Tadmor-Levi Roni, Sharabi Lior, Koren Adi, Schlesinger Sharon, Tzirkel-Hancock Noam, Argov-Argaman Nurit
The Robert H. Smith Faculty of Agriculture, Food and Environment Sciences, The Hebrew University of Jerusalem, POB 12, 7610001, Rehovot, Israel.
Stem Cell Res Ther. 2025 Jun 23;16(1):320. doi: 10.1186/s13287-025-04442-y.
Increased production of the modern dairy cow can induce a stress response by the mammary epithelial cells (MEC) and compromise production traits. To alleviate this stress response, various strategies have been tested. Previous studies have shown an immunomodulatory effect of mesenchymal stem cells (MSC) and their secretome on different cell types and tissues; however, their effect in the context of lactation performance has not yet been studied. In this study, we aimed to assess the effects of MSC and their secretome on the stress response and lipogenesis in bovine MEC.
We measured gene expression, lipid droplet (LD) characteristics, and triglyceride content in bovine MEC subjected to stress. The effect of co-culturing with MSC or their secretome, used as conditioned media (CM) was evaluated in the same context.
In MEC, lipopolysaccharide (LPS) triggered a progressive rise in pro-inflammatory cytokines, while HO predominantly activated lipogenic pathways. More specifically, acetyl-CoA carboxylase (ACC) expression significantly increased in response to HO, whereas no change was observed in LPS-treated cells. Fatty acid synthase (FASN) expression decreased under LPS and remained unchanged under HO. Stearoyl-CoA desaturase (SCD1) expression was significantly elevated by LPS but remained stable under HO. Both stressors increased triglyceride content of MEC after 48 h and reduced intracellular LD size. When MEC were co-cultured with MSC, the response to LPS was attenuated, as indicated by lower expression of the pro-inflammatory genes, interleukin 6 (IL-6) and tumor necrosis factor α (TNFα). Using MSC secretome as CM for MEC led to reduced expression of TNFα and IL-6 under both basal conditions and in response to LPS. Interestingly, independent of external stress, MSC secretome significantly increased the expression of all lipogenic genes, including FASN, ACC and diacylglycerol acyl-transferase (DGAT).
These results demonstrate that the lipogenic capacity of MEC as well as their intracellular LD size and number, are integral to the stress response. MSC exerted an immunomodulatory effect on MEC and enhanced their lipogenic capacity. This effect is at least partly mediated by paracrine factors, and does not require physical contact between MEC and MSC. Further studies are warranted to identify the bioactive components, which could be used to enhance MEC bioactivity during lactation.
现代奶牛产量的增加会引发乳腺上皮细胞（MEC）的应激反应，并损害生产性能。为了缓解这种应激反应，人们已经测试了各种策略。先前的研究表明，间充质干细胞（MSC）及其分泌组对不同的细胞类型和组织具有免疫调节作用；然而，它们在泌乳性能方面的作用尚未得到研究。在本研究中，我们旨在评估MSC及其分泌组对牛MEC应激反应和脂肪生成的影响。
我们测量了应激状态下牛MEC中的基因表达、脂滴（LD）特征和甘油三酯含量。在相同背景下评估了与MSC或其分泌组（用作条件培养基（CM））共培养的效果。
在MEC中，脂多糖（LPS）引发促炎细胞因子的逐渐升高，而己酮可可碱（HO）主要激活脂肪生成途径。更具体地说，乙酰辅酶A羧化酶（ACC）的表达在HO刺激下显著增加，而在LPS处理的细胞中未观察到变化。脂肪酸合酶（FASN）的表达在LPS作用下降低，在HO作用下保持不变。硬脂酰辅酶A去饱和酶（SCD1）的表达在LPS作用下显著升高，但在HO作用下保持稳定。两种应激源在48小时后均增加了MEC的甘油三酯含量，并减小了细胞内LD的大小。当MEC与MSC共培养时，促炎基因白细胞介素6（IL-6）和肿瘤坏死因子α（TNFα）的表达降低，表明对LPS的反应减弱。使用MSC分泌组作为MEC的CM导致在基础条件下以及对LPS反应时TNFα和IL-6的表达降低。有趣的是，独立于外部应激，MSC分泌组显著增加了所有脂肪生成基因的表达，包括FASN、ACC和二酰基甘油酰基转移酶（DGAT）。
这些结果表明，MEC的脂肪生成能力以及其细胞内LD的大小和数量，是应激反应不可或缺的部分。MSC对MEC发挥了免疫调节作用，并增强了它们的脂肪生成能力。这种作用至少部分是由旁分泌因子介导的，并且不需要MEC和MSC之间的物理接触。有必要进行进一步的研究以确定生物活性成分，这些成分可用于在泌乳期间增强MEC的生物活性。
