CLEC5A is critical for dengue-virus-induced lethal disease

Abstract

Dengue haemorrhagic fever and dengue shock syndrome, the most severe responses to dengue virus (DV) infection, are characterized by plasma leakage (due to increased vascular permeability) and low platelet counts. CLEC5A (C-type lectin domain family 5, member A; also known as myeloid DAP12-associating lectin (MDL-1)) contains a C-type lectin-like fold similar to the natural-killer T-cell C-type lectin domains and associates with a 12-kDa DNAX-activating protein (DAP12) on myeloid cells. Here we show that CLEC5A interacts with the dengue virion directly and thereby brings about DAP12 phosphorylation. The CLEC5A-DV interaction does not result in viral entry but stimulates the release of proinflammatory cytokines. Blockade of CLEC5A-DV interaction suppresses the secretion of proinflammatory cytokines without affecting the release of interferon-alpha, supporting the notion that CLEC5A acts as a signalling receptor for proinflammatory cytokine release. Moreover, anti-CLEC5A monoclonal antibodies inhibit DV-induced plasma leakage, as well as subcutaneous and vital-organ haemorrhaging, and reduce the mortality of DV infection by about 50% in STAT1-deficient mice. Our observation that blockade of CLEC5A-mediated signalling attenuates the production of proinflammatory cytokines by macrophages infected with DV (either alone or complexed with an enhancing antibody) offers a promising strategy for alleviating tissue damage and increasing the survival of patients suffering from dengue haemorrhagic fever and dengue shock syndrome, and possibly even other virus-induced inflammatory diseases.

CLEC‐2 signaling via Syk in myeloid cells can regulate inflammatory responses

“…These findings are in line with reports in platelets showing that CLEC-2 signals lead to PLCg activation, an enzyme crucial for intracellular calcium increase [18,19]. The use of mAbs to selective trigger surface receptors has provided important insight into the signaling and function of different CLRs [40][41][42]. Furthermore, human CLEC-2 signaling in platelets has also been studied upon crosslinking by polyclonal antibodies [19] and our own 17D9 mAb has also been used by others to selectively trigger CLEC-2 signaling in mouse platelets [20,43].…”

CLEC5A is critical for dengue virus–induced inflammasome activation in human macrophages

“…The sources of antibodies for blocking assay are as follows: antimannose receptor antibody (BioLegend); anti-DC-SIGN (R&D Systems); anti-CLEC5A blocking antibody. 20 The antibodies for immunoprecipitation or immunoblotting are as follows: anti-IL-1␤, anti-IL-18 (Santa Cruz Biotechnology), and antiactin antibody (Chemicon). Human monocytes were obtained from healthy donors at the Taipei Blood Center of Taiwan Blood Services Foundation, under a protocol (PM-99-TP-075) approved by the institutional review board of the Clinical Center of department of Health, Taiwan.…”

“…Previously, we have shown that DV can replicate in M-M and induce TNF-␣ production, 20 but whether DV can infect and replicate in GM-M is not investigated yet. When the susceptibility of GM-M to DV infection was examined by the expression of NS3 protein using immunofluorescence (IF), we identified intensive NS3-positive signals ( Figure 2A) and a higher percentage of NS3-positive cells after incubation with DV ( Figure 2B).…”

“…It has been shown that DV can bind and activate CLEC5A to induce the phosphorylation of DAP12, 20 an ITAM-containing adaptor protein phosphorylated by activated Syk, 42 as well as the release of proinflammatory cytokines. However, whether CLEC5A is linked to inflammasome activation has not been investigated yet.…”

“…Furthermore, up-regulation of pro-IL-1␤, pro-IL-18, and NLRP3 transcription with increased caspase-1 activity was found in DV-infected GM-M . Interestingly, blockade of CLEC5A, a C-type lectin critical for DHF, 20 and Japanese encephalitis virus infection, 21 inhibits the activation of NLRP3 inflammasome, and abolishes DV-induced IL-1␤ production and pyrotopsis in GM-M . These observations suggest that CLEC5A is critical to regulate NLRP3 inflammasome activation in DV infection and that the blockade of CLEC5A would be helpful to alleviate clinical symptoms in dengue patients.…”