Recent Research Projects

Recent Publications

Immune Functions in Avian Reproductive Organs

Immunodefense systems in the reproductive and digestive organs play essential roles in maintaining the health, productive efficiency, and hygiene egg and meet production. The goal of our research is to enhance the reproductive functions and immunodefense functions in chickens.

Project 1 (Innate immune system in reproductive organs in chickens)

We investigate the innate immune functions and its endocrine control in chicken reproductive organs. We have identified expression of Toll-like receptors and avian ß-defensins (AvBDs) in the male and female reproductive organs. Toll-like receptors recognize pathogen associated molecular patterns. AvBDs are the member of antimicrobial peptides that kill a wide spectrum of microorganisms. We showed novel findings that antimicrobial peptides and cytokines are expressed, and their expression was upregulated in response to bacterial components in the ovary and oviduct. Then, we have shown that proinflammatory cytokines also upregulate the expression of AvBDs. In the other study, we identified the expression of mucin and tight junction molecules, namely claudins, forming mucosal barrier in the oviduct. The expression of mucin was upregulated by bacterial components. The expressions of antimicrobial peptides, cytokines and mucosal barrier molecules are changed in the regressed oviduct during molting, probably due to decline of gonadal steroid levels. The intracellular mechanism by which the expressions of AvBDs and cytokines are regulated is now under investigation.


   


Project 2 (Mechanism of sperm storage in hen oviduct)

 It is unique that sperm can survive for a few weeks in the sperm storage tubules (SST) of the oviduct. The sperm storage function affects the fertility. We investigate the mechanism by which sperm survive in the SST. Specifically, we are looking at how the SST cells provide sperm with survival factors and suppress anti-sperm immunoreactions. One of the factors to suppress the anti-sperm immunoreaction may be transforming growth factor-ß synthesized in the SST.  



Project 3 (Effects of probiotics on the immune system in digestive tract of chickens)

 We investigate the mucosal immune functions mediated by antimicrobial peptides and possible effects of probiotics to enhance that immunity in the gastro-intestinal mucosa of chicks. We have shown that probiotics induced T cells in the intestinal mucosa. Currently we are looking at the effects of probiotics on the expression of avian ß-defensins in the gut mucosa of chicks.  



Role of innate immune components in mastitis

 Mastitis is a critical problem in the dairy industry. However, its treatment and prevention methods have not been established. Mammary gland has a local immune system consisting established and innate immunity. Mammary epithelial cells can detect bacterial components using toll-like receptors on the cell surface. Then epithelial cells produce and secrete innate immune factors such as beta-defensin and lactoferrin and lactoperoxidase into the milk. ß-defensin and lactoferrin attack bacteria directly and kill it. ß-defensin family consists several components containing lingual antimicrobial peptide (LAP). Lactoferrin absorb iron ion, resulting in the shortage of iron ion in the surrounding circumstances. As bacteria need iron ion for its proliferation, lactoferrin has a role in bacteriostatic function. Cathelicidin, one of antimicrobial peptides, is secreted by leukocytes. Mastitis recruits a number of leukocytes in mammary gland. Therefore, cathelicidin may be contained in milk and have important role on preventing mastitis. However, there is limited information about function of these innate immune factor and antimicrobial peptides in the Mammary gland.

Research Theme
  • Changes of immune factors concentration in milk during estrous cycle relating to the prevalence of the mastitis.
  • Role of lingual antimicrobial peptide (LAP) and cathelicidin in the mastitis.
 


Previous Research

Function of ghrelin in the hen oviduct
Ghrelin, a novel acylated peptide, is the endogenous ligand for growth hormone secretagogue (GHS) receptor. Ghrelin is produced mainly in the oxyntic glands of the stomach, but also produced in the intestines, kidneys, hypothalamus and pituitary gland. Ghrelin may play an important role in controlling feeding behavor and energy homeostasis. The weight of the growing hen increase with oviduct development, suggesting the presence of some metabolism control factor in oviduct.

Research Theme

Endocrine Disrupters in Avian Reproduction
Chemicals in feed and environment may cause serious problems in thereproduction, immune functions and growth of poultry and wild birds. Our research suggested that DES administration inhibit epididymis development. Fagocytosis of inferior spermatozoa as well as capacitation are occured in the epididymis. These function may be also affected by endocrine disrupters.

Follicular Growth and Atresia in Hen Ovary
Follicular growth and atresia are closely related to egg production. We are looking at the significance of oocyte and hormones in granulosa cell proliferation and atresia, and also significance of apoptosis in atresia.

Effects of Induced Molting on Reproductive Organs
Induced molting improves egg production. We are looking at how the tissue remodeling occurs in the oviduct and pituitary, specifically induction of apoptosis and cell proliferation is focused.

Presence of Sex Steroid Receptors in Hen Ovary
Ovarian functions are controlled by gonadotropins, whereas sex steroids may also play significant roles as local regulators in the ovary. We have identified the receptors for progesterone, androgen and estrogen, suggesting that the ovarian tissues are the target sites for sex steroids.

Measurement of steroid hormone in the plasma and feces of animals.
To examine reproductive aspects of animals, plasma steroid hormone concentration is usually measured. More simple and practical method of measurement is strongly required. Blood collection is difficult in the case of grazing, nervous cows and wild animals. Therefore, if fecal steroid hormone can be utilized, this technique is very convenient. Therefore, I tried to establish method to measure steroid hormone (progesterone, 20OH-pregnan, estrone sulfate, estradiol-17beta, testosterone, cortisol, corticosterone) in cattle, pig, goat, chicken, giraffe, rhinoceros.

Cystic ovarian disease in dairy cows
Cystic ovarian disease disturbs the reproductive performance of dairy cows mainly postpartum. We are investigating the mechanisms in the cystic follicle formation in order to suppress and treat it.

Research Theme