Mastitis is an inflammatory breast disease that develops mostly during the first 12 weeks’ post-partum
in women and it is the major reason for early cessation of breastfeeding. The mechanisms of human
mastitis are mostly unknown, while many studies have been published in bovine, showing a chronic
inflammatory response in mammary tissue with high and extended production of pro-inflammatory
cytokines (IL-1B, IL-6, IL-8, TNF-¿), known to be mediated via increases in the activity of NF-¿B. During
chronic inflammation these cytokines, reactive oxygen species (ROS), and phagocytes can cause
considerable damage to the mammary tissue and hence, decrease in milk production and cessation of
breastfeeding. Interestingly, numerous previous studies have reported the beneficial and protective
anti-inflammatory properties mediated by the activation of the cannabinoid type 2 (CB2) receptor with
endogenous cannabinoids, phytocannabinoids, and synthetic agonists in human models of chronic
inflammatory diseases. Furthermore, CB2 expression is found upregulated in these tissues undergoing
chronic inflammatory responses. Activation of CB2 with these agonists has been previously shown to
causes a decrease in pro-inflammatory cytokines (IL-1B, IL-6, IL-8, TNF-¿) and ROS production also
mediated by a downregulation of NF-¿B. Indeed, downregulation of oxidative enzymes (iNOS) and
upregulation of anti-oxidant enzymes (SOD) is also observed. These are the same components and
signaling pathways known to be chronically upregulated during mastitis inflammation. The overall goal
of this project is to provide evidence of the potential role of CB2 as a therapeutic target in the modulation
of mammary tissue inflammation during mastitis infection. The endogenous cannabinoid and CB2
agonist 2-AG has been detected in human milk during lactation, providing evidence this organ may be
under control of the endocannabinoid system. Our main hypothesis is that CB2 expression in the
mammary gland is elevated during mastitis, and its anti-inflammatory properties can be activated by
endogenous and synthetic agonists in vitro. This hypothesis will be tested through three specific aims
in bovine mammary tissue: 1) to characterize the gene and/or protein expression profile of the CB2
receptor, documented molecules related to CB2 immunomodulation (NF-K¿, COX2, iNOS), and
inflammatory cytokines (IL-1¿, IL-6, IL-8, TNF-¿) in healthy and mastitis bovine mammary tissue (mixed
cell types) during lactation, 2) to test the anti-inflammatory effect of CB2 receptor activation via
endogenous and synthetic agonists (2-AG and JWH133) in vitro using bovine primary mammary
epithelial cell culture by monitoring changes in expression of these aforementioned molecules, and 3)
characterize host response to CB2 activation during infection with S. aureus compared to E. Coli by
monitoring changes in expression of these aforementioned molecules These studies are expected to
significantly advance current understanding of CB2 anti-inflammatory potential during inflammation of
peripheral organs.
