ABSTRACT
Coronaviruses (CoVs) belong to the family Coronaviridae, which are enveloped and have a single-stranded RNA genome. The new coronavirus (SARS-CoV-2) is the seventh known coronavirus that can infect humans and cause serious illness, such as acute respiratory syndrome. The coronaviruses already identified have contributed to the understanding of the clinical manifestations caused by SARSCoV-2, as well as their associations with the immune system. The aim of the present study was to carry out a narrative review of the literature on the host's immune response to infection by the new coronavirus. The review contains basic and summarized information on the main mechanisms involved in the immune response to SARS-CoV-2. The characteristics of the infection were considered according to the following: from the initial contact with the host through binding to angiotensin-converting enzyme 2 (ACE-2); the recognition of the pathogen by innate immunity cells; its containment mechanisms, including the production of effector cytokines and chemokines important in the development of the inflammatory process; and the participation of the complement system until the activation of the adaptive immune response. The probable occurrence of a host dysfunctional immune response and the escape mechanisms of the virus were also addressed. Despite numerous studies on the pathogenesis of SARS-CoV-2 infection, knowledge about the host's immune response in COVID-19 is not fully understood. The present work established the relationship between the new coronavirus and the immune system, but further studies are needed for all the mechanisms of the process to be elucidated.
Os coronavírus (CoVs) pertencem à família Coronaviridae, são envelopados com genoma de RNA (Ácido Ribonucleico) de fita simples e de sentido positivo. O novo coronavírus (SARS-CoV-2) é o sétimo coronavírus conhecido com capacidade de infectar seres humanos e pode provocar doença grave, como a síndrome respiratória aguda. Os coronavírus já identificados contribuíram para o entendimento das manifestações clínicas causadas pelo SARS-CoV-2, bem como suas correlações com o sistema imune. O presente trabalho teve o propósito de realizar uma revisão narrativa de literatura sobre a resposta imune do hospedeiro à infecção pelo novo coronavírus. A revisão contém informações básicas e resumidas dos principais mecanismos envolvidos na resposta imune ao SARS-CoV-2. Foram consideradas as características da infecção desde o contato inicial com o hospedeiro, por meio da ligação da Enzima Conversora de Angiotensina 2 (ECA2), o reconhecimento do patógeno pelas células da imunidade inata, seus mecanismos de contenção, incluindo a produção de citocinas efetoras e quimiocinas importantes no desenvolvimento do processo inflamatório, a participação do sistema complemento até a ativação da resposta imune adaptativa. Foram abordados também a provável ocorrência de uma resposta imune disfuncional do hospedeiro e os mecanismos de escape do vírus. Apesar dos inúmeros trabalhos sobre a patogenia da infecção pelo SARS-CoV-2, o conhecimento sobre a resposta imune do hospedeiro na COVID-19 não está totalmente esclarecido. O presente trabalho estabeleceu as relações do novo coronavírus com o sistema imunológico, entretanto, mais estudos ainda são necessários para que todos os mecanismos do processo sejam elucidados.
Subject(s)
Severe Acute Respiratory Syndrome , SARS-CoV-2 , COVID-19/immunology , ImmunityABSTRACT
The species of the genus Lychnophora, Asteraceae, are popularly known as "arnica" and are native from Brazilian savana (Cerrado). They are widely used in Brazilian folk medicine as anti-inflammatory, to treat bruise, pain, rheumatism and for insect bites. For evaluation of acute toxicity, the ethanolic extract was given to albino female and male mice. In open-field test, the extract of Lychnophora trichocarpha (Spreng.) Spreng. (0.750 g/kg) induced a significant inhibition of the spontaneous locomotor activity and exploratory behavior of the animals were observed 1 and 4 h after administration. In traction test, the same dose reduced the muscular force 1 h after administration. The exploratory behavior reduced significantly in the group that received 0.50 g/kg, 1 and 4 h after administration of the extract. The animals that received the doses of 0.25, 0.50 and 0.75 g/kg did not show any change of blood biochemical parameters comparing to control group and showed some histopathological changes such as congestion and inflammation of kidney and liver. The dose of 1.5 g/kg caused the most serious signs of toxicity. Histopathological changes observed was hemorrhage in 62.5% and pulmonary congestion in 100% of the animals. Brain and liver congestion was found in 62.5% of the animals.
ABSTRACT
PURPOSE: To evaluate and characterize the wound healing process profile induced by allantoin incorporated in soft lotion oil/water emulsion using the planimetric and histological methods. METHODS: Female Wistar rats (n=60) were randomly assigned to 3 experimental groups: (C) control group-without treatment; (E) group treated with soft lotion O/W emulsion excipients; (EA) group treated with soft lotion O/W emulsion containing allantoin 5 percent. The emulsions either containing or not allantoin were topically administered for 14 days and the wound area was evaluated by planimetry and by qualitative and quantitative histological analysis of open wound model. RESULTS: The data which were obtained and analyzed innovate by demonstrating, qualitatively and quantitatively, by histological analysis, the profile of healing process induced by allantoin. The results suggest that the wound healing mechanism induced by allantoin occurs via the regulation of inflammatory response and stimulus to fibroblastic proliferation and extracellular matrix synthesis. CONCLUSION: This work show, for the first time, the histological wound healing profile induced by allantoin in rats and demonstrated that it is able to ameliorate and fasten the reestablishment of the normal skin.
OBJETIVO: Avaliar e caracterizar o perfil cicatricial induzido pela alantoína incorporada em uma emulsão óleo/água, sob os aspectos planimétrico e histológico. MÉTODOS: Ratos Wistar fêmeas (n=60) foram agrupados aleatoriamente em três grupos experimentais grupo controle - sem tratamento (C); grupo tratado com emulsão pura (E); grupo tratado com emulsão contendo 5 por cento de alantoína (EA). As emulsões contendo ou não alantoína foram administradas topicamente durante 14 dias e a área da ferida foi avaliada por planimetria e por análise histológica qualitativa e quantitativa em modelo de ferida aberta. RESULTADOS: Na análise planimétrica não foi observado diferenças significativas entre os grupos experimentais. Os resultados da análise histológica sugerem que o mecanismo de cicatrização induzido pela alantoína ocorre via controle da resposta inflamatória e estímulos à proliferação fibroblástica e síntese de matrix extracelular de maneira mais intensa e rapidamente em relação aos grupos controles. CONCLUSÃO: Este trabalho mostra pela primeira vez o perfil histológico de cicatrização induzido pela alantoína em ratos, demonstrando ser capaz de melhorar e acelerar o processo de reconstituição da pele.