Introduction

Unclear etiology of IBD, the frequent similarity of their clinical and endoscopic manifestations, lack of a gold standard in diagnosing diseases, which complicates the choice of targeted therapy, urgently require improving the efficiency of currently available diagnostic technologies [1]. Significant efforts are being made to search for biomarkers that can be used to identify patients at high risk of IBD relapse who need more intensive monitoring and therapy in the early stages of these diseases, in remission to prevent long-term irreversible structural damage [2].

Aims & Methods

The purpose of the research was to study the levels of fatty acids (FAs) in red blood cells (rbc) membranes and blood serum in patients with IBD examined under follow-up control as possible predictors of disease exacerbation.
During our study, 44 patients with IBD have been monitored, in the course of that period, the average age was equal to 36.3±5.2. The first examination has been performed in remission of the diseases, the second one 6 to 12 months after the first step, and it has been done in the acute stage of IBD. The composition of the FAs has been studied using gas chromatography-mass spectrometry (Agilent 7000B (USA).

Results

Predictors of exacerbation progress in patients with IBD have been found to be reduced levels of such FAs as C20:5 n-3 (p=0.002), C18:3 n-3 (p=0.039), C20:2 n-6 (p=0.002), C16:2 n-6 (p=0.006), C22: 4 n-6 (p=0.008), and on the contrary, increased content of FA C18:0 (p=0.005), SFAs/USFAs (p=0.039), SFAs/PUFAs (p=0.03) in rbc membranes and FA C20:0 in blood serum (p=0.008). The diagnostic model created was able to predict the exacerbation progress with a sensitivity of 87.2%, specificity of 91.3% (AUC 0.936), incorporating the above-described fatty acids with respect to their degree of contribution. We have found correlations of rbc C18:0 with haemoglobin level (r=-0.344, p<0.001), erythrocyte sedimentation rate (r=0.480, p=0.012), fibrinogen level (r=0.352, p=0.004); rbc C18:3n-3 - with level of C-reactive protein (r=-0.472, p=0.023), fibrinogen (r=-0.420, p=0.022), faecal calprotectin (r=-0.391, p=0.044). The content of rbc C16:2n-6 was directly correlated with the level of fecal calprotectin (r=0.407, p=0.028), ratio of SFAs/USFAs was depending on the number of leukocytes (r=0.411, p=0.046). The function of elevated levels of SFAs as predictors of exacerbation of IBD is probably determined by the fact that they potentially regulate inflammatory reactions by acting on the pathways of the PPAR-γ and retinoid X receptors (RXR) [3]. Reduced levels of C18:3n-3 as a predictor of exacerbation may be related to the ability of this FA to reduce the activity of ionised calcium-binding adaptor molecule 1-positive macrophages [4] and to reduce the expression of proinflammatory genes IL-8, COX2 and inducible nitric oxide synthase to reduce intestinal inflammation [5]. The significance of C20:5n-3 for prediction of the active stage of IBD is due to the fact that it inhibits the inflammatory pathways of transforming growth factor beta-1/epidermal growth factor receptor P-EGFR and NF-κB, and it also modulates redox balance and mitigates the progression of UC [6]. Reduced levels of several omega-6 PUFAs may be related to their increased consumption during elongation, desaturation, including in the arachidonic cascade associated with the cynthesis of proinflammatory cytokines [7].

Conclusion

The use of fatty acids of rbc membranes and blood serum is promising and pathogenetically justified, namely as biomarkers for predicting the exacerbation progress in patients with IBD.

References

1. Seyedian SS, Nokhostin F, Malamir MD. A review of the diagnosis, prevention, and treatment methods of inflammatory bowel disease. J Med Life. 2019 Apr-Jun;12(2):113-122. doi: 10.25122/jml-2018-0075.
2. Tibble J.A., Sigthorsson G., Bridger S.et al. Surrogate markers of intestinal inflammation are predictive of relapse in patients with inflammatory bowel disease. Gastroenterology. 2000; 119: 15–22. doi:10.1053/gast.2000.8523
3. Mozaffarian D. Trans fatty acids effects on systemic inflammation and endothelial function. Atheroscler Suppl (2006) 7(2):29–32. doi: 10.1016/ j.atherosclerosissup.2006.04.007
4. Kim J, Ahn M, Choi Y. et al. Alpha-linolenic acid alleviates dextran sulfate sodium-induced ulcerative colitis in mice. Inflammation (2020) 43(5):1876–83. doi: 10.1007/s10753-020-01260-7
5. Reifen R, Karlinsky A, Stark AH. et al. A-linolenic acid (Ala) is an anti-inflammatory agent in inflammatory bowel disease. J Nutr Biochem (2015) 26 (12):1632–40. doi: 10.1016/j.jnutbio.2015.08.006
6. El Mahdy RN, Nader MA, Helal MG. et al. Eicosapentaenoic acid mitigates ulcerative colitis-induced by acetic acid through modulation of nf-Kb and tgf-B/egfr signaling pathways. Life Sci (2023) 327:121820. doi: 10.1016/j.lfs.2023.121820
7. Ajabnoor SM, Thorpe G, Abdelhamid A, Hooper L. Long-term effects of increasing omega-3, omega-6 and total polyunsaturated fats on inflammatory bowel disease and markers of inflammation: a systematic review and meta-analysis of randomized controlled trials. Eur J Nutr. 2021 Aug;60(5):2293-2316. doi: 10.1007/s00394-020-02413-y.

Introduction

Inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis (UC), are chronic advanced immune-mediated inflammatory diseases of unknown etiologies [1, 2]. There is still no unified “gold standard” for the diagnosis of IBDs; the diagnosis is usually made on the basis of data sets which include medical history, clinical manifestations, typical endoscopic views and histological signs, therefore, between 5% and 15% of cases of IBDs do not meet the strict criteria for either UC or CD, and in 14% of patients diagnosed with both UC and CD, the diagnosis can be changed over time [3, 4].

Aims & Methods

Research objective is as follows: To develop a diagnostic method for the IBDs including differential diagnosis, using a combination of indicators, such as fecal, hematological, serological, fatty acids' (FA) levels of erythrocyte (RBC) membranes and blood serum (BS).
A total of 91 patients (average age 37.7 ± 12.1 years old) with IBDs and 53 patients of the comparison group (43.3 ± 11.7 years old) have been examined. The group of patients with IBDs have included patients with ulcerative colitis (UC) – 50 persons and with Crohn’s disease (CD) – 41 persons. In the examined patients, the red blood parameters and biochemical parameters have been studied by standard methods, as for the level of fecal calprotectin, it has been researched by the enzyme-linked immunosorbent assay (ELISA), and the levels of fatty acids of erythrocyte membranes and blood serum have been investigated by the gas chromatography–mass spectrometry (GC-MS) (Agilent 7000B, USA).

Results

In a comparative analysis of patient groups using statistical analysis, a composite set of indicators has been found to be the most significant in distinguishing the patients with acute UC from comparison group individuals: hemoglobin levels (p<0.00001), sedimentation rate (p<0.00001), ferritin levels (p<0.00001), fecal calprotectin (p<0.00001), and oleic acid content (p=0.0031), polyunsaturated fatty acids in erythrocyte membranes (p<0.05), arachidonic acid in erythrocyte membranes and blood serum (p<0.05), and serum PUFAs (p=0.0018) and n6/n3 PUFA ratio (p=0.0005). Diagnostic models have been developed using machine learning methods using data analysis libraries of the Python programming language. The first model, which includes a combination of the above indicators, allows to perform the calculation of the diagnostic index Y _D1 to differentiate healthy individuals from patients with IBDs (AUC 0.957, sensitivity 0.974, specificity 0.941). The second diagnostic model for distinguishing patients with acute ulcerative colitis from patients with active Crohn's disease (AUC 0.887, sensitivity 0.993, specificity 0.840) have considered the levels of hemoglobin, hematocrit, mean corpuscular volume of erythrocytes (p=0.007), mean cell hemoglobin concentration and content in the RBCs (p<0.05), ESR (p<0.05), C-reactive protein (p=0.002), ferritin (p=0.014), fibrinogen (p<0.0001), fecal calprotectin (p=0.005), and erythrocyte level of oleic acid (p<0.05).

Conclusion

The diagnostic models that have been created include fecal, serum markers of inflammation, as well as levels of fatty acids pathogenetically associated with the activity of IBDs, which ensures their high diagnostic accuracy. The non-invasive nature, an availability of indicators, and a convenient algorithm allow us to optimize and expedite the diagnosis of the IBDs.

References

1. Kaplan G.G., Ng S.C. Understanding and preventing the global increase of inflammatory bowel disease. Gastroenterology. 2017 Feb; 152(2):313-321.e2. DOI: 10.1053/j.gastro.2016.10.020.
2. Maaser C., Sturm A., Vavricka S.R., Kucharzik T., Fiorino G., Annese V., et al. European Crohn’s and Colitis Organisation [ECCO] and the European Society of Gastrointestinal and Abdominal Radiology [ESGAR]. EC-CO-ESGAR Guideline for Diagnostic Assessment in IBD Part 1: Initial diagnosis, monitoring of known IBD, detection of complications. J Crohns Colitis. 2019;13(2):144– 64. DOI: 10.1093/ecco-jcc/jjy113
3. Abraham B.P., Mehta S., El-Serag H.B. Natural history of pediatric-onset inflammatory bowel disease: a systematic review. J Clin Gastroenterol. 2012;46(7):581–9. DOI: 10.1097/MCG.0b013e318247c32f
4. Henriksen M., Jahnsen J., Lygren I., Sauar J., Schulz T., Stray N., et al. Change of diagnosis during the first five years after onset of inflammatory bowel disease: results of a prospective follow-up study (the IBSEN Study). Scand J Gastroenterol. 2006;41(9):1037–43. DOI: 10.1080/00365520600554527.

Introduction

Apelin, an adipokine secreted from visceral fat, has been associated with endothelial cells dysfunction‐related chronic inflammatory diseases. Decreased serum apelin levels have been found in patients with cardiovascular disease (CVD). Higher apelin levels have been measured in mesenteric adipose tissue and inflamed colonic epithelium of patients with Inflammatory Bowel Disease (IBD), but data on the role of serum apelin levels in IBD patients are lacking.

Aims & Methods

We aimed to a) compare serum apelin levels between 104 consecutive IBD patients and 104 age and sex matched healthy controls (blood donors), b) to evaluate the correlation between serum apelin levels with demographics, disease characteristics, treatment and disease course.
Serum apelin-13 levels were measured using ELISA (Wuhan Fine Biological Technology Co., Ltd). Statistical analysis was performed with SPSS 24 (SPSSInc. Chicago, IL, USA).

Results

Mean apelin levels were significantly higher in IBD patients compared to their matched healthy controls (1996.29 ± 1592.96pg/ml vs 1552.99 ± 809.64, p=0.012). Among the examined parameters only smoking was found independently associated with serum apelin levels in IBD patients (p<0.001).
IBD patients with CVD (25) had lower but not significant different serum apelin levels compared to patients without CVD (79) (1743.01 ± 1116.26pg/dl vs 2465.09 ± 2006.51pg/ml, p=0.122). In a subgroup analysis of patients without CVD (79 IBD patients) significantly elevated serum apelin levels were found in patients with extended UC, history of immunomodulator use and absence of musculoskeletal EIMs (2539,69 ± 1969.29pg/ml vs 1164.45 ± 818.89pg/ml, p=0.044, 2317.69 ± 1867.99pg/ml vs 1451.40 ± 1024.20pg/ml, p=0.043 and 2340.58 ± 1850.16pg/ml vs 1392.09 ± 1054.99pg/ml, p=0.027, respectively).
Finally, a moderate positive correlation was found among UC extent and serum apelin levels in patients without CVD (r=0.525, p=0.004). Νegative correlations were found among age at study entry and serum apelin levels in both IBD patients without CVD and all IBD patients (r=-0.263, p=0.001 and r=-0.214, p=0.002, respectively) and between immunomodulator use, history of musculoskeletal EIMs and serum apelin levels in patients without CVD (r=-0.26, p=0.021 and r=-0.336, p=0.005, respectively).

Conclusion

The circulating serum apelin levels are significantly increased in IBD patients compared to matched healthy controls. Increased apelin levels are independently associated with smoking status and disease extend (in UC). IBD patients with musculoskeletal manifestations have decreased serum apelin levels compared to IBD patients without musculoskeletal manifestations. Further investigation with larger studies on the role of serum apelin in IBD is needed.

Disclosure

None

Introduction

Inflammatory bowel diseases (IBD) are mainly represented by Crohn's Disease (CD) and Ulcerative Colitis (UC). Among several factors related to these diseases, dysbiosis is considered an immediate environmental factor for the development of IBD. Dysbiosis is related to the imbalance of the intestinal microbiota, which affects the existing symbiotic relationship between the intestinal microbiota and its host that provides a nutrient-rich environment for intestinal bacteria, while the microbiota plays a fundamental role in maintaining the intestinal function of its host. Among these functions, the microbiota has its participation in the digestion of complex polysaccharides present in the host diet, important for the formation of monosaccharides and short-chain fatty acids (SCFA), such as acetate, propionate, and butyrate. These SCFA are important in maintaining the intestinal barrier and intestinal homeostasis, in proliferation, differentiation and modulation of gene expression of intestinal cells, in the production of essential vitamins in the intestinal lumen, in addition to acting in regulation of the mechanisms that provide balance between the intestinal mucosa and its immune system, resulting in the tolerance of harmless bacteria and immune responses against pathogenic bacteria. There are several studies on the intestinal microbiota in patients with IBD, however, there are still few studies on the SCFA profile in these patients. Therefore, the present study aimed to evaluate and compare the SFCA profile in patients with IBD and healthy individuals.

Aims & Methods

94 patients from a public outpatient healthcare service in Brazil and 63 healthy individuals were included in the study. Exclusion criteria: diagnosis of other chronic diseases, use of antibiotics, prebiotics, probiotics or symbiotics in the last 4 weeks. Participants were divided into two groups, IBD group and control group (healthy), fecal samples from all participants were collected for qualitative and quantitative analysis of SCFA, which was performed by gas chromatography technique coupled with mass spectrometry (GC/MS). Statistical analysis: descriptive statistics and association tests. Values of p ≤ 0.05 were considered significant. Data presented in mean (SD).

Results

The SCFA profiles were different in IBD patients compared to healthy individuals, with higher SCFA values in the IBD group when compared to the control group: acetic acid (0.32 ± 0.18 vs 0.12 ± 0.11, with p< 0.0001), propionic acid (0.24 ± 0.10 vs 0.15 ± 0.09, with p< 0.0001), butyric acid (0.19 ± 0.11 vs 0.39 ± 0.25, with p< 0.0001) and sum of SCFA (0.75 ± 0.32 vs 0.39 ± 0.25, with p< 0.0001) concentration.

Conclusion

The SFCA profile in patients with IBD showed a difference when compared to healthy individuals, where the values of SFCA fecal were higher in patients with IBD compared to healthy individuals. Such a difference may occur because the IBD group, due to the inflammatory process characteristic of the disease, may have greater difficulty in absorbing the SCFA produced in the intestine, releasing more SCFA in the feces, since most of the SCFAs produced in the colonic lumen (90-95%) are absorbed by the intestinal mucosa and only 5 to 10% are excreted in the feces. However, to confirm this hypothesis, further studies would be needed to evaluate and compare the SFCA systemic between these groups, through blood test, and thus determine the SFCA profile of these individuals, being able to propose therapies that help in the modulation of the microbiota of these patients and in the development of new treatment targets in the future.

References

1. García‐Villalba R, et al. Journal of separation science. 2012; 35(15): 1906-1913.
2. Kaplan GG. Nature reviews Gastroenterology & hepatology.2015; 12(12): 720-727.
3. Sánchez-Tapia M, Tovar AR, Torres N. Archives of Medical Research. 2019; 50(5): 259–268.
4. Schirmer M, et al. Nature Reviews Microbiology. 2019; 17(8): 497-511.
5. Zhao G, Nyman M, and Jönsson, A J. Biomedical Chromatography. 2006; 20(8): 674-682.

Introduction

Inflammatory bowel disease (IBD) is strongly associated with joint inflammation, as is highlighted by the high prevalence of spondyloarthritis (SpA) in patients with IBD (up to 13%) compared to the general population (0.2-1.6%) [1, 2]. IBD and SpA have many overlapping features, including genetic risk factors, changes in the gut microbiota, and therapies targeting TNF-α , IL-23, or JAK [3]. However, current therapies for both diseases are unable to break the cycle of chronic inflammation, and still a significant proportion of patients fail to respond. Disease heterogeneity likely plays a role in this [4, 5], underscoring the necessity to improve management and refine classification.

Aims & Methods

In this study, 92 inflammation-related proteins were quantified in serum of patients from one IBD and one SpA cohort using the novel Olink proteomics proximity extension assay. Fold changes (FC) in expression with |log₂FC| > 0.5 were considered meaningful, and false discovery rates (FDR) <0.05 were considered significant. The IBD cohort existed of 255 IBD patients with (n=155) and without (n=100) self-reported joint complaints [8]. From the patients with joint complaints, 58 fulfilled any of the SpA criteria. The SpA cohort, or SPACE cohort, consisted of 169 patients with chronic back pain (≥3 months, ≤2 years) of unknown origin [9]. After 2 years of follow-up, 85 patients had proven axSpA. Serum samples were taken at baseline, and 167/169 samples from the SPACE cohort and 241/255 samples from the IBD cohort passed quality control and were included in the analysis.

Results

Thirty-four proteins were differentially expressed between 95 IBD patients without joint complaints and 85 proven axial SpA (axSpA) patients from the SPACE cohort, of which 14 were higher in IBD patients (including 4E‑BP1, IFN‑γ, TNF, FGF‑21, CD8A, and CCL9), and 20 were higher in axSpA patients (including CASP‑8, SIRT2, STAMBP, FGF‑19, ST1A1, and EN‑RAGE). In addition, the immune profile of IBD patients with joint complaints differed from IBD patients without joint complaints: 4E‑BP1, CASP-8, STAMBP, SIRT2, AXIN1, and TNFSF14, were significantly upregulated in patients with joint complaints. Of note, if IBD patients without joint complaints were compared to the subgroup of 58 patients with joint complaints who met criteria for SpA, the same proteins showed significant upregulation, suggesting minimal difference between IBD patients with joint complaints who meet or who do not meet SpA criteria. Direct comparison of patients who met and who did not meet SpA criteria within the group of IBD patients with joint complaints indeed showed no noteworthy difference in serum immune profile. Within the SPACE cohort, comparison of patients with chronic back pain with and without axSpA diagnosis also showed no significant difference in serum protein expression.

Conclusion

This study shows that patients with axSpA versus patients with IBD without joint complaints have differing serum immune profiles. Within IBD patients with self-reported joint complaints and within patients with self-reported chronic back pain (from the SPACE cohort), no distinct difference in immune profile is observed, regardless of SpA diagnosis. The inflammation signatures of patients with chronic inflammatory diseases should be further investigated to provide insights for enhancing disease management in the future.

References

1. Karreman, M.C., et al., The Prevalence and Incidence of Axial and Peripheral Spondyloarthritis in Inflammatory Bowel Disease: A Systematic Review and Meta-analysis. J Crohns Colitis, 2017. 11(5): p. 631-642.
2. Stolwijk, C., et al., Global Prevalence of Spondyloarthritis: A Systematic Review and Meta-Regression Analysis. Arthritis Care Res (Hoboken), 2016. 68(9): p. 1320-31.
3. Gracey, E., et al., Revisiting the gut-joint axis: links between gut inflammation and spondyloarthritis. Nat Rev Rheumatol, 2020. 16(8): p. 415-433.
4. van Unen, V., et al., Mass Cytometry of the Human Mucosal Immune System Identifies Tissue- and Disease-Associated Immune Subsets. Immunity, 2016. 44(5): p. 1227-39.
5. Gulino, G.R., M. Van Mechelen, and R. Lories, Cellular and molecular diversity in spondyloarthritis. Semin Immunol, 2021. 58: p. 101521.
6. van Erp, S.J., et al., Classifying Back Pain and Peripheral Joint Complaints in Inflammatory Bowel Disease Patients: A Prospective Longitudinal Follow-up Study. J Crohns Colitis, 2016. 10(2): p. 166-75.
7. Marques, M.L., et al., Can rheumatologists unequivocally diagnose axial spondyloarthritis in patients with chronic back pain of less than 2 years duration? Primary outcome of the 2-year SPondyloArthritis Caught Early (SPACE) cohort. Ann Rheum Dis, 2024. 83(5): p. 589-598.

Disclosure

FAG: grants from Stichting vrienden van Sole Mio and Stichting ASAS, grants and/or consulting fees from Abbvie, ASAS, BMS, Galapagos, Janssen, Lilly, Novartis, Pfizer, and UCB.
AEM: grants from Nestle, Norgine, Cablon, Galapagos, and ZonMW, ad boards/speaker fees from Tramedico, Janssen, Takeda, Galapagos, Vedanta, Ferring, AbbVie, and Dear Health.
PV: speaker fees from Takeda and Galapagos, advisory board: Takeda, Galapagos, Lilly, BMS, Janssen, and Abbvie

Introduction

Inflammatory bowel disease (IBD) is a chronic inflammatory process closely linked to diet and nutrition. Diet and nutrition have been proposed to be significantly involved in the pathogenesis of IBD, although their specific propagation and attenuation of gut inflammation remains unclear.

Aims & Methods

Using paired dietary history and serum immunoproteins, we sought to investigate the association of various nutritional components in multi-ethnic Asian IBD patients from a single-center academic hospital in Singapore. Participants completed a self-administered validated 163-item semi-quantitative food frequency questionnaire to determine dietary intake. Adequate micronutrient intake was determined by the recommended dietary allowance (RDA) as stipulated by the Singapore Health Promotion Board. Participants also had 88 paired serum immunoproteins profiled using the Olink Target 96 Inflammation assay. Spearman correlation analysis, with false discovery rate, was used to identify significant diet-immune associations.

Results

Our study cohort included 40 (55.6%) patients with Crohn's disease and 32 (44.4%) patients with ulcerative colitis, with a median age of 40 years (range 30.5 - 57.0). More than two-thirds (n=51, 70.8%) were male. The median body mass index was 23.4kg/m2 (range 20.0 - 26.3). In our study, IBD patients self-reported to be taking insufficient dietary fiber and vitamin A, whereby 86.1% and 58.3% of IBD patients, were taking lower than the RDA for dietary fibre (n=62, median 15.9g/day) and vitamin A (n=42, median 706mcg/day), respectively.
Using spearman correlation, we identified 192 significant (p<0.05) diet-immune associations from only 39 (44%) of the 88 immunoproteins screened. Of note, 8 immunoproteins (4E-BP1, CASP-8, CDCP1, FGF-23, IL-17A, IL-20RA, IL-22 RA1, STAMBP) accounted for almost half (n=92/192) of all the significant diet-inmune associations. Only beta carotene and vitamin A were negatively associated with pro-inflammatory immunoproteins, such as Interleukin-18, Interleukin 10-receptor subunit beta, C-C motif chemokine 19, Vascular endothelial growth factor A, and and Urokinase-type plasminogen activator.
Table 1. List of immunoproteins and their key molecular functions and micronutrient-immunoprotein associations. Eight immunoproteins (4E-BP1, CASP-8, CDCP1, FGF-23, IL-17A, IL-20RA, IL-22 RA1, STAMBP) were identified to have the most diet-immune associations, accounting for almost half (n=92/192) of all significant associations identified.

Protein Name	Function	Count of diet-immune associations	Specific dietary associations
Eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1)	Enables protein binding (GO:0005515) Enables eukaryotic initiation factor 4E binding (GO:0008190) Enables translation repressor activity (GO:0030371)	11	Iron Calcium Riboflavin MUFA Protein Zinc CHO Starch Energy SFA Total fat
Caspase-8 (CASP-8)	Enables cysteine-type endopeptidase activity (GO:0004197) Enables death receptor binding (GO:0005123) Enables tumor necrosis factor receptor binding (GO:0005164) Enables protein binding (GO:0005515) Enables peptidase activity (GO:0008233)	13	Vitamin A Iron Thiamine Potassium Calcium Riboflavin MUFA Protein Zinc CHO Energy PUFA SFA Total fat
CUB domain containing protein 1 (CDCP-1)	Enables protein binding (GO:0005515)	10	BCarotene Vitamin A Vitamin C Potassium Riboflavin MUFA Protein Zinc SFA Total fat
Fibroblast growth factor 23 (FGF-23)	Positive regulation of protein kinase B signalling (GO:0051897) MAPK cascade (GO:0000165) Fibroblast growth factor receptor binding (GO:0005104) Enables type 1 fibroblast growth factor receptor binding (GO:0005105) Enables protein binding (GO:0005515) Enables growth factor activity (GO:0008083)	11	Iron Thiamine Potassium Calcium Riboflavin Zinc Energy PUFA SFA Total fat Dietary fiber
Interleukin-17A (IL-17A)	Positive regulation of antimicrobial peptide production (GO:0002225) Adaptive immune response (GO:0002250) immune system process (GO:0002376) Apoptotic process (GO:0006915) Inflammatory response (GO:0006954)	11	Iron Potassium MUFA Protein Zinc CHO Starch Energy PUFA SFA Total fat
Interleukin-20 receptor subunit alpha (IL-20RA)	Cytokine receptor activity (GO:0004896) Enables protein binding (GO:0005515) Enables interleukin-20 binding (GO:0042015)	11	Thiamine Potassium Calcium Riboflavin MUFA Protein Zinc Energy PUFA SFA Total fat
Interleukin-22 receptor subunit alpha-1 (IL-22RA1)	Cytokine receptor activity (GO:0004896) Enables interferon receptor activity (GO:0004904) Enables protein binding (GO:0005515) Enables interleukin-20 binding (GO:0042015)	13	BCarotene Vitamin C Iron Potassium Calcium Riboflavin MUFA Energy PUFA SFA Total fat Dietary fiber Sugar
STAM-binding protein (STAMBP)	Enables protein binding (GO:0005515) Peptidase activity (GO:0008233) Metallopeptidase activity (GO:0008237) Hydrolase activity (GO:0016787) Enables protein domain specific binding (GO:0019904)	16	Vitamin A Iron Thiamine Potassium Calcium Riboflavin Protein Zinc CHO Starch Energy PUFA SFA Total fat Dietary fiber Sugar

Conclusion

Our study found specific components of the diet, such as carbohydrates, starch, fiber to be positively associated with inflammatory immunoproteins. Only vitamin A and beta-carotene were negatively associated with circulating immunoproteins. We hope our findings assist in the development of specific dietary therapies to provide IBD patients with specific nutrient requirements and yet limit specific dietary substrates that may propagate gastrointestinal inflammation. Further studies are required to investigate the mechanisms of these nutritional factors involved in inflammation and to evaluate the application of specific diets during the course of IBD.

References

1. Mentella, M. C., Scaldaferri, F., Pizzoferrato, M., Gasbarrini, A., &amp; Miggiano, G. A. (2020). Nutrition, IBD and Gut Microbiota: A Review. Nutrients, 12(4), 944. https://doi.org/10.3390/nu12040944

2. Neelakantan, N., Whitton, C., Seah, S., Koh, H., Rebello, S., Lim, J., Chen, S., Chan, M., Chew, L., &amp; van Dam, R. (2016). Development of a semi-quantitative food frequency questionnaire to assess the dietary intake of a multi-ethnic urban Asian population. Nutrients, 8(9), 528. https://doi.org/10.3390/nu8090528

Introduction

Both patients and clinicians would benefit from less invasive means than endoscopy for detection of gut inflammation in inflammatory bowel disease (IBD), such as faecal or serological biomarkers.

Aims & Methods

The aim of this study was to investigate the presence of the neutrophilic proteins: calprotectin (CP), myeloperoxidase (MPO), neutrophil gelatinase-associated lipocalin (NGAL) and the eosinophilic protein: eosinophil-derived neurotoxin (EDN) in faecal and serum samples from IBD patients with ulcerative colitis (UC) and Crohn’s disease (CD) in relation to disease activity and intestinal inflammation localization. Their diagnostic potential in IBD was studied using irritable bowel syndrome (IBS) patients as controls.
Faecal (f) and serum (s) samples from 97 IBD (median: 38y, range 18-79y) and 100 IBS (median: 36y, range 18-75y) patients from the outpatient Gastroenterology Clinic, Uppsala University Hospital were included in the study. Active disease was defined as having a Partial Mayo score ≥ 2 (UC) or Harvey-Bradshaw score ≥5 (CD). Disease localization was obtained from patient journals.
CP and EDN were measured by commercial EliA and ImmunoCAP assays, respectively. MPO and NGAL were measured with in-house research assays based on the ImmunoCAP technology. All analyses were done using the automated Phadia 250 instrument.

Results

All four biomarkers were elevated in IBD compared to IBS in faecal samples (p<0.001) and serum (p<0.01), and most biomarkers were also elevated in the separate UC and CD groups (Table 1). Faecal EDN were higher in CD compared to both UC (p=0.016) and IBS.
Table 1. Biomarker levels in UC and CD patients in comparison to IBS patients

	UC N=59	CD N=38	IBS N=100	p-value (UC vs. IBS)	p-value (CD vs. IBS)
fCP	305.8 mg/kg	165.8 mg/kg	16.51 mg/kg	<0.0001	<0.0001
fMPO	3.74 mg/kg	2.42 mg/kg	0.10 mg/kg	<0.0001	<0.0001
fNGAL	7.30 mg/kg	6.78 mg/kg	2.36 mg/kg	<0.0001	<0.0001
fEDN	0.50 mg/kg	1.79 mg/kg	0.29 mg/kg	0.049	<0.0001
sCP	4186 µg/L	4124 µg/L	3037 µg/L	0.0145	ns
sMPO	291.6 µg/L	291.2 µg/L	151.3 µg/L	0.0006	0.0038
sNGAL	240.2 µg/L	239.5 µg/L	162.2 µg/L	<0.0001	0.0004
sEDN	29.07 µg/L	24.54 µg/L	19.4 µ/L	0.0020	ns

Four biomarkers were elevated in active UC vs remission: fCP (610.9 mg/kg vs 45.5 mg/kg, p=0.0180), fMPO (6.84 mg/kg vs 1.30 mg/kg, p=0.0479), sCP (4599 µg/L vs 3128 µg/L, p=0.0194) and sNGAL (298.3 µg/L vs 189.3 µg/L p=0.0012). No association was observed between the biomarkers and disease activity in CD.
Patients with extensive UC had significantly higher levels, compared to patients with left-sided UC, of fCP (851.6 mg/kg vs 148.3 mg/kg, p=0.0135), fMPO (17.67mg/kg vs 2.84 mg/kg, p=0.0493) and fEDN (1.34 mg/kg vs 0.36 mg/kg, p=0.0146). None of the biomarkers were associated with disease localization in CD.

Conclusion

Faecal and serum CP, MPO, NGAL and EDN may be used as diagnostic biomarkers to differentiate patients with IBD from IBS. Our study indicates that fMPO may be used as an alternative to fCP as disease activity marker in UC, and that sCP and sNGAL are promising novel serum markers for disease activity. In addition to the neutrophil markers, fEDN could be of value for characterization of extensive disease in UC patients. The higher fEDN levels in CD compared to UC observed in the present study indicates an important role of activated eosinophils in the clinical manifestation of CD.
The biomarkers MPO, NGAL and EDN measured both in faecal and serum could, in addition to CP, potentially aid in the clinical decision-making in IBD.

Disclosure

H Ekoff, N Rydell and R Movérare are employed by Thermo Fisher Scientific.