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Lee IR, Sng E, Lee KO, Molton JS, Chan M, Kalimuddin S, Izharuddin E, Lye DC, Archuleta S, Gan YH. Comparison of Diabetic and Non-diabetic Human Leukocytic Responses to Different Capsule Types of Klebsiella pneumoniae Responsible for Causing Pyogenic Liver Abscess. Front Cell Infect Microbiol 2017; 7:401. [PMID: 28936426 PMCID: PMC5594087 DOI: 10.3389/fcimb.2017.00401] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 08/25/2017] [Indexed: 12/15/2022] Open
Abstract
The major risk factor for Klebsiella liver abscess (KLA) is type 2 diabetes mellitus (DM), but the immunological mechanisms involved in the increased susceptibility are poorly defined. We investigated the responses of neutrophils and peripheral blood mononuclear cells (PBMCs) to hypervirulent Klebsiella pneumoniae (hvKP), the causative agent of KLA. DNA and myeloperoxidase levels were elevated in the plasma of KLA patients compared to uninfected individuals indicating neutrophil activation, but diabetic status had no effect on these neutrophil extracellular trap (NET) biomarkers in both subject groups. Clinical hvKP isolates universally stimulated KLA patient neutrophils to produce NETs ex vivo, regardless of host diabetic status. Ability of representative capsule types (K1, K2, and non-K1/K2 strains) to survive intra- and extra-cellular killing by type 2 DM and healthy neutrophils was subsequently examined. Key findings were: (1) type 2 DM and healthy neutrophils exhibited comparable total, phagocytic, and NETs killing against hvKP, (2) phagocytic and NETs killing were equally effective against hvKP, and (3) hypermucoviscous K1 and K2 strains were more resistant to total, phagocytic, and NETs killing compared to the non-mucoviscous, non-K1/K2 strain. The cytokine response and intracellular killing ability of type 2 DM as well as healthy PBMCs upon encounter with the different capsule types was also examined. Notably, the IL-12–IFNγ axis and its downstream chemokines MIG, IP-10, and RANTES were produced at slightly lower levels by type 2 DM PBMCs than healthy PBMCs in response to representative K1 and non-K1/K2 strains. Furthermore, type 2 DM PBMCs have a mild defect in its ability to control hvKP replication relative to healthy PBMCs. In summary, our work demonstrates that type 2 DM does not overtly impact neutrophil intra- and extra-cellular killing of hvKP, but may influence cytokine/chemokine production and intracellular killing by PBMCs.
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Affiliation(s)
- I Russel Lee
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of SingaporeSingapore, Singapore
| | - Ethel Sng
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of SingaporeSingapore, Singapore
| | - Kok-Onn Lee
- Department of Medicine, Yong Loo Lin School of Medicine, National University of SingaporeSingapore, Singapore
| | - James S Molton
- Department of Medicine, Yong Loo Lin School of Medicine, National University of SingaporeSingapore, Singapore.,Division of Infectious Diseases, University Medicine Cluster, National University Health SystemSingapore, Singapore
| | - Monica Chan
- Communicable Disease Center, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng HospitalSingapore, Singapore.,Lee Kong Chian School of Medicine, Nanyang Technological UniversitySingapore, Singapore
| | - Shirin Kalimuddin
- Department of Infectious Diseases, Singapore General HospitalSingapore, Singapore
| | - Ezlyn Izharuddin
- Communicable Disease Center, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng HospitalSingapore, Singapore
| | - David C Lye
- Department of Medicine, Yong Loo Lin School of Medicine, National University of SingaporeSingapore, Singapore.,Communicable Disease Center, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng HospitalSingapore, Singapore.,Lee Kong Chian School of Medicine, Nanyang Technological UniversitySingapore, Singapore
| | - Sophia Archuleta
- Department of Medicine, Yong Loo Lin School of Medicine, National University of SingaporeSingapore, Singapore.,Division of Infectious Diseases, University Medicine Cluster, National University Health SystemSingapore, Singapore
| | - Yunn-Hwen Gan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of SingaporeSingapore, Singapore
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