Characterization of esophageal inflammation in patients with achalasia. A retrospective immunohistochemical study

Focus on Achalasia in the Omics Era

Achalasia is a rare and complex esophageal disease of unknown etiology characterized by difficulty in swallowing due to the lack of opening of the lower esophageal sphincter and the absence of esophageal peristalsis. Recent advancements in technology for analyzing DNA, RNA and biomolecules in high-throughput techniques are offering new opportunities to better understand the etiology and the pathogenetic mechanisms underlying achalasia. Through this narrative review of the scientific literature, we aim to provide a comprehensive assessment of the state-of-the-art knowledge on omics of achalasia, with particular attention to those considered relevant to the pathogenesis of the disease. The notion and importance of the multi-omics approach, its limitations and future directions are also introduced, and it is highlighted how the integration of single omics data will lead to new insights into the development of achalasia and offer clinical tools which will allow early diagnosis and better patient management.

A single-cell transcriptional landscape of immune cells shows disease-specific changes of T cell and macrophage populations in human achalasia

Achalasia is a rare motility disorder of the esophagus caused by the gradual degeneration of myenteric neurons. Immune-mediated ganglionitis has been proposed to underlie the loss of myenteric neurons. Here, we measure the immune cell transcriptional profile of paired lower esophageal sphincter (LES) tissue and blood samples in achalasia and controls using single-cell RNA sequencing (scRNA-seq). In achalasia, we identify a pattern of expanded immune cells and a specific transcriptional phenotype, especially in LES tissue. We show C1QC+ macrophages and tissue-resident memory T cells (TRM), especially ZNF683+ CD8+ TRM and XCL1+ CD4+ TRM, are significantly expanded and localized surrounding the myenteric plexus in the LES tissue of achalasia. C1QC+ macrophages are transcriptionally similar to microglia of the central nervous system and have a neurodegenerative dysfunctional phenotype in achalasia. TRM also expresses transcripts of dysregulated immune responses in achalasia. Moreover, inflammation increases with disease progression since immune cells are more activated in type I compared with type II achalasia. Thus, we profile the immune cell transcriptional landscape and identify C1QC+ macrophages and TRM as disease-associated immune cell subsets in achalasia.

RNA-sequencing reveals molecular and regional differences in the esophageal mucosa of achalasia patients

Achalasia is an esophageal motility disorder characterized by the functional loss of myenteric plexus ganglion cells in the distal esophagus and lower esophageal sphincter. Histological changes have been reported in the esophageal mucosa of achalasia, suggesting its involvement in disease pathogenesis. Despite recent advances in diagnosis, our understanding of achalasia pathogenesis at the molecular level is very limited and gene expression profiling has not been performed. We performed bulk RNA-sequencing on esophageal mucosa from 14 achalasia and 8 healthy subjects. 65 differentially expressed genes (DEGs) were found in the distal esophageal mucosa of achalasia subjects and 120 DEGs were identified in proximal esophagus. Gene expression analysis identified genes common or exclusive to proximal and distal esophagus, highlighting regional differences in the disease. Enrichment of signaling pathways related to cytokine response and viral defense were observed. Increased infiltration of CD45+ intraepithelial leukocytes were seen in the mucosa of 38 achalasia patients compared to 12 controls. Novel insights into the molecular changes occurring in achalasia were generated in this transcriptomic study. Some gene changes observed in the mucosa of achalasia may be associated with esophagitis. Differences in DEGs between distal and proximal esophagus highlight the importance of better understanding regional differences in achalasia.

Circulating levels of cytokines, chemokines and growth factors in patients with achalasia

Idiopathic achalasia is a disease that is characterized by the absence of peristalsis and incomplete relaxation of the lower esophageal sphincter, which is accompanied by dysphagia, regurgitation, chest pain and weight loss. The role of inflammatory infiltrates in the pathogenesis of achalasia remains controversial, although the infiltrating cell profile in the tissue has been previously characterized histologically and immunohistochemically. The present study aimed to evaluate the serum levels of 27 protein biomarkers to determine their association with achalasia and the clinical disease characteristics. The cytokine, chemokine and growth factor serum profiles of 68 patients with achalasia and 39 healthy individuals were explored using the 27-Bio-Plex Pro Human Cytokine assay. Reductions in the levels of inflammatory mediators IL-1β, IL-2, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-15, IL-17, fibroblast growth factor, granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, interferon-γ, monocyte chemoattractant protein-1, macrophage inflammatory protein-1 (MIP-1)α and MIP-1β, regulated upon activation normal T cell expressed and presumably secreted, TNF-α and VEGF were detected in the serum samples of patients with achalasia compared with those in the control group (P<0.05). However, significant associations between the expression in the levels of inflammatory factors and clinical characteristics of the patients were not found (P>0.05). These results suggest that achalasia is a disease that has a local but not a systemic inflammatory pattern. Further studies are required to improve the current understanding of the mechanism underlying this disease.

The etiology of achalasia: An immune-dominant disease

There is accumulating evidence suggesting that an autoimmune component is involved in esophageal achalasia. An increase in immune cells, cytokines, chemokines, and autoimmune antibodies in serum and infiltration of immune cells in tissues support the view that immune-mediated inflammation is a crucial pathogenesis of inhibitory neuron degeneration in the lower esophageal sphincter. Infection of viruses such as the herpes virus family has been suspected of provoking the autoimmune reaction. Meanwhile, previous reports on immunogenetics have proposed that specific risk alleles on the human leukocyte antigen complex define the susceptible population to achalasia. In this study we reviewed current knowledge regarding the immune-related factors of achalasia, including immunology, viral infection and immunogenetic variations.

Histopathological Analysis of Esophageal Mucosa in Patients with Achalasia

Background/Aims

Achalasia is an esophageal motor disorder that leads to functional esophageal obstruction. Food stasis and bacterial fermentation can predispose an individual to esophageal mucosal inflammation, causing multifocal dysplasia and increasing the risk of developing esophageal squamous cell carcinoma. We aimed to evaluate esophageal mucosal alterations in achalasia patients and determine clinical factors associated with the histopathological findings.

Methods

From 2009 to 2013, we obtained endoscopic biopsies from the lower and middle esophagus of 22 patients with achalasia and 17 controls. Patients’ clinical data and histological severity of esophagitis were retrospectively analyzed. Additionally, immunohistochemical staining for CD3, CD20, Ki-67, and p53 was conducted.

Results

The median age of achalasia patients was 49.5 years (range, 27 to 82 years), and there were nine males (40.9%). The median symptom duration was 5.8 years (range, 1 to 33.5 years), and 10 patients (45%) underwent previous treatment (nine, balloon dilation; one, botulinum toxin injection). Achalasia patients had significantly more severe esophagitis than did controls (p=0.001, lower esophagus; p=0.008, middle esophagus), and the number of CD3-positive lymphocytes exceeded that of CD20-positive lymphocytes (p<0.001). Achalasia patients also had a higher esophageal Ki-67 proliferation index (p=0.048). Although statistically nonsignificant, p53 expression was only observed in achalasia patients. There was no association between the histological severity of esophagitis and other clinicopathological findings.

Conclusions

Achalasia patients showed significantly severe histological esophagitis and a high Ki-67 proliferation index, indicating an increased risk of neoplastic progression. Therefore, careful endoscopic inspection is necessary for the early detection of superficial neoplasia in these patients. (Gut Liver 2021;15-722)

Multiplex immunoassays reveal increased serum cytokines and chemokines associated with the subtypes of achalasia

BACKGROUND

Achalasia is an esophageal motility disorder with unknown etiology. Previous findings indicate that immune-mediated inflammatory process causes inhibitory neuronal degeneration. This study was designed to evaluate levels of serological cytokines and chemokines in patients with achalasia.

METHODS

We collected information from forty-seven patients with achalasia who underwent peroral endoscopic myotomy. Control samples were collected from forty-seven age- and sex-matched healthy people. The concentrations of serological cytokines and chemokines were analyzed by Luminex xMAP immunoassay. Serological and clinical data were compared between groups.

KEY RESULTS

Compared with healthy controls, achalasia patients had significantly increased concentrations of eleven cytokines and chemokines, namely, TGF-ß1 (P < .001), TGF-ß2 (P < .001), TGF-ß3 (P < .001), IL-1ra (P < .001), IL-17 (P = .005), IL-18 (P < .001), IFN-γ (P < .001), MIG (P < .001), PDGF-BB (P < .001), IP-10 (P = .003), and SCGF-B (P < .001). Gene ontology (GO) and network functional enrichment analysis revealed regulation of signaling receptor activity and receptor-ligand activity were the most related pathways of these cytokines and chemokines. Levels of twelve cytokines and chemokines were significantly increased in type III compared with I/II achalasia, namely, TGF-ß2, IL-1ra, IL-2Ra, IL-18, MIG, IFN-γ, SDF-1a, Eotaxin, PDGF-BB, IP-10, MCP-1, and TRAIL.

CONCLUSIONS AND INFERENCES

Patients with achalasia exhibited increased levels of serological cytokines and chemokines. Levels of cytokines and chemokines were significantly increased in type III than in type I/II achalasia. Cytokines and chemokines might contribute to the inflammatory development of achalasia.