27, and collagen type III, alpha 1 were up-regulated in VSMCs exposed to irradiated ECs. Secretion of transforming growth factor (TGF)-beta1 was increased after irradiation of ECs, and irradiated ECs activated the Smad pathway in VSMCs by inducing Smad3/4 nuclear translocation and Smad-dependent promoter activation. Using small interferring RNA targeting Smad3 and a TGFbeta-RII neutralizing antibody, we demonstrate that a TGF-beta1/TGF-beta-RII/Smad3 pathway is involved in the fibrogenic phenotype of VSMCs induced by irradiated ECs. In conclusion, we show the importance of proliferation, migration, and fibrogenic phenotype of VSMCs in patients. Moreover, we demonstrate in vitro that ECs influence these fundamental mechanisms involved in radiation-induced vascular damages.

Transfection of antisense core 2 beta1,6-N-acetylglucosaminyltransferase-1 cDNA suppresses selectin ligand expression and tissue infiltration of B-cell precursor leukemia cells

B-cell precursor (BCP) leukemia cells infiltrate into peripheral organs and the disease often relapses. Inhibition of tissue infiltration may improve the treatment outcome of BCP-leukemia patients. Selectin ligand has been suggested to play an important role in the infiltration of leukemia cells. However, the regulation mechanisms and involvement in tissue infiltration of selectin ligand expression in BCP-leukemia cells are not fully understood. In this study, we report that BCP-leukemia cells express selectin ligand on O-sialoglycoproteins. Core 2 beta1,6-N-acetylglucosaminyltransferase-1 (C2GnT-1) is mainly expressed in BCP-leukemia cells. Transfection of the antisense C2GnT-1 cDNA resulted in a significant reduction of either selectin ligand expression or selectin-dependent cell adhesion in BCP-leukemia cell line KM3 cells. Migration ability into mouse peripheral organs was reduced significantly in the antisense transfectant. These findings suggest that C2GnT-1 regulates selectin ligand expression. Downregulation of the selectin ligand expression level inhibits tissue infiltration of BCP-leukemia cells. C2GnT-1 may be a candidate of therapeutic target for the inhibition of infiltration of leukemia cells.

P-selectin mediates leukocyte rolling in concanavalin-A-induced hepatitis

Concanavalin-A (Con-A)-induced hepatitis is an experimental model of human autoimmune hepatitis characterized by leukocyte activation and infiltration of the liver. The aim of the present study was to evaluate the role of P-selectin on leukocyte-endothelial interactions within the hepatic microvasculature in response to Con-A.

METHODS

The study was performed in P-selectin-deficient mice and wild-type mice pretreated with anti-P-selectin blocking monoclonal antibody (mAb) or vehicle. After 2 h of Con-A (20 mg/kg i.v.) or PBS administration, leukocyte rolling and adhesion and the index of sinusoidal perfusion were evaluated using the intravital microscopy technique in the liver. Apoptosis was determined by flow cytometry analysis of caspase-3 activity assayed on freshly isolated hepatocytes.

RESULTS

Con-A induced a significant increase in leukocyte rolling, mainly located at the central venule (2.1+/-0.4 vs 0.6+/-0.2 cells/min in wild-type mice treated with vehicle) and less marked, but still significant, in portal venules. This was associated with a significant increase in leukocyte adhesion. In P-selectin-deficient mice treated with Con-A, leukocyte rolling in portal and central venules was markedly reduced. However, leukocyte adhesion was only partially attenuated. A few sinusoids were perfused in wild-type mice treated with Con-A (26%). The percentage of perfused sinusoids was significantly higher in P-selectin-deficient mice (45%; P<0.05 vs wild-type). Similar effects were noted after the simultaneous injection of Con-A and anti-P-selecting mAb in wild-type mice. After Con-A treatment, apoptosis was markedly reduced in isolated hepatocytes of P-selectin-deficent mice (37+/-7% vs 75+/-5% in wild type).

CONCLUSION

The results of this intravital microscopy study clearly demonstrate that P-selectin is involved in the initial leukocyte rolling that leads to the development of Con-A-induced liver injury.

Protective effect of superoxide dismutase in radiation-induced intestinal inflammation

PURPOSE

To analyze the therapeutic value of Cu/Zn-superoxide dismutase (SOD1) supplementation in an experimental model of radiation-induced intestinal inflammation and explore its mechanistic effects.

METHODS AND MATERIALS

Mice were subjected to abdominal irradiation with 10 Gy or sham irradiation and studied 24 or 72 hours after radiation. Groups of mice were treated with 0.1, 4, or 6 mg/kg/day of SOD1 or vehicle. Leukocyte-endothelial cell interactions in intestinal venules were assessed by intravital microscopy. Endothelial intercellular adhesion molecule-1 (ICAM-1) expression was determined with radiolabeled antibodies. Effects of SOD1 on histologic damage and levels of lipid hydroperoxides were also measured.

RESULTS

A significant increase in the flux of rolling leukocytes and number of firmly adherent leukocytes in intestinal venules was observed at 24 and 72 hours after irradiation. Treatment with SOD1 had no effect on leukocyte rolling but significantly and dose-dependently decreased firm leukocyte adhesion to intestinal venules. Treatment with SOD1 at doses that reduced leukocyte recruitment abrogated the increase in hydroperoxides in intestinal tissue and ICAM-1 upregulation in intestinal endothelial cells. The inflammatory score, but not a combined histology damage score, was also significantly reduced by SOD1.

CONCLUSIONS

Treatment with SOD1 decreases oxidative stress and adhesion molecule upregulation in response to abdominal irradiation. This is associated with an attenuation of the radiation-induced intestinal inflammatory response.

Protective effect of superoxide dismutase in radiation-induced intestinal inflammation

PURPOSE

To analyze the therapeutic value of Cu/Zn-superoxide dismutase (SOD1) supplementation in an experimental model of radiation-induced intestinal inflammation and explore its mechanistic effects.

METHODS AND MATERIALS

Mice were subjected to abdominal irradiation with 10 Gy or sham irradiation and studied 24 or 72 hours after radiation. Groups of mice were treated with 0.1, 4, or 6 mg/kg/day of SOD1 or vehicle. Leukocyte-endothelial cell interactions in intestinal venules were assessed by intravital microscopy. Endothelial intercellular adhesion molecule-1 (ICAM-1) expression was determined with radiolabeled antibodies. Effects of SOD1 on histologic damage and levels of lipid hydroperoxides were also measured.

RESULTS

A significant increase in the flux of rolling leukocytes and number of firmly adherent leukocytes in intestinal venules was observed at 24 and 72 hours after irradiation. Treatment with SOD1 had no effect on leukocyte rolling but significantly and dose-dependently decreased firm leukocyte adhesion to intestinal venules. Treatment with SOD1 at doses that reduced leukocyte recruitment abrogated the increase in hydroperoxides in intestinal tissue and ICAM-1 upregulation in intestinal endothelial cells. The inflammatory score, but not a combined histology damage score, was also significantly reduced by SOD1.

CONCLUSIONS

Treatment with SOD1 decreases oxidative stress and adhesion molecule upregulation in response to abdominal irradiation. This is associated with an attenuation of the radiation-induced intestinal inflammatory response.

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.

Radiation enteropathy and leucocyte-endothelial cell reactions in a refined small bowel model

BACKGROUND

Leucocyte recruitment and inflammation are key features of high dose radiation-induced tissue injury. The inflammatory response in the gut may be more pronounced following radiotherapy due to its high bacterial load in comparison to the response in other organs. We designed a model to enable us to study the effects of radiation on leucocyte-endothelium interactions and on intestinal microflora in the murine ileum. This model enables us to study specifically the local effects of radiation therapy.

METHOD

A midline laparotomy was performed in male C57/Bl6 mice and a five-centimetre segment of ileum is irradiated using the chamber. Leucocyte responses (rolling and adhesion) were then analysed in ileal venules 2 - 48 hours after high dose irradiation, made possible by an inverted approach using intravital fluorescence microscopy. Furthermore, intestinal microflora, myeloperoxidase (MPO) and cell histology were analysed.

RESULTS

The highest and most reproducible increase in leucocyte rolling was exhibited 2 hours after high dose irradiation whereas leucocyte adhesion was greatest after 16 hours. Radiation reduced the intestinal microflora count compared to sham animals with a significant decrease in the aerobic count after 2 hours of radiation. Further, the total aerobic counts, Enterobacteriaceae and Lactobacillus decreased significantly after 16 hours. In the radiation groups, the bacterial count showed a progressive increase from 2 to 24 hours after radiation.

CONCLUSION

This study presents a refinement of a previous method of examining mechanisms of radiation enteropathy, and a new approach at investigating radiation induced leucocyte responses in the ileal microcirculation. Radiation induced maximum leucocyte rolling at 2 hours and adhesion peaked at 16 hours. It also reduces the microflora count, which then starts to increase steadily afterwards. This model may be instrumental in developing strategies against pathological recruitment of leucocytes and changes in intestinal microflora in the small bowel after radiotherapy.

The role of CCL3/macrophage inflammatory protein-1α in experimental colitis

CCL3/macrophage inflammatory protein (MIP-1)-1alpha is elevated in the rectal biopsies of patients with active inflammatory bowel diseases, but its role remains undefined. The present study examined the role of CCL3/MIP-1alpha during trinitrobenzene sulfonic acid (TNBS)-induced colitis in the rat. Colonic CCL3/MIP-1alpha levels were elevated (>20-fold above control) within 24 h and remained elevated to day 7 of colitis induction by TNBS administration. In addition, significant increases in colonic neutrophil accumulation were observed within 24 h to day 7 of TNBS treatment. Pre-treatment of rats with a single dose of CCL3/MIP-1alpha antibody significantly reduced (47%) colonic neutrophil accumulation during the early (24 h) phase of TNBS-induced colitis. In contrast, chronic (repeated) administration of CCL3/MIP-1alpha antibody did not attenuate colonic neutrophil accumulation during the late phase (day 7) of TNBS-induced colitis. These results suggest a role for CCL3/MIP-1alpha in promoting colonic neutrophil accumulation during the early (24 h) phase of TNBS-induced colitis.

Gene deletion of P-Selectin and ICAM-1 does not inhibit neutrophil infiltration into peritoneal cavity following cecal ligation-puncture

Background

Neutrophil infiltration is one of the critical cellular components of an inflammatory response during peritonitis. The adhesion molecules, P-selectin and intercellular adhesion molecule (ICAM)-1, mediate neutrophil-endothelial cell interactions and the subsequent neutrophil transendothelial migration during the inflammatory response. Despite very strong preclinical data, recent clinical trials failed to show a protective effect of anti-adhesion therapy, suggesting that the length of injury might be a critical factor in neutrophil infiltration. Therefore, the objective of this study was to determine the role of P-selectin and ICAM-1 in neutrophil infiltration into the peritoneal cavity during early and late phases of peritonitis.

Methods

Peritonitis was induced in both male wild-type and P-selectin/ICAM-1 double deficient (P/I null) mice by cecal ligation-puncture (CLP). Peripheral blood and peritoneal lavage were collected at 6 and 24 hours after CLP. The total leukocyte and neutrophil contents were determined, and neutrophils were identified with the aid of in situ immunohistochemical staining. Comparisons between groups were made by applying ANOVA and student t-test analysis.

Results

CLP induced a severe inflammatory response associated with a significant leukopenia in both wild-type and P/I null mice. Additionally, CLP caused a significant neutrophil infiltration into the peritoneal cavity that was detected in both groups of mice. However, neutrophil infiltration in the P/I null mice at 6 hours of CLP was significantly lower than the corresponding wild-type mice, which reached a similar magnitude at 24 hours of CLP. In contrast, in peritonitis induced by intraperitoneal inoculation of 2% glycogen, no significant difference in neutrophil infiltration was observed between the P/I null and wild-type mice at 6 hours of peritonitis.

Conclusions

The data suggest that alternative adhesion pathway(s) independent of P-selectin and ICAM-1 can participate in neutrophil migration during peritonitis and that the mode of stimuli and duration of the injury modulate the neutrophil infiltration.

Inflammatory reaction and changes in expression of coagulation proteins on lung endothelial cells after total-body irradiation in mice

Inflammatory reaction is a classical feature of radiation exposure, and pneumonitis is a dose-limiting complication in the handling of hematological disorders treated with total-body irradiation. In the present study, we first evaluated the inflammatory response in C57BL6/J mice exposed to lethal doses of gamma rays treated with antibiotics or not. Both interleukin 6 and KC (also known as Gro1) were increased in the plasma 10 to 18 days after radiation exposure, independent of bacterial infection, whereas fibrinogen release was linked to a bacterial infection. Furthermore, both Il6 and KC were increased in the lungs of irradiated mice. Our second objective was to characterize the endothelial cell changes in the lungs of total-body-irradiated mice. For this purpose, a quantitative RT-PCR was used to determine the expression of genes involved in inflammatory and coagulation processes. We found that the adhesion molecules P-selectin and platelet endothelial cell adhesion molecule 1 were up-regulated, whereas E-selectin remained unchanged. Tissue factor expression was up-regulated as well, and thrombomodulin gene expression was down-regulated. The investigation by immunohistochemistry of adhesion molecules confirmed the increase in the basal expression of both P-selectin and platelet endothelial cell adhesion molecule 1 on pulmonary endothelial cells. All together, our results suggest the involvement of endothelial cells in the development of radiation-induced inflammatory and thrombotic processes.

A statin-based inhibitor of lymphocyte function antigen-1 protects against ischemia/reperfusion-induced leukocyte adhesion in the colon

1. Statins are mainly used to control hypercholesterolemia; however, recent studies have also ascribed anti-inflammatory effects to the statins. LFA703 is a novel statin-derived compound, which potently inhibits lymphocyte function antigen-1 (LFA-1, CD11a/CD18) but does not affect HMG-CoA reductase activity. 2. The objective of this study was to examine the anti-inflammatory mechanisms of LFA703 in ischemia/reperfusion (I/R)-induced leukocyte-endothelium interactions in the colon. For this purpose, the superior mesenteric artery was occluded for 30 min and leukocyte responses were analyzed in colonic venules after 120 min of reperfusion in mice using inverted intravital fluorescence microscopy. 3. First, the inhibitory mechanisms of LFA703 on leukocyte adhesion were investigated in vitro using a mouse CD4+8+ thymocyte cell line. Immunoneutralization of LFA-1 and ICAM-1 abolished leukocyte adhesion, whereas inhibition of VLA-4 had no effect in this in vitro assay. Indeed, it was found that LFA703 dose-dependently reduced LFA-1-dependent leukocyte adhesion to mouse endothelial cells in vitro with an IC50 of 3.2 microm. 4. I/R caused an increase in leukocyte rolling and adhesion in colonic venules. Immunoneutralization of LFA-1 significantly reduced I/R-induced leukocyte adhesion by 89% in colonic venules. In contrast, I/R-provoked leukocyte rolling was insensitive to inhibition of LFA-1 function. 5. Administration of 30 mg kg-1 of LFA703 decreased reperfusion-induced leukocyte adhesion by more than 91%, while the level of leukocyte rolling was unchanged, suggesting that LFA703 effectively blocked LFA-1-dependent firm adhesion of leukocyte in the colon. However, LFA703 did not decrease the expression of LFA-1 on circulating leukocytes. 6. This study demonstrates that LFA-1 is indeed a critical adhesion molecule in mediating postischemic leukocyte adhesion in the colon. Moreover, this is the first study showing that a statin-based synthetic compound has the capacity to abolish LFA-1-dependent leukocyte adhesion in I/R. These novel findings may have great implications in the clinical treatment of conditions associated with I/R-induced tissue injury, such as organ transplantation, trauma and major surgery.

Relative roles of ICAM-1 and VCAM-1 in the pathogenesis of experimental radiation-induced intestinal inflammation

PURPOSE

Cell adhesion molecules mediate leukocyte recruitment into the irradiated organs; modulation of this process may protect from radiation damage. Our objective was to characterize the requirement for intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) in intestinal inflammatory response after abdominal irradiation.

METHODS AND MATERIALS

Endothelial ICAM-1 and VCAM-1 expression was determined using radiolabeled antibodies in mice 24 h and 14 days after irradiation with 10 Gy, or sham radiation. Leukocyte-endothelial cell interactions in intestinal venules were assessed using intravital microscopy, and the function of ICAM-1 and VCAM-1 in this process by using blocking antibodies and ICAM-1(-/-) mice.

RESULTS

The number of adherent leukocytes significantly increased 24 h after irradiation and remained elevated at 14 days. Treatment with anti-ICAM-1 antibodies and ICAM-1 genetic deficiency significantly reduced leukocyte adhesion 24 h after irradiation. At 14 days after irradiation, both wild-type and ICAM-1(-/-) mice had an upregulation of VCAM-1, expression, and VCAM-1 immunoneutralization, but not ICAM-1 immunoneutralization, significantly reduced leukocyte adhesion. In ICAM-1(-/-) mice, regeneration of the intestinal epithelium was enhanced relative to wild-type mice.

CONCLUSIONS

ICAM-1 plays a key role in leukocyte recruitment at early time points after abdominal irradiation, whereas VCAM-1 is the main molecular determinant of leukocyte recruitment at late time points.

P-selectin and P-selectin glycoprotein ligand 1 are major determinants for Th1 cell recruitment to nonlymphoid effector sites in the intestinal lamina propria

The recruitment of activated T cell subsets to sites of effector immune responses is mediated by homing receptors induced upon activation in secondary lymphoid tissue. Using an adoptive transfer model, the intestinal recruitment of CD4+ T cells activated with intraperitoneal antigen in complete Freund's adjuvant was examined. The data demonstrate that activated CD4+ T cells recruited to intestinal Peyer's patches (PP) and lamina propria (LP) up-regulate functional P-selectin glycoprotein ligand 1 (PSGL-1). Blockade of IL-12 inhibited functional PSGL-1 expression and reduced PP and LP CD4+ T cell recruitment by >40%. P-selectin blockade reduced LP recruitment of activated cells by 56% without affecting PP recruitment. Studies of mice examined 3 d after adoptive transfer of differentiated T cell subsets revealed that Th1 but not Th2 cells were recruited to small intestine PP and LP. Mucosal addressin cell adhesion molecule blockade reduced Th1 recruitment to PP by 90% and to LP by >72%, whereas P-selectin blockade reduced Th1 recruitment to PP by 18% and Th1 recruitment to LP by 84%. These data suggest that IL-12-induced functional PSGL-1 expression is a major determinant for the recruitment of Th1 effector cells to noninflamed as well as inflamed intestine.

The gene expression sequence of radiated mucosa in an animal mucositis model

Oral mucositis is a common, dose-limiting, acute toxicity of radiation therapy administered for the treatment of cancers of the head and neck. Accumulating data would suggest that the pathogenesis of mucositis is complex and involves the sequential interaction of all cell types of the oral mucosa, as well as a number of cytokines and elements of the oral environment. While a number of studies have reported on gene expression of particular cell types in response to radiation, the overall response of irradiated mucosa has only been evaluated in a limited way. The present study was undertaken to evaluate the expression of a target group of genes using RNA quantification assays and, more broadly, to assess patterns of mucosal gene expression using DNA microarray hybridization. Our results demonstrate the sequential upregulation of a series of genes that, when taken collectively, suggest an intricate functional interaction.