New drugs targeting Th2 lymphocytes in asthma

Asthma represents a profound worldwide public health problem. The most effective anti-asthmatic drugs currently available include inhaled beta2-agonists and glucocorticoids and control asthma in about 90-95% of patients. The current asthma therapies are not cures and symptoms return soon after treatment is stopped even after long term therapy. Although glucocorticoids are highly effective in controlling the inflammatory process in asthma, they appear to have little effect on the lower airway remodelling processes that appear to play a role in the pathophysiology of asthma at currently prescribed doses. The development of novel drugs may allow resolution of these changes. In addition, severe glucocorticoid-dependent and resistant asthma presents a great clinical burden and reducing the side-effects of glucocorticoids using novel steroid-sparing agents is needed. Furthermore, the mechanisms involved in the persistence of inflammation are poorly understood and the reasons why some patients have severe life threatening asthma and others have very mild disease are still unknown. Drug development for asthma has been directed at improving currently available drugs and findings new compounds that usually target the Th2-driven airway inflammatory response. Considering the apparently central role of T lymphocytes in the pathogenesis of asthma, drugs targeting disease-inducing Th2 cells are promising therapeutic strategies. However, although animal models of asthma suggest that this is feasible, the translation of these types of studies for the treatment of human asthma remains poor due to the limitations of the models currently used. The myriad of new compounds that are in development directed to modulate Th2 cells recruitment and/or activation will clarify in the near future the relative importance of these cells and their mediators in the complex interactions with the other pro-inflammatory/anti-inflammatory cells and mediators responsible of the different asthmatic phenotypes. Some of these new Th2-oriented strategies may in the future not only control symptoms and modify the natural course of asthma, but also potentially prevent or cure the disease.

Trigeminal nasal-specific neurons respond to nerve growth factor with substance-P biosynthesis

BACKGROUND

Nerve growth factor (NGF) has been found to induce substance-P biosynthesis in large-diameter A-fibres vagal airway neurons. However, the effect of NGF on trigeminal neurons innervating the nasal mucosa of the mouse has not been investigated so far.

OBJECTIVE

NGF has been implicated in allergic diseases by modulating sensory nerves. Therefore, the present study investigated the effect of NGF on neuropeptides expression such as substance-P and glutamate in nasal trigeminal neurons.

METHODS

Using neuronal tracing in combination with double labelling immunohistochemistry the expression of substance-P, glutamate and neurofilament protein 68-kDa expression was examined in nasal-specific trigeminal neurons of BALB/c-mice.

RESULTS

The numbers of Fast blue-labelled trigeminal neurons expressing substance-P were significantly increased after NGF exposure (NGF-treated ganglia: 16.4 +/- 0.6% vs. control: 7.0 +/- 0.4%, P<or=0.001). NGF treatment-induced substance-P biosynthesis in neurofilament-positive (NGF-treated ganglia: 8.6 +/- 0.2% vs. control: 1.1 +/- 0.2%, P<or=0.001) as well as neurofilament-negative (NGF-treated ganglia: 7.8 +/- 0.6% vs. control: 5.9 +/- 0.4%, P=0.05) and non-glutamatergic neurons (NGF-treated ganglia: 11.8 +/- 1.9% vs. control 1.1 +/- 1.0%, P<or=0.001) 24 h after NGF exposure.

CONCLUSION

Under normal conditions, substance-P was expressed in nasal-specific neurofilament-negative, glutamatergic and C-fibre neurons. Nasal-specific trigeminal neurons respond to NGF treatment with substance-P biosynthesis in non-glutamatergic, neurofilament-positive as well as -negative neurons. These findings suggest that nasal-specific trigeminal neurons are composed of heterogenous subpopulations in relation to their peptide profiles and therefore may have different functions in neurogenic airway inflammation.

Proteases and Their Role in Chronic Inflammatory Lung Diseases

Proteases play an essential role in modulating the turnover of extracellular matrix. Furthermore, they are involved in the processing of various proteins thus regulating fundamental cellular functions such as apoptosis, cells growth and activation, protein secretion and phagocytosis. At the tissue and organ levels, proteases influence mechanisms including cell migration and invasion, cellular interactions and signal transduction as well as tissue formation and stabilization. Proteases are classified based on their catalytic mechanisms into serin, aspartic, metallo, threonin and cysteine proteases and are localized extracellularly, at the cellular surface, in the cytoplasm of cells or within specific subcellular structures such as lysosomes. The present review focuses on the specific functions of lysosomal cysteine proteases and the potential effects of modulators of cysteine protease activity.

Inhibition of signal transducer and activator of transcription 1 attenuates allergen-induced airway inflammation and hyperreactivity

BACKGROUND

Transcriptional factors of the signal transducer and activator of transcription (STAT) family play an important role in orchestrating immune reactions.

OBJECTIVE

The aim of the current study was to investigate the role of STAT-1 in murine allergen-induced sensitization and development of airway inflammation (AI) and airway hyperreactivity (AHR), cardinal features of bronchial asthma.

METHODS

BALB/c mice were systemically sensitized to ovalbumin and challenged with ovalbumin through the airways. Decoy oligonucleotide (ODN) specific for STAT-1 was applied once locally to the airways of sensitized animals before allergen airway challenges.

RESULTS

Single application of decoy ODN markedly and significantly reduced numbers of eosinophils and lymphocytes in bronchoalveolar lavage fluids compared with those seen in sensitized and challenged animals receiving mutant control ODN. Associated with this decrease in eosinophilic AI were significantly reduced levels of IL-5 in BAL fluid, of CD40 expression in peribronchial infiltrates, and of vascular cell adhesion molecule 1 expression in vascular endothelial cells, respectively. In addition, development of AHR after allergen sensitization and airway challenges was effectively abolished after local STAT-1 decoy ODN treatment.

CONCLUSION

The data indicate that a decoy ODN neutralizing STAT-1 effectively inhibits allergen-induced AI and AHR, probably by attenuating upregulation of costimulatory and adhesion molecules, and suggest a significant role of STAT-1 in asthma pathology.

[Hypo-osmolar hyponatremia as the chief symptom in hypothyroidism]

CASE HISTORY AND DIAGNOSIS

A 75-year-old male patient presented with a history of anorexia, muscle weakness, and increasing memory loss. He had mild pedal edema and decreased deep tendon reflexes. As the laboratory tests showed hypoosmolar hyponatremia and urinary sodium within the normal range, a syndrome of inappropriate ADH secretion (SIADH) was presumed. While neither the medical history nor any of the diagnostic procedures revealed any underlying pathology explaining the SIADH, laboratory tests showed significant hypothyroidism. Hypothyroid states are associated with significant changes in renal function, one of which is hypoosmolar hyponatremia.

TREATMENT AND COURSE

Treatment included fluid restriction and hormone substitution and resulted in a quick correction of the hyponatremia and a clear improvement of the patient's cognitive function.

CONCLUSION

It is concluded that the diagnosis of SIADH should only be made after thorough investigation of the adrenal and thyroid hormone status.

Expression of heme oxygenase isoenzymes 1 and 2 in normal and asthmatic airways: effect of inhaled corticosteroids

Heme oxygenase (HO) is considered to be an antioxidant enzyme that catabolizes heme to produce carbon monoxide (CO) and biliverdin. We determined the expression and distribution of HO-1 and HO-2, two isoenzymes of HO, in the airways of patients with asthma, and determined the effect of inhaled corticosteroid therapy. Immunostaining for both enzymes was widely distributed in the airways' submucosa, particularly in airway epithelium and submucosal macrophages (CD68(+)) as determined by double immunostaining. There was no difference in intensity and extent of staining in biopsies from normal subjects (n = 10) and subjects with asthma (n = 10). Following 1 mo of treatment with inhaled corticosteroids (budesonide 1,600 microg/d), there was no significant change in the expression and distribution of either HO-1 or HO-2 in the airways' submucosa in eight subjects with mild asthma, despite a significant reduction in airway eosinophils and a reduction in bronchial responsiveness to methacholine. Levels of exhaled nitric oxide were significantly reduced, but exhaled CO levels remained unchanged by the treatment. Treatment with a placebo inhaler (n = 8) had no effects on these parameters. Thus, both HO-1 and HO-2 are extensively distributed equally in normal subjects and subjects with asthma, and are not modulated by inhaled corticosteroid therapy in subjects with asthma. HO may be an important endogenous antioxidant enzyme.