Altered Esophageal Smooth Muscle Phenotype in Achalasia.

Background/Aims: Achalasia is a disorder characterized by impairment in lower esophageal sphincter relaxation and esophageal aperistalsis, caused primarily by loss of inhibitory innervation. However, little is known about associated changes in esophageal smooth muscle. We examined the contractile phenotype and innervation of the circular smooth muscle, as well as inflammatory status, and correlated these with patient-specific parameters. Methods: Circular smooth muscle biopsies were obtained in consecutive patients with achalasia undergoing peroral endoscopic myotomy. Axonal innervation and neurotransmitter subtypes were determined with immunocytochemistry, and this was used with quantitative Polymerase Chain Reaction (qPCR) to characterize smooth muscle proliferation and cellular phenotype, as well as collagen expression. These were compared to control tissue obtained at esophagectomy and correlated with patient demographic factors including age, onset of symptoms, and Eckhardt score. Results: Biopsies of smooth muscle were obtained from 25 patients with achalasia. Overall, there was increased mast cell number and collagen deposition but increased smooth muscle cell proliferation vs control. There was a striking drop in axon density over controls, with no differences among subtypes of achalasia. Immunocytochemical analysis showed increased expression of the contractile marker α-smooth muscle actin, principally in Type 1 achalasia, that increased with disease duration, while qPCR identified increased mRNA for smoothelin with decreased myosin heavy chain and collagen 3a1, but not collagen 1a1. Conclusions: The thickened circular smooth muscle layer in achalasia is largely denervated, with an altered contractile phenotype and fibrosis. Biopsies obtained during peroral endoscopic myotomy provide a means to further study the pathophysiology of achalasia.

Response to Marabotto et al.

Biopsies have important value in assessing for nonerosive reflux disease.

The role of histology in the diagnosis of non-erosive reflux disease: A systematic review and meta-analysis.

BACKGROUND AND PURPOSE: Non-erosive reflux disease (NERD) accounts for over half of all gastroesophageal reflux cases and is characterized by reflux symptoms with pathologic acid exposure on pH monitoring but no evidence of erosions on upper endoscopy. Ambulatory pH monitoring is limited by availability and patient tolerance. The utility of performing esophageal mucosal biopsies in diagnosing NERD is unclear. We conducted a systematic review and meta-analysis to determine the sensitivity of esophageal mucosal biopsies in diagnosing NERD. METHODS: Data were obtained from Embase and Ovid MEDLINE from inception to April 2021. Studies were included if esophageal mucosal biopsies were taken and analyzed using conventional histopathologic analysis in symptomatic NERD patients. Relevant data was including histologic abnormalities and location of the biopsy. Sensitivity and specificity were calculated against healthy controls or those with functional heartburn. RESULTS: The search yielded 2871 studies, of which 10 studies met our inclusion criteria and contained raw data. Histological abnormalities included histologic sum scores, papillary elongation, basal cell hyperplasia, and dilated intraepithelial spaces. When assessing for the presence of any abnormality, biopsies taken <3 cm from the lower esophageal sphincter (LES) had a pooled sensitivity of 0.71 (95% CI 0.64-0.77) and specificity of 0.64 (95% 0.54-0.73); however, analysis of individual histologic features such as the presence of eosinophils improved the sensitivity. CONCLUSIONS: Although esophageal mucosal biopsies had poor sensitivity at diagnosing NERD, biopsies taken within 3 cm of the LES had higher sensitivity when pathologists reported upon eosinophils and dilated intraepithelial spaces.

Nintedanib regulates intestinal smooth muscle hyperplasia and phenotype in vitro and in TNBS colitis in vivo.

Chronic inflammation of the human intestine in Crohn's disease (CD) causes bowel wall thickening, which typically progresses to stricturing and a recurrent need for surgery. Current therapies have limited success and CD remains idiopathic and incurable. Recent evidence shows a key role of intestinal smooth muscle cell (ISMC) hyperplasia in stricturing, which is not targeted by current anti-inflammatory therapeutics. However, progression of idiopathic pulmonary fibrosis, resembling CD in pathophysiology, is controlled by the tyrosine kinase inhibitors nintedanib (NIN) or pirfenidone, and we investigated these drugs for their effect on ISMC. In a culture model of rat ISMC, NIN inhibited serum- and PDGF-BB-stimulated growth and cell migration, and promoted the differentiated phenotype, while increasing secreted collagen. NIN did not affect signaling through PDGF-Rß or NFκB but did inhibit cytokine-induced expression of the pro-inflammatory cytokines IL-1ß and TNFα, supporting a transcriptional level of control. In TNBS-induced colitis in mice, which resembles CD, NIN decreased ISMC hyperplasia as well as expression of TNFα and IL-1ß, without effect in control animals. NIN also inhibited growth of human ISMC in response to human serum or PDGF-BB, which further establishes a broad range of actions of NIN that support further trial in human IBD.