Surrogate markers of mucosal healing in inflammatory bowel disease: A systematic review

Fecal calprotectin and endoscopic scores: The cornerstones in clinical practice for evaluating mucosal healing in inflammatory bowel disease

Managing inflammatory bowel disease (IBD) is becoming increasingly complex and personalized, considering the advent of new advanced therapies with distinct mechanisms of action. Achieving mucosal healing (MH) is a pivotal therapeutic goal in IBD management and can prevent IBD progression and reduce flares, hospitalization, surgery, intestinal damage, and colorectal cancer. Employing proactive disease and therapy assessment is essential to achieve better control of intestinal inflammation, even if subclinical, to alter the natural course of IBD. Periodic monitoring of fecal calprotectin (FC) levels and interval endoscopic evaluations are cornerstones for evaluating response/remission to advanced therapies targeting IBD, assessing MH, and detecting subclinical recurrence. Here, we comment on the article by Ishida et al Moreover, this editorial aimed to review the role of FC and endoscopic scores in predicting MH in patients with IBD. Furthermore, we intend to present some evidence on the role of these markers in future targets, such as histological and transmural healing. Additional prospective multicenter studies with a stricter MH criterion, standardized endoscopic and histopathological analyses, and virtual chromoscopy, potentially including artificial intelligence and other biomarkers, are desired.

Challenges in IBD Research 2024: Pragmatic Clinical Research

Pragmatic clinical research is 1 of the 5 focus areas of the Challenges in IBD Research 2024, a multidisciplinary effort by scientists, clinicians, patients, and funders to identify priorities for patient-centric research. This summary provides a comprehensive overview of current gaps in inflammatory bowel disease (IBD) clinical research and actionable approaches to address them. This review is focused on identifying research that is needed to achieve the best outcomes for patients in clinical practice. Research gaps include understanding the needs of understudied patient groups and addressing barriers to care so all patients receive optimal care, validating and using biomarkers to enable early diagnosis and result in better outcomes for adults and children with IBD, and determining the optimal sequencing of treatments (medical, surgical, adjunct) in children and adults. Inclusive pragmatic research is needed to address these gaps and lead to improvements in patient care and outcomes for all populations of patients with IBD.

MicroRNAs in inflammatory bowel disease: What do we know and what can we expect?

MicroRNAs (miRNAs), small non-coding RNAs composed of 18-24 nucleotides, are potent regulators of gene expression, contributing to the regulation of more than 30% of protein-coding genes. Considering that miRNAs are regulators of inflammatory pathways and the differentiation of intestinal epithelial cells, there is an interest in exploring their importance in inflammatory bowel disease (IBD). IBD is a chronic and multifactorial disease of the gastrointestinal tract; the main forms are Crohn's disease and ulcerative colitis. Several studies have investigated the dysregulated expression of miRNAs in IBD, demonstrating their important roles as regulators and potential biomarkers of this disease. This editorial presents what is known and what is expected regarding miRNAs in IBD. Although the important regulatory roles of miRNAs in IBD are clearly established, biomarkers for IBD that can be applied in clinical practice are lacking, emphasizing the importance of further studies. Discoveries regarding the influence of miRNAs on the inflammatory process and the exploration of their role in gene regulation are expected to provide a basis for the use of miRNAs not only as potent biomarkers in IBD but also as therapeutic targets for the control of inflammatory processes in personalized medicine.

Clinical utility of C-reactive protein-to-albumin ratio in the management of patients with inflammatory bowel disease

Background and Aim

C-reactive protein (CRP)-to-albumin ratio (CAR) is a novel score with prognostic value in inflammatory conditions. This study assessed the performance of CAR as an objective marker of disease activity and prediction of subtherapeutic infliximab trough levels in patients with inflammatory bowel disease (IBD).

Methods

A retrospective study was conducted on three different patient cohorts with IBD: patients who had (i) fecal calprotectin (FC) measurements; (ii) Mayo Endoscopic Scores; and (iii) infliximab trough levels available. The relative performances of CAR, albumin, and CRP were compared in predicting disease activity (based on FC or Mayo Endoscopic Score) and infliximab trough levels.

Results

In both the FC (n = 289) and endoscopy (n = 65) cohorts, albumin and CAR correlated with objective disease activity. CAR (area under the curve [AUC] 0.70) was only marginally better at detecting active disease, measured by FC, compared to CRP (AUC 0.68). A CAR >0.15 was able to detect Mayo 3 disease (AUC 0.83, sensitivity 81%, specificity 89%). Albumin (r = 0.38) and CAR (r = -0.42) correlated with infliximab trough levels (n = 204). The optimal CAR for detecting subtherapeutic infliximab trough levels was >0.08 (AUC 0.70, sensitivity 66%, specificity 64%). Both albumin and CAR were independent predictors of subtherapeutic infliximab trough levels but correlated poorly with infliximab trough levels longitudinally in the same patient.

Conclusion

CAR was only a modest discriminator of subtherapeutic infliximab levels and offers little more than CRP in detecting active disease. CAR has potential to detect severe Mayo 3 disease and could be calculated in patients admitted with suspected acute severe ulcerative colitis.

Matrix gla protein, a potential marker of tissue remodelling and physiological ageing of the gut in crohn's disease

BACKGROUND

The inactive dephosphorylated and uncarboxylated form of the matrix Gla protein (dp-ucMGP) has been shown to be increased in plasma of inflammatory bowel disease (IBD) patients. Our aim was to assess if the plasmatic level of dp-ucMGP could reflect disease endoscopic activity, presence of strictures and cumulative structural bowel damage in Crohn's disease (CD) patients.

METHODS

The plasmatic level of dp-ucMGP was measured in a monocentric cohort of prospectively recruited patients. The analysis was done by chemiluminescent immunoassay on blood samples collected the day of a planned ileocolonoscopy. In addition to classical clinical data (gender, age, body mass index (BMI), disease duration, current treatment), endoscopic data (disease location, Crohn's Disease Endoscopic Index of Severity (CDEIS), mucosal healing (MH), presence of 9 CD lesion types) and biological markers (faecal calprotectin and C-reactive protein (CRP)) were collected. The association between dp-ucMGP level and Lémann index was also investigated. Univariate linear regression was used to investigate the relationship between dp-ucMGP level and different parameters collected.

RESULTS

A total of 82 ileocolonoscopies and dp-ucMGP assays were performed in 75 CD patients (45 females; 37 ileocolonic, 19 ileal and 19 colonic diseases) between October 2012 and November 2019. A total of 24 patients (29.3%) showed MH. The dp-ucMGP levels were not associated with MH, CDEIS, faecal calprotectin or CRP levels. Plasmatic dp-ucMGP levels increased significantly with age (p = 0.0032), disease duration (p = 0.0033), corticosteroids use (p = 0.019) and tended to increase in patients with intestinal strictures (p = 0.086) but not with the Lémann index.

CONCLUSION

The significant increase of plasmatic dp-ucMGP levels with age, disease duration and the trend observed in patients with non-ulcerated strictures may suggest that this extracellular matrix protein could be a marker of tissue remodelling and physiological ageing of the gut.

Validation of rapid fecal calprotectin assay using particle enhanced turbidimetric immunoassay for inflammatory bowel disease

Fecal calprotectin (FC) is a promising biomarker for diagnosis and treatment of inflammatory bowel disease, ulcerative colitis (UC), and Crohn's disease. An enzyme immunoassay (EIA) is widely used for FC detection, though the considerable lag time, up to several days, causes clinical management delay. This study was performed to examine the new rapid kit fCAL-turbo, which is based on a particle-enhanced turbidimetric immunoassay (15 min), by comparing FC values with other EIAs (EliA, PhiCal, Bühlmann) and endoscopic scores. Using 94 samples, fCAL-turbo showed strong significant positive correlations with the other kits (Spearman's r = 0.9178-0.9886). Of 74 UC patients, 69 underwent an endoscopy and fCAL-turbo reflected endoscopic activity with a moderate correlation with Mayo endoscopic subscore (MES) (r = 0.6945, others r = 0.6682-0.7013). Receiver operating characteristic analyses based on MES 0 versus 1-3 showed a similar efficacy as compared to the other kits (cut-off and area under the curve: 89.70 µg/g and 0.8592, respectively, others 62.35-138.4 µg/g and 0.8280-0.8611, respectively). Furthermore, multiple regression analysis confirmed that fCAL-turbo results significantly contributed to prediction of MES 0 with a higher t-value as compared to the other biomarkers. fCAL-turbo showed strong correlations with the other kits and also demonstrated excellent performance for predicting endoscopic remission of UC.

Ischemia-modified albumin: a novel blood marker of endoscopic mucosal healing in inflammatory bowel disease

BACKGROUND/AIMS

The achievement of endoscopic remission is an important therapeutic goal in the treatment of inflammatory bowel diseases (IBD). We aimed to evaluate the role of fecal calprotectin (FCP) and ischemia-modified albumin (IMA) as biomarkers for evaluating IBD disease activity.

METHODS

A total of 48 patients with IBD (20 with ulcerative colitis and 28 with Crohn's disease) were included in this study. FCP and serum C-reactive protein levels, erythrocyte sedimentation rate, and IMA were measured in patients with IBD and compared with endoscopic findings.

RESULTS

Elevated FCP and serum IMA levels were significantly associated with endoscopic non-mucosal healing. The correlation between FCP and IMA was not significant. Analysis of the receiver operating characteristic curve showed that both FCP and IMA had diagnostic value in predicting non-mucosal healing. When the Ln(FCP)+IMA/10 value was calculated using both factors, the predictive value for non-mucosal healing increased; however, no significant difference was observed.

CONCLUSIONS

IMA could be a candidate serum biomarker for predicting endoscopic mucosal healing in IBD.

Emerging strategy towards mucosal healing in inflammatory bowel disease: what the future holds?

For decades, the therapeutic goal of conventional treatment among inflammatory bowel disease (IBD) patients is alleviating exacerbations in acute phase, maintaining remission, reducing recurrence, preventing complications, and increasing quality of life. However, the persistent mucosal/submucosal inflammation tends to cause irreversible changes in the intestinal structure, which can barely be redressed by conventional treatment. In the late 1990s, monoclonal biologics, mainly anti-TNF (tumor necrosis factor) drugs, were proven significantly helpful in inhibiting mucosal inflammation and improving prognosis in clinical trials. Meanwhile, mucosal healing (MH), as a key endoscopic and histological measurement closely associated with the severity of symptoms, has been proposed as primary outcome measures. With deeper comprehension of the mucosal microenvironment, stem cell niche, and underlying mucosal repair mechanisms, diverse potential strategies apart from monoclonal antibodies have been arising or undergoing clinical trials. Herein, we elucidate key steps or targets during the course of MH and review some promising treatment strategies capable of promoting MH in IBD.

Different levels of healing in inflammatory bowel diseases: mucosal, histological, transmural, barrier and complete healing

Mucosal healing on endoscopy has emerged as a key prognostic parameter in the management of patients with IBD (Crohn's disease, ulcerative colitis/UC) and can predict sustained clinical remission and resection-free survival. The structural basis for this type of mucosal healing is a progressive resolution of intestinal inflammation with associated healing of ulcers and improved epithelial barrier function. However, in some cases with mucosal healing on endoscopy, evidence of histological activity in mucosal biopsies has been observed. Subsequently, in UC, a second, deeper type of mucosal healing, denoted histological healing, was defined which requires the absence of active inflammation in mucosal biopsies. Both levels of mucosal healing should be considered as initial events in the resolution of gut inflammation in IBD rather than as indicators of complete transmural healing. In this review, the effects of anti-inflammatory, biological or immunosuppressive agents as well as small molecules on mucosal healing in clinical studies are highlighted. In addition, we focus on the implications of mucosal healing for clinical management of patients with IBD. Moreover, emerging techniques for the analysis of mucosal healing as well as potentially deeper levels of mucosal healing such as transmural healing and functional barrier healing of the mucosa are discussed. Although none of these new levels of healing indicate a definitive cure of the diseases, they make an important contribution to the assessment of patients' prognosis. The ultimate level of healing in IBD would be a resolution of all aspects of intestinal and extraintestinal inflammation (complete healing).

Real-World Endoscopic and Histologic Outcomes in Ulcerative Colitis Patients: A Retrospective Cohort Study

BACKGROUND

Histologic activity has emerged as an aspirational therapeutic goal in ulcerative colitis management. It is not yet a formal treatment target in ulcerative colitis. However, it could be used as an adjunct to mucosal healing to represent a deeper level of healing. We investigated mucosal and histologic remission rates and potential predictors of these outcomes in a cohort of UC patients.

METHODS

We conducted a retrospective analysis of data collected from UC patients enrolled in an ongoing prospective cohort study. Mucosal healing was defined as Mayo endoscopic score = 0.

RESULTS

A total of 131 patients with ulcerative colitis were enrolled in our study and were prospectively followed for a median length of 2 years (range 0-5 years), totaling 266 study visits. Mucosal healing was recorded for 27 patients at 70 (26%) different study visits. For patients with mucosal healing, histologic remission was achieved in 18/27 (66%) patients. On univariate analysis, sustained clinical remission, SIBDQ scores ≥ 5.5, CRP ≤ 5 mg/dL and absence of corticotherapy were associated with mucosal healing and SIBDQ scores ≥ 5.5 and CRP ≤ 5 mg/dL with histologic healing, respectively. After logistic regression analysis, none of the investigated factors were associated with mucosal and histologic healing. The number of CD8+ intraepithelial lymphocytes (IELs) was significantly greater than the number of CD4+ IELs in periods of disease activity, as well as during mucosal healing (p < 0.01 in both cases).

CONCLUSIONS

Mucosal healing and histologic remission rates are low in real-life settings. The results of univariate analysis indicate that a good quality of life (SIBDQ score) and normal inflammatory markers (CRP) are associated with mucosal and histologic healing. However, frequently used patient- and disease-related factors, including mucosal healing, are not reliable predictors for histologic remission. Greater CD8+ lymphocyte involvement and higher CD8+/CD4+ distribution can have a meaningful impact on understanding the pathogenesis and natural history of ulcerative colitis, as well as future treatment options for lymphocyte-targeting medications.

Positioning and Usefulness of Biomarkers in Inflammatory Bowel Disease

BACKGROUND

Mucosal healing (MH) was proposed to be an ideal treatment goal for patients with inflammatory bowel disease (IBD). Instead of endoscopy to confirm MH, biomarkers are frequently used and have become an indispensable modality for the clinical examination of patients with IBD.

SUMMARY

Common biomarkers of IBD include C-reactive protein (CRP), erythrocyte sedimentation rate, antineutrophil cytoplasmic antibodies, anti-Saccharomyces cerevisiae antibodies, leucine-rich α2 glycoprotein, fecal calprotectin (FCP), and the fecal immunochemical test. Biomarkers play five major roles in the management of IBD: (1) diagnosing and distinguishing between IBD and non-IBD or ulcerative colitis and Crohn's disease; (2) predicting treatment response, especially before administrating biologics; (3) monitoring and grasping endoscopic or histological disease activity; (4) replacing endoscopy for diagnosing MH, including endoscopic and histological remission; and (5) predicting recurrence before disease activity appears through symptoms. Many reports have demonstrated the usefulness of CRP and FCP for those five roles; however, they have limitations for diagnosing MH or predicting treatment response. In general, FCP has better ability in those positions than CRP; additionally, leucine-rich α2 glycoprotein can diagnose endoscopic disease activity better than CRP. The novel biomarker, prostaglandin E-major urinary metabolite, and anti-αvβ6 antibody are expected to be noninvasive and reliable biomarkers; however, more evidence is required for future studies. Oncostatin M and microRNA are also prospects, in addition to other familiar and novel biomarkers.

KEY MESSAGES

Each biomarker has a useful feature; therefore, we should consider their features and use appropriate biomarkers for the five roles to enable noninvasive and smooth management of IBD.

Colonocyte keratin 7 is expressed de novo in inflammatory bowel diseases and associated with pathological changes and drug-resistance

The clinical course of IBD, characterized by relapses and remissions, is difficult to predict. Initial diagnosis can be challenging, and novel disease markers are needed. Keratin 7 (K7) is a cytoskeletal intermediate filament protein not expressed in the colonic epithelium but has been reported in IBD-associated colorectal tumors. Our aim was to analyze whether K7 is expressed in chronic colonic inflammatory diseases and evaluate its potential as a novel biomarker. K7 was analyzed in two patient cohorts using immunohistochemistry-stained colon samples and single-cell quantitative digital pathology methods. K7 was correlated to pathological changes and clinical patient characteristics. Our data shows that K7 is expressed de novo in the colonic epithelium of ulcerative colitis and Crohn's disease IBD patients, but not in collagenous or lymphocytic colitis. K7 mRNA expression was significantly increased in colons of IBD patients compared to controls when assessed in publicly available datasets. While K7 increased in areas with inflammatory activity, it was not expressed in specific crypt compartments and did not correlate with neutrophils or stool calprotectin. K7 was increased in areas proximal to pathological alterations and was most pronounced in drug-resistant ulcerative colitis. In conclusion, colonic epithelial K7 is neo-expressed selectively in IBD patients and could be investigated for its potential as a disease biomarker.

Ustekinumab trough levels predicting laboratory and endoscopic remission in patients with Crohn's disease

BACKGROUNDS

Optimal concentration of ustekinumab (UST) predicting endoscopic remission has not been fully investigated in Crohn's disease (CD). We aimed to identify the optimal UST trough levels predicting clinical, laboratory and endoscopic remission in CD patients.

METHODS

Twenty-eight patients with CD were enrolled and investigated (27 patients by enteroscopy and 1 by colonoscopy). The endoscopic activity was assessed using the scoring system that applied the Rutgeerts score to observed intestine. Serum UST trough levels and anti-UST antibodies (AUAs) levels were determined by in-house immunoassays.

RESULTS

Endoscopic activity was negatively correlated with serum UST trough levels (Spearman's rank correlation coefficient (ρ) = - 0.66, P = 0.0001) and serum albumin levels (ρ = - 0.60, P = 0.0007). The endoscopic activity was positively and significantly correlated with CRP (ρ = 0.59, P = 0.0009) and ESR (ρ = 0.44, P = 0.033). There was no significant association between the endoscopic score and AUA levels and/or Crohn's disease activity index (CDAI). Serum UST trough levels and albumin levels were significantly higher in the endoscopic remission group (scores of 0 and 1) than in the non-endoscopic remission group (UST trough, mean 3.3 vs. 1.8 μg/mL). No significant difference was observed in AUAs between the endoscopic remission and non-remission groups. Receiver operation curve (ROC) analysis revealed that the optimal cutoff value of UST trough levels predicting normal CRP and serum albumin levels was 1.7 μg/mL for each, and the optimal cutoff value predicting endoscopic remission was 2.0 μg/mL (AUC: 0.80, 95% CI 0.64-0.96).

CONCLUSION

Achievement of endoscopic remission requires higher UST trough levels than required for normalization of CRP and serum albumin levels.

Changes in Salivary Parameters of Oral Immunity after Biologic Therapy for Inflammatory Bowel Disease

We previously observed that inflammatory bowel disease (IBD) may compromise oral host defense, as assessed by decreased salivary levels of immunoglobulin A (IgA) and myeloperoxidase (MPO). Biologic therapy with inhibitors of cytokines or adhesion molecules is increasingly used for patients with IBD. Little is known, however, about how this treatment modality affects the release and properties of saliva. Here, we aimed to determine how biologic therapy in patients who had not responded to previous standard treatment with conventional drugs affected the salivary concentration of IgA and MPO. To this end, unstimulated whole mixed saliva was collected before treatment or after 10-12 weeks of therapy from 27 patients with Crohn's disease (CD) and 24 patients with ulcerative colitis (UC). After the induction phase of therapy with biologics, salivary levels of IgA and MPO increased significantly in UC, but not in CD patients. These increases were approximately 8-fold and 6-fold, for IgA and MPO, respectively. Moreover, these effects occurred in UC patients who responded successfully to therapy, but not in those who failed to improve. Furthermore, the relative increases in salivary IgA and MPO correlated with the relative decrease in UC severity, as assessed by the Mayo scale. These data indicate that the successful therapy with biologics in UC patients results also in improved oral host defense. However, it remains to be determined why such an effect does not occur during therapy for CD.

Role of Biomarkers in the Diagnosis and Treatment of Inflammatory Bowel Disease

The number of patients with inflammatory bowel disease (IBD) is increasing worldwide. Endoscopy is the gold standard to assess the condition of IBD. The problem with this procedure is that the burden and cost on the patient are high. Therefore, the identification of a reliable biomarker to replace endoscopy is desired. Biomarkers are used in various situations such as diagnosis of IBD, evaluation of disease activity, prediction of therapeutic effect, and prediction of relapse. C-reactive protein and fecal calprotectin have a lot of evidence as objective biomarkers of disease activity in IBD. The usefulness of the fecal immunochemical test, serum leucine-rich glycoprotein, and urinary prostaglandin E major metabolite have also been reported. Herein, we comprehensively review the usefulness and limitations of biomarkers that can be used in daily clinical practice regarding IBD. To date, no biomarker is sufficiently accurate to replace endoscopy; however, it is important to understand the characteristics of each biomarker and use the appropriate biomarker at the right time in daily clinical practice.

Circulating Fibroblast Activation Protein as Potential Biomarker in Patients With Inflammatory Bowel Disease

A major concern in the management of Inflammatory Bowel Disease (IBD) is the absence of accurate and specific biomarkers to drive diagnosis and monitor disease status timely and non-invasively. Fibroblast activation protein (FAP) represents a hallmark of IBD bowel strictures, being overexpressed in stenotic intestinal myofibroblasts. The present study aimed at evaluating the potential of circulating FAP (cFAP) as an accessible blood biomarker of IBD. Quantitative determination of cFAP was performed by enzyme-linked immunosorbent assay on plasma samples prospectively collected from patients with IBD and control subjects. A discrimination model was established on a training set of 50% patients and validated on independent samples. Results showed that cFAP concentration was reduced in patients with IBD when compared to controls (p < 0.0001). Age, sex, smoking, disease location and behavior, disease duration and therapy were not associated with cFAP. The sensitivity and specificity of cFAP in discriminating IBD from controls were 70 and 84%, respectively, based on the optimal cutoff (57.6 ng mL⁻¹, AUC = 0.78). Predictions on the test set had 57% sensitivity, 65% specificity, and 61% accuracy. There was no strong correlation between cFAP and routine inflammatory markers in the patients' population. A subgroup analysis was performed on patients with Crohn's disease undergoing surgery and revealed that cFAP correlates with endoscopic mucosal healing. In conclusion, cFAP deserves attention as a promising blood biomarker to triage patients with suspected IBD. Moreover, it might function as a biomarker of post-operative remission in patients with Crohn's disease.