AHR activation by tryptophan--pathogenic hallmark of Th17-mediated inflammation in eosinophilic fasciitis, eosinophilia-myalgia-syndrome and toxic oil syndrome?

The aryl-hydrocarbon-receptor (AHR) is involved as receptor and transcription factor in dioxin toxicity. Recently, its role in Th17-mediated autoimmunity and autoinflammation has been described, yet a disease-associated AHR ligand is still elusive. L-tryptophan and its metabolites are assumed to trigger the autoinflammatory disorders eosinophilic fasciitis, eosinophilia-myalgia-syndrome and toxic oil syndrome. Since L-tryptophan and metabolites are well known as AHR ligands we hypothesize that it is their interaction with AHR that induces Th17 cell differentiation and autoinflammation in these disorders. This, for the first time would link disease-causing environmental factors to a well-defined cellular receptor and the subsequent pathogenic pathway.

Immunogenetic risk and protective factors for the development of L-tryptophan-associated eosinophilia-myalgia syndrome and associated symptoms.

OBJECTIVE: To assess L-tryptophan (LT) dose, age, sex, and immunogenetic markers as possible risk or protective factors for the development of LT-associated eosinophilia-myalgia syndrome (EMS) and related clinical findings. METHODS: HLA-DRB1 and DQA1 allele typing and Gm/Km phenotyping were performed on a cohort of 94 white subjects with documented LT ingestion and standardized evaluations. Multivariate analyses compared LT dose, age, sex, and alleles among groups of subjects who ingested LT and subsequently developed surveillance criteria for EMS, developed EMS or characteristic features of EMS (EMS spectrum disorder), or developed no features of EMS (unaffected). RESULTS: Considering all sources of LT, higher LT dose (odds ratio [OR] 1.4, 95% confidence interval [95% CI] 1.1-1.8), age >45 years (OR 3.0, 95% CI 1.0-8.8), and HLA-DRB1*03 (OR 3.9, 95% CI 1.2-15.2), DRB1*04 (OR 3.9, 95% CI 1.1-16.4), and DQA1*0601 (OR 13.7, 95% CI 1.3-1.8) were risk factors for the development of EMS, whereas DRB1*07 (OR 0.12, 95% CI 0.02-0.48) and DQA1*0501 (OR 0.23, 95% CI 0.05-0.85) were protective. Similar risk and protective factors were seen for developing EMS following ingestion of implicated LT, except that DRB1*03 was not a risk factor and DQA1*0201 was an additional protective factor. EMS spectrum disorder also showed similar findings, but with DRB1*04 being a risk factor and DRB1*07 and DQA1*0201 being protective. There were no differences in sex distribution, Gm/Km allotypes, or Gm/Km phenotypes among any groups. CONCLUSION: In addition to the xenobiotic dose and subject age, polymorphisms in immune response genes may underlie the development of certain xenobiotic-induced immune-mediated disorders, and these findings may have implications for future related epidemics.

Generation of quinoneimine intermediates in the bioactivation of 3-(N-phenylamino)alanine (PAA) by human liver microsomes: a potential link between eosinophilia-myalgia syndrome and toxic oil syndrome.

Eosinophilia-myalgia syndrome (EMS) was an intoxication episode that occurred in the US in 1989 and affected 1,500 people. EMS was associated with the ingestion of manufactured L-tryptophan, and 3-(N-phenylamino)alanine (PAA) was identified as one of the contaminants present in the L-tryptophan batches responsible for intoxication. In previous studies (Martínez-Cabot et al., Chem Res. Toxicol., in press), we have shown that the incubation of 3-(N-phenylamino)propane-1,2-diol (PAP), a toxic biomarker of the oil batches that caused Toxic Oil Syndrome in Spain, with human liver microsomes generates a reactive quinoneimine intermediate. The structural similarity between PAA and PAP led Mayeno and co-workers (Mayeno et al. (1995) Chem. Res. Toxicol. 8, 911-916) to hypothesize that both xenobiotics could be linked to a common etiologic agent. We thus set about to study the bioactivation of PAA by human liver microsomes. Under these conditions, PAA is converted to its 4'-hydroxy derivative, an unstable intermediate that is rapidly transformed into the final metabolites 4-aminophenol and formylglycine, which were identified in the incubations by GC/MS using the H2(18)O-labeled medium. We also provide evidence that 4-aminophenol and formylglycine are formed from a quinoneimine intermediate via a pathway similar to that demonstrated for PAP bioactivation. This quinoneimine, in the absence of nucleophiles in the incubation medium, could isomerize to give the corresponding imine, which could undergo hydrolysis to yield the aforementioned final products. These findings establish that EMS and TOS are linked by a common toxic metabolite (4-aminophenol) and that they may be further linked by the concomitant release of potentially hazardous carbonyl species.

Eosinophilic perimyositis as the presenting feature of a monoclonal T-cell expansion.

A 51-year-old physically active man was investigated for exertional myalgias and muscle stiffness. On examination he had mild proximal muscle weakness of the upper extremities and retraction of the digit flexors. Blood eosinophilia was present, but serum creatine kinase (CK) levels and an electromyographic study were normal. A skin-fascia-muscle biopsy of the calf revealed a macrophagic and CD4+ T-cell infiltration of the perimysium, and a T-cell expansion was observed in blood, bone marrow, and muscle. A diagnosis of eosinophilic perimyositis was made, and prednisone and azathioprine were administrated with a good clinical response. This case highlights the differential diagnosis of blood eosinophilia with muscle disorders, and underscores that eosinophilic perimyositis may be the expression of a T-cell monoclonal expansion. Although the pathogenesis behind the T-cell expansion is unclear but probably inflammatory, we suggest regular follow-up to allow early treatment of any T-cell lymphoproliferative malignancy that may develop.

L-tryptophan contaminant 'peak E' induces the release of IL-5 and IL-10 by peripheral blood mononuclear cells from patients with functional somatic syndromes.

In 1989, the development of eosinophilia myalgia syndrome (EMS) was observed in some patients after the intake of l-tryptophan containing several contaminants, including 1,1'-ethylidenebis[l-tryptophan] ('peak E'). Since l-tryptophan has been taken particularly by individuals suffering from functional somatic syndromes (FSS), such as fibromyalgia syndrome (FMS), we put forward the hypothesis that EMS may have developed preferentially in patients with FSS as an allergic reaction towards the contaminant peak E. We therefore studied the immunological reactivity towards l-tryptophan and peak E in these individuals (n = 12) and compared these data with those obtained in 12 healthy controls and 12 patients with other chronic disorders. Peripheral blood mononuclear cells (PBMC) were cultured for 7 days with pure l-tryptophan and peak E. Supernatant fluids were collected at day 7. The type 2 cytokines IL-4, IL-5 and IL-10, and the type 1 cytokines IL-2 and IFN-gamma, were determined by a double sandwich ELISA. PBMC from seven of the 12 FSS patients, but only three of the 24 controls, produced cytokines after incubation with peak E (P < 0.05). Interestingly, six of the seven FSS patients reacting with peak E produced IL-5 and/or IL-10. In contrast, PBMC from only one patient with other chronic disorders and one healthy control secreted type 2 cytokines in response to peak E. The observed heightened type 2 reactivity towards the more immunogenic contaminant 1,1'-ethylidenebis[l-tryptophan] in FSS patients may therefore be taken as an additional argument for our concept that EMS may have developed as a kind of drug-induced allergic disease.

The toxic oil syndrome: 20 years on.

With hindsight, it is easy to criticise the standards of food regulation of two decades ago. Nevertheless, when the Spanish toxic oil syndrome (TOS) appeared in 1981, there were many who asked why aniline was permitted as an official adulterant for imported French rape seed oil, and why such adulterated oils were often illegally refined in Spain and marketed without difficulty. This review brings up to date a comprehensive survey of the ensuing research published in 1995 and concentrates on recent significant findings. These include the identification of the refinery that produced the toxic oil, and the detection of oil contaminants with possible aetiological significance. Possible chemical links have been found between oil contaminants and those detected in L-tryptophan implicated in the eosinophilia-myalgia syndrome (EMS). There is good evidence that the initial pathogenetic mechanism is immunological. On metabolic evidence, it is suggested that not one, but a group of, toxic agents was responsible for TOS.

Red eye syndrome: clinical and experimental experience in a new aspect of diffuse eosinophilic infiltration?

Twenty-two of 24 hemodialysis patients dialyzed simultaneously with a new batch of cellulose acetate dialyzers promptly developed a spectrum of symptoms and physical signs including red eyes, hearing loss, tinnitus, and bone pain, previously described as red eye syndrome. We subsequently injected 4 rabbits with an eluate from a dialyzer of the same or a control batch. Six hours following exposure, the animals developed, in addition to red eyes, diffuse eosinophilic infiltration of various organs as well as myopathic changes and moderate brain edema. On the basis of these data, we suggest that it cannot be concluded whether the underlying pathophysiological mechanisms were toxic, allergic or both and that the occurrence of relevant symptomatology in 2 or more simultaneously dialyzed patients is a strong argument against unnecessary diagnostic or therapeutic procedures. Finally, a second exposure in a given patient should be avoided.

Eosinophilia-myalgia syndrome, eosinophilic fasciitis, and related fibrosing disorders.

Clinically distinct fibrosing processes affecting the skin, selected internal organs, or both in a characteristic pattern are a common cause of morbidity. In addition to systemic sclerosis, the prototype idiopathic fibrosing disorder, these conditions include the eosinophilia-myalgia syndrome, epidemic toxic oil syndrome, eosinophilic fasciitis, localized forms of scleroderma, keloid, and the newly described entity of fibrosing colonopathy. The pathogenesis of these disorders, although still incompletely understood, appears to share similarities with that of systemic sclerosis. Insights into these diseases have recently emerged from epidemiologic and toxicoepidemiologic investigations, in situ hybridization and polymerase chain reaction amplification of target genomes, and in vivo and in vitro experimental research. Minor contaminants in food supplements, activation and degranulation of eosinophils, altered expression of CD34 antigen on dendritic cells, disordered regulation of fibroblast apoptosis and proliferation, infection with Borrelia organisms, and cytokines such as transforming growth factor-beta, interleukin-4, and connective tissue growth factor are implicated in inducing an accentuated and persistent fibrogenic host response to injury, resulting in tissue fibrosis. In addition, humoral and cellular autoimmunity may also be implicated.

Effect of L-tryptophan products on function of human eosinophils: investigation of the causal mechanisms of eosinophilia myalgia syndrome associated with L-tryptophan products.

Contaminants in the L-tryptophan products, known as peak-E and peak-5, at a concentration of 1-10 micrograms/ml had the ability to elicit chemokinetic migration of eosinophils. Purified eosinophils adhered to peak-E- or peak-5-stimulated human umbilical vein endothelial cells, and this adherence was inhibited by the presence of antibody to intercellular adhesion molecule-1, but not by vascular cell adhesion molecule-1 antibody. Neither contaminant affected the expression of integrins, e.g. CD11b or CD49d, on the purified eosinophils. Human peripheral blood mononuclear cells (PBMCs) produced eosinophil survival-enhancing activity when cultivated with peak-E, but not with medium alone, peak-5 or control tryptophan. This activity of peak-E was significantly inhibited (p < 0.01) by the presence of antibody to granulocyte-macrophage colony-stimulating factor (GM-CSF). In addition, expression of GM-CSF mRNA was found in total cellular RNA isolated from peak-E-stimulated PBMCs. Eosinophils acquired the ability to migrate toward interleukin-8 (IL-8) when preincubated with the contaminants of interest. IL-8 also bound to the contaminant-stimulated eosinophils, but not to those stimulated with medium alone. These findings suggest that contaminants in the L-tryptophan products modify the several functions of eosinophils and play a role in the pathogenesis of eosinophil myalgia syndrome.

Pathogenesis of L-tryptophan eosinophilia myalgia syndrome.

Taken together, these studies suggest that many different etiologic agents alone or together may initiate the common final pathways of tissue pathologic response resulting in the clinical syndrome of eosinophilia, myalgias and fasciitis. Tryptophan itself may contribute to some of the scarring features of the illness, while impure L-tryptophan, and one or more of the impurities cause the characteristic features of the illness. The altered tryptophan metabolism in EMS is secondary to inflammation.