High milk neutrophil chemiluminescence limits the severity of bovine coliform mastitis

Abstract

-Polymorphonuclear neutrophil (PMN) function changes during mastitis. To investigate the contribution of milk PMN to the severity of Escherichia coli (E. coli) mastitis, chemiluminescence (CL) of blood and milk PMN and their efficiency to destroy coliform bacteria in the mammary gland were examined following the induction of E. coli mastitis in early lactating cows. To better assess and define the degree of mastitis severity, cows were classified as moderate and severe responders according to milk production loss in the non-infected quarters at post-infection hour (PIH) 48. There was an inverse relationship between pre-infection milk PMN CL and colony-forming units at PIH 6. In moderate cows, the pre-infection blood and milk PMN CL was ~ 2-fold higher than that of severe cows. The probability of severe response increased with decreasing pre-infection PMN CL. At the beginning of the infection blood and milk PMN CL was consistently higher, and milk PMN CL increased faster after infection in moderate cows. At PIH > 48 milk PMN CL in severe cows exceeded that of moderate cows. The somatic cell count (SCC) in moderate cows increased faster than colonyforming units, whereas in severe cows the results were reversed. The kinetics of CL activity for blood and milk PMN before and during the early phase of infection confirmed an impairment in PMN CL activity for severe responding cows. High pre-infection blood and milk PMN CL and the immediate increase of milk PMN CL and SCC after infection limited bacterial growth thereby facilitating the recovery of E. coli mastitis in moderate cows. Our study strengthens the idea that pre-existing milk PMN (a static part of the udder's immune defense) functions as a "cellular antibiotic" before and during infection, and low milk PMN CL is a risk factor for bovine coliform mastitis.bovine / chemiluminescence / mastitis / neutrophil / severity

Bacterial lipopolysaccharide stimulates bovine neutrophil production of TNF-α, IL-1β, IL-12 and IFN-γ

“…In vivo studies have demonstrated that the life span of bovine PMN from mammary quarters infected with E. coli is prolonged when compared to noninfected quarters [25]. Further, higher preinfection viability of mammary PMN correlated with increased chemiluminescence activity, a more rapid bacterial clearance and recovery of infected quarters [25,26].…”

Infusão intramamária de Weissella confusa afeta a contagem de células somáticas e a contagem diferencial de leucócitos no leite

“…According to MEHRZAD et al (2005) and MERLE et al (2007), SCCs do not seem to describe completely the defense activities within the udder, which require the determination of functional parameters such as viability and activity of PMNs.…”

Mediation analysis to estimate direct and indirect milk losses associated with bacterial load in bovine subclinical mammary infections

“…These are the most abundant and the most important phagocytes of the innate immunity and they constitute more than 90% of somatic cells in cows with clinical mastitis (Sharma et al, 2011). If neutrophils are effective as antimicrobial defences, they are also a putative source of molecules with proinflammatory and proteolytic roles which harm the mammary epithelium (Capuco et al, 1986;Mehrzad et al, 2005). In such cases, a therapeutic approach is to treat cows with anti-inflammatory agents (McDougall et al, 2009).…”