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Warner BW. The Pathogenesis of Resection-Associated Intestinal Adaptation. Cell Mol Gastroenterol Hepatol 2016; 2:429-438. [PMID: 27722191 PMCID: PMC5042605 DOI: 10.1016/j.jcmgh.2016.05.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 05/06/2016] [Indexed: 12/14/2022]
Abstract
After massive small-bowel resection, the remnant bowel compensates by a process termed adaptation. Adaptation is characterized by villus elongation and crypt deepening, which increases the capacity for absorption and digestion per unit length. The mechanisms/mediators of this important response are multiple. The purpose of this review is to highlight the major basic contributions in elucidating a more comprehensive understanding of this process.
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Affiliation(s)
- Brad W. Warner
- Correspondence Address correspondence to: Brad W. Warner, MD, Washington University School of Medicine, St. Louis Children's Hospital, One Children's Place, Suite 5s40, St. Louis, Missouri 63110. fax: (314) 454-2442.Washington University School of MedicineSt. Louis Children's HospitalOne Children's PlaceSuite 5s40St. LouisMissouri 63110
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Abstract
Adaptation is an important compensatory response to environmental cues resulting in enhanced survival. In the gut, the abrupt loss of intestinal length is characterized by increased rates of enterocyte proliferation and apoptosis and culminates in adaptive villus and crypt growth. In the development of an academic pediatric surgical career, adaptation is also an important compensatory response to survive the ever changing research, clinical, and economic environment. The ability to adapt in both situations is critical for patients and a legacy of pediatric surgical contributions to advance our knowledge of multiple conditions and diseases.
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Wakeman D, Guo J, Santos JA, Wandu WS, Schneider JE, McMellen ME, Leinicke JA, Erwin CR, Warner BW. p38 MAPK regulates Bax activity and apoptosis in enterocytes at baseline and after intestinal resection. Am J Physiol Gastrointest Liver Physiol 2012; 302:G997-1005. [PMID: 22383494 PMCID: PMC3362074 DOI: 10.1152/ajpgi.00485.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 02/27/2012] [Indexed: 01/31/2023]
Abstract
Increased apoptosis in crypt enterocytes is a key feature of intestinal adaptation following massive small bowel resection (SBR). Expression of the proapoptotic factor Bax has been shown to be required for resection-induced apoptosis. It has also been demonstrated that p38-α MAPK (p38) is necessary for Bax activation and apoptosis in vitro. The present studies were designed to test the hypothesis that p38 is a key regulator of Bax activation during adaptation after SBR in vivo. Enterocyte expression of p38 was deleted by tamoxifen administration to activate villin-Cre in adult mice with a floxed Mapk14 (p38-α) gene. Proximal 50% SBR or sham operations were performed on wild-type (WT) and p38 intestinal knockout (p38-IKO) mice under isoflurane anesthesia. Mice were killed 3 or 7 days after operation, and adaptation was analyzed by measuring intestinal morphology, proliferation, and apoptosis. Bax activity was quantified by immunoprecipitation, followed by Western blotting. After SBR, p38-IKO mice had deeper crypts, longer villi, and accelerated proliferation compared with WT controls. Rates of crypt apoptosis were significantly lower in p38-IKO mice, both at baseline and after SBR. Levels of activated Bax were twofold higher in WT mice after SBR relative to sham. In contrast, activated Bax levels were reduced by 67% in mice after p38 MAPK deletion. Deleted p38 expression within the intestinal epithelium leads to enhanced adaptation and reduced levels of enterocyte apoptosis after massive intestinal resection. p38-regulated Bax activation appears to be an important mechanism underlying resection-induced apoptosis.
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Affiliation(s)
- Derek Wakeman
- Department of Surgery, Division of Pediatric Surgery, St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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McMellen ME, Wakeman D, Longshore SW, McDuffie LA, Warner BW. Growth factors: possible roles for clinical management of the short bowel syndrome. Semin Pediatr Surg 2010; 19:35-43. [PMID: 20123272 PMCID: PMC2891767 DOI: 10.1053/j.sempedsurg.2009.11.010] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The structural and functional changes during intestinal adaptation are necessary to compensate for the sudden loss of digestive and absorptive capacity after massive intestinal resection. When the adaptive response is inadequate, short bowel syndrome (SBS) ensues and patients are left with the requirement for parenteral nutrition and its associated morbidities. Several hormones have been studied as potential enhancers of the adaptation process. The effects of growth hormone, insulin-like growth factor-1, epidermal growth factor, and glucagon-like peptide 2 on adaptation have been studied extensively in animal models. In addition, growth hormone and glucagon-like peptide 2 have shown promise for the treatment of SBS in clinical trials in human beings. Several lesser studied hormones, including leptin, corticosteroids, thyroxine, testosterone, and estradiol, are also discussed.
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Affiliation(s)
- Mark E. McMellen
- Division of Pediatric Surgery, St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, MO, USA
| | - Derek Wakeman
- Division of Pediatric Surgery, St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, MO, USA
| | - Shannon W. Longshore
- Department of Surgery, University of California, Davis Medical Center, Sacramento, CA, USA
| | - Lucas A. McDuffie
- School of Medicine, Eastern Virginia Medical School, Norfolk, VA, USA
| | - Brad W. Warner
- Division of Pediatric Surgery, St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, MO, USA,Correspondence: Brad W. Warner, MD Division of Pediatric Surgery St. Louis Children's Hospital, One Children's Place Suite 5S40, St. Louis, MO 63110 Tel.: 1 314 454 6022 Fax: 1 314 454 2442
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Koga H, Yang H, Haxhija EQ, Teitelbaum DH. The role of Angiotensin II type 1a receptor on intestinal epithelial cells following small bowel resection in a mouse model. Pediatr Surg Int 2008; 24:1279-86. [PMID: 18989682 PMCID: PMC2814528 DOI: 10.1007/s00383-008-2277-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AIM We have previously shown that inhibition of angiotensin converting enzyme (ACE) significantly reduced intestinal epithelial cell (EC) apoptosis and improved morphometric intestinal adaptation in a mouse model of massive small-bowel resection (SBR). This study attempted to further examine the downstream signaling factors in this system by blocking the action of angiotensin II (ATII), hypothesizing that this would lead to similar improvement of intestinal adaptation after SBR. METHOD Two groups of mice (C57BL/6J) underwent either a 60% mid-intestinal resection (SBR group) or a transection/re-anastomosis (Sham group). Because real-time PCR studies showed that only ATII receptor type 1a (ATII-1a) expression was significantly increased after SBR, compared to SHAM mice, we decided to use the specific ATII-1a receptor antagonist Losartan to block this signaling pathway. An additional two groups of mice received daily i.p. injections of Losartan (SBR + Losartan and Sham + Losartan group). At 7 days, the adaptive response was assessed in the remnant gut including villus height, crypt depth, EC apoptosis (TUNEL staining) and proliferation (BrdU incorporation). The apoptotic and proliferation signaling pathways were addressed by analysis of EC mRNA expression. RESULT SBR (with and without Losartan) led to a significant increase in villus height and crypt depth. Losartan treatment did not significantly change EC proliferation, but did significantly reduce EC apoptosis rates as compared to the non-treated SBR group. Losartan treatment was associated with a significant reduction of the bax-to-bcl-2 ratio and TNF-alpha expression after SBR compared to non-treated groups. Interestingly, Losartan-treated groups showed a tremendous increase in proliferation of signaling factors EGFR, KGFR and IL7R, which may indicate an expanded potential for further intestinal adaptation also beyond 7 days after SBR. CONCLUSION This study showed that the ATII-1a receptor may be of crucial importance for the modulation of intestinal EC apoptosis, and for regulating the post-resectional EC adaptive response.
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Affiliation(s)
- Hiroyuki Koga
- Section of Pediatric Surgery, Department of Surgery, C.S Mott Children's Hospital F3970, University of Michigan Medical School, Ann Arbor, MI 48109-0245, USA
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Haxhija EQ, Yang H, Spencer AU, Koga H, Sun X, Teitelbaum DH. Modulation of mouse intestinal epithelial cell turnover in the absence of angiotensin converting enzyme. Am J Physiol Gastrointest Liver Physiol 2008; 295:G88-G98. [PMID: 18483182 PMCID: PMC2494725 DOI: 10.1152/ajpgi.00589.2007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Angiotensin converting enzyme (ACE) has been shown to be involved in regulation of apoptosis in nonintestinal tissues. This study examined the role of ACE in the modulation of intestinal adaptation utilizing ACE knockout mice (ACE-/-). A 60% small bowel resection (SBR) was used, since this model results in a significant increase in intestinal epithelial cell (EC) apoptosis as well as proliferation. Baseline villus height, crypt depth, and intestinal EC proliferation were higher, and EC apoptosis rates were lower in ACE-/- compared with ACE+/+ mice. After SBR, EC apoptosis rates remained significantly lower in ACE-/- compared with ACE+/+ mice. Furthermore, villus height and crypt depth after SBR continued to be higher in ACE-/- mice. The finding of a lower bax-to-bcl-2 protein ratio in ACE-/- mice may account for reduced EC apoptotic rates after SBR in ACE-/- compared with ACE+/+ mice. The baseline higher rate of EC proliferation in ACE-/- compared with ACE+/+ mice may be due to an increase in the expression of several EC growth factor receptors. In conclusion, ACE appears to have an important role in the modulation of intestinal EC apoptosis and proliferation and suggests that the presence of ACE in the intestinal epithelium has a critical role in guiding epithelial cell adaptive response.
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Affiliation(s)
- Emir Q. Haxhija
- Section of Pediatric Surgery, Department of Surgery, University of Michigan Medical School, and C. S. Mott Children's Hospital, Ann Arbor, Michigan; and Department of Pediatric Surgery, Medical University Graz, Graz, Austria
| | - Hua Yang
- Section of Pediatric Surgery, Department of Surgery, University of Michigan Medical School, and C. S. Mott Children's Hospital, Ann Arbor, Michigan; and Department of Pediatric Surgery, Medical University Graz, Graz, Austria
| | - Ariel U. Spencer
- Section of Pediatric Surgery, Department of Surgery, University of Michigan Medical School, and C. S. Mott Children's Hospital, Ann Arbor, Michigan; and Department of Pediatric Surgery, Medical University Graz, Graz, Austria
| | - Hiroyuki Koga
- Section of Pediatric Surgery, Department of Surgery, University of Michigan Medical School, and C. S. Mott Children's Hospital, Ann Arbor, Michigan; and Department of Pediatric Surgery, Medical University Graz, Graz, Austria
| | - Xiaoyi Sun
- Section of Pediatric Surgery, Department of Surgery, University of Michigan Medical School, and C. S. Mott Children's Hospital, Ann Arbor, Michigan; and Department of Pediatric Surgery, Medical University Graz, Graz, Austria
| | - Daniel H. Teitelbaum
- Section of Pediatric Surgery, Department of Surgery, University of Michigan Medical School, and C. S. Mott Children's Hospital, Ann Arbor, Michigan; and Department of Pediatric Surgery, Medical University Graz, Graz, Austria
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Sheng G, Guo J, Warner BW. Epidermal growth factor receptor signaling modulates apoptosis via p38alpha MAPK-dependent activation of Bax in intestinal epithelial cells. Am J Physiol Gastrointest Liver Physiol 2007; 293:G599-606. [PMID: 17615176 DOI: 10.1152/ajpgi.00182.2007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Previous studies have demonstrated that the proapoptotic protein Bax plays an important role in the elevated enterocyte apoptosis that occurs during the intestinal adaptation response to massive small bowel resection (SBR). Additionally, epidermal growth factor receptor (EGFR) activation prevents SBR-induced enterocyte apoptosis. The present study aims to delineate the relationship between EGFR activity and intestinal epithelial cell apoptosis. Treatment of model intestinal epithelial cells (RIEC-18) with both a selective EGFR inhibitor (ZD1839) and EGFR small interfering RNA knockdown resulted in a dramatic increase in apoptosis, accompanied by rapid phosphorylation of p38alpha. Concurrently, Bax underwent conformational changes consistent with activation and translocated to mitochondria. In contrast, EGF stimulation enhanced cell survival by attenuating p38alpha phosphorylation, Bax conformational change, mitochondrial trafficking, and apoptosis. These results demonstrate that that diminished EGFR activity initiates the intrinsic pathway of apoptosis through p38alpha-dependent Bax activation in intestinal epithelial cells. These finding provide mechanistic insight into the role that EGFR signaling plays in the regulation of enterocyte apoptosis following massive intestinal loss.
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Affiliation(s)
- George Sheng
- Division of Pediatric Surgery, St. Louis Children's Hospital, One Children's Place, St. Louis, MO 63110, USA
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Haxhija EQ, Yang H, Spencer AU, Sun X, Teitelbaum DH. Intestinal epithelial cell proliferation is dependent on the site of massive small bowel resection. Pediatr Surg Int 2007; 23:379-90. [PMID: 17205293 DOI: 10.1007/s00383-006-1855-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Early intestinal adaptation after massive small bowel resection (SBR) is driven by increased epithelial cell (EC) proliferation. There is a clear clinical difference in the post-operative course of patients after the loss of proximal (P) compared to distal (D) small bowel. This study examined the effects of the site of SBR on post-resectional intestinal adaptation, and investigated the potential mechanisms involved. C57BL/6J mice (n = 7/group) underwent: (1) 60% P-SBR, (2) 60% D-SBR, (3) 60% mid (M)-SBR and (4) SHAM-operation (transection/reanastomosis). Mice were sacrificed at 7 days after surgery and ECs and adjacent mucosal lymphocytes (IELs) isolated. Adaptation was assessed in both jejunum and ileum by quantification of villus height, crypt depth, villus cell size, crypt cell size (microns), goblet cell number, and EC proliferation (%BrdU incorporation). Proliferation signalling pathways including keratinocyte growth factor (KGF)/KGFR(1), IL-7/IL-7R, and epidermal growth factor receptor (EGFR) were measured by RT-PCR. Expression of IL-7 was further analysed by immunofluorescence. Data were analyzed using ANOVA. All three SBR models led to significant increases in villus height, crypt depth, goblet cell numbers and EC proliferation rate when compared to respective SHAM groups. The strongest morphometric changes were found for jejunal segments after M-SBR and for ileal segments after P-SBR. Furthermore, morphometric analysis showed that at 1-week post-resection a tremendous increase in EC numbers occurred in jejunal villi (cell hyperplasia), whereas a significant increase in EC size predominated in ileal villi (cell hypertrophy). mRNA expression of KGF, KGFR(1), IL-7R, and EGFR showed a significant increase only after D-SBR, whereas IL-7 increased significantly after SBR in all investigated models, and this was confirmed by immunofluorescence studies. Early intestinal adaptation shows distinct differences depending on the site of SBR, and is predominately driven by cell hyperplasia in jejunal villi and cell hypertrophy in ileal villi. However, the exact mechanisms, which guide these signalling pathways are still unclear.
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Affiliation(s)
- Emir Q Haxhija
- Department of Pediatric Surgery, Medical University Graz, Graz, Austria
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