RESUMO
Granzyme B (GZMB) is a serine protease that is abundantly expressed in advanced human atherosclerotic lesions and may contribute to plaque instability. Perforin is a pore-forming protein that facilitates GZMB internalization and the induction of apoptosis. Recently a perforin-independent, extracellular role for GZMB has been proposed. In the current study, the role of GZMB in abdominal aortic aneurysm (AAA) was assessed. Apolipoprotein E (APOE)(-/-) x GZMB(-/-) and APOE(-/-) x perforin(-/-) double knockout (GDKO, PDKO) mice were generated to test whether GZMB exerted a causative role in aneurysm formation. To induce aneurysm, mice were given angiotensin II (1000 ng/kg/min) for 28 days. GZMB was found to be abundant in both murine and human AAA specimens. GZMB deficiency was associated with a decrease in AAA and increased survival compared with APOE-KO and PDKO mice. Although AAA rupture was observed frequently in APOE-KO (46.7%; n = 15) and PDKO (43.3%; n = 16) mice, rupture was rarely observed in GDKO (7.1%; n = 14) mice. APOE-KO mice exhibited reduced fibrillin-1 staining compared with GDKO mice, whereas in vitro protease assays demonstrated that fibrillin-1 is a substrate of GZMB. As perforin deficiency did not affect the outcome, our results suggest that GZMB contributes to AAA pathogenesis via a perforin-independent mechanism involving extracellular matrix degradation and subsequent loss of vessel wall integrity.
Assuntos
Aneurisma da Aorta Abdominal/genética , Granzimas/metabolismo , Perforina/fisiologia , Angiotensina II/farmacologia , Animais , Aorta Abdominal/metabolismo , Aorta Abdominal/patologia , Aneurisma da Aorta Abdominal/induzido quimicamente , Aneurisma da Aorta Abdominal/metabolismo , Aneurisma da Aorta Abdominal/mortalidade , Apolipoproteínas E/genética , Espaço Extracelular/metabolismo , Fibrilina-1 , Fibrilinas , Granzimas/genética , Granzimas/fisiologia , Humanos , Sistema Imunitário/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas dos Microfilamentos/metabolismo , Perforina/genética , Perforina/metabolismo , Processamento de Proteína Pós-Traducional/genética , Distribuição TecidualRESUMO
Microbial infections in insects activate a series of immune responses that culminate in the production of antimicrobial peptides (AMPs). In Drosophila, two signaling pathways, govern the challenge-dependent expression of AMPs; the Toll and IMD pathways. While AMPs have been the subject of much research in mosquitoes, the regulation of the pathways required for AMP expression remains largely unknown. We report here the identification of Aedes FADD (AeFADD), a death domain protein in Aedes aegypti. AeFadd is expressed in all immune-competent tissues and all developmental stages examined. At the transcriptional level, AeFadd transcripts increased when challenged with Escherichia coli but not Micrococcus luteus. In both cases, we observed the induction of two AMP genes; cecropin and defensin. Loss of AeFadd function by dsRNA interference impaired the inducible expression of both AMPs, and rendered adult mosquitoes susceptible to both types of bacteria. Identifying molecules that regulate mosquito immunity may help elucidate the factors that contribute to the vectorial capacity and provide insights into general mechanisms that regulate innate immunity.
Assuntos
Aedes/imunologia , Aedes/microbiologia , Peptídeos Catiônicos Antimicrobianos/genética , Proteína de Domínio de Morte Associada a Fas/imunologia , Proteínas de Insetos/imunologia , Aedes/genética , Aedes/crescimento & desenvolvimento , Sequência de Aminoácidos , Animais , Peptídeos Catiônicos Antimicrobianos/imunologia , Proteína de Domínio de Morte Associada a Fas/química , Proteína de Domínio de Morte Associada a Fas/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Imunidade Inata , Proteínas de Insetos/química , Proteínas de Insetos/genética , Masculino , Dados de Sequência Molecular , Ligação Proteica , Estrutura Terciária de Proteína , Homologia de Sequência de Aminoácidos , Febre Amarela/parasitologiaRESUMO
The mechanism and role of apoptotic cell death in the pathogenesis of atheromatous diseases is an area of intense research. Atherosclerosis is an inflammatory disease and as such, immune-mediated cell killing plays an important role. Recent studies have suggested that Granzyme B and perforin play an important role in atherogenesis. The current manuscript reviews our current understanding pertaining to the role of Granzyme B in cardiac allograft vasculopathy and atherosclerosis.
