Harnessing the natural inhibitory domain to control TNFα Converting Enzyme (TACE) activity in vivo

Proinflammatory microglial activation impairs in vitro cortical tissue repair via zinc-dependent ADAM17 cleavage of the CSF-1 receptor

Infection and subsequent inflammatory processes negatively impact prognosis in individuals with traumatic brain injury (TBI). Tissue repair following TBI is tightly regulated by microglia, promoting or, importantly, preventing astrocyte-mediated repair processes, depending on the activation state of the neuroimmune cells. This study investigated the poorly understood mechanism linking proinflammatory microglia activation and astrocyte-mediated tissue repair using an in vitro mechanical injury model in mixed cortical cultures of rat neurons and glia. We hypothesized that proinflammatory activation disrupts the microglial response to colony-stimulating factor 1 (CSF-1), which stimulates microglia migration and proliferation, both essential for astrocyte-mediated tissue repair. Following mechanical damage, cultures were treated with lipopolysaccharide (LPS) and interferon-gamma (IFNγ) to induce a proinflammatory state. Immunocytochemical and biochemical analyses were used to evaluate glial repair. Proinflammatory activation dramatically impeded wound closure, reducing microglial levels via upregulation of the zinc-dependent disintegrin and metalloprotease 17 (ADAM17), leading to the cleavage of the CSF-1 receptor (CSF-1R). Indeed, pharmacological inhibition of ADAM17 effectively promoted wound closure during inflammation. Moreover, zinc chelation prevented ADAM17-mediated cleavage of CSF-1R and induced the release of trophic factors, dramatically improving tissue recovery. Our findings strongly identify ADAM17 as a primary regulator of CSF-1R-mediated signaling and establish a mechanism defining the association between pro-inflammatory microglial activation and tissue repair following injury.

Updates on Inflammatory Molecular Pathways Mediated by ADAM17 in Autoimmunity

ADAM17 is a member of the disintegrin and metalloproteinase (ADAM) family of transmembrane proteases with immunoregulatory activity in multiple signaling pathways. The functional ADAM17 is involved in the shedding of the ectodomain characterizing many substrates belonging to growth factors, cytokines, receptors, and adhesion molecules. The ADAM17-dependent pathways are known to be crucial in tumor development and progression and in the modulation of many pathological and physiological processes. In the last decade, ADAM17 was considered the driver of several autoimmune pathologies, and numerous substrate-mediated signal transduction pathways were identified. However, the discoveries made to date have led researchers to try to clarify the multiple mechanisms in which ADAM17 is involved and to identify any molecular gaps between the different transductional cascades. In this review, we summarize the most recent updates on the multiple regulatory activities of ADAM17, focusing on reported data in the field of autoimmunity.

Identification of novel TACE inhibitors using DNN based- virtual screening, molecular dynamics and biological evaluation

Rheumatoid Arthritis (RA) is a well-known autoimmune inflammatory disease, distressing roughly 1% of the adult population throughout the globe. Many studies have suggested that overexpression of TNF-α, a pro-inflammatory cytokine, is responsible for the progression of RA. Furthermore, inhibition of the shedding rate of TNF-α is regulated by the TACE (TNF-α converting enzyme) protein and, hence is considered as an important therapeutic target for the prevention of progressive synovial joint destruction in rheumatoid arthritis. In the present study, we have proposed a deep neural network (DNN)-based workflow for the virtual screening of compounds towards the identification of potential inhibitors against the TACE proteins. Subsequently, a set of compounds were shortlisted, based on the molecular docking and subjected to the biological evaluation to validate the inhibitory activities of the screened compounds, determine the practical applicability of the DNN-based model, and strengthen the hypothesis. Out of seven, three compounds (BTB10246, BTB10247, and BTB10245) showed significant inhibition at 10 µM and 0.1 µM concentration. These three compounds also showed a stable and significant interaction potential against the TACE protein as compared with the re-docked complex system and can serve as a novel scaffold for further design of new molecules with improved inhibitory activities against TACE.Communicated by Ramaswamy H. Sarma.

Cryo-EM reveals that iRhom2 restrains ADAM17 protease activity to control the release of growth factor and inflammatory signals

A disintegrin and metalloprotease 17 (ADAM17) is a membrane-tethered protease that triggers multiple signaling pathways. It releases active forms of the primary inflammatory cytokine tumor necrosis factor (TNF) and cancer-implicated epidermal growth factor (EGF) family growth factors. iRhom2, a rhomboid-like, membrane-embedded pseudoprotease, is an essential cofactor of ADAM17. Here, we present cryoelectron microscopy (cryo-EM) structures of the human ADAM17/iRhom2 complex in both inactive and active states. These reveal three regulatory mechanisms. First, exploiting the rhomboid-like hallmark of TMD recognition, iRhom2 interacts with the ADAM17 TMD to promote ADAM17 trafficking and enzyme maturation. Second, a unique iRhom2 extracellular domain unexpectedly retains the cleaved ADAM17 inhibitory prodomain, safeguarding against premature activation and dysregulated proteolysis. Finally, loss of the prodomain from the complex mobilizes the ADAM17 protease domain, contributing to its ability to engage substrates. Our results reveal how a rhomboid-like pseudoprotease has been repurposed during evolution to regulate a potent membrane-tethered enzyme, ADAM17, ensuring the fidelity of inflammatory and growth factor signaling.

Redefining metalloproteases specificity through network proteolysis

Proteolytic processes on cell surfaces and extracellular matrix (ECM) sustain cell behavior and tissue integrity in health and disease. Matrix metalloproteases (MMPs) and a disintegrin and metalloproteases (ADAMs) remodel cell microenvironments through irreversible proteolysis of ECM proteins and cell surface bioactive molecules. Pan-MMP inhibitors in inflammation and cancer clinical trials have encountered challenges due to promiscuous activities of MMPs. Systems biology advances revealed that MMPs initiate multifactorial proteolytic cascades, creating new substrates, activating or suppressing other MMPs, and generating signaling molecules. This review highlights the intricate network that underscores the role of MMPs beyond individual substrate-enzyme activities. Gaining insight into MMP function and tissue specificity is crucial for developing effective drug discovery strategies and novel therapeutics. This requires considering the dynamic cellular processes and consequences of network proteolysis.

The protease ADAM17 at the crossroads of disease: revisiting its significance in inflammation, cancer, and beyond

The protease A Disintegrin And Metalloproteinase 17 (ADAM17) plays a central role in the pathophysiology of several diseases. ADAM17 is involved in the cleavage and shedding of at least 80 known membrane-tethered proteins, which subsequently modulate several intracellular signaling pathways, and therefore alter cell behavior. Dysregulated expression and/or activation of ADAM17 has been linked to a wide range of autoimmune and inflammatory diseases, cancer, and cardiovascular disease. In this review, we provide an overview of the current state of knowledge from preclinical models and clinical data on the diverse pathophysiological roles of ADAM17, and discuss the mechanisms underlying ADAM17-mediated protein shedding and the potential therapeutic implications of targeting ADAM17 in these diseases.

Alpha-1 antitrypsin inhibits fractalkine-mediated monocyte-lung endothelial cell interactions

Chronic obstructive pulmonary disease (COPD) is characterized by nonresolving inflammation fueled by breach in the endothelial barrier and leukocyte recruitment into the airspaces. Among the ligand-receptor axes that control leukocyte recruitment, the full-length fractalkine ligand (CX3CL1)-receptor (CX3CR1) ensures homeostatic endothelial-leukocyte interactions. Cigarette smoke (CS) exposure and respiratory pathogens increase expression of endothelial sheddases, such as a-disintegrin-and-metalloproteinase-domain 17 (ADAM17, TACE), inhibited by the anti-protease α-1 antitrypsin (AAT). In the systemic endothelium, TACE cleaves CX3CL1 to release soluble CX3CL1 (sCX3CL1). During CS exposure, it is not known whether AAT inhibits sCX3CL1 shedding and CX3CR1+ leukocyte transendothelial migration across lung microvasculature. We investigated the mechanism of sCX3CL1 shedding, its role in endothelial-monocyte interactions, and AAT effect on these interactions during acute inflammation. We used two, CS and lipopolysaccharide (LPS) models of acute inflammation in transgenic Cx3cr1gfp/gfp mice and primary human endothelial cells and monocytes to study sCX3CL1-mediated CX3CR1+ monocyte adhesion and migration. We measured sCX3CL1 levels in plasma and bronchoalveolar lavage (BALF) of individuals with COPD. Both sCX3CL1 shedding and CX3CR1+ monocytes transendothelial migration were triggered by LPS and CS exposure in mice, and were significantly attenuated by AAT. The inhibition of monocyte-endothelial adhesion and migration by AAT was TACE-dependent. Compared with healthy controls, sCX3CL1 levels were increased in plasma and BALF of individuals with COPD, and were associated with clinical parameters of emphysema. Our results indicate that inhibition of sCX3CL1 as well as AAT augmentation may be effective approaches to decrease excessive monocyte lung recruitment during acute and chronic inflammatory states.NEW & NOTEWORTHY Our novel findings that AAT and other inhibitors of TACE, the sheddase that controls full-length fractalkine (CX3CL1) endothelial expression, may provide fine-tuning of the CX3CL1-CX3CR1 axis specifically involved in endothelial-monocyte cross talk and leukocyte recruitment to the alveolar space, suggests that AAT and inhibitors of sCX3CL1 signaling may be harnessed to reduce lung inflammation.

Breast Cancer Macrophage Heterogeneity and Self-renewal are Determined by Spatial Localization

Tumor-infiltrating macrophages support critical steps in tumor progression, and their accumulation in the tumor microenvironment (TME) is associated with adverse outcomes and therapeutic resistance across human cancers. In the TME, macrophages adopt diverse phenotypic alterations, giving rise to heterogeneous immune activation states and induction of cell cycle. While the transcriptional profiles of these activation states are well-annotated across human cancers, the underlying signals that regulate macrophage heterogeneity and accumulation remain incompletely understood. Here, we leveraged a novel ex vivo organotypic TME (oTME) model of breast cancer, in vivo murine models, and human samples to map the determinants of functional heterogeneity of TME macrophages. We identified a subset of F4/80highSca-1+ self-renewing macrophages maintained by type-I interferon (IFN) signaling and requiring physical contact with cancer-associated fibroblasts. We discovered that the contact-dependent self-renewal of TME macrophages is mediated via Notch4, and its inhibition abrogated tumor growth of breast and ovarian carcinomas in vivo, as well as lung dissemination in a PDX model of triple-negative breast cancer (TNBC). Through spatial multi-omic profiling of protein markers and transcriptomes, we found that the localization of macrophages further dictates functionally distinct but reversible phenotypes, regardless of their ontogeny. Whereas immune-stimulatory macrophages (CD11C+CD86+) populated the tumor epithelial nests, the stroma-associated macrophages (SAMs) were proliferative, immunosuppressive (Sca-1+CD206+PD-L1+), resistant to CSF-1R depletion, and associated with worse patient outcomes. Notably, following cessation of CSF-1R depletion, macrophages rebounded primarily to the SAM phenotype, which was associated with accelerated growth of mammary tumors. Our work reveals the spatial determinants of macrophage heterogeneity in breast cancer and highlights the disruption of macrophage self-renewal as a potential new therapeutic strategy.

Targeting IL-6 trans-signalling: past, present and future prospects

Interleukin-6 (IL-6) is a key immunomodulatory cytokine that affects the pathogenesis of diverse diseases, including autoimmune diseases, chronic inflammatory conditions and cancer. Classical IL-6 signalling involves the binding of IL-6 to the membrane-bound IL-6 receptor α-subunit (hereafter termed 'mIL-6R') and glycoprotein 130 (gp130) signal-transducing subunit. By contrast, in IL-6 trans-signalling, complexes of IL-6 and the soluble form of IL-6 receptor (sIL-6R) signal via membrane-bound gp130. A third mode of IL-6 signalling - known as cluster signalling - involves preformed complexes of membrane-bound IL-6-mIL-6R on one cell activating gp130 subunits on target cells. Antibodies and small molecules have been developed that block all three forms of IL-6 signalling, but in the past decade, IL-6 trans-signalling has emerged as the predominant pathway by which IL-6 promotes disease pathogenesis. The first selective inhibitor of IL-6 trans-signalling, sgp130, has shown therapeutic potential in various preclinical models of disease and olamkicept, a sgp130Fc variant, had promising results in phase II clinical studies for inflammatory bowel disease. Technological developments have already led to next-generation sgp130 variants with increased affinity and selectivity towards IL-6 trans-signalling, along with indirect strategies to block IL-6 trans-signalling. Here, we summarize our current understanding of the biological outcomes of IL-6-mediated signalling and the potential for targeting this pathway in the clinic.

Intestinal Damage, Inflammation and Microbiota Alteration during COVID-19 Infection

BACKGROUND

The virus SARS-CoV-2 is responsible for respiratory disorders due to the fact that it mainly infects the respiratory tract using the Angiotensin-converting enzyme 2 (ACE2) receptors. ACE2 receptors are also highly expressed on intestinal cells, representing an important site of entry for the virus in the gut. Literature studies underlined that the virus infects and replicates in the gut epithelial cells, causing gastrointestinal symptoms such as diarrhea, abdominal pain, nausea/vomiting and anorexia. Moreover, the SARS-CoV-2 virus settles into the bloodstream, hyperactivating the platelets and cytokine storms and causing gut-blood barrier damage with an alteration of the gut microbiota, intestinal cell injury, intestinal vessel thrombosis leading to malabsorption, malnutrition, an increasing disease severity and mortality with short and long-period sequelae.

CONCLUSION

This review summarizes the data on how SARS-CoV-2 effects on the gastrointestinal systems, including the mechanisms of inflammation, relationship with the gut microbiota, endoscopic patterns, and the role of fecal calprotectin, confirming the importance of the digestive system in clinical practice for the diagnosis and follow-up of SARS-CoV-2 infection.

The Role of ADAM17 in Inflammation-Related Atherosclerosis

Atherosclerosis is a chronic inflammatory disease that poses a huge economic burden due to its extremely poor prognosis. Therefore, it is necessary to explore potential mechanisms to improve the prevention and treatment of atherosclerosis. A disintegrin and metalloprotease 17 (ADAM17) is a cell membrane-bound protein that performs a range of functions through membrane protein shedding and intracellular signaling. ADAM17-mediated inflammation has been identified to be an important contributor to atherosclerosis; however, the specific relationship between its multiple regulatory roles and the pathogenesis of atherosclerosis remains unclear. Here, we reviewed the activation, function, and regulation of ADAM17, described in detail the role of ADAM17-mediated inflammatory damage in atherosclerosis, and discussed several controversial points. We hope that these insights into ADAM17 biology will lead to rational management of atherosclerosis. ADAM17 promotes vascular inflammation in endothelial cells, smooth muscle cells, and macrophages, and regulates the occurrence and development of atherosclerosis.

The dichotomous outcomes of TNFα signaling in CD4+ T cells

TNFa blocking agents were the first-in-class biologic drugs used for the treatment of autoimmune disease. Paradoxically, however, exacerbation of autoimmunity was observed in some patients. TNFa is a pleiotropic cytokine that has both proinflammatory and regulatory effects on CD4+ T cells and can influence the adaptive immune response against autoantigens. Here, we critically appraise the literature and discuss the intricacies of TNFa signaling that may explain the controversial findings of previous studies. The pleiotropism of TNFa is based in part on the existence of two biologically active forms of TNFa, soluble and membrane-bound, with different affinities for two distinct TNF receptors, TNFR1 and TNFR2, leading to activation of diverse downstream molecular pathways involved in cell fate decisions and immune function. Distinct membrane expression patterns of TNF receptors by CD4+ T cell subsets and their preferential binding of distinct forms of TNFα produced by a diverse pool of cellular sources during different stages of an immune response are important determinants of the differential outcomes of TNFa-TNF receptor signaling. Targeted manipulation of TNFa-TNF receptor signaling on select CD4+ T cell subsets may offer specific therapeutic interventions to dampen inflammation while fortifying immune regulation for the treatment of autoimmune diseases.

Shaikh F, B. Patil A, L. S. Hallur R. Identification of three coagulins as MMP inhibitors from Withania coagulans Dunal fruits

Introduction and Aim: W. coagulans Dunal has been reported to contain an array of bioactive compounds. The present investigation was carried out to investigate MMP inhibitory molecules from W. coagulans Dunal fruit.   Materials and Methods: Isolation of active principle compounds and anti-ChC activity from methanol extract of W. coagulans Dunal fruit were carried out using chromatographic techniques and dot-blot assay on X-ray film. Active principle compounds were identified by ESI MS, 1H, and 13C NMR spectroscopy. The Bioefficacy of compounds was assessed by in vitro solution assay and gelatin zymography.   Results: Dot blot assay of methanol extract of W. coagulans Dunal fruit exhibited inhibitory activity against ChC (Clostridium histolyticum collagenase). Bioactivity assay guided chromatographic fractionation revealed the presence of five compounds out of which three were tentatively identified as Coagulin-H, Coagulin-L, and Coagulin-O by ESI MS, 1H, and 13C NMR spectroscopy. In vitro solution assay revealed Coagulin-H exhibits the highest MMP-2 and MMP-9  inhibitory activity. Coagulin-L and Coagulin-O exhibit 80.57 ± 2.1 % and 70.96 ± 2.8 % inhibitor activities against MMP-2 and 78.94 ± 3.6% and 63.15 ± 3.8% inhibitor activities against MMP-9 at 150 µg/ml respectively. In gel inhibition assay by gelatin zymography revealed that crude extracted residue of fruit exhibits dose-dependent inhibitory potential against MMPs of NIH3T3 fibroblast and HeLa cervical cells.   Conclusion: Our results advocate the anti-MMP potential of purified Coagulin-H, Coagulin-L, and Coagulin-O of W. coagulans Dunal fruits. These bioactive principles could be further investigated in detail for anti-cancer properties.

Blockade of the protease ADAM17 ameliorates experimental pancreatitis

Acute and chronic pancreatitis, the latter associated with fibrosis, are multifactorial inflammatory disorders and leading causes of gastrointestinal disease-related hospitalization. Despite the global health burden of pancreatitis, currently, there are no effective therapeutic agents. In this regard, the protease A Disintegrin And Metalloproteinase 17 (ADAM17) mediates inflammatory responses through shedding of bioactive inflammatory cytokines and mediators, including tumor necrosis factor α (TNFα) and the soluble interleukin (IL)-6 receptor (sIL-6R), the latter of which drives proinflammatory IL-6 trans-signaling. However, the role of ADAM17 in pancreatitis is unclear. To address this, Adam17^ex/ex mice-which are homozygous for the hypomorphic Adam17^ex allele resulting in marked reduction in ADAM17 expression-and their wild-type (WT) littermates were exposed to the cerulein-induced acute pancreatitis model, and acute (1-wk) and chronic (20-wk) pancreatitis models induced by the cigarette smoke carcinogen nicotine-derived nitrosamine ketone (NNK). Our data reveal that ADAM17 expression was up-regulated in pancreatic tissues of animal models of pancreatitis. Moreover, the genetic (Adam17^ex/ex mice) and therapeutic (ADAM17 prodomain inhibitor [A17pro]) targeting of ADAM17 ameliorated experimental pancreatitis, which was associated with a reduction in the IL-6 trans-signaling/STAT3 axis. This led to reduced inflammatory cell infiltration, including T cells and neutrophils, as well as necrosis and fibrosis in the pancreas. Furthermore, up-regulation of the ADAM17/IL-6 trans-signaling/STAT3 axis was a feature of pancreatitis patients. Collectively, our findings indicate that the ADAM17 protease plays a pivotal role in the pathogenesis of pancreatitis, which could pave the way for devising novel therapeutic options to be deployed against this disease.

Inhibitory proteins block substrate access by occupying the active site cleft of Bacillus subtilis intramembrane protease SpoIVFB

Intramembrane proteases (IPs) function in numerous signaling pathways that impact health, but elucidating the regulation of membrane-embedded proteases is challenging. We examined inhibition of intramembrane metalloprotease SpoIVFB by proteins BofA and SpoIVFA. We found that SpoIVFB inhibition requires BofA residues in and near a predicted transmembrane segment (TMS). This segment of BofA occupies the SpoIVFB active site cleft based on cross-linking experiments. SpoIVFB inhibition also requires SpoIVFA. The inhibitory proteins block access of the substrate N-terminal region to the membrane-embedded SpoIVFB active site, based on additional cross-linking experiments; however, the inhibitory proteins did not prevent interaction between the substrate C-terminal region and the SpoIVFB soluble domain. We built a structural model of SpoIVFB in complex with BofA and parts of SpoIVFA and substrate, using partial homology and constraints from cross-linking and co-evolutionary analyses. The model predicts that conserved BofA residues interact to stabilize a TMS and a membrane-embedded C-terminal region. The model also predicts that SpoIVFA bridges the BofA C-terminal region and SpoIVFB, forming a membrane-embedded inhibition complex. Our results reveal a novel mechanism of IP inhibition with clear implications for relief from inhibition in vivo and design of inhibitors as potential therapeutics.

Validating Cell Surface Proteases as Drug Targets for Cancer Therapy: What Do We Know, and Where Do We Go?

Cell surface proteases (also known as ectoproteases) are transmembrane and membrane-bound enzymes involved in various physiological and pathological processes. Several members, most notably dipeptidyl peptidase 4 (DPP4/CD26) and its related family member fibroblast activation protein (FAP), aminopeptidase N (APN/CD13), a disintegrin and metalloprotease 17 (ADAM17/TACE), and matrix metalloproteinases (MMPs) MMP2 and MMP9, are often overexpressed in cancers and have been associated with tumour dysfunction. With multifaceted actions, these ectoproteases have been validated as therapeutic targets for cancer. Numerous inhibitors have been developed to target these enzymes, attempting to control their enzymatic activity. Even though clinical trials with these compounds did not show the expected results in most cases, the field of ectoprotease inhibitors is growing. This review summarizes the current knowledge on this subject and highlights the recent development of more effective and selective drugs targeting ectoproteases among which small molecular weight inhibitors, peptide conjugates, prodrugs, or monoclonal antibodies (mAbs) and derivatives. These promising avenues have the potential to deliver novel therapeutic strategies in the treatment of cancers.

Inhibition of ADAM17 impairs endothelial cell necroptosis and blocks metastasis

Metastasis is the major cause of death in cancer patients. Circulating tumor cells need to migrate through the endothelial layer of blood vessels to escape the hostile circulation and establish metastases at distant organ sites. Here, we identified the membrane-bound metalloprotease ADAM17 on endothelial cells as a key driver of metastasis. We show that TNFR1-dependent tumor cell-induced endothelial cell death, tumor cell extravasation, and subsequent metastatic seeding is dependent on the activity of endothelial ADAM17. Moreover, we reveal that ADAM17-mediated TNFR1 ectodomain shedding and subsequent processing by the γ-secretase complex is required for the induction of TNF-induced necroptosis. Consequently, genetic ablation of ADAM17 in endothelial cells as well as short-term pharmacological inhibition of ADAM17 prevents long-term metastases formation in the lung. Thus, our data identified ADAM17 as a novel essential regulator of necroptosis and as a new promising target for antimetastatic and advanced-stage cancer therapies.

ACE2 in the Gut: The Center of the 2019-nCoV Infected Pathology

The 2019-nCoV is a rapidly contagious pneumonia caused by the recently discovered coronavirus. Although generally the most noticeable symptoms are concentrated in the lungs, the disorders in the gastrointestinal tract are of great importance in the diagnosis of 2019-nCoV. The angiotensin-converting enzyme 2 (ACE2), an important regulator of many physiological functions, including blood pressure and nutrients absorption, is recently identified as a vital entry for 2019-nCoV to enter host cells. In this review, we summarize its functions both physiologically and pathologically. We also elaborate its conflicting roles from the clews of contemporary researches, which may provide significant indications for pharmacological investigations and clinical uses.

Regulation of meprin metalloproteases in mucosal homeostasis

Mucus is covering the entire epithelium of the gastrointestinal tract (GIT), building the interface for the symbiosis between microorganisms and their host. Hence, a disrupted mucosal barrier or alterations of proper mucus composition, including the gut microbiota, can cause severe infection and inflammation. Meprin metalloproteases are well-known to cleave various pro-inflammatory molecules, contributing to the onset and progression of pathological conditions including sepsis, pulmonary hypertension or inflammatory bowel disease (IBD). Moreover, meprins have an impact on migration and infiltration of immune cells like monocytes or leukocytes during intestinal inflammation by cleaving tight junction proteins or cell adhesion molecules, thereby disrupting epithelial cell barrier and promoting transendothelial cell migration. Interestingly, both meprin α and meprin β are susceptibility genes for IBD. However, both genes are significantly downregulated in inflamed intestinal tissue in contrast to healthy donors. Therefore, a detailed understanding of the underlying molecular mechanisms is the basis for developing new and effective therapies against manifold pathologies like IBD. This review focuses on the regulation of meprin metalloproteases and its impact on physiological and pathological conditions related to mucosal homeostasis.

ADAM17 orchestrates Interleukin-6, TNFα and EGF-R signaling in inflammation and cancer

It was realized in the 1990s that some membrane proteins such as TNFα, both TNF receptors, ligands of the EGF-R and the Interleukin-6 receptor are proteolytically cleaved and are shed from the cell membrane as soluble proteins. The major responsible protease is a metalloprotease named ADAM17. So far, close to 100 substrates, including cytokines, cytokine receptors, chemokines and adhesion molecules of ADAM17 are known. Therefore, ADAM17 orchestrates many different signaling pathways and is a central signaling hub in inflammation and carcinogenesis. ADAM17 plays an important role in the biology of Interleukin-6 (IL-6) since the generation of the soluble Interleukin-6 receptor (sIL-6R) is needed for trans-signaling, which has been identified as the pro-inflammatory activity of this cytokine. In contrast, Interleukin-6 signaling via the membrane-bound Interleukin-6 receptor is mostly regenerative and protective. Probably due to its broad substrate spectrum, ADAM17 is essential for life and most of the few human individuals identified with ADAM17 gene defects died at young age. Although the potential of ADAM17 as a therapeutic target has been recognized, specific blockade of ADAM17 is not trivial since the metalloprotease domain of ADAM17 shares high structural homology with other proteases, in particular matrix metalloproteases. Here, the critical functions of ADAM17 in IL-6, TNFα and EGF-R pathways and strategies of therapeutic interventions are discussed.

Metabolic Messengers: tumour necrosis factor

Tumour necrosis factor (TNF) is a classical, pleiotropic pro-inflammatory cytokine. It is also the first 'adipokine' described to be produced from adipose tissue, regulated in obesity and proposed to contribute to obesity-associated metabolic disease. In this review, we provide an overview of TNF in the context of metabolic inflammation or metaflammation, its discovery as a metabolic messenger, its sites and mechanisms of action and some critical considerations for future research. Although we focus on TNF and the studies that elucidated its immunometabolic actions, we highlight a conceptual framework, generated by these studies, that is equally applicable to the complex network of pro-inflammatory signals, their biological activity and their integration with metabolic regulation, and to the field of immunometabolism more broadly.

Blocking only the bad side of IL-6 in inflammation and cancer

Interleukin-6 (IL-6) is considered an inflammatory cytokine, which is involved not only in most inflammatory states but it also plays a prominent role in inflammation associated cancers. The response of cells to the cytokine strictly depends on the presence of the IL-6 receptor (IL-6R),which presents IL-6 to the signal transducing receptor subunit gp130, which is expressed on all cells of the body. The expression of IL-6R is limited to some cells, which are therefore IL-6 target cells. The IL-6R can be cleaved by proteases and the thus generated soluble IL-6R (sIL-6R) still binds the ligand IL-6. The complex of IL-6 and sIL-6R can bind to gp130 on any cell, induce dimerization of gp130 and intracellular signaling. This process has been named IL-6 trans-signaling. A fusion protein of soluble gp130 with the constant portion of human IgG1 (sgp130Fc) turned out to be a potent and specific inhibitor of IL-6 trans-signaling. In many animal models of human diseases the significance of IL-6 trans-signaling has been analyzed. It turned out that the activities of IL-6 mediated by the sIL-6R are the pro-inflammatory activities of the cytokine whereas activities of IL-6 mediated by the membrane-bound IL-6R are rather protective and regenerative. The sgp130Fc protein has recently been developed into a biologic. The possible consequences of a specific IL-6 trans-signaling blockade is discussed in the light of the recent successfully concluded phase II clinical trials in patients with inflammatory bowel disease.

The role of ADAM17 during liver damage

A disintegrin and metalloprotease (ADAM) 17 is a membrane bound protease, involved in the cleavage and thus regulation of various membrane proteins, which are critical during liver injury. Among ADAM17 substrates are tumor necrosis factor α (TNFα), tumor necrosis factor receptor 1 and 2 (TNFR1, TNFR2), the epidermal growth factor receptor (EGFR) ligands amphiregulin (AR) and heparin-binding-EGF-like growth factor (HB-EGF), the interleukin-6 receptor (IL-6R) and the receptor for a hepatocyte growth factor (HGF), c-Met. TNFα and its binding receptors can promote liver injury by inducing apoptosis and necroptosis in liver cells. Consistently, hepatocyte specific deletion of ADAM17 resulted in increased liver cell damage following CD95 stimulation. IL-6 trans-signaling is critical for liver regeneration and can alleviate liver damage. EGFR ligands can prevent liver damage and deletion of amphiregulin and HB-EGF can result in increased hepatocyte death and reduced proliferation. All of which indicates that ADAM17 has a central role in liver injury and recovery from it. Furthermore, inactive rhomboid proteins (iRhom) are involved in the trafficking and maturation of ADAM17 and have been linked to liver damage. Taken together, ADAM17 can contribute in a complex way to liver damage and injury.

Key metalloproteinase-mediated pathways in the kidney

Matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinases (ADAMs) belong to the metzincin family of zinc-containing multidomain molecules, and can act as soluble or membrane-bound proteases. These enzymes inactivate or activate other soluble or membrane-expressed mediator molecules, which enables them to control developmental processes, tissue remodelling, inflammatory responses and proliferative signalling pathways. The dysregulation of MMPs and ADAMs has long been recognized in acute kidney injury and in chronic kidney disease, and genetic targeting of selected MMPs and ADAMs in different mouse models of kidney disease showed that they can have detrimental and protective roles. In particular, MMP-2, MMP-7, MMP-9, ADAM10 and ADAM17 have been shown to have a mainly profibrotic effect and might therefore represent therapeutic targets. Each of these proteases has been associated with a different profibrotic pathway that involves tissue remodelling, Wnt-β-catenin signalling, stem cell factor-c-kit signalling, IL-6 trans-signalling or epidermal growth factor receptor (EGFR) signalling. Broad-spectrum metalloproteinase inhibitors have been used to treat fibrotic kidney diseases experimentally but more targeted approaches have since been developed, including inhibitory antibodies, to avoid the toxic side effects initially observed with broad-spectrum inhibitors. These advances not only provide a solid foundation for additional preclinical studies but also encourage further translation into clinical research.

Impact of the COVID-19 pandemic on inflammatory bowel disease patients: A review of the current evidence

Since the initial coronavirus disease 2019 (COVID-19) outbreak in China in December 2019, the infection has now become the biggest medical issue of modern medicine. Two major contributors that amplified the impact of the disease and subsequently increased the burden on health care systems were high mortality among patients with multiple co-morbidities and overcapacity of intensive care units. Within the gastroenterology-related community, particular concern was raised with respect to patients with inflammatory bowel disease (IBD), as those patients are prone to opportunistic infections mainly owing to their immunosuppressive-based therapies. Hence, we sought to summarize current knowledge regarding COVID-19 infection in patients with IBD. Overall, it seems that IBD is not a comorbidity that poses an increased risk for COVID-19 acquisition, except in patients treated with 5-aminosalicylates. Furthermore, outcomes of the infected patients are largely dependent on therapeutic modality by which they are treated, as some worsen the clinical course of COVID-19 infection, whereas others seem to dampen the detrimental effects of COVID-19. Finally, we discussed the present and the future impact of COVID-19 pandemic and concomitantly increased health care burden on IBD-management.

Molecular switch in human diseases-disintegrin and metalloproteinases, ADAM17

The ADAMs (a disintegrin and metalloproteinase) are a family of cell surface proteins with crucial roles in the regulation of cell adhesion, cell proliferation to migration, proteolysis and cell signaling transduction pathways. Among these enzymes, the ADAM17 shows significant effects in the “ectodomain shedding” of its substrates such as cytokines (e.g., tumor necrosis factor α, TNFα), growth factors (e.g., epidermal growth factor, EGF), adhesion proteins (e.g., L-selectin), and their receptors (e.g., IL-6R and TNFα). Several studies focus on the underlying molecular mechanisms of ADAM17 in diseased conditions. Here, we took several different approaches to elucidate the function of ADAM17, the participation of ADAM17 in several human diseases, and the potential as targeted therapy reagents. As more and more studies verify the miRNA-mediated expression variation of ADAM17, the specific regulation network of miRNAs and ADAM17 was exploited in this review as well.

Contribution of ADAM17 and related ADAMs in cardiovascular diseases

A disintegrin and metalloproteases (ADAMs) are key mediators of cell signaling by ectodomain shedding of various growth factors, cytokines, receptors and adhesion molecules at the cellular membrane. ADAMs regulate cell proliferation, cell growth, inflammation, and other regular cellular processes. ADAM17, the most extensively studied ADAM family member, is also known as tumor necrosis factor (TNF)-α converting enzyme (TACE). ADAMs-mediated shedding of cytokines such as TNF-α orchestrates immune system or inflammatory cascades and ADAMs-mediated shedding of growth factors causes cell growth or proliferation by transactivation of the growth factor receptors including epidermal growth factor receptor. Therefore, increased ADAMs-mediated shedding can induce inflammation, tissue remodeling and dysfunction associated with various cardiovascular diseases such as hypertension and atherosclerosis, and ADAMs can be a potential therapeutic target in these diseases. In this review, we focus on the role of ADAMs in cardiovascular pathophysiology and cardiovascular diseases. The main aim of this review is to stimulate new interest in this area by highlighting remarkable evidence.

ADAM17 Inhibition Increases the Impact of Cisplatin Treatment in Ovarian Cancer Spheroids

Simple Summary

Ovarian cancer (OvCa) treatment is still a challenge, mainly due to acquired resistance mechanisms during the course of chemotherapy. Here, we show the enhanced cytotoxicity of the combined treatment with the ADAM17 inhibitor GW280264X and cisplatin in comparison with cisplatin monotherapy. This effect was visible in five of five ovarian cancer cell lines grown as a monolayer and two of three tested cell lines in three-dimensional tumor spheroids. Tumor spheroids derived from primary tumor and ascites cells were sensitized to cisplatin treatment by GW280264X. In summary, the combination of ADAM17 inhibition with conventional chemotherapy seems to be a promising strategy to overcome chemotherapy resistance in OvCa.

Abstract

Chemotherapy resistance is a major challenge in ovarian cancer (OvCa). Thus, novel treatment combinations are highly warranted. However, many promising drug candidates tested in two-dimensional (2D) cell culture have not proved successful in the clinic. For this reason, we analyzed our drug combination not only in monolayers but also in three-dimensional (3D) tumor spheroids. One potential therapeutic target for OvCa is A disintegrin and metalloprotease 17 (ADAM17). ADAM17 can be activated by chemotherapeutics, which leads to enhanced tumor growth due to concomitant substrate cleavage. Therefore, blocking ADAM17 during chemotherapy may overcome resistance. Here, we tested the effect of the ADAM17 inhibitor GW280264X in combination with cisplatin on ovarian cancer cells in 2D and 3D. In 2D, the effect on five cell lines was analyzed with two readouts. Three of these cell lines formed dense aggregates or spheroids (HEY, SKOV-3, and OVCAR-8) in 3D and the treatment effect was analyzed with a multicontent readout (cytotoxicity, viability, and caspase3/7 activation). We tested the combined therapy on tumor spheroids derived from primary patient cells. In 2D, we found a significant reduction in the half minimal (50%) inhibitory concentration (IC₅₀) value of the combined treatment (GW280264X plus cisplatin) in comparison with cisplatin monotherapy in all five cell lines with both 2D readout assays (viability and caspase activation). In contrast, the combined treatment only showed an IC₅₀ reduction in HEY and OVCAR-8 3D tumor spheroid models using caspase3/7 activity or Celltox^TM Green as the readout. Finally, we found an improved effect of GW280264X with cisplatin in tumor spheroids derived from patient samples. In summary, we demonstrate that ADAM17 inhibition is a promising treatment strategy in ovarian cancer.

Alimentary system is directly attacked by SARS-COV-2 and further prevents immune dysregulation caused by COVID-19

BACKGROUND

SARS-COV-2 causes digestive system symptom, the effect of which remains equivocal.

METHODS

Patients with COVID-19 were classified into four groups according to symptom. The study traced the onset and duration of symptoms, compared laboratory examinations and conducted bioinformatic analysis. Immune indices were further analysed.

RESULTS

By March 16, 25 patients with COVID-19 and 13 with suspect COVID-19 were admitted to West China Hospital, Sichuan University. Digestive system symptom group had the highest level of ESR (mm/h, P < .0001), serum ferritin (ng/ml, P < .0001), hepatic enzymes (P < .05) and retentive lymphocyte count/percentage (P < .05) and its subsets (P < .05). Combined group (respiratory combined with subsequent digestive system symptom) had the highest level of IL-6 (pg/ml, P = .0046), CRP (mg/L, P = .0004) and moderate lymphocyte depletion. Respiratory system symptom and asymptomatic groups suffered the most from lymphocyte depletion (P < .05). Bioinformatic analysis indicated co-expression of binding related proteins of SARS-COV-2 (ACE2, TMPRSS2 and Furin) in small intestine. CD147 was extensively expressed in alimentary tract. CTSL, PIKfyve, TPC2 and CTSB could be detected with ≥moderate expressions in a variety of organs including alimentary system.

CONCLUSIONS

Alimentary system is possibly attacked by SARS-COV-2 other than hyperinflammation or immune dysregulation caused by it. Involvement of alimentary system might further protect mild and moderate cases from lymphocyte depletion caused by COVID-19.

Strategies to Target ADAM17 in Disease: From its Discovery to the iRhom Revolution

For decades, disintegrin and metalloproteinase 17 (ADAM17) has been the object of deep investigation. Since its discovery as the tumor necrosis factor convertase, it has been considered a major drug target, especially in the context of inflammatory diseases and cancer. Nevertheless, the development of drugs targeting ADAM17 has been harder than expected. This has generally been due to its multifunctionality, with over 80 different transmembrane proteins other than tumor necrosis factor α (TNF) being released by ADAM17, and its structural similarity to other metalloproteinases. This review provides an overview of the different roles of ADAM17 in disease and the effects of its ablation in a number of in vivo models of pathological conditions. Furthermore, here, we comprehensively encompass the approaches that have been developed to accomplish ADAM17 selective inhibition, from the newest non-zinc-binding ADAM17 synthetic inhibitors to the exploitation of iRhom2 to specifically target ADAM17 in immune cells.

Management of inflammatory bowel disease in the COVID-19 era

During the coronavirus disease 2019 (COVID-19) pandemic, many unpredictable changes have occurred in the medical field. Risk of COVID-19 does not seem to increase in patients with inflammatory bowel disease (IBD) considering based on current reports. Current medications for IBD do not increase this risk; on the contrary, some of these might be used as therapeutics against COVID-19 and are under clinical trial. Unless the patients have confirmed COVID-19 and severe pneumonia or a high oxygen demand, medical treatment should be continued during the pandemic, except for the use of high-dose corticosteroids. Adherence to general recommendations such as social distancing, wearing facial masks, and vaccination, especially for pneumococcal infections and influenza, is also required. Patients with COVID-19 need to be withhold immunomodulators or biologics for at least 2 weeks and treated based on both IBD and COVID-19 severity. Prevention of IBD relapse caused by sudden medication interruption is important because negative outcomes associated with disease flare up, such as corticosteroid use or hospitalization, are much riskier than medications. The outpatient clinic and infusion center for biologics need to be reserved safe spaces, and endoscopy or surgery should be considered in urgent cases only.

Distinct integrin activation pathways for effector and regulatory T cell trafficking and function

Integrin activation mediates lymphocyte trafficking and immune functions. Conventional T cell (Tconv cell) integrin activation requires Rap1-interacting adaptor molecule (RIAM). Here, we report that Apbb1ip-/- (RIAM-null) mice are protected from spontaneous colitis due to IL-10 deficiency, a model of inflammatory bowel disease (IBD). Protection is ascribable to reduced accumulation and homing of Tconv cells in gut-associated lymphoid tissue (GALT). Surprisingly, there are abundant RIAM-null regulatory T cells (T reg cells) in the GALT. RIAM-null T reg cells exhibit normal homing to GALT and lymph nodes due to preserved activation of integrins αLβ2, α4β1, and α4β7. Similar to Tconv cells, T reg cell integrin activation and immune function require Rap1; however, lamellipodin (Raph1), a RIAM paralogue, compensates for RIAM deficiency. Thus, in contrast to Tconv cells, RIAM is dispensable for T reg cell integrin activation and suppressive function. In consequence, inhibition of RIAM can inhibit spontaneous Tconv cell-mediated autoimmune colitis while preserving T reg cell trafficking and function.

The Role of RECK in Hepatobiliary Neoplasia Reveals Its Therapeutic Potential in NASH

Non-alcoholic fatty liver disease (NAFLD) is a multimorbidity disorder ranging from excess accumulation of fat in the liver (steatosis) to steatohepatitis (NASH) and end-stage cirrhosis, and the development of hepatocellular carcinoma (HCC) in a subset of patients. The defining features of NASH are inflammation and progressive fibrosis. Currently, no pharmaceutical therapies are available for NAFLD, NASH and HCC; therefore, developing novel treatment strategies is desperately needed. Reversion Inducing Cysteine Rich Protein with Kazal motifs (RECK) is a well-known modifier of the extracellular matrix in hepatic remodeling and transition to HCC. More recently, its role in regulating inflammatory and fibrogenic processes has emerged. Here, we summarize the most relevant findings that extend our current understanding of RECK as a regulator of inflammation and fibrosis, and its induction as a potential strategy to blunt the development and progression of NASH and HCC.

A combinational approach to restore cytokine balance and to inhibit virus growth may promote patient recovery in severe COVID-19 cases

The COVID-19 pandemic has led to twin public health and economic crises around the world. Not only has it cost hundreds of thousands of lives but also severely impacted livelihoods and placed enormous strain on community healthcare and welfare services. In this review, we explore the events associated with SARS-CoV-2 pathogenesis and host immunopathological reactivity due to the clinical manifestations of this coronavirus infection. We discuss that the metallopeptidase enzyme ADAM17, also known as tumor necrosis factor-α-converting enzyme, TACE, is responsible for shedding of angiotensin-converting enzyme 2 and membrane-bound interleukin (IL)-6 receptor. This leads to elevated pro-inflammatory responses that result in cytokine storm syndrome. We argue that cytokine balance may be restored by recovering an IL-6 trans-signaling neutralizing buffer system through the mediation of recombinant soluble glycoprotein 130 and recombinant ADAM17/TACE prodomain inhibitor. This cytokine restoration, possibly combined with inhibition of SARS-CoV-2 entry as well as replication and coagulopathy, could be introduced as a novel approach to treat patients with severe COVID-19. In cases of co-morbidity, therapies related to the management of associated disease conditions could ameliorate those clinical manifestations.

Clinical Features and Pathogenic Mechanisms of Gastrointestinal Injury in COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the global coronavirus disease 2019 (COVID-19) outbreak. Along with the respiratory tract, the gastrointestinal (GI) tract is one of the main extra-pulmonary targets of SARS-CoV-2 with respect to symptom occurrence and is a potential route for virus transmission, most likely due to the presence of angiotensin-converting enzyme 2. Therefore, understanding the mechanisms of GI injury is crucial for a harmonized therapeutic strategy against COVID-19. This review summarizes the current evidence for the clinical features of and possible pathogenic mechanisms leading to GI injury in COVID-19.

The ADAM17 protease promotes tobacco smoke carcinogen-induced lung tumorigenesis

Lung cancer is the leading cause of cancer-related mortality, with most cases attributed to tobacco smoking, in which nicotine-derived nitrosamine ketone (NNK) is the most potent lung carcinogen. The ADAM17 protease is responsible for the ectodomain shedding of many pro-tumorigenic cytokines, growth factors and receptors, and therefore is an attractive target in cancer. However, the role of ADAM17 in promoting tobacco smoke carcinogen-induced lung carcinogenesis is unknown. The hypomorphic Adam17ex/ex mice-characterized by reduced global ADAM17 expression-were backcrossed onto the NNK-sensitive pseudo-A/J background. CRISPR-driven and inhibitor-based (GW280264X, and ADAM17 prodomain) ADAM17 targeting was employed in the human lung adenocarcinoma cell lines A549 and NCI-H23. Human lung cancer biopsies were also used for analyses. The Adam17ex/ex mice displayed marked protection against NNK-induced lung adenocarcinoma. Specifically, the number and size of lung lesions in NNK-treated pseudo-A/J Adam17ex/ex mice were significantly reduced compared with wild-type littermate controls. This was associated with lower proliferative index throughout the lung epithelium. ADAM17 targeting in A549 and NCI-H23 cells led to reduced proliferative and colony-forming capacities. Notably, among select ADAM17 substrates, ADAM17 deficiency abrogated shedding of the soluble IL-6 receptor (sIL-6R), which coincided with the blockade of sIL-6R-mediated trans-signaling via ERK MAPK cascade. Furthermore, NNK upregulated phosphorylation of p38 MAPK, whose pharmacological inhibition suppressed ADAM17 threonine phosphorylation. Importantly, ADAM17 threonine phosphorylation was significantly upregulated in human lung adenocarcinoma with smoking history compared with their cancer-free controls. Our study identifies the ADAM17/sIL-6R/ERK MAPK axis as a candidate therapeutic strategy against tobacco smoke-associated lung carcinogenesis.

The Thrilling Journey of SARS-CoV-2 into the Intestine: From Pathogenesis to Future Clinical Implications

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has a direct impact on the gastrointestinal system, as up to 50% of fecal samples from coronavirus disease 2019 (COVID-19) patients contain detectable viral RNA despite a negative rhino-pharyngeal swab. This finding, together with an intestinal expression of angiotensin conversion enzyme 2 protein, suggests a possible fecal-oral transmission for SARS-CoV-2. Furthermore, gastrointestinal (GI) symptoms are common in COVID-19 patients including watery diarrhea, vomiting-particularly in children-nausea, and abdominal pain. Pathogenesis of SARS-CoV-2 infection presents significant similarities to those of some immune-mediated diseases, such as inflammatory bowel diseases or rheumatoid arthritis, leading to the hypothesis that targeted therapies used for the treatment of immune-mediated disease could be effective to treat (and possibly prevent) the main complications of COVID-19. In this review, we synthesize the present and future impact of SARS-CoV-2 infection on the gastrointestinal system and on gastroenterology practice, hypothesizing a potential role of the "gut-lung axis" and perhaps of the gut and lung microbiota into the interindividual differential susceptibility to COVID-19 19 disease. Finally, we speculate on the reorganization of outpatient gastroenterology services, which need to consider, among other factors, the major psychological impact of strict lockdown measures on the whole population.

ADAM-Mediated Signalling Pathways in Gastrointestinal Cancer Formation

Tumour growth is not solely driven by tumour cell-intrinsic mechanisms, but also depends on paracrine signals provided by the tumour micro-environment. These signals comprise cytokines and growth factors that are synthesized as trans-membrane proteins and need to be liberated by limited proteolysis also termed ectodomain shedding. Members of the family of A disintegrin and metalloproteases (ADAM) are major mediators of ectodomain shedding and therefore initiators of paracrine signal transduction. In this review, we summarize the current knowledge on how ADAM proteases on tumour cells but also on cells of the tumour micro-environment contribute to the formation of gastrointestinal tumours, and discuss how these processes can be exploited pharmacologically.

IBD Patients Could Be Silent Carriers for Novel Coronavirus and Less Prone to its Severe Adverse Events: True or False?

Inflammatory bowel diseases (IBDs) are chronic disorders of the gastrointestinal tract. The goal of IBD treatment is to reduce the inflammation period and induce long-term remission. Use of anti-inflammatory drugs including corticosteroids, immunosuppressants and biologicals, is often the first step in the treatment of IBD. Therefore, IBD patients in pandemic of infectious diseases are considered a high-risk group. The public believes that IBD patients are at a higher risk in the current coronavirus 2 pandemic. Nevertheless, these patients may experience mild or moderate complications compared to healthy people. This might be because of particular anti-TNF-α treatment or any immunosuppressant that IBD patients receive. Moreover, these patients might be silent carrier for the virus.

COVID-19 and immunomodulation in IBD

The current coronavirus pandemic is an ongoing global health crisis due to COVID-19, caused by severe acute respiratory syndrome coronavirus 2. Although COVID-19 leads to little or mild flu-like symptoms in the majority of affected patients, the disease may cause severe, frequently lethal complications such as progressive pneumonia, acute respiratory distress syndrome and organ failure driven by hyperinflammation and a cytokine storm syndrome. This situation causes various major challenges for gastroenterology. In the context of IBD, several key questions arise. For instance, it is an important question to understand whether patients with IBD (eg, due to intestinal ACE2 expression) might be particularly susceptible to COVID-19 and the cytokine release syndrome associated with lung injury and fatal outcomes. Another highly relevant question is how to deal with immunosuppression and immunomodulation during the current pandemic in patients with IBD and whether immunosuppression affects the progress of COVID-19. Here, the current understanding of the pathophysiology of COVID-19 is reviewed with special reference to immune cell activation. Moreover, the potential implications of these new insights for immunomodulation and biological therapy in IBD are discussed.

Protective role of ACE2 and its downregulation in SARS-CoV-2 infection leading to Macrophage Activation Syndrome: Therapeutic implications

In light of the outbreak of the 2019 novel coronavirus disease (COVID-19), the international scientific community has joined forces to develop effective treatment strategies. The Angiotensin-Converting Enzyme (ACE) 2, is an essential receptor for cell fusion and engulfs the SARS coronavirus infections. ACE2 plays an important physiological role, practically in all the organs and systems. Also, ACE2 exerts protective functions in various models of pathologies with acute and chronic inflammation. While ACE2 downregulation by SARS-CoV-2 spike protein leads to an overactivation of Angiotensin (Ang) II/AT1R axis and the deleterious effects of Ang II may explain the multiorgan dysfunction seen in patients. Specifically, the role of Ang II leading to the appearance of Macrophage Activation Syndrome (MAS) and the cytokine storm in COVID-19 is discussed below. In this review, we summarized the latest research progress in the strategies of treatments that mainly focus on reducing the Ang II-induced deleterious effects rather than attenuating the virus replication.

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Protective role of ACE2 in the organs and system

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Downregulation of ACE2 expression by SARS-CoV-2 leads to Ang II-induced organ damage.

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The appearance of MAS in COVID-19 patient

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Suggested treatment to diminish the deleterious effect of Ang II or appearance of MAS

ADAM17 selectively activates the IL-6 trans-signaling/ERK MAPK axis in KRAS-addicted lung cancer

Oncogenic KRAS mutations are major drivers of lung adenocarcinoma (LAC), yet the direct therapeutic targeting of KRAS has been problematic. Here, we reveal an obligate requirement by oncogenic KRAS for the ADAM17 protease in LAC In genetically engineered and xenograft (human cell line and patient-derived) Kras ^G12D-driven LAC models, the specific blockade of ADAM17, including with a non-toxic prodomain inhibitor, suppressed tumor burden by reducing cellular proliferation. The pro-tumorigenic activity of ADAM17 was dependent upon its threonine phosphorylation by p38 MAPK, along with the preferential shedding of the ADAM17 substrate, IL-6R, to release soluble IL-6R that drives IL-6 trans-signaling via the ERK1/2 MAPK pathway. The requirement for ADAM17 in Kras ^G12D-driven LAC was independent of bone marrow-derived immune cells. Furthermore, in KRAS mutant human LAC, there was a significant positive correlation between augmented phospho-ADAM17 levels, observed primarily in epithelial rather than immune cells, and activation of ERK and p38 MAPK pathways. Collectively, these findings identify ADAM17 as a druggable target for oncogenic KRAS-driven LAC and provide the rationale to employ ADAM17-based therapeutic strategies for targeting KRAS mutant cancers.

Recent developments and strategies for the discovery of TACE inhibitors

INTRODUCTION

TNF-α plays a central role in certain autoimmune diseases as well as in inflammation. The current strategy for excluding TNF-α from circulation is to selectively inhibit TNF-α converting enzyme (TACE), an enzyme that cleaves mTNF-α to active TNF-α. Various TACE inhibitors have been discovered by using different strategies to control inflammatory diseases, cancer, and cardiac hypertrophy.

AREAS COVERED

The present article summarizes the design and discovery of novel TACE inhibitors that have been reported in the literature since 2012 onwards. It also includes some reports concerning the new role that TACE plays in cancer and cardiac hypertrophy.

EXPERT OPINION

So far, undertaken studies that have looked to design and develop small TACE inhibitors have been discouraging due to the failure of any TACE inhibitors to hit the market. However, some of the latest developments, such as with tartrate-based inhibitors, has given hope to the potentiality of a viable novel selective TACE inhibitor therapeutic in the future. Indeed, some of the novel peptidomimetics and monoclonal antibodies have great potential to pave the way for an effective and safe therapy by selectively inhibiting TACE enzyme.

A Bispecific Inhibitor of the EGFR/ADAM17 Axis Decreases Cell Proliferation and Migration of EGFR-Dependent Cancer Cells

Dysregulated epidermal growth factor receptor (EGFR) is an oncogenic driver of many human cancers, promoting aberrant cell proliferation, migration, and survival. Pharmacological targeting of EGFR is often challenged by acquired mechanisms of resistance. Ligand-dependent mechanisms in EGFR wild-type cells rely on ligand or receptor overexpression, allowing cells to outcompete inhibitors and perpetuate signaling in an autocrine manner. Importantly, EGFR ligands are synthesized as membrane-bound precursors that must be solubilized to enable receptor-ligand interactions. The A disintegrin and metalloproteinase 17 (ADAM17) is considered the main sheddase of several EGFR ligands, and a potential pharmacological target. However, its broad substrate range and ubiquitous expression complicate its therapeutic targeting. Here, we present a novel bispecific fusion protein construct consisting of the inhibitory prodomain of ADAM17 (TPD), fused to an EGFR-targeting designed ankyrin repeat protein (DARPin). TPD is a natural inhibitor of ADAM17, maintaining the protease in a zymogen-like form. Meanwhile, the high affinity anti-EGFR DARPin E01 binds to EGFR and inhibits ligand binding. The resulting fusion protein E01-GS-TPD retained binding ability to both molecular targets EGFR and ADAM17. The large difference in affinity for each target resulted in enrichment of the fusion protein in EGFR-positive cells compared to EGFR-negative cells, suggesting a possible application in autocrine signaling inhibition. Accordingly, E01-GS-TPD decreased migration and proliferation of EGFR-dependent cell lines with no significant increase in apoptotic cell death. Finally, inhibition of proliferation was observed through EGFR ligand-dependent mechanisms as growth inhibition was not observed in EGFR mutant or KRAS mutant cell lines. The use of bispecific proteins targeting the EGFR/ADAM17 axis could be an innovative strategy for the treatment of EGFR-dependent cancers.

Mirolysin structures open a window on gum disease

Guevara, Rodriguez-Banqueri et al. [(2020), IUCrJ, 7, 18-29] determine crystal structures of mirolysin, a metalloprotease that helps oral pathogen Tannerella forsythia evade the human immune response. The structures provide insight into the regulation and specificity of mirolysin, and hint at how it might be inhibited for therapeutic effect.

Potential anti-arthritic and anti-inflammatory effects of TNF-α processing inhibitor-1 (TAPI-1): A new approach to the treatment of S. aureus arthritis

Treatment of septic arthritis has become more challenging due to the rise of multidrug resistant strains of Staphylococcus aureus (S. aureus) in recent years. Failure of antibiotic therapies has compelled to initiate the search for new alternatives. This study aimed to unveil the potential anti-arthritic effects of TAPI-1 (TNF-α processing inhibitor-1), an inhibitor that inhibits TACE (TNF-α converting enzyme) mediated release of soluble TNF-α and its receptors along with attenuation of other inflammatory and joint destructive factors responsible for the progression of arthritis. Male Swiss albino mice were inoculated with live S. aureus (5 × 10⁶ cells/mouse) for the development of septic arthritis. TAPI-1 was administered intraperitoneally (10 mg/kg body weight) post S. aureus infection at regular intervals. Throughout the experiment, the severity of arthritis was obtained to be significantly low after TAPI-1 administration. Arthritis index and histopathology confirmed effectiveness of TAPI-1 in mitigating inflammation induced paw swelling and less bone-cartilage destruction in the arthritic knee joints. Lower levels of soluble tumor necrosis factor alpha (sTNF-α) and soluble tumor necrosis factor alpha receptor-1 (sTNFR-1) were detected in the TAPI-1 treated group suggesting TAPI-1 mediated blocking of TACE with subsequent inhibition of TNF-α signalling. Treatment with TAPI-1 lowered the levels of reactive species; matrix metalloproteinase-2 (MMP-2), receptor activator of nuclear factor kappa-B ligand (RANKL) and osteopontin (OPN) denoting less matrix degradation and less osteoclastic bone resorption. Together, this experimental work authenticates TAPI-1 as an alternative therapeutic intervention for the treatment of S. aureus arthritis.

β7 Integrin Inhibition Can Increase Intestinal Inflammation by Impairing Homing of CD25hiFoxP3+ Regulatory T Cells

BACKGROUND & AIMS

Integrin α4β7 mediates lymphocyte trafficking to the gut and gut-associated lymphoid tissues, a process critical for recruitment of effector lymphocytes from the circulation to the gut mucosa in inflammatory bowel disease (IBD) and murine models of intestinal inflammation. Antibody blockade of β7 integrins generally is efficacious in IBD; however, some patients fail to respond, and a few patients can experience exacerbations. This study examined the effects of loss of β7 integrin function in murine models of IBD.

METHODS

In a mouse IBD model caused by lack of interleukin 10, a cytokine important in CD25hiFoxP3+ regulatory T cell (Treg) function, genetic deletion of β7 integrin or antibody blockade of α4β7-mucosal addressin cell adhesion molecule-1 interaction paradoxically exacerbated colitis.

RESULTS

Loss of β7 impaired the capacity of Tregs homing to the gut and therefore suppress intestinal inflammation in an adoptive T-cell transfer model; however, the intrinsic suppressive function of β7-deficient Tregs remained intact, indicating that the β7 deficiency selectively impacts gut homing. Deletion of β7 integrin did not worsen colitis in an acute dextran sodium sulfate model in which Treg number and function were normal.

CONCLUSIONS

In Integrin subunit beta (Itgb)7-/-Il10-/- mice, loss of β7-dependent Treg homing to gut-associated lymphoid tissues combined with loss of intrinsic Treg function exacerbated intestinal inflammation. These results suggest that IBD patients with reduced CD25hiFoxP3+ Treg numbers or function or lack of interleukin 10 could be at risk for failure of α4β7 blocking therapy.

Regulation of Fibrotic Processes in the Liver by ADAM Proteases

Fibrosis in the liver is mainly associated with the activation of hepatic stellate cells (HSCs). Both activation and clearance of HSCs can be mediated by ligand–receptor interactions. Members of the a disintegrin and metalloprotease (ADAM) family are involved in the proteolytic release of membrane-bound ligands and receptor ectodomains and the remodelling of the extracellular matrix. ADAM proteases are therefore major regulators of intercellular signalling pathways. In the present review we discuss how ADAM proteases modulate pro- and anti-fibrotic processes and how ADAM proteases might be harnessed therapeutically in the future.

ADAM17: An Emerging Therapeutic Target for Lung Cancer

Lung cancer is the leading cause of cancer-related mortality, which histologically is classified into small-cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). NSCLC accounts for approximately 85% of all lung cancer diagnoses, with the majority of patients presenting with lung adenocarcinoma (LAC). KRAS mutations are a major driver of LAC, and are closely related to cigarette smoking, unlike mutations in the epidermal growth factor receptor (EGFR) which arise in never-smokers. Although the past two decades have seen fundamental progress in the treatment and diagnosis of NSCLC, NSCLC still is predominantly diagnosed at an advanced stage when therapeutic interventions are mostly palliative. A disintegrin and metalloproteinase 17 (ADAM17), also known as tumour necrosis factor-α (TNFα)-converting enzyme (TACE), is responsible for the protease-driven shedding of more than 70 membrane-tethered cytokines, growth factors and cell surface receptors. Among these, the soluble interleukin-6 receptor (sIL-6R), which drives pro-inflammatory and pro-tumourigenic IL-6 trans-signaling, along with several EGFR family ligands, are the best characterised. This large repertoire of substrates processed by ADAM17 places it as a pivotal orchestrator of a myriad of physiological and pathological processes associated with the initiation and/or progression of cancer, such as cell proliferation, survival, regeneration, differentiation and inflammation. In this review, we discuss recent research implicating ADAM17 as a key player in the development of LAC, and highlight the potential of ADAM17 inhibition as a promising therapeutic strategy to tackle this deadly malignancy.

Meprin β induces activities of A disintegrin and metalloproteinases 9, 10, and 17 by specific prodomain cleavage

Meprin β is a membrane-bound metalloprotease involved in extracellular matrix assembly and inflammatory processes in health and disease. A disintegrin and metalloproteinase (ADAM)10 and ADAM17 are physiologic relevant sheddases of inactive promeprin β, which influences its substrate repertoire and subsequent biologic functions. Proteomic analysis also revealed several ADAMs as putative meprin β substrates. Here, we demonstrate specific N-terminal processing of ADAM9, 10, and 17 by meprin β and identify cleavage sites within their prodomains. Because ADAM prodomains can act as specific inhibitors, we postulate a role for meprin β in the regulation of ADAM activities. Indeed, prodomain cleavage by meprin β caused increased ADAM protease activities, as observed by peptide-based cleavage assays and demonstrated by increased ectodomain shedding activity. Direct interaction of meprin β and ADAM proteases could be shown by immunofluorescence microscopy and immunoprecipitation experiments. As demonstrated by a bacterial activator of meprin β and additional measurement of TNF-α shedding on bone marrow-derived macrophages, meprin β/ADAM protease interactions likely influence inflammatory conditions. Thus, we identified a novel proteolytic pathway of meprin β with ADAM proteases to control protease activities at the cell surface as part of the protease web.-Wichert, R., Scharfenberg, F., Colmorgen, C., Koudelka, T., Schwarz, J., Wetzel, S., Potempa, B., Potempa, J., Bartsch, J. W., Sagi, I., Tholey, A., Saftig, P., Rose-John, S., Becker-Pauly, C. Meprin β induces activities of A disintegrin and metalloproteinases 9, 10, and 17 by specific prodomain cleavage.