Intramammary inoculation with lactic acid bacteria at dry-off triggers an immunomodulatory response in dairy cows

Abstract

The use of antibiotics to prevent bovine mastitis is responsible for the emergence and selection of resistant strains. Lactic acid bacteria (LAB) could be introduced into animal feed as an alternative prevention method that would bypass the risk of resistance development. In previous research, we demonstrated that two probiotic LAB strains isolated from bovine milk were capable of stimulating the production of antibodies and the host’s immune cellular response in the udder. The present study aimed to elucidate whether the antibodies of animals inoculated with these strains were able to increase phagocytosis by neutrophils and inhibit the growth of different mastitis-causing pathogens. Moreover, the effect of LAB on the expression of pro-inflammatory cytokines was assessed. Ten animals were inoculated intramammarily with 106 cells of the two strains at dry-off. The blood serum was tested for its ability to opsonize bovine mastitis pathogens, the in vitro bactericidal activity of bovine blood and milk against these pathogens was determined, and cytokine mRNA expression was quantified in milk somatic cells. The inoculated animals did not show abnormal signs of sensitivity to the LAB. Their blood serum significantly enhanced the phagocytosis of Staphylococcus spp. and the LAB. Escherichia coli and Streptococcus uberis were inhibited by the milk serum but not the blood serum, whereas Staphylococcus aureus and Staphylococcus haemolyticus were inhibited by both. In regard to cytokine expression, interleukin (IL)-1β increased markedly for up to 4 h post-inoculation, and an increase in IL-8 was observed 4, 12 and 24 h after inoculation. Tumour necrosis factor-α mRNA increased 1 and 2 h after inoculation and a significant difference was registered at 6 h for interferon-γ. This rapid immunomodulatory response shows that inoculating animals with LAB at dry-off, when they are especially susceptible, could be a useful strategy for the prevention of bovine mastitis.

Lactococcus lactis subsp lactis CRL1655 and Schleiferilactobacillus perolens CRL1724 inhibit the adherence of common bovine mastitis pathogens to mammary gland cells, without causing histological changes in the mammary gland

“…Their own high adherence capability might enable them to effectively create a steric impediment for the pathogens and/or to outcompete them for a niche and receptors (Bouchard et al, 2015). Overall, these in vitro results, in addition to previous results where we demonstrated the immunomodulatory capacity of these two strains when they were intramammary inoculated in cows at dry‐off (Berardo et al, 2020; Pellegrino et al, 2017), suggest that the intramammary inoculation of bovine udders with LAB strains could prevent or reduce the likelihood of an intrammamary infection becoming established and/or developing during the first days of the dry‐off period.…”

Colonization and local host response following intramammary Staphylococcus chromogenes challenge in dry cows

“…It might be a concern that all 4 non-inoculated negative control quarters belonged to the same cow. However, this approach has been used by other researchers before [27,49]. Studies have demonstrated changes in qSCC [50] or the proportion of polymorphonuclear neutrophilic granulocytes or neutrophils and lymphocytes [51,52] in milk of adjacent healthy quarters when another quarter is affected with subclinical mastitis.…”

“…Alternatives for long-acting antimicrobial treatment of quarters at dry-off have been investigated before [23]. The concept to use less pathogenic bacteria, such as NAS [19,70], Corynebacterium bovis [71] or lactic acid bacteria [27,49] as probiotics to control mastitis in dairy cows during the dry period, was suggested by some [27,72]. Probiotics, such as udder-adapted bacteria, could be used to increase the activity of the mammary gland by means of a moderate inflammation in order to protect the udder against infections with more pathogenic bacteria.…”

“…The dry period is very important for dairy cows as intramammary infections (IMI) present at the moment of dry off can cure yet non-lactating mammary quarters can also become newly infected with potential negative effects for the start of the next lactation [23,24]. Despite the fact that the dry period is significant for dairy cows' udder health, only a limited number of intramammary challenge studies were conducted in the dry period [25][26][27], and none using NAS. Also, only a few studies have determined cytokine levels in dry period secretion from late gestation dairy cows.…”

Rumen Microbiota Alterations During Ketosis is Associated with the Development of Mastitis in Dairy Cows

“…Studies have shown that higher SCC are associated with differential microbial composition and function in the rumen, indicating the correlation between rumen microbiota and subclinical mastitis [1]. Some clinical trials have shown that oral probiotics supplementation could effectively control mastitis, suggesting that the mechanism of mastitis protection might be achieved via the host gut microbiota [20,42]. It was reported that the pattern of faecal microbial community changes of mastitis cows was similar to that of the milk, characterized by a general increase in the mastitis pathogens and deprivation of Lactobacillus [20].…”