Helicobacter Infection in the Surfactant Protein D-Deficient Mouse


Reprint request to: Wafa Khamri, Immunoregulation Laboratory, Department of Nephrology and Transplantation, 5th Floor Thomas Guy House, Guy's Hospital Campus, King's College London School of Medicine at Guy's, London SE1 9RT, UK. Tel.: +44 207 1887672; Fax: +44 207 1887675; E-mail: wafa.khamri@kcl.ac.uk.


Background:  Surfactant protein D (SP-D), a component of innate immunity, is expressed in the gastric mucosa and is up-regulated in the presence of Helicobacter infection. SP-D binds to Helicobacter in vitro, suggesting the involvement of SP-D in Helicobacter-induced immune responses. The aim of this study was to determine the role of SP-D in gastric epithelial defense in vivo.

Methods:  Specific pathogen-free SP-D-deficient mice (SP-D−/–) and C57BL/6 wild-type controls were challenged by gavage with different doses of Helicobacter felis, a mouse-adapted Helicobacter strain. Mice were assessed for colonization rates and density of infection. Inflammatory responses were measured by neutrophil counting and T-cell responses by proliferation assays on spleen cells stimulated with H. felis sonicate. The in vitro effect of SP-D on Helicobacter uptake by monocyte-derived dendritic cells was assessed by confocal microscopy and FACS analyses.

Results:  SP-D−/– mice were more susceptible to low-dose infectious challenge than C57BL/6 controls (p = .02). The density of colonization was higher in the SP-D−/– infected mice. Neutrophil infiltrates were lower in the SP-D−/– mice, particularly in the acid-secreting regions of the stomach. T-cell proliferative responses to Helicobacter antigen were reduced in SP-D−/– mice (p = .001) after 12 weeks infection. In vitro uptake of Helicobacter by dendritic cells was significantly enhanced in the presence of SP-D (p = .001).

Conclusion:  In the absence of SP-D, Helicobacter uptake by dendritic cells is impaired. This provides an explanation for the diminished inflammation and immune responses in the SP-D−/– mice.