The ecology and epidemiology of malaria parasitism in wild chimpanzee reservoirs.

Chimpanzees (Pan troglodytes) harbor rich assemblages of malaria parasites, including three species closely related to P. falciparum (sub-genus Laverania), the most malignant human malaria parasite. Here, we characterize the ecology and epidemiology of malaria infection in wild chimpanzee reservoirs. We used molecular assays to screen chimpanzee fecal samples, collected longitudinally and cross-sectionally from wild populations, for malaria parasite mitochondrial DNA. We found that chimpanzee malaria parasitism has an early age of onset and varies seasonally in prevalence. A subset of samples revealed Hepatocystis mitochondrial DNA, with phylogenetic analyses suggesting that Hepatocystis appears to cross species barriers more easily than Laverania. Longitudinal and cross-sectional sampling independently support the hypothesis that mean ambient temperature drives spatiotemporal variation in chimpanzee Laverania infection. Infection probability peaked at ~24.5 °C, consistent with the empirical transmission optimum of P. falciparum in humans. Forest cover was also positively correlated with spatial variation in Laverania prevalence, consistent with the observation that forest-dwelling Anophelines are the primary vectors. Extrapolating these relationships across equatorial Africa, we map spatiotemporal variation in the suitability of chimpanzee habitat for Laverania transmission, offering a hypothetical baseline indicator of human exposure risk.

CD4 receptor diversity represents an ancient protection mechanism against primate lentiviruses.

Infection with human and simian immunodeficiency viruses (HIV/SIV) requires binding of the viral envelope glycoprotein (Env) to the host protein CD4 on the surface of immune cells. Although invariant in humans, the Env binding domain of the chimpanzee CD4 is highly polymorphic, with nine coding variants circulating in wild populations. Here, we show that within-species CD4 diversity is not unique to chimpanzees but found in many African primate species. Characterizing the outermost (D1) domain of the CD4 protein in over 500 monkeys and apes, we found polymorphic residues in 24 of 29 primate species, with as many as 11 different coding variants identified within a single species. D1 domain amino acid replacements affected SIV Env-mediated cell entry in a single-round infection assay, restricting infection in a strain- and allele-specific fashion. Several identical CD4 polymorphisms, including the addition of N-linked glycosylation sites, were found in primate species from different genera, providing striking examples of parallel evolution. Moreover, seven different guenons (Cercopithecus spp.) shared multiple distinct D1 domain variants, pointing to long-term trans-specific polymorphism. These data indicate that the HIV/SIV Env binding region of the primate CD4 protein is highly variable, both within and between species, and suggest that this diversity has been maintained by balancing selection for millions of years, at least in part to confer protection against primate lentiviruses. Although long-term SIV-infected species have evolved specific mechanisms to avoid disease progression, primate lentiviruses are intrinsically pathogenic and have left their mark on the host genome.

CD4 receptor diversity in chimpanzees protects against SIV infection.

Human and simian immunodeficiency viruses (HIV/SIVs) use CD4 as the primary receptor to enter target cells. Here, we show that the chimpanzee CD4 is highly polymorphic, with nine coding variants present in wild populations, and that this diversity interferes with SIV envelope (Env)-CD4 interactions. Testing the replication fitness of SIVcpz strains in CD4+ T cells from captive chimpanzees, we found that certain viruses were unable to infect cells from certain hosts. These differences were recapitulated in CD4 transfection assays, which revealed a strong association between CD4 genotypes and SIVcpz infection phenotypes. The most striking differences were observed for three substitutions (Q25R, Q40R, and P68T), with P68T generating a second N-linked glycosylation site (N66) in addition to an invariant N32 encoded by all chimpanzee CD4 alleles. In silico modeling and site-directed mutagenesis identified charged residues at the CD4-Env interface and clashes between CD4- and Env-encoded glycans as mechanisms of inhibition. CD4 polymorphisms also reduced Env-mediated cell entry of monkey SIVs, which was dependent on at least one D1 domain glycan. CD4 allele frequencies varied among wild chimpanzees, with high diversity in all but the western subspecies, which appeared to have undergone a selective sweep. One allele was associated with lower SIVcpz prevalence rates in the wild. These results indicate that substitutions in the D1 domain of the chimpanzee CD4 can prevent SIV cell entry. Although some SIVcpz strains have adapted to utilize these variants, CD4 diversity is maintained, protecting chimpanzees against infection with SIVcpz and other SIVs to which they are exposed.

Adenovirus infection in savanna chimpanzees (Pan troglodytes schweinfurthii) in the Issa Valley, Tanzania.

Adenoviruses are a widespread cause of diverse human infections with recently confirmed zoonotic roots in African great apes. We focused on savanna-dwelling chimpanzees in the Issa Valley (Tanzania), which differ from those from forested sites in many aspects of behavior and ecology. PCR targeting the DNA polymerase gene detected AdV in 36.7% (69/188) of fecal samples. We detected five groups of strains belonging to the species Human mastadenovirus E and two distinct groups within the species Human mastadenovirus C based on partial hexon sequence. All detected AdVs from the Issa Valley are related to those from nearby Mahale and Gombe National Parks, suggesting chimpanzee movements and pathogen transmission.

Modifiers of radiation effects in the eye.

World events, including the threat of radiological terrorism and the fear of nuclear accidents, have highlighted an urgent need to develop medical countermeasures to prevent or reduce radiation injury. Similarly, plans for manned spaceflight to a near-Earth asteroid or journey to Mars raise serious concerns about long-term effects of space radiation on human health and the availability of suitable therapeutic interventions. At the same time, the need to protect normal tissue from the deleterious effects of radiotherapy has driven considerable research into the design of effective radioprotectors. For more than 70 years, animal models of radiation cataract have been utilized to test the short and long-term efficacy of various radiation countermeasures. While some compounds, most notably the Walter Reed (WR) class of radioprotectors, have reported limited effectiveness when given before exposure to low-LET radiation, the human toxicity of these molecules at effective doses limits their usefulness. Furthermore, while there has been considerable testing of eye responses to X- and gamma irradiation, there is limited information about using such models to limit the injurious effects of heavy ions and neutrons on eye tissue. A new class of radioprotector molecules, including the sulfhydryl compound PrC-210, are reported to be effective at much lower doses and with far less side effects. Their ability to modify ocular radiation damage has not yet been examined. The ability to non-invasively measure sensitive, radiation-induced ocular changes over long periods of time makes eye models an attractive option to test the radioprotective and radiation mitigating abilities of new novel compounds.

How radiation influences atherosclerotic plaque development: a biophysical approach in ApoE⁻/⁻ mice.

Atherosclerosis is the development of lipid-laden plaques in arteries and is nowadays considered as an inflammatory disease. It has been shown that high doses of ionizing radiation, as used in radiotherapy, can increase the risk of development or progression of atherosclerosis. To elucidate the effects of radiation on atherosclerosis, we propose a mathematical model to describe radiation-promoted plaque development. This model distinguishes itself from other models by combining plaque initiation and plaque growth, and by incorporating information from biological experiments. It is based on two consecutive processes: a probabilistic dose-dependent plaque initiation process, followed by deterministic plaque growth. As a proof of principle, experimental plaque size data from carotid arteries from irradiated ApoE[Formula: see text] mice was used to illustrate how this model can provide insight into the underlying biological processes. This analysis supports the promoting role for radiation in plaque initiation, but the model can easily be extended to include dose-related effects on plaque growth if available experimental data would point in that direction. Moreover, the model could assist in designing future biological experiments on this research topic. Additional biological data such as plaque size data from chronically-irradiated mice or experimental data sets with a larger variety in biological parameters can help to further unravel the influence of radiation on plaque development. To the authors' knowledge, this is the first biophysical model that combines probabilistic and mechanistic modeling which uses experimental data to investigate the influence of radiation on plaque development.

Role of TGF Beta and PPAR Alpha Signaling Pathways in Radiation Response of Locally Exposed Heart: Integrated Global Transcriptomics and Proteomics Analysis.

Epidemiological data from patients undergoing radiotherapy for thoracic tumors clearly show the damaging effect of ionizing radiation on cardiovascular system. The long-term impairment of heart function and structure after local high-dose irradiation is associated with systemic inflammatory response, contraction impairment, microvascular damage, and cardiac fibrosis. The goal of the present study was to investigate molecular mechanisms involved in this process. C57BL/6J mice received a single X-ray dose of 16 Gy given locally to the heart at the age of 8 weeks. Radiation-induced changes in the heart transcriptome and proteome were investigated 40 weeks after the exposure. The omics data were analyzed by bioinformatics tools and validated by immunoblotting. Integrated network analysis of transcriptomics and proteomics data elucidated the signaling pathways that were similarly affected at gene and protein level. Analysis showed induction of transforming growth factor (TGF) beta signaling but inactivation of peroxisome proliferator-activated receptor (PPAR) alpha signaling in irradiated heart. The putative mediator role of mitogen-activated protein kinase cascade linking PPAR alpha and TGF beta signaling was supported by data from immunoblotting and ELISA. This study indicates that both signaling pathways are involved in radiation-induced heart fibrosis, metabolic disordering, and impaired contractility, a pathophysiological condition that is often observed in patients that received high radiation doses in thorax.

Blood and lymphatic microvessel damage in irradiated human skin: The role of TGF-ß, endoglin and macrophages.

BACKGROUND AND PURPOSE: Microvascular damage is an important component of late radiation-induced morbidity. In our pre-clinical models, we demonstrated that repair of vessel injury is dependent on proper endoglin-mediated transforming growth factor-beta (TGF-ß) signalling and that it can be affected by infiltrating macrophages. We now wanted to extend these findings in irradiated patients, using skin as a model system, and assess whether bisphosphonates could modulate the response. MATERIALS AND METHODS: Paired skin biopsies from irradiated and non-irradiated sites were obtained from 48 breast cancer patients. In 8 patients, biopsies were repeated after 4months of bisphosphonate treatment. Immunohistochemistry was used to assess vascular alterations and leucocyte infiltration. Western Blot and qPCR were used to assess expression of growth factors and their receptors. RESULTS: Decreased blood vessel numbers at early time points were followed by increased endoglin expression and restoration of vessel number. Loss of small lymphatic vessels was associated with increased TGF-ß levels, whereas dilation of lymphatic vessels correlated with increased macrophage infiltration. Bisphosphonate treatment reduced leucocyte infiltration, but also prevented restoration of blood vessel numbers after irradiation. CONCLUSION: Radiation injury of the microvasculature is mediated through TGF-ß, whereas repair is modulated by the co-receptor endoglin and promoted by macrophages.

Mouse bone marrow-derived endothelial progenitor cells do not restore radiation-induced microvascular damage.

Background. Radiotherapy is commonly used to treat breast and thoracic cancers but it also causes delayed microvascular damage and increases the risk of cardiac mortality. Endothelial cell proliferation and revascularization are crucial to restore microvasculature damage and maintain function of the irradiated heart. We have therefore examined the potential of bone marrow-derived endothelial progenitor cells (BM-derived EPCs) for restoration of radiation-induced microvascular damage. Material & Methods. 16 Gy was delivered to the heart of adult C57BL/6 mice. Mice were injected with BM-derived EPCs, obtained from Eng(+/+) or Eng(+/-) mice, 16 weeks and 28 weeks after irradiation. Morphological damage was evaluated at 40 weeks in transplanted mice, relative to radiation only and age-matched controls. Results. Cardiac irradiation decreased microvascular density and increased endothelial damage in surviving capillaries (decrease alkaline phosphatase expression and increased von Willebrand factor). Microvascular damage was not diminished by treatment with BM-derived EPCs. However, BM-derived EPCs from both Eng(+/+) and Eng(+/-) mice diminished radiation-induced collagen deposition. Conclusion. Treatment with BM-derived EPCs did not restore radiation-induced microvascular damage but it did inhibit fibrosis. Endoglin deficiency did not impair this process.

Thalidomide ameliorates inflammation and vascular injury but aggravates tubular damage in the irradiated mouse kidney.

PURPOSE: The late side effects of kidney irradiation include vascular damage and fibrosis, which are promoted by an irradiation-induced inflammatory response. We therefore treated kidney-irradiated mice with the anti-inflammatory and angiogenesis-modulating drug thalidomide in an attempt to prevent the development of late normal tissue damage and radiation nephropathy in the mouse kidney. METHODS AND MATERIALS: Kidneys of C57Bl/6 mice were irradiated with a single dose of 14 Gy. Starting from week 16 after irradiation, the mice were fed with thalidomide-containing chow (100 mg/kg body weight/day). Gene expression and kidney histology were analyzed at 40 weeks and blood samples at 10, 20, 30, and 40 weeks after irradiation. RESULTS: Thalidomide improved the vascular structure and vessel perfusion after irradiation, associated with a normalization of pericyte coverage. The drug also reduced infiltration of inflammatory cells but could not suppress the development of fibrosis. Irradiation-induced changes in hematocrit and blood urea nitrogen levels were not rescued by thalidomide. Moreover, thalidomide worsened tubular damage after irradiation and also negatively affected basal tubular function. CONCLUSIONS: Thalidomide improved the inflammatory and vascular side effects of kidney irradiation but could not reverse tubular toxicity, which probably prevented preservation of kidney function.

Bone marrow-derived macrophages incorporate into the endothelium and influence vascular and renal function after irradiation.

PURPOSE: We recently demonstrated that endoglin, an ancillary transforming growth factor beta (TGF-ß) receptor, modulates vascular damage and fibrosis formation and influences renal function after kidney irradiation. We also suggested that this was partially accomplished by endoglin-mediated regulation of cytokine production in macrophages. Endoglin is expressed on both endothelial cells and on activated macrophages. Therefore, in the current study, we addressed the respective contribution of altered endoglin levels in the different cellular compartments to the development of kidney toxicity after irradiation. MATERIALS AND METHODS: Female endoglin wild-type (Eng(+/+) or WT) or heterozygous (Eng(+/-) or HET) mice were subjected to total body irradiation (2 × 6 Gy with a 6-hour interval) followed by kidney irradiation (1 × 3 Gy). Recipient mice were then transplanted with 4 × 10E(6) green fluorescent protein heterozygous (GFP(+/-)) bone marrow cells from either Eng(+/+) or Eng(+/-) male donor mice. Chimerism was determined 6 weeks thereafter. Blood samples were taken every 10 weeks after irradiation and at sacrifice at 35 weeks. One kidney was used to isolate macrophages; the other kidney was used for histology and to determine cytokine and chemokine concentrations. RESULTS: In all treatment groups, the majority of infiltrating macrophages were bone marrow-derived and this was not altered by endoglin. Bone marrow cells accumulated in damaged tissue areas in the interstitium, but also incorporated into the vasculature. Reducing endoglin levels in macrophages, but not in the endothelium, led to improved renal function (hematocrit, blood urea nitrogen) after irradiation. This was probably promoted by lowered production of pro-inflammatory cytokines and chemokines in macrophages. Other measurements of tissue toxicity (pericyte coverage, fibrosis, damage score) were not altered by differential endoglin expression. CONCLUSIONS: Endoglin regulates pro-inflammatory macrophage properties thereby influencing vascular and renal function after kidney irradiation.

Irradiation of existing atherosclerotic lesions increased inflammation by favoring pro-inflammatory macrophages.

BACKGROUND AND PURPOSE: Recent studies have shown an increased incidence of localized atherosclerosis and subsequent cardiovascular events in cancer patients treated with thoracic radiotherapy. We previously demonstrated that irradiation accelerated the development of atherosclerosis and predisposed to an inflammatory plaque phenotype in young hypercholesterolemic ApoE(-/-) mice. However, as older cancer patients already have early or advanced stages of atherosclerosis at the time of radiotherapy, we investigated the effects of irradiation on the progression of existing atherosclerotic lesions in vivo. MATERIAL AND METHODS: ApoE(-/-) mice (28 weeks old) received local irradiation with 14 or 0 Gy (sham-treated) at the aortic arch and were examined after 4 and 12 weeks for atherosclerotic lesions, plaque size and phenotype. Moreover, we investigated the impact of irradiation on macrophage phenotype (pro- or anti-inflammatory) and function (efferocytotic capacity, i.e. clearance of apoptotic cells) in vitro. RESULTS: Irradiation of existing lesions in the aortic arch resulted in smaller, macrophage-rich plaques with intraplaque hemorrhage and increased apoptosis. In keeping with the latter, in vitro studies revealed augmented polarization toward pro-inflammatory macrophages after irradiation and reduced efferocytosis by anti-inflammatory macrophages. In addition, considerably more lesions in irradiated mice were enriched in pro-inflammatory macrophages. CONCLUSIONS: Irradiation of existing atherosclerotic lesions led to smaller but more inflamed plaques, with increased numbers of apoptotic cells, most likely due to a shift toward pro-inflammatory macrophages in the plaque.

Radiation- and anthracycline-induced cardiac toxicity and the influence of ErbB2 blocking agents.

In Her2-positive breast cancer patients, inhibition of epidermal growth factor receptor 2 (ErbB2)-signaling is often combined with chemotherapy and radiotherapy. The risk of cardiac toxicity after anthracyclines and radiotherapy is recognized, but little is known about increased risk when these treatments are combined with ErbB2 inhibition. This study investigated whether ErbB2 inhibition increased radiation or anthracycline-induced toxicity. In an in vitro study, human cardiomyocytes were treated with irradiation or doxorubicin, alone or in combination with trastuzumab, and evaluated for cell survival and growth. Groups of mice received 0 or 14 Gy to the heart, alone or in combination with lapatinib, or 3 × 4 mg/kg doxorubicin alone or in combination with lapatinib. Mice were evaluated 40 weeks after treatment for cardiac damage. Changes in cardiac function ((99m)Tc-Myoview gated SPECT) were related to histomorphology and microvascular damage. Radiation or doxorubicin-induced cardiomyocyte toxicity (in vitro) were not exacerbated by trastuzumab. Cardiac irradiation of mice decreased microvascular density (MVD) and increased endothelial damage in surviving capillaries (decrease alkaline phosphatase expression and increased von Willebrand factor), but these changes were not exacerbated by lapatinib. Inflammatory responses in the irradiated epicardium (CD45+ and F4/80+ cells) were significantly reduced in combination with lapatinib. Irradiation, doxorubicin, and lapatinib each induced cardiac fibrosis but this was not further enhanced when treatments were combined. At the ultra-structural level, both lapatinib and doxorubicin induced mitochondrial damage, which was enhanced in combined treatments. Lapatinib alone also induced mild changes in cardiac function but this was not enhanced in the combined treatments. Trastuzumab did not enhance direct radiation or anthracycline toxicity of cardiomyocytes in vitro. Lapatinib did not enhance the risk of radiation or anthracycline-induced cardiac toxicity in mice up to 40 weeks after treatment, but mitochondrial damage was more severe after doxorubicin combined with lapatinib.

Cardiovascular effects after low-dose exposure and radiotherapy: what research is needed?

The authors of this report met at the Head Quarter of the International Atomic Energy Agency (IAEA) in Vienna, Austria, on 2-4 July 2012, for intensive discussions of an abundance of original publications on new epidemiological studies on cardiovascular effects after low-dose exposure and radiotherapy and radiobiological experiments as well as several comprehensive reviews that were published since the previous meeting by experts sponsored by the IAEA in June 2006. The data necessitated a re-evaluation of the situation with special emphasis on the consequences current experimental and clinical data may have for clinical oncology/radiotherapy and radiobiological research. The authors jointly arrived at the conclusions and recommendations presented here.

Endoglin haplo-insufficiency modifies the inflammatory response in irradiated mouse hearts without affecting structural and mircovascular changes.

BACKGROUND: It is now widely recognized that radiotherapy of thoracic and chest wall tumors increases the long-term risk of cardiovascular damage although the underlying mechanisms are not fully elucidated. There is increasing evidence that microvascular damage is involved. Endoglin, an accessory receptor for TGF-ß1, is highly expressed in damaged endothelial cells and may play a crucial role in cell proliferation and revascularization of damaged heart tissue. We have therefore specifically examined the role of endoglin in microvascular damage and repair in the irradiated heart. MATERIALS & METHODS: A single dose of 16 Gy was delivered to the heart of adult Eng(+/+) or Eng(+/-) mice and damage was evaluated at 4, 20 and 40 weeks, relative to age-matched controls. Gated single photon emission computed tomography (gSPECT) was used to measure cardiac geometry and function, and related to histo-morphology, microvascular damage (detected using immuno- and enzyme-histochemistry) and gene expression (detected by microarray and real time PCR). RESULTS: Genes categorized according to known inflammatory and immunological related disease were less prominently regulated in irradiated Eng(+/-) mice compared to Eng(+/+) littermates. Fibrosis related genes, TGF-ß1, ALK 5 and PDGF, were only upregulated in Eng(+/+) mice during the early phase of radiation-induced cardiac damage (4 weeks). In addition, only the Eng(+/+) mice showed significant upregulation of collagen deposition in the early fibrotic phase (20 weeks) after irradiation. Despite these differences in gene expression, there was no reduction in inflammatory invasion (CD45+cells) of irradiated Eng(+/-) hearts. Microvascular damage (microvascular density, alkaline phosphatase and von-Willebrand-Factor expression) was also similar in both strains. CONCLUSION: Eng(+/-) mice displayed impaired early inflammatory and fibrotic responses to high dose irradiation compared to Eng(+/+) littermates. This did not result in significant differences in microvascular damage or cardiac function between the strains.

Endoglin haploinsufficiency attenuates radiation-induced deterioration of kidney function in mice.

BACKGROUND AND PURPOSE: Endoglin is a transforming growth receptor beta (TGF-ß) co-receptor, which plays a crucial role in the development of late normal tissue damage. Mice with halved endoglin levels (Eng(+/-) mice) develop less inflammation, vascular damage and fibrosis after kidney irradiation compared to their wild type littermates (Eng(+/+) mice). This study was aimed at investigating whether reduced tissue damage in Eng(+/-) mice also results in superior kidney function. MATERIAL AND METHODS: Kidneys of Eng(+/+) and Eng(+/-) mice were irradiated with a single dose of 14 Gy. Functional kidney parameters and kidney histology were analysed at 20, 30 and 40 weeks after irradiation. RESULTS: Eng(+/-) mice displayed improved kidney parameters (haematocrit, BUN) compared to Eng(+/+) mice at 40 weeks after irradiation. Irradiation of Eng(+/+) kidneys damaged the vascular network and led to an increase in PDGFR-ß positive cells, indicative of fibrosis-promoting myofibroblasts. Compared to Eng(+/+) kidneys, vascular perfusion and number of PDGFR-ß positive cells were reduced in Eng(+/-) control mice; however, this did not further deteriorate after irradiation. CONCLUSIONS: Taken together, we show that not only kidney morphology, but also kidney function is improved after irradiation in Eng(+/-) compared to Eng(+/+) mice.

Thalidomide is not able to inhibit radiation-induced heart disease.

PURPOSE: Radiotherapy to the thorax increases the risk of radiation-induced heart disease. We and others have shown that local irradiation to the murine heart results in inflammatory and fibrotic responses and decreased microvascular density. In the present study we tested whether thalidomide is able to inhibit radiation-induced heart disease. METHODS: Single doses of 16 Gy or 0 Gy (sham treatment) were delivered to the hearts of mice. At 16 weeks after irradiation the mice were allocated to receive a thalidomide-containing chow (100 mg/kg body weight/day) or control chow until the end of the experiment. At 40 weeks after irradiation, functional imaging was performed and the hearts were examined for histological damage. RESULTS: Irradiation led to an increase in epicardial thickness and infiltrating inflammatory cells in the epicardium as well as an increase in interstitial collagen content. The microvasculature had a decreased alkaline phosphatase activity and reduced pericyte coverage. Thalidomide had no protective role in any of these processes. There were no differences in heart function measured between the treatment groups. CONCLUSIONS: Although others have shown protective effects of thalidomide in disease models involving inflammation, fibrosis and blood vessel maturation, thalidomide was not able to reduce radiation-induced heart damage.

Irradiation induces different inflammatory and thrombotic responses in carotid arteries of wildtype C57BL/6J and atherosclerosis-prone ApoE(-/-) mice.

BACKGROUND AND PURPOSE: We have previously shown that irradiation to the carotid arteries of hypercholesterolemic ApoE(-/-) mice accelerated the development of macrophage-rich, inflammatory atherosclerotic lesions. We now investigated the mechanism underlying the development of radiation-induced atherosclerosis. MATERIALS AND METHODS: ApoE(-/-) and wildtype C57BL/6J mice received 0, 8 or 14 Gy to the neck and the carotid arteries were harvested 1 day, 1 or 4 weeks later. Immunohistochemical stainings were performed to evaluate well-known inflammatory and thrombotic molecules. A hypothesis-generating approach was used to compare gene expression profiles of irradiated and unirradiated carotid arteries. RESULTS: Basal levels of endothelial VCAM-1 and thrombomodulin immunoexpression were higher in ApoE(-/-) mice than in C57BL/6J mice. At 1 week after 14 Gy VCAM-1 immunoexpression was decreased in ApoE(-/-) mice, whereas ICAM-1 immunoexpression was decreased at 1 and 4 weeks after 14 Gy in C57BL/6J mice. Thrombomodulin and tissue factor immunoexpression were elevated at 4 weeks after 14 Gy in ApoE(-/-) mice and reduced in C57BL/6J mice. There were no changes in immunoexpression of eNOS, MCP-1 or endoglin. Several canonical pathways were differentially expressed after irradiation, including tight junction pathways, leukocyte extravasation signaling and PI3K/AKT signaling. CONCLUSION: ApoE(-/-) and C57BL/6J mice respond differently to irradiation. The thrombotic pathways were activated after irradiation in ApoE(-/-) mice only. Genes involved in tight junction regulation were up-regulated in ApoE(-/-) mice and decreased in C57BL/6J mice. These factors may have contributed to fatty-streak formation in ApoE(-/-) mice.

The TGF-ß co-receptor endoglin regulates macrophage infiltration and cytokine production in the irradiated mouse kidney.

BACKGROUND AND PURPOSE: We previously showed that mice with reduced levels of the transforming growth factor-beta (TGF-ß) co-receptor endoglin (Eng(+/-) mice) develop less fibrosis and vascular damage after kidney irradiation than their wild type (Eng(+/+) mice) littermates; however, the underlying mechanism was unclear. Results from current studies suggest that this occurs via modulation of the radiation-induced inflammatory response. MATERIALS AND METHODS: Kidneys of Eng(+/+) and Eng(+/-) mice were irradiated with 16Gy. Mice were sacrificed at 20weeks after irradiation and gene expression and protein levels were analyzed. RESULTS: Kidney irradiation triggered the infiltration of macrophages in both Eng(+/+) and Eng(+/-) mice, however, levels of macrophage-produced cytokines interleukin 1 beta (Il1b) and interleukin 6 (Il6) were reduced in irradiated Eng(+/-) compared to Eng(+/+) mice. Double immuno-stainings confirmed that IL-6 was produced by macrophages, whereas IL-1ß was mainly detected in other cell types. Accordingly, inflammatory cell precursors derived from the bone marrow of Eng(+/-) mice showed impaired ability to express Il1b and Il6 compared to wild type mice. CONCLUSIONS: Endoglin promotes kidney inflammation after irradiation by regulating macrophage infiltration and interleukin production, thereby promoting pathogenic changes after radiation exposure.

Local heart irradiation of ApoE(-/-) mice induces microvascular and endocardial damage and accelerates coronary atherosclerosis.

BACKGROUND AND PURPOSE: Radiotherapy of thoracic and chest-wall tumors increases the long-term risk of radiation-induced heart disease, like a myocardial infarct. Cancer patients commonly have additional risk factors for cardiovascular disease, such as hypercholesterolemia. The goal of this study is to define the interaction of irradiation with such cardiovascular risk factors in radiation-induced damage to the heart and coronary arteries. MATERIAL AND METHODS: Hypercholesterolemic and atherosclerosis-prone ApoE(-/-) mice received local heart irradiation with a single dose of 0, 2, 8 or 16 Gy. Histopathological changes, microvascular damage and functional alterations were assessed after 20 and 40 weeks. RESULTS: Inflammatory cells were significantly increased in the left ventricular myocardium at 20 and 40 weeks after 8 and 16 Gy. Microvascular density decreased at both follow-up time-points after 8 and 16 Gy. Remaining vessels had decreased alkaline phosphatase activity (2-16 Gy) and increased von Willebrand Factor expression (16 Gy), indicative of endothelial cell damage. The endocardium was extensively damaged after 16 Gy, with foam cell accumulations at 20 weeks, and fibrosis and protein leakage at 40 weeks. Despite an accelerated coronary atherosclerotic lesion development at 20 weeks after 16 Gy, gated SPECT and ultrasound measurements showed only minor changes in functional cardiac parameters at 20 weeks. CONCLUSIONS: The combination of hypercholesterolemia and local cardiac irradiation induced an inflammatory response, microvascular and endocardial damage, and accelerated the development of coronary atherosclerosis. Despite these pronounced effects, cardiac function of ApoE(-/-) mice was maintained.