MALDI-MSI spatially maps N-glycan alterations to histologically distinct pulmonary pathologies following irradiation

Abstract

Radiation-induced lung injury is a highly complex combination of pathological alterations that develop over time and severity of disease development is dose-dependent. following exposures to lethal doses of irradiation, morbidity and mortality can occur due to a combination of edema, pneumonitis and fibrosis. Protein glycosylation has essential roles in a plethora of biological and immunological processes. Alterations in glycosylation profiles have been detected in diseases ranging from infection, inflammation and cancer. We utilized mass spectrometry imaging to spatially map N-glycans to distinct pathological alterations during the clinically latent period and at 180 days post-exposure to irradiation. Results identified alterations in a number of high mannose, hybrid and complex N-glycans that were localized to regions of mucus and alveolar-bronchiolar hyperplasia, proliferations of type 2 epithelial cells, accumulations of macrophages, edema and fibrosis. The glycosylation profiles indicate most alterations occur prior to the onset of clinical symptoms as a result of pathological manifestations. Alterations in five N-glycans were identified as a function of time postexposure. Understanding the functional roles n-glycans play in the development of these pathologies, particularly in the accumulation of macrophages and their phenotype, may lead to new therapeutic avenues for the treatment of radiation-induced lung injury. Radiation-induced lung injury (RILI) is a complex combination of pathologies that include vascular damage, epithelial cell death followed by hyper-proliferation, edema, and mixed immune infiltrations resulting in pneumonitis and an aberrant wound-healing processes that ultimately lead to the development of pulmonary fibrosis 1-4. Accidental or intentional exposures to high doses of ionizing radiation results in RILI, which contributes to increased risk of mortality within months 3,4. RILI is also a common side effect of thoracic radiotherapy for treatment of malignancies; it often limits curative therapeutic strategies 1,5. Whereas RILI due to radiotherapy can be controlled to prevent mortality, accidental or intentional exposures to lethal doses of ionizing radiation result in significant lung disease development 3,6-8. To date there are no Food and Drug Administration (FDA) approved therapeutic options to treat or mitigate RILI and the molecular mechanisms leading to the development of pulmonary fibrosis remain incompletely understood. Protein glycosylation is a post-translational modification that plays essential biological roles in structural and modulatory processes, and cell-cell recognition 9. More specifically, glycoproteins are involved in protein folding, molecular trafficking and clearance, and secretion processes 10-12. On the cell surface, membrane-bound glycoproteins are binding ligands for host-host interactions that include cell adhesion, receptor activation and extracellular matrix molecules, and host-pathogen interactions that enable bacteria and viruses to attach and gain entry...

Spatial Mapping of Plant N-Glycosylation Cellular Heterogeneity Inside Soybean Root Nodules Provided Insights Into Legume-Rhizobia Symbiosis

“…The N -glycan spatial profiling using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) has emerged over the past few years as a powerful approach in clinical research for insight into aberrant N -glycan structures in specific cell types and histopathological regions during disease progression (Carter et al, 2020 ; Conroy et al, 2021 ; Grzeski et al, 2022 ; Malaker et al, 2022 ; Zhang et al, 2022 ). The method relies on spraying the enzyme peptide N -glycanase (PNGase) over formalin-fixed paraffin-embedded (FFPE) tissue sections to in-situ release the N -linked carbohydrates from their carrier proteins.…”

Cervical Spinal Cord Injury Leads to Injury and Metabolic Dysfunction of the Lung

“…N-linked glycan biosynthesis is an understudied facet of glucose metabolism. In the lung, N-linked glycans are crucial for the differentiation of bronchoalveolar stem and alveolar type 2 cells to form the alveolar and bronchiolar lining [37][38][39] . Further, N-linked glycans are critical components of mucins and surfactant proteins that maintain the liquid-air interface, reduce surface tension, and provide lubrication for the mechanical action of the lung 40,41 .…”

Therapeutic and diagnostic targeting of fibrosis in metabolic, proliferative and viral disorders

“…In this context, emerging imaging techniques such as matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) hold potential to visualize the spatial distribution of macromolecules which might represent distinct molecular signatures (e.g., glycan alternations) in chemoradiation-induced fibrosis (Fig. 8c; image 10-12) [312].…”

“…Color-coding: the analysis of manuscripts described in section 4.2 reveal the frequency in which each organ and imaging modality are investigated and used for the detection of fibrosis in cancer; light red = low frequency; red = medium frequency; dark red = high frequency. All images were adapted with permission [300,302,303,309,312,314].…”