[Fecal Microbiota Transfer (FMT) in Germany - Status and Perspective]. / Fäkaler Mikrobiota-Transfer (FMT) in Deutschland ­ Status und Perspektive.

INTRODUCTION: Fecal microbiota transfer (FMT) is a treatment to modulate the gastrointestinal microbiota. Its use in recurrent Clostridioides difficile infection (rCDI) is established throughout Europe and recommended in national and international guidelines. In Germany, the FMT is codeable in the hospital reimbursement system. A comprehensive survey on the frequency of use based on this coding is missing so far. MATERIAL AND METHODOLOGY: Reports of the Institute for Hospital Remuneration (InEK), the Federal Statistical Office (DESTATIS), and hospital quality reports 2015-2021 were examined for FMT coding and evaluated in a structured expert consultation. RESULTS: Between 2015 and 2021, 1,645 FMT procedures were coded by 175 hospitals. From 2016 to 2018, this was a median of 293 (274-313) FMT annually, followed by a steady decline in subsequent years to 119 FMT in 2021. Patients with FMT were 57.7% female, median age 74 years, and FMT was applied colonoscopically in 72.2%. CDI was the primary diagnosis in 86.8% of cases, followed by ulcerative colitis in 7.6%. DISCUSSION: In Germany, FMT is used less frequently than in the European comparison. One application hurdle is the regulatory classification of FMT as a non-approved drug, which leads to significantly higher costs in manufacturing and administration and makes reimbursement difficult. The European Commission recently proposed a regulation to classify FMT as a transplant. This could prospectively change the regulatory situation of FMT in Germany and thus contribute to a nationwide offer of a therapeutic procedure recommended in guidelines.

Microbiota medicine: towards clinical revolution.

The human gastrointestinal tract is inhabited by the largest microbial community within the human body consisting of trillions of microbes called gut microbiota. The normal flora is the site of many physiological functions such as enhancing the host immunity, participating in the nutrient absorption and protecting the body against pathogenic microorganisms. Numerous investigations showed a bidirectional interplay between gut microbiota and many organs within the human body such as the intestines, the lungs, the brain, and the skin. Large body of evidence demonstrated, more than a decade ago, that the gut microbial alteration is a key factor in the pathogenesis of many local and systemic disorders. In this regard, a deep understanding of the mechanisms involved in the gut microbial symbiosis/dysbiosis is crucial for the clinical and health field. We review the most recent studies on the involvement of gut microbiota in the pathogenesis of many diseases. We also elaborate the different strategies used to manipulate the gut microbiota in the prevention and treatment of disorders. The future of medicine is strongly related to the quality of our microbiota. Targeting microbiota dysbiosis will be a huge challenge.

What does a gastroenterologist need to know in the time of SARS-CoV-2 pandemia?

Coronavirus disease 2019 (COVID 19) is an emerging infectious disease caused by a novel coronavirus SARS-CoV2 that was first identified in Wuhan, China 2019 and that led to a worldwide pandemia. In addition to typical respiratory signs (dry cough, shortness of breathing), some patients may develop gastrointestinal and hepatological complications including diarrhea or acute hepatitis, respectively. Due to the close contact to the patient's secretion, the gastroenterologists are at increased risk of getting the infection. Therefore, a proper individual risk stratification before every endoscopic procedure is highly recommended. Endoscopy personnel should reduce exposure hazards by keeping a distance from the patient and using gloves, face masks, face shields and gowns. Taking into the consideration the fact that the virus proliferates in the gastrointestinal (GI) tract, special attention should be given to handling with stool specimens. In patients obtaining FMT for recurrent C. difficile infection, recommended screening measures include donor's medical history and testing for SARS-CoV-2 presence in pharyngeal and stool specimens.

Hydroxychloroquine is no miracle cure for covid-19 infection -imaging and clinical course in an elderly female.

The risk for an unfavourable course of SARS-CoV-2 pneumonia rises with age and comorbidities. We report the case of an elderly female where the sum of such factors - together with massive findings in the computed tomography of the lung - led us to a therapy with hydroxychloroquine as a compassionate use. The unfavourable outcome demonstrates that - despite the enthusiasm of some authors - hydroxychloroquine is no miracle drug. The worldwide SOLIDARITY trial will help clinicians to assess the potential of the repurposed antimalarial drugs better.

An analysis of early morning acth levels in the first case of pembrolizumab-induced adrenalitis as a delayed immune-related event (dire) - case study.

OBJECTIVE: The aim: The levels of adrenocorticotrophic hormone (ACTH) are elevated in primary adrenal failure (Addison's disease) with a peak in the early morning hours. This also occurs under hydrocortisone replacement therapy due to the unphysiological substitution regime. The aim was to study ACTH levels under two different replacement regimens. This is exemplified in a patient with adrenalitis after immunotherapy for malignant melanoma (MM), since (elevated) levels of ACTH and its cleavage product alpha-melanocyte stimulating hormone (α-MSH) raise concerns since receptors for both hormones can be expressed in melanoma cells. PATIENTS AND METHODS: Material and methods: A female with MM had immunotherapy with pembrolizumab and developed adrenalitis with Addison crisis about one year after discontinuation of this therapy (delayed immune-related event = DIRE). ACTH levels were measured hourly (4-8 a.m.) during a "conventional" hydrocortisone replacement therapy and during a therapy with dual-release hydrocortisone. RESULTS: Results: Salient differences between the morning ACTH profiles under the "conventional" hydrocortisone replacement regimen with 10-5-5 mg/die compared to the single-dose regimen with 20 mg dual-release hydrocortisone were not discernible. CONCLUSION: Conclusion: DIRE could be an underestimated problem in immunotherapy and could put the patients at hazard. Especially in case of an endocrinological DIRE concerning the adrenocorticotrophic axis, life-threatening situations can arise for the patients. As for the special situation with M. Addison and MM, where hormonal feedback mechanisms may cause further problems beyond the normal hormonal replacement therapy, we observed no salient differences in the early morning ACTH profiles under different hydrocortisone replacement regimens.

Course of a SARS-COV-2 pneumonia in a middle-aged male patient.

The SARS-CoV-2 infection has recently been declared a pandemic by the WHO. Most fatalities occur in elderly people with comorbidities. However, SARS-CoV-2 pneumonias do also occur in younger patients with no comorbidities or risk factors at all. We report here on one of the "early" cases that occurred in Germany. A 57-year-old man was infected and developed pneumonia after a skiing vacation in Northern Italy. Other members of the travel group also fell ill, but only showed flu-like symptoms. Only a few if any infections originated from the affected person; at this point in time the infection situation in the region could still be grasped. Under supportive measures, the disease developed positively despite impressive radiological findings. The positive course is likely also due to the age of the person affected and the lack of any risk factors. The case does also exemplify that a good health condition does not necessarily protect from acquiring a moderately severe SARS-CoV-2 infection.

Severe metabolic syndrome and primary amenorrhea as main pathophysiological features in a subtype of turner syndrome (46, X, del (X) Q 21).

Turner syndrome can be manifest with a considerable genetic and phenotypic variability. This merely accounts for about 50% of patients who do not have the "classic" 45 X genotype. We report the case of a 42-year-old female patient with a 46, X, del (X) q 21 genotype (deletion on the second X chromosome on the long arm). As the patient displayed a non-typical phenotype and was infertile, a diagnosis was established at the age of 24 with no follow-up treatment. As part of our therapy of the individual due to newly manifested diabetes mellitus, our diagnostic workup revealed a severe metabolic syndrome encompassing fatty liver disease, obstructive sleep apnea syndrome and hyperuricemia. Our observations should sensitize physicians treating female patients for one or more aspects of the metabolic syndrome and its presence in Turner syndrome. These patients have an unfavorable cardiovascular profile, in part due to the metabolic syndrome, but also due to factors intrinsic to Turner syndrome.

Acute-onset diabetes mellitus with ketoacidosis in a nivolumab-treated patient with hepatocellular carcinoma.

The therapy with immune checkpoint inhibitors (Programmed cell death-1 and programmed cell death-ligand-1 inhibitors) is a novel and promising approach in cancer treatment. The mode of action can cause serious adverse advents, mainly immune-related ones. The case of a 65 year old caucasian female is reported. She suffers from hepatocellular carcinoma since 2012. She underwent several surgeries, was treated with sorafenib and had transcatheter arterial chemoembolizations. As part of an individual healing trial, the patient was treated with nivolumab every 2 or 3 weeks since September 2017 and has no recurrence of the tumor ever since. Eight months after onset of the therapy she rapidly developed an insulin-dependent diabetes with ketoacidosis. She had no previous history of diabetes. She had no type 1 diabetes-related autoantibodies or a common HLA-genotype associated with a higher risk to develop type 1 diabetes mellitus. This adverse event during therapy with an immune checkpoint inhibitor is yet reported to be rare. Cases with a rapid-onset diabetes with ketoacidosis have also been reported under treatment with other immune checkpoint inhibitors. The pathomechanism is not clear yet and which patients are at an elevated risk. An increasing use of immune checkpoint inhibitor therapy can be expected. This may cause a concurrent increase of the side effect diabetes. Glucose monitoring and sensitizing the patients for this adverse event seems reasonable.

Emphysematous pyelonephritis - a rare complication of diabetes mellitus.

Emphysematous pyelonephritis is a rare form of acute necrotizing pyelonephritis. It is a gas-producing, necrotizing infection involving the renal parenchyma and surrounding tissues. It is associated with high mortality and morbidity. In the majority of cases, patients with long-standing diabetes and poor glycemic control are affected. We report the case of a 67 yr old female who survived severe sepsis due to emphysematous pyelonephritis. Potential therapeutic strategies in the aftermath from a diabetologist's point of view are discussed.

Dynamics of Fukuoka Criteria and Patient Management in Pancreatic Intraductal Papillary Mucinous Neoplasms (IPMNs) During Follow-Up.

BACKGROUND Pancreatic intraductal papillary mucinous neoplasms (IPMNs) present a clinical challenge. Evidence-based guidelines are lacking. The so-called "Fukuoka criteria" were developed to assess the risk of malignancy in IPMNs upon imaging. However, little is known about their diagnostic value and the natural course of IPMNs. Thus, the aim of this study was the assessment of Fukuoka criteria and patient management in pancreatic IPMNs -during follow-up. MATERIAL AND METHODS IPMNs were identified via retrospective survey of endoscopic ultrasound (EUS) examinations. Fukuoka criteria were assessed on EUS findings and additional imaging (CT, MRI, ultrasound). Patients' symptoms and comorbidities were recorded. Dynamics of Fukuoka criteria and patient management were compared at first presentation and during follow-up. RESULTS We screened 1324 EUS examinations. Sixty-five patients (male/female, 14/37; mean age, 68.8 years; range, 48-85 years) with IPMNs were identified (57 branch duct (BD-)IPMNs, 3 main duct (MD-) IPMNs, 5 mixed-type (MT)-IPMNs). Seven patients received surgical resection (4 BD-IPMNs, 2 MD-IPMNs, 1 MT-IPMN). Nine BD-IPMNs had neither surgery nor follow-up. Fifty-one patients (44 BD-IPMNs, 2 MD-IPMNs, 5 MT-IPMNs) underwent follow-up (mean duration, 18.7 months; range, 3-139 months). There were 15/51 patients who were initially Fukuoka-positive. One MD-IPMN, 4/5 MT-IPMNs, and 13/44 BD-IPMNs showed progressive changes but were not resected due to patients' refusal or comorbidities. Four BD-IPMNs converted to Fukuoka-positive. CONCLUSIONS Evidence-based guidelines for non-invasive dignity assessment of IPMNs are lacking. In our study, MD-IPMNs displayed greater dynamics than BD-IPMNs and MT-IPMNs concerning Fukuoka criteria. Prospective long-term studies are needed to clarify prognostic significance of the single Fukuoka criteria and sensible duration of follow-up.

Hypertrophic Pachymeningitis and the Syndrome of Inappropriate Antidiuretic Hormone Secretion: Coincidence or Cause?

OBJECTIVE: To investigate a potential cause of the syndrome of inappropriate antidiuretic hormone secretion (SIADH). CLINICAL PRESENTATION AND INTERVENTION: A 70-year-old female patient had nausea and collapsed. Although euvolemic, pathological laboratory findings showed hyponatremia and hypoosmolality, and cerebral magnetic resonance imaging showed hypertrophic pachymeningitis. Secondary hypertrophic pachymeningitis was excluded. Other nonneurological reasons for SIADH were also excluded. Moderate fluid restriction restored an almost normal serum osmolality and sodium. CONCLUSION: This case of SIADH was conservatively treated with moderate fluid restriction that almost restored normal serum osmolality and sodium levels.

Successful Therapy of Severe Pseudomembranous Clostridium difficile Colitis Using a Combination of Fecal Microbiota Therapy and Fidaxomicin.

OBJECTIVE: The aim of this work was to describe the use of a combination of fidaxomicin and fecal microbiota therapy (FMT) in Clostridium difficile infection (CDI). CLINICAL PRESENTATION AND INTERVENTION: A 78-year-old female, who was admitted for surgery due to acute diverticulitis caused by postoperative complications and broad antibiotic therapy, developed CDI-induced colitis. Despite the introduction of metronidazole and vancomycin therapy, her clinical condition continued to deteriorate. She was transferred to the intensive care unit where FMT followed by fidaxomicin were performed because her C-reactive protein and leucocyte levels remained elevated. Further clinical improvement and the resolution of colitis was observed. CONCLUSION: In this case, severe CDI colitis was successfully treated with the combination of FMT and fidaxomicin.

Low Pretreatment Acoustic Radiation Force Impulse Imaging (ARFI) Values Predict Sustained Virological Response in Antiviral Hepatitis C Virus (HCV) Therapy.

BACKGROUND Non-invasive procedures such as acoustic radiation force impulse imaging (ARFI) shear-wave elastography are currently used for the assessment of liver fibrosis. In the course of chronic hepatitis C, significant liver fibrosis or cirrhosis develops in approximately 25% of patients, which is a negative predictor of antiviral treatment response. Cirrhosis can be prevented by successful virus elimination. In this prospective study, a pretreatment ARFI cutoff value of 1.5 m/s was evaluated in relation to sustained virological response to anti-HCV therapy. MATERIAL AND METHODS In 23 patients with chronic hepatitis C, liver stiffness was examined with ARFI at defined times before and under antiviral triple therapy (peginterferon, ribavirin in combination with a first-generation protease inhibitor, and telaprevir or boceprevir). Patients were stratified into 2 groups based on pretreatment ARFI values (<1.5 m/s and ≥1.5 m/s) for the assessment of virological response. RESULTS The liver stiffness at baseline for all patients was 1.57±0.79 m/s (ARFI median ± standard deviation; margin: 0.81 m/s to 3.45 m/s). At week 4 of triple therapy, patients with low pretreatment ARFI values had higher rates of HCV-RNA negativity (69% vs. 43%), reflecting an early rapid virological response (eRVR). Sustained virological response (SVR) was found in 75% (12/16) of patients with an ARFI value <1.5 m/s and only 57% (4/7) of patients with ARFI value ≥1.5 m/s. CONCLUSIONS Patients with chronic hepatitis C and pretreatment ARFI <1.5 m/s showed earlier virus elimination and better response to treatment.

[Gut microbiome and psyche: paradigm shift in the concept of brain-gut axis]. / Darmmikrobiom und Psyche: der Paradigmenwechsel im Konzept der Hirn-Darm-Achse.

BACKGROUND: The concept of the brain-gut axis describes the communication between the central and enteric nervous system. The exchange of information takes place in both directions. The great advances in molecular medicine in recent years led to the discovery of an enormous number of microorganisms in the intestine (gut microbiome), which greatly affect the function of the brain-gut axis. METHOD: Overview RESULTS AND CONCLUSIONS: Numerous studies indicate that the dysfunction of the brain-gut axis could lead to both inflammatory and functional diseases of the gastrointestinal tract. Moreover, it was shown that a faulty composition of the gut microbiota in childhood influences the maturation of the central nervous system and thus may favor the development of mental disorders such as autism, depression, or other. An exact causal relationship between psyche and microbiome must be clarified by further studies in order to find new therapeutic options.

Excretion of urinary histamine and N-tele methylhistamine in patients with gastrointestinal food allergy compared to non-allergic controls during an unrestricted diet and a hypoallergenic diet.

BACKGROUND: Patients with gastrointestinal food allergy are characterised by increased production of mast cell derived mediators upon allergen contact and present often with unspecific symptoms. The aim of this study was to evaluate urinary histamine and methylhistamine excretion in patients with food allergy and to compare their values with food-tolerant controls. METHODS: In a retrospective case control study the urinary excretion parameters were analysed from 56 patients (40.9, 19 - 58 years) in whom later food challenge tests confirmed food allergy. During their diagnostic work-up urine was collected during a 12-h period under an unrestricted diet with staple foods and a hypoallergenic potato-rice-diet (each 2 days). Healthy controls underwent the same diet types to define normal excretion parameters. Urinary histamine and n-methylhistamine were determined by ELISA or tandem mass spectrometry, respectively, and were expressed as median (25 - 75% range, µg/mmol creatinine x m(2)BSA). RESULTS: During unrestricted diet urinary histamine was significantly higher in gastrointestinal food allergy than healthy controls (1.42, 0.9 - 2.7 vs 0.87, 0.4 - 1.3; p < 0.0001), while the difference between both groups became marginal during potato-rice diet (1.30, 0.7 - 2.1 vs 1.05, 0.5 - 1.5; p = 0.02). N-methylhistamine was found to be significantly elevated in gastrointestinal food allergy both during unrestricted diet (7.1, 5.0 - 11.2) and potato-rice diet (5.7, 3.7 - 8.7) compared to controls (p < 0.0001). Interestingly, urinary methylhistamine excretion (p < 0.004) and clinical symptom score (p < 0.02) fell significantly when the diet was switched from unrestricted to hypoallergenic food, but was not correlated with symptom scores. CONCLUSIONS: In gastrointestinal food allergy significantly higher levels of urine histamine and methylhistamine excretion were found under unrestricted diet, reflecting an increased secretion of histamine due to offending foods. Measurement of urinary n-methylhistamine levels may help to find out patients with increased histamine production and/or food-allergen induced clinical symptoms, respectively.

Malnutrition in Hospitals: It Was, Is Now, and Must Not Remain a Problem!

BACKGROUND: Malnutrition is an under-recognized problem in hospitalized patients. Despite systematic screening, the prevalence of malnutrition in the hospital did not decrease in the last few decades. The aim of our study was to evaluate the prevalence of malnutrition and to determine the explicit daily calorie intake of hospitalized patients, to identify the risk factors of developing malnutrition during hospitalization and the effect on the financial reimbursement according to the German DRG-system. MATERIAL AND METHODS: 815 hospitalized patients were included in this study. The detection of malnutrition was based on the nutritional-risk-screening (NRS) and subjective-global-assessment (SGA) scores. A trained investigator recorded the daily calorie and fluid intake of each patient. Furthermore, clinical parameters, and the financial reimbursement were evaluated. RESULTS: The prevalence of malnutrition was 53.6% according to the SGA and 44.6% according the NRS. During hospitalization, patients received on average 759.9±546.8 kcal/day. The prevalence of malnutrition was increased in patients with hepatic and gastrointestinal disease and with depression or dementia. The most important risk factors for malnutrition were bed rest and immobility (OR=5.88, 95% CI 2.25-15.4). In 84.5% of patient records, malnutrition was not correctly coded, leading to increased financial losses according to the DRG-system (94.908 Euros). CONCLUSIONS: Hospitalized patients suffer from inadequate nutritional therapy and the risk for developing malnutrition rises during the hospital stay. The early screening of patients for malnutrition would not only improve management of nutritional therapy but also, with adequate coding, improve financial reimbursement according to the DRG-system.

Outcome and complications of endoscopic balloon dilatations in various types of ileocaecal and colonic stenosis in patients with Crohn's disease.

AIM: We examined the outcome and the complications of endoscopic balloon dilatation (EBD) of ileocaecal and colonic strictures due to Crohn's disease. METHODS: We examined 237 dilatation procedures in 77 patients with symptomatic ileocaecal and colonic stenosis regarding outcome, individual perforation risk, the need for further interventions, and other complications within a 10 years observation period. RESULTS: In 50 of 77 patients (64.9%), endoscopic dilatation procedures were successful within a median follow-up period of 24 months (25th and 75th percentile 10-38.5 months). Thirty five patients (45.5%) were successfully dilated with only one endoscopic procedure, while the remaining patients required two or more EBDs. Albeit the EBD, 27 patients of the whole cohort (35.1%) underwent surgical repair of the stenosis in due course. Overall complication rate was 7.6%, with postdilatation bleeding in 1.7% and abdominal pain longer than 24 h in 4.2%. Perforation occurred in 4 of 77 patients (5.2%), resulting in a perforation rate of 1.7% per intervention, or, more importantly, for the individual patient in a long-term perforation rate of 5.2% per patient, respectively. DISCUSSION: Endoscopic balloon dilatation (EBD) is a safe and effective approach to ileocaecal and colonic stenosis in approximately 65% of Crohn's disease patients. Even in case of recurrence, further endoscopic treatments can be undertaken. The perforation rate depending on the number of interventions is low, but for the individual patient a cumulative per patient perforation risk of 5.2% in the long-term should be considered during patient information and decisions for or against surgical interventions.

Impact of acoustic radiation force impulse imaging in clinical practice of patients after orthotopic liver transplantation.

BACKGROUND: Acoustic radiation force impulse (ARFI) elastography is a reliable diagnostic device for quantitative non-invasive assessment of liver fibrosis in patients with chronic liver disease. The aim of our prospective study was to evaluate the impact of ARFI in patients after orthotopic liver transplantation (OLT). Therefore, we compared ARFI shear wave velocities with clinical features, non-invasive markers, and the histology of patients following OLT. MATERIAL AND METHODS: Post-transplant patients underwent a clinical examination and blood samples were taken. B-mode and Doppler ultrasound (US) of the portal vein and the hepatic artery were performed. Subsequently, a minimum of 10 valid ARFI values were measured in the left and right liver lobe. Liver biopsy was performed if indicated. RESULTS: Between May 2012 and May 2014, 58 Patients after OLT were included in the prospective study. Laboratory markers and aspartate aminotransferase-to-platelet ratio index (APRI) correlated with ARFI values (r=0.44, p<0.001). The histological (n=22) fibrosis score (Ludwig) was significantly correlated with the ARFI of the biopsy site (r=0.55, p=0.008). The mean shear-wave velocities were significantly increased in advanced fibrosis (F≤2 1.57±0.57 m/s; F≥3 2.85±0.66 m/s; p<0.001), obstructive cholestasis and active viral hepatitis. The area under the receiver operating characteristic (AUROC) curves for the accuracy of ARFI were 74% (F≥1), 73% (F≥2), 93% (F≥3), and 80% (=F4). CONCLUSIONS: ARFI elastography correlates well with laboratory values and with noninvasive and invasive markers of fibrosis in patients after OLT. In this regard, elevated ARFI-velocities should be interpreted with caution in the context of obstructive cholestasis and active viral disease.

Methylation-dependent activation of CDX1 through NF-κB: a link from inflammation to intestinal metaplasia in the human stomach.

The caudal homeobox factor 1 (CDX1) is an essential transcription factor for intestinal differentiation. Its aberrant expression in intestinal metaplasia of the upper gastrointestinal tract is a hallmark within the gastritis-metaplasia-carcinoma sequence. CDX1 expression is influenced by certain pathways, such as Wnt, Ras, or NF-κB signaling; however, these pathways alone cannot explain the transient expression of CDX1 in intestinal metaplasia or the molecular inactivation mechanism of its loss in cases of advanced gastric cancer. In this study, we investigated the epigenetic inactivation of CDX1 by promoter methylation, as well as the functional link of CDX1 promoter methylation to the inflammatory NF-κB signaling pathway. We identified methylation-dependent NF-κB binding to the CDX1 promoter and quantified it using competitive electrophoretic mobility shift assays and chromatin immunoprecipitation. A methylated CDX1 promoter was associated with closed chromatin structure, reduced NF-κB binding, and transcriptional silencing. Along the gastritis-metaplasia-carcinoma sequence, we observed a biphasic pattern of tumor necrosis factor-α (TNF-α) protein expression and an inverse biphasic pattern of CDX1 promoter methylation; both are highly consistent with CDX1 protein expression. The stages of hyper-, hypo-, and hyper-methylation patterns of the CDX1 promoter were inversely correlated with the NF-κB signaling activity along this sequence. In conclusion, these functionally interacting events drive CDX1 expression and contribute to intestinal metaplasia, epithelial dedifferentiation, and carcinogenesis in the human stomach.

Esophagoprotection mediated by exogenous and endogenous melatonin in an experimental model of reflux esophagitis.

Reflux esophagitis is a common clinical entity in western countries with approximately 30% of the population experiencing the symptoms at least once every month. The imbalance between the protective and aggressive factors leads to inflammation and damage of the esophageal mucosa. We compared the effect of exogenous melatonin and melatonin derived endogenously from L-tryptophan with that of pantoprazole or ranitidine in acid reflux esophagitis due to ligation of the rat pylorus and the limiting ridge between the forestomach and the corpus. Four hours after the induction of gastric reflux, an increase in mucosal lesions associated with edema of the submucosa and with the infiltration of numerous neutrophils and the fall in esophageal blood flow (EBF) were observed. Both melatonin and L-tryptophan or pantoprazole significantly reduced the lesion index (LI) and raised the EBF. Pinealectomy that significantly decreased plasma melatonin levels aggravated LI and these effects were reduced by melatonin and L-tryptophan. Luzindole, the MT2 receptor antagonist, abolished the melatonin-induced reduction in LI and the rise in EBF. L-NNA and capsaicin that augmented LI and decreased EBF, also significantly reduced melatonin-induced protection and hyperemia; both were restored with L-arginine and calcitonin gene-related peptide (CGRP) added to melatonin. Upregulation of IL-1ß and TNF-α mRNAs and plasma IL-1ß and TNF-α levels were significantly attenuated by melatonin and L-tryptophan. We conclude that melatonin protects against acid reflux-induced damage via activation of MT2 receptors mediated by NO and CGRP released from sensory nerves and the suppression of expression and release of TNF-α and IL-1ß.