GPR4 Knockout Attenuates Intestinal Inflammation and Forestalls the Development of Colitis-Associated Colorectal Cancer in Murine Models

GPR4 is a proton-sensing G protein-coupled receptor highly expressed in vascular endothelial cells and has been shown to potentiate intestinal inflammation in murine colitis models. Herein, we evaluated the proinflammatory role of GPR4 in the development of colitis-associated colorectal cancer (CAC) using the dextran sulfate sodium (DSS) and azoxymethane (AOM) mouse models in wild-type and GPR4 knockout mice. We found that GPR4 contributed to chronic intestinal inflammation and heightened DSS/AOM-induced intestinal tumor burden. Tumor blood vessel density was markedly reduced in mice deficient in GPR4, which correlated with increased tumor necrosis and reduced tumor cell proliferation. These data demonstrate that GPR4 ablation alleviates intestinal inflammation and reduces tumor angiogenesis, development, and progression in the AOM/DSS mouse model.

Increased interleukin-6/C-reactive protein levels are associated with the upregulation of the adenosine pathway and serve as potential markers of therapeutic resistance to immune checkpoint inhibitor-based therapies in non-small cell lung cancer

BACKGROUND

Systemic immune activation, hallmarked by C-reactive protein (CRP) and interleukin-6 (IL-6), can modulate antitumor immune responses. In this study, we evaluated the role of IL-6 and CRP in the stratification of patients with non-small cell lung cancer (NSCLC) treated with immune checkpoint inhibitors (ICIs). We also interrogated the underlying immunosuppressive mechanisms driven by the IL-6/CRP axis.

METHODS

In cohort A (n=308), we estimated the association of baseline CRP with objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) in patients with NSCLC treated with ICIs alone or with chemo-immunotherapy (Chemo-ICI). Baseline tumor bulk RNA sequencing (RNA-seq) of lung adenocarcinomas (LUADs) treated with pembrolizumab (cohort B, n=59) was used to evaluate differential expression of purine metabolism, as well as correlate IL-6 expression with PFS. CODEFACS approach was applied to deconvolve cohort B to characterize the tumor microenvironment by reconstructing the cell-type-specific transcriptome from bulk expression. Using the LUAD cohort from The Cancer Genome Atlas (TCGA) we explored the correlation between IL-6 expression and adenosine gene signatures. In a third cohort (cohort C, n=18), plasma concentrations of CRP, adenosine 2a receptor (A2aR), and IL-6 were measured using ELISA.

RESULTS

In cohort A, 67.2% of patients had a baseline CRP≥10 mg/L (CRP-H). Patients with CRP-H achieved shorter OS (8.6 vs 14.8 months; p=0.006), shorter PFS (3.3 vs 6.6 months; p=0.013), and lower ORR (24.7% vs 46.3%; p=0.015). After adjusting for relevant clinical variables, CRP-H was confirmed as an independent predictor of increased risk of death (HR 1.51, 95% CI: 1.09 to 2.11) and lower probability of achieving disease response (OR 0.34, 95% CI: 0.13 to 0.89). In cohort B, RNA-seq analysis demonstrated higher IL-6 expression on tumor cells of non-responders, along with a shorter PFS (p<0.05) and enrichment of the purinergic pathway. Within the TCGA LUAD cohort, tumor IL-6 expression strongly correlated with the adenosine signature (R=0.65; p<2.2e-16). Plasma analysis in cohort C demonstrated that CRP-H patients had a greater median baseline level of A2aR (6.0 ng/mL vs 1.3 ng/mL; p=0.01).

CONCLUSIONS

This study demonstrates CRP as a readily available blood-based prognostic biomarker in ICI-treated NSCLC. Additionally, we elucidate a potential link of the CRP/IL-6 axis with the immunosuppressive adenosine signature pathway that could drive inferior outcomes to ICIs in NSCLC and also offer novel therapeutic avenues.

Transwell In Vitro Cell Migration and Invasion Assays

Cell migration and invasion have essential roles in both normal physiology and disease. As such, methodologies to assess cell migratory and invasive capacities are necessary to elucidate normal cell processes and underlying mechanisms of disease. Here, we describe commonly used transwell in vitro methods for the study of cell migration and invasion. The transwell migration assay involves the chemotaxis of cells through a porous membrane after the establishment of a chemoattractant gradient using two medium-filled compartments. The transwell invasion assay involves the addition of an extracellular matrix on top of the porous membrane which only permits chemotaxis of cells which possess invasive properties such as tumor cells.

Case Report: Peripheral blood T cells and inflammatory molecules in lung cancer patients with immune checkpoint inhibitor-induced thyroid dysfunction: Case studies and literature review

Immunotherapy has changed the paradigm of cancer treatment, yet immune checkpoint inhibitors (ICIs) such as PD-1/PD-L1 monoclonal antibodies may cause immune-related adverse events (irAEs) in some patients. In this report, two non-small cell lung cancer (NSCLC) patients treated with nivolumab presented with checkpoint inhibitor-induced thyroid dysfunction (CITD), followed by a second irAE of pneumonitis and intestinal perforation, respectively. Increases in peripheral CD8⁺ T cells correlated with the onset of CITD in the patients. Intriguingly, common inflammatory biomarkers, including C-reactive protein (CRP) and neutrophil/lymphocyte ratio (NLR), were not consistently increased during the onset of CITD but were substantially increased during the onset of pneumonitis and intestinal perforation irAEs. The observations suggest that unlike other irAEs such as pneumonitis, CRP levels and NLR were non-contributory in diagnosing CITD, whereas T cell expansion may be associated with immunotherapy-induced thyroiditis.

Abstract 6139: GPR4 promotes the development of colitis-associated colorectal cancer in an experimental mouse model

GPR4 is a proton-sensing G protein-coupled receptor expressed in endothelial cells as well as other cell types. Endothelial cell adhesion, blood vessel permeability, leukocyte infiltration, and angiogenesis are regulated by the proinflammatory functions of GPR4. Inhibition of GPR4 ameliorates inflammatory bowel disease (IBD) in mouse models. GPR4 expression is upregulated in the intestinal tissues of IBD and colorectal cancer patients and is associated with a worse prognosis. Herein, we studied the role of GPR4 in colitis-associated colorectal cancer (CAC) by inducing CAC in GPR4 knockout (KO) and wild-type (WT) mice using azoxymethane (AOM)/dextran sulfate sodium (DSS). The severity of CAC development was higher in WT mice than GPR4 KO mice when treated with AOM/DSS. Blood vessel density was significantly higher within the tumors of WT mouse colons compared to GPR4 KO mice. GPR4 KO tumors showed a significant increase in tumor necrosis in comparison to WT tumors. Fecal blood/diarrhea score, colon shortening, and mesenteric lymph node size were aggravated in WT mice compared to GPR4 KO mice treated with AOM/DSS. Our data demonstrate that GPR4 increases intestinal inflammation and angiogenesis, enhancing tumor development in the CAC mouse model, suggesting that GPR4 inhibition may reduce the risk of developing colitis-associated colorectal cancer.

Citation Format: Mona A. Marie. GPR4 promotes the development of colitis-associated colorectal cancer in an experimental mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6139.

Abstract 1667: A pilot study correlating baseline plasma levels of adenosine 2A receptor (A2aR) with acute phase reactants in advanced non-small cell lung cancer (NSCLC) patients treated with immune-checkpoint inhibitors

Background: Acute-phase reactants, such as C-reactive protein (CRP) and IL-6, can modulate immune suppression within the tumor microenvironment (TME) and thus potentially result in inferior outcomes to immune checkpoint inhibitors (ICIs). Immunosuppression within the TME is also be mediated by tumoral adenosine production, via hypoxia-induced exonuclease activity of CD39 and CD73 and adenosine 2a receptor (A2aR) signaling. We sought to evaluate whether plasma levels of A2aR correlate with the acute phase reactants (CRP and IL-6) in advanced NSCLC patients treated with ICIs.

Methods: Between December 2016 and April 2019, we enrolled 18 patients with advanced NSCLC treated with single-agent ICIs or in combination with chemotherapy. We isolated plasma samples from patients before ICI initiation and again after each treatment. Plasma concentrations of A2aR and IL-6 were measured using ELISA. The baseline level of CRP was obtained from peripheral blood at ICI initiation (± 3 days). Previous studies correlating CRP and cancer outcomes defined a C-reactive protein (CRP) cutoff of 10 mg/L to define normal (CRP-N) and high CRP (CRP-H) levels. We assessed the relationship between CRP, IL-6, and A2aR plasma levels. Statistical analyses were performed using the Mann-Whitney test and linear regression analysis.

Results: At the initiation of ICI, the median age of the cohort was 63. Two patients had stage III disease and 16 patients had stage IV disease. Four had squamous cell carcinoma, and 14 had non-squamous cell carcinoma. Six patients were treated with concomitant chemotherapy (pembrolizumab with carboplatin and pemetrexed). Patients received a median of 4 ICI cycles (range: 1-8 cycles) in our study. In the cohort, the median baseline levels of CRP, IL-6, and A2aR were 16.9 mg/L, 5.1 pg/mL, and 3.6 ng/mL, respectively. A positive correlation was present between baseline CRP levels and IL-6 plasma levels (R=0.76; p=0.003). Seven patients were CRP-N, and 11 patients were CRP-H. CRP-H patients had a greater median baseline level of A2aR (6.0 ng/mL vs. 1.3 ng/mL; p=0.01). Likewise, patients with baseline IL-6 levels greater than 5 pg/mL had a higher median baseline level of A2aR (6.0 ng/mL vs. 1.3 ng/mL; p=0.02).

Conclusions: In a small, heterogeneous cohort of advanced NSCLC patients treated with ICIs, we demonstrate that elevated baseline levels of acute-phase reactants (CRP and IL-6) potentially act as an indirect surrogate for high plasma A2aR levels. Validation from larger studies is required to understand the biomarker implications of these findings in determining outcomes to ICIs.

J.D.M. and A.R.N contributed equally to this work.

Citation Format: Justin D. McCallen, Abdul R. Naqash, Mona A. Marie, Nitika Sharma, Mahvish Muzaffar, Paul R. Walker, Li Yang. A pilot study correlating baseline plasma levels of adenosine 2A receptor (A2aR) with acute phase reactants in advanced non-small cell lung cancer (NSCLC) patients treated with immune-checkpoint inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1667.

Can GPR4 Be a Potential Therapeutic Target for COVID-19?

Coronavirus disease 19 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), first emerged in late 2019 and has since rapidly become a global pandemic. SARS-CoV-2 infection causes damages to the lung and other organs. The clinical manifestations of COVID-19 range widely from asymptomatic infection, mild respiratory illness to severe pneumonia with respiratory failure and death. Autopsy studies demonstrate that diffuse alveolar damage, inflammatory cell infiltration, edema, proteinaceous exudates, and vascular thromboembolism in the lung as well as extrapulmonary injuries in other organs represent key pathological findings. Herein, we hypothesize that GPR4 plays an integral role in COVID-19 pathophysiology and is a potential therapeutic target for the treatment of COVID-19. GPR4 is a pro-inflammatory G protein-coupled receptor (GPCR) highly expressed in vascular endothelial cells and serves as a "gatekeeper" to regulate endothelium-blood cell interaction and leukocyte infiltration. GPR4 also regulates vascular permeability and tissue edema under inflammatory conditions. Therefore, we hypothesize that GPR4 antagonism can potentially be exploited to mitigate the hyper-inflammatory response, vessel hyper-permeability, pulmonary edema, exudate formation, vascular thromboembolism and tissue injury associated with COVID-19.

The Proton-Sensing GPR4 Receptor Regulates Paracellular Gap Formation and Permeability of Vascular Endothelial Cells

GPR4 is a pH-sensing G protein-coupled receptor highly expressed in vascular endothelial cells and can be activated by protons in the inflamed tissue microenvironment. Herein, we report that acidosis-induced GPR4 activation increases paracellular gap formation and permeability of vascular endothelial cells through the G_α12/13/Rho GTPase signaling pathway. Evaluation of GPR4 in the inflammatory response using the acute hindlimb ischemia-reperfusion mouse model revealed that GPR4 mediates tissue edema, inflammatory exudate formation, endothelial adhesion molecule expression, and leukocyte infiltration in the inflamed tissue. Genetic knockout and pharmacologic inhibition of GPR4 alleviate tissue inflammation. These results suggest GPR4 is a pro-inflammatory receptor and could be targeted for therapeutic intervention.

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Acidosis/GPR4 regulates endothelial paracellular gap formation and permeability

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GPR4 exacerbates inflammation by increasing tissue edema and leukocyte infiltration

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Pharmacological inhibition of GPR4 reduces inflammatory responses

Isolated neutropenia as a rare but serious adverse event secondary to immune checkpoint inhibition

BACKGROUND

Compared to conventional chemotherapy, Immune checkpoint inhibitors (ICI) are known to have a distinct toxicity profile commonly identified as immune-related adverse events (irAEs). These irAEs that are believed to be related to immune dysregulations triggered by ICI can be serious and lead to treatment interruptions and in severe cases, precipitate permanent discontinuation. Isolated neutropenia secondary to ICI has been rarely documented in the literature and needs further description. We report a case of pembrolizumab related severe isolated neutropenia in a patient with metastatic non-small cell lung cancer. We were also able to obtain serial blood and plasma-based biomarkers for this patient during treatment and during neutropenia to understand trends that may correlate with the irAE. In addition we summarize important findings from other studies reporting on ICI related neutropenia.

CASE PRESENTATION

A 74 years old Caucasian male treated with single-agent pembrolizumab for metastatic non-small cell lung cancer presented with fevers, chills, and an isolated neutrophil count (ANC) of 0 2 weeks after the fourth dose. In addition to antibiotics, due to the strong suspicion of this neutropenia being immune-mediated, he was started on 1 mg/kg of steroids and also received filgrastim to accelerate neutrophil recovery. Serial trends in C-reactive protein and certain other inflammatory cytokines demonstrated a corresponding rise at the time of neutropenia. Post recovery, his pembrolizumab was kept on hold. Eight weeks later he had a second episode of neutropenia which was again managed similar to the first episode. Despite permanent discontinuation of ICI after the first neutropenia, his disease showed an ongoing complete metabolic response on imaging. Our literature review reveals that hematological toxicities constitute < 1% irAEs with isolated neutropenia roughly accounting for one-fourth of the hematological irAEs. Based on the handful of ICI related neutropenia cases reported to date, we identified nivolumab to be the most common offender. The median number of ICI cycles administered before presenting with neutropenia was three, and the median time to recovery was approximately two weeks. All of these neutropenic episodes were ≥ grade 3 and led to permanent ICI discontinuation. Using immunosuppressive therapies in conjunction with granulocyte-colony stimulating factor was the most common strategy described to have favorable results.

CONCLUSION

Neutropenia as an isolated irAE secondary to ICI is rare but represents a severe toxicity that needs early recognition and can often result in treatment discontinuations. Careful monitoring of these patients with the prompt initiation of immunosuppressive and supportive measures to promote rapid recovery as well as prevent and treat infectious complications should be part of the management algorithms. Serial monitoring of blood and plasma-based biomarkers from more extensive studies may help in identifying patients at risk for irAEs and thus guide patient selection for ICI.

Novel mechanism of cannabidiol-induced apoptosis in breast cancer cell lines

Studies have emphasized an antineoplastic effect of the non-psychoactive, phyto-cannabinoid, Cannabidiol (CBD). However, the molecular mechanism underlying its antitumor activity is not fully elucidated. Herein, we have examined the effect of CBD on two different human breast cancer cell lines: the ER-positive, well differentiated, T-47D and the triple negative, poor differentiated, MDA-MB-231 cells. In both cell lines, CBD inhibited cell survival and induced apoptosis in a dose dependent manner as observed by MTT assay, morphological changes, DNA fragmentation and ELISA apoptosis assay. CBD-induced apoptosis was accompanied by down-regulation of mTOR, cyclin D1 and up-regulation and localization of PPARγ protein expression in the nuclei and cytoplasmic of the tested cells. The results suggest that CBD treatment induces an interplay among PPARγ, mTOR and cyclin D1 in favor of apoptosis induction in both ER-positive and triple negative breast cancer cells, proposing CBD as a useful treatment for different breast cancer subtypes.

Urinary CXCL10: a marker of nephritis in lupus patients

Systemic lupus erythematosus (SLE) is a connective tissue disease characterized by the formation of autoantibodies and immune complexes. Lupus nephritis is one of the hallmark features of SLE. CXCL10 is a chemokine secreted by IFNg- stimulated endothelial cells and has been shown to be involved in the pathological processes of autoimmune diseases. The objective was to measure urinary CXCL10 in SLE patients, to compare levels between nephritis and non-nephritis groups and to study its correlation with other variables. Sixty lupus patients were enrolled in our trial. Thirty patients had lupus nephritis and the other 30 were without evidence of lupus nephritis. Thirty healthy subjects were willing to participate as a healthy control group. Renal biopsy was performed for lupus nephritis group. Urinary CXCL10 was measured using the ELISA technique. Serum creatinine, C3, C4 and 24 h urinary proteins were measured. Lupus activity was assessed using systemic lupus erythematosus disease activity index (SLEDAI) scoring system. Renal activity was measured using renal activity scoring system. CXCL10 was significantly higher in lupus nephritis patients than in lupus patients without nephritis. CXCL10 was significantly correlated with renal activity score, 24 hours urinary proteins and the SLEDAI score. It is highly valid predictor of SLE nephritis with high sensitivity and specificity. CXCL 10 a highly sensitive and specific non-invasive diagnostic tool for lupus nephritis patients.