Mass spectrometry detection of inhaled drug in distal fibrotic lung

Abstract

Background: Currently the only available therapies for fibrotic Interstitial Lung Disease are administered systemically, often causing significant side effects. Inhaled therapy could avoid these but to date there is no evidence that drug can be effectively delivered to distal, fibrosed lung. We set out to combine mass spectrometry and histopathology with rapid sample acquisition using transbronchial cryobiopsy to determine whether an inhaled drug can be delivered to fibrotic, distal lung parenchyma in participants with Interstitial Lung Disease.

Methods: Patients with radiologically and multidisciplinary team confirmed fibrotic Interstitial Lung Disease were eligible for this study. Transbronchial cryobiopsies and endobronchial biopsies were taken from five participants, with Interstitial Lung Disease, within 70 min of administration of a single dose of nebulised ipratropium bromide. Thin tissue cryosections were analysed by Matrix Assisted Laser Desorption/Ionization-Mass Spectrometry imaging and correlated with histopathology. The remainder of the cryobiopsies were homogenised and analysed by Liquid Chromatography-tandem Mass Spectrometry.

Results: Drug was detected in proximal and distal lung samples from all participants. Fibrotic regions were identified in research samples of four of the five participants. Matrix Assisted Laser Desorption/Ionization-Mass Spectrometry imaging showed co-location of ipratropium with fibrotic regions in samples from three participants.

Conclusions: In this proof of concept study, using mass spectrometry, we demonstrate for the first-time that an inhaled drug can deposit in distal fibrotic lung parenchyma in patients with Interstitial Lung Disease. This suggests that drugs to treat pulmonary fibrosis could potentially be administered by the inhaled route. Trial registration A prospective clinical study approved by London Camden and Kings Cross Research Ethics Committee and registered on clinicaltrials.gov (NCT03136120).

Keywords: Drug distribution; Interstitial fibrosis; MALDI-MS imaging; Transbronchial cryobiopsy.

Conflict of interest statement

The authors declare that they have no competing interests.

© 2022. The Author(s).

Figures

Fig. 1

Pre-Clinical Study in rats—MALDI-MS imaging of a 16 µm thick tissue section of rat lung and a 5 mm punched biopsy of rat lung, taken 65 min after a nebulised administration of ipratropium. Top Left—Photo of the region of the tissue from where the section had been cut (after removal of multiple punched biopsies). Top Right—MALDI-MS Image showing the distribution of the m/z 166 fragment ion, representative of ipratropium in Rat 7, section 13 (200 µm spatial resolution). The signal intensity for the ipratropium fragment ion at m/z 166.0 is represented as a concentration-dependent colour scale—white being highest concentrations. Bottom Left to Right: a Photo of 5 mm punched biopsy from rat lung. b Optical Image (digitally scanned image of rat lung section). c MALDI-MS image, 200 µm spatial resolution (and Signal Intensity Scale bar). d Histology image (Consecutive section)

Fig. 2

Representative CT scans from 4 patients prior to cryobiopsy from Right Lower Lobe in each case: A Patient 001. B Patient 003. C Patient 004. D Patient 006

Fig. 3

Representative MALDI-MS images, histology images and MS/MS for each participant. (TBC Samples). Each representative figure depicts the MALDI-MS image (100 µm pixel size) for the biopsy sample section and its corresponding histology image, a photograph of the frozen embedded biopsy sample and mass spectra showing both fragment ions (at m/z 123.9 and 166.0), obtained at the site of confirmed ipratropium detection (referred to as ipratropium or drug foci). For clarity, the MALDI-MS images for the detection of ipratropium have been adapted and the drug foci regions circled that are above the signal to noise threshold ratio 3:1 for both fragment ions (at m/z 123.9 and 166.0). The approximate location of these foci has been circled on the corresponding histology image

Fig. 4

Representative MALDI-MS images, histology images and MS/MS for each participant (endobronchial samples). Each representative figure depicts the MALDI-MS image (100 µm pixel size) for the biopsy sample section and its corresponding histology image, a photograph of the frozen embedded biopsy sample and mass spectra showing both fragment ions (at m/z 123.9 and 166.0), obtained at the site of confirmed ipratropium detection (referred to as ipratropium or drug foci)

Fig. 5

Images showing MALDI-MS imaging hit on consecutive sample sections, 4A32 (i) and 4A33 (ii) and approximate location of MALDI hit (middle). Bottom: A Co-location of MALDI-MS imaging and Histology in TBC and Zoomed-in region B depict the approximate location of the MALDI-MSI hit present within a fibrotic area of TBC sample 4A31, possibly co-located with a small airway. C and zoomed-in region D of TBC sample 5A23 illustrate lung architecture consistent with pulmonary fibrosis and the approximate location of the MALDI-MSI hits appear to co-locate with a small airway