PDF(Pubmed)
Abstract：
Heat stress negatively affects health, welfare, and livestock productivity by impairing immune function, increasing disease incidence. In recent years, there has been increasing interest in understanding the immune system of water buffalo due to the growing economic impact of this species for the high quality and nutritional value of buffalo milk. While there are common responses across bovine and buffalo species, there are also some species-specific variations in the physiological responses to heat stress, mainly attributed to differences in metabolism and heat dissipation efficiency. At cellular level, the exposure to thermal stress induces several anomalies in cell functions. However, there is limited knowledge about the differential response of bovine and buffalo leucocytes to early and late exposure to different degrees of thermal exposure. The aim of this study was to compare the in vitro effect of hyperthermia on apoptosis and phagocytosis in leukocytes from bovine and buffalo species. For this, whole blood samples of six bovines and nine buffaloes were incubated at 39°C (mimicking normothermia condition) or 41°C (mimicking heat stress condition) for 1, 2, and 4 h. Two flow cytometric assays were then performed to evaluate apoptosis and determine functional capacity of phagocytic cells (neutrophils and monocytes). The results showed that the viability of bovine and buffalo leukocytes was differently affected by temperature and time of in vitro exposure. A higher percentage of apoptotic leukocytes was observed in bovines than in buffaloes at 39°C (3.19 vs. 1.51, p < 0.05) and 41°C (4.01 vs. 1.69, p < 0.05) and for all incubation time points (p < 0.05). In contrast, no difference was observed in the fraction of necrotic leukocytes between the two species. In both species, lymphocytes showed the highest sensitivity to hyperthermia, showing an increased apoptosis rates along with increased incubation time. In bovine, apoptotic lymphocytes increased from 5.79 to 12.7% at 39°C (p < 0.05), in buffalo, this population increased from 1.50 to 3.57% at 39°C and from 2.90 to 4.99% at 41°C (p < 0.05). Although no significant differences were found between the two species regarding the percentage of phagocytic neutrophils, lower phagocytosis capacity values (MFI, mean fluorescence intensity) were found in bovines compared with buffaloes at 41°C (27960.72 vs. 53676.45, p > 0.05). However, for monocytes, the differences between species were significant for both phagocytosis activity and capacity with lower percentages of bovine phagocytic monocytes after 2 h at 39°C and after 1 h at 41°C. The bovine monocytes showed lower MFI values for all temperature and time variations than buffaloes (37538.91 vs. 90445.47 at 39°C and 33752.91 vs. 70278.79 at 41°C, p < 0.05). In conclusion, the current study represents the first report on the comparative analysis of the effect of in vitro heat stress on bovine and buffalo leukocyte populations, highlighting that the leukocytes of buffalo exhibit relatively higher thermal adaptation than bovine cells.
摘要：
热应激对健康有负面影响，福利,通过损害免疫功能来提高牲畜的生产力，增加疾病发病率。近年来,人们对了解水牛的免疫系统越来越感兴趣，这是由于水牛的高质量和营养价值对水牛的经济影响越来越大。虽然牛和水牛物种有共同的反应，对热应激的生理反应也有一些物种特异性的变化，主要归因于新陈代谢和散热效率的差异。在细胞水平，暴露于热应力会引起细胞功能的几种异常。然而,关于牛和水牛白细胞对早期和晚期暴露于不同程度的热暴露的差异反应的知识有限。这项研究的目的是比较热疗对牛和水牛物种白细胞凋亡和吞噬作用的体外影响。为此，将6只牛和9只水牛的全血样品在39°C（模拟常温条件）或41°C（模拟热应激条件）孵育1、2和4小时。然后进行两次流式细胞术测定以评估细胞凋亡并确定吞噬细胞（中性粒细胞和单核细胞）的功能能力。结果表明，体外暴露温度和时间对牛和水牛白细胞的活力有不同的影响。在39°C时，在牛中观察到的凋亡白细胞百分比高于水牛（3.19vs.1.51，p<0.05）和41°C（4.01vs.1.69，p<0.05）和所有孵育时间点（p<0.05）。相比之下,两个物种之间的坏死白细胞分数没有观察到差异。在这两个物种中，淋巴细胞对热疗的敏感性最高，随着孵育时间的增加，细胞凋亡率增加。在牛，凋亡淋巴细胞在39°C时从5.79％增加到12.7％（p<0.05），在水牛,该人群在39°C时从1.50增加到3.57％，在41°C时从2.90增加到4.99％（p<0.05）。尽管两个物种之间在吞噬中性粒细胞的百分比方面没有发现显着差异，较低的吞噬能力值(MFI，与41°C的水牛相比，在牛中发现了平均荧光强度）（27960.72vs.53676.45，p>0.05）。然而,对于单核细胞，在39℃2小时后和41℃1小时后，物种之间的吞噬活性和能力差异显著，牛吞噬单核细胞的百分比较低。牛单核细胞在所有温度和时间变化下的MFI值均低于水牛（37538.91vs.90445.47在39°C和33752.91与70278.79在41°C,p<0.05)。总之,本研究代表了体外热应激对牛和水牛白细胞种群影响的比较分析的第一份报告，强调水牛的白细胞比牛细胞表现出相对较高的热适应性。
