Exploring the potential immunomodulatory effects of gallic acid on milk phagocytes in bovine mastitis caused by Staphylococcus aureus

Abstract

Bovine mastitis caused by Staphylococcus aureus may exacerbate by resulting in significant economic losses and impacting milk quality. To date, the use of gallic acid, a phenolic compound naturally occurring in various plants, holds promise due to its potent anti-oxidant and anti-inflammatory effects in many pieces of literature, thus, making it a subject of interest in bovine innate immunity research. Here we used gallic acid to assess its potential immunomodulation on milk phagocytes in vitro challenges with mastitis-causing bacteria. Our findings indicated that cells exposed to gallic acid showed no harm to cell viability but might maintain the longevity of cells during the bacterial infection. Gallic acid-treated cells displayed reduced cell migration, phagocytosis, and bacterial killing ability, while showing an increase in ROS production, all of which are undoubtedly linked to the intracellular killing abilities of the cells. Nonetheless, the extracellular structure called neutrophil extracellular traps (NETs) was significantly released after receiving gallic acid, representing extracellular killing. We also reported that gallic acid neutralizes inflammation by regulating specific pro-inflammatory genes (IL1B, IL6, TNF) and ROS-generating genes (CYBA, LAMP1, RAC1), subsequently preventing tissue damage. Regarding apoptosis-related genes and proteins, the increased production of caspase-3 and Bcl-2 family proteins could potentially promote the longevity of cells, implicated in the mechanism of combating bacterial invasion during udder inflammation and infection. The novel role of gallic acid on milk phagocytes highlights its potential immunomodulatory properties and contributes to our understanding of its effects on bacterial-host interactions, and provides valuable molecular insights.

VIROSCOPE®, an ethanolic extract of medicinal plants produced in Lomé, Togo, demonstrated excellent anti-inflammatory and immune cell proliferation activities

“…Therefore, VIROSCOPE® would have dose-dependent immunomodulatory properties and the dose of VIROSCOPE® to drink will depend on the desired effect. Rutin and gallic acid (two major active ingredients found in VIROSCOPE®) have already been reported to have immunomodulatory activity [26,30,31] .…”

Divergent Immune Responses to Minor Bovine Mastitis-Causing Pathogens

“…Cells were incubated in the dark for 15 min, then washed with cold HBSS. ROS-positive cells were analyzed by a flow cytometer [ 21 ].…”

“…Plates were incubated at 37 °C for 90 min. Bacterial viability was assessed using the previously described colorimetric method with MTT [ 15 , 21 ]. The absorbance (OD) was then measured at a wavelength of 570 nm using a microplate reader (Anthos Labtec Instruments, Wals, Austria).…”

“…Plates were incubated at 37 °C for 18 h to allow for colony growth. Images of the colonies were captured using the GelMax system (Ultra-Violet Products, Cambridge, UK) [ 21 ].…”

“…Unraveling how bovine neutrophils recognize “minor players” like NASM and LAB, especially S. chromogenes , holds the key to understanding udder immunity dynamics. Upon pathogen recognition, bovine neutrophils wage war with classical tactics (phagocytosis, ROS, RNI, AMPs, granule enzymes) [ 17 ], and subtle strategies (NETs, inflammatory mediators) for comprehensive udder defense unfold [ 15 , 18 , 19 , 20 , 21 ]. Adding another layer to their defense, neutrophils undergo programmed death (apoptosis) to limit NASM and LAB infections and resolve inflammation, revealing the intricate interplay between host and pathogen.…”