Introduction

SARS-CoV-2 exhibits an extra-pulmonary tropism, with up to 70% of COVID-19 patients experiencing at least one gastrointestinal (GI) symptom. Persistent viral presence has been observed in intestinal biopsies months after the virus has been cleared from the respiratory tract, which has been implicated in the development of long COVID symptoms. Despite these observations, the dynamics of SARS-CoV-2 infection within the intestine, as well as its potential to act as a viral reservoir and source of ongoing pathogenesis, remain largely unknown.

Aims & Methods

We recently established a robust mouse model to study the dynamics of intestinal SARS-CoV-2 infection by exposing the distal ileum of mice through ventral laparotomy and administering the virus directly into the lumen.

Results

In wild-type (WT) C57Bl/6 mice, after perfusion, viral RNA was detected throughout the GI tract at 7 days post infection (dpi), not only at the site of initial infection, but also in other regions such as the esophagus, stomach, duodenum, jejunum, colon, and rectum. Moreover, viral RNA was also found in extra-intestinal sites, including the salivary gland, liver, and brain. In Stat1^-/- mice with impaired type I, II, and III interferon signaling, the levels of viral RNA as well as nucleocapsid antigens in the GI tract were 10 to 100 times higher than those in WT mice. Virus also successfully disseminated to systemic organs such as the heart, lung, kidney, brain, and spleen. Viral shedding in feces was observed from 3 to 7 dpi in Stat1^-/- mice but not WT mice. Notably, rapid secretory diarrhea was observed in these mice, marking the first instance of diarrhea induced by SARS-CoV-2 infection in a mouse model. Additional studies are ongoing to further characterize these findings, including the assessment of the timing of viral replication, titration of infectious viruses, detailed histological analysis, and immunological profiling.

Conclusion

These results emphasize the usefulness of this mouse model in exploring the mechanisms underlying the impact of SARS-CoV-2 on the intestines locally and systemically. The study also underscores the critical role of interferon signaling in restricting intra-intestinal replication and preventing the virus from spreading to other organs. This has important clinical implications, particularly for individuals taking JAK inhibitor medications, which could affect the interferon response and potentially increase susceptibility to more severe outcomes from SARS-CoV-2 infection.

Disclosure

M.S.D. is a consultant for Inbios, Vir Biotechnology, Ocugen, Topspin Therapeutics, GlaxoSmithKline, Moderna, and Immunome. The Diamond laboratory has received unrelated funding support in sponsored research agreements from Vir Biotechnology, Emergent BioSolutions, and Moderna.

Clinical Case Summary

Introduction: Ulcerative colitis (UC) is a chronic inflammatory disease characterized by remitting and relapsing patterns, necessitating multifaceted therapeutic interventions, among which mesalazine, or 5-aminosalicylic acid (5-ASA), is prominently utilized. Despite its typically favorable tolerability profile, mesalazine may occasionally precipitate severe adverse events, such as myocarditis.
Case presentation: A 46-year-old male recently diagnosed with UC presented with a moderate UC flare-up and was initiated on 5-ASA therapy upon admission.
Within a span of two days following initiation of oral therapy, he developed acute chest pain, palpitations, dyspnea, and desaturation, necessitating intensive care due to cardiogenic shock.
Paraclinical assessments revealed elevated troponin levels, along with electrocardiographic and echocardiographic abnormalities, including left ventricular dysfunction and reduced ejection fraction.
Discontinuation of mesalazine resulted in symptom improvement and reduction of cardiac markers. Subsequent evaluations demonstrated a recovery in cardiac function, establishing a causal relationship between myocarditis and the administration of 5-ASA. Consequently, a therapeutic switch to mercaptopurine was instituted.
Conclusion: This case underscores the infrequent yet significant hazard of mesalazine-triggered myocarditis, emphasizing the critical necessity for vigilant patient monitoring during this therapy and prompt consideration of alternative therapeutic options in the presence of severe cardiac complications.

Introduction

Despite approval of several therapeutic approaches for the treatment of IBD, current treatments do not extend clinical response beyond the 40% ‘therapeutic ceiling’ and many patients do not achieve clinical remission.
The aryl hydrocarbon receptor (AhR) is a cytosolic ligand-dependent transcription factor that is expressed in many cell types. Activation of the receptor regulates many pathophysiological functions, including immune homeostasis and barrier integrity. AQ312 is a potent and selective AhR agonist undergoing preclinical development for the treatment of IBD.

Aims & Methods

The aim of the work was to determine the potency of AQ312 and evaluate the effects of AQ312 in preclinical animal models of IBD.
Cellular potency of AQ312 was determined using the human, mouse and rat AhR/ARNT reporter gene assay and compared to reference AhR agonists (Indigo Biosciences). The pharmacokinetics of AQ312 were measured in rats after acute administration (P.O.). Acute colitis was induced in C57Bl/6 mice by administration of DSS in the drinking water. Chronic colitis was induced in SCID mice by transfer of CD4+ T cells obtained from spleens of Balb/c mice. AQ312 was administered perorally (P.O.) at 1mg/kg, daily (d-7 to d9 in DSS and d0-d48 T cell transfer). Body weight was monitored throughout the study whilst colon weight and length, and inflammatory cells (flow cytometry) and cytokines (Luminex) in the colon were determined at necropsy. In addition, expression of cytochrome P450 1A1 (CYP1A1) was determined in colon tissue by RT-PCR to demonstrate AhR activation.

Results

AQ312 was a selective and potent activator of AhR, with similar potency for human, mouse and rat receptors (EC50 of 4.3, 2.1 and 3.9nM respectively). In rats, a single dose of AQ312 was rapidly cleared (T_0.5=1h) with little systemic exposure after 4h. Induction of acute or chronic experimental colitis in mice led to marked colon edema, immune cell infiltration and increased production of inflammatory cytokines. These effects were significantly reduced after per oral treatment with AQ312.

Conclusion

AQ312 is a potent and selective small molecule AhR agonist that is rapidly cleared in rodents. The molecule has demonstrated therapeutic benefit in 2 models of experimental colitis. AQ312 has the potential to be the ‘best in class’ AhR agonist for the treatment of IBD.

Introduction

Inflammatory Bowel Diseases (IBD) are chronic inflammatory disorders characterized by alterations of acute relapses and remission. The past decades have brought substantial advances in the pharmacological management of IBD by a wide range of medicines. However, the sustained efficacy of the currently available anti-inflammatory therapies is still far from optimal. Therefore, the development of novel therapies represents a major unmet clinical need in this field. Recently, the enrichment of the coagulation pathway genes and among these, Plasminogen activator inhibitor 1 (PAI-1) was described in IBD, whereas PAI-1 emerged as a link between the epithelium and inflammation. Moreover, the genetic deletion of PAI-1 prevented the severity of experimental colitis in mice.

Aims & Methods

Based on these, we aimed to develop and test novel PAI-1 inhibitors for the treatment of IBD.
The novel, amino acid-based PAI-1 inhibitor, LDN-071 was synthesized by the A³SMO^® platform. The inhibitory potential and cytotoxicity effects of the peptide were determined by in vitro assays. Acute and chronic colitis was induced in mice with DSS and 10 mg/bwkg LDN-071 was administered per os. The changes of body weight, spleen weight, and colon length were measured. Haematoxylin eosin (HE) and Periodic acid-Schiff (PAS) staining were performed for histology. ELISA and qRT-PCR measurements were applied to analyze the cytokine expressions. Hydroxyproline assay was used to quantify the mucosal collagen deposition. In vivo, the toxicity of LDN-071 was determined in mice. Human colon organoid and fibroblast (FB) cell cultures were generated from IBD patients and the effects of LDN-071 were observed.

Results

LDN-071 significantly inhibited PAI-1 in vitro without decreasing the cell viability in a concentration range of 1µM-1mM. In the acute mice model, the administration of 10 mg/bwkg LDN-071 in the DSS-treated mice prevented the body weight loss, the development of bloody diarrhea, the decrease of colon length, and the increase of the spleen weight, which were displayed by the DSS+vehicle-treated animals. The histological analysis of the colon revealed that DSS treatment induced severe transmural inflammation, ulceration, loss of crypt structures, and goblet cell depletion. Importantly, all these parameters were significantly ameliorated by the administration of 10 mg/bwkg LDN-071 in the acute and chronic models as well. Additionally, mucosal gene and protein expressions of TNF-α, IL-1β, and IL-6 were significantly decreased by PAI-1 inhibition in the acute phase. Besides, the LDN-071 treatment significantly reduced the inflammation, epithelial erosion, and fibrosis caused by chronic administration of DSS. However, the collagen deposition was significantly lower in the PAI-1-inhibited DSS mice. Importantly, no signs of toxicity were observed in mice exposed to 100 mg/bwkg LDN-071 for 7 days. In our in vitro models, the PAI-1 inhibition reduced the protein level and gene expression of pro-inflammatory cytokines in human colon organoid of IBD patient. Moreover, the gene expression of fibrosis-related genes significantly decreased after the LDN-071 treatment in IBD patients-derived human FB cell culture.

Conclusion

Our results showed that LDN-071, a novel amino acid-based inhibitor of PAI-1, significantly ameliorated the severity of acute and chronic colitis in mice. However, the LDN-071 reduced the expression of inflammation- and fibrosis-related genes and proteins in vitro human models. We propose that the inhibition of PAI-1 could be a potential novel therapeutic strategy in IBD.

Disclosure

LDN-071 PAI-1 inhibitor is owned by Ladon Therapeutics Ltd.

Introduction

Maintaining the mucus layer is crucial in the innate immune system, and MCU2 is a significant component of the mucus layer in the intestinal tract. Urolithin A (Uro A) is a gut microbiota-derived metabolite from ellagic acid, commonly found in pomegranates and raspberries. Recently, it has been described that the administration of Uro A enhances barrier function via the tight junction. However, the intestinal protective effect via mucin production has yet to be elucidated.

Aims & Methods

This study aimed to elucidate the effect of Uro A on mucin synthesis in the colon and to investigate the underlying molecular mechanisms. First, in vivo experiments were performed using wild-type mice (C57BL/6), NF-E2-related factor 2 (Nrf2) deficient mice, and wild-type mice treated with an aryl hydrocarbon receptor (AhR) antagonist. After Uro A administration, gut microbiota composition was analyzed, and short-chain fatty acid concentration was also measured. Next, in vitro assays using mucin-producing cells (LS174T) were conducted to assess mucus production upon Uro A treatment.

Results

The thickness of the MUC2-positive mucus layer in the Uro A group was significantly increased compared with that in the control group (p<0.01). MUC2 protein levels in the colonic mucosal epithelium were significantly higher in the Uro A group than in the control group (p=0.041). In Nrf2 deficient mice, Uro A treatment did not increase MUC2 protein levels in the colonic epithelium (p=0.309). Similarly, in mice treated intraperitoneally with an AhR antagonist, MUC2 protein levels did not increase in the colonic epithelium after treatment with Uro A (p=0.222). In experiments using Fluorescein isothiocyanate- Dextran, Uro A administration suppressed the mucosal permeability. Meanwhile, Uro A administration did not significantly upregulate tight junction protein expression in the epithelium. Hence, increased intestinal mucus appears to suppress leaky gut by a mechanism distinct from upregulating tight junction protein. After the treatment with Uro A, short-chain fatty acid-producing bacteria such as family S24_7, and genus Ruminococcus significantly increased. In addition, the propionic acid concentrations in stools were significantly increased after UroA administration. The treatment of Uro A was also beneficial for dextran sulfate sodium (DSS)-induced colitis in the mice model. The Uro A group showed a marked reduction in the disease activity index (DAI) after DSS administration (p=0.033), and in the control group, the intestinal length was significantly shortened (p=0.018). Hematoxylin and eosin staining of tissue sections showed that inflammatory cell infiltration and destruction of gland duct structures were mild in the Uro A group. In vitro data using LS174T cells demonstrated that the MUC2 mRNA level and the MUC2 protein levels in LS174T cells significantly increased after Uro A administration (p=0.02 and p<0.01, respectively). Fluorescence immunostaining showed that the strength of MUC2 fluorescence in LS174T cells after treatment with Uro A was significantly higher than that in the control group. In addition, MUC2 fluorescence expression did not increase after treatment with an Nrf 2 inhibitor. Similarly, MUC2 fluorescence did not increase after treatment with AhR antagonist.

Conclusion

Uro A promoted the up-regulation of MUC2 synthesis through the AhR and Nrf2 pathway, leading to the enhancement of the mucosal barrier function and the inhibition of the development of murine colitis. These findings involve alternating the intestinal microbiota and SCFA.

Disclosure

Tomohisa Takagi received collaborative research funds from Mitsubishi Tanabe Pharma Corporation and PreMedica, Inc. Yuji Naito received scholarship funds from EA Pharma Co., Ltd.; a collaboration research fund from Taiyo Kagaku Co., Ltd.

Introduction

High-risk human papillomavirus (hr-HPV) has been associated with a subset of Barrett’s dysplasia (BD) and oesophageal adenocarcinoma (OAC).^1,2,3,4 The L1 major capsid protein has been closely linked to disease regression and is a prognostic factor in HPV driven cancers of the cervix and anus.​^5,6​​​​ The progression of cervical intraepithelial neoplasia to invasive cancer is accompanied by a loss of viral L1 capsid protein expression.

Aims & Methods

Thus, in a retrospective, cross-sectional study, we investigated L1 protein expression in HPV-positive patients representing the oesophageal squamous (controls) [Group1]-Barrett’s metaplasia [Group 2]-low-grade dysplasia [Group 3]-high-grade dysplasia [Group 4]-adenocarcinoma [Group 5] sequence. L1 protein immuno-histochemical staining was correlated with p16 overexpression and E6/E7 mRNA in-situ hybridization. The association between the 5 patient groupings and L1 expression was analysed using the Chi-square test. Multivariable logistic regression was undertaken to investigate the above association with adjustment of potential confounders (age, gender, BMI, ever smoked and excess alcohol). Adjusted odds ratio (95% CI) was calculated.​​​​​

Results

^​​​​​​Of 116 HPV DNA-positive patients [(age range: 19-90, mean (SD), 63.2 (13.5)], 88 males and 28 females), 73 (62.9%) were genotype 16, 37 (31.9%) genotype 18 and 6 (5.2%) were genotype 6. L1 nuclear staining was observed in 64 individuals. L1 expression was detected in 84.9% (28/33) of controls; 94.1% (16/17) of BO patients; 50% (7/14) of LGD subjects; 38.1% (8/21) of HGD individuals and 16.1% (5/31) of OAC patients; [adjusted P < 0.0001]. Conversely, p16 was present in 9.1% (3/33) of controls, 17.7% of BO (3/17), 57.1% (8/14) in LGD individuals, 61.9% (13/21) of HGD patients and 64.5% (20/31) of OAC subjects [p<0.0001]. Corresponding figures for E6/E7 mRNA positivity was 6.1% (2/33), 23.5% (4/17), 28.6% (4/14), 38.1% (8/21) and 45.2% (14/31) respectively [p=0.008]. Expression of HPV-L1 and p16 or L1 and E6/E7 mRNA was largely mutually exclusive.

Conclusion

HPV L1 capsid expression is incrementally lost with increasing oesophageal disease severity as in viral driven anal and cervical lesions. Utility of L1 alone or in combination with p16/E6/E7 mRNA in stratifying HPV-positive oesophageal lesions for treatment should be further explored.

References

1. Rajendra S, Wang B, Snow ET, et al. Transcriptionally active human papillomavirus is strongly associated with Barrett’s dysplasia and esophageal adenocarcinoma. Am J Gastroenterol 2013;108:1082–1093.
2. Rajendra S, Yang T, Xuan W, et al. Active human papillomavirus involvement in Barrett's dysplasia and oesophageal adenocarcinoma is characterized by wild-type p53 and aberrations of the retinoblastoma protein pathway. Int J Cancer. 2017;141(10):2037-2049.
3. Li X, Gao C, Yang Y, et al. Systematic review with meta-analysis: the association between human papillomavirus infection and oesophageal cancer. Aliment Pharmacol Ther. 2014;39(3):270-281.
4. Rajendra, S., W. Xuan, N. Merrett, et al. Survival Rates for Patients With Barrett High-grade Dysplasia and Esophageal Adenocarcinoma With or Without Human Papillomavirus Infection. JAMA Netw Open. 2018; 1: e181054.
5. Choi YS, Kang WD, Kim SM, et al. Human papillomavirus L1 capsid protein and human papillomavirus type 16 as prognostic markers in cervical intraepithelial neoplasia 1. Int J Gynecol Cancer 2010;20(2):288-293.
6. Hernandez J, Elahi A, Siegel E, Coppola D, Riggs B, Shibata D. HPV L1 capsid protein detection and progression of anal squamous neoplasia Am J Clin Pathol 2011; 135: 436-41.

Disclosure

None

Introduction

Eosinophilic esophagitis (EoE) is treated with oral antacids, steroid-swallowing therapy, and antigen elimination diet. Despite treatment, EoE often recurs, and the mechanism has not been elucidated. Recently, pathogenic helper Th2 (Tpath2) cell was reported to be responsible for chronic eosinophilic inflammation, for example asthma and eosinophilic chronic rhinosinusitis, by producing large amount of Th2 cytokine [1]. Our previous research has identified the presence of Tpath2 cells in the esophageal mucosa of patients with EoE [2]. However, there has been no previous report whether Tpath2 remains in the tissues during remission or after treatment.

Aims & Methods

The aim of this study was to examine the association between the progression of EoE and Tpath2 cells in the esophageal mucosa. We collected esophageal mucosa biopsies regardless of the endoscopic findings from 11 patients (generally 2 specimens from 5cm and 15cm oral side of esophagogastric junction respectively) previously diagnosed as EoE. Flow cytometry was utilized to quantify the frequency of eosinophils and Tpath2 cells in these samples. Each patient’s medical history or disease course were also reviewed.

Results

Of the 11 patients, 6 (54.5%) were in remission from EoE and 5 (45.5%) had active disease. Notably, abnormal frequency of Tpath2 cells within the esophageal mucosa of the patients in remission (median 1.41%, range 0.31 - 2.85%) were observed to the same levels in those with active disease (median 2.48%, range 1.02 - 4.18%) (P=0.33. Mann-Whitney test.). In remission cases, the median period from confirmation of remission to this biopsy was 38 months (range 24 - 49) , meaning T path2 cells still remained at least for that period after remission. Among patients in remission at the time of biopsy, two patients who were absence of treatment relapsed EoE during subsequent disease course.

Conclusion

Tpath2 cells remain within the esophageal mucosa of patients with EoE for a relatively long time regardless of eosinophil control. Although further investigation is needed, some cases of EoE recurred during remission phase, suggesting that Tpath2 cells may also be involved in the recurrence.

References

1. Nakayama T et al. Th2 cells in health and disease. Annu Rev Immunol. 2017; 35:53-84.
2. Kaneko T et al. Amphiregulin-producing T helper 2 cells facilitate esophageal fibrosis of eosinophilic esophagitis. J Allergy Clin Immunol Global. 2024; Epub ahead of print