A new class of cyclosporin analogues for the treatment of asthma

Inhibitors of Cyclophilin A: Current and Anticipated Pharmaceutical Agents for Inflammatory Diseases and Cancers

Cyclophilin A, a widely prevalent cellular protein, exhibits peptidyl-prolyl cis-trans isomerase activity. This protein is predominantly located in the cytosol; additionally, it can be secreted by the cells in response to inflammatory stimuli. Cyclophilin A has been identified to be a key player in many of the biological events and is therefore involved in several diseases, including vascular and inflammatory diseases, immune disorders, aging, and cancers. It represents an attractive target for therapeutic intervention with small molecule inhibitors such as cyclosporin A. Recently, a number of novel inhibitors of cyclophilin A have emerged. However, it remains elusive whether and how many cyclophilin A inhibitors function in the inflammatory diseases and cancers. In this review, we discuss current available data about cyclophilin A inhibitors, including cyclosporin A and its derivatives, quinoxaline derivatives, and peptide analogues, and outline the most recent advances in clinical trials of these agents. Inhibitors of cyclophilin A are poised to enhance our comprehension of the molecular mechanisms that underpin inflammatory diseases and cancers associated with cyclophilin A. This advancement will aid in the development of innovative pharmaceutical treatments in the future.

Application of aerosol therapy in respiratory diseases in children: A Saudi expert consensus

The Saudi Pediatric Pulmonology Association (SPPA) is a subsidiary of the Saudi Thoracic Society (STS), which consists of a group of Saudi experts with well-respected academic and clinical backgrounds in the fields of asthma and other respiratory diseases. The SPPA Expert Panel realized the need to draw up a clear, simple to understand, and easy to use guidance regarding the application of different aerosol therapies in respiratory diseases in children, due to the high prevalence and high economic burden of these diseases in Saudi Arabia. This statement was developed based on the available literature, new evidence, and experts' practice to come up with such consensuses about the usage of different aerosol therapies for the management of respiratory diseases in children (asthma and nonasthma) in different patient settings, including outpatient, emergency room, intensive care unit, and inpatient settings. For this purpose, SPPA has initiated and formed a national committee which consists of experts from concerned specialties (pediatric pulmonology, pediatric emergency, clinical pharmacology, pediatric respiratory therapy, as well as pediatric and neonatal intensive care). These committee members are from different healthcare sectors in Saudi Arabia (Ministry of Health, Ministry of Defence, Ministry of Education, and private healthcare sector). In addition to that, this committee is representing different regions in Saudi Arabia (Eastern, Central, and Western region). The subject was divided into several topics which were then assigned to at least two experts. The authors searched the literature according to their own strategies without central literature review. To achieve consensus, draft reports and recommendations were reviewed and voted on by the whole panel.

Importance of microbial natural products and the need to revitalize their discovery

Microbes are the leading producers of useful natural products. Natural products from microbes and plants make excellent drugs. Significant portions of the microbial genomes are devoted to production of these useful secondary metabolites. A single microbe can make a number of secondary metabolites, as high as 50 compounds. The most useful products include antibiotics, anticancer agents, immunosuppressants, but products for many other applications, e.g., antivirals, anthelmintics, enzyme inhibitors, nutraceuticals, polymers, surfactants, bioherbicides, and vaccines have been commercialized. Unfortunately, due to the decrease in natural product discovery efforts, drug discovery has decreased in the past 20 years. The reasons include excessive costs for clinical trials, too short a window before the products become generics, difficulty in discovery of antibiotics against resistant organisms, and short treatment times by patients for products such as antibiotics. Despite these difficulties, technology to discover new drugs has advanced, e.g., combinatorial chemistry of natural product scaffolds, discoveries in biodiversity, genome mining, and systems biology. Of great help would be government extension of the time before products become generic.

Unexpected applications of secondary metabolites

Secondary metabolites have been found to have interesting applications over and above their well-known medical uses, e.g., as antimicrobials, etc. These alternative applications include antitumor, cholesterol-lowering, immunosuppressant, antiprotozoal, antihelminth, antiviral and anti-ageing activities. Polyene antibiotics, such as amphotericin B, are of use as antiprion agents, antitumor drugs and against leishmaniasis. Other microbial natural products that show antibiotic activity are used against cancer e.g., doxorubicin, neomycin, β-lactams, bleomycin and rapamycin. Macrolide antibiotics, such as erythromycin, clarithromycin and azithromycin, improve pulmonary function in patients suffering from panbioncholitis. Pigments like prodigiosin and shikonin have antitumor activity, while violacein has anti-ulcer and antitumor activity and also acts as an antiprotozoal agent. Statins, in addition to lowering cholesterol and LDL levels, also decrease elevated C-reactive protein (CRP) levels independent of their cholesterol effects. Immunosuppressants have many alternative effects: (i) Cyclosporin is proving useful in treatment of inflammatory disease such as asthma and muscular dystrophy. (ii) Rapamycin is extremely useful in preventing restenosis of stents grafted in balloon angioplasty. (iii) Tacrolimus and ascomycin help in treating inflammatory skin disease such as allergic contact dermatitis and psoriasis. Artemisinin, an antimalarial agent, is also showing antitumor activity. Other natural products, including those from plants (betulinic acid and shikonin), animals (bryostatins) and microbes (squalestatin and sophorolipids) have a multiplicity of potentially useful actions. Unexpected functions of known secondary metabolites are continuously being unraveled, and are fulfilling some of the needs of present day medicine and show great promise for the future.

The JAK-3 inhibitor CP-690550 is a potent anti-inflammatory agent in a murine model of pulmonary eosinophilia

Janus kinase 3 (JAK-3) is a tyrosine kinase that has been shown to participate in the signaling of several cytokines that are believed to play a role in allergic airway disease, e.g. IL-2, 4 and 9. The current study describes the immunosuppressive effects of CP-690550, a novel, small molecule inhibitor of JAK-3, in a murine model of allergic pulmonary inflammation. In vitro, CP-690550 potently inhibited IL-4 induced upregulation of CD23 (IC(50)=57 nM) and class II major histocompatibility complex (MHCII) expression (IC(50)=71 nM) on murine B cells. Repeat aerosol exposure to ovalbumin in wild-type mice sensitized to the antigen resulted in preferential recruitment of Th2-like cells (IL-4+ and IL-5+) into bronchoalveolar lavage fluid (BAL). The importance of IL-4 in the development of pulmonary eosinophilia was supported by a marked (90%) reduction in the influx of these cells in IL-4KO mice similarly sensitized and ovalbumin exposed. Animals dosed with CP-690550 (15 mg/kg/d) during the period of antigen sensitization and boost demonstrated marked reductions in BAL eosinophils and levels of IL-13 and eotaxin following ovalbumin aerosol exposure. The JAK-3 inhibitor (1.5-15 mg/kg/d) also effectively reduced the same parameters when administered during the period of antigen challenge. In contrast, the calcineurin inhibitor tacrolimus (10 mg/kg) was effective only when administered during the period of ovalbumin aerosol exposure. These data support the participation of JAK-3 in processes that contribute to pulmonary eosinophilia in the allergic mouse model. CP-690550 represents an intriguing novel therapy for treatment of allergic conditions associated with airway eosinophilia including asthma and rhinitis.

Update on glucocorticoid action and resistance

Extensive development of inhaled and oral glucocorticoids has resulted in highly potent molecules that have been optimized to target activity to the lung and minimize systemic exposure. These have proved highly effective for most asthmatic subjects, but despite these developments, there are a number of subjects with asthma who fail to respond to even high doses of inhaled or even oral glucocorticoids. Advances in delineating the fundamental mechanisms of glucocorticoid pharmacology, especially the concepts of transactivation and transrepression and cofactor recruitment, have resulted in better understanding of the molecular mechanisms whereby glucocorticoids suppress inflammation. The existence of multiple mechanisms underlying glucocorticoid insensitivity raises the possibility that this might indeed reflect different diseases with a common phenotype, and studies examining the efficacy of potential new agents should be targeted toward subgroups of patients with severe corticosteroid-resistant asthma who clearly require effective new drugs and other approaches to improved asthma control.

A rational approach to the management of severe refractory asthma

Severe refractory asthma is a heterogeneous condition with different patterns of severity and different reasons for loss of asthma control. The three main patterns include asthma with frequent exacerbations, asthma with irreversible airway obstruction, and asthma with reduced sensitivity or resistance to corticosteroids. Each of these patterns has distinct risk factors. The assessment of patients with severe asthma requires a systematic, diagnostic and management protocol. The majority of patients will benefit from thorough analysis and treatment of aggravating factors. In some patients with severe refractory asthma, in particular those with concomitant chronic rhinosinusitis, long-term administration of systemic corticosteroids may be necessary. In these patients all efforts should be directed towards reducing the dose of corticosteroids as much as possible. Although several corticosteroid-sparing agents and immunosuppressants have been proposed in the literature, none of these has gained complete acceptance in clinical practice, either because of limited efficacy or unacceptable adverse effects. Novel potent anti-inflammatory therapies aimed at reducing the need for systemic corticosteroids in patients with severe, refractory asthma are urgently needed.

New strategies in the treatment and prevention of allergic diseases

Allergic diseases (AD) are more prevalent today than 30 years ago but over the same period, few novel efficacious drugs have been discovered to treat, control or even cure these disorders. Topical or systemic glucocorticosteroids combined with symptom-relieving medications, such as beta 2 -adrenoceptor agonists, leukotriene inhibitors or antihistamines, are still the mainstay of antiallergic treatment. Modified glucocorticosteroids with less adverse effects, better bronchodilators and new selective mediator inhibitors may improve symptom control in the future. Only specific immunotherapy has shown potential for long-lasting disease-modifying effects. Immunomodulation is a therapeutic goal, aiming to modify the dominant helper T cell Type 2 inflammation to a helper T cell Type 1 response using modified allergens, mycobacteria or CpG oligodeoxynucleotides. Humanised monoclonal anti-IgE antibodies are an exciting new immunomodulatory medication that are expected to reach the clinical practice and have recently been licensed in Australia and the US. Advances in molecular, cellular and genetic research of the immunopathophysiology of AD have led to the development of new antagonists for cytokines, chemokines, receptors, second messengers and transcription factors that may become available for clinical use in the next 10 years. Specific diets supplemented with antioxidants or probiotics need further study but offer promise as safe and cheap preventative medicine. The strong genetic component of AD and the Human Genome Project have opened a new field of research, and modification or replacement of target genes has a curative potential with exciting new therapeutic developments in the years ahead.

Therapeutic potential of macrolide immunosuppressants in dermatology

Dermatologists are frequently presented with inflammatory dermatoses that are responsive to treatment with immunomodulating drugs. Corticosteroids, particularly when applied topically, have been the mainstay of treatment in the past. Their undoubted efficacy, however, has been undermined by problems with repeated use including tachyphylaxis and side effects such as skin atrophy and hypertension. Macrolide immunosuppressive drugs, originally used for prophylaxis of organ transplant rejection, have been shown to be effective in the treatment of inflammatory dermatoses. The original drugs used in dermatology in this class have their own limitations including poor absorption when used topically and their distinct side-effect profiles. A search for other immunosuppressive macrolide antibiotics has led to the development of new agents, which have enhanced profiles for the treatment of skin disease. This review discusses the main dermatoses that may be targeted by this class of drugs and summarises the topical and systemic macrolides either currently in use, in clinical trials or preclinical development.