Knockout of the c-Jun N-terminal Kinase 2 aggravates the development of mild chronic dextran sulfate sodium colitis independently of expression of intestinal cytokines TNFα, TGFB1, and IL-6

Figures & data

Figure 1 The disease activity index (DAI) after administration of three cycles of 1.0% dextran sulfate sodium (DSS) or H₂O as the control (means ± SEM).

Notes: (A) After administration of 1.0% DSS, the DAI in WT1 mice was significantly elevated, in comparison with the H₂O control group (P ≤ 0.05). Cyclic administration of DSS in Mapk8−/− animals resulted in mild triphasic colitis, with no significant differences in comparison with the H₂O control group or the WT1 DSS group (statistical evaluation: ANOVA over all time points). (B) After administration of 1.0% DSS in the WT2 animals, the DAI was not significantly elevated, in comparison with the H₂O control group. Cyclic administration of DSS in Mapk9−/− animals resulted in mild triphasic colitis, which was significantly greater, in comparison with the H₂O control group (P ≤ 0.001) and in comparison with the WT2 DSS group (P ≤ 0.05) (statistical evaluation: ANOVA over all time points).

Figure 2 The crypt damage score (CDS) after administration of three cycles of 1.0% dextran sulfate sodium (DSS) or H₂O as the control (means ± SEM).

Notes: The most affected regions were the mid-colon and distal colon. (A) Differences in the CDS in JNK1 knockout (Mapk8−/−) and wild-type controls (WT1) did not reach statistical significance (CDS value comparison: one-way ANOVA; pair comparisons: Tukey’s test). (B) In the DSS-treated Mapk9−/− group, the CDS was significantly elevated, in comparison with the DSS-treated WT2 group (mid-colon, P = 0.034; distal colon, P = 0.047) and with the H₂O control group (mid-colon, P = 0.001; distal colon, P = 0.047) (CDS value comparison: one-way ANOVA; pair comparisons: Tukey’s test).

Figure 3 Hematoxylin–eosin staining of the distal colon.

Notes: (A) Wild-type controls (WT2) treated with H₂O: normal mucosa with a regular crypt architecture. (B) JNK2 knockout mice (Mapk9−/−) treated with H₂O: normal mucosa with a regular crypt architecture. (C) Wild-type controls (WT2) treated with three cycles of 1.0% dextran sulfate sodium (DSS): mild changes in the crypt architecture. (D) JNK2 knockout mice (Mapk9−/−) treated with three cycles of 1.0% DSS: severe changes in the crypt architecture, with ulceration and loss of crypts.

Table 1 Relative mRNA expression (mean ± SEM) for TNFα, TGFB1, and IL-6

	TNFα	TGFB1	IL-6
Mapk8−/− DSS	744 ± 238	574 ± 111	1674 ± 675
WT1 DSS	2048 ± 1356	2319 ± 850	10139 ± 5838
Mapk8−/− H2O	739 ± 268	1920 ± 1197	975 ± 528
WT1 H2O	1244 ± 610	2481 ± 915	2171 ± 622
Mapk9−/− DSS	622 ± 170	1402 ± 310	1516 ± 417
WT2 DSS	624 ± 259	1237 ± 572	1201 ± 477
Mapk9−/− H2O	302 ± 57	574 ± 123	199 ± 74
WT2 H2O	662 ± 293	1706 ± 787	2336 ± 1159

Abbreviations: DSS, dextran sulfate sodium; IL-6, interleukin-6; SEM, standard error of the mean; TGFB1, transforming growth factor β1; TNFα, tumor necrosis factor-α; WT, wild-type.

Figure 4 Immunofluorescence (Cy3-conjugated antibody) of CD8+ cells in the distal colon.

Notes: (A) Wild-type controls (WT2) treated with H₂O. (B) JNK2 knockout mice (Mapk9−/−) treated with H₂O. (C) Wild-type controls (WT2) treated with three cycles of 1.0% dextran sulfate sodium (DSS). (D) JNK2 knockout mice (Mapk9−/−) treated with three cycles of 1.0% DSS.

Figure 5 The labeling density of CD8 and CD4 (cells per high-power field) after administration of three cycles of 1.0% dextran sulfate sodium (DSS) or H₂O as the control.

Notes: (A) After induction of chronic DSS colitis, CD8 staining was significantly higher in Mapk9−/− animals, in comparison with WT2 mice (P = 0.002). CD8 staining was also significantly elevated in Mapk9−/− animals treated with DSS, in comparison with Mapk9−/− animals treated with H₂O (P = 0.023) (statistical evaluation: t-test). (B) There was significantly greater staining in Mapk9−/− animals treated with DSS, in comparison with Mapk9−/− animals treated with H₂O (P = 0.046). In DSS-treated Mapk9−/− animals, CD4 staining was greater, but did not show any significant differences in comparison with DSS-treated WT2 mice (P = 0.071) (statistical evaluation: t-test).