Denise A. Hatala

Salicylate-Based Anti-Inflammatory Drugs Inhibit the Early Lesion of Diabetic Retinopathy

It has been previously reported that aspirin inhibited the development of diabetic retinopathy in diabetic animals, raising the possibility that anti-inflammatory drugs may have beneficial effects on diabetic retinopathy. To further explore this, we compared effects of oral consumption of three different salicylate-based drugs (aspirin, sodium salicylate, and sulfasalazine) on the development of early stages of diabetic retinopathy in rats. These three drugs differ in their ability to inhibit cyclooxygenase but share an ability to inhibit nuclear factor-κB (NF-κB). Diabetes of 9–10 months duration significantly increased the number of TUNEL (transferase-mediated dUTP nick-end labeling)-positive capillary cells and acellular (degenerate) capillaries in the retinal vasculature, and all three salicylate-based drugs inhibited this cell death and formation of acellular capillaries without altering the severity of hyperglycemia. In short-term diabetes (2–4 months), all three salicylates inhibited the diabetes-induced loss of neuronal cells from the ganglion cell layer. Oral aspirin (as a representative of the salicylate family) inhibited diabetes-induced increase in NF-κB DNA-binding affinity in electrophoretic mobility shift assay and transcription factor array in nuclear extract isolated from whole retina. All three salicylates inhibited the diabetes-induced translocation of p50 (a subunit of NF-κB) into nuclei of retinal vascular endothelial cells of the isolated retinal vasculature, as well as of p50 and p65 into nuclei of cells in the ganglion cell layer and inner nuclear layer on whole-retinal sections. Sulfasalazine (also as a representative of the salicylates) inhibited the diabetes-induced upregulation of several inflammatory gene products, which are regulated by NF-κB, including vascular cell adhesion molecule, intracellular adhesion molecule-1, inducible nitric oxide synthase, and cyclooxygenase-2 in whole-retinal lysate. Salicylates, in doses administrated in our experiments, inhibited NF-κB and perhaps other transcription factors in the retina, were well tolerated, and offered new tools to investigate and inhibit the development of diabetic retinopathy.

Retinol Dehydrogenase (RDH12) Protects Photoreceptors from Light-induced Degeneration in Mice

RDH12 has been suggested to be one of the retinol dehydrogenases (RDH) involved in the vitamin A recycling system (visual cycle) in the eye. Loss of function mutations in the RDH12 gene were recently reported to be associated with autosomal recessive childhood-onset severe retinal dystrophy. Here we show that RDH12 localizes to the photoreceptor inner segments and that deletion of this gene in mice slows the kinetics of all-trans-retinal reduction, delaying dark adaptation. However, accelerated 11-cis-retinal production and increased susceptibility to light-induced photoreceptor apoptosis were also observed in Rdh12-/- mice, suggesting that RDH12 plays a unique, nonredundant role in the photoreceptor inner segments to regulate the flow of retinoids in the eye. Thus, severe visual impairments of individuals with null mutations in RDH12 may likely be caused by light damage1.

Temporal and spatial mRNA expression patterns of TGF-β1, 2, 3 and TβRI, II, III in skeletal muscles of mdx mice

Abstract To address potential regulatory roles of TGF-β1 in muscle inflammation and fibrosis associated with dystrophin deficiency, we performed quantitative RT-PCR and in situ hybridization to characterize the temporal and spatial mRNA expression patterns of TGF-β1 and other TGF-β subfamily members, TGF-β2 and TGF-β3, as well as their receptors, in quadriceps and diaphragm muscles of mdx mice. TGF-β1 mRNA was markedly upregulated in the endomysial inflammatory cells and regenerating fibers of mdx quadriceps and diaphragm, with the mRNA levels correlated with the degree of endomysial inflammation. Upregulation of TGF-β2, β3, and their receptors was also appreciated but to a much lesser degree. While high levels of TGF-β1 mRNA remained in the aging mdx quadriceps but not the diaphragm, progressive fibrosis only occurred in the diaphragm. Our data support a regulatory role for TGF-β1 in muscle inflammation in mdx mice. It also suggests different susceptibility of quadriceps and diaphragm muscles to fibrosis induced by TGF-β1 signaling pathway.

Keratinocyte but Not Endothelial Cell-Specific Overexpression of Tie2 Leads to the Development of Psoriasis

Psoriasis is initiated and maintained through a multifaceted interplay between keratinocytes, blood vessels, gene expression, and the immune system. One previous psoriasis model demonstrated that overexpression of the angiopoietin receptor Tie2 in endothelial cells and keratinocytes led to the development of a psoriasiform phenotype; however, the etiological significance of overexpression in each cell type alone was unclear. We have now engineered two new mouse models whereby Tie2 expression is confined to either endothelial cells or keratinocytes. Both lines of mice have significant increases in dermal vasculature but only the KC-Tie2-overexpressing mice developed a cutaneous psoriasiform phenotype. These mice spontaneously developed characteristic hallmarks of human psoriasis, including extensive acanthosis, increases in dermal CD4(+) T cells, infiltrating epidermal CD8(+) T cells, dermal dendritic cells and macrophages, and increased expression of cytokines and chemokines associated with psoriasis, including interferon-gamma, tumor necrosis factor-alpha, and interleukins 1alpha, 6, 12, 22, 23, and 17. Host-defense molecules, cathelicidin, beta-defensin, and S100A8/A9, were also up-regulated in the hyperproliferative skin. All of the phenotypic traits were completely reversed without any scarring following repression of the transgene and were significantly improved following treatment with the anti-psoriasis systemic therapeutic, cyclosporin A. Therefore, confining Tie2 overexpression solely to keratinocytes results in a mouse model that meets the clinical, histological, immunophenotypic, biochemical, and pharmacological criteria required for an animal model of human psoriasis.

Novel complement inhibitor limits severity of experimentally myasthenia gravis

Complement mediated injury of the neuromuscular junction is considered a primary disease mechanism in human myasthenia gravis and animal models of experimentally acquired myasthenia gravis (EAMG). We utilized active and passive models of EAMG to investigate the efficacy of a novel C5 complement inhibitor rEV576, recombinantly produced protein derived from tick saliva, in moderating disease severity.

The Cardioprotective Protein Apolipoprotein A1 Promotes Potent Anti-tumorigenic Effects

Background: ApoA1, a component of HDL, promotes anti-inflammatory, immunomodulatory, and cardioprotective functions. Results: ApoA1 suppresses tumor growth and metastasis, primarily via modulation of innate and adaptive immune responses. Conclusion: ApoA1 impacts tumor biology at multiple levels, which appear to be linked to immunomodulatory function. Significance: ApoA1 redirects elicited immune cells toward tumor suppression and rejection and may hold benefit as a cancer therapeutic. Here, we show that apolipoprotein A1 (apoA1), the major protein component of high density lipoprotein (HDL), through both innate and adaptive immune processes, potently suppresses tumor growth and metastasis in multiple animal tumor models, including the aggressive B16F10L murine malignant melanoma model. Mice expressing the human apoA1 transgene (A1Tg) exhibited increased infiltration of CD11b+ F4/80+ macrophages with M1, anti-tumor phenotype, reduced tumor burden and metastasis, and enhanced survival. In contrast, apoA1-deficient (A1KO) mice showed markedly heightened tumor growth and reduced survival. Injection of human apoA1 into A1KO mice inoculated with tumor cells remarkably reduced both tumor growth and metastasis, enhanced survival, and promoted regression of both tumor and metastasis burden when administered following palpable tumor formation and metastasis development. Studies with apolipoprotein A2 revealed the anti-cancer therapeutic effect was specific to apoA1. In vitro studies ruled out substantial direct suppressive effects by apoA1 or HDL on tumor cells. Animal models defective in different aspects of immunity revealed both innate and adaptive arms of immunity contribute to complete apoA1 anti-tumor activity. This study reveals a potent immunomodulatory role for apoA1 in the tumor microenvironment, altering tumor-associated macrophages from a pro-tumor M2 to an anti-tumor M1 phenotype. Use of apoA1 to redirect in vivo elicited tumor-infiltrating macrophages toward tumor rejection may hold benefit as a potential cancer therapeutic.

Adrenal and ovarian steroid hormone responses to gonadotropin-releasing hormone agonist treatment in polycystic ovary syndrome

It has been postulated that in polycystic ovary syndrome ovarian steroids can influence adrenal steroidogenesis. To test this hypothesis, basal and dexamethasone-suppressed-corticotropin-stimulated steroid hormone responses were compared among three groups of women before, during, and after gonadotropin-releasing hormone agonist treatment for 3 months. The groups were characterized as follows: (1) women with polycystic ovary syndrome with high dehydroepiandrosterone sulfate levels (greater than 400 micrograms/dl), (2) women with polycystic ovary syndrome with normal dehydroepiandrosterone sulfate levels (less than 300 micrograms/dl), and (3) normal ovulatory women. In response to gonadotropin-releasing hormone agonist, basal serum luteinizing hormone, follicle-stimulating hormone, estradiol, estrone, 17-hydroxyprogesterone, androstenedione, and testosterone in all three groups were suppressed to similar levels. Basal serum dehydroepiandrosterone sulfate levels in the group with high levels declined, but they did not reach the normal, unaltered concentrations in the other two groups. Two subjects with polycystic ovary syndrome in this group with high levels, who showed the greatest declines in basal serum dehydroepiandrosterone sulfate levels (34%, 40%), also had evidence of 3 beta-hydroxysteroid dehydrogenase deficiency before treatment, which was resolved by the end of treatment. In both groups with polycystic ovary syndrome, the increase in maximum incremental rise of dehydroepiandrosterone and dehydroepiandrosterone sulfate levels in response to a pharmacologic dose of corticotropin from a dexamethasone-suppressed baseline (adrenal androgen capacity) remained unaltered during gonadotropin-releasing hormone agonist administration. We conclude that ovarian steroids may promote excessive adrenal androgen secretion in women with polycystic ovary syndrome, may induce 3 beta-hydroxysteroid dehydrogenase deficiency as a mechanism for adrenal involvement in some women with polycystic ovary syndrome, and do not influence adrenal androgen capacity.

Overexpression of Bcl-2 in Vascular Endothelium Inhibits the Microvascular Lesions of Diabetic Retinopathy

Recent studies on the pathogenesis of diabetic retinopathy have focused on correcting adverse biochemical alterations, but there have been fewer efforts to enhance prosurvival pathways. Bcl-2 is the archetypal member of a group of antiapoptotic proteins. In this study, we investigated the ability of overexpressing Bcl-2 in vascular endothelium to protect against early stages of diabetic retinopathy. Transgenic mice overexpressing Bcl-2 regulated by the pre-proendothelin promoter were generated, resulting in increased endothelial Bcl-2. Diabetes was induced with streptozotocin, and mice were sacrificed at 2 months of study to measure superoxide generation, leukostasis, and immunohistochemistry, and at 7 months to assess retinal histopathology. Diabetes of 2 months duration caused a significant decrease in expression of Bcl-2 in retina, upregulation of Bax in whole retina and isolated retinal microvessels, and increased generation of retinal superoxide and leukostasis. Seven months of diabetes caused a significant increase in the number of degenerate (acellular) capillaries in diabetic animals. Furthermore, overexpression of Bcl-2 in the vascular endothelium inhibited the diabetes-induced degeneration of retinal capillaries and aberrant superoxide generation, but had no effect on Bax expression or leukostasis. Therefore, overexpression of Bcl-2 in endothelial cells inhibits the capillary degeneration that is characteristic of the early stages of diabetic retinopathy, and this effect seems likely to involve inhibition of oxidative stress.

Cutaneous manipulation of vascular growth factors leads to alterations in immunocytes, blood vessels and nerves: Evidence for a cutaneous neurovascular unit.

BACKGROUND Skin cells produce soluble factors which influence keratinocyte proliferation, angiogenesis, nerve innervation and immunocyte response. OBJECTIVE To test the hypothesis that epidermal-dermal interactions influence neural outgrowth, vascular survival, immunocyte recruitment and keratinocyte proliferation. METHODS We genetically manipulated the epidermis to express excess vascular endothelial growth factor (VEGF) and/or angiopoietin-1 (Ang1) and then examined the epidermal and dermal phenotypes. We compared these findings with those occurring following overexpression of the Ang1 receptor Tie2 in endothelial cells or keratinocytes. RESULTS Keratinocyte-overexpression of Ang1 resulted in increased epidermal thickness compared to control littermates. Keratinocyte-specific overexpression of Ang1 or VEGF increased dermal angiogenesis compared to control animals and combined Ang1-VEGF lead to further increases. Cutaneous leukocyte examination revealed increases in CD4(+) T cell infiltration in mice with keratinocyte-specific overexpression of Ang1, VEGF and Ang1-VEGF combined; in contrast only keratinocyte-specific Ang1 overexpression increased cutaneous F4/80(+) macrophage numbers. Interestingly, combined keratinocyte-derived Ang1-VEGF overexpression reduced significantly the number of F4/80(+) and Cd11c(+) cells compared to mice overexpressing epidermal Ang1 alone. Endothelial cell-specific Tie2 overexpression increased dermal angiogenesis but failed to influence the epidermal and immune cell phenotypes. Keratinocyte-specific Tie2 expressing mice had the highest levels of CD4(+), CD8(+) and CD11c(+) cell numbers and acanthosis compared to all animals. Finally, increases in the number of cutaneous nerves were found in all transgenic mice compared to littermate controls. CONCLUSION These findings demonstrate that change to one system (vascular or epidermal) results in change to other cutaneous systems and suggest that individual molecules can exert effects on multiple systems.