Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
Department of Large Animal Clinical Sciences, Michigan State University, 736 Wilson Road, East Lansing 48824.
J Dairy Sci. 2018 Jul;101(7):6542-6555. doi: 10.3168/jds.2017-13777. Epub 2018 Apr 5.
The aim of this study was to determine the number of adipose tissue macrophages (ATM) and the mRNA expression of adipokines [adiponectin (ADIPOQ), leptin (LEP), interleukin 6 (IL6), tumor necrosis factor (TNF), and interleukin 10 (IL10)] in different adipose depots from cows with a variable body condition score (BCS) at the end of the dry period. We hypothesized that the number of ATM and the expression of these adipokines depend on adipocyte size and the anatomical location of the adipose depot. Subcutaneous, omental, mesenteric, perirenal, and intrapelvic adipose tissue samples were taken immediately after euthanasia of 10 Holstein Friesian dairy cows (upcoming parity 2 to 5, age 3.9 ± 1.4 yr; mean ± standard deviation) at the end of pregnancy (actual days of pregnancy at the moment of euthanasia: 269 ± 5 d). During the dry period, all animals received similar diets to meet but not exceed requirements. Five animals were considered to have a normal BCS (2.5-3.5) and 5 animals were considered to be over-conditioned (BCS = 3.75-5). Body weight of the animals at the moment of euthanasia was 717 ± 77 kg. Expression of the different genes was determined by reverse transcription quantitative real-time PCR. Adipocyte size was determined by measuring the area of 100 adipocytes on histological sections. Average adipocyte area was 10,475 ± 1,019, 8,500 ± 780, 10,383 ± 1,227, 11,466 ± 1,039, and 11,087 ± 1,632 µm for the subcutaneous, mesenteric, omental, intrapelvic, and perirenal adipose depot, respectively. Immunohistochemistry using anti-bovine CD172a antibodies was performed to determine the proportion of ATM (the number of CD172a-positive cells per 100 adipocytes, given as a percentage). Expression of LEP, IL6, and TNF was positively associated with adipocyte size, whereas no association could be detected between ADIPOQ and IL10 with the size of the adipocytes. The omental adipose depot was especially infiltrated with ATM (1.92 ± 0.55, 1.10 ± 0.33, and 8.28 ± 2.24% for the subcutaneous, mesenteric, and omental adipose depot, respectively). The proportion of ATM was positively associated with the size of the adipocytes in the omental and mesenteric adipose depot. Expression of ADIPOQ, LEP, IL6, TNF, and IL10 differed among depots, which suggests differences in inflammatory characteristics depending on the anatomical location of depots. In conclusion, the results of the present study confirm the adipose tissue as a potential source of inflammatory mediators and demonstrate ATM infiltration, especially in the omental adipose depot.
本研究旨在确定不同体况评分（BCS）奶牛在干奶期末不同脂肪组织中脂肪组织巨噬细胞（ATM）的数量和脂肪因子[脂联素（ADIPOQ）、瘦素（LEP）、白细胞介素 6（IL6）、肿瘤坏死因子（TNF）和白细胞介素 10（IL10）]的 mRNA 表达。我们假设 ATM 的数量和这些脂肪因子的表达取决于脂肪细胞的大小和脂肪组织的解剖位置。在妊娠末期（安乐死时实际妊娠天数：269 ± 5 天），10 头荷斯坦弗里森奶牛（即将分娩 2-5 胎，年龄 3.9 ± 1.4 岁；平均值 ± 标准差）安乐死后，立即从皮下、网膜、肠系膜、肾周和盆腔内脂肪组织中取样。在干奶期，所有动物都接受了类似的饮食，以满足但不超过需求。5 只动物被认为体况正常（2.5-3.5），5 只动物被认为是过肥（BCS=3.75-5）。安乐死时动物的体重为 717 ± 77 公斤。通过逆转录定量实时 PCR 确定不同基因的表达。通过测量组织学切片上 100 个脂肪细胞的面积来确定脂肪细胞的大小。皮下、肠系膜、网膜、盆腔内和肾周脂肪组织的平均脂肪细胞面积分别为 10475 ± 1019、8500 ± 780、10383 ± 1227、11466 ± 1039 和 11087 ± 1632 µm。使用抗牛 CD172a 抗体进行免疫组织化学染色，以确定 ATM 的比例（每 100 个脂肪细胞中 CD172a 阳性细胞的数量，以百分比表示）。LEP、IL6 和 TNF 的表达与脂肪细胞大小呈正相关，而 ADIPOQ 和 IL10 与脂肪细胞大小之间没有关联。网膜脂肪组织特别被 ATM 浸润（皮下、肠系膜和网膜脂肪组织分别为 1.92 ± 0.55、1.10 ± 0.33 和 8.28 ± 2.24%）。ATM 的比例与网膜和肠系膜脂肪组织中脂肪细胞的大小呈正相关。ADIPOQ、LEP、IL6、TNF 和 IL10 的表达在不同的脂肪组织中存在差异，这表明脂肪组织的炎症特征因解剖位置的不同而不同。总之，本研究的结果证实了脂肪组织是炎症介质的潜在来源，并证明了 ATM 的浸润，特别是在网膜脂肪组织中。
