Spatiotemporal quantification of cell dynamics in the lung following influenza virus infection

Abstract

Abstract. Lung injury caused by influenza virus infection is widespread. Understanding lung damage and repair progression post infection requires quantitative spatiotemporal information on various cell types mapping into the tissue structure. Based on high content images acquired from an automatic slide scanner, we have developed algorithms to quantify cell infiltration in the lung, loss and recovery of Clara cells in the damaged bronchioles and alveolar type II cells (AT2s) in the damaged alveolar areas, and induction of pro-surfactant protein C (pro-SPC)-expressing bronchiolar epithelial cells (SBECs). These quantitative analyses reveal: prolonged immune cell infiltration into the lung that persisted long after the influenza virus was cleared and paralleled with Clara cell recovery; more rapid loss and recovery of Clara cells as compared to AT2s; and two stages of SBECs from Scgb1a1 þ to Scgb1a1 − . These results provide evidence supporting a new mechanism of alveolar repair where Clara cells give rise to AT2s through the SBEC intermediates and shed light on the understanding of the lung damage and repair process. The approach and algorithms in quantifying cell-level changes in the tissue context (cell-based tissue informatics) to gain mechanistic insights into the damage and repair process can be expanded and adapted in studying other disease models.

Multiple cells-of-origin of mutant K-Ras–induced mouse lung adenocarcinoma

“…Lineage-tracing experiments performed in steady-state conditions and in response to lung injury clearly demonstrated that CC10 + SPC + putative BASCs are unable to give rise to SPC + alveolar cells (19). However, under specific conditions (such as K-RasG12D expression as we report here) as well as under inflammatory stress as reported by the group of Jianzhu Chen (20), such transdifferentiation might nevertheless occur. Occasionally, we observed apparently normal alveolar cells in the vicinity of BADJ regions of Ad5-CC10-Cre switched K-Ras LSL-G12D/+ mice, suggesting that KRasG12D expression in a subpopulation of CC10 + cells resident in the BADJ region can permit cells to undergo AT2 cell differentiation, possibly facilitated by an inflammatory response induced by the adenovirus.…”

Epigenetic and Transcriptomic Regulation of Lung Repair during Recovery from Influenza Infection

“…These findings are in line with advance temporal imaging studies that demonstrate increased lung capillary leak at 21 days after infection. 23,24 Further, others have shown disruption in lung antigen-presenting cell populations after primary influenza infection. 25 Although we cannot say which event is provoking the other (inflammation leading to extended disrepair or vice versa), the lung remains in an extended state of frustrated inflammation and repair, resulting in increased fibrotic gene expression.…”

Aging exacerbates damage and delays repair of alveolar epithelia following influenza viral pneumonia

“…To compare damage and repair of bronchiolar and alveolar epithelia between young and aged mice, we quantified the changes of club cells, AT1s and AT2s over time by calculating the club cell coverage index, AT1 coverage index and AT2 relative density [27]. All three indices were based on analysis of immunofluorescent images of lung sections (see Materials and methods for details) in order to preserve spatial relationships among different cell types in the tissue.…”

“…Following infection, club cells are induced to differentiate into AT2s via SBECs [12,25], and we therefore compared the induction of SBECs [27] between aged and young mice. The induction of SBECs is quantified as the percentage of SBEC-containing bronchioles among the total bronchioles, measured in immunofluorescent images of lung sections (see Materials and methods for details).…”

“…In this study, we used automated image analysis [27] to quantify the damage and regeneration of club cells, AT1s, AT2s, and SBECs in young and aged mice following influenza infection. Our results show that although there is no difference in the extent of damage and kinetics of regeneration of club cells between young and aged mice, damage to AT1s and AT2s is more extensive, and regeneration of AT2s is significantly delayed in aged mice as compared to young mice.…”