Georgios Michailidis

Aristotle University of Thessaloniki, Saloníki, Central Macedonia, Greece

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Publications (25)44.93 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Toll-like receptors (TLRs) and b-defensins (BD) molecules are group of molecules that recognize various microbial components and play a crucial role in the activation of the innate immune system in vertebrate species. Although TLRs gene expression has been studied in various pig tissues, little is known about their expression in porcine reproductive tract. Concerning b-defensins genes, only BD1, 2 and 3 counterparts have been well studied in pigs' reproductive organs. The aim of this study was to investigate the expression pattern of both gene families in pigs' male and female reproductive organs, and embryos, as potential tool for further association studies in respect to immunity and disease resistance. RT-PCR analysis revealed that all of the examined TLR genes were expressed in the reproductive organs of male and female pigs, with TLR3 and TLR5 showing the higher levels and TLR9 the lowest, in all analyzed tissues. BD genes showed a different expression pattern in respect to the examined tissue. In embryos, TLR1 revealed high expression levels, while only BD3, BD108, and BD123 were found to be expressed.
    Animal Biotechnology 07/2015; 26(3):188-93. DOI:10.1080/10495398.2014.902849
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    Reproduction Fertility and Development 08/2014; DOI:10.1071/RD14147
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    ABSTRACT: Sertoli cells play an important physiological role in the testis, as they support, nourish, and protect the germ cells. As protection of the developing spermatozoa is an emerging aspect of reproductive physiology, this study examined the expression pattern of innate immune related genes, including Avian β-Defensins (AvBDs), Toll-like receptors (TLRs) and cytokines and investigated the time course of an inflammatory response in rooster Sertoli cells triggered by exposure to the bacterial endotoxin lipopolysaccharide (LPS). Sertoli cells were isolated from 6-week old chicken, cultured in vitro and stimulated with 1μg/ml LPS at different time courses (0, 6, 12, 24 and 48 h). Expression analysis data revealed that all 10 members of the chicken TLR family, 9 members of the AvBD family, as well as 8 cytokine genes were expressed in Sertoli cells. Quantitative real-time PCR analysis revealed that LPS treatment resulted in a significant induction in the expression levels of 6 TLR, 6 AvBD and 4 cytokine genes, while 2 cytokine genes were down-regulated and 2 others genes were unchanged. The increasing IL-1beta production was confirmed in the conditioned medium. Furthermore, the phagocytosis of Sertoli cells was increased after LPS treatment. In conclusion, these findings provide evidence that Sertoli cells express innate immune related genes and respond directly to bacterial ligands. These genes represent an important component of the immune system which could be integrated to semen, and present a distinctive constituent of the protective repertoire of the testis to ascending infections.
    Reproduction (Cambridge, England) 06/2014; DOI:10.1530/REP-14-0064
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    M Anastasiadou, A Theodoridis, G Michailidis
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    ABSTRACT: Rooster infertility is a major concern in the poultry industry and protection of the male reproductive organs from pathogens is an essential aspect of reproductive physiology. During the last years, research on antimicrobial protection has elucidated the critical role of the antimicrobial peptides avian β-defensins (AvBDs) in the innate immunity in chickens. AvBDs have been reported to be expressed in the hen reproductive organs, providing protection against microbial pathogens including Salmonella Enteritidis (SE). However, mechanisms of antimicrobial protection of rooster reproductive organs and especially the testis, mediated by AvBDs are poorly understood. The aim of this study was to investigate the expression of the complete family of the 14 AvBD genes, in the rooster testis in vivo, to determine whether sexual maturation affects their testicular mRNA abundance and to investigate whether SE infection alters their expression. Expression analysis revealed that 9 members of the AvBD family, namely AvBD1, 2, 4, 5, 6, 9, 10, 12 and 14 were expressed in the testis. Quantitative real-time PCR analysis revealed that the mRNA abundance of three AvBDs was up regulated and of three AvBDs was down regulated with respect to sexual maturation. In addition, SE infection resulted in a significant induction of AvBD4, 10, 12 and 14 in the testis of sexually mature roosters. These findings provide strong evidence to suggest that an AvBD-mediated immune response mechanism exists in the rooster testis providing protection against bacterial pathogens including Salmonella species.
    Veterinary Research Communications 01/2014; 38(2). DOI:10.1007/s11259-014-9591-4
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    ABSTRACT: In the present study, the single nucleotide polymorphism of CFB (Complement Factor B), BF gene, was analyzed by PCR-RFLP in a commercial pig population in Greece. BF gene is coding for properdin, a protein that plays an integral role in the uterine epithelium growth and is found in a QTL region with many other genes associated with specific reproductive traits. BF gene is considered to affect various reproductive traits in pigs and the present study associated the BF gene genotypes with litter size of the sows (TNB, total number born and NBA number born alive piglets/birth). Sows with AB genotype gave statistically significant lower values for TNB and NBA piglets/birth (p<0.05) than the BB genotype. Our results support the concept that BF belongs to the group of genes that control the litter size of the sows and thus BF gene could be used for Marker-assisted selection programmes for the genetic improvement of reproductive characteristics in livestock.
    Animal reproduction science 07/2013; 141(1-2). DOI:10.1016/j.anireprosci.2013.06.011
  • M Anastasiadou, M Avdi, G Michailidis
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    ABSTRACT: The epididymis is an organ involved in the maturation, transport, and storage of sperm prior to ejaculation. As epididymis is exposed to a constant risk of inflammatory conditions that may lead to transient or permanent sterility, protection of this organ from pathogens is an essential aspect of reproductive physiology. The families of antimicrobial peptides β-defensins and the pattern-recognition receptors Toll-like (TLR) mediate innate immunity in various vertebrates including avian species. As rooster infertility is a major concern in the poultry industry, the objectives of this study were to determine the expression profile of the entire family of the avian β-defensins (AvBD) and TLR genes in the rooster epididymis, to investigate whether sexual maturation affects their epididymidal mRNA abundance and to determine the changes in their expression levels in response to Salmonella enteritidis (SE) infection in the epididymis of sexually mature roosters. RNA was extracted from the epididymis of healthy pubertal, sexually mature and aged birds, and from sexually mature SE infected birds. RT-PCR analysis revealed that 10 members of the AvBD and nine members of the TLR gene families were expressed in the epididymis. Quantitative real-time PCR analysis revealed that the epididymidal mRNA abundance of certain AvBD and TLR genes was developmentally regulated with respect to sexual maturation. SE infection resulted in a significant induction of AvBD 1, 9, 10, 12 and 14, as well as TLR 1-2, 2-1, 2-2, 4, 5 and 7 genes, in the epididymis of sexually mature roosters, compared to healthy birds of the same age. These findings provide strong evidence to suggest that the rooster epididymis is capable of initiating an inflammatory response to Salmonella, through activation of certain members of the AvBD and TLR gene families.
    Animal reproduction science 06/2013; DOI:10.1016/j.anireprosci.2013.06.006
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    ABSTRACT: Avian β-defensins (AvβDs) constitute a family of antimicrobial peptides that are critical to innate immunity in chickens, providing protection against microbial pathogens including Salmonella Enteritidis (SE). As apart from the digestive tract another main route of SE colonization in birds is via infection of the oviduct and specifically of the vagina, the aim of this study was to investigate the expression of the complete family of AvβDs, in the chicken vagina in vivo, to determine whether sexual maturation affects their mRNA abundance and to investigate whether SE infection alters the vaginal AvβDs expression. Expression analysis revealed that 11 members of the AvβD family were expressed in the chicken vagina. Quantitative real-time PCR analysis revealed that the mRNA abundance of five AvβDs was up regulated and of one AvβD was down regulated with respect to sexual maturation. In addition SE infection resulted in a significant induction of AvβD5, 7, 10, 11, 12 and 14 in the vagina of sexually mature birds, and in a significant induction of AvβD5 and 11 in the vagina of aged birds. These findings provide strong evidence to suggest that an AvβD-mediated immune response mechanism exists in the chicken vagina providing protection against bacterial pathogens including Salmonella species.
    Veterinary Research Communications 02/2013; 37(2). DOI:10.1007/s11259-013-9553-2
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    ABSTRACT: Rooster infertility is a major concern in the poultry industry and chicken male reproductive organs are the infectious tissues of various pathogenic microorganisms. Protection of the chicken male reproductive organs from pathogens is therefore an essential aspect of reproductive physiology. Recently Toll-like receptors (TLRs) have been identified as one of the key components of innate immunity in vertebrate species and have been reported to be expressed in the reproductive organs in various female species, including the chicken. However, mechanisms of antimicrobial protection of male reproductive organs mediated by TLRs are poorly understood. The objectives of this study were to determine the expression profile of the entire family of the ten chicken TLR genes in the chicken testis, to investigate whether sexual maturation affects their testicular mRNA abundance and to determine the changes in their expression levels in response to Salmonella enteritidis (SE) infection. RNA was extracted from the testis of healthy pre-pubertal, sexually mature and aged birds, and from sexually mature SE infected birds. RT-PCR analysis revealed that all TLRs, apart from TLR1-1 (TLR6), were expressed in the chicken testis. Quantitative real-time PCR analysis revealed that the testicular mRNA abundance of certain TLRs was developmentally regulated with respect to sexual maturation, while SE infection resulted in a significant induction of TLR2-1, 4, 5, 15 and 21 in the testis of sexually mature birds compared, to healthy birds of the same age. These findings provide strong evidence to suggest a key role of TLRs in the innate immune responses of chicken testis against Salmonella colonization.
    Animal reproduction science 10/2011; 128(1-4):93-9. DOI:10.1016/j.anireprosci.2011.09.003
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    ABSTRACT: The actin-binding protein profilin (PRF) plays an important role in cell growth and expansion by regulating the organization of the actin filaments. Recent studies have reported association between fiber elongation in cultivated cotton (Gossypium hirsutum) and PRF expression. In the present study, we cloned four genomic clones from allotetraploid cotton (G. hirsutum) and its putative diploid progenitors (G. arboreum and G. raimondii) designated GhPRF1_A, GhPRF1_D, GaPRF1, and GrPRF1 encoding cotton PRF and characterized their genomic structure, phylogenetic relationships and promoter structure. Sequence analysis of the coding regions of all clones resulted in a single protein product which revealed more than 80% similarity to most plant PRFs and a typical organization with an actin-binding and a polybasic phospholipid binding motif at the carboxy terminus. DNA blot hybridization suggested that PRF gene is present with more than one copy in the allotetraploid species G. hirsutum. Expression analysis performed in various organs of cultivated cotton revealed that the PRF gene was preferentially expressed in cotton fibers. Very low levels of expression were observed in whole flowers, while PRF transcripts were not detected in other organs examined. Furthermore, higher levels of expression were observed at the early stages of cotton fiber development (at 10 days post anthesis), indicative that this gene may play a major role in the early stages of cotton fiber development. Quantitation of the expression by real-time PCR revealed higher expression levels in a G. hirsutum variety with higher fiber percentage compared to a variety with lower percentage. In addition, higher levels of expression were found in cultivated allotetraploid G. barbadense cotton species with higher fiber length in comparison to cultivated allotetraploid G. hirsutum.
    Molecular Biology Reports 07/2011; 39(4):3523-32. DOI:10.1007/s11033-011-1125-3
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    ABSTRACT: The objective of this study was to investigate the association of polymorphisms at the STAT5A and FGF2 gene loci with fertility, lactation milk yield and lameness in dairy cattle. Five hundred and eighteen primiparous Holstein cows were included in the study. Several reproductive traits were considered including conception rate (0/1) at first insemination, conception rate (0/1) in a 305-day lactation, number of inseminations per conception, interval (days) from calving to conception for cows that conceived in the first 305 days of lactation and age at first calving. Milk yield and lameness incidence were also recorded. Genotyping was performed using PCR-RFLP. The effect of allele substitution at each gene locus on reproductive traits, milk yield and lameness was assessed with single-trait mixed linear models. No significant associations were found between reproduction traits and any of the studied polymorphisms, apart from age at first calving, for which STAT5A polymorphism had a suggestive effect (P = 0.077). In addition, no significant effect of any polymorphism on lameness was found. Replacement of the C by G allele at the STAT5A locus was associated with a significant (P<0.05) increase in lactation milk yield, suggesting that this locus could be considered in gene assisted selection for the genetic improvement of milk production.
    Research in Veterinary Science 02/2011; 91(2):235-9. DOI:10.1016/j.rvsc.2011.01.009
  • G Michailidis, A Theodoridis, M Avdi
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    ABSTRACT: Toll-like receptors (TLRs) are a critical component of the innate immune response in many vertebrates, including avian species. The recent findings of chicken TLRs (cTLRs) expression in ovarian follicles and in the chicken ovary in vivo, as well as the changes in their expression in response to lipopolysaccharide or Salmonella enteritidis (SE) infection, have broad implications for reproductive physiology and for the prevention of transmission of zoonotic diseases to humans through the consumption of contaminated poultry eggs. Because the main route of egg contamination is from infection of the oviduct and mainly from the vagina, the aim of this study was to investigate the expression of the ten cTLRs identified to date in the chicken oviduct in vivo, to determine whether sexual maturation affects their mRNA abundance and to investigate whether SE infection alters the expression of TLRs in the chicken vagina. RNA was extracted from the vagina of healthy prepubertal, sexually mature and aged birds, and from sexually mature and aged SE infected birds. RT-PCR analysis revealed that all types of cTLRs apart from TLR1-1 were expressed in the vagina of sexually mature birds. Quantitative real-time PCR analysis revealed that the mRNA abundance of TLR2-1, 2-2 and 4 differ with respect to sexual maturation in the chicken vagina. SE infection resulted in a significant induction of TLR5 and 15 in the vagina of sexually mature birds, and in a significant induction of TLR2-1, 4 and 15 in the vagina of aged birds, while a significant down-regulation was observed for TLR7 in the vagina of sexually mature birds. These findings suggest that a TLR mediated immune response mechanism exists in the chicken vagina, playing a crucial role in preventing microbial pathogens from being incorporated into newly forming eggs.
    Animal reproduction science 02/2011; 123(3-4):234-41. DOI:10.1016/j.anireprosci.2011.01.010
  • G Michailidis, M Avdi, A Argiriou
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    ABSTRACT: Avian β-defensins (AvβDs) are antimicrobial peptides that play significant roles in the innate immune system in chickens. The aim of this study was to identify the types of AvβDs expressed in the chicken ovary, to investigate the effects of sexual maturation in the ovarian mRNA abundance and to determine the changes in their expression levels as a result to Salmonella enteritidis (SE) infection. RNA was extracted from the ovary of healthy prepubertal, sexually mature and aged birds, as well as from sexually mature and aged SE infected birds. Real-time PCR analysis revealed that 11 AvβDs genes were expressed in the chicken ovary. A significant up regulation of AvβD1, 3, 4, 5, 7 and 11 was observed in the ovary of sexually mature and aged birds. Furthermore, a significant up-regulation of AvβD4, 5, 7, 11 and 12 was observed in the ovary of SE infected sexually mature birds. These results suggest that the mRNA expression of at least six AvβDs increase with age in the ovary of laying hens, and that at least five AvβDs show an induction in their expression in response to SE infection, indicating an AvβD-mediated immune response mechanism in the chicken ovary.
    Research in Veterinary Science 11/2010; 92(1):60-5. DOI:10.1016/j.rvsc.2010.10.010
  • G Michailidis, A Theodoridis, M Avdi
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    ABSTRACT: One of the key members of the innate immune system in many vertebrate species is the family of Toll-like receptors (TLRs). These molecules, which initiate the innate immune response and mount an anti-microbial response in both vertebrates and invertebrates, have recently been identified in the chicken genome. The recent findings of chicken TLRs (cTLRs) expression in ovarian follicles during follicular growth and in response to lipopolysaccharide (LPS) infection are very important for reproductive physiology due to the transovarian transmission of Salmonella enteritidis (SE) in laying hens. The aim of this study was to investigate the expression of the ten cTLRs identified to date, in the chicken ovary in vivo and embryos during early embryonic development, to investigate whether sexual maturation affects their ovarian mRNA abundance and to investigate the transcriptional changes of TLRs in the chicken ovary in response to SE infection. RNA was extracted from embryos from day 3 to day 10 of embryonic development as well as from the ovaries of healthy prepubertal, sexually mature and aged birds, and from sexually mature and aged SE infected birds. RT-PCR analysis revealed that all TLRs apart from TLRs 1-1 and 2-2 were expressed in the ovary of sexually mature chickens, while all TLRs apart from TLR1-1 were expressed in the chicken embryos during embryonic development. Quantitative real-time PCR analysis revealed that the ovarian mRNA abundance of TLRs differ with respect to sexual maturation. SE infection resulted in a significant induction of TLR4, and 15 in the ovary of sexual mature birds, and in a significant induction of TLR15 in the ovary of aged birds, while a significant down-regulation was observed for TLR3 in the ovary of aged birds. These findings suggest that a TLR-mediated immune response mechanism exists in the chicken ovary.
    Animal reproduction science 10/2010; 122(3-4):294-302. DOI:10.1016/j.anireprosci.2010.09.004
  • Georgios Michailidis
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    ABSTRACT: In recent years host antimicrobial peptides and proteins have been recognised as key mediators of the innate immune response in many vertebrate species, providing the first line of defense against potential pathogens. In chickens a number of cationic antimicrobial peptides have been recently identified. However, although these peptides have been studied extensively in the avian gastrointestinal tract, little is known about their function in the chicken reproductive organs and embryos. Chicken Liver Expressed Antimicrobial Peptide-2 (cLEAP-2) has been previously reported to function in protecting birds against microbial attack. The aim of this study was to investigate the expression of cLEAP-2 gene in the chicken reproductive organs, as well as in chicken embryos during embryonic development, and to determine whether cLEAP-2 expression in the chicken reproductive organs was constitutive or induced as a response to Salmonella enteritidis infection. RNA was extracted from ovary, oviduct, testis and epididymis of sexually mature healthy and Salmonella infected birds, as well as from chicken embryos until day ten of embryonic development. Expression analysis data revealed that cLEAP-2 was expressed in the chicken ovary, testis and epididymis as well as in embryos during early embryonic development. Quantitative real-time PCR analysis revealed that cLEAP-2 expression was constitutive in the chicken epididymis, but was significantly up regulated in the chicken gonads, following Salmonella infection. In addition, expression of cLEAP-2 during chicken embryogenesis appeared to be developmentally regulated. These data provide evidence to suggest a key role of cLEAP-2 in the protection of the chicken reproductive organs and the developing embryos from Salmonella colonization.
    Veterinary Research Communications 06/2010; 34(5):459-71. DOI:10.1007/s11259-010-9420-3
  • Georgios Michailidis, Anagnostis Argiriou, Melpomeni Avdi
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    ABSTRACT: Maternal mRNAs, which are expressed in oocytes, play an important role in the success of early embryo development, as they allow the first cleavages to occur. Zygote arrest 1 (Zar1) is an oocyte-specific maternal-effect gene that functions at the oocyte-to-embryo transition in many vertebrate species including human, pig, cattle, sheep, mouse, rat, frog and zebrafish. Recently, through in silico studies, a gene structurally related to Zar1, called Zar1-like has been identified in many vertebrates, including the chicken. The objectives of this study were to investigate the expression of the chicken Zar1 and Zar1-like genes in chicken tissues and embryos and to determine whether sexual maturation affects their mRNA abundance. RNA was extracted from various organs of chickens aged from one month up to two years old and from chicken embryos until day ten of embryonic development. Expression analysis of the genes was performed using RT-PCR and real-time PCR. RT-PCR analysis revealed that both genes were preferentially expressed in chicken oocytes, ovary and testes and in embryos during embryonic development. Quantitative real-time PCR analysis revealed a significant up regulation of Zar1 in the mature ovary, and also a significant up regulation of Zar1 and Zar1-like genes in the testes of sexually mature roosters, suggesting a key role of these genes in the chicken fertility. In contrast, expression of Zar1-like was not affected by age in the chicken ovary. Our results indicate that the chicken Zar1 and Zar1-like transcripts are co-expressed in high levels in the chicken gonads. In addition their expression beyond the stage of embryonic genome activation suggests an embryonic and not only a maternal origin of these transcripts.
    Veterinary Research Communications 02/2010; 34(2):173-84. DOI:10.1007/s11259-010-9343-z
  • Claire L Townes, Georgios Michailidis, Judith Hall
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    ABSTRACT: Chicken Liver Expressed Antimicrobial Peptide-2 (cLEAP-2) is known to have killing activities against Salmonella spp., but the mechanism by which killing occurs remains to be elucidated. The ability of cLEAP-2 to disrupt the outer membrane of several Salmonella spp. was assessed using the fluorescent probe N-phenyl-1-naphthylamine (NPN). A rapid dose-dependent permeabilization of the outer membranes of Salmonella enterica serovar Typhimurium phoP, and S. enterica serovar Typhimurium SL1344 was observed although no significant permeabilisation of the S. enteriditis membrane was detected. These data suggested that the ability of the mature cLEAP-2 peptide to permeabilise the Salmonella outer membrane is important in mediating its killing activities. The ability of the peptide to kill Gram-positive bacteria, specifically Streptococcus spp. and Staphylococcus spp. was also investigated using recombinant peptide and a time-kill assay. Of the strains analysed the Streptococcus pyogenes M1 strain appeared the most resistant to LEAP-2 killing although S. pyogenes mutants deficient in Sortase and M1 activities showed increased sensitivity to the mature peptide. This suggested the involvement of specific Streptococcus cell wall proteins including M1 in the resistance of the bacteria to cLEAP-2 killing. cLEAP-2 showed no significant toxicity towards mammalian erythrocytes indicating selectivity for bacterial over eukaryote cell membranes. These data provide further support for mature cLEAP-2 functioning in protecting the chicken against microbial attack.
    Biochemical and Biophysical Research Communications 08/2009; 387(3):500-3. DOI:10.1016/j.bbrc.2009.07.046
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    G. Michailidis, A. Kalivas, M. Avdi, A. Argiriou
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    ABSTRACT: Export Date: 1 September 2011, Source: Scopus
  • G. Michailidis, A. Argiriou, M. Avdi
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    ABSTRACT: Gallinacins (Gals) are antimicrobial peptides that play a significant role in innate immunity in chickens providing the first line of defence against potential pathogens. The aim of this study was to determine the changes in expression of Gals 4 and 5 during growth and in response to Salmonella enteritidis (SE) infection in the ovary and oviduct of egg laying hens. RNA was extracted from the ovary and oviduct of hens aged between three month and. two-year-old and SE-infected hens. Expression of Gals 4 and 5 mRNA was examined by quantitative Real-Time RT-PCR. Expression analysis data revealed a significant upregulation of Gals 4 and 5 in the ovary during growth and in response to SE infection. In addition, the expressions of Gals 4 and 5 in the oviduct were significantly greater in older birds than in young ones but decreased in nonlaying hens in response to SE infection. These results suggest that the mRNA expressions of Gals 4 and 5 increased with age in the ovary and oviduct of laying hens; they increased in the ovary in response to SE challenge, whereas they decreased in the regressed oviduct during the nonlaying phase. Also, synthesis of these antimicrobial peptides in the oviduct decrease in response to SE infection.
  • G. Michailidis, A. Argiriou, M. Avdi
  • G. Michailidis, A. Argiriou, M. Avdi

Publication Stats

166 Citations
44.93 Total Impact Points

Institutions

  • 2009–2015
    • Aristotle University of Thessaloniki
      • • Laboratory of Animal Reproduction and Animal Physiology
      • • Department of Animal Production
      Saloníki, Central Macedonia, Greece
  • 2005
    • Newcastle University
      • Institute for Cell and Molecular Biosciences
      Newcastle-on-Tyne, England, United Kingdom