1. No Ameliorating Effect of Surfactant Protein D on DSS-Induced Colitis in Mice
Anders B. Nexoe1, Bartosz Pilecki1, Mathias Rathe2, Steffen Husby2, Uffe Holmskov1, Grith L. Sorensen1
1Department of Cancer and Inflammation Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
2H. C. Andersen Children’s Hospital, Odense University Hospital, Odense, Denmark
ABSTRACT
Inflammatory bowel diseases (IBD) are disorders associated to a pathological immune response. Surfactant protein D (SP-D) is part of the innate host defense and has known anti-inflammatory effects. We hypothesize that SP-D dampens dextran sodium sulfate (DSS)-induced colitis by reducing innate inflammatory signaling and facilitation clearance of apoptotic cells. We induced experimental colitis in C57BL/6N Sftpd-/- (KO) and Sftpd+/+ (WT) mice by administration of 1% or 1.5% DSS for 7 days.
BACKGROUND
SP-D is a collectin widely distributed on mucosal surfaces of the body including the gastrointestinal tract. It is part of the innate immune system and mediates control of pro-inflammatory mechanisms.
Genetic variations of SP-D have recently been associated to IBD in a Japanese population and showed association to ulcerative colitis (UC) (1). In contrast, an American case-control analysis revealed a significant association between a specific SP-D genetic variant and susceptibility to Crohn’s disease (CD), but not UC (2).
Together these two studies suggest that SP-D is involved in IBD and warrant in vivo studies of the related pathophysiological mechanisms.
FIGURES
Figure 1: WT Control (n=10), KO Control (n=9), WT 1.5% DSS (n=10), KO 1.5% DSS (n=9), WT 1% DSS (n=12), KO 1% DSS (n= 11).
All data are represented as means ± SEM.
AIM
We aim to compare the inflammatory response between WT and KO mice in a dextran sodium sulfate (DSS) model of colitis.
We hypothesize that SP-D dampens DSS-induced colitis by reducing innate inflammatory signaling and facilitate clearance of apoptotic cells.
Figure 2: WT Control (n=10), KO Control (n=9), WT 1.5% DSS (n=10), KO 1.5% DSS (n=9), WT 1% DSS (n=12), KO 1% DSS (n= 11).
All data are represented as means ± SEM.
METHODS
Sftpd-/- (KO) and Sftpd+/+ (WT) mice were backcrossed into the C57BL/6N background. Colitis was induced in week-old male KO and WT littermates by supplementing the ad libitum water with 1% or 1.5% DSS for 7 days. Treatment with 1% DSS will be followed by 3 days of water.
We monitored weight loss and disease activity index (DAI score) and measured the colon length at termination.
To come:
The colons will be stained with hematoxylin & eosin to estimate the histological damage and immunohistochemical stainings will be used to analyze levels of apoptosis, necrosis and inflammatory infiltration.
Colon tissue samples will be analyzed for, neutrophil activity, levels of SP-D and inflammatory markers (TNF-α, IL-6, INF-γ, TGF-β, CCL-2 and iNOS)
Day 0:
Start of treatment with DSS
Day 7:
Mice receiving 1.5% DSS are terminated
1% DSS is replaced with water
Day 10:
Mice receiving water for 3 days are terminated
Figure 3: WT Control (n=10), KO Control (n=9), WT 1.5% DSS (n=10), KO 1.5% DSS (n=9), WT 1% DSS (n=12), KO 1% DSS (n= 11).
All data are represented as means ± SEM.
CONCLUSION
Our in vivo study of a potential SP-D mediated amelioration of DSS induced colitis showed no difference in weight loss, DAI score or the length of colon between WT and KO animals when treated with 1% for 7 days or 1.5% DSS for 7 days followed by 3 days of restitution. Thus it seems that there is no ameliorating effect of SP-D on DSS-induced colitis in mice.
RESULTS
While mice treated with DSS did experience a notable weight loss, there were no difference between WT and KO (figure 1).
Likewise we observed an increased DAI score and a decrease in the length of colon in mice treated with DSS, but there were no difference between WT and KO (figure 2 and figure 3).
REFERENCES
1. Tanaka M, Arimura Y, Goto A, Hosokawa M, Nagaishi K, Yamashita K, et al. Genetic variants in surfactant, pulmonary-associated protein D (SFTPD) and Japanese susceptibility to ulcerative colitis. Inflammatory bowel diseases Jun;15(6): PubMed PMID:
2. Lin Z, John G, Hegarty JP, Berg A, Yu W, Wang Y, et al. Genetic variants and monoallelic expression of surfactant protein-D in inflammatory bowel disease. Ann Hum Genet Sep;75(5): PubMed PMID: Pubmed Central PMCID: PMC
This work was supported by The A.P. Møller Foundation for the Advancement of Medical Science and OUH’s Prægraduat Pulje
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