Serum Leucine-Rich α2 Glycoprotein: A Novel Biomarker For Small Bowel Mucosal Activity in Crohn's Disease

Precision Medicine in Inflammatory Bowel Disease: A Spotlight on Emerging Molecular Biomarkers

Inflammatory bowel diseases (IBD) remain challenging in terms of understanding their causes and in terms of diagnosing, treating, and monitoring patients. Modern diagnosis combines biomarkers, imaging, and endoscopic methods. Common biomarkers like CRP and fecal calprotectin, while invaluable tools, have limitations and are not entirely specific to IBD. The limitations of existing markers and the invasiveness of endoscopic procedures highlight the need to discover and implement new markers. With an ideal biomarker, we could predict the risk of disease development, as well as the possibility of response to a particular therapy, which would be significant in elucidating the pathogenesis of the disease. Recent research in the fields of machine learning, proteomics, epigenetics, and gut microbiota provides further insight into the pathogenesis of the disease and is also revealing new biomarkers. New markers, such as BAFF, PGE-MUM, oncostatin M, microRNA panels, αvβ6 antibody, and S100A12 from stool, are increasingly being identified, with αvβ6 antibody and oncostatin M being potentially close to being presented into clinical practice. However, the specificity of certain markers still remains problematic. Furthermore, the use of expensive and less accessible technology for detecting new markers, such as microRNAs, represents a limitation for widespread use in clinical practice. Nevertheless, the need for non-invasive, comprehensive markers is becoming increasingly important regarding the complexity of treatment and overall management of IBD.

Serum Leucine-Rich α2 Glycoprotein Could Be a Useful Biomarker to Differentiate Patients with Normal Colonic Mucosa from Those with Inflammatory Bowel Disease or Other Forms of Colitis

(1) Background: Serum leucine-rich α2 glycoprotein (LRG) has been reported as a useful biomarker for monitoring disease activity in patients with inflammatory bowel disease (IBD). We investigated whether serum LRG can differentiate patients with normal colonic mucosa from those with IBD or other forms of colitis. (2) Methods: Patients with diarrhea, abdominal pain, or bloody stools were consecutively enrolled at their initial visit to our hospital. Serum LRG and C-reactive protein were measured, and a colonoscopy and histology were performed. (3) Results: We enrolled 317 patients (181 men, 136 women; median age: 51 years). Based on the endoscopic and histological criteria, 260 patients were diagnosed with ulcerative colitis (n = 134), Crohn's disease (n = 10), infectious colitis (n = 43), diverticular colitis (n = 17), or nonspecific colitis (n = 56). The remaining 57 patients were diagnosed with normal colonic mucosa including histology. The latter group's median LRG value (9.5 µg/mL, range: 5.8-13.5) was significantly lower than that of the other 260 patients (13.6 µg/mL, range: 6.8-62.7, p < 0.0001). The optimal LRG cut-off value of <10.4 µg/mL was derived from the receiver operating characteristic (ROC) curve, showing a 91% sensitivity and 77% specificity for identifying patients with normal colonic mucosa. (4) Conclusions: serum LRG values < 10.4 µg/mL could be a useful biomarker for predicting patients with normal colonic mucosa.

Biomarkers in inflammatory bowel disease: a practical guide

Inflammatory bowel disease (IBD), comprising ulcerative colitis (UC) and Crohn's disease (CD), is a costly condition in terms of morbidity and healthcare utilization, with an increasing prevalence now approaching 1% in the Western world. Endoscopic assessment of IBD remains the gold standard for diagnosis, evaluation of treatment response and determination of post-operative recurrence, but is expensive and invasive. Biomarkers can facilitate non-invasive disease assessment, with C-reactive protein and faecal calprotectin as the most widely available biomarkers in current clinical practice. This narrative review summarizes the evidence for their use in both UC and CD and offers practical guidance for healthcare providers taking into account the limitations of biomarker interpretation. We present evidence for the future use of novel biomarkers in IBD and discuss how biomarker discovery could deliver the goal of precision medicine in IBD.

Systematic Review and Meta-Analysis of the Use of Serum Leucine-Rich Alpha-2 Glycoprotein to Assess Crohn's Disease Activity

BACKGROUND

Although fecal calprotectin is the most widely used biomarker for assessing Crohn's disease activity, serum leucine-rich alpha-2 glycoprotein has recently attracted attention, especially in Japan. Here we performed a systematic review and meta-analysis of serum leucine-rich alpha-2 glycoprotein to obtain evidence for its accuracy in assessing Crohn's disease activity.

METHODS

On February 1, 2023, we performed searches of PubMed, Web of Science, and CENTRAL. The Prospero number is CRD42023396034. The primary outcomes were the sensitivity and specificity of serum leucine-rich alpha-2 glycoprotein for assessing Crohn's disease activity. We used a bivariate generalized linear mixed model, assuming a binomial distribution at the test level and a bivariate normal distribution at the between-test level.

RESULTS

We selected 9 studies involving 797 individuals in our systematic review. Regarding the primary outcomes, the synthesized sensitivity and specificity of serum leucine-rich alpha-2 glycoprotein were 77.0% (95% confidence interval, 67.8% to 84.2%) and 81.1% (95% confidence interval, 72.6% to 87.4%), respectively. The area under the curve was 0.86, and the partial area under the curve was 0.78. Regarding between-study heterogeneity, both the I2 value by Zhou and Dendukuri approach and the I2 value by Holling sample size-adjusted approaches were 0%.

CONCLUSIONS

Our systematic review and meta-analysis of serum leucine-rich alpha-2 glycoprotein demonstrated its accuracy in assessing Crohn's disease activity. Further studies are needed to demonstrate its clinical utility and clinical validity.

Combination of leucine-rich alpha-2 glycoprotein and fecal markers detect Crohn's disease activity confirmed by balloon-assisted enteroscopy

BACKGROUND/AIMS

Endoscopic activity confirmed by enteroscopy is associated with poor clinical outcome in Crohn's disease (CD). We investigated which of the existing biomarkers best reflects endoscopic activity in CD patients including the small bowel, and whether their combined use can improve accuracy.

METHODS

One hundred and four consecutive patients with ileal and ileocolonic type CD who underwent balloon-assisted enteroscopy (BAE) from October 2021 to August 2022 were enrolled, with clinical and laboratory data prospectively collected and analyzed.

RESULTS

Hemoglobin, platelet count, C-reactive protein, leucine-rich alpha-2 glycoprotein (LRG), fecal calprotectin, and fecal hemoglobin all showed significant difference in those with ulcers found on BAE. LRG and fecal calprotectin showed the highest areas under the curve (0.841 and 0.853) for detecting ulcers. LRG showed a sensitivity of 78% and specificity of 80% at a cutoff value of 13 μg/mL, whereas fecal calprotectin showed a sensitivity of 91% and specificity of 67% at a cutoff value of 151 μg/g. Dual positivity for LRG and fecal calprotectin, as well as LRG and fecal hemoglobin, both predicted ulcers with an improved specificity of 92% and 100%. A positive LRG or fecal calprotectin/hemoglobin showed an improved sensitivity of 96% and 91%. Positivity for LRG and either of the fecal biomarkers was associated with increased risk of hospitalization, surgery, and relapse.

CONCLUSIONS

The biomarkers LRG, fecal calprotectin, and fecal hemoglobin can serve as noninvasive and accurate tools for assessing activity in CD patients confirmed by BAE, especially when used in combination.

Systemic immune-inflammation index as a potential biomarker to monitor ulcerative colitis

OBJECTIVE

The treat-to-target strategy is recommended by Selecting Therapeutic Targets in Inflammatory Bowel Disease II (STRIDE-II) for treating ulcerative colitis (UC), and monitoring remission status is crucial during this management. The systemic immune-inflammation index (SII), defined as platelet * neutrophil/lymphocyte, is a complete blood count-based index reflecting the balance of immune and inflammatory status. This study aims to investigate the feasibility of SII for diagnosing UC and monitoring UC disease activity.

METHODS

This study retrospectively analyzed patients with UC and controls. Relationships between SII and Mayo clinical score, Mayo Endoscopic Score (MES), and Nancy Histological Index (NHI) were evaluated.

RESULTS

167 patients with UC and 106 controls were included. SII significantly increased in patients with UC and was closely correlated with the Mayo clinical score, MES, and NHI. SII diagnosed UC with a cut-off value of 619.1 × 109/L (area under the curve = 0.861, p < 0.0001, sensitivity 79.64%, specificity 77.36%), evaluated clinical remission status with a cut-off value of 1068 × 109/L (area under the curve = 0.691, p < 0.05, sensitivity 55.71%, specificity 81.48%), endoscopic improvement with a cut-off value of 981.3 × 109/L (area under the curve = 0.819, p < 0.0001, sensitivity 65.22%, specificity 89.66%), and histological healing with a cut-off value of 689.3 × 109/L (area under the curve = 0.898, p < 0.0001, sensitivity 88.89%, specificity 95.83%).

CONCLUSION

SII is a potential biomarker for diagnosing UC and monitoring UC disease severity, especially in evaluating mucosal and histological healing during the long-term management in treat-to-target strategy. However, further research is needed to confirm its usefulness and optimize its clinical application.

Usefulness of Serum Leucine-Rich Alpha-2 Glycoprotein as a Surrogate Marker of Small Bowel Mucosal Injury in Crohn's Disease

Introduction

Although the importance of mucosal healing has been suggested in Crohn's disease, it is difficult to repeat endoscopy, especially for the entire small bowel. Recently, serum leucine-rich alpha-2 glycoprotein (LRG) has been used as a surrogate marker of endoscopy. However, few studies have investigated a correlation between LRG and mucosal injury of the entire small bowel.

Methods

We retrospectively analyzed the clinical data of 30 patients with Crohn's disease from June 2020 to August 2022 at Yamaguchi Red Cross Hospital. All the patients were surveyed through the gastrointestinal tract by esophagogastroduodenoscopy, total colonoscopy, and capsule endoscopy (CE). Subjects with mucosal injury only in the small bowel were selected. Then, we assessed the relationship between serum biomarkers (LRG, C-reactive protein [CRP], hemoglobin, albumin) and small bowel mucosal injury scores (Lewis score [LS], Capsule Endoscopy Crohn's Disease Activity Index [CECDAI], and Crohn's Disease Activity in Capsule Endoscopy [CDACE]) calculated by CE.

Results

LRG and CRP were significantly correlated with small bowel mucosal injury scores (LS, CECDAI, CDACE) (p < 0.05, Spearman's rank correlation coefficient). The degree of correlation was greater for LRG than for CRP.

Conclusions

LRG is a useful surrogate marker that closely reflects small bowel mucosal injury in the entire small bowel.

Monitoring of leucine-rich alpha-2-glycoprotein and assessment by small bowel capsule endoscopy are prognostic for Crohn's disease patients

Background and Aim

Endoscopy is important to determine the effectiveness of treatment for Crohn's disease (CD), but searching the entire small intestine is difficult. Thus, we investigated the usefulness of leucine-rich alpha-2 glycoprotein (LRG), a new biomarker for predicting mucosal activity, in evaluating the activity of CD small intestinal lesions. This will further determine whether the results of small bowel capsule endoscopy (SBCE) affect the prognosis of patients with CD.

Methods

A total of 114 patients with CD who underwent SBCE were included. We analyzed the correlation between LRG and Capsule Endoscopy Crohn's Disease Activity Index (CECDAI). The cutoff value of LRG to achieve mucosal healing was calculated using the receiver operating characteristic curve. Then, we compared the presence or absence of intervention and the relapse rate of patients who could not achieve mucosal healing.

Results

The CECDAI correlated with LRG. The calculated LRG value for achieving mucosal healing was ≤11.9. Ninety-one patients were in clinical remission at the time of SBCE. During the follow-up period, 17 patients relapsed. As a result of SBCE, when no treatment intervention was performed in the case of CECDAI ≥3.5, the relapse rate was significantly higher than when CECDAI <3.5 or intervention was performed in the case of CECDAI ≥3.5.

Conclusions

The results reveal that LRG correlates with the activity of the entire small intestine and that SBCE assessment and therapeutic intervention can influence patient prognosis.

Leucine-Rich Alpha-2 Glycoprotein Is a Reliable Serum Biomarker for Evaluating Clinical and Endoscopic Disease Activity in Inflammatory Bowel Disease

BACKGROUND

Leucine-rich alpha-2 glycoprotein (LRG) is a novel serum biomarker for inflammation in inflammatory bowel disease (IBD). This prospective study aimed to compare the value of LRG with C-reactive protein (CRP) and fecal calprotectin for evaluating clinical and endoscopic disease activity in patients with IBD.

METHODS

At entry, clinical and endoscopic disease activity was assessed in 267 patients with IBD (ulcerative colitis [UC] 203; Crohn's disease [CD] 64), and the levels of LRG, CRP and fecal calprotectin were measured. The accuracy of the biomarkers for the detection of clinical and endoscopic disease activity was determined by the area under the receiver operating characteristic curve.

RESULTS

Leucine-rich alpha-2 glycoprotein showed a significant relationship with the clinical and endoscopic severity in both UC and CD (both diseases, P < .0001). In the clinical assessment of UC, the accuracy of LRG was significantly higher than that of CRP (0.73 vs 0.63; P < .001). In the endoscopic assessment of UC, the accuracy of LRG was significantly higher than that of CRP (P = .01), but it was significantly lower than that of fecal calprotectin (P = .009; LRG, 0.80; CRP, 0.72; fecal calprotectin, 0.91). In the clinical and endoscopic assessment of CD, the accuracy was not significantly different between the biomarkers (clinical activity: LRG, 0.71; CRP, 0.64; fecal calprotectin, 0.66; in endoscopic activity: LRG, 0.79; CRP, 0.78; fecal calprotectin, 0.81).

CONCLUSIONS

Leucine-rich alpha-2 glycoprotein is a reliable serum biomarker for the assessment of clinical and endoscopic disease activity in patients with IBD. It can be an alternative to CRP for the assessment of UC.

Combined serum albumin, fecal immunochemical test, and leucine-rich alpha-2 glycoprotein levels for predicting prognosis in remitting patients with ulcerative colitis

This study investigated the usefulness of serum leucine-rich alpha-2 glycoprotein (LRG) and fecal immunochemical tests (FIT) for predicting relapse in patients with ulcerative colitis (UC). Data of 194 patients tested for LRG between January 2020 and June 2022 were retrospectively collected and clinical characteristics were recorded. LRG was strongly correlated with CRP levels and it had a moderately negative correlation with albumin levels, whereas FIT was not significantly correlated with either CRP or albumin levels. Furthermore, the median serum albumin and FIT were significantly different between patients with or without clinical relapse; while the LRG level was not associated with clinical relapse. Although LRG is not an independent factor for predicting clinical relapse, the cumulative remission rate was significantly higher in patients with higher albumin than in those with lower albumin. Furthermore, the combination of FIT and albumin was useful for predicting for relapse, patients with higher FIT and lower albumin tended to have higher relapse rates than those with both lower FIT and albumin and those with lower FIT and higher albumin. Our study indicated that serum albumin level is useful for predicting relapse, even in remitting outpatients. Although LRG is not an independent factor for predicting clinical relapse, it is useful for identifying patients that are likely to relapse when combined serum albumin or FIT results.

Serum leucine-rich alpha-2 glycoprotein levels for predicting active ultrasonographic findings in intestinal lesions of patients with Crohn's disease in clinical remission

This study aimed to investigate the cutoff value of leucine-rich alpha-2 glycoprotein (LRG) in predicting active intestinal ultrasonography (IUS) findings in patients with Crohn's disease (CD) in clinical remission. Data were retrospectively collected from patients with CD evaluated using LRG and undergoing IUS from September 2020 to August 2022. Patients with a Harvey-Bradshaw Index of ≤4 were included and those who underwent intestinal resection were excluded. Bowel wall thickness and stratification and blood flow signal using superb microvascular imaging (SMI) were used to assess ultrasonography findings. SMI signals were categorized into 4 grades following the Limberg score. Receiver operating characteristic curves were constructed and the area under the curve was calculated to determine the LRG cutoff values for predicting active IUS findings and were compared with those of C-reactive protein. This study included 213 patients. The LRG cutoff values to predict active bowel wall thickness, loss of bowel wall stratification, and SMI of ≥1, ≥2, and 3 were 14.6 μg/mL, 14.6 μg/mL, 14.6 μg/mL, 14.6 μg/mL, and 16.9 μg/mL, respectively, with significantly higher areas under the curve in SMI of ≥1 and 3 than in C-reactive protein. The best LRG cutoff value for predicting active IUS findings was 14.6 μg/mL in patients with CD in clinical remission, suggesting that LRG is better than C-reactive protein for detecting active IUS findings in CD.

Amino acids-targeted metabolomics reveals novel diagnostic biomarkers for ulcerative colitis and Crohn's disease

Inflammatory bowel disease (IBD), which mainly comprises ulcerative colitis (UC) and Crohn's disease (CD), is a common chronic intestinal inflammatory disease that affects the ileum, rectum, and colon. Currently, the diagnosis of IBD is based on clinical history, physical examination and complementary diagnostic tests. It is challenging for physicians to make a definitive diagnosis. This study aimed to analyze the variation in amino acid metabolites in IBD serum and to identify potential predictive biomarkers of IBD diagnosis and progression. Serum samples were collected from 158 UC patients, 130 CD patients and 138 healthy controls (HCs). The 37 amino acids in serum were determined by ultra-high-pressure liquid chromatography coupled to a mass spectrometer. A panel of three-amino-acid metabolites (taurine, homocitrulline and kynurenine) was identified as a specific biomarker panel of IBD. Receiver operating characteristic analysis (ROC) showed that the panel had a sensitivity of 88.4% with a specificity of 84.6% for discriminating CD patients from UC patients. The biomarkers identified are increased in CD compared to UC. Our approach demonstrated a strong relationship between serum amino acid levels and IBD. We successfully identified serum amino acid biomarkers associated with CD and UC. The biomarker panel has potential in clinical practice for IBD diagnosis and will provide new insights into IBD pathogenesis.

Evaluation of Crohn's Disease Small-Bowel Mucosal Healing Using Capsule Endoscopy and Usefulness of Leucine-Rich α2-Glycoprotein

Recently, the importance of achieving clinical and deep remissions with mucosal healing (MH) has been demonstrated as a therapeutic goal to avoid Crohn's disease (CD) surgical operations. Although ileocolonoscopy (CS) is considered the gold standard, there are increasing reports on the benefits of capsule endoscopy (CE) and serum leucine-rich α2-glycoprotein (LRG) for evaluating small-bowel lesions in CD. We evaluated the data of 20 patients with CD who underwent CE in our department between July 2020 and June 2021 and whose serum LRG level was measured within 2 months. Concerning the mean LRG value, there was no significant difference between the CS-MH and CS-non-MH groups. Conversely, the mean LRG level was 10.0 μg/mL in seven patients in the CE-MH group and 15.2 μg/mL in 11 patients in the CE-non-MH group with a significant difference between the two groups (p = 0.0025). This study's findings show that CE can sufficiently determine total MH in most cases, and LRG is useful for evaluating CD small-bowel MH because of its correlation with CE-MH. Furthermore, satisfying CS-MH criteria and a cut-off value of 13.4 μg/mL for LRG suggests its usefulness as a CD small-bowel MH marker, which could be incorporated into the treat-to-target strategy.

Serum Leucine-Rich α2 Glycoprotein: A Novel Biomarker for Transmural Inflammation in Crohn's Disease

INTRODUCTION

Leucine-rich alpha-2 glycoprotein (LRG) is a newly studied biomarker for inflammatory diseases. This study aimed to investigate whether LRG can be used for evaluating transmural activity in patients with Crohn's disease (CD).

METHODS

We performed magnetic resonance enterography (MRE) in 227 consecutive CD patients from June 2020 to August 2021. We prospectively compared MRE findings with clinical and laboratory data including LRG. MRE was evaluated using 2 validated scoring systems, and transmural inflammation was defined as having a maximum simplified magnetic resonance index of activity (sMaRIA) score of ≥4 and a 5-point classification score of ≥9, respectively.

RESULTS

The correlation between LRG and the total MRE score showed a positive correlation ( r = 0.576 for sMaRIA score, P < 0.01 and r = 0.633 for 5-point score, P < 0.01). Serum concentrations of LRG significantly increased as MRE scores increased ( P < 0.01). The area under the curve of LRG for sMaRIA score of ≥4 and 5-point score of ≥9 was 0.845 and 0.869, respectively, which was significantly higher than that of CDAI ( P < 0.01) or C-reactive protein ( P < 0.01). LRG levels of ≥14 μg/mL had a 67% sensitivity and a 90% specificity for sMaRIA score of ≥4, and 73% sensitivity and 89% specificity for 5-point score of ≥9. Patients with high LRG levels were also strongly associated with CD-related hospitalization, surgery, and clinical relapse compared to those with low LRG levels ( P < 0.01 for all).

DISCUSSION

LRG is a highly accurate serum biomarker for detecting transmural activity in CD patients. Results need to be validated in further multicenter studies.

Transmural remission characterized by high biologic concentrations demonstrates better prognosis in Crohn's disease

BACKGROUND

The importance and pathophysiology of transmural healing in patients with Crohn's disease (CD) remains to be verified. We aimed to examine the association between serum concentrations of biologics and transmural remission evaluated via magnetic resonance enterography (MRE).

METHODS

We enrolled patients with CD who received maintenance biologics 1 year after induction and prospectively followed up for at least 1 year after baseline laboratory, endoscopic and MRE examination. We evaluated the relationship between baseline factors including the presence of transmural remission and patient prognosis, as well as between serum concentrations and transmural remission.

RESULTS

We included 134 patients. Of them, 65, 31, 27, and 11 patients received infliximab, adalimumab, ustekinumab, and vedolizumab, respectively. Those who achieved transmural remission showed a lower risk of hospitalization and surgery than those who did not achieve remission (P < 0.01). Adjusted hazard ratios of transmural remission for predicting hospitalization and surgery was 0.11 and 0.02, respectively, which was lower than that of clinical remission, biochemical remission, and endoscopic remission. Regarding serum concentrations, the median concentration was higher in patients with transmural remission than in patients with transmural activity for all agents (P < 0.01 for infliximab, P = 0.04 for adalimumab, P < 0.01 for ustekinumab, P = 0.08 for vedolizumab).

CONCLUSIONS

Transmural remission was the best predictor for prognosis in CD patients who received maintenance biologic therapy. High drug concentration levels were associated with transmural remission confirmed via MRE.

Systematic review of artificial intelligence-based image diagnosis for inflammatory bowel disease

OBJECTIVES

Diagnosis of inflammatory bowel diseases (IBD) involves combining clinical, laboratory, endoscopic, histologic, and radiographic data. Artificial intelligence (AI) is rapidly being developed in various fields of medicine, including IBD. Because a key part in the diagnosis of IBD involves evaluating imaging data, AI is expected to play an important role in this aspect in the coming decades. We conducted a systematic literature review to highlight the current advancement of AI in diagnosing IBD from imaging data.

METHODS

We performed an electronic PubMed search of the MEDLINE database for studies up to January 2022 involving IBD and AI. Studies using imaging data as input were included, and nonimaging data were excluded.

RESULTS

A total of 27 studies are reviewed, including 18 studies involving endoscopic images and nine studies involving other imaging data.

CONCLUSION

We highlight in this review the recent advancement of AI in diagnosing IBD from imaging data by summarizing the relevant studies, and discuss the future role of AI in clinical practice.

Serum Leucine-Rich α2 Glycoprotein: A Biomarker for Predicting the Presence of Ulcerative Colitis but Not Ulcerative Proctitis

The serum level of leucine-rich α2 glycoprotein (LRG) is a biomarker for active ulcerative colitis (UC). We examined the serum level of LRG as a biomarker for predicting the presence of UC. Patients with persistent diarrhea and/or bloody stool with no history of UC were consecutively enrolled at their initial visit. Serum LRG measurement and colonoscopy with histology were performed on the same day. We enrolled 103 patients (69 men; median age, 45 years) with suspected UC; 66 patients were diagnosed with active UC (proctitis, n = 10; left-sided colitis, n = 26; and pancolitis, n = 30) based on endoscopic and histological criteria. Although the median LRG value in patients with proctitis was similar to that of patients with normal colonoscopic findings (8.5 vs. 8.6 mg/mL, p = 0.24), the median LRG values were significantly elevated in patients with left-sided colitis and pancolitis compared with those of patients with normal colonoscopy (13.6 or 18.0 vs. 8.6 mg/mL, p < 0.0001). The LRG cut-off value of 10.8 μg/mL was derived from the ROC curve, showing 96% sensitivity and 97% specificity for active UC but not active proctitis. Using a cut-off value of 10.8 mg/mL serum, LRG could be a novel biomarker for predicting patients with active UC except for proctitis.

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.

Serum Leucine-Rich Alpha-2 Glycoprotein in Quiescent Crohn's Disease as a Potential Surrogate Marker for Small-Bowel Ulceration detected by Capsule Endoscopy

Background: Small bowel (SB) lesions in quiescent Crohn’s disease (CD) are sometimes not identified by clinical activity or existing markers. We investigated the usefulness of a novel biomarker, leucine-rich α2-glycoprotein (LRG), for screening for the presence of SB ulcerative lesions detected by small-bowel capsule endoscopy (SBCE). Methods: We examined patients with a Crohn’s Disease Activity Index (CDAI) value < 150 and a C-reactive protein (CRP) value < 0.5 mg/dL with SB or SB colonic CD. The presence of small-bowel ulcerative lesions (≥0.5 cm) was grouped by SBCE results, and we then compared the groups’ LRG value to establish a cutoff value for screening for the presence of lesions. Results: In 40 patients with CD, the LRG values differed significantly between the patients with and without SB ulcerative lesions (Ul + 14.1 (2.1−16.5) μg/mL vs. Ul − 12.3 (9.3−13.5) μg/mL; p = 0.0105). The respective cutoff LRG values for the presence of SB ulcerative lesions was 14 μg/mL (areas under the ROC curve 0.77), with sensitivity 63.6%, specificity 82.8%, positive predictive values 58.3%, negative predictive values 85.7%, and accuracy 78%. Conclusion: These results indicate that LRG may be useful in predicting the presence of SB inflammation associated in patients with CD with CRP < 0.5 mg/dL and CDAI < 150, and in selecting patients for SBCE.