Dataset Information

C5a-C5aR1 Axis Activation Drives Envenomation Immunopathology by the Snake Naja annulifera.

ABSTRACT: Systemic complement activation drives a plethora of pathological conditions, but its role in snake envenoming remains obscure. Here, we explored complement's contribution to the physiopathogenesis of Naja annulifera envenomation. We found that N. annulifera venom promoted the generation of C3a, C4a, C5a, and the soluble Terminal Complement Complex (sTCC) mediated by the action of snake venom metalloproteinases. N. annulifera venom also induced the release of lipid mediators and chemokines in a human whole-blood model. This release was complement-mediated, since C3/C3b and C5a Receptor 1 (C5aR1) inhibition mitigated the effects. In an experimental BALB/c mouse model of envenomation, N. annulifera venom promoted lipid mediator and chemokine production, neutrophil influx, and swelling at the injection site in a C5a-C5aR1 axis-dependent manner. N. annulifera venom induced systemic complementopathy and increased interleukin and chemokine production, leukocytosis, and acute lung injury (ALI). Inhibition of C5aR1 with the cyclic peptide antagonist PMX205 rescued mice from these systemic reactions and abrogated ALI development. These data reveal hitherto unrecognized roles for complement in envenomation physiopathogenesis, making complement an interesting therapeutic target in envenomation by N. annulifera and possibly by other snake venoms.

SUBMITTER: Silva de Franca F

PROVIDER: S-EPMC8082402 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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C5a-C5aR1 Axis Activation Drives Envenomation Immunopathology by the Snake Naja annulifera.

Silva de França Felipe F Villas-Boas Isadora Maria IM Cogliati Bruno B Woodruff Trent M TM Reis Edimara da Silva EDS Lambris John D JD Tambourgi Denise V DV

Frontiers in immunology 20210415

Systemic complement activation drives a plethora of pathological conditions, but its role in snake envenoming remains obscure. Here, we explored complement's contribution to the physiopathogenesis of Naja annulifera envenomation. We found that N. annulifera venom promoted the generation of C3a, C4a, C5a, and the soluble Terminal Complement Complex (sTCC) mediated by the action of snake venom metalloproteinases. N. annulifera venom also induced the release of lipid mediators ...[more]

PMID: 33936074

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Project description:Enterovirus A71 (EV-A71) is a common small RNA virus that is highly neuroinvasive. Emerging evidence indicates that the complement fragment C5a and its receptor C5aR1 are important drivers of neuroinflammation. However, the potential role of the C5a-C5aR1 axis in EV-A71 encephalitis remains largely elusive. Our previous studies revealed that EV-A71 can infect astrocytes and result in complement activation in vivo. Here, we investigated how complement factors interact with astrocytes to promote a severe inflammatory response upon EV-A71 infection. Our data revealed that EV-A71 infected mainly astrocytes and caused astrocyte activation in the mouse brain, which was further verified in patients with EV-A71 infection and U87-MG cells. Notably, EV-A71 infection led to activation of the C5a-C5aR1 axis in U87-MG cells, and knockdown (siC5aR1) or blockade (PMX53) of C5aR1 significantly suppressed EV-A71-induced astrocyte activation and proinflammatory cytokine (e.g., CXCL1) production. Next, the activation of the C5a-C5aR1 axis in mouse astrocytes was confirmed. Compared with C5aR1 knockout mice, wild-type mice presented more severe symptoms and lower survival rates after EV-A71 infection. C5aR1 deficiency or blockade significantly reduced EV-A71-induced pathological damage and proinflammatory cytokine production in the mouse brain. Importantly, an increased level of soluble C5a was strongly correlated with the severity of symptoms in patients with EV-A71 infection. By using confocal microscopy, primary astrocytes, and human specimens, we observed that the increase in CXCL1 levels resulted mainly from astrocytes. Neutralizing CXCL1 significantly alleviated the neuropathological changes caused by EV-A71 infection, and the production of CXCL1 in astrocytes was regulated by p38 MAPK signaling. Taken together, our findings indicate that the activation of the C5a-C5aR1 axis in astrocytes facilitates the neuropathological changes resulting from EV-A71 infection, emphasizing the potential role of p38 MAPK-mediated CXCL1 production in these alterations.ImportanceEnterovirus A71 (EV-A71) is a common small RNA virus with highly neuroinvasive tendencies. Our previous studies took the view that EV-A71 could infect astrocytes and result in complement activation in vivo. We investigated how complement interacts with astrocytes to promote a severe inflammatory response upon EV-A71 infection in the study. As expected, our data demonstrate that EV-A71 triggers robust activation of the C5a-C5aR1 axis in astrocytes and that knockout or blockade of C5aR1 in animals exposed to lethal doses of EV-A71 significantly enhances survival by diminishing the production of the chemokines CXCL1 and IL-6. In addition, neutralizing CXCL1 significantly alleviates the neuropathogenesis caused by EV-A71 infection. Thus, inhibiting the C5a-C5aR1 axis has emerged as a potential therapeutic strategy to mitigate neural damage caused by EV-A71 infection.

Dataset Information

C5a-C5aR1 Axis Activation Drives Envenomation Immunopathology by the Snake Naja annulifera.

Publications

C5a-C5aR1 Axis Activation Drives Envenomation Immunopathology by the Snake <i>Naja annulifera</i>.

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