There has been much recent interest in the role of the vitamin D axis in lung disease, which includes vitamin D, vitamin D receptor (VDR) and vitamin D-binding protein (VDBP; also known as Gc-globulin). VDBP is a serum protein which has immunomodulatory functions relevant in the lung, predominantly relating to macrophage activation and neutrophil chemotaxis. Variations within its gene are also associated with airways disease, implying a role for the protein product in pathogenesis. Thus far the majority of evidence relates to chronic obstructive pulmonary disease (COPD), but is scant in other airways diseases, such as asthma and bronchiectasis. VDBP also acts as a scavenger protein to clear extracellular G-actin released from necrotic cells, which may be of relevance in severe lung infections and acute lung injury. Vitamin D protects against the development of cancer and tuberculosis, although optimal levels are unknown. The majority of circulating vitamin D is bound to VDBP, and its uptake into cells occurs in both bound and unbound forms, which suggests the role of VDBP warrants further study in these conditions as well. This article reviews the evidence of the role VDBP and its gene (GC) in a range of lung diseases, including asthma, COPD and tuberculosis.
Rationale and objectives. Severe asthma with fungal sensitization (SAFS) and allergic bronchopulmonary aspergillosis (ABPA) are progressive allergic fungal lung diseases whose effective treatment remains to be established. Current treatment with itraconazole is associated with a 40% failure rate and adverse events (AEs). We assessed the effect of voriconazole or posaconazole as second- and third-line therapies. Methods. We conducted a retrospective review of adult asthmatic patients with either ABPA or SAFS receiving voriconazole or posaconazole. Clinical, radiological, and immunological evaluation was used to assess response. Results. There were 25 patients, ABPA (n = 20) or SAFS (n = 5), 10 males, median age = 58 years. All patients had failed itraconazole (n = 14) or developed AEs (n = 11). There were 33 courses of therapy analyzed, 24 with voriconazole and 9 with posaconazole. Clinical response to voriconazole was observed in 17/24 (70%) patients at 3 months, 15/20 (75%) at 6 months, and 12/16 (75%) at 12 months compared with 7/9 (78%) at 3, 6, and 12 months for posaconazole. Eighteen of 24 (75%) patients discontinued oral corticosteroids (OCS), 12 of them within 3 months of therapy. Asthma severity was downgraded from severe to moderate (n = 8) and moderate to mild (n = 1) asthma in 9 of 24 (38%) asthmatic patients. There was a marked reduction in OCS and short-acting beta-2 agonist use, health-care utilization due to asthma, and improvement in overall health status. Furthermore, there was a statistically significant reduction in immunological markers appearing at 9 months (p = .008) for total IgE and at 12 months for radioallergosorbent test IgE for Aspergillus fumigatus (p = .0056). Six of 23 (26%) patients on voriconazole had AEs requiring discontinuation before 6 months compared with none on posaconazole (p = .15). Four relapsed (57%), one at 3 months and three at 12 months after discontinuation. Conclusion. Both voriconazole and posaconazole are potentially effective alternative treatment options for SAFS and ABPA and may improve asthma control and reduce severity, though larger prospective studies are required to support these retrospective study findings.
The mycobiome is highly variable. Highest loads of fungus are observed in severe asthmatics and the most common fungus is Aspergillus fumigatus complex. Individuals receiving steroid therapy had significantly higher levels of Aspergillus and total fungus in their bronchoalveolar lavage.
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