Augmentation of natural killer cell activity in mice by oral administration of transforming growth factor-beta

Exogenous transforming growth factor beta1 replacement and fertility in male Tgfb1 null mutant mice

Analysis of Tgfb1 null mutant mice has demonstrated that the cytokine transforming growth factor β1 (TGFB1) has essential non-redundant roles in fertility. The present study attempted to alleviate the infertility phenotype of Tgfb1 null mutant male mice by administration of exogenous TGFB1, either orally by colostrum feeding or subcutaneously by delivery of recombinant human latent TGFB1 (rhLTGFB1) via osmotic mini-pumps. Bovine colostrum and fresh unpasteurised bovine milk were found to be rich sources of TGFB1 and TGFB2; however, feeding Tgfb1 null mutant mice colostrum for 2 days failed to raise serum levels of TGFB1. Administration of rhLTGFB1 (~150 μg in total) over 14 days to Tgfb1 null mutant mice resulted in detectable TGFB1 in serum; however, mean levels remained 10-fold less than in Tgfb1 heterozygous mice. After 7 days and 14 days of rhLTGFB1 administration, serum testosterone, spontaneous non-contact erections and mating behaviour were assessed. Despite the increased serum TGFB1, administration of rhLTGFB1 to Tgfb1 null mutant mice failed to improve these fertility parameters. It is concluded that sustained restoration of circulating latent TGFB1 to levels approaching the normal physiological range does not rescue the infertility phenotype caused by TGFB1 deficiency. Reproductive function in male Tgfb1 null mutant mice may not respond to systemic TGFB1 supplementation due to a requirement for local sources of TGFB1 at the site of action in the reproductive tract, or perturbed development during the neonatal period or puberty such that adult reproductive function is permanently impaired.

Evidence for the immunostimulatory effects of low-dose orally delivered human IFN-alpha in cattle

Orally delivered interferon-alpha (IFN-alpha) has been associated with systemic protection against various disorders in humans and animals. In an attempt to understand how IFN-alpha delivers a systemic signal following its local oral administration, the present study aimed at identifying genes differentially regulated in bovine peripheral blood through the use of cDNA microarrays following oral therapy with IFN-alpha. We identified thousands of genes to be IFN-alpha regulated. Of these, about 8.5% had a minimum 4-fold degree of change, the majority of which represented novel IFN-stimulated genes (ISG). Several upregulated ISGs were transcripts with key and diverse biologic functions, including antigen processing and presentation, leukocyte migration, lymphocyte activation, immune effector and modulation functions, apoptosis, and hematopoiesis. Interestingly, IFN-alpha expression itself was not modulated in bovine peripheral blood, suggesting that the blood levels of IFN-alpha are not the hallmark of the immunostimulatory effects of oral IFN-alpha therapy. Rather, IFN-alpha seems to interact with local mucosal lymphoid cells in the gastrointestinal tract. This interaction may initiate a signaling cascade eventually leading to the transcriptional induction of ISGs, which in turn encode immunostimulatoiry proteins. Thus, ISGs, through the proteins they encode, may potentially perform critical immune modulation functions.

Effects of exogenous transforming growth factor beta on Trypanosoma congolense infection in mice

The socioeconomic implications of trypanosomosis in sub-Saharan Africa and the limitations of its current control regimes have stimulated research into alternative control methods. Considering the pro- and anti-inflammatory properties of transforming growth factor beta1 (TGF-beta1) and its potential to enhance immunity against protozoan parasites, we examined the effects of intraperitoneally delivered TGF-beta1 in C57BL/6 mice infected with Trypanosoma congolense, the hemoprotozoan parasite causing nagana in cattle. A triple dose of 10 ng TGF-beta1 significantly reduced the first parasitemic peak and delayed mortality of infected mice. Furthermore, exogenous TGF-beta1 significantly decreased the development of trypanosome-induced anemia and splenomegaly. The apparent TGF-beta1-induced antitrypanosome protection, occurring mainly during the early stage of infection, correlated with an enhanced parasite antigen-specific Th1 cell response characterized by a skewed type I cytokine response and a concomitant stronger antitrypanosome immunoglobulin G2a antibody response. Infected TGF-beta1-pretreated mice exhibited a significant reduction in the trypanosome-induced hyperexpansion of B cells. Furthermore, evidence is provided herein that exogenous TGF-beta1 activates macrophages that may contribute to parasite control. Collectively, these data indicate that exogenous TGF-beta1 is immunostimulative, inducing partial protection against T. congolense infection, possibly through mechanisms involving innate immune responses.

Interleukin-2 in human milk: a potential modulator of lymphocyte development in the breastfed infant

Development of lymphocyte subpopulations and response to antigen exposure will be influenced by the limited ability of neonates to produce cytokines. In the case of cytokines such as interleukin (IL)-2 which are potent T lymphocyte regulators but poorly produced by newborn infants, the supply of cytokines through human milk could alleviate an immunological deficit and potentially aid the maturation of the immune system. We analysed human milk from 52 mothers (15-357 days postpartum) by ELISA to determine levels of aqueous IL-2, as well as production by human milk cells. IL-2 was detectable (>8 pg/mL) in the aqueous phase of 81% of all day 1 samples with no significant difference found in the mean concentration over 3 consecutive days. IL-2 was produced constitutively at detectable levels by 57% of milk cell samples and production was significantly increased by stimulation with Con A (380%). No correlation was found between aqueous and cellular IL-2, however there was a significant correlation between milk aqueous IL-2 and serum IL-2. This is the first report of IL-2 in the aqueous phase of human milk. A supply of exogenous IL-2 in human milk may provide the suckling infant with important immunological signals during a significant stage of T cell development.

Wnt-10b secreted from lymphocytes promotes differentiation of skin epithelial cells

Wnt-10b was originally isolated from lymphoid tissue and is known to be involved in a wide range of biological actions, while recently it was found to be expressed early in the development of hair follicles. However, few studies have been conducted concerning the role of Wnt-10b with the differentiation of skin epithelial cells. To evaluate its role in epithelial differentiation, we purified Wnt-10b from the supernatant of a concanavalin A-stimulated lymphocyte culture using an affinity column and investigated its effects on the differentiation of adult mouse-derived primary skin epithelial cells (MPSEC). MPSEC cultured with Wnt-10b showed morphological changes from cuboidal to spindle-shaped with inhibited proliferation, and also obtained characteristics of the hair shaft and inner root sheath of the hair follicle, represented by red-colored Ayoub Shklar staining, and reactions to AE-13 and AE-15 as seen with immunocytology. Further, RT-PCR analysis demonstrated the expression of mRNA for keratin 1, keratin 2, loricrin, mHa5, and mHb5, in association with a decreased expression of the basal cell marker keratin 5, in Wnt-10b-treated MPSEC. In addition, involvement of the canonical Wnt signal pathway was demonstrated by a TCF reporter (pTOPFLASH) assay. These results suggest that Wnt-10b promotes the differentiation of MPSEC and may play an important role in hair follicle development by promoting differentiation of epithelial cells.

Interleukin-18 in human milk

We analyzed IL-18 levels of human milk. Colostrum contained significantly higher levels of IL-18 compared with early milk and mature milk. By stepwise multiple linear regression analysis, preterm delivery and pregnancy complications of mothers significantly correlated with high levels of IL-18 in human milk (p = 0.0007 and 0.0018, respectively). There was a significant correlation between the levels of IL-18 and soluble Fas ligand in colostrum (p = 0.0003). IL-18 was detected in actively secreting epithelial cells in lactating mammary gland by immunohistochemical staining. These results suggest that IL-18 in colostrum plays an important role in host defense of high-risk neonates.

Apelin, the natural ligand of the orphan receptor APJ, is abundantly secreted in the colostrum

By using a strategy that we have developed to search for the ligands of orphan seven-transmembrane-domain receptors [S. Hinuma et al., Nature 393 (1998) 272-276], we have recently identified a natural ligand, apelin, for the orphan 7TMR, APJ [K. Tatemoto et al., Biochem. Biophys. Res. Commun. 251 (1998) 471-476]. In this paper, we isolated rat and mouse apelin cDNAs, and analyzed the tissue distribution of apelin mRNA in rats. Although apelin mRNA was widely detected in a variety of tissues, the highest expression of apelin mRNA was detected in the mammary gland of pregnant rats. In the mammary gland, biologically active apelin and its mRNA considerably increased during pregnancy and lactation, and reached a maximal level around parturition. Moreover, a large amount of apelin (14-93 pmol/ml) was found to be secreted in the bovine colostrum, and it was still detectable even in commercial bovine milk. Since apelin partially suppressed cytokine production by mouse spleen cells in response to T cell receptor/CD3 cross-linking, the oral intake of apelin in the colostrum and milk might modulate immune responses in neonates.