CpG-ODN Induces a Dose-Dependent Enrichment of Immunological Niches in the Spleen and Lungs of Neonatal Chicks That Correlates with the Protective Immunity against Escherichia coli

• Published in: Journal of immunology research 2020, Vol.2020 (2020), p.1-15
• Main Authors: Foldvari, Marianna, Tikoo, Suresh K., Willson, Philip, Gomis, Susantha, Gupta, Ashish, Ayalew, Lisanework E., Karunarathana, Ruwani, Kurukulasuriya, Shanika, Popowich, Shelly, Goonewardene, Kalhari, Ahmed, Khawaja Ashfaque, Gunawardana, Thushari, Lockerbie, Betty
• Format: Article
• Language: English
• Subjects: Adjuvants, Immunologic - administration & dosage; Animals; Antibiotic Prophylaxis - adverse effects; Antibiotics; Antigens; Antimicrobial agents; Bacteria; Bacterial infections; Biotechnology; CD4 antigen; CD4-Positive T-Lymphocytes - drug effects; CD4-Positive T-Lymphocytes - immunology; CD40 antigen; CD8 antigen; CD8-Positive T-Lymphocytes - drug effects; CD8-Positive T-Lymphocytes - immunology; Chemokines; Chickens; Chickens - immunology; Chickens - microbiology; Chicks; Cloning; CpG islands; Cytokines; Dose-Response Relationship, Immunologic; E coli; Eggs; Enrichment; Escherichia coli - immunology; Escherichia coli - isolation & purification; FDA approval; Flow cytometry; Immune system; Immunity; Immunology; Infections; Juveniles; Lung - cytology; Lung - drug effects; Lung - immunology; Lungs; Lymphocytes T; Macrophages; Macrophages - drug effects; Macrophages - immunology; Monocytes; Neonates; Oligodeoxyribonucleotides - administration & dosage; Oligonucleotides; Organs; Pathogens; Poultry; Poultry Diseases - immunology; Poultry Diseases - microbiology; Poultry Diseases - prevention & control; Salmonella; Sepsis; Spleen; Spleen - cytology; Spleen - drug effects; Spleen - immunology
• ISSN: 2314-8861; 2314-7156
• DOI: 10.1155/2020/2704728

Immunoprotective function of oligodeoxynucleotides containing CpG motifs (CpG-ODN) has been demonstrated in neonatal chickens against common bacterial pathogens such as E.coli and Salmonella sp. Our recent study reported that CpG-ODN administration enriches immune compartments in neonatal chicks. However, a causal relationship between CpG-ODN-induced immune enrichment and protective mechanisms remains unestablished. In this study, we investigated in ovo administered CpG-ODN-mediated immune cell recruitment in the immunological niches in lymphoid (spleen) and nonlymphoid (lungs) organs using various doses of CpG-ODN and examined whether the immunological profiles have any correlation with immunoprotection against E.coli infection. Eighteen-day-old embryonated eggs were injected with either 5, 10, 25, and 50 μg of CpG-ODN or saline (n=~40 per group). On the day of hatch (72 hr after CpG-ODN treatment), we collected the spleen and lungs (n=3‐4 per group) and examined the recruitment of macrophages/monocytes, their expression of MHCII and CD40, and the number of CD4+ and CD8+ T-cell subsets in the immunological niches in the spleen and lungs using flow cytometry. We observed the dose-dependent recruitment of immune cells, wherein 25 μg and 50 μg of CpG-ODN induced significant enrichment of immunological niches in both the spleen and the lungs. Four days after the CpG-ODN treatment (1-day after hatch), chicks were challenged with a virulent strain of E. coli (1×104 or 1×105 cfu, subcutaneously). Clinical outcome and mortality were monitored for 8 days postchallenge. We found that both 25 μg and 50 μg of CpG-ODN provided significant protection and reduced clinical scores compared to saline controls against E. coli infection. Overall, the present study revealed that CpG-ODNs orchestrate immunological niches in neonatal chickens in a dose-dependent manner that resulted in differential protection against E. coli infection, thus supporting a cause and effect relationship between CpG-ODN-induced immune enrichment and the antibacterial immunity.