Increased susceptibility to dextran sulfate sodium induced colitis in the T cell protein tyrosine phosphatase heterozygous mouse - PubMed (original) (raw)
Increased susceptibility to dextran sulfate sodium induced colitis in the T cell protein tyrosine phosphatase heterozygous mouse
Syed-Wajahat Hassan et al. PLoS One. 2010.
Abstract
T cell protein tyrosine phosphatase (TC-PTP/PTPN2) is an enzyme that is essential for the proper functioning of the immune system and that participates in the control of cell proliferation, and inflammation. We previously observed that TC-PTP(-/-) mice display various immunodeficiencies, hypersensitivity to LPS and die within three weeks of birth due to anemia and widespread inflammation. A recent analysis of the Wellcome Trust Case Control Consortium (WTCC) genome wide scan data, reported in 2007, indicated a potential role for TC-PTP in inflammatory bowel disease (IBD). To further investigate the potential role of TC-PTP in IBD, we studied heterozygous TC-PTP mutant mice challenged with dextran sulfate sodium (DSS) in their drinking water. In comparison to control animals, we observed significant changes in the colon mucosa of DSS-treated TC-PTP(+/-) mice, in the ratio of colon to body weight, as well as an up-regulation of mRNA transcripts for IL-6, IL-23, 1L-12beta, IFN-gamma, TNF-alpha. Moreover, up-regulation of serum IL-6 levels in DSS-treated TC-PTP(+/-) mice confirms that mice with a single copy of the TC-PTP gene display increased susceptibility to systemic inflammation due to bowel epithelial erosion resulting from DSS challenge. Our findings support the lack of modulation of Janus kinases 1 and 3 (Jak1, Jak3), and the downstream signal transducer and activator of transcription 1,3 and 5 (Stat1, Stat3, Stat 5) by PTPN2 in the development of IBD like condition. Pathological and molecular analysis reveal that the deficiency of TC-PTP results in pro-inflammatory condition in the bowel of heterozygous TC-PTP(+/-) mice. These novel findings in TC-PTP hemi-deficiency support the hypothesis that TC-PTP is an important regulator of inflammatory cytokine signaling and that it may be implicated in the pathophysiology of IBD.
Conflict of interest statement
Competing Interests: The authors have declared that no competing interests exist.
Figures
Figure 1. Increased response to DSS treatment in the presence of only one allele of TC-PTP.
A. Increased weight loss of TC-PTP +/− mice during DSS-induced colitis. At 19 days of age mouse body weight was 11–12 g followed by DSS treatment. Body weight of DSS-treated TC-PTP +/− (Het-DSS) (2.58±0.4) mice were significantly lower than, TC-PTP+/− (Het) (5.0±0.8) and TC-PTP+/+ (WT-DSS) (3.78±0.5) mice ***p<0.0002. DSS-treated TC-PTP+/− mice compared to DSS-treated TC-PTP+/+ mice *p<0.001. Data represent the mean of three groups of three animals each (N = 9). B. Ratio of colon weight of DSS-treated TC-PTP +/− (Het-DSS) mice were significantly lower than DSS-treated TC-PTP+/+ (WT-DSS) mice p<0.05. In the case of TC-PTP+/− (Het) vs. DSS-treated TC-PTP+/− (WT-DSS) mice p<0.001, and p<0.001 in comparison of TC-PTP+/+ vs. DSS-treated TC-PTP+/+ mice.
Figure 2. Loss of colorectal crypt-villi.
A. Histopathological features of the mouse colon in association with colitis. Bar = 1000 µm. From top to bottom: TC-PTP+/+(WT), TC-PTP+/− (Het), DSS-treated TC-PTP+/+(WT-DSS) and DSS-treated TC-PTP+/− (Het-DSS). In TC-PTP+/+(WT) crypts are straight and the base of the glands reach the muscularis mucosae. Crypt-villus axes are normal and epithelium layer is intact. In DSS-treated TC-PTP+/− (Het-DSS) mice ingestion of DSS caused crypt destruction, Numerous neutrophils were present in the section (arrows). Loss of the surface epithelial layer is obvious, while changes in crypt-villus axis and colon tissue architecture are observed. B. The number of crypts per field, field is 1000 µm in colorectal section of bowel. The number of crypts in DSS-treated TC-PTP+/− (Het-DSS) mice were significantly lower than DSS-treated TC-PTP+/+ (WT-DSS) mice p<0.002. C. Crypts in field, crypts width, crypts height and epithelial height were quantified. Data represent mean and SD of three groups of three animal each (N = 9).
Figure 3. Blood cell counts and histological analysis of colons.
A. Increase in numbers of lymphocytes p<0.0114 and neutrophils p<0.0001 in DSS-treated TC-PTP +/− mice compared to DSS-treated TC-PTP+/+. B. The mean histology activity scores of colon tissue sections of TC-PTP+/+(WT) (0.3±0.34), TC-PTP+/− (Het) (7±0.55), DSS-treated TC-PTP+/+(WT-DSS) (12±0.48) and DSS-treated TC-PTP+/−(Het-DSS) (32±0.67) mice. Analysis was performed blinded by pathologist on a scale from 0 to 40 (see Methods).
Figure 4. Jak/Stat signaling pathways.
Immunoblotting was used to observe total protein levels and protein phosphorylation levels of JAK1, JAK3, STAT1, STAT3 and STAT5.
Figure 5. Colonic up-regulation of cytokines mRNA expression.
DSS-treated TC-PTP+/−(Het-DSS) mice showed up-regulation of TNFα, IFNγ, IL-12 β, IL-23R and IL-6. Untreated TC-PTP−/− (null) mouse colon mRNA was used as a control.
Figure 6. IL-6 serum level in DSS-treated and control mice.
Serum was collected at the time of euthanasia and analyzed for cytokine levels using Mouse Cytokine Multiplex Assay. A 4.2-fold increase in serum IL-6 concentration in the TC-PTP+/−(Het-DSS) (11.6±7.6 pg/ml) compared to TC-PTP+/+ (WT-DSS) (2.6±2.4 pg/ml) mice (p<0.05).
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