Maturation of mononuclear phagocytes in the lungs of young calves—In vitro study

Abstract

The influences of age in calves' immune system are described in their first phase of life. We hypothesized that variations that occur in the main mechanisms of lung innate response can help to identify periods of greater susceptibility to the respiratory diseases that affect calves in the first stage of their life. This study aimed to evaluate the innate immune system. Nine healthy calves were monitored for 3 mo and 8 immunologic evaluations were performed. Bronchoalveolar lavage samples were recovered by bronchoscopy. The alveolar macrophages in samples were identified by protein expression of cluster of differentiation 14 (CD14) and underwent functional evaluation of phagocytosis (Staphylococcus aureus stained with propidium iodide and Escherichia coli). Data was assessed by one-way ANOVA (unstacked and parametric) and the Mann-Whitney test (nonparametric). Functional alterations in CD14-positive phagocytes were observed, with punctual higher intensity of phagocytosis in the third week and its decrease starting at 45 d of life. A gradual increase in phagocytosis rate was observed starting at this date. It is concluded that from 45 d of life on, alveolar macrophages have less phagocytic capacity but more cells perform this function. We suggest that this occurs because lung macrophages of calves start to maintain their immune response without passive immunity influence. Until 90 d of life, calves did not achieve the stability to conclude the maturation of local innate immune response.

Perfil citológico pulmonar de bezerros sadios nos três primeiros meses de vida

“…Os achados descritos acima são semelhantes ao encontrado por outros autores (Brown & Ananaba 1988, Pringle et al 1988, Allen et al 1992, Yeo et al 1993, Fernandes et al 2000, e apresentam o mesmo padrão observado nas espécies bovina (Batista et al 2012) equina (Fogarty 1990, Fernandes et al 2000, canina (Hirt et al 2010), suína (Hennig-Pauka et al 2007), felina (Padrid et al 1991) e em coelhos (Hawkins et al 2008). …”

“…As porcentagens de macrófagos encontrados diferem em alguns dos momentos dos encontrados por Batista et al (2012) já que este autor utilizou a técnica de citometria de fluxo para identificação de macrófagos por meio de marcadores de superfície (CD14). Segundo Raidal et al (1998) as populações celulares encontradas no LBA são constituídas por macrófagos, células não macrofágicas e outras subpopulações de macrófagos que realizam diferentes funções além da fagocitose e não expressam o CD14.…”

“…Em contrapartida, os animais mais velhos recrutam menor número de neutrófilos, que são mais eficientes na eliminação dos patógenos, porém mais danosa ao tecido hospedeiro (Grell et al 2005, Batista et al 2012, corroborando com os dados de citologia broncoalveolar em bovinos estudados a partir dos 90 dias de idade encontrados por Bertagnon (2015), nos quais a média até os 180 dias de vida dos animais foi de 67% para macrófagos e 23% para neutrófilos, não apresentando diferença entre os momentos experimentais.…”

Influence of orchiectomy of seven month old bulls on bronchoalveolar immune function

“…BAL samples were collected by bronchoscopy with a flexible video endoscope (EC-250LP5, Fujinon ® 1,690 mm X ø11 mm) inserted nasopharyngeally up to the bronchus; 80mL of 0.9% sterile saline solution was injected through the equipment's working channel and then aspirated with a surgical vacuum cleaner (Batista et al, 2012), thus achieving a recovery of approximately 50mL of BAL.…”

“…The castration of male cattle is routine practice in many countries, and although widely studied, no satisfactory protocol has been developed standard technique for reduced pain and faster cicatrization (Stafford, 2002;Pang et al, 2009;Coetzee et al, 2010), there is currently no consensus (Becker et al, 2012) Bovine Respiratory Diseases (BRD) cause major economic losses in husbandry (Pinchak et al, 2004), and these diseases are common following castration (Snowder et al, 2008). Numerous studies on the effects of castration on acute stress, cortisol production, decrease in performance and the blood immune response have been conducted (Ting et al, 2003;Ballou et al, 2013).…”