Expression of CD14 and toll-like receptors 2 and 4 by milk neutrophils in bovine mammary glands infected with Corynebacterium bovis

Abstract

RESUMO.-[Expressão de CD14 e dos receptores do tipo toll 2 e 4 por neutrófilos lácteos provenientes de glândulas infectadas por Corynebacterium bovis.] O presente estudo objetivou avaliar alterações na expressão de CD14, e dos receptores do tipo toll (TLR) 2 e 4 na superfície de neutrófilos lácteos provenientes de glândulas mamárias infectadas por Corynebacterium bovis. O presente estudo utilizou 23 quartos negativos no exame bacteriológico, sem alterações na prova de fundo escuro e com contagem automática de células somáticas menor que 1 x10 5 células/mL, e 14 quartos mamários infectados por C. bovis A identificação de neutrófilos, assim como a porcentagem de neutrófilos lácteos que expressaram CD14, TLR2 e 4 foram avaliadas por citometria de fluxo utilizando anticorpos monoclonais. A porcentagem de neutrófilos que expressaram TLR2 e TLR4 nos quartos mamários infectados por C. bovis não diferiu dos quartos mamários sadios, assim como na expressão de TLR4. No entanto, a intensidade de fluorescência do TLR2 na superfície dos neutrófilos foi menor nos quartos mamários infectados por C. bovis. A porcentagem de neutrófilos que expressaram CD14 e a intensidade de fluorescência da molécula de CD14 foi menor na superfície dos neutrófilos lácteos dos quartos infectados por C. bovis. This study evaluated the expression of CD14, toll-like receptor (TLR) 2 and TLR4 on the surface of milk neutrophils in bovine mammary glands infected with Corynebacterium bovis. Here, we used 23 culture-negative control quarters with no abnormal secretion on the strip cup test and milk somatic cell count lower than 1x10 5 cells/mL, and 14 C. bovis infected quarters. The identification of neutrophils, as well as, the percentage of neutrophils that expressed CD14, TLR2 and TLR4 were analyzed by flow cytometry using monoclonal antibodies. The present study encountered no significant difference in the percentages of milk neutrophils that expressed TLR2 and TLR4 or in the expression of TLR4 by milk neutrophils. Conversely, a lower median fluorescence intensity of TLR2 in milk neutrophils was observed in C. bovis-infected quarters. The percentage of neutrophils that expressed CD14 and the median fluorescence intensity of CD14 in milk neutrophils was also lower in C. bovis-infected quarters.INDEX TERMS: Immune response, pattern recognition receptor, mastitis, milk, polymorphonuclear neutrophil leukocyte.

Somatic cell count and mastitis pathogen detection in composite and single or duplicate quarter milk samples

“…For instance, C. bovis did not result in a significant increase in milk SCC in this study. This pathogen has been regarded as a minor pathogen with limited clinical significance (Oliveira et al 2013), probably due at least in part to the modulation of innate immunity (i.e., toll-like receptor 2) in an attempt to control inflammation and tissue injury (Blagitz et al 2015). However, major pathogens, including S. aureus, S. agalactiae and Streptococcus uberis, led to a significant augmentation of the milk SCC in the present study, as previously described (Djabri et al 2002, Souza et al 2009, Botaro et al 2015.…”

Milk lymphocyte profile and macrophage functions: new insights into the immunity of the mammary gland in quarters infected with Corynebacterium bovis

“…Thus, our results corroborate other studies that found a high correlation between isolation of C. bovis from aseptically collected milk samples and the reduction in the occurrence of intramammary infection by other pathogenic bacteria [6,13,[16][17][18], although there is no consensus on this assertion [36][37][38][39]. In addition to our data regarding the lymphocytic and functional profile of milk macrophages, other factors may be related to the potential protective effect of intramammary infection by C. bovis, such as inhibition of growth by competition, bacterial antagonism, increased activity of milk neutrophils, and the presence of plasmocytes in the parenchymal tissue and the teat apices of quarters colonized with C. bovis [6,16,21,40].…”

“…bovis is of interest to mastitis researchers because quarters infected with this bacterium are less likely to become infected with other, more pathogenic bacteria [6,13,[15][16][17][18][19]. Previous studies conducted by our research group investigated the functions of milk neutrophils (e.g., viability, phagocytosis and intracellular reactive oxygen species production) in udder quarters infected with C. bovis [20,21]. Thus, to deepen our understanding of the mammary gland immunity in C. bovis-infected udder quarters, this study aimed to investigate the lymphocyte profile of milk and the function of milk macrophages of healthy mammary glands compared to udder quarters naturally infected with C. bovis.…”

Milk Lymphocyte Profile and Macrophage Functions: New Insights Into the Immunity of the Mammary Gland in Quarters Infected With Corynebacterium Bovis

“…Thus, our results corroborate other studies that found a high correlation between isolation of C. bovis from aseptically collected milk samples and the reduction in the occurrence of intramammary infection by other pathogenic bacteria [6, 13, 16-18], although there is no consensus on this assertion [36][37][38][39]. In addition to our data regarding the lymphocytic and functional pro le of milk macrophages, other factors may be related to the potential protective effect of intramammary infection by C. bovis, such as inhibition of growth by competition, bacterial antagonism, increased activity of milk neutrophils, and the presence of plasmocytes in the parenchymal tissue and the teat apices of quarters colonized with C. bovis [6,16,21,40]. Furthermore, macrophages represent the rst line of defense of the mammary gland against invasive pathogens because they make up the predominant leukocyte population in healthy udder quarters [27,30,41].…”

“…C. bovis is of interest to mastitis researchers because quarters infected with this bacterium are less likely to become infected with other, more pathogenic bacteria [6,13,[15][16][17][18][19]. Previous studies conducted by our research group investigated the functions of milk neutrophils in udder quarters infected with C. bovis [20,21]. To advance this research further, this study aimed to investigate the lymphocyte pro le of milk and the function of milk macrophages of healthy mammary glands compared to udder quarters naturally infected with C. bovis.…”