External Beam Radiotherapy for Head and Neck Cancers Is Associated with Increased Variability in Retinal Vascular Oxygenation

Background

Radiation retinopathy is a possible post-treatment complication of radiation therapy. The pathophysiologic mechanism is hypothesized to be microvascular in origin, but evidence is limited. In an effort to study retinal oxygenation in these patients, we herein evaluate the repeatability and variability of retinal oximetry measurements in subjects who had previously received radiation and make comparisons to a cohort of unirradiated subjects.

Methods

Using retinal oximetry, a non-invasive imaging modality, we performed in vivo measurements of arteriole (SaO₂) and venule SO₂ (SvO₂) in subjects (n = 9, 18 retinas) who had received incidental radiation to their retinas (≥ 45 Gy to one retina) and in healthy subjects (n = 20, 40 retinas). A total of 1367 SO₂ observations on 593 vessels in 29 persons were analyzed to assess three sources of variance in vessel SO₂: 1) variance in repeated measurements of the same vessel (“repeatability”), 2) variance in different vessels within the same subject (“within-subject variability”), and 3) variance between subjects (“between-subject variability”).

Results

Retinal oximetry measurements were highly repeatable in both irradiated patients and unirradiated subjects. The within-subject variability of SvO₂ and SaO₂ measurements constituted the highest component of variance in both groups and was significantly higher in venules vs. arterioles (relative effect size 1.8, p<0.001) and in irradiated subjects vs. unirradiated subjects (relative effect size 1.6, p<0.001).

Conclusions

Retinal oximetry is a highly repeatable technology and can be reliably used to study vascular oxygenation in irradiated subjects. Different vessels within the same subject exhibit a high degree of variability, suggesting that pooled analyses of multiple vessels are most likely to be informative of regional retinal oxygenation. Finally, irradiated subjects exhibited significantly higher within-subject variability in SO₂ measurements, suggesting that radiation may cause regional alterations in retinal oxygen delivery and/or metabolism.     

Induction of T helper 1 response by immunization of BALB/c mice with the gene encoding the second subunit of Echinococcus granulosus antigen B (EgAgB8/2)

A pre-designed plasmid containing the gene encoding the second subunit of Echinococcus granulosus AgB8 (EgAgB8/2) was used to study the effect of the immunization route on the immune response in BALB/c mice. Mice were immunized with pDRIVEEgAgB8/2 or pDRIVE empty cassette using the intramuscular (i.m.), intranasal (i.n.) or the epidermal gene gun (g.g.) routes. Analysis of the antibody response and cytokine data revealed that gene immunization by the i.m. route induced a marked bias towards a T helper type 1 (Th1) immune response as characterized by high IFN-γ gene expression and a low IgG1/IgG2a reactivity index (R.I.) ratio of 0.04. The i.n. route showed a moderate IFN-γ expression but a higher IgG1/IgG2a R.I. ratio of 0.25 indicating a moderate Th1 response. In contrast, epidermal g.g. immunization induced a Th2 response characterized by high IL-4 expression and the highest IgG1/IgG2a R.I. ratio of 0.58. In conclusion, this study showed the advantage of genetic immunization using the i.m. route and i.n. over the epidermal g.g. routes in the induction of Th1 immunity in response to E. granulosus AgB gene immunization.     

The Peripheral Myeloid Expansion Driven by Murine Cancer Progression Is Reversed by Radiation Therapy of the Tumor

Expansion of myeloid-lineage leukocytes in tumor-bearing mice has been proposed as a cause of systemic immunosuppression. We demonstrate that radiation therapy of tumors leads to a decline in myeloid cell numbers in the blood and a decrease in spleen size. The frequency of myeloid cells does not decline to the level seen in tumor-free mice: we demonstrate that metastatic disease can prevent myeloid cell numbers from returning to baseline, and that tumor recurrence from residual disease correlates with re-expansion of myeloid lineage cells. Radiation therapy results in increased proliferation of T cells in the spleen and while T cell responses to foreign antigens are not altered by tumor burden or myeloid cell expansion, responses to tumor-associated antigens are increased after radiation therapy. These data demonstrate that myeloid cell numbers are directly linked to primary tumor burden, that this population contracts following radiation therapy, and that radiation therapy may open a therapeutic window for immunotherapy of residual disease.     

Suppression of Cell-Mediated Immunity following Recognition of Phagosome-Confined Bacteria

Listeria monocytogenes is a facultative intracellular pathogen capable of inducing a robust cell-mediated immune response to sub-lethal infection. The capacity of L. monocytogenes to escape from the phagosome and enter the host cell cytosol is paramount for the induction of long-lived CD8 T cell–mediated protective immunity. Here, we show that the impaired T cell response to L. monocytogenes confined within a phagosome is not merely a consequence of inefficient antigen presentation, but is the result of direct suppression of the adaptive response. This suppression limited not only the adaptive response to vacuole-confined L. monocytogenes, but negated the response to bacteria within the cytosol. Co-infection with phagosome-confined and cytosolic L. monocytogenes prevented the generation of acquired immunity and limited expansion of antigen-specific T cells relative to the cytosolic L. monocytogenes strain alone. Bacteria confined to a phagosome suppressed the production of pro-inflammatory cytokines and led to the rapid MyD88-dependent production of IL-10. Blockade of the IL-10 receptor or the absence of MyD88 during primary infection restored protective immunity. Our studies demonstrate that the presence of microbes within a phagosome can directly impact the innate and adaptive immune response by antagonizing the signaling pathways necessary for inflammation and the generation of protective CD8 T cells.     

LPS-induced liver injury in D-galactosamine-sensitized mice requires secreted TNF-alpha and the TNF-p55 receptor

Lipopolysaccharide and D-galactosamine induced lethality and apoptotic liver injury is dependent on endogenously produced tumor necrosis factor (TNF)-alpha. The present study was undertaken to determine whether membrane-associated or secreted TNF-alpha signaling through the p55 or p75 receptor was responsible for survival and hepatic injury after lipopolysaccharide administration in D-galactosamine-sensitized mice. Transgenic mice expressing null forms of TNF-alpha, the p55 and p75 receptor, and mice expressing only a cell-associated form of TNF-alpha were challenged with 8 mg D-galactosamine and 100 ng lipopolysaccharide. Mortality and apoptotic liver injury were only seen in wild-type and p75 knockout mice. p75 Knockout mice had significantly higher concentrations of plasma TNF-alpha than any other experimental group (P 相似文献   

Metformin inhibits mTOR–HIF-1α axis and profibrogenic and inflammatory biomarkers in thioacetamide-induced hepatic tissue alterations

The potential inhibitory effect of the antidiabetic and anti-inflammatory drug, metformin on thioacetamide (TAA)-induced hepatotoxicity associated with the inhibition of mammalian target of rapamycin (mTOR)–hypoxia-inducible factor-1α (HIF-1α) axis has not been investigated before. Therefore, we tested whether metformin can protect against liver injuries including fibrosis induced by TAA possibly via the downregulation of mTOR–HIF-1α axis and profibrogenic and inflammatory biomarkers. Rats either injected with TAA (200 mg/kg; twice a week for 8 weeks) before being killed after 10 weeks (model group) or were pretreated with metformin (200 mg/kg) daily for 2 weeks before TAA injections and continued receiving both agents until the end of the experiment, at Week 10 (protective group). Using light and electron microscopy examinations, we observed in the model group substantial damage to the hepatocytes and liver tissue such as collagen deposition, infiltration of inflammatory cells, and degenerative cellular changes with ballooned mitochondria that were substantially ameliorated by metformin. Metformin also significantly ( p < 0.05) inhibited TAA-induced HIF-1α, mTOR, the profibrogenic biomarker α-smooth muscle actin, tissue inhibitor of metalloproteinases-1, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), alanine aminotransferase (ALT) and aspartate aminotransferase in harvested liver homogenates and blood samples. In addition, a significant ( p < 0.01) positive correlation between hypoxia scoring (HIF-1α) and the serum levels of TNF-α ( r = 0.797), IL-6 ( r = 0.859), and ALT ( r = 0.760) was observed. We conclude that metformin protects against TAA-induced hepatic injuries in rats, which is associated with the inhibition of mTOR–HIF-1α axis and profibrogenic and inflammatory biomarkers; thus, may offer therapeutic potential in humans.     

Synthesis,In Vitro Anti-HIV Activity,Cytotoxicity, and Computational Studies of Some New Steroids and Their Pyrazoline and Oxime Analogues

Russian Journal of Bioorganic Chemistry - There is an urgent need for the design and development of new and safer drugs for the treatment of HIV infection, active against the currently resistant...     

Anti-proteinase 3 anti-neutrophil cytoplasm autoantibodies recapitulate systemic vasculitis in mice with a humanized immune system

Evidence is lacking for direct pathogenicity of human anti-proteinase-3 (PR3) antibodies in development of systemic vasculitis and granulomatosis with polyangiitis (GPA, Wegener''s granulomatosis). Progress in study of these antibodies in rodents has been hampered by lack of PR3 expression on murine neutrophils, and by different Fc-receptor affinities for IgG across species. Therefore, we tested whether human anti-PR3 antibodies can induce acute vasculitis in mice with a human immune system. Chimeric mice were generated by injecting human haematopoietic stem cells into irradiated NOD-scid-IL2Rγ^−/− mice. Matched chimera mice were treated with human IgG from patients with: anti-PR3 positive renal and lung vasculitis; patients with non-vasculitic renal disease; or healthy controls. Six-days later, 39% of anti-PR3 treated mice had haematuria, compared with none of controls. There was punctate bleeding on the surface of lungs of anti-PR3 treated animals, with histological evidence of vasculitis and haemorrhage. Anti-PR3 treated mice had mild pauci-immune proliferative glomerulonephritis, with infiltration of human and mouse leukocytes. In 3 mice (17%) more severe glomerular injury was present. There were no glomerular changes in controls. Human IgG from patients with anti-PR3 autoantibodies is therefore pathogenic. This model of anti-PR3 antibody-mediated vasculitis may be useful in dissecting mechanisms of microvascular injury.     

Cutting Edge: Brazilian Pemphigus Foliaceus Anti-Desmoglein 1 Autoantibodies Cross-React with Sand Fly Salivary LJM11 Antigen

The environmental factors that contribute to the development of autoimmune diseases are largely unknown. Endemic pemphigus foliaceus in humans, known as Fogo Selvagem (FS) in Brazil, is mediated by pathogenic IgG4 autoantibodies against desmoglein 1 (Dsg1). Clusters of FS overlap with those of leishmaniasis, a disease transmitted by sand fly (Lutzomyia longipalpis) bites. In this study, we show that salivary Ags from the sand fly, and specifically the LJM11 salivary protein, are recognized by FS Abs. Anti-Dsg1 monoclonal autoantibodies derived from FS patients also cross-react with LJM11. Mice immunized with LJM11 generate anti-Dsg1 Abs. Thus, insect bites may deliver salivary Ags that initiate a cross-reactive IgG4 Ab response in genetically susceptible individuals and lead to subsequent FS. Our findings establish a clear relationship between an environmental, noninfectious Ag and the development of potentially pathogenic autoantibodies in an autoimmune disease.