Loss of ADAM17-Mediated Tumor Necrosis Factor Alpha Signaling in Intestinal Cells Attenuates Mucosal Atrophy in a Mouse Model of Parenteral Nutrition

Fn14 and TNFR2 as regulators of cytotoxic TNFR1 signaling

Tumor necrosis factor (TNF) receptor 1 (TNFR1), TNFR2 and fibroblast growth factor-inducible 14 (Fn14) belong to the TNF receptor superfamily (TNFRSF). From a structural point of view, TNFR1 is a prototypic death domain (DD)-containing receptor. In contrast to other prominent death receptors, such as CD95/Fas and the two TRAIL death receptors DR4 and DR5, however, liganded TNFR1 does not instruct the formation of a plasma membrane-associated death inducing signaling complex converting procaspase-8 into highly active mature heterotetrameric caspase-8 molecules. Instead, liganded TNFR1 recruits the DD-containing cytoplasmic signaling proteins TRADD and RIPK1 and empowers these proteins to trigger cell death signaling by cytosolic complexes after their release from the TNFR1 signaling complex. The activity and quality (apoptosis versus necroptosis) of TNF-induced cell death signaling is controlled by caspase-8, the caspase-8 regulatory FLIP proteins, TRAF2, RIPK1 and the RIPK1-ubiquitinating E3 ligases cIAP1 and cIAP2. TNFR2 and Fn14 efficiently recruit TRAF2 along with the TRAF2 binding partners cIAP1 and cIAP2 and can thereby limit the availability of these molecules for other TRAF2/cIAP1/2-utilizing proteins including TNFR1. Accordingly, at the cellular level engagement of TNFR2 or Fn14 inhibits TNFR1-induced RIPK1-mediated effects reaching from activation of the classical NFκB pathway to induction of apoptosis and necroptosis. In this review, we summarize the effects of TNFR2- and Fn14-mediated depletion of TRAF2 and the cIAP1/2 on TNFR1 signaling at the molecular level and discuss the consequences this has in vivo.

Investigating the Crime Scene-Molecular Signatures in Inflammatory Bowel Disease

Inflammatory bowel diseases (IBD) are without cure and troublesome to manage because of the considerable diversity between patients and the lack of reliable biomarkers. Several studies have demonstrated that diet, gut microbiota, genetics and other patient factors are essential for disease occurrence and progression. Understanding the link between these factors is crucial for identifying molecular signatures that identify biomarkers to advance the management of IBD. Recent technological breakthroughs and data integration have fuelled the intensity of this research. This research demonstrates that the effect of diet depends on patient factors and gut microbial activity. It also identifies a range of potential biomarkers for IBD management, including mucosa-derived cytokines, gasdermins and neutrophil extracellular traps, all of which need further evaluation before clinical translation. This review provides an update on cutting-edge research in IBD that aims to improve disease management and patient quality of life.

Inflammatory activation of surface molecule shedding by upregulation of the pseudoprotease iRhom2 in colon epithelial cells

The metalloproteinase ADAM17 contributes to inflammatory and proliferative responses by shedding of cell-surface molecules. By this ADAM17 is implicated in inflammation, regeneration, and permeability regulation of epithelial cells in the colon. ADAM17 maturation and surface expression requires the adapter proteins iRhom1 or iRhom2. Here we report that expression of iRhom2 but not iRhom1 is upregulated in intestinal tissue of mice with acute colitis. Our analysis of public databases indicates elevated iRhom2 expression in mucosal tissue and epithelial cells from patients with inflammatory bowel disease (IBD). Consistently, expression of iRhom2 but not iRhom1 is upregulated in colon or intestinal epithelial cell lines after co-stimulation with tumor necrosis factor (TNF) and interferon gamma (IFNgamma). This upregulation can be reduced by inhibition of Janus kinases or transcription factors NF-kappaB or AP-1. Upregulation of iRhom2 can be mimicked by iRhom2 overexpression and is associated with enhanced maturation and surface expression of ADAM17 which then results in increased cleavage of transforming growth factor (TGF) alpha and junctional adhesion molecule (JAM)-A. Finally, the induction of these responses is suppressed by inhibition of iRhom2 transcription. Thus, inflammatory induction of iRhom2 may contribute to upregulated ADAM17-dependent mediator and adhesion molecule release in IBD. The development of iRhom2-dependent inhibitors may allow selective targeting of inflammatory ADAM17 activities.

NRG4-ErbB4 signaling represses proinflammatory macrophage activity

Proinflammatory macrophages are essential drivers of colitis and express the growth factor receptor ErbB4. This study tested the role of ErbB4 and its specific ligand, NRG4, in regulating macrophage function. We show that endogenous NRG4-ErbB4 signaling limits macrophage production of proinflammatory cytokines in vitro and limits colitis severity in vivo and thus is a potential target for therapeutic intervention.

Advances in Understanding TKS4 and TKS5: Molecular Scaffolds Regulating Cellular Processes from Podosome and Invadopodium Formation to Differentiation and Tissue Homeostasis

Scaffold proteins are typically thought of as multi-domain "bridging molecules." They serve as crucial regulators of key signaling events by simultaneously binding multiple participants involved in specific signaling pathways. In the case of epidermal growth factor (EGF)-epidermal growth factor receptor (EGFR) binding, the activated EGFR contacts cytosolic SRC tyrosine-kinase, which then becomes activated. This process leads to the phosphorylation of SRC-substrates, including the tyrosine kinase substrates (TKS) scaffold proteins. The TKS proteins serve as a platform for the recruitment of key players in EGFR signal transduction, promoting cell spreading and migration. The TKS4 and the TKS5 scaffold proteins are tyrosine kinase substrates with four or five SH3 domains, respectively. Their structural features allow them to recruit and bind a variety of signaling proteins and to anchor them to the cytoplasmic surface of the cell membrane. Until recently, TKS4 and TKS5 had been recognized for their involvement in cellular motility, reactive oxygen species-dependent processes, and embryonic development, among others. However, a number of novel functions have been discovered for these molecules in recent years. In this review, we attempt to cover the diverse nature of the TKS molecules by discussing their structure, regulation by SRC kinase, relevant signaling pathways, and interaction partners, as well as their involvement in cellular processes, including migration, invasion, differentiation, and adipose tissue and bone homeostasis. We also describe related pathologies and the established mouse models.

Necroptosis, ADAM proteases and intestinal (dys)function

Recently, an unexpected connection between necroptosis and members of the a disintegrin and metalloproteinase (ADAM) protease family has been reported. Necroptosis represents an important cell death routine which helps to protect from viral, bacterial, fungal and parasitic infections, maintains adult T cell homeostasis and contributes to the elimination of potentially defective organisms before parturition. Equally important for organismal homeostasis, ADAM proteases control cellular processes such as development and differentiation, immune responses or tissue regeneration. Notably, necroptosis as well as ADAM proteases have been implicated in the control of inflammatory responses in the intestine. In this review, we therefore provide an overview of the physiology and pathophysiology of necroptosis, ADAM proteases and intestinal (dys)function, discuss the contribution of necroptosis and ADAMs to intestinal (dys)function, and review the current knowledge on the role of ADAMs in necroptotic signaling.

Inactive Rhomboid Protein 2 Mediates Intestinal Inflammation by Releasing Tumor Necrosis Factor-α

BACKGROUND

Tumor necrosis factor (TNF)-α is a major proinflammatory cytokine that plays a key role in inflammatory bowel disease (IBD). Inactive rhomboid protein 2 (iRhom2) is essential for activating TNF-α-converting enzyme (TACE) in immune cells, which regulates TNF-α release. The aim of the study was to investigate the role of iRhom2 in intestinal inflammation in IBD.

METHODS

The expression of iRhom2 and TACE in lipopolysaccharide (LPS)-stimulated COLO 205 and RAW 264.7 cells was assessed by reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. The expression of iRhom2 and TACE in the colonic tissue of IBD patients and 2,4,6-trinitrobenzenesulfonic acid solution (TNBS)-treated mice was determined by RT-PCR and immunohistochemistry. To assess the role of iRhom2 in intestinal inflammation, colitis was induced in wild-type and iRhom2-/- mice by the administration of TNBS enema.

RESULTS

In LPS-stimulated COLO 205 and RAW 264.7 cells, the mRNA and protein levels of TACE and iRhom2 were upregulated. The expression of TACE and iRhom2 in the colon of the IBD patients and TNBS-treated mice was significantly enhanced. The inflammatory cells that expressed high levels of iRhom2 in the colon were identified as macrophages. Finally, iRhom2 deficiency ameliorated TNBS-induced colitis by inhibiting TNF-α release.

CONCLUSIONS

iRhom2 has an important role in intestinal inflammation through TNF-α secretion in immune cells, which suggests that iRhom2 could be a novel therapeutic target for IBD.

Deletion of iRhom2 protects against diet-induced obesity by increasing thermogenesis

Objective

Obesity is the result of positive energy balance. It can be caused by excessive energy consumption but also by decreased energy dissipation, which occurs under several conditions including when the development or activation of brown adipose tissue (BAT) is impaired. Here we evaluated whether iRhom2, the essential cofactor for the Tumour Necrosis Factor (TNF) sheddase ADAM17/TACE, plays a role in the pathophysiology of metabolic syndrome.

Methods

We challenged WT versus iRhom2 KO mice to positive energy balance by chronic exposure to a high fat diet and then compared their metabolic phenotypes. We also carried out ex vivo assays with primary and immortalized mouse brown adipocytes to establish the autonomy of the effect of loss of iRhom2 on thermogenesis and respiration.

Results

Deletion of iRhom2 protected mice from weight gain, dyslipidemia, adipose tissue inflammation, and hepatic steatosis and improved insulin sensitivity when challenged by a high fat diet. Crucially, the loss of iRhom2 promotes thermogenesis via BAT activation and beige adipocyte recruitment, enabling iRhom2 KO mice to dissipate excess energy more efficiently than WT animals. This effect on enhanced thermogenesis is cell-autonomous in brown adipocytes as iRhom2 KOs exhibit elevated UCP1 levels and increased mitochondrial proton leak.

Conclusion

Our data suggest that iRhom2 is a negative regulator of thermogenesis and plays a role in the control of adipose tissue homeostasis during metabolic disease.

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Deletion of iRhom2 protects mice from metabolic syndrome.

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In obesity, iRhom2 deletion increases energy expenditure, thermogenesis and white adipose tissue beiging.

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iRhom2 deletion enhances thermogenesis in naïve brown adipocytes.

Loss of PACS-2 delays regeneration in DSS-induced colitis but does not affect the ApcMin model of colorectal cancer

PACS-2 is a multifunctional sorting protein that mediates cell homeostasis. We recently identified PACS-2 in a functional genome-wide siRNA screen for novel regulators of the metalloproteinase ADAM17, the main sheddase for ligands of the ErbB receptor family. Of note, we showed that Pacs2^-/- mice have significantly reduced EGFR activity and proliferative index in the intestinal epithelium. As EGFR signaling is highly mitogenic for intestinal epithelial stem cells, and plays essential roles in intestinal epithelial regeneration and tumor development, we have now examined the role of PACS-2 in these processes. Specifically, we analyzed the role of Pacs2-deficiency in a DSS-induced colitis model as well as in the genetic Apc^Min colon cancer model. We now report that loss of PACS-2 delays tissue regeneration after colonic injury with little effect on key inflammatory parameters. We did however not observe any apparent effects on tumor formation driven by excessive proliferative signaling downstream from APC-deficiency. Our findings reveal that the role of PACS-2 in regulating ADAM17-mediated shedding is not an obligate requirement for the epithelium to respond to the strong inflammatory or tumorigenic inducers in the models assessed here.

Mucus Detachment by Host Metalloprotease Meprin β Requires Shedding of Its Inactive Pro-form, which Is Abrogated by the Pathogenic Protease RgpB

The host metalloprotease meprin β is required for mucin 2 (MUC2) cleavage, which drives intestinal mucus detachment and prevents bacterial overgrowth. To gain access to the cleavage site in MUC2, meprin β must be proteolytically shed from epithelial cells. Hence, regulation of meprin β shedding and activation is important for physiological and pathophysiological conditions. Here, we demonstrate that meprin β activation and shedding are mutually exclusive events. Employing ex vivo small intestinal organoid and cell culture experiments, we found that ADAM-mediated shedding is restricted to the inactive pro-form of meprin β and is completely inhibited upon its conversion to the active form at the cell surface. This strict regulation of meprin β activity can be overridden by pathogens, as demonstrated for the bacterial protease Arg-gingipain (RgpB). This secreted cysteine protease potently converts membrane-bound meprin β into its active form, impairing meprin β shedding and its function as a mucus-detaching protease.

Role of ADAM10 in intestinal crypt homeostasis and tumorigenesis

A disintegrin and metalloproteinases (ADAMs) are a family of mSultidomain, membrane-anchored proteases that regulate diverse cellular functions, including cell adhesion, migration, proteolysis and other cell signaling events. Catalytically-active ADAMs act as ectodomain sheddases that proteolytically cleave type I and type II transmembrane proteins and some GPI-anchored proteins from the cellular surface. ADAMs can also modulate other cellular signaling events through a process known as regulated intramembrane proteolysis (RIP). Through their proteolytic activity, ADAMs can rapidly modulate key cell signaling pathways in response to changes in the extracellular environment (e.g. inflammation) and play a central role in coordinating intercellular communication. Dysregulation of these processes through aberrant expression, or sustained ADAM activity, is linked to chronic inflammation, inflammation-associated cancer and tumorigenesis. ADAM10 was the first disintegrin-metalloproteinase demonstrated to have proteolytic activity and is the prototypic ADAM associated with RIP activity (e.g. sequential Notch receptor processing). ADAM10 is abundantly expressed throughout the gastrointestinal tract and during normal intestinal homeostasis ADAM10 regulates many cellular processes associated with intestinal development, cell fate specification and maintenance of intestinal stem cell/progenitor populations. In addition, several signaling pathways that undergo ectodomain shedding by ADAM10 (e.g. Notch, EGFR/ErbB, IL-6/sIL-6R) help control intestinal injury/regenerative responses and may drive intestinal inflammation and colon cancer initiation and progression. Here, I review some of the proposed functions of ADAM10 associated with intestinal crypt homeostasis and tumorigenesis within the gastrointestinal tract in vivo. This article is part of a Special Issue entitled: Proteolysis as a Regulatory Event in Pathophysiology edited by Stefan Rose-John.

ErbB4 signaling stimulates pro-inflammatory macrophage apoptosis and limits colonic inflammation

Efficient clearance of pro-inflammatory macrophages from tissues after resolution of a challenge is critical to prevent prolonged inflammation. Defects in clearance can contribute to conditions such as inflammatory bowel disease, and thus may be therapeutically targetable. However, the signaling pathways that induce termination of pro-inflammatory macrophages are incompletely defined. We tested whether the ErbB4 receptor tyrosine kinase, previously not known to have role in macrophage biology, is involved in this process. In vitro, pro-inflammatory activation of cultured murine and human macrophages induced ErbB4 expression; in contrast, other ErbB family members were not induced in pro-inflammatory cells, and other innate immune lineages (dendritic cells, neutrophils) did not express detectable ErbB4 levels. Treatment of activated pro-inflammatory macrophages with the ErbB4 ligand neuregulin-4 (NRG4) induced apoptosis. ErbB4 localized to the mitochondria in these cells. Apoptosis was accompanied by loss of mitochondrial membrane potential, and was dependent upon the proteases that generate the cleaved ErbB4 intracellular domain fragment, suggesting a requirement for this fragment and mitochondrial pathway apoptosis. In vivo, ErbB4 was highly expressed on pro-inflammatory macrophages but not neutrophils during experimental DSS colitis in C57Bl/6 mice. Active inflammation in this model suppressed NRG4 expression, which may allow for macrophage persistence and ongoing inflammation. Consistent with this notion, NRG4 levels rebounded during the recovery phase, and administration of exogenous NRG4 during colitis reduced colonic macrophage numbers and ameliorated inflammation. These data define a novel role for ErbB4 in macrophage apoptosis, and outline a mechanism of feedback inhibition that may promote resolution of colitis.

Interdependency of EGF and GLP-2 Signaling in Attenuating Mucosal Atrophy in a Mouse Model of Parenteral Nutrition

BACKGROUND & AIMS

Total parenteral nutrition (TPN), a crucial treatment for patients who cannot receive enteral nutrition, is associated with mucosal atrophy, barrier dysfunction, and infectious complications. Glucagon-like peptide-2 (GLP-2) and epidermal growth factor (EGF) improve intestinal epithelial cell (IEC) responses and attenuate mucosal atrophy in several TPN models. However, it remains unclear whether these 2 factors use distinct or overlapping signaling pathways to improve IEC responses. We investigated the interaction of GLP-2 and EGF signaling in a mouse TPN model and in patients deprived of enteral nutrition.

METHODS

Adult C57BL/6J, IEC-Egfr^{knock out (KO)} and IEC-pik3r1^KO mice receiving TPN or enteral nutrition were treated with EGF or GLP-2 alone or in combination with reciprocal receptor inhibitors, GLP-2(3-33) or gefitinib. Jejunum was collected and mucosal atrophy and IEC responses were assessed by histologic, gene, and protein expression analyses. In patients undergoing planned looped ileostomies, fed and unfed ileum was analyzed.

RESULTS

Enteral nutrient deprivation reduced endogenous EGF and GLP-2 signaling in mice and human beings. In the mouse TPN model, exogenous EGF or GLP-2 attenuated mucosal atrophy and restored IEC proliferation. The beneficial effects of EGF and GLP-2 were decreased upon Gefitinib treatment and in TPN-treated IEC-Egfr^KO mice, showing epidermal growth factor-receptor dependency for these IEC responses. By contrast, in TPN-treated IEC-pi3kr1^KO mice, the beneficial actions of EGF were lost, although GLP-2 still attenuated mucosal atrophy.

CONCLUSIONS

Upon enteral nutrient deprivation, exogenous GLP-2 and EGF show strong interdependency for improving IEC responses. Understanding the differential requirements for phosphatidylinositol 3-kinase/phosphoAKT (Ser473) signaling may help improve future therapies to prevent mucosal atrophy.

ADAM17 is a Tumor Promoter and Therapeutic Target in Western Diet-associated Colon Cancer

PURPOSE

Epidermal growth factor receptors (EGFR) are required for tumor promotion by Western diet. The metalloprotease, ADAM17 activates EGFR by releasing pro-EGFR ligands. ADAM17 is regulated by G-protein-coupled receptors, including CXCR4. Here we investigated CXCR4-ADAM17 crosstalk and examined the role of ADAM17 in tumorigenesis.

EXPERIMENTAL DESIGN

We used CXCR4 inhibitor, AMD3100 and ADAM17 inhibitor, BMS566394 to assess CXCR4-ADAM17 crosstalk in colon cancer cells. We compared the expression of CXCR4 ligand, CXCL2, and ADAM17 in mice fed Western diet versus standard diet. Separately, mice were treated with marimastat, a broad-spectrum ADAM17 inhibitor, or AMD3100 to assess EGFR activation by ADAM17 and CXCR4. Using Apc-mutant Min mice, we investigated the effects of ADAM17/10 inhibitor INCB3619 on tumorigenesis. To assess the effects of colonocyte ADAM17, mice with ADAM17 conditional deletion were treated with azoxymethane (AOM). ADAM17 expression was also compared in colonocytes from primary human colon cancers and adjacent mucosa.

RESULTS

CXCL12 treatment activated colon cancer cell EGFR signals, and CXCR4 or ADAM17 blockade reduced this activation. In vivo, Western diet increased CXCL12 in stromal cells and TGFα in colonocytes. Marimastat or AMD3100 caused >50% reduction in EGFR signals (P < 0.05). In Min mice, INCB3619 reduced EGFR signals in adenomas and inhibited intestinal tumor multiplicity (P < 0.05). In the AOM model, colonocyte ADAM17 deletion reduced EGFR signals and colonic tumor development (P < 0.05). Finally, ADAM17 was upregulated >2.5-fold in human malignant colonocytes.

CONCLUSIONS

ADAM17 is a Western diet-inducible enzyme activated by CXCL12-CXCR4 signaling, suggesting the pathway: Western diet→CXCL12→CXCR4→ADAM17→TGFα→EGFR. ADAM17 might serve as a druggable target in chemoprevention strategies. Clin Cancer Res; 23(2); 549-61. ©2016 AACR.

Considerations on inhibition approaches for proinflammatory functions of ADAM proteases

Proteases of the disintegrin and metalloproteinase (ADAM) family mediate the proteolytic shedding of various surface molecules including cytokine precursors, adhesion molecules, growth factors, and receptors. Within the vasculature ADAM10 and ADAM17 regulate endothelial permeability, transendothelial leukocyte migration, and the adhesion of leukocytes and platelets. In vivo studies show that both proteases are implicated in several inflammatory pathologies, for example, edema formation, leukocyte infiltration, and thrombosis. However, both proteases also contribute to developmental and regenerative processes. Thus, although ADAMs can be regarded as valuable drug targets in many aspects, the danger of severe side effects is clearly visible. To circumvent these side effects, traditional inhibition approaches have to be improved to target ADAMs at the right time in the right place. Moreover, the inhibitors need to be more selective for the target protease and if possible also for the substrate. Antibodies recognizing the active conformation of ADAMs or small molecules blocking exosites of ADAM proteases may represent inhibitors with the desired selectivities.

Homeostasis alteration within small intestinal mucosa after acute enteral refeeding in total parenteral nutrition mouse model

Feeding strategies to care for patients who transition from enteral nutrient deprivation while on total parenteral nutrition (TPN) to enteral feedings generally proceed to full enteral nutrition once the gastrointestinal tract recovers; however, an increasing body of literature suggests that a subgroup of patients may actually develop an increased incidence of adverse events, including death. To examine this further, we studied the effects of acute refeeding in a mouse model of TPN. Interestingly, refeeding led to some beneficial effects, including prevention in the decline in intestinal epithelial cell (IEC) proliferation. However, refeeding led to a significant increase in mucosal expression of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), as well as an upregulation in Toll-like receptor 4 (TLR-4). Refeeding also failed to prevent TPN-associated increases in IEC apoptosis, loss of epithelial barrier function, and failure of the leucine-rich repeat-containing G protein-coupled receptor 5-positive stem cell expression. Transitioning from TPN to enteral feedings led to a partial restoration of the small bowel microbial population. In conclusion, while acute refeeding led to some restoration of normal gastrointestinal physiology, enteral refeeding led to a significant increase in mucosal inflammatory markers and may suggest alternative strategies to enteral refeeding should be considered.

Epithelial Cell-Derived a Disintegrin and Metalloproteinase-17 Confers Resistance to Colonic Inflammation Through EGFR Activation

Epithelial regeneration is a key process for the recovery from ulcerative colitis (UC). Here we demonstrate that a disintegrin and metalloproteinase-17 (ADAM17), a main sheddase for tumor necrosis factor (TNF)-α, is essential for defensive epithelial properties against UC by promoting epithelial cell growth and goblet cell differentiation in mouse and human. Mice with systemic deletion of Adam17 developed severe dextran sulfate sodium-induced colitis when compared to mice with myeloid cell Adam17 deletion or control littermates. ADAM17 was predominantly expressed by regenerating epithelia in control mice, and its loss or inhibition attenuated epidermal growth factor receptor (EGFR) activation, epithelial proliferation, mucus production and barrier functions. Conversely, ectopic EGFR stimulation promoted epithelial regeneration thereby partially rescuing the severe colitis caused by ADAM17 deficiency. In UC patients, epithelial ADAM17 expression positively correlated with both cell proliferation and goblet cell number. These findings suggest that maintaining ADAM17–EGFR epithelial signaling is necessary for the recovery from UC and would be beneficial to therapeutic strategies targeting ADAM17-mediated TNF-α shedding.

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Mice with systemic deletion of ADAM17, but not with its myeloid cell-specific deficiency, are more sensitive to colitis.

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ADAM17-EGFR axis promotes repair processes through epithelial cell proliferation and goblet cell differentiation.

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Epithelial ADAM17 expression correlates with cell growth and mucus production in ulcerative colitis patients.

Epithelial regeneration is a key process for the recovery from ulcerative colitis (UC). We now demonstrate that a disintegrin and metalloproteinase-17 (ADAM17) is essential for defensive epithelial properties against UC by driving repair processes in mouse and human. During colonic inflammation, ADAM17 is up-regulated in regenerating epithelia, and its loss or inhibition attenuated epidermal growth factor receptor (EGFR) activation, epithelial proliferation, mucus production and barrier functions. These findings suggest that maintaining ADAM17–EGFR epithelial signaling is necessary for the recovery from UC and would be beneficial to therapeutic strategies targeting ADAM17-mediated tumor necrosis factor-α shedding.

ADAM Proteases and Gastrointestinal Function

A disintegrin and metalloproteinases (ADAMs) are a family of cell surface proteases that regulate diverse cellular functions, including cell adhesion, migration, cellular signaling, and proteolysis. Proteolytically active ADAMs are responsible for ectodomain shedding of membrane-associated proteins. ADAMs rapidly modulate key cell signaling pathways in response to changes in the extracellular environment (e.g., inflammation) and play a central role in coordinating intercellular communication within the local microenvironment. ADAM10 and ADAM17 are the most studied members of the ADAM family in the gastrointestinal tract. ADAMs regulate many cellular processes associated with intestinal development, cell fate specification, and the maintenance of intestinal stem cell/progenitor populations. Several signaling pathway molecules that undergo ectodomain shedding by ADAMs [e.g., ligands and receptors from epidermal growth factor receptor (EGFR)/ErbB and tumor necrosis factor α (TNFα) receptor (TNFR) families] help drive and control intestinal inflammation and injury/repair responses. Dysregulation of these processes through aberrant ADAM expression or sustained ADAM activity is linked to chronic inflammation, inflammation-associated cancer, and tumorigenesis.