Immunomodulatory Effects of Lactoferrin during Burkholderia thailandensis Infection. (4th October 2017)

• Record Type: Journal Article
• Authors: Wright, Shelton; Lovelace-Macon, Lara; Ducken, Deirdre; West, T Eoin
• Is Part Of: Open forum infectious diseases. Volume 4(2017)Supplement 1
• Page Start: S225
• Page End: S225
• Publication Date: 2017-10-04
• Subjects: Communicable diseases -- Periodicals; Medical microbiology -- Periodicals; Infection -- Periodicals; 616.9
• DOI: 10.1093/ofid/ofx163.467
• Languages: English
• ISSNs: 2328-8957

Abstract

Abstract: Background: Melioidosis is a tropical infection caused by the Gram-negative bacterium and Tier 1 select agent Burkholderia pseudomallei . Agnostic whole exome sequencing of DNA from patients with melioidosis has identified single nucleotide variants in the lactoferrin gene that are associated with death. Lactoferrin is a glycoprotein with both antimicrobial and immunomodulatory properties. We investigated whether iron-saturated lactoferrin altered Burkholderia growth or cellular responses to Burkholderia infection. Methods: (1) Burkholderia thailandensis, a bacterium closely related to B. pseudomallei and does not require BSL-3 select agent containment, was cultured in liquid M9 minimal media in the presence of varying concentrations of iron-saturated purified human lactoferrin (phLTF) or recombinant human lactoferrin (rhLTF). Growth was quantified at 24 hours. (2) A human monocyte cell line (THP-1) was differentiated and infected with B. thailandensis at multiplicities of infection (MOI) 1 and 10. phLTF or rhLTF 100 μg/mL was added 1 hour after infection and cell supernatants were collected at 6 hours. TNF-α, IFN-γ, and IL-1β concentrations were measured by ELISA. Under these conditions, a kanamycin protection assay was performed 1 hour after infection and at 6 hours, lysed cell supernatants were incubated over 24 hours and colonies counted. Results: (1) B. thailandensis growth in minimal media broth was not altered by the presence of phLTF or rhLTF. (2) Infected THP-1 cells released higher concentrations of IL-1β in the presence of phLTF at MOI 10. Infected THP-1 cells released higher concentrations of TNF-α in the presence of rhLTF at MOI 1 and in the presence of rhLTF or phLTF at MOI 10 (Figure 1, * P < 0.05). IFN-γ concentrations were below the level of detection of the assay. Cells exposed to phLTF expressed more intracellular bacteria compared with controls (Figure 2, * P < 0.05). Conclusion: While lactoferrin does not alter B. thailandensis growth in liquid media, it does increase the release of the pro-inflammatory cytokines in monocytes. Together, these novel results suggest that lactoferrin may have an important immunomodulatory role in melioidosis. Further studies will evaluate the in vitro effect of iron-desaturated lactoferrin and lactoferrin gene variants on microbial activity. Disclosures: T. E. West, NIH: Grant Investigator and Scientific Advisor, Research grant. DTRA: Grant Investigator, Research grant