Modulation of the Systemic Immune Response in Suckling Rats by Breast Milk TGF-β2, EGF and FGF21 Supplementation

Abstract

Breast milk is a rich fluid containing bioactive compounds such as specific growth factors (GF) that contribute to maturation of the immune system in early life. The aim of this study was to determine whether transforming growth factor-β2 (TGF-β2), epidermal growth factor (EGF) and fibroblast growth factor 21 (FGF21), compounds present in breast milk, could promote systemic immune maturation. For this purpose, newborn Wistar rats were daily supplemented with these GF by oral gavage during the suckling period (21 days of life). At day 14 and 21 of life, plasma for immunoglobulin (Ig) quantification was obtained and spleen lymphocytes were isolated, immunophenotyped and cultured to evaluate their ability to proliferate and release cytokines. The main result was obtained at day 14, when supplementation with EGF increased B cell proportion to reach levels observed at day 21. At the end of the suckling period, all GF increased the plasma levels of IgG1 and IgG2a isotypes, FGF21 balanced the Th1/Th2 cytokine response and both EGF and FGF21 modified splenic lymphocyte composition. These results suggested that the studied milk bioactive factors, mainly EGF and FGF21, may have modulatory roles in the systemic immune responses in early life, although their physiological roles remain to be established.

Maternal Microbiota, Early Life Colonization and Breast Milk Drive Immune Development in the Newborn

“…It lowered NK cell frequency in the MLNs and altered the cytokine profile in the neonate ( 206 ). The same group showed that oral administration of TGF-β during this period of life further modified the splenic lymphocyte composition, suggesting effects on systemic immunity ( 207 ). Furthermore, breast milk levels of TGF-β negatively correlated with the occurrence of eczema in neonates ( 208 ).…”

The Research Progress in Transforming Growth Factor-β2

“…In addition, the presence of TGF-β2 in breast milk is thought to be associated with the maturation of the immune system after birth. Dietary supplementation with TGF-β2 at 35 µg/kg/day can increase IgG1 and IgG2a production and decrease the ratio of Th1/Th2, indicating that TGF-β2 is involved in promoting the maturation of immune development [98]. Breast milk TGF-β2 levels were also negatively correlated with plasma viral load levels [99].…”

“…Mouse chondrocytes and human osteoarthritic cartilage (5/10/25 ng/mL TGF-β2) [60,[88][89][90] Inhibit skeletal muscle satellite cell differentiation and proliferation and promote apoptosis Chicken skeletal muscle satellite cells (Inhibition of TGF-β2 by miR-200a-3p) [91] Downregulate bone formation Human dental follicle stem cells (1 µg/mL TGF-β2 inhibitor) [92] Upregulate gene expression of collagens, extracellular matrix molecules, and growth factors associated with tendon healing Mouse tendon-derived stem cells and equine bone marrow-derived mesenchymal stem cells (1 ng/mL TGF-β2) [93,94] Immune system Affect immune cell proliferation and apoptosis MCF-7 cells, RAW 264.7 cells, lamprey supraneural myeloid body cells, and peripheral blood leukocytes (0.01/0.1/1/10 ng/mL TGF-β2) [95] Maintain brain immune homeostasis by regulating the chemokine receptor-modulated immune response in microglia Mouse NG2 glial cells (5 ng/mL or 10 ng/mL TGF-β2) [96] Redirect inflammatory monocyte-derived cells in central nervous system autoimmunity Neural precursor cells from Tgfb2tm1Doe mice (Tgfb2 −/− ) and bone marrow-derived dendritic cells (0.01/1/10/100 ng/mL TGF-β2) [97] Promote the maturation of immune development G15 pregnant Wistar rats (TGF-β2 at 35 µg/kg/day) [98] Have an impact on antiviral immunity HIV breast feeding women [99] Tumor Sustain acidic tumor microenvironmentinduced lung cancer metastasis Human lung cancer cells (5 µg/mL of anti-TGF-β2 antibody) [53] Inhibit growth of hepatocellular carcinoma cells Human hepatocellular carcinoma cells (1 ng/mL or 5 ng/mL TGF-β2) [67] Support acidosis-driven EMT and the metastatic spreading of cancer cells Human cervix SiHa, pharynx FaDu, colorectal HCT-116, and HT-29 cancer cell lines (10 µM TGFβ2-specific antisense oligonucleotide) [100] Decrease dendritic cells migratory potential and activation and the anticancer immune response Mouse bone marrow-derived dendritic cells (5 µM TGF-β receptor inhibitor) [101] Mediate the effects of TRAP-dependent proliferation and migration in breast cancer cells MDA-MB-231 breast cancer cell line (0.25 µg/mL TGF-β2 neutralising antibody) [102] Block pancreatic cancer repopulation and metastasis Human pancreatic cancer cell lines (Inhibition of TGF-β2 by miR-193a) [103] NA, not available.…”

Rat Milk and Plasma Immunological Profile throughout Lactation

“…Leptin, in addition to its well-described metabolic function, also plays a more proinflammatory role in the regulation of the innate and adaptive IS [ 30 , 31 , 32 , 33 ], inhibiting Treg cells’ proliferation and activity [ 29 , 32 ]. With regard to FGF21, little is known about its function on the IS; there are few preclinical studies performed in suckling rats which show the potential role of FGF21 in promoting the maturation of the intestinal and systemic IS [ 34 , 35 ]. During lactation, although leptin and adiponectin are primarily transferred from the mother’s blood to the milk, they can also be synthesized by the mammary glands [ 26 , 36 , 37 ].…”

“…It was reported that milk EGF plays an important role in infant bowel development and in the prevention of necrotizing enterocolitis, especially in the first days of life [ 41 ]. There is not as much research evaluating the effects of EGF on the neonatal immune response [ 34 , 35 , 42 ]. With regard to human milk TGF-β, it has different functions in the infant’s gut, such as maintaining immune homeostasis, regulating inflammation (anti-inflammatory effect), promoting IgA production or participating in oral tolerance, and even influencing the composition of gut microbiota [ 43 , 44 , 45 ].…”