PUMA-mediated intestinal epithelial apoptosis contributes to ulcerative colitis in humans and mice
Wei Qiu, … , Jian Yu, Lin Zhang
Wei Qiu, … , Jian Yu, Lin Zhang
Published April 1, 2011
Citation Information: J Clin Invest. 2011;121(5):1722-1732. https://doi.org/10.1172/JCI42917.
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Research Article Gastroenterology

PUMA-mediated intestinal epithelial apoptosis contributes to ulcerative colitis in humans and mice

Abstract

Intestinal epithelial cell (IEC) apoptosis contributes to the development of ulcerative colitis (UC), an inflammatory bowel disease (IBD) that affects the colon and rectum. Therapies that target the inflammatory cytokine TNF have been found to inhibit IEC apoptosis in patients with IBD, although the mechanism of IEC apoptosis remains unclear. We therefore investigated the role of p53-upregulated modulator of apoptosis (PUMA), a p53 target and proapoptotic BH3-only protein, in colitis and IEC apoptosis, using patient samples and mouse models of UC. In UC patient samples, PUMA expression was elevated in colitis tissues relative to that in uninvolved tissues, and the degree of elevation of PUMA expression correlated with the severity of colitis and the degree of apoptosis induction. In mice, PUMA was markedly induced in colonic epithelial cells following induction of colitis by either dextran sulfate sodium salt (DSS) or 2,4,6-trinitrobenzene sulfonic acid (TNBS). The induction of PUMA was p53-independent but required NF-κB. Absence of PUMA, but neither absence of p53 nor that of another BH3-only protein (Bid), relieved DSS- and TNBS-induced colitis and inhibited IEC apoptosis. Furthermore, treating mice with infliximab (Remicade), a clinically used TNF-specific antibody, suppressed DSS- and TNBS-induced PUMA expression and colitis. These results indicate that PUMA induction contributes to the pathogenesis of colitis by promoting IEC apoptosis and suggest that PUMA inhibition may be an effective strategy to promote mucosal healing in patients with UC.

Authors

Wei Qiu, Bin Wu, Xinwei Wang, Monica E. Buchanan, Miguel D. Regueiro, Douglas J. Hartman, Robert E. Schoen, Jian Yu, Lin Zhang

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Figure 1

Apoptosis and PUMA induction in human UC specimens.

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Apoptosis and PUMA induction in human UC specimens. (A) TUNEL (brown) st...
(A) TUNEL (brown) staining of a matched pair of uninvolved colonic and colitis tissues from a patient with UC (original magnification, ×400). Arrows indicate example TUNEL-positive cells. (B) Active caspase-3 (brown) staining of a matched pair of uninvolved colonic and colitis tissues from a patient with UC (original magnification, ×400). Arrows indicate example active caspase-3–positive cells. (C) TUNEL (green) and cytokeratin (red) double staining of a colitis specimen (referred to as UC1). Arrows indicate example TUNEL and cytokeratin double-positive cells (original magnification, ×200). (D) Western blot analysis of PUMA expression in 3 matched pairs of uninvolved colonic (N) and colitis (C) tissues. Lysate of PUMA-expressing HCT116 colon cancer cells was analyzed as a positive control. The arrow indicates the active form of PUMA, and the asterisk indicates an inactive form of PUMA generated by alternative splicing. (E) PUMA mRNA expression (dark dots) in uninvolved colonic and colitis tissues was analyzed by RNA ISH (original magnification, ×400). Arrows indicate example PUMA-expressing cells. (F) Correlation between PUMA protein expression and severity of colitis in patients with UC (left panel). Correlation between apoptosis induction and severity of colitis in patients with UC (right panel). The tops of the boxes indicate the upper quartiles of the data, and the bottoms of the boxes indicate the lower quartiles of the data. The lines within the boxes indicate the median values. The top and bottom whiskers indicate the maximum values and minimum values, respectively. Values were mean ± SD (n = 7 in each group).