Glucocorticoid induced the expression of mRNA and the secretion of lipocortin 1 in rat astrocytoma cells

Glucocorticoid Treatment in Acute Respiratory Distress Syndrome: An Overview on Mechanistic Insights and Clinical Benefit

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS), triggered by various pathogenic factors inside and outside the lungs, leads to diffuse lung injury and can result in respiratory failure and death, which are typical clinical critical emergencies. Severe acute pancreatitis (SAP), which has a poor clinical prognosis, is one of the most common diseases that induces ARDS. When SAP causes the body to produce a storm of inflammatory factors and even causes sepsis, clinicians will face a two-way choice between anti-inflammatory and anti-infection objectives while considering the damaged intestinal barrier and respiratory failure, which undoubtedly increases the difficulty of the diagnosis and treatment of SAP-ALI/ARDS. For a long time, many studies have been devoted to applying glucocorticoids (GCs) to control the inflammatory response and prevent and treat sepsis and ALI/ARDS. However, the specific mechanism is not precise, the clinical efficacy is uneven, and the corresponding side effects are endless. This review discusses the mechanism of action, current clinical application status, effectiveness assessment, and side effects of GCs in the treatment of ALI/ARDS (especially the subtype caused by SAP).

A Mechanistic Basis for the Beneficial Effects of Caloric Restriction On Longevity and Disease: Consequences for the Interpretation of Rodent Toxicity Studies

Caloric restriction in rodents has been repeatedly shown to increase life span while reducing the severity and retarding the onset of both spontaneous and chemically induced neoplasms. These effects of caloric restriction are associated with a spectrum of biochemical and physiological changes that characterize the organism's adaptation to reduced caloric intake and provide the mechanistic basis for caloric restriction's effect on longevity. Here, we review evidence suggesting that the primary adaptation appears to be a rhythmic hypercorticism in the absence of elevated adrenocorticotropin (ACTH) levels. This characteristic hypercorticism evokes a spectrum of responses, including reduced body temperature and increased metabolic efficiency, decreased mitogenic response coupled with increased rates of apoptosis, reduced inflammatory response, reduced oxidative damage to proteins and DNA, reduced reproductive capacity, and altered drug-metabolizing enzyme expression. The net effect of these changes is to (1) decrease growth and metabolism in peripheral tissues to spare energy for central functions, and (2) increase the organism's capacity to withstand stress and chemical toxicity. Thus, caloric restriction research has uncovered an evolutionary mechanism that provides rodents with an adaptive advantage in conditions of fluctuating food supply. During periods of abundance, body growth and fecundity are favored over endurance and longevity. Conversely, during periods of famine, reproductive performance and growth are sacrificed to ensure survival of individuals to breed in better times. This phenomena can be observed in rodent populations that are used in toxicity testing. Improvements over the last 30 years in animal husbandry and nutrition, coupled with selective breeding for growth and fecundity, have resulted in several strains now exhibiting larger animals with reduced survival and increased incidence of background lesions. The mechanistic data from caloric restriction studies suggest that these large animals will also be more susceptible to chemically induced toxicity. This creates a problem in comparing tests performed on animals of different weights and comparing data generated today with the historical database. The rational use of caloric restriction to control body weight to within preset guidelines is a possible way of alleviating this problem.

Effects of delayed delivery of dexamethasone-21-phosphate via subcutaneous microdialysis implants on macrophage activation in rats

Macrophage activation is of interest in the biomaterials field since macrophages with an M(Dex) characteristic phenotype, i.e., CD68(+)CD163(+), are believed to result in improved integration of the biomaterial as well as improved tissue remodeling and increased biomaterial longevity. To facilitate delivery of a macrophage modulator, dexamethasone-21-phosphate (Dex), microdialysis probes were subcutaneously implanted in male Sprague-Dawley rats. Dex localized delivery was delayed to the third day post implantation as a means to alter macrophage activation state at an implant site. To better elucidate the molecular mechanisms associated with M(Dex) macrophage activation, CCL2 was quantified in dialysates, gene expression ratios were determined from excised tissue surrounding the implant, histological analyses, and immunohistochemical analyses (CD68, CD163) were performed. Delayed Dex infusion resulted in the up-regulation of IL-6 at the transcript level in the tissue in contact with the microdialysis probe and decreased CCL2 concentrations collected in dialysates. Histological analyses showed increased cellular density as compared to controls in response to delayed Dex infusion. Dex delayed infusion resulted in an increased percentage of CD68(+)CD163(+), M(Dex), macrophages in the tissue surrounding the microdialysis probe as compared to probes that served as controls.

Development of the HPA axis: where and when do sex differences manifest?

Sex differences in the response to stress contribute to sex differences in somatic, neurological, and psychiatric diseases. Despite a growing literature on the mechanisms that mediate sex differences in the stress response, the ontogeny of these differences has not been comprehensively reviewed. This review focuses on the development of the hypothalamic-pituitary-adrenal (HPA) axis, a key component of the body's response to stress, and examines the critical points of divergence during development between males and females. Insight gained from animal models and clinical studies are presented to fully illustrate the current state of knowledge regarding sex differences in response to stress over development. An appreciation for the developmental timelines of the components of the HPA axis will provide a foundation for future areas of study by highlighting both what is known and calling attention to areas in which sex differences in the development of the HPA axis have been understudied.

Implications of glucocorticoid therapy in idiopathic inflammatory myopathies

Glucocorticoids are the cornerstone of therapy in patients with idiopathic inflammatory myopathies (IIM), despite adverse effects and suboptimal therapy success rates. Glucocorticoids are used in patients with IIM to suppress inflammatory and immune responses implicated in the pathogenesis of these diseases. Nevertheless, potential inhibitory effects of glucocorticoids on skeletal muscle mass, myogenesis and immune responses that promote skeletal muscle regeneration after muscle injury warrant attention. Glucocorticoids lead to skeletal muscle catabolism by modulating major pathways involved in regulating muscle mass. Glucocorticoids also inhibit muscle regeneration by decreasing myogenic cell proliferation and differentiation. Finally, glucocorticoids might have inhibitory effects on immune cells that have been shown to be an important component of the muscle regenerative response. Better understanding of the signalling pathways involved in restorative versus adverse effects of glucocorticoids in IIM could yield additional insight into the aetiopathogenesis of persistent muscle weakness in patients with IIM after glucocorticoid treatment, and help in the development of novel, targeted treatment options with fewer adverse effects.

Mechanisms of action of topical corticosteroids in psoriasis

Psoriasis is a lifelong, chronic, and immune-mediated systemic disease, which affects approximately 1-3% of the Caucasian population. The different presentations of psoriasis require different approaches to treatment and appropriate prescriptions according to disease severity. The use of topical therapy remains a key component of the management of almost all psoriasis patients, and while mild disease is commonly treated only with topical agents, the use of topical therapy as adjuvant therapy in moderate-to-severe disease may also be helpful. This paper focuses on the cutaneous mechanisms of action of corticosteroids and on the currently available topical treatments, taking into account adverse effects, bioavailability, new combination treatments, and strategies to improve the safety of corticosteroids. It is established that the treatment choice should be tailored to match the individual patient's needs and his/her expectations, prescribing to each patient the most suitable vehicle.

Characterization of ZK 245186, a novel, selective glucocorticoid receptor agonist for the topical treatment of inflammatory skin diseases

BACKGROUND AND PURPOSE

Glucocorticoids are highly effective in the therapy of inflammatory diseases. Their value, however, is limited by side effects. The discovery of the molecular mechanisms of the glucocorticoid receptor and the recognition that activation and repression of gene expression could be addressed separately opened the possibility of achieving improved safety profiles by the identification of ligands that predominantly induce repression. Here we report on ZK 245186, a novel, non-steroidal, low-molecular-weight, glucocorticoid receptor-selective agonist for the topical treatment of inflammatory dermatoses.

EXPERIMENTAL APPROACH

Pharmacological properties of ZK 245186 and reference compounds were studied in terms of their potential anti-inflammatory and side effects in functional bioassays in vitro and in rodent models in vivo.

KEY RESULTS

Anti-inflammatory activity of ZK 245186 was demonstrated in in vitro assays for inhibition of cytokine secretion and T cell proliferation. In vivo, using irritant contact dermatitis and T cell-mediated contact allergy models in mice and rats, ZK 245186 showed anti-inflammatory efficacy after topical application similar to the classical glucocorticoids, mometasone furoate and methylprednisolone aceponate. ZK 245186, however, exhibits a better safety profile with regard to growth inhibition and induction of skin atrophy after long-term topical application, thymocyte apoptosis, hyperglycaemia and hepatic tyrosine aminotransferase activity.

CONCLUSIONS AND IMPLICATIONS

ZK 245186 is a potent anti-inflammatory compound with a lower potential for side effects, compared with classical glucocorticoids. It represents a promising drug candidate and is currently in clinical trials.

Therapeutic approaches for control of transcription factors in allergic disease

The inflammatory response observed in allergic disease involves multiple cell types but is orchestrated in part by the T(H)2 cytokines IL-4, IL-5, and IL-13. In recent years, the transcription factors that control the expression and function of these cytokines have been elucidated, including signal transducer and activator of transcription 6, GATA3, nuclear factor of activated T cells, and nuclear factor kappaB. These molecules are attractive targets for therapeutic intervention because they regulate the expression of numerous effector molecules and functions simultaneously. For instance, the immunosuppressive agents glucocorticoids and cyclosporin A both function by repressing the activity of transcription factors through a variety of mechanisms. In this review we examine the role of each transcription factor in allergic disease and discuss approaches that have been taken to therapeutically interfere with transcription factor function in allergic disease.

Selective glucocorticoid receptor agonists (SEGRAs): novel ligands with an improved therapeutic index

Glucocorticoids are among the most successful therapies in the treatment of chronic inflammatory and autoimmune diseases. Their efficacy seems to be caused by the interference of the ligand-activated glucocorticoid receptor with many pro-inflammatory pathways via different mechanisms. The ubiquitous expression of the glucocorticoid receptor is a prerequisite for efficacy. Their main drawback, however, is due to their potential to induce adverse effects, in particular upon high dosage and prolonged usage. For the purpose reducing systemic side effects, topical glucocorticoids that act locally have been developed. Nevertheless, undesirable cutaneous effects such as skin atrophy persist from the use of topical glucocorticoids. Therefore a high medical need exists for drugs as effective as glucocorticoids but with a reduced side effect profile. Glucocorticoids function by binding to and activating the glucocorticoid receptor which positively or negatively regulates the expression of specific genes. Several experiments suggest that negative regulation of gene expression by the glucocorticoid receptor accounts for its anti-inflammatory action. This occurs through direct or indirect binding of the receptor to pro-inflammatory transcription factors that are already bound to their regulatory sites. The positive action of the receptor occurs through homodimer binding of the ligand receptor complex to discrete nucleotide sequences and this contributes to some of the adverse effects of the hormone. Glucocorticoid receptor ligands that promote the negative regulatory action of the receptor with reduced positive regulatory function should therefore show an improved therapeutic index. A complete separation of the positive from the negative regulatory activities of the receptor has so far not been possible because of the interdependent nature of the two regulatory processes. Nevertheless, recent understanding of the molecular mechanisms of the GR has triggered several drug discovery programs and these have led to the identification of dissociated GR-ligands. Such selective GR agonists (SEGRAs) are likely to enter clinical testing soon.

Insight into the molecular mechanisms of glucocorticoid receptor action promotes identification of novel ligands with an improved therapeutic index

Glucocorticoids are highly effective in the therapy of inflammatory and autoimmune disorders. Their beneficial action is restricted because of their adverse effects upon prolonged usage. Topical glucocorticoids that act locally have been developed to significantly reduce systemic side effects. Nonetheless, undesirable cutaneous effects such as skin atrophy persist from the use of topical glucocorticoids. There is therefore a high medical need for drugs as effective as glucocorticoids but with a reduced side-effect profile. Glucocorticoids function by binding to and activating the glucocorticoid receptor that positively or negatively regulates the expression of specific genes. Several experiments suggest that the negative regulation of gene expression by the glucocorticoid receptor accounts for its anti-inflammatory action. This occurs through direct or indirect binding of the receptor to transcription factors such as activator protein-1, nuclear factor-kappaB or interferon regulatory factor-3 that are already bound to their regulatory sites. The positive action of the receptor occurs through homodimer binding of the receptor to discrete nucleotide sequences and this possibly contributes to some of the adverse effects of the hormone. Glucocorticoid receptor ligands that promote the negative regulatory action of the receptor with reduced positive regulatory function should therefore show improved therapeutic potential. A complete separation of the positive from the negative regulatory activities of the receptor has so far not been possible because of the interdependent nature of the two regulatory processes. Nevertheless, considerable improvement in the therapeutic action of glucocorticoid receptor ligands is being achieved through the use of key molecular targets for screening novel glucocorticoid receptor ligands.

Proteomic characterization of harvested pseudopodia with differential gel electrophoresis and specific antibodies

Malignant gliomas (astrocytomas) are lethal tumors that invade the brain. Invasive cell migration is initiated by extension of pseudopodia into interstitial spaces. In this study, U87 glioma cells formed pseudopodia in vitro as cells pushed through 3 microm pores of polycarbonate membranes. Harvesting pseudopodia in a novel two-step method provided material for proteomic analysis. Differences in the protein profiles of pseudopodia and whole cells were found using differential gel electrophoresis (DIGE) and immunoblotting. Proteins from two-dimensional (2D) gels with M(R)'s of 20-100 kDa and pI's of 3.0-10.0 were identified by peptide mass fingerprinting analysis using mass spectrometry. For DIGE, lysates of pseudopodia and whole cells were each labeled with electrophilic forms of fluorescent dyes, Cy3 or Cy5, and analyzed as mixtures. Analysis was repeated with reciprocal labeling. Differences in protein distributions were detected by manual inspection and computer analysis. Topographical digital maps of the scanned gels were used for algorithmic spot matching, normalization of background, quantifying spot differences, and elimination of artifacts. Pseudopodial proteins in Coomassie-stained 2D gels included isoforms of glycolytic enzymes as the largest group, seven of 24 proteins. Peptide mass fingerprint analysis of DIGE gels demonstrated increased isoforms of annexin (Anx) I, AnxII, enolase, pyruvate kinase, and aldolase, and decreased mitochondrial manganese superoxide dismutase and transketolase in pseudopodia. Specific antibodies showed restricted immunoreactivity of the hepatocyte growth factor (HGF) alpha chain to pseudopodia, indicating localization of its active form. Met (the HGF receptor), actin, and total AnxI were increased in pseudopodial lysates on immunoblots. Increased constituents of the pseudopodial proteome in glioma cells, identified in this study as actin, HGF, Met, and isoforms of AnxI, AnxII, and several glycolytic enzymes, represent therapeutic targets to consider for suppression of tumor invasion.

Dexamethasone-induced and estradiol-induced CREB activation and annexin 1 expression in CCRF-CEM lymphoblastic cells: evidence for the involvement of cAMP and p38 MAPK

AIMS

Annexin 1 (ANXA1), a member of the annexin family of calcium-binding and phospholipid-binding proteins, is a key mediator of the anti-inflammatory actions of steroid hormones. We have previously demonstrated that, in the human lymphoblastic CCRF-CEM cell line, both the synthetic glucocorticoid hormone, dexamethasone (Dex), and the estrogen hormone, 17beta-estradiol (E2beta), induce the synthesis of ANXA1, by a mechanism independent of the activation of their nuclear receptors. Recently, it was reported that the gene coding for ANXA1 contains acAMP-responsive element (CRE). In this work, we investigated whether Dex and E2beta were able to induce the activation of CRE binding proteins (CREB) in the CCRF-CEM cells. Moreover, we studied the intracellular signalling pathways involved in CREB activation and ANXA1 synthesis in response to Dex and E2beta; namely, the role of cAMP and the p38 mitogen activated protein kinase (MAPK).

RESULTS

The results show that Dex and E2beta were as effective as the cAMP analogue, dBcAMP, in inducing CREB activation. On the contrary, dBcAMP induced ANXA1 synthesis as effectively as these steroid hormones. Furthermore, the cAMP antagonist, Rp-8-Br-cAMPS, and the specific p38 MAPK inhibitor,SB203580, effectively prevented both Dex-induced, E2beta-induced and dBcAMP-induced CREB activation and ANXA1 synthesis.

CONCLUSIONS

Taken together, our results suggest that,in CCRF-CEM cells, Dex-induced and E2beta-inducedANXA1 expression requires the activation of the transcription factor CREB, which in turn seems to be mediated by cAMP and the p38 MAPK. These findings also suggest that, besides the nuclear steroid hormone receptors, other transcription factors, namely CREB, may play important roles in mediating the anti-inflammatory actions of glucocorticoids and oestrogen hormones.

An annexin 1 N-terminal peptide activates leukocytes by triggering different members of the formyl peptide receptor family

The human N-formyl peptide receptor (FPR) is a key modulator of chemotaxis directing granulocytes toward sites of bacterial infections. FPR is the founding member of a subfamily of G protein-coupled receptors thought to function in inflammatory processes. The other two members, FPR-like (FPRL)1 and FPRL2, have a greatly reduced affinity for bacterial peptides or do not bind them at all, with FPRL2 being considered an orphan receptor so far. In this study we show that a peptide derived from the N-terminal domain of the anti-inflammatory protein annexin 1 (lipocortin 1) can activate all three FPR family members at similar concentrations. The annexin 1 peptide initiates chemotactic responses in human monocytes that express all three FPR family members and also desensitizes the cells toward subsequent stimulation with bacterial peptide agonists. Experiments using HEK 293 cells stably expressing a single FPR family member reveal that all three receptors can be activated and desensitized by the N-terminal annexin 1 peptide. These observations identify the annexin 1 peptide as the first endogenous ligand of FPRL2 and indicate that annexin 1 participates in regulating leukocyte emigration into inflamed tissue by activating and desensitizing different receptors of the FPR family.

Upregulation of annexins I, II, and V after traumatic spinal cord injury in adult rats

The posttraumatic inflammatory reaction contributes to progressive tissue damage after spinal cord injury (SCI). Annexins, a family of structurally related calcium- and phospholipid-binding proteins, have potent anti-inflammatory effects by inhibiting the activity of phospholipase A(2) (PLA(2)), a key enzyme responsible for inflammation and cytotoxicity. We investigated spatiotemporal expression of annexins I, II, and V after a contusive SCI using the New York University impact device (a 10-g rod, height 12.5 mm) in adult rats. Western blot analysis revealed that annexin I expression increased at 3 days after injury, peaked at 7 days (1.75-fold above the baseline level; P < 0.01), started to decline at 14 days, and returned to the baseline level at and beyond 28 days post-injury. The expression of annexin II started to increase at 3 days, reached its maximal level at 14 days (2.73-fold; P < 0.01), remained at a high level up to 28 days, and then declined to the basal level by 56 days after injury. Annexin V expression started at 3 days, reached its maximal level at 7 days (1.61-fold; P < 0.05) and remained at this level until 56 days after injury. RT-PCR results confirmed expression of all three annexins at the mRNA level after SCI. Immunohistochemistry and immunofluorescence double-labeling analyses revealed that increased annexins I, II, and V were localized in neurons and glial cells. The present study thus revealed increased expression of the three annexin isoforms after moderate contusive SCI. The precise role of annexins in posttraumatic inflammation and neuroprotection after SCI remains to be determined.

Interleukin-1beta induces the expression of lipocortin 1 mRNA in cultured rat cortical astrocytes

Lipocortin 1 (LC1) has been shown to increase in neuronal damage and act as a neuroprotectant and a neurotrophic factor. IL-1beta acts as a mediator of inflammation and has been reported as a potent inducer of various neurotrophic factors including nerve growth factor and fibroblast growth factor. In this study, we investigated the relationship between LC1 and IL-1beta in cultured rat astrocytes. Time-and dose-dependent experiments of IL-1beta on rat cortical astrocytes in culture revealed that the expression of LC1 mRNA was significantly augmented by IL-1beta at 8 h, 10 ng/ml. In addition, IL-1beta evoked an extracellular secretion of LC1 without its cytotoxic effects. The effect of IL-1beta was completely abolished when we treated cells with inhibitor of mitogen-activated protein kinases (MAPKs) (PD98059) (25 microM), phospholipase A(2) inhibitor mepacrine (30 microM) and protein synthesis inhibitor cycloheximide (CHX) (10 microg/ml). This suggests that induction of LC1 by IL-1beta is through a MAPKs and phospholipaseA(2) pathway and requires protein synthesis. These results indicate that IL-1beta released in the central nervous system (CNS) injury can stimulate the transcription of the LC1 gene. Subsequent synthesis and release of LC1 may provide trophic support to neurons and modulate the action of IL-1beta in brain damage.

Neurotrophic action of lipocortin 1 derived from astrocytes on cultured rat cortical neurons

The lipocortins are a family of structurally related proteins, namely an annexin family, that exerts a variety of cellular functions through Ca2+-dependent binding to phospholipase A2 [EC 3.1. 1.4], including a crucial role in the central nervous system (CNS) such as antipyrogenic, thermoregulatory and neuroprotective agents in vivo. To elucidate the paradigm of lipocortin 1 functions in the CNS, we have first demonstrated (1) the induction and subsequent extracellular secretion of LC1 by glucocorticoid in cultured rat astrocytes, and (2) neurotrophic activities (survival-promoting, neuritogenic and synaptogenic actions on rat cortical neurons) of recombinant LC1. Time-and dose-dependent experiments of a synthetic glucocorticoid, dexamethasone (DEX), on rat cortical astrocytes in culture revealed that the expression of the intracellular LC1 mRNA and protein were significantly augmented by DEX (1 microM). In addition, DEX evoked an extracellular secretion of LC1 without its cytotoxic effects. Furthermore, the recombinant LC1 appeared to promote not only the survival and neurite outgrowth but also the synaptogenesis of embryonal rat cortical neurons. These results suggest that LC1 induced and selectively released from astrocytes by either endogenously or exogenously introduced glucocorticoids may play a specific and essential role on development and regeneration of the central nervous system.