Dengue Virus Serotype 2 and Its Non-Structural Proteins 2A and 2B Activate NLRP3 Inflammasome

Abstract

Dengue is the most prevalent and rapidly transmitted mosquito-borne viral disease of humans. One of the fundamental innate immune responses to viral infections includes the processing and release of pro-inflammatory cytokines such as interleukin (IL-1β and IL-18) through the activation of inflammasome. Dengue virus stimulates the Nod-like receptor (NLRP3-specific inflammasome), however, the specific mechanism(s) by which dengue virus activates the NLRP3 inflammasome is unknown. In this study, we investigated the activation of the NLRP3 inflammasome in endothelial cells (HMEC-1) following dengue virus infection. Our results showed that dengue infection as well as the NS2A and NS2B protein expression increase the NLRP3 inflammasome activation, and further apoptosis-associated speck-like protein containing caspase recruitment domain (ASC) oligomerization, and IL-1β secretion through caspase-1 activation. Specifically, we have demonstrated that NS2A and NS2B, two proteins of dengue virus that behave as putative viroporins, were sufficient to stimulate the NLRP3 inflammasome complex in lipopolysaccharide (LPS)-primed endothelial cells. In summary, our observations provide insight into the dengue-induced inflammatory response mechanism and highlight the importance of DENV-2 NS2A and NS2B proteins in activation of the NLRP3 inflammasome during dengue virus infection.

Inflammasome Fuels Dengue Severity

“…Pharmacological inhibition of NLRP3, caspase-1 and CRISPR knockout of ASC in endothelial cells showed that NS2A and NS2B mediated inflammasome and IL-1β secretion was NLRP3 and caspase-1 specific. Lastly, the study also suggested that NS2A triggering NLRP3 inflammasome activation is due to Ca ++ homeostasis and/or mitochondrial disruption /ROS production (Shrivastava et al, 2020 ). In summary, these evidences show the dengue virus proteins induced mechanism in activating NLRP3 inflammasome.…”

Contact System Activation in Plasma from Dengue Patients Might Harness Endothelial Virus Replication through the Signaling of Bradykinin Receptors

“…It is well established that thrombocytopenia and vascular dysfunction are common manifestations of severe DENV infection. Analysis of human fatal cases and studies in animal models provided evidence that DENV infects endothelial cells lining different tissues [ 18 , 19 , 20 , 21 , 22 ], raising the possibility that microvascular leakage is underpinned by dysregulated endothelial function and/or viral-induced death [ 23 , 24 , 25 ]. A major limitation in understanding the mechanisms underlining those issues is the lack of an immunocompetent mouse experimental model that sustains virus replication and present dengue clinical signs after systemic inoculation.…”

Activation and Inhibition of the NLRP3 Inflammasome by RNA Viruses

“…Detection of a higher level of NLRP3 expression, ASC oligomerization, and Caspase-1 activation from LPS-treated HMEC-1 cells transfected with NS2A or NS2B indicates that NS2A and NS2B can activate IL-1β mediated NLRP3 inflammasome. 135 Above all, results suggest that DENV M, NS2A, and NS2B proteins induce NLRP3 inflammasome activation.…”

“… 132 , 133 However, the Nonstructural proteins 2A, 2B, and structural protein M activate the NLRP3 inflammasome. 134 , 135 M protein of DENV is responsible for endothelial dysfunction, and vascular leakage resulting in IL-1β mediated NLRP3 activation. 134 DENV stimulates inflammatory NLRP3 assembly in platelets.…”

“… 134 Another study showed that NS2A and NS2B of DENV-2 induce IL-1β secretion and activation of NLRP3 inflammasome through Ca ++ ion channel and mitochondrial ROS model. 135 THP-1 and HMEC-1 cells were infected with DENV-2 or treated with LPS plus ATP. Detection of IL-1β secretion from supernatant or Caspase-1 and ASC oligomerization indicates that DENV-2 can induce NLRP3 inflammasome.…”