Functional and clinical aspects of the myelomonocyte protein calprotectin

Development of Luminescent Biosensors for Calprotectin

Calprotectin, a metal ion-binding protein complex, plays a crucial role in the innate immune system and has gained prominence as a biomarker for various intestinal and systemic inflammatory and infectious diseases, including inflammatory bowel disease (IBD) and tuberculosis (TB). Current clinical testing methods rely on enzyme-linked immunosorbent assays (ELISAs), limiting accessibility and convenience. In this study, we introduce the Fab-Enabled Split-luciferase Calprotectin Assay (FESCA), a novel quantitative method for calprotectin measurement. FESCA utilizes two new fragment antigen binding proteins (Fabs), CP16 and CP17, that bind to different epitopes of the calprotectin complex. These Fabs are fused with split NanoLuc luciferase fragments, enabling the reconstitution of active luciferase upon binding to calprotectin either in solution or in varied immobilized assay formats. FESCA's output luminescence can be measured with standard laboratory equipment as well as consumer-grade cell phone cameras. FESCA can detect physiologically relevant calprotectin levels across various sample types, including serum, plasma, and whole blood. Notably, FESCA can detect abnormally elevated native calprotectin from TB patients. In summary, FESCA presents a convenient, low-cost, and quantitative method for assessing calprotectin levels in various biological samples, with the potential to improve the diagnosis and monitoring of inflammatory diseases, especially in at-home or point-of-care settings.

A critical role for iron and zinc homeostatic systems in the evolutionary adaptation of Escherichia coli to metal restriction

Host nutritional immunity utilizes metal deprivation to help prevent microbial infection. To investigate bacterial adaptation to such restrictive conditions, we conducted experimental evolution with two metal sequestering agents. Ethylenediaminetetraacetic acid (EDTA) and diethylenetriamine pentamethylene phosphonic acid (DTPMP) were selected as ligands because they differentially affect cellular levels of iron, manganese and zinc in Escherichia coli. Mutants of E. coli strain BW25113 were isolated after cultivation at sub-minimum inhibitory concentration (MIC) chelant levels and genetic changes potentially responsible for tolerance were identified by whole-genome sequencing. In EDTA-selected strains, mutations in the promoter region of yeiR resulted in elevated gene expression. The yeiR product, a zinc-specific metallochaperone, was confirmed to be primarily responsible for EDTA resistance. Similarly, in two of the DTPMP-selected strains, a promoter mutation increased expression of the fepA-entD operon, which encodes components of the ferric-enterobactin uptake pathway. However, in this case improved DTPMP tolerance was only detectable following overexpression of FepA or EntD in trans. Additional mutations in the cadC gene product, an acid-response regulator, preserved the neutrality of the growth medium by constitutively activating expression of the cadAB regulon. This study uncovers specific resistance mechanisms for zinc and iron starvation that could emerge by selection against host nutritional immunity or competition with heterologous metallophores. It also provides insight into the specific metals affected by these two widely used chelators critical for their antibacterial mode of action.

Serum calprotectin as a marker of neonatal sepsis: a hospital-based cross-sectional diagnostic study

Background

Despite significant advances in neonatal care, neonatal sepsis remains a major contributor to mortality, morbidity, and protracted hospitalization. The development of early possible diagnostic indicators for newborn sepsis is critical. Since calprotectin participates in major biological processes, it could be a diagnostic marker for infection/inflammation. This study aimed to estimate serum calprotectin in neonates with clinical sepsis. In addition, we compared serum calprotectin with standard sepsis markers and serum procalcitonin to evaluate its diagnostic accuracy.

Methods

A hospital-based cross-sectional diagnostic study of neonates identified with clinical sepsis using standard criteria was carried out. We compared estimated serum calprotectin levels to serum procalcitonin levels and conventional sepsis markers (leucocyte count, blood culture, immature to total neutrophil ratio, and C- reactive protein). We used SPSS version 25 to analyze the data. To examine diagnostic accuracy and determine a cut-off value for serum calprotectin, we used the receiver operating characteristics (ROC) curve.

Results

Of the 83 subjects included, 36.5% (30/83) had blood culture positive status, the median value of serum calprotectin being 0.93 ng/ml (0.67 to 1.3). Respiratory, cardiovascular, and gastrointestinal instabilities were present in 67.5% (56/83), 59% (49/83), and 50.1% (42/83) cases, respectively. The median values of serum calprotectin, procalcitonin, TLC, and I/T ratio between neonates withpositive blood culturesand negative culturesdid not differ significantly.. On ROC, calprotectin was not predictive for blood culture positivity (sensitivity: 50%; specificity: 44% at 0.83 ng/ml of serum calprotectin) and C-reactive protein (CRP) levels (sensitivity: 57%; specificity: 67% at serum calprotectin levels of 0.89 ng/ml). However, compared with serum procalcitonin, serum calprotectin at 1.2 ng/ml had sensitivity and specificity of 60% and 73%, respectively.

Conclusions

Serum calprotectin did not show a distinct advantage over the existing sepsis markers. Serum calprotectin level at 1.2 ng/ml had a sensitivity and specificity of 60% and 73%, respectively, compared to serum procalcitonin in detecting neonatal sepsis.

Fecal calprotectin level as a marker of esophageal varices in Egyptian HCV cirrhotic patients

INTRODUCTION AND AIM

Esophageal varices are one of the complications of portal hypertension in cirrhotic patients that lead to high morbidity and mortality. Our aim was to assess the fecal calprotectin (FC) level in Egyptian cirrhotic patients as a non-invasive marker for the presence of esophageal varices.

MATERIALS AND METHODS

The current study included 250 participants in the period from June 2019 to November 2020, divided into three groups: group 1: 100 HCV cirrhotic patients with esophageal varices that would then be subdivided, according to the Paquet classification; group 2: 100 HCV cirrhotic patients without esophageal varices; group 3: 50 normal age and sex-matched healthy subjects as the control group. Patients with other causes of abnormal calprotectin results were excluded.

RESULTS

The comparison of FC in the three study groups revealed a statistically significant difference, with FC levels higher in groups 1 and 2 (mean 66.4±10.41 and 48.4±10.92, respectively). There was a significant difference in FC levels between the subgroups, subdivided according to the Paquet classification (P=.001). FC levels were higher in the grade III and IV subgroups. FC in the diagnosis of HCV cirrhotic patients with esophageal varices showed the best performance when the cut-off value was >55; AUC was 0.918, with 92% sensitivity, 95% specificity, and 93% accuracy.

CONCLUSION

FC levels serve as a screening tool for esophageal varices. FC was higher in cirrhotic patients with esophageal varices, especially in the grade III and IV subgroups, according to the Paquet classification.

Calprotectin, Biomarker of Depression in Patients with Inflammatory Bowel Disease?

Background and Objectives: Calprotectin is a marker for intestinal inflammation. Recent research suggests a link between inflammation and depression. This study assessed the association between the levels of calprotectin in patients from South-Eastern Europe and the severity of depression, anxiety, and quality of life. Materials and Methods: This cross-sectional study included 30 confirmed patients with Crohn's disease (CD) and ulcerative colitis (UC) who were assessed using clinical interviews for determining the severities of mental disorders (i.e., depression severity-PHQ-9, anxiety-GAD-7) and the quality of life (EQ-5D). Stool samples were collected from all participants for measuring their levels of calprotectin. Results: The level of calprotectin is correlated with PHQ-9 (ρ = 0.416, p = 0.022) and EQ-5D (ρ = -0.304, p = 0.033) but not with GAD 7 (ρ = 0.059, p = 0.379). Calprotectin levels in patients with mild, moderate, and moderately severe depression were significantly higher than in patients with minimal depression (198 µg/g vs. 66,9 µg/g, p = 0.04). Calprotectin level was corelated with the following depressive symptoms: autolytic ideation (ρ = 0.557, p = 0.001), fatigue (ρ = 0.514, p = 0.002), slow movement (ρ = 0.490, p = 0.003), and sleep disorders (ρ = 0.403, p = 0.014). Calprotectin was an independent predictor of depression with an odds ratio of 1.01 (95%: 1.002-1.03, p < 0.01). An ROC analysis showed that a level of calprotectin of 131 µg/g or higher has a sensitivity of 82%, a specificity of 61%, and an accuracy of 70% for predicting depression. In this study, no significant correlations were found between calprotectin level and anxiety. Conclusions: Calprotectin levels are associated with the severity of depression, and checking for a calprotectin level of 131 µg/g or higher may be a potential accessible screening test for depression in patients with inflammatory bowel disease.

Why is manganese so valuable to bacterial pathogens?

Apart from oxygenic photosynthesis, the extent of manganese utilization in bacteria varies from species to species and also appears to depend on external conditions. This observation is in striking contrast to iron, which is similar to manganese but essential for the vast majority of bacteria. To adequately explain the role of manganese in pathogens, we first present in this review that the accumulation of molecular oxygen in the Earth's atmosphere was a key event that linked manganese utilization to iron utilization and put pressure on the use of manganese in general. We devote a large part of our contribution to explanation of how molecular oxygen interferes with iron so that it enhances oxidative stress in cells, and how bacteria have learned to control the concentration of free iron in the cytosol. The functioning of iron in the presence of molecular oxygen serves as a springboard for a fundamental understanding of why manganese is so valued by bacterial pathogens. The bulk of this review addresses how manganese can replace iron in enzymes. Redox-active enzymes must cope with the higher redox potential of manganese compared to iron. Therefore, specific manganese-dependent isoenzymes have evolved that either lower the redox potential of the bound metal or use a stronger oxidant. In contrast, redox-inactive enzymes can exchange the metal directly within the individual active site, so no isoenzymes are required. It appears that in the physiological context, only redox-inactive mononuclear or dinuclear enzymes are capable of replacing iron with manganese within the same active site. In both cases, cytosolic conditions play an important role in the selection of the metal used. In conclusion, we summarize both well-characterized and less-studied mechanisms of the tug-of-war for manganese between host and pathogen.

Decreased fecal calprotectin levels in Spondyloarthritis patients colonized by Blastocystis spp

Spondyloarthritis (SpA) is a group of chronic inflammatory systemic diseases mainly characterized by inflammation in the spine and/or peripheral joints. Although a link between SpA-pathogenesis, intestinal inflammation and gut dysbiosis has been proposed, studies have been focused on bacteria-host interactions and very little has been reported regarding intestinal parasites. Here, intestinal parasitic infection of 51 SpA-patients were evaluated and compared to healthy control individuals. No significant differences in the frequency of any parasite between SpA-patients and control individuals were found. Significantly higher levels of fecal calprotectin (FCP) were found in the SpA-patients compared to the control individuals. However, FCP levels were the same when comparing SpA-patients and control individuals, both colonized by Blastocystis spp. On the other hand, when comparing Blastocystis spp. colonized and Blastocystis spp. free SpA-patients, FCP levels were significantly higher in those Blastocystis spp. free. Without ignoring the small sample size as a study limitation, the results showed that in the SpA-patients colonized by Blastocystis spp., the FCP levels were significantly lower than those in the Blastocystis spp. free group and comparable to those in the control group. These findings seem to suggest a relationship between Blastocystis spp. and intestinal inflammation in SpA-patients, but studies intended to explore that interaction specifically should be designed.

Relationship between the Levels of Calprotectin and Soluble Receptor for Advanced Glycation End Products with Abdominal Aortic Aneurysm Diameter: A Preliminary Clinical Trial

An abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta greater than 50% of the diameter of a healthy aorta. Previous experimental studies confirm the effect of calprotectin (CAL) on the onset of arterial pathology. It has been suggested that low levels of soluble receptors for advanced glycation end products (RAGEs) increase levels of cytokines that lead to the inhibition of matrix metalloproteinases (MMPs), affecting AAA formation. This study aimed to analyze the correlation of levels of RAGE and CAL with AAA diameter. A group of 32 patients aged 50−75 with diagnosed AAA was enrolled in the study. This group of patients was further divided into three subgroups based on AAA diameter: (1) <4.5 cm, (2) 4.5−5.5 cm, (3) >5.5 cm. Peripheral blood was drawn from all participants on admission to measure the serum CAL and RAGE levels. An enumeration survey was performed three months after AAA surgical treatment. CAL and RAGE plasma levels were measured with the enzyme-linked immunosorbent assay (ELISA). The median CAL levels were 2273.0 ng/mL before and 1217.0 ng/mL after treatment. There was a statistically significant decrease in CAL levels following the surgical treatment (p = 0.003). The correlation analysis between CAL levels and RAGE levels before and after surgical treatment showed no statistically significant correlations. In addition, there were no statistically significant correlations between CAL and RAGE levels with AAA size. In conclusion, CAL levels appear to be a significant marker in patients with AAA. There is an almost twofold decrease in CAL levels after AAA excision.

Advancements in Gastrointestinal System Biomarkers

The requirement for diagnostic surgical operations of gastrointestinal system diseases significantly decreases with the help of proper diagnostic tools. These modalities are also beneficial for identifying postoperative complications, allowing us to diagnose them in earlier stages, and increasing the postoperative survival rates. Biomarkers are considered an integral part of diagnostic examinations. Developments of biomarkers used for diagnosing and treating abdominal diseases are essential for improving our capabilities in non-invasive monitoring. In this chapter, we review both the novel and the routine biomarkers in the diagnosis and follow-up of gastrointestinal system diseases.

Plasma calprotectin - preanalytical stability and interference from hemolysis

As an activation product of neutrophil granulocytes, calprotectin has been widely used in fecal samples for diagnosis and monitoring of patients with inflammatory bowel disease. However, fecal sample collection is cumbersome, and pre-analytical sources of error are plentiful. Therefore, plasma calprotectin is being investigated as a promising new biomarker. To utilize any biomarker, pre-analytical factors such as stability and susceptibility to interference from hemolysis must be established. We present precision estimates, stability results as well as interference study on plasma calprotectin in EDTA-plasma using the Thermo Fischer Phadia 250 EliA^TM Calprotectin immunoassay. Precision was estimated by the use of patient pools as well as internal quality controls provided by the manufacturer. Coefficients of variance were below 6.9% for patient samples. Calprotectin was stable in EDTA plasma after storage at 5-8 °C for up to 4 days, as well as after long-term storage at -20 °C. Susceptibility to interference from hemolysis was high, especially for low concentrations of calprotectin (<50 ng/mL) where hemoglobin levels above 0.02 mmol/L lead to false increase in calprotectin concentrations of up to 100%.

Manganese Utilization in Salmonella Pathogenesis: Beyond the Canonical Antioxidant Response

The metal ion manganese (Mn²⁺) is equally coveted by hosts and bacterial pathogens. The host restricts Mn²⁺ in the gastrointestinal tract and Salmonella-containing vacuoles, as part of a process generally known as nutritional immunity. Salmonella enterica serovar Typhimurium counteract Mn²⁺ limitation using a plethora of metal importers, whose expression is under elaborate transcriptional and posttranscriptional control. Mn²⁺ serves as cofactor for a variety of enzymes involved in antioxidant defense or central metabolism. Because of its thermodynamic stability and low reactivity, bacterial pathogens may favor Mn²⁺-cofactored metalloenzymes during periods of oxidative stress. This divalent metal catalyzes metabolic flow through lower glycolysis, reductive tricarboxylic acid and the pentose phosphate pathway, thereby providing energetic, redox and biosynthetic outputs associated with the resistance of Salmonella to reactive oxygen species generated in the respiratory burst of professional phagocytic cells. Combined, the oxyradical-detoxifying properties of Mn²⁺ together with the ability of this divalent metal cation to support central metabolism help Salmonella colonize the mammalian gut and establish systemic infections.

Serum Calprotectin Level Is Independently Associated With Carotid Plaque Presence in Patients With Psoriatic Arthritis

Background

Whether calprotectin could play a role in augmenting cardiovascular (CV) risk in patients with psoriatic arthritis (PsA) remains uncertain. The aim of this study is to elucidate the association between serum calprotectin level and subclinical atherosclerosis in patient with PsA.

Method

Seventy-eight PsA patients (age: 52 ± 10 years, 41 [52.6%] male) without CV disease were recruited into this cross-sectional study. Carotid intima-media thickness (cIMT) and the presence of plaque were determined by high-resolution ultrasound. Calprotectin levels in serum were quantified by enzyme-linked immunosorbent assay. The variables associated with the presence of carotid plaque (CP) were selected from the least absolute shrinkage and selection operator (LASSO) regression analysis.

Results

29/78 (37.2%) of patient had carotid plaque (CP+ group). Serum calprotectin level was significantly higher in the CP+ group (CP− group: 564.6 [329.3–910.5] ng/ml; CP+ group: 721.3 [329.3–910.5] ng/ml, P = 0.005). Serum calprotectin level correlated with PsA disease duration (rho = 0.280, P = 0.013) and mean cIMT (rho = 0.249, P = 0.038). Using LASSO regression analysis, the levels of Ln-calprotectin (OR: 3.38, 95% CI [1.37, 9.47]; P = 0.026) and PsA disease duration (OR: 1.09, 95% CI [1.01, 1.18]; P = 0.013) were screened out from a total of 19 variables. The model in predicting the presence of CP was constructed by Ln-calprotectin and PsA disease duration with an area under the receiver-operating characteristic (ROC) curve of 0.744, (95 CI% [0.59, 0.80], P = 0.037).

Conclusion

Serum calprotectin level is associated with the presence of CP in PsA. Further studies are required to confirm whether this pathway is associated with CV events in PsA.

The Current Status of Molecular Biomarkers for Inflammatory Bowel Disease

Diagnosis and prognosis of inflammatory bowel disease (IBD)-a chronic inflammation that affects the gastrointestinal tract of patients-are challenging, as most clinical symptoms are not specific to IBD, and are often seen in other inflammatory diseases, such as intestinal infections, drug-induced colitis, and monogenic diseases. To date, there is no gold-standard test for monitoring IBD. Endoscopy and imaging are essential diagnostic tools that provide information about the disease's state, location, and severity. However, the invasive nature and high cost of endoscopy make it unsuitable for frequent monitoring of disease activity in IBD patients, and even when it is possible to replace endoscopy with imaging, high cost remains a concern. Laboratory testing of blood or feces has the advantage of being non-invasive, rapid, cost-effective, and standardizable. Although the specificity and accuracy of laboratory testing alone need to be improved, it is increasingly used to monitor disease activity or to diagnose suspected IBD cases in combination with endoscopy and/or imaging. The literature survey indicates a dearth of summarization of biomarkers for IBD testing. This review introduces currently available non-invasive biomarkers of clinical importance in laboratory testing for IBD, and discusses the trends and challenges in the IBD biomarker studies.

Antimicrobial peptides and proteins in human biological fluids

Antimicrobial peptides and proteins (AMPs) are endogenous compounds that have a direct antimicrobial effect on bacteria (e. g., by disrupting bacterial membranes), as well as on fungi and viruses. AMPs are the main component of the innate immunity of living organisms and are produced by both epithelial cells (skin cells, cells of respiratory tract, intestine, urinary and genital tracts) and cells of the immune system and are secreted into secretory fluids. AMPs can also act as chemoattractants for immunocompetent cells (neutrophils, monocytes, T lymphocytes, dendritic cells) in the inflammation site and affect the antigen presenting cells by modulating adaptive T cell immune responses. The representatives of the main 15 AMP classes, that we describe in this review, are the most studied group of the large pool of these compounds. We discuss their localization, expression, and concentration in various biofluids of humans under normal and pathological conditions.

Regulation of zinc-dependent enzymes by metal carrier proteins

Zn²⁺ ions are essential in many physiological processes, including enzyme catalysis, protein structural stabilization, and the regulation of many proteins. The affinities of proteins for Zn²⁺ ions span several orders of magnitude, with catalytic Zn²⁺ ions generally held more tightly than structural or regulatory ones. Metal carrier proteins, most of which are not specific for Zn²⁺, bind these ions with a broad range of affinities that overlap those of catalytic, structural, and regulatory Zn²⁺ ions and are thought to be responsible for distributing the metal through most cells, tissues, and fluid compartments. While little is known about how many proteins obtain or release these ions, there is now considerable experimental evidence suggesting that metal carrier proteins may be responsible for transferring metals to and from some Zn²⁺-dependent proteins, thus serving as a major regulatory factor for them. In this review, the biological roles of Zn²⁺ and structures of Zn²⁺ binding sites are examined, and experimental evidence demonstrating the direct participation of metal carrier proteins in enzyme regulation is discussed. Mechanisms of metal ion transfer are also offered, and the potential physiological significance of this phenomenon is explored.

Analytical and clinical evaluation of DiaSorin Liaison® Calprotectin fecal assay adapted for serum samples

Background

Calprotectin is a calcium‐binding protein that can be measured in serum, plasma, and feces. Increased serum and plasma calprotectin concentrations have been found in chronic inflammatory rheumatic disorders. An analytical and clinical evaluation of the DiaSorin Liaison® fecal Calprotectin assay using LIAISON® XL was performed.

Methods

The protocol included an analytical and clinical evaluation in which imprecision, the linearity of dilution, differences between serum and plasma samples and method comparison with CalproLab™ ELISA kit were assessed. Serum calprotectin concentrations in active (n = 26) and remission (n = 23) rheumatoid arthritis (RA) patients were compared.

Results

The intra‐day and inter‐day analytical imprecision CVs ranged from 2.9% to 4.0% and 2.7% to 10.4%, respectively. Correlation between measured and expected values was high (R > 0.99), indicating good linearity. The Wilcoxon signed‐rank test showed that serum and plasma matched samples presented statistically significant differences (p < 0.001) being the highest concentrations of calprotectin observed in serum samples. Deming regression equation was as follows: Diasorin calprotectin (μg/ml) = −0.32 (95% CI: −0.65 ‐ −0.05) +1.58 (95% CI: 1.42–1.79).* Calprolab calprotectin (μg/ml). Significantly higher serum calprotectin levels were found in RA patients with active disease when compared to patients with low disease activity or in clinical remission (mean ± SD) [(3.35 μg/ml ± 1.55) vs. (1.63 μg/ml ± 0.52), p < 0.001] and these levels correlated well with all disease activity indices.

Conclusions

The DiaSorin Liaison® fecal Calprotectin assay adapted for serum samples showed adequate technical performances and the clinical performances were similar to other assays.

Zinc sequestration by human calprotectin facilitates manganese binding to the bacterial solute-binding proteins PsaA and MntC

Zinc is an essential transition metal nutrient for bacterial survival and growth but may become toxic when present at elevated levels. The Gram-positive bacterial pathogen Streptococcus pneumoniae is sensitive to zinc poisoning, which results in growth inhibition and lower resistance to oxidative stress. Streptococcus pneumoniae has a relatively high manganese requirement, and zinc toxicity in this pathogen has been attributed to the coordination of Zn(II) at the Mn(II) site of the solute-binding protein (SBP) PsaA, which prevents Mn(II) uptake by the PsaABC transport system. In this work, we investigate the Zn(II)-binding properties of pneumococcal PsaA and staphylococcal MntC, a related SBP expressed by another Gram-positive bacterial pathogen, Staphylococcus aureus, which contributes to Mn(II) uptake. X-ray absorption spectroscopic studies demonstrate that both SBPs harbor Zn(II) sites best described as five-coordinate, and metal-binding studies in solution show that both SBPs bind Zn(II) reversibly with sub-nanomolar affinities. Moreover, both SBPs exhibit a strong thermodynamic preference for Zn(II) ions, which readily displace bound Mn(II) ions from these proteins. We also evaluate the Zn(II) competition between these SBPs and the human S100 protein calprotectin (CP, S100A8/S100A9 oligomer), an abundant host-defense protein that is involved in the metal-withholding innate immune response. CP can sequester Zn(II) from PsaA and MntC, which facilitates Mn(II) binding to the SBPs. These results demonstrate that CP can inhibit Zn(II) poisoning of the SBPs and provide molecular insight into how S100 proteins may inadvertently benefit bacterial pathogens rather than the host.

Serum Calprotectin Level as an Inflammatory Marker in Newly Diagnosed Hypertensive Patients

Background

Hypertension is one of the leading causes of cardiovascular mortality. Although the pathogenetic process involved is not yet fully understood, the disease involves endothelial damage and inflammation. Calprotectin is an inflammatory marker that rises in parallel with disease activity in conditions such as systemic inflammatory diseases, infection, and atherosclerosis. The purpose of this study was to evaluate inflammation through serum calprotectin levels in newly diagnosed primary hypertension patients.

Methods

Forty-nine newly diagnosed hypertensive patients and 38 healthy adults were included in the study. Patients' office blood pressure values, biochemical findings, and demographic characteristics were recorded. Serum calprotectin levels were measured using ELISA. Parameters affecting serum calprotectin levels and determinants of hypertension were evaluated.

Results

Serum calprotectin levels were 242.8 (72.4–524) ng/mL in the control group and 112.6 (67.4–389.8) ng/mL in the hypertensive patient group, the difference being statistically significant (p=0.001). There was no correlation between serum calprotectin levels and other parameters (blood pressure values, age, gender, serum creatinine, uric acid, and calcium levels) in the hypertensive group. A lower serum calprotectin level was found to be independently related to hypertension (β = −0.009, p=0.005). Serum calprotectin at a cutoff level of 128.6 ng/mL differentiated hypertensives from healthy controls with a sensitivity of 69.4% and specificity of 68.4% (AUC = 0.767).

Conclusions

The results of this study were the opposite of our hypothesis that a higher calprotectin level may reflect subclinical endothelial damage in newly diagnosed hypertensive patients. Further comparative studies involving patients at different stages of hypertension may contribute to clarifying the relationship between calprotectin and hypertension. We conclude that molecular studies seem essential for understanding the place of calprotectin in hypertension-associated inflammation, a complex process.

Heterogeneity of Fecal Calprotectin Reflecting Generation of Neutrophil Extracellular Traps (NETs) in the Gut: New Immunoassays Are Available

Background: We aimed at obtaining more information on the structure of fecal calprotectin (CP) as a basis for establishing improved quantitative assays and detection of Neutrophil Extracellular Traps (NETs) in stools. Commercial fecal CP assays produce different results, probably due to differences in antibodies, extraction procedures, and standards used. In addition, the structure of fecal CP may be different from that in the standard so that rules for immunoassays are violated. We aimed at solving these problems by studying the structure of fecal CP and developing new antibodies and assay procedures including some for NETs in stools. Methods and Findings: Stool samples from children with abdominal symptoms were extracted by a conventional and a new procedure. Some extracts were run on anion exchange and size exclusion chromatography, and fractions were tested on ELISAs by use of ten new mouse monoclonal antibodies against the CP subunit S100A9. Hybrid ELISAs (named HELISA) were established using anti-DNA or anti-histones for coating of microwells, and enzyme labelled anti-CP was used for development. By ion exchange chromatography, five to ten fecal CP subfraction peaks differing in net electric charge were found, all of which contained the major chromatin components. The presence of DNA and histones followed calprotectin in the chromatographic fractions suggesting that NETs are generated in the gut lumen. The new CP monoclonals reacted very differently against the subfractions so that a mixture of them (called MiMo) must be used to obtain reliable assay values for fecal CP. A new method called FELISA was developed where standards and samples are applied directly in Nunc (Denmark) MaxiSorp plates, without any catching antibody. It takes advantage of the property of CP to bind strongly to the plastic in wells. This method has a higher sensitivity because it will detect CP molecules with only one antigenic epitope available. It will give more reliable estimates and more efficient selection of patients for complex diagnostic procedures. We also developed an alternative to the FELISA: a competitive ELISA where S100A9 coated in microwells will compete with CP in standards and samples for binding to a properly diluted HRP-anti-CP solution. In this method, the presence of other proteins in extraction or dilution buffers will not interfere. Using the HELISA, about 65% of the patients had detectable fecal NETs in concentrations between 150 and 1500 ng/mL; however, the values correlated poorly with CP values. Extraction of fecal samples with a simple buffer of TBS, and pH 5 with 5 mM EDTA, gave a yield of about 90%, while the yields of commercial kits are not specified or lie around 50%. A fecal CP standard will bring methods in accordance with the requirements for immunoassays that the structure of CP in the standard and sample must be the same. A mixture of fecal anion exchange fractions as a standard may be a solution to this problem. The principle worked in the first trial by giving the same values after storage of such a standard at 5C for four months. Conclusions: Fecal CP consists of at least five subfractions containing NETs or degradation products thereof. Commercial kits should not be accepted for clinical use unless it has been shown that they can detect all subfractions which may require the use of a mixture of monoclonals. The methods presented here can be used for such a quality control. The HELISA methods can be used for assays on NETs in stools and to study their possible pathogenic effects in the gut. Use of the FELISA and the S100A9 competitive method may give increased sensitivity, higher precision, and better selection of patients for more complex procedures.

Juvenile Polyps in Bangladeshi Children and Their Association with Fecal Calprotectin as a Biomarker

PURPOSE

Colonoscopy is considered the most reliable method for the diagnosis of juvenile polyps. However, colonoscopic screening is an invasive and expensive procedure. Fecal calprotectin (FCP), a marker of intestinal inflammation, has been shown to be elevated in patients with polyps. Therefore, this study aimed to evaluate FCP as a screening biomarker for the diagnosis of juvenile polyps.

METHODS

This cross-sectional, observational study was conducted at the Pediatric Gastroenterology and Nutrition Department, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. For children with polyps, colonoscopic polypectomy and histopathology were performed. FCP levels were analyzed before and 4 weeks after polypectomy in all patients. Information was recorded in a datasheet and analyzed using the computer-based program SPSS.

RESULTS

The age of the children was between 2.5 and 12 years. Approximately 93% of the polyps were found in the rectosigmoid region. Children with juvenile polyps had elevated levels of FCP before polypectomy that subsequently normalized after polypectomy. The mean FCP levels before and after polypectomy were 277±247 µg/g (range, 80-1,000 µg/g) and 48.57±38.23 µg/g (range, 29-140 µg/g) (p<0.001), respectively. The FCP levels were significantly higher in patients with multiple polyps than in those with single polyps. Moreover, mean FCP levels in patients with single and multiple polyps were 207.6±172.4 µg/ g and 515.4±320.5 µg/g (p<0.001), respectively.

CONCLUSION

Colonic juvenile polyps were found to be associated with elevated levels of FCP that normalized after polypectomy. Therefore, FCP may be recommended as a noninvasive screening biomarker for diagnosis of colonic juvenile polyps.

Evaluation of Serum Calprotectin Levels in Patients with Inflammatory Bowel Disease

BACKGROUND

Fecal calprotectin has been proposed as a useful biomarker of disease activity in inflammatory bowel disease (IBD). However, the role of calprotectin in systemic circulation is not well established. Thus, this study aimed to quantify serum calprotectin levels to identify a potential inflammatory marker for IBD.

METHODS

Ninety-eight patients with ulcerative colitis (UC) and 105 patients with Crohn's disease (CD) were prospectively enrolled and clinically scored. Ninety-two healthy, age-matched subjects served as controls. Blood samples from UC and CD patients and controls were analyzed for serum calprotectin levels and routine laboratory parameters. Disease activity was assessed by partial Mayo score and Harvey-Bradshaw index for UC and CD, respectively.

RESULTS

Serum calprotectin levels were higher in CD and UC patients than in controls and were higher during active disease than during inactive disease in CD but not in UC. In UC, serum calprotectin levels were correlated with C-reactive protein (CRP) but not with other laboratory parameters or disease activity. In CD, serum calprotectin levels were positively correlated with disease activity, serum CRP, and platelet count. In UC and CD, serum calprotectin and CRP levels increased during the acute phase and decreased towards remission.

CONCLUSIONS

Serum calprotectin is an inflammatory marker in IBD but might be more effective in evaluating patients with CD than those with UC. Further studies are needed to confirm these findings and to better determine the specific uses of serum calprotectin in routine practice.

Combined Use of Fecal Biomarkers in Inflammatory Bowel Diseases: Oncostatin M and Calprotectin

Background

Fecal biomarkers have emerged as one of the most useful tools for clinical management of inflammatory bowel disease (IBD). Oncostatin M (OSM), like fecal calprotectin (FC), is highly expressed in the inflamed intestinal mucosa which may have potential usefulness. We aimed to evaluate the additional utility of these two fecal biomarkers for IBD diagnosis, activity, and prediction of infliximab response over FC alone.

Methods

In group 1, 236 IBD patients (145 Crohn’s disease, 91 ulcerative colitis), 50 disease controls, and 32 healthy controls were recruited for IBD diagnosis and activity. In group 2, baseline stool samples were collected from 62 patients to predict infliximab response at week 28 and 52. The performance of fecal biomarkers for IBD management was assessed by the area under the receiver operating characteristic curve (AUC).

Results

Fecal OSM and FC levels were increased in IBD patients and were positively correlated with clinical and endoscopic activity. Their combination showed a better ability for disease diagnosis (AUC = 0.93) and slightly improved the capability to identify mucosal healing (AUC = 0.923). Baseline OSM and FC levels were elevated in non-responders at week 28 and 52. The AUCs of OSM, FC, and their combination to predict therapeutic response were 0.763, 0.834, and 0.859 at week 28, 0.638, 0.661, and 0.704 at week 52, respectively. Combined use of fecal and blood biomarkers improved predictive accuracy with an AUC of 0.919 at week 28 and 0.887 at week 52.

Conclusion

In addition to FC, OSM is a novel fecal biomarker, and their combination is more beneficial for disease diagnosis and prediction of infliximab response but not for disease activity in IBD patients. Further larger-scale studies are required to confirm our findings.

Molecular Basis of Ca(II)-Induced Tetramerization and Transition-Metal Sequestration in Human Calprotectin

Human calprotectin (CP, S100A8/S100A9 oligomer, MRP8/MRP14 oligomer) is an abundant innate immune protein that contributes to the host metal-withholding response. Its ability to sequester transition metal nutrients from microbial pathogens depends on a complex interplay of Ca(II) binding and self-association, which converts the αβ heterodimeric apo protein into a Ca(II)-bound (αβ)2 heterotetramer that displays enhanced transition metal affinities, antimicrobial activity, and protease stability. A paucity of structural data on the αβ heterodimer has hampered molecular understanding of how Ca(II) binding enables CP to exert its metal-sequestering innate immune function. We report solution NMR data that reveal how Ca(II) binding affects the structure and dynamics of the CP αβ heterodimer. These studies provide a structural model in which the apo αβ heterodimer undergoes conformational exchange and switches between two states, a tetramerization-incompetent or "inactive" state and a tetramerization-competent or "active" state. Ca(II) binding to the EF-hands of the αβ heterodimer causes the active state to predominate, resulting in self-association and formation of the (αβ)2 heterotetramer. Moreover, Ca(II) binding causes local and allosteric ordering of the His3Asp and His6 metal-binding sites. Ca(II) binding to the noncanonical EF-hand of S100A9 positions (A9)D30 and organizes the His3Asp site. Remarkably, Ca(II) binding causes allosteric effects in the C-terminal region of helix αIV of S100A9, which stabilize the α-helicity at positions H91 and H95 and thereby organize the functionally versatile His6 site. Collectively, this study illuminates the molecular basis for how CP responds to high extracellular Ca(II) concentrations, which enables its metal-sequestering host-defense function.

Term infant formula supplemented with milk-derived oligosaccharides shifts the gut microbiota closer to that of human milk-fed infants and improves intestinal immune defense: a randomized controlled trial

BACKGROUND

Bovine milk-derived oligosaccharides (MOS) containing primarily galacto-oligosaccharides with inherent concentrations of sialylated oligosaccharides can be added to infant formula to enhance the oligosaccharide profile.

OBJECTIVE

To investigate the effects of an MOS-supplemented infant formula on gut microbiota and intestinal immunity.

METHODS

In a double-blind, randomized, controlled trial, healthy term formula-fed infants aged 21-26 d either received an intact protein cow milk-based formula (control group, CG, n = 112) or the same formula containing 7.2 g MOS/L (experimental group, EG, n = 114) until the age of 6 mo. Exclusively human milk-fed infants (HFI, n = 70) from an observational study served as the reference. Fecal samples collected at baseline, and the ages of 2.5 and 4 mo were assessed for microbiota (16S ribosomal RNA-based approaches), metabolites, and biomarkers of gut health and immune response.

RESULTS

Aged 2.5 and 4 mo, redundancy analysis (P = 0.002) and average phylogenetic distance (P < 0.05) showed that the overall microbiota composition in EG was different from CG and closer to that of HFI. Similarly, EG caesarean-born infants were different from CG caesarean- or vaginally born infants and approaching HFI vaginally born infants. Relative bifidobacteria abundance was higher in EG compared with CG (P < 0.05) approaching HFI. At the age of 4 mo, counts of Clostridioides difficile and Clostridium perfringens were ∼90% (P < 0.001) and ∼65% (P < 0.01) lower in EG compared with CG, respectively. Geometric LS mean (95% CI) fecal secretory IgA in EG was twice that of CG [70 (57, 85) compared with 34 (28, 42) mg/g, P < 0.001] and closer to HFI. Fecal oral polio vaccine-specific IgA was ∼50% higher in EG compared with CG (P = 0.065). Compared with CG, EG and HFI had lower fecal calcium excretion (by ∼30%, P < 0.005) and fecal pH (P < 0.001), and higher lactate concentration (P < 0.001).

CONCLUSIONS

Infant formula with MOS shifts the gut microbiota and metabolic signature closer to that of HFI, has a strong bifidogenic effect, reduces fecal pathogens, and improves the intestinal immune response.

Angiopoietin 1 release from human neutrophils is independent from neutrophil extracellular traps (NETs)

Background

Neutrophils induce the synthesis and release of angiopoietin 1 (Ang1), a cytosolic growth factor involved in angiogenesis and capable of inducing several pro-inflammatory activities in neutrophils. Neutrophils also synthesize and release neutrophil extracellular traps (NETs), comprised from decondensed nuclear DNA filaments carrying proteins such as neutrophil elastase (NE), myeloperoxidase (MPO), proteinase 3 (PR3) and calprotectin (S100A8/S100A9), which together, contribute to the innate immune response against pathogens (e.g., bacteria). NETs are involved in various pathological conditions through pro-inflammatory, pro-thrombotic and endothelial dysfunction effects and have recently been found in heart failure (HF) and type 2 diabetes (T2DM) patients. The aim of the present study was to investigate the role of NETs on the synthesis and release of Ang1 by the neutrophils in patients with T2DM and HF with preserved ejection fraction (HFpEF) (stable or acute decompensated; ADHFpEF) with or without T2DM.

Results

Our data show that at basal level (PBS) and upon treatment with LPS, levels of NETs are slightly increased in patients suffering from T2DM, HFpEF ± T2DM and ADHF without (w/o) T2DM, whereas this increase was significant in ADHFpEF + T2DM patients compared to healthy control (HC) volunteers and ADHFpEF w/o T2DM. We also observed that treatments with PMA or A23187 increase the synthesis of Ang1 (from 150 to 250%) in HC and this effect is amplified in T2DM and in all cohorts of HF patients. Ang1 is completely released (100%) by neutrophils of all groups and does not bind to NETs as opposed to calprotectin.

Conclusions

Our study suggests that severely ill patients with HFpEF and diabetes synthesize and release a greater abundance of NETs while Ang1 exocytosis is independent of NETs synthesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-021-00442-8.

The Role of Serum Calprotectin as a New Marker in Abdominal Aortic Aneurysms - A Preliminary Report

BACKGROUND

Abdominal Aortic Aneurysm (AAA) remains a surgical challenge. There are many recognizable markers associated with the formation of AAA. Previous experiments carried out on animal models have shown a correlation between serum calprotectin and the occurrence of AAA.

OBJECTIVE

This study aimed to evaluate the level of calprotectin as a potential diagnostic biomarker in patients with diagnosed AAA.

METHODS

The study group consisted of 75 patients aged 35-75 years assigned to two groups: a control group (n=43) of healthy subjects without AAA and a study group (n=32) of patients with a diagnosed AAA. The first calprotectin test was performed upon patient admission to the hospital, and the second control test was performed after three months. The concentration of calprotectin in plasma was determined using the Immunoenzymatic Method (ELISA) with the commercially available Assaypro Kit (AssayMax™ Human Calprotectin ELISA Kit), as well as the sandwich method with polyclonal antibodies to human calprotectin and peroxidase enzyme.

RESULTS & DISCUSSION

Serum calprotectin levels in AAA patients were three times higher than in healthy subjects (p<0.05). A statistically significant twofold decrease in calprotectin concentration was observed after AAA surgery compared to the control group (p<0.05).

CONCLUSION

Calprotectin levels can be an important marker in the detection of AAA. In conclusion, AAA patients showed a threefold increase in serum calprotectin level and a twofold decrease in this marker after AAA surgery.

Chromogranin A regulates gut permeability via the antagonistic actions of its proteolytic peptides

AIM

A "leaky" gut barrier has been implicated in the initiation and progression of a multitude of diseases, for example, inflammatory bowel disease (IBD), irritable bowel syndrome and celiac disease. Here we show how pro-hormone Chromogranin A (CgA), produced by the enteroendocrine cells, and Catestatin (CST: hCgA_352-372 ), the most abundant CgA-derived proteolytic peptide, affect the gut barrier.

METHODS

Colon tissues from region-specific CST-knockout (CST-KO) mice, CgA-knockout (CgA-KO) and WT mice were analysed by immunohistochemistry, western blot, ultrastructural and flowcytometry studies. FITC-dextran assays were used to measure intestinal barrier function. Mice were supplemented with CST or CgA fragment pancreastatin (PST: CgA_250-301 ). The microbial composition of cecum was determined. CgA and CST levels were measured in blood of IBD patients.

RESULTS

Plasma levels of CST were elevated in IBD patients. CST-KO mice displayed (a) elongated tight, adherens junctions and desmosomes similar to IBD patients, (b) elevated expression of Claudin 2, and (c) gut inflammation. Plasma FITC-dextran measurements showed increased intestinal paracellular permeability in the CST-KO mice. This correlated with a higher ratio of Firmicutes to Bacteroidetes, a dysbiotic pattern commonly encountered in various diseases. Supplementation of CST-KO mice with recombinant CST restored paracellular permeability and reversed inflammation, whereas CgA-KO mice supplementation with CST and/or PST in CgA-KO mice showed that intestinal paracellular permeability is regulated by the antagonistic roles of these two peptides: CST reduces and PST increases permeability.

CONCLUSION

The pro-hormone CgA regulates the intestinal paracellular permeability. CST is both necessary and sufficient to reduce permeability and primarily acts by antagonizing PST.

The Use of Fecal Calprotectin Testing in Paediatric Disorders: A Position Paper of the European Society for Paediatric Gastroenterology and Nutrition Gastroenterology Committee

OBJECTIVES

The aim of the study was to review the evidence regarding the clinical use and value of fecal calprotectin (FC) measurements in different gastrointestinal disorders in children.

METHODS

A literature search was conducted in the PubMed, MEDLINE, EMBASE, and Cochrane databases until October 31, 2019. Subtopics were identified and each assigned to individual authors.

RESULTS

A total of 28 recommendations were voted on using the nominal voting technique. Recommendations are given related to sampling, measurement methods, and results interpretation. The 14 authors anonymously voted on each recommendation using a 9-point scale (1 strongly disagree to 9 fully agree). Consensus was considered achieved if at least 75% of the authors voted 6, 7, 8, or 9.

CONCLUSIONS

Consensus was reached for all recommendations. Limitations for the use of FC in clinical practice include variability in extraction methodology, performance of test kits as well as the need to establish local reference ranges because of the influence of individual factors, such as age, diet, microbiota, and drugs. The main utility of FC measurement at present is in the diagnosis and monitoring of inflammatory bowel disease (IBD) as well as to differentiate it from functional gastrointestinal disorders (FAPDs). FC, however, has neither utility in the diagnosis of infantile colic nor to differentiate between functional and organic constipation. A rise in FC concentration, may alert to the risk of developing necrotizing enterocolitis and help identifying gastrointestinal involvement in children with Henoch-Schönlein purpura. FC measurement is of little value in Cow's Milk Protein Allergy, coeliac disease (CD), and cystic fibrosis. FC does neither help to distinguish bacterial from viral acute gastroenteritis (AGE), nor to diagnose Helicobacter Pylori infection, small intestinal bacterial overgrowth (SIBO), acute appendicitis (AA), or intestinal polyps.

Serum Calprotectin is Indicating Clinical and Ultrasonographic Disease Activity in Rheumatoid Arthritis, even with Normal C-Reactive Protein Levels

Objective:

Calprotectin is an inflammatory biomarker which assesses disease activity in rheumatoid arthritis (RA). The objective of this study was to test whether serum calprotectin is associated with clinical and ultrasonographic disease activity in patients with RA, and to analyse its predicting value for disease activity evaluation despite normal C-Reactive protein (CRP) levels.

Methods:

We included 80 patients with RA and 30 healthy subjects. Patients were examined clinically and by ultrasound, (US7 score) along with laboratory parameters (calprotectin, CRP, erythrocyte sedimentation rate [ESR]). Disease activity scores (DAS28) were calculated to assess disease activity. Firstly, patients were divided into four subgroups according to the DAS28-ESR (high, moderate, low disease activity, and remission), then into two subgroups; group-1 (DAS-28≤3.2) and group-2 (DAS28>3.2). The predicting value of calprotectin for disease activity in patients with normal CRP was analysed with univariate and multivariate analysis and receiver operating characteristic curves.

Results:

Calprotectin levels were higher in RA patients than controls (96.3±45.9 ng/ml, 54.7±50.0 ng/ml, respectively; p<0.001). Calprotectin levels were 74.8±45.5 ng/ml in group-1 (n=37) and 114.7±37.9 ng/ml in group-2 (n=43) (p<0.001). In univariate analyses, calprotectin was significantly correlated with clinical, laboratory, and ultrasound parameters (p<0.05), and was a better predictor of power doppler synovitis than CRP in multivariate analysis (OR=1.014; 95%CI 1.002–1.027; p=0.024). The discriminatory capacity for calprotectin to distinguish ultrasonographically active disease in patients with normal CRP levels using AUC was 0.75 (95%CI 0.56–0.90, p=0.023).

Conclusions:

Calprotectin represents disease activity, even in patients who are clinical and ultrasonographical active but have normal CRP levels.

Elevated Intestinal Inflammation in Preterm Infants With Signs and Symptoms of Gastroesophageal Reflux Disease

OBJECTIVES

Reflux is common in infancy; however, persistent signs and symptoms of gastrointestinal distress are often attributed to gastroesophageal reflux disease (GERD). In this pilot study, we aimed to characterize associations between signs and symptoms of suspected GERD and noninvasive markers of intestinal inflammation in preterm infants.

METHODS

We reviewed Electronic Medical Record (EMR) data to identify clinical signs and symptoms among case patients (n = 16). Controls (n = 16) were matched on gestational age. Univariate and multivariate regression analyses were used to compare fecal calprotectin and urinary intestinal fatty acid binding protein (I-FABP) levels between cases and controls.

RESULTS

We found no differences in baseline characteristics between cases and controls. In the multivariate regression analysis controlling for the proportion of mother's milk, cases had higher fecal calprotectin levels than controls, with no differences in I-FABP levels between cases and controls.

CONCLUSION

Our findings suggest that preterm infants with signs and symptoms of GERD have higher levels of intestinal inflammation as indicated by fecal calprotectin compared to their controls. Further studies are needed to evaluate the role of intestinal inflammation in signs and symptoms of gastrointestinal distress and whether fecal calprotectin might have predictive value in diagnosing GERD.

Non-IgE- or Mixed IgE/Non-IgE-Mediated Gastrointestinal Food Allergies in the First Years of Life: Old and New Tools for Diagnosis

non-IgE and mixed gastrointestinal food allergies present various specific, well-characterized clinical pictures such as food protein-induced allergic proctocolitis, food protein-induced enterocolitis and food protein-induced enteropathy syndrome as well as eosinophilic gastrointestinal disorders such as eosinophilic esophagitis, allergic eosinophilic gastroenteritis and eosinophilic colitis. The aim of this article is to provide an updated review of their different clinical presentations, to suggest a correct approach to their diagnosis and to discuss the usefulness of both old and new diagnostic tools, including fecal biomarkers, atopy patch tests, endoscopy, specific IgG and IgG4 testing, allergen-specific lymphocyte stimulation test (ALST) and clinical score (CoMiss).

Heme protects Pseudomonas aeruginosa and Staphylococcus aureus from calprotectin-induced iron starvation

Pseudomonas aeruginosa and Staphylococcus aureus are opportunistic bacterial pathogens that cause severe infections in immunocompromised individuals and patients with cystic fibrosis. Both P. aeruginosa and S. aureus require iron to infect the mammalian host. To obtain iron, these pathogens may rely on siderophore-mediated ferric iron uptake, ferrous iron uptake, or heme uptake at different points during infection. The preferred iron source depends on environmental conditions, including the presence of iron-sequestering host-defense proteins. Here, we investigate how the presence of heme, a highly relevant iron source during infection, affects bacterial responses to iron withholding by the innate immune protein calprotectin (CP). Prior work has shown that P. aeruginosa is starved of iron in the presence of CP. We report that P. aeruginosa upregulates expression of heme uptake machinery in response to CP. Furthermore, we show that heme protects P. aeruginosa from CP-mediated inhibition of iron uptake and iron-starvation responses. We extend our study to a second bacterial pathogen, S. aureus, and demonstrate that CP also inhibits iron uptake and induces iron-starvation responses by this pathogen. Similarly to P. aeruginosa, we show that heme protects S. aureus from CP-mediated inhibition of iron uptake and iron-starvation responses. These findings expand our understanding of microbial responses to iron sequestration by CP and highlight the importance of heme utilization for bacterial adaptation to host iron-withholding strategies.

Faecal cytokine profiling as a marker of intestinal inflammation in acutely decompensated cirrhosis

BACKGROUND & AIMS

Gut dysbiosis and inflammation perpetuate loss of gut barrier integrity (GBI) and pathological bacterial translocation (BT) in cirrhosis, contributing to infection risk. Little is known about gut inflammation in cirrhosis and how this differs in acute decompensation (AD). We developed a novel approach to characterise intestinal immunopathology by quantifying faecal cytokines (FCs) and GBI markers.

METHODS

Faeces and plasma were obtained from patients with stable cirrhosis (SC; n = 16), AD (n = 47), and healthy controls (HCs; n = 31). A panel of 15 cytokines and GBI markers, including intestinal fatty-acid-binding protein-2 (FABP2), d-lactate, and faecal calprotectin (FCAL), were quantified by electrochemiluminescence/ELISA. Correlations between analytes and clinical metadata with univariate and multivariate analyses were performed.

RESULTS

Faecal (F) IL-1β, interferon gamma, tumour necrosis factor alpha, IL-21, IL-17A/F, and IL-22 were significantly elevated in AD vs. SC (q <0.01). F-IL-23 was significantly elevated in AD vs. HC (p = 0.0007). FABP2/d-lactate were significantly increased in faeces in AD vs. SC and AD vs. HC (p <0.0001) and in plasma (p = 0.0004; p = 0.011). F-FABP2 correlated most strongly with disease severity (Spearman's rho: Child-Pugh 0.466; p <0.0001; model for end-stage liver disease 0.488; p <0.0001). FCAL correlated with plasma IL-21, IL-1β, and IL-17F only and none of the faecal analytes. F-cytokines and F-GBI markers were more accurate than plasma in discriminating AD from SC.

CONCLUSIONS

FC profiling represents an innovative approach to investigating the localised intestinal cytokine micro-environment in cirrhosis. These data reveal that AD is associated with a highly inflamed and permeable gut barrier. FC profiles are very different from the classical innate-like features of systemic inflammation. There is non-specific upregulation of TH1/TH17 effector cytokines and those known to mediate intestinal barrier damage. This prevents mucosal healing in AD and further propagates BT and systemic inflammation.

LAY SUMMARY

The gut barrier is crucial in cirrhosis in preventing infection-causing bacteria that normally live in the gut from accessing the liver and other organs via the bloodstream. Herein, we characterised gut inflammation by measuring different markers in stool samples from patients at different stages of cirrhosis and comparing this to healthy people. These markers, when compared with equivalent markers usually measured in blood, were found to be very different in pattern and absolute levels, suggesting that there is significant gut inflammation in cirrhosis related to different immune system pathways to that seen outside of the gut. This provides new insights into gut-specific immune disturbances that predispose to complications of cirrhosis, and emphasises that a better understanding of the gut-liver axis is necessary to develop better targeted therapies.

Salivary Stress/Immunological Markers in Crohn's Disease and Ulcerative Colitis

There is continuous and growing interest in research into new alternatives to standard biomarkers to detect and follow-up disease, reducing physical and psychological stress in patients needing regular and invasive medical examinations for the evaluation of pathologies, including inflammatory bowel diseases (IBD). Saliva is one of the most promising body fluids in the research of new biomarkers, thanks to the large number of molecules it contains. Many molecules present in saliva are often directly correlated to their concentration in the blood but may be affected by the condition of the oral cavity. This means that a careful selection of a specific biomarker is required for each pathology, especially pathologies such as IBD, which may induce inflammation in the oral cavity. Here, we analyze the currently used and the proposed new salivary biomarkers (i.e., calprotectin, cytokines, IgA, cortisol, and oxidative stress markers) for the detection and follow-up of the main subtypes of IBD, known as ulcerative colitis and Crohn's disease.

Irritable bowel syndrome-like symptoms in treated microscopic colitis patients compared with controls: a cross-sectional study

Background

The prevalence of irritable bowel syndrome (IBS)-like symptoms is high in untreated patients with microscopic colitis (MC), but there is uncertainty of the prevalence of IBS-like symptoms in treated patients. We assessed the degree of IBS-like symptoms in patients with MC in comparison to control subjects, and investigated the association between IBS-like symptoms and faecal calprotectin (FC) in MC patients.

Methods

Patients with an established MC diagnosis (n = 57) were compared to sex- and age-matched controls (n = 138) for scores in the GSRS-IBS (Gastrointestinal Symptom Rating Scale for Irritable Bowel Syndrome) and HADS (Hospital Anxiety Depression Scale). In MC patients, an FC level was simultaneously analysed.

Results

The median interval from MC diagnoses to the time the subjects participated in the study was 5.5 years (25th–75th percentiles; 4.5–9.5 years). The total GSRS-IBS score, subscores for abdominal pain, bloating, and diarrhoea were significantly higher in MC patients compared to controls (all P < 0.001). There was a significant correlation between FC levels and reported bowel frequency (P = 0.023), but there was no correlation between FC levels and GSRS-IBS scores. Patients with MC had significantly higher scores on anxiety (HADS-A) (P < 0.001) and used more selective serotonin-reuptake-inhibitor drugs (P = 0.016) than the control subjects. However, only the control subjects (not the patients with MC) showed significant correlations between GSRS-IBS scores and HADS scores.

Conclusions

Patients with MC reported more IBS-like symptoms and anxiety than control subjects but neither FC levels nor symptoms of affectivity were significantly correlated with IBS-like symptoms.

A Pilot Study Evaluating Novel Urinary Biomarkers for Crohn's Disease

Introduction

Although collecting faeces and blood samples are considered non-invasive methods of monitoring Crohn's disease (CD), these methods are less preferred by some patients. This study utilized urine as an alternative to evaluate four disease biomarkers in young adults with active CD before and after exclusive enteral nutrition (EEN) therapy.

Methods

Urine samples collected at baseline (W0) and after 8 weeks (W8) of EEN therapy were assayed by ELISA for levels of intestinal fatty acid-binding protein (I-FABP), liver fatty acid-binding protein (L-FABP), claudin-3, and calprotectin. Levels of each biomarker were also compared with standard clinical parameters, including disease indexes, nutrient, and inflammatory markers.

Results

Of the paired urine samples from 14 patients, 10 were female and 12 were newly diagnosed with CD. Urinary I-FABP: Cr (standardized to urine Cr) levels were significantly reduced, while urinary L-FABP: Cr levels increased following EEN therapy. Urinary L-FABP: Cr correlated positively with serum insulin-like growth factor 1 (IGF-1) (r = 0.60, p = 0.02). Urinary CLND3: Cr and calprotectin: Cr levels were not significantly different after treatment.

Conclusion

I-FABP is a potential urinary biomarker of disease activity in adults with CD, while urinary L-FABP may be an indirect marker of nutritional status in adults with CD. CLND3 and calprotectin do not appear to have roles as urinary biomarkers in CD. These findings warrant further investigations using a larger sample size.

Faecal calprotectin in inflammatory bowel diseases: a review focused on meta-analyses and routine usage limitations

A growing body of evidence has been published about the usefulness of measuring calprotectin in faecal samples (FCAL) in inflammatory bowel disease (IBD) assessment, including diagnosis, monitoring of disease activity and relapse prediction. Several systematic reviews with meta-analyses compiling studies for each particular clinical setting have been carried out in recent years. Most of these were focused on the use of FCAL in IBD diagnosis and showed a relevant role for this marker in selecting patients with gastrointestinal symptoms who would not need a further examination by endoscopy. Although a lesser number of meta-analyses have been performed on the use of FCAL as a surrogate marker of disease activity, a close correlation between FCAL and endoscopic activity of IBD has been shown. With respect to the predictive capacity of FCAL for IBD relapse, a single meta-analysis published indicates that this role is more limited. Furthermore, FCAL thresholds vary considerably depending on the clinical setting and, what is more concerning, among different commercially available assays due to a lack of FCAL concentration interchangeability. Here, we summarise recent publications about the role and limitations of FCAL in IBD, with a special focus on meta-analyses, and give an overview of alternative faecal biomarkers.

Calcium Binding to the Innate Immune Protein Human Calprotectin Revealed by Integrated Mass Spectrometry

Although knowledge of the coordination chemistry and metal-withholding function of the innate immune protein human calprotectin (hCP) has broadened in recent years, understanding of its Ca²⁺-binding properties in solution remains incomplete. In particular, the molecular basis by which Ca²⁺ binding affects structure and enhances the functional properties of this remarkable transition-metal-sequestering protein has remained enigmatic. To achieve a molecular picture of how Ca²⁺ binding triggers hCP oligomerization, increases protease stability, and enhances antimicrobial activity, we implemented a new integrated mass spectrometry (MS)-based approach that can be readily generalized to study other protein-metal and protein-ligand interactions. Three MS-based methods (hydrogen/deuterium exchange MS kinetics; protein-ligand interactions in solution by MS, titration, and H/D exchange (PLIMSTEX); and native MS) provided a comprehensive analysis of Ca²⁺ binding and oligomerization to hCP without modifying the protein in any way. Integration of these methods allowed us to (i) observe the four regions of hCP that serve as Ca²⁺-binding sites, (ii) determine the binding stoichiometry to be four Ca²⁺ per CP heterodimer and eight Ca²⁺ per CP heterotetramer, (iii) establish the protein-to-Ca²⁺ molar ratio that causes the dimer-to-tetramer transition, and (iv) calculate the binding affinities associated with the four Ca²⁺-binding sites per heterodimer. These quantitative results support a model in which hCP exists in its heterodimeric form and is at most half-bound to Ca²⁺ in the cytoplasm of resting cells. With release into the extracellular space, hCP encounters elevated Ca²⁺ concentrations and binds more Ca²⁺ ions, forming a heterotetramer that is poised to compete with microbial pathogens for essential metal nutrients.

Metal Sequestration and Antimicrobial Activity of Human Calprotectin Are pH-Dependent

Human calprotectin (CP, S100A8/S100A9 oligomer) is an abundant innate immune protein that sequesters transition metal ions in the extracellular space to limit nutrient availability and the growth of invading microbial pathogens. Our current understanding of the metal-sequestering ability of CP is based on biochemical and functional studies performed at neutral or near-neutral pH. Nevertheless, CP can be present throughout the human body and is expressed at infection and inflammation sites that tend to be acidic. Here, we evaluate the metal binding and antimicrobial properties of CP in the pH range of 5.0-7.0. We show that Ca(II)-induced tetramerization, an important process for the extracellular functions of CP, is perturbed by acidic conditions. Moreover, a low pH impairs the antimicrobial activity of CP against some bacterial pathogens, including Staphylococcus aureus and Salmonella enterica serovar Typhimurium. At a mildly acidic pH, CP loses the ability to deplete Mn from microbial growth medium, indicating that Mn(II) sequestration is attenuated under acidic conditions. Evaluation of the Mn(II) binding properties of CP at pH 5.0-7.0 indicates that mildly acidic conditions decrease the Mn(II) binding affinity of the His₆ site. Lastly, CP is less effective at preventing capture of Mn(II) by the bacterial solute-binding proteins MntC and PsaA at low pH. These results indicate that acidic conditions compromise the ability of CP to sequester Mn(II) and starve microbial pathogens of this nutrient. This work highlights the importance of considering the local pH of biological sites when describing the interplay between CP and microbes in host-pathogen interactions.

Serum calprotectin: a promising biomarker in rheumatoid arthritis and axial spondyloarthritis

Background

Calprotectin (S100A8/S100A9 protein) is known as a damage-associated molecular pattern (DAMP) protein and reflects mainly neutrophil activation. Serum calprotectin levels might be a good alternative to acute-phase protein as a biomarker in inflammatory rheumatic diseases. The aim of this study is to investigate the association of serum calprotectin with disease activity and severity in rheumatoid arthritis (RA), axial spondyloarthritis (axSpA), and psoriatic arthritis (PsA).

Methods

Serum calprotectin was measured in patients with RA, axSpA, and PsA from the prospective Swiss Clinical Quality Management (SCQM) registry. Asymptomatic first-degree relatives of RA patients were used as healthy controls (HC). Outcomes included swollen joint count (SJC), Disease Activity Score (DAS), Health Assessment questionnaire (HAQ), joint radiographs, and ultrasound power Doppler (USPD) score for RA; Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS) and coxitis for axSpA; and SJC and Disease Activity Index for PSoriatic Arthritis (DAPSA) for PsA. Comparison of outcomes by calprotectin quartile levels was performed using Kruskal-Wallis tests for continuous outcomes or trend tests for categorical outcomes.

Results

A total of 1729 subjects [RA = 969, axSpA = 451, PsA = 237, and HC = 72] were included. Median levels of serum calprotectin were higher in each disease group compared to HC (p < 0.01). In RA patients, all clinical outcomes were statistically different between quartiles of serum calprotectin, indicating an association between calprotectin levels and higher disease activity (SJC, DAS, and USPD scores) and severity (joint radiographs and HAQ). In axSpA, an association between calprotectin levels and ASDAS score (p < 0.01) and prevalence of coxitis (p = 0.02) was observed. For PsA patients, SJC and DAPSA did not differ across calprotectin quartiles.

Conclusions

This large study supports the association of serum calprotectin levels with disease activity in both RA and axSpA, but not in PsA.

Extensive Changes in Transcriptomic "Fingerprints" and Immunological Cells in the Large Organs of Patients Dying of Acute Septic Shock and Multiple Organ Failure Caused by Neisseria meningitidis

Background: Patients developing meningococcal septic shock reveal levels of Neisseria meningitidis (10⁶-10⁸/mL) and endotoxin (10¹-10³ EU/mL) in the circulation and organs, leading to acute cardiovascular, pulmonary and renal failure, coagulopathy and a high case fatality rate within 24 h. Objective: To investigate transcriptional profiles in heart, lungs, kidneys, liver, and spleen and immunostain key inflammatory cells and proteins in post mortem formalin-fixed, paraffin-embedded (FFPE) tissue samples from meningococcal septic shock patients. Patients and Methods: Total RNA was isolated from FFPE and fresh frozen (FF) tissue samples from five patients and two controls (acute non-infectious death). Differential expression of genes was detected using Affymetrix microarray analysis. Lung and heart tissue samples were immunostained for T-and B cells, macrophages, neutrophils and the inflammatory markers PAI-1 and MCP-1. Inflammatory mediators were quantified in lysates from FF tissues. Results: The transcriptional profiles showed a complex pattern of protein-coding and non-coding RNAs with significant regulation of pathways associated with organismal death, cell death and survival, leukocyte migration, cellular movement, proliferation of cells, cell-to-cell signaling, immune cell trafficking, and inflammatory responses in an organ-specific clustering manner. The canonical pathways including acute phase response-, EIF2-, TREM1-, IL-6-, HMBG1-, PPAR signaling, and LXR/RXR activation were associated with acute heart, pulmonary, and renal failure. Fewer genes were regulated in the liver and particularly in the spleen. The main upstream regulators were TNF, IL-1β, IL-6, RICTOR, miR-6739-3p, and CD3. Increased numbers of inflammatory cells (CD68+, MPO+, CD3+, and CD20+) were found in lungs and heart. PAI-1 inhibiting fibrinolysis and MCP-1 attracting leukocyte were found significantly present in the septic tissue samples compared to the controls. Conclusions: FFPE tissue samples can be suitable for gene expression studies as well as immunostaining of specific cells or molecules. The most pronounced gene expression patterns were found in the organs with highest levels of Neisseria meningitidis DNA. Thousands of protein-coding and non-coding RNA transcripts were altered in lungs, heart and kidneys. We identified specific biomarker panels both protein-coding and non-coding RNA transcripts, which differed from organ to organ. Involvement of many genes and pathways add up and the combined effect induce organ failure.

Effect of Different Milk Diet on the Level of Fecal Calprotectin in Very Preterm Infants

Objective: To evaluate the course of fecal calprotectin (FC) in very preterm infants over the first 15 days of life in relation to the type of milk diet. Methods: This study was part of a randomized controlled trial comparing two different ways of integrating the own mother's milk (OMM) for the evaluation of feeding tolerance in very preterm infants. In infants with gestational age of ≤ 32 weeks randomized to receive preterm formula (PF group) or pasteurized donor human milk (PDHM group) as a supplement to the OMM insufficient or unavailable, FC level was planned to be measured at the first meconium passage and at days 8 and 15 of life (T0, T1, and T2, respectively). Results: FC data were available for all the 70 infants randomized, 35 in the PF group, and 35 in the PDHM group. The mean FC levels were similar in the two study groups at T0 and T1, whereas they were significantly higher in the PF group than the PDHM group at T2. FC values decreased over the first week of life in both groups and significantly increased over the second week of life only in the PF group. Conclusions: Our study demonstrates a significant increase in FC levels when PF is used as a supplement to the OMM compared to the use of PDHM. Further studies are needed to establish if the higher FC levels in infants receiving PF are the expression of a normal immunological maturation rather than an initial inflammatory process.

Fecal Calprotectin in Combination With Standard Blood Tests in the Diagnosis of Inflammatory Bowel Disease in Children

Introduction: Fecal calprotectin (FC) is a useful non-invasive screening test but elevated levels are not specific to inflammatory bowel disease (IBD). The study aimed to evaluate the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of FC alone or FC in combination with other standard blood tests in the diagnosis of IBD. Methods: Children aged <17 years who had FC (normal range <50 μg/g) measured and underwent endoscopy over 33 months in Christchurch, New Zealand were identified retrospectively (consecutive sampling). Medical records were reviewed for patient final diagnoses. Results: One hundred and two children were included; mean age was 12.3 years and 53 were male. Fifty-eight (57%) of the 102 children were diagnosed with IBD: 49 with Crohn's disease, eight with ulcerative colitis and one with IBD-unclassified. FC of 50 μg/g threshold provided a sensitivity of 96.6% [95% confident interval (CI) 88.3-99.4%] and PPV of 72.7% (95% CI 61.9-81.4%) in diagnosing IBD. Two children with IBD however were found to have FC <50 μg/g. Sensitivity in diagnosing IBD was further improved to 98.3% (95% CI 90.7-99.1%) when including FC >50 μg/g or elevated platelet count. Furthermore, PPVs in diagnosing IBD improved when FC at various thresholds was combined with either low albumin or high platelet count. Conclusion: Although FC alone is a useful screening test for IBD, a normal FC alone does not exclude IBD. Extending FC to include albumin or platelet count may improve sensitivity, specificity, PPV and NPV in diagnosing IBD. However, prospective studies are required to validate this conclusion.

Fecal calprotectin and colorectal cancer

Fecal calprotectin (FC) is a bioactive protein secreted by inflammatory cells in the intestine, having anti-microbial and anti-infection activities. The content of FC reflects the inflammatory state of the intestine, and its role in inflammatory bowel disease has been translated into clinical practice. In recent years, the application of FC in colorectal cancer (CRC) has been increasing. Previous research results show that FC can be used to screen colorectal cancer and differentiate it from other intestinal diseases, and the concentration of FC may be related to the stage, location, and resectability of CRC. However, its role still needs to be further clarified through high-quality, large-sample research. This paper reviews the application of FC in colorectal cancer.

Exploring Iron Withholding by the Innate Immune Protein Human Calprotectin

Calprotectin (CP) is a versatile player in the metal-withholding innate immune response, a process termed "nutritional immunity." CP is a heterooligomer of the polypeptides S100A8 and S100A9 and houses two transition-metal-binding sites at its S100A8/S100A9 heterodimer interface. During infection, CP is released from host cells and sequesters "bioavailable" transition metal ions in the extracellular space, thereby preventing microbial acquisition of these essential nutrients. For many years, the role of CP in nutritional immunity was interpreted in the contexts of Mn(II) and Zn(II) limitation, but recent work has broadened our understanding of its contributions to this process. We uncovered that CP provides a form of nutritional immunity that has previously received little attention: the battle between host and microbe for ferrous iron (Fe(II)). In this Account, we present our current understanding of Fe(II) coordination by CP and its role in Fe(II) withholding as well as considerations for future discovery. Nutritional immunity was first described in the context of host-microbe competition for ferric iron (Fe(III)). The battle for Fe(II) has received comparably little attention because the abundance of Fe(II) at infection sites and the importance of Fe(II) acquisition for microbial pathogenesis were recognized only recently. Several years ago, we discovered that human CP sequesters Fe(II) at its His6 site with subpicomolar affinity and thus hypothesized that it provides a means for Fe(II) limitation by the host during microbial infection. Fe(II) coordination by CP is unprecedented in biology because of its novel hexahistidine coordination sphere and its high-affinity binding, which surpasses that of other known Fe(II)-binding proteins. CP is also capable of shifting the Fe redox equilibrium by stabilizing Fe(II) in aerobic solution and can thereby sequester Fe in both reducing and nonreducing environments. These coordination chemistry studies allowed us to hypothesize that CP provides a means for Fe(II) limitation by the host during microbial infection. While investigating this putative Fe(II)-sequestering function, we discovered that CP withholds Fe from diverse bacterial pathogens. Recent studies by our lab and others of the bacterial pathogens Pseudomonas aeruginosa and Acinetobacter baumannii have shown that, by preventing sufficient Fe acquisition, CP induces Fe starvation responses in these organisms. As a result, CP affects bacterial virulence and metabolism. We also elucidated a complex interplay between CP and secondary metabolites produced by P. aeruginosa during the competition for Fe. Our work provides a foundation for understanding how CP affects Fe homeostasis during microbial infection. We believe that understanding how bacterial physiology is altered when challenged with Fe(II) withholding by CP will likely reveal crucial determinants of bacterial survival within the host.

Analytical Performance and Clinicopathologic Correlation of Four Fecal Calprotectin Methods

OBJECTIVES

Calprotectin is a noninvasive biomarker that can distinguish inflammatory bowel disease from irritable bowel syndrome. We investigated four automated fecal calprotectin methods on five different platforms for their preanalytical process, analytical performance, and clinicopathologic correlation.

METHODS

Four calprotectin methods (Bühlmann, EliA CN, EliA CN2, and DiaSorin) were performed on five platforms (Cobas 8000 E502, Phadia Immunocap 100 and 250, and Liaison and Liaison XL) in two hospital laboratories.

RESULTS

Overall variation for the different extraction devices was less than 19% when feces were of normal consistency. Freeze-thawing of samples resulted in comparable results compared with fresh samples. The different methods had a good analytic correlation (R = 0.83-0.95). Their clinicopathologic correlation was comparable, but the Bühlmann method showed significantly higher calprotectin values in every patient category.

CONCLUSIONS

The automated calprotectin methods showed a good performance and comparable clinicopathologic correlation. Due to lack of standardization, the numerical values differ for the various methods.

Utility of Diagnostic Tests in Children With Functional Abdominal Pain Disorders

Functional gastrointestinal disorders (FGIDs) and functional abdominal pain disorders (FAPDs) are common in pediatric patients. The prevalence of FGIDs using the Rome IV criteria ranges from 21.1% to 25.0% in children. The Rome IV criteria specify that the decision of testing is left to the clinician, giving him or her freedom to decide on the necessary workup. The clinician should consider all of the functional and organic diseases that manifest with chronic abdominal pain, as well as alarm features that should prompt testing. Societal guidelines and reports do not recommend routine evaluations for FAPDs, particularly in the absence of alarm features. Studies have reported variable results upon assessing the diagnostic yields of different tests. Furthermore, these evaluations considerably increase costs for the health care system. This article examines the current evidence on the utility of diagnostic testing in pediatric patients with FAPDs.

Clinical utility of fecal calprotectin: potential applications beyond inflammatory bowel disease for the primary care physician

Fecal calprotectin (FC) is an inflammatory marker released mainly from gastrointestinal granulocytes measured in stool samples. FC is noninvasive, economical, simple, and acceptable for patients. Levels of FC have proven reliable for intestinal inflammation, with good clinical sensitivity, and are useful in screening and monitoring inflammatory bowel disease (IBD), as well as in the differential diagnosis between IBD and irritable bowel syndrome (IBS). Given its advantages, FC represents an attractive biomarker that could be utilized in various gastrointestinal (GI) diseases apart from IBD, and is currently being studied extensively by many research groups with significant amounts of data emerging. In this current review we aim to provide an outline of the utility of FC in distinguishing between IBS and IBD, as well as an up-to-date summary of the available clinical experience concerning FC in various common conditions of the GI tract commonly encountered by gastroenterology practitioners, such as IBS, microscopic colitis, acute gastroenteritis, Clostridium difficile infection, colorectal cancer, diverticular disease, coeliac disease, and other GI conditions.

Mucosal Profiles of Immune Molecules Related to T Helper and Regulatory T Cells Predict Future Relapse in Patients With Quiescent Ulcerative Colitis

BACKGROUND

T helper (Th)- and regulatory T (Treg) cell-related immune molecules are implicated in ulcerative colitis (UC). However, the association between their mucosal expression during remission and the subsequent clinical course of UC is unknown.

METHODS

The expression of cytokines and transcription factors related to Th1, Th2, Th17, and Treg in endoscopic mucosal biopsy specimens from 40 UC patients in clinical remission and 9 controls was measured by quantitative polymerase chain reaction. The relationship between their expression patterns, as stratified by Mayo Endoscopic Subscore (MES), and any future relapse was evaluated by univariate and multivariate analyses.

RESULTS

Six of 40 patients (baseline MES 0/1/2, 22/14/4) experienced a relapse during the study period (median, 37 months). At baseline, even in the MES0 patients, the interleukin (IL)-17A of the patients was significantly upregulated in comparison with controls (P = 0.0351). Future relapse was associated with a higher baseline expression of IL-17A, IL-17F, and IL-21 in MES0/1, and the upregulation of IL-17F and IL-21 remained statistically significant when limited to MES0 patients. Kaplan-Meier analysis revealed that as a single marker, a higher IL-21 level best grouped patients with an increased risk of relapse (P = 0.0042). Furthermore, a multivariate model that consisted of IL-21 and T-bet showed an even greater value (P = 0.0001).

CONCLUSIONS

The profiles of Th/Treg-related gene expression in the colonic mucosa are altered, even during clinical and endoscopic remission of UC, with a detectable Th17-predominant profile predicting future relapse. This association might represent latent immune dysregulation during disease quiescence and has the potential to be utilized to improve patient care.