Relationship between Oxidative Stress and Endometritis: Exploiting Knowledge Gained in Mares and Cows

Abstract

The etiopathogenesis of endometritis in mares and cows differs significantly; this could depend on a different sensitivity and reactivity of the uterus but also on endocrine and rearing factors and different stress sources. In both species, microorganisms and the immune system play a primary role in the generation of this pathology. Microbiological and cytological tests support clinical examination and significantly improve diagnostic accuracy. For both species, during the inflammation, immune cells invade the endometrium and release bioactive substances to contrast primary or secondary pathogen contamination. These molecules are traceable to cytokines, chemokines, and prostaglandins as well as reactive oxygen and nitrogen species (ROS and RNS), collectively known as RONS. The RONS-mediated oxidation causes morphological and functional alterations of macromolecules, such as proteins, lipids, and nucleic acids, with the consequent production of derivative compounds capable of playing harmful effects. These bioactive molecules and by-products, which have recently become increasingly popular as diagnostic biomarkers, enter the bloodstream, influencing the functionality of organs and tissues. This review has collected and compared information obtained in cows and mares related to the diagnostic potential of these biomarkers that are assessed by using different methods in samples from either blood plasma or uterine fluid.

Serological and Uterine Biomarkers for Detecting Endometritis in Mares

“…An increase in oxidant levels may be counteracted by an increase in the antioxidant barrier, maintaining an unchanged oxidant/antioxidant balance, as during the peripartum in the mares [43]; this resilience to OS is named eustress (OeS). Conversely, when OS cannot be efficiently contrasted and the oxidative damage of macromolecules becomes an irreversible occurrence, the organism undergoes a condition of distress (OdS) [18]. In the present study, the enhancement of the antioxidant barrier, as indicated by the increase in FRAP and TTL values, may be associated with the increase in NO x , which was significantly higher in the endometritis-negative than in the -positive mares, and aimed at maintaining the correct redox balance.…”

“…Along these lines, it seems interesting to develop alternative diagnostic approaches to detect uterine inflammation without a direct intervention on the uterus. This topic was investigated in a recent review aimed at gathering information on the equine and bovine species of blood biomarkers linked to oxidative stress and associated with endometritis occurrence [18]. In the present study, the blood levels of markers associated with redox balance, inflammation, and protease regulator potential have been assessed in mares at the time of estrus and before insemination in order to highlight possible diagnostic evidence of endometritis without accessing the endometrium.…”

New Insights into Polymorphisms in Candidate Genes Associated with Incidence of Postparturient Endometritis in Ossimi Sheep (Ovis aries)

“…The immunological alterations and genetic variants associated with postpartum endometritis in sheep are equally little understood, and few reliable diagnostic and prognostic instruments are available to help us in the development of our preventive and treatment strategies [24,25]. It is imperative to underscore that further investigation is required to detect any pertinent immunological markers linked to reproductive concerns, which may ascertain whether sheep exhibit resistance to them.…”