Evaluating protective effects of botanicals under inflammation and oxidative stress in chicken apical-out enteroids

Botanicals (BOTs) are well known for their anti-inflammatory and antioxidant activities. They have been widely used as feed additives to reduce inflammation and improve intestinal functions in agricultural animals. However, the effects of BOTs on chicken intestinal epithelial functions are not fully understood. The 3D apical-out chicken enteroids recapitulate the intestinal tissue, and allow convenient access to the luminal surface, thus serving as a suitable model for investigating gut functions. The aim of this study was to identify the roles of BOTs in protecting the intestinal epithelium in chicken enteroids under challenging conditions. Apical-out enteroids were isolated from the small intestines of 18 days-old chicken embryos. Lipopolysaccharide (LPS, 10 µg/mL) and menadione (400 µM) challenges were performed in the media with or without BOTs. Paracellular Fluorescein isothiocyanate-dextran 4kD (FD4) permeability, inflammatory cytokine gene expression, and reactive oxygen species (ROS) generation were analyzed post-BOTs and challenges treatments. Statistical analysis was performed using one-way ANOVA and post hoc multiple comparisons among treatments. The results showed that the LPS challenge for 24 h induced a 50% increase in FD4 permeability compared with nontreated control; thymol, thyme essential oil, and phenol-rich extract significantly (P < 0.02) reduced FD4 permeability by 25%, 41%, and 48% respectively, in comparison with LPS treatment. Moreover, the gene expression of inflammatory cytokines was upregulated, tight junction proteins and defensins were downregulated (P < 0.05) after 6 h of LPS treatment, while these BOTs treatments significantly restored the LPS-induced gene expression alterations (P < 0.05). Menadione oxidative challenge for 1 h significantly increased the ROS level compared with unchallenged control. Enteroids treated with thymol and thyme essential oils showed 30% reduced ROS levels, while the phenol-rich extract reduced them by 60%, in comparison with the challenged group (P < 0.0001). These data confirmed the role of BOTs in supporting the barrier function and reducing the disruptive effects of inflammation and oxidation in the chicken intestine.

Through the Looking Glass: Genome, Phenome, and Interactome of Salmonella enterica

This review revisits previous concepts on biological phenomenon contributing to the success of the Salmonella enterica subspecies I as a pathogen and expands upon them to include progress in epidemiology based on whole genome sequencing (WGS). Discussion goes beyond epidemiological uses of WGS to consider how phenotype, which is the biological character of an organism, can be correlated with its genotype to develop a knowledge of the interactome. Deciphering genome interactions with proteins, the impact of metabolic flux, epigenetic modifications, and other complex biochemical processes will lead to new therapeutics, control measures, environmental remediations, and improved design of vaccines.

Effects of LPS on the Secretion of Gonadotrophin Hormones and Expression of Genes in the Hypothalamus-Pituitary-Ovary (HPG) Axis in Laying Yangzhou Geese

Simple Summary

Lipopolysaccharide (LPS), an endotoxin from E. coli, has been proven to impair follicle development and steroidogenesis, secretion of pituitary and hypothalamus reproductive hormones in mammals. However, the effects of LPS on the avian reproductive axis remain elusive. Pathogenic bacterial infection due to the particular mating behavior on the water containing pathogens was reported to decrease the laying rate and cause economic loss in goose production. In this study, we showed that LPS infection disturbed the plasma pituitary gonadotrophin hormone concentrations and the gene expression of the reproductive axis in Yangzhou geese. Notably, for the first time we proved that both the expression of gonadotrophin-releasing hormone (GnRH) and gonadotropin-inhibiting hormone (GnIH), two important reproductive genes from the hypothalamus, were altered after LPS treatment in birds. Our results can explain the decreased laying rate in goose after bacterial infection, and also provide new insights into reproductive dysfunction caused by LPS and the immune challenge in birds.

Abstract

Lipopolysaccharide (LPS) from gram-negative bacteria was found to be involved in the decrease in laying performance in goose flocks with high stocking density during summer months. LPS injection delayed the increase in the laying rate and altered hierarchical follicle morphology. While there is evidence that LPS exerts suppressive effects on goose reproduction, the time course effects of LPS on the hypothalamus-pituitary-ovary (HPG) axis remain elusive. In this study, we investigated the expression of genes in the HPG axis and the plasma gonadotrophin hormone concentrations in breeding geese at 0, 6, 12, 24, and 36 h after intravenous injection with LPS. The results showed that LPS treatment enhanced and suppressed expression of hypothalamic gonadotropin-inhibiting hormone (GnIH) and gonadotrophin-releasing hormone (GnRH) mRNA, respectively, and similar effects were observed on the mRNA expression of their receptors, GnIHR and GnRHR, in the pituitary. LPS treatment transiently increased follicle FSHβ mRNA expression at 12 h and exerted no significant effect on LHβ mRNA expression in the pituitary. Regardless of the expression of FSHβ and LHβ, plasma follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations were significantly increased during 24–36 h after LPS treatment. In the ovary, StAR and Cyp11a1 were mainly expressed in the granulosa layer (GL) of hierarchical follicles, while Cyp17a1 and Cyp19a1 were mainly expressed in white follicles (WFs) and yellowish follicles (YFs), and to a lesser extent in the theca layer (TL). After LPS treatment, the mRNA levels of Cyp11a1 in the GLs, Cyp17a1 in the WFs and TL, and Cyp19a1 in the WFs, YFs, and TL were significantly decreased. However, LPS treatment transiently upregulated StAR expression at 12 h. These results indicate that the exposure of laying geese to LPS may impair the HPG axis and disturb ovarian steroidogenesis. Our research provides new insights into reproductive dysfunction caused by LPS and the immune challenge in birds.

Peptidoglycan derived from Lactobacillus rhamnosus MLGA up-regulates the expression of chicken -defensin 9 without triggering an inflammatory response

Defensins are critical components of the innate immune system and play an important role in the integration of innate and adaptive immune responses. Although information on the immunomodulatory properties of peptidoglycan from bacteria is abundant, little is known about the β-defensin induction effect of peptidoglycan from the probiotic Lactobacillus. This study investigated the effect of intact peptidoglycan from L. rhamnosus MLGA on the induction of avian β-defensin 9 in chicken immune cells and intestinal explants. Peptidoglycan from Lactobacillus rhamnosus MLGA dose dependently promoted avian β-defensin 9 mRNA expression in chicken PBMCs, splenocytes, thymocytes, hepatocytes, and chicken embryo jejunum, ileum, and cecum explants and increased the capacity of PBMC or splenocyte lysates to inhibit the growth of Salmonella Enteritidis. In contrast to the effect of L. rhamnosus MLGA-derived peptidoglycan, peptidoglycan derived from pathogenic Staphylococcus aureus reduced avian β-defensin 9 mRNA expression in chicken PBMCs and splenocytes. The inducible effect of peptidoglycan from L. rhamnosus MLGA on avian β-defensin 9 expression in PBMCs and splenocytes was observed without activation of the expression of associated pro-inflammatory cytokines IL-1β, IL-8, and IL-12p40, whereas these cytokine expressions were suppressed by peptidoglycan hydrolysate obtained by lysozyme digestion. The results of the present study show the capability of peptidoglycan derived from L. rhamnosus MLGA to induce the antimicrobial peptide defensin while simultaneously avoiding the deleterious risks of an inflammatory response.

Effects of Toll-like Receptor Ligands on the Expression of Proinflammatory Cytokines and Avian β-defensins in Cultured Chick Intestine

Few studies have focused on the regulation of cytokine and avian β-defensin (AvBDs) expression for promoting immune defense in the avian intestine. The aim of this study was to investigate the effects of different Toll-like receptor (TLR) ligands (bacterial patterns) on the expression of proinflammatory cytokines (IL-1β and IL-6) and AvBDs (AvBD1, AvBD4, and AvBD7) in the chick intestine. The ileum and cecum of 3-day-old chicks were collected and examined histologically to identity the cells present in the intestinal mucosa. Other tissues were cultured with or without the TLR2, TLR4, and TLR21 ligands—Pam3CSK4, LPS, and CpG-ODN—for 1 or 3 h. The gene expression profiles of proinflammatory cytokines and AvBDs were determined in these tissues using real-time polymerase chain reaction (PCR). The mucosa of the ileum and cecum contained leukocytes, luminal and crypt epithelial cells, and other enterocytes. Pam3CSK4 tended to downregulate the expression of IL-1β, AvBD1, and AvBD7 in the ileum but upregulated their expression in the cecum. LPS downregulated the expression of IL-1β and IL-6 in both the ileum and the cecum, whereas it upregulated the expression of AvBD1, AvBD4, and AvBD7 in the cecum. CpG-ODN upregulated the expression of IL-6 and AvBD7 in the ileum and IL-1β in the cecum, and downregulated the expression of IL-1β and AvBDs in the ileum. We suggested that the expression levels of proinflammatory cytokines and AvBDs in the chick intestine are affected by TLR2, TLR4, and TLR21 ligands. Thus, these innate immune factors may be modulated by the luminal microbe complex in the intestine.

Beta defensin 3 enhances ovarian granulosa cell proliferation and migration via ERK1/2 pathway in vitro†

Antimicrobial peptides (AMPs) are regarded as host defense peptides that possess bactericidal activity as well as immunomodulatory function. However, the role of AMP in the mammalian ovary is unknown. In the present study, porcine granulosa cells were utilized in a cell model to study the role of porcine beta defensin 2 (pBD2; pDEFB4B) and 3 (pBD3; pDEFB103A) during ovarian follicular development. Granulosa cells were cultured in the absence and presence of 1, 10, and 50 μg/ml of pDEFB4B or pDEFB103A. After 24 h of treatment, pDEFB103A but not pDEFB4B stimulated granulosa cell proliferation in a concentration-dependent manner (P < 0.05). This effect was dependent on the stage of follicular development. In addition, transwell cell migration assay showed that in the presence of pDEFB103A (10 μg/ml), a 2.5-fold increase in cell migration was achieved. Furthermore, further study revealed that pDEFB103A increased the mRNA levels of cyclin D1 (CCND1) and proliferating cell nuclear antigen (PCNA), both associated with cell proliferation. To study the potential pathway involved in pDEFB103A-induced cell proliferation and migration, western blots were performed. It was found that pDEFB103A significantly increased the phosphorylated-ERK1/2 to nonphosphorylated ratio. Moreover, pretreatment with the U0126, a specific ERK1/2 phosphorylation inhibitor, suppressed PDEFB103A inducing GCs ERK1/2 phosphorylation, as well as proliferation and migration, suggesting that PDEFB103A may act via activating the ERK1/2 pathway. Furthermore, using a signal transduction pathway Elk-1 trans-reporting system, the activation of ERK1/2 pathway by PDEFB103A was further confirmed. Our data suggest that AMP may play a physiological role in the mammalian ovary.

Effects of Probiotics Lactobacillus reuteri and Clostridium butyricum on the Expression of Toll-like Receptors, Pro- and Anti-inflammatory Cytokines, and Antimicrobial Peptides in Broiler Chick Intestine

The aim of this study was to determine the effects of live probiotics Lactobacillus reuteri (LR) and Clostridium butyricum (CB) on the expression of genes of innate immune system in broiler chick ileum and cecum. Chicks were administered 500 µl water with or without LR or CB, daily from day 1 to 6 after hatching. The ileum and cecum were collected on day 7 for analysis of gene expression of Toll-like receptors (TLRs), pro- and anti-inflammatory cytokines, and antimicrobial peptides (AMPs) using real-time PCR. The expression of TLR2-1 was upregulated by CB in the ileum and that of TLR5 was upregulated by both LR and CB. Expression of IL-1β and TGFβ2 in the ileum and of TGFβ3 and TGFβ4 in the cecum was upregulated by both LR and CB. The gene expressions of avian β-defensin (AvBD) 1 and cathelicidin (CATH) 3 were upregulated by CB and that of AvBD4 was upregulated by LR in the cecum. However, the expression of CATH2 in the ileum was downregulated by LR. These results suggest that probiotic LR and CB treatments affect a part of the innate defense system in the ileum and cecum by modulating the expression of innate immune molecules including TLRs, pro- and anti-inflammatory cytokines, and AMPs.

Effects of the routine multiple vaccinations on the expression of innate immune molecules and induction of histone modification in ovarian cells of layer chicks

The aim of this study was to determine whether vaccination affects the expression of Toll-like receptors (TLRs), cytokines, and avian β-defensins (AvBDs) in the chick ovary with or without lipopolysaccharide (LPS) stimulation. White Leghorn female chicks were administered vaccines for infectious bronchitis, Marek's disease, Newcastle disease, and infectious bursal disease during the first 14 D after hatching and ovarian tissues were collected on day 21. Control chicks received water or dilution buffer in place of vaccine. In Experiment 1, ovarian tissues were incubated with or without LPS, and the expression of innate immune molecules (TLRs, cytokines, and AvBDs) was examined by real-time PCR. In Experiment 2, the levels of histone modification in fresh ovarian tissues were examined by western blot analysis. The results of Experiment 1 showed that, in vaccinated chick ovaries, the expression of TLR1-1, 2-1, 2-2, and 21 was up-regulated, whereas that of TLR1-2, 4, and 7 was down-regulated under LPS stimulation. Among the examined 6 cytokines, only the expression of TNFSF15 was lower in the ovaries of vaccinated chicks than that in control with or without LPS stimulation. The expression of AvBD1, 2, 4, and 7 was lower in the ovaries of vaccinated chicks than in control without LPS stimulation, and that of AvBD1 and 2 was also lower even in ovaries incubated with LPS. In Experiment 2, the density of di-methyl histone H3 (Lys9) and acetyl histone H3 (Lys9) was significantly higher in the vaccine group than in the control, whereas di-methyl and tri-methyl histone H3 (Lys4) and acetyl histone H3 (Lys27) did not show differences between the groups. These results suggest that vaccination positively or negatively affects the expression of innate immune molecules in the chick ovary including TLRs, TNFSF15, and AvBDs, and it may be associated with epigenetic reprogramming by histone modifications in ovarian cells. Thus, in the future, it may be possible to develop or improve vaccination programs for the enhancement of the innate immune system in the hen ovary.

Effects of Salmonella enteritidis Vaccination on the Expression of Innate Immune Molecules and Histone Modifications in the Follicular Theca of Laying Hens

The aim of this study was to examine whether Salmonella enteritidis (SE) vaccination affects innate immune function and histone modifications responsible for epigenetic reprogramming in the follicular theca of laying hens. White Leghorn laying hens were administered the SE vaccine or phosphate buffered saline (PBS; control) one week before sample collection. The largest follicles (F1) were collected for total RNA and histone protein extraction. Gene expression levels of immune molecules (Toll-like receptors [TLRs], cytokines, and avian β-defensins [AvBDs]), and histone modifications in the follicular thecal tissues, were examined using real-time PCR and western blot, respectively. The results showed that the expression levels of TLR1-1, 2-1, 4, and 15 were upregulated by SE vaccination. Although vaccination caused no significant change in cytokine expression, AvBDl, 2, 4, and 7 expression levels were significantly upregulated in the vaccinated group. In addition, the relative density of histone H3-lysine9 dimethylation (H3K9me2) was increased by the vaccination. These results suggest that SE vaccination enhances innate immune functions in the ovary of laying hens, including upregulating TLR and AvBD expression, and is also associated with an increase in histone H3K9me2 in thecal cells.

Effects of TLR Ligands on the Expression of Cytokines and Possible Role of NFκB in its Process in the Theca of Chicken Follicles

The aim of this study was to determine the effects of Toll-like receptor (TLR) ligands on the expression of cytokines in chicken follicular theca and to investigate whether nuclear factor-κB (NFκB) was involved in their expression. The follicular theca was collected from the largest follicle of laying hens. In experiment 1, the expression of TLRs in the theca interna and externa was confirmed using RT-PCR. The theca tissues were then incubated with or without Pam3CSK4 (TLR2 ligand), poly I:C (TLR3 ligand), LPS (TLR4 ligand), flagellin (TLR5 ligand), R837 (TLR7 ligand), and CpG-ODN (TLR21 ligand) for 3 h, after which cytokine expression (IL-1β, IL-6, TNFSF15, CXCLi2, IFN-α, and IFN-β) was analyzed by real-time PCR. In experiment 2, the theca tissues were incubated in a medium containing Pam3CSK4, poly I:C, LPS, or CpG-ODN with or without BAY 11-7085 (an inhibitor of NFκB) for 3 h. The results of experiment 1 revealed that all TLRs, namely TLR1 (type 1 and 2), TLR2 (type 1 and 2), 3–5, 7, 15, and 21, were expressed in the follicular theca, although the PCR products of TLR1 (type 2) and TLR21 were faint. Moreover, Pam3CSK4 and LPS upregulated the expression of all detected cytokines, except for IFN-α, whose expression was not upregulated by LPS. Poly I:C upregulated the expression of IL-6, CXCLi2, and IFN-β, while CpG-ODN upregulated IL-1β. Flagellin and R837 did not significantly affect cytokine expression. In experiment 2, the expression of IL-1β, IL-6, CXCLi2 and IFN-β in tissues incubated with LPS was downregulated by BAY 11-7085. These results suggest that the innate immune system, including pattern recognition by TLRs and cytokine synthesis, occur in the theca; whereas, functions for recognition of bacterial patterns is more developed than that of viral ones.

Female Reproductive System and Immunology

Health of the reproductive organs is essential for formation and production of high quality and hygienic eggs. It is of importance to review the structures and functions of female reproductive system for better understanding of the mechanism by which the eggs are formed. The unique functions of ovarian cells for follicular growth and differentiation as well as steroidogenesis and oocyte maturation are regulated by gonadotropins and gonadal steroids. The oviduct is responsible for egg formation, while the unique function to store sperms for a prolonged period takes place in the specific tissue of this organ. The unique innate and adaptive immuno-defense systems that play essential role to prevent infection are developed in the ovary and oviduct. Toll-like receptors (TLRs) that recognize the molecular pattern of microbes and initiate the immunoresponse are expressed in those organs. Avian β-defensins (AvBDs), a member of antimicrobial peptides, are synthesized by the ovarian and oviductal cells. Challenge of those cells by TLR ligands upregulates the expression of proinflammatory cytokines, which in turn stimulate the expression of AvBDs. The adaptive immune system in the ovary and oviduct is also unique, since the migration of lymphocytes is enhanced by estrogens. In contrast to the development of immuno-defense system, spontaneous ovarian cancer and uterine fibroids appear more frequently in chickens than in mammals, and thus chickens could be used as a model for studying these diseases. Thus the avian reproductive organs have unique functions not only for egg formation but also for the immuno-defense system, which is essential for prevention of infection and production of hygienic eggs.

Cytokine activation during embryonic development and in hen ovary and vagina during reproductive age and Salmonella infection

Salmonellosis is one of the most important zoonotic diseases and is usually associated with consumption of Salmonella Enteritidis (SE) contaminated poultry meat or eggs. Contamination with SE is usually the result of infection of the digestive tract, or reproductive organs, especially the ovary and vagina. Thus, knowledge of endogenous innate immune mechanisms operating in the ovary and vagina of hen is an emerging aspect of reproductive physiology. Cytokines are key factors for triggering the immune response and inflammation in chicken to Salmonella infection. The aim of this study was to investigate the expression profile of 11 proinflammatory cytokines in the chicken embryos during embryonic development, as well as in the hen ovary and vagina in vivo, to investigate whether sexual maturation affects their ovarian and vaginal mRNA abundance and to determine whether cytokine expression was constitutive or induced in the ovary and vagina as a response to SE infection. RT-PCR analysis revealed that several cytokines were expressed in the chicken embryos, and in the ovary and vagina of healthy birds. Expression of various cytokines during sexual maturation appeared to be developmentally regulated. In addition, a significant up-regulation of several cytokines in the ovary and vagina of sexually mature SE infected birds compared to healthy birds of the same age was observed. These results suggest a cytokine-mediated immune response mechanism against Salmonella infection in the hen reproductive organs.

Transcriptional changes of cytokines in rooster testis and epididymis during sexual maturation stages and Salmonella infection

Infection of rooster testis and epididymis by pathogens can lead to impaired fertility, resulting in economic losses in the poultry industry. Antimicrobial protection of rooster reproductive organs is, therefore, an important aspect of reproductive physiology. Salmonellosis is one of the most important zoonotic diseases, caused by Salmonella bacteria including Salmonella Enteritidis (SE) and is usually the result of infection of the reproductive organs. Thus, knowledge of the endogenous innate immune mechanisms of the rooster testis and epididymis is an emerging aspect of reproductive physiology. Cytokines are key factors for stimulating the immune response and inflammation in chickens to Salmonella infection. In the present study the expression profile of 11 pro-inflammatory cytokine genes in the rooster testis and epididymis in vivo and transcriptional changes in these organs during sexual maturation and SE infection were investigated. Gene expression analysis data revealed that in both testis and epididymis nine cytokines namely the IL-1β, IL-6, IL-8, IL-10, IL-12, IL-15, IL-16, IL-17 and IL-18 genes were expressed, while no mRNA transcripts were detected in both organs for IL-2 and IL-4. Furthermore, the expression of various cytokine genes during sexual maturation appeared to be developmentally regulated, while SE infection resulted in a significant up-regulation of IL-1β, -6, -12 and -18 genes in the testis and an increase in the mRNA relative abundance of IL-1β, -6, -12, -16 and -18 in the epididymis of SE-infected sexually mature 28-week-old roosters. These results suggest a cytokine-mediated immune response mechanism against Salmonella infection in the rooster reproductive tract.

Characterization of host responses induced by Toll-like receptor ligands in chicken cecal tonsil cells

The innate responses of cecal tonsils against invading microorganisms are mediated by conserved pattern recognition receptors (PRRs) such as the Toll-like receptors (TLRs). TLRs expressed by mammalian and avian immune system cells have the capability to recognize pathogen-associated molecular patterns (PAMPs). Although, the role of TLR ligands in innate and adaptive responses in chickens has been characterized in spleen and bursa of Fabricius, considerably less is known about responses in cecal tonsils. The aim of the current study was to assess responses of mononuclear cells from cecal tonsils to treatment with the TLR2, TLR4 and TLR21 ligands, Pam3CSK4, lipopolysaccharide (LPS), and CpG oligodeoxynucleotide (ODN), respectively. All three ligands induced significant up-regulation of interferon (IFN)-γ, interleukin (IL)-1β, IL-6 and CxCLi2/IL-8, whereas no significant changes were observed in expression of IL-13 or the antimicrobial peptides, avian β-defensin (AvBD) 1, AvBD2 and cathelicidin 3 (CATHL-3). In general, CpG ODN elicited the highest cytokine responses by cecal tonsil mononuclear cells, inducing significantly higher expression compared to LPS and Pam3CSK4, for IFNγ, IL-1β, IL-6 and CxCLi2 at various time points. These findings suggest the potential use of TLR21 ligands as mucosal vaccine adjuvants, especially in the context of pathogens of the intestinal tract.

Effects of different TLR ligands on the expression of proinflammatory cytokines and avian β-defensins in the uterine and vaginal tissues of laying hens

The immune response in the lower part of the hen oviduct is of crucial importance to protect the oviductal tissues from infection by microorganisms colonizing the cloaca. The aim of this study was to examine whether different TLRs can recognize their ligands to induce expression of proinflammatory cytokines and avian β-defensins (AvBDs) in the uterus and vagina of laying hens. The mucosal tissues of the uterus and vagina were collected, cultured in TCM-199 medium and stimulated with or without different ligands of TLRs, namely Pam3CSK4 (TLR2), poly I:C (TLR3), flagellin (TLR5), R848 (TLR7), and CpG-ODN (TLR21) and incubated for 3h. The expression of IL1B in the uterus and vagina was upregulated by all TLR ligands tested. The expression of IL6 in the uterus and vagina was upregulated by poly I:C and CpG-ODN, and it was also upregulated by Pam3CSK4 in the uterus and by R848 in the vagina. The expression of AvBD10 was upregulated by poly I:C in the uterus and by flagellin in the vagina. On the other hand, the AvBD10 expression was downregulated by CpG-ODN in the uterus and by R848 in the vagina, whereas its expression was not affected by Pam3CSK4 in both tissues. The expression of AvBD12 in the uterus and vagina was not affected by any TLR ligands except for CpG-ODN, which downregulated its expression in the vagina. These results suggest that TLR2, 3, 5, 7, and 21 in the uterine and vaginal tissues are functionally active in inducing proinflammatory cytokines in response to their specific ligands, although the effect on the expression of AvBDs is limited. Proinflammatory cytokines induced by interaction of TLRs with their ligands may play roles in the defense against infectious microorganisms.

Avian host defense peptides

Host defense peptides (HDPs) are important effector molecules of the innate immune system of vertebrates. These antimicrobial peptides are also present in invertebrates, plants and fungi. HDPs display broad-spectrum antimicrobial activities and fulfill an important role in the first line of defense of many organisms. It is becoming increasingly clear that in the animal kingdom the functions of HDPs are not confined to direct antimicrobial actions. Research in mammals has indicated that HDPs have many immunomodulatory functions and are also involved in other physiological processes ranging from development to wound healing. During the past five years our knowledge about avian HDPs has increased considerably. This review addresses our current knowledge on the evolution, regulation and biological functions of HDPs of birds.

Induction of avian β-defensins by CpG oligodeoxynucleotides and proinflammatory cytokines in hen vaginal cells in vitro

Immune function in the vagina of hen oviduct is essential to prevent infection by microorganisms colonizing in the cloaca. The aim of this study was to determine whether CpG oligodeoxynucleotides (CpG-ODN) stimulate the expression of avian β-defensins (AvBDs) in hen vaginal cells. Specific questions were whether CpG-ODN affects the expression of AvBDs and proinflammatory cytokines and whether the cytokines affect AvBDs expression in vaginal cells. The dispersed vaginal cells of White Leghorn laying hens were cultured and stimulated by different doses of lipopolysaccharide (LPS), CpG-ODN, interleukin 1β (IL1B), or IL6. The cultured cell population contained epithelial cells, fibroblast-like cells, and CD45-positive leukocytes. The immunoreactive AvBD3, -10, and -12 were localized in the mucosal epithelium in the section of the vagina. The expression of AvBDs, IL1B, and IL6 was analyzed by quantitative RT-PCR. RT-PCR analysis showed the expression of AvBD1, -3, -4, -5, -10, and -12 in the cultured vaginal cells without stimulation. Toll-like receptors (TLRs) 4 and 21, which recognize LPS and CpG-ODN respectively and IL1 and IL6 receptors (IL1R1 and IL6R) were also expressed in them. The expression of IL1B, IL6, and AvBD10 and -12 was upregulated by LPS, whereas only IL1B and IL6 were upregulated by CpG-ODN. IL1B stimulation upregulated AvBD1 and -3 expression, whereas IL6 stimulation did not cause changes in AvBDs expression. These results suggest that CpG-ODN derived from microbes upregulates the expression of IL1B and IL6 by interaction with TLR21 and then IL1B induces AvBD1 and -3 to prevent infection in the vagina.