P2rx4 deficiency in mice alleviates allergen-induced airway inflammation

Abstract

Compelling evidences point out a crucial role for extracellular nucleotides such as adenosine triphosphate (ATP) during inflammatory conditions. Once released into the extracellular space, ATP modulates migration, maturation and function of various inflammatory cells via activating of purinergic receptors of the P2Y- and P2X- family. P2RX4 is an ATP-guided ion channel expressed on structural cells such as alveolar epithelial and smooth muscle cells as well as inflammatory cells including macrophages, dendritic cells (DCs) and T cells. P2RX4 has been shown to interact with P2RX7 and promote NLRP3 inflammasome activation. Although P2RX7 has already been implicated in allergic asthma, the role of P2RX4 in airway inflammation has not been elucidated yet. Therefore, we used a selective pharmacological antagonist and genetic ablation to investigate the role of P2RX4 in an ovalbumin (OVA) driven model of allergen-induced airway inflammation (AAI). Both, P2RX4 antagonist 5-BDBD treatment and P2rx4 deficiency resulted in an alleviated broncho alveolar lavage fluid eosinophilia, peribronchial inflammation, Th2 cytokine production and bronchial hyperresponsiveness. Furthermore, P2rx4-deficient bone marrow derived DCs (BMDCs) showed a reduced IL-1ß production in response to ATP accompanied by a decreased P2rx7 expression and attenuated Th2 priming capacity compared to wild type (WT) BMDCs in vitro. Moreover, mice adoptively transferred with P2rx4-deficient BMDCs exhibit a diminished AAI in vivo. In conclusion our data suggests that P2RX4-signaling contributes to AAI pathogenesis by regulating DC mediated Th2 cell priming via modulating IL-1ß secretion and selective P2RX4-antagonists might be a new therapeutic option for allergic asthma.

AP2rx7passenger mutation affects the vitality and function of immune cells in P2X4ko and other transgenic mice

“…This finding was consistent in both male and female mice. Similar observations have been made in prior studies: BMDCs from P2rx4 tm1Rass were reported to exhibit a decreased P2rx7 mRNA expression (Zech et al, 2016) and macrophages from P2rx4 tm1Rass showed a reduced pore formation capacity in response to ATP stimulation (Pérez-Flores et al, 2015). At last, our finding that microglia from B6 P2X4ko mice express similar level of P2X7 compared to B6 WT also confirms an earlier report (Ulmann et al, 2008).…”

P2X4: A fast and sensitive purinergic receptor

“…In lung epithelial cells, P2X4 is associated with both exocytosis of lung surfactants and alveolar fluid transport [28] , making it a key player in airway homeostasis. It is elevated in asthmatic patients and in a mouse model of asthmatic disease [108] . In the mouse model of asthma, P2X4 antagonists can be used to efficiently alleviate many of the symptoms: eosinophilia, inflammation, mucus production, and cellular infiltration in the airway [108] , [109] .…”

“…It is elevated in asthmatic patients and in a mouse model of asthmatic disease [108] . In the mouse model of asthma, P2X4 antagonists can be used to efficiently alleviate many of the symptoms: eosinophilia, inflammation, mucus production, and cellular infiltration in the airway [108] , [109] . P2X4-deficient mice are also less prone to Th2 responses, the same can be observed in mice which received an adoptive transfer of P2X4-deficient bone marrow cells [108] .…”

Deletion of the P2X4 receptor is neuroprotective acutely, but induces a depressive phenotype during recovery from ischemic stroke

“…These changes are accompanied by upregulation and activation of microglial P2X4Rs (Vazquez-Villoldo et al, 2014). Prior studies using global P2X4R knockout (KO) mice showed diminished inflammasome signaling following spinal cord injury or allergen-induced airway inflammation (de Rivero Vaccari et al, 2012; Zech et al, 2016). In these injury models, P2X4R-positive leukocytes (i.e., macrophages, dendritic cells, and T cells) are the main sources of pro-inflammatory cytokine release.…”