An Immunogenomics Approach to Understanding Periparturient Immunosuppression and Mastitis Susceptibility in Dairy Cows*

Abstract

<p/> <p>Studies comparing in vivo and in vitro functional capacities of leukocytes from non-parturient and periparturient dairy cows have provided substantial evidence that systemic and local mammary immune defenses are deficient around parturition. This evidence has lead to the reasonable hypothesis that immune deficiency underlies the heightened mastitis susceptibility of periparturient cows. Nutrition and vaccine studies substantiate this hypothesis, showing that dietary antioxidant supplementation and rigorous immunization regimes can bolster innate and humoral immunity to the point that mastitis severity and time for return to normal milk production are reduced. However, completely effective resolution of this significant production disease has not been achieved because so little is understood about its complex etiology. In particular, we possess almost no knowledge of how or why immune cells responding to parturient physiology end up with deficient functional capacities. Fluctuations in reproductive steroid hormones and chronic shifts in neuroendocrine hormones with roles in nutrient partitioning and appetite control may affect the expression of critical leukocyte genes in periparturient dairy cows. A thorough understanding of leukocyte biology during periparturition would seem a critical goal for future development of effective mastitis prevention strategies. Recently, our group has begun to use cDNA microarray technology to explore bovine leukocyte RNA for global gene expression changes occurring around parturition. We are working within the context of a hypothesis that the physiology of parturition negatively affects expression of critical genes in blood leukocytes. In the current study we initiated hypothesis testing using leukocyte RNA from a high producing Holstein cow collected at 14 days prepartum and 6 hours postpartum to interrogate a cDNA microarray spotted with >700 cDNAs representing unique bovine leukocyte genes. This analysis revealed 18 genes with ≥1.2-fold higher expression 14 days prepartum than 6 hours postpartum. BLASTN analysis of these genes revealed only one that can be considered a classical immune response gene. All other repressed genes were either unknown or putatively identified as encoding key proteins involved in normal growth and metabolism of cells. Given the critical roles of these repressed genes in normal cell functions, we may have identified good candidates to pursue with respect to periparturient immunosuppression and mastitis susceptibility.</p

Evidence for a Novel Gene Expression Program in Peripheral Blood Mononuclear Cells fromMycobacterium aviumsubsp.paratuberculosis-Infected Cattle

“…The cDNA microarrays used in this study (BOTL-3 cDNA microarrays) were an expanded version of those described previously (6,13,45). Each microarray contained 3,888 spots consisting of 709 bovine expressed sequence tag (EST) clone inserts and 345 amplicons representing known immune response genes derived from the bovine sequence (15), all spotted in triplicate (3,162 gene spots).…”

“…Recently, development of cDNA microarrays containing 724 unique bovine genes specifically targeted to enhance studies of bovine immunobiology was described (6,45). This BOTL-2 (bovine total leukocyte, version 2) cDNA microarray was used to demonstrate differences in the gene expression profiles of PBMCs isolated from cattle in various stages of Johne's disease (13).…”

Adrenomedullin (AM) and adrenomedullin binding protein (AM-BP) in the bovine mammary gland and milk: Effects of stage of lactation and experimental intramammary E. coli infection

“…The time around calving is recognized as a period of increased disease incidence in cows [22,23,[36][37][38]. Periparturient susceptibility to disease is attributed to residual degrees of compromised immune functions that persist as a carryover from hormone and cytokine interactions that were needed to maintain pregnancy (i.e., pregnancy-related immunosuppression to prevent embryonic allograph rejection by maternal tissues, [38,39]), but are in fact in the process of being downregulated as fetal maturation signals prompt the initiation of separation of the calf from the mother at parturition [40].…”

“…Because of its multiple effects on tissue function and survival as well as its properties as an antimicrobial peptide, we were interested to determine whether AM levels in bovine milk and mammary tissue might be associated with or reflective of the changes in udder health status and general mammary physiology that have been documented with regard to the impact of stage of lactation, especially around calving and presence of mammary infection [21][22][23]. Employing immunohistochemical image analysis techniques as well as RIA and Western blot approaches, we report here for the first time quantified localized changes in tissue AM and AM-BP in mammary tissue of cows, as well as changes in concentrations of AM and AM-BP in milk as a function of lactational status, milk somatic cell count, or presence of intramammary infection.…”

Examination of animal and zoonotic pathogens using microarrays

“…The bovine DNA array work has primarily focused to interrogate normal physiology, pregnancy, lactation, and parturition [9,17,94] mainly to understand cell physiology under various conditions, however, there are so far very few studies to examine host-pathogen interactions. Band et al [8] developed a bovine microarray, which is now commercially available and has been used to study the response of bovine tissues to various pathogens.…”