Programmed cell death-1 (PD-1) and programmed death-ligand 1 (PD-L1) expression in PD-1 inhibitor-associated colitis and its mimics

Novel endoscopic scoring system for immune mediated colitis: a multicenter retrospective study of 674 patients

BACKGROUND AND AIMS

No endoscopic scoring system has been established for immune-mediated colitis (IMC). This study aimed to establish such a system for IMC and explore its utility in guiding future selective immunosuppressive therapy (SIT) use compared to clinical symptoms.

METHODS

This retrospective, international, 14-center study included 674 patients who developed IMC after immunotherapy and underwent endoscopic evaluation. Ten endoscopic features were selected by group consensus and assigned 1 point each to calculate an IMC endoscopic score (IMCES). IMCES cutoffs were chosen to maximize specificity for SIT use. This specificity was compared between IMCESs, and clinical symptoms were graded according to a standardized instrument.

RESULTS

A total of 309 (45.8%) patients received SIT. IMCES specificity for SIT use was 82.8% with a cutoff of 4. The inclusion of ulceration as a mandatory criterion resulted in higher specificity (85.0% for a cutoff of 4). In comparison, the specificity of a Mayo endoscopic subscore of 3 was 74.6%, and the specificity of clinical symptom grading was much lower at 27.4% and 12.3%, respectively. Early endoscopy was associated with timely SIT use (P < .001; r = 0.4084).

CONCLUSIONS

This is the largest multicenter study to devise an endoscopic scoring system to guide IMC management. An IMCES cutoff of 4 has a higher specificity for SIT use than clinical symptoms, supporting early endoscopic evaluation for IMC.

Enterocolitis and other immunotherapy and targeted therapy-related gastrointestinal manifestations: A review for gastroenterologist

New oncologic treatments, particularly immunotherapy (IT), have revolutionized the treatment of advanced-stage malignant tumors. Immune checkpoint inhibitors are the main form of IT and act by increasing T cell activity and the organism's immune response against neoplastic cells. Targeted therapy is another form of IT that acts by inhibiting oncogenes or inflammation signaling and tumor angiogenesis pathways. However, these mechanisms of tumor destruction can interfere with the host's immune self-tolerance or with the mechanisms of epithelial tissue repair and predispose to immune system-mediated adverse events that can affect multiple organs, including the digestive tract. The gastrointestinal manifestations of damage caused by IT can range from low-grade mucositis to ulceration, and in some cases, necrosis and perforation. Any part of the gastrointestinal tract can be affected, but there is greater involvement of the small bowel and colon, with a pattern similar to that seen in inflammatory bowel disease. The most common clinical manifestation is chronic diarrhea. The differential diagnosis includes enteropathogenic infections, especially those caused by opportunistic microorganisms; adverse drug reactions; and other inflammatory and malabsorption disorders. Treatment is guided by damage severity. Mild cases can be treated with antidiarrheals and rehydration in the outpatient setting; moderate cases with hospitalization, systemic steroids, and temporary suspension of IT; and severe cases with immunosuppressants or biologic agents and definitive suspension of IT.

PD-1-positive cells contribute to the diagnosis of inflammatory bowel disease and can aid in predicting response to vedolizumab

Differentiating inflammatory bowel disease (IBD) from other inflammatory diseases is often challenging. Programmed cell death protein-1 (PD-1) is expressed in T cells and is an indicator of their exhaustion. The role of PD-1 expression in diagnosing IBD and predicting the response of biologic agents remains inconclusive. In this study, endoscopic biopsy samples of 19 patients diagnosed with IBD, intestinal tuberculosis, and intestinal Behcet's disease were analyzed using multiplexed immunohistochemistry. Additionally, a separate "vedolizumab (VDZ) cohort" established in ulcerative colitis patients who underwent endoscopic biopsy before VDZ administration was analyzed to predict response to VDZ. In the immunohistochemistry analysis, the cell density of T cell subsets, including PD-1 + cells, was investigated and compared between IBD and other inflammatory diseases (OID). Cell densities of PD-1 + cells (p = 0.028), PD-1 + helper T cells (p = 0.008), and PD-1 + regulatory T cells (p = 0.024) were higher in IBD compared with OID. In the VDZ cohort, patients with a 14-week steroid-free clinical response had higher levels of PD-1 + cells (p = 0.026), PD-1 + helper T cells (p = 0.026), and PD-1 + regulatory T cells (p = 0.041) than the no response group. PD-1 + immune cells may contribute to the diagnosis of IBD and could be used to predict response to VDZ in ulcerative colitis patients.

Case Report: A severe case of immunosuppressant-refractory immune checkpoint inhibitor-mediated colitis rescued by tofacitinib

Immune checkpoint inhibitor therapy for cancer treatment can give rise to a variety of adverse events. Here we report a male patient with metastatic melanoma who experienced life-threatening colitis and duodenitis following treatment with ipilimumab and nivolumab. The patient did not respond to the first three lines of immunosuppressive therapy (corticosteroids, infliximab, and vedolizumab), but recovered well after administration of tofacitinib, a JAK inhibitor. Cellular and transcriptional data on colon and duodenum biopsies shows significant inflammation in the tissue, characterized by a large number of CD8 T cells and high expression of PD-L1. While cellular numbers do decrease during three lines of immunosuppressive therapy, CD8 T cells remain relatively high in the epithelium, along with PD-L1 expression in the involved tissue and expression of colitis-associated genes, indicating an ongoing colitis at that moment. Despite all immunosuppressive treatments, the patient has an ongoing tumor response with no evidence of disease. Tofacitinib might be a good candidate to consider more often for ipilimumab/nivolumab-induced colitis.

The significance of PD-1/PD-L1 imbalance in ulcerative colitis

Objectives

To investigate the expression and significance of programmed cell death protein 1 (PD-1) and programmed cell death ligand-1 (PD-L1) in the mucosal tissues and peripheral blood of patients with ulcerative colitis (UC).

Methods

Eighty patients with UC were recruited from January 2021 to August 2022 from the Shanxi Province People's Hospital. PD-1 and PD-L1 expression was assessed by immunohistochemistry in mucosal tissues. An enzyme-linked immunosorbent assay was used to measure soluble PD-1 and PD-L1 levels in peripheral blood serum, and the membrane-bound forms of PD-1 (mPD-1), (T-helper cell) Th1 and Th17, in peripheral blood were determined by flow cytometry.

Result

PD-1 expression was observed only in the monocytes of the mucosal lamina propria of UC patients, while PD-L1 was mainly located in both epithelial cells and monocytes on the cell membrane. The expression level of PD-1/PD-L1 in the monocytes and epithelial cells of mucosal lamina propria increased with disease activity (P < 0.05). The percentages of PD-1/T and PD-1/CD4+T in the peripheral blood of moderate UC patients (PD-1/T 12.83 ± 6.15% and PD-1/CD4+T 19.67 ± 9.95%) and severe UC patients (PD-1/T 14.29 ± 5.71% and PD-1/CD4+T 21.63 ± 11.44%) were higher than in mild UC patients (PD-1/T 8.17 ± 2.80% and PD-1/CD4+T 12.44 ± 4.73%; P < 0.05). There were no significant differences in PD-1/CD8+T cells between mild and severe UC patients (P > 0.05). There was a statistically significant difference in the expression level of sPD-L1 between the UC groups and healthy controls, and the expression level of sPD-L1 increased with disease severity (P < 0.05); however, there was no statistically significant difference in sPD-1 expression levels between the UC groups and healthy controls (P > 0.05). The correlation coefficients between Th1 and sPD-L1, PD-1/T, PD-1/CD4+T and PD-1/CD8+T were 0.427, 0.589, 0.486, and 0.329, respectively (P < 0.001). The correlation coefficients between Th17 and sPD-L1, PD-1/T, PD-1/CD4+T and PD-1/CD8+T were 0.323, 0.452, 0.320, and 0.250, respectively (P < 0.05).

Conclusion

The expression level of PD-1/PD-L1 was correlated with UC disease activity, and two forms of PD-1 and PD-L1 may be used as a potential marker for predicting UC and assessing disease progression in UC patients. PD-1/PD-L1 imbalance was a significant phenomenon of UC immune dysfunction. Future research should focus on two forms of PD-1/PD-L1 signaling molecules to better understand the pathogenesis of UC and to identify potential drug therapies.

Constitutive programmed death ligand 1 expression protects gastric G-cells from Helicobacter pylori-induced inflammation

INTRODUCTION

Gastric intestinal metaplasia (GIM) is a premalignant lesion, highly associated with Helicobacter pylori infection. Previous studies have shown that H. pylori is able to induce the expression of programmed death ligand 1 (PD-L1), an inhibitory immune modulator, in gastric cells. Our aim was to investigate whether tissues from GIM patients may exploit PD-L1 expression upon H. pylori infection to evade immunosurveillance.

METHODS

Immunohistochemistry was performed for PD-L1 and enteroendocrine markers somatostatin and gastrin on samples derived from a cohort of patients with known GIM, both before and after H. pylori eradication. To determine the identity of any observed PD-L1-positive cells, we performed multiplex immunofluorescent staining and analysis of single-cell sequencing data.

RESULTS

GIM tissue was rarely positive for PD-L1. In normal glands from GIM patients, PD-L1 was mainly expressed by gastrin-positive G-cells. While the D-cell and G-cell compartments were both diminished 2-fold (p = .015 and p = .01, respectively) during H. pylori infection in the normal antral tissue of GIM patients, they were restored 1 year after eradication. The total number of PD-L1-positive cells was not affected by H. pylori, but the percentage of PD-L1-positive G-cells was 30% higher in infected subjects (p = .011), suggesting that these cells are preferentially rescued from destruction.

CONCLUSIONS

Antral G-cells frequently express PD-L1 during homeostasis. G-cells seem to be protected from H. pylori-induced immune destruction by PD-L1 expression. GIM itself does not express PD-L1 and is unlikely to escape immunosurveillance via expression of PD-L1.

Beyond Cancer: Regulation and Function of PD-L1 in Health and Immune-Related Diseases

Programmed Cell Death 1 Ligand 1 (PD-L1, CD274, B7-H1) is a transmembrane protein which is strongly involved in immune modulation, serving as checkpoint regulator. Interaction with its receptor, Programmed Cell Death Protein 1 (PD-1), induces an immune-suppressive signal, which modulates the activity of T cells and other effector cells. This mediates peripheral tolerance and contributes to tumor immune escape. PD-L1 became famous due to its deployment in cancer therapy, where blockage of PD-L1 with the help of therapeutic antagonistic antibodies achieved impressive clinical responses by reactivating effector cell functions against tumor cells. Therefore, in the past, the focus has been placed on PD-L1 expression and its function in various malignant cells, whereas its role in healthy tissue and diseases apart from cancer remained largely neglected. In this review, we summarize the function of PD-L1 in non-cancerous cells, outlining its discovery and origin, as well as its involvement in different cellular and immune-related processes. We provide an overview of transcriptional and translational regulation, and expression patterns of PD-L1 in different cells and organs, and illuminate the involvement of PD-L1 in different autoimmune diseases as well as in the context of transplantation and pregnancy.

Pharmacological Treatments Available for Immune-Checkpoint-Inhibitor-Induced Colitis

Immune checkpoint inhibitor treatment has shown revolutionary therapeutic effects in various carcinomas. However, immune-related adverse events (irAE) following this treatment can sometimes lead to treatment discontinuation. One such frequently encountered adverse event is immune-related colitis (irAE colitis). Corticosteroids (CS) are the first-line treatment for irAE colitis, but we often encounter CS-refractory or -resistant cases. The application of multiple biologics has been proposed as a therapy to be administered after CS treatment; however, the efficacy and safety of biologics for patients with irAE colitis who do not respond to CS have not been established. This review summarizes the treatment regimens available for irAE colitis, focusing on the mechanism of action of corticosteroids, infliximab, vedolizumab, and other drugs.

Over-expression of Programmed Death Ligand 1 (PD-L1) in Refractory Inflammatory Bowel Disease (IBD)

Programmed death ligand 1 (PD-L1) dysregulation has been implicated in chronic inflammatory diseases, but its role in regulating intestinal mucosa inflammation is still unclear. The aim of this study was to assess PD-L1 expression in the intestinal mucosa of patients with refractory inflammatory bowel disease (IBD) compared to controls. We evaluated PD-L1 expression by immunohistochemistry in colectomy specimens of patients with ulcerative colitis (UC) and Crohn disease (CD) compared to controls. PD-L1 expression was assessed in colonic epithelium and inflammatory cells, along with the location of the inflammatory cells expressing PD-L1. All cases were stained with CD3, CD4, CD8, FOXP3, CD20, CD68, and CD90 immunostains to determine the types of cells expressing PD-L1. The UC group showed significantly higher PD-L1 expression in the colonic epithelium compared to both CD and control groups (both P<0.001), and CD was also significantly higher than the control group (P=0.004). Both UC and CD groups showed similar PD-L1 expression in the inflammatory infiltrate, but significantly higher than the control group (both P<0.001). Among both IBD groups, higher IBD activity was associated with higher levels of PD-L1 expression in the colonic epithelium (P<0.05) and inflammatory infiltrate (P<0.001). When comparing PD-L1 expression to lineage specific markers, CD3+, CD4+ T cells, CD68+ macrophages, and CD90+ colonic stromal cells appeared to be expressing PD-L1. These findings implicate a role for PD-L1 in the dysregulation of the immune response in refractory IBD. Further studies are warranted to better understand the role of the immune regulatory pathways in intestinal mucosa.

Incidence of immune checkpoint inhibitor-mediated diarrhea and colitis (imDC) in patients with cancer and preexisting inflammatory bowel disease: a propensity score-matched retrospective study

Background and aims

The risk of use of immune-mediated diarrhea and colitis (imDC) in patients with preexisting inflammatory bowel disease (IBD) is not fully understood. We report the incidence of imDC in these patients, and compare with a matched cohort of patients with cancer and without IBD.

Methods

Patients with IBD from a tertiary center cancer registry who underwent immune checkpoint inhibitor (ICI) therapy from 2011 to 2019 were identified. A 1:5 matched cohort of patients with and without a history of IBD was created, based on age, ICI therapy, and cancer type. Demographic data, clinical history of IBD, cancer, ICI agent, imDC events after ICI therapy, and overall survival were analyzed. Overall survival and time-to-imDC (TTimDC) were estimated by Kaplan-Meier and multivariate Cox proportional-hazards models.

Results

From a retrospective cohort of 3900 patients who received ICI therapy, 30 patients with IBD were matched with 150 patients without a history of IBD. Most patients received PD-1/PD-L1 inhibitor monotherapy (154/180, 85.6%). Individuals with preexisting IBD showed significantly shorter TTimDC than those in the non-IBD group (1-year imDC-free rate 67% vs 93%; HR 7.59, 95% CI 3.00 to 19.15, p<0.0001). Eleven (36%) from the IBD cohort experienced imDC events; none led to life-threatening conditions needing surgical interventions or death. Corticosteroids or biologics were needed in 8/11 (73%) patients, and discontinuation of therapy improved imDC in the remaining three. Half of patients required hospitalization. In contrast, no significant difference in overall survival was observed between IBD and non-IBD cohorts (HR 0.89, 95% CI 0.54 to 1.48). Both groups had overall comparable rates of other non-imDC immune-related adverse events.

Conclusion

Patients with preexisting IBD had worse time-to-imDC than non-IBD matched controls, yet did not exhibit worse overall survival. While close monitoring of patients with preexisting IBD is warranted while on immunotherapy, this comorbidity should not preclude ICI therapy if clinically required.

Distribution of mucosal PD-1 expressing T cells in patients with colitis of different etiologies

BACKGROUND

Immunotherapy, targeting programmed death-1 (PD-1) enhances antitumor T-cell activity in patients with malignancies. Blocking PD-1 or its ligand may lead to fulminant colitis as serious adverse event in these patients. Since little is known of the presence and role of PD-1⁺T cells in colitis of different etiologies, we determined PD-1⁺T cells in mucosal specimens of patients with inflammatory bowel disease, infectious colitis (InfC), immunotherapy-related colitis (ImC) and healthy controls (HC).

METHODS

Newly diagnosed patients with ulcerative colitis (UC, n = 73), Crohn's disease (CD, n = 50), InfC (n = 5), ImC (n = 8) and HC (n = 8) were included. Baseline inflamed colonic biopsies were studied with immunohistochemistry and flowcytometry.

RESULTS

Using immunohistochemistry, PD-1 was not present on lymphocytes in the epithelium of all patients, nor in HC. The percentage PD-1⁺ of all lymphocytes in the lamina propria was 40% in UC, 5% in InfC, 3% in ImC and 0% in HC. Flowcytometry showed significant higher percentages of PD-1⁺T cells in inflamed biopsy specimens of UC patients (22%) compared to all other groups: CD patients (13%), InfC (12%), ImC (5%) and HC (6%).

CONCLUSION

There are relevant differences in distribution and frequencies of mucosal PD-1⁺ T-cell subsets in patients with UC, CD, InfC and ImC, supporting the hypothesis that these types of colitis are driven by different immunological pathways. The increased numbers of PD-1⁺ and PD-L1⁺ lymphocytes in the colonic mucosa of UC patients suggest that the PD-1/PD-L1 pathway might be more activated in UC than in CD.

Role of PD-L1 in Gut Mucosa Tolerance and Chronic Inflammation

The gastrointestinal (GI) mucosa is among the most complex systems in the body. It has a diverse commensal microbiome challenged continuously by food and microbial components while delivering essential nutrients and defending against pathogens. For these reasons, regulatory cells and receptors are likely to play a central role in maintaining the gut mucosal homeostasis. Recent lessons from cancer immunotherapy point out the critical role of the B7 negative co-stimulator PD-L1 in mucosal homeostasis. In this review, we summarize the current knowledge supporting the critical role of PD-L1 in gastrointestinal mucosal tolerance and how abnormalities in its expression and signaling contribute to gut inflammation and cancers. Abnormal expression of PD-L1 and/or the PD-1/PD-L1 signaling pathways have been observed in the pathology of the GI tract. We also discuss the current gap in our knowledge with regards to PD-L1 signaling in the GI tract under homeostasis and pathology. Finally, we summarize the current understanding of how this pathway is currently targeted to develop novel therapeutic approaches.