Streptococcus pneumoniae inhibits purinergic signaling and promotes purinergic receptor P2Y2 internalization in alveolar epithelial cells

Abstract

Edited by Roger J. Colbran Bacterial pneumonia is a global health challenge that causes up to 2 million deaths each year. Purinergic signaling plays a pivotal role in healthy alveolar epithelium. Here, we used fluorophore-based analysis and live-cell calcium imaging to address the question of whether the bacterial pathogen Streptococcus pneumoniae directly interferes with purinergic signaling in alveolar epithelial cells. Disturbed purinergic signaling might result in pathophysiologic changes like edema formation and atelectasis, which are commonly seen in bacterial pneumonia. Purine receptors are mainly activated by ATP, mediating a cytosolic calcium response. We found that this purinergic receptor P2Y 2-mediated response is suppressed in the presence of S. pneumoniae in A549 and isolated primary alveolar cells in a temperature-dependent manner. Downstream inositol 3-phosphate (IP 3) signaling appeared to be unaffected, as calcium signaling via protease-activated receptor 2 remained unaltered. S. pneumoniae-induced suppression of the P2Y 2-mediated calcium response depended on the P2Y 2 phosphorylation sites Ser-243, Thr-344, and Ser-356, which are involved in receptor desensitization and internalization. Spinning-disk live-cell imaging revealed that S. pneumoniae induces P2Y 2 translocation into the cytosol. In conclusion, our results show that S. pneumoniae directly inhibits purinergic signaling by inducing P2Y 2 phosphorylation and internalization, resulting in the suppression of the calcium response of alveolar epithelial cells to ATP, thereby affecting cellular integrity and function. The authors declare that they have no conflicts of interest with the contents of this article. This article contains Figs. S1-S4.

Pulmonary Micro-Ecological Changes and Potential Microbial Markers in Lung Cancer Patients

“…In vitro , investigations have revealed that S. pneumoniae can cause damage to alveolar epithelial cells ( 90 ). Similar results have confirmed that S. pneumoniae directly inhibits purinergic signaling by inducing purinergic receptor P2Y2 phosphorylation and internalization, which can lead to suppression of the calcium response of alveolar epithelial cells to ATP and affect the cellular integrity and function ( 91 ). Streptococcus may promote the development of lung cancer, although further experiments are needed for verification.…”

P2 Purinergic Signaling in the Distal Lung in Health and Disease

“…P2X 7 receptor has also been described to be required for the clearance of Streptococcus pneumoniae [ 52 ]. In a recent study, Oluto et al reported that Streptococcus pneumoniae inhibits purinergic signaling by increased internalization of P2Y 2 receptors in alveolar epithelial cells [ 202 ]. This might result in reduced surfactant secretion and subsequent alveolar collapse [ 95 ].…”

Possible role of purinergic signaling in COVID-19

“…Purinergic receptors are fundamental in understanding the COVID-19, because, in addition to being associated with the immune system, they have also been studied in the context of SARS, fibrosis, and blood clotting [ 25 ]. One of the receptors recently discussed in COVID-19 is P2X7, which is ionotropic, has an affinity for ATP, it is present in T cells, macrophages, neutrophils and DCs, and its function is to activate the cell types previously described and generate an inflammatory environment [ 11 , 20 , 26 ]. When activated by ATP, P2X7R rapidly promotes K + efflux, increased cytosolic Ca 2+ concentration, and release of cytokines, such as interleukin 1 beta (IL-1β) in neutrophils, in addition to activating the NLRP3 inflammasome [ 27 ].…”

“…When activated by ATP, P2X7R rapidly promotes K + efflux, increased cytosolic Ca 2+ concentration, and release of cytokines, such as interleukin 1 beta (IL-1β) in neutrophils, in addition to activating the NLRP3 inflammasome [ 27 ]. IL-1β was found at high levels in patients affected by COVID-19 [ 20 , 26 , 28 ]. In general, the outcome of P2X7R signaling is the activation of effector T cells, T regulatory cells, natural killer T cells (NKT), monocytes, macrophages, and DCs.…”

“…Regarding metabotropic receptors, findings in animal models point to an association between viral pneumonia and P2Y2R. One aspect of P2Y receptors is its association with G protein, so its prolonged stimulation can cause desensitization of the receptor [ 26 ]. This receptor is expressed in monocytes, DCs, and lymphocytes.…”