Vitamin D Deficiency and Radiological Findings in Adult Non-Cystic Fibrosis Bronchiectasis

Relation between vitamin D deficiency and Pseudomonas aeruginosa colonization in patients with bronchiectasis

BACKGROUND

The relationship between vitamin D deficiency and Pseudomonas aeruginosa (P. aeruginosa) colonization in bronchiectasis patients is not well understood.

METHODS

This study was conducted at Shanghai Pulmonary Hospital from June 2014 to May 2018. Serum 25-hydroxyvitamin D levels were measured in patients with bronchiectasis, and clinical data including sputum culture results were collected. To investigate the relationship between vitamin D levels and P. aeruginosa colonization, we conducted correlation analysis and logistic regression. Additionally, in vitro experiments with bone marrow-derived macrophages (BMDMs) infected with P. aeruginosa strain PAO1 were performed to further explore the influence of vitamin D on the bacterial infection and inflammatory response.

RESULTS

Among the 195 patients with bronchiectasis, 83.1% (162/195) were vitamin D deficient. A significant negative correlation was observed between serum vitamin D levels and the BSI (Bronchiectasis Severity Index) score. Patients with vitamin D deficiency showed higher rates of P. aeruginosa colonization compared to those with adequate vitamin D levels. Female gender and vitamin D deficiency were identified as risk factors for P. aeruginosa colonization in patients with bronchiectasis. Additionally, serum interleukin (IL)-1β levels were significantly elevated in the vitamin D-deficiency group. In vitro experiments, 1,25-dihydroxyvitamin D [1,25D] was shown to inhibit PAO1 phagocytosis in BMDMs and to suppress IL-1β secretion.

CONCLUSIONS

Vitamin D deficiency was strongly associated with an increased risk of P. aeruginosa colonization in patients with bronchiectasis. Furthermore, vitamin D demonstrated protective effects by reducing P. aeruginosa survival in cells and modulating the inflammatory dysregulation induced by the bacterium.

No causal association between serum vitamin D levels and bronchiectasis: A Mendelian randomization analysis

Observational studies have reported an association between Vitamin D deficiency and an increased risk of bronchiectasis. This study aims to investigate the causal relationship between Vitamin D levels and bronchiectasis using a 2-sample Mendelian randomization (MR) analysis. Data from 2 genome-wide association studies (GWAS) based on European ancestry were analyzed: serum vitamin D levels (sample size = 441,291 [UK Biobank]) and bronchiectasis (sample size = 187,830 [cases = 1107, controls = 186,723; FinnGen]). Inverse-variance weighted (IVW) analysis was primarily used to assess the causal effect of 25(OH)D levels on bronchiectasis, supplemented by Mendelian randomization Egger regression (MR-Egger), weighted median, simple mode, and weighted mode analyses. Additionally, MR-Egger intercept test and MR-Pleiotropy Residual Sum and Outlier methods were implemented to determine pleiotropy, and Cochran's Q test was conducted for heterogeneity testing. Leave-one-out analysis and Bayesian weighted Mendelian randomization was also used to assess the robustness of the results. The MR analysis suggested no significant causal effects of serum 25(OH)D levels on bronchiectasis using the IVW method (odds ratio = 1.550; 95% confidence interval [CI]: 0.908-2.315; P = .120). These results were consistent across MR-Egger regression, weighted median, simple mode, and weighted mode analyses. No significant heterogeneity, pleiotropy, or bias was detected in instrumental variables. Additionally, no evidence supported the causal effects of bronchiectasis on serum vitamin D levels (β = -0.002, 95% CI: -0.007 to 0.003; P = .463). Our study found no significant causal association between serum 25(OH)D levels and bronchiectasis, in either direction. A larger sample-sized randomized controlled trial (RCT) is needed to further investigate this potential causal relationship.

25-Hydroxy vitamin D and body composition are associated with pulmonary function in non-cystic fibrosis bronchiectasis: A cross-sectional study

BACKGROUND

Previous studies have emphasized the effects of vitamin D on the lung function of cystic fibrosis (CF) adult patients. The main aim of the present study sought to determine the association between circulating 25-hydroxyvitamin D (25-OH D) concentration and clinical outcomes in non-cystic fibrosis (non-CF) bronchiectasis subjects. Secondary, we assessed the possible relationship between body composition and respiratory dysfunction in these patients.

MATERIALS AND METHODS

Sixty-two non-CF bronchiectasis patients (24 male/38 female), aged 18-72, were recruited in this cross-sectional study. Anthropometric indices, lung function tests, and bronchiectasis severity valuations were determined. Body composition, including Mid-arm muscle circumference (MAMC, cm) was calculated using triceps skinfold (TSF,mm) and mid-arm circumference (MAC,cm) under the reference formula. Then serum 25-hydroxyvitamin D concentration and C-reactive protein level were measured. The correlation between vitamin D level and pulmonary function and disease exacerbation tests was primarily assessed. Additionally, we evaluated the correlation between body composition and lung function tests.

RESULTS

Circulating 25-hydroxyvitamin D status positively was correlated with lung function tests, including FEV₁ (r = 0.30, p value = 0.035) and FVC (r = 0.36, p value = 0.011), and also be associated with the extent of pulmonary involvement (r = -0.34, p value = 0.03). There was a significant negative correlation between percentage body fat and respiratory function, FEV₁/FVC ratio (r = -0.43, p value < 0.001). In contrast, there was a strong correlation between skeletal muscle mass and pulmonary function tests (r = 0.26, p value = 0.04).

CONCLUSION

There is a positive association between low 25-hydroxyvitamin D status and lung dysfunction in participants with non-CF bronchiectasis. The pulmonary dysfunction also correlated with more percentage body fat and low skeletal muscle mass in these patients. Therefore, the evaluation of body composition and serum vitamin D are suggested in the disease management of the patients with non-CF bronchiectasis. However, these associations should be interpreted with caution due to the likelihood of reverse causation. More high-quality prospective studies are warranted to confirm our observations and determine the mechanisms underlying these findings.

Bronchiectasis-Could Immunonutrition Have a Role to Play in Future Management?

Bronchiectasis is a chronic condition in which areas of the bronchial tubes become permanently widened predisposing the lungs to infection. Bronchiectasis is an age-associated disease with the highest prevalence in people older than 75 years. While the prevalence of bronchiectasis is higher in males, disease is more severe in females who have a poorer prognosis. The overall prevalence of the disease is thought to be rising. Its aetiology is multi-faceted, but a compromised immune system is now thought to play a central role in the pathology of this disease. Research has begun to study the role of malnutrition and certain nutrients-vitamin D and zinc-along with the role of the lung microbiome in relation to the management of bronchiectasis. Given this, the present mini review sets out to provide an overview of the state-of-the-art within the field, identify research gaps and pave the way for future developments and research investment within this field.