Persistent Airway Hyperresponsiveness Following Recovery from Infection with Pneumonia Virus of Mice

Abstract

Respiratory virus infections can have long-term effects on lung function that persist even after the acute responses have resolved. Numerous studies have linked severe early childhood infection with respiratory syncytial virus (RSV) to the development of wheezing and asthma, although the underlying mechanisms connecting these observations remain unclear. Here, we examine airway hyperresponsiveness (AHR) that develops in wild-type mice after recovery from symptomatic but sublethal infection with the natural rodent pathogen, pneumonia virus of mice (PVM). We found that BALB/c mice respond to a limited inoculum of PVM with significant but reversible weight loss accompanied by virus replication, acute inflammation, and neutrophil recruitment to the airways. At day 21 post-inoculation, virus was no longer detected in the airways and the acute inflammatory response had largely resolved. However, and in contrast to most earlier studies using the PVM infection model, all mice survived the initial infection and all went on to develop serum anti-PVM IgG antibodies. Furthermore, using both invasive plethysmography and precision-cut lung slices, we found that these mice exhibited significant airway hyperresponsiveness at day 21 post-inoculation that persisted through day 45. Taken together, our findings extend an important and versatile respiratory virus infection model that can now be used to explore the role of virions and virion clearance as well as virus-induced inflammatory mediators and their signaling pathways in the development and persistence of post-viral AHR and lung dysfunction.

Differential Expression of Mitosis and Cell Cycle Regulatory Genes during Recovery from an Acute Respiratory Virus Infection

“…The development of a symptomatic but sublethal PVM model provided us with the opportunity to examine changes in the airway that persist after virus clearance and recovery. In our previous study [13], we found that mice that recovered from a sublethal dose of PVM developed significant airway hyperresponsiveness that could be detected as early as day 21 post-inoculation. Interestingly, and despite its impact on both weight loss and proinflammatory cytokine production, treatment with L. plantarum resulted in no significant reductions in total methacholine-induced airway resistance (R rs ) measured at this time point (Figure 1e).…”

“…Airway resistance (R rs ) was assessed as previously described [13]. Briefly, mice (day 21 after inoculation as per Figure 1a) were anesthetized by the intraperitoneal injection of ketamine and xylazine before undergoing tracheal intubation.…”

“…As noted above, we recently identified an inoculation strategy that generates a symptomatic but sublethal PVM infection in wild-type mice. Outcomes from this strategy include reversible weight loss accompanied by virus replication and ultimately seroconver-sion [13]. In earlier studies, we found that mice inoculated with the standard (lethal) dose of PVM were protected from the sequelae of severe infection by the direct administration of L. plantarum to the airways either before or immediately after inoculation [8][9][10][11][12].…”

“…We recently identified an inoculation strategy that resulted in symptomatic but sublethal PVM infection in wild-type mice [13]. Using this strategy, we found that all mice ultimately survived acute infection.…”

Application of Precision-Cut Lung Slices as an In Vitro Model for Research of Inflammatory Respiratory Diseases

“…PCLSs can be utilized as a platform for viral infection in vitro to explore inflammatory mediators and signaling pathways by observing the titer changes of the virus in lung tissues [ 54 ]. For instance, to study respiratory tract infections caused by the rhinovirus (RV), transcriptome analysis found that anti-rhinovirus preparations can initiate immune responses on PCLSs, thereby effectively inhibiting pro-inflammatory responses mediated by nuclear factor kappa B (NF-κB) and interferon [ 74 ].…”