Effects of five commonly used glucocorticoids on haemangioma in vitro

Diagnosis and Management of Infantile Hemangioma

Infantile hemangiomas (IHs) are the most common tumors of childhood. Unlike other tumors, they have the unique ability to involute after proliferation, often leading primary care providers to assume they will resolve without intervention or consequence. Unfortunately, a subset of IHs rapidly develop complications, resulting in pain, functional impairment, or permanent disfigurement. As a result, the primary clinician has the task of determining which lesions require early consultation with a specialist. Although several recent reviews have been published, this clinical report is the first based on input from individuals representing the many specialties involved in the treatment of IH. Its purpose is to update the pediatric community regarding recent discoveries in IH pathogenesis, treatment, and clinical associations and to provide a basis for clinical decision-making in the management of IH.

Infantile hemangioma-mechanism(s) of drug action on a vascular tumor

Infantile hemangioma (IH), a benign vascular tumor, is the most common tumor of infancy, with an incidence of 5%-10% at the end of the first year. The tumor displays a distinctive life cycle consisting of a proliferating phase, occurring in the first months of life, followed by an involuting phase. Thus, IH represents a unique model of postnatal vasculogenesis, angiogenesis, and vessel regression. Traditionally, corticosteroids were the drug of choice when treatment of IH was indicated. In recent years, beta-blockers, most specifically propranolol, have serendipitously been shown to be an effective pharmacological treatment. This article will focus on the mechanism of action of these two drugs, the old and the new treatments, in slowing the growth and accelerating involution of IH.

Pharmacologic therapies for infantile hemangioma: is there a rational basis?

BACKGROUND

Infantile hemangioma is the most common tumor of infancy. The majority of cases are managed conservatively, but intervention is necessary in approximately 10 percent of cases because of the threat to life or function or because of tissue distortion or destruction. The mainstay treatment for these problematic proliferating infantile hemangiomas is pharmacologic therapy, mostly discovered serendipitously.

METHODS

This review examines the rational basis of the hitherto empirical pharmacologic therapies for the enigmatic infantile hemangioma, in light of new knowledge regarding its biology, including the critical roles of stem cells and the renin-angiotensin system.

RESULTS

Steroids have remained the first-line therapy for problematic infantile hemangioma for over 40 years despite their known side effects and failure rates. Vincristine has emerged as an alternative to interferon for steroid-resistant cases because of interferon's adverse effects, especially neurotoxicity. β-Blockers are now the preferred first-line therapy for problematic cases. There is increasing evidence that infantile hemangioma is a disorder of aberrant proliferation and differentiation of primitive mesoderm-derived neural crest phenotypic cells. This primitive phenotype that gives rise to a hemogenic endothelium intermediate has the ability to undergo primitive erythropoiesis and terminal mesenchymal differentiation.

CONCLUSIONS

The recent discovery of the crucial role of stem cells and the inferred role of the renin-angiotensin system in the biology of infantile hemangioma underscores the possibility of even more targeted therapies, by using modulators of the renin-angiotensin system, on infantile hemangioma. The observation of the potential role of these traditional antihypertensive agents in stem cell biology may lead to better understanding of developmental biology and tumor stem cell growth.

Stress hormones increase cell proliferation and regulates interleukin-6 secretion in human oral squamous cell carcinoma cells

Patients with oral cancer can have high psychological distress levels, but the effects of stress-related hormones on oral cancer cells and possible mechanisms underlying these relationships are unknown. In this study, we have investigated the effects of stress-related hormones on interleukin-6 (IL-6) secretion and proliferation of oral squamous cell carcinoma (OSCC) cells. The effects of norepinephrine (NE), and cortisol were studied in SCC9, SCC15, and SCC25 cells and effects of isoproterenol in SCC9 and SCC25 cells. Real-time PCR studies revealed constitutive β1- and β2-adrenergic receptors (β-ARs) expression in the SCC9, SCC15, and SCC25 cells. The results showed that NE and isoproterenol significantly enhanced IL-6 mRNA expression and protein production in supernatants of SCC9 and SCC25 cells. Physiological stress levels of NE and isoproterenol (10 μM) at 1 h elicited the most robust IL-6 increase. Regarding IL-6 secretion, 10 μM NE induced a 5-fold increase at 1 h, 3.7-fold increase at 6 h, and 3.2-fold at 24 h in SCC9 cells. These effects were blocked by the β-adrenergic antagonist propranolol, supporting a role for β-ARs in IL-6 secretion. The effects of cortisol varied according to the hormone concentration. Pharmacological concentrations of cortisol (1000 nM) inhibited IL-6 production by SCC9 and SCC25 cells. Cortisol dose that simulates stress conditions (10 nM) tended to increase IL-6 expression in SCC9 cells. Hormonal doses that simulate stress conditions (10 μM NE, at 6 h in SCC9 and SCC15 cells and 10 nM cortisol, at 48 h in SCC15 cells) stimulated increased cell proliferation. Treatment of SCC9 cells with IL-6 neutralizing ab (10 μg/mL) partially inhibited NE-induced proliferation. Finally, 20 OSCC biopsies were shown to express β1- and β2-ARs. These findings suggest that stress hormones can affect oral cancer cells behavior.

Corticosteroid suppression of VEGF-A in infantile hemangioma-derived stem cells

BACKGROUND

Corticosteroids are commonly used to treat infantile hemangioma, but the mechanism of action of this therapy is unknown. We investigated the effect of corticosteroids in a previously described in vivo model of infantile hemangioma and in cultured hemangioma-derived cells.

METHODS

We tested hemangioma-derived stem cells for vasculogenic activity in vivo after implantation into immune-deficient (nude) mice. We studied dexamethasone treatment of both the cells before implantation and the mice after implantation. We also tested hemangioma-derived stem cells for expression of vascular endothelial growth factor A (VEGF-A) in vitro and studied the inhibition of VEGF-A expression, using short hairpin RNA (shRNA) in vivo and in vitro.

RESULTS

Systemic treatment with dexamethasone led to dose-dependent inhibition of tumor vasculogenesis in the murine model. Pretreatment of hemangioma-derived stem cells in vitro before implantation also inhibited vasculogenesis. Dexamethasone suppressed VEGF-A production by hemangioma-derived stem cells in vitro but not by hemangioma-derived endothelial cells or human umbilical-vein endothelial cells. Silencing VEGF-A in hemangioma-derived stem cells reduced vasculogenesis in vivo. VEGF-A was detected in hemangioma specimens in the proliferating phase but not in the involuting phase and was shown by immunostaining to reside outside of vessels. Corticosteroid treatment suppressed other proangiogenic factors in hemangioma-derived stem cells, including urokinase plasminogen activator receptor, interleukin-6, monocyte chemoattractant protein 1, and matrix metalloproteinase 1.

CONCLUSIONS

In a murine model, dexamethasone inhibited the vasculogenic potential of stem cells derived from human infantile hemangioma. The corticosteroid also inhibited the expression of VEGF-A by hemangioma-derived stem cells, and silencing of VEGF-A expression in these cells inhibited vasculogenesis in vivo.

The role of clusterin (CLU) in malignant transformation and drug resistance in breast carcinomas

Breast cancer is the main cause of cancer-related death among women in Western countries. Current research is focused on identifying antiapoptotic proteins which could be a possible target for novel chemotherapeutic drugs. Secretory clusterin (sCLU) is an extracellular chaperone that has been functionally implicated in DNA repair, cell-cycle regulation, apoptotic cell death and tumorigenesis. The implication of sCLU in carcinogenesis and the progression of breast carcinomas make it an interesting gene, worthy of investigation. It has been reported to present powerful antiapoptotic activity and to perform a prosurvival function with most therapeutic treatments for breast cancer. This review summarizes our current understanding of the role of CLU in tumorigenesis, progression, and response to treatment in breast carcinomas.

Therapeutic manipulation of glucocorticoid metabolism in cardiovascular disease

The therapeutic potential for manipulation of glucocorticoid metabolism in cardiovascular disease was revolutionized by the recognition that access of glucocorticoids to their receptors is regulated in a tissue-specific manner by the isozymes of 11beta-hydroxysteroid dehydrogenase. Selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 have been shown recently to ameliorate cardiovascular risk factors and inhibit the development of atherosclerosis. This article addresses the possibility that inhibition of 11beta-hydroxsteroid dehydrogenase type 1 activity in cells of the cardiovascular system contributes to this beneficial action. The link between glucocorticoids and cardiovascular disease is complex as glucocorticoid excess is linked with increased cardiovascular events but glucocorticoid administration can reduce atherogenesis and restenosis in animal models. There is considerable evidence that glucocorticoids can interact directly with cells of the cardiovascular system to alter their function and structure and the inflammatory response to injury. These actions may be regulated by glucocorticoid and/or mineralocorticoid receptors but are also dependent on the 11beta-hydroxysteroid dehydrogenases which may be expressed in cardiac, vascular (endothelial, smooth muscle) and inflammatory (macrophages, neutrophils) cells. The activity of 11beta-hydroxysteroid dehydrogenases in these cells is dependent upon differentiation state, the action of pro-inflammaotory cytokines and the influence of endogenous inhibitors (oxysterols, bile acids). Further investigations are required to clarify the link between glucocorticoid excess and cardiovascular events and to determine the mechanism through which glucocorticoid treatment inhibits atherosclerosis/restenosis. This will provide greater insights into the potential benefit of selective 11beta-hydroxysteroid dehydrogenase inhibitors in treatment of cardiovascular disease.

Treating subglottic haemangioma with methylprednisolone and interferonα-2a

Subglottic haemangiomas are benign vascular malformations presenting in early infancy with respiratory distress due to progressive airway obstruction. The lesion, after undergoing proliferation during the first few months, naturally involutes by an age of 2-3 years. Due to high incidence of mortality, therapy should be initiated immediately. Multiple therapeutic options, such as steroids, interferon, surgery and laser ablation, are available but the best treatment is controversial. This report describes an infant presenting with respiratory distress and cutaneous haemangioma who was detected to have airway obstructive haemangioma from the subglottis to the carina. Due to the massive size, surgical and laser ablation could not be exercised. Also, the infant showed no response to dexamethasone, prednisolone or interferon. Following failure of these modalities, the infant was successfully managed with concurrent administration of daily interferon and pulse methylprednisolone. The regime resulted in rapid shrinkage of the haemangioma and resolution of symptoms, with no recurrence up to 24 months of age.

Evaluating systemic prednisone therapy for proliferating haemangioma in infancy

In this study, we reviewed the history of 38 children with proliferating haemangiomas treated with systemic corticosteroids at our institution between 2000 and 2002. Prednisone was administered at an initial dose of 2 mg/kg per day for 2 weeks followed by a dose of 1 mg/kg per day for another 2-4 weeks and consecutive slow tapering over an additional 4-5 months. For 93% of the children, this protocol was successful in reducing the size of the haemangioma by more than 25% after 2 weeks of treatment. Side effects were moderate and reversible after cessation of therapy.

The effect of intralesional steroid injections on the volume and blood flow in periocular capillary haemangiomas

AIM

To examine the effect of steroid therapy on the volume estimates and blood flow characteristics of childhood periorbital capillary haemangiomas.

PATIENTS AND METHODS

Children at risk of amblyopia due to periorbital haemangiomas were treated with intralesional steroid injections (between 1 and 4 courses) and serial assessment of the volume and blood-flow characteristics of the lesions measured using colour Doppler ultrasonography. The characteristics of the haemangiomas in these children were compared with a cohort of untreated cases.

RESULTS

Eight of nine treated children were female, this proportion being significantly different from the equal sex distribution of an untreated cohort (p < 0.05). All children in the steroid-treated group presented within 1 month of birth, compared to the untreated children, who presented at an average of 2.1 months of age (range 0-14, median 2.9 months) (p = 0.04) and they required significantly longer follow-up in the Orbital service (mean 65 months, range 26-105), compared with an average of 35 months (range 4-92, median 23) in the untreated group (p = 0.002). The maximum estimated volume of the lesions were significantly larger in the treated group (treated group mean 8.9 ml, untreated group mean 4.1 ml; p = 0.016), with a trend towards higher maximum measured blood velocities in the treated group (treated mean 64 cm compared with untreated mean 52 cm; p = 0.1). Steroid injections appear to reduce the volume and blood flow of haemangiomas, this suppression persisting for several months (between 5 and 20) before the lesion later displays the cyclic fluctuations in volume and flow seen with untreated lesions. All treated haemangiomas had some residual vascular anomaly, detectable on ultrasonography, at last follow-up--this being despite absence of clinical signs in most cases.

CONCLUSION

Periorbital capillary haemangiomas requiring steroid therapy for risk of amblyopia were significantly commoner in females, were larger lesions and presented at an earlier age. Intralesional steroids appear to cause a reduction of blood flow, with a transient reduction in volume and a suppression of the natural cyclic variation seen without treatment. The changes after a course of steroid therapy appear to last for between 5 and 20 months, this period of suppression of the lesion probably being particularly useful during infancy and early childhood when the child is at greatest risk of amblyopia.

Anticlusterin treatment of breast cancer cells increases the sensitivities of chemotherapy and tamoxifen and counteracts the inhibitory action of dexamethasone on chemotherapy-induced cytotoxicity

INTRODUCTION

Overexpression of the apoptosis-related protein clusterin is associated with breast cancer development and tumor progression. We describe the use of clusterin-specific antisense oligonucleotides and antibodies to sensitize breast carcinoma cells to anticancer drugs routinely used in breast cancer therapy.

METHODS

MCF-7 and MDA-MB-231 cells were treated with the oligonucleotide or antibody, chemotherapeutic agents (doxorubicin or paclitaxel), tamoxifen, or with combinations of these.

RESULTS

Treatments that include antisense clusterin oligonucleotide or antibody to clusterin have been shown to reduce the number of viable cells more effectively than treatment with the drugs alone. We also demonstrate that dexamethasone pretreatment of breast cancer cell lines inhibits chemotherapy-induced cytotoxicity and is associated with the transcriptional induction of clusterin. However, anticlusterin treatment increases chemotherapy-induced cytotoxicity, even in the presence of glucocorticoids, suggesting a possible role for these proteins in glucocorticoid-mediated survival.

CONCLUSION

These data suggest that combined treatment with antibodies to clusterin or antisense clusterin oligodeoxynucleotides and paclitaxel, doxorubicin, or tamoxifen could be a novel and attractive strategy to inhibit the progression of breast carcinoma by regulation of the clusterin function. Moreover, glucocorticoid activation in breast cancer cells regulates survival signaling by the direct transactivation of genes like clusterin which encode proteins that decrease susceptibility to apoptosis. Given the widespread clinical administration of dexamethasone before chemotherapy, understanding glucocorticoid-induced survival mechanisms is essential for achieving optimal therapeutic responses.

Mechanisms underlying developmental programming of elevated blood pressure and vascular dysfunction: evidence from human studies and experimental animal models

Cardiovascular-related diseases are the leading cause of death in the world in both men and women. In addition to the environmental and genetic factors, early life conditions are now also considered important contributing elements to these pathologies. The concept of 'fetal' or 'developmental' origins of adult diseases has received increased recognition over the last decade, yet the mechanism by which altered perinatal environment can lead to dysfunction mostly apparent in the adult are incompletely understood. This review will focus on the mechanisms and pathways that epidemiological studies and experimental models have revealed underlying the adult cardiovascular phenotype dictated by the perinatal experience, as well as the probable key causal or triggering elements. Programmed elevated blood pressure in the adult human or animal is characterized by vascular dysfunction and microvascular rarefaction. Developmental mechanisms that have been more extensively studied include glucocorticoid exposure, the role of the kidneys and the renin-angiotensin system. Other pathophysiological pathways have been explored, such as the role of the brain and the sympathetic nervous system, oxidative stress and epigenetic changes. As with many complex diseases, a unifying hypothesis linking the perinatal environment to elevated blood pressure and vascular dysfunction in later life cannot be presumed, and a better understanding of those mechanisms is critical before clinical trials of preventive or 'deprogramming' measures can be designed.

A novel in vivo model of human hemangioma: xenograft of human hemangioma tissue on nude mice

BACKGROUND

Experimental models of human infantile hemangiomas are needed, although none of the current ones is ideal in representing the natural development of hemangioma. In this article, the authors present a nude mice model of human hemangioma with serial morphologic findings on grafts.

METHODS

A specimen of rapidly growing hemangioma tissue was obtained surgically from a 2-month-old boy and was cut into 96 pieces, which were implanted subcutaneously into nude mice, six pieces each. During the 6-month experimental period, gross view, hematoxylin and eosin staining, double immunofluorescent labeling with mouse antihuman CD31 and fluorescein isothiocyanate-labeled rat antimouse CD34, and transmission electron microscopic observation were performed.

RESULTS

Eighty-one of the 96 grafts (84.4 percent) survived and grew during the second month to 3 to 4 months after transplantation, followed by gradual involution. Histologic examination showed cellular edema, degeneration, and necrosis in the early stage. From approximately 30 days, cellular density increased and karyokinesis was identified at 45 days. At 2 months, the grafts were composed mainly of hemangioma tissue and signs of involution appeared. Thereafter, signs of involution turned significant and the grafts were replaced with fibrofatty tissue. It was confirmed through double immunofluorescent labeling that the chief cellular components were endothelial cells of human origin. Findings on ultrastructural investigation were concordant with those on light microscopic observation.

CONCLUSIONS

With human hemangioma tissue implanted into nude mice, an animal model was established successfully. The development of grafts after ischemia resembled the natural course of human infantile hemangioma.

Myeloid cells in infantile hemangioma

Little is known about the pathogenesis of infantile hemangiomas despite the fact that they are relatively common tumors. These benign neoplasms occur in as many as 1 in 10 births, and although rarely life threatening, hemangiomas can pose serious concerns to the cosmetic and psychosocial development of the afflicted child. Ulceration, scarring, and disfigurement are significant problems as are encroachment of the ear and eye, which can threaten hearing and vision. The precise mechanisms controlling the rapid growth observed in the first months of life and the spontaneous involution that follows throughout the course of years remain unknown. In this report we demonstrate the presence of large numbers of hematopoietic cells of the myeloid lineage in proliferating hemangiomas and propose a mechanism for the observed evolution of these lesions that is triggered by hypoxia and involves the participation of myeloid cells. We report the results of experiments using myeloid markers (CD83, CD32, CD14, CD15) that unexpectedly co-labeled hemangioma endothelial cells, providing new evidence that these cells are distinct from normal endothelium.

Clusterin as a therapeutic target for radiation sensitization in a lung cancer model

PURPOSE

Clusterin plays important roles in cell survival and death. Inactivation of clusterin enhances the therapeutic efficacy of chemotherapy in lung cancer models. The purpose of this study was to determine whether inhibition of clusterin by an antisense-based investigative drug enhances radiation sensitization in a lung cancer model.

METHODS AND MATERIALS

Cells were transfected with an antisense oligonucleotide (ASO) against clusterin (OGX-011). Apoptosis was determined by 7-aminoactinomycin D staining. Cell survival was examined by 3-(4, 5-methylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide (MTT) and clonogenic assay. Xenograft model was used to demonstrate tumor growth and tumor blood flow.

RESULTS

OGX-011 specifically attenuated the expression of secreted clusterin (prosurvival), with no apparent effect on the expression of nuclear clusterin (proapoptotic). Apoptosis was significantly increased when H460 lung cancer cells were treated with OGX-011 plus radiation. Inhibition of clusterin followed by radiation greatly decreased cell survival. H460 xenografts that were treated with OGX-011 plus radiotherapy demonstrated growth delay beyond 17 days. Doppler studies showed that tumor blood flow was compromised when mice bearing H460 xenografts were treated with OGX-011 and radiation.

CONCLUSION

A combination of radiotherapy and OGX-011 improved control of tumor growth and vascular regression in the H460 lung cancer model.

Hemangiomas of infancy: clinical and biological characteristics

Hemangiomas of infancy are common in the general pediatric population, are usually easily diagnosed, and generally do not require treatment. However, a small but significant percentage of hemangiomas of infancy may develop complications, including infection or ulceration. In addition, hemangiomas located in some anatomic regions may be associated with other anomalies and therefore require more careful monitoring and earlier intervention to prevent permanent sequelae. This review focuses on distinguishing hemangiomas from vascular malformations and delineates the natural history of hemangiomas of infancy, with an emphasis on identifying those hemangiomas that require additional evaluation and closer follow-up. Current treatment modalities, including the use of systemic steroids and the pulsed-dye laser, are discussed. In addition, several conditions that often present with cutaneous hemangiomas are described, including PHACES syndrome and neonatal hemangiomatosis. Finally, an assessment is made of the current understanding of the biology of hemangioma proliferation and involution, including the role of endothelial growth factors and GLUT1, a new marker for hemangiomas of infancy.

Neonatal glucocorticosteroid treatment causes systolic dysfunction and compensatory dilation in early life: studies in 4-week-old prepubertal rats

Glucocorticosteroid treatment is widely used to prevent chronic lung disease in premature infants. Recent studies in adult rats, treated with dexamethasone in the neonatal period, report negative long-term effects on the heart and severely reduced life expectancy. We treated neonatal rats with dexamethasone and studied cardiac function after 4 wk (prepubertal age) to investigate whether the late effects as previously described are preceded by detectable alterations in cardiac function at a younger age. Male rat pups (n = 12) were injected intraperitoneally with dexamethasone on d 1, 2, and 3 (0.5, 0.3, and 0.1 mug/g) of life. Control pups (n = 10) received saline. At 4 wk the animals were anesthetized, and a pressure-conductance catheter was introduced into the left ventricle to measure pressure-volume loops. Cardiac function was measured and pressure-volume relations were determined to quantify intrinsic systolic and diastolic function. Subsequently, hearts were excised for histologic examination. Compared with saline-treated animals, dexamethasone-treated rats had a reduced ventricular weight (270 +/- 40 versus 371 +/- 23 mg, p < 0.001) and reduced systolic function (end-systolic elastance: 1.24 +/- 0.43 versus 2.50 +/- 1.39 mm Hg/muL, p = 0.028). Cardiac output was maintained and end-diastolic volume was increased (84 +/- 23 versus 59 +/- 19 microL, p = 0.012) indicating a state of compensatory dilatation. Heart rate, diastolic function, and systemic vascular resistance were unchanged. Neonatal dexamethasone treatment causes cardiac alterations that can be detected in the prepubertal period and that may precede severe cardiac dysfunction later in life. If our findings are confirmed in humans, this may have consequences for a large patient population and cardiac screening at young age may be indicated to enable secondary prevention.

Update on hemangiomas and vascular malformations

PURPOSE OF REVIEW

Our knowledge base in the area of vascular anomalies is growing rapidly. With greater understanding of classification and diagnosis, as well as with the numerous areas of research bringing further awareness on the complexity of these lesions, we are improving our ability to treat them. We will attempt in this article to summarize the developments in the field of vascular anomalies over the last year.

RECENT FINDINGS

Emphasis on correct classification is still a high priority in the literature and yet there remains a great deal of misinformation. Many new developments in the basic science of these lesions are allowing better understanding of why these lesions occur while improving our management in these patients. Advances in laser surgery as well as sclerotherapy techniques have improved our ability to treat extensive lesions and also improve patients' quality of life.

SUMMARY

Many new and exciting areas of discovery occur almost daily in the field of vascular anomalies. Due to the breadth of this topic, it is certain that not all articles can be reviewed however the author has tried to present the most recent and clinically relevant breakthroughs in the field.

Quantitative proteomic analysis of sokotrasterol sulfate-stimulated primary human endothelial cells

The endothelium forms a continuous monolayer at the interface between blood and tissue and contributes significantly to the sensing and transducing of signals between blood and tissue. New blood vessel formation, or angiogenesis, is initiated by the activation of endothelial cells and is an important process required for various pathological and physiological situations. This study used cleavable isotope-coded affinity tag reagents combined with mass spectrometry to investigate the molecular basis of a recently discovered angiogenesis-promoting steroid, sokotrasterol sulfate. Changes in the relative abundances of over 1000 proteins within human endothelial cells treated with sokotrasterol sulfate and vehicle-treated cells were identified and quantitated using this technique. A method that examines the entire ensemble of quantitative measurements was developed to identify proteins that showed a statistically significant change in relative abundance resulting from treatment with sokotrasterol sulfate. A total of 93 proteins was significantly up-regulated, and 37 were down-regulated in response to sokotrasterol sulfate stimulation of endothelial cells. Among the up-regulated proteins, several were identified that are novel to endothelial cells and are likely involved in cell communication and morphogenesis. These findings are consistent with a role for sokotrasterol sulfate in endothelial sprouting.

Mast Cells and Hemangioma

Hemangioma is a primary tumor of the microvasculature in which angiogenesis is initially excessive, followed by spontaneous regression of the newly formed vessels, with the cellular parenchyma gradually being replaced with fibrofatty tissue. Mast cells, which are highly heterogenous in terms of their morphology, function, and metabolic products, have been implicated in the pathophysiology of hemangioma. Csaba stain shows that mast cells are predominantly of the biogenic amine phenotype throughout the development of hemangioma. The predominance of this phenotype remains unaltered following successful steroid therapy, although their number increases fourfold. Mast cells, all of which stain positive for tryptase, and those that stain positive for chymase as well, have been identified in hemangioma biopsy specimens throughout the three developmental phases. The total number of mast cells is highest during the involuting phase, less in the involuted phase, and least in the proliferative phase. The proportion of mast cells that contain both tryptase and chymase decreases from the proliferative through involuting to the involuted phase. This decreasing proportion of mast cells that contain both tryptase and chymase with ongoing involution parallels that of progressive deposition of the extracellular matrix as indicated by increasing fibrosis and fatty deposition. The short-chain type VIII collagen, thought to play a key role in angiogenesis, has been detected throughout the developmental phases of hemangioma. It has been postulated that this collagen, which is produced early in new vessel development, provides a substratum to facilitate the migration of endothelial cells. It may also facilitate the deposition of other extracellular constituents and influence cell movement and the maintenance of cell phenotypes. The intracellular localization of type VIII collagen in mast cells only in the early proliferative phase suggests that there is an active synthesis by mast cells during this phase. The increasing extracellular localization during hemangioma development may be caused by an increased secretion of protein from intracellular stores. The increased number of mast cells during the involuting phase indicates that these cells may play a role in the regression of hemangioma. This is in contrast to the large body of evidence showing the proangiogenic role of mast cells. The proportion of proliferating mast cells decreases, whereas the proportion of mast cells positive for clusterin/apolipoprotein J increases with ongoing involution of hemangioma. Clusterin/apolipoprotein J expression has been considered as a prominent marker of apoptotic cell loss. The presence of clusterin/apolipoprotein J granules both in the adjacent endothelial cells and in capillary lumens suggests that mast cells may be secreting this apoptotic modulator to promote the regression of hemangioma. Certain effectors produced by mast cells may participate in the development of hemangioma. It has been proposed that one of the functions of mast cells is to release factors leading to the regression of hemangioma. The evidence suggests that although mast cells may have a function in the endothelial proliferation in hemangioma, they also play a crucial role in the regression of this tumor. However, the roles of mast cells in the life cycle of hemangioma are likely to be complex and may involve stimulators of angiogenesis in the proliferative phase but inhibitors in later phases.

Differential modulation of glucocorticoid action by FK506 in A549 cells

Glucocorticoids inhibit the release of eicosanoid pro-inflammatory mediators. The immunosuppressant FK506 is known to enhance many aspects of glucocorticoid action. In the present study we show that FK506 (1 microM or 10 microM) inhibits the release of arachidonic acid and prostaglandin E2 from A549 cells and also inhibits their proliferation. Simultaneous treatment of FK506 together with the glucocorticoids dexamethasone, methyl-prednisolone, fluticasone or mometasone (10 nM) enhances the growth inhibitory effect of these steroids. Furthermore, the simultaneous use of FK506 and these glucocorticoids similarly results in enhanced inhibition of arachidonic acid release. When pretreated for 2 h, FK506 enhances glucocorticoid inhibition of COX2 (cyclo-oxygenase 2) expression. However, when administered simultaneously, FK506 blocks glucocorticoid inhibition of COX2 expression. Nuclear uptake of glucocorticoid receptors mediated by glucocorticoids is also blocked by the simultaneous administration of FK506. These results suggest that the effect of simultaneous treatment of FK506 with glucocorticoids differs significantly from that where pre-treatment of the immunosuppressant is used. Recently, immunophilin interchange has been identified as a first step in glucocorticoid receptor activation following ligand activation. We show here that the FKB51 (FK506-binding protein 51)-FKB52 switch is differentially regulated by glucocorticoid and FK506 treatment strategy.