The Mammary Microenvironment in Mastitis in Humans, Dairy Ruminants, Rabbits and Rodents: A One Health Focus

Abstract

The One Health concept promotes integrated evaluation of human, animal, and environmental health questions to expedite advances benefiting all species. A recognition of the multi-species impact of mastitis as a painful condition with welfare implications leads us to suggest that mastitis is an ideal target for a One Health approach. In this review, we will evaluate the role of the mammary microenvironment in mastitis in humans, ruminants and rabbits, where appropriate also drawing on studies utilising laboratory animal models. We will examine subclinical mastitis, clinical lactational mastitis, and involution-associated, or dry period, mastitis, highlighting important anatomical and immunological species differences. We will synthesise knowledge gained across different species, comparing and contrasting disease presentation. Subclinical mastitis (SCM) is characterised by elevated Na/K ratio, and increased milk IL-8 concentrations. SCM affecting the breastfeeding mother may result in modulation of infant mucosal immune system development, whilst in ruminants notable milk production losses may ensue. In the case of clinical lactational mastitis, we will focus on mastitis caused by Staphylococcus aureus and Escherichia coli. Understanding of the pathogenesis of involution-associated mastitis requires characterization of the structural and molecular changes occurring during involution and we will review these changes across species. We speculate that milk accumulation may act as a nidus for infection, and that the involution ‘wound healing phenotype’ may render the tissue susceptible to bacterial infection. We will discuss the impact of concurrent pregnancy and a ‘parallel pregnancy and involution signature’ during bovine mammary involution.

The Multifaceted Role of STAT3 in Mammary Gland Involution and Breast Cancer

“…Mammary gland involution in the dairy cow frequently differs from murine models in that cows in dairy production systems are likely to be in the final trimester of pregnancy during the period of mammary gland involution (termed the dry period) [ 53 ], and thus may exhibit what we have described as a ‘parallel pregnancy signature’ [ 54 ]. Bovine mammary involution is considered to encompass both a phase of cell death, but also an important period of epithelial cell renewal prior to the next lactation [ 55 , 56 , 57 ].…”

Expression Profiles of Inflammation-related MicroRNAs in Mycoplasma bovis Infected Milk of Holstein-Friesian and Doğu Anadolu Kırmızısı Cows

“…Failure to detect subclinical mastitis promptly allows the infection to spread rapidly (Halasa et al, 2007;Hughes and Watson, 2018). Increasing evidence in recent years suggests that M. bovis is a major cause of severe mastitis infections (Vahanikkila et al, 2019;Murai and Higuchi, 2019;Josi et al, 2018) and that M. bovis is more frequently detected than other pathogens in subclinical mastitis (Al-Farha et al, 2017;Fox 2012;Nicholas et al, 2016).…”

Size of supernumerary teats in sheep correlates with complexity of the anatomy and microenvironment

“…The stromal compartment of the mammary microenvironment also includes fibroblasts and smooth muscle cells (Hughes & Watson, 2018a), constituents which are particularly important in the teat (Fig. 3).…”