Small molecule targeting of the STAT5/6 Src homology 2 (SH2) domains to inhibit allergic airway disease.

Asthma is a chronic inflammatory disease of the lungs and airways and one of the most burdensome of all chronic maladies. Previous studies have established that expression of experimental and human asthma requires the IL-4/IL-13/IL-4 receptor α (IL-4Rα) signaling pathway, which activates the transcription factor STAT6. However, no small molecules targeting this important pathway are currently in clinical development. To this end, using a preclinical asthma model, we sought to develop and test a small-molecule inhibitor of the Src homology 2 domains in mouse and human STAT6. We previously developed multiple peptidomimetic compounds on the basis of blocking the docking site of STAT6 to IL-4Rα and phosphorylation of Tyr641 in STAT6. Here, we expanded the scope of our initial in vitro structure-activity relationship studies to include central and C-terminal analogs of these peptides to develop a lead compound, PM-43I. Conducting initial dose range, toxicity, and pharmacokinetic experiments with PM-43I, we found that it potently inhibits both STAT5- and STAT6-dependent allergic airway disease in mice. Moreover, PM-43I reversed preexisting allergic airway disease in mice with a minimum ED50 of 0.25 µg/kg. Of note, PM-43I was efficiently cleared through the kidneys with no long-term toxicity. We conclude that PM-43I represents the first of a class of small molecules that may be suitable for further clinical development against asthma.

Airway surface mycosis in chronic TH2-associated airway disease.

BACKGROUND: Environmental fungi have been linked to TH2 cell-related airway inflammation and the TH2-associated chronic airway diseases asthma, chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP), and allergic fungal rhinosinusitis (AFRS), but whether these organisms participate directly or indirectly in disease pathology remains unknown. OBJECTIVE: To determine the frequency of fungus isolation and fungus-specific immunity in patients with TH2-associated and non-TH2-associated airway disease. METHODS: Sinus lavage fluid and blood were collected from sinus surgery patients (n = 118) including patients with CRSwNP, patients with CRS without nasal polyps, patients with AFRS, and non-CRS/nonasthmatic control patients. Asthma status was determined from medical history. Sinus lavage fluids were cultured and directly examined for evidence of viable fungi. PBMCs were restimulated with fungal antigens in an enzyme-linked immunocell spot assay to determine total memory fungus-specific IL-4-secreting cells. These data were compared with fungus-specific IgE levels measured from plasma by ELISA. RESULTS: Filamentous fungi were significantly more commonly cultured in patients with TH2-associated airway disease (asthma, CRSwNP, or AFRS: n = 68) than in control patients with non-TH2-associated disease (n = 31): 74% vs 16%, respectively (P < .001). Both fungus-specific IL-4 enzyme-linked immunocell spot (n = 48) and specific IgE (n = 70) data correlated with TH2-associated diseases (sensitivity 73% and specificity 100% vs 50% and 77%, respectively). CONCLUSIONS: The frequent isolation of fungi growing directly within the airways accompanied by specific immunity to these organisms only in patients with TH2-associated chronic airway diseases suggests that fungi participate directly in the pathogenesis of these conditions. Efforts to eradicate airway fungi from the airways should be considered in selected patients.

Tracheobronchial mycosis in a retrospective case-series study of five status asthmaticus patients.

The etiology of status asthmaticus (SA), a complication of severe asthma, is unknown. Fungal exposure, as measured by fungal atopy, is a major risk factor for developing asthma, but the relationship of fungi in SA per se has not previously been reported. In this five patient retrospective case series study, lower respiratory tract cultures were performed on bronchoalveolar lavage or tracheal aspirate fluid, comparing standard clinical laboratory cultures with a specialized technique in which respiratory mucus was removed prior to culture. We show that mucolytic treatment allows an increased detection of fungal growth, especially yeast, from the lower airways of all SA patients. We also demonstrate that inhalation of the yeast Candida albicans readily induces asthma-like disease in mice. Our observations suggest that SA may represent a fungal infectious process, and support additional prospective studies utilizing anti-fungal therapy to supplement conventional therapy, broad-spectrum antibiotics and high-dose glucocorticoids, which can promote fungal overgrowth.

Vitamin D and asthma.

PURPOSE OF REVIEW: asthma is a disease that continues to carry a significant health burden on humanity. Vitamin D is thought to play a role in many chronic diseases as it may possess immunomodulatory properties. This article will review the role of vitamin D regulation on the immune system and its potential implication in the pathophysiology of asthma. RECENT FINDINGS: vitamin D receptors are present on many cells in the body, specifically peripheral blood mononuclear cells. Vitamin D has been shown to regulate the balance of several pro-inflammatory and anti-inflammatory responses in the immune system. Studies have suggested that prenatal vitamin D intake has an effect on childhood wheezing and asthma. Additionally, vitamin D may play a role in asthma exacerbations, and recent evidence also suggests its importance in steroid resistant asthma. SUMMARY: vitamin D has a complex role on the immune system and its regulation of various aspects of immunity has allowed speculation on its potential role in asthma. However, the net effect of vitamin D on the immune system and its role in asthma still remains unanswered. More research needs to address the diagnostic and therapeutic implications vitamin D may have in the future of asthma management.

Pediatric size phlebotomy tubes and transfusions in adult critically ill patients: a pilot randomized controlled trial.

BACKGROUND: Transfusion of red blood cells (RBC) is common, can have adverse effects, and is a costly and limited resource. Interventions that reduce iatrogenic blood losses could reduce transfusions. The objectives of this pilot trial were to assess the feasibility (acceptability of the intervention and suitability of eligibility criteria) and potential effectiveness of pediatric size phlebotomy tubes in adult critically ill patients. METHODS: We conducted a pilot, randomized controlled trial in the medical intensive care unit (ICU) of a university-affiliated, tertiary care referral hospital from November 2017 to September 2018. A total of 200 patients with hemoglobin of at least 7 g/dL and without bleeding were randomized to pediatric or adult size phlebotomy tubes. Stratification was according to baseline hemoglobin (7-9.49 g/dL, 9.5-11.99 g/dL, and 12 g/dL or greater). Acceptability was measured via the number of blood test recollections and the number of patients that discontinued the use of pediatric tubes. The suitability of patient eligibility criteria was determined by identifying baseline characteristics associated with RBC transfusions. Potential effectiveness was estimated from the time to RBC transfusion or to hemoglobin level below 7 g/dL. RESULTS: The use of pediatric tubes was acceptable as patients experienced a low number of tests recollections (on average 1 every 57 days), and none of the participants discontinued their use. The baseline hemoglobin category was the only factor that appeared to be independently associated with RBC transfusions. A total of 6 patients (6%) in the pediatric tube group and 11 patients (11%) in the adult tube group (hazard ratio, 0.69; 95% CI, 0.25 to 1.9) received an RBC transfusion or reached hemoglobin below 7 g/dL. Almost all of these patients (16 of 17 participants) had baseline hemoglobin of 7-9.49 g/dL. CONCLUSIONS: This pilot study suggests that pediatric phlebotomy tubes are acceptable to patients and can therefore be used in adult ICU patients. A future study should focus on patients with hemoglobin levels below 9.5 g/dL, as these patients have a high risk of transfusions. This intervention has the potential of being successful in selected patients. A definitive trial is warranted. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03286465. Retrospectively registered on September 18, 2017.

Oxygen distribution in the rabbit eye and oxygen consumption by the lens.

PURPOSE: Excessive exposure to oxygen has been proposed to be a risk factor for nuclear cataracts. For a better understanding of the metabolism of oxygen in the eye, oxygen distribution was mapped in the intraocular fluids, and the rate of oxygen consumption by the lens in rabbits breathing different levels of oxygen was calculated. METHODS: Young albino rabbits were anesthetized, intubated, and exposed to normoxic, hypoxic, or hyperoxic conditions. The hemoglobin saturation of the blood was monitored with a pulse oximeter, and arterial oxygen levels were measured with a blood gas analyzer. A fiberoptic optical oxygen sensor (optode) was used to determine oxygen levels in different regions of the eye. Oxygen flux across the posterior of the lens was calculated from the measured oxygen gradients in the vitreous chamber. RESULTS: Oxygen levels in the ocular fluids changed markedly when rabbits breathed air made hypoxic or hyperoxic. Oxygen levels were highest near the retinal vasculature, the iris vasculature, and the inner surface of the central cornea. Compared with nearby regions, oxygen levels were decreased in the aqueous humor closest to the pars plicata of the ciliary body and near the anterior chamber angle. Oxygen levels were generally lower closer to the lens. From the oxygen gradients in the vitreous body, oxygen consumption by the posterior half of the lens was calculated to be 0.2 to 0.4 microL/h under normoxic conditions. Oxygen consumption by the posterior of the lens increased in proportion to the amount of oxygen supplied. CONCLUSIONS: Intraocular oxygen is mostly derived from the retinal and iris vasculature and by diffusion across the cornea. Freshly secreted aqueous humor and the aqueous humor in the anterior chamber angle are relatively depleted of oxygen. The marked increase in oxygen consumption that occurs when the lens is exposed to increased oxygen is likely to result in the production of higher levels of reactive oxygen species and may provide a link between elevated oxygen levels and the risk of nuclear cataracts.

Long-Acting Beta Agonists Enhance Allergic Airway Disease.

Asthma is one of the most common of medical illnesses and is treated in part by drugs that activate the beta-2-adrenoceptor (ß2-AR) to dilate obstructed airways. Such drugs include long acting beta agonists (LABAs) that are paradoxically linked to excess asthma-related mortality. Here we show that LABAs such as salmeterol and structurally related ß2-AR drugs such as formoterol and carvedilol, but not short-acting agonists (SABAs) such as albuterol, promote exaggerated asthma-like allergic airway disease and enhanced airway constriction in mice. We demonstrate that salmeterol aberrantly promotes activation of the allergic disease-related transcription factor signal transducer and activator of transcription 6 (STAT6) in multiple mouse and human cells. A novel inhibitor of STAT6, PM-242H, inhibited initiation of allergic disease induced by airway fungal challenge, reversed established allergic airway disease in mice, and blocked salmeterol-dependent enhanced allergic airway disease. Thus, structurally related ß2-AR ligands aberrantly activate STAT6 and promote allergic airway disease. This untoward pharmacological property likely explains adverse outcomes observed with LABAs, which may be overcome by agents that antagonize STAT6.

Airway fibrinogenolysis and the initiation of allergic inflammation.

The past 15 years of allergic disease research have produced extraordinary improvements in our understanding of the pathogenesis of airway allergic diseases such as asthma. Whereas it was previously viewed as largely an immunoglobulin E-mediated process, the gradual recognition that T cells, especially Type 2 T helper (Th2) cells and Th17 cells, play a major role in asthma and related afflictions has inspired clinical trials targeting cytokine-based inflammatory pathways that show great promise. What has yet to be clarified about the pathogenesis of allergic inflammatory disorders, however, are the fundamental initiating factors, both exogenous and endogenous, that drive and sustain B- and T-cell responses that underlie the expression of chronic disease. Here we review how proteinases derived from diverse sources drive allergic responses. A central discovery supporting the proteinase hypothesis of allergic disease pathophysiology is the role played by airway fibrinogen, which in part appears to serve as a sensor of unregulated proteinase activity and which, when cleaved, both participates in a novel allergic signaling pathway through Toll-like receptor 4 and forms fibrin clots that contribute to airway obstruction. Unresolved at present is the ultimate source of airway allergenic proteinases. From among many potential candidates, perhaps the most intriguing is the possibility such enzymes derive from airway fungi. Together, these new findings expand both our knowledge of allergic disease pathophysiology and options for therapeutic intervention.

Cleavage of fibrinogen by proteinases elicits allergic responses through Toll-like receptor 4.

Proteinases and the innate immune receptor Toll-like receptor 4 (TLR4) are essential for expression of allergic inflammation and diseases such as asthma. A mechanism that links these inflammatory mediators is essential for explaining the fundamental basis of allergic disease but has been elusive. Here, we demonstrate that TLR4 is activated by airway proteinase activity to initiate both allergic airway disease and antifungal immunity. These outcomes were induced by proteinase cleavage of the clotting protein fibrinogen, yielding fibrinogen cleavage products that acted as TLR4 ligands on airway epithelial cells and macrophages. Thus, allergic airway inflammation represents an antifungal defensive strategy that is driven by fibrinogen cleavage and TLR4 activation. These findings clarify the molecular basis of allergic disease and suggest new therapeutic strategies.

New bronchodilators.

Bronchodilators are central in the treatment of airway diseases including chronic obstructive pulmonary disease (COPD). Bronchodilators in COPD aim to improve lung function, reduce symptoms, prevent exacerbation, and enhance quality of life. The majority of programs in development for novel bronchodilators are focused on enhancing existing targets to once daily dosing and improving their safety profiles. However, just as important are other programs that aim to discover novel pharmacologic targets such as EP4 receptor agonists, bitter taste receptors, and selective PDE inhibitors. Furthermore, existing and novel bronchodilators have become vital components of multiple combination therapies targeting COPD. This review will discuss emerging bronchodilators highlighting preclinical data and available clinical trials.