Lipid Laden Macrophages in Respiratory Disease

Role of alveolar nitric oxide in gastroesophageal reflux-associated cough: prospective observational study

BACKGROUND

Fractional exhaled nitric oxide (FeNO) measured at multiple exhalation flow rates can be used as a biomarker to differentiate central and peripheral airway inflammation. However, the role of alveolar nitric oxide (CaNO) indicating peripheral airway inflammation remains unclear in gastroesophageal reflux-associated cough (GERC).

OBJECTIVES

We aimed to characterize the changes in alveolar nitric oxide (CaNO) and determine its clinical implication in GERC.

DESIGN

This is a single-center prospective observational study.

METHODS

FeNOs at exhalation flow rates of 50 and 200 ml/s were measured in 102 patients with GERC and 134 patients with other causes of chronic cough (non-GERC). CaNO was calculated based on a two-compartment model and the factors associated with CaNO were analyzed. The effect of anti-reflux therapy on CaNO was examined in 26 GERC patients with elevated CaNO.

RESULTS

CaNO was significantly elevated in GERC compared with that in non-GERC (4.6 ± 4.4 ppb versus 2.8 ± 2.3 ppb, p < 0.001). GERC patients with high CaNO (>5 ppb) had more proximal reflux events (24 ± 15 versus 9 ± 9 episodes, p = 0.001) and a higher level of pepsin (984.8 ± 492.5 versus 634.5 ± 626.4 pg/ml, p = 0.002) in sputum supernatant than those with normal CaNO. More GERC patients with high CaNO required intensified anti-reflux therapy (χ2 = 3.963, p = 0.046), as predicted by a sensitivity of 41.7% and specificity of 83.3%. Cough relief paralleled a significant improvement in CaNO (8.3 ± 3.0 versus 4.8 ± 2.6 ppb, p < 0.001).

CONCLUSION

Peripheral airway inflammation can be assessed by CaNO measurement in GERC. High CaNO indicates potential micro-aspiration and may predict a necessity for intensified anti-reflux therapy.

Bronchoalveolar Lavage in a Pediatric Population

OBJECTIVES

The cytomorphologic findings of bronchoalveolar lavage (BAL) in pediatrics were correlated with clinical symptoms.

METHODS

Patient demographics, clinical symptoms/history, cytomorphologic findings, and oil red O (ORO) staining of 100 pediatric patients who underwent BAL between 2014 and 2016 were reviewed at a large academic institution.

RESULTS

Of the 100 patients (males/females, 62:38), the most common conditions for BAL included cough (46/100), reflux (39/100), pneumonia (30/100), dysphagia (22/100), asthma (19/100), and cystic fibrosis (15/100). Sixteen of 100 patients were admitted with pulmonary symptoms from the emergency department. Cytomorphologic findings showed acute inflammation in 37 BALs and chronic inflammation in 9. Abundant thick mucin was present in 3 cytology cases from patients with cystic fibrosis. Fungal elements were detected in 3 cases (Candida, Aspergillus, and Pneumocystis jirovecii) and viral effects (rhinovirus) in one. Thirty-seven of 100 had rare ORO-positive lipid-laden macrophages (LLMs), 7 of 100 had moderate LLMs, 11 of 100 had numerous LLMs, 18 of 100 had positive staining without the degree of staining, 25 of 100 had negative ORO staining, and 2 of 100 had noncontributory ORO staining. An iron stain was done on 15 BALs (2 positive, 9 negative, and 4 noncontributory).

CONCLUSIONS

BAL cytology is a useful tool in pediatrics to discriminate underlying causes of aerodigestive system conditions, while ORO staining may occasionally help.

Characterisation of a New Human Alveolar Macrophage-Like Cell Line (Daisy)

Purpose

There is currently no true macrophage cell line and in vitro experiments requiring these cells currently require mitogenic stimulation of a macrophage precursor cell line (THP-1) or ex vivo maturation of circulating primary monocytes. In this study, we characterise a human macrophage cell line, derived from THP-1 cells, and compare its phenotype to the THP-1 cells.

Methods

THP-1 cells with and without mitogenic stimulation were compared to the newly derived macrophage-like cell line (Daisy) using microscopy, flow cytometry, phagocytosis assays, antigen binding assays and gene microarrays.

Results

We show that the cell line grows predominantly in an adherent monolayer. A panel of antibodies were chosen to investigate the cell surface phenotype of these cells using flow cytometry. Daisy cells expressed more CD11c, CD80, CD163, CD169 and CD206, but less CD14 and CD11b compared with mitogen-stimulated THP-1 cells. Unlike stimulated THP-1 cells which were barely able to bind immune complexes, Daisy cells showed large amounts of immune complex binding. Finally, although not statistically significant, the phagocytic ability of Daisy cells was greater than mitogen-stimulated THP-1 cells, suggesting that the cell line is more similar to mature macrophages.

Conclusions

The observed phenotype suggests that Daisy cells are a good model of human macrophages with a phenotype similar to human alveolar macrophages.