Toxicity of infliximab in the course of treatment of Crohn's disease

Evaluation of infliximab-induced genotoxicity and possible action on BCL-2 and P53 genes

Although the last pandemic created an urgency for development of vaccines, there was a continuous and concerted effort to search for therapeutic medications among existing drugs with different indications. One of the medications of interest that underwent this change was infliximab (IFM). This drug is used as an anti-inflammatory, predominantly in patients with Crohn 's disease, colitis ulcerative, and rheumatoid arthritis. In addition to these patients, individuals infected with Coronavirus Disease (COVID-19) were administered this chimeric monoclonal antibody (IMF) to act as an immunomodulator for patients in the absence of comprehensive research. Consequently, the present study aimed to examine the genotoxic effects attributed to IFM treatment employing different assays in vivo using mouse Mus musculus. Therefore, IFM was found to induce genotoxic effects as evidenced by the comet assay but did not demonstrate genotoxic potential utilizing mouse bone marrow MN test. The results of evaluating the expression of the P53 and BCL-2 genes using RT-qPCR showed stimulation of expression of these genes at 24 hr followed by a decline at 48 hr. Although the comet assay provided positive results, it is noteworthy that based upon negative findings in the micronucleus test, the data did not demonstrate significant changes in the genetic material that might affect the therapeutic use of IFM. The stimulation of expression of P53 and BCL-2 genes at 24 hr followed by a decline at 48 hr suggest a transient, if any, effect on genetic material. However, there is still a need for more research to more comprehensively understand the genotoxic profile of this medication.

Past, Present and (Foreseeable) Future of Biological Anti-TNF Alpha Therapy

Due to the key role of tumor necrosis factor-alpha (TNF-α) in the pathogenesis of immunoinflammatory diseases, TNF-α inhibitors have been successfully developed and used in the clinical treatment of autoimmune disorders. Currently, five anti-TNF-α drugs have been approved: infliximab, adalimumab, golimumab, certolizumab pegol and etanercept. Anti-TNF-α biosimilars are also available for clinical use. Here, we will review the historical development as well as the present and potential future applications of anti-TNF-α therapies, which have led to major improvements for patients with several autoimmune diseases, such as rheumatoid arthritis (RA), ankylosing spondylitis (AS), Crohn's disease (CD), ulcerative colitis (UC), psoriasis (PS) and chronic endogenous uveitis. Other therapeutic areas are under evaluation, including viral infections, e.g., COVID-19, as well as chronic neuropsychiatric disorders and certain forms of cancer. The search for biomarkers able to predict responsiveness to anti-TNF-α drugs is also discussed.

A review of the impact of biologics on surgical complications in Crohn's disease

Anti-tumor necrosis factor therapy has revolutionized the treatment of Crohn's disease. Despite the increased use in the past decade and a half, a majority of patients with Crohn's disease with ultimately require operative management of their disease. No clear consensus has been made in the literature regarding the surgical outcomes in patients who have been exposed to anti-tumor necrosis factor therapy. This review highlights the most recent and relevant literature regarding the safety and effects of anti-tumor necrosis factor use in the perioperative period.

Factors associated with treatment outcome, and long-term prognosis of patients with ulcerative colitis undergoing selective depletion of myeloid lineage leucocytes: a prospective multicenter study

BACKGROUND

Patients with ulcerative colitis (UC) have elevated/activated myeloid lineage leucocytes and may respond favorably to adsorptive granulocyte/monocyte apheresis (GMA). However, there are patients who respond well to GMA, and patients who do not benefit. Therefore, predictive factors of GMA efficacy need to be defined.

METHODS

In a prospective multicenter setting, 200 UC patients at 32 institutes received one GMA session per week over 10 weeks. Patients who achieved remission were followed for 12 months. The Clinical Activity Index (CAI) ≤3 meant remission, and response meant CAI decreased by ≥3. Quality of life was evaluated by the Inflammatory Bowel Disease Questionnaire (IBDQ).

RESULTS

After final GMA, remission, response and no response rates were 67.0%, 15.0% and 18%, respectively. The remission group had a significant decrease in myeloid leucocytes and platelets. Corticosteroid dose decreased (P < 0.001); 49 of 97 patients on corticosteroids became steroid-free. Baseline CAI was lower in the remission group versus non-remission (P < 0.01), whereas IBDQ was higher in the remission group versus non-remission (P < 0.05). After 12 months, 52 of 134 patients had maintained remission. Disease duration was longer in the relapsed group versus maintained remission group (P = 0.041). Male gender, first UC episode and corticosteroid responder were significant factors for maintaining remission, whereas corticosteroid dependent UC was associating with relapse.

DISCUSSION

Selective myeloid leucocyte depletion was effective for remission induction and improving patients' quality of life. Baseline demographics such as disease activity level, duration and corticosteroid dependency appear to predict response to GMA. Additionally, patients with a first UC episode who were drug naive responded well to GMA and achieved a favorable long-term disease course by avoiding pharmacologics from an early stage of their inflammatory bowel disease. These findings should help to end unnecessary use of medical resources by targeting GMA to patients who may respond well.

Early diagnosis and treatment of postoperative endoscopic recurrence of Crohn's disease: partial benefit by infliximab--a pilot study

BACKGROUND

Current data indicate that infliximab-given immediately after surgery-may be very effective in preventing postsurgical recurrence of Crohn's disease. However, it is unknown whether a similar benefit would result from early diagnosis and treatment, rather than prevention of endoscopic recurrence.

AIMS

The primary outcome of this study was to clarify whether infliximab, given after diagnosis of postoperative endoscopic recurrence of Crohn's diseases (Rutgeerts score ≥ 2) can induce endoscopic remission (score <2) at 54 weeks. The secondary outcomes were improvement in the endoscopic score and clinical recurrence at 54 weeks.

METHODS

In this prospective open label multicenter pilot study 43 patients with ileocolonic Crohn's disease subjected to curative surgery underwent colonoscopy 6 months after surgery. Patients with endoscopic recurrence (Rutgeerts score ≥2) were treated with either mesalamine 800 mg tid or infliximab 5 mg/kg bw on a maintenance basis. Colonoscopy was performed after 54 weeks of therapy.

RESULTS

A total of 24/43 patients were diagnosed with endoscopic recurrence at 6 months. Thirteen were treated with infliximab and 11 with mesalamine. None of the 11 mesalamine-treated patients had endoscopic remission at 54 weeks. Two had clinical recurrence at 8 and 9 months. Fifty-four percent of patients treated with infliximab had endoscopic remission at 54 weeks (P = 0.01) while 69% had an improvement in the endoscopic score. None had clinical recurrence.

CONCLUSIONS

Treatment of postsurgical endoscopic lesions by infliximab appears superior to mesalamine. However, a sizeable proportion of patients did not fully benefit from this strategy.

Low-dose maintenance therapy with infliximab prevents postsurgical recurrence of Crohn's disease

BACKGROUND & AIMS

Infliximab might prevent postsurgical recurrence of Crohn's disease. However, it is unclear whether long-term therapy is necessary and whether alternative strategies could be applied to minimize potential side effects and reduce the costs of treatment.

METHODS

We performed a prospective cohort study in 12 consecutive patients, treated immediately after surgery with maintenance infliximab (5 mg/kg), who did not have clinical or endoscopic evidence of disease recurrence after 24 months; they were followed up for an additional year. Infliximab treatment was then discontinued; patients with disease recurrence, based on endoscopy (Rutgeerts score, >or=2), were given lower doses of infliximab (starting with 1 mg/kg) to re-establish mucosal integrity. Surrogate markers of disease activity (fecal calprotectin [FC], C-reactive protein, and erythrocyte sedimentation rate) were assessed after each infliximab dose.

RESULTS

None of the patients had clinical or endoscopic recurrence of Crohn's disease 3 years after surgery. However, discontinuation of infliximab caused endoscopic recurrence after 4 months in 10 of 12 patients (83%). All 10 patients then were treated again with infliximab, which, at a dose of 3 mg/kg every 8 weeks, restored and maintained mucosal integrity for 1 year. Among the surrogate markers, FC levels correlated with endoscopic scores (Wald test, P < .0001).

CONCLUSIONS

Long-term maintenance therapy with infliximab is required to maintain mucosal integrity in patients after surgery for Crohn's disease. However, a dose of 3 mg/kg (a 40% reduction from the standard dose) was sufficient to avoid disease recurrence, determined by endoscopy, in all patients at 1 year. FC levels correlate with mucosal status at different infliximab doses.

Role of the C5a receptor (C5aR) in acute and chronic dextran sulfate-induced models of inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is a critical public health issue; more and more people are affected, but treatment options remain limited. Complement activation and the anaphylatoxin C5a have been shown to play a role in IBD. In this study, mouse models of acute and chronic dextran sulfate-induced colitis were used to further elucidate the impact of C5a and its receptor (C5aR) on disease development.

METHODS

In C57BL/6J wildtype and C5aR(-/-) mice the extent of complement activation, changes in weight, and water/food consumption were determined. Disease severity was evaluated via a clinical score, histology, cytokine- and myeloperoxidase-determination as well as real-time reverse-transcriptase polymerase chain reaction (RT-PCR) for expression of anaphylatoxin receptors and inflammatory mediators.

RESULTS

C5aR(-/-) mice showed milder disease symptoms, less histological damage, and a lower expression of inflammatory mediators in acute colitis, a setting where complement was activated. In chronic colitis the knockout mice exhibited aggravated weight loss, a higher degree of histological damage and granulocyte infiltration. Intriguingly, increases in C3a-receptor and C5L2 mRNA were dependent on C5aR. Compared to wildtype mice, C5aR(-/-) animals displayed smaller lymph nodes in acute colitis, but extensive swelling and diminished IL-4 and IFN-γ responses in the chronic disease, demonstrating that C5aR modifies T-helper cell polarization.

CONCLUSIONS

C5aR exerts detrimental functions in acute colitis, strongly supporting the idea that a C5aR-antagonist might be useful for IBD treatment. However, since the absence of C5aR was no longer protective and in some regards disadvantageous in chronic IBD, future studies should address the efficacy and the possible side effects of a sustained antagonist treatment.

Use of infliximab within 3 months of ileocolonic resection is associated with adverse postoperative outcomes in Crohn's patients

BACKGROUND

Few studies have evaluated preoperative infliximab use and postoperative outcomes in Crohn's patients. Our aim was to evaluate 30-day postoperative outcomes for Crohn's patients treated with infliximab within 3 months prior to ileocolonic resection.

METHODS

The study is a retrospective evaluation of data for patients undergoing ileocolonic resection after 1998 from a prospective Crohn's disease database. Patient characteristics and 30-day complications were compared for patients treated with infliximab within 3 months before surgery and an infliximab naïve group. The infliximab group was also compared with non-infliximab patients undergoing ileocolonic surgery before 1998.

RESULTS

Sixty of 389 Crohn's patients undergoing ileocolonic resection received infliximab. The infliximab and non-infliximab groups had similar characteristics, preoperative risk factors, and surgical procedure. However, steroid use was higher (p < 0.05) in the non-infliximab group while concurrent immunosuppressive use was higher (p < 0.001) in the infliximab group. Multivariate analysis showed infliximab use to be associated with 30-day postoperative readmission (p = 0.045), sepsis (p = 0.027), and intraabdominal abscess (p = 0.005). The presence of diverting stoma (n = 17) in the infliximab group was associated with lower risk of sepsis (0% vs. 27.9%, p = 0.013). Similar results were noted when the infliximab group was compared to the pre-infliximab patients.

CONCLUSIONS

Infliximab use within 3 months before surgery is associated with increased postoperative sepsis, abscess, and readmissions in Crohn's patients. Diverting stoma may protect against these complications.

Therapeutic options in acute severe ulcerative colitis

Ulcerative colitis is a relapsing-remitting inflammatory disease affecting the colon and is associated with considerable morbidity. In acute severe attacks, there continues to be an associated mortality rate of 1-2%, even in specialist units. During an acute severe exacerbation, approximately two-thirds of patients will respond to intravenous corticosteroid therapy, the accepted first-line therapy in such cases. For steroid-refractory patients, options are limited to surgery (colectomy) or second-line agents, such as ciclosporin or infliximab, used in an attempt to salvage the colon. Considerable debate exists over the optimal management of such patients. During the last decade, an increased understanding of the pathogenesis of inflammatory bowel disease has led to the rapid development of other biological agents, such as basiliximab and visilizumab. Novel methods, such as leucopheresis, have been studied and other established immunomodulatory agents, such as tacrolimus, have also been suggested. The purpose of this review is to highlight some of the areas of recent development in the treatment of acute severe ulcerative colitis and review important safety data, with a particular emphasis on biological agents.

Current treatment of inflammatory bowel disease in children

Children with inflammatory bowel disease present formidable therapeutic challenges. As both Crohn's disease and ulcerative colitis remain medically incurable conditions associated with potentially significant morbidity, the focus of treatment must be to reduce or eliminate symptoms, optimize nutritional status, promote normal growth and development, prevent complications and minimize the potential psychological effects of these chronic illnesses. This review focuses on the evidence supporting the treatments currently used in children with inflammatory bowel disease, and suggests potential treatment algorithms for particular clinical circumstances.

Review article: minimizing tuberculosis during anti-tumour necrosis factor-alpha treatment of inflammatory bowel disease

BACKGROUND

Tumour necrosis factor (TNF)-alpha inhibitors are a major advance in the management of inflammatory bowel disease but increase the risk for tuberculosis (TB).

AIM

To examine the reasons for the increase in the risk for TB and the strategies to reduce it.

METHODS

PubMed searches were performed using search terms that included TB and each of the current anti-TNF-alpha biological agents and also TB and Crohn's disease.

RESULTS

Increased susceptibility to TB, often with extrapulmonary or disseminated disease, occurs following treatment with all anti-TNF-alpha biological agents and amounts to a four- to 20-fold increased risk with infliximab. TB usually occurs shortly after anti-TNF-alpha initiation suggesting reactivation of latent infection. Animal studies show that TNF-alpha inhibition impairs inflammatory cell trafficking and granuloma formation. Currently recommended screening for latent TB typically, risk assessment, tuberculin skin testing and chest radiograph used prior to anti-TNF-alpha treatment can reduce TB rates by up to 90% but newer screening interferon gamma assays may enhance screening efficacy. Patients positive on screening who are treated with isoniazid and subsequently receive anti-TNF-alpha treatment still have approximately 19% risk for TB.

CONCLUSIONS

Tuberculosis following treatment with TNF-alpha inhibitors usually results from reactivation of latent disease. Screening reduces the risk substantially but does not completely eliminate it.

Treatment with anti-gamma-glutamyl transpeptidase antibody attenuates osteolysis in collagen-induced arthritis mice

The effectiveness of a new antibody treatment on arthritis-associated osteolysis was studied by using CIA mice. GGT, a newly identified bone-resorbing factor, was upregulated in arthritic joints. We generated monoclonal antibodies against GGT and injected them into CIA mice. Mice treated with antibodies showed a reduction in osteoclast number and bone erosion.

INTRODUCTION

Gamma-glutamyl transpeptidase (GGT) acts as a bone-resorbing factor that stimulates osteoclast formation. GGT expression has been detected in active lymphocytes that accumulate at inflammation sites, such as rheumatoid arthritis (RA). We hypothesize that GGT is an effective target for suppression of arthritis-related osteoclastogenesis and joint destruction. Here, we describe the therapeutic effect of neutralizing antibodies against GGT on joint destruction using a collagen-induced arthritis (CIA) mouse model.

MATERIALS AND METHODS

GGT expression in the synovium of RA patients and CIA mice was determined by immunohistochemistry and RT-PCR. Monoclonal antibodies were generated against recombinant human GGT (GGT-mAbs) using BALB/c mice. Antibody treatment was performed by intraperitoneal injections of GGT-mAbs into CIA mice. Effects of antibody treatment on arthritis and bone erosion were evaluated by incidence score, arthritis score, and histopathological observations. The role of GGT in osteoclast development was examined by using the established osteoclastogenic culture system.

RESULTS

GGT expression was significantly upregulated in inflamed synovium. Immunohistochemistry revealed that GGT was present in lymphocytes, plasma cells, and macrophages, as well as capillaries. Injection of GGT-mAbs significantly decreased the number of osteoclasts and attenuated the severity of joint destruction in CIA mice. In vitro examination showed that GGT enhanced RANKL-dependent osteoclast formation. GGT stimulated the expression of RANKL in osteoblasts and its receptor RANK in osteoclast precursors, respectively.

CONCLUSIONS

This study indicates that inflamed synovial tissue-derived GGT acts as a risk factor for joint destruction and that the antibody-mediated inhibition of GGT significantly decreases osteoclast number and bone erosion in CIA mice. GGT antagonists might be novel therapeutic agents for attenuating joint destruction in RA patients.

Clinical pharmacokinetics and use of infliximab

Tumor necrosis factor-alpha (TNFalpha) is a key proinflammatory cytokine involved in chronic inflammatory diseases. Infliximab, a chimeric (human-murine) monoclonal IgG1 anti-TNFalpha antibody, is used in the treatment of Crohn's disease (including fistulising disease) and rheumatoid arthritis (in combination with methotrexate) if standard treatments have failed. The indications for infliximab have recently been expanded to include ankylosing spondylitis, psoriatic arthritis, psoriasis and ulcerative colitis. The biological agent infliximab is given by multiple intravenous infusions in a dosage of 3-5 mg/kg (initially at weeks 0, 2 and 6; subsequently in intervals of 4-8 weeks). In controlled trials, clinical response rates of 20-40% have been achieved with such regimens in Crohn's disease and rheumatoid arthritis. However, the therapeutic benefits must be balanced against the risks of a variety of severe adverse events (e.g. severe infections including tuberculosis, hepatotoxicity, infusion reactions, serum sickness-like disease and lymphoma). Following single and multiple infusions of infliximab, no relevant differences in median concentration-time profiles have been observed between patients with Crohn's disease, patients with rheumatoid arthritis and patients with psoriasis. The apparent volume of distribution of the high-molecular-weight infliximab (149.1 kDa) is low (3-6L) and represents the intravascular space. The long persistence in this compartment (elimination half-life 7-12 days, mean residence time 12-17 days) is due to the very low systemic clearance of about 11-15 mL/hour (0.18-0.25 mL/minute). Elimination of infliximab is most probably accomplished through degradation by unspecific proteases. During multiple infusions (every 4-8 weeks), no accumulation was observed, and serum concentrations and the area under the plasma concentration-time curve of infliximab increased in proportion to the infused dose, indicating linear pharmacokinetics. Co-medication with methotrexate delayed the decline in the serum concentrations of infliximab. When relating serum concentrations to the clinical response in patients with rheumatoid arthritis and patients with Crohn's disease, it can be assumed that trough concentrations above 1 microg/mL could be used as a kind of therapeutic target. In the future, identification of biomarkers for (non-)response and risk factors for adverse drug reactions would be very helpful. Furthermore, combined biological, pharmacokinetic, pharmacogenomic and clinical studies have not yet been performed and are needed to optimise the therapeutic potential of infliximab, which is currently established as a rescue treatment in refractory patients.

Humoral and cellular monitoring to predict the development of infection in Crohn's disease patients beginning treatment with infliximab

Although severe infectious complications are rare, it is important to properly screen patients for predisposing conditions before beginning treatment with infliximab. We assessed immunity markers that might provide prognostic value for the development of infection in Crohn's disease patients after treatment with infliximab. In a prospective study, 34 fistulizing Crohn's disease patients (mean age 37 years) were studied. Patients were scheduled to receive three infusions of infliximab (5 mg/kg) at weeks 0, 2, and 6. Immunologic studies: Serum immunoglobulin (IgG, IgA, IgM), IgG-subclasses, and complement (C3, C4, factor B) determined by nephelometry; CD3+, CD3+CD4+, CD3+CD8+, CD19+, and CD56+CD3- lymphocyte subsets performed by flow cytometry. During a mean follow-up of 56 months, 1 patient had disseminated tuberculosis and 2 patients had severe bacterial infections. The presence of infection was associated with significantly higher IgM (246 vs. 121 mg/dL; Mann-Whitney test, P = 0.01), lower C3 (64 vs. 118, P = 0.02), lower C4 concentrations (12 vs. 25, P = 0.02), and with decreased levels of CD19 B cells (47 vs. 290, P = 0.03) in the baseline study. Further prospective studies in a larger number of patients are suggested to examine whether early monitoring of immunocompetence might help to identify the risk of infection in patients treated with infliximab.

The inhibition of TNF-alpha anti-tumoral properties by blocking antibodies promotes tumor growth in a rat model

Tumor necrosis factor (TNF) antagonists represent a milestone in the therapy of autoimmune conditions. Anti-TNF antibodies have been approved for clinical use and during the last eight years thousands of patients have been treated. However, the long-term sequelae of anti-TNF agents in promoting carcinogenesis remain unclear. This study sought to define the role of intra-tumor TNF-alpha production on cancer cell progression and to determine whether TNF-alpha antibodies can suppress anti-tumoral immunity. Using an experimental animal tumor model we demonstrate that anti-TNF-alpha antibodies hinder anti-tumor immune responses and promote growth of immunogenic rat colon tumors (REG) that are always rejected by immunocompetent untreated rats. The major role of TNF-alpha in the anti-tumoral immune response was confirmed by transfecting progressive and tolerogenic rat colon tumor cells (PRO) with the TNF-alpha gene. PRO tumor cells secreting TNF-alpha induce tumor-infiltrating dendritic cell (DC) activation. This triggers a potent immune response leading to tumor rejection and long-lasting immunity. Therefore, the prominent role of TNF-alpha in anti-tumoral immune responses underscores the need for caution and close surveillance following the administration of TNF inhibitors.

Update in the treatment of paediatric ulcerative colitis

Ulcerative colitis is an important disease in the paediatric population. Ulcerative colitis is one of the chronic inflammatory bowel diseases, and is medically incurable. However, the arsenal of medications has grown as knowledge of the pathogenesis of this disease advances. This review looks at the classical treatments for children with ulcerative colitis, including the 5-aminosalicylates, corticosteroids and imunomodulators, as well as biological therapy and other, newer modalities.

Medical therapy for refractory pediatric Crohn's disease

Crohn's disease is a common indication for referral to pediatric gastroenterology. While most patients with Crohn's disease respond to standard induction therapy, steroid-refractory or steroid-dependent disease is a frequently encountered problem. This review discusses the data existing in both the adult and pediatric literature for medical therapy of refractory pediatric Crohn's disease.

Quality of life after proctocolectomy with ileoanal anastomosis for patients with ulcerative colitis

Ulcerative colitis, a chronic inflammatory disease of the rectal and colonic mucosa, affects approximately 250,000 to 500,000 people in the United States, with 30% to 40% of patients requiring some form of surgical intervention during the course of their disease. The predominant reason for total proctocolectomy is for symptoms refractory to currently available medical therapy. Less common reasons are dysplasia or cancer. The goal of colectomy is to prevent recurrence of systemic inflammatory disease. Consequently, surgery with total proctocolectomy and creation of an ileal J-pouch-anal anastomosis has become the procedure of choice for many patients without other therapeutic options. Health-related quality of life (QOL) in patients with severe ulcerative colitis is so poor that, after ileal J-pouch-anal anastomosis, QOL is considered to improve in most clinical studies (8 studies, improved QOL; 1 study, no change; 1 study, QOL worse than general population). However, QOL and bowel function after such surgery cannot be considered "normal" in all patients, because a substantial number still have problems with urgency, leakage, nocturnal soiling, sexual dysfunction, and pouchitis, and some require conversion to a permanent ileostomy after ileal J-pouch-anal anastomosis failure. Thus, despite the availability of ileal J-pouch-anal anastomosis, surgery does not always restore all aspects of QOL to normal.

Development of a novel bioavailable inhibitor of the calmodulin-regulated protein kinase MLCK: a lead compound that attenuates vascular leak

Tissue barriers involving epithelial and endothelial cell layers are critical to homeostasis, regulating passage of water, macromolecules, cells and certain classes of small molecules via two distinct cellular mechanisms, transcellular or paracellular. Endothelial or epithelial barrier dysfunction is a key component of pathophysiology in diverse diseases and injuries that have a broad impact on survival and quality of life. However, effective and safe small molecule therapeutics for these disorders are lacking. Success in development would therefore fill a major unmet medical need across multiple disease areas. Myosin light chain kinase (MLCK), a highly specialized calcium/calmodulin (CaM) regulated protein kinase, modulates barrier function through its regulation of intracellular contractile processes. MLCK levels and activity are increased in various animal models of disease and in human clinical disease samples. Our prior work with a genetic knockout (KO) mouse strain for the long form of MLCK, MLCK210, has identified MLCK as a drug discovery target for endothelial and epithelial barrier dysfunction. We describe here the development of a selective, bioavailable, stable inhibitor of MLCK that attenuates barrier dysfunction in mice comparable to that seen with the MLCK KO mice. The inhibitor compound 6 is stable in human microsomal metabolic stability assays and can be synthesized in a high-yielding and facile synthetic process. These results provide a foundation for and demonstrate the feasibility of future medicinal chemistry refinement studies directed toward the development of novel therapies for disorders involving barrier dysfunction.