Esophageal Epithelium Of Patients Research Articles

Regulatory T cells Are Increased and Correlate With Mast Cells in Eosinophilic Esophagitis.

The incidence of eosinophilic esophagitis (EoE) has been increasing recently. The role of regulatory T cells (Tregs) and correlations with other inflammatory cells in EoE remain unknown. We aim to clarify the role of Tregs and their correlations with inflammatory cells in EoE patients. Biopsies from controls and EoE patients before and after treatments were analyzed. Eosinophil infiltration was evaluated by hematoxylin and eosin staining. Immunohistochemical staining was performed to examine infiltration of T cells, Tregs, and mast cells. Gene expressions of chemokines were evaluated by reverse transcription-quantitative polymerase chain reaction. Tregs and mast cells were increased in the esophageal epithelial layers of EoE patients. After treatments, Tregs and mast cells were decreased when histologic remission was achieved. Infiltration of Tregs correlated significantly with numbers of eosinophils and mast cells. Filaggrin mRNA was decreased in patients with EoE before treatment and upregulated after treatment, even when histologic remission was not achieved. Tregs were increased in esophageal epithelium of patients with EoE, and correlated with mast cell infiltration.

IκB Kinase-β Regulates Neutrophil Recruitment Through Activation of STAT3 Signaling in the Esophagus

Background & AimsThe epithelial barrier is the host’s first line of defense against damage to the underlying tissue. Upon injury, the epithelium plays a critical role in inflammation. The IκB kinase β (IKKβ)/nuclear factor-κB pathway was shown to be active in the esophageal epithelium of patients with esophageal disease. However, the complex mechanisms by which IKKβ signaling regulates esophageal disease pathogenesis remain unknown. Our prior work has shown that expression of a constitutively active form of IKKβ specifically in esophageal epithelia of mice (IkkβcaEsophageal Epithelial Cell-Knockin (EEC-KI)) is sufficient to cause esophagitis.MethodsWe generated ED-L2/Cre;Rosa26-Ikkβca+/L;Stat3L/L (IkkβcaEEC-KI;Stat3Esophageal Epithelial Cell Knockout (EEC-KO)) mice, in which the ED-L2 promoter activates Cre recombinase in the esophageal epithelium, leading to constitutive activation of IKKβ and loss of Stat3. Esophageal epithelial tissues were collected and analyzed by immunostaining, RNA sequencing, quantitative real-time polymerase chain reaction assays, flow cytometry, and Western blot. IkkβcaEEC-KI mice were treated with neutralizing antibodies against interleukin (IL)23p19 and IL12p40.ResultsHere, we report that IkkβcaEEC-KI mice have increased activation of epithelial Janus kinase 2/STAT3 signaling. Stat3 deletion in IkkβcaEEC-KI mice attenuated the neutrophil infiltration observed in IkkβcaEEC-KI mice and resulted in decreased expression of genes related to immune cell recruitment and activity. Blocking experiments in IkkβcaEEC-KI mice showed that STAT3 activation and subsequent neutrophil recruitment are dependent on IL23 secretion.ConclusionsOur study establishes a novel interplay between IKKβ and STAT3 signaling in epithelial cells of the esophagus, where IKKβ/IL23/STAT3 signaling controls neutrophil recruitment during the onset of inflammation. GEO accession number: GSE154129.

Sa1159 – The Impacts of On-Demand Versus Continuous Therapy on the Symptom Control and Histological Changes of Metaplastic Esophageal Epithelium in Patients with Barrett Esophagus — a Randomized Controlled Trial

Sa1159 – The Impacts of On-Demand Versus Continuous Therapy on the Symptom Control and Histological Changes of Metaplastic Esophageal Epithelium in Patients with Barrett Esophagus — a Randomized Controlled Trial

ЭКСПРЕССИЯ Е-КАДГЕРИНА В СЛИЗИСТОЙ ОБОЛОЧКЕ ПИЩЕВОДА У ПАЦИЕНТОВ С ГАСТРОЭЗОФАГЕАЛЬНОЙ РЕФЛЮКСНОЙ БОЛЕЗНЬЮ И/ИЛИ СИНДРОМОМ ОБСТРУКТИВНОГО АПНОЭ/ГИПОПНОЭ СНА

Background. Obstructive sleep apnea/hypopnea syndrome (OSAHS) seems to have a negative impact on the state of esophageal mucosa in patients with GERD, therefore it is significant to evaluate the structure of esophageal epithelium in patients with GERD and OSAHS. Objective – to evaluate E-cadherin expression in the epithelium of the lower third of the esophagus in patients with GERD and/or OSAHS. Materials and methods. 143 examined patients have undergone esophagogastroduodenoscopy with the biopsy of the lower third of the esophagus as well as respiratory monitoring. The patients were divided into 4 groups: group 1 – patients with GERD (n=35), group 2 – patients with GERD and OSAHS (n=40), group 3 – with OSAHS (n=38), group 4 – control group (n=30). There have been performed the identification of plasma concentration of N-terminal E-cadherin fragment and evaluation of E-cadherin expression in the epithelium of the lower third of the esophagus. Results. The patients with GERD and OSAHS had statistically significant higher plasma concentration of N-terminal E-cadherin fragment in comparison to other groups. E-cadherin expression in the epithelium was statistically significantly lower in all studied groups in contrast to the control group. There has been revealed a negative correlation between plasma concentration of N-terminal E-cadherin fragment and E-cadherin expression in the epithelium as well as between apnea/hypopnea index and E-cadherin expression. Conclusion. The patients with GERD and OSAHS are characterized by low E-cadherin expression in the epithelium of the lower third of the esophagus on the background of high plasma concentration of N-terminal E-cadherin fragment.

Cleavage of E-Cadherin Contributes to Defective Barrier Function in Neosquamous Epithelium.

After ablation of Barrett's esophagus (BE), the esophagus heals with neosquamous epithelium (NSE). Despite normal endoscopic appearance, NSE exhibits defective barrier function with similarities to defects noted in the distal esophageal epithelium in patients with gastroesophageal reflux disease (GERD). To determine whether patients with NSE, unlike patients with healthy esophageal epithelium, have C-terminal fragments (CTFs) of e-cad detectable on tissue biopsy. Secondly, to determine whether patients with NSE have elevated levels of N-terminal fragments (NTFs) of e-cad in the serum. Fifteen patients with ablated long-segment BE, who had healing with formation of NSE, were enrolled in this pilot study. Western blots for CTFs and NTFs were performed on biopsies of NSE. Venous blood was obtained to assess levels of NTFs. Endoscopic distal esophageal biopsies from patients without esophageal disease served as tissue controls. Control blood samples were obtained from healthy subjects. Blots of NSE were successful in 14/15 patients, and all 14 (100%) had a 35-kD CTF of e-cad, while CTFs were absent in healthy control tissues. Despite CTFs in NSE, serum NTFs of e-cad in NSE were similar to controls, p>0.05. However, unlike healthy controls, blots of NSE also showed NTFs with molecular weights of 70-90kD. Cleavage of e-cad, as evidenced by the presence of CTFs and NTFs on biopsy, contributes to defective barrier function in NSE. However, unlike findings reported in GERD patients, serum NTFs are not elevated in NSE patients. This difference may reflect poor absorption with tissue entrapment of NTFs in previously ablated areas with poorly perfused NSE.

Activity of mitogen-activated protein kinases in the esophageal epithelium of patients with Barrett's esophagus.

Barrett's esophagus (BE), a complication of gastroesophageal reflux disease, is associated with an increased risk of esophageal cancer. Mitogen-activated protein kinases may play an important role in the pathogenesis of this process. We aimed to evaluate mitogen-activated protein kinases activity in esophageal mucosa of patients with BE and find possible relationship between reflux type and BE. Twenty-four patients (mean age: 59 years) with gastroesophageal reflux disease symptoms and endoscopically suspected esophageal metaplasia (ESEM) were prospectively enrolled for testing by a multichannel intraluminal impedance monitoring along with a Bilitec 2000. Endoscopic biopsies were taken from methylene blue-positive pit patterns (sites suggesting specialized intestinal metaplasia [SIM]), from 2 cm above the Z-line and from cardial parts of the stomach. The biopsies were analyzed for extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38 activity by Western blot. Seventeen ESEMs had histologically proven metaplasia: eight patients had SIM and nine had gastric-type epithelia (GE). Biliary reflux was more evident in SIM (P = 0.019) but not in GE (P = 0.019); non-biliary reflux was typical for GE (P = 0.005) but not for SIM (P = 0.04). Strong activations of ERK and p38 were found predominantly in SIM, but not in normal esophageal mucosa (NE) (P = 0.01 and P < 0.001 respectively). Strong signals for active JNK and p38 were detected in GE, but not in NE (P = 0.006 and P = 0.02 respectively). ERK activity was significantly higher than p38 activity in ESEM patients only with GE (P = 0.02). The strong activation of ERK, but not JNK is indicative of SIM. The presence of bile in gastroesophageal refluxate is predisposing to SIM, but not to GE in esophageal mucosa.

The Influence of Age, Smoking, Antiretroviral Therapy, and Esophagitis on the Local Immunity of the Esophagus in Patients with AIDS

Studies have shown immunological and morphological alterations in the esophagus during the course of AIDS. Esophageal postmortem samples of 22 men with AIDS autopsied in a teaching hospital between 1982 and 2009 were collected. We carried out revision of the autopsy reports and medical records, morphometric analysis (Image J and KS-300 Kontron-Zeiss), and immunohistochemical (anti-S100, anti-IgA, anti-IgG, and anti-IgM) analysis of the esophagus. In accordance with most of the parameters evaluated, age and the smoking habit harmed the esophageal local immunity, whereas the use of antiretroviral therapy improved the immune characteristics of this organ. Patients with esophagitis also presented immunological fragility of the esophagus. This leads to the conclusion that alterations in the esophageal epithelium of patients with AIDS are not only caused by direct action of HIV but also the clinical and behavioral characteristics of the patient.

A Transforming Growth Factor Beta-1 Gene Single Nucleotide Polymorphism May Influence Phenotype in Pediatric Eosinophilic Esophagitis

S U N D A Y 474 Key Function of Cadherin-Like 26 in Eosinophilic Gastrointestinal Disorders Julie M. Caldwell, PhD, Margaret Collins, MD, Carine Blanchard, PhD, Emily Stucke, BA, Katherine Kemme, BS, Lissa Amin, BA, Philip Putnam,MD, James Franciosi, MD, Juan Pablo Pablo Abonia, MD, Marc E. Rothenberg, MD, PhD, FAAAAI; Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, Cincinnati Childrens’ Hospital Medical Center, Cincinnati, OH, Cincinnati Children Hospital, Cincinnati, OH, Nemours Children’s Hospital, Orlando, FL. RATIONALE: Cadherin-like 26 (CDH26) is markedly overexpressed in the affected tissue of eosinophilic gastritis (EG) and eosinophilic esophagitis (EoE) patients. We aimed to understand the expression pattern and function of CDH26 in eosinophilic gastrointestinal disorders. METHODS: Characterization of CDH26 expression patterns was undertaken through RT-PCR, immunohistochemistry, and western blot analysis. Protein interactions were examined using transient transfection and immunoprecipitation analysis. CDH26 function in mediating calciumdependent cell aggregation was tested. The impact of CDH26 on eosinophil transmigration through 293T cells was investigated. RESULTS: CDH26 was highly expressed in the gastric and esophageal epithelium of patients with EG or EoE, respectively. This molecule exhibited homotypic interaction and additionally interacted with betacatenin, alpha-catenin, and delta-catenin (p120) when expressed ectopically in 293T cells. Furthermore, cells expressing high levels of CDH26 exhibited calcium-dependent aggregation. Interestingly, CDH26 protein expression was observed in human peripheral blood eosinophils, and eosinophil transmigration through 293T cells overexpressing CDH26 was enhanced compared to transmigration through control cells. CONCLUSIONS: CDH26 interacts with catenin proteins, which link cadherin molecules to the actin cytoskeleton. Furthermore, CDH26 exhibits homotypic interaction and promotes calcium-dependent cell aggregation, consistent with a function in cell adhesion. A greater number of eosinophils migrated to eotaxin through CDH26-overexpressing cells compared to control cells. SinceCDH26 protein expressionwas detected in eosinophils, engagement between CDH26 molecules on epithelial cells and eosinophils may impact cell signaling and localization. As such, we propose that CDH26 is a major cadherin expressed in allergic GI tissue and may have a key role in various aspects of disease pathogenesis and diagnosis.

The association between smoking and LINE-1 hypomethylation (global DNA hypomethylation) in normal esophageal epithelium of patients with esophageal squamous cell carcinoma.

41 Background: DNA methylation is a major epigenetic mechanism in X-chromosome inactivation, imprinting and repression of transposable elements and endogenous retroviral sequences. Global DNA hypomethylation appears to play an important role in genomic instability, leading to cancer development. DNA methylation in the long interspersed nucleotide element-1, L1 (LINE-1) repetitive element is a good indicator of global DNA methylation level. Smoking and alcohol is extremely important as the etiology of esophageal squamous cell carcinoma. Nonetheless, whether or not smoking and alcohol affect LINE-1 methylation level in normal esophageal epithelium of esophageal cancer patients remains uncertain. Methods: We quantified LINE-1 methylation of normal esophageal mucosa using pyrosequencing technology in 118 resected esophageal squamous cell carcinomas. The data on smoking (Brinkman index, absence or presence) and alcohol amount are available in all cases. We excluded preoperatively treated cases. Results: LINE-1 methylation in normal esophageal epithelium of esophageal cancer patients ranged from 57.1 to 92.8 of 0-100 scale (N=118; mean 81.2; median 80.0; standard deviation 7.2). LINE-1 methylation level (continuous variable) was significantly associated with Brickman index (continuous variable) (r=0.12, p=0.0002); heavy smoker had lower LINE-1 methylation level of normal esophageal mucosa. LINE-1 methylation level was lower in patients with smoking history (mean 79.7) than in patients without smoking history (mean 83.2) (p=0.034). Alcohol assumption was not associated with LINE-1 methylation level (r=0.003, p=0.58). Conclusions: Smoking was associated with LINE-1 hypomethylation in esophageal normal epithelium, suggesting the possibility of epigenetic field effects caused by cigarette in esophageal tumorigenesis. Considering that DNA methylation alterations are reversible and can thus be targets for chemoprevention, our findings may have clinical implication.

Mast cells infiltrate the esophageal smooth muscle in patients with eosinophilic esophagitis, express TGF-β1, and increase esophageal smooth muscle contraction

Increased numbers of mast cells are present in the esophageal epithelium in patients with eosinophilic esophagitis (EE). However, mast cell infiltration into the esophageal lamina propria (LP) and smooth muscle (SM) and the effects of their products on SM function has not been determined. We investigated mast cell localization and characterization in esophageal SM, the functional significance of mast cell TGF-β1 expression to contraction of human esophageal smooth muscle (HESM) cells in vitro, and the effect of topical corticosteroids on the number of tryptase-positive (MC(T)) and chymase-positive (MC(C)) mast cells in patients with EE. MC(T)- and MC(C)-positive mast cell numbers were quantitated in the epithelium, the LP before and after topical corticosteroid therapy, and the muscularis mucosa in patients with EE and control subjects by using immunohistology. Double immunofluorescence was used to assess mast cell production of TGF-β1. The ability of TGF-β1 to influence HESM cell contractility was assessed in vitro. In the SM in patients with EE, significantly increased numbers of MC(T)- and TGF-β1-positive cells (but only low levels of eosinophils) were detected compared with those seen in control subjects. MC(T) expressed TGF-β1, which increased the contractility of cultured primary HESM cells in vitro. Topical corticosteroid therapy in patients with EE significantly reduced epithelial MC(T) numbers but not LP tryptase-chymase-positive mast cell numbers. MC(T) numbers, rather than eosinophil numbers, are increased in the SM in patients with EE, express TGF-β1, and increase the contractility of HESM cells in vitro. As such, mast cells localized to SM in patients with EE might modulate esophageal contractility.

Comparative Analysis of FcεRI Expression Patterns in Patients With Eosinophilic and Reflux Esophagitis

Eosinophilic esophagitis (EoE) is an allergic disease of the esophagus. The IgE receptors on immune cells that infiltrate the esophagus are poorly defined. The high-affinity receptor for IgE, FcεRI, may play a role in EoE. The objective of the present study is to identify and compare the IgE receptors in the esophageal epithelium of patients with EoE, reflux esophagitis (RE), and normal controls. A retrospective case-control study of 62 patients (19 EoE, 22 RE, 21 normal controls) was conducted. Biopsies were immunostained for FcεRI, CD23, galectin-3, c-kit, CD1a, and langerin. FcεRI was the only IgE receptor present in the esophageal epithelium of patients with EoE. The FcεRI-positive cell count varied by diagnosis (proximal biopsies EoE 32.6 ± 19.0 cells/high-power field, RE 26.7 ± 16.6, controls 15.6 ± 8.3, ANOVA P = 0.005; distal biopsies EoE 24.2 ± 16.2, RE 35.7 ± 27.6, controls 15.3 ± 8.4, P = 0.006). In the proximal esophagus, the FcεRI count was higher in EoE than in controls (P = 0.006); in the distal esophagus, the FcεRI count was higher in RE than in controls (P = 0.004). EoE and RE had similar FcεRI-positive cell counts. A subset of FcεRI-positive cells was similar in morphology and distribution to Langerhans cells (CD1a and langerin positive). The presence of FcεRI-positive cells in high numbers in the esophageal epithelium implies this receptor must be critical in the IgE-mediated activation of immune cells in the esophagus. Langerhans cells in the esophageal epithelium appear to express FcεRI. The role of Langerhans cells in the pathophysiology of EoE needs to be elucidated.

Budesonide Is Effective in Adolescent and Adult Patients With Active Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease of the esophagus characterized by dense tissue eosinophilia; it is refractory to proton pump inhibitor therapy. EoE affects all age groups but most frequently individuals between 20 and 50 years of age. Topical corticosteroids are effective in pediatric patients with EoE, but no controlled studies of corticosteroids have been reported in adult patients. We performed a randomized, double-blind, placebo-controlled trial to evaluate the effect of oral budesonide (1 mg twice daily for 15 days) in adolescent and adult patients with active EoE. Pretreatment and posttreatment disease activity was assessed clinically, endoscopically, and histologically. The primary end point was reduced mean numbers of eosinophils in the esophageal epithelium (number per high-power field [hpf] = esophageal eosinophil load). Esophageal biopsy and blood samples were analyzed using immunofluorescence and immunoassays, respectively, for biomarkers of inflammation and treatment response. A 15-day course of therapy significantly decreased the number of eosinophils in the esophageal epithelium in patients given budesonide (from 68.2 to 5.5 eosinophils/hpf; P < .0001) but not in the placebo group (from 62.3 to 56.5 eosinophils/hpf; P = .48). Dysphagia scores significantly improved among patients given budesonide compared with those given placebo (5.61 vs 2.22; P < .0001). White exudates and red furrows were reversed in patients given budesonide, based on endoscopy examination. Budesonide, but not placebo, also reduced apoptosis of epithelial cells and molecular remodeling events in the esophagus; no serious adverse events were observed. A 15-day course of treatment with budesonide is well tolerated and highly effective in inducing a histologic and clinical remission in adolescent and adult patients with active EoE.

Esophageal pH exposure and epithelial cell differentiation

It is proposed that epithelial changes induced by gastroesophageal reflux disease are related to the pH environment of the esophageal lumen. We hypothesized that the various types of esophageal epithelium are associated with specific pH environments that induce their formation. The aim of this study was to compare the luminal pH environment to the histology of the distal esophageal epithelium in patients with gastroesophageal reflux disease. A total of 197 symptomatic patients with increased esophageal acid exposure on 24-hour pH monitoring were grouped according to the histology based on biopsies from the distal esophagus: 17 with squamous epithelium, 126 with cardiac epithelium (CE), and 54 with Barrett's epithelium (BE). All were free of Helicobacter pylori infection and monitored off acid suppression therapy. Acid exposure was expressed as the percent of time the luminal pH was at intervals of 0-1, 1-2, 2-3, 3-4, 4-5, 5-6, and 6-7 over a 24-hour period. Patients with BE spent significantly more time at pH intervals 2-3, 3-4, and 4-5 than those with CE. This pattern switched at pH interval 5-6, where patients with cardiac mucosa spent more time than those with BE. Patients with squamous and CE had similar pH exposure at all intervals. Patients with BE have significantly longer exposure time at the pH interval of 2 to 5 compared to those with cardiac and squamous epithelium. This suggests that the exposure of stem cells to a luminal pH between 2 and 5 may trigger the differentiation of CE into intestinalized CE.

Expression of tight junction protein occludin and changes in intercellular space in the esophageal epithelium in patients with gastroesophageal reflux disease

Expression of tight junction protein occludin and changes in intercellular space in the esophageal epithelium in patients with gastroesophageal reflux disease

Changes of intercellular spaces of esophageal epithelium in patients with gastroesophageal reflux disease before and after esomeprazole treatment

To observe the changes of dilated intercellular space (DIS) of esophageal epithelium in different subtypes of gastroesophageal reflux disease (GERD) before and after esomeprazole treatment. Nineteen patients with GERD, 6 with erosive esophagitis (EE), 7 with NERD with abnormal acid exposure (NERD pH+), and 6 with NERD with normal acid exposure (NERD pH-), were treated with esomeprazole 40 mg daily for two months. During endoscopy before and after treatment, six biopsy specimens were taken from the apparently normal mucosa 3 - 5 cm above the dentate line in the esophagus to undergo HE staining and histological examination and transmission electron microscopy (TEM). Fifteen normal subjects were used as controls. Two months after the treatment 5 cases (83.33%) in the EE group, 6 cases (85.57%) in the NERD pH+ group, and 5 cases (83.33%) in the NERD pH- group showed a complete recovery of DIS and complete disappearance of the symptom of heartburn. Two of the left three patients who showed incomplete recovery of DIS still had heartburn. A complete recovery of DIS 2 months after treatment of esomeprazole is always accompanied by resolution of heartburn symptom. No significant difference in complete recovery of DIS can be found among different GERD subgroups.

Enhanced expression of interleukin-8 and activation of nuclear factor kappa-B in endoscopy-negative gastroesophageal reflux disease.

Interleukin-8 (IL-8) mediates neutrophil trafficking via its receptors. Recent studies have shown that IL-8 is likely involved in the development and progression of erosive reflux esophagitis (RE), yet little is known about its implication in endoscopy-negative gastroesophageal reflux disease (GERD). The purpose of this study was to determine IL-8 messenger ribonucleic acid (mRNA) expression levels in endoscopy-negative GERD, along with assessment of nuclear factor kappaB (NF-kappaB) activation, which upregulates IL-8 expression. We studied 31 patients with endoscopy-negative GERD, 15 patients with erosive RE, and 15 asymptomatic controls. Paired biopsy samples were taken from the esophagus 3 cm above the gastroesophageal junction; one biopsy was snap-frozen for measurement of IL-8 mRNA levels by real-time quantitative polymerase chain reaction, and another was formalin-fixed for histopathological evaluation. In nine endoscopy-negative GERD patients, the IL-8 mRNA expression levels were measured before and 8 wk after treatment with lansoprazole. We also sampled additional specimens for NF-kappaB-DNA binding assay and immunohistochemical analyses of NF-kappaB p65 and p50 subunits, IL-8 and specific IL-8 receptor, CXCR-1. The relative IL-8 mRNA expression levels were significantly higher in esophageal mucosa of patients with endoscopy-negative GERD than those of the controls. The presence of basal zone hyperplasia and intraepithelial neutrophils, histopathological hallmarks of GERD, were associated with higher levels of IL-8 mRNA. Lansoprazole treatment significantly reduced the IL-8 mRNA expression levels. The esophageal epithelium of patients with GERD showed intense immunoreactivity for IL-8, and expressed CXCR-1 antigen. We found NF-kappaB activation in esophageal mucosa in GERD patients and the NF-kappaB subunits were localized predominantly in the nuclei of IL-8-expressing cells. Our results demonstrate enhanced mucosal expression of IL-8 in incipient GERD even without mucosal breaks. NF-kappaB activation may be implicated in the pathogenesis in GERD.

Enhancement of formation of the esophageal carcinogen benzylmethylnitrosamine from its precursors by Candida albicans.

Previous studies in Linxian, an area of China with a high incidence of esophageal carcinoma, showed that fungal infections are common in the esophageal epithelium of patients with either premalignant changes or early esophageal carcinoma. Fungi of the genus Candida were the most frequent invaders. In these areas nitrate and nitrite are often present in high concentrations in drinking water and staple grains. The present studies have established the ability of Candida albicans to augment the nitrosative formation of the esophagus-specific carcinogen, benzylmethylnitrosamine (NBMA; N-nitroso-N-methylbenzylamine). Stationary C. albicans cultures, with pH held at 6.8, were incubated with the precursors of NBMA, benzylmethylamine (BMA; N-methylbenzylamine) and NaNO(2). There was a significant increase in the amount of NBMA formed in these cultures, compared to precursors-only controls. The amount of NBMA synthesized depended on fungal cell number. Exponentially growing cultures were also able to cause NBMA formation. The identity of the NBMA was confirmed by high-performance liquid chromatographic coelution with authentic NBMA in three solvent systems and by mass spectroscopy. Boiled cells and conditioned medium in which cells had been incubated were not effective in enhancing nitrosation. Cultured Candida released acidic metabolites that reduced the pH of the medium when only a low concentration of buffer was present. Spontaneous nitrosation of BMA was enhanced under these acidic conditions. Thus, C. albicans infecting the esophageal epithelium could cause local formation of NBMA by both cell-mediated catalysis and extracellular decrease in pH.