Faecal lysozyme: determination, reference intervals and some data in gastro-intestinal disease

Surrogate Fecal Biomarkers in Inflammatory Bowel Disease: Rivals or Complementary Tools of Fecal Calprotectin?

BACKGROUND

Current noninvasive methods for assessing intestinal inflammation in inflammatory bowel disease (IBD) remain unsatisfactory. Along with C-reactive protein and erythrocyte sedimentation rate, fecal calprotectin (FC) is the standard test for assessing IBD activity, even though its specificity and accuracy are not optimal and it lacks a validated cutoff. Over the past few decades, several fecal markers released from intestinal inflammatory cells have been investigated in IBD; they are the subject of this systematic review.

METHODS

A systematic electronic search of the English literature up to April 2017 was performed using Medline and the Cochrane Library. Only papers written in English that analyzed fecal biomarkers in IBD were included. In vitro studies, animal studies, studies on blood/serum samples, and studies analyzing FC or fecal lactoferrin alone were excluded.

RESULTS

Out of 1023 citations, 125 eligible studies were identified. Data were grouped according to each fecal marker including S100A12, high-mobility group box 1, neopterin, polymorphonuclear neutrophil elastase, fecal hemoglobin, alpha1-antitrypsin, human neutrophil peptides, neutrophil gelatinase-associated lipocalin, chitinase 3-like-1, matrix metalloproteinase 9, lysozyme, M2-pyruvate kinase, myeloperoxidase, fecal eosinophil proteins, human beta-defensin-2, and beta-glucuronidase. Some of these markers showed a high sensitivity and specificity and correlated with disease activity, response to therapy, and mucosal healing. Furthermore, they showed a potential utility in the prediction of clinical relapse.

CONCLUSIONS

Several fecal biomarkers have the potential to become useful tools complementing FC in IBD diagnosis and monitoring. However, wide variability in their accuracy in assessment of intestinal inflammation suggests the need for further studies.

Comparison of 4 neutrophil-derived proteins in feces as indicators of disease activity in ulcerative colitis

BACKGROUND

To evaluate the diagnostic use of fecal concentrations of lactoferrin (Lf), calprotectin (Cal), polymorphonuclear neutrophil-elastase (PMN-e), and lysozyme (Lys) as indicators of disease activity in patients with active and inactive ulcerative colitis (UC).

METHODS

A total of 76 fecal specimens were collected from 31 patients with UC in times of active and inactive status of disease. Disease activity was determined with the colitis activity index (CAI; Rachmilewitz index), which includes a combination of laboratory parameters and clinical symptoms, with a score of at least 6 indicating active disease. Fecal Lf, Cal, PMN-e, and Lys were measured and reported as micrograms per milliliter feces. Levels of more than 7.25, more than 6.00, at least 0.062, and at least 0.6 for Lf, Cal, PMN-e, and Lys, respectively, were considered elevated as specified by the manufacturers.

RESULTS

Based on the CAI classification, 25 of the samples were from patients with active disease status and 51 were from patients with inactive status. Lf, PMN-e, and Cal but not Lys showed increased levels in samples from patients in active disease compared with those in remission (median for Lf: 28.12 +/- 110.86 versus 179.54 +/- 334.09, P < 0.001; median for Cal: 15.13 +/- 30.27 versus 116.23 +/- 182.29, P < 0.001; median for PMN-e: 0.21 +/- 0.44 versus 1.02 +/- 0.89, P < 0.001; median for Lys: 1.54 +/- 2.39 versus 3.75 +/- 5.39, P > 0.05). All 4 parameters correlated with the CAI (Lf: r = 0.441, P < 0.001; Cal: r = 0.505, P < 0.001; PMN-e: r = 0.604, P < 0.001; Lys: r = 0.295, P < 0.05). Introducing a composite index based on Lf, Cal, and PMN-e, the specificity was 72.5% and the sensitivity 88% compared with the CAI.

CONCLUSIONS

Among the neutrophil-derived proteins in feces, PMN-e, Cal, and Lf represent useful markers of disease activity in patients with UC. Using all 3 markers in a composite index may be an additional noninvasive tool for the management of ambulant patients with UC.

Fecal calprotectin levels predict colorectal inflammation among patients with chronic diarrhea referred for colonoscopy

OBJECTIVE

Chronic diarrhea is a relatively common condition with multiple diverse etiologies. Stool testing may serve as a diagnostic aid to discriminate the presence or absence of organic pathology, such as colorectal inflammation. Calprotectin (a leukocyte-derived protein) and hemoglobin can be measured quantitatively from stool and represent candidate inflammation biomarkers. The aim of this study was to assess and compare the screening performance of fecal calprotectin and fecal hemoglobin among colonoscopy referral patients with chronic diarrhea of unknown origin or chronic colitis of unknown activity.

METHODS

All subjects were identified prospectively and each submitted a single stool sample before purgation. Fecal calprotectin (PhiCal; Nycomed Pharma, Oslo, Norway) and fecal hemoglobin (HemoQuant; Mayo Medical Laboratories, Rochester, MN) assays were performed in separate laboratories by masked technicians. Colonoscopic and histological findings served as criterion standards for establishing the presence or absence of colorectal inflammation.

RESULTS

Among 110 subjects who provided complete fecal assay data, 29 (26%) had and 81 (74%) did not have colorectal inflammation. Increased fecal calprotectin levels were significantly (p = 0.0001) associated with the presence of colorectal inflammation, whereas fecal hemoglobin levels were not (p = 0.61). Direct comparison of the fecal assays revealed that calprotectin was a more sensitive biomarker for colorectal inflammation at all specificity levels (p = 0.0001).

CONCLUSIONS

In this study of colonoscopy referral patients, colorectal inflammation was reflected by fecal calprotectin but not by fecal hemoglobin levels. Assay of fecal calprotectin holds promise as a triage tool to identify inflammatory causes of chronic diarrhea.

Monoclonal antibody Adnab-9 defines a preneoplastic marker in epithelium at risk for adenocarcinoma of the small intestine

Unlike colorectal cancer, risk markers for adenocarcinoma of the small intestine (ASI) have not been identified. Because the demographic and pathological features of both of these diseases are similar, immunohistochemistry was performed using monoclonal antibodies for three colonic premalignant markers, Adnab-9 (recognizes a colonic adenoma epitope), CaCo3/61, and FBB2/29 (small intestine proteoglycans expressed ectopically in colonic neoplasms), in normal and neoplastic small intestinal epithelium, and the results were compared with normal controls. Adnab-9 was also examined in 20 familial adenomatous polyposis (FAP) patients, a population known to be at an increased risk for ASI. Immunohistochemistry in normal and neoplastic tissue (adenoma, adenocarcinoma) from 18 patients with primary adenocarcinoma of the small intestine was compared with normal small intestine from 10 nonneoplastic controls. Four of 10 (40%) cases of normal small intestinal epithelium from controls were mildly positive in less than 10% of crypts, versus strong staining (>50% of crypts) in 16 of 18 (89%) patients with adenocarcinoma, and in 17 of 20 (85%) patients with FAP (P<.05). Adnab-9 predominantly stained Paneth cells as well as rare crypt and basal villous goblet cells. Adenomatous epithelium from the adenocarcinoma cases and adenomas from the FAP patients showed staining of Adnab-9 in 63% and 78% of cases, respectively. Only 17% of adenocarcinomas were positive for Adnab-9. In contrast, neither CaCo3/61 nor FBB2/29 showed any significant differences in the degree of staining in normal small intestinal epithelium in patients with adenocarcinoma compared with controls. Enhanced Adnab-9 staining in normal small intestinal epithelium from patients who harbor adenocarcinoma, and in FAP patients, supports its role as a risk marker of small intestinal neoplasia.

Up-regulation of lysozyme production in colonic adenomas and adenocarcinomas

AIMS

The presence of lysozyme protein in some gastric adenomas and adenocarcinomas has been well documented. There have been relatively few studies investigating the presence of lysozyme in tumours of the large intestine and they show contrasting results. We aim to investigate the cellular source and expression of lysozyme in colonic adenomas and adenocarcinomas.

METHODS AND RESULTS

We randomly selected 29 and 27 colonic adenomas and adenocarcinomas, respectively. Using in-situ hybridization (ISH) and immunohistochemistry (IHC), we found an up-regulation of lysozyme in the dysplastic epithelium of all the adenomas studied, with more than 80% of cases expressing moderate to strong signals. Although the up-regulation of lysozyme was also observed in adenocarcinomas, only 30% of the cases showed moderate to strong signals, mostly with an uneven distribution. Down-regulation of lysozyme in the severely dysplastic and invasive foci were noted in some cases of adenoma with malignant transformation. Normal colonic glands were consistently negative for lysozyme at both the mRNA and the protein level, but inflamed and immature regenerative colonic epithelium at the crypt base showed positive signals in a similar pattern to those observed in the dysplastic epithelium of the adenomas.

CONCLUSIONS

Our results confirm that colonic epithelium can produce lysozyme and its expression is up-regulated in the dysplastic epithelium in adenomas and in invasive cancer cells. It is interesting that regenerative colonic epithelium showed a similar pattern of lysozyme expression as in adenomas. The loss of lysozyme secreting phenotype in most of the invasive tumours suggests that lysozyme may not confer an advantage to tumour progression.

Early detection of anastomotic leaks after low anterior resection of the rectum

PURPOSE

Lysozyme destroys the mucopolysaccharide chains of the cell wall of gram-negative bacteria. It is a component of local defense and is formed in macrophages. Determination of lysozyme content in the wound seems to be the most reliable method for early recognition of wound infection.

METHODS

In a prospective randomized study on the efficacy of single vs. double staple technique in anterior rectum resection, the effluent from the pelvic drain was examined with regard to its lysozyme activity.

RESULTS

Lysozyme activity in drained secretion remained stable for more than 24 hours at room temperature. When the single staple technique was used, enzyme activity was sharply increased (mean, 9.6 mg/dl on the first postoperative day) compared with the double staple technique (mean, 5.5 mg/dl on the first postoperative day). The difference was statistically significant (P < 0.0001). Mean lysozyme activity was increased in those patients with clinically (18 mg/dl on the first postoperative day) and radiologically (15.3 mg/dl on the first postoperative day) detected dehiscence (P < 0.0001).

CONCLUSION

Lysozyme determination may be reproduced by detection of enzyme stability in drained secretion. Determination of lysozyme content seems to be a new possibility for early recognition of anastomotic dehiscence.

Solid-phase competitive luminescence immunoassay for lysozyme in faeces

We have developed a new simple solid-phase luminescence immunoassay (LIA) for the determination of faecal lysozyme. The assay utilises a polyclonal capture antibody coated to polystyrene beads and acridinium ester-labelled human lysozyme as tracer. Samples are incubated with polystyrene beads and tracer overnight at 4 degrees C. After a thorough washing step, emitted light is measured by an automated luminometer for 2 seconds. The standard curve uses five standards ranging from 0.025 to 6.4 mg/l. The method has a sensitivity of 0.02 mg/l. Dilution recoveries for three samples were 88, 104 and 108%. Intraassay coefficients of variation (CV, n = 24) were 10.1% and 11.7% for a healthy control and a patient sample; interassay CV (n = 16) were 6.7% and 13.1% for the same healthy control but another patient sample. The normal range of faecal lysozyme in 80 healthy controls was found to be 0.02-1 mg/l (97.5 percentile) with a median of 0.28 mg/l. Fifty-three patients with Crohn's disease had faecal lysozyme values ranging from 0.16 to 100.7 mg/l with a median of 1.75 mg/l, and 30 patients with ulcerative colitis showed levels between 0.09 and 118 mg/l with a median of 1.11 mg/l. The assay has proved useful for differentiating healthy individuals from those with inflammatory bowel disease and might be a valuable tool for diagnosing or evaluating inflammatory bowel disease.

Mucosal origin and shedding of an early colonic tumor marker defined by Adnab-9 monoclonal antibody

Recent attention has been drawn to the diagnostic potential of tests based on shed colonic tumor markers. Adnab-9 monoclonal antibody raised against neoplastic, potentially premalignant colonic adenomas recognizes a marker in colonic effluent or tissue which correlates with the presence of tumors or risk of colorectal cancer. The origin of this antigen and optimal collection of colonic effluent were investigated by enzyme-linked immunosorbent assay and Western blotting. Mean Adnab-9 binding in effluent samples from colorectal cancer patients even after resection is high as compared with that in normal subjects (P < 0.05). Effluent samples are best collected in the morning hours. Antigen proteolysis may be significant depending on the site and timing of effluent collection, but breakdown products are reactive. Tissue and effluent Adnab-9 binding at any one anatomic site of collection appear to correlate (r = 0.88, P = 0.01). The Adnab-9 antigen is constitutively expressed at low levels throughout the distal bowel and localized to the deepest regions of the mucosal crypts. Other than meconium, no significant levels of binding are found in other body fluids. This antigen is specific for the gastrointestinal tract, its binding in conveniently collected effluent samples correlates with tissue content, and the antigen is constitutively expressed in the crypts of the distal small bowel and colonic mucosa.