Immunization with Complete Freund’s Adjuvant Reveals Trained Immunity-like Features in A/J Mice

Background/Objectives: Freund’s adjuvants induce different immunomodulatory effects, but their underlying molecular mechanisms are unclear. In this study, we investigated whether the immune-stimulating effects of the complete Freund’s adjuvant (CFA) involve the mechanisms of trained immunity (TI). M...

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Main Authors: Kiruthiga Mone, Shraddha Singh, Fatema Abdullatif, Meghna Sur, Mahima T. Rasquinha, Javier Seravalli, Denise K. Zinniel, Indranil Mukhopadhyay, Raul G. Barletta, Teklab Gebregiworgis, Jay Reddy
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Vaccines
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Online Access:https://www.mdpi.com/2076-393X/13/7/768
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author Kiruthiga Mone
Shraddha Singh
Fatema Abdullatif
Meghna Sur
Mahima T. Rasquinha
Javier Seravalli
Denise K. Zinniel
Indranil Mukhopadhyay
Raul G. Barletta
Teklab Gebregiworgis
Jay Reddy
author_facet Kiruthiga Mone
Shraddha Singh
Fatema Abdullatif
Meghna Sur
Mahima T. Rasquinha
Javier Seravalli
Denise K. Zinniel
Indranil Mukhopadhyay
Raul G. Barletta
Teklab Gebregiworgis
Jay Reddy
author_sort Kiruthiga Mone
collection DOAJ
description Background/Objectives: Freund’s adjuvants induce different immunomodulatory effects, but their underlying molecular mechanisms are unclear. In this study, we investigated whether the immune-stimulating effects of the complete Freund’s adjuvant (CFA) involve the mechanisms of trained immunity (TI). Methods: We examined bone marrow cells (BMCs) isolated from CFA-immunized A/J mice to address this question. Incomplete Freund’s adjuvant (IFA) and <i>Mycobacterium tuberculosis</i> var. <i>bovis</i> Bacillus Calmette-Guérin (BCG) served as negative and positive controls, respectively. We evaluated cytokine profiles, metabolic, and epigenetic changes. Results: First, BMCs from all groups except saline showed varied levels of IL-1β, IL-6, and TNF-α. But expression of CCL5 and CXCL10 was significantly elevated only in the CFA and BCG groups. Transcriptionally, significant elevations were noted for TNF-α and IL-1β in the CFA and BCG groups, whereas CXCL10, IL-6, and IL-10 were upregulated in the CFA and BCG groups, respectively. Second, while BMCs from the BCG group expressed the markers of both the M1 and M2 macrophages, no clear trends were noted in the CFA and IFA groups. Third, cell lysates from the CFA group revealed metabolic reprogramming in the BMCs. Specifically, we observed an increased level of lactate, indicative of aerobic glycolysis, which is implicated in TI, and this was also detected in the IFA group. Fourth, epigenetic analysis revealed histone enrichment in the promoter region of TNF-α, in the CFA group, but to a lesser degree than the BCG group. However, no epigenetic changes were observed in the IFA group. Conclusions: Our data provide new insights into the mechanisms of Freund’s adjuvants and the immunomodulatory effects of CFA could involve the features of TI.
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spelling doaj-art-2ed3fae1634b49abb6fd39199b0bb8982025-08-20T02:47:06ZengMDPI AGVaccines2076-393X2025-07-0113776810.3390/vaccines13070768Immunization with Complete Freund’s Adjuvant Reveals Trained Immunity-like Features in A/J MiceKiruthiga Mone0Shraddha Singh1Fatema Abdullatif2Meghna Sur3Mahima T. Rasquinha4Javier Seravalli5Denise K. Zinniel6Indranil Mukhopadhyay7Raul G. Barletta8Teklab Gebregiworgis9Jay Reddy10School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USASchool of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USADepartment of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A 5C1, CanadaSchool of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USASchool of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USADepartment of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USASchool of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USADepartment of Statistics, University of Nebraska-Lincoln, Lincoln, NE 68583, USASchool of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USADepartment of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A 5C1, CanadaSchool of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USABackground/Objectives: Freund’s adjuvants induce different immunomodulatory effects, but their underlying molecular mechanisms are unclear. In this study, we investigated whether the immune-stimulating effects of the complete Freund’s adjuvant (CFA) involve the mechanisms of trained immunity (TI). Methods: We examined bone marrow cells (BMCs) isolated from CFA-immunized A/J mice to address this question. Incomplete Freund’s adjuvant (IFA) and <i>Mycobacterium tuberculosis</i> var. <i>bovis</i> Bacillus Calmette-Guérin (BCG) served as negative and positive controls, respectively. We evaluated cytokine profiles, metabolic, and epigenetic changes. Results: First, BMCs from all groups except saline showed varied levels of IL-1β, IL-6, and TNF-α. But expression of CCL5 and CXCL10 was significantly elevated only in the CFA and BCG groups. Transcriptionally, significant elevations were noted for TNF-α and IL-1β in the CFA and BCG groups, whereas CXCL10, IL-6, and IL-10 were upregulated in the CFA and BCG groups, respectively. Second, while BMCs from the BCG group expressed the markers of both the M1 and M2 macrophages, no clear trends were noted in the CFA and IFA groups. Third, cell lysates from the CFA group revealed metabolic reprogramming in the BMCs. Specifically, we observed an increased level of lactate, indicative of aerobic glycolysis, which is implicated in TI, and this was also detected in the IFA group. Fourth, epigenetic analysis revealed histone enrichment in the promoter region of TNF-α, in the CFA group, but to a lesser degree than the BCG group. However, no epigenetic changes were observed in the IFA group. Conclusions: Our data provide new insights into the mechanisms of Freund’s adjuvants and the immunomodulatory effects of CFA could involve the features of TI.https://www.mdpi.com/2076-393X/13/7/768trained immunityadjuvantsFreund’s adjuvantscomplete Freund’s adjuvantincomplete Freund’s adjuvantCFA
spellingShingle Kiruthiga Mone
Shraddha Singh
Fatema Abdullatif
Meghna Sur
Mahima T. Rasquinha
Javier Seravalli
Denise K. Zinniel
Indranil Mukhopadhyay
Raul G. Barletta
Teklab Gebregiworgis
Jay Reddy
Immunization with Complete Freund’s Adjuvant Reveals Trained Immunity-like Features in A/J Mice
Vaccines
trained immunity
adjuvants
Freund’s adjuvants
complete Freund’s adjuvant
incomplete Freund’s adjuvant
CFA
title Immunization with Complete Freund’s Adjuvant Reveals Trained Immunity-like Features in A/J Mice
title_full Immunization with Complete Freund’s Adjuvant Reveals Trained Immunity-like Features in A/J Mice
title_fullStr Immunization with Complete Freund’s Adjuvant Reveals Trained Immunity-like Features in A/J Mice
title_full_unstemmed Immunization with Complete Freund’s Adjuvant Reveals Trained Immunity-like Features in A/J Mice
title_short Immunization with Complete Freund’s Adjuvant Reveals Trained Immunity-like Features in A/J Mice
title_sort immunization with complete freund s adjuvant reveals trained immunity like features in a j mice
topic trained immunity
adjuvants
Freund’s adjuvants
complete Freund’s adjuvant
incomplete Freund’s adjuvant
CFA
url https://www.mdpi.com/2076-393X/13/7/768
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