Granulomonocytapheresis as a cell-dependent treatment option for patients with inflammatory bowel disease: Concepts and clinical features for better therapeutic outcomes

Therapeutic Granulomonocytapheresis as a Non-pharmacologic Treatment Option for Inflammatory Bowel Disease: Efficacy Reports on a Wide Age Range and Disease Profile

The major phenotypes of inflammatory bowel disease (IBD) include ulcerative colitis (UC) and Crohn's disease (CD), which cause debilitating symptoms, including bloody diarrhea, abdominal discomfort, and fever. Patients require life-long immunosuppressive medications, which cause adverse side effects as additional morbidity factors. However, IBD is initiated and perpetuated by inflammatory cytokines, and given that in patients with IBD myeloid lineage leukocytes are elevated with activation behavior and release inflammatory cytokines, selective depletion of elevated granulocytes and monocytes by granulomonocytapheresis is a relevant therapeutic option for IBD patients. Therefore, a column filled with specially designed beads as granulomonocytapheresis carriers for selective adsorption of myeloid lineage leukocytes (Adacolumn) has been applied to treat patients with active IBD. Patients receive up to 10 granulomonocytapheresis sessions at one or two sessions per week. During each session, the carriers adsorb up to 60% of the myeloid leukocytes from the blood that passes through the granulomonocytapheresis column. Efficacy rates in the UC setting have been as high as 85% in steroid-naïve patients, and 100% in drug-naïve, first-episode cases, but patients with a long duration of active IBD and extensive colonic lesions that have become refractory to pharmacological treatment have not responded well. However, granulomonocytapheresis has a favorable safety profile. Given that immunosuppressive medications used to treat IBD potentially may increase the risk of severe viral infection, non-drug granulomonocytapheresis should be a favorable treatment strategy. Further, by targeting granulomonocytapheresis to patients with background features and identifying a patient as a likely responder, futile use of medical resources is avoided.

Concomitant pharmacologic medications influence the clinical outcomes of granulocyte and monocyte adsorptive apheresis in patients with ulcerative colitis: A multicenter retrospective cohort study

BACKGROUND

Granulocyte and monocyte adsorptive apheresis (GMA) with Adacolumn has been used as a remission induction therapy for patients with active ulcerative colitis (UC). Herein, we investigated the influence of concomitant medications in the remission induction of GMA in patients with active UC.

METHODS

This multicenter retrospective cohort study included patients with UC underwent GMA in five independent institutions in Japan from January 2011 to July 2021. Factors including concomitant medications associated with clinical remission (CR) were analyzed statistically.

RESULT

A total of 133 patients were included. Seventy-four patients achieved a CR after GMA. The multivariable analysis revealed that concomitant medication with 5-aminosalicylic acid, Mayo endoscopic subscore (MES), and concomitant medication with immunosuppressors (IMs) remained as predictors of CR after GMA. In the subgroup analysis in patients with MES of 2, concomitant medication with IMs was demonstrated as a significant negative factor of CR after GMA (P = .042, OR 0.354). Seventy-four patients who achieved CR after GMA were followed up for 52 weeks. In the multivariable analysis, the maintenance therapy with IMs was demonstrated as a significant positive factor of sustained CR up to 52 weeks (P = .038, OR 2.214). Furthermore, the rate of sustained CR in patients with biologics and IMs was significantly higher than that in patients with biologics only (P = .002).

CONCLUSION

GMA was more effective for patients with active UC that relapsed under treatment without IMs. Furthermore, the addition of IMs should be considered in patients on maintenance therapy with biologics after GMA.

A high-throughput microfluidic device based on controlled incremental filtration to enable centrifugation-free, low extracorporeal volume leukapheresis

Leukapheresis, the extracorporeal separation of white blood cells (WBCs) from red blood cells (RBCs) and platelets (PLTs), is a life-saving procedure used for treating patients with cancer and other conditions, and as the initial step in the manufacturing of cellular and gene-based therapies. Well-tolerated by adults, leukapheresis poses a significant risk to neonates and low-weight infants because the extracorporeal volume (ECV) of standard centrifugation-based machines represents a particularly large fraction of these patients' total blood volume. Here we describe a novel high-throughput microfluidic device (with a void volume of 0.4 mL) based on controlled incremental filtration (CIF) technology that could replace centrifugation for performing leukapheresis. The CIF device was tested extensively using whole blood from healthy volunteers at multiple hematocrits (5-30%) and flow rates (10-30 mL/min). In the flow-through regime, the CIF device separated WBCs with > 85% efficiency and 10-15% loss of RBCs and PLTs while processing whole blood diluted with saline to 10% hematocrit at a flow rate of 10 mL/min. In the recirculation regime, the CIF device demonstrated a similar level of separation performance, virtually depleting WBCs in the recirculating blood (~ 98% reduction) by the end of a 3.5-hour simulated leukapheresis procedure. Importantly, the device operated without clogging or decline in separation performance, with minimal activation of WBCs and PLTs and no measurable damage to RBCs. Compared to the typical parameters of centrifugation-based leukapheresis, the CIF device had a void volume at least 100-fold smaller, removed WBCs about twice as fast, and lost ~ 2-3-fold fewer PLTs, while operating at a flow rate compatible with the current practice. The hematocrit and flow rate at which the CIF device operated were significantly higher than previously published for other microfluidic cell separation methods. Finally, this study is the first to demonstrate a highly efficient separation of cells from recirculating blood using a microfluidic device. Overall, these findings suggest the feasibility of using high-throughput microfluidic cell separation technology to ultimately enable centrifugation-free, low-ECV leukapheresis. Such a capability would be particularly useful in young children, a vulnerable group of patients who are currently underserved.

Targeting neutrophils in inflammatory bowel disease: revisiting the role of adsorptive granulocyte and monocyte apheresis

INTRODUCTION

Inflammatory bowel disease (IBD) is a chronic immune-mediated disease of the gastrointestinal tract comprising Crohn's disease (CD) and ulcerative colitis (UC). While any part of the digestive tract can be affected in CD, mucosal inflammation in UC is limited to the colon. Differences and similarities between the two conditions are reflected by their pathophysiology.

AREAS COVERED

An overview of immunological aspects, pharmacological management, and biomarkers of IBD is provided. The role of adsorptive granulocyte and monocyte apheresis (GMA) is reviewed including its primary and secondary effects on the immune system, as well as clinical studies in IBD (mainly UC), and potential biomarkers for adsorptive GMA.

EXPERT OPINION

In UC, adsorptive GMA with Adacolumn (Adacolumn®, JIMRO Co., Ltd. Takasaki, Gunma, Japan) selectively depletes elevated myeloid lineage leukocytes and has a range of beneficial secondary immune effects. Adsorptive GMA is a safe and effective non-pharmacological treatment option for UC. Pilot studies have reported promising results for adsorptive GMA in combination with biological agents, although larger studies are required. Fecal calprotectin concentrations, neutrophil counts in histological samples and/or the neutrophil/lymphocyte ratio in peripheral blood may prove to be useful biomarkers for predicting GMA effectiveness in the future.

Fecal calprotectin is a useful biomarker for predicting the clinical outcome of granulocyte and monocyte adsorptive apheresis in ulcerative colitis patients: a prospective observation study

Background

Granulocyte and monocyte adsorptive apheresis (GMA) is widely used as a remission induction therapy for active ulcerative colitis (UC) patients. However, there are no available biomarkers for predicting the clinical outcome of GMA. We investigated the utility of Fecal calprotectin (FC) as a biomarker for predicting the clinical outcome during GMA therapy in active UC patients.

Methods

In this multicenter prospective observation study, all patients received 10 sessions of GMA, twice a week, for 5 consecutive weeks. FC was measured at entry, one week, two weeks, and at the end of GMA. Colonoscopy was performed at entry and after GMA. The clinical activity was assessed based on the partial Mayo score when FC was measured. Clinical remission (CR) was defined as a partial Mayo score of ≤ 2 and endoscopic remission (ER) was defined as Mayo endoscopic subscore of either 0 or 1. We analyzed the relationships between the clinical outcome (CR and ER) and the change in FC concentration.

Result

Twenty-six patients were included in this study. The overall CR and ER rates were 50.0% and 19.2%, respectively. After GMA, the median FC concentration in patients with ER was significantly lower than that in patients without ER (469 mg/kg vs. 3107 mg/kg, p = 0.03). When the cut-off value of FC concentration was set at 1150 mg/kg for assessing ER after GMA, the sensitivity and specificity were 0.8 and 0.81, respectively. The FC concentration had significantly decreased by one week. An ROC analysis demonstrated that the reduction rate of FC (ΔFC) at 1 week was the most accurate predictor of CR at the end of GMA (AUC = 0.852, P = 0.002). When the cut-off value of ΔFC was set at ≤ 40% at 1 week for predicting CR at the end of GMA, the sensitivity and specificity were 76.9% and 84.6%, respectively.

Conclusion

We evaluated the utility of FC as a biomarker for assessing ER after GMA and predicting CR in the early phase during GMA in patients with active UC. Our findings will benefit patients with active UC by allowing them to avoid unnecessary invasive procedures and will help establish new strategies for GMA.

Leukocytapheresis in patients with inflammatory bowel diseases

Leukocytapheresis, a blood purification therapy, exerts anti-inflammatory effects by removing activated leukocytes from the peripheral blood through extracorporeal circulation. It is a potential option of treatment for patients with inflammatory bowel diseases (IBD), especially those with ulcerative colitis (UC), who do not respond to conventional therapy. Given that it has a favourable safety profile and seems to have steroid sparing effects, its position in the treatment of UC is likely to expand. However, there is inadequate evidence to draw any conclusions about the efficacy of leukocytapheresis in patients with Crohn's disease, and it should only be used in accordance with special arrangements for consent. Considering the current level of knowledge, it is essential to conduct large, well-designed, randomized clinical trials to evaluate the effects of leukocytapheresis in the management of IBD patients.

Use of granulocyte/monocytapheresis in ulcerative colitis: A practical review from a European perspective

Half of the patients with ulcerative colitis require at least one course of systemic corticosteroids in their lifetime. Approximately 75% of these patients will also require immunosuppressive drugs (i.e., thiopurines or biological agents) in the mid-term to avoid colectomy. Immunosuppressive drugs raise some concerns due to an increased risk of serious and opportunistic infections and cancer, particularly in elderly and co-morbid patients, underlining the unmet need for safer alternative therapies. Granulocyte/monocytapheresis (GMA), a CE-marked, non-pharmacological procedure for the treatment of ulcerative colitis (among other immune-mediated diseases), remains the only therapy targeting neutrophils, the hallmark of pathology in ulcerative colitis. GMA has proven its efficacy in different clinical scenarios and shows an excellent and unique safety profile. In spite of being a first line therapy in Japan, GMA use is still limited to a small number of centres and countries in Europe. In this article, we aim to give an overview from a European perspective of the mechanism of action, recent clinical data on efficacy and practical aspects for the use of GMA in ulcerative colitis.

Granulocyte and monocyte adsorptive apheresis induces apoptosis of neutrophils and release of a novel chemoattractant for desensitization of interleukin-8 response - In vitro and in vivo results

OBJECTIVE

Apoptotic cells participate in maintenance of homeostasis of the adaptive immune system. Granulocyte/monocyte adsorptive apheresis (GMA) performed with an Adacolumn has been shown to have clinical efficacy together with immunomodulatory effects for immune-mediated disorder cases, such as inflammatory bowel disease (IBD) or psoriatic arthritis. Although induction of apoptosis in neutrophils by GMA has been observed, the detailed mechanism remains unclear.

METHODS

To focus on phagocytosis-induced cell death (PICD) that induces apoptotic neutrophils, a comparative study utilizing a GMA-carrier (leukocyte adsorbing carrier for Adacolumn) and yeast particles was performed with in vitro and in vivo examinations.

RESULTS

L-selectin was significantly (P = 0.0133) shed, reactive oxygen species (ROS) production was promoted (P = 0.0019), and apoptosis induction was enhanced (P = 0.0087) by peripheral blood co-cultured with the GMA-carrier or yeast particles as compared to incubated blood alone. Furthermore, degranulation of myeloperoxidase, elastase, and lactoferrin was increased by both treatments, while the highest level of interleukin-1 receptor antagonist release was found with GMA-carrier treatment (P = 0.0087) as compared to the yeast particles. Plasma from blood treated with the GMA-carrier showed chemotactic activity, and suppressed neutrophil migration to IL-8 and LTB₄. In vivo results demonstrated that neutrophil chemotaxis to IL-8 was desensitized (P = 0.0078) in rabbits following GMA apheresis, while CXCR1 and CXCR2 expressions in neutrophils were reduced by exposing peripheral blood to the GMA-carrier.

CONCLUSIONS

GMA may regulate the immune system in patients with an immune-mediated disorder by inducing a biological response of neutrophils with a PICD-like reaction.

Factors associated with the outcomes in ulcerative colitis patients undergoing granulocyte and monocyte adsorptive apheresis as remission induction therapy: A multicenter cohort study

Ulcerative colitis (UC) patients harbor activated myeloid leukocytes, which exacerbate and perpetuate UC by releasing inflammatory cytokines. Granulocyte and monocyte adsorptive apheresis (GMA) with an Adacolumn depletes elevated myeloid leukocytes, inducing efficacy with favorable safety. To understand how the clinical outcome with GMA is affected by prior corticosteroid treatment or concomitant immunomodulators, a retrospective multicenter study in 102 UC patients, who had not responded well to first-line medications was undertaken. The remission rates after a course of GMA therapy were significantly higher in corticosteroid-naïve patients compared with those with prior corticosteroid exposure. Absence of corticosteroid background was an independent predictive factor of response to GMA. Further, in corticosteroid-naïve patients, the 1-year cumulative sustained remission rate in patients who did not receive immunomodulators was significantly higher than in patients who received immunomodulators. Accordingly, multivariate analysis revealed that immunomodulator was associated with higher risk of relapse. In conclusion, GMA was an effective treatment for corticosteroid-naïve patients and the efficacy sustained longer in those not receiving immunomodulators during GMA. GMA fulfills the notion that apheresis is to induce disease remission by removing from the body factors known to perpetuate disease. In therapeutic settings, these findings should help better decision making and avoid futile use of medical resources.

Efficacy of Granulocyte and Monocyte Adsorptive Apheresis in Patients With Inflammatory Bowel Disease Showing Lost Response to Infliximab

BACKGROUND AND AIMS

In inflammatory bowel disease [IBD] patients, antibody-to-infliximab [ATI] generation is responsible for loss of response [LOR] and infusion reaction [IR] to infliximab. An immuno-therapeutic approach is considered an option to overcome LOR. Granulocyte/monocyte adsorptive apheresis [GMA] using an Adacolumn has been shown to have clinical efficacy together with immunomodulatory effects in IBD patients.

METHODS

We developed an ATI-CAI assay utilizing a C1q immobilized plate and applied it to measure ATI in patients who were receiving infliximab, including 56 with sustained response, 76 with LOR and six with IR. Furthermore, 14 patients with LOR and two with paradoxical skin reactions who received infliximab + GMA combination therapy were analysed.

RESULTS

Fourteen patients with LOR, seven with Crohn's disease and seven with ulcerative colitis, showed significantly improved clinical indices [p = 0.0009], and decreased ATI [p = 0.0171] and interleukin-6 [p = 0.0537] levels at week 8 following initiation of infliximab + GMA therapy. Nine patients who received combination therapy achieved remission, which was maintained to week 24 with infliximab alone. Additionally, cutaneous lesions in two patients with IR were improved. ATI-CAI assay efficiency was not influenced by infliximab concentration during the test. Pre- and post-infliximab infusion ATI levels were not different. Patients with ATI greater than the 0.153 μg/mL cut-off value were likely to experience LOR [odds ratio 3.0].

CONCLUSIONS

Patients who received infliximab + GMA therapy appeared to regain clinical response to infliximab by a decrease in ATI level. Furthermore, the concentration of infliximab in the test did not influence ATI measurement, but was associated with clinical response.

Selective granulocyte and monocyte apheresis in inflammatory bowel disease: Its past, present and future

The etiology and pathogenesis of inflammatory bowel disease (IBD), including ulcerative colitis and Crohn’s disease, are not fully understood so far. Therefore, IBD still remains incurable despite the fact that significant progress has been achieved in recent years in its treatment with innovative medicine. About 20 years ago, selective granulocyte and monocyte apheresis (GMA) was invented in Japan and later approved by the Japanese health authority for IBD treatment. From then on this technique was extensively used for IBD patients in Japan and later in Europe. Clinical trials from Japan and European countries have verified the effectiveness and safety of GMA therapy in patients with IBD. In 2013, GMA therapy was approved by China State Food and Drug Administration for therapeutic use for the Chinese IBD patients. However, GMA therapy has not been extensively used in China, although a few clinical studies also showed that it was effective in clinical and endoscopic induction of remission in Chinese IBD patients with a high safety profile. This article reviews past history, present clinical application as well as the future prospective of GMA therapy for patients with IBD.

Efficacy and safety of adsorptive granulomonocytapheresis in Chinese patients with ulcerative colitis: A retrospective analysis of 50 cases with focus on factors impacting clinical efficacy

Background

Myeloid‐derived leucocytes, a major source of inflammatory cytokines, play an important role in the exacerbation of ulcerative colitis (UC). Selective depletion of myeloid leucocytes by adsorptive granulomonocytapheresis (GMA) with an Adacolumn should alleviate inflammation and promote remission. However, there are discrepancies among the reported efficacy outcomes. This study aimed to evaluate the efficacy and safety of GMA in UC patients with a focus on factors affecting clinical efficacy.

Methods

This was a retrospective analysis of 50 patients with active UC who had received GMA therapy. GMA efficacy was evaluated based on the Rachmilewitz's clinical activity index (CAI) and Mayo endoscopic score for mucosal healing. Laboratory findings were analyzed to demonstrate any relationship with the GMA‐responder or nonresponder feature. Adverse events were recorded during and after GMA therapy.

Results

The overall clinical remission rate (CAI ≤4) was 79.2%, and among these, the mucosal healing rate was 59.2%. The clinical remission rate was 69.2% in patients who received 5 GMA sessions and 82.3% in patients who received 10 sessions. Significantly higher baseline CAIs and lower albumin and hemoglobin levels were observed in nonremission cases compared with those who achieved remission. Four patients (8%) experienced transient adverse events, but none were severe.

Conclusions

GMA was favored by patients because of its safety and nonpharmacological treatment options. Accordingly, UC patients were spared from pharmaceuticals after applying GMA therapy.

A young male with epitheliolysis in the small bowel and colon

Background: Toxic epidermal necrolysis (TEN) is characterized by epidermal necrosis of various degree, and can affect the entire body surface. Affection of small bowel and colon is a rare manifestation of TEN. We present a case with an unusual appearance of epitheliolysis of the small bowel and colon due to a toxic reaction.Case report: A 19 year old male was diagnosed with ulcerative colitis (UC) after treatment with tetracyclines followed by isotretinoin due to acne vulgaris. Medical treatment did not lead to improvement of his UC, and an emergency resection of the colon was performed. Postoperatively his condition worsened due to small bowel epitheliolysis, and he recovered finally 6 months later after a partial small bowel resection.Conclusion: The true cause of this very serious situation with severe gastrointestinal involvement is not fully understood. In this case, successive treatment with antibiotics and isotretinoin given to a patient with an inflamed colon might have triggered the destruction of the epithelial barrier, leading to an immense immunological reaction in the intestinal wall. We suggest that physicians should be aware of UC-like symptoms occurring prior to or during treatment with tetracyclines and/or isotretinoin.

The combination of granulocyte-monocyte apheresis and vedolizumab: A new treatment option for ulcerative colitis?

OBJECTIVES

To assess the effectiveness and safety of combining granulocyte-monocyte apheresis (GMA) and vedolizumab (VDZ) in patients with refractory ulcerative colitis (UC).

METHODS

This retrospective, multicentre pilot study included all UC patients receiving both GMA and VDZ. We recorded data on GMA sessions, demographic characteristics, and clinical response. Effectiveness was assessed 1 and 6 months after finishing the GMA using the partial Mayo score, C-reactive protein, and fecal calprotectin levels. Data were also compiled on VDZ intensification, use of new immunomodulators and colectomy during follow-up.

RESULTS

Eight patients were included (mean age 46 years; 63% female; mean disease duration, 132 months; 50% E3). GMA was started after a loss of response to VDZ in all cases (25% primary nonresponse and 75% secondary loss of response). All had previously received anti-TNF agents. VDZ was prescribed as the second-, third-, or fourth-line biologic in 37%, 50%, and 13% of cases, respectively. Patients had a mean baseline partial Mayo score of 7.5 (SD 2.1) and received a median of 15 GMA sessions (range 5-38). After a median follow-up of 7.5 months (IQR 5-12), partial Mayo score decreased after 1 and 6 months (P = .01 and .06, respectively). Three patients (38%) achieved steroid-free clinical remission and five (63%) withdrew VDZ. Colectomy rate was 38%. No adverse events were observed during the combination therapy.

CONCLUSIONS

This small case series suggests that combining GMA with VDZ could be a treatment option in selected cases of UC with an inadequate response to this biologic agent.

Novel Leucocyte/Thrombocyte Apheresis for Induction of Steroid-Free Remission in Ulcerative Colitis: A Controlled Randomized Pilot Study

BACKGROUND AND AIMS

In active ulcerative colitis [UC] refractory to mesalazine, escalation to either steroids or immunosuppression is common practice. The efficacy and safety of alternative escalation therapy with a novel leukocyte apheresis device were studied.

METHODS

This was a prospective, randomized, controlled multicentre pilot study comparing leukocyte apheresis with prednisolone in refractory UC (disease activity index [DAI] ≥ 4 and ≤8). Group A received weekly apheresis over five consecutive weeks. Group P received oral prednisolone 40 mg/day tapered to 0 mg at week 6. The primary end point was steroid-free clinical remission [DAI ≤ 2] at week 12. Clinical response was also analysed.

RESULTS

Twenty-four patients were enrolled, 13 of whom were randomized into group A and 11 into group P. Clinical remission off steroids at week 12 was achieved in 3/12 patients [25.0%] with apheresis and 2/10 [20.0%] with prednisolone [p = 1.0]. The response rate after 12 weeks was 75.0% in group A and 50.0% in group P. Mean DAI scores improved in both treatment groups [p = 0.008]. C-reactive protein decreased from 6.0 ± 5.3 to 3.8 ± 3.7 mg/L at 12 weeks in group A and increased from 5.2 ± 6.0 to 6.3 ± 7.9 mg/mL in group P. Both treatments were well tolerated. No unexpected serious adverse events were seen in group A. In group P one symptomatic infection with Clostridium difficile occurred.

CONCLUSIONS

In patients with active UC refractory to mesalazine a novel leukocyte apheresis showed promising results. A comparison with prednisolone revealed similar therapeutic effectivity and excellent safety, providing the chance to escalate without systemic steroids.

Efficacy and Safety of Adsorptive Granulocyte and Monocyte Apheresis in Elderly and Pregnant Patients With Ulcerative Colitis

In patients with active ulcerative colitis (UC), adsorptive granulocyte/monocyte apheresis (GMA) is expected to promote remission. We conducted a retrospective cohort study to evaluate the efficacy and safety of GMA in patients with active UC. Twenty-one UC patients including five pregnant or lactating mothers and four elderly patients (aged >60 years) received up to 10 GMA sessions. UC severity was evaluated at baseline and after GMA therapy according to Lichtiger's Clinical Activity Index (CAI). We defined clinical remission as CAI ≤4. Overall, the median CAI score after GMA therapy had decreased from 9 to 4 (P < 0.001). The clinical remission rate was 62%, but in the elderly and pregnant or lactating mothers, the remission rates were 100% and 60%, respectively. No severe adverse effects were seen in this study. Our results may support GMA as an effective and safe treatment for active UC patients, including elderly patients and pregnant cases.

Cellular and Molecular Therapeutic Targets in Inflammatory Bowel Disease-Focusing on Intestinal Barrier Function

The human gut relies on several cellular and molecular mechanisms to allow for an intact and dynamical intestinal barrier. Normally, only small amounts of luminal content pass the mucosa, however, if the control is broken it can lead to enhanced passage, which might damage the mucosa, leading to pathological conditions, such as inflammatory bowel disease (IBD). It is well established that genetic, environmental, and immunological factors all contribute in the pathogenesis of IBD, and a disturbed intestinal barrier function has become a hallmark of the disease. Genetical studies support the involvement of intestinal barrier as several susceptibility genes for IBD encode proteins with key functions in gut barrier and homeostasis. IBD patients are associated with loss in bacterial diversity and shifts in the microbiota, with a possible link to local inflammation. Furthermore, alterations of immune cells and several neuro-immune signaling pathways in the lamina propria have been demonstrated. An inappropriate immune activation might lead to mucosal inflammation, with elevated secretion of pro-inflammatory cytokines that can affect the epithelium and promote a leakier barrier. This review will focus on the main cells and molecular mechanisms in IBD and how these can be targeted in order to improve intestinal barrier function and reduce inflammation.