Nutrition Program, School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, OR, USA.
Department of Pediatrics, Oregon Health and Science University, Portland, OR, USA.
J Nutr. 2022 Jan 11;152(1):331-342. doi: 10.1093/jn/nxab350.
Milk proteins contain many encrypted bioactive peptides. Whether these bioactive peptides are released in the infant intestine and exert immunomodulatory activity remains unknown.
This study examined in vitro immunomodulatory activities of peptides from in vitro- and in vivo-digested human milk.
Peptides were extracted from in vitro-digested human milk and pooled intestinal samples from 8 infants fed human milk. Peptides extracted from in vitro-digested samples were fractionated. The in vitro effects of these peptides and fractions on the secretion of TNF-α and IL-8 in LPS-treated human immune THP-1 macrophages were evaluated. The significance of differences between in vitro peptide fraction treatment and control on cytokine production was analyzed by t test. LC-MS/MS-based peptidomics was conducted to identify the peptides. The peptides were screened for potential bioactivity using a sequence homology search using the Milk Bioactive Peptide Database (MBPDB).
Six fractions of the peptide mixture extracted from the in vitro-digested human milk significantly inhibited TNF-α production by LPS-challenged THP-1 macrophages. Fractions F4, F8, F11, F14, and F17 attenuated IL-8 secretion, and F6/7 and F18 increased IL-8 secretion. Peptides extracted from the pooled in vivo intestinal samples attenuated both TNF-α and IL-8 secretion. There were 266 and 418 peptides identified in the in vitro and in vivo samples, respectively. Among the peptides, 34 and 50 in the in vitro and in vivo samples, respectively, had >80% sequence similarity to bioactive peptides in the MBPDB.
Peptides released by in vitro and in vivo infant digestion of human milk were immunomodulatory in human immune cells; fractions F4, F8, and F11 were anti-inflammatory; and F6/7 and F18 were proinflammatory. Thirteen peptides were present in all fractions with anti-inflammatory activity, and 38 peptides were present in all fractions with proinflammatory activity. These peptides potentially contributed to the observed immunomodulatory activity of the peptide mixtures.
牛奶蛋白含有许多加密的生物活性肽。这些生物活性肽是否在婴儿肠道中释放并发挥免疫调节活性尚不清楚。
本研究检测了体外和体内消化的人乳肽的体外免疫调节活性。
从体外消化的人乳中提取肽，并从 8 名母乳喂养的婴儿的肠道样本中提取肽。从体外消化的样本中提取的肽被分离。评估这些肽和肽段对脂多糖处理的人免疫 THP-1 巨噬细胞中 TNF-α和 IL-8 分泌的体外作用。通过 t 检验分析体外肽段处理与对照之间细胞因子产生差异的显著性。采用基于 LC-MS/MS 的肽组学方法鉴定肽。使用牛奶生物活性肽数据库（MBPDB）对序列同源性搜索筛选潜在的生物活性肽。
从体外消化的人乳中提取的肽混合物的 6 个馏分显著抑制了 LPS 刺激的 THP-1 巨噬细胞中 TNF-α的产生。F4、F8、F11、F14 和 F17 减轻了 IL-8 的分泌，而 F6/7 和 F18 增加了 IL-8 的分泌。从汇集的体内肠道样本中提取的肽减轻了 TNF-α和 IL-8 的分泌。在体外和体内样本中分别鉴定出 266 种和 418 种肽。在这些肽中，体外和体内样本中分别有 34 种和 50 种肽与人乳生物活性肽数据库中的生物活性肽具有>80%的序列相似性。
体外和体内婴儿消化人乳释放的肽在人免疫细胞中具有免疫调节作用；F4、F8 和 F11 是抗炎的；F6/7 和 F18 是促炎的。13 种肽存在于所有具有抗炎活性的馏分中，38 种肽存在于所有具有促炎活性的馏分中。这些肽可能对观察到的肽混合物的免疫调节活性有贡献。
