Synergism between antibody and neutrophils in the ruminant mammary gland

Immunological activities of the mammary gland are important both as a means of transferring immunity from mother to young and for defending the mammary gland itself against infection. The presence of immunoglobulins G1, G2 and A, and of neutrophils, macrophages and complement in the ruminant mammary gland is described, in particular the synergistic role of antibody and neutrophils is discussed and studies of immunization against staphylococcal mastitis are outlined.     

Small ruminant lentiviruses: immunopathogenesis of visna-maedi and caprine arthritis and encephalitis virus

The small ruminant lentiviruses include the prototype for the genus, visna-maedi virus (VMV) as well as caprine arthritis encephalitis virus (CAEV). Infection of sheep or goats with these viruses causes slow, progressive, inflammatory pathology in many tissues, but the most common clinical signs result from pathology in the lung, mammary gland, central nervous system and joints. This review examines replication, immunity to and pathogenesis of these viruses and highlights major differences from and similarities to some of the other lentiviruses.     

Physiology of the periparturient period and its relation to severity of clinical mastitis

Incidence of clinical mastitis is highest at drying off and during the periparturient period. Intramammary Escherichia coli infection in high-yielding cows can show a severe clinical response during the early post-partum period. Severe clinical mastitis is mainly determined by cow factors, in particular the functionality of the circulating polymorphonuclear leukocytes (PMN) which are recruited to the mammary gland during the inflammatory reaction. There is a co-incidence between the periods of highest incidence of clinical mastitis and specific structural changes in the mammary gland. During the periparturient period, marked changes in various systemic and local hormones are related to the secretory state of the mammary gland epithelium (lactogenesis). Estrogen and progesterone induce proliferation of the mammary epithelium throughout gestation and act as survival factors in different tissues, although conflicting data have been reported on their effect on PMN oxidative burst. Somatotropin (STH), responsible for maintenance of lactation in ruminants, has been shown to positively influence innate immunity and a more rapid recovery in milk production of severely affected animals. The concentration of STH, and as a result also IGF-I levels is, however, quite low during early lactation. IGF-I and its regulating binding proteins are associated with cell survival, modulation of apoptosis and functionality of PMN in humans. During early lactation, bio-availability of IGF-I is decreased, which might reduce its stimulating effects on PMN quality and functionality. PRL, concomitantly known as a lactogenic hormone and an immunoregulatory cytokine, has also been associated with modulation of the immune system. It is expected that in periparturient animals, hormone changes could interfere with the immune response and the clinical response of mastitis.     

Immunolocalization of lingual antimicrobial peptide (LAP) in the bovine mammary gland

Lingual antimicrobial peptide (LAP), a member of the β-defensin family in cows, is involved in the innate immune system and plays a crucial role in killing a large variety of microorganisms. The aim of the present study was to demonstrate the immunolocalization of LAP in the mammary glands of cows. A LAP antibody was raised in a rabbit by immunity with a synthetic 11 amino acid sequence out of a 42-amino acid sequence of the mature form of LAP. The specificity of the LAP antibody was checked using a competitive immunoassay and Western blotting. Paraffin sections of the mammary gland were immunostained with LAP antibody. In the competitive immunoassay, an increase of synthetic LAP concentration suppressed the optical density. Western blotting analysis for LAP revealed the presence of the LAP peptide in mammary alveolar tissue. When the mammary gland was immunostained with LAP antibody, epithelial cells of both infected and non-infected alveoli were immunopositive. These results indicate that LAP is localized in the epithelium of non-infected as well as infected alveolus in the mammary gland in cows.     

体液防御在奶牛乳腺组织先天性免疫中的作用

深入研究乳腺组织的免疫防御对制定控制乳腺炎的措施非常重要。乳腺的先天性免疫是一个非常广泛的研究领域,尽管经过多年的研究,但目前对乳腺先天性防御的相关知识仍旧非常缺乏。本文综述了近年来关于奶牛乳腺组织的体液防御在其先天性免疫中的功能和作用机制的研究结果。     

高精料饲粮条件下反刍动物瘤胃适应机制的解析

饲喂高能、高淀粉饲粮是集约化生产中提高反刍动物生产性能的常用策略,但高精料饲粮易引起一系列的营养代谢疾病,其中以瘤胃酸中毒最为常见。反刍动物瘤胃不仅具有消化、吸收营养物质的功能,瘤胃上皮亦是重要的免疫屏障,故瘤胃健康对反刍动物至关重要。本文主要从反刍动物采食高精料饲粮时其瘤胃组织形态、瘤胃上皮适应分子机制和瘤胃微生物区系3个方面的变化进行阐述,以期为高精料饲粮条件下瘤胃适应机制的研究提供参考。     

Effects of bovine leukemia virus infection on milk neutrophil function and the milk lymphocyte profile

The effects of bovine leukemia virus (BLV) on the immune response have been extensively investigated; however, its effects on mammary gland immunity are only speculative. Although BLV has a tropism for B cells, it can affect both adaptive and innate immunities because these systems share many effector mechanisms. This scenario is the basis of this investigation of the effects of BLV on mammary gland immunity, which is largely dependent upon neutrophilic functions. Thus, the present study sought to examine neutrophilic functions and the lymphocyte profile in the milk of naturally BLV-infected cows. The viability of the milk neutrophils and the percentage of milk neutrophils that produced reactive oxygen species (ROS) or phagocytosed Staphylococcus aureus were similar between BLV-infected and BLV-uninfected dairy cows. Furthermore, the expression of CD62L and CD11b by the milk neutrophils and the percentage of milk neutrophils (CH138⁺ cells) that were obtained from the udder quarters of the BLV-infected cows were not altered. Conversely, the median fluorescence intensity (MFI) representing intracellular ROS production and the phagocytosis of S. aureus, the expression of CD44 by the milk neutrophils and the percentage of apoptotic B cells were lower in the milk cells from BLV-infected dairy cows, particularly those from animals with persistent lymphocytosis (PL). The lymphocyte subsets were not different among the groups, with the exception of the percentage of CD5⁻/CD11b⁻ B cells, which was higher in the milk cells from BLV-infected cows, particularly those with PL. Thus, the present study provides novel insight into the implications of BLV infection for mammary gland immunity.     

Expression of potential lymphocyte trafficking mediator molecules in the mammary gland

The mammary gland performs a variety of immunological functions, including protecting itself from mastitis and protecting neonates from infectious agents. Several molecules that mediate lymphocyte trafficking in the immune system are also expressed in the mammary gland. This review is focused on the immunological function of these molecules, especially glycosylation-dependent cell adhesion molecule-1 (GlyCAM-1) and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) in the mammary gland. GlyCAM-1 is expressed in the lactating mouse mammary gland. Endothelial cells produce this protein and secrete it into milk. The glycosylated modification of mammary gland GlyCAM-1 is different from that of the lymph nodes, and lacks the binding ability for L-selectin on lymphocytes. GlyCAM-1 in the mammary gland is not involved in lymphocyte migration, and probably has another function besides that of the lymph nodes. MAdCAM-1 is expressed on endothelial cells of small venules around mouse mammary lobules during lactation. This molecule has the ability to interact with alpha4beta7 integrin on lymphocytes and mediates lymphocyte recruitment to the mammary gland. The density of beta7+/CD3+ T-cells is correlated with the density of the MAdCAM-1-stained area, suggesting that MAdCAM-1 may mediate the migration of these cells. In contrast, there is no relationship between MAdCAM-1 expression and the number of beta7+/c-IgA+ B-cells, implying that some other factor is involved in lymphocyte migration to the mammary gland. Chemokines, such as IL-8, GRO-alpha, MCP-1, RANTES and MEC, have been detected in human and mouse mammary glands. Although little information is available, these molecules may contribute to lymphocyte migration to the mammary gland.     

The mammary gland and neonate mucosal immunity

The passive mucosal protection of neonate mammals is dependent on the continuous supply until weaning of maternally dimeric IgA (monogastric) and IgG1 (ruminants). This lactogenic (humoral) immunity is linked to the gut, the so-called entero-mammary link, because of the translocation of Ig (IgA and IgG1) or the emigration of IgA lymphoblasts from the gut into the mammary gland (MG); on the other hand, studies on the lymphocyte subsets in the MG of artiodactyls sustained the view of a true local immune response, depending on the MG stage development. Accordingly, the increase of the lactogenic immunity may focus on (1) inductor sites (gut and, possibly, the MG), (2) increase in cell traffic from the gut into the MG, and (3) enhancement at the effector site of the Ig production and excretion in milk. A specific mucosal environment (interleukins and hormones) is responsible for IgM/IgA switch, the induction of mucosal homing receptor onto lymphoblasts and mucosal vascular addressins; very few data are available for the mechanism of lymphoblasts recruitment, either IgA or IgG1, although lactogenic hormones have been implicated in the IgA-blasts homing into the mice MG. After weaning, the neonate is able to mount a gut immune response, but the shortage of the suckling period did not seem to be detrimental for its onset. In soyabean allergy, both piglet and calf exhibited gut villus atrophy, gut accumulation of IgA (swine) and IgG1 (cattle) immunocytes, sustaining the view that a specific environment in ruminant is responsible for both IgA and IgG1 production.     

ASAS centennial paper: Lactation biology for the twenty-first century

Knowledge of general aspects of mammary gland function, including metabolic pathways and hormonal regulation of mammary gland development and lactation, in livestock species was obtained several decades ago. As basic biological information of growth factor action, apoptotic mechanisms, and signal transduction events has exploded, the mouse became the model of choice for studying fundamental mechanisms regulating mammary function. A complete sequenced genome also has made the mouse amenable for studies of mammary gene network expression. Advances in molecular biology techniques currently allow researchers to genetically modify mice to either overexpress or completely lack specific genes, thereby studying their function in an in vivo setting. Furthermore, the use of mammary-specific promoters has allowed genes related to mammary gland function to be eliminated from the mammary gland in a developmental and tissue-specific manner. These studies have demonstrated the complexity that underlies mammary gland development and function in rodents and may provide insight into the mechanisms that ultimately allow the ruminant or swine mammary gland to function in a coordinated fashion throughout puberty, pregnancy, lactation, and involution. The challenge facing animal scientists is how to obtain similar information in much larger and expensive livestock. One possible approach is to manipulate gene expression in vitro using mammary cell culture models derived from domestic animals (e.g., genes can be "knocked down" using small interfering RNA approaches). Ultimately, major advances in understanding lactation biology may come from coupling basic mechanistic information with functional genomics, proteomics, and metabolomics approaches. A strong foundation in bioinformatics will also be required to optimize use of these new technologies. Stem cell biology also represents an exciting area in the next decade that holds promise for improving lactation efficiency. Strong training of our future scientists in these areas should facilitate livestock-focused mammary gland research that will allow basic information to be gained at unprecedented amounts, ultimately leading to optimization of livestock production.     

荷斯坦乳牛乳腺和乳腺上皮细胞中Toll样受体及辅助因子编码基因的检测

参照牛TLR4、TLR2、CD14、MD-2基因序列设计了相应基因的引物。采用RT-PCR技术检测了体外培养的荷斯坦乳牛乳腺和乳腺上皮细胞中Toll样受体TLR4、TLR2及辅助因子CD14、MD-2基因。结果显示,乳腺上皮细胞中存在TLR4、TLR2、CD14和MD-2四个基因的表达,而乳腺中除MD-2未检测到外,其余3个基因均扩增成功。说明该受体及辅助因子可能参与了乳腺的先天性免疫防御。该研究为探讨乳腺的先天性免疫及乳腺上皮细胞在乳腺先天性免疫中的作用奠定了基础。     

Research Progress on Primary Culture,Purification and Identification Technique of Bovine Mammary Epithelial Cells

The bovine mammary epithelial cells not only have the function of synthesis and secretion of milk, but also play an important role in innate immunity system of the mammary gland, and there is great significance of them on studying the mechanism of lactation, mastitis pathogenesis and drug screening.Primary cultured bovine mammary gland epithelial cells are suitable for setting up cell model which can be used as the dielectric for physiological, pathological and pharmacological researching, avoiding the difficulties of in vivo test, such as the long cycle, the high cost, the individual difference, etc.The author summarized the latest researches of cell primary culture in vitro, cultivation technology, purification and identification method in order to provide reference for the studies of bovine mammary epithelial cells culture.     

奶牛乳腺上皮细胞原代培养、纯化及鉴定技术研究进展

奶牛乳腺上皮细胞不仅具有合成和分泌乳汁的功能,而且在乳腺的先天免疫中扮演着重要角色,对泌乳机制、乳房炎发病机制的研究,以及药物筛选具有重要意义。原代培养的奶牛乳腺上皮细胞适宜建立细胞模型,可作为生理、病理、药理等方面研究的良好介质,解决体内试验周期长、成本高、个体差异大的难题。作者主要从奶牛乳腺上皮细胞原代培养的发展历程、培养技术、纯化技术及鉴定方法等方面的最新研究情况进行综述,以期为奶牛乳腺上皮细胞培养相关研究提供参考。     

Expression of leptin and its receptors in various tissues of ruminants

The energy metabolism of domestic animals is under the control of hormonal factors, which include thyroid hormones and leptin. Leptin signals from the periphery to the centre. It is mostly produced in the white adipose tissue and informs the central nervous system (CNS) about the total fat depot of the body. Low and high levels of leptin induce anabolic and catabolic processes, respectively. Besides controlling the food uptake and energy expenditure leptin is also involved in regulation of the reproduction and the immune system. Leptin is produced in several tissues other than fat. In the present paper the leptin expression of ruminant (Egyptian water buffalo, cow, and one-humped camel) tissues are examined. The mammary gland produces leptin in each species investigated. The local hormone production contributes to milk leptin and most probably helps to maintain lactation. Considerable leptin receptor expression was observed in the milk-producing epithelial cells, which is the same cell type that produces most of the udder leptin. Based on the results tissues participating in production have an autoregulative mechanism through which tissues can be relatively independent of the plasma leptin levels in order to maintain the desired function.     

Staphylococcus aureus intramammary infection elicits increased production of transforming growth factor-alpha, beta1, and beta2

In contrast to other mastitis pathogens, the host response evoked during Staphylococcus aureus intramammary infection is marked by the absence of the induction of critical cytokines, including IL-8 and TNF-alpha, which have established roles in mediating host innate immunity. The elucidation of changes in the expression of other mediators with the potential to regulate mammary inflammatory responses to S. aureus remains lacking. Transforming growth factor (TGF)-alpha, TGF-beta1, and TGF-beta2 are cytokines that regulate mammary gland development. Because these cytokines also have a demonstrated role in mediating inflammation, the objective of the current study was to determine whether S. aureus intramammary infection influences their expression. Ten cows were challenged with S. aureus and milk samples collected. Increases in milk levels of TGF-alpha were evident within 32h of infection and persisted for 16h. Increases in TGF-beta1 and TGF-beta2 levels were detected within 40h of S. aureus infection and persisted through the end of the study. Thus, in contrast to IL-8 and TNF-alpha, S. aureus elicits host production of TGF-alpha, TGF-beta1, and TGF-beta2. This finding may suggest a role for these cytokines in mediating mammary gland host innate immune responses to S. aureus.     

2008-2009年反刍动物营养研究进展Ⅳ.脂肪营养

反刍动物产品是膳食的重要组成,其脂肪品质及脂肪酸组成与人体健康密切相关。笔者综述了2009年在ADSA-ASAS大会、ASAS-CAAV大会和CNKI、PubMed等数据库中与反刍动物脂类营养相关的文献。研究热点主要集中于添加油脂对产品中脂肪组成的调控作用、日粮脂肪在瘤胃的代谢作用、乳腺脂肪酸代谢机制及脂肪代谢相关基因的研究。     

奶牛干奶期乳腺免疫力低下机理及影响因素分析

奶牛乳腺自身抵抗力下降是乳腺炎发生的直接原因,也是兽医产科学研究的重点,从提高奶牛自身抵抗力预防乳腺炎的发生已成近年来研究的新热点,作者着重就奶牛在泌乳周期中尤其是干奶期抵抗力下降的机理做了必要的分析和探讨,对影响干奶期免疫力低下的一些因素也作了详尽阐述,这些方面的论述对乳腺机能方面的进一步研究和预防乳腺炎的发生有一定的参考和应用价值。     

家禽训练免疫研究进展

微生物耐药是威胁人类健康、动物保健和食品安全的重大问题。为减少耐药性及动物源食品的药物残留,迫切需要探索预防和治疗疾病的替代机制,其中之一便是激活先天免疫系统对病原体攻击产生强而持久的非特异性免疫应答,这一过程称为训练免疫,即先天免疫记忆。愈来愈多的研究表明,天然免疫细胞甚至组织驻留干细胞对某些感染和疫苗接种具有保护免受再感染的免疫记忆功能,即先天免疫系统也表现出适应性免疫特征。在兽医研究领域,通过改善先天免疫系统提高家禽抗病能力的概念并不新颖,但极少有可用的、有目的的针对训练免疫的应用研究。通过训练免疫途径增强动物免疫力是一个值得关注的崭新领域,将为设计新型广谱疫苗和寻找新的药物靶点开辟新的途径。笔者综述了训练免疫领域的最新进展,阐述了家禽训练免疫调控及未来研究方向。