Pathogenesis Of Eosinophilia-myalgia Syndrome Research Articles

Enhanced collagen synthesis and transcription by peak E, a contaminant of L-tryptophan preparations associated with the eosinophilia myalgia syndrome epidemic.

The pathogenesis of the eosinophilia myalgia syndrome (EMS) remains unclear. Several abnormal constituents have been found in the L-tryptophan lots responsible for the illness, particularly, 1,1-ethylidenebis[L-tryptophan], also called peak E or EBT, and 3-phenylamino-alanine or peak 5. However, the role of these contaminants in the pathogenesis of EMS and in the development of fibrosis is unknown. We now report that peak E, a dimer of L-tryptophan, is a potent stimulus for human dermal fibroblast DNA and collagen synthesis. Peak E (0.1-1.0 microM) increased DNA synthesis up to four-fold (P = 0.0001) in a dose-dependent manner (r = 0.987). When added to monolayer cultures for 2 to 24 h, peak E (0.5 to 100 microM) caused a progressive, more than threefold increase in alpha 1(I) procollagen mRNA levels and collagenous protein. No increase in procollagen mRNA levels was found after the addition of another major L-tryptophan contaminant, peak 5, or with L-tryptophan itself. Transient transfection with a 2.5-kb alpha 1(I) procollagen promoter-luciferase construct showed that peak E causes a twofold upregulation of promoter activity (P = 0.022). Contraction of collagen gels, consisting of human dermal fibroblasts incorporated into a type I collagen lattice, was enhanced two-fold by exposure to peak E (P = 0.001). We conclude that a major constituent of contaminated batches of L-tryptophan, peak E, is a potent stimulus for fibroblast activation and collagen synthesis. This stimulatory action of peak E may provide a direct mechanism for the development of fibrosis in EMS.

Eosinophilia-myalgia syndrome, toxic-oil syndrome, and diffuse fasciitis with eosinophilia

Eosinophilia-myalgia syndrome, a recently described illness, reached epidemic proportions in 1989 and was linked to the ingestion of L-tryptophan containing trace amounts of several contaminants. Eosinophilia-myalgia syndrome shares many clinical and pathologic similarities with toxic-oil syndrome, an epidemic linked to the ingestion of adulterated cooking oil that occurred in Spain in 1981, and to diffuse fasciitis with eosinophilia, a condition first described in 1974. Over the past year, much work has been done in understanding the etiology and pathogenesis of eosinophilia-myalgia syndrome and toxic-oil syndrome. Follow-up data detailing the long-term sequelae and mortality rates for these two conditions are becoming available. The results from these studies are reviewed in this paper.

Pharmacogenetic characteristics of the eosinophilia-myalgia syndrome

This study tested the hypothesis that patterns of xenobiotic metabolism in patients with eosinophilia-myalgia syndrome (EMS) differed from healthy control subjects. We determined the genotypes of 27 EMS patients with EMS and 114 control subjects for the cytochrome P450 CYP2D6 polymorphism. The metabolic phenotypes of patients with EMS for S-mephenytoin hydroxylation (n = 17) and dapsone acetylation (n = 19) were determined and compared with 29 healthy control subjects. The incidence of the CYP2D6 poor metabolizer genotype (mutant/mutant) was 0.185 in patients with EMS and 0.061 in control subjects (Mantel-Haenszel, chi 2 = 7.213, p = 0.007). The mephenytoin S/R ratios were 0.39 +/- 0.23 in patients with EMS versus 0.18 +/- 0.13 in control subjects (p < or = 0.005). There was no difference in dapsone acetylation between the two groups. A pattern of xenobiotic metabolism may play a role in the pathogenesis of EMS, but the precise role that it plays remains unclear.

A murine model of the eosinophilia-myalgia syndrome induced by 1,1'-ethylidenebis (L-tryptophan).

The eosinophilia-myalgia syndrome (EMS) is a recently described disease that has been associated with the ingestion of L-tryptophan containing trace amounts of several impurities. The first such contaminant to be identified and linked epidemiologically to the EMS epidemic was 1,1'-ethylidenebis(L-tryptophan) (EBT), but its role in the etiology and pathogenesis of the syndrome has been controversial. We report the development of inflammation and fibrosis affecting the dermis and subcutis, including the fascia and perimyseal tissues, after the daily intraperitoneal administration of EBT to female C57BL/6 mice. Such changes are accompanied by increased numbers of mast cells, many of which appear to be degranulating. Plasma levels of quinolinic acid, a metabolic product of L-tryptophan via the kynurenine pathway, are reduced initially, and then become elevated when inflammation and fibrosis are more pronounced. The nature and location of the inflammatory cell infiltrate and fibrosis, as well as the presence of mast cells and alterations of L-tryptophan metabolism, are consistent with findings reported in patients with EMS. This murine model suggests that EBT may have been one of the mediators of EMS and should facilitate studies of the pathogenesis of EMS.

1,1'-Ethylidenebis(tryptophan) (Peak E) induces functional activation of human eosinophils and interleukin 5 production from T lymphocytes: association of eosinophilia-myalgia syndrome with a L-tryptophan contaminant.

This study was designed to clarify the important association between eosinophilia-myalgia syndrome (EMS) and the L-tryptophan contaminant, "Peak E." To determine the functional activation of eosinophils induced by Peak E, eosinophil cationic protein (ECP) release was examined. Peak E augumented the release of ECP from peripheral blood normodense eosinophils by degranulation. Proliferative analysis using the human eosinophilic leukemia cell line EoL-3 showed prominent cellular replication in the presence of Peak E. Moreover, Peak E upregulated interleukin 5 (IL-5) receptor levels on normodense eosinophils. Of particular interest, Peak E-stimulated human splenic T cells produced bioactive and immunoreactive IL-5. Marked induction of IL-5 mRNA in Peak E-stimulated T cells was also shown by reverse-transcriptase polymerase chain reaction (RT-PCR). In contrast, L-tryptophan without the contaminant showed none of these effects. Thus, these data suggest that Peak E might be involved in the pathogenesis of EMS through bimodal mechanism including IL-5 generation by T cells and potentiation of eosinophil functional activation.

Early impressions concerning actinomycetal infections that may play a role in the pathogenesis of eosinophilia-myalgia syndrome (EMS) and other ‘new illnesses’

Actinomycetal infections by Actinomyces, Nocardia, and Streptomyces appear to be increasing in incidence. Clinical and laboratory data from twelve patients believed to have subclinical actinomycete-streptomycete infections (ASI) ∗ ∗ For this paper, the actinomycete-streptomycete combination is used because there are crossovers in the literature as to nomenclature. For example, Streptomyces fradiae is also referred to as Actinomyces fradiae. Generally it is the antibiotic producers (streptomycetes) that are the subject of this paper. are presented. It is proposed that the recent epidemic of eosinophilia-myalgia syndrome (EMS) may have been caused by pre-existing host ASI that generated toxic agents when individuals ingested supplemental l-tryptophan (LT). LT is the substrate used by streptomycetes to synthesize actinomycins, extremely cytotoxic metabolites that could have accounted for symptoms seen in EMS. Actinomycins inhibit CoA activity and interfere with the synthesis and utilization of amino acids. LT also provides streptomycetes with additional NAD, a substance of great importance to their DNA synthesis and metabolic activity. With increased activity, streptomycin, chloramphenicol, adriamycin or any one of the many secondary metabolites (antibiotics) produced by Streptomyces could be endogenously generated in greater quantities. The clinical result would be increased host toxicity. A contaminant that has been isolated from case associated lots of LT may have simply provided additional tryptophan for an ASI. It is also possible that a nucleotide or similar substance in the case associated LT products caused increased activation of tryptophan-2,3-dioxygenase, the rate-limiting enzyme required for the production of NAD and/or actinomycin. Potential reasons for ASI, atypical forms of actinomycete-streptomycete micro-organisms, and the possibility of involvement in other diseases are discussed.

The eosinophilia-myalgia syndrome and eosinophilic fasciitis

The scientific excitement that follows the recognition of a new disease has been reflected in the numerous publications describing the clinical, histopathologic, and pathogenetic aspects of the eosinophilia-myalgia syndrome (EMS) during the period covered by this review. The clinical picture that has emerged during the past 2 years indicates that EMS is a multisystemic disease with prominent cutaneous, hematologic, and visceral manifestations that frequently evolves into a chronic course and can occasionally be fatal. Considerable progress has been made toward understanding the etiology and pathogenesis of EMS. The demonstration of an association with the ingestion of L-tryptophan-containing products originating from a single source has led to the identification and characterization of a putative etiologic agent present as a contaminant in these preparations. Although the accumulation of eosinophils, lymphocytes, macrophages, and fibroblasts in the affected tissues suggests that these cells play important roles in the pathogenesis of EMS, the precise mechanisms of their involvement have not been established. Several studies have demonstrated the activation of eosinophils and the deposition of eosinophil-derived toxic proteins in affected tissues. Fibroblast activation and increased expression of genes coding for various connective tissue macromolecules have been demonstrated employing in situ hybridizations with complementary DNAs. Furthermore, interleukin-5 and transforming growth factor-beta have been implicated as potential mediators in the pathogenesis of EMS. The explosive epidemic of EMS has emphasized the importance of chemical and environmental factors in the development of systemic disorders characterized by chronic inflammation and fibrosis. It is expected that further study of the pathogenesis of EMS will provide valuable information regarding the mechanisms responsible for these obscure disorders.

Effect of synthesized constituents in the L-tryptophan product on the differentiation of eosinophils and the induction of IL-6: A possible cause of eosinophilia-myalgia syndrome

While the pathogenesis of eosinophilia-myalgia syndrome (EMS) remains obscure, the ingestion of L-trypophan (LT) and possibly certain constituents in the LT product might be associated. We investigated the effect of chemically synthesized substances, 1,1′-ethylidene bis[tryptophan] (EBT) and its decomposition product, 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA) recently identified in the implicated LT, on the eosinophil differentiation and the induction of IL-1 and IL-6. EBT and MTCA alone did not support colony formation. However, EBT or MTCA in conjunction with IL-2 induced colony-forming activity containing a small number of eosinophils. In addition, these LT constitutents induced a significant level of IL-6 but not IL-1β in the mononuclear cells from normal volunteers and a patient with hypereosinophilic syndrome. These results suggest that certain constituents of LT product are associated with the pathogenesis of EMS through the induction of colony-stimulating factors and IL-6, hence giving rise to eosinophilia and inflammation.