Chemotactic peptide-induced acute colitis in rabbits

The formyl peptide fMLF primes platelet activation and augments thrombus formation

Essentials The role of formyl peptide receptor 1 (FPR1) and its ligand, fMLF, in the regulation of platelet function, hemostasis, and thrombosis is largely unknown. Fpr1-deficient mice and selective inhibitors for FPR1 were used to investigate the function of fMLF and FPR1 in platelets. N-formyl-methionyl-leucyl-phenylalanine primes platelet activation and augments thrombus formation, mainly through FPR1 in platelets. Formyl peptide receptor 1 plays a pivotal role in the regulation of platelet function.

BACKGROUND

Formyl peptide receptors (FPRs) play pivotal roles in the regulation of innate immunity and host defense. The FPRs include three family members: FPR1, FPR2/ALX, and FPR3. The activation of FPR1 by its high-affinity ligand, N-formyl-methionyl-leucyl-phenylalanine (fMLF) (a bacterial chemoattractant peptide), triggers intracellular signaling in immune cells such as neutrophils and exacerbates inflammatory responses to accelerate the clearance of microbial infection. Notably, fMLF has been demonstrated to induce intracellular calcium mobilization and chemotaxis in platelets that are known to play significant roles in the regulation of innate immunity and inflammatory responses. Despite a plethora of research focused on the roles of FPR1 and its ligands such as fMLF on the modulation of immune responses, their impact on the regulation of hemostasis and thrombosis remains unexplored.

OBJECTIVE

To determine the effects of fMLF on the modulation of platelet reactivity, hemostasis, and thrombus formation.

METHODS

Selective inhibitors for FPR1 and Fpr1-deficient mice were used to determine the effects of fMLF and FPR1 on platelets using various platelet functional assays.

RESULTS

N-formyl-methionyl-leucyl-phenylalanine primes platelet activation through inducing distinctive functions and enhances thrombus formation under arterial flow conditions. Moreover, FPR1 regulates normal platelet function as its deficiency in mouse or blockade in human platelets using a pharmacological inhibitor resulted in diminished agonist-induced platelet activation.

CONCLUSION

Since FPR1 plays critical roles in numerous disease conditions, its influence on the modulation of platelet activation and thrombus formation may provide insights into the mechanisms that control platelet-mediated complications under diverse pathological settings.

The Formyl Peptide Receptors: Diversity of Ligands and Mechanism for Recognition

The formyl peptide receptors (FPRs) are G protein-coupled receptors that transduce chemotactic signals in phagocytes and mediate host-defense as well as inflammatory responses including cell adhesion, directed migration, granule release and superoxide production. In recent years, the cellular distribution and biological functions of FPRs have expanded to include additional roles in homeostasis of organ functions and modulation of inflammation. In a prototype, FPRs recognize peptides containing N-formylated methionine such as those produced in bacteria and mitochondria, thereby serving as pattern recognition receptors. The repertoire of FPR ligands, however, has expanded rapidly to include not only N-formyl peptides from microbes but also non-formyl peptides of microbial and host origins, synthetic small molecules and an eicosanoid. How these chemically diverse ligands are recognized by the three human FPRs (FPR1, FPR2 and FPR3) and their murine equivalents is largely unclear. In the absence of crystal structures for the FPRs, site-directed mutagenesis, computer-aided ligand docking and structural simulation have led to the identification of amino acids within FPR1 and FPR2 that interact with several formyl peptides. This review article summarizes the progress made in the understanding of FPR ligand diversity as well as ligand recognition mechanisms used by these receptors.

Development of small molecule non-peptide formyl peptide receptor (FPR) ligands and molecular modeling of their recognition

Formyl peptide receptors (FPRs) are G protein-coupled receptors (GPCRs) expressed on a variety of cell types. These receptors play an important role in the regulation of inflammatory reactions and sensing cellular damage. They have also been implicated in the pathogenesis of various diseases, including neurodegenerative diseases, cataract formation, and atherogenesis. Thus, FPR ligands, both agonists and antagonists, may represent novel therapeutics for modulating host defense and innate immunity. A variety of molecules have been identified as receptor subtype-selective and mixed FPR agonists with potential therapeutic value during last decade. This review describes our efforts along with recent advances in the identification, optimization, biological evaluation, and structure-activity relationship (SAR) analysis of small molecule non-peptide FPR agonists and antagonists, including chiral molecules. Questions regarding the interaction at the molecular level of benzimidazoles, pyrazolones, pyridazin-3(2H)-ones, N-phenylureas and other derivatives with FPR1 and FPR2 are discussed. Application of computational models for virtual screening and design of FPR ligands is also considered.

Guinea pig ileum motility stimulation elicited by N-formyl-Met-Leu-Phe (fMLF) involves neurotransmitters and prostanoids

In guinea-pig ileum (GPI), the chemotactic peptide N-formyl-Met-Leu-Phe-OH (fMLF) possesses spasmogenic properties through the activation of formyl peptide receptors (FPRs). Despite this, the mediators involved remain to be elucidated. fMLF (1nM-1μM) induced a dose-dependent contraction of GPI (EC(50)=24nM), that is blocked by pre-treatment with the FPRs antagonist Boc(2). The pre-treatment with tetrodotoxin (TTX) atropine or with SR140333 reduced the fMLF-induced contraction, whereas with hexamethonium, MEN10627, SB222200, mepyramine, cimetidine, thioperamide or methysergide did not produce any effect. With DuP697 pre-treatment, but not with piroxicam, reduced the fMLF-induced contraction. After stimulation with 24nM fMLF, a strong increase in the PGE(2) levels was observed. Finally, the concomitant blocking of the NK(1) receptor, the muscarinic receptors and COX-2 abolished the GPI contractions induced by fMLF. fMLF induced a concentration-dependent contraction of guinea-pig jejunum (EC(50)=11nM), proximal colon (EC(50)=3.5nM) and distal colon (EC(50)=2.2nM), with a time-course similar to that observed in GPI. In these preparations as well, the co-administration of atropine, SR140333 and DuP697 abolished the contractions induced by fMLF. Intraperitoneal injection of fMLF (0.1 or 1μmol/kg) enhanced the gastrointestinal motility in mice, abolished by the co-administration of atropine, SR140333 and DuP697. In conclusion, we showed that fMLF exerts spasmogenic actions on guinea-pig intestine both in vitro and in vivo through the release of acetylcholine and substance P from myenteric motorneurons and through prostanoids, probably from the inflammatory cells of the enteric immune system.

fMLP induces Hsp27 expression, attenuates NF-kappaB activation, and confers intestinal epithelial cell protection

Sustained expression of cytoprotective intestinal epithelial heat shock proteins (Hsps), particularly Hsp27, depends on stimuli derived from bacterial flora. In this study, we examined the role of the bacterial chemotactic peptide fMLP in stimulating colonic epithelial Hsp expression at concentrations encountered in a physiological milieu. Treatment of the polarized human intestinal epithelial cell line Caco2bbe with physiological concentrations of fMLP (10-100 nM) induced expression of Hsp27, but not Hsp72, in a time- and concentration-dependent manner. Induction of Hsp27 by fMLP was specific since the fMLP analogs MRP and MLP were not effective. Hsp27 induction by fMLP was blocked by the fMLP-receptor antagonist BOC-FLFLF and was blocked when the dipeptide transporter PepT1, an entry pathway for fMLP, was silenced. fMLP activated both the p38 and ERK1/2 MAP kinase pathways in Caco2bbe cells, but not the SAPK/JNK pathway. The p38 inhibitor SB203580, but not the MEK-1 inhibitor PD98059, blocked Hsp27 induction by fMLP. fMLP treatment inhibited actin depolymerization and decreased transepithelial resistance caused by the oxidant monochloramine, and this inhibition was reversed by silencing Hsp27 expression. fMLP pretreatment also inhibited activation of proinflammatory transcription factor NF-kappaB by TNF-alpha in Caco2bbe cells, reducing induction of NF-kappaB target genes by TNF-alpha both in human intestinal biopsies and Caco2bbe cells. In conclusion, fMLP may contribute to the maintenance of intestinal homeostasis by mediating physiological expression of Hsp27, enhancing cellular protection, and negatively regulating the inflammatory response.

Crohn's disease and Escherichia coli. A new approach in therapy to maintain remission of colonic Crohn's disease?

Involvement of pathogenic or potentially pathogenic bacteria in the pathogenesis of inflammatory bowel disease has long been suggested because, among other reasons, the inflammatory response resembles that in infectious bowel diseases. Elevated antibody levels to pathogen antigens and a changed metabolic activity of the intestinal microflora have been detected in patients with Crohn's disease. Several studies have revealed a possible etiologic link between intestinal microorganisms and inflammatory bowel disease. Therefore, several therapeutic strategies, including reduction or dilution of bacterial components in the intestine by antibiotics or intestinal lavage, respectively, inactivation of inflammatory bacterial products, and reconstitution of intestinal microflora have been employed, substantiating the idea that dysfunction of the intestinal mucosal barrier and an alteration of bacterial composition contribute to the inflammatory disease. However, the beneficial effect of restoration of the physiologic intestinal microflora in colonic inflammation by exogenous administration of a viable nonpathogenic bacterium has not been investigated before in a placebo-controlled study. Promising results came from the present pilot study in which the nonpathogenic Escherichia coli strain Nissle 1917 was tested for efficacy and tolerance in maintaining remission in patients with colonic Crohn's disease. Application of the physiologic bacteria reduced the risk for relapse and minimized the need for glucocorticoids. Therefore we are convinced that in Crohn's disease parts of the intestinal microflora, including the host's immune response toward indigenous flora or an impairment of the gut flora's metabolic activity are involved in the development or at least in the onset of relapse from remissive of colonic Crohn's disease. However, more data are necessary to prove the benefit of E. coli strain Nissle 1917 as a new therapy to maintain remission of colonic Crohn's disease.

Presence of immunocytes and sulfidopeptide leukotrienes in the inflamed guinea pig distal colon

This study examined whether the immunocyte recruitment associated with a mild inflammatory state induced by acetic acid would produce detectable sulfidopeptide leukotriene (LT) levels from colonic tissues or in dialysates. Histological examination and measurements of peroxidase activities of inflamed tissues indicated edema, hyperplasia and neutrophil infiltration. Significant elevated LTB4 and prostaglandin E2(PGE2) levels were found but only slight elevations in sulfidopeptide LTs occurred. A slight elevation in eosinophil peroxidase indicated that eosinophil infiltration also occurred. The increase in sulfidopeptide LT levels appeared insufficient by itself to alter secretory responses in the distal colon. However, combined with other immunocyte products such as PGs, the sulfidopeptide LTs may influence the symptomology of inflammatory bowel disease.

Eicosanoids and the gastrointestinal tract

Determining the role of eicosanoids in gastrointestinal physiology and pathophysiology has been an active area of investigation over the past 20 years. The landmark discovery of prostaglandin endoperoxide synthase and other enzymes involved in the production of arachidonic acid products (lipoxygenases and epoxygenases) ushered in a new era of research. The goal of this review is to distill a large body of work pertaining to studies of eicosanoids in the gastrointestinal tract. This review has been organized according both to functional (secretion and motility) and disease-related (inflammation, mucosal injury, and neoplasia) effects. The aim of this article is to present a clear summary of this area of gastroenterology so that future research can be directed in a logical and productive manner.

Significance of systemic endotoxaemia in inflammatory bowel disease

Quantitative and qualitative disturbances in faecal flora suggest a role for enteric bacteria and their products in the pathogenesis of inflammatory bowel disease (IBD). This study investigated the hypothesis that systemically circulating endotoxins are of pathogenic significance in IBD by measuring antibody, cytokine, and acute phase protein responses. Systemic endotoxaemia was found in 88% patients with ulcerative colitis (n = 25) and 94% with Crohn's disease (n = 31) during clinical relapse. Systemic endotoxaemia correlated positively with anatomic extent and clinical activity of ulcerative colitis. Circulating tumour necrosis factor (TNF) was detected in 40% of patients with ulcerative colitis and 45% with Crohn's disease. Plasma TNF concentrations correlated with clinical and laboratory measures of disease activity and were associated with a surgical outcome to the disease episode. Plasma soluble TNF receptor p55 concentration correlated positively with disease activity and endotoxin core antibody concentrations. Plasma IgG endotoxin core antibody concentrations were significantly increased in patients with Crohn's disease and correlated with systemic endotoxaemia. The presence of systemic endotoxaemia, its correlation with disease activity, disease extent, and endotoxin core antibody concentration and the detection of circulating TNF and soluble TNF receptors all support a pathogenic role for endotoxins in IBD.

Eicosanoid production by a differentiated canine colonic epithelial cell line, VNCC

BACKGROUND/AIMS

The lack of pure, proliferative, but not transformed intestinal epithelial cells has impeded progress in understanding their role in chronic intestinal inflammation. To clarify that role, the present study characterized the epithelial cell line VNCC, derived from normal adult dog distal colon.

METHODS

Cells were cultured on plastic and permeable supports for analysis of eicosanoid production (by radioimmunoassay and high-performance liquid chromatography) and transport characteristics (by Ussing chamber short-circuit determinations).

RESULTS

In culture, VNCC formed confluent monolayers and domes, suggesting formation of tight junctions and active solute absorption. When cultured on permeable supports, VNCC developed modest, but variable, transepithelial resistances (563 +/- 94 omega/cm2) with a spontaneous short-circuit current of 5.0 +/- 0.4 microA/cm2. Forskolin caused a prolonged increase in the short-circuit current, inhibited by amiloride but not bumetanide, suggesting that VNCC display 5'-cyclic adenosine monophosphate-stimulated sodium absorption. VNCC incubated with arachidonic acid released a variety of eicosanoids including 6-keto-prostaglandin (PG)F1 alpha, PGE2, thromboxane B2, and PGF2 alpha, but no hydroxyarachidonate metabolites. Bradykinin stimulated VNCC eicosanoid release.

CONCLUSIONS

The ability of VNCC to divide and differentiate in culture, to form polarized monolayers capable of active sodium absorption, and to respond to inflammatory mediators with eicosanoid release makes them a unique tool for the study of the interactions of inflammation on colonocyte function.

Review article: thromboxanes in inflammatory bowel disease--pathogenic and therapeutic implications

Recent work suggests that thromboxanes may play a major pathogenic role in inflammatory bowel disease. Thromboxanes are produced in excess not only in inflamed mucosa but also in Crohn's disease, by uninflamed bowel and by isolated intestinal and peripheral blood mononuclear cells. Their cellular source is likely to include platelets, neutrophils, endothelial and epithelial cells as well as mononuclear cells, possible stimuli to their overproduction being chemotactic peptides, lipopolysaccharide, leukotrienes, platelet activating factor, interleukin-1, bradykinin and angiotensin II. The pro-inflammatory effects of thromboxanes are both direct (diapedesis and activation of neutrophils, mucosal ulceration, reduction of suppressor T-cell activity) and indirect (vasoconstriction, platelet activation). Although corticosteroids and aminosalicylates inhibit thromboxane synthesis, this action does not necessarily explain their therapeutic effect in inflammatory bowel disease. Selective thromboxane synthesis inhibitors and receptor antagonists, however, ameliorate experimental colitis in animals. Picotamide and ridogrel are dual thromboxane pathway blockers already used in man. Drugs of this type could prove useful not only for the prevention of systemic thrombo-embolism but also for suppressing intestinal mucosal inflammation in patients with inflammatory bowel disease.

Review article: the mode of action of the aminosalicylates in inflammatory bowel disease

Sulphasalazine and other 5-aminosalicylic acid (5-ASA)-containing drugs are used in the treatment of acute inflammatory bowel disease and in the maintenance of clinical remission. Despite their use for over 50 years, the mechanism of action of this class of drugs remains uncertain, although a number of possibilities are discussed in this review. It seems likely that the aminosalicylates are important free radical scavengers, can reduce leukotriene production and can inhibit the cellular release of interleukin-1, all of which are likely to be important in reducing the acute inflammatory response in inflammatory bowel disease. The effects of these drugs on prostaglandin production are more contentious, but it appears that 10(-5) to 10(-4) M concentrations stimulate production of prostaglandins which may be cytoprotective, while higher doses of these drugs inhibit prostaglandin production. The aminosalicylates may maintain remission in inflammatory bowel disease by preventing leucocyte recruitment into the bowel wall. The drugs inhibit the chemotactic response to leukotriene B4, reduce the synthesis of platelet activating factor and also inhibit leucocyte adhesion molecule upregulation.

Increased absorption of polyethylene glycol 600 deposited in the colon in active ulcerative colitis

A defect in the barrier function of the intestinal mucosa has been proposed as important in both the pathogenesis and systemic manifestations of inflammatory bowel disease. After colonoscopy, polymers of polyethylene glycol (PEG) with molecular weights of 414-810 (mean 600), were instilled in the descending colon of patients with ulcerative colitis (n = 17) and in controls without intestinal inflammation (n = 8). The patients with active ulcerative colitis (n = 6) had a significantly increased uptake of PEGs in the molecular weight range 458-810, measured as urinary excretion over the first 6 hours after instillation. The median values for their excretion were 2.85-3.80% of PEGs instilled compared with 0.32-0.94% for patients in remission (n = 11) (p < 0.05-0.01) and 0.17-0.60% for the controls (p < 0.05-0.01). The differences in absorption of PEG 414 did not reach the present level of statistical significance. There was a positive correlation between PEG absorption and the endoscopic and histological grading of inflammatory activity in the sigmoid colon (p < 0.01-0.001). These findings support a correlation between the presence of active inflammation and PEG absorption. There was little evidence to support the presence of a primary defect in the colonic barrier in patients with ulcerative colitis.

Rabbit gut permeability in response to histamine chloramines and chemotactic peptide

Granulocyte-derived chlorinated amines and bacterial formyl peptides are thought to enhance epithelial permeability. In the current study, gut permeability to [51Cr]ethylenediaminetetraacetic acid (EDTA) was monitored in response to luminal formyl-methionyl-leucyl-phenylalanine (fMLP) and histamine monochloramine and dichloramine. Responses were determined in rabbits during states of basal and elevated permeability. Luminal fMLP had minimal effects of gut permeability in control and injured states. Histamine monochloramine or dichloramine enhanced epithelial permeability under basal conditions; this effect was exaggerated by a pre-existing injury. Both histamine monochloramine and dichloramine retained full histamine agonist properties, and a combination of antioxidant and antihistamine therapy was required to block this increase in gut permeability. Whereas histamine chloramines caused a dose-dependent cytotoxicity in rat-cultured enterocytes, marked histological changes to the mucosa were not evident, nor were mucosal glutathione levels depleted. As histamine chloramines retain the histaminergic and oxidizing potential of their precursors, they represent a unique form of inflammatory mediator, although their highly reactive nature precludes in vivo confirmation of their formation.

Neutrophil recruitment to the gastrointestinal tract

The infiltration of an organ or tissue by neutrophils is the hallmark of acute inflammation. Recent work from many laboratories suggests that neutrophils may play a role in the development of tissue injury in a variety of disease states in the gastrointestinal tract. These diseases include gastritis, necrotizing enterocolitis, ileitis, ulcerative colitis, and ischemia reperfusion injuries. In view of this recent interest in the neutrophil and its relationship to GI diseases, it seems timely to review what is known about neutrophil recruitment to the gastrointestinal tract. This review will therefore focus on the sojourn of the neutrophil from the circulation to its destination in the GI tract.

Chemiluminescence assay of mucosal reactive oxygen metabolites in inflammatory bowel disease

Previous studies suggesting increased reactive oxygen metabolite (ROM) production in inflammatory bowel disease have been restricted to peripheral blood and isolated intestinal phagocytes. In the current study, chemiluminescence and the effect of various scavengers, enzymes, and enzyme inhibitors were used to show that ROMs account for the increased production of oxidants by colorectal mucosal biopsy specimens in inflammatory bowel disease. Luminol-amplified chemiluminescence was increased in active ulcerative colitis [macroscopic grade 1: 25 photons.mg-1.min.10(-3) (median), 8-47 (95% confidence intervals), n = 40; grade 2: 89, 65-156, n = 30; grade 3: 247, 133-562, n = 13] and Crohn's disease [mild: 9, 3-84, n = 6; severe: 105, 25-789 (range), n = 5] compared with normal-looking mucosa (ulcerative colitis: 0.8, 0.4-1.4, n = 22, P less than 0.01; Crohn's disease: 0.8, 0.1-2, n = 6, P less than 0.05) and controls (0.6, 0.04-1.4, n = 52, P less than 0.01). In ulcerative colitis, luminol chemiluminescence correlated with microscopic inflammation (Spearman's p = 0.74, P = 0.0001) and was decreased by sodium azide (-89%, P less than 0.05), taurine (-31%, P less than 0.05), catalase (-23%, P less than 0.05), and dimethyl sulfoxide (-29%, P less than 0.05). Superoxide dismutase and oxypurinol decreased lucigenin chemiluminescence in ulcerative colitis by -63% (P less than 0.05) and -27% (P less than 0.05), respectively. Luminol chemiluminescence correlated with lucigenin chemiluminescence (Spearman's rho = 0.72, P = 0.003). These results suggest that neutrophil-derived oxidants (superoxide, hydrogen peroxide, hydroxyl radical, and hypochlorite) are generated in colorectal mucosa in active inflammatory bowel disease and support the hypothesis that production of such metabolites by neutrophils is of major pathogenetic importance.

Experimental colitis in animal models

Colitis may be induced in animals by oral administration of sulfated polysaccharides (carrageenan, amylopectin sulfate, dextran sulfate), chemical irritation by rectal instillation of diluted acetic acid, delayed hypersensitivity reaction after sensitization to DNCB or after one single administration of TNBS, and Arthus reaction induced by intravenous injection of immune complexes after chemical irritation of the colon, and by chemoattractant peptides such as FMLP. It appears that all models of colon inflammation in the rat, mouse, or rabbit produce increased amounts of eicosanoids similar to that found in human colitis. Thus, animal studies provide useful information on the origin, regulation, and function of inflammatory mediators. However, with the possible exception of the cotton-top tamarin, no animal model of induced or spontaneous inflammation of the colon is analogous to human ulcerative colitis in etiology, course of disease activity, or histology (114). The observation that two different immune-mediated models gave similar results suggests that the colitis is not a specific response to delayed-type hypersensitivity or immune-complex-mediated reactions but rather an unspecific, stereotype response (125). The original disturbance may not determine the nature of the lesions ultimately produced but may instead serve as an initiator of a final common immunologic pathway.

Inflammatory bowel disease. Part I: Nature and pathogenesis

Once regarded as medical curiosities, ulcerative colitis and Crohn's disease have achieved a remarkable change in status recently and today are among the more compelling of all human illnesses. The cause(s) of inflammatory bowel disease (IBD) are not known. Genetic, environmental, microbial, and immunologic factors are involved, but the precise mechanisms are obscure. The incidence of ulcerative colitis is relatively stable, while Crohn's disease continues to increase in frequency. In 10% to 15% of patients, it is hard to differentiate between ulcerative colitis and Crohn's colitis; however, problems with diagnosis usually resolve with time and repeated examinations. In part I of his two-part monograph on IBD, Dr. Kirsner addresses the nature and pathogenesis of the disease. Increased study of ulcerative colitis and Crohn's disease in recent years has generated new knowledge regarding their etiology. Part I focuses on microbial, immunologic, and genetic mechanisms and the inflammatory processes involved in the disease. In part II, which will be presented in next month's issue of Disease-a-Month, Dr. Kirsner deals with the clinical features, course, and management of IBD, based on the author's 55 years of experience with these problems and supplemented by critical examination of the recent (1988-1990) literature. Particular attention is directed to the symptoms and physical findings of ulcerative colitis and Crohn's disease, the laboratory, radiologic, endoscopic, and pathologic features, and the many systemic complications. The IBDs are mimicked by several enterocolonic infections and other conditions, making differential diagnosis necessary. Inflammatory bowel disease in children and the elderly conforms to conventional clinical patterns modified by the health circumstances of the respective age groups. Because the cause of IBD has not been established, current medical therapy is facilitative and supportive rather than curative. The principles of medical treatment are approximately the same for ulcerative colitis and Crohn's disease. Treatment emphasizes a program rather than a drug and also considers the individuality of the therapeutic response. A clearer understanding of dietary and nutritional needs, including hyperalimentation and electrolyte and fluid balance, aids treatment. Antidiarrheal and antispasmodic preparations and sedatives are prescribed for symptom relief. The bowel inflammation is controlled with sulfasalazine or the newer 5-amino salicylic acid (5-ASA) compounds, antibacterial drugs for complications of Crohn's disease and IBD, adrenocortical steroids, and the immunosuppressive compounds 6-mercaptopurine (6-MP), azathioprine, and cyclosporine, as determined in each patient. The surgical procedures available for treatment of ulcerative colitis include total proctocolectomy and ileostomy or ileoanal anastomosis.(ABSTRACT TRUNCATED AT 400 WORDS)