O calicivírus na estomatite crónica felina: estudo imunohistoquímico
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2021-12-15
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As doenças da cavidade oral são muito frequentes na clínica médica felina e apresentam quadros clínicos muito distintos ao exame estomatológico-dentário. A avaliação histológica é essencial na identificação e classificação das lesões, avaliação da arquitetura dos tecidos, na sua organização tecidual habitual e também a sua relação com os tecidos adjacentes, permitindo por isso o estudo dos detalhes morfológicos. As condições inflamatórias da cavidade oral são muito frequentes nos gatos, realçandose como mais comuns a gengivoestomatite crónica felina (GECF). A GECF é uma doença crónica imunomediada da cavidade oral, caracterizada por uma resposta inflamatória exagerada a um estímulo antigénico constante e que se traduz numa inflamação oral simétrica e bilateral dos tecidos orais. A sua etiologia multifatorial não é completamente conhecida, inclui fatores infeciosos, ambientais e sistémicos- A presença de placa bacteriana provoca uma estimulação do sistema imunitário, existindo ainda outros fatores infeciosos que podem contribuir para o desenvolvimento desta doença, de entre eles o Calicivírus Felino (CVF). O CVF é um agente patogénico muito contagioso e, por isso, amplamente distribuído pela população felina. As células Natural Killer (NK), linfócitos granulares do sistema imune inato, representam, em conjunto com outras células e fatores humorais, a primeira linha de defesa contra infeções virais. Através da avaliação celular da mucosa oral de animais com GECF, e tendo como principais objetivos a identificação da presença do antigénio CVF e células NK, no sentido da melhor compreensão da afeção, integrou-se o estudo do papel do CVF na imunidade da cavidade oral. Quarenta amostras de mucosa oral de gatos com diagnóstico de estomatite crónica felina foram alvo análise imunohistoquímica, após a otimização do protocolo indireto com polímero, para avaliação da expressão do antigénio CVF e identificação de células NK, positivas para CD56. As células imunopositivas foram avaliadas em cinco campos de grande ampliação (objetiva de 40x) e estimadas por dois observadores independentes. Neste estudo, não se encontrou uma associação significativa entre a presença de CFV e os grupos etários (KW test, p=0.322), a raça (KW test, p=0.283) ou o sexo (KW test, p=0.322) dos gatos em estudo. Também na marcação das células NK, não se observou uma relação entre as mesmas variáveis: grupo etário (KW test, p=0.726), raça (KW test, p=0.282) ou sexo (KW test, p=0.503) e a quantidade de células positivas. Da mesma forma, não se evidenciou uma relação entre a presença do CVF e a população de células NK (MW test: Z(U)=63, , p<0.0001, R=9.9), que apresentaram uma elevada quantidade, mesmo quando não se identificou a presença de CVF, o que sugere a existência de outros motivos para a presença destas células, as quais devem ser exploradas em trabalhos futuros Através da sua contribuição para a caracterização histológica e imunológica da cavidade oral, bem como para o conhecimento dos mecanismos de inflamação e da sua etiologia, este estudo revelou-se importante, na medida em que compreender estes mecanismos é fundamental para o desenvolvimento de novas terapias que se direcionem quer aos agentes etiológicos quer aos processos inflamatórios envolvidos.
Oral cavity diseases are very frequent in feline practice and present many different pictures on dental and oral examination. Histological evaluation is essential in the identification and classification of the lesions and in the assessment of tissue’s architecture, its usual organization and its relationship with adjacent tissues, thus allowing the study of morphological details. Inflammatory conditions of the oral cavity are very common in cats, the most common being the feline gingivitis-stomatitis complex (FCGS) and the eosinophilic complex. FCGS is a chronic immune-mediated condition of the oral cavity, characterized by an exaggerated inflammatory response to a constant antigenic stimulus, causing a bilateral, symmetrical oral inflammation of oral tissues. It is a multifactorial disease and its aetiology is not completely known, including infectious, environmental and systemic factors. The presence of bacterial plaque causes a stimulation of the immune system, and there are other infectious factors that can contribute to the development of this disease, including the Feline Calicivirus (FCV). FCV is a very contagious pathogen and therefore widely distributed in the feline population. Natural killer cells, granular lymphocytes of the innate immune system, represent, together with other cells and humoral factors, the first line of defence against viral infections. Through the cellular evaluation of the oral mucosa of animals with FCGS, and having as main objectives the identification of the presence of the FCV antigen and NK cells, in order to better understand the condition, was integrated the study of the role of the FVC in the immunity of the oral cavity. Forty samples of oral mucosa from cats diagnosed with feline chronic stomatitis were subjected to immunohistochemical analysis, after optimization of the indirect polymer protocol, for evaluation of FCV antigen expression and identification of NK cells, positive for CD56. Immunopositive cells were evaluated in five high-magnification fields (40x objective) and estimated by two independent observers. In this study no significant association between the age group (KW test, p=0.322), breed (KW test, p=0.283) or sex (KW test, p=0.322) of the cats and the presence of FCV was observed. Regarding NK cells, no significant association between the age (KW test, p=0.726), breed (KW test, p=0.282) or sex (KW test, p=0.503) of the cats and the number of positive cells was observed. Likewise, it was not found a relationship between the presence of FCV and the presence of NK cells (MW test: Z(U)=63, p<0.0001, R=9.9), that showed high expression, even when the presence of FCV was not observed, suggesting different causes for the presence of these cells, which can be explored in future works. Through its contribution to the histological and immunological characterization of the oral cavity, as well as to the understanding of the mechanisms of inflammation and its aetiology, this study played an important role, as understanding these mechanisms is fundamental for the development of new therapies that address either the etiological agents or the inflammatory processes involved.
Oral cavity diseases are very frequent in feline practice and present many different pictures on dental and oral examination. Histological evaluation is essential in the identification and classification of the lesions and in the assessment of tissue’s architecture, its usual organization and its relationship with adjacent tissues, thus allowing the study of morphological details. Inflammatory conditions of the oral cavity are very common in cats, the most common being the feline gingivitis-stomatitis complex (FCGS) and the eosinophilic complex. FCGS is a chronic immune-mediated condition of the oral cavity, characterized by an exaggerated inflammatory response to a constant antigenic stimulus, causing a bilateral, symmetrical oral inflammation of oral tissues. It is a multifactorial disease and its aetiology is not completely known, including infectious, environmental and systemic factors. The presence of bacterial plaque causes a stimulation of the immune system, and there are other infectious factors that can contribute to the development of this disease, including the Feline Calicivirus (FCV). FCV is a very contagious pathogen and therefore widely distributed in the feline population. Natural killer cells, granular lymphocytes of the innate immune system, represent, together with other cells and humoral factors, the first line of defence against viral infections. Through the cellular evaluation of the oral mucosa of animals with FCGS, and having as main objectives the identification of the presence of the FCV antigen and NK cells, in order to better understand the condition, was integrated the study of the role of the FVC in the immunity of the oral cavity. Forty samples of oral mucosa from cats diagnosed with feline chronic stomatitis were subjected to immunohistochemical analysis, after optimization of the indirect polymer protocol, for evaluation of FCV antigen expression and identification of NK cells, positive for CD56. Immunopositive cells were evaluated in five high-magnification fields (40x objective) and estimated by two independent observers. In this study no significant association between the age group (KW test, p=0.322), breed (KW test, p=0.283) or sex (KW test, p=0.322) of the cats and the presence of FCV was observed. Regarding NK cells, no significant association between the age (KW test, p=0.726), breed (KW test, p=0.282) or sex (KW test, p=0.503) of the cats and the number of positive cells was observed. Likewise, it was not found a relationship between the presence of FCV and the presence of NK cells (MW test: Z(U)=63, p<0.0001, R=9.9), that showed high expression, even when the presence of FCV was not observed, suggesting different causes for the presence of these cells, which can be explored in future works. Through its contribution to the histological and immunological characterization of the oral cavity, as well as to the understanding of the mechanisms of inflammation and its aetiology, this study played an important role, as understanding these mechanisms is fundamental for the development of new therapies that address either the etiological agents or the inflammatory processes involved.
Descrição
Dissertação de Mestrado Integrado em Medicina Veterinária exclusivamente apresentado na
Universidade de Trás-os-Montes e Alto Douro para obtenção do título de Mestre em
Medicina Veterinária
Palavras-chave
Gato , inflamação oral